Self-adhesive protein/polypyrrole hybrid film for flexible electronic sensors in physiological signal monitoring

Flexible electronic sensors composed of conductive material and flexible film have attracted increasing attention in decades due to its commercial, medical and scientific value. However, the poor interfacial bonding robustness between conductive materials and flexible film influences widely practical application of sensors. It is still a great challenge to fabricate a self-adhesive conductive film. Herein, we report a freestanding and self-adhesive bovine serum albumin/polypyrrole (BSA/PPy) hybrid film at the air/water interface. It is discovered that the PPy nanoparticles aggregate uniformly on the BSA film that is formed by amyloid-like BSA aggregation. The BSA/PPy film was integrated with polydimethylsiloxane (PDMS) film to fabricate flexible electronic sensors. The test indicates that the BSA/PPy film-based sensor could tolerate 500 cycles of bending without the resistance performance variation. The BSA/PPy film functions as a key mediator to dynamically tune the PPy conductance in response to external pressures and strains. The sensors exhibit ability for detecting tiny acoustic vibration, real-time human motion, physiological behavior and for differentiating various breathing pattern. Our strategy may open a pathway to readily construct flexible electronic sensors toward practical applications.