Flexible Waterborne Polyurethane-Bacterial Cellulose Films for Real-Time Physiological Monitoring

Abstract

The incorporation of waterborne polyurethane (WPU) into bacterial cellulose (BC) fibers significantly improved the tensile strength of the resulting WPU/BC composite film, achieving an enhancement of 19.4 times. The formation of hydrogen bonds between WPU and BC effectively eliminates cavities within the BC matrix, achieving significant plasticization and toughening. Compared with the pure BC film (WPU/BC-0), the elastic modulus of the WPU/BC-5 composite film is reduced by 97.5%, and surface hardness is decreased by 96.9%. When integrated with a flexible EGaIn electrode, the wearable composite film demonstrated exceptional potential in flexible electronics, reliably enabling point-of-care detection of human electrocardiograph (ECG) signals. This WPU-regulated BC approach provides a promising alternative for fabricating flexible and durable substrates suitable for wearable device applications.