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Andrea Schiaffino, Massimiliano Stengel
Based on a first-principles based multiscale approach, we study the polarity P of ferroelastic twin walls in SrTiO_{3}. In addition to flexoelectricity, which was pointed out before, we identify two new mechanisms that crucially contribute to P: a direct "rotopolar" coupling to the gradients of the antiferrodistortive oxygen tilts, and a trilinear coupling that is mediated by the antiferroelectric displacement of the Ti atoms. Remarkably, the rotopolar coupling presents a strong analogy to the mechanism that generates a spontaneous polarization in cycloidal magnets...
September 29, 2017: Physical Review Letters
Eli J Curry, Kai Ke, Meysam T Chorsi, Kinga S Wrobel, Albert N Miller, Avi Patel, Insoo Kim, Jianlin Feng, Lixia Yue, Qian Wu, Chia-Ling Kuo, Kevin W-H Lo, Cato T Laurencin, Horea Ilies, Prashant K Purohit, Thanh D Nguyen
Measuring vital physiological pressures is important for monitoring health status, preventing the buildup of dangerous internal forces in impaired organs, and enabling novel approaches of using mechanical stimulation for tissue regeneration. Pressure sensors are often required to be implanted and directly integrated with native soft biological systems. Therefore, the devices should be flexible and at the same time biodegradable to avoid invasive removal surgery that can damage directly interfaced tissues. Despite recent achievements in degradable electronic devices, there is still a tremendous need to develop a force sensor which only relies on safe medical materials and requires no complex fabrication process to provide accurate information on important biophysiological forces...
January 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
Amine El Kacimi, Emmanuelle Pauliac-Vaujour, Joel Eymery
We report a simple and scalable fabrication process of flexible capacitive piezoelectric sensors using vertically aligned gallium nitride (GaN) wires as well as their physical principles of operation. As-grown N-polar GaN wires obtained by self-catalyst metal-organic vapor phase epitaxy are embedded into a PDMS matrix and directly peeled off from the sapphire substrate before metallic electrode contacting. This geometry provides an efficient control of the wire orientation and an additive contribution of the individual piezoelectric signals...
January 17, 2018: ACS Applied Materials & Interfaces
Jean-Michel Friedt, Gilles Martin, Gwenhael Goavec-Mérou, David Rabus, Sébastien Alzuaga, Lilia Arapan, Marianne Sagnard, Émile Carry
Passive wireless transducers are used as sensors, probed by a RADAR system. A simple way to separate the returning signal from the clutter is to delay the response, so that the clutter decays before the echoes are received. This can be achieved by introducing a fixed delay in the sensor design. Acoustic wave transducers are ideally suited as cooperative targets for passive, wireless sensing. The incoming electromagnetic pulse is converted into an acoustic wave, propagated on the sensor substrate surface, and reflected as an electromagnetic echo...
January 16, 2018: Sensors
Hedieh Malekzad, Parham Sahandi Zangabad, Hamed Mirshekari, Mahdi Karimi, Michael R Hamblin
The aim of this review is to cover advances in noble metal nanoparticle (MNP)-based biosensors and to outline the principles and main functions of MNPs in different classes of biosensors according to the transduction methods employed. The important biorecognition elements are enzymes, antibodies, aptamers, DNA sequences, and whole cells. The main readouts are electrochemical (amperometric and voltametric), optical (surface plasmon resonance, colorimetric, chemiluminescence, photoelectrochemical, etc.) and piezoelectric...
June 27, 2017: Nanotechnology Reviews
Hemalatha Parangusan, Deepalekshmi Ponnamma, Mariam Al Ali Al-Maadeed
Herein, we investigate the morphology, structure and piezoelectric performances of neat polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) and PVDF-HFP/Co-ZnO nanofibers, fabricated by electrospinning. An increase in the amount of crystalline β-phase of PVDF-HFP has been observed with the increase in Co-doped ZnO nanofiller concentration in the PVDF-HFP matrix. The dielectric constants of the neat PVDF-HFP and PVDF-HFP/2 wt.% Co-ZnO nanofibers are derived as 8 and 38 respectively. The flexible nanogenerator manipulated from the polymer nanocomposite (PVDF-HFP/Co-ZnO) exhibits an output voltage as high as 2...
