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Yulong Bai, Ning Jiang, Shifeng Zhao
Nanocluster-assembled FeGa micron-scale discs prepared by low-energy cluster beam deposition were embedded into Bi5Ti3FeO15 matrices to form pseudo 1-3 heterostructure films. The microstructures and multiferroic properties were investigated. Good ferroelectric, piezoelectric, and ferromagnetic properties and giant magnetoelectric effects are achieved for the heterostructure films, which is ascribed to the depression of the clamped effect from the hard substrate for such pseudo 1-3 structures and the multi-interface coupling between the large magnetostrictive coefficient of FeGa micron-scale discs and the high piezoelectric coefficient of the circle surrounding the Bi5Ti3FeO15 matrices...
March 16, 2018: Nanoscale
Sergey Zhukov, Dagmar Eder-Goy, Sergey Fedosov, Bai-Xiang Xu, Heinz von Seggern
The present study is focused on tubular multi-channel arrays composed of commercial fluoropolymer (FEP) tubes with different wall thickness. After proper charging in a high electric field, such tubular structures exhibit a large piezoelectric [Formula: see text] coefficient significantly exceeding the values of classical polymer ferroelectrics and being even comparable to conventional lead-free piezoceramics. The quasistatic piezoelectric [Formula: see text] coefficient was theoretically derived and its upper limits were evaluated considering charging and mechanical properties of the arrays...
March 15, 2018: Scientific Reports
Clarisse Ribeiro, Carlos M Costa, Daniela M Correia, João Nunes-Pereira, Juliana Oliveira, Pedro Martins, Renato Gonçalves, Vanessa F Cardoso, Senentxu Lanceros-Méndez
Poly(vinylidene fluoride) (PVDF) and its copolymers are the polymers with the highest dielectric constants and electroactive responses, including piezoelectric, pyroelectric and ferroelectric effects. This semicrystalline polymer can crystallize in five different forms, each related to a different chain conformation. Of these different phases, the β phase is the one with the highest dipolar moment and the highest piezoelectric response; therefore, it is the most interesting for a diverse range of applications...
April 2018: Nature Protocols
Shi-Hao Zhang, Bang-Gui Liu
We propose through first-principles investigation that the GaTeCl monolayer is an excellent two-dimensional (2D) multiferroic with giant mechanical anisotropy. The calculated phonon spectrum, molecular dynamic simulations, and elastic moduli confirm its dynamic and mechanical stability, and our cleavage energy analysis shows that exfoliating one GaTeCl monolayer from the existing GaTeCl bulk is feasible. The calculated in-plane ferroelectric polarization reaches 578 pC m-1 . The energy barriers per formula unit of the ferroelastic 90° rotational and ferroelectric reversal transitions are 476 meV and 754 meV, respectively, being the greatest in the 2D multiferroics family so far...
March 15, 2018: Nanoscale
Kai Lu, Wen Huang, Junxiong Guo, Tianxun Gong, Xiongbang Wei, Bing-Wei Lu, Si-Yi Liu, Bin Yu
A flexible 4 × 4 sensor array with 16 micro-scale capacitive units has been demonstrated based on flexible piezoelectric poly(vinylidene fluoride) (PVDF) film. The piezoelectricity and surface morphology of the PVDF were examined by optical imaging and piezoresponse force microscopy (PFM). The PFM shows phase contrast, indicating clear interface between the PVDF and electrode. The electro-mechanical properties show that the sensor exhibits excellent output response and an ultra-high signal-to-noise ratio...
March 14, 2018: Nanoscale Research Letters
Thomas Hanser, Romain Doliveux
PURPOSE: The aim of this randomized prospective split-mouth clinical trial was to evaluate the outcome of bone block harvesting from the retromolar region using the MicroSaw and Piezosurgery. MATERIALS AND METHODS: Fifty-three patients for extensive bilateral bone grafting procedures with or without concomitant implant placement in the maxilla and/or mandible were scheduled. In each patient, bone blocks were harvested in the retromolar area within the external oblique ridge of the mandible...
March 2018: International Journal of Oral & Maxillofacial Implants
Kenji Fugito Junior, Arthur Rodriguez Gonzalez Cortes, Ricardo de Carvalho Destro, Marcelo Yoshimoto
PURPOSE: The search for optimizing rehabilitation results with the use of osseointegrated implants has led oral surgeons to look for other technologies that can provide better predictability for treatments; however, effectiveness must be considered as well. This study aimed to compare temperature variation during preparation of implant surgical beds using conventional rotary implant burs versus ultrasonic tips and to study perforation effectiveness by analyzing the functional wear of both systems and the influence of such wear on the overheating of cortical bone...
