Humidity sensor based on the ionic polymer metal composite

In this paper, a novel method for fabrication of an ionic polymer-metal composite (IPMC)-based humidity sensor is developed and optimized. IPMC is a kind of smart material that can work as a sensor or an actuator in wet environments or liquids. Poor adhesion between electrodes and the polymer and peeling off phenomenon are common problems in IPMC fabrication. Mechanical roughening, plasma treatment of the polymer surface and sputtering a thin layer of Ti and Cr as adhesion layers between polymer and Au electrodes are proposed to solve these issues. Different fabricated IPMC electrodes were then used as a capacitor to measure the relative humidity variations at different deflections and relative humidity conditions and the results have been compared. Our results show that IPMC using Au with 990 nm thicknesses worked properly and a sensitivity value of 13.43% was achieved.