A non-contact biopotential sensing system with motion artifact suppression

This paper describes a wearable sensing system to monitor biopotentials via noncontact capacitive sensors that are suitable for long-term and ambulatory monitoring applications. To overcome motion-induced measurement artifacts typically encountered in such systems, a motion artifact suppression technique is introduced. Specifically, a sensor that consists of a pair of physically-interleaved capacitive channels is designed to have different amounts of parasitic input capacitance, creating channel-specific outputs that depend on the input coupling capacitance itself. Differences in output channel results can then be placed through a digital reconstruction filter to re-create the original biopotential with attenuated motion artifacts. To validate the system concept, a wireless ECG sensing system is designed. Simulation results indicate that motion-induced signal distortion is reduced by over 14X after reconstruction.