March 2018: International Journal of Oral & Maxillofacial Implants
Andrey Anatolievich Shevyrin, Arthur G Pogosov
Thin suspended nanostructures with a two-dimensional electron gas can be used as nanoelectromechanical systems in which electron transport is piezoelectrically coupled to mechanical motion and vibrations. Apart from practical applications, these systems are interesting for studying electron transport under unusual conditions, namely, in the presence of additional mechanical degrees of freedom. In the present paper, we analyze the influence of the bending on the density of a gated two-dimensional electron gas contained in a suspended membrane using the Thomas-Fermi approach and the model of pure electrostatic screening...
March 13, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Andrea Franzini, Federico Legnani, Elena Beretta, Francesco Prada, Francesco DiMeco, Sergio Visintini, Angelo Franzini
BACKGROUND: Laminoplasty and laminectomy are two common surgical procedures utilized in approaching degenerative and neoplastic disease of the spinal canal. Routinely adopted instruments, such as Kerrison rongeur or high-speed drill (HSD), entail some potentially serious complications such as dura injuring and thermal and mechanical damage to neurovascular structures. We have adopted piezoelectric bone surgery, which permits a selective cut of mineralized tissues, to perform posterior procedures on the thoracic spine, where the relationship between bone and the spinal cord are critical...
March 9, 2018: World Neurosurgery
Ramin Khayatzadeh, Fehmi Civitci, Onur Ferhanoglu, Hakan Urey
In this study, we propose a compact, lightweight scanning fiber microdisplay towards virtual and augmented reality applications. Our design that is tailored as a head-worn-display simply consists of a four-quadrant piezoelectric tube actuator through which a fiber optics cable is extended and actuated, and a reflective (or semi-reflective) ellipsoidal surface that relays the moving tip of the fiber onto the viewer's retina. The proposed display, offers significant advantages in terms of architectural simplicity, form-factor, fabrication complexity and cost over other fiber scanner and MEMS mirror counterparts towards practical realization...
March 5, 2018: Optics Express
Junliang Han, Feifei Tong, Ping Chen, Xiancai Zeng, Zhengyong Duan
This paper used piezoelectric sensor to study the dysfunction of endothelial cell monolayer barrier caused by inflammatory factors. The biocompatible conductive polymer membrane of pPy[pGlu]-pLys was prepared on the surface of the ITO work electrode to improve the interface between the endothelial cell and the electrode. Both the impedance analysis data and the stable plateau stage of sensor's frequency shift indicated that endothelial cells formed a good monolayer barrier on this polymer surface. The response frequency shifts of lipopolysaccharide (LPS)- and histamine-induced endothelial barrier dysfunction were different, which distinguished their different stimulation mechanism...
March 2, 2018: Biosensors & Bioelectronics
Avi Abadi, Gabor Kosa
Automatic manipulation of microscopic particles is very important in biology, especially in new lab-on-chip systems for automatic testing and DNA manipulation. We suggest a particle manipulation system (PMS) based on vibrating piezoelectric beams creating steady streaming flow in a viscous liquid. The flow is nearly unidirectional and it is used to control the position and velocity of the particles in the workspace of the PMS. The particles position in the PMS are controlled by visual feedback. This study presents the manipulation method, the system's model describing its behavior and characterizes experimentally its performance...
March 9, 2018: Biomedical Microdevices
Brahmanandam Javvaji, Bo He, Xiaoying Zhuang
Graphene is a non-piezoelectric material. Engineering the piezoelectricity in graphene is possible
 with the help of impurities, defects and structural modifications. This study reports the mechanism
 of strain induced polarization and the estimation of piezoelectric and flexoelectric coefficients for
 graphene system. The combination of charge-dipole potential and the strong many-body potential
 is employed for describing the inter-atomic interactions. The breaking of symmetry in graphene
 material is utilized to generate the polarization...
March 9, 2018: Nanotechnology
Carlo Lajolo, Nicola Alberto Valente, William Giuseppe Romandini, Massimo Petruzzi, Fernando Verdugo, Antonio D'Addona
BACKGROUND: The apical portion of the implant osteotomy receives less irrigation and cooling during surgical preparation. High bone temperatures, above the critical 10°C threshold, may impair osseointegration, particularly, around dense cortical bone. The aim of this study is to evaluate the apical cortical plate temperature increase with two different devices and pressure loads in a porcine rib ex-vivo model. METHODS: Twenty-four implant sites were prepared on porcine ribs divided into 4 groups of 6 samples each according to the device used (conventional drill system or piezosurgery) and pressure load applied (1000 g or 1500 g)...
