Sensitive and flexible humidity sensor based on sodium hyaluronate/MWCNTs composite film

Abstract

A sensitive humidity responsive sensor based on sodium hyaluronate (SH)/multi-walled carbon nanotubes (MWCNTs) composite film is reported. The sensor is fabricated on a flexible interdigital electrode of a polyethylene terephthalate substrate by a drop coating method. The humidity sensing properties, including repeatability, hysteresis, stability, response-recovery characteristics are investigated, and the film containing 50 wt% MWCNTs exhibits the best performance. Compared with most previous work, this resultant sensor presents a broader detection range for relative humidity (11–98% RH) and faster response/recovery performance (0.32 s/0.27 s). Moreover, the sensor possesses excellent stability after the humidity changes repeatedly, long-term operation, temperature changes and cyclic mechanical bending. The outstanding performance is probably attributable to the synergistic effect of SH and MWCNTs. This sensor developed in this work possesses the potential to be applied in breath monitoring, respiration pattern identification, and touchiness switch by sensing skin sweat evaporation in a non-contact way.