Fabrication of silver interdigitated electrodes on polyimide films via surface modification and ion-exchange technique and its flexible humidity sensor application

•A new method had been developed to form Ag metallization on PI substrate.•PI acts as both substrate and sensitive layer for humidity sensor.•Formation of IDEs by inkjet-printing method on flexible substrate.

In this paper, the flexible capacitive humidity sensors using the polyimide foils as the substrate together with the moisture sensitive materials had been investigated. A simple and low cost inkjet-printing method had been developed to form silver interdigitated electrodes on PI foils. Two kinds of capacitive humidity sensors with Ag IDEs were constructed. And the humidity sensor characteristics such as sensitivity and hysteresis were analyzed. The results indicated that the metallization of Ag on PI is potential for various future flexible applications.