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- 2018
- medical application
- electrical capacitance tomography
- electrical impedance tomography
- Optoelectronic Information Science and Engineering
- University of Manchester
- Chiba University
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Ferroelectric‐Polymer‐Enabled Contactless Electric Power Generation in Triboelectric Nanogenerators
摘要： Triboelectric nanogenerators (TENGs) are considered as one of the most important renewable power sources for mobile electronic devices and various sensors in the Internet of Things era. However, their performance should inherently be degraded by the wearing of contact surfaces after long-term use. Here, a ferroelectric polymer is shown to enable TENGs to generate considerable electricity without contact. Ferroelectric-polymer-embedded TENG (FE-TENG) consists of indium tin oxide (ITO) electrodes, a polydimethylsiloxane (PDMS) elastomer, and a poly(vinylidene fluoride) (PVDF) polymer. In contrast to down- and non-polarization, up-polarized PVDF causes significantly large triboelectric charge, rapidly saturated voltage/current, and considerable remaining charge due to the modulated surface potential and increased capacitance. The remained triboelectric charges flow by just approaching/receding the ITO electrode to/from the PDMS without contact, which is sufficient to power light-emitting diodes and liquid crystal displays. Additionally, the FE-TENG can charge an Li-battery with a significantly reduced number of contact cycles. Furthermore, an arch-shaped FE-TENG is demonstrated to operate a wireless temperature sensor network by scavenging the irregular and random vibrations of water waves. This work provides an innovative and simple method to increase conversion efficiency and lifetime of TENGs; which widens the applications of TENG to inaccessible areas like the ocean.
关键词： contactless power generation,surface potential,capacitance,ferroelectric polymers,triboelectric nanogenerators
更新于2025-09-11 14:15:04
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A dual-channel optical fiber sensor based on surface plasmon resonance for heavy metal ions detection in contaminated water
摘要： Transition metal phosphides (TMPs) have recently emerged as an important type of electrode material for use in supercapacitors thanks to their intrinsically outstanding specific capacity and high electrical conductivity. Herein, we report the synthesis of bimetallic CoxNi1?xP ultrafine nanocrystals supported on carbon nanofibers (CoxNi1?xP/CNF) and explore their use as positive electrode materials of asymmetric supercapacitors. We find that the Co:Ni ratio has a significant impact on the specific capacitance/capacity of CoxNi1?xP/CNF, and CoxNi1?xP/CNF with an optimal Co:Ni ratio exhibits an extraordinary specific capacitance/capacity of 3514 F g?1/1405.6 C g?1 at a charge/discharge current density of 5 A g?1, which is the highest value for TMP-based electrode materials reported by far. Our density functional theory calculations demonstrate that the significant capacitance/capacity enhancement in CoxNi1?xP/CNF, compared to the monometallic NiP/CNF and CoP/CNF, originates from the enriched density of states near the Fermi level. We further fabricate a flexible solid-state asymmetric supercapacitor using CoxNi1?xP/CNF as positive electrode material, activated carbon as negative electrode material, and a polymer gel as the electrolyte. The supercapacitor shows a specific capacitance/capacity of 118.7 F g?1/166.2 C g?1 at 20 mV s?1, delivers an energy density of 32.2 Wh kg?1 at 3.5 kW kg?1, and demonstrates good capacity retention after 10000 charge/discharge cycles, holding substantial promise for applications in flexible electronic devices.
