Chris Keimel, GE Global Research
Helena Silva, University of Connecticut
Robert N. Candler, University of California, Los Angeles
Frank W. DelRio, National Institute of Standards and Technology
Symposium Support Tousimis Research Corp.
Zurich Instruments Ltd.
XX3: Fluidic Systems and Surface Interactions
Monday PM, December 02, 2013
Sheraton, 3rd Floor, Fairfax A
2:30 AM - *XX3.01
Low Temperature Fabrication and Surface Modification Methods for Fused Silica Micro- and Nanochannels
Sumita Pennathur 1
1UCSB Santa Barbara USAShow Abstract
Electrokinetic based micro- and nanofluidic technologies provide revolutionary opportunities to separate, identify and analyze biomolecular species. Key to fully harnessing the power of such systems is the development of a robust method for integrated electrodes as well as a thorough understanding of the influence of the electrokinetic surface properties with and without different surface modifications. In this work, we demonstrate a surface micromachined fabrication approach for integrated addressable metal electrodes within centimeter-long nanofluidic channels using a low-temperature, xenon diflouride dry-release method for novel biosensing applications, as well as recent results from a joint theoretical and experimental study of electrokinetic surface properties in nano- and microfluidic channels fabricated with fused silica. The main contribution of this fabrication process involves the addition of addressable electrodes to a novel dry-release channel fabrication method, produced at <300°C, to be used in nanofluidic electronic sensing of biomolecules. We also show a novel method with which to coat our channels with silane based chemistries. Finally, we show a theoretical model that we developed to robustly characterize the surface. Our theoretical model consists of three parts: (1) a chemical equilibrium model of the wall, (2) a chemical equilibrium model of the bulk electrolyte, and (3) a self-consistent Gouy--Chapman--Stern triple-layer model of the electrochemical double layer coupling between (1) and (2). We use experimental data with aqueous potassium chloride and buffer solutions in silica nanochannels to confirm theoretical predictions. In addition to describing techniques used to measure electrokinetic properties within experimental micro- and nanofluidic systems, show three separate experimental validations of this electrokinetic surface model.
3:00 AM - XX3.02
Flexible Surface Acoustic Wave Devices and Its Applications in Microfluidics
Jian Zhou 1 Xingli He 1 Wenbo Wang 1 Nana Hu 1 Weipeng Xuan 1 Hao Jin 1 Shurong Dong 1 Demiao Wang 1 Jikui (Jack) Luo 1 2
1Zhejiang University Hang Zhou China2Bolton University Bolton United KingdomShow Abstract
Flexible microsystems are a member of the flexible electronic family, yet provide important and unqiue functions. Various devices and microsystems have been developed such as the micro-machined infrared bolometer, piezoelectric actuators, piezoelectric pressure sensors, and micro-fluidics. Surface acoustic wave (SAW) devices are essential for electronics, microsensors, microsystems and lab-on-a-chip; however there is no report on the development of flexible SAW device yet. This paper reports the first development of flexible SAW devices on cheap, bendable and disposable plastic films.
SAW devices were made on ZnO thin films deposited on polyimide substrates by sputtering. By optimizing the process, we were able to obtain ZnO films on polymers with good quality and low stress of <100 MPa, suitable for direct device fabrication. Crystal structure characterization revealed the ZnO films are dominated by (0002) crystal orientation with the grain sizes of ~70 nm. The SAW devices were made by photolithograph and lift-off process. The results are highlighted as follows,
(1). Deposition process has significant effects on performance of SAW devices, high deposition pressure resulted in high quality ZnO films, and the transmission signal become larger as the pressure was increased.
(2). For a fixed wavelength, the ZnO film thickness affects the SAW characteristics strongly, the thicker the ZnO film, the better performance of the SAW devices.
(3). Flexible SAW devices showed two resonant modes. The resonant frequency of the first mode increases from 198 to 447 MHz as the wavelength was decreased from 32 to 10 mu;m, while the zero mode decreases from ~200 to 34 MHz. Large signal amplitudes up to 18dB were obtained from devices with different wavelengths.
(4). Theoretical analysis and modeling revealed that the zero mode resonance is the Rayleigh wave, while the first mode resonance is the Lamb wave. Modeling showed the Rayleigh wave velocity increases with decrease in wavelength, while the Lamb wave velocity decreases, in excellent agreement with the experimental results.
(5). The resonant frequencies of the SAW devices decrease linearly with increase in temperature, with the temperature coefficients of frequency of ~442 and ~245 ppm/K for the two mode waves respectively.
(6). The flexible SAW devices have been used to test the ability for microfluidics and particle sorting, two of many lab-on-a-chip functions. A streaming velocity up to ~3.5 cm/s was obtained. Also it showed the flexible SAW devices are able to perform microparticles concentration and sorting in a few tens of seconds.
The results showed that the flexible SAW devices have high performance for electronics, sensors and microfluidics, compatible to those made on rigid substrates, demonstrated great potential for widespread applications.
