Two-frequency impedance plethysmograph: real and imaginary parts
- 1 January 1990
- journal article
- research article
- Published by Springer Nature in Medical & Biological Engineering & Computing
- Vol. 28 (1) , 38-42
- https://doi.org/10.1007/bf02441675
Abstract
A four-channel impedance plethysmograph has been designed. Impedance signals are obtained at two frequencies by measuring both real and imaginary parts. Particular attention has been paid to the sine wave generation circuits that provide system versatility. The required phase-sensitive demodulation is achieved by means of analogue multiplexers. Results show that there are significant variations in the thoracic equivalent capacitance related to respiration and that there is an increased sensitivity to cardiac activity at low frequencies.This publication has 12 references indexed in Scilit:
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