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Md Mehebub Alam, Ayesha Sultana, Debabrata Sarkar, Dipankar Mandal
The electroactive β-phase is most desirable due to its highest piezo-, pyro- and ferro-electric properties in poly(vinylidene fluoride) (PVDF). Induction of β-phase is successfully accomplished in titanium dioxide (TiO2) nanoparticles (NPs) doped spin coated PVDF nanocomposite (PNC) films. The optimized yields of β-phase and homogeneous ultra-smooth free standing PNC film is utilized in mechanical energy harvesting application by fabricating a nanogenerator (NG) where the typical electrical poling step is not undertaken...
June 22, 2017: Nanotechnology
Amanda H Lewis, Alisa F Cui, Malcolm F McDonald, Jörg Grandl
Several cell types experience repetitive mechanical stimuli, including vein endothelial cells during pulsating blood flow, inner ear hair cells upon sound exposure, and skin cells and their innervating dorsal root ganglion (DRG) neurons when sweeping across a textured surface or touching a vibrating object. While mechanosensitive Piezo ion channels have been clearly implicated in sensing static touch, their roles in transducing repetitive stimulations are less clear. Here, we perform electrophysiological recordings of heterologously expressed mouse Piezo1 and Piezo2 responding to repetitive mechanical stimulations...
June 20, 2017: Cell Reports
Andrei Diaconu, Simona-Lacramioara Lupu, Ionela Rusu, Ioan-Marian Risca, Lionel Salmon, Gabor Molnár, Azzedine Bousseksou, Philippe Demont, Aurelian Rotaru
We report on the effect of hydrostatic pressure on the electrical conductivity and dielectric permittivity of the [Fe(Htrz)2(trz)](BF4) (Htrz = 1H-1,2,4, triazole) spin crossover complex. Variable temperature and pressure broadband imped-ance spectrometry revealed a piezo-resistive effect of more than one order of magnitude for pressures as low as 500 bar, associated with a large pressure-induced hysteresis of 1700 bar. The origin of the piezo-resistive effect has been attributed to the pressure induced spin-state switching in the complex and the associated P,T phase diagram was determined...
June 21, 2017: Journal of Physical Chemistry Letters
P José Gouveia, S Rosa, L Ricotti, B Abecasis, H V Almeida, L Monteiro, J Nunes, F Sofia Carvalho, M Serra, S Luchkin, A Leonidovitch Kholkin, P Marques Alves, P Jorge Oliveira, R Carvalho, A Menciassi, R Pires das Neves, L Silva Ferreira
The use of engineered cardiac tissue for high-throughput drug screening/toxicology assessment remains largely unexplored. Here we propose a scaffold that mimics aspects of cardiac extracellular matrix while preserving the contractility of cardiomyocytes. The scaffold is based on a poly(caprolactone) (PCL) nanofilm with magnetic properties (MNF, standing for magnetic nanofilm) coated with a layer of piezoelectric (PIEZO) microfibers of poly(vinylidene fluoride-trifluoroethylene) (MNF+PIEZO). The nanofilm creates a flexible support for cell contraction and the aligned PIEZO microfibers deposited on top of the nanofilm creates conditions for cell alignment and electrical stimulation of the seeded cells...
September 2017: Biomaterials
C Borderon, A E Brunier, K Nadaud, R Renoud, M Alexe, H W Gundel
Two Pb(Zr0.20Ti0.80)O3 samples of different thickness and domain configuration have been studied. The c-domain sample was found to have a higher coercive field E c and higher dielectric losses than the other which presents approximately 60% of c-domains and 40% of a-domains as observed by piezo force microscopy (PFM) characterization. Hyperbolic law measurements reveal that the higher coercive field is due to domain wall pinning in deeper defects and hence a higher field E th is required for unpinning. The dissipation factors due to domain wall motion, however, are similar in both samples since the domain wall density is low and there is almost no interaction between domain walls...
June 13, 2017: Scientific Reports
Wesley Johnson, Changsheng Dai, Jun Liu, Xian Wang, Devin K Luu, Zhuoran Zhang, Changhai Ru, Chao Zhou, Min Tan, Huayan Pu, Shaorong Xie, Yan Peng, Jun Luo, Yu Sun
Mammalian oocytes such as mouse oocytes have a highly elastic outer membrane, zona pellucida (ZP) that cannot be penetrated without significantly deforming the oocyte, even with a sharp micropipette. Piezo drill devices leverage lateral and axial vibration of the micropipette to accomplish ZP penetration with greatly reduced oocyte deformation. However, existing piezo drills all rely on a large lateral micropipette vibration amplitude (>20 μm ) and a small axial vibration amplitude (<0.1 μm ). The very large lateral vibration amplitude has been deemed to be necessary for ZP penetration although it also induces larger oocyte deformation and more oocyte damage...