3:15 AM - XX3.03
Modeling of a MEMS Floating Element Shear Sensor
Nikolas Kastor 1 Zhengxin Zhao 1 Robert White 1
1Tufts University Medford USAShow Abstract
A MEMS floating element shear stress sensor has been developed for flow testing applications, targeted primarily and ground and flight testing of aerospace vehicle and components. Skin friction is one of the major components of drag in vehicles, but is difficult to measure using existing techniques such as oil film interferometry, boundary layer profile surveys, or thermal methods. Direct floating element MEMS sensors address these issues by providing real time, momentum transfer based unsteady shear measurements at a surface with the potential for low topology and array sensing. However, concerns remain about the interaction of the flow with the mechanical elements of the structure at the microscale. In particular, there are concerns about the validity of laminar flow cell calibration to measurement in turbulent flows, and the extent to which pressure gradients may introduce errors into the shear stress measurement. In order to address these concerns, a numerical model of the Tufts floating element shear stress sensor has been constructed.
The model describes the behavior of the mechanical components, fluid interaction and electrostatics of a micromachined nickel floating element fluid shear stress sensor. Three 3-D numerical simulations were performed on the geometry of this sensor: A finite element model of the static element; a computational fluid dynamics (CFD) model of the floating element, for flat and textured versions of the floating shuttle; and a finite element model of the capacitive sensing combs. The static, large displacement, finite element model subjected the sensor element to applied loads of 2Pa to 12Pa. This model shows linear deflection in the flow direction on the order of 10-10m and deflection in the transverse flow direction on the order of 10-11m at 12Pa. In the CFD model, the shear sensor experienced internal duct flows of 5CFH to 40CFH where the geometry of the floating element was studied to determine which features contributed to what percentage of the total applied force and sensitivity. Pressure gradient was determined to contribute to 25% of the sensitivity of the flat sensor and close to 60% for the textured shuttle showing that a textured shuttle surface adds to the pressure gradient sensitivity and non-linearity. The finite element model of the capacitive combs shows the electrostatic coupling and fringe effects and how they contribute to the sensitivity of the sensor. With the combination of these three numeric models, sensor output as a function of steady state fluid flow parameters can be predicted and directly compared to experimental data. The computational model allows us to quantify the contributions (e.g. pressure gradient vs shear, top surface vs. lateral surfaces) to the sensor output in a manner that is difficult by purely experimental means.
3:30 AM - XX3.04
Submicron Displacement Measurements of MEMS Using Optical Microphotographs in Aqueous Media: Enhancement Using Color Image Processing
Stephan Warnat 1 Hunter King 1 Rachael Schwartz 1 Marek Kujath 1 Ted Hubbard 1
1Dalhousie University Halifax CanadaShow Abstract
The measurement of precise submicron displacements is essential in several MEMS applications. For instance, the measurement of mechanical parameters of biological cells requires repeatable measurement of displacements in the nanometer regime. This paper presents a method to make precise displacement measurements in an aqueous media. Optical microscopes are limited by the diffraction of light and a maximum resolution of about 200 nm is typically achievable; pattern matching algorithms allow further refinement of the displacement measurements to about 100 nm. The measurement technique developed by Yamahata et al. [Yamahata et al., JMEMS, Vol. 19, No. 4, pp. 1273-1275, 2010] allows displacement measurements in the nanometer regime using only a conventional optical microscope setup. This technique is based on applying a FFT phase-shift comparison of movable spatially periodic comb structures with known pitch of the comb. Implementation of the Yamahata method using MUMPS structures operating in air demonstrated 5 nm repeatability [Warnat et al, 24th Canadian Congress of Applied Mechanics, Saskatoon, June 2-5, 2013]. However, estimation of mechanical parameters of live biological cells requires measurements in aqueous media. Implementation of the Yamahata method in aqueous environment resulted in a 35-50 nm repeatability [Warnat et al, 24th Canadian Congress of Applied Mechanics, Saskatoon, June 2-5, 2013], this is due to poor optical contrast between the periodic comb structures (Poly-Si) and the substrate (SiN). This paper shows an approach to overcome the material contrast problem in water by analyzing static color microphotographs. While the substrate and the moving comb intensities are similar and of low contrast, the color profiles are different and of higher contrast. The image analysis was complicated by the variable nitride layer thickness 600 +/- 70 nm and thus varying color. The contrast is improved by subtracting the substrate average RGB color from the image, resulting in a higher contrast image that is then processed by the Yamahata technique. This paper shows displacement measurements in an aqueous media with a repeatability of 10 nm. This approach is therefore a good alternative to electrostatic displacement measurement techniques, which need additional and often expensive electronic measurement devices.
3:45 AM - XX3.05
Detections of Fast Single-Particle Translocation through a Micro-Fluidic Channel via Combined Optical and Electrical Sensing
Shoji Tanaka 1 2 Makusu Tsutsui 2 Kentaro Doi 1 Satoyuki Kawano 1 Tomoji Kawai 2 Masateru Taniguchi 2
1Osaka University Toyonaka Japan2Osaka University Ibaraki JapanShow Abstract
Nanopores and nanochannels have been widely used as a useful platform for electrical detections of single-particles to study the fast translocation dynamics [D. Branton et al., Nat. Biotechnol., 26, 1146 (2008), B. M. Venkatesan et al., Nat. Nanotechnol., 6, 615 (2011)]. The sensing mechanism involves measurements of temporal blockage of the ionic current through a fluidic channel, which is called resistive pulses, by an individual particle passing through it. In recent years, there has been increasing number of research efforts in this field reporting miscellaneous features in the electrical signatures of single-molecule or -particle translocations, e.g. ionic current blockage, enhancement, or even composites of these two aspects. Although systematic and statistical analysis of numerous electrical signals gives comprehensible explanations on the underlying physics in many cases, electrical detections alone cannot ensure whether a resistive pulse is associated with envisaged translocation of individual analyte particles [S. Alon et al., Rev. Sci. Instrum., 81, 014301 (2010)].
