Capacitive Biopotential Measurement for Electrophysiological Signal Acquisition: A Review

A conventional clinical biopotential measurement system requires the use of wet electrodes that are in contact with skin using conductive gel. Those systems can acquire high-quality signals but may not be feasible for a long-term purpose due to the skin irritation and allergic contact dermatitis. The emerging of human-centered monitoring calls for alternative solutions. Recent technological advances enable capacitive measurement of electrophysiological measurement, which can acquire signals through cloth or even with an air gap; however, difficulties still exist. This paper systemically reviews the recent progress in capacitive measurement from electrode design, analog front end to high-level system architecture, aiming to provide comprehensive and practical instructions for entire system design. The current development serves as the solid fundamental, raising new solutions for future improvement. In addition, the challenges and the strategies are highlighted in order to demonstrate a technical guide. Some perspectives based on our experience are also discussed hoping to inspire new idea and technique in this area.