Using Conductive Fabric for Multi-Channel Capacitive ECG Measurement

One of the attractive long-term health monitoring methods is Capacitive electrocardiogram (cECG) measurement. However, there is little literature available on carrying out the multi-channel cECG system in standard limb leads and the circuit diagram. This paper presents a multi-channel limb-lead cECG system that utilized conductive fabrics as the capacitive sensor, including the capacitive driven-body (CDB) circuit used to reduce the common-mode power-line interference (PLI), and verify the stability of the system through theoretic analysis and long-term experiments. The design criteria of this system and the corresponding circuit diagram are described. The signals obtained by the system presented are competitive with those by commercially available ECG machines. The sensor manufactured by conductive fabrics and the feasible size and the distance of the subjects were tested and evaluated. According to the test results, the sensor area for cECG measurement is suggested to be greater than 60 cm2, and the distance should not exceed 3 mm.