Automated measurement of bioelectric impedance at very low frequencies

✍ Scribed by John J. Almasi; Otto H. Schmitt

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 511 KB
• Volume: 7
• Category: Article
• ISSN: 0010-4809
• DOI: 10.1016/0010-4809(74)90025-1

✦ Synopsis

An on-line real-time system utilizing a simple package of dedicated hardware in conjunction with a small computer for measuring two-terminal electrical impedance is described. Operating efficiently from0.005 to 500 Hz, it covers most of the interesting range for bioelectrode, organ, and tissue studies in electrocardiography, encephalography, myography, and other electrographic researches. The impedance to be measured is driven sinusoidally at a constant current chosen by the operator. By sampling the voltage and the associated current at appropriate paired times during one electrical cycle, coefficients for a discrete Fourier series expansion are obtained in a form which makes calculation of real and imaginary impedance components, DC offset, and harmonic content very simple. Results are displayed on a television-type raster for immediate evaluation and may then be recorded on high-speed tape for subsequent detailed analysis. * We are pleased to acknowledge the support of this work in part by research grants HE005 I3 and HE07575, National