Elisabetta Comini Brescia University
Pelagia-Irene (Perena) Gouma State University of New York-Stony Brook (SUNY)
Vincenzo Guidi University of Ferrara
Xiao-Dong (XD) Zhang Bose Corporation
V1: Inorganic Materials for Sensing I
Tuesday PM, April 10, 2007
Room 2008 (Moscone West)
9:30 AM - **V1.1
Oxide Nanobelt Based Nanosensors.
Zhong Wang 1 Show Abstract
1 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
10:00 AM - V1.2
FT-IR and Electrical Characterization of Tin-Oxide Nanowires.
Davide Calestani 1 , Sara Morandi 2 , Giovanna Ghiotti 2 , Roberto Mosca 1 , Andrea Zappettini 1 , Mingzheng Zha 1 Show Abstract
1 , IMEM-CNR Institute, Parma Italy, 2 Dip. Chimica I.F.M. and NIS Centre of Excellence, Università di Torino, Torino Italy
Chemical sensors based on Metal Oxide nanowires (NWs) have shown excellent properties. Due to the high surface to volume ratio, high sensitivity was demonstrated . In particular, tin-oxide nanowires show a strong luminescence band, whose intensity depends on the presence of particular gas species, so that an optical sensor was proposed . For the application of SnO2 NWs as chemo-resistive gas sensors the characterization of their electronic and electrical properties is crucial. In this presentation we report about a thorough characterization of tin-oxide nanowires performed by Fourier Transform Infrared Spectroscopy (FT-IR) and electrical techniques.SnO2 nanowires (with diameters in the 30-100nm range) have been grown on alumina substrates by the physical vapor transport technique at a temperature of about 900°C .For the IR analysis, after a pre-treatment at 500°C in vacuum and in dry oxygen, samples underwent treatments in ethanol, CO or NO2 at temperatures up to 500°C. After each treatment the sample was cooled down to room temperature and an absorption FT-IR spectrum was recorded.The IR spectra of the SnO2 NWs show, together with the vibrational absorptions of the test-gas and its decomposition/red-ox products, a very broad electronic absorption with a rather sharp edge at approximately 1600cm-1 (0.20eV) and a maximum at about 2380cm-1 (0.29eV). In agreement with previous findings , we ascribe this absorption to the photo-ionization of mono-ionized oxygen vacancies (VO+ + hν → VO2+ + e- (C.B.)). The intensity of this spectroscopic feature is found to increase with the temperature of the reducing treatment. For the same temperature and gas pressure the electronic absorption is more intense in the presence of ethanol with respect to CO. On the contrary, the effects of an oxidizing gas, such as NO2, are not detectable. It is worth noting that in bulk SnO2 the electronic levels related to mono-ionized oxygen vacancies were determined to lie 0.15eV below the conduction band . In order to verify the respective positions of the electronic absorptions, spectra recorded on SnO2 NWs are compared to those of a SnO2 powder prepared in laboratory by a sol-gel method. The shape of the powder absorption is different from that of nanowires, since the edge is broader and the maximum is located at about 1700cm-1 (0.21eV). Thus the energy level associated to the mono-ionized oxygen vacancy seems to be deeper in the nanowires than in the powder material.Results obtained by FT-IR absorption spectroscopy are compared to those achieved by thermally stimulated current and impedance spectroscopy measurements and discussed with reference to the literature. E.Comini et al., Sens. Actuators B, 111-112(2005), 2 G.Faglia et al., Appl. Phys. Lett., 86(2005), 011923 D.Calestani et al., J. Crystal Growth, 275(2005), e2083 A.Chiorino et al., Sens. Actuators B, 44(1997), 474 S.Samson, C.G.Fonstad, J. Appl. Phys., 44(1973), 4618
10:15 AM - V1.3
Growth and Sensing Property of Aligned Cd1-xZnxS Nanowires Arrays
Shih-Yuan Lu 1 , Yi-Feng Lin 1 , Yung-Jung Hsu 1 Show Abstract
1 Dept. of Chemical Engineering, National Tsing-Hua University, Hsin-Chu Taiwan
Aligned plain CdS and ternary Cd1-xZnxS nanowires arrays were successfully fabricated via a non-catalytic and template-free MOCVD process, and their sensing ability toward tyrosine amino acid was demonstrated. These nanowires were grown on top of a 1μm thick buffer layer formed in-situ on the silicon substrate. The nanowires were with diameter of 20-30 nm and length of 500-700 nm. With increasing deposition temperature from 300 to 400 oC, the composition of the ternary nanowires became more ZnS-rich. A plausible growth mechanism for the nanowires was proposed and discussed. Basically, the morphology of the growing deposit turned from 2-D film to 1-D nanowire because of the drive for higher surface-to-volume ratio morphology caused by the reduction of precursor vapor supply toward the latter stage of the deposition. The X-ray diffraction (XRD) analysis and selected area electron diffraction pattern (SAED) not only confirmed the plain and solid solution nature, but also showed the hexagonal single crystalline structure of the nanowires. The dominant growth direction in the c-axis was also clearly revealed in the XRD patterns. The x values of the ternary nanowires were determined with the energy dispersive spectrum (EDS) data to be 0.21 and 0.44 for the ternary nanowires prepared at the deposition temperatures of 300 and 400oC, respectively. In addition, as evident from the HRTEM images, the nanowires grew along the  direction of the hexagonal crystalline phase of CdS, consistent with the XRD analysis. The PL emission peaks of the nanowires were found located at 535, 498, and 473 nm for the x values of 0, 0.21, 0.44, respectively, all near band edge emissions and demonstrating the color tunability achieved with adjustment of the composition of the ternary nanowires. These nanowires were further demonstrated their sensing ability toward tyrosine amino acid by using photoluminescence intensity and electric resistance of the nanowires as the detecting measure. Tyrosine amino acid was dissolved in phosphate buffer solution (PBS) and the concentration of tyrosine was controlled by changing the amount of PBS. At the tyrosine concentration of 1mM and pH value of 7, the plain CdS nanowires showed better tyrosine sensing properties than that of the ternary nanowires. At the pH value of 7, the amino group (NH3+) of the adsorbed tyrosine scavenged electrons from the nanowire surface to reduce the PL intensity of the nanowires. This same effect also led to an increase in the electric resistance of the nanowires. The incorporation of ZnS, a wider energy band gap material, reduces the free charge carrier concentrations in the ternary nanowires and thus increases the electric resistance of the nanowires. The stronger bonding between Zn and S than that between Cd and S results in less electron scavenging effect produced by the absorbed tyrosine and thus less sensitivity in detection of tyrosine for ternary nanowires.
10:30 AM - V1.4
Low-Temperature Solution Processing of Oxide Nanocrystals and Their Application in the Processing of Improved Chemical Sensors
Mauro Epifani 1 , Jordi Arbiol 2 3 , Elisabetta Comini 4 , Raul Diaz 2 , Eva Pellicer 2 , Pietro Siciliano 1 , Guido Faglia 4 , Joan Morante 2 Show Abstract
1 Istituto per la Microelettronica ed i Microsistemi, CNR-IMM, Lecce Italy, 2 Departament d'Electronica, University of Barcelona, Barcelona Spain, 3 Serveis Cientifico-Tecnics, University of Barcelona, Barcelona Spain, 4 SENSOR Laboratory, CNR-INFM, Brescia Italy
10:45 AM - V1.5
Visible-Range Luminescence Study in Indium Oxide Nanowires
Davide Calestani 1 , Mingzheng Zha 1 , Margherita Mazzera 1 , Laura Lazzarini 1 , Andrea Zappettini 1 , Giancarlo Salviati 1 , Carlo Paorici 2 , Lucio Zanotti 1 Show Abstract
1 , IMEM-CNR Institute, Parma Italy, 2 Dip. Fisica, Università di Parma, Parma Italy
Recently the great potential of metal oxides nanowires (NWs) for gas sensor applications has been studied. SnO2, ZnO, In2O3 were grown in the nanowires form by several research groups and their sensing properties have been tested (e.g. see [1-2]).To understand the sensing mechanism of nanowires-based sensors, the electronic properties and the defects in metal oxide nanowires is currently under investigation. Recently we reported some results concerning the role of oxygen vacancies in SnO2 NWs . In the present study we tried to get some information about the electronic properties of In2O3 nanowires, mainly by mean of an in-depth luminescence characterization of samples prepared in our laboratory.In2O3 nanowires were grown by a vapor transport process, starting from In. The nanocrystals were grown directly on alumina and silicon substrates. Morphological and structural properties have been studied by Scanning and Transmission Electron Microscopy (SEM and TEM) imaging and X-Ray Diffraction techniques. Depending on the growth conditions, the obtained nanocrystals have different thickness, ranging from “wide” 1-2μm nanobelts (rectangular section) to very thin 10-20nm nanowires (round section). They are generally single-crystals and can grow up to several hundreds of μm in length.Though bulk In2O3 cannot emit light at room temperature (RT), we observed that these nanocrystals are characterized by luminescence emission in the visible range.Both Photoluminescence (PL) and Cathodoluminescence (CL) spectroscopy have been performed on the samples, focusing on large areas and on single nanowires respectively. A wide emission band with maximum at about 580nm has been revealed at RT. Studying its line shape it is possible to observe that the band is the convolution of two or more broad peaks. When the temperature is decreased down to 12K, the integrated emission intensity increases and the band maximum shifts to 615nm, probably as a consequence of the different weights of the component peaks. The origin of this band is not yet clear but we are inclined to exclude the role of impurities because the starting material is 6N-pure, it should be further “purified” by the vapour transport process and the emission is independent on the substrate material.At low temperature another emission band appeared at about 430nm, whose integrated intensity also increases by decreasing the temperature. In agreement with literature data we associated this emission to the presence of oxygen vacancies. This hypothesis has been confirmed by an annealing treatment of the samples in an oxygen-rich atmosphere at 1000°C. This “forced oxidation” resulted in a complete suppression of the emission at 430nm.The results are discussed in order to evaluate their influence on the In2O3 NWs properties. Z.W.Pan, Z.R.Dai, Z.L.Wang, Science, 291 (2001), 1947 E.Comini et al., Appl. Phys. Lett., 81 (2002), 1869 R.Mosca et al., Mater. Res. Soc. Symp. Proc., 915 (2006), 0915-R04-06
11:30 AM - **V1.6
Gas Sensors Based on Metal Oxides: What One Can Learn About the Surface Reactions from in-situ Electrical and Spectroscopic Techniques.
Udo Weimar 1 Show Abstract
1 Physical Chemistry, University of Tuebingen, Tuebingen Germany
12:00 PM - V1.7
Aligned ZnO Nanorod Arrays for Sensor Applications.
David Scrymgeour 1 , Clark Highstrete 1 , Yun-Ju Lee 1 , Stephen Howell 1 , Erik Spoerke 1 , Mark Lee 1 , Julia Hsu 1 Show Abstract
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
12:15 PM - V1.8
The Development of Surface Plasmon Resonance Spectroscopy on Conducting Metal Oxides.
Crissy Rhodes 1 , Alina Efremenko 1 , Mark Losego 2 , Jon-Paul Maria 2 , Stefan Franzen 1 Show Abstract
1 Dept. of Chemistry, North Carolina State University, Raleigh, North Carolina, United States, 2 Dept. of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States
Surface plasmon resonance (SPR) spectroscopy is a surface-sensitive optical technique used to characterize adsorbed biomolecules and to monitor biological binding events. This technique is based upon the detection of a shift in the surface plasmon resonance that occurs after the binding event. Plasmon resonance is a general phenomenon observed in all conductors and is a function of the charge carrier density (n) of the material as approximated by the Drude free electron model. This resonance can be observed as a sharp decrease in the intensity of the reflected light at a specific resonant angle. Typically, gold or silver with relatively large n (10^23 electrons/cm^3) have been used as substrates for SPR with detection in the visible spectral region. Consequently, conducting metal oxides (CMO)s with an intermediate charge carrier density of 10^20-10^21 electrons/cm^3 possess a plasmon band in the mid- to near- infrared region. Therefore, in our study, for detection of the SPR effect in the near-IR region a particular CMO of commercial interest has been chosen: indium tin oxide (ITO). This material is transparent in the visible range, and reflective in the IR range, which offers the possibility of multiplexing detection methods. Preliminary experiments have been performed using simple molecules such as hexadecanethiol, as an initial step toward the identification of the binding of biomolecules. In addition, the material properties of ITO have been varied to examine the dependence of the excitation of the SPR peak on these characteristics. ITO films are prepared by RF magnetron sputtering and the film resistivity is controlled by post annealing conditions in an oxygen atmosphere. One particularly insightful study involved the deposition of ITO films with different thicknesses. Within this thickness series, one can elucidate a direct dependence of the SPR effect on the skin depth. Skin depth is a measure of the penetration of an electromagnetic wave at the 1/e attenuation point and is a key factor for determining optimal thickness for various applications including biosensing and field evaluation of conductors. We have shown that in ITO thin films, the theoretical skin depth must be reached for the observance of an SPR effect and further increasing the thickness has additional effects. With the ease of the custom film deposition of ITO, this substrate seems ideal to study the dependence of the SPR effect on various material properties of the surface.
12:30 PM - V1.9
Role of the Synthesis of Nanopowders in the Gas Sensing Behavior of Metal Oxides.
Marco Nagliati 1 , Maria Cristina Carotta 1 , Vincenzo Guidi 1 , Cesare Malagu 1 , Giuliano Martinelli 1 Show Abstract
1 Physics, University of Ferrara, Ferrara Italy
12:45 PM - V1.10
Nerve Agent Simulants Detection By Tin Oxide Nanowires.
Andrea Ponzoni 1 , Camilla Baratto 1 , Sebastiano Bianchi 1 , Elisabetta Comini 1 , Guido Faglia 1 , Matteo Ferroni 1 , Giorgio Sberveglieri 1 Show Abstract
1 Chemystry and Physics Dept., CNR-INFM SENSOR Lab. and Brescia University, BRESCIA Italy
In the last years, metal oxide nanowires appeared as one of the most interesting class of materials due to their peculiar morphological and structural features. Their reduced dimensions, which can be scaled down to the nm-level by properly addressing the synthesis parameters, together with their single crystal shape exhibiting well-defined crystallographic surfaces, allow to investigate properties of meso-scaled materials. Focusing on gas sensing, the reduced dimensions and the single crystal structure are promising properties to develop solid state gas sensors featuring high sensitivity together with improved stability. In this work we synthesized tin oxide nanowires by means of Vapor-Liquid-Solid (VLS) process in a tubular furnace preliminary evacuated at 0.01 mbar. We started from tin oxide powders heated at 1350°C, working at constant pressure of 100 mbar provided by an Ar flux. Nanowires grow on alumina substrates covered with Pt catalyst placed downstream at 300-500 °C. Morphology and crystalline degree of deposited materials have been characterized by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) highlighting they exhibit width ranging from 20 to 200 nm, length up to 200 mm and tetragonal phase.Conductometric gas sensors have been prepared depositing by sputtering Pt electrical contacts on nanowires structures and a Pt meander acting as heating element on the back side of the substrate. Gas sensing tests have been carried out by flow through method in a thermostatic chamber with controlled humidity. Dimethyl methylphosphonate (DMMP) has been chosen as target gas. Its importance in gas sensing field is strongly related to its molecular structure, similar to the Sarin nerve agent molecule. Because of this and its reduced toxicity, DMMP is usually adopted as Sarin simulant in the development of Sarin sensitive devices. Sarin Immediately Dangerous to Life or Health (IDLH) value is 30 ppb, so far DMMP has been tested in the concentration range between 20 and 90 ppb.The DMMP molecule, featuring different methoxy and methyl groups can interact in different ways with tin oxide surface, furthermore at high temperatures it can break resulting in more molecules each interacting separately with the sensitive layer. Poisoning effects are also foreseen because of the presence of P atoms in DMMP that, according to catalysis literature, can produce P2O5 molecules that bond to tin oxide surface and prevent further adsorption. Working temperature and humidity effects have been studied. Results have been compared with response obtained by tin oxide thin films synthesized by sputtering method. Short-term stability (few days) has also been studied and work is in progress to provide longer time stability data. Results highlight that both nanostructures exhibit similar performances in terms of best working temperature and response intensity, but improved stability has been observed with nanowire based devices.
