Abstract
Abstract The presented multichannel measuring system working on various frequencies is suitable either for electrical impedance spectroscopy or tomography. The authors of this paper have developed ...
Highlights
Today measuring methods, as Electrical Impedance Spectroscopy (EIS) [1] and Electrical Impedance Tomography (EIT) [2], [3] are frequently applied in various science disciplines: medicine, diagnostics and material investigations as well
The presented multichannel measuring system working on various frequencies is suitable either for electrical impedance spectroscopy or tomography
In [7] a high performance digital lock-in amplifier implemented in a low-cost Digital Signal Processor (DSP) board is described, where the lock-in amplifier is capable of carrying out measurements applying different excitation frequencies
Summary
As Electrical Impedance Spectroscopy (EIS) [1] and Electrical Impedance Tomography (EIT) [2], [3] are frequently applied in various science disciplines: medicine, diagnostics and material investigations as well. For most instruments of this field the use of lock-in amplifier is indispensable in the measurement method. There are several approaches for developing lock-in amplifiers using different technological concepts and methodologies. Paper [4] describes a digital implementation of a lock- in amplifier, based on the classic quadrature technique and on a mathematical algorithm for error signal extraction. The tech market offers many instruments, which are developed with different functionalities applying the lock-in amplifier technique for the measurement. In case of high precision measurements many methods are used: Fourier analysis [10], information-filtering demodulation [11], impedance measurement system based on digital auto-balancing bridge [12], four-point single sinusoidal signals instantaneous frequency estimation method [13], or the lock-in amplifier method [14], [15]. Keysight Technologies is one of the leader companies that offers high-precision impedance measuring and analyzing instruments [18]
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