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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • medical application
  • electrical capacitance tomography
  • electrical impedance tomography
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • University of Manchester
  • Chiba University
123 条数据
?? 中文（中国） ▾

  • [IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Optical Power Dependence of Capacitance in Uni- Traveling-Carrier Photodetectors

    摘要： Optical power dependence of capacitance in uni-traveling-carrier photodetectors is analyzed by a model for capacitance calculation. The relationship between light-intensity-dependent capacitance and DC saturation characteristics of the device is found through the experiments and simulations.

    关键词： uni-traveling-carrier photodetectors,capacitance,optical power

    更新于2025-09-12 10:27:22

  • [IEEE 2019 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) - Boston, MA, USA (2019.5.29-2019.5.31)] 2019 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) - Highspeed Broadband Optical Modulation with Small Footprint Symmetrical IMI Graphene Hybrid Plasmonic Waveguide

    摘要： The modal properties and modulation characteristics of the fundamental gap mode supported by nanowire based symmetrical IMI graphene hybrid plasmonic waveguide are investigated employing the finite element method. The proposed modulator even with its remarkably small footprint offers both high extinction ratio (as high as 40 dB) and large modulation bandwidth (as large as 237 GHz) simultaneously with only 2.4 μm long active region at the telecommunication wavelength. The optical capacitance effect along with IMI like mode coupling are reported here for this improved modulation performance. Furthermore, a deep subwavelength mode size (~λ2/400) with low energy consumption per bit (as small as 0.9 fJ/bit) suggests its highly dense integration in photonic integrated circuits. Also, the performance variation of this waveguide is explored with respect to the alteration of operating wavelength and cross-sectional geometry.

    关键词： hybrid plasmonic waveguide,Extinction ratio,surface plasmon polariton,graphene,optical capacitance

    更新于2025-09-12 10:27:22

  • [IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Design and Fabrication of a Coupled Dual-Coil for Fingerprint Sensor Application

    摘要： This paper presents a novel concept that uses the mutual inductance of a spiral dual-coil to identify fingerprint patterns. Unlike commercial optical and capacitive sensing technologies, this unique dual-coil design enables the measurement of a fingerprint by the effect of ridges and valleys on electrical impedance. In this study, a typical sensing chip with a 3×128 dual-coil array was fabricated by microfabrication process. The variations of coupling capacitance and mutual inductance were then used to verify the properties of different mediums. The measurement results show that the resonant frequency is produced at 8 MHz, which results in a maximum induced current of 1 mA and a phase shift of 41.3 degrees. Higher conductivity mediums cause larger phase shifts. Sample data resulting from a dual-coil array were successfully used to reconstruct a fingerprint image.

    关键词： dual-coil,fingerprint sensor,microfabrication,coupling capacitance,mutual inductance

    更新于2025-09-12 10:27:22

  • Quantifying charge carrier density in organic solar cells by differential charging techniques

    摘要： Accurate determination of charge carrier density in organic solar cells under light irradiation is essential because charge carrier density is directly related to the bimolecular recombination rate and open-circuit voltage of the cells. We investigate the robustness of transient photovoltage/current (TPV/C) and impedance spectroscopy (IS) to interference from the geometric capacitance of the cells (Cgeo) during quantification of the charge carrier density. TPV/C and IS accurately quantify the charge carrier density of bulk heterojunction cells with small Cgeo. For planar heterojunction cells with a larger Cgeo contribution, IS fails to separate the charge carriers in the organic layer from those in the electrodes. In contrast, TPV/C eliminates the effect of Cgeo and gives a reasonable estimation of the charge carrier density in the organic layer with the planar heterojunction, demonstrating that TPV/C is more robust than IS to interference from Cgeo of the cells.

    关键词： transient photovoltage/current,geometric capacitance,charge carrier density,organic solar cells,impedance spectroscopy

    更新于2025-09-12 10:27:22

  • Active control on switchable waveguide of elastic wave metamaterials with the 3D printing technology

    摘要： Propagation of elastic waves along a direction has special interests in practical applications. These concerns generate the design of an elastic wave metamaterial with electrically switchable properties, which is studied in this work. The structure contains a T-shaped waveguide in a plate with the 3D printing technology; and the active control system is used to tune the propagation direction of the flexural wave. The piezoelectric patches which are connected by the negative capacitance circuits are applied to behave as the active control system. The finite element simulation is performed to give the theoretical prediction of the switchable waveguide and the tunable equivalent parameters are achieved by the electrical circuits. The active control experiments are finally carried out to support the numerical design.

    关键词： 3D printing technology,switchable waveguide,elastic wave metamaterials,negative capacitance circuits,active control,piezoelectric patches

    更新于2025-09-12 10:27:22

  • Characterization and validation of an in vivo confocal Raman spectroscopy led tri‐method approach in the evaluation of the lip barrier