V2: Inorganic Materials for Sensing II
Tuesday PM, April 10, 2007
Room 2008 (Moscone West)
2:30 PM - **V2.1
Multifunctional Chemical Sensors based on Wide Band Gap Materials.
Anita Lloyd Spetz 1 , Kristina Buchholt 1 , Doina Lutic 2 , Michael Strand 2 , Per-Olov Kall 3 , Mehri Sanati 2 , Rositza Yakimova 4 Show Abstract
1 Dep. of Physics, Chemistry and Biology, Applied Physics, Linköping University Sweden, 2 Chemistry, School of Technology and Design, Växjö University Sweden, 3 Dep Physics, Chemistry and Biology, Physical and Inorganic Chemistry, Linköping University Sweden, 4 Dep Physics, Chemsitry and Biology, Material Science, Linköping University Sweden
3:00 PM - V2.2
Spectroscopic and Optical Characterization of nano-WO3 as a Gas Sensing material.
Krithika Kalyanasundaram 1 , P. Gouma 1 , N. Ohashi 2 , H. Haneda 2 Show Abstract
1 Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, New York, United States, 2 , National Institute of Materials Science (NIMS), Tsukuba Japan
There is no clear relation that associates the surface electronic properties of a metal oxide to the selectivity of that metal oxide towards a particular gas.The aim of this paper , therefore is to correlate the surface electronic structure of the metal oxide under study, namely WO3, to its gas sensing behavior. Nanostructured WO3 was prepared by using the sol-gel method and was annealed at two different temperatures (400°C and 515°C) to obtain specific polymorphs in the sensing films. Gas sensing experiments carried out revealed distinct differences in the response patterns between the two sensors. Thermal desorption spectroscopy (TDS), X-ray Photoelectron spectroscopy (XPS), Raman spectroscopy, photoluminescence (PL), and infra-red (IR) measurements were carried out on both of these polymorphs and the results will be discussed in relation to the gas sensing behavior of the metal oxide.
3:15 PM - V2.3
Quasi-1D Organometallic and Metal Oxide Nanostructures as Gas Sensors: Fabrication, Functionalization and Prototype Devices
Andrei Kolmakov 1 Show Abstract
1 Physics, SIUC, Carbondale, Illinois, United States
Quasi 1-D chemiresistors made of metal oxides are close to occupy their specific niche in the real world solid state sensorics. Using single crystal individual nanowires and nanowire mats we have studied their performance in model as well as in real world environments. Along with generic high sensitivity, the major advantage of this kind of sensors with respect to available granular thin film sensors will be their size and stable, predictable and reproducible performance in a wide range of operating conditions. The performance of such a gas sensor and especially its sensitivity is determined by its materials-specific surface chemistry as well as the size and shape of its active element(s). The array of methods which allow one to fabricate, functionalize and characterize chemiresistors will be reported. In particular we have developed and tested experimental approaches to tune sensitivity and selectivity of these sensors as well as implemented new methods to monitor the surface processes on individual nanostructures. In particular, the influence of the bulk doping (with donors) and surface sensitization with catalyst particles Ni, Pd, along with radiation induced defects on the surface reactivity and selectivity were directly demonstrated. The above results were compared with gas sensing performance of the individual organometallic nanowires and 2D weblike films. The CuPc nanostructures exhibit excellent sensitivity and selectivity toward NOx in a wide temperature range. The advantages and challenges related with these organometallic chemiresistors will be discussed. Finally the prototypes of nanowire electronic noses and real world nanowire micromachined devices will be discussed and their characteristics will be demonstrated.
3:30 PM - V2.4
Analysis of Time Constants Associated to the Chemical-Electrical Transduction Processes Using Bottom up Gas Nanosensors Based on Single Metal Oxide Nanowires.
Juan Morante 1 , Francisco Hernandez-Ramirez 1 , Albert Tarancón 1 , Albert Romano-Rodríguez 1 Show Abstract
1 Electronics, University of Barcelona, Barcelona Spain
4:15 PM - **V2.5
Photoluminescence in Nanostructured Materials and Applications to Gas Sensing.
Pasquale Maddalena 1 2 , Stefano Lettieri 2 , Antonio Setaro 2 , Camilla Baratto 3 , Guido Faglia 3 Show Abstract
1 Physical Sciences Dept., University of Naples, Napoli Italy, 2 CRS Coherentia, CNR-INFM, Napoli Italy, 3 SENSOR, CNR-INFM, Brescia Italy
In recent years much attention has been paid on nano-scale materials, because of their peculiar properties. Great efforts have been made in controlling the morphologies of these new structures, in order to tune their physical and optical properties. In particular, the search for nanostructured materials working as all-optical contactless gas sensors awakens great interest because of their potentialities for medical and environmental health purposes.Photoluminescence is an optical phenomenon which is strictly connected to the energy configuration of the material under investigation so that it is dependent on the radiative and nonradiative recombination mechanisms of the photogenerated charges. This is particularly interesting in the study of nanostructured materials since most of them exhibit a strong visible photoluminescence emission even at ambient temperature. Due to the high surface to volume ratio of these materials, charge carriers recombination phenomena are influenced by external conditions (temperature, humidity, surrounding gas) so that photoluminescence properties in controlled ambient can be exploited in view of possible applications in chemical sensing.Indeed, chemical sensing based on photoluminescence quenching in nanostructures, such as metal oxide nanocrystals/nanobelts, has been reported in recent years though the influence of structure defects on the emission process is not yet clear.To better understand the nature of the quenching process, both stationary and time resolved photoluminescence studies have been carried out in semiconducting metal oxide nanocrystals and nanostructured silica. Measurements performed in controlled conditions allow investigation of the role played by the oxygen vacancies as recombination traps in the emission process.
4:45 PM - V2.6
Chemical and Biological Sensors Based Upon Polymer Electronics
Timothy Swager 1 Show Abstract
1 Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
This lecture will describe the conceptual design and optimization of chemical/biological sensors based upon conjugated polymers (CPs) and carbon nanotubes (CNTs). The ability of a CP or CNT to produce amplification in a fluorescence- or resistance-based chemosensor stems from the ability to transport optical excitations or electrical charge, respectively, over large distances. These transport properties provide increased sensitivity over small-molecule chemosensors. By adding new functional diversity, chemoresistive properties have been realized. In fluorescence sensors, the migration of an optical excitation increases the probability of an encounter with an occupied binding site. To impart specificity a variety of molecular recognition schemes, assemblies, and reactions have been employed. Recent applications in biosensory schemes will be discussed.
5:00 PM - V2.7
Integrative Chemistry Portfolio toward Designing Vanadium Oxide Microscopic Fibers and Tuning their Sensors and Mechanical Properties
Celine M. Leroy 1 , Helene Serier 1 , Marie-France Achard 1 , Nathalie Steunou 2 , Jacques Livage 2 , Renal Backov 1 Show Abstract
1 , CNRS-Universite Bordeaux-I, Pessac France, 2 , CNRS-Université Pierre et Marie Curie, Paris France
5:15 PM - V2.8
Gas Sensing Properties of MoO3 Nanoparticles and Nanowires.
Lisheng Wang 1 , Krithika Kalyanasundaram 1 , Perena Gouma 1 Show Abstract
1 Department of Materials Science and Engineering, State University of New York at Stony Brook , Stony Brook, New York, United States
5:30 PM - V2.9
Hydrogen Detection using NEMS Devices Fabricated from Tunable Microstructure Pd-Ta Nanocomposites.
David Mitlin 1 , Chris Gilkison 1 , Kenneth Bosnick 4 , Colin Ophus 1 , Christopher Harrower 1 , Reza Mohammadi 1 , Ken Westra 2 , Zonghoon Lee 3 , Ulrich Dahmen 3 , Velimir Radmilovic 3 Show Abstract
1 Chemical And Materials Engineering and National Institute for Nanotechnology, University of Alberta and NRC, Edmonton, Alberta, Canada, 4 National Institute for Nanotechnology, NRC, Edmonton, Alberta, Canada, 2 Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, 3 NCEM, Lawrence Berkeley National Laboratory, University of California, Berkeley, California, United States
V3: Poster Session: Functional Materials for Chemical and Biochemical Sensors I
Wednesday AM, April 11, 2007
Salon Level (Marriott)
9:00 PM - V3.1
BaZrO3 Thin Films for Humidity Gas Sensors.
XiaoXin Chen 1 , Michael Sorenson 1 , Clayton Butler 1 , Loren Rieth 1 , Mark Miller 1 , Florian Solzbacher 1 Show Abstract
1 , University of Utah, Salt Lake City, Utah, United States
9:00 PM - V3.10
Air Reference Free Miniaturized Oxygen Sensor for Combustion Applications.
John Spirig 1 , Prabir Dutta 1 , Jules Routbort 2 , Dileep Singh 2 Show Abstract
1 Chemistry, The Ohio State University, Columbus, Ohio, United States, 2 , Argonne National Laboratory, Argonne, Illinois, United States
Potentiometric internal reference oxygen sensors are created by embedding a metal/metal oxide within a yttria-stabilized zirconia oxygen-conducting ceramic superstructure. Three metal/metal oxide systems based on Pd, Ni, and Ru are examined. A static internal reference oxygen pressure is produced inside the reference chamber of the sensor at the target application temperature. The metal/metal oxide-containing reference chamber is sealed within the stabilized zirconia ceramic superstructure by a high pressure (3-6MPa) and high temperature (1200-1300dC) bonding method that initiates grain boundary sliding between the ceramic components. The bonding method creates ceramic joints that are pore-free and indistinguishable from the bulk ceramic. The Pd/PdO-based oxygen sensor presented in this study is capable of long-term operation and resistant to the strains of thermal cycling. The current temperature limit of the device is limited 800dC. As the sensor does not require reference gas plumbing there is flexibility in placement of sensors in a combustion stream. Furthermore, the sensor assembly process readily lends itself to miniaturization.
9:00 PM - V3.11
Studies of TiO2 Based Mixed Oxide Thin Film Materials Prepared by Ion-assisted Electron Beam Evaporation for Gas Sensing Applications.
Anurat Wisitsoraat 1 , Elisabetta Comni 2 , Giorgio Sberveglieri 2 , Wojtek Wlodarski 3 , Prayoon Songsiriritthigul 4 Show Abstract
1 Nanoelectronics and MEMS Laboratory, NECTEC, Bangkok Thailand, 2 Sensor Laboratory, University of Brescia, Brescia Italy, 3 School of Electrical & Computer Engineering, RMIT University, Melbourne, Victoria, Australia, 4 , National Synchrotron Research Center, NakhonRatchasima Thailand
TiO2 is one of the most promising gas-sensing materials due to its high temperature stability, and harsh environment tolerance. However, its low electrical n-type conductivity hinders its practical implementation as a conductometric sensor. The addition of foreign atoms into TiO2 host is one of the most effective means to improve its conductivity as well as gas-sensing selectivity. In this report, various TiO2 mixed thin film materials prepared by ion-assisted electron beam evaporation have been studied for gas-sensing applications. First, four TiO2 composites, TiO2-WO3, TiO2-MoO3, TiO2-NiOx, and TiO2-ZnO, are made by thorough mixing of TiO2 powder with WO3, MoO3, NiOx, or ZnO powders with different concentrations ranging from 1% to 20 %. The mixed powders are then compressed into pellets and the compressed materials are electron beam evaporated with oxygen ion-addition to form TiO2 nanocomposite thin film on glass, silicon, and alumina substrates. Chemical, structural, and morphological characterizations have been performed by means of photoemission techniques, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Atomic force microscopy (AFM). After annealing in air at 500 deg C, AFM, SEM, and XRD characterizations reveal that various TiO2 thin films have nanocrystalline structure with fine grain ranging from 10-50 nm. In addition, different surface morphologies have been observed. It is found that MoO3 and ZnO inclusions produces precipitates or bright particles on the surface while no such precipitate is formed on TiO2-WO3 and TiO2-NiOx thin film. Photoemission techniques, including X-ray and Ultraviolet photoemission spectroscopy (XPS and UPS) confirms expected elemental composition of Ti, O and addition elements of W, Mo, Ni, Zn on the thin film surface. Furthermore, the oxidation states of these metallic elements has been identified. Electrical and gas-sensing characterizations toward different gases including acetone, CO, and NO2 have been carried out. From electrical characterization, NiOx addition with sufficiently high concentration has proven to produce p-type semiconducting thin film while WO3, MoO3, and ZnO inclusions result in typical n-type metal oxide semiconductor. The gas-sensing sensitivity, selectivity, and minimum detectable concentration can be effectively controlled by different dopants and doping concentrations. WO3 doped TiO2 thin film showed high sensitivity towards NO2 acetone and ethylene at lower working temperature. In addition, TiO2-MO3 material demonstrated good sensitivity towards CO. But ZnO inlcusion deteriorated sensitivity towards all gases. While p-type NiOx doped TiO2 structure show high sensitivity toward ethanol and acetone with distinct behaviours compared to other n-type TiO2 thin films.
9:00 PM - V3.14
Gold-Tantalum Nanocomposite as Structural Material for Resonant NEMS Biosensing Cantilevers.
N. Nelson-Fitzpatrick 1 , C. Ophus 2 , E. Luber 2 , L. Gervais 1 , D. Mitlin 2 , Z. Lee 3 , V. Radmilovic 3 , U. Dahmen 3 , S. Evoy 1 Show Abstract
1 Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, 2 Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada, 3 National Center For Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States
The application of micro-electro-mechanical-systems (MEMS) and nano-electro-mechanical-systems (NEMS) to chemical and biological sensing has been the focus of substantial work in the scientific and engineering fields. Most MEMS and NEMS devices are fabricated from single crystal or polycrystalline silicon, carbides, nitrides or diamond films, with silicon being the most commonly employed . The selective immobilization of molecular species onto device surfaces is however key to the successful development of any given biosensing platform. One method that has been proposed for the biofunctionalization of NEMS devices is to synthesize thiolized molecules that will bind to a biological system of interest, and to exploit the natural affinity of such molecules for a gold structure that has been deposited onto the device . Such steps however introduce additional fabrication complexities for the realization of the device. It has also been shown that the deposition of metal onto a dynamic NEMS device significantly degrades the quality of its resonance . Nanomechanical resonating biosensors could alternatively be machined directly out of a gold material, allowing the direct use of thiol-based chemistry for their biofunctionalization. Metallic materials have however mostly been overlooked given their limited stiffness and hardness, as well as the challenge associated with the nanomachining of a traditionally polycrystalline system. To that end, we have synthesized a series of nanocomposite alloy films of Gold-Tantalum at different stoichiometries using a co-sputtering method. These Au-Ta films feature significantly reduced grain size, as low as 40nm average diameter for a 400nm-thick film, and a roughness of less than 1nm RMS. Additionally, we were able to tune intrinsic stress and control the elastic modulus by varying the Ta concentration in the alloy. All these mechanical and physical improvements were achieved without the loss of the film’s affinity towards thiolized molecules. We have fabricated a series of resonant ultra-thin resonant cantilevers with lengths ranging from L = 1 to 8 um, widths ranging from W = 400 to 800nm, and a thickness of T = 50nm out of low stress Au-Ta (5at. % Ta). These devices possessed resonant frequencies ranging from f = 500 kHz to 10 MHz. From these results, we extracted a root of modulus to density ratio of (E/ρ)^0.5 = 2490 m/s. We will present a full description of the mechanical properties of this alloy as function of its composition. We will also present preliminary results on the binding of thiolized self-assembled monolayers and bacteriophages onto these ultra-thin Au-Ta cantilevers. D. W. Carr, S. Evoy, L. Sekaric, J. M. Parpia, and H. G. Craighead, Appl. Phys. Lett. 75, 920 (1999). B. Ilic, S. Krylov, W. Senaratne, C. Ober, P. Neuzil, and H. G. Craighead, J. Appl. Phys. 95, 3694 (2004).  L. Sekaric, D.W. Carr, S. Evoy, J.M. Parpia, HG Craighead Sens & Act. A 101, 215 (2002).
