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[American Society of Agricultural and Biological Engineers 2017 Spokane, Washington July 16 - July 19, 2017 - ()] 2017 Spokane, Washington July 16 - July 19, 2017 - Design and modeling of grain impact sensor utilizing two crossed polyvinylidene fluoride films
摘要： In order to reduce the unavoidable grain losses during harvesting, the combine harvester’s operational parameters should be adjusted accordingly. So, it is important to develop a real-time sensor which can monitor the grain losses. A grain impact sensor utilizing crossed piezoelectric polyvinylidene fluoride (PVDF) films as sensitive material is described. This sensor is composed of two crossed layers of sensor unit arrays, a damping layer and a support plate. The two layers are insulated from each other but can detect the impact simultaneously. The sensor unit arrays of those two layers are perpendicular and the sensor units in each layer are independent and parallel. Each sensor unit has its independent signal processing circuit, which is composed of charge amplifier, band-pass filter, envelope detector and voltage comparator. Two signals from two layers presented a two-dimensional impact position information through multi-sensor fusion technology. The sensor can obtain the spatial distribution of grain loss accurately to reduce the error-recognition ratio. Moreover, the grain impact sensor was simulated by finite element method to obtain the best number and size of the sensor units for higher sensitivity, detection speed, stress transfer efficiency, deformation transfer efficiency.
关键词： double layers,grain impact sensor,multi-sensor fusion,grain loss detecting,PVDF film
更新于2025-09-23 15:22:29
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Synthesis and characterization of spin-coated clay/PVDF thin films
摘要： This paper reports the fabrication of Cloisite-15A (C-15A)-dispersed polyvinylidene fluoride (PVDF) nanocomposite thin films by spin coating and their characterization for sensor applications. The effects of nanoclay, duration of ultrasonication and spinning speed on the morphology and properties of thin films were studied. The influence of these parameters on the amount of β-phase was analysed using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) techniques. The influence of C-15A on the morphology and surface quality of thin films was analysed by scanning electron microscopy (SEM). Piezoelectric coefficient was measured at 110 Hz and 0.25 N. Contact angle was measured to assess the hydrophobicity of thin films. The β-phase of 82.97% was obtained in the specimens with 5 wt% C-15A, processed at 500 rpm and spun for 35 min. The piezoelectricity of the specimens increased from ?18 to ?25 pC N?1. Experiments were conducted as per L16 orthogonal array.
关键词： spin coating,Cloisite-15A,β-crystals,PVDF/clay thin films,piezoelectricity
更新于2025-09-23 15:22:29
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Space debris positioning based on two-dimensional PVDF piezoelectric film sensor
摘要： In order to determine the positions of debris collision spacecraft accurately, the experiments have been performed to impact orthogonal stacking two-dimensional Polyvinylidene fluoride (PVDF) piezoelectric film at different collision speeds based on the piezoelectric effects of the PVDF film by using two-stage light gas gun loading system and the self-constructed positioning system. The debris source was positioned accurately by PVDF strips sensor and testing system, which has been established to extract piezoelectric signals of the PVDF film during the process of impacting. The visualization of the position for debris impacting spacecraft was achieved through the LABview language programme and signal processing acquired by the signal acquisition system in the experiments. The experimental results show that the positions of the debris impacting source can be realized accurately by the piezoelectric effects of the orthogonal stacking two-dimensional PVDF film, the flight velocity and the incidence angle of the debris can be determined by installing the double-set PVDF film as the targets with a certain spacing.
关键词： Debris source positioning,Hypervelocity impact,PVDF piezoelectric film,Debris
更新于2025-09-23 15:22:29
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AIP Conference Proceedings [Author(s) PHYSICS, TECHNOLOGIES AND INNOVATION (PTI-2018): Proceedings of the V International Young Researchers’ Conference - Ekaterinburg, Russia (14–18 May 2018)] - Synthesis and investigation of functional layers for composite multiferroics
摘要： This article is devoted to the synthesis and investigation of thin ferroelectric and magnetostrictive layers as potential constituents of composite multiferroics. We chose alloy Fe10Ni90 as magnetostrictive medium. The magnetic anisotropy and magnetoelastic properties of films Fe10Ni90 are investigated. It is shown that they can be significantly modified with a variation in the thickness of the samples in the range 40-80 nm. We chose polyvinylidene fluoride(PVDF) as ferroelectric medium. Its films were obtained by spin-coating and had a thickness of ~200 nm. The analysis of the crystallinity and phase composition of the films are completed. It is established that the factors influencing on these properties are the thickness of the films and the conditions for their heat treatment. The magnetic properties of the PVDF / Fe10Ni90 film structures with optimized parameters of layered components are determinate.