June 7, 2017: IEEE Transactions on Bio-medical Engineering
Haiyang Zou, Xiaogan Li, Wenbo Peng, Wenzhuo Wu, Ruomeng Yu, Changsheng Wu, Wenbo Ding, Fei Hu, Ruiyuan Liu, Yunlong Zi, Zhong Lin Wang
Silicon underpins nearly all microelectronics today and will continue to do so for some decades to come. However, for silicon photonics, the indirect band gap of silicon and lack of adjustability severely limit its use in applications such as broadband photodiodes. Here, a high-performance p-Si/n-ZnO broadband photodiode working in a wide wavelength range from visible to near-infrared light with high sensitivity, fast response, and good stability is reported. The absorption of near-infrared wavelength light is significantly enhanced due to the nanostructured/textured top surface...
June 6, 2017: Advanced Materials
Krishna C Balram, Marcelo I Davanço, B Robert Ilic, Ji-Hoon Kyhm, Jin Dong Song, Kartik Srinivasan
Acoustic wave devices provide a promising chip-scale platform for efficiently coupling radio frequency (RF) and optical fields. Here, we use an integrated piezo-optomechanical circuit platform that exploits both the piezoelectric and photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm) optical waves, through coupling to propagating and localized 2.4 GHz acoustic waves. We demonstrate acousto-optic modulation, resonant in both the optical and mechanical domains, in which waveforms encoded on the RF carrier are mapped to the optical field...
February 2017: Physical Review Applied
G Signorello, M Schraff, P Zellekens, U Drechsler, M Bürge, H R Steinauer, R Heller, M Tschudy, H Riel
We present an automatic measurement platform that enables the characterization of nanodevices by electrical transport and optical spectroscopy as a function of the uniaxial stress. We provide insights into and detailed descriptions of the mechanical device, the substrate design and fabrication, and the instrument control software, which is provided under open-source license. The capability of the platform is demonstrated by characterizing the piezo-resistance of an InAs nanowire device using a combination of electrical transport and Raman spectroscopy...
May 2017: Review of Scientific Instruments
Tomaš Stankevič, Christer Engblom, Florent Langlois, Filipe Alves, Alain Lestrade, Nicolas Jobert, Gilles Cauchon, Ulrich Vogt, Stefan Kubsky
The field of three-dimensional multi-modal X-ray nanoimaging relies not only on high-brilliance X-rays but also on high-precision mechanics and position metrology. Currently available state-of-the-art linear and rotary drives can provide 3D position accuracy within tens to hundreds of nm, which is often insufficient for high resolution imaging with nanofocused X-ray beams. Motion errors are especially troublesome in the case of rotation drives and their correction is more complicated and relies on the metrology grade reference objects...
May 2017: Review of Scientific Instruments
T Darnige, N Figueroa-Morales, P Bohec, A Lindner, E Clément
We describe the development of a tracking device, mounted on an epi-fluorescent inverted microscope, suited to obtain time resolved 3D Lagrangian tracks of fluorescent passive or active micro-objects in microfluidic devices. The system is based on real-time image processing, determining the displacement of a x, y mechanical stage to keep the chosen object at a fixed position in the observation frame. The z displacement is based on the refocusing of the fluorescent object determining the displacement of a piezo mover keeping the moving object in focus...
May 2017: Review of Scientific Instruments
Soichiro Yamaguchi, Ken-Ichi Otsuguro
Mas-related G-protein coupled receptor B4 (MrgprB4) has been reported to be expressed in the dorsal root ganglion (DRG) neurons which detect stroking of hairy skin of mice. However, the mechanisms by which the MrgprB4 positive (+) neurons respond to adequate stimulus remain unsolved as it was also reported that electrophysiological analysis of cultured MrgprB4+ neurons did not reveal responses to mechanical stimuli. Contrary to the observation, however, in this study we show that the MrgprB4+ neurons functionally express a mechanically activated channel using DRG neurons dissociated from genetically-modified mice whose MrgprB4+ neurons express a red fluorescent protein...
May 22, 2017: Neuroscience Letters
Marjan Zakerin, Antonin Novak, Masaya Toda, Yves Emery, Filipe Natalio, Hans-Jürgen Butt, Rüdiger Berger
In this paper, we apply a digital holographic microscope (DHM) in conjunction with stroboscopic acquisition synchronization. Here, the temperature-dependent decrease of the first resonance frequency (S₁(T)) and Young's elastic modulus (E₁(T)) of silicon micromechanical cantilever sensors (MCSs) are measured. To perform these measurements, the MCSs are uniformly heated from T₀ = 298 K to T = 450 K while being externally actuated with a piezo-actuator in a certain frequency range close to their first resonance frequencies...
