Polymer Nanosheet Interfaced Bioelectrode for Skin‐Inert sEMG Measurement

Abstract The interface between skin and electrodes plays a major role in the accuracy and efficiency of biopotential measurements. For reliable biosignal recording, stable and low‐impedance contact is required between electrodes and the target tissue. Conventional wet electrodes (Ag/AgCl) are composed of metal electrodes with skin‐adhesive hydrogel. However, for long‐term measurement, direct contact between the pre‐gel electrode and skin causes discomfort and skin irritation, especially for infants and people with sensitive skin because of the adhesiveness of the hydrogel. In this study, a low‐adhesive electrode is reported by exploiting a free‐standing polymeric ultra‐thin film (referred to as a “nanosheet”) as an intermediate layer at the backside of the electrode, which reduces the adhesiveness of the pre‐gel electrode while allowing for surface electromyogram (sEMG) measurement. Intermediate layer of the nanosheet made from polystyrene–polybutadiene–polystyrene triblock copolymer (SBS), polystyrene (PS) or polydimethylsiloxane (PDMS) is prepared using the roll‐to‐roll gravure coating method. The thickness of each nanosheet is varied from hundreds to thousands of nanometers, and the effect on the electrode performance is evaluated. The nanosheet‐modified electrodes with low adhesiveness are applied to human skin, which shows a good performance to detect sEMG signals of the forearm in a skin‐friendly manner.