Wenzhuo Wu, Purdue University
Christian Falconi, University of Tor Vergata
Rusen Yang, University of Minnesota
Junyi Zhai, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences
ES4.1: Triboelectric Nanogenerators I
Monday PM, April 17, 2017
PCC North, 200 Level, Room 229 A
2:30 PM - *ES4.1.01
Nanogenerator for Self-Powered Systems and Large-Scale Blue Energy
Zhong Lin Wang 1 2 Show Abstract
1 , Georgia Institute of Technology, Atlanta, Georgia, United States, 2 , Beijing Institute of Nanoenergy and Nanosystems, CAS, Beijing China
Triboelectrification is an effect that is known to each and every one probably ever since the ancient Greek time, but it is usually taken as a negative effect and is avoided in many technologies. We have recently invented a triboelectric nanogenerator (TENG) that is used to convert mechanical energy into electricity by a conjunction of triboelectrification and electrostatic induction. As for this power generation unit, in the inner circuit, a potential is created by the triboelectric effect due to the charge transfer between two thin organic/inorganic films that exhibit opposite tribo-polarity; in the outer circuit, electrons are driven to flow between two electrodes attached on the back sides of the films in order to balance the potential. Ever since the first report of the TENG in January 2012, the output power density of TENG has been improved for five orders of magnitude within 12 months. The area power density reaches 500 W/m2, volume density reaches 490 kW/m3, and a conversion efficiency of ~50% has been demonstrated. The TENG can be applied to harvest all kind mechanical energy that is available but wasted in our daily life, such as human motion, walking, vibration, mechanical triggering, rotating tire, wind, flowing water and more. Alternatively, TENG can also be used as a self-powered sensor for actively detecting the static and dynamic processes arising from mechanical agitation using the voltage and current output signals of the TENG, respectively, with potential applications for touch pad and smart skin technologies. The TENG is possible not only for self-powered portable electronics, but also as a new energy technology with a potential of contributing to the world energy in the near future.
 Z.L. Wang “Triboelectric Nanogenerators as New Energy Technology for Self-Powered Systems and as Active Mechanical and Chemical Sensors”, ACS Nano 7 (2013) 9533-9557.
 G. Zhu, J. Chen, T. Zhang, Q. Jing, Z. L. Wang* “Radial-arrayed rotary electrification for high-performance triboelectric generator”, Nature Communication, 5 (2014) 3456.
 Zhong Lin Wang,* Jun Chen, Long Lin “Progress in triboelectric nanogenertors as new energy technology and self-powered sensors” (invited review), Energy & Environmental Sci, 8 (2015) 2250-2282.
3:00 PM - ES4.1.02
Hybrid Generators with Cascaded Piezoelectric and Triboelectric Units—Design, Fabrication, Testing and Analysis
Song Chen 1 , Xiaoming Tao 1 , Wei Zeng 1 , Bao Yang 1 , Songmin Shang 1 Show Abstract
1 , Hong Kong Polytech University, Kowloon Hong Kong
Harvesting mechanical energy is a promising approach for maintenance free, self-powered systems in wearable and portable electronics 1,2,3,4. New hybrid generators (HGs) with much enhanced piezoelectricity were designed and fabricated via a simple, room-temperature, cost-effective route by using nonwoven fabrics made from electro-spun PVDF-TrFE /Ag nanowires nanofibers (PTAN), and PDMS composites with graphite nanoparticles as the active layers, thus the effects of piezoelectricity and triboelectricity are combined into a single HG. The inclusion of Ag nanowires promoted the formation of the β-phase crystals and enhanced piezoelectricity of the PTAN nanofibers. With a 3 Hz cyclic compression force, the peak voltage and average power output of the HG reached 190V and 16.46μW, respectively. Moreover, this new approach is effective to significantly improve power output of the constitutive units as well as the HG by using conductive fillers in the composites for piezoelectric layer or dielectric layer with increased respective dielectric constants and low dielectric loss. Superposition of the piezoelectric and triboelectric outputs is evident at all five separate working stages during one compression cycle. The noticeably high power output of the HG can be used as a power source in wearable electronics to extend the life of battery.
Similar to the analysis of triboelectric generators 5, the mechanical deformation process of the HG has been related to the charge generation and induction transfer processes. For the first time, a theoretical analysis of the contact-mode hybrid generator has been developed to describe the relationships among transfer charges, voltage, current and average output power in terms of materials parameters, HG structural parameters, harvesting and operational conditions. The theoretical analysis would provide a powerful tool for material synthesis and selection, design and optimization of the configuration and operation of hybrid generators as well as the value of external capacitor.
The work has been partially supported by Research Grants Council of Hong Kong SAR Government (Grant No. 525113, 15215214,1521016).
1. Wang ZL, Lin L, Chen J, Niu S, Zi Y, 2016. Triboelectric Nanogenerators, Springer International Publishing, 2016.
2. Tao XM, 2015. Handbook of Smart Textiles, Springer International Publishing. 2015.
3. Zeng W, Shu L, Li Q, Chen S, Wang F, Tao XM, 2014. F, Advanced Materials. 26(31):5310-5336, DOI: 10.1002/adma.201400633.
4. Zeng W, Tao XM, Chen S, Shang SM, Chan Wong LW, Choy SH, 2013. Energy and Environmental Science, 6 (9), 2631 – 2638.
5. Yang B, Zeng W, Peng ZH, Liu SR, Chen K, Tao XM, 2016. Advanced Energy Materials, 6(16) DOI: 10.1002/aenm.201600505.
6. Chen S, Tao XM, Zeng W, Yang B, Shang SM, 2016. Advanced Energy Materials, accepted.
3:15 PM - *ES4.1.03
Triboelectrification of Graphene for Triboelectric Nanogenerators and Tribotronics
Sang-Woo Kim 1 Show Abstract
1 , Sungkyunkwan University, Suwon Korea (the Republic of)
As the first issue, I will present about the demonstration of large electric power generation from a single moving water droplet on a monolayer graphene, producing an output power of about 1.9 μW, which is about 100 times larger than the power output achieved in previous reports. This result is explained to be a result of the change in triboelectrification-induced pseudocapacitance between a water droplet and the monolayer graphene on polytetrafluoroethylene (PTFE). Positive and negative charges were found to respectively accumulate at the bottom and top surfaces of graphene on PTFE by the triboelectric potential generated during the graphene transfer process. The negative charges accumulate onto the top surface of the graphene and are driven forward by the moving droplet, charging and discharging at the front and rear of the droplet. As the second topic, I am going to introduce a graphene tribotronic touch sensor which is based on coplanar coupling of a single electrode mode triboelectric nanogenerator (S-TENG) and a graphene FET. When any object (e.g. human finger) comes into contact with friction layer of the S-TENG, the charges are produced due to well-known triboelectric effect. The triboelectric charges acts as a gate bias to the graphene FET and modulates its current transport. The tribotronic transistor therefore does not require any external gate voltage as in traditional metal oxide field effect transistors. The tribotronic sensors have displayed a sensitivity of ~2% kPa-1, a limit of detection <1 kPa, and a response time of ~30 ms. Furthermore, the devices can effectively detect touch stimuli from both bare and gloved fingers which can be a limitation with capacitive touch screens. Due to all these features, the graphene tribotronic devices are an ideal candidate for electronic skins (e-skins) and touch screens.
3:45 PM - ES4.1.04
Recyclable, Green Triboelectric Nanogenerator and Its Application as Clearable Self-Powered Motion Sensor
Qijie Liang 1 , Xiaoqin Yan 1 , Qian Zhang 1 , Yue Zhang 1 Show Abstract
1 , University of Science and Technology, Beijing, Beijing China
In this work, we successfully developed a fast soluble, recyclable and green triboelectric nanogenerator based on triboelectrification and cascade reactions. All the components are water-soluble or can be dissolved by water-triggered cascade reaction. The entire device get fully disintegrated and dissolved with a transience time within minutes once the external trigger of water commences. Moreover, it can be reproduced with the generated solution with no waste released to environment. The properties of the reproduced membranes and the performance of the reproduced devices were systematically investigated. Furthermore, triboelectric nanogenerators working under four modes were fabricated, revealing the wide potential applications of integrating with other electronics. The developed triboelectric nanogenerator exhibited excellent performance of scavenging mechanical energy from environment. We also demonstrated its potential applications on self-powered nanosensors for health monitoring and motion sensing. The fast soluble triboelectric nanogenerator in this work renders as a promising power solution for biomedical implants, environmental monitoring and secure electronics and will push forward the development of self-powered nanosensor and green electronics.
ES4.2: Piezotronics I
Monday PM, April 17, 2017
PCC North, 200 Level, Room 229 A
4:15 PM - *ES4.2.01
The Photochemical Properties of Polar Surface Domains on Non-Polar Surfaces
Gregory Rohrer 1 , Paul Salvador 1 Show Abstract
1 , Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Polar semiconductors have recently received significant attention because their internal fields separate photogenerated electron-hole pairs and reduce recombination. On surfaces with polar domains, electrons are attracted to positively terminated domains where they promote reduction reactions and holes are attracted to negatively charged domains where they promote oxidation. We have found that polar domains can be created on the surfaces of non-polar materials, including BiVO4, WO3, and SrTiO3. In the cases, of WO3 and BiVO4, polarity arises from the flexoelectric effect. On SrTiO3, polarity arises from polar terminations on different terraces. For SrTiO3, it is possible to control the fraction of the surface terminated by positive or negative charges by annealing the surfaces in environments with an excess or deficit of strontium. In this talk, we will describe photochemical reactions on the surfaces of materials with polar domains and discuss opportunities to exploit polar domains in materials where they are not expected on the basis of the known bulk properties.
