Design and characterization of a multi-frequency bioimpedance measurement prototype

• Published in: Journal of physics. Conference series Vol. 407; no. 1; pp. 12011 - 11
• Main Authors: Neto, O E Mattia, Porto, R W, Aya, J C C
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2012
• Subjects: Channels; Circuits; Current sources; Demodulation; Digitization; Electric potential; Electrical properties; Errors; Frequency response; Linearity; Physics; Prototypes; Quadratures; Signal processing; Voltage
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/407/1/012011

A multi-frequency bioimpedance measurement prototype is proposed, validated and characterized. It consists of an Improved Howland Current Source controlled by voltage, a load voltage sensing scheme through a discrete 3-opamp instrumentation amplifier, a phase and quadrature demodulation setup through analog multipliers, and digitization and processing of the signals using a digital benchtop multimeter. The electrical characterization of the measurement channel was done for resistive loads only, on four different circuits. Measurements were made on 10 frequencies, from 100 kHz to 1 MHz, with 10 load resistances, from 100 Ω to 1 kΩ, to obtain linearity, absolute error and frequency response. The best performance among the four circuits was a maximum absolute error of 5.55 %, and −1.93 % of load current variation at the worst case scenario.