- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2019
- 2018
- impedance spectroscopy
- molten-salt
- conductivity
- Ba0.97La0.02Ti1-xNb4x/5O3
- EIS spectrum
- Warburg element
- blocking electrodes
- liquid crystals
- electric conductivity
- Signal-to-Noise Ratio (SNR)
- Optoelectronic Information Science and Engineering
- Materials Science and Engineering
- South Ural State University
- Université de Monastir
- Majmaah University
- University of Northumbria
- Université de Sousse
- Gabes University
- Technical University of Darmstadt
- University of Huddersfield
-
Electrical transport properties and complex impedance investigation of Fe3+ and La3+ co-doping (Pb,Sr)TiO3 thin films
摘要： This work investigates the impact of Fe3+ and La3+ co-doping on the structural, electrical transport and dielectric relaxation properties of PST thin films. XRD and Raman spectroscopy data show that the Fe3+ and La3+ doping induce a pseudocubic to tetragonal structural phase transformation. Schottky barrier heights calculated from temperature-dependent current–voltage plots for the PST, PSTF and PSLTF films decreased to 1.20, 0.59, and 0.36 eV, respectively. This behavior was directly assigned to the increase in oxygen vacancies. The frequency dependence of sample’s impedance revealed the presence of the typical electrical relaxation phenomenon in all films. Activation energies calculated from the imaginary part of the impedance are 1.73 and 0.57 eV: the high value (1.73 eV, PST films) suggests the presence of long-range oxygen vacancy diffusion, while the lower one (0.57 eV PSLTF films) should be associated to the short-range oxygen vacancy diffusion.
关键词： Dielectric relaxation,Thin films,Electrical transport,Impedance spectroscopy
更新于2025-09-23 15:21:01
-
[IEEE 2018 EMF-Med 1st World Conference on Biomedical Applications of Electromagnetic Fields (EMF-Med) - Split, Croatia (2018.9.10-2018.9.13)] 2018 EMF-Med 1st World Conference on Biomedical Applications of Electromagnetic Fields (EMF-Med) - Measurement of Weak Low Frequency Electromagnetic Field Effects on Cells
摘要： The aim of our research is a development of an automated experimental platform for identification of the effects of weak low frequency (LF) electromagnetic field (EMF) on cells. The platform comprises multiple measurement stations, allowing monitoring and subsequent characterization of cell cultures. Main detection methods include electroimpedance spectroscopy (EIS), optical microscopy, and turbidimetry. EIS provides information about cell culture growth and enables electrical characterization of cell structures. Morphology and cell kinetics are investigated via computer analysis of images obtained from video-microscopy. The complex measurement system allows efficient scanning of frequencies and amplitudes of EMF while searching for possible specific response of investigated biosystem. The developing platform aspires to contribute towards general methodology of investigation into LF EMF biological effects.
关键词： microscopy image analysis,impedance spectroscopy,COST EMF-MED,low frequency electromagnetic fields
更新于2025-09-23 15:21:01
-
[IEEE 2019 IEEE International Electron Devices Meeting (IEDM) - San Francisco, CA, USA (2019.12.7-2019.12.11)] 2019 IEEE International Electron Devices Meeting (IEDM) - Area-Selective-CVD Technology Enabled Top-Gated and Scalable 2D-Heterojunction Transistors with Dynamically Tunable Schottky Barrier
摘要： Neurological or biomechanical disorders may distort ankle mechanical impedance and thereby impair locomotor function. This paper presents a quantitative characterization of multivariable ankle mechanical impedance of young healthy subjects when their muscles were relaxed, to serve as a baseline to compare with pathophysiological ankle properties of biomechanically and/or neurologically impaired patients. Measurements using a highly backdrivable wearable ankle robot combined with multi-input multi-output stochastic system identification methods enabled reliable characterization of ankle mechanical impedance in two degrees-of-freedom (DOFs) simultaneously, the sagittal and frontal planes. The characterization included important ankle properties unavailable from single DOF studies: coupling between DOFs and anisotropy as a function of frequency. Ankle impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness in both seated (knee flexed) and standing (knee straightened) postures. Stiffness in the sagittal plane was greater than in the frontal plane and furthermore, was greater when standing than when seated, most likely due to the stretch of bi-articular muscles (medial and lateral gastrocnemius). Very low off-diagonal partial coherences implied negligible coupling between dorsiflexion-plantarflexion and inversion-eversion. The directions of principal axes were tilted slightly counterclockwise from the original joint coordinates. The directional variation (anisotropy) of ankle impedance in the 2-D space formed by rotations in the sagittal and frontal planes exhibited a characteristic “peanut” shape, weak in inversion-eversion over a wide range of frequencies from the stiffness dominated region up to the inertia dominated region. Implications for the assessment of neurological and biomechanical impairments are discussed.