4:45 PM - *ES4.2.02
Piezo-Phototronics in Opto-Electronics and Its Application in Visible Strain Mapping of Robotics
Caofeng Pan 1 , Xun Han 1 Show Abstract
1 Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing China
Emulation of human senses via electronic means has long been a grand challenge in research of artificial intelligence as well as prosthetics, and is of pivotal importance for developing intelligently accessible and natural interfaces between human/environment and machine. In this talk, we present a novel design of ZnO nanowire arrays, which can be used to directly record the strain distribution by piezotronic and piezo-phototronic effect.
First, we demonstrated how the piezo-phototronic effect can be effectively utilized to enhance the emission intensity of an n-ZnO/p-GaN NW LED. The emission light intensity and injection current at a fixed applied voltage has been enhanced by a factor of 17 and 4 after applying a 0.093% compressive strain, respectively. Then, we extend the single NW device to NW LEDs array, for pressure/force sensor arrays for mapping strain with a resolution as high as 2.7 μm. Such sensors are capable of recording spatial profiles of pressure distribution, and the tactile pixel area density of our device array is 6250000/cm2, which is much higher than the number of tactile sensors in recent reports (~ 6-27/cm2) and mechanoreceptors embedded in the human fingertip skins (~ 240/cm2).
Lastly, the piezo-phototronic effect was achieved on Si wafer based on a n-ZnO nanofilm/p-Si micropillar heterostructure (ZSH) LEDs array. By applying a strain onto the top of the ZSH LEDs, the light emission intensity of ZSH LEDs array was enhanced as well by 120% under -0.05% compressive strains. A pressure map can be created by reading out in parallel the change of the electroluminescent intensities from all the pixels in the near future. This research not only introduce a novel approach to fabricate Si-based light-emitting components with high performances, but also may be a great step toward digital imaging of mechanical signals using optical means, having potential applications in artificial skin, touch pad technology, personalized signatures, bio-imaging and optical MEMS, and even and smart skin.
5:15 PM - ES4.2.03
Self-Assembly of Diphenylalanine Peptide with Controlled Polarization for Power Generation
Vu Nguyen 1 , Ren Zhu 1 , Kory Jenkins 1 , Rusen Yang 1 Show Abstract
1 , University of Minnesota, Minneapolis, Minnesota, United States
Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition, and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and un-switchable polarization has been the road-block to fulfilling its potentials and the demonstration of a piezoelectric device is still lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V-1. We experimentally demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm-2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.
5:30 PM - *ES4.2.04
Ferret—An Open-Source Code for Simulating Thermodynamical Evolution and Phase Transformations in Complex Materials Systems at Mesoscale
Serge Nakhmanson 1 Show Abstract
1 Materials Science and Engineering, University of Connecticut, Storrs, Connecticut, United States
Ferret is an open-source highly scalable real-space finite-element-method (FEM) based code for simulating transitional behavior of materials systems with coupled physical properties at mesoscale. This code is built on MOOSE, Multiphysics Object Oriented Simulation Environment, and is being developed by a team of collaborators at the University of Connecticut and Argonne National Laboratory. In this presentation we provide an overview of computational approach utilized by the code, as well as its technical features and the associated software within our computational tool chain, including structural model and mesh generator, and visualization facilities. We also highlight a variety of examples of the code applications, some of which are being pursued in collaboration with a number of different experimental groups. These applications include (a) evaluations of size- and microstructure-dependent elastic and optical properties of core-shell nanoparticles, including Zn/ZnO and ZnO/TiO2 core/shell material combinations; (b) modeling of the influence of shape, size and elastic distortions of monolythic ZnO and Zn/ZnO core/shell nanowires on their optical properties; (c) studies of the properties and domain-wall dynamics in perovskite-ferroelectric films, nanowires and nanoridges, and (d) investigation of transitional behavior and topological phases in ferroelectric nanoinclusions embedded in a dielectic matrix. Finally, we showcase the resuls of our efforts to parameterize the coarse-grained thermodynamical expressions used by Ferret with the help of first-principles simulations, including different strategies for fitting Landau-type energy functionals for perovskite structures.
Wenzhuo Wu, Purdue University
Christian Falconi, University of Tor Vergata
Rusen Yang, University of Minnesota
Junyi Zhai, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences
ES4.3: Piezoelectric Nanogenerators I
Tuesday AM, April 18, 2017
PCC North, 200 Level, Room 229 A
11:30 AM - *ES4.3.01
Ferroelectric Polymer for Energy Harvesting and Self-Powered Devices/Sensors
Pooi See Lee 1 , Kaushik Parida 1 , Venkatswarlu Bhavanasi 1 Show Abstract
1 School of Materials Science and Engineering, Nanyang Technological University, Singapore Singapore
Mechanical/vibrational energy harvesting has drawn interests in recent years because of its potential in energy generation and self-powered sensors/ devices. The mechanical energy can be harvested efficiently by using piezoelectric and triboelectric mechanisms. Poly (vinylidene difluoride-trifluoroethylene) [PVDF-TrFE] is a functional polymer with ferroelectric, piezoelectric and triboelectric behavior. Piezoelectric polymers typically sustains higher strains and strain rates compared to its inorganic counterparts making it suitable for the mechanical energy harvesting. Yet the piezoelectric energy harvesting ability of PVDF-TrFE is lower because of its lower piezoelectric coefficient and Young’s modulus. In this talk, I will discuss various approaches taken to improve the energy harvesting ability of PVDF-TrFE polymer such as improving the piezoelectric coefficients, compressibility and incoporation of electrostatic effects. 1-D nanostructuring leads to the improved piezoelectric coefficients of PVDF-TrFE (44 pm/V, two times higher than the films) and hence an improved mechanical energy harvesting properties. Porous PVDF-TrFE films can be fabricated to improve the compressibility of the PVDF-TrFE and therefore the energy harvesting ability. Furthermore, we utilized these porous piezoelectric films to realize fast charging self-powered supercapacitor, with 90% of its charging potential achieved in less than 10 sec. We have found that bi-layer film based on PVDF-TrFE and graphene oxide leads to both enhanced piezoelectric and electrostatic effects, while elevating the Young’s modulus and creating a residual stress (or stress gradient) in the films, leading to the improved energy harvesting performance.
In addition to the piezoelectric phenomenon, PVDF-TrFE is utilized for triboelectric energy harvesting by utilizing its functional properties. By tuning the polarization, we realized a good triboelectric transparent negative material. A wide range self-powered pressure sensor and an energy harvester utilizing triboelectric phenomenon can be built based on PVDF-TrFE. The efforts illustrated lead to the pathways of realizing futuristic self-powered devices and sensors in addition to clean energy generation.
12:00 PM - ES4.3.02
Smart Fibers for Textile-Based Micro-Generators and Compliant Energy Storage
Xin Lu 1 , Hang Qu 1 , Maksim Skorobogatiy 1 Show Abstract
1 , Ecole Polytechnique de Montreal, Montreal, Quebec, Canada
In the past decade, the R&D of micro-generators based on flexible piezoelectric fibers has received intensive attention due to the boosting market of personal wearable electronics. In previous works, piezoelectric fibers are normally fabricated by two routes. In the first one, ceramic piezoelectric materials such as ZnO Nanowires (NWs) or BaTiO3 NWs are directly deposited or wet-extruded along a metallic wire/filament. While the fabrication process is simple, the as-fabricated fibers normally have reliability issues, as the bonding between the ceramic materials and the metallic core is weak, especially when the fibers are subject to repeated bending or stretching actions. The second route is based on traditional polymer wet-spinning or melt-spinning techniques in which piezoelectric polymers such as PVDF or PVDF-TrFE are extruded together with a conductive polymer to form a sheath-core fiber structure. Note that the as-spun fibers may require an additional deposition of a metallic layer as an outer electrode that may also have reliability problems due to surface abrasion and frequent bending actions.
In this abstract, we report fabrication of the multimaterial piezoelectric fibers from perovskite ceramic nanoparticles (BTO/PZT)-PVDF, and CNT-PVDF composites via fiber drawing. Furthermore, we perform a comparative study of the piezoelectric performance of thus fabricated fibers. The proposed fibers feature a spiral geometry that significantly increases the fiber piezoelectric response. Due to the judicious arrangement of the conductive layers, connecting to our fibers is easy as the two electrodes occupy the opposite sides of the exposed fiber surface. Experimentally, a piezoelectric generator using a 10 cm long BTO-PVDF (BTO concentration: 20 wt%) fiber could generate an open-circuit voltage of 1.4 V and a short-circuit current of 0.8 nA respectively, when the fiber tip is displaced transversely by 10 mm. The corresponding voltage and current were ~6 V and ~4 nA for a PZT-PVDF (20 wt% PZT) fiber generator, and ~3 V and ~1.2 nA for a CNT-PVDF (0.4 wt% CNT) fiber generator. Compared to the previous piezoelectric fibers, our fibers adopt a spiral structure, and thus have much larger active areas for piezoelectricity generation as well as smaller gaps between the electrodes. As a result, our fibers could generate much higher piezoelectric currents, which are proportional to the number of turns in a spiral. Among other advantages of the piezoelectric fibers reported in this paper are low cost of the materials used in fabrication, light weight, good durability, and possibility of mass production via fiber drawing.As examples of practical applications of the proposed piezoelectric fibers, we present energy harvesting textiles using BTO-PVDF fibers, and characterized their performance in the context of wearable and automotive microgenerators. Moreover, we also present detection of sound using CNT-PVDF fiber that feature piezoelectric voltage generated by sound wave to be proportional to the square root of the acoustic power.
Reference X. Lu, H. Qu and M. Skorobogatiy.“Piezoelectric Microstructured Fibers Fabricated from Thermoplastic Nanocomposites using Fiber Drawing Technique-Comparative Study and Potential Applications”, ACS Nano, in Press (2017).
