Sustainable cork-based laser-induced graphene sensors for humidity monitoring in cultural heritage preservation

Sustainable sensing platforms are essential for environmental monitoring and the preservation of cultural heritage. Here, we report a chemiresistive relative humidity (RH) sensor fabricated via direct laser writing on biodegradable and renewable cork substrates. The sensor integrates laser-induced graphene (LIG) electrodes, a PEDOT:PSS stabilizing layer, and a hybrid of green- and chemically synthesized graphene oxide (GO) as the active sensing layer, optimizing performance while minimizing environmental impact. The device exhibits a sensitivity of 0.366 KΩ/%RH across 0–100% RH, with hysteresis below 0.5% RH, and demonstrates long-term stability with a drift of <1% RH over 75 days. Deployment in museum environments using a custom-built data logger confirmed reliable RH monitoring comparable to commercial sensors. Life cycle assessment shows that green electrolytic GO synthesis reduces climate change impact by up to 4.5-fold, while the cork substrate lowers the carbon footprint approximately eight-fold relative to polyimide-based sensors. This work presents a sustainable, high-performance RH sensing platform for real-world cultural heritage preservation applications.