Topic
Electrical impedance
About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.
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TL;DR: In this article, an investigation into monitoring the moisture condition of cement-based materials using impedance spectroscopy techniques is presented, where impedance measurements are made over the frequency range 20 Hz-110 MHz.
Abstract: This paper outlines an investigation into monitoring the moisture condition of cement-based materials using impedance spectroscopy techniques. Impedance measurements are made over the frequency range 20 Hz-110 MHz, and several parameters identified which could characterise the moisture condition of such materials.
97 citations
TL;DR: In this article, an intrinsic resonance at a fixed ultrasonic frequency of 37.6 kHz was found in the ac impedance spectra of carbon nanotubes, which could be used to compensate capacitance in electronic circuits or to fabricate nanotube-based transducers.
Abstract: Carbon nanotubes exhibit exceptional dc electrical transport but relatively little is known about their ac behavior. We discover, in the ac impedance spectra of nanotubes, an intrinsic resonance at a fixed ultrasonic frequency of 37.6 kHz. In the 100 Hz to 8 MHz frequency range the overall impedance shows a negative capacitance associated with the dynamical response of the metal-nanotube contact. These effects could be used to compensate capacitance in electronic circuits or to fabricate nanotube-based transducers.
97 citations
01 Mar 2013
TL;DR: In this article, a physical model of an interdigitated sensor working in a frequency range from 100 Hz to 10 MHz was used to optimize the use of the sensor for bioimpedance spectroscopy.
Abstract: This paper is concerned with a physical model of an interdigitated sensor working in a frequency range from 100 Hz to 10 MHz. A theoretical approach is proposed to optimize the use of the sensor for bioimpedance spectroscopy. The correlation between design parameters and frequency behavior in coplanar impedance sensors are described. CoventorWare software was used to model the biological medium loaded interdigital sensor in three dimensions to measure its electrical impedance. Complete system simulation by a finite element method (FEM) was used for sensor sensitivity optimization. The influence of geometrical parameters (number of fingers, width of the electrodes) on the impedance spectroscopy of the biological medium was studied. The simulation results are in agreement with the theoretical equations of optimization. Thus, it is possible to design a priori such sensor by taking into account the biological medium of interest that will load the sensor.
96 citations
Patent•
11 Jun 2001
TL;DR: In this article, the frequency response of the calculated Fourier coefficients displays perfect nulls at evenly spaced frequencies either side of the known frequency f 1/f 1 and the one or more frequencies of potential hum, noise, or other spurious interference.
Abstract: The disclosed invention relates to measuring an ac dynamic parameter (e.g., impedance, admittance, resistance, reactance, conductance, susceptance) of an electrochemical cell/battery or other electrical element under conditions of possible interference from potential sources such as ac magnetic fields and/or ac currents at the powerline frequency and its harmonics. More generally, it relates to evaluating a signal component at a known frequency f1 under conditions of possible hum, noise, or other spurious interference at one or more other known frequencies. A microprocessor or microcontroller commands A/D circuitry to sample a band-limited signal at M evenly spaced times per period 1/f1 distributed over an integer number N of such periods and calculates time-averaged Fourier coefficients from these samples. The frequency response of the calculated Fourier coefficients displays perfect nulls at evenly spaced frequencies either side of frequency f1. By choosing N according to algorithms disclosed herein, null responses are made to coincide with the one or more frequencies of potential hum, noise, or other spurious interference.
96 citations
TL;DR: A simplified treatment of the electrical impedance of biological tissues is presented, examining the sources of impedance changes and the requirements for recording these changes.
Abstract: A simplified treatment of the electrical impedance of biological tissues is presented, examining the sources of impedance changes and the requirements for recording these changes. The author covers small electrodes, simple models, resistivity of blood, the reactive component in bioimpedance, the use of bioadmittance, the use of the finite-element technique and impedance matching. >
96 citations