Polyimide-derived laser-induced porous graphene-incorporated microwave resonator for high-performance humidity sensing

Abstract

Bulk absorption based microwave humidity sensing characteristics of a laser induced graphene (LIG) is investigated for the first time. An LIG flake with a three dimensional network of high porosity patterned on a polyimide substrate using CO2 microlaser is integrated into the capacitive sensing region of a microwave resonator. The performance evaluation reveals that the developed microwave LIG sensor linearly detects the wide range of relative humidity with a high sensitivity, short response and recovery time (< 6 s), and small hysteresis (up to 0.375% RH); thus validating the high performance intrinsic humidity sensing characteristics of LIG at microwave regime.