    摘要： Background/Aim: It was the aim to establish and validate in vivo confocal Raman spectroscopy for characterization of the lip barrier in conjunction with transepidermal water loss (TEWL) and skin capacitance assessments. For the first time in vivo, barrier-relevant components of the lip (derived, natural moisturizing factors (NMFs) and ceramides are described. Methods: In 32 healthy volunteers, a dental tongue fixation device was inserted to prevent both voluntary and involuntary lip moisturization during measurements. Seventeen individual parameters relating to water, ceramide, and NMF content were assessed via Raman spectroscopy. Additionally, corneometry and TEWL were measured. To give a guidance for the required volunteer group size of future lip barrier studies for all test parameters, coefficients of variation (CV) were calculated and plots showing the required sample size for a given percentage treatment effect. Results: Raman spectroscopy assessed parameters on the lower lip comprehensively characterized the state of the lip barrier. Parameter variability was sufficiently low to corroborate changes in most parameters using relatively small study populations. Conclusions: Lip skin is comparatively well hydrated. Biophysical measurement of the lip barrier function is a challenge, as unconscious licking of the lower lip has to be prevented. In vivo confocal Raman spectroscopy provides insightful parameters for the characterization of the lip barrier and sufficiently low inter-individual variability to assess relatively small parameter changes employing relatively few study subjects. Differences at the molecular level and at a high spatial resolution are detectable, and these insights might provide a breakthrough in the evaluation of lip barrier function and developing solutions for lip care.

    关键词： lip skin measurements,closed chamber transepidermal water loss,lip stratum corneum,skin hydration capacitance,Raman spectroscopy

    更新于2025-09-12 10:27:22

  • Diffusion charge compensation strategy for power balancing in capacitor-less photovoltaic modules during partial shading

    摘要： Photovoltaic arrays are highly susceptible to the partial shading that drastically reduces the power output by forming multiple peaks in the characteristics curves complicating the operation of maximum power point trackers (MPPTs). In this paper, a new diffusion charge compensation strategy for power enhancement in the arrays during partial shading has been proposed. The strategy eliminates the requirement of bypass diodes and passive energy storage components and uses the inherent diffusion capacitance of the module for power balancing during shading reducing cost and complexity. The strategy has been tested in MATLAB/Simulink environment and validated experimentally under various partial shading scenarios. The proposed strategy increases the power output and improves the tracking efficiency of the MPPTs by forming single maxima in the characteristics curves of the array during partial shading as compared to the conventional arrays with and without bypass diodes. Also, the proposed strategy excels in performance by increasing the power output of arrays during partial shading with a conversion efficiency of nearly 98%.

    关键词： Photovoltaic,Power generation,Partial shading,Diffusion capacitance,Maximum power point tracker,Charge compensation

    更新于2025-09-12 10:27:22

  • Ionic liquid/ZnO(0001?) single crystal and epitaxial film interfaces studied through a combination of electrochemical measurements and a pulsed laser deposition process under vacuum

    摘要： O-Polar ZnO(000%1) single crystals and ZnO and Mg-doped ZnO (MgZnO) films which were subsequently deposited on the ZnO crystals by a pulsed laser deposition (PLD) method were electrochemically investigated through the interfaces with ionic liquid (IL) in a vacuum. The sample surfaces were confirmed to be atomically clean and flat by reflection high energy electron diffraction (RHEED) observation, prior to their electrochemical measurements. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were then performed, and the donor density, flat band potential of these ZnO samples, and the electric double layer capacitance at the IL/ZnO interfaces were successfully evaluated. The flat band potentials of ZnO and MgZnO films were found to shift to more negative potentials relative to those of the single crystal ZnO, with different values for thicker films, respectively. Some possible origins of the different flat band potentials between ZnO and MgZnO films, and their film thickness dependence of the flat band potential will be discussed in this paper.

    关键词： vacuum,ZnO,flat band potential,pulsed laser deposition,MgZnO,electric double layer capacitance,ionic liquid,electrochemical measurements

    更新于2025-09-12 10:27:22

  • [IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Electrical Properties of Oxide-Confined Vertical-Cavity Surface-Emitting Lasers

    摘要： We present a comprehensive description of electrical properties of vertical-cavity surface-emitting lasers (VCSELs) based on a drift-diffusion model applied to carrier transport in 3D multilayer semiconductor laser heterostructure with a p-n junction. We address the impact of interface grading in distributed Bragg reflectors (DBRs), modulation doping of the DBRs and surrounding layers of the quantum well (QW) as well as material-dependent carrier mobilities and recombination constants and are focused on oxide-confined GaAs/AlGaAs VCSELs. We evaluate both depletion and diffusion capacitance and show that both contributions to the capacitance as well as the differential series resistance critically depend on the injection current and chip design such that, in general, VCSEL cannot be properly modeled by an equivalent circuit approximation. Current profiles demonstrate significant increase of the current density at the edges of the oxide-confined aperture (current crowding) which could be suppressed by a proper design.

    关键词： current crowding,differential resistance,oxide aperture,carrier transport,capacitance,modulation frequency bandwidth,vertical cavity surface-emitting laser

    更新于2025-09-12 10:27:22

  • [IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - An Extraction Method for the Parasitic Capacitance of the Photovoltaic Module Based on the Oscillation of the Leakage Current

    摘要： In photovoltaic (PV) plant, the parasitic capacitance between the PV module and the ground causes leakage current in the non-isolated systems. The case can be deteriorated in the rain environment, because increases dramatically due to the rain water. This paper presents an extraction method for the parasitic capacitance between the PV module and the ground. Unlike the common analytical, numerical way and direct measurement method, the parasitic capacitance is obtained through measurement of the leakage current oscillation. A full-bridge inverter is used to explain the principle as well as for the measurement. Theoretical calculation, MATLAB simulations and experimental measurements finally verify the accuracy of the proposed methods. The experimental results are shown to validate the method works well.

    关键词： photovoltaic module,parasitic capacitance,leakage current,oscillation

    更新于2025-09-11 14:15:04