Self-powered flexible humidity sensor based on moisture-induced electric generation

Wong, Ke Xin (2025) Self-powered flexible humidity sensor based on moisture-induced electric generation. Final Year Project, UTAR.

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Abstract

Conventional humidity sensors often suffer from limited flexibility and reliance on external power sources, hindering their integration into low-cost, sustainable, and portable systems. This study presents the development of a flexible self-powered humidity sensor based on moisture-induced electricity generation (MEG), utilizing laser-induced graphene (LIG) fabricated on lignin-coated paper. A commercially available 5 V violet laser engraver (405 nm) was employed to induce graphitization through a simple, single-step scribing process. Fabrication was optimized by varying the paper’s tilt angle (0° to 20°) to enhance voltage output and stability. Surface morphology and elemental composition were analyzed using SEM, EDX, and XRD. Under 80% relative humidity, the sample fabricated at 20° tilt angle generated the highest average voltage (~6.5 mV) but showed unstable performance. In contrast, the sample prepared at 15° produced a slightly lower voltage (~4.2 mV) with significantly greater stability, identifying it as the optimal configuration. These findings demonstrate the potential of LIG-based MEG as a cost-effective, battery-free humidity sensing solution and offer insights into scalable fabrication strategies for flexible electronics. Keywords: humidity sensor; self-powered sensor; laser-induced graphene; moisture-induced electricity generation; flexible electronics Subject Area: TA165 Engineering instruments, meters, etc. Industrial instrumentation

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