9:00 PM - V3.16
Conjugated Polyelectrolyte Sensors
Kirk Schanze 1 Show Abstract
1 Chemistry Department, University of Florida, Gainesville, Florida, United States
9:00 PM - V3.17
One-dimensional Photonic Crystals Based on Functional Ordered Mesoporous Films.
Hernan Miguez 1 , Maria Cecilia Fuertes 2 , Francisco Javier Lopez-Alcaraz 1 , Galo Soler-Illia 2 , Paula Angelome 2 , Victor Luca 3 Show Abstract
1 Institute of Materials Science of Seville, Spanish Research Council, Sevilla Spain, 2 Centro Atómico Constituyentes, Comisión de Energía Atómica, San Martín Argentina, 3 , Institute of Materials and Engineering Sciences, Lucas Heights, New South Wales, Australia
9:00 PM - V3.18
Thermal and Mechanical Stability of Directly Deposited, SiO2-doped SnO2 Sensor Layers
Antonio Tricoli 1 , Sotiris Pratsinis 1 Show Abstract
1 Particle Technology Laboratory, Mechanical and Process Engineering, ETH Zurich, Zurich Switzerland
Direct deposition of nanoparticles on sensor substrates avoids the tedious steps of standard routes of wet synthesis of nanoparticles and their slurry or paste deposition and subsequent solvent evaporation and calcinations that frequently results in layers with non-reproducible sensor performance because of cracks and other imperfections during layer synthesis. Despite their promise, direct deposition techniques suffer from limited layer adhesion and cohesion to the substrate stemming from their high porosity. This defect prevents the immediate scale-up and compatibility of direct deposition techniques with CMOS technology for manufacture of sophisticated sensors. Here, lacy, nanostructured, pure or SiO2-doped SnO2 layers of high porosity (98%) are self-assembled on SiO2 or SiN substrates. Doping with SiO2 is investigated by morphological and thermal stability analysis by BET, XRD, HR-TEM, STEM and EDXs. The SiO2 presence reduced thermally-induced growth up to 900 °C, stabilizing crystal size at 18 and 7 nm respectively by 0.8 and 8 wt % while preserving sensor high sensitivity. Preliminary experiments on SnO2/SiO2 nanomaterial synthesis revealed formation of crystalline SnO2 and well dispersed amorphous SiO2. Addition of SiO2 strongly increased SnO2 thermal stability already at 0.8 wt % due to the good SiO2 dispersion. Increasing SiO2 mass up to 8 wt % did not produced fully coated SnO2 particles preserving the SnO2 nanoparticles’ good sensitivity. Functionalization with SiO2 is particularly promising for sensor application in harsh environments, granting good sensor material stability at high sensitivity. Estimation of layer adhesion is quantitatively determined by measuring the area cleared below N2 jet gas and water impingement test experiments. The sensor performance is established for CO and ethanol (EtOH).
9:00 PM - V3.19
A Facile Synthetic Route to Produce Indium Oxide Nanostructures.suitable for gas sensor applications
Dae Joon Kang 1 2 3 , Jimin Du 1 2 3 Show Abstract
1 Physics , Sungkyunkwan University, Suwon Korea (the Republic of), 2 SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon Korea (the Republic of), 3 Institute of Basic Science, Sungkyunkwan University, Suwon Korea (the Republic of)
9:00 PM - V3.20
Control of Cell Adhesion Using Conducting Polymers
Maria Bolin 1 , Karl Svennersten 2 , Emilien Saindon 1 , Agneta Richter-Dahlfors 2 , Magnus Berggren 1 Show Abstract
1 Organic Electronics, Science and Technology, Linköping University, Norrköping Sweden, 2 Department Of Microbiology, Tumor and Cell Biology , Karolinska Institutet, Stockholm Sweden
Petri dishes of polystyrene and plastic foils were coated with the conducting polymer PEDOT (poly (3, 4-ethylenedioxythiophene)), via an all-liquid chemical polymerisation process including iron (III) tosylate as the counter ion. The polymer surface is then subtractive patterned to form adjacent electrodes using over-oxidation as the patterning technique. This enables us to exclusively address and reduce one PEDOT-electrode while the other is oxidized and cell media serve as the electrolyte. We have investigated how cells adhere, grow and differentiate onto the two electrodes while they are biased with an appropriate electric signal. Epithelial MDCK cells have been seeded on the surfaces on both pristine PEDOT surfaces and on pre-switched surfaces. We find that cells that were seeded on a pre-switched surface and incubated showed a distinct difference of adhesion and growth character on the two different electrodes, depending on the bias voltage. The cells prefer to adhere to the reduced side while hardly any cells were found on the oxidized electrode. We also found that cells that initially adhered to the reduced side starts to release when the surface was switched from the neutral state to the oxidized side. The surfaces can be switched reversibly to generate full adhesion-release cycles of the cells. Electrochemically active surfaces can be included in electrochemical devices, such as transistors. Our findings open for complex circuits carrying surface switches that allow us to, via electronic x-y-addressing control the cell adhesion and growth along large surfaces. Such “smart” surfaces can be used to guide cell growth to form desired tissue formation, to control cell culturing in general, to electrically control the release of large cell membranes etc.
9:00 PM - V3.21
Plasma Polymer Nanocoatings as Responsive Materials for Ultrasensitive Sensor Platform.
Srikanth Singamaneni 1 2 , Melburne LeMieux 4 , Michael McConney 1 2 , Yen-Hsi Lin 2 4 , Hao Jiang 3 , Jesse Enlow 3 , Timothy Bunning 3 , Vladimir Tsukruk 2 1 Show Abstract
1 Polymer, Textile and Fiber Engineering, Geogia Institute of technology, Atlanta, Georgia, United States, 2 School of Materials Sceince and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States, 4 Department of Materials Science and Engineering, Iowa State University, Ames, Iowa, United States, 3 Materials and Manufacturing Directorate, Air Force Research Laboratory, Wight-Patterson Air Force Base, Ohio, United States
9:00 PM - V3.22
Polymer Nanocomposite Based Chemiresistive Gas Sensors.
Divakara Atchuta Meka 1 , Shalini Prasad 1 , Linda George 2 Show Abstract
1 Electrical and Computer Engineering, Portland State University, Portland, Oregon, United States, 2 Environmental Science, Portland State University, Portland, Oregon, United States
9:00 PM - V3.23
Immobilization of Glycine and its Oligomers on Aldehyde-terminated Surfaces and its Influence on the Orientation of Liquid Crystals.
Kun-Lin Yang 1 , Xinyan Bi 1 Show Abstract
1 Chemical and Biomolecular Engineering, National University of Singapore, Singapore Singapore
9:00 PM - V3.25
Cross Conjugated Water Soluble Poly (para-phenylenes): Towards the Versatile Chemo- and Biosensors.
Hairong Li 1 , Suresh Valiyaveettil 1 Show Abstract
1 , National University of Singapore, Singapore Singapore
9:00 PM - V3.27
Microphotonic Cylinderical Waveguide Based Protein Biosensor
Vijay Sekhar Reddy Kovvuri 1 , Sudhaprasanna Kumar Padigi 1 , Kofi Kasaante 2 , Andres LaRosa 2 , Shalini Prasad 1 Show Abstract
1 Electrical and Computer Science, Portland State University, Portland, Oregon, United States, 2 Physics, Portland State University, Portland, Oregon, United States
9:00 PM - V3.28
Characterization of the Transient Response of Amperometric Electrochemical Microsensors
Jin Zou 1 , Mark Wagner 1 Show Abstract
1 , Sensorcon, Inc., Reading, Massachusetts, United States
Micromachining technologies offer the potential to reduce the cost and increase the performance of amperometric sensors for toxic gases such as NO2. The sensitivity and response rate of these sensors are dependant upon mass transport phenomenon, which is governed by the geometry and permeability of the materials used. We have demonstrated a new amperometric microsensor technology that uses deposited catalyst films and aqueous electrolytes for improved performance, and have developed a multiphysics numerical method for characterizing its transient response.Earlier work on similar sensors used PVD films on Nafion sheets, and identified the electrode perimeter/area ratio as a key contributor to the signal/noise ratio . Common methods to improve sensitivity by using high surface area nanomaterials on the electrode can increase current output, but do not necessarily increase the signal/noise ratio. Previous models which are based primarily on observation only consider the diffusion effects of a sensor membrane, and do not couple the effects of mass consumption due to the electrochemical reaction . The principle of operation of amperometric sensors is based upon the reduction or oxidation of the gas when it comes into contact with the electrode-electrolyte interface. This implies that the gas must transport through an electrolyte film to the electrode surface before it can react. Therefore, aqueous electrolytes are advantageous because they offer both high permeability and high ion conductivity. However, since it is difficult for micromachined gas sensors to accommodate liquid materials, most recent research efforts have focused on solid state solutions, which are often not based on traditional electrochemical methods [3, 4]. In order to accommodate liquid based electrolytes, these sensors must be integrated with packaging [5, 6].This paper reviews our effort to characterize a new type of electrochemical microsensor for NO2. MEMS processing methods are used to create a sensor structure which is compatible with aqueous electrolytes. We present a multiphysics based numerical method which couples multi-step diffusion and electrochemical consumption, by coupling Fick’s law with Faraday’s laws to better characterize the time dependant transient response of the sensor. Experimental tests of the sensor verify the accuracy of the model. References: G. Jordan Macclay, William J. Buttner, and Joseph R. Stetter, IEEE Transactions on Electron Devices, Vol. 35, No. 6, pp793-799 June 1988  Si-Chung Chang and Joseph R. Stetter, Electroanalysis, 2 359-365, 1990 X.Z. Ji, A. Zuppero, J. Gidwani, And G. Somorjal, Nano Letters, Vol 5, No.4, 753-756, 2005 Xiao Z. Ji and Gabor A. Somorjai, J. Phys. Chem. B, 109, 22530-22535, 2005 R.L. Smith and S.D. Collins, IEEE Trans. Electron device, Vol. 35, No. 6, PP.782-792, 1988 D.L. Polla, Richard Muller, Richard White, IEEE Electron Device lett., Vol. 7 No4, pp254-256, 1986
9:00 PM - V3.3
Designing Chemo-Sensors based on Charged Derivatives of Gramicidin A
Ricardo Capone 1 , Steven Blake 2 , Thomas Mayer 1 , Marcela Rincon Restrepo 1 , Jerry Yang 2 , Michael Mayer 1 Show Abstract
1 Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States, 2 2Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, Colorado, United States
Chemical changes of charge at the entrance of modified gramicidin A (gA) pores can be used to monitor chemically reactive agents with sensitivity up to individual molecules Ref. Here, we discuss the relevant parameters to optimize the sensitivity of such ion channel-based sensors. In order to design an effective sensor that measures changes in charge of a gramicidin A pore, the following conditions should be fulfilled: 1) the synthesis of the sensor (i.e. the derivative of gA) should be simple, practical, and start from readily accessible molecular building blocks; 2) the charge should be placed as close to the entrance of the pore as possible to achieve high sensitivity; 3) the total charge on the gA derivative should be well-defined within the operational pH range; 4) the ionic strength of the recording buffer should be as low as possible while maintaining a detectable flow of cations through the pore (≤ 0.1 M); 5) the applied transmembrane voltage should be a high as possible (> 100 mV); 6) the lipids in the supporting membrane have to be charged differently than the derivative of gA to avoid shielding; and 7) folded bilayers as opposed to painted bilayers should be used. Measuring the single channel conductance of gA derivatives under these optimized conditions showed that, the difference in ion channel conductance of neutral and negatively charged derivatives of gA depends only on the charge at the entrance of the pore; it does not depend on the charge at the exit of the pore. This asymmetric characteristic opens the possibility to design bi-functional sensors that detect the presence or absence of a charge on each monomer of a functional gA pore independently.
9:00 PM - V3.4
Integrated Optical Sensing with Desorption Ionization Mass Spectrometry on Chemically Modified Porous Silicon Photonic Crystals
Kristopher Kilian 1 , Russel Pickford 3 , Suhrawardi Ilyas 2 , Katharina Gaus 4 , Michael Gal 2 , Michael Guilhaus 3 , J. Justin Gooding 1 Show Abstract
1 School of Chemistry, University of New South Wales, Sydney, New South Wales, Australia, 3 Bioanalytical Mass Spectrometry Facility, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia, 2 School of Physics, University of New South Wales, Sydney, New South Wales, Australia, 4 Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
New methods in mass spectrometry employing solid substrates that assist ionization show promise for small molecule profiling in biology and medicine. Desorption ionization on porous silicon (DIOS) mass spectrometry in particular has been widely utilized owing to a high surface area and matrix-free ionization. Porous silicon based photonic crystals have been used extensively as biosensing transducers but no reports on their integration into DIOS applications have been made. In this work we show detection of peptides on two different optical crystals, microcavities and rugate filters. The structure and optical properties of the crystals are easily tuned during fabrication by modifications to the applied current density, yielding a mesoporous scaffold that exhibits a resonance in the reflectivity spectrum upon incident light irradiation. Introduction of peptides results in a change in the resonant reflectivity position proportional to the change in refractive index. The ionization of peptides from the porous materials is shown to depend on both the nanostructure and surface chemistry. Two different chemical strategies, employing alkene hydrosilylation were compared for their effect on peptide ionization and detection sensitivity. Hydrophobic monolayers were found to yield greater sensitivity to peptide compared to hydrophilic layers. The thickness of the porous structure was found to be critical in the ability of peptide to be ionized in the absence of matrix. The integration of silicon-based photonic sensors with mass spectrometry will enable optical detection of captured molecules and subsequent quantitative analysis, eliminating sample processing steps and providing “smart” analytical components.
9:00 PM - V3.8
Optical Resonant Cavity to Detect Chiral Media.
Riccardo Milan 1 2 , Vincenzo Guidi 1 3 , Sergei Atutov 1 3 Show Abstract
1 Dept. of Physics, University of Ferrara, Ferrara Italy, 2 National Laboratory of Legnaro, INFN, Legnaro (PD) Italy, 3 , INFN, Ferrara Italy
Elisabetta Comini Brescia University
Pelagia-Irene (Perena) Gouma State University of New York-Stony Brook (SUNY)
Vincenzo Guidi University of Ferrara
Xiao-Dong (XD) Zhang Bose Corporation
V4: Biosensors and Hybrid Sensors I
Wednesday AM, April 11, 2007
Room 2008 (Moscone West)
9:45 AM - **V4.1
Development of Polymer-based Sensors for Detection of Sulfur Dioxide at ppm-Level Concentrations.
Margaret Ryan 1 , Charles Taylor 1 , Abhijit Shevade 1 , Adam Kisor 1 , Shao-Pin Yen 1 , Margie Homer 1 Show Abstract
1 , Jet Propulsion Laboratory, Pasadena, California, United States
The electronic nose (ENose) under development at the Jet Propulsion Laboratory uses an array of polymer-carbon black composite sensors to monitor spacecraft cabin air quality in near-real-time. Earlier generations of the JPL ENose have been successfully tested using a variety of organic analytes, as well as ammonia and hydrazine . The next generation ENose is currently under development for demonstration on-board the International Space Station in 2008. For this application, sulfur dioxide has been added to the target compound list owing to crew health considerations. Sulfur dioxide is a potential contaminant in the breathing air from lithium-thionyl chloride batteries used to power equipment in the crew habitat on ISS, and is toxic at ppm-level concentrations. NASA has set a monitoring target of 1 ppm at atmospheric pressure for this demonstration. In developing sensors with a sensitivity toward SO2, the ENose team has used a combination of molecular modeling and experimental approaches. In modeling, the methodology adopted involves calculating binding energies of SO2 with common classes of organic structures using quantum mechanical methods. These organic structures represent functional groups on polymers which may be used as the basis for polymer-carbon composite sensors. Binding energies indicate a candidate for SO2 detection would be a polymer containing amine functional groups. Reversible SO2 absorption by polymers has been previously reported in the literature [2-4]. Literature information combined with modeling led to the use of novel polymer-carbon black films for sulfur dioxide detection at low ppm-level concentrations.We selected two polymers to investigate, derivatives of linear and cross-linked poly-4-vinyl pyridine (P4VPY) and vinyl benzyl chloride (VBC) functionalized with various free-amine containing substituents. This paper will consider the response of polymer-carbon composite films to SO2 and to other chemical species of interest to NASA for crew habitat monitoring. When preparing new materials, variables that must be investigated include: sensitivity, selectivity reversibility, and ability of sensors to be regenerated after exposures to SO2. In order to screen candidate materials, experiments were carried out using microarrays with interdigitated electrodes and embedded heaters, as well as microhotplate sensors. The use of this sensing approach assisted with optimization of sensing parameters such as operating and regeneration temperatures, and carbon-black loading. M.A. Ryan, et al., IEEE Sensors Journal, 4, (3) 337-347, 2004. A. Diaf, J.L. Garcia and E.J. Beckman, Journal of Polymer Science, 53, 857-875, 1994. M. Matsuguchi, et al., Sensors and Actuators B-Chemical, 77, 363-367 (2001). E. Ranucci, et al., Polymers for Advanced Technologies 7, 529-535 (1996).