In the presentation, I present a single-particle tracking in a fluidic channel by combined electrical and optical sensing. This approach offers the missing function of the electrical method for identifying the presence and absence of analyte in a nanopore or nanochannel at the moment when a resistive pulse is detected.
In experiments, a fluidic microsystem lithographed on a glass substrate was used to measure the ionic current through the microchannel. Meanwhile, fluorescent imaging of dyed polystyrene particles was conducted simultaneously from the back of the substrate. I will show that this technique enables unambiguous sorting of resistive pulses to translocation-derived and non-translocation-derived, particle-particle collisions and temporal blocking, and even discriminates single-particle and two-particle-cluster translocations. It is also found that the combined optical/electrical sensing reveals an important role of particle history in the pre-translocation regime in determining its electrophoretic dynamics in a microchannel by allowing detections of single-particle motions at extensive spatial and dynamic ranges. The capability of this combined approach to guarantee the presence of an analyte in a specific volume may be useful in developing electrode-embedded nanopore sensors [M. Zwolak et al., Rev. Mod. Phys., 80, 141 (2008), M. Tsutsui et al., Sci. Rep., 1, 46 (2011)], which requires elucidating whether the measured transverse current originates from a particle or a molecule of concern.
XX4: Energy Generation and Conversion
Monday PM, December 02, 2013
Sheraton, 3rd Floor, Fairfax A
4:30 AM - *XX4.01
Capacitive Energy Storage Based on Mesoporous Oxide Films
Veronica Augustyn 1 Iris Rauda 2 Sarah Tolbert 2 Bruce Dunn 1
1UCLA Los Angeles USA2UCLA Los Angeles USAShow Abstract
Capacitive energy storage is distinguished from other types of electrochemical energy storage by short charging times, the ability to deliver significantly more power than batteries and long cycle life. A key limitation to this technology, which is based on electric double-layer capacitance, is its low energy density. For this reason, there is considerable interest in exploring materials which exhibit pseudocapacitive charge storage where the fast and reversible redox reactions that occur with transition metal oxides lead to energy densities which are several times larger than traditional double layer capacitance.
Our results with mesoporous TiO2, MoO3 and Nb2O5 films establish that this porous architecture is very beneficial for capacitive energy storage. Through the co-assembly of inorganic sol-gel precursors with diblock copolymers, an interconnected mesoporous network is formed that enables the electrolyte to access the redox-active pore walls, thus ensuring that the entire film is electrochemically active. Because of the mesoporous morphology, pseudocapacitive contributions dominate the charge storage process. Moreover, these mesoporous materials exhibit significantly higher levels of charge storage with far better kinetics than the corresponding oxides without a well-defined pore-solid architecture. Mesoporous films of MoO3 and Nb2O5 exhibit enhanced pseudocapacitive charge storage because of an additional contribution associated with lithium ions being inserted into preferentially oriented crystalline layers. The pseudocapacitive behavior exhibited by the mesoporous transition metal oxide films represents a very promising direction for designing electrochemical capacitors that can achieve increased energy density while still maintaining high power density.
5:00 AM - XX4.02
Textured K0.5Na0.5NbO3 for Micro Electromechanical Systems: Processing-Structure-Property Relationships
Maria Elizabete Costa 1 Muhammad Asif Rafiq 1 Paula Vilarinho 1
1University of Aveiro/CICECO Aveiro PortugalShow Abstract
This talk is about the electromechanical performance of highly grain-oriented (K0.50Na0.50)NbO3 ceramics fabricated using KNN single crystals as templates. Smart materials, that include piezoelectric and ferroelectrics, play a crucial role in the development of micro-electromechanical systems (MEMS), for applications as optical displays, acceleration sensing, radio-frequency switching, drug delivery, chemical detection, and power generation and storage. The increasing importance of MEMs in microelectronics industry has also been addressed by the International Road Map for Semiconductors (ITRS) within the concept of functional diversification called “More than Moore” . Pb(Zrx,Ti1-x)O3 (PZT) is still the most widely used piezoelectric for such applications, but environment protection and related legislations - are pushing research of lead free piezoelectrics and ferroelectrics. Among them K0.5Na0.5NbO3 (KNN) is one of the leading lead free piezoelectric materials in the perovskite group being considered as a candidate material for MEMS. Undoped K0.5Na0.5NbO3 (KNN) has inferior electromechanical properties as compared to PZT and thus various efforts are on going to tailor and improve the electrical and electromechanical properties of KNN. Some of the strategies include doping, chemical substitutions, or microstructure texturing . In this work, we report the fabrication and electrical properties of highly grain-oriented (K0.50Na0.50)NbO3 ceramics via the use of KNN single crystals as templates. This is an alternative strategy to the current use of hetero-templates (such as plate-like NaNbO3 particles) and not reported before. KNN single crystals were grown by a modified flux method . The grown KNN crystals present a high dielectric permittivity of 29,100 at the tetragonal to cubic phase transition temperature, remnant polarization of 19.4 µC/cm2, piezoelectric coefficient of 160 pC/N and revealed a long range ordered domain pattern of parallel 180° domains with zig-zag 90° domains. The role of homo-texturing on the orientation dependence of the electromechanical properties is presented and the relationships between the properties, processing, and performance of KNN are established. The obtained results are benchmarked against the current available information published in the literature.
