Flexible humidity sensor based on TiO_2 nanoparticles-polypyrrole-poly- [3-(methacrylamino)propyl] trimethyl ammonium chloride composite materials

摘要

A novel flexible resistive-type humidity sensor was fabricated by the in situ photopolymerization of TiO_2 nanoparticles/polypyrrole (TiO_2 NPs/PPy) and TiO_2 nanoparticles/polypyrrole/poly-[3-(methacrylamino)propyl] trimethyl ammonium chloride (TiO_2 NPs/PPy/PMAPTAC) composite thin films on a polyester (PET) substrate. The effect of the TiO_2 NPs concentration on the electrical and humidity sensing properties of the TiO_2 NPs/PPy composite thin films on a PET substrate was investigated. PMAPTAC was incorporated into the TiO_2 NPs/PPy composite thin films to increase the flexibility and sensitivity of the composite films for practical use. Characterizations of the thin films were performed by Fourier transform infrared spectroscopy (FTTR). The flexible humidity sensors based on the TiO_2 NPs/PPy/PMAPTAC composite thin films had the best flexibility, highest sensitivity, least hysteresis and greatest linearity. Other sensing properties such as the effects of applied frequency and ambient temperature, response and recovery times, and long-term stability were also studied.