10:15 AM - V4.2
Chemical Sensing Properties of Poly(methyl metacrylate)- TiO2 Nanocomposites.
Gabriella Leo 1 , Annalisa Convertino 1 , Marinella Striccoli 2 , Michela Tamborra 3 , Corrado Sciancalepore 3 , Maria Lucia Curri 2 , Angela Agostiano 3 2 Show Abstract
1 ISMN, CNR , Monterotondo Staz. (Roma) Italy, 2 IPCF - sez. Bari, CNR, Bari Italy, 3 Dipartimento di Chimica, Università di Bari, Bari Italy
The growing demand of our society to detect and monitor gases and vapors for safety, health and environmental issues requires a high degree of innovation in sensor technology, which includes both the research development of novel sensing materials and the integration of original sensor architectures. Particular attention has been devoted to polymers as sensing materials for devices exploiting various transduction signals, such as optical, mechanical, electrical and thermal. Some recent results show that the presence of inorganic nanoparticles (NPs) causes a further modification of the sorption processes in a polymer matrix . Indeed the interaction between the NP surface and the gas molecules can control the selectivity, rate and efficiency, of molecule adsorption in the nanocomposite. In addition, the high surface-to-volume ratio of NPs increases the number of active sites for interaction with the analytes. Hence, NP based polymer composites can address an innovative generation of chemical sensors combining the sensing abilities and the possibility of a versatile tailoring of the physical properties of the NP with the mechanical and/or optical responses related to the gas sorption processes of the polymers.In this work the sensing properties of Poly(methyl metacrylate) (PMMA) based nanocomposite have been investigated as a function of the shape (dot or rod), concentration and surface ligands (oleic and phosphonic acid) of the embedded TiO2 NPs. Colloidal chemical routes have been used to synthesize the TiO2 NPs with a high control on size, shape and crystal phase. The surface chemistry of the NPs has been modified by exploiting ligand exchange techniques. Thin films of TiO2 NP-PMMA nanocomposite deposited by spin coating on Si and glass substrates, have been investigated by Vis-NIR spectrophotometry in presence of organic vapors (acetone, ethanol). Films of PMMA composites based on commercial TiO2 NPs have also been prepared as comparison. The effects of the surrounding vapors on the nanocomposite thin films have been tested by reflectance measurements in the visible. The vapor sensing behavior of the PMMA nanocomposite have been estimated by measuring the degree of swelling, Dt/t, where t is the thickness of the film and Dt is the relative thickness variation, from the reflectance spectra measured before and after the vapor exposure. Indeed, when the organic vapors are adsorbed by the polymer matrix, a reversible shift of the fringe pattern has been observed in the reflectance spectra for the nanocomposite films due to the reversible film swelling. The overall results have indicated that, the different shape of the embedded NPs and the presence of the organic molecule layer coordinating the surface of the TiO2 NPs appear to be critical in the sensing process, by enhancing or inhibiting the swelling phenomenon of the nanocomposite, and by modifying the response time of the PMMA. A. Convertino et al. Adv. Mater. 13, 1103, (2003).
10:30 AM - V4.3
Porous Silicon Microcavity Coupled with Fluorescence Polymer as a Sensor for the Detection of Explosives
Igor Levitsky 1 2 , William Euler 2 , Natalia Tokranova 3 , Aimee Rose 4 Show Abstract
1 , Emitech, Inc., Fall River, Massachusetts, United States, 2 Chemistry, University of RI, Kingston, Rhode Island, United States, 3 , College of Nanoscale Science and Engineering, University at Albany (SUNY), Albany, New York, United States, 4 , ICx-Nomadics, Cambridge, Massachusetts, United States
10:45 AM - V4.4
Towards poly(3,4-ethylenedioxythiophene)s-based Sensors: Conductimetric Responses in Aqueous Solutions.
Hsiao-hua Yu 1 , Emril Ali 1 , Hong Xie 1 , Shyh-Chyang Luo 1 , Jackie Ying 1 Show Abstract
1 , Institute of Bioengineering and Nanotechnology, Singapore Singapore
11:30 AM - **V4.5
Recent Advance on Chemical and Bio Sensors Using Oxide Nanowires and Carbon Nanotubes
Chongwu Zhou 1 Show Abstract
1 Dept. of Electrical Engineering, University of Southern California, Los Angeles, California, United States
In this talk I will present our recent advance on the chemical and biosensing applications of nanowires and carbon nanotubes. Single-crystalline oxide nanowires such as In2O3 and SnO2 were synthesized using a generic laser ablation method, and field effect transistors with on/off ratios as high as 104 were fabricated based on these nanowires. Furthermore, we have integrated nanowire chemical sensors with micromachined hotplates fabricated atop a silicon nitride membrane. This chemical sensor chip can be easily heated up to 400 degree and therefore allowed the study of chemical sensing at elevated temperatures. In2O3 nanowire sensors made this way exhibited good response to a variety of chemicals including ethanol, CO and hydrogen. Our devices exhibited significantly improved chemical sensing performance compared to existing solid-state sensors in many aspects such as the sensitivity, the selectivity, the response time and the lowest detectable concentrations. In addition, we have combined both In2O3 nanowires and carbon nanotubes for complementary detection of various biospecies important for biomedical research and environmental studies. One particular example is the detection of prostate specific antigen, an important biomarker for prostate cancer. While In2O3 nanowires showed enhanced conduction upon exposure, carbon nanotube transistors showed reduced conduction, as a result of the opposite polarity of carriers in these nanostructures. We have further developed a selective functionalization technique based on electrochemical activation and reduction between hydroquinone and quinine. This technique allowed us to functionalize an array of biosensors with different probe molecules, an important step toward the construction of biosensor chips. Our work clearly demonstrates the potential of one-dimensional nanostructures to work as high-performance
12:00 PM - V4.6
Chemical Vapor Sensing with Novel Coupled Channel Organic Semiconductor and Silicon Field-Effect Devices.
Deepak Sharma 1 , Shannon Lewis 1 , Sebastian Schoefer 1 , Ananth Dodabalapur 1 , Myung Yoon 2 , Antonio Facchetti 2 , Tobin Marks 2 Show Abstract
1 Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas, United States, 2 Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois, United States
We report the characteristics of a new hybrid sensor device that combines the functional properties of silicon field-effect devices with unique properties of organic semiconductors and novel self-assembled dielectrics. The four-terminal field effect device has two channels: one formed in an organic semiconductor (p) and the second in silicon (n). Both the channels are coupled so that one channel gates the other. The organic channel is exposed to air and interacts with the chemical vapor present in the ambient. The device can operate as a traditional CHEMFET as well as an organic TFT based sensor. Another sensing mode, which is most sensitive, is designated as the chemical memory mode. In this unique mode of operation, the device operates in a manner akin to a non-volatile memory in which the write function is provided by the chemical analyte. The erase is done electrically by reverse biasing the device. In previous work, we reported on sensing characteristics of such devices with a thermally grown SiO2 gate insulator coupling the two channels1. In the present work, we couple the two channels through a high-k self assembled organosilane dielectric grown at Northwestern University. The relative dielectric constant is about 16. The typical thickness of this dielectric film is about 1.5-4 nm. This dielectric has recently demonstrated excellent properties in field-effect devices and combined a high dielectric constant, low leakage currents, and compatibility with a range of organic and inorganic semiconductors2. In the chemical memory sensor mode, the n-channel is biased on while keeping the p-channel off and the n-channel current is measured with time. Subsequently, both the channels are biased on and conducting and analyte is delivered to the exposed pentacene layer. Following this, the n-channel current is measured again at the biasing condition prior to analyte delivery. The current increases by a a factor of about 5. This indicates a decrease in the threshold voltage (VT) due to the hole trapping in the organic channel after the interaction with analyte. In these sensors we are essentially using trapped charges as the “non-volatile” gate charge. The charge retention requirements of the sensor are much less than that of a normal non-volatile memory. The reset mechanism is very similar– electrical reverse bias based resetting. The chief difference with established silicon CHEMFET technology is that CHEMFETs use channel charge modulation by dipoles (which have a net charge of zero) whereas in our device we use trapped positive charges which will obviously produce a much greater conductivity and capacitance modulation.1. D. Sharma, L. Wang, D. Fine, and A. Dodabalapur, IEDM Technical Digest, 2005.2. Myung-Han Yoon, Antonio Facchetti, and Tobin J. Marks. Molecular Dielectric Multilayers for Ulta-Low-Voltage Organic Thin Film Transistors, MRS Symposium Proceedings, 2005, 871E, I3.2.1-I3.2.6.
12:15 PM - V4.7
Molecularly Imprinted Polymer-Based Immunoassay of Herbicide Acids Using Resonant Piezoelectric Membranes with Integrated Actuation and Read-Out Capabilities.
Cedric Ayela 1 , Fanny Vandevelde 2 , Karsten Haupt 2 , Nicu Liviu 1 Show Abstract
1 Nanobiotechnology Department, LAAS CNRS, Toulouse France, 2 , Universite de Technologie de Compiegne, Compiegne France
12:30 PM - V4.8
Poly (3-hexylthiophene)-ZnO Nanocomposites For Novel Organic –Inorganic Hybrid Sensor.
Camilla Baratto 1 , Guido Faglia 1 , Giorgio Sberveglieri 1 , Massood Atashbar 2 , Erika Hrehorova 2 Show Abstract
1 Chemistry and Physics, INFM-CNR & University of Brescia, Brescia Italy, 2 Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan, United States
12:45 PM - V4.9
Electrode Arrays of Carbon Nanofibers for Biosensing at Single Molecular and Cellular Levels
Jessica Koehne 1 2 , Hua Chen 3 , Alan Cassell 4 , Barbara Nguyen 1 , M. Meyyappan 1 , Gang-yu Liu 2 , Jun Li 1 Show Abstract
1 NASA Ames Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California, United States, 2 Chemistry, University of California, Davis, Davis, California, United States, 3 NASA Ames Center for Nanotechnology, ELORET Corporation, Moffett Field, California, United States, 4 NASA Ames Center for Nanotechnology, University of California, Santa Cruz, Moffett Field, California, United States
Carbon nanofibers (CNFs) are highly conductive and robust materials with high aspect ratios. Their unique properties and intriguing nanostructure can be employed to develop new tools to interrogate biomolecules and cells at nanoscale. Here, we report two studies using vertically aligned CNFs. First, a reliable nanoelectrode array (NEA) based on vertically aligned CNFs embedded in SiO2 is used for ultrasensitive DNA detection. Characteristic nanoelectrode behavior is observed using low-density CNF arrays for measuring both bulk and surface immobilized redox species such as K4Fe(CN)6 and ferrocene derivatives. The open-end of CNFs presents similar properties as graphite edge-plane electrodes with wide potential window, flexible chemical functionalities, and good biocompatibility. Oligonucleotide probes are selectively functionalized at the open ends of the nanofiber array and specifically hybridized with oligonucleotide targets. The guanine groups are employed as the signal moieties in the electrochemical measurements. Ru(bpy)32+ mediator is used to further amplify the guanine oxidation signal. The hybridization of subattomoles of PCR amplified DNA targets is detected electrochemically by combining the CNF nanoelectrode array with the Ru(bpy)32+ amplification mechanism. Second, the SiO2 matrix was etched back using a plasma process to produce needle-like protruding nanoelectrode arrays. This platform can be used towards biosensing at the single cell level by penetrating fibers into cells for investigating gene transfection, electrical stimulation and detection of cellular processes Extensive confocal microscopy measurements will be present to verify the viability of PC12 neural cells upon CNF impaling, as well as determining the location of the CNFs. Our goal is to take the advantage the nanostructure of CNF arrays for unconventional biomolecular studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.
V5: Biosensors and Hybrid Sensors II
Wednesday PM, April 11, 2007
Room 2008 (Moscone West)
3:00 PM - **V5.1
Plasmonics for Chemical and Biochemical Sensing: New Geometries, Spectroscopies, and Interfaces.
Naomi Halas 1 Show Abstract
1 , Rice University, Houston, Texas, United States
3:30 PM - V5.2
Virus Assay Using Antibody-Functionalized Peptide Nanotubes
Robert MacCuspie 1 , Phillp Krause 2 , Hiroshi Matsui 1 Show Abstract
1 Chemistry, City University of New York, Hunter College, New York, New York, United States, 2 Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, United States
Robust trace-level detection of viruses is crucial to meet urgent needs in fighting the spread of disease or detecting bioterrorism events. Here, we introduce a method for rapid and highly sensitive detection of viruses utilizing fluorescent antibody nanotubes. When each virus (adenovirus, HSV-2, influenza B, and vaccinia) was mixed with antibody nanotubes in solution, we observed that these nanotubes rapidly aggregated around the viruses to form a networking structure. Light scattering also revealed that the size of the aggregates increased as the concentrations of viruses increased. Trace amounts of these viruses were detected on attomolar order by changes in fluorescence and light scattering intensities of the aggregated dye-loaded antibody nanotubes around viruses by flow cytometry, which was used to simultaneously detect the light scattering and the fluorescence and to separate signals from unbound nanotubes, which otherwise were sources of background interference. A typical limit of detection for this assay was determined to be on the order of 102 pfu/mL by creating standard curves between the integrated fluorescence intensities of the nanotube-virus aggregates and the added virus concentrations. These standard curves also allowed us to quantify viral concentrations based on their fluorescence intensities. The increased size of the nanotube-virus aggregates resulted in an increase of their fluorescence intensities, since more antibody nanotubes are contained in the larger aggregates, consistent with our observation of a linear correlation between the integrated fluorescence intensities of aggregates and the concentrations of viruses on a log scale. High specificity of anti-HSV-2 nanotube toward the targeted virus was also demonstrated by quantifying the concentration of HSV-2 in mixed solutions of HSV-2 and SV-40. Typically, we obtained the fluorescence data through flow cytometry in under five minutes, and with standard curves previously prepared, the overall process takes only 30 minutes from receipt of the sample in the lab until the final quantitative data are ready. If the gating protocols for the fluorescence-FCS intensity distribution and standard curves between integrated fluorescence intensities of the nanotube-virus aggregates and virus concentrations are prepared for targeted viruses in advance, this nanotube assay can be rapidly applied to determine viral concentrations in unknown samples. This antibody nanotube assay could complement other existing viral assays such as PCR, which detects virus structures rather than nucleic acids, and this feature makes the antibody nanotube assay more versatile in the detection of a variety of viruses
3:45 PM - V5.3
Nanospring –Based Biosensors for Electrical DNA Microarrays.