January 15, 2018: Scientific Reports
Anat Ratnovsky, Emanuel Kusayev, Sara Naftali
A flexible piezoelectric thin film sensor has been proposed recently in several studies for detection of muscle movements. The objective of this study was to investigate the ability of this sensor to assess skeletal muscle performance and fatigue under isokinetic contractions. Simultaneous noninvasive measurements of muscles activity were done using surface electromyography (EMG) electrodes and two thin film piezoelectric sensors. Measurements were taken from the biceps during slow and fast elbow flexion with and without strong grip, during different weight lifting and from the gastrocnemius during treadmill marching at speeds of 4 and of 10 kph...
January 5, 2018: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
Carsten Richter, Matthias Zschornak, Dmitri Novikov, Erik Mehner, Melanie Nentwich, Juliane Hanzig, Semën Gorfman, Dirk C Meyer
Physical properties of crystalline materials often manifest themselves as atomic displacements either away from symmetry positions or driven by external fields. Especially the origin of multiferroic or magnetoelectric effects may be hard to ascertain as the related displacements can reach the detection limit. Here we present a resonant X-ray crystal structure analysis technique that shows enhanced sensitivity to minute atomic displacements. It is applied to a recently found crystalline modification of strontium titanate that forms in single crystals under electric field due to oxygen vacancy migration...
January 12, 2018: Nature Communications
Peijian Huang, Ning Wang, Junying Li, Yong Zhu, Jie Zhang, Zhide Xi
In order to access the fretting damage of the steam generator tube (SGT), a fast fiber Fabry-Perot (F-P) non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED) was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP) was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail...
January 12, 2018: Sensors
Shuhai Liu, Longfei Wang, Zheng Wang, Yafeng Cai, Xiaolong Feng, Yong Qin, Zhong Lin Wang
Piezotronic transistor (PT) that utilize inner crystal potential generated by interface piezoelectric polarization charges as the gate voltage has great potential applications in force/pressure triggered or controlled electronics device, sensors, human-machine communication and microelectromechanical systems. Although the performance of PTs has been partly enhanced by exploring special materials with different geometry or high piezoelectricity, few studies have been focused on the structure design of PT itself to more effectively enhance the performance and structural reliability...
January 12, 2018: ACS Nano
Oleg I Vershinin, Aleksey V Konyashkin, Oleg A Ryabushkin
The dependence of the nonlinear optical absorption coefficients on the intensity and polarization of pulsed laser radiation at 355 nm was investigated for lithium triborate (LBO) crystals using the piezoelectric resonance laser calorimetry.
January 1, 2018: Optics Letters
L M Riobo, F E Veiras, M G Gonzalez, M T Garea, P A Sorichetti
This paper describes the design and performance of a phase demodulation scheme based on software-defined radio (SDR), applied in heterodyne interferometry. The phase retrieval is performed in real time by means of a low-cost SDR with a wideband optoelectronic front-end. Compared to other demodulation schemes, the system is quite simpler, versatile, and of lower cost. The performance of the demodulator is demonstrated by measuring the displacement per volt of a thin-film polymeric piezoelectric transducer based on polyvinylidene fluoride for ultrasonic applications...
January 10, 2018: Applied Optics
Wenyan Yang, Wuxiao Han, Huiling Gao, Linlin Zhang, Shuai Wang, Lili Xing, Yan Zhang, Xinyu Xue
As the concentration of different biomarkers in human body fluids are an important parameter of chronic disease, wearable biosensors for in situ analysis of body fluids with high sensitivity, real-time detection, flexibility and biocompatibility have significant potential therapeutic applications. In this paper, a flexible self-powered implantable electronic-skin (e-skin) for in situ body fluids analysis (urea/uric-acid) as a real-time kidney-disease diagnoser has been proposed based on the piezo-enzymatic-reaction coupling process of ZnO nanowire arrays...
January 11, 2018: Nanoscale
Jun Qian, Sai Jiang, Qijing Wang, Shushu Zheng, Shuya Guo, Chang Yi, Jianpu Wang, Xinran Wang, Kazuhito Tsukagoshi, Yi Shi, Yun Li
Piezoelectric response of P(VDF-TrFE), which is modulated by the dipole density due to the polarization switching on applying an electric field, allows it act as the fundamental components for electromechanical systems. As proposed since the 1970s, its polar α-phase is supposed to yield an enhanced piezoelectric activity. However, its experimental verification has never been reported, hampered by a substantial challenge for the achievement of a smooth, neat α-phase film. Here, we prepare ultrathin crystalline α-phase P(VDF-TrFE) films on the AlOx/Al-coated SiO2/Si substrates via a solution-based approach at room temperature...
