Fabrication and Characterization of Moisture Slow-releasing Embroidered Electrode and ECG Monitoring Belt

The microenvironmental humidity at the interface between the bioelectrical electrode and the human skin can affect the quality of the bioelectrical signal collected by the electrode. This paper utilized superabsorbent polyacrylic fiber as the base material to fabricate a novel moisture slow-releasing embroidered electrode. The moisture-locking capacity of polyester non-woven fabric (PENWF) substrate, polyacrylic non-woven fabric (PANWF) substrate, polyester-based electrode (PE-E) and polyacrylic-based electrode (PA-E) were compared in this paper. The non-woven fabric with polyacrylic fiber owned excellent moisture-locking capacity, so it could realize the slow-releasing of moisture and provide a suitable wet environment for the dry bioelectric electrode to collect ECG signals. With the extension of time, the amplitude of the ECG signal collected by PA-E did not change much, and only decreased by 17.1 % after evaporating for 10 h; but after evaporating for 10 h, the amplitude of the ECG signal collected by the PE-E decreased by 48.9 %. In addition, 5 mm, 10 mm, and 15 mm thick polyurethane sponge (PUS) filling materials were used to make the ECG monitoring belts, and their signal-to-noise ratios were analyzed under different states of static, swinging arms and walking. The 5 mm thick elastic filler material has the highest signal-to-noise ratio among the three thicknesses. It could collect ECG signals stably under swing arm and walking at a constant speed, and the signal-to-noise ratio (SNR) were 25.393 dB and 30.086 dB respectively. The polyurethane sponge filling materials with a thickness of 5 mm provided an appropriate pre-stress for the ECG signal dynamic measurement, which could provide a reference parameter for the production of smart ECG garment in the future.