David McIlroy 1 , James Nagler 2 , Larry Branen 3 , Joshua Branen 3 , Giancarlo Corti 1 , Lidong Wang 1 , M. Norton 4 Show Abstract
1 Physics, University of Idaho, Moscow, Idaho, United States, 2 Biological Sciences, University of Idaho, Moscow, Idaho, United States, 3 Food Science and Toxicology, University of Idaho, Moscow, Idaho, United States, 4 Mechanical and Materials Engineering, Washington State University, Pullman, Washington, United States
It is well known that nanomaterials have unique surface properties that make them attractive for biological sensing. Many of the current uses of nanomaterials in biosensing are photonic in nature, where the primary mode of sensing is via optical pumping. With the success of photonic based sensors there has been a move to develop electrical based biosensors with nanomaterials. The difficulty is the integration of nanoscale materials into an electrical device that is economic and scalable. We have developed a process that allows for the growth of nanosprings in predetermined patterns using standard lithographic techniques. This breakthrough has greatly simplified device fabrication. The sensors utilize mats of nanosprings as the sensing material and are grown across two or more electrodes. The nanosprings are formed from silica and can be coated with metal nanoparticles to increase their conductivity. Because of the unique surface stoichiometry of the silica nanosprings, the mats of bare nanosprings have conductivities in the picoamp range. The conductivity of the mats can be increased by coating them with metal nanoparticles. Upon exposure of the bare nanospring mats to a buffer solution the conductivity increases to the microamp range. Upon exposure to a buffer solution containing DNA the conductivity increases to the milliamp range. A detailed analysis of the I-V characteristics, transport properties and surface interactions of the nanospring-based biosensor will be presented.
4:30 PM - V5.4
Hazardous Gas Sensors Based on Polyaniline Nanofibers
Shabnam Virji 1 , Jesse Fowler 1 , Bruce Weiller 1 Show Abstract
1 , The Aerospace Corporation, El Segundo, California, United States
Polyaniline nanofibers are versatile sensor materials for detection of a variety of analytes including acids, bases, redox active agents, and organic vapors at room temperature. The nanofibers form stable dispersions in water and can be easily modified with inorganic and organic additives to create new composite materials that can enhance detection of analytes over unmodified nanofibers. We have shown that polyaniline nanofibers modified with copper chloride and related salts give a greatly enhanced response to hydrogen sulfide that is orders of magnitude greater than the unmodified nanofibers. Other inorganic additives can be used to create sensors for many other toxic analytes of interest. Organic additives can also be used to enhance the sensing ability of polyaniline nanofibers for high priority toxic gases relevant to homeland security. Recently, we have shown that doped, unmodified polyaniline nanofibers can detect hydrogen well below the explosion threshold of 4%. We have now demonstrated an entirely new response to hydrogen when platinum is used as the electrode material instead of gold. An overview of these results will be presented.
4:45 PM - V5.5
WITHDRAWN 03/26/07 Use of Spectral Changes of Structural Color of Core-Shell Colloidal Photonic Crystal Films for Selective Chemical Sensing
Radislav Potyrailo 1 , Zhebo Ding 1 , Matthew Butts 1 , Sarah Genovese 1 Show Abstract
1 , GE Global Research, Niskayuna, New York, United States
Friday, April 13Withdrawn-oralV9.5 @ 10:30 am
5:00 PM - V5.6
Electrical Characterization of DNA Deposition and Hybridization using MOS Capacitors.
Sebania Libertino 1 , Manuela Fichera 1 , Salvatore Lombardo 1 Show Abstract
1 Catania, CNR - IMM, Catania Italy
5:15 PM - V5.7
A Maximum Entropy-Nonlinear Least Squares Analysis on ds-DNA based Optical Molecular Rulers.
Mani Prabha Singh 1 , Geoffrey Strouse 1 Show Abstract
1 Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, United States
The structural changes taking place in a biomolecule during specific binding events are measurable with optical molecular rulers. Fluorescence spectroscopy is an important tool in these studies. A steady state measurement gives an averaged value of the distance due to the flexibility of the rulers which arises due to the linkers attaching the fluorophore probes. As a result, a time resolved (tr)- spectroscopic measurement gives a broadened lifetime peak due to the presence of a distribution of distances. A maximum entropy method-nonlinear least squares (MEM-NLLS) fit to the time resolved data determines the broadening of the lifetimes observed due to this flexibility. This broadened peak is resolvable into its constituents and hence the presence of different states/conformers or a distribution of distances can be detected. A double strand (ds-) DNA based optical ruler involving energy transfer from a cyanine fluorophore, Cy5 to a 1.5nm Au nanoparticle (NP) is studied as a function of distance and orientation. The energy transfer efficiency follows a (1/R)4 dependence, where R is the distance separating the fluorophore Cy5 from the Au NP. Cyanine family of fluorophores, because of their structure, is known to closely interact with the ds-DNA structure. Steady-state as well as time-resolved fluorescence spectroscopy is carried out on the ds-DNA construct and a MEM-NLLS analysis was carried out on the time resolved data at various distances. The results confirm the broadening as well as the preference of certain sites by the dye.
5:30 PM - V5.8
VOC Gas Sensing Properties of Organic/MoO3 Hybrid Thin Films with Various Polyaniline Derivatives.
Ichiro Matsubara 1 , Toshio Itoh 1 , Woosuck Shin 1 , Noriya Izu 1 Show Abstract
1 , National Institute of Advanced Industrial Research & Technology, Nagoya Japan
Alternately stacked organic-inorganic hybrids that consist of semiconductive molybdenum trioxide (MoO3) sheets (host) and various organic components (guest) can be used as volatile organic compound (VOC) sensing materials. Almost all the organic/MoO3 hybrid sensors show a distinct response to aldehydic gases, i.e., formaldehyde and acetaldehyde, whereas they show little or no response to other VOCs. The typical organic/MoO3 hybrids ever prepared, such as polypyrrole/MoO3 and polyaniline (PANI)/MoO3 hybrids, have a higher sensitivity to formaldehyde than to acetaldehyde. We have also reported that organic/MoO3 hybrids have a great potential for selective VOC sensing, because the sensing properties of organic/MoO3 hybrids can be controlled by modifying the interlayer organic components, which have the function of molecular recognition. Therefore, it is expected that organic/MoO3 hybrids with a new type of organic components could show a higher sensitivity to acetaldehyde than to formaldehyde. In this study, we have investigated the VOC-sensing properties of organic/MoO3 hybrid thin films with various PANI-derivatives. As results, several PANI-derivatives/MoO3 hybrid thin films a higher sensitivity to acetaldehyde than to formaldehyde. We will report the details of preparation and VOCs (specifically aldehydic gases) sensing properties of PANI-derivatives/MoO3 hybrid thin films. This work was partially supported by New Energy and Industrial Technology Development Organization (NEDO), Japan.
Elisabetta Comini Brescia University
Pelagia-Irene (Perena) Gouma State University of New York-Stony Brook (SUNY)
Vincenzo Guidi University of Ferrara
Xiao-Dong (XD) Zhang Bose Corporation
V6: Biosensors and Hybrid Sensors III
Thursday AM, April 12, 2007
Room 2008 (Moscone West)
9:30 AM - V6.1
Electrochemical Release of Immobilized IgG Protein.
Tanveer Mahmud 1 , Arnan Mitchell 1 , Sally Gras 2 , Adrian Trinchi 3 , Kourosh Kalantar-zadeh 1 Show Abstract
1 Electrical and Computer Engineering, RMIT University, Melbourne, Victoria, Australia, 2 Biomolecular of Chemical and Biomolecular Engineering, University of Melbourne, Melbourne, Victoria, Australia, 3 , CSIRO, Melbourne, Victoria, Australia
9:45 AM - V6.2
Manufacturable Carbon Nanotube Biosensor Chips for Protein and Cell Detection
Fumiaki Ishikawa 1 , Koungmin Ryu 1 , Alexander Badmaev 1 , Chongwu Zhou 1 Show Abstract
1 , USC, Los Angeles, California, United States
Significant effort has been devoted to the study of biosensing using individual single-walled carbon nanotube (SWNT) devices. Few reports exist, however, on manufacturable construction of such biosensing chips, which are crucial for the realization of disposable diagnostic tools. In this talk, we will present two manufacturable approaches for the construction of the biosensor chips using carbon nanotubes. The first approach is based on chemical vapor deposition (CVD) growth of SWNTs on entire wafers followed by metal electrode patterning using a shadow mask and removal of unwanted nanotubes using oxygen plasma. We were able to get about forty devices on one wafer with a narrow resistance distribution (about 20~300 killo-ohm), indicating the high reproducibility and manufacturability of our processes. The other approach is based on our recent success of growing massively aligned carbon nanotubes on a-plane sapphire and miscut quartz from patterned catalyst islands at desired locations. This approach has led to high-density biosensor arrays based on aligned nanotubes. In addition, we investigated the device performance for protein sensing and observed pronounced sensitivity from 10 nM down to 10 pM by metal cluster coating of the nanotubes. The possible mechanism for the improvement was investigated with a control experiment, and we suggest the formation of Schottky barrier between the carbon nanotube and metal cluster interface plays an important role in enhancing the sensitivity. Furthermore, we have applied such nanotube sensors to brown tide algae detection, which is responsible for harmful brown tide, and demonstrated sensitivity of 8*105 cells/ml with selectivity using the recently developed antibody for the algae cell.
10:15 AM - V6.4
Functional Core-Shell Nanoparticles for Biochemical Sensors.
Achim Weber 1 , Kirsten Borchers 1 , Herwig Brunner 1 2 , Gunter Tovar 1 2 Show Abstract
1 Biomimetic Surfaces, Fraunhofer-IGB, Stuttgart Germany, 2 , University Stuttgart, IGVT, Stuttgart Germany
10:30 AM - V6.5
Biological Sensing Using Surface Potential Force Microscopy
Asher Sinensky 1 , Angela Belcher 1 2 Show Abstract
1 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Bioengineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Many biological molecules have a native state which includes the presence of charge centers (e.g. the negatively charged backbone of DNA). Because of this inherent charge, the formation of highly specific complexes between biomolecules will often be accompanied by local changes in charge density. Here we demonstrate a sensor for charged biomolecules, including proteins and DNA, using the scanning probe technique known as Surface Potential Force Microscopy (SPFM or Kelvin Probe). If a probe molecule is patterned onto a surface, biological interactions can result in the highly specific binding of a target biomolecule which may in turn result in a variation in the local surface potential due to a change in local charge density. By spatially resolving this variation in surface potential it is possible to measure the presence of a specific bound target biomolecule on a surface without the aid of special chemistries or any form of labeling (fluorescent or otherwise). This work could provide a framework for future biosensors or microarrays with feature densities hundreds of times greater than current microarray technologies.
10:45 AM - V6.6
Surface Modification and Functionalization of Silicon Carbonitride for Resonant NEMS Biosensing Applications
Lee Fischer 1 2 , Wally Qiu 3 , Ni Yang 3 , Mark McDermott 3 2 , Stephane Evoy 1 2 Show Abstract
1 Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, 2 Nanodevices and Sensors, National Institute for Nanotechnology, Edmonton, Alberta, Canada, 3 Chemistry, University of Alberta, Edmonton, Alberta, Canada
Identification and quantitative analysis of biological molecules is vital in disease detection, drug discovery, and many fundamental problems in molecular biology. Cantilever devices have been proposed as highly-sensitive transducers for the assaying of such biomolecular systems. Surface machining now routinely allows the fabrication of mechanical objects with lateral dimensions reaching the sub 100 nm range and resonant frequencies operating in the GHz range. Such nanoelectromechanical systems (NEMS) are of great interest for the detection and assaying of biomolecules with high sensitivity. The selective immobilization of molecular species onto device surfaces is however key to the successful development of any given biosensing platform. The functionalization of silicon has traditionally involved complex silane-based surface chemistries that offer limited reliability and stability. Alternatively, the coating of surfaces with a gold layer followed by the self-assembly of an alkane-thiol monolayer has also been employed to produce stable amine groups and facilitate further binding chemistries. Such steps however introduce additional fabrication complexities and can induce degradation of the mechanical properties of the NEMS resonator.Alternatively, we have recently established that PECVD silicon carbonitride (SiCN) directly hosts stable amine groups without the need for complex attachment chemistries. Our previous work involving the fabrication and assaying of beam resonators in this material has also determined that it was on par with silicon for NEMS applications while offering the additional advantage of the tunability of its chemical and mechanical properties. We here report the use of ammonia and oxygen plasmas to modify the SiCN surface for the eventual immobilization of carcinoembryonic antigen (CEA) onto resonating NEMS sensors. Similar methods have been used to aminate polymers as well as carbon nanofibres for biological and gas sensing, respectively. We characterize this modified surface chemistry using FT-IR and XPS, and correlate the resulting surface composition to plasma parameters (such as time, power, pressure). Fluorescently-tagged streptavidin, as well as succinimide and silane-based chemistries are used to quantify the resulting extent of the surface modification. Finally, we examine the resonant behavior of SiCN beams and cantilevers before and after a vapor-phase deposition of succinimide and silane-based monolayers onto their surfaces. L.M. Fischer, et al. Mater. Res. Soc. Symp. Proc. Vol. 924 (2006) 0924-Z08-12. H.-C. Wen, et al. Surface & Coatings Technol. 200, 3166-3169 (2006) K. Nakanishi, et al. Analytical Chemistry 68, 1695-1700 (1996)
11:30 AM - V6.7
Interferometric UV Lithography for Nanoscale Patterning of Biological Substrates
Aschalew Kassu 1 , Jean-Michel Taguenang 1 , Anup Sharma 1 Show Abstract
1 Physics, Alabama A&M University, Normal, Alabama, United States
Interferometric UV lithography with low-power 244 nm laser is used to produce micron and nano-scale periodic structures like gratings and microarrays in substrates of biological interest like phospholipid thin films as well as polymers like poly-L-Lysine and polybutadiene. Phospholipid films have found extensive uses as simple models of cell membranes. Model biomembranes are known to be excellent platforms for immobilizing antibodies for biosensing-related applications. Additionally, poly-L-lysine is an amino-acid polymer. Due to its hydrophilicity it is commonly used as a coating agent to promote cell adhesion in culture as well as for immobilization of oligonucleotides in DNA microarrays. Likewise, polybutadiene is a biologically benign polymer which holds promise as a substrate for sensing applications.The experiments described here were motivated by the promise of interferometric techniques to extend photolithography to produce nanometer scale features. Holographic gratings and microarrays are recorded in azo-dye (NBD)-labeled phospholipid thin films using 244 nm UV light. Diffraction efficiency of these gratings shows extreme sensitivity to humidity and can increase reversibly by two orders of magnitude in air, which is saturated with water vapor. This effect is related to the unique characteristics of phospholipid molecules to undergo hydration-dependent structural reorganizations and self-assembly. Lithographic patterning is explained as due to (i) laser-light induced gradient force and (ii) UV-induced photodissociation of phospholipid molecules. UV laser is seen to enhance hydrophilicity of polymer-substrates like poly-L-Lysine and poly-butadiene. Using phase-contrast microscopy, it is observed that UV-patterned hydrophilic arrays in poly-L-Lysine adsorb ambient humidity from air for several hours with relative humidity as low as 50%. Kinetics of this effect was investigated with a novel technique involving spatially periodic adsorption of ambient humidity by a holographically fabricated grating on film surface. Deep-UV is routinely used for crosslinking biological molecules on poly-L-Lysine. These results will be important in controlling the ambient conditions used for crosslinking. In thin-films of polybutadiene, interferometric UV patterning results in nanowells which are 30 nm deep and have an array spot-size of 500 nm x 500 nm. The technique provides a new platform for immobilizing biological molecules for high-density sensor chips. This work is supported by a National Science Foundation EPSCoR Grant.
11:45 AM - V6.8
The Fabrication and Performance of A Magnetoelastic Material as a Platform for Liquid Based Biosensors
Bryan Chin 1 , Michael Johnson 1 , Rajeesh Guntapali 1 Show Abstract
1 materials engineering, auburn university, Auburn, Alabama, United States
12:00 PM - V6.9
Conductimetric Detection of Protein and Cancer Cells with Oxide Nanosensors on a SOP Platform.