关键词： magnetostrictive,PVDF,ferroelectric,composite multiferroics,Fe10Ni90
更新于2025-09-23 15:21:21
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Electrical and Electromagnetic Interference (EMI) shielding properties of hexagonal boron nitride nanoparticles reinforced polyvinylidene fluoride nanocomposite films
摘要： The hexagonal boron nitride nanoparticles (h-BNNPs) reinforced flexible polyvinylidene fluoride (PVDF) nanocomposite films were prepared via a simple and versatile solution casting method. The morphological, thermal and electrical properties of h-BNNPs/PVDF nanocomposite films were elucidated. The electromagnetic interference (EMI) shielding properties of prepared nanocomposite films were investigated in the X-band frequency regime (8–12 GHz). The EMI shielding effectiveness (SE) was increased from 1 dB for the PVDF film to 11.21 dB for the h-BNNPs/PVDF nanocomposite film containing 25 wt% h-BNNPs loading. The results suggest that h-BNNPs/PVDF nanocomposite films can be used as lightweight and low-cost EMI shielding materials.
关键词： Hexagonal boron nitride,PVDF,SEM,EMI shielding,DSC,electrical properties
更新于2025-09-23 15:21:21
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A Robust Artificial Synapse Based on Organic Ferroelectric Polymer
摘要： Memristors with history-dependent resistance are considered as artificial synapses and have potential in mimicking the massive parallelism and low-power operation existing in the human brain. However, the state-of-the-art memristors still suffer from excessive write noise, abrupt resistance variation, inherent stochasticity, poor endurance behavior, and costly energy consumption, which impedes massive neural architecture. A robust and low-energy consumption organic three-terminal memristor based on ferroelectric polymer gate insulator is demonstrated here. The conductance of this memristor can be precisely manipulated to vary between more than 1000 intermediate states with the highest OFF/ON ratio of ≈104. The quasicontinuous resistive switching in the MoS2 channel results from the ferroelectric domain dynamics as confirmed unambiguously by the in situ real-time correlation between dynamic resistive switching and polarization change. Typical synaptic plasticity such as long-term potentiation and depression (LTP/D) and spike-timing dependent plasticity (STDP) are successfully simulated. In addition, the device is expected to experience 1 × 109 synaptic spikes with an ultralow energy consumption for each synaptic operation (less than 1 fJ, compatible with a bio-synaptic event), which highlights its immense potential for the massive neural architecture in bioinspired networks.
关键词： artificial synapses,organic,PVDF,ferroelectric,memristors
更新于2025-09-23 15:21:21
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Light driven PVDF fibers based on photochromic nanosilica@naphthopyran fabricated by wet spinning
摘要： Photoresponsive polyvinylidene fluoride (PVDF) fibers doped with naphthopyran-functionalized silica nanoparticles (SiO2@NPT) were successfully prepared by dry–jet wet spinning. The incorporated photochromic nanomaterials, SiO2@S1 and SiO2@S2, were previously prepared by covalent post-grafting of the silylated NPTs – 2H-naphtho[1,2-b]pyran derivatives, S1 and S2 – onto nano-sized SiO2 (15 ± 3 nm). The morphological and chemical characterization of the resulting doped fibers PVDF@SiO2@S1 and PVDF@SiO2@S2 was evaluated by scanning electron microscopy with energy dispersive spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Both PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers presented average diameters of 133 ± 8 μm and 98 ± 7 μm, respectively, and a porous outer surface. The presence of the SiO2@NPT within the fibers was confirmed through the observation of dense clusters embedded within the polymeric matrix. Furthermore, the FTIR-ATR spectra of the fibers revealed that the PVDF matrix was composed of α and β crystalline and amorphous phases. The PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers showed photoresponsive properties under UV and sunlight irradiation, exhibiting fast coloration kinetics and good optical contrast (ΔE*ab = 7.2 and 15.1, respectively), and changing from a pale orange and an off-white color to a more intense yellow-orange and purple coloration, respectively, in less than 1 min. Moreover, they showed an initial fast bleaching, losing half of their color in less than 30 min (t1/2 = 28 and 20 min for PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers, respectively), but displaying a residual coloration that took 1 and 2 h to return to the initial uncolored state (t3/4 = 95 and 49 min, respectively). The PVDF@SiO2@S2 fibers presented the best photochromic performance.