 International Technology Roadmap For Semiconductors 2012.
 Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, T. Nagaya, M. Nakamura, Lead-free piezoceramics. Nature, 2004, 432, 84-87.
 Muhammad Asif Rafiq, M. Elisabete V. Costa, Paula M. Vilarinho, Establishing the domain structure of (K0.5Na0.5)NbO3 (KNN) single crystals by piezoforce-response microscopy, submitted.
5:15 AM - XX4.03
Sliding-Triboelectric Nanogenerators Based on In-Plane Charge-Separation Mechanism for Mechanical Energy Harvesting and Active Sensing
Sihong Wang 1 Long Lin 1 Yannan Xie 1 Qingshen Jing 1 Simiao Niu 1 Zhong Lin Wang 1
1Georgia Institute of Technology Atlanta USAShow Abstract
Aiming at harvesting ambient mechanical energy for self-powered systems, e.g. self-powered microelectromechanical systems (MEMS), triboelectric nanogenerators (TENGs) have been recently developed as a highly efficient, cost-effective and robust approach to generate electricity from mechanical movements and vibrations, on the basis of the coupling between triboelectrification and electrostatic induction. However, all of the previously-demonstrated TENGs are based on vertical separation of triboelectric-charged planes [1, 2], which requires sophisticated device structures to ensure enough resilience for the charge separation, otherwise there is no output current. In this paper, we demonstrated a newly designed TENG based on an in-plane charge separation process using the relative sliding between two contacting surfaces. Using Polyamide 6,6 (Nylon) and polytetrafluoroethylene (PTFE) films with surface etched nanowires, the two polymers at the opposite ends of the triboelectric series, the newly invented TENG produces an open-circuit voltage up to ~1300 V, and a short-circuit current density of 4.1 mA/m2, with a peak power density of 5.3 W/m2, which can be used as a direct power source for instantaneously driving hundreds of serially-connected light-emitting diodes (LEDs). The working principle and the relationships between electrical outputs and the sliding motion are fully elaborated and systematically studied, providing a new mode of TENGs with diverse applications. Compared to the existing vertical-touching based TENGs, this planar-sliding TENG has a high efficiency, easy fabrication and suitability for many types of mechanical triggering. Furthermore, with the relationship between the electrical output and the sliding motion being calibrated, the sliding-based TENG could potentially be used as a self-powered displacement/speed/acceleration sensor in MEMS. 
 Fan, F. R.; Tian, Z. Q.; Wang, Z. L. Nano Energy 2012, 1, 328-334.
 Wang, S. H.; Lin, L.; Wang, Z. L. Nano Lett. 2012, 12, 6339-6346.
 Wang, S. H.; Lin, L.; Xie, Y. N., Jing, Q. S., Niu, S. M., Wang, Z. L. Nano Lett. 2013, 13, 2226-2233.
5:30 AM - XX4.04
Piezoelectric Energy Harvesting Using Lead-Free (K,Na)NbO3 Films on Flexible Metal Foil
Shiraishi Takahisa 1 Kaneko Noriyuki 1 Kurosawa Minoru 1 Uchida Hiroshi 2 Kobayashi Takeshi 3 Funakubo Hiroshi 1
1Tokyo Institute of Technology Yokohama Japan2Sophia University Kioi-cho Japan3National Institute of Advanced Industrial Science and Technology Tsukuba JapanShow Abstract
The battery-less sensor system has been investigated for the health monitoring system of infrastructure because of the maintenance-free and the low cost. These devices operate by the energy from external environmental sources. Vibration energy harvesting by the piezoelectric films is one of the method to generate the electric power. In this method, the piezoelectric films are required the high flexibility as well as the good electromechanical properties because the large displacement of piezoelectric films leads the large energy generation. Therefore, it is important to get the piezoelectric films on flexible substrates. In addition, environmental friendly lead-free piezoelectric materials must be used and have superior piezoelectric and electromechanical properties.
In the present study, 3 mu;m-thick (K,Na)NbO3 films were deposited on metal foil substrate (25 mu;m in thickness) at low temperature of 240omicron;C by hydrothermal method. Hydrothermal method is the wet process and deposit films at low temperature below 300omicron;C for large area.
We succeeded to make the flexible (K,Na)NbO3 films because these films did not break by the large displacement. Clear hysteresis loop was observed in polarization- electric filed and strain-electric field relationships. d33 value and remanent polarization were 28 pm/V and 7 mu;C/cm, respectively. Moreover, the resonance frequency value was 20 Hz. This value of (K,Na)NbO3 films on flexible substrate was smaller than that of (K,Na)NbO3 films on rigid substrate. These low resonance frequency is useful because the environmental frequency is generally less than about 1 kHz.