关键词： cobalt phosphide,high specific capacitance,transition metal phosphide,nickel phosphide,asymmetrical supercapacitor
更新于2025-09-11 14:15:04
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Photovoltaic, photo-impedance, and photo-capacitance effects of the flexible (111) BiFeO <sub/>3</sub> film
摘要： Ferroelectric polarization allows a depolarization electric field to separate electron-hole pairs excited by lights, and thus, the photovoltaic properties of ABO3-type films on a hard SrTiO3 or Si substrate have been extensively studied recently. However, there are a few reports on the photocapacitance and photoimpedance of these oxide films, especially on flexible substrates. In this work, the strong photovoltaic, giant photocapacitance, and photoimpedance effects were observed in the flexible (111) BiFeO3 films with natural downward polarization. The flexible mica/SrRuO3/BiFeO3/Au cells show a maximum photovoltaic efficiency at 150 °C, a 95.5% decrease in photoimpedance effects, and a 316% increase in photocapacitance effects under 405-nm-wavelength light illumination at 25 °C. Most importantly, these properties do not show obvious degradation when the device is bent to 3 mm radius for 104 times. This work is of vital importance for us to develop new flexible photoelectronic devices.
关键词： photo-capacitance,photovoltaic,flexible,photo-impedance,BiFeO3 film
更新于2025-09-11 14:15:04
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Common Mode Noise Reduction of 3-level Active Neutral Point Clamped Inverters with Uncertain Parasitic Capacitance of Photovoltaic Panels
摘要： SiC devices can upgrade the inverter performance to a new level by its potentially more than 10 times higher switching speed compared to its Si counterpart. Whereas, the high switching frequency and dv/dt, di/dt worsen the electromagnetic interference (EMI). Reduction of the common mode (CM) noise of the non-isolated photovoltaic (PV) inverters are addressed by many researchers through adding filters or balancing the circuit. However, most methods rely on the certainty of the parasitics in the system in advance. It is usually not practical for a PV inverter because the parasitic capacitance of PV panels that are to be installed in plants varies from case to case and further can be seriously affected by the damp environment. This paper proposes a practical way to reduce the CM noise of the 3-level (3L) active neutral point clamped (ANPC) inverters with uncertain parasitic capacitance of PV panels. Firstly, the CM model of ANPC inverters with all parasitic capacitances is established. Next, most existing hardware-based reduction methods of the CM noise are summarized based on a unified mathematical model and further compared with each other. After the comparison, a practical method is proposed to reduce the CM noise of the ANPC inverter with uncertain parasitic capacitances, which just adds little volume and cost to the whole system. Finally, the simulation and experiments are conducted to validate the proposed method.
关键词： EMI elimination,common mode (CM),active neutral point clamped (ANPC) topology,electromagnetic interference (EMI),Uncertain parasitic capacitance
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - ITO-Nano-Titania Gas Sensors at Adsorption of Ethanol, Acetone and Water Molecules
摘要： The measurements capacitance-voltage characteristics and capacitance kinetics were applied for investigation of physical principle of sensor response in the ITO – nanostructured titanium dioxide heterojunction. The studies were fulfilled for ethanol, acetone and water vapor under various frequencies of probing signal. It was shown that processes of surface states recharging are making the most significant contribution to the total capacitance of the studied heterojunction and playing a major role in forming of sensor response to the molecules of the used analytes.
关键词： titanium dioxide,surface states,adsorption,capacitance-voltage characteristics,capacitance kinetics,gas sensor,electronic traps,hysteresis
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Scaling of Mass and Force Using Electrical Metrology
摘要： The impending redefinition of the International System of Units (SI) allows realization of the kilogram using electrical metrology. It can be shown that electrical metrology can also be used to scale mass using electrostatic forces. An approach to mass metrology at the milligram scale using an Electrostatic Force Balance (EFB) is described. The relative uncertainty in EFB mass measurements is found to be substantially lower than those obtained with the current method based on subdivision of the artifact kilogram.
