NCMB-Button: A wearable non-contact system for long-term multiple biopotential monitoring

This paper presents a button-like wearable wireless non-contact system (NCMB-Button) for long-term multiple biopotential monitoring. Featured non-contact detection based on ultra-high input impedance of the analog front end, the NCMB-Button is capable of acquiring multiple biopotential signals including ECG, EMG, and EEG, through multiple layers of cloth without directly contacting human skin. The detecting performance is also enhanced by introducing the feedback into the skin. The system is powered by a 150 mAh rechargeable Li-ion battery and packaged into a 39 mm × 32 mm × 17 mm 3D printed small box. A power management circuit is also designed to provide dual power supply for op amps. The total weight of the system is 24.0 g. The detection performance is validated through multiple motion scenarios with different types of cloth. The results show that the ECG and EMG signals are able to be detected through up to 19 layers of cloth (Polyester) with fast recovery from motion artifacts. The EEG signals are also detected during which the alpha wave in drowsy condition is visible. The NCMB-Button demonstrates the feasibility of long-term biopotential monitoring for daily application without affecting daily activities