5:45 AM - XX4.05
High Power Primary Lithium Ion Micro Batteries
James H. Pikul 1 Paul V. Braun 2 1 William P. King 1 2
1University of Illinois at Urbana - Champaign Urbana USA2University of Illinois at Urbana-Champaign Urban USAShow Abstract
Here we present a primary microbattery with high capacity and high power density. The microbattery is based on interdigitated three-dimensional nanoporous bicontinuous electrodes, which enables short ion diffusion lengths and high discharge power. The microbatteries utilize new primary battery chemistry to achieve a capacity of 8.67 µAh/cm2µm, which is 3X the average capacity of our previously reported high power rechargeable microbatteries . The microbattery capacity is increased by using lithium as an anode and two phases of manganese oxide as the cathode to achieve a large discharge voltage range of 3.3 - 0.6 volts with high capacity. Increasing the discharge voltage range takes advantage of the low voltage requirements of state of the art microelectronics for portable devices . The interdigitated three-dimensional nanoporous bicontinuous electrodes allow for micro-integration of the anode and cathode and shorten the ion diffusion and electron conduction lengths to achieve high power density. The 3D electrodes were formed by electrodepositing nickel through a colloid assembly formed from 500 nm diameter colloidal particles, resulting in a Ni inverse of the colloid structure, on a gold patterned glass substrate. Electrodeposited lithium was used for the anode and electrodeposited manganese oxide for the cathode active materials. Lithium is an excellent primary anode because of its high energy density and low, constant voltage relative to the cathode. During galvanostatic discharge the manganese oxide has two voltage plateaus with mean voltages of 2.6 volts and 0.8 volts, corresponding to two difference Mn valence states. The footprint area of the tested cells was ~4 mm2. The microbattery cells can deliver a high power density of 3,300 µW/cm2µm, which is close to the highest power reported for microbatteries . Additionally the microbatteries can alternate between a high power pulsed discharge (740 µW/cm2µm pulsed 36 times for 0.1 seconds) and a low power sleep discharge (0.3 µW/cm2µm), which is critical for applications requiring wireless communication and device actuation. High capacity and high power density primary microbatteries can enable smaller power sources, faster computation, stronger actuation, and longer data transmission distances for microsystems with short to medium lifetimes.
 J. H. Pikul, H. Gang Zhang, J. Cho, P. V. Braun, and W. P. King, "High-power lithium ion microbatteries from interdigitated three-dimensional bicontinuous nanoporous electrodes," Nature communications, vol. 4, p. 1732, 2013 2013.
 G. Chen, M. Fojtik, K. Daeyeon, D. Fick, P. Junsun, S. Mingoo, C. Mao-Ter, F. Zhiyoong, D. Sylvester, and D. Blaauw, "Millimeter-scale nearly perpetual sensor system with stacked battery and solar cells," in Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2010 IEEE International, 2010, pp. 288-289.
XX1: Metrology and Reliability
Monday AM, December 02, 2013
Sheraton, 3rd Floor, Fairfax A
9:30 AM - *XX1.01
MEMS Motion Metrology by Super-Resolution Fluorescence Microscopy
Craig McGray 1
1Modern Microsystems, Inc. Silver Spring USAShow Abstract
Measuring the motion of microelectromechanical systems is key to understanding system performance and reliability and is rapidly becoming an area of great commercial importance. These measurements can be difficult due not only to the size of the measured devices, but also to the size of the characteristic motions of the devices, which are often many orders of magnitude smaller. Such is the case for many stepwise microactuators and closed-loop acccelerometers, in which the characteristic motions may be on the order of nanometers. Although such small dimensions lie beneath the Rayleigh limit for optical resolution, the motions may still be measured optically using super-resolution analysis techniques, provided that there is sufficient contrast in the image. One way to provide sufficient contrast for these techniques is through fluorescence microscopy. By labeling a MEMS device with multiple fluorescent nanoparticles and measuring the motions of these particles, translations and rotations of the MEMS devices can be determined. Measurement uncertainties of 1.85 nm and 100 microradians have been achieved, with localization precision of 130 pm.
10:00 AM - XX1.02
Design and Operation of a Microfabricated Phonon Spectrometer
Obafemi Otelaja 1 Jared Hertzberg 2 3 Mahmut Aksit 2 Richard Robinson 2
1Cornell University ithaca USA2Cornell University ithaca USA3University of Maryland College Park USAShow Abstract
Phonons — the quanta of lattice vibrations — are the major heat carriers in semiconductors and insulators, and a better understanding of their nanoscale transport will inform the engineering of materials for thermoelectric and microelectronic cooling applications. To this end, we have developed a microfabricated phonon spectrometer utilizing superconducting tunnel junctions (STJ) as phonon transducers.[1,2] Al-AlxOy-Al STJs are utilized for emission and detection of tunable and non-thermal acoustic phonons with frequency ~100 to 870 GHz in silicon microstructures. [1,2] We show that phonon spectroscopy with STJs offers a spectral resolution of ~15-20 GHz, which is ~10 times better than thermal conductance measurements, for probing nanoscale phonon transport. We discuss the design, fabrication, and low-noise instrumentation needed to implement a phonon spectrometer. We show that the phonons propagate ballistically through silicon microstructures with submicron spatial resolution. With a spectrally resolved measurement of phonon transport such as ours, the understanding of phonon propagation and scattering in nanoscale structures will be greatly improved; hence, the exploitation and engineering of phonons for thermoelectric devices, microelectronic coolers, and phononic devices should become more feasible. In addition, with the ability to distinguish acoustic phonon modes, we can further understand the acoustic loss mechanisms in micromechanical resonators.
