Parametrically Engineered Laser-Induced Graphene with Tunable Electrical and Morphological Properties for Flexible...

Laser-induced graphene (LIG) provides a scalable and maskless route for fabricating three-dimensional porous graphene on polymer substrates for flexible electronics. However, achieving reproducible control over its electrical and structural properties remains challenging due to the complex interplay of laser processing parameters. Here, we systematically investigate the effects of laser power, scan speed, dots per inch (DPI), energy per unit area (EPUA), and depth of focus (DOF) on the morphology, crystallinity, and conductivity of LIG formed on polyimide substrates. The optimized LIG exhibits excellent structural quality (I _D/I _G ∼ 0.25, L_a ∼ 76 nm) and low sheet resistance (∼10 Ω/□), within the lower range of reported values. The material is further validated through flexible piezoresistive sensors and electrothermal heaters. The pressure sensor demonstrates two distinct sensitivity regimes (1.25% N^1- and 32% N^1-), a low limit of detection (∼150 mN), and minimal hysteresis (∼5-6%). Piezoresistive behavior is governed by deformation-induced modulation of conductive pathways involving interflake contact resistance, tunneling effects, and microstructural rearrangement within the porous LIG network. The LIG-based microheater achieves a temperature of 201 °C within 6.2 s at a low operating voltage of 6.5 V, outperforming many reported flexible heaters in terms of heating efficiency. These results establish a transferable framework for engineering high-quality LIG with tunable properties and demonstrate its potential for scalable, low-power multifunctional flexible electronic applications.