A Flexible Capacitive Electromyography Biomedical Sensor for Wearable Healthcare Applications

Musculoskeletal diseases and disorders (MSDs) have a significant negative impact on personal health and the worldwide economy. Leveraging the advancement of wearable sensing technology to provide electromyography (EMG) measurement capability can improve the efficiency of the public healthcare strategy to combat MSDs. Integrating conventional EMG contact electrodes into a wearable device is proven to be a challenge because it requires direct electrical contact with the body and has a dependency on the conductive gel. Existing prototypes of capacitive EMG (cEMG) sensors are typically large and designed with a hybrid printed circuit board (PCB). This research article presents a fully flexible cEMG biomedical sensor with integrated front-end analog circuitry in only a medical plaster size. An efficient moving average of the squared data (MASq) technique is presented to effectively suppress the noise floor and improve the signal quality. The experimental results of measuring EMG signals from flexor carpi radialis, extensor carpi radialis, and biceps brachii using the flexible cEMG biomedical sensor are presented. The postprocess data recorded signal-to-noise ratios (SNRs) ranging from 1.8-5.7 while achieving practically 100% sensitivity in measuring muscle contractions. Its miniature, rugged, and flexible characteristics allow it to operate as a standalone adhesive plaster sensor or integrate into wearable applications.