P Markondeya Raj 1 , Janagama Goud 1 , Jin Liu 1 , Mahdevan Iyer 1 , Zhong Lin Wang 1 , Rao Tummala 1 Show Abstract
1 Electrical and Computer Engineering, Georgia Tech. - Packaging Research Center, Georgia Institute of Technology, Georgia, United States
The emergence of digital convergence combining computing, communication, consumer functions in a single portable system, when coupled with the advances in medicine lead to a new class of sophisticated implantable bioelectronic systems that can sense, digitize, diagnose, monitor and even dispense medicine to the regions of the body that needs it. Large scale integration of multiplexed, ultra sensitive sensor arrays is critical for several applications such as early detection of diseases and real-time health diagnosis. Nanotechnology based sensor devices fabricated when biofuctionalized with the corresponding biomolecules lead to the next-generation embedded bio-sensor systems for early disease detection. Current ultrasensitive nanoscale sensor integration research is mostly confined to silicon platform with limited choice of sensing materials. Integrating sensors a organic systems packaging platform (System-On-Package) can easily couple the sensing with wireless and digital functions leading to highly integrated bioelectronic systems at low-cost. Semiconducting oxides are widely known and commercially applied for their gas sensing properties. However, biochemical sensing has mostly depended on optical and electrochemical techniques that are more cumbersome. This work investigates the biosensing characteristics of ZnO nanobelts, ZnO and doped barium titanate thin films. Nano zinc oxide sensors showed significant changes in conductivity after protein functionalization with rabbit IgG and hybridization with anti-rabbit IgG. Systematic changes in conductivity of nanosensors were also measured after coating the oxides with MCF-7 cancer cells and its antibodies. In another set of experiments, ZnO nanobelts showed systematic conductivity changes after functionalizing with S-100 Schwann nerve cells. The conductivity changes from rabbit IgG protein hybridization can be detected even with doped barium titanate films. The experimental results in this paper indicate that the conductimetric properties of nano and thin film oxides can be sensitized to protein and cancer cell hybridization reactions and can be accurately detected. This technique can also be applied to certain pathogen proteins or toxic proteins from the environment. These nanostructured oxide biosensors have potential for early detection of prostate-specific antigen (PSA) and breast cancer genes such as HER2 (or HER2/neu), BRCA1 and BRCA2 I. When combined with organic substrate packaging, integration of wireless and mixed signal interfaces, and microfluidic guidance of biological fluids, this SOP based system integration approach is expected to provide low-cost, real-time sensing for clinical diagnostics and early detection of cancer diseases.
12:15 PM - V6.10
High Sensitivity Photonic Crystal Biosensor Incorporating Nanorod Structures for Enhanced Surface Area.
Wei Zhang 1 , Nikhil Ganesh 1 , Ian Block 2 , Brian Cunningham 2 Show Abstract
1 Department of Materials Science and Engineering, University of Illinois at Urbana Champaign, Urbana, Illinois, United States, 2 Department of Electrical and Computer Engineering, University of Illinois at Urbana Champaign, Urbana, Illinois, United States
12:30 PM - V6.11
Quantum Dot-molecule Energy Transfer Systems Applicable to Multiphoton-excited Imaging and Quantification of Biochemical Parameters in vivo.
Andrew Greytak 1 , Rebecca Somers 1 , Emily McLaurin 1 , Moungi Bawendi 1 , Daniel Nocera 1 Show Abstract
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
12:45 PM - V6.12
Conjugated Polyelectrolytes as Tools for Decorating Biomolecules in vitro, in tissue and in vivo
Olle Inganas 1 , Peter Nilsson 1 , Anna Herland 1 , Per Bjork 1 , Per Konradsson 3 , Per Hammarstrom 2 , Jon Jonasson 4 , Mikael Lindgren 5 , Andreas Aslund 3 , Gunilla Westermark 6 Show Abstract
1 IFM, Linköping University, Biomolecular and organic electronics, Linkoping Sweden, 3 IFM, Linköping University, Organic chemistry, Linkoping Sweden, 2 IFM, Linköping University, Biochemistry, Linkoping Sweden, 4 Biomedicine and Surgery, Linköping University, Clinical Chemistry, Linkoping Sweden, 5 Physics, The Norwegian University of Science and Technology, Trondheim Norway, 6 Biomedicine and Surgery, Linköping University, Cell Biology, Linköping Sweden
Photoluminescence from conjugated polymers in the form of charged macromolecules, polyelectrolytes, is a tool to image the presence and activity of biological macromolecules in simple and in complex systems. The CPEs form complexes with biological macromolecules, by means of all the weak interactions available from biological interactions….van der Waals interactions, electrostatic and dipolar interactions, hydrophobic and hydrogen bonding. The geometry of the polymeric emitter is influenced by the interactions with target molecules, and the emission and absorption properties change due to these changes. By this means biomolecular events such as conformational changes, hybridisation of DNA chains and antibody-antigene reactions may be followed. Such studies can be done in buffers, in tissue samples when appropriately treated, and in in vivo studies. Protein aggregation resulting in amyloid fibrils can be followed both in vitro and after deposition in tissue; the target amyloids are selectively decorated in tissue samples. By this means amyloid plaque implicated in Alzheimer disease can be decorated. Such decorated deposits are also accessible in multiphoton excitation, where stimulus in the near infrared leads to red emission by two photon processes. Two photon processes are enhanced in the CPEs studied, and therefore offers interesting options for imaging of live cells and tissue.
V7: Biosensors and Hybrid Sensors IV
Thursday PM, April 12, 2007
Room 2008 (Moscone West)
3:00 PM - V7.1
Nanoplasmonic Molecular Ruler for Studying DNA-protein Interactions and Proteomic Changes.
Fanqing Chen 1 , Gang Liu 2 , Luke Lee 2 Show Abstract
1 Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 , University of California at Berkeley, Berkeley, California, United States
3:15 PM - V7.2
Vacuum Deposited Porphyrine/Phthalocyanine Films as Promising Optical Gas Sensing Materials
Gianluigi Maggioni 1 , Michele Tonezzer 2 3 , Sara Carturan 1 , Alberto Quaranta 3 , Katerina Severova 4 2 , Gianantonio Della Mea 3 2 Show Abstract
1 INFN-LNL, Università di Padova c/o, Legnaro Italy, 2 Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare, Legnaro (PD) Italy, 3 DIMTI, Università di Trento, Povo (TN) Italy, 4 Institute of Physical and Applied Chemistry, Brno University of Technology, Brno Czech Republic
Porphyrins and phthalocyanines are macrocyclic compounds which have been arousing increasing attention in the last decade due to their peculiar electrical and optical properties. Particularly interesting are the optical properties of these macrocycles, such as the intense absorption of visible light and the chemical stability upon illumination, which can be tailored by modifying their basic molecular structure. These properties have been used for developing optical chemical sensors, since the interaction between the analyte and the macrocycle gives rise to measurable changes of the light absorption of the macrocycle.In order to be exploited as sensing materials, porphyrins and phthalocyanines must be usually deposited as solid films onto a suitable substrate. A large number of chemical techniques (spin coating, Langmuir–Blodgett, etc.) has been used and studied for this purpose. Fewer efforts, on the contrary, have been made to produce thin films by means of vacuum deposition techniques in spite of the fact that these techniques assure several advantages with respect to the standard chemical methods such as great reproducibility, uniformity and stricter control of the film thickness. Moreover, the vacuum deposition techniques produce thin films without using any extraneous compound such as organic solvents, thus allowing to obtain samples with very high purity. Sample purity is expected to play an important role in the chemical sensing field, because the presence of retained solvent in the film can partially hinder the film/analyte interaction, thus lowering the optical response to the analyte.In this work two vacuum deposition techniques were used for the production of thin films of macrocyclic molecules: high vacuum evaporation (VE) and glow-discharge-induced sublimation (GDS). Vacuum evaporation is a well known deposition method; while it has been already widely used for the production of phthalocyanine films, vacuum evaporation of porphyrin films is still relatively little explored. GDS technique, on the contrary, has been used very little for the deposition of both phthalocyanines and porphyrins: it is based on the use of a radio frequency plasma, which gives rise to the sublimation of the macrocyclic molecules and to their condensation onto the substrate.Two macrocycles were selected for this work: 5,10,15,20 meso-tetraphenyl porphyrin (H2TPP) and copper phthalocyanine (CuPc). H2TPP and CuPc films were deposited by VE and GDS techniques. H2TPP films were also deposited by spin coating (SPIN), by exploiting the solubility of this compound in organic solvents. In order to evaluate the sensing properties of H2TPP and CuPc films, their optical response to volatile organic compounds (VOCs) was tested at room temperature, by exposing the sample to VOC vapours at different concentrations. All the vacuum deposited films exhibited short response times and much higher sensitivity than those deposited by standard chemical methods.
3:30 PM - V7.3
Preparation of Layered Organic/Molybdenum Trioxide Hybrid Thin Films as High Sensitive VOC Sensors.
Toshio Itoh 1 , Ichiro Matsubara 1 , Woosuck Shin 1 , Noriya Izu 1 Show Abstract
1 Advanced Manufacturing Researci Institute, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Aichi, Japan
The sick house syndrome is caused by several harmful volatile organic compounds (VOCs), specifically formaldehyde. The indoor regulation values of aldehydic gases concentration are indicated by the Ministry of Health, Labour and Welfare in Japan. To prevent this problem, using ventilation systems controlled by VOC sensors is one of the best approaches, because of not only the ventilation of indoor air but also energy saving. Therefore, VOC sensing devices which possess continuous monitoring and low-concentrate, i.e. sub-ppm level, VOC detection are required.Layered organic-inorganic hybrids of semiconductive molybdenum trioxide (MoO3) thin films with organic components, e.g. polyaniline (PANI) and poly(o-anisidine) (PoANIS), are investigated for the volatile organic compounds (VOCs) sensing properties by means of monitoring their electrical resistance. We tried new procedure of synthesizing organic/MoO3 hybrid thin film: 1) deposition of MoO3 thin films on a silicon substrate with a LaAlO3 buffer layer and a gold comb-type electrode by chemical vapor deposition (CVD); 2) insertion of sodium ions into MoO3 interlayers by reduction; 3) intercalation of organic components into MoO3 interlayers by ion exchange. MoO3 thin films were prepared by the pyrolysis of molybdenum hexacarbonyl in oxygen atmosphere by CVD. The MoO3 thin films were soaked into sodium hydrosulfite aqueous solution to reduce the MoO3 and to insert ion-exchangeable sodium ions between the MoO3 sheets. Thus-obtained films ([Na(H2O)2]xMoO3) then underwent an ion-exchange reaction. The [Na(H2O)2]xMoO3 films were soaked in organic polymers aqueous solutions to ion-exchange Na+ for organic polymers, respectively. The resulting hybrid films were washed quickly with distilled water and then dried.The VOC-sensing properties of the organic/MoO3 hybrid were determined experimentally using a flow apparatus. The organic/MoO3 hybrid thin film was placed in homeothermic chamber, and the resistance of the thin film was measured directly through the gold comb-type electrode. The target VOC concentrations were precisely controlled using the flow system with a mass flow controller. After the pure carrier gas was passed through the chamber, the target VOC flowed, and then the gas flowing into the chamber was again changed to pure carrier gas.The new-prepared organic/MoO3 hybrids show a distinct increasing resistive response to aldehydic gases. In contrast, there is little or no response to chloroform, alcohols, acetone, and aromatics. Moreover, these hybrids can detect sub-ppm concentration of VOCs. In this presentation, preparation of layered organic/MoO3 hybrid thin films as high-sensitive VOC sensors and its sensing properties will be reported.This work was partially supported by New Energy and Industrial Technology Development Organization (NEDO), Japan.
3:45 PM - V7.4
Chiral Recognition with Enhanced Sensing Organic Thin-film Transistors.
Luisa Torsi 1 2 , Gianluca Farinola 1 , Patrizia Iliade 1 , Maria Tanese 1 2 , Francesco Marinelli 1 , Mirizio Francesca 1 , Omar Omar 3 , Ludovico Valli 4 , Gabriele Giancane 4 , Francesco Babudri 1 3 , Francesco Palmisano 1 , Pier Zambonin 1 2 , Francesco Naso 1 3 Show Abstract
1 Chemistry, Università degli Studi di Bari, Bari Italy, 2 , CE TIRES - Università degli Studi di Bari, Bari Italy, 3 Chemistry - CNR ICCOM, Università degli Studi di Bari, Bari Italy, 4 Innovation Engeneering, Università degli Studi di Lecce, Lecce Italy
4:30 PM - V7.5
PNA Based SERS Substrates for DNA Detection.
Laura Fabris 1 , Gary Braun 1 , SeungJoon Lee 1 , Mark Dante 1 , Norbert Reich 1 , Moskovits Martin 1 , Thuc-Quyen Nguyen 1 , Guillermo Bazan 1 Show Abstract
1 Department of Chemistry and Biochemistry , University of California, Santa Barbara, California, United States
4:45 PM - V7.6
A Novel Glucose Sensor Based on the Deflection of a Thin Hydrogel Membrane
Sandeep Mariserla 1 , Thomas Mackin 2 Show Abstract
1 Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois, United States, 2 Mechanical Engineering, California State Polytechnic University, San Louis Obispo, California, United States
Self-monitoring of blood glucose has become an important and critical tool for effective management of patients with diabetes. We describe here a novel MEMS sensor that can continuously measure, in real time, the concentration of glucose in a solution. The device utilizes a glucose-sensitive hydrogel membrane, which swells reversibly in the presence of a glucose containing solution. The amount of swelling is related to the concentration of glucose. The hydrogel is composed of 2-hydroxyethyl methacrylate (HEMA) functionalized with 3-acrylamidophenylboronic acid (AAPBA) groups as the glucose-sensitive moiety. Phenylboronic acid (PBA) derivatives interact with glucose by forming a charged complex, causing the hydrogel to swell by solvent intake.A thin hydrogel layer is processed into a laminated membrane architecture that includes one half of a parallel plate capacitor. The resultant swelling of the hydrogel deflects the membrane and moves that capacitor plate. Signal transduction arises directly from motion of the plate with respect to a fixed conducting pad, resulting in a change in capacitance. Hence the presence or variation in the concentration of glucose can be observed as a change in capacitance of the device.The device is fabricated using standard microfabrication techniques. A Single-Crystal-Silicon (SCS) wafer is fabricated into a die; this die is then placed into a tetramethyl ammonium hydroxide (TMAH) bath for anisotropic etching of the SCS. This step thins the wafer where the polymer membrane will reside, reducing etch time in subsequent steps. Si islands are patterned from the bottom side of the die using PR, followed by coating the top surface with an intermediate polydimethylsiloxane (PDMS) layer. This PDMS layer is the structural layer of the membrane, and also serves as a hermetic seal between the glucose solution and the capacitance gage. The glucose-sensitive hydrogel monomer is then flown onto the PDMS membrane in the final step and UV-polymerized, thus excluding and protecting it from the harsh processing conditions mentioned in the earlier steps.Results detailing the swelling properties of the AAPBA-containing HEMA hydrogel samples, their adhesion to the PDMS protective membrane and the deflection caused by their bi-layer expansion will be discussed. The mechanical properties of the bi-material membrane and it’s response to varying concentrations of glucose solutions will be analyzed. Determination of the bending mechanics of the glucose-sensitive bi-layer hydrogel membrane will help formulate the dimensions and the recipe for incorporation into the device.
5:00 PM - V7.7
Highly Sensitive Nitric Oxide Biosensor: Detection Using X-ray Photoelectron Spectroscopy.
