Performance analysis of novel flexible electrodes for wearable ECG/heart rate monitoring

The development of manufacturing methods has made it possible to add metal materials as flexible electrodes into wearables. This paper presents effective methods of manufacturing custom electrodes that give reliable ECG/HR signal and maintain textile comfort. Screen-printing, micro etching and electro plating have been used to make dry electrodes that are integrated into common types of heart rate straps. Each manufacturing method of dry electrodes is related to single electrode material. The effects of different materials on signal quality are investigated. Tested materials were platinum, silver ink and stainless steel. These heart rate straps were used during rest condition, cycling, walking and running. Ten users were included (7 male and 3 female) and were measured during physical activity. Electrode performance was measured and signals were compared simultaneously with silver/silver chloride gel electrodes. In this study, platinum has the smallest signal error; therefore, it is the most appropriate of the tested materials. Followed by Ag ink, disposable Ag/AgCl and lastly stainless steel. The results obtained during exercise indicate that, all of the tested materials worked reliably with these activities and there is no statistical difference between them. The HR error % in all materials was below 20%, which was considered the limit for reliability. It can be concluded that their signal measurement reliability is adequate for sportswear and health care applications. These electrodes did not rub or the edges scratched the skin. The additional result is that they are reasonably comfortable to wear during exercising.