12:15 PM - *ES4.3.03
Polymer-Based Nanogenerators for Piezoelectric and Triboelectric Energy Harvesting Applications
Sohini Kar-Narayan 1 Show Abstract
1 , University of Cambridge, Cambridge United Kingdom
Harvesting energy from ambient mechanical sources in our environment has generated tremendous interest as it offers a fundamental energy solution for ‘small power’ applications, including but not limited to wireless sensors. In this context, piezoelectric and/or triboelectric materials offer the simplest means of directly converting mechanical vibrations, from sources such as moving parts of machines, fluid flow and even body movements, into electrical power for microscale device applications. In particular, nanoscale energy harvesters, or nanogenerators, are capable of converting low-level ambient vibrations into electrical energy, thus paving the way for the realisation of the next generation of self-powered devices. Polymer-based nanogenerators are attractive as they are inherently flexible and robust making them less prone to mechanical failure which is a key requirement for vibrational energy harvesters. They are also lightweight, easy and cheap to fabricate, lead free and biocompatible, but their energy harvesting performance is often found lacking in comparison to more commonly studied inorganic materials. Our group thus develops scalable nanofabrication techniques for flexible and low-cost polymer-based nanogenerators with improved energy conversion efficiency, by using facile template-assisted nanowire growth techniques. In this talk, I will discuss our recent advances in incorporating nanowires of P(VDF-TrFE), Nylon-11, cellulose and poly-lactic acid into scalable piezoelectric and triboelectric nanogenerators, as well as the design and performance of polymer-ceramic nanocomposite nanogenerators. I will also focus on advanced scanning probe microscopy methods that we use for the characterization of these polymeric nanomaterials and the extraction of relevant materials properties for nanogenerator design.
12:45 PM - ES4.3.04
Machine-Washable Textile Triboelectric Nanogenerators for Effective Human Respiratory Monitoring through Loom Weaving of Metallic Yarns
Zhizhen Zhao 1 , Casey Yan 2 , Youfan Hu 1 , Zijian Zheng 2 Show Abstract
1 , Peking University, Peking China, 2 , The Hong Kong Polytechnic University, Hong Kong Hong Kong
With rapid growth in performance and materials of nanogenerators, comfortable and convenient energy harvesting along with useful self-powered sensing become close to our daily life. In the meanwhile, wearable technology has attracted huge attention because it satisfies both human body information collecting and comfortable clothing. Recently, textile triboelectric nanogenerators (t-TENGs) become very popular due to their ease of fabrication and promising output performance. Weaving special yarns into soft fabric makes t-TENGs lightweight, portable and flexible. Still, the bulky fabric structures, washing durability and scalability with the conventional textile manufacturing industry are critical challenges hampering further technological advances of t-TENGs. Now, a big breakthrough takes place in t-TENG which is fabricated by direct weaving of Cu-coated polyethylene terephthalate (Cu-PET) warp yarns and polyimide coated Cu-PET (PI-Cu-PET) weft yarns on an industrial sample weaving loom. The new device takes fully the advantage of the woven structure itself. Upon even very subtle deformation, such as tapping and bending, the contact area of the crisscross intersections of the weft and warp yarns changes which lead to effective generation of triboelectric charges. Electric output of voltage or current will be generated under such process. And we integrate the as-made t-TENG into a chest strap to monitor human respiratory information including rate and depth. More importantly, the as-made t-TENG can withstand the industry standard machine-wash tests, showing remarkable washing durability. It is worth noting that all the materials used here have been widely accepted by the textile industry, and the device fabrication is done with miniaturized industrial machineries, making the t-TENGs fully compatible with high-throughput textile processing. In a word, the textile industry compatibility, the proven machine wash ability, and the sensitivity to subtle human body motions make the new designed t-TENG a very promising candidate for wearable technology with excellent scalability, and can be further applied in sports, healthcare sectors and many other fields.
ES4.4: Triboelectric Nanogenerators II
Tuesday PM, April 18, 2017
PCC North, 200 Level, Room 229 A
2:30 PM - *ES4.4.01
Boosted Output Performance of Triboelectric Nanogenerator via Electric Double Layer Effect
Jeong Min Baik 1 Show Abstract
1 , Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of)
For existing triboelectric nanogenerators, it is important to explore unique methods to further enhance the electric output power under realistic environments in order to speed up its commercialization. We report here, for the first time, a new practical TENG composed of three layers, in which the key layer, an electric double layer, is inserted between a top layer, made of Al/PDMS, and a bottom layer, made of Al, respectively. The efficient charge separation in the middle layer, based on Volta’s electrophorus, is resulted from sequential contact configuration of the TENG and direct electrical connection of the middle layer to the earth (ground). This device design provides substantially larger electric potential at even low frequency regime than in previous reports. A sustainable and enhanced output performance of 1.22 mA and 46.8 mW/cm2 under low frequency of 3 Hz is produced, giving over 16-fold enhancement in output power and corresponding to energy conversion efficiency of 22.4 %. Through the integration of the TENG with a signal-processing circuit, wireless sensors such as a remote controller and an infrared sensor are demonstrated. Finally, a portable power-supplying system, which provides enough DC power for charging a battery of smart watch/phone, were also successfully developed.
3:00 PM -
3:15 PM - *ES4.4.03
Triboelectric Nanogenerator for Energy Harvesting and Self-Powered Biomechanical Motion Sensors
Qingliang Liao 1 , Fang Yi 1 , Yue Zhang 1 Show Abstract
1 , University of Science and Technology Beijing, Beijing China
The advances in industry and information technology promote the development of internet of things and sensor technology. Consequently, there is a growing need to develop power sources for sensor works that currently may include thousands or even millions of sensor nodes with various functionalities. Self-powered sensors based on energy harvesting technologies have been given significant attention with the increasing concern over energy crisis, which generally realized through two approaches: one is to drive conventional sensors by energy harvesters; the other one is to detect signals via the electrical outputs triggered by ambient environment stimulations. Triboelectric nanogenerator (TENG) is a new technology to harvest mechanical energy and has attracted attentive attention. TENGs can be utilized as self-powered sensors and have the advantages of light weight, low cost, and high sensitivity.
In this work, we introduce three kinds of TENGs to act as self-powered biomechanical motion sensors. Three kinds of TENGs with different structures were designed and the detecting properties of the fabricated biomechanical motion sensors were measured. The working mechanisms of the TENGs were investigated.
A single-electrode-mode triboelectric nanogenerator is developed to accurately detect the trajectory, displacement, velocity and acceleration of moving objects in two dimensions, which is applied to visualize the movement of a sliding object and walking steps of a person. A triboelectric nanogenerator based on a unique working principle that the changes of triboelectric charge distribution/density on the triboelectric layer inducing the polarization of charges is developed, which can serve as self-powered wearable sensors to detect diaphragm breathing and joint motion. A triboelectric nanogenerator with self-recovering characteristics is developed, which can act as self-powered sensors to detect humidity, airflow rate, force and be applied for security monitoring.
The designed three kinds of biomechanical motion sensor show excellent responsive properties. These works not only provide new design options for energy harvesters but also offer new perspectives for self-powered sensors.
3:45 PM - ES4.4.04
Tribotronics—A New Field by Coupling Triboelectricity and Semiconductor
Chi Zhang 1 , Yaokun Pang 1 , Zhong Lin Wang 1 Show Abstract
1 , Chinese Academy of Sciences, Beijing China
Recently, the invention of the triboelectric nanogenerator (TENG) has provided an effective approach to convert ambient mechanical energy into electricity, which has great application in micro-energy, macro-energy, and active sensors. On the other hand, the triboelectric induced potential difference is an inner electrical signal created by the external mechanical force, which could be used as a gate signal to tune/control the carrier transport characteristics in field effect transistor as the same effect as applying a gate voltage. In 2014, by coupling triboelectricity and semiconductor, tribotronics as a new field is proposed, which is about the devices fabricated using the electrostatic potential created by triboelectrification as a “gate” voltage to tune/control electrical transport and transformation in semiconductors.
In the past years, various tribotronic functional devices have been experimentally demonstrated. The tribotronic logic device has established the relationship between the mechanical force and CMOS logic electric level and universal combinational logic circuits have been demonstrated for first performing mechanical-electrical coupled tribotronic logic operations. The flexible organic tribotronic memory has demonstrated an active memory which can be written and erased by externally applied touch actions. The organic and MoS2 tribotronic transistors have extended the tribotronics to the organic and 2D materials, respectively, and exhibited the material variety for the interactive application. By further introducing optoelectronics, a new field of tribo-phototronics has been consequently derived by three way coupling among triboelectricity, semiconductor, and photoexcitation. The tribotronic light-emitting diode and phototransistor have been developed for demonstrating the triboelectric charges enhanced light-emission and photoelectric conversion characteristics, respectively.
Tribotronics has established a direct interaction mechanism between the external environment and electronics, which is likely to have important applications in sensors, human silicon technology interfacing, MEMS, nanorobotics, and active flexible electronics. As an extension of the proposed piezoelectric nanogenerator in 2006, piezotronics in 2007 and triboelectric nanogenerator in 2012, tribotronics is another original and novel field in the development of nano-energy and nano-electronics. The concepts and results presented in this review show promises for implementing novel micro/nano-electromechanical devices that may derive plenty of potentially important research interests and applications in sensing, energy harvesting, human-machine interfacing, MEMS/NEMS and active flexible/stretchable electronics in the near future.