Manish Dubey 1 , Steven Bernasek 1 , Jeffrey Schwartz 1 Show Abstract
1 Department of Chemistry, Princeton University, Princeton, New Jersey, United States
Detection of gaseous nitric oxide (NO) in biological systems has attracted a lot of attention ever since its identification as the endothelial-derived relaxing factor (EDRF)1. NO also acts as a signal molecule in the nervous system, and is associated with the presence of infection and Alzheimer’s and other diseases. Apart from biological systems, NO is a main product released on the pyrolysis of nitro-organic explosives. For these reasons, much work has been done in the field of NO detection, and the need for a sensitive detector is evident. In this study, we report a direct and a highly sensitive technique to detect gaseous NO using X-ray Photoelectron Spectroscopy (XPS).The binding of NO by heme proteins is well understood2, and we have utilized it for detection. We have developed a reliable method to grow Self-Assembled Monolayers (SAMs) of alkylphosphonic acids on oxide surfaces3. This platform is used to covalently attach an iron heme-like molecule, which was synthesized separately. The N1s signal from the heme ligand was measured by XPS before and after exposure to NO. Before NO binds to the iron, a single nitrogen peak is present, attributed to the nitrogens of the porphyrin ring. After reaction with NO, a new, distinct peak was observed in the high resolution N1s spectrum. This peak is at a higher binding energy (approx 5.5 eV), and is attributed to the NO bound to the iron. An estimate of the bound NO was calculated to be about 40 picomoles. Reference:1. R. M. J. Palmer, A.G. Ferrige, S. Moncada, Nature, 1987, 327, 524.2. K. R. Rodgers, Curr Opin Chem Biol, 1999, 3, 158.3. E. L. Hanson, J. Schwartz, B. Nickel, M. Koch, M. F. Danisman, J. Am. Chem. Soc., 2003, 125, 16074.
5:15 PM - V7.8
Localized Surface Plasmon Resonance Biosensor for Substrate Binding to Cytochrome P450 Proteins.
Jing Zhao 1 , Richard Van Duyne 1 , George Schatz 1 Show Abstract
1 Chemistry, Northwestern University, Evanston, Illinois, United States
Localized surface plasmon resonance (LSPR) is one of the signature optical properties of noble metal nanoparticles. The LSPR resonant wavelength is extremely sensitive to the local environment around the nanoparticles, allowing for the development of nanoparticle-based LSPR chemical and biological sensors. Recently, the influence of resonant adsorbates on the LSPR of Ag nanoparticles was explored by mapping the LSPR wavelength change upon the adsorption of the analytes through the visible wavelength region. Both reduced and amplified LSPR response was observed when the nanoparticles’ surface plasmon couples with the molecular resonance of the adsorbates. This study provides a new approach to guide the design of biosensing chip sensors for biological targets with visible chromophores. A chip with patterned nanostructures was constructed and optimized for the detection of low molecular weight substrate/inhibitor binding to heme-containing proteins. This binding induces a change in the molecular resonances of the protein. Specifically, the heme-containing cytochrome P450 (cyt P450) proteins absorb light in the visible region (Soret absorption ~ 417 nm). When a small substrate/inhibitor molecule binds to cyt P450, the spin state/coordinating environment of the protein will change, which leads to a change in its Soret band. By fabricating nanoparticles with their LSPR that couples with the molecular resonance of P450 molecules with and without substrate/inhibitor, the response caused by substrate/inhibitor binding was monitored through a wide range of wavelengths. The most amplified response for a substrate with a molecular weight as low as ~ 150 g/mol was found to be as large as 37 nm.
5:30 PM - V7.9
Fabrication of Novel Polydiacetylene-Based Microarray Chips for Label-Free DNA Detection
Dong June Ahn 1 2 , Doo Ho Yang 1 , Eun Jin Kim 1 , Gil Sun Lee 1 2 , Jong-Man Kim 3 Show Abstract
1 Department of Chemical & Biological Engineering, Korea University, Seoul Korea (the Republic of), 2 Instute for Integrated Nano Systems, Korea University, Seoul Korea (the Republic of), 3 Department of Chemical Engineering, Hanyang University, Seoul Korea (the Republic of)
Polydiacetylene supramolecules are interesting biomimetic materials in view of application to chemical and biological sensors. These conjugated supramolecules are unique in changing color from blue to red upon specific binding events, caused by shortening of delocalization length of π-electrons along diacetylenic backbones. Various binding events including viruses, toxins, glucose, DNAs, proteins, and ionic interactions have been reported detectible with the forms of solution-phase vesicles and solid-supported films. However, multiplexing of various binding events has not been possible. As continuing efforts to develop polydiacetylene-based microarray chips, we have been successful in immobilization of the vesicles on solid substrate surfaces (Adv. Mater. 2003, 15, 1118) and, for the first time, in fabrication of chemical-sensing microarrays on glass by using a conventional ink-jet spotter (J. Am. Chem. Soc. 2005, 127, 17580). Each dot was found to possess the color changing property as well as the fluorescence self-emission. In this presentation, we focus on developing a novel polydiacetylene-based microarray DNA chip. Label-free detection results on sequences of E. Coli. and anthrax lethal factors will be discussed in the aspects of sensitivity as low as 10 fM and of specificity capable of discerning single-base mismatch against perfect match for SNP applications.
5:45 PM - V7.10
Analyte-Induced Ordering Transitions of Liquid Crystals on Chemically Functionalized Surfaces for Reporting Chemical Warfare Agents.
Katie Cadwell 1 , Nathan Lockwood 1 , Colin Willis 2 , Nicholas Abbott 1 Show Abstract
1 Chemical & Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States, 2 , Defense Science & Technology Laboratory - Porton Down , Salisbury, Wiltshire, United Kingdom
This presentation will describe an experimental investigation of the orientational ordering of liquid crystals on chemically functionalized surfaces and how changes in this ordering can report the presence of vapor-phase analytes. Surfaces presenting metal ions will be shown to coordinate with liquid crystals containing suitable ligands, thus leading to micrometer-thick films of liquid crystal with orientations that are regulated by metal ion-ligand coordination interactions. Subsequent exposure of these oriented films of liquid crystal to analytes that interact competitively for metal ion coordination at the interface will be demonstrated to lead to ordering transitions in the liquid crystal. Such ordering transitions are visible to the naked eye when illuminated with white light and viewed between crossed polars. Infrared measurements provide insights into the molecular origins of the macroscopic ordering transitions that are observed when micrometer-thick films of liquid crystals supported on metal salts are exposed to organophosphorous compounds. The potential utility of these principles for simple sensing technologies will be illustrated by rapid detection of organophosphorous simulants and chemical warfare agents.
V8: Poster Session: Functional Materials for Chemical and Biochemical Sensors II
Friday AM, April 13, 2007
Salon Level (Marriott)
9:00 PM - V8.12
WITHDRAWN 03/20/07 An Optoelectronic Sensor based on Carbon Nanotubes Nanocomposites for the Room Temperature Detection of Environmental Pollutants
Marco Consales 1 , Antonello Cutolo 1 , Stefania Campopiano 2 , Michele Penza 3 , Patrizia Aversa 3 , Michele Giordano 4 , Andrea Cusano 1 Show Abstract
1 Optoelectronic Division-Engineering Department, University of Sannio, Benevento Italy, 2 Department for Technologies, University of Naples Parthenope, Napoli Italy, 3 Materials and New Technologies Unit, ENEA, Brindisi Italy, 4 Institute of Composite Biomedical Materials, CNR, Napoli Italy
Thursday, April 12Withdrawn-posterV8.12
9:00 PM - V8.13
WITHDRAWN 03/20/07 A Single-Walled Carbon Nanotubes-based Optical Fiber Sensor for Chemical Detection in Water Environment
Marco Consales 1 , Alessio Crescitelli 1 , Antonello Cutolo 1 , Stefania Campopiano 2 , Michele Penza 3 , Patrizia Aversa 3 , Michele Giordano 4 , Andrea Cusano 1 Show Abstract
1 Optoelectronic Division-Engineering Department, University of Sannio, Benevento Italy, 2 Department for Technologies, University of Naples Parthenope, Napoli Italy, 3 Materials and New Technologies Unit, ENEA, Brindisi Italy, 4 Institute of Composite Biomedical Materials, CNR, Napoli Italy
Thursday, April 12Withdrawn-posterV8.13
9:00 PM - V8.15
An Organic Electronic Ion Pump to Induce Intracellular Signalling in Living Cells.
Magnus Berggren 1 , Agneta Richter-Dahlfors 2 , Joakim Isaksson 1 , David Nilsson 3 , Peter Kjall 2 , Nathaniel Robinson 1 Show Abstract
1 ITN, Linkoping University, Norrkoping Sweden, 2 MTC, Karolinska Institutet, Stockholm Sweden, 3 Printed Electronics, Acreo AB, Norrkoping Sweden
9:00 PM - V8.16
Novel Investigation of Ozone Sensor Based on Porous Silicon.
Rathinasamy Prabakaran 1 Show Abstract
1 Department of Materials Science and CEMOP/UNINOVA , CENIMAT, Caparica, Caparica, Portugal
9:00 PM - V8.17
Copper Phthalocyanine Organic Nanowires as a Prospective Platform for Chemical Sensing
Evghenii Strelcov 1 , Seghei Dmitriev 1 , Andrei Kolmakov 1 Show Abstract
1 Physics, SIUC, Carbondale, Illinois, United States
9:00 PM - V8.18
Resist Free Fabrication of Metal Oxide Nanowire Gas Sensors
Bradly Button 1 , Yigal Lilach 3 , Victor Sysoev 2 , Serghei Dmitriev 2 , Andrei Kolmakov 1 Show Abstract
1 Physics, SIUC, Carbondale, Illinois, United States, 3 , PNNL, Richland, Washington, United States, 2 Physics, Saratov State Technical University, Saratov Russian Federation
9:00 PM - V8.19
Adhesion Force of Avidin Molecules on Well-ordered Solid Surfaces.
Ryuji Aoki 1 , Taro Arakawa 1 , Toshio Ogino 1 Show Abstract
1 Dept. of Electrical and Computer Engineering, Yokohama National University, Yokohama Japan
9:00 PM - V8.2
Development of Device of VOC Sensors Using Organic/MoO3 Hybrid Materials.
Hiroki Yabe 1 , Susumu Kajita 1 , Toshio Itoh 2 , Woosuck Shin 2 , Noriya Izu 2 , Ichiro Matsubara 2 Show Abstract
1 Advanced Technologies Development Lavoratory, Matsushita Electric Works, Ltd., Osaka Japan, 2 Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology, Nagoya Japan
Introduction: We are developing new volatile organic compounds (VOCs) sensors with high selectivity and sensitivity by using the layered organic/inorganic hybrids of semiconductive molybdenum oxide with organic components. A device which integrates sensor elements on a substrate can be fabricated by molding material technology. In this presentation, we report the thermal stability of the sensor materials, which is important for the design of the sensor device. Experimental section: LaAlO3 buffer layer was coated by a solution method on a silicon wafer with a thermally oxidized SiO2 insulation layer. A gold comb-type electrode was formed by a lift-off process on the buffer layer. The MoO3 thin film was prepared on the substrate by the pyrolysis of molybdenum hexacarbonyl in oxygen by CVD. The MoO3 thin film was soaked in the aqueous solution of Na2S2O4 and Na2MoO4 2H2O to reduce the MoO3 layers and to insert Na+ ions in the interlayers. Polyaniline, PANI, aqueous suspension was prepared by the polymerization of aniline. An aniline hydrochloride aqueous solution was adjusted pH value to 1.0 using HCl solution and then mixed with polymerization initiator, (NH4)2S2O8. The Na+ intercalated MoO3 film, [Na(H2O)2]xMoO3, was soaked in the PANI suspension to ion-exchange Na+ for PANI. The resulting thin film is referred to as (PANI)xMoO3. To study thermal stability of the sensor materials, (PANI)xMoO3 sensor elements were heated at 150, 200, 250, 300 degrees Celsius for 5 or 30 minutes. X-ray diffraction analysis (XRD) was carried out to estimate thermal stability of the crystallinity of the (PANI)xMoO3. Gas sensing properties of the (PANI)xMoO3 thin films to HCHO gas were measured in a flow apparatus at 100 degrees Celsius with HCHO balanced with nitrogen. The response signal was defined as the ratio of Rg/Ra, where Rg and Ra were the electrical resistances of the sensor elements in an analyte gas with nitrogen carrier gas and in only carrier gas, respectively. Results and Discussion: From XRD pattern of the substrate after CVD, deposited MoO3 thin film possessed b-axis orientation along the face of the substrate. The interlayer distance of the host was increased to 1.36nm because PANI was intercalated into the MoO3 by cation-exchange reaction. After the heat treatment at 150 degrees Celsius, XRD peaks of (PANI)xMoO3 hardly change. But at more than 200 degrees Celsius, XRD peaks were shifted to wide angle and sank down. These results mean the interlayer PANI in MoO3 was partially broken and the interlayer distance decreased with the treatment temperature and time increased at more than 200 degrees Celsius. Gas sensing property of the sensor elements, Rg/Ra, was no problem after the heat treatment at 150 degrees Celsius. Acknowledgment: This work was partially supported by New Energy and Industrial Technology Development Organization (NEDO). We would like to express our thanks for their kind support.
9:00 PM - V8.20
Characteristics of Electrochemical CO2 Sensor Based on Thin Film Conducting Electrolyte Combined with Thick Film Components.
Woon Young Lee 1 , Jinseong Park 2 , Haegun Shin 2 , Dong-won Park 1 , Yong-Kook Choi 1 Show Abstract
1 , Chonnam University, Gwangju Korea (the Republic of), 2 , Chosun University, Gwangju Korea (the Republic of)
9:00 PM - V8.21
CMOS Micro Humidity Sensors Using Nano-structured Carbon Nitride Film
Sungpil Lee 1 , Jigong Lee 1 , Sungyeop Kim 1 , Choongwon Chang 1 , Chongsoo Mun 2 Show Abstract
1 Electronic Engineering, Kyungnam University, Masan, Kyungnam, Korea (the Republic of), 2 Advanced Materials Engineering, Kyungnam University, Masan, Kyungnam, Korea (the Republic of)
CMOS micro humidity sensors with nano-structured carbon nitride film as humidity sensing materials are fabricated by 0.8 μm standard CMOS process and porous gate metal formation, and their threshold voltage and drain current drift are investigated according to the relative humidity change. Integrated sensor system consists of humidity sensor, temperature sensor, Hall sensor and OP amp. The micro humidity sensor has several type, such as conventional n-type and p-type FET, n-type and p-type interdigital gate and combined bridge structure. Gate length of sensor is 8 μm, chip size is 2x4 mm and pin number is 28, respectively. The sensor part is consisted of a pair of transistors, that is, humid-sensitive transistor and non-sensitive one. The aspect ratio is 300/8 for both transistors to get same current-voltage characteristics and to compare a drift of drain current to humidity changes. Nano-structured carbon nitride (CNx) films as humidity sensing materials on the gate insulator are prepared by reactive RF magnetron sputtering with a DC bias at various deposition conditions. When water molecules meet carbon nitride layer through the porous gold layer of FET gate, they are chemisorbed on the available sites of the carbon nitride surface by dissociative mechanism to form two hydroxyl ions for each water molecule, which possess high local charge density and a strong electrostatic field, and the proton reacts with an adjacent surface O2- group to form a second OH- group. Therefore singly bonded water molecules are able to form dipole and to reorient freely under an externally applied gate field, resulting in an increase in the dielectric constant. It is caused by an increase of capacitances in sensing materials. This is attributed to the threshold voltage changes and the drain current increases of micro humidity sensors. The fabricated humid non-sensitive MISFET, that is, reference MISFET presents the typical enhancement mode characteristics. The humidity sensitive MISFET shows that the normalized drain current linearly increases from 0.124 to 0.415 in the range of the relative humidity from 30% to 95%. The normalized value of the drain current can be used as a sensitivity of the humidity sensitive field effect transistor.
9:00 PM - V8.22
Hydrogen Sensors Based on Cu/Pd Bimetal Layers.
