Flexible and highly sensitive graphene/carboxymethyl cellulose films for bending sensing

High sensitivity is the major desired requirements of strain sensors for wearable electronics applications, especially in health and medical monitoring. A bending sensor attach tightly to skin remains a hot topic considering wide response range and high sensitivity. Herein, a highly sensitive strain sensor based on graphene/carboxymethyl cellulose (GE/CMC) composite film is fabricated through vacuum filtration and chemical reduction. CE/CMC films present an ordered multi-layer structure, which is helpful for signal sensitivity. Owing to the super flexibility of carboxymethyl and the excellent electrical and mechanical properties of GE, the free-standing GE/CMC film reveals high conductivity at 1321.9 S m⁻¹, good response performance at low voltage driving of 1 mV. The bending signal of GE/CMC film was stable, when applying 0–90° forward bending strain. Its sensitivity reaches at 0.83 rad⁻¹, and response time of 90° forward bending strain is less than 190 ms, with a regularly stable bending signal response in 100 cycles bending testing. With such outstanding performances, the GE/CMC film can be expected to be applied in motion signal detection.