关键词： Photochromism,Silica nanoparticles,PVDF fibers,Naphthopyrans,Wet spinning
更新于2025-09-23 15:21:21
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Ablation of piezoelectric polyvinylidene fluoride with a 193 nm excimer laser
摘要： The unique flexible and piezoelectric properties of polyvinylidene fluoride (PVDF) films would allow for new applications for integrated bioelectronic devices. The use of these films has been precluded by the difficulty in machining them into small, discrete features without damaging the properties of the material. The etching of piezoelectric PVDF by means of a 193 nm excimer laser is explored and characterized. Etch rates are shown for common laser fluence values, along with images of the quality of the cuts to provide the reader with an understanding of the compromise between etch rate and edge roughness. The authors describe a novel method for the etching of piezoelectric, β-phase PVDF. While PVDF is flexible, acoustically matched to biological tissue, and has a wide resonance bandwidth, it is often overlooked as a piezoelectric material for micro-electrical-mechanical-system devices because of the difficulty in fabrication. In this paper, the authors characterize the etch rate and quality while using a 193 nm argon fluoride excimer laser for patterning.
关键词： excimer laser,etching,piezoelectric,ablation,PVDF
更新于2025-09-23 15:21:01
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Cowpea-structured PVDF/ZnO Nanofibers Based Flexible Self-powered Piezoelectric Bending Motion Sensor Towards Remote Control of Gestures
摘要： Interactive human-machine interface (iHMI) is a bridge connecting human beings and robots, which has an important requirement for perceiving the change of pressure and bending angle. Here, we designed a flexible self-powered piezoelectric sensor (PES) based on the cowpea-structured PVDF/ZnO nanofibers (CPZNs) for remote control of gestures in human-machine interactive system. Due to the synergistic piezoelectric effect of hybrid PVDF/ZnO and the flexibility of polymer, this PES exhibited excellent bending sensitivity of 4.4 mV deg-1 ranging widely from 44 ° to 122 °, fast response time of 76 ms, and good mechanical stability. Besides, the PES could operate under both bending and pressing mode, show ultrahigh pressing sensitivity of 0.33 V kPa-1, with response time of 16 ms. When integrated in iHMI, the PES could be conformably covered on different curve surfaces, demonstrated accurate bending angle recording and fast recognition for realizing intelligent human-machine interaction. On this basis, the application of remote control of robotic hand was successfully realized in form of acting the same gesture as human hand synchronously. This CPZNs-based self-powered PES is distinct and unique in its structure and fundamental mechanism, and exhibits a prospective potential application in iHMI.
关键词： human-machine interaction,cowpea-structured nanofiber,bending monitoring,self-powered,PVDF/ZnO
更新于2025-09-23 15:21:01
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Strategies to Achieve High Performance Piezoelectric Nanogenerators
摘要： Piezoelectric nanogenerators have attracted much attention in the past decade. In this study, the development of piezoelectric nanogenerators and their progress toward high power generation is discussed. The characteristics and application range of numerous types of piezoelectric nanogenerators are also considered. In addition, several strategies that may improve the performance of piezoelectric nanogenerators are summarized. Here, we compare the open circuit voltages and short circuit currents of various piezoelectric nanogenerators under different factors, and the current problems of piezoelectric nanogenerators are also discussed. Finally, the future prospects and directions of piezoelectric nanogenerators are predicted. Future studies should be focused on the production of high-performance materials, the establishment of working principle and simulation model, the integration of nanogenerator, and the design of the energy harvesting circuit. Hence, it is emergency to search for functional materials with high piezoelectricity and further improve the electromechanical properties of existing piezoelectric materials. Moreover, further research is needed to increase the stability and flexibility of composite materials, to develop wearable and embedded flexible functional devices based on the biocompatibility of inorganic nanoparticles, and to supply power for microelectronic systems.
关键词： BaTiO3,Piezoelectric nanogenerators,Composite thin film materials,PVDF,Chemical doping,Nanostructure
更新于2025-09-23 15:21:01