Design of a Low-Power Microcontroller-Based Bioimpedance Spectroscopy Measurement System

This paper introduces a novel, low-power bioimpedance measurement system design for portable medical applications realizing an efficient peripheral use and synchronized data acquisition. The system features dual independent Analog-Digital-Converters (ADCs) for simultaneous voltage and current acquisition. It employs a Digital-to-Analog Converters for the generation of a multisine excitation signal by Direct Memory Access for the generation of signals through optimized lookup tables and the transfer of measurement data from the ADCs for impedance calculation by Fast Fourier Transform. A Tietze topology voltage-controlled current source is implemented realizing a stable current injection ensuring patient safety. Experimental results demonstrate excellent measurement accuracy for a frequency range from 1 kHz to 200 kHz. The multisine approach achieves a maximum magnitude deviation of 1.89% and phase of 1.62° while having an average magnitude deviation of 1.30% and average phase deviations of 0.56° demonstrating a high-precision measurement accuracy comparable to commercial systems while maintaining a power consumption of only 218 mW.