 J.B. Hertzberg, O. O. Otelaja, N. J. Yoshida, and R. D. Robinson. Rev. Sci. Instrum. 82, 104905 (2011).
 O.O. Otelaja et al, New J. Phys. 15 (2013), 043018
10:15 AM - XX1.03
Nucleation Rate of Capillary Bridges between Multi-Asperity Surfaces
Emrecan Soylemez 1 Maarten P. de Boer 1 W. Robert Ashurst 2
1Carnegie Mellon University Pittsburgh USA2Auburn University Auburn USAShow Abstract
This work is devoted to capillary nucleation rate with time. It is well known that the environment in which microelectromechanical systems operate significantly affects their performance. It is therefore important to characterize micromachine behavior in environments that are well controlled. To this end, we have modified and characterized an advanced test system that allows for environmental control (pressure, relative humidity, and gas composition) while retaining full micromachine characterization capability (long working distance interferometry, electrical probe connectivity, actuation scripting). The system also includes a load lock with in-situ plasma cleaning that renders surfaces uniformly hydrophilic. A microcantilever crack healing experiment is conducted and surface adhesion energy measurements are tracked over time after a step change in humidity is applied. The experimental sample includes twenty silicon cantilevers, of lengths 1,050 µmle;Lle;2,000 µm in 50 µm increments. The height of the step-up support post is h=1.8 µm, the cantilever width is w=20 µm and the cantilever thickness is t=2.5 µm. After increasing relative humidity from 30% to 53%, the crack healing rate begins at 4 µm/minute and gradually decreases to 0 after 410 minutes. An FEM model has been generated to simulate the near-crack tip capillary adhesion forces. From this model, it is found that the capillary nucleation rate decreases from 0.00525 to 0.0000797 bridges/µm2/min as the crack heals. In turn, the capillary nucleation rate can be understood via a thermal activation process in which the activation energy depends on the local asperity gap. We will test this model by measuring crack healing rates at different temperatures and humidity levels. Capillary formation is important in nature (granular materials, insect locomotion) and in technology (disk drives, adhesion), and the methodology described here enables us to measure and study capillary bridge nucleation rates.
10:30 AM - XX1.04
MEMS Reliability as a Function of Loading Spectrum and Component Geometry
Robert Cook 1 Frank DelRio 1 Michael Gaither 1 Rebecca Kirkpatrick 1 William Osborn 1 Richard Gates 1
1National Institute of Standards and Technology Gaithersburg USAShow Abstract
The NIST microscale “theta” specimen, which is shaped like the Greek letter Θ, acts as a mechanical test specimen when loaded in compression; generating tensile stress in the central web of the specimen or bending stress in the outer frame. MEMS-scale lithographic and etching processes can be used to microfabricate many specimens such that statistically-relevant numbers of strength tests can be performed for MEMS device reliability predictions. Here, the tensile strength distributions of Si specimens resulting from different etch recipes are used to predict reliability in two different ways. In the first, the ability of a component to support a required load over a specified lifetime is considered: The loading spectrum applied to a component is varied, and the proportion of intact components remaining as a function of time is determined. Both explicit and stochastic variations of the maximum applied stress with time are demonstrated. In the second, the effect of a change in component loading geometry is considered: The specimen geometry is altered and the proportion of intact components remaining as a function of applied load is determined. In both approaches, the theta specimen is used to great effect to gain quantitative insight into the role of etching-induced surface features on the manufacturing yield and operational reliability of MEMS components.
10:45 AM - XX1.05
On-Chip Testing and Characterization of Polysilicon Thin Films Fracture Mechanisms
Renaud Vayrette 1 2 Montserrat Galceran 3 4 Stephane Godet 3 Jean-Pierre Raskin 2 5 Thomas Pardoen 1 5
1Universitamp;#233; catholique de Louvain Louvain-la-Neuve Belgium2Universitamp;#233; catholique de Louvain Louvain-la-Neuve Belgium3Universitamp;#233; Libre de Bruxelles Brussels Belgium4CIC Energigune Minano Spain5Universitamp;#233; catholique de Louvain Louvain-la-Neuve BelgiumShow Abstract
The characterization and understanding of the mechanical response of freestanding nano-objects are of prime interest for fundamental research and for supporting reliability analysis of various Micro- and NanoElectroMechanical Systems (MEMS/NEMS). A versatile on-chip mechanical testing platform has been developed using MEMS-based structures in order to explore the mechanical properties of freestanding nano-objects. These structures take advantage of the mismatch stress present in a long silicon nitride beam to apply a deformation to a specimen beam attached to it owing to the release of the underneath sacrificial layer. The connection between the both beams is ensured by an overlap. At the specimen beam ends, dogbone shapes are located to concentrate the loading where the width is uniform. The in-plane dimensions of both, the actuator and the specimen beams, are varied to induce different strains and stress levels. Then, a large range of deformation can be applied to the specimen allowing the extraction of the strain-stress curve as well as the creep/relaxation behavior. Thousands of tests can be performed using a single processed wafer making statistical data analysis possible. The specimen stress and strain are extracted from the measured total displacement of the structure after its release using an analytical model based on beam theory.
Recently, in order to improve the accuracy of the stress and strain estimation, additional geometrical and material features contributing to the total displacement of the structure have been implemented into the analytical model. These geometrical features are the specimen dogbones, the overlap between the actuator and specimen, and the under etching of the specimen and actuator fixed parts after the structures release. The presence of a stress gradient in the actuator constitutes an additional feature that must be taken into account. 3D finite elements simulations have been performed to evaluate the improved model precision and to determine what extent these additional features have to be considered or neglected.
