Roll-to-roll graphene films for non-disposable electrocardiogram electrodes

Abstract

Graphene has good electrical properties, flexibility, and biocompatibility, making it an ideal material to monitor electrocardiogram (ECG) signals. However, the production cost and the feasibility of large-scale production limit the application of graphene electrodes. Here, we demonstrate a roll-to-roll (R2R) method to transfer graphene grown by open-R2R chemical vapor deposition onto an ethylene vinyl acetate/polyethylene terephthalate (EVA/PET) substrate to make non-disposable ECG electrodes. This method can produce a continuous graphene/EVA/PET film with 15 cm width, and the length can reach several meters. The graphene/EVA/PET film has excellent flexibility and transparency (75.08% transmittance at 780 nm). Compared with commercial silver/silver chloride (Ag/AgCl) electrodes, R2R graphene electrodes have lower electrode–skin impedance below 1 kHz and can obtain ECG signals with similar performance to Ag/AgCl electrodes. Besides, R2R graphene electrodes have good washability. After ten times cleaning, the resistance of the R2R graphene electrode only increased by 23.2%, which was lower than that of the previous graphene electrodes. This work has great potential in the long-term and real-time healthcare monitoring system.