关键词： multivariable impedance,stiffness anisotropy,ankle stiffness,Ankle joint,human ankle,ankle joint stiffness,impedance structure,multivariable stiffness
更新于2025-09-23 15:19:57
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Water Free Cleaning Solution: Environmental Durability of Electrodynamic Screen (EDS) Films in Water-Free Cleaning of Solar Collectors
摘要： We demonstrate the performance enhancement of field-effect transistor (FET)-based plasmonic terahertz (THz) detector with monolithic integrated antenna in low-impedance regime and report the experimental results of Si MOSFET impedance in THz regime using 0.2-THz measurement system. By designing FET with low-impedance ranges (<1 kΩ) and integrating antennas with impedances of 50 and 100 Ω, we found that our low-impedance MOSFETs have the input impedance criterion of 50 Ω at 0.2 THz and the MOSFETs with thinner gate oxide show the highly enhanced plasmonic photoresponses at 50-Ω antenna by 325 times from the result of the detector without antenna.
关键词： terahertz,impedance,photoresponse,MOSFET,detector,plasmonic
更新于2025-09-23 15:19:57
-
Application of ZnxLayFezO4 spinel nanomaterial in quantum dot sensitized solar cells
摘要： A novel inorganic spinel nanomaterial with formula Zn0.6093La1.3979Fe0.8650O4 (ZLF) was synthesized and characterized by the X-ray photoelectron spectroscopy (XPS) to determine its stoichiometric formula. The Filed-Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) images displayed that the ZLF nanoparticles (NPs) had a very fine spherical morphology and average particle sizes in the range of about 5–30 nm. Quantum dot-sensitized solar cells (QDSSCs) were fabricated using the ZLF NPs which were incorporated into the TiO2 pastes of photoanodes. The photoluminescence (PL) spectra of the ZLF NPs and the photoanodes exhibited three maxima plus a weak broad peak at around 420, 460 and 485 plus 530 nm. The lowest intensity of the PL peak for the CdSe cell fabricated using 0.4 %ZLF suggested that it had the least charge recombination and the easiest electron transfer. The photovoltaic parameters of the optimized champion cell containing 0.4 % of ZLF NPs (η = 3.50 %, JSC = 13.11 mA/cm2, VOC = 0.58 V) were boosted compared to those of the ZLF-free reference cell (η = 2.18 %, JSC = 8.70 mA/cm2, VOC = 0.57 V) demonstrating a high improvement of approximately 61 % in the efficiency. The Electrochemical Impedance Spectra (EIS) revealed that the charge transfer resistance (RCT) in the optimum cell was dropped by adding the ZLF NPs into the TiO2 compared to that of the reference ZLF-free cell. Thus, upon adding 0.4 %ZLF, appropriate photocurrent efficiency was attained for the QDSSC because the ZLF nanoparticles were used in a minimum amount in order to speed up the electron transport, decline the recombination and enhance the cell efficiency.
关键词： Photoluminescence spectra,Spectra,ZnLaFeO4nanoparticles,Quantum dot sensitized solar cells,Electrochemical impedance (EIS),XPS
更新于2025-09-23 15:19:57
-
Current-voltage and capacitance study of light-induced metastabilities in CuZnSnSSe thin-film solar cells
摘要： White, red and blue light-induced metastabilities in Cu2ZnSnS4(Se4) solar cells were investigated by temperature dependent current-voltage measurements, drive level capacitance profiling, impedance and thermal admittance spectroscopy. A set of devices were studied where white and blue light soaking at room temperature led to degradation of the device performance, while after red light soaking the solar cell efficiency did not change. We observed a significant effect of light soaking on capacitance data measured in both low and high-temperature ranges for these devices. In particular, the net doping concentration extracted from drive-level capacitance profiling substantially increased after light soaking treatments. Low and high-temperature capacitance steps observed in the reference capacitance-frequency spectra were assigned to Fermi level pinning and bulk defects, correspondingly. Light soaking with different-wavelength light led to a shift of both steps toward the high-frequency range, and hence a decrease in the thermal admittance activation energies. A low-frequency “inductive” loop was detected in the impedance spectra after light soaking, regardless of wavelength. It was proposed that the appearance of the “inductive” loop is due to the formation of a negative electric field at the highly defected CdS/Cu2ZnSnS4(Se4) hetero-interface. This result also leads us to conclude that such electric field is responsible for the metastable behaviour of these devices at room temperature, while the low temperature metastable changes might have a different origin. We also discuss the methodology for electrical characterization of the metastable solar cells in detail.