The technique has been used to study the deformation and fracture of phosphorus-doped polysilicon thin films. Two different film thicknesses have been tested: 240 and 40 nm. The Young&’s modulus and the fracture strain have been extracted. For the two film thicknesses, the fracture strain increases with decrease specimen surface area. The thinnest film exhibits the lowest fracture strains. More surprising, post mortem analyses of broken samples reveal a change of fracture mode between the two film thicknesses, from transgranular to intergranular. The fracture strain difference and the fracture mode change observed between the two films thicknesses will be discussed in the light of surface roughness and microstructural characterization using the ACOM-TEM method.
XX2: Chemical and Biological Systems
Monday AM, December 02, 2013
Sheraton, 3rd Floor, Fairfax A
11:30 AM - *XX2.01
Microscale Manipulation of Cells and Their Environment for Cell Sorting and Stem Cell Biology
Joel Voldman 1
1MIT Cambridge USAShow Abstract
Microsystems have the potential to impact biology by providing new ways to manipulate cells and the microenvironment around them. Simply physically manipulating cells or their environment—using microfluidics, electric fields, or optical forces—provides new ways to separate cells and organize cell-cell interactions. One example illustrating the power of microscale manipulation of cells is to sort cells based on their intrinsic electrical properties. Electrical properties have previously been correlated with important biological phenotypes (apoptosis, cancer, etc.), but a sensitive and specific method approach has been lacking. We have developed a method called iso-dielectric separation that uses electric fields to drive cells to the point in a conductivity gradient where they become electrically transparent, resulting in a continuous separation method specific to electrical properties. With this method, we have screened the entire genome of an organism to understand the biological basis of electrical properties, finding that the relationship between genetics and intrinsic properties has both intuitive and non-intuitive features. We have also applied those results to develop a point-of-care assay for immune cell activation for monitoring sepsis. Microfluidics can also be used to manipulate the environment around cells. For example, we have developed arrays of microfluidic perfusion culture chambers that use fluid flow to create a convection-dominated transport environment, allowing control over local cell-cell diffusible signaling. This in turn provides a more controlled soluble microenvironment in which to study diffusible signaling in cell systems. In particular, we have examined the impact of diffusible signaling on self-renewal and neural specification of embryonic stem cells. Using these microsystems, we have identified the existence of previously unknown autocrine loops involved in fate specification, and have delineated the effects of shear itself on self-renewal. Together, these new microscale tools provide ways to exploit cells&’ potential for both basic science and applied biotechnology.
12:00 PM - XX2.02
Solvent Immersion Lithography Based on Directed Polymer Disolution for Prototyping Microfluidics and Optofluidics
Andreas E. Vasdekis 1 Michael J Wilkins 1 Jay W Grate 1 Alan E. Konopka 1 Sotiris S. Xantheas 1 Tsun Mei Chang 2
1Pacific Northwest National Laboratory Richland USA2University of Wisconsin-Parkside 2000, Kenosha USAShow Abstract
We present a new method for prototyping polymer microsystems, termed as Solvent Immersion Lithography (SIL)  that enables ultra-fast polymer imprinting, and bonding; for example, a complete assembly of a microfluidic system can be typically achieved in less than one minute, and under minimal instrumentation requirements. SIL is based on directed polymer disolution, induced by immersing a polymer into a favourable solvent. The same immersion step enables also the penetration of molecules mixed with the solvent into the polymer walls. This leads to channel surface functionalization, and adds novel functions to the imprinted features such as catalytic or sensing capabilities. Microfluidics , optofluidics , cell growth microreactors, as well as microstructured oxygen sensors prototyped by SIL will be discussed.
In directed polymer dissolution, the solvent penetrates into a polymer film at depths determined by the underlying polymer-solvent interactions . This type of interaction generates a surface gel that can be imprinted and subsequently irreversibly bonded with non-treated surfaces. The imprinting depth can be controlled through the compatibility between the solvent and polymer solubility parameters, as well as using solvent mixtures. In this talk we will focus on polystyrene and various organic solvents, as well as water-solvent mixtures. The latter was found to inhibit imprinting even at minute amounts of water, hence giving rise to another, and tightly regulated imprinting mechanism. These effects were analyzed in detail using surface chemical imaging, such as micro-Raman and confocal microscopy, as well as computational methods .
The details and performance of SIL will be presented, along with microfluidic and optofluidic applications. Regarding optofluidics, oxygen sensing moieties were integrated in the imprinted surfaces of a microfluidic channel, enabling the monitoring of oxygen concentrations within. Furthermore, as an example in microbiology, the growth of pure and mixed microbial populations was investigated in polystyrene micro-pore scale models. In these, a double mean generation lifetime was revealed for the thermophile anaerobe cellulose fermenter Clostridium Thermocellum  than under ideal culture conditions.