March 9, 2018: Journal of Periodontology
Qi Su, Qiquan Quan, Jie Deng, Hongpeng Yu
Inspired by a way of rowing, a new piezoelectric driving quadruped micro-robot operating in bending-bending hybrid vibration modes was proposed and tested in this work. The robot consisted of a steel base, four steel connecting pins and four similar driving legs, and all legs were bonded by four piezoelectric ceramic plates. The driving principle is discussed, which is based on the hybrid of first order vertical bending and first order horizontal bending vibrations. The bending-bending hybrid vibration modes motivated the driving foot to form an elliptical trajectory in space...
March 7, 2018: Sensors
Hongpeng Yu, Qiquan Quan, Xinqi Tian, He Li
A novel U-shaped piezoelectric ultrasonic motor that mainly focused on miniaturization and high power density was proposed, fabricated, and tested in this work. The longitudinal vibrations of the transducers were excited to form the elliptical movements on the driving feet. Finite element method (FEM) was used for design and analysis. The resonance frequencies of the selected vibration modes were tuned to be very close to each other with modal analysis and the movement trajectories of the driving feet were gained with transient simulation...
March 7, 2018: Sensors
Hailing Fu, Guangzhu Chen, Nan Bai
Piezoelectric energy harvesting using cantilever-type structures has been extensively investigated due to its potential application in providing power supplies for wireless sensor networks, but the low output power has been a bottleneck for its further commercialization. To improve the power conversion capability, a piezoelectric beam with different electrode coverage ratios is studied theoretically and experimentally in this paper. A distributed-parameter theoretical model is established for a bimorph piezoelectric beam with the consideration of the electrode coverage area...
March 7, 2018: Sensors
Rusen Yan, Guru Khalsa, Suresh Vishwanath, Yimo Han, John Wright, Sergei Rouvimov, D Scott Katzer, Neeraj Nepal, Brian P Downey, David A Muller, Huili G Xing, David J Meyer, Debdeep Jena
Epitaxy is a process by which a thin layer of one crystal is deposited in an ordered fashion onto a substrate crystal. The direct epitaxial growth of semiconductor heterostructures on top of crystalline superconductors has proved challenging. Here, however, we report the successful use of molecular beam epitaxy to grow and integrate niobium nitride (NbN)-based superconductors with the wide-bandgap family of semiconductors-silicon carbide, gallium nitride (GaN) and aluminium gallium nitride (AlGaN). We apply molecular beam epitaxy to grow an AlGaN/GaN quantum-well heterostructure directly on top of an ultrathin crystalline NbN superconductor...
March 7, 2018: Nature
Shruti B Seshadri, Michelle M Nolan, Goknur Tutuncu, Jennifer S Forrester, Eva Sapper, Giovanni Esteves, Torsten Granzow, Pam A Thomas, Juan C Nino, Tadej Rojac, Jacob L Jones
Large piezoelectric coefficients in polycrystalline lead zirconate titanate (PZT) are traditionally achieved through compositional design using a combination of chemical substitution with a donor dopant and adjustment of the zirconium to titanium compositional ratio to meet the morphotropic phase boundary (MPB). In this work, a different route to large piezoelectricity is demonstrated. Results reveal unexpectedly high piezoelectric coefficients at elevated temperatures and compositions far from the MPB. At temperatures near the Curie point, doping with 2 at% Sm results in exceptionally large piezoelectric coefficients of up to 915 pm/V...
March 7, 2018: Scientific Reports
Jobin Varghese, Tuomo Siponkoski, Maciej Sobocinski, Timo Vahera, Heli Jantunen
This paper reports the first ultralow sintering temperature (450 oC) co-fired multifunctional ceramic substrate based on a commercial lead zirconium titanate (PZ29)-glass composite and fabricated by tape casting, isostatic lamination, and sintering. This substrate was prepared from a novel tape casting slurry composition suitable for co-firing at this low temperature with commercial Ag electrodes at 450 oC. The green cast tape and sintered substrate showed a surface roughness of 146 nm and 355 nm, respectively, suitable for device level fabrication by post-processing...
March 7, 2018: ACS Applied Materials & Interfaces
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