A Wireless Biopotential Sensing Node with Simultaneous Body-Channel Communication by TX-Coupled 21 V_pp Common-Mode Interference Suppression

Continuous sensing and wireless data transmission are essential for the real-time low-noise acquisition of physiological data for remote healthcare. For energy-efficient communication among wearables different wireless modalities have been proposed such as RF [1] [2] and body-coupled (BCC) [3]–[13] with the latter exhibiting advantageous path loss and confinement to the body surface [14]–[16]. However the coupling of electric field onto the body (body-coupled communication) and the continuous biopotential sensing could interfere mutually in two ways. First the BCC data TX output signal introduces a higher-frequency common-mode interference (CMI) at the biopotential sensing front-end. Second the BCC data TX output signal leaks through the 50Hz CMI cancellation circuit that is imperative in wearable ExG sensing to avoid saturation due to large power-line interferences in practical settings. Techniques have been proposed to tackle the first issue (i.e higher-frequency CMI) including higher input dynamic range and intrinsic CMRR at high frequency [3]. However the leaking of BCC data TX signal through the 50Hz CMI cancellation path could cause the body-coupled transmission to fail [17] for which an effective solution is still lacking