ES4.5: Piezophototronics I
Tuesday PM, April 18, 2017
PCC North, 200 Level, Room 229 A
4:30 PM - *ES4.5.01
Piezotronics-Regulated Electrochemical and Catalytic Materials and Devices
Xudong Wang 1 Show Abstract
1 , University of Wisconsin, Madison, Madison, Wisconsin, United States
Recent discovery of the piezotronic effect revealed that when a strain is experienced by a piezoelectric semiconductor material or device, it can introduce interfacial charge redistribution and lead to significant performance gain or new functionality. In this talk, we will discuss the coupling of piezoelectric polarization and the intrinsic electric field in a space charge region for the purpose of tuning charge transport behaviors in Wurtzite materials. Three piezotronic-enhanced or enabled applications will be introduced as successful examples. The piezotronic effect has been applied to the ZnO/PbS quantum dot (QD) heterojunction for engineering the interfacial band structure and depletion region. This method escalated the solar energy efficiency by 30% when a relatively small strain -0.25% was applied to the QDSC under low-intensity illumination. The enhancement of short circuit current and efficiency was mostly due to the expansion of depletion region in PbS, as a result of piezoelectric polarization-induced charge redistribution at the ZnO/PbS interface. Similarly, piezotronic effect could enhance the oxygen evolution reaction (OER) in photoelectrochemical (PEC) systems. In a Ni(OH)2-decorated ZnO photoanode system, appreciably improved photocurrent density of sulfite and hydroxyl oxidation reactions were obtained by physically deflecting the photoanode. A largely enhanced performance of PEC photoanodes was also obtained by ferroelectric polarization-endowed band engineering on the basis of TiO2/BaTiO3 core/shell nanowires. Numerical model was established to calculate the potential distribution across the catalyst/piezoelectric/electrolyte heterojunction and reveal favorable electronic band bending as a result of internal piezoelectric polarization. Furthermore, the strain-induced piezopolarization can direct interact with electrochemical processes, which is denoted as the piezocatalysis effect. By straining a ferroelectric PMN-PT beam in water, we experimentally demonstrated that piezoelectric potential can raise the energy of electrons at the surface of piezoelectric material (or electrode) to such a level that is sufficient to drive proton reduction reactions within its immediate vicinity. A piezocatalyst can realize self- or remotely-activated electrochemical processes from ambient oscillations or applying acoustic waves, respectively. In summary, interfacing between piezotronics and electrochemical systems will open a new route for engineering the catalytic properties of conventional catalysts via mechanical straining.
5:00 PM - *ES4.5.02
Trions and Excitons Modulation in Two-Dimensional MoS2 by Acoustic Means
Amgad Rezk 1 , Benjamin Carey 1 , Leslie Yeo 1 , Kourosh Kalantar-zadeh 1 Show Abstract
1 , RMIT, Melbourne, New South Wales, Australia
Two-dimensional molybdenum disulfide (2D MoS2) has attracted increasing attention in recent years due to its fascinating physical and chemical properties.1-7
A very recent discovery is the observation that 2D MoS2 is by nature piezoelectric, if it contains an odd number of layers but not so in even layered configurations.7 This appears to originate from the opposite orientation of alternating layers in 2H-MoS2, resulting in an inversion symmetry breaking only in odd-numbered layers, whereas systems with an even number of layers remain centrosymmetric, losing its piezoelectric response. Wu et al.7 subsequently investigated the piezoelectric properties of one to six layered MoS2 through continuous stretching and releasing of the flakes with a strain frequency of 0.5 Hz, in which the piezoelectric coupling coefficient was estimated to be ∼5.08% for a single layer and observed to reduce significantly for 3 and 5 layers.
In this work, by exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of 2D MoS2, we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS2 using high frequency sound wave coupling.5 We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons–holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS2 using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS2 for odd-numbered layers. At larger applied powers, the thermal effect dominates the behaviour of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS2 that can be implemented in future optical and electronic systems.
1. K. J. Berean, J. Z. Ou, T. Daeneke, B. J. Carey, E. P. Nguyen, Y. Wang, S. P. Russo, R. B. Kaner and K. Kalantar-zadeh, Small 11, 5035 (2015).
2. K. Kalantar-zadeh, J. Z. Ou, T. Daeneke, M. S. Strano, M. Pumera and S. L. Gras, Adv. Funct. Mater. 25, 5086 (2015).
3. E. P. Nguyen, B. J. Carey, J. Z. Ou, J. Van Embden, E. D. Gaspera, A. F. Chrimes, M. J. S. Spencer, S. Zhuiykov, K. Kalantar-zadeh and T. Daeneke, Adv. Mater. 27, 6225 (2015).
4. J. Z. Ou, A. F. Chrimes, Y. Wang, S. Y. Tang, M. S. Strano and K. Kalantar-zadeh, Nano Lett. 14, 857 (2014).
5. A. R. Rezk, B. Carey, A. F. Chrimes, D. W. M. Lau, B. C. Gibson, C. Zheng, M. S. Fuhrer, L. Y. Yeo and K. Kalantar-zadeh, Nano Lett. 16, 849 (2016).
6. Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman and M. S. Strano, Nat. Nanotech. 7, 699 (2012).
7. W. Wu, L. Wang, Y. Li, F. Zhang, L. Lin, S. Niu, D. Chenet, X. Zhang, Y. Hao, T. F. Heinz, J. Hone and Z. L. Wang, Nature 514, 470 (2014).
5:30 PM - *ES4.5.03
Achieving Ultrahigh UV Responsivity of Single Nonpolar A-Axial GaN Nanowire with Asymmetric Piezopotential Distribution via Piezo-Phototronic Effect under Optimized Strain
Chuan-Pu Liu 1 , Chen-Yu Tsai 1 , Kapil Gupta 1 Show Abstract
1 , National Cheng Kung Univ, Tainan Taiwan
Intuitively, piezotronics effect is widely expected to facilitate the optimization process by fine tuning Schottky barrier height (SBH) with external stress through piezopotential. However, piezopotential distribution will definitely interact with free carriers and optimally affect the distribution of free carriers and thus piezopotential itself dynamically. The interplay can be even complicated by the excess carriers excited by lights of various powers. The dynamic coupling between stress-induced piezopotential distribution and light-induced carrier concentration distribution under the field of piezo-phototronics seems to be a daunting task and still lacks of complete understanding experimentally.
In present study, the interplay among the external strain, light illumination and intrinsic carrier concentration representing piezo-phototronic coupling is systematically and quantitatively examined. A comprehensive analysis on the dependence of the carrier screening effect on both the strain-induced SBH and carrier trapping effect, induced by the unique piezopotential distribution in a strained a-axial GaN NW, has been performed. In this study, when applying an optimum tensile strain of 0.012% on an a-axis GaN NW with a carrier concentration of 6.2×1017cm-3, we demonstrate the highest UV responsivity of 1.3x105 (A/W) under the illumination intensity of 39.36 mW/cm2. The nonlinear responsivity enhancement under strain is explained by the competition between the SBH lowering effect and carrier trapping effect induced by the unique piezopotential distribution in a single strained a-axial GaN NW. Therefore, this work provides a new design rule for better utilizing piezopotential in coupling with light to achieve the highest performance in optoelectric devices incorporating piezo-phototronics. The results from this study suggest that a-axial GaN NWs hold promise for use in high performance piezotronic- or piezo-phototronic-based sensors.
ES4.6: Poster Session I: Nanogenerators and Piezotronics
Tuesday PM, April 18, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - ES4.6.01
Mechanoluminescence Color Conversion from ZnS-Embedded-Polydimethylsiloxane Elastomer Functionalized with Fluorescent Dye
Soon Moon Jeong 1 , Seongkyu Song 1 , Hyunmin Kim 1 , Kyung-Il Joo 2 , Hideo Takezoe 3 Show Abstract
1 , Daegu Gyeongbuk Institute of Science and Technology, Daegu Korea (the Republic of), 2 , Kyungpook National University, Daegu Korea (the Republic of), 3 , Toyota Physical and Chemical Research Institute, Aichi Japan
Mechanoluminescence (ML) is attractive for energy-saving technology because it can be generated by all available mechanical vibrations in nature. ML has potential applications in colorful displays and white-light sources. However, most ML phenomena show weak intensity and limited color expression due to the destructive nature of the process. Recently, the color manipulation of mechanoluminescence (ML) has been demonstrated by mixing different-color-emitting ML particles or controlling dopant concentration. However, the use of different ML materials usually restrain the various color expression because there has been a limited number of reported ML materials. Here, we show a red luminescence by complete color conversion from a spontaneously formed fluorescent-dye-diffused elastomeric zinc sulfide (ZnS) composite . The generation of red light could be achieved by spontaneously diffused 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) in polydimethylsiloxane (PDMS) which fully absorbs mechanically excited green ML. Based on this approach, we could achieve color-tuning from green to red and were able to demonstrated various-color-emitting optomechanical display by employing DCJTB.
 S. M. Jeong, S. Song, H. Kim, K. –I. Joo and H. Takezoe, Adv. Funct. Mater. 26, 4848 (2016).
9:00 PM - ES4.6.02
PCE Improved TENG with Gear Mechanism Based Mechanical Energy Transfer System
Wook Kim 1 , Dukhyun Choi 1 Show Abstract
1 , Kyung Hee University, Yongin-si Korea (the Republic of)
The performance of TENGs is mainly affected by the level of input mechanical energy and characteristics of triboelectric materials. Furthermore, the output performance of TENGs could be changed with mechanical structure and external electrical circuit. In this study, we investigated the effect of mechanical energy transfer system on TENG for enhancing both output performance and power conversion efficiency (PCE). To achieve objectives, we applied the gear mechanism on mechanical structure to improve the contact rate. We set an input gear with a specific size (rin) and a working gear with a smaller size (rw < rin) and connected these gears to enhance the working frequency (fw) at the working gear. We measured the output energy under a constant input energy with different size of the working gear (rw). We prepared gears with gear ratios (rin/rw) of 1, 1.7, and 5. Under the constant input energy, the peak voltage and current from our TENG system were enhanced up to the maximum of 3.6 times and 4.4 times, respectively. Also, the PCE was maximally increased up to 7 times under input frequency of 1.5 Hz with gear ratio of 5. To understand the effect of energy transfer mechanism on TENG, we charged a capacitor with external electrical circuit. Under the input frequency of 4.5 Hz, we obtained a 3 times enhanced rectifying voltage at a gear ratio of 5. Remarkably, capacitor voltage was enhanced up to about 8 fold in using our TENG system. It is attributed that our gear-based TENG system could improve simultaneously the magnitude as well as the generation time of output power, finally enhancing output energy. Therefore, our TENG system could provide an effective way to enhance the output performance and PCE of TENGs operating at a given input energy.
