Preparation of flexible resistive micro-humidity sensors using quaternary ammonium salt-modified graphene oxide and their humidity-sensing properties

A novel resistive-type micro-humidity sensor was constructed from an interdigitated micro-electrode on a flexible polyimide substrate of size 2.0×3.0 mm 2 . The humidity-sensing film was composed of a graphene oxide modified with glycidyltrimethylammonium chloride (GO-GTMAC). We investigate the effect of water adsorption on the electrical properties of GO-GTMAC films using the direct current (DC) measurement and alternating current (AC) complex impedance spectroscopy. The micro-humidity sensor was found to have a sensing range of 0.0268 logΩ/%RH, a linearity of R 2 =0.987, a hysteresis of −1.3±0.2%RH, a response time of 70 s, and a temperature coefficient of 0.50±0.05%RH/°C.