A wearable button-like system for long-term multiple biopotential monitoring using non-contact electrodes

High medical expenditure on chronic diseases in recent years promotes proactive healthcare and health management. Wearable devices provide a good solution for long-term monitoring for both in-hospital and out-of-hospital healthcare; however, long-term contact may cause comfort issues. This paper introduces the design, manufacturing, and experimental validation of a button-like wearable system for long-term multiple biopotential monitoring using non-contact electrodes, namely NCMB-Button. The button-like system is capable of acquiring ECG signals through multiple layers of cloth without directly contacting human skin and other multiple biopotential signals, including EMG and EEG without using traditional wet gel. The detecting performance is achieved and enhanced by introducing a feedback loop into the skin to reduce motion artifacts. The system is packaged into a 39 mm × 32 mm × 17 mm 3D printed case, featuring low-weight and low-cost. The total weight of the system is 24.0 g. The detection performance is validated by testing in multiple motion scenarios through different types of cloth. The results show that ECG signals were able to be detected through the thickness of 2.60 mm of fabric cloth with fast recovery from motion artifacts. Two types of EMG signals were also detected during the validation experiments. The EEG signals were detected during sleepiness condition in which the alpha wave was visible as the indicator. The NCMB-Button demonstrates the feasibility of long-term biopotential monitoring for various applications without interrupting daily activities.