9:00 PM - ES4.6.03
Kinematically Driven Triboelectric Nanogenerator as a Practical Power Source
Divij Bhatia 1 , Dukhyun Choi 1 Show Abstract
1 , Kyung Hee University, Yongin Korea (the Republic of)
Triboelectric nanogenerators (TENG) can convert various forms of wasted mechanical energy in our environment into useful electrical energy that can power wireless sensor nodes constituting an internet of things (IoT) application. In this work we demonstrate a TENG system that utilizes mundane rotation energy to power a temperature and humidity wireless sensor node. Firstly we convert low frequency rotation input into high frequency using a custom gear system. A windup spring based mechanism was used to fix the output rotation frequency. Then using a cam the high frequency rotation is converted into linear motion to drive multiple verticle contact mode TENGs. A power converter system constituting a transformer and charge pump circuit is used to reliably power a temperature and humidity sensor that can periodically transmit data wirelessly via bluetooth to any smart device like a laptop or mobile phone. A number or such renewably TENG-powered wireless nodes can provide a great estimate of environmental conditions in industry applications sensitive to temperature and humidity changes. Automated control systems can be designed around these TENG-powered wireless nodes to ensure proper operation by self-adjusting critical settings or triggering a total system shutdown under emergency.
9:00 PM - ES4.6.04
High-Output Power of the Triboelectric Nanogenerator Made from Recycling Rice Husks
Chih-Kai Chang 1 , Jyh Ming Wu 1 Show Abstract
1 , National Tsing Hua University, Hsinchu Taiwan
This work, we are the first to discover the high-output current density of the triboelectric nanogenerator (TENG) using rice husks as a source material. The raw rice husks (RH) can be directly phase transited into the amorphous SiO2 (RHSiO2) structure with highly nanoporous fragments by the thermal annealing with additional acid hydrolysis process. The RHSiO2-TENG's configuration is designed by polytetrafluoroethene (PTFE) and RHSiO2 films, which are chemically and thermally more stable than the metallic film. The pore size around 20–40 nm is widely distributed throughout the SiO2 fragments that possess rich Si–O–Si and OH stretching bonds with strong tendency of repulsing electron because the H atoms have an extremely low electron affinity, leading to the RHSiO2 film exhibits much lower electron affinity when compared with the commercial SiO2 nanoparticles. As a consequence, the area power density of the RHSiO2 triboelectric nanogenerator (RHSiO2-TENG) reaches 0.84 W m-2 with a peak short circuit current density of 5.7 mA m-2. Such a short-circuit current density is almost among the highest reported value based on dielectric-to-dielectric mode triboelectric nanogenerators. Rice husk possess many advantageous traits such as their light weight, low cost, being environmentally friendly, high porosity, excellent robustness, exceptionally chemical and thermal stability for superior corrosion resistance, makes it a valuable material for industrial applications.
9:00 PM - ES4.6.05
Fabrication of a Highly Transparent Nanostructured Triboelectric Nanogenerator for the Application of an Efficient Hybrid Energy Harvester
Donghyeon Yoo 1 , Dongwhi Choi 1 , Dong Sung Kim 1 Show Abstract
1 , Pohang University of Science and Technology (POSTECH), Pohang Korea (the Republic of)
Triboelectric nanogenerators (TENGs), working based on a coupling of contact electrification and electric induction, have positioned as one of the promising energy harvesters, since the first report in 2012 due to their high accessibility from the ubiquitous characteristics of contact electrification. Recently, the possibility of harvesting water droplet-induced mechanical energy from TENGs is reported and several efforts are involved in increasing the electrical output performance and finding the practical applications. Along with it, a concept of hybrid energy harvesters, which can complementary harvest solar and raindroplet-induced mechanical energy, emerges as one of the main applications. The hybrid energy harvesters are composed of a solar cell and the attached TENG on its surface. They mainly harvest solar energy and subsidiary droplet-induced mechanical energy. However, the previous reported hybrid energy harvesters have a fundamental matter of the decrease in solar cell efficiency because the TENG hinders light absorption of the solar cell. Herein, we reported a new type of hybrid energy harvesters, where a solar cell is undisturbed by a TENG. The TENG is composed of 200 nm-structured quartz glass and a layer of AgNW, which give highly transparent characteristics. From the investigation of current-voltage characteristics, the efficiency of the solar cell in the present hybrid energy harvesters is similar with that of solar cell solely. Finally, the hybrid system shows self-cleaning characteristics and the corresponding droplet-induced mechanical energy generation due to the unique nanostructures. From the results, we believe the present research suggests a TENG, which has high potential to be applied in the fields of solar energy industry.
9:00 PM - ES4.6.06
Self-Recovering Triboelectric Nanogenerator as Active Multifunctional Sensors
Qingliang Liao 1 , Mingyuan Ma 1 , Yue Zhang 1 Show Abstract
1 , University of Science and Technology Beijing, Beijing China
A novel self-recovering triboelectric nanogenerator (STENG) driven by airflow is designed as active multifunctional sensors. A spring was composed to the STENG and enable the nanogenerator to have self-recovering characteristic. The maximum output voltage of the fabricated STENG is about 251 V. The instantaneous output current and power reaches 56 μA and 3.1 mW on a load of 1MΩ.The STENG can act as active multifunctional sensors that include humidity sensor, airflow rate sensor and motion sensor. The STENG-based humidity sensor has a wide detection range of 20%-80%, rapid response time of 18 ms and recovery time of 80 ms. This work expands practical applications of triboelectric nanogenerators as active sensors with advantages of simple fabrication and cost-effective.
9:00 PM - ES4.6.07
Optimization of Design Parameters towards Enhancing the Output Performance in Flexible Hybrid Triboelectric and Piezoelectric Nanogenerator
Xiya Yang 1 , Walid Daoud 1 Show Abstract
1 School of Energy and Environment, City University of Hong Kong, Hong Kong China
Interests in combined effect generators in mechanical energy harvesting [1-3] have rapidly grown in recent years due to their wide utilization without being limited by time or environment conditions. Since mechanical energy is easily obtainable in the living environment, conversion of mechanical energy to electricity using micro generators has become an approach to alleviate the serious problem of energy shortages.
Both piezoelectric and triboelectric effects can be utilized to design and realize good performance generators with high energy conversion efficiency. In this work, a flexible hybrid triboelectric and piezoelectric effects generator (TPEG) with a sandwich structure of aluminum - polydimethylsiloxane (PDMS) / polyvinylidene fluoride (PVDF) composite film [PPCF] - carbon is fabricated first for the purpose of converting mechanical energy to electricity. Enhanced by surface modification of PPCF with zinc oxide (ZnO) nanorods , the TPEG generated an open-circuit voltage (Voc) of ~40V and a short-circuit current (Isc) of 0.28μA with maximum power density of ~70mW/m2 and maximum efficiency of 34.56%. Subsequently, experimental studies on the impacts of design parameters towards improving the final output potential and the energy conversion efficiency were conducted by adjusting the factors of gap distance (d[cm]) between the triboelectric pair (Al and PPCF); the frequency (f[Hz]) of “press-release” by the linear motor, applied velocity (v[m/s]), and compression force (F[N]). The output performance of TPEG for experimental studies of the optimized gap distance, frequency, maximum velocity and compression force are analyzed through Voc, Isc, maximum power delivered to the external load and maximum conversion efficiency. Overall, the flexible hybrid TPEG with optimized design parameters is proved to be an efficient generator in mechanical energy conversion with promising output potential as well as high conversion efficiency.
 Zhu, G.; Peng, B.; Chen, J.; Jing, Q.; Wang, Z.L. Triboelectric nanogenerators as a new energy technology: From fundamentals devices to applications. Nano Energy 2015, 14, 126-138.
 Yang, Y. and Wang, Z. L., Hybrid energy cells for simultaneously harvesting multi-types of energies. Nano Energy 2015, 14, 245-256.
 Lin, L.; Xie, Y. N.; Niu, S. M.; Wang, S. H.; Yang, P. K.; Wang, Z. L., Robust Triboelectric Nanogenerator Based on Rolling Electrification and Electrostatic Induction at an Instantaneous Energy Conversion Efficiency of similar to 55%. ACS Nano 2015, 9, 922-930.
 Yang, X.Y. and Daoud, W. A., Triboelectric and Piezoelectric Effects in a Combined Tribo-Piezoelectric Nanogenerator Based on Interfacial ZnO Nanostructure. Adv. Funct. Mater. 2016, doi:10.1002/adfm.201602529.
9:00 PM - ES4.6.08
Ordered PZT Arrays Grown on Silicon Substrates Using Glancing Angle Pulsed Laser Deposition on Self-Assembled Nanotemplates
Domingo Mateo-Feliciano 1 , Derick Gonzalez 2 , Mahesh Hordagoda 1 , Pritish Mukherjee 1 , Sarath Witanachchi 1 Show Abstract
1 , University of South Florida, Tampa, Florida, United States, 2 , University of Puerto Rico at Mayaguez, Mayaguez, Puerto Rico, United States
Thin films and nanostructures of the piezoelectric material Lead Zirconium Titanium Oxide (PZT) offer a multitude of applications in Piezotronics. While the growth of PZT thin films is well established, methodologies for the fabrication of vertically-aligned and spatially ordered PZT columns in nanoscale are not common. In this work an approach that uses a self-assembled nanoparticle template in a glancing angle pulsed laser deposition (GAPLD) process is presented. As the first step, commercially available silica nanospheres (SNS) with diameter in the range of 250nm to 800 nm were self-assembled in a closed-pack hexagonal configuration as a monolayer using the Langmuir-Blodgett method. As the second step, a thin lanthanum strontium manganite oxide (LSMO) was grown by laser ablation on the template to serve as a bottom electrode as well as the seed layer for the subsequent PZT growth by GAPLD. Due to the shadowing effect introduced by the GAPLD, PZT columns in the form of hexagonal nanopillars evolved over the spatially ordered nanotemplate. Morphological, structural, and piezoelectric properties of these structures and their dependence on the nanoparticle size of the template will be presented.
