Water‐Stable Paper‐Based Laser‐Induced Graphene With Asymmetric Water Adhesion and Wettability

ABSTRACT Here, we demonstrate a Parafilm penetration coupled with directional laser scribing, simultaneously regulating surface wettability and underwater stability of paper‐based laser‐induced graphene (PLIG). Parafilm penetration generates an asymmetric Parafilm–paper (PP) precursor comprising a Parafilm‐rich front surface (PP‐F) and a cellulose‐rich back surface (PP‐B). Subsequent laser scribing to either side yields PP‐derived LIG (PP‐LIG) with porous graphitic structures and good electrical conductivity (∼100 Ω/sq). This process produces distinct interfacial properties: a hydrophobic and water‐adhesive PP‐F‐LIG and a superhydrophobic, non‐adhesive PP‐B‐LIG. The resulting surface wettability and adhesion enable surface‐dependent electrochemical kinetics, suppress humidity‐induced resistance variations to below 0.6% at 90% relative humidity, maintain stable performance under prolonged water immersion without delamination, and exhibit consistent electrical and wetting properties across samples, indicating good reproducibility. Leveraging these tailored surface properties, PP‐LIG enables liquid sensing of various organic solvents, encapsulation‐free underwater pressure sensing with a sensitivity of 2.38 kPa ⁻¹ , and self‑propelled catalytic motors operating at the liquid/air interface. This work demonstrates that stabilizing PLIG against moisture and water exposure enables reliable operation in wet environments, while the resulting asymmetric wettability and adhesion expand the scope of paper‐based devices to liquid, underwater, and dynamically changing interfaces, establishing a scalable and sustainable platform for environment‐resilient papertronics.