关键词： impedance spectroscopy,metastability,kesterite solar cells,electrical characterization
更新于2025-09-23 15:19:57
-
Frequency-dependent equivalent modelling of broadband air-coupled transducers
摘要： Electrical impedance is an essential parameter for characterizing the performance of transducers during manufacturing and application phases. The Conventional method to model the electrical impedance is based on Butterworth-Van Dyke (BVD) model with constant equivalent parameters, which is valid only in the neighborhood of resonance frequency. In this study, we present a method for modelling the electrical impedance over broadband featuring improved BVD model with frequency-dependent equivalent parameters. In order to obtain frequency-dependent parameters from the measured impedance, estimation is performed in a constrained piecewise and stepwise manner. Firstly, a concise calculation method to obtain initial values of equivalent parameters is presented. Then, the original impedance is equally divided into multiple segments and the resonant segments containing the resonant frequencies are located. New impedance data is reconstructed with one of non-resonant segments and the resonant segments. Finally, with the initial values refined by genetic algorithm (GA), equivalent parameters are obtained from the reconstructed impedance based on GA. The estimation results are assigned to the central frequency point of the non-resonant segment. A new segment is generated by shifting the last non-resonant segment one frequency interval, and data reconstruction and estimation process are repeated till all parameters at each frequency are gained. Frequency-dependent parameters are obtained by the combination of a series of constant parameters at each frequency. The proposed method is verified with good accuracy in modelling of electrical impedance and transmitting response of broadband air-coupled transducer used for gas flow measurement which are difficult to be accurately modelled by the traditional method.
关键词： Electrical impedance,frequency-dependent parameters,improved BVD model,broadband air-coupled transducers
更新于2025-09-23 15:19:57
-
Dynamic Response-Based LEDs Health and Temperature Monitoring
摘要： this paper presents a number of novel methods to measure the junction temperature and to estimate the health of gallium nitride light-emitting diodes (LEDs). The methods are based on measurements of the dynamic impedance and optical output. Our experimental analysis reveals temperature sensitive parameters of the electrical and optical responses. Moreover, a correlation between the non-radiative current characterizing the defects in the active region and the small-signal impedance is demonstrated. The demonstrated methods can be applied to enhance existing techniques. The temperature-monitoring derived dependencies also build a foundation for advanced in-field monitoring health of the LEDs and for prediction of imminent failures using the infrastructure of visible light communication systems. Such models are valuable for predictive maintenance.
关键词： smart driver,failure modes,temperature,impedance,OWC,electrical response,optical response,defects,LED,reliability
更新于2025-09-23 15:19:57
-
Analysis of a single-mode waveguide at sub-terahertz frequencies as a communication channel
摘要： We study experimentally the transmission of an electromagnetic waveguide in the frequency range from 160 to 300 GHz. Photo-mixing is used to excite and detect the fundamental TE10 mode in a rectangular waveguide with two orders-of-magnitude lower impedance. The large impedance mismatch leads to a strong frequency dependence of the transmission, which we measure with a high-dynamic range of up to 80 dB and with high frequency-resolution. The modified transmission function is directly related to the information rate of the waveguide, which we estimate to be about 1 bit per photon. We suggest that the results are applicable to a Josephson junction employed as a single-photon source and coupled to a superconducting waveguide to achieve a simple on-demand narrow-bandwidth free-space number-state quantum channel.
关键词： communication channel,TE10 mode,sub-terahertz frequencies,Josephson junction,impedance mismatch,superconducting waveguide,single-photon source,waveguide
更新于2025-09-23 15:19:57
-
A fully electronically tunable millimeter wave lab-in-waveguide nano-fluidic sensor
摘要： In this paper, we report an ultra-sensitive millimeter wave (mm-wave) reflection liquid sensor, which is electronically tunable, non-invasive, and label-free. The reflection liquid sensor is based on the impedance match technique. It is implemented in a rectangular waveguide structure, which makes the interaction between mm-wave and liquid under test (LUT) in a closed environment, forms a nano-fluidic lab-in-waveguide liquid sensor, and isolates the interference of surroundings. The reflection liquid sensor shows high sensitivity to permittivity change of the LUTs. Taking the ethanol-distilled water as benchmark, a more than 62 dB ethanol-distilled water contrast is experimentally achieved. The detection limit is 0.05% ethanol in volumetric concentration with a 4 dB signal difference, which is the best performance of the microwave and mm-wave liquid sensors publicly reported until now. The ultra-sensitive reflection sensor can be used for bio-chemical sensing. The lab-in-waveguide biosensor is also compatible with microfluidics.
关键词： impedance match,electronically tunable,liquid sensor,label-free,millimeter wave,non-invasive
更新于2025-09-23 15:19:57