9:00 PM - ES4.6.09
One-Step Fabrication of the Pattern Assisted Triboelectric Nanogenerator Operated by the Discrete Liquid-Solid Contact Electrification Phenomenon
Dongwhi Choi 1 , Donghyeon Yoo 1 , Dong Sung Kim 1 Show Abstract
1 , POSTECH, Pohang Korea (the Republic of)
In 2013, the phenomenon of discrete liquid-solid contact electrification inside the conventional pipet tip is firstly unveiled by our group. Discrete liquid-solid contact electrification is based on the sequential process of liquid-solid contact and separation. After its discovery, the discrete liquid-solid contact electrification phenomenon is utilized as a fundamental of operation of the various applications such as triboelectric nanogenerators (TENGs) and the self-powered sensors.
Herein, the phenomenon is briefly introduced and then, the fabrication of TENGs utilizing discrete liquid-solid contact electrification is demonstrated. By utilizing the thermal nanoimprinting process, nano-Pattern Assisted TriboElectric Replicable Nanogenerator, called nano-PATERN, can be one-step fabricated; the thermal nanoimprinting process enables not only nano-replication of a contact layer but also simultaneous integration with the electrode layer, which is an essential prerequisite for constructing nanotopographical TENGs.
The remarkable functional characteristics of high flexibility and transparency confirm significant benefits of the nano-PATERN for various applications such as solar cell applied-hybrid energy harvesters. Consequently, this study makes an important contribution for the mass production and practical utilization of TENGs.
9:00 PM - ES4.6.10
Spontaneous Dipole Modulation of Ferroelectric BaTiO3 NPs-Polymer Composite for Performance Enhancement of Triboelectric Nanogenerators
Sung-Ho Shin 1 , Yang Hyeog Kwon 1 , Joo-Yun Jung 2 , Junghyo Nah 1 Show Abstract
1 , Chungnam National Univ, Daejeon, SE, Korea (the Republic of), 2 Department of Nano Manufacturing Technology, Korea Institute of Machinery and Materials, Daejeon, Chungchungnam-Do, Korea (the Republic of)
Recently, triboelectric nanogenerators (TEGs) have been of interest as energy harvesting devices, thanks to their relatively simple fabrication process for their exceptionally high output power density. Triboelectrically generated output power can be greatly affected by choices of contacting materials, surface patterning, and chemical surface functionalization. However, the coupling effects of spontaneous dipoles inside the composite due to polarized ferroelectric NPs have not been much investigated. In this work, we report a novel method to extend the performance limit of TEGs by introducing polarized ferroelectric nanoparticles (NPs) inside the composite. Triboelectric output voltage and current have been modulated by varying the mixing ratio of BaTiO3 NPs to PDMS and differently polarizing BTO NPs inside the composite. In this way, the roles of permittivity and polarized dipole modulation in output power generation were systematically investigated and adopted for performance enhancement of the TEGs. Our results show that peak output power density of the TEGs can be greatly enhanced either by increasing permittivity or aligning polarization domain of the composite layer, exhibiting over 5-fold increases in output power density. The approach introduced here is a simple, effective, and cost-competitive route for the high performance TEGs and can be adopted in maximizing the output power of TEGs.
9:00 PM - ES4.6.11
Performance Enhanced Triboelectric Nanogenerator via Large-Area and Defectless Nanograting Enabled by Multistep Pattern Downscaling Lithography
Hee seung Wang 1 , Chang Kyu Jeong 1 , Keon Jae Lee 1 Show Abstract
1 , KAIST, Daejeon Korea (the Republic of)
The triboelectric nanogenerator (TENG) has been developed as a promising technology for mechanical energy harvesting with high output power, easy fabrication, low cost advantage and structure diversity of device. To obtain incomparable performance of TENG, many researchers have developed various methods including chemical and topographical surface engineering for larger contact area and triboelectric charge. Among them, it has been reported that significantly enhanced output-power can be generated owing to simply nano-fabricated patterns, so this approach has gained much recent-attention. In this research, we apply a seamless and ultralong 100 nm-pitch nanograting pattern assisted triboelectric nanogenerator. Based on the process of stitch-less and repetitive pattern downscaling lithography by alternatively depositing spacers/pattern receiver layers and etching, we introduce wafer-scale defectless nano-grating template with extremely high aspect ratio (4,000,000:1). Replicating this template to flexible substrate, the disposable nano-patterned plastic followed electrode deposition serves as friction surface of TENG to increase the output performances of TENG by forming the large effective contact surface area. The nanograting based-surface for TENG presented the increase of corresponding current and voltage as well as output power compared to the natural flat surface. This novel technology for triboelectric energy harvesting can induce new electronics innovations in triboelectricity and widely expand its applications as not only efficient energy sources but also various sensor.
9:00 PM - ES4.6.12
Design of the Piezoelectric Energy Harvesting Modules for Self-Powered Smart Roadways
Inki Jung 1 2 , Youn-Hwan Shin 1 2 , Sang Tae Kim 1 , Chong-Yun Kang 1 2 Show Abstract
1 Center for Electronic Materials, Korea Institute of Science and Technology, Seoul Korea (the Republic of), 2 KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul Korea (the Republic of)
With the advent of environmental issues, various energy harvesting technologies have received research attention for making use of the ambient energy sources. Piezoelectric energy harvesters are one of the most attractive technologies to recycle the wasted kinetic energy into the electricity. Herein, we demonstrate a piezoelectric energy harvesting module based on polyvinylidene fluoride (PVDF) to utilize the traffic induced energy on roadways. In contrast to the ceramic-based piezoelectrics, PVDF maintains inherent flexibility and durability despite the mechanical shock caused by the vehicles on roadways. In order to construct a harvesting module, we first structurally optimized harvesting elements based on Finite Element Analysis (FEA). Also, tThe devices were are then designed such so that parallel-connected unit harvesters effectively can lower the overall impedance. A prototype harvester prototype module was was fabricated with 15×15 cm2 size, and we performed measuredments under model roadway systems. The maximum output power density of 4.9 W/m2 was observed under 250 kg axial load and 10 km/h wheel speed. This macro-scale (~W/m2) energy harvesting technology provides us with the opportunity to expect smart roadways to come in the near future.
9:00 PM - ES4.6.14
Investigation of Aluminum Nitride Films for a Vibration Energy Harvesting Device
Kun-Mao Huang 1 , Hsuan-Ying Chen 1 , Kun-Dar Li 1 Show Abstract
1 Department of Materials Science, National University of Tainan, Tainan Taiwan
Due to the stimulation of the environmental issues, over the past decades many energy-related researches were focused on the subjects of energy harvesting materials, such as solar cells, thermoelectric generators and piezoelectric transducers. Aluminum nitride becomes one of the promising materials for the applications in the energy harvester by virtue of its good piezoelectric property. Taking the advantages of the low temperature process and high deposition rate, DC reactive magnetron sputtering was applied in this study to prepare AlN thin films for a vibration energy harvesting device. By changing the sputtering parameters, such as N2 ratio, sputtering power and substrate temperature, different morphologies and crystal structures of AlN films were produced. Afterwards, a vibration energy harvesting device of AlN films deposited on a polyimide (PI) substrate with Al electrode was fabricated and the piezoelectric property of this device was further evaluated. From the SEM images, XRD analysis and piezoelectric property measurement, the influence of sputtering parameters on the morphology and piezoelectric property of AlN films was distinctly demonstrated. While the sputtering power was increased from 80W to 160W, it showed that a preferred crystal plane of (002) could be obtained, and the grains of AlN films with a size of ~150nm on the substrate were observed apparently. The vibration energy harvesting device with (002) preferred orientations would have a higher peak-to-peak voltage and power. In addition, the experimental results also demonstrated that an appropriate substrate temperature can improve the crystallinity of AlN films to enhance the piezoelectric property. The highest power density in this study reached about 140mW under the vibration frequency of 20Hz.
9:00 PM - ES4.6.15
Sponge TENG Generating Stable Output in Various Mechanical Energy and Harsh Environments
Hwang Heejae 1 , Dukhyun Choi 1 Show Abstract
1 Mechanical Engineering, Kyunghee University, Yongin Korea (the Republic of)
Harvesting energy from our living environment is an effective approach for sustainable, maintenance-free, and green powder source for wireless, portable, or implanted electronics. So, as moving into a ubiquitous socity, wasted energy around us is received attention to be harvested. Triboelectric nanogenerator(TENG) is one of the solution. But, in order to apply TENG to real life, there are two factors. First, it is that stable energy generating in ant environments such as in high humidity. Second, it is that shape of generator is critically important in order to apply various mechanical energy source. In various previous research, almost all comprises two plate and spacer, roughly. The components are managed to restrict TENG to applications of narrow range. In this study, we focused on triboelectric nanogenerators that can harvest in various situation and harsh environments in order to overcome the weakness of TENG. We fabricated milti-shape sponge type TENG from Al particles to utilize diverse mechanical energy source in daily life and avoid from surrounding condition, such as humidity and dust. Also they have a porous fabrication, like a sponge. So, it can use a application resisting an Impulse. We expect this study pioneers application of TENG to our life.
