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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.


Papers
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Journal ArticleDOI
TL;DR: In this article, a transfer function based on an assumed physical model is proposed to interpret measured impedance data, and the transfer function can be derived and analyzed, when accepting some approximations.

122 citations

Patent
27 Apr 1992
TL;DR: In this paper, a novel adaptation of digital cross-correlation and convolution techniques is used to simultaneously display real and imaginary electrical impedance of living biological tissue at several selectable sinusoidal frequencies.
Abstract: A method and apparatus for displaying complex impedance and related physical characteristics of an object (30) at a plurality of sinusoidal frequencies over a wide frequency range. Excitation signal waveforms (10, 14, 18) are stored in digital form. Digital sampling and processing circuitry (84, 86) provide high form. Digital sampling and processing circuitry (84, 86) provide high noise immunity and accurate measurement at all impedance phase angles. The technique is particularly well-suited to the measurement of complex impedances in living biological tissue because the digital implementation results in highly accurate measurement values over a plurality of selectable frequencies within a wide sinusoidal frequency region. A novel adaptation of digital cross-correlation (84) and convolution (86) techniques is used to simultaneously display (72) real and imaginary electrical impedance of living biological tissue at several selectable sinusoidal frequencies.

122 citations

Journal ArticleDOI
TL;DR: The results show that the value of the components of electrode impedance varied with time after surgery: access resistance increased slowly over time, whereas polarization impedance increased up to Week 2 but decreased after commencement of electrical stimulation at that stage.
Abstract: Background Impedance measurements are commonly performed at the end of cochlear implant surgery, not only to confirm that all electrodes are working but also to monitor the impedances of the newly implanted electrodes. The current method of testing allows the determination of only the overall electrode impedance but not its components, access resistance and polarization impedance. To determine whether any longitudinal change in the electrode impedance is caused by a change in the endocochlear environment or rather caused by a change in the surface quality of the electrode, it is necessary to extract access resistance and polarization impedance. Methods We applied an impedance model that enabled us to calculate access resistance and polarization impedance after measurement of electrode impedance at three points along the voltage waveform. Results The results show that the value of the components of electrode impedance varied with time after surgery: access resistance increased slowly over time, whereas polarization impedance increased up to Week 2 but decreased after commencement of electrical stimulation at that stage. These results are consistent with the hypothesis that a layer of fibrous tissue forms around the electrode within the cochlear canal, resulting in a slow increase of access resistance, whereas a layer of proteins forms on the surface of the electrode in the early phase after implantation. Electrical stimulation appears to disperse this surface layer, thereby reducing both the polarization impedance and electrode impedance. Conclusion The method presented enables the extraction of more detailed information about the longitudinal changes in the intracochlear environment after cochlear implantation.

122 citations

Journal ArticleDOI
TL;DR: In this paper, the impedance of IT-SOFC cathodes over a very wide performance range was investigated by using impedance measurements on symmetrical cells with three different microstructures in the temperature range 550-850°C.

122 citations

Journal ArticleDOI
TL;DR: A novel technique for measuring electrochemical impedance, in which the electrode potential is ramped to a desired bias potential and a small potential step is applied to the working electrode after a short time delay, which is expected to revolutionize electrochemical measurements.
Abstract: We describe a novel technique for measuring electrochemical impedance, in which the electrode potential is ramped to a desired bias potential and a small potential step is applied to the working electrode after a short time delay. Fourier transform of the first derivative of the current signal thus obtained provides ac currents in the frequency domain, which allows the computation of impedances of the electrode/electrolyte interface in the whole frequency range. A home-built data acquisition system for these measurements and the results obtained therefrom were used for the measurements. The advantage of the technique includes an extremely short time of less than 1 ms for impedance measurements in the whole frequency region while equilibrium conditions of the electrochemical system are being maintained before and after the measurements, among many others. This technique is expected to revolutionize electrochemical measurements and to find important applications such as in situ measurements during battery cycling, corrosion testing, and other electrochemical experiments.

122 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,514
20223,479
20211,009
20201,579
20191,924
20181,809