An open-source hardware for electrical bioimpedance measurement

This paper describes open-source hardware to measure both the magnitude and phase of the electrical bioimpedance in a frequency range from few kilohertz up to 100 kHz by using a four-electrode technique. The amount of current injected and the sensitivity of the system can be set to the desired range by changing the front-end resistor values. The system can be easily built and adapted with the help of the design details made available at GitHub. The practical performance was evaluated in abdominal impedance measurement, which was the primary motivation to build the system. Other experiments were performed with a 2R-1C circuit, a 10-Ω resistor, and a 100-nF capacitor, with observed relative errors in the impedances of -0.73 ± 0.34 %, -2.47 ± 1.43 % and -8.81 ± 0.64 % (mean ± SD), respectively, from 10 kHz to 100 kHz.