9:00 PM - ES4.6.16
Enhanced Performance of Triboelectric Nanogenerators by Localized Surface Plasmon Resonance Effect with Silver Nanoparticles
Songhwa Chae 1 , Dukhyun Choi 1 Show Abstract
1 , Kyung Hee University, Yongin Korea (the Republic of)
Nowadays, energy crisis becomes a global problem and there are a lot of efforts to develop the use of green energy source. As a solution to this problem, energy harvest system received world attention. In 2012, energy generating based on the conjunction of triboelectric effect and electrostatic induction is presented as triboelectric nanogenerators (TENGs), which can produce electrical power from ambient environment such as human motion, vibration, walking, wind and so on. TENGs are expected to be used in the wearable and self-powered devices. In this study, we report that using Localized surface plasmon resonance (LSPR) effect enhance power of TENGs. We used ITO-coated PET film as electrode and polydimethylsiloxane (PDMS) as negatively charged material. We prepared PDMS thin film without micro/nano morphology and bonded it to ITO-coated PET film for top layer. Then, for bottom layer, silver was deposited 20nm on ITO-coated PET film via thermal evaporator, next annealing process to the film was conducted for silver nanoparticles (Ag-NPs) forming. When the light hit the Ag-NPs, it can exhibit LSPR effect. The LSPR effect can create strong near-field electromagnetic fields and far-field propagating waves. Therefore, the LSPR effect from Ag-NPs can improve the performance of TENGs. Finally, we compared the performances of TENGs in with or without light condition. We expect this integration system can provide a new hybrid TENGs for transparent devices application.
9:00 PM - ES4.6.17
Template-Assisted Hydrothermal Growth of Aligned Zinc Oxide Nanowires for Piezoelectric Energy Harvesting Applications
Canlin Ou 1 , Sohini Kar-Narayan 1 Show Abstract
1 , University of Cambridge, Cambridge United Kingdom
A flexible and robust piezoelectric nanogenerator (NG) based on a novel hybrid polymer-ceramic nanocomposite structure for piezoelectric energy harvesting (EH) applications has been successfully fabricated via a simple yet cost-effective, scalable and low-temperature template-assisted hydrothermal synthesis method. Vertically aligned arrays of dense and uniform zinc oxide (ZnO) nanowires (NWs) with high aspect ratios were grown within flexible nanoporous polycarbonate (PC) templates. The synthesised ZnO NWs are polycrystalline and have demonstrated a strong alignment along (100) preferred orientation. The as-grown high-quality ZnO NWs embedded within soft and flexible PC templates can be directly integrated into NGs with minimal post-possessing treatment, and the resulting NGs are particularly robust and relatively immune to detrimental environmental factors and mechanical failure, as the constituent ZnO NWs remain embedded and protected inside the polymer matrix. A single NG of area ~3 cm2 and thickness ~12 μm has generated a peak output power density of ~1.6 W/m3 across a load resistance of ~1 MΩ, and its energy conversion efficiency was found to be ~4.2%, which is comparable to previously reported values for ZnO NWs. The mechanical stability of the NGs has also been comprehensively evaluated by various piezoelectric EH tests, and it has shown that these flexible ZnO-PC based NGs are particularly robust and exhibit superior stable EH performance over time. Furthermore, Li has been doped to modify the piezoelectric and ferroelectric properties of ZnO. Long and well-aligned yet polycrystalline ZnO NWs doped with different Li concentration have been successfully synthesised. A decrease in a and c lattice parameters and an increase in the c/a ratio with increasing Li concentration have been observed in the Li-doped NWs, which confirms Li has successfully partially substituted Zn. Their ferroelectric and piezoelectric properties are subsequently assessed.
9:00 PM - ES4.6.19
A Flexible Energy Harvester Based on a Lead-Free and Piezoelectric BCTZ Nanoparticle–Polymer Composite
Changyeon Baek 1 , Kwi-Il Park 2 , Do Kyung Kim 1 Show Abstract
1 , KAIST, Daejeon Korea (the Republic of), 2 Energy Engineering, Gyeongnam National University of Science and Technology, Jinju Korea (the Republic of)
Lead-free piezoelectric 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.2Ti0.8)O3 (BCTZ) nanoparticles (NPs) composed of earth-abundant elements were adopted for use in a flexible composite-based piezoelectric energy harvester (PEH) that can convert mechanical deformation into electrical energy. The solid-state synthesized BCTZ NPs and silver nanowires (Ag NWs) chosen to reduce the toxicity of the filler materials were blended with a polydimethylsiloxane (PDMS) matrix to produce a piezoelectric nanocomposite (p-NC). The naturally flexible polymer-based p-NC layers were sandwiched between two conductive polyethylene terephthalate plastic substrates to achieve a flexible energy harvester. The BCTZ NP-based PEH effectively generated an output voltage peak of ∼15 V and a current signal of ∼0.8 μA without timedependent degradation. This output was adequate to operate a liquid crystal display (LCD) and to turn on six blue light emitting diodes (LEDs).
9:00 PM - ES4.6.20
Eco-Friendly Smart Mobile Pouch Triboelectric Nanogenerator for Self-Powered Wireless Power Transfer Applications
Arunkumar Chandrasekhar 1 , Nagamalleswara Rao Alluri 1 , Sudhakaran M.S.P 1 , Young Sun Mok 1 2 , Sang-Jae Kim 1 Show Abstract
1 , Jeju National University, Jeju Korea (the Republic of), 2 Department of Chemical Engineering, Pennsylvania State University, University Park, PA , Pennsylvania, United States
A Smart Mobile Pouch Triboelectric Nanogenerator (SMP-TENG) is introduced as a promising eco-friendly approach for scavenging biomechanical energy for powering next generation intelligent devices and smart phones. This is a cost-effective and robust method for harvesting energy from human motion, by utilizing worn fabrics as a contact material. The SMP-TENG is capable of harvesting energy in two operational modes: lateral sliding and vertical contact and separation. Moreover, the SMP-TENG can also act as a self-powered emergency flashlight and self-powered pedometer during normal human motion. A wireless power transmission setup integrated with SMP-TENG is demonstrated. This upgrades the traditional energy harvesting device into a self-powered wireless power transfer SMP-TENG. The wirelessly transferred power can be used to charge a Li-ion battery and light LEDs. The SMP-TENG opens a wide range of opportunities in the field of self-powered devices and low maintenance energy harvesting systems for portable and wearable electronic gadgets.
This work was supported by the Jeju Sea Grant College Program 2016, Funded by the Ministry of Oceans and Fisheries (MOF) and by the National Research Foundation of Korea (NRF) funded by the Korea Government GRANT (2016R1A2B2013831).
9:00 PM - ES4.6.21
Wearable Sensory Glove Using TiO2-ZnO Core-Shell Structures on Flexible Ti-Wires via Chemical Oxidation/Deposition Method
Nagamalleswara Rao Alluri 1 , Arunkumar Chandrasekhar 2 , Ji Hyun Jeong 1 , Sang-Jae Kim 2 Show Abstract
1 Mechanical Engineering, Jeju National University, Jeju City, Jeju Island, Korea (the Republic of), 2 Mechatronics Engineering, Jeju National University, Jeju, Jeju Island, Korea (the Republic of)
We report a scalable synthesis of TiO2 nanoparticles-ZnO micro rods based core-shell structures on a micro-meter sized diameter (100 μm) and few centimeter sized lengths of Ti wire via chemical oxidation/deposition method. It is highly desirable to scale down the wearable device dimensions at micro/nanoscale with high repeatability and sensitivity. The phase structure and surface morphology was investigated by Raman spectra and scanning electron microscope confirming the well crystalline TiO2 anatase nanoparticles and hexagonal wurtzite structure of ZnO micro rods. The fabricated wire based device (Ag/TiO2-ZnO/Ag) has a capability to convert the tiny mechanical motions into electricity using the piezoelectric behavior of ZnO micro rods. The classification/detection of joint or finger movements is possible by the device output voltage or current. The reliability of the sensor depends on the generated electric potential, location of the device on the glove, strain generated by the joints, and flexibility of the device. Therefore, the flexible wire based wearable gloves useful for in-patient rehabilitation, finger Braille typing and directional bending of the human body. These efficient smart devices (battery free) have a great demand in implantable biomedical devices, optical sensors and chemical sensors.
Keywords: TiO2-ZnO core-shell structures, piezoelectric behavior, energy harvesting, self-powered device, and chemical oxidation
This work was supported by the Jeju Sea Grant College Program 2016 Funded by the Ministry of Oceans and Fisheries (MOF) and by the National Research Foundation of Korea (NRF) funded by the Korea Government GRANT (2016R1A2B2013831).
9:00 PM - ES4.6.22
Triboelectric–Electromagnetic Hybrid Generator for Harvesting Blue Energy
Zhen Wen 1 2 , Hengyu Guo 2 , Min-Hsin Yeh 2 , Yunlong Zi 2 , Xin Wang 2 , Xuhui Sun 1 , Zhong Lin Wang 2 Show Abstract
1 , Soochow University, Suzhou China, 2 Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Although blue energy is capable of meeting all of our energy needs, there is no effective way to harvest it due to its low frequency and irregular amplitude, which may restrict the application of traditional power generators. Here we propose a hybrid nanogenerator that consists of a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) for harvesting ocean energy. Since the mechanical transmission from the external mechanical source to the TENG is through a noncontact force between the paired magnets, a fully isolated packaging of TENG part can be easily achieved. At the same time, combining with metal coils, these magnets can be fabricated to be EMG. The contrastive characteristics and advantages of outputs indicate that the TENG is irreplaceable for harvesting low frequency (<5 Hz) energy, which fits the frequency range for most of the water wave based blue energy, while EMG is able to produce larger output at high frequencies (>10 Hz). The complementary output can be maximized and hybridized for harvesting energy in a broad frequency range. Notably, various different kinds of hybrid nanogenerators could generate electricity under either rotation mode or fluctuation mode to collect energy in ocean tide, current, and wave energy. The proposed hybrid nanogenerator renders an effective and sustainable progress in practical applications of the hybrid nanogenerator toward harvesting water wave energy offered by nature.