January 11, 2018: Scientific Reports
Markus Kratzer, Michael Lasnik, Sören Röhrig, Christian Teichert, Marco Deluca
Lead zirconate titanate (PZT) is one of the prominent materials used in polycrystalline piezoelectric devices. Since the ferroelectric domain orientation is the most important parameter affecting the electromechanical performance, analyzing the domain orientation distribution is of great importance for the development and understanding of improved piezoceramic devices. Here, vector piezoresponse force microscopy (vector-PFM) has been applied in order to reconstruct the ferroelectric domain orientation distribution function of polished sections of device-ready polycrystalline lead zirconate titanate (PZT) material...
January 11, 2018: Scientific Reports
Sunghoon Lee, Taewook Kang, Wunho Lee, Mohammad M Afandi, Jongho Ryu, Jongsu Kim
We demonstrated the tri-functional device based on all powder-processing methods by using ZnS powder as phosphor layer and piezoelectric material as dielectric layer. The fabricated device generated the electroluminescent (EL) light from phosphor and the sound from piezoelectric sheet under a supply of external electric power, and additionally harvested the reverse-piezoelectric energy to be converted into EL light. Under sinusoidal applied voltage, EL luminances were exponentially increased with a maximum luminous efficiency of 1...
January 10, 2018: Scientific Reports
Andrew Reid, David J W Hardie, David Mackie, Joseph C Jackson, James F C Windmill
Underwater acoustic transducers, particularly at low frequencies, are beset by problems of scale and inefficiency due to the large wavelengths of sound in water. In insect mating calls, a high call volume is usually desirable, increasing the range of signal transmission and providing a form of advertisement of the signaller's quality to a potential mate; however, the strength of the call is constrained by body size and by the need to avoid predators who may be listening in. Male crickets and water boatmen avoid some of the limitations of body size by exploiting resonant structures, which produce sharply tuned species-specific songs, but call frequency and volume remain linked to body size...
January 2018: Journal of the Royal Society, Interface
Pandey Rajagopalan, Vipul Singh, Palani I A
Zinc oxide (ZnO) is a remarkable inorganic semiconductor with exceptional piezoelectric properties compared to other semiconductors. However, in comparison to lead-based hazardous piezoelectric materials, its features have undesired limitations. Here we report the 5~6 folds enhancement in the piezoelectric properties via chemical doping of copper matched to intrinsic ZnO. The flexible piezoelectric nanogenerator (F-PENG) device was fabricated using an unpretentious solution process of spin coating with other advantages like robust, low weight, improved adhesion, and low cost...
January 10, 2018: Nanotechnology
Yudong Liu, Junmeng Guo, Aifang Yu, Yang Zhang, Jinzong Kou, Ke Zhang, Rongmei Wen, Yan Zhang, Junyi Zhai, Zhong Lin Wang
Utilizing magnetic field directly modulating/turning the charge carrier transport behavior of field-effect transistor (FET) at ambient conditions is an enormous challenge in the field of micro-nanoelectronics. Here, a new type of magnetic-induced-piezopotential gated field-effect-transistor (MIPG-FET) base on laminate composites is proposed, which consists of Terfenol-D, a ferroelectric single crystal (PMNPT), and MoS2 flake. When applying an external magnetic field to the MIPG-FET, the piezopotential of PMNPT triggered by magnetostriction of the Terfenol-D can serve as the gate voltage to effectively modulate/control the carrier transport process and the corresponding drain current at room temperature...
January 10, 2018: Advanced Materials
Peng Li, Jiwei Zhai, Bo Shen, Shujun Zhang, Xiaolong Li, Fangyuan Zhu, Xingmin Zhang
High-performance lead-free piezoelectric materials are in great demand for next-generation electronic devices to meet the requirement of environmentally sustainable society. Here, ultrahigh piezoelectric properties with piezoelectric coefficients (d33 ≈700 pC N-1 , d33 * ≈980 pm V-1 ) and planar electromechanical coupling factor (kp ≈76%) are achieved in highly textured (K,Na)NbO3 (KNN)-based ceramics. The excellent piezoelectric properties can be explained by the strong anisotropic feature, optimized engineered domain configuration in the textured ceramics, and facilitated polarization rotation induced by the intermediate phase...
January 10, 2018: Advanced Materials
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