Optimizing Wrist-Based Bioimpedance: The Role of Electrode Type, Positioning and Signal Frequency in Health Monitoring

Bioimpedance spectroscopy is a non-invasive technique that offers insights into physical parameters such as heart rate, fat-free mass, extra/intra-cellular, and water retention. When integrated with wrist wearables, it holds potential for personalized health monitoring. Electrode type, positioning, and tightness of the wearable heavily influence signal characteristics. This complexity makes it challenging to draw conclusions across various setups, highlighting the need to quantitatively assess recording parameters. Such assessments not only aid in effective modeling but also promote diversification of experimental setups. In this work, the impact of electrode positioning and type on wrist-based bioimpedance measurements was investigated. The effects of input signal frequency and pressure applied on electrodes were also considered, using a custom pediatric blood pressure cuff to simulate wearable tightness. Additionally, acquisition-dependent drift on bioimpedance measurements was explored. A one-way ANOVA analysis for dry electrode positioning revealed significant impedance differences (p<0.05)* at both 100Hz and 1000Hz. In contrast, wet electrode positioning showed highly significant impedance differences (p<0.01)** at 1000Hz.