关键词： capacitance,metrology,force,voltage,standards
更新于2025-09-10 09:29:36
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Effect of capacitance on ZnO-Bi2O3-Yb2O3 based varistor for nanosecond transients; 电容对毫微秒瞬变用 ZnO-Bi2O3-Yb2O3 基压敏电阻的影响;
摘要： The microstructure and electrical properties of ZnO-Bi2O3-Yb2O3 based varistor ceramics were investigated with various temperature effects from 900 °C to 1050 °C. From the results, it was observed that the increase of sintering temperature offers a reduced capacitive effect from 0.460 nF to 0.321 nF. Furthermore, the grain sizes of varistors were varied from 6.8 μm to 9.8 μm. The consequence of such smaller grain sizes provided a better voltage gradient of about 895 V/mm for the disc sintered at 900 °C and fallen drastically to 410 V/mm for the sample sintered at 1050 °C. In addition, there was an increase of non-linearity index to a maximum value of 36.0 and reduced leakage current of 0.026 mA/cm2. However, the density of the varistor decreased with an increase of temperature from 5.41 g/cm3 to 5.24 g/cm3. With this base, the influence of varistor capacitance and high voltage gradient were scrutinized and it led an improved transition speed of the varistor assembly from non-conduction to conduction mode during intruding nanosecond transients.
关键词： nanosecond transient,rare earth oxide,metal oxide varistor,transition delay,capacitance,ytterbium oxide
更新于2025-09-10 09:29:36
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Enhancing the inherent piezoelectric behavior of a three-dimensionally printed acrylate polymer by electrical poling
摘要： A three-dimensionally (3D) printed acrylate polymer without filler, printed by stereolithography, has previously been shown to be inherently piezoelectric in the out-of-plane and in-plane directions in the absence of electrical poling. This work has shown that the longitudinal piezoelectric coupling coefficient d is increased by poling at an electric field of 2400 V m?1 by up to about 200%. The poling takes 60 min for either direction. The effect of in-plane poling on the in-plane piezoelectric effect is greater than the effect of out-of-plane poling on the out-of-plane piezoelectric effect. This is due to the lower piezoelectric coefficient without poling for the in-plane direction, consistent with the fact that the molecular alignment is 2D in the plane of the printed layers and the in-plane poling is conducted in a particular in-plane direction. Without poling, d is smaller for the in-plane direction than the out-of-plane direction. With poling, d is essentially equal for the two directions. This suggests that the in-plane poling possibly causes the in-plane molecular alignment to develop a slight degree (if any) of 1D molecular alignment. The natural depoling that occurs immediately after the completion of the poling takes as little as 60 min, with the depoling being faster in the out-of-plane direction than the in-plane direction. Due to the depoling, the inherent piezoelectric behavior without poling remains practically attractive.
关键词： acrylate,capacitance,piezoelectric,poling,3D printing,permittivity,polymer
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Reference Ultra Low DC Current Source (ULCS) Between 1 fA and 100pA at TüB?:TAK UME
摘要： We present a programmable ultra low DC current source (ULCS), developed at TüB?TAK UME, from 1 fA up to 100 pA with 100 aA resolution. The principle of the device is based on applying a ramp voltage on standard capacitors with values between 1 pF and 1000 pF. The standard capacitors are kept in a temperature controlled box. The device is fully automated with computer control and can be used to generate any currents with 100 aA resolution in its range.
关键词： ramp voltage,capacitance measurement,DC Low current,uncertainty,temperature control
更新于2025-09-10 09:29:36
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Fully Depleted SOI Pixel Detector With Multijunction Structure in p-Type Substrate
摘要： A fully depleted silicon-on-insulator (SOI) pixel detector with multijunction structure in p-type substrate is proposed to reduce the diode capacitance and improve the effective shielding between the SOI circuits and sensor. A buried p-well (BPW) and a buried n-well (BNW) are applied to their respective bias voltages to shield SOI circuits from the sensor in the substrate. BPW is biased to counteract the back-gate effect. A deeply BPW is employed to form a potential barrier to electrons in BNW, stopping the front-to-back leakage current. Lateral electric field is also formed to accelerate holes to the p+ charge collector. The simulation results demonstrate that the pixel can achieve its objectives under a full depletion condition. The capacitance of the charge collector can be reduced, which depends primarily on the charge-collector/BNW junction.
关键词： fully depleted,Capacitance,silicon-on-insulator (SOI) pixel detector,crosstalk
更新于2025-09-10 09:29:36