Manika Khanuja 1 , Bodh Mehta 1 , Sonnada Shivaprasad 2 Show Abstract
1 Physics, Indian Institute of Technology Delhi, New Delhi, Delhi, India, 2 Surface Physics and Nanostructures, National Physical Laboratory, New delhi, Delhi, India
9:00 PM - V8.23
Near-Infrared Sensitive Photorefractive Bifunctional Dendrimers Operating at 830 nm
Kyung Moon Jung 1 , Sang Kyu Lee 1 , Min Ju Cho 1 , Dong Hoon Choi 1 Show Abstract
1 depratment of chemistry, korea university, Seoul Korea (the Republic of)
During the past decade, photorefractive (PR) organic materials have received considerable attention due to their low cost, easy processability, and possibility of manipulation of PR properties by chemical modifications. While most studies of PR polymers and organic glasses were carried out in a visible wavelength region, the extension to near-infrared (NIR) wavelengths has several advantages, which include the use of low-cost semiconductor diodes available at many NIR wavelengths, and the tissue transparency window at 700–900 nm in biological applications. The PR wavelength sensitivity is embedded in the photogeneration process, and is usually determined by a sensitizer added to the PR material composite and its interactions with the other components of the composite. In most NIR studies, PR sensitization is achieved using (2,4,7-trinitro-9-fluorenylidene)malononitrile (TNFM) as a sensitizer. New bifunctional dendrimers C-TCP-Cz and C-Cz-TCP were synthesized successfully. C-TCP-Cz and C-Cz-TCP have three functional dendrons. The difference of dendrimers is the order of Cz and TCP. C-TCP-Cz has the carbazole unit at the outermost peripheral position. NLO chromophore exists at the terminal peripheral unit in C-Cz-TCP. The chemical structures of the new bifunctional dendrimers were characterized by 1H NMR spectrometer. The flexible six methylene spacer and 1st-generation dendrimer are designed to reduce the glass transition temperature. So the glass transition temperatures of C-TCP-Cz and C-Cz-TCP were 44oC and 29oC at heating rate of 10oC/min. We prepared the thick PR samples by using C-TCP-Cz and C-Cz-TCP. PR sample was fabricated using C-TCP-Cz and TNFM. The solution prepared in monochlorobenzene was filtered through an acrodisc syringe filter and then cast on indium-tin-oxide (ITO) pre-coated glass. The film was dried overnight at 100oC under vacuum. After the solvent had been removed completely, another ITO glass was placed on top of the film and pressed down at 150 oC with a 60-µm polyimide film as a spacer to get a sandwich device for two-beam coupling (2BC) experiments. The net gain of one of the dendrimers, C-Cz-TCP was determined about 80-100 cm-1.
9:00 PM - V8.24
Bottom-up Creation for Antibody with High Affinity for Inorganic Materials
Mitsuo Umetsu 1 , Takamitsu Hattori 1 , Takeshi Nakanishi 1 , Izumi Kumagai 1 Show Abstract
1 Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai Japan
Recent advance in biotechnology enables us to find the peptides with affinity for nonbiological materials and with function of mineralizing inorganic materials. The recognition of peptide/protein for material surface, especially, the specific binding on inorganic materials, is attracting a growing interest as an indispensable tool for the fusion between biotechnology and nanotechnology. The peptide/protein with excellent binding ability and specificity for an inorganic compound and its crystal structure, enables to directly immobilize and pattern biomolecules on the corresponding inorganic nanoparticles and substrates, and further, to control the crystal structure growth in the inorganic synthesis process. Antibody is a naturally occurring recognition molecule with high binding ability and specificity in immune system. In general, antibody have high affinity at the dissociate constant of ~nM, and it can be expected to be superior to that of a low-molecular weight peptide showing relatively low affinity to its target surface. Here, we append the affinity for inorganic material to antibody by replacing the complementarity determining regions (CDRs) of antibody with a specific peptide for the corresponding material. The utilization of the peptide for innovating antibody would open the way to convenient preparation for the antibody against non-biomaterials. We would show the possibilities of the CDR-grafting technique for the innovation of the antibody with affinity for non-biomaterials, and further, the maturation of the grafted antibody to the bio-interface molecule with high affinity by phage display technique.
9:00 PM - V8.25
An Overview of Polydiacetylene Optical Strain Sensors.
Jennifer Kauffman 1 , William Pennington 2 , Michael Ellison 1 , Timothy Hanks 3 Show Abstract
1 Materials Science & Engineering, Clemson University, Clemson, South Carolina, United States, 2 Chemistry, Clemson University, Clemson, South Carolina, United States, 3 Chemistry, Furman University, Greenville, South Carolina, United States
Polydiacetylene polymers are known for their dramatic colorimetric detection abilities. When formed in a solid-state polymerization, the backbone of the polymer is planar and continuous π-overlap is observed. However, when an outside force is imposed on the system the backbone contorts, breaking the conjugation length and providing an optical shift. The state of the backbone has been monitored quantitatively through Raman spectroscopy. Several novel strain sensing systems have been created and subjected to simultaneous tensile testing and Raman scans. A few of these systems include copolyurethane-diacetylene polymers cross-polymerized with UV, hydrogen-bonded polymer blends of 4-butoxymethylcarbonyl urethane in several industrial polyurethanes (ex. Tecoflex®, Lycra®, Minwax®, etc.), and finally polydiacetylene cationic and anionic dyes that have been bound electro-statically to acrylic and wool, respectively. A linear trend has been established between the Raman -C≡C- stretch peak of the polydiacetylene (~2100cm-1) and the percent strain detected from the system. It has been determined that similar strain sensing capabilities are available from the polymer blends as compared to the copolymer systems.
9:00 PM - V8.26
Development of an Immunoassay for Monitoring Tissue-Specific Function in Cellular Micropatterns.
Caroline Jones 1 , Ji Youn Lee 1 , Alexander Revzin 1 Show Abstract
1 Biomedical Engineering, UC Davis, Davis, California, United States
Surface micropatterning approaches have been utilized extensively for investigating the effects of cell-cell and cell-surface interactions on the expression of cell phenotype. More recently, robotic microarraying approaches have emerged as tools for combinatorial screening of cell-microenvironment interactions. The emergence of cell culture approaches that provide multiple biological stimuli in the same cell culture dish necessitates the development of new methods for evaluating local cell function in the context of a complex microenvironment. The present project seeks to develop an immunoassay for local detection of tissue-specific proteins in micropatterned hepatic cells. Glass surfaces were patterned with cell-adhesive proteins (e.g. collagen (I)) using robotic printing or photolithographic approaches. Glass surfaces were then incubated with an anti-albumin antibody, resulting in formation of discrete micropatterned domains for cell-adhesion and albumin binding. When seeded onto the surface, hepatic cells (HepG2 cells) became spatially localized to matrix protein domains and started secreting liver-specific proteins such as albumin. Secreted albumin was then captured by the antibody molecules immobilized around cellular clusters. Binding of the albumin was verified by fluorescently- or HRP-labeled secondary antibody. The proposed surface micropatterning approach enabled local detection of tissue-specific proteins secreted by hepatic cells. This approach may offer a new tool for monitoring local phenotype of cells exposed to a complex, microfabricated environment.
9:00 PM - V8.27
Inorganic Electride Films as Potential Electro-optic Sensors
Georgi Diankov 1 , Andrew Ichimura 1 Show Abstract
1 Chemistry and Biochemistry, San Francisco State University, San Francisco, California, United States
Zeolites are microporous crystalline solids that have traditionally found applications in exchange, separations, and catalytic processes. These diverse applications originate from the 'molecular' pore size of 5-7 Å, the robustness of the framework and the ability to withstand high temperatures, as well as the variable composition (depending on zeolite type) from pure silica to materials with equal molar ratios of Si and Al ([M+AlO2-]x[SiO2]1-x; x≤0.5]. Recently, zeolites have received considerable attention as potential chemical sensors prepared as supported thin films, using substrates such as an ATR crystal or the end of a quartz optical fiber.1,2 Our interest in sensing applications involving zeolites takes a different approach and stems from the unique optical and electric properties of alkali metal doped silica zeolites, which are referred to as M@SZ where M = Na-Cs and SZ is an all-silica zeolite.3,4 In this report, the properties of M@SZ prepared as bulk powders and thin films supported on Au, Si, quartz and ITO are explored through optical (IR, UV-vis-NIR) reflectance and transmission spectroscopy, X-ray diffraction, HRSEM, solid-state MAS NMR and AFM. For this study, zeolite MFI (silicalite, ZSM-5) was chosen because films of pure silica material are straightforward to synthesize. Optical reflectance measurements on powders show that Cs@MFI exhibits a broad NIR peak that increases in intensity with increasing Cs concentration. The NIR band is evidence for free electrons trapped in the zeolite pores.3,4 Cs-doped MFI films also exhibit the NIR band, but significantly, the absorption intensity increases toward the NIR as would be expected if the sample were metallic. Packed powder conductivity measurements show that bulk samples are insulating due to grain boundary effects. It is hypothesized that the continuity of the polycrystalline MFI film may permit electron transport through the pore structure of Cs@MFI, as predicted by density functional calculations.5 Conductivity measurements on M@MFI films are in progress. Because the free electron NIR band is intrinsic to M@SZ materials, it is envisioned that thin M@SZ films could function as NIR transducers and find applications as sensors or as integral components of electro-optic technology. 1.Bein, T. Chem. Mater 1999, 8, 1636-1653.2.Zhang, J.; Luo, M.; Xiao, H.; Dong, J. Chem. Mater. 2006, 18, 4-6.3.Ichimura, A. S.; Dye, J. L.; Camblor, M. A.; Villaescusa, L. A. J. Am. Chem. Soc. 2002, 124, 1170-1171.4.Wernette, D. P.; Ichimura, A. S.; Urbin, S. A.; Dye, J. L. Chem. Mater., 2003, 15(7), 1441-1448.5.Li, Z.; Yang, J.; Hou, J. G.; Zhu, Q.; J. Am. Chem. Soc., 2003, 125, 1170-1171.
9:00 PM - V8.29
Synthesis, Characterization and Modification of Fe3O4 Nanoparticles and their Application in DNA Sequence Detection.
Jin Xie 1 Show Abstract
1 , Brown University, Providence, Rhode Island, United States
9:00 PM - V8.3
Hydrogen Sensors Using Pd-based Metallic Glassy Alloys.
Susumu Kajita 1 , Sumiaki Nakano 1 , Shin-ichi Yamaura 2 , Hisamichi Kimura 2 , Kunio Yubuta 2 , Akihisa Inoue 2 Show Abstract
1 , Matsushita Electric Works, Ltd, Kadoma , Osaka Japan, 2 Institute for Materials Research, Tohoku University, senndai,miyagi Japan
Pd-based metallic glassy alloys have been investigated as materials for the hydrogen sensors. We produced thin films of Pd-Cu-Si alloy known as typical metallic glassy alloys and then examined their sensitivity to hydrogen in various gas conditions.The Pd-Cu-Si thin films with different composition ratio were deposited on glass substrates by r. f. magnetron sputtering method. In order to verify the amorphicity of the thin films, an X-ray diffractometry ( XRD ) and a transmission electron microscopy ( TEM ) was used. The existence of a supercooled liquid region ( SCLR ) was measured with a differential scanning calorimeter ( DSC ). The sensitivity to hydrogen of thin films were examined by measuring the change of electric resistance of them when they were exposed to hydrogen and some other gases.Glass transition temperature ( Tg ) was 606 K to 637 K , crystallization temperature ( Tx ) was 633 K to 681K. Analyses by TEM , it showed that nano crystals existed in some films. The Pd-Cu-Si thin films were sensitive to hydrogen in wide range of hydrogen concentration (e.g. 1% to 100%) and showed rapid response to the change of hydrogen concentration. Besides their sensitivity and response time was changed by measurement temperature. It was also found that the influence of the impurity gasses such as CO, CO2, CH4 and H2O on hydrogen sensitivity changed depending on the measurement temperature. Furthermore, these thin films did not flake off from the glass substrate after the examination of hydrogen sensitivity, though the Pd-Ni crystalline thin film flaked off easily.These results indicate that the Pd-Cu-Si metallic glassy alloys have an excellent property as materials for the hydrogen sensors.
9:00 PM - V8.30
Fabrication and Characterization of Individual Nanotube Based Nanoelectrodes for Chemical and Biological Sensing.
Kyungsuk Yum 1 , Min-Feng Yu 1 Show Abstract
1 Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
We present the fabrication and characterization of individual nanotube based high length-to-diameter aspect ratio nanoelectrodes for chemical and biological sensing. The nanoelectrodes are fabricated by coating insulating nanotubes with metal, such as gold and silver, subsequently coating them with thin insulating layers, and cutting the end of the nanoelectrodes. The process yields ring-shaped nanoelectrodes, with the thickness of the ring of ~ 10 nm, whose electrochemically active area is controlled by the metal deposition. The nanoelectrodes have a total structural diameter of ~ 100 nm, including insulating layers, and length up to ~ 30 µm. The nanoelectrodes are characterized by cyclic voltammetry (CV) and square wave voltammetry (SWV), and the structure of the nanoelectrodes is further examined in transmission electron microscope (TEM). The nanoelectrodes show steady-state voltammetric current responses and good insulation of the side wall of nanoelectrodes. The high length-to-diameter aspect ratio nanoelectrodes will allow a new opportunity for electrochemical sensing in microscale environments, e.g. in vivo probing local intracellular environments without damaging cells, with high temporal and spatial resolution.
9:00 PM - V8.4
Low temperature Fabrication of Tungsten Oxide Arrays onto Ceramic Substrates
Seungwan Song 1 , Insu Kang 1 , Jeongmin Lee 1 , Robert Glass 2 Show Abstract
1 Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon Korea (the Republic of), 2 Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States
A method for growing tungsten oxide films on alumina and zirconia ceramic substrates using an aqueous polytungstate solution at 75-98oC is presented. Variation in the reaction parameters of temperature, time and substrate resulted in a variation in growth morphology from round particles to square and hexagonal plates, rice, flower-like crystals and acorns arrays. The films made in solution method were active in electrochemical sensing of NO2 gas and their resistance variation was consistent with changes in gas concentration. The resultant data contribute to the applications of metal oxide films fabricated onto ceramic substrates not only to sensors but also membranes and solid oxide fuel cells.
9:00 PM - V8.6
ppb Level Gas Sensors Based on SnOx: M (M = Ag, Pd) Composite Nanoparticle Layers: A Comparative Study of the Effect of Metal Nanoparticle Size on Ethanol Sensing.
Ivaturi Aruna 1 , Kruis Frank 1 Show Abstract
1 Department of Engineering Sciences, University of Duisburg-Essen, Duisburg Germany
9:00 PM - V8.7
Hydrogel Based Composite Materials for Chemical, Biological and Medical Sensing Applications.
Tim Porter 1 , Jim Reed 2 , Ray Stewart 2 , Kathryn Morton 2 Show Abstract
1 Physics, Northern Arizona University, Flagstaff, Arizona, United States, 2 , Cantimer, Inc., Menlo Park, California, United States
Various hydrogels, functionalized hydrogels and hydrogel composite materials may be used as the active sensing material is embedded piezoresistive microcantilever (EPM) sensors. Depending on the sensing application, the sensing material is designed to physically or chemically respond to the desired analyte, resulting in signal transduction through the microcantilever. Previous EPM sensor designs have demonstrated rapid responses to a variety of chemical and biological species, including volatile organic compounds, carbon monoxide, hydrogen cyanide gas, single-strand DNA, certain proteins, vaccinia virus, and others. In the present application, we describe the use of a functionalized hydrogel material in a small, handheld personal hydration sensor. This sensor is designed to respond to changes in solution osmolality, thus providing a rapid, intraoral, and non-invasive method of measuring an individual's hydration state. The sensing material responds volummetrically to the analyte through the partitioning in of fluid species owing to osmotic pressure and membrane diffusion into the gel volume. Stable signals are generally obtained after 30 seconds of exposure. After an osmolality sensing event, the sensor material may fully recover to its original state through immersion in a standard solution of known osmolality. Applications for this sensor include pediatric hydration assessment, geriatric hydration monitoring, and various sports monitoring applications.
9:00 PM - V8.9
Enhanced Gas Sensing Properties of In2O3:Ag Composite Nanoparticle Layers: Size and Interfacial Effects
Vidhya Singh 1 , Bodh Mehta 1 , F. Kruis 2 Show Abstract
1 Thin Film Laboratory, Department of Physics, Indian Institute of Technology, New Delhi, Delhi, India, 2 Nanostrukturtechnik, University of Duisburg-Essen, Duisburg, NRW, Germany