A Low Cost Bioimpedance Measurement System Based on AD5933 Chip

In this paper, we address the critical need for a low and stable impedance at the skin-electrode interface to ensure precise and dependable biosignal acquisition. Regarding this matter an impedance analyzer is a necessary equipment in the laboratory but due to its higher cost, it is not available in the majority of them. Our study introduces a cost-effective impedance measurement system utilizing EVAL-AD5933EBZ, enhanced with an analog front-end circuit design, and employs a four-electrode strategy measurement method. The primary objective is to investigate the behavior of complex skin-electrode impedance and assess its stability over time for dry and commercial gel electrodes in order to evaluate the developed design. Our experimental tests were conducted within the frequency range of 5 kHz to 50 kHz. The results validate the accurate performance of our measurement system and demonstrate that the studied dry electrodes exhibited a similar behavior to the commercial electrode. These findings provide valuable insights into the impedance characteristics of the skin-electrode interface.