9:00 PM - ES4.6.25
Flexible and Controllable Piezo-Phototronic Pressure Mapping Sensor Matrix by Organic/Inorganic Hybrid LED Array
Rongrong Bao 1 , Caofeng Pan 1 , Zhong Lin Wang 1 Show Abstract
1 , Chinese Academy of Sciences, Beijing China
Functional tactile sensing device is mandatory for next-generation robotics and human-machine interfaces since the emulation of touching requires large-scale pressure sensor arrays with high-spatial resolution, high-sensitivity, and fast-response. Some tactile sensors fabricated with organic transistors or micro-structured rubber layer pressure sensor arrays have been reported. While with a resolution at the order of millimeter, these devices have not yet met the requirements of artificial skins whose spatial resolution is near 50 μm. Our group have demonstrated pressure sensor array base on piezotronic and piezo-phototronic effects. An ultra-high resolution of 2.7 μm was derived from piezo-phototronic pressure sensor array using ZnO nanowire (NW)/p-GaN LEDs array. These devices provide stable, fast response, as well as parallel-reading detections of spatial pressure distributions. However, the lacking of flexibility with a rigid sapphire substrate prevents the NW-LEDs array device from applications as smart skin; and the pressure measuring range of the device is in a relatively high pressure region. Therefore, a flexible pressure mapping system with moderate spatial-resolution become necessary and may find numerous potential applications in human-machine interfaces.
Recently, we designed and fabricated a flexible LED array composed of PEDOT:PSS and patterned ZnO NWs with a spatial resolution of 7 μm for mapping of spatial pressure distributions by using the piezo-phototronic effect. These devices possess a wide range of pressure measurements from 40 MPa to 100 MPa depending on the growth conditions of ZnO NWs. Furthermore, a LED array composed of PEDOT:PSS and CdS nanorods had been demonstrated for mapping spatial pressure distributions. The emission intensity of which depends on the local strain owing to the piezo-phototronic effect. Therefore, pressure distribution is obtained by parallel-reading the illumination intensities of LED arrays based on electroluminescence working mechanism. The spatial resolution is achieved as high as 1.5 μm. Flexible LED device array has been prepared by CdS nanorod array on Au/Cr/Kapton substrate.
The flexibility and stability of these LED arrays mapping system was studied. The outstanding flexibility, high resolution and controllability of these pressure mapping sensors provide promising technologies for future applications in biological sciences, human-machine interfacing, smart sensor and processor systems, and even defense technology.
 S. C. B. Mannsfeld, B. C. K. Tee, R. M. Stoltenberg, C. V. H. H. Chen, S. Barman, B. V. O. Muir, A. N. Sokolov, C. Reese, Z. Bao, Nature Materials 2010, 9, 859;
 B. C. K. Tee, A. Chortos, R. R. Dunn, G. Schwartz, E. Eason, Z. A. Bao, Advanced Functional Materials 2014, 24, 5427.
 W. Z. Wu, X. N. Wen, Z. L. Wang, Science 2013, 340, 952.
 C. F. Pan, L. Dong, G. Zhu, S. M. Niu, R. M. Yu, Q. Yang, Y. Liu, Z. L. Wang, Nat. Photonics 2013, 7, 752;
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Design and Efficiency of Flexible Capacitive Piezoelectric Sensors Based on GaN Wires
Amine El Kacimi 1 2 , Emmanuelle Pauliac-Vaujour 1 2 , Joel Eymery 3 2 Show Abstract
1 , CEA-LETI, Grenoble France, 2 , Université Grenoble Alpes, Grenoble France, 3 , CEA-INAC, MEM-NRS, Grenoble France
Gallium Nitride (GaN) piezoelectric wire-based flexible hybrid structures provide original solution for mechanical sensing applications. Heavily n-doped GaN wires are grown by Metal Organic Vapor Phase Epitaxy (MOVPE) on sapphire substrate with in-situ injection of silane , . It provides N-polar wires with hexagonal cross-section, 10 – 700 µm length (depending on growth time) and a slight conical shape (with 0.3-2° angle).
Horizontally assembled wire-based sensors, obtained by wet chemical functionalization of GaN wires transferred onto flexible substrate, have been previously studied , . The operating principles of these devices under bending are analyzed with finite element calculations. In particular, we demonstrate that the wire conical shape is necessary for potential generation due to symmetry breaking of electrostatic dipoles created by piezoelectric field. To optimize the efficiency, this geometry requires dipole alignments, which will be enlightened through the simulation of different regular wire network configurations. This important point is difficult to manage in the practical device realization .
To overcome this problem, we propose a new solution integrating as-grown GaN wires directly inside a flexible PDMS layer within a capacitive structure. Charges are vertically separated and potential is collected on the top electrode. These devices can operate under compressive loading or bending constraints and their physical working mechanisms are also analyzed. In these structures, the electrical characteristics can easily be tuned by controlling wire length, density and device dimensions. An equivalent electrostatic dipole model is also proposed to explain the origin of potential generation in such vertical devices. Moreover, FEM calculations coupling semiconductor physics (free carriers) and piezoelectricity are performed to understand the effect of doping on the piezo-potential and device output.
The comparison of both structures shows that vertical devices are more reproducible and provide better output voltage in comparison to horizontal ones and the general design rules will be given. Experimentally, we demonstrate the realization of vertical-wire devices providing up to 3V output voltage.
 J. Eymery, et al., Comptes Rendus Phys., vol. 14, no. 2–3, pp. 221–227, Feb. 2013.
 R. Koester, et al., Nanotechnology, vol. 21, no. 1, p. 015602, Jan. 2010.
 S. Salomon et al., Nanotechnology, vol. 25, no. 37, p. 375502, Sep. 2014.
 F. Kim, et al., J. Am. Chem. Soc, vol. 23, no. 18, pp. 4360–4361, Dec 2001.
 M. C. P. Wang et al., Mater. Today, vol. 12, no. 5, pp. 34–43, May 2009.
9:00 PM - ES4.6.29
Piezo-Phototronic Enhanced UV Sensing Based on a Nanowire Photodetector Array
Xun Han 1 , Caofeng Pan 1 Show Abstract
1 , Beijing Institute of Nanoenergy and Nanosystems, Beijing China
High performance and high resolution photon sensor arrays are essential for medical science, imaging and functional systems. Here, we demonstrate a pressure sensitive UV photodetector array consisting of 32 × 40 pixels based on vertically aligned ZnO nanowires. Each pixel is composed of ZnO nanowire and Au nanopatterns to form a Schottky contact UV photodetector with spatial resolution of 100μm (254 dpi) and response time of 60 ms. The imaging of optical stimuli distributions is achieved by recording the electrical outputs from all pixels of the devices. By utilizing the strain-induced piezoelectric polarization charges at the local Schottky contact, the piezo-phototronic effect has been introduced to modify the energy band diagram and thus to tune/control the generation, recombination, separation and transport of charge carriers during the optoelectronic processes within the UV photodetectors. As a result, the performances of the devices are enhanced by 700% in photoresponsivity, 600% in sensitivity and 280% in detection limit by applying a static strain of 40.83 MPa. This work provides a practical solution to achieving large-scale PDs with high performances by integrating nanowire-photodetector into array configuration. The UV photodetectors array may find applications in optoelectronic systems, biomedical diagnostics, adaptive optical computing and communication.
9:00 PM - ES4.6.30
A Highly Shape-Adaptive, Stretchable Design Based on Conductive Liquid for Energy Harvesting and Self-Powered Biomechanical Monitoring
Fang Yi 1 Show Abstract
1 , Peking University, Beijing China
The rapid growth of deformable and stretchable electronics calls for a deformable and stretchable power source. We report a scalable approach for energy harvesters and self-powered sensors that can be highly deformable and stretch- able. With conductive liquid contained in a polymer cover, a shape-adaptive triboelectric nanogenerator (saTENG) unit can effectively harvest energy in various working modes. The saTENG can maintain its performance under a strain of as large as 300%. The saTENG is so flexible that it can be conformed to any three-dimensional and curvilinear surface. We demonstrate applications of the saTENG as a wearable power source and self-powered sensor to monitor bio- mechanical motion. A bracelet-like saTENG worn on the wrist can light up more than 80 light-emitting diodes. Owing to the highly scalable manufacturing process, the saTENG can be easily applied for large-area energy harvesting. In addition, the saTENG can be extended to extract energy from mechanical motion using flowing water as the electrode. This approach provides a new prospect for deformable and stretchable power sources, as well as self- powered sensors, and has potential applications in various areas such as robotics, biomechanics, physiology, kinesiology, and entertainment.
9:00 PM - ES4.6.31
Self-Powered Motion Sensor Using Flow-Less CNT Sheet Nanogenerator
Hyelynn Song 1 , Taewoo Kim 1 , Hyeongwook Im 1 , Tae June Kang 2 , Yong Hyup Kim 1 Show Abstract
1 , Seoul National University, Seoul Korea (the Republic of), 2 , Inha University, Incheon Korea (the Republic of)
Carbon nanotube (CNT), which has one-dimensional atomic structure, is highly accessible to external stimuli because of its high surface area to volume ratio. Thus, electronic configuration of CNT can be strongly influenced by tiny perturbations. The unique interaction between CNT and its surrounding stimuli has been of particular interest over the past decade. A thorough understanding of the interaction enables to develop a wide range of applications, such electrical bio/chemical sensors and actuators with unrivaled performance. Previous researches proved that CNT can