May 23, 2017: Sensors
W Apoutou N'Djin, Bjoern Gerold, Jeremy Vion, Michael Canney, An Nguyen-Dinh, Alexandre Carpentier, Jean-Yves Chapelon
Capacitive Micro-machined Ultrasound Transducers (CMUTs) exhibit several potential advantages over conventional piezo technologies for use in therapeutic ultrasound devices, including: ease of miniaturization and integration with electronics, broad bandwidth (>several MHz), and compatibility with magnetic resonance imaging (MRI). In this work, the electro-acoustic performance of CMUTs designed for interstitial high intensity contact ultrasound (HICU) applications was evaluated and the feasibility of generating ultrasound-induced heating and thermal destruction of biological tissues was studied...
May 24, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Qianhua Gao, Paul R Cooper, A Damien Walmsley, Ben A Scheven
INTRODUCTION: Piezo1 and Piezo2 are mechanosensitive membrane ion channels. We hypothesized that Piezo proteins may play a role in transducing ultrasound-associated mechanical signals and activate downstream mitogen-activated protein kinase (MAPK) signaling processes in dental cells. In this study, the expression and role of Piezo channels were investigated in dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) after treatment with low-intensity pulsed ultrasound (LIPUS)...
May 17, 2017: Journal of Endodontics
Parker G Rosquist, Gavin Collins, A Jake Merrell, Noelle J Tuttle, James B Tracy, Evan T Bird, Matthew K Seeley, David T Fullwood, William F Christensen, Anton E Bowden
This paper describes a method for the estimation of the 3D ground reaction force (GRF) during human walking using novel nanocomposite piezo-responsive foam (NCPF) sensors. Nine subjects (5 male, 4 female) walked on a force-instrumented treadmill at 1.34 m/s for 120 s each while wearing a shoe that was instrumented with four NCPF sensors. GRF data, measured via the treadmill, and sensor data, measured via the NCPF inserts, were used in a tenfold cross validation process to calibrate a separate model for each individual...
May 16, 2017: Annals of Biomedical Engineering
Xingfu Wang, Wenbo Peng, Ruomeng Yu, Haiyang Zou, Yejing Dai, Yunlong Zi, Changsheng Wu, Shuti Li, Zhong Lin Wang
Achievement of p-n homojuncted GaN enables the birth of III-nitride light emitters. Owing to the wurtzite-structure of GaN, piezoelectric polarization charges present at the interface can effectively control/tune the optoelectric behaviors of local charge-carriers (i.e., the piezo-phototronic effect). Here, we demonstrate the significantly enhanced light-output efficiency and suppressed efficiency droop in GaN microwire (MW)-based p-n junction ultraviolet light-emitting diode (UV LED) by the piezo-phototronic effect...
June 14, 2017: Nano Letters
Hiroki Ida, Yasufumi Takahashi, Akichika Kumatani, Hitoshi Shiku, Tomokazu Matsue
Observation of nanoscale structure dynamics on cell surfaces is essential to understanding cell functions. Hopping-mode scanning ion conductance microscopy (SICM) was used to visualize the topography of fragile convoluted nanoscale structures on cell surfaces under noninvasive conditions. However, conventional hopping mode SICM does not have sufficient temporal resolution to observe cell-surface dynamics in situ because of the additional time required for performing vertical probe movements of the nanopipette...
June 6, 2017: Analytical Chemistry
Urtnasan Erdenebayar, Jong Uk Park, Pilsoo Jeong, Kyoung Joung Lee
In this study, we propose a novel method for obstructive sleep apnea (OSA) detection using a piezo-electric sensor. OSA is a relatively common sleep disorder. However, more than 80% of OSA patients remain undiagnosed. We investigated the feasibility of OSA assessment using a single-channel physiological signal to simplify the OSA screening. We detected both snoring and heartbeat information by using a piezo-electric sensor, and snoring index (SI) and features based on pulse rate variability (PRV) analysis were extracted from the filtered piezo-electric sensor signal...
June 2017: Journal of Korean Medical Science
Yingying Sun, Masahiro Yanagisawa, Masahiro Kunimoto, Masatoshi Nakamura, Takayuki Homma
The internal structure of self-assembled monolayers (SAMs) such as 3-aminopropyltriethoxysilane (APTES) fabricated on a glass substrate is difficult to characterize and analyze at nanometer level. In this study, we employed surface-enhanced Raman spectroscopy (SERS) to study the internal molecular structure of APTES SAMs. The sample APTES SAMs were deposited with Ag nanoparticles to enhance the Raman signal and to obtain subtler structure information, which were supported by density functional theory calculations...
April 20, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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