 A. E. Vasdekis, et al. under consideration (2013).
 G. M. Whitesides, Nature 442, 368 (2006).
 D. Psaltis, S. R. Quake, C. Yang, Nature 442, 381 (2006).
 E. Kim,, Y. N. Xia, X. M. Zhao, G. M. Whitesides Advanced Materials 9, 651 (1997).
 A. L. Demain, M. Newcomb, J. H. D. Wu, Microbiology and Molecular Biology Reviews 69 124 (2005).
12:15 PM - XX2.03
Blood Plasma Biomarker Separation Using a MEMS Device Integrated with a Vertically Aligned Carbon Nanotube Membrane
Yin-Ting Yeh 1 Nestor Perea-Lopez 2 Archi Dasgupta 3 Ramdane Harouaka 1 Mauricio Terrones 2 4 5 Siyang Zheng 1 5
1The Pennsylvania State University University Park USA2The Pennsylvania State University University Park USA3The Pennsylvania State University University Park USA4The Pennsylvania State University University Park USA5The Pennsylvania State University University Park USAShow Abstract
We have developed a MEMS filtration device fabricated with patterned vertically aligned carbon nanotubes (VACNT) and polydimethylsiloxane (PDMS). The microfluidic channel wall of the droplet-shaped device is made of a VACNT forest in the dimension of 50 µm in height, ~10^7 counts/cm^2 in density and 15 nm in single VACNT diameter. The VACNT is synthesized by aerosol based chemical vapor deposition on a patterned Fe catalyst thin film. The Fe catalyst is deposited on a silicon substrate and patterned by lift-off fabrication in droplet geometry. The top PDMS cover is fabricated by SU-8 molding technique with two fluidic access through holes, one inlet and one outlet. Oxygen plasma surface treatment is applied on both PDMS and VACNT to achieve permanent bonding and sealing. The dead-end filtration is performed in the assembled device. The inlet port is established as a sample reservoir. The outlet port is connected to vacuum source with a sample collection trap. The sample at the inlet reservoir is driven by vacuum source connected outlet and transported through the filtration membrane. The membrane is characterized to have permeability of ~10^14 m^2, porosity of ~99.6% and cut-off size of ~124 nm. The measured permeability and porosity match with the theoretical estimation by Darcy's model at the same order of magnitude. The cut-off size is estimated by combining flow resistance experimental data to a VACNT forest geometrical model, and later confirmed to be within the range of 110-140 nm with filtration experiments using fluorescently labeled nanoparticles of different sizes. The membrane is able to achieve high throughput nano-scale liquid filtration due to its high porosity and nanometer range cut-off size. Furthermore, we demonstrate the blood albumin measurement after plasma separation from human whole blood. The results show that plasma from the blood can be extracted and collected at outlet vacuum trap while the blood cells are blocked and confined at the enclosed droplet chamber. The measured blood albumin concentration matches with that measured after conventional plasma extraction by centrifugation.
12:30 PM - XX2.04
Ultrahigh Speed Rotary Nanomotors Assembled from Nanoscale Building Blocks
Kwanoh Kim 1 Donglei Fan 1 2
1the University of Texas at Austin Austin USA2the University of Texas at Austin Austin USAShow Abstract
Rotary nanomotors, a critical but less developed type of NEMS devices, is extremely important for further advancing NEMS technology. In this work, we report innovative design, assembly, and rotation of ordered arrays of nanomotors. The nanomotors were bottom-up assembled from nanoscale building blocks with nanowires as rotors, patterned nanomagnets as bearings, and quadrupole microelectrodes as stators. Arrays of nanomotors can be synchronously rotated with controlled angle, speed (to at least 18,000 rpm), and chirality by electric fields. The fundamental nanoscale electrical, mechanical, and magnetic interactions in the nanomotor system were investigated, which adds new knowledge and understanding for design of various metallic NEMS devices. The innovations from concept, design, to actuation are on multi-levels and may bring transformative impact to NEMS, microfluidics, and lab-on-chip architectures.
12:45 PM - XX2.05
High Resolution Position Monitoring of Suspended MEMS towards Biological and Chemical Sensors
G. Putrino 1 Mariusz Martyniuk 1 A. Keating 2 J. M. Dell 1 L. Faraone 1
1The University of Western Australia Crawley Australia2The University of Western Australia Crawley AustraliaShow Abstract
MEMS-based biological and chemical sensors have gained increasing attention due to their ability to provide a technique for high-precision (zepto-gram), label-free sensing. However, to date, the widespread application of this class of sensors has been impeded in part by the lack of a technology capable of performing high resolution measurements of large arrays of MEMS devices. We present an experimental demonstration of a technology capable of filling that need.
MEMS-based sensors consist of either free-standing microcantilevers or microbridges, coated in a functionalization substance which preferentially bonds to the chemicals being searched for. MEMS sensors have two modes of operation: static (where height position is measured) and dynamic (where resonance frequency is measured). To measure the state of the cantilevers, our design integrates a silicon photonics waveguide and diffraction grating beneath the sensing cantilever. By making the underside of the cantilever reflective, a resonant optical micro-cavity is formed beneath the cantilever. The amount of light coupled back into the waveguide from the grating is an extremely sensitive measure of the position of the cantilever.
Silicon photonics optical components were fabricated using deep ultra-violet (DUV) lithography. Microcantilevers were then fabricated above these components using surface micromachining. The optical output from the waveguide was measured as a function of the height of the suspended microcantilever.
The measurements show that the position of the suspended MEMS is measured with accuracy of single picometers. We have demonstrated the measurement of the first two harmonics of cantilever resonant mechanical motion that is thermally stimulated at room-temperature.