Combined laser-induced graphene and microcontact printing for processing scalable and stackable micro-stripe patterns toward multifunctional electronic devices

Laser-induced graphene (LIG) is a highly promising technology for assembling thin-film electronics with miniaturized surficial patterns, although hard to guarantee both high-quality formation of raw materials and high resolution of feature size. In this study, a combined microcontact printing (μCP) and LIG protocol is creatively utilized to fabricate ultra-thin graphene films with highly ordered micro-stripe arrays. In addition to realize various patterned structures with unique scalable and stackable characteristics, PAA concentration (4–8 wt%) is systematically investigated as a critical parameter to precisely control the feature size of micro-patterns before and after the irradiation process, including line width (before: 5.37–22.44 μm, after: 4.83–22.32 μm) and average height (before: 69.81–187.39 nm, after: 5.72–48.61 nm). By further exploring a defocused multi-lasing strategy, sheet resistance of the graphene array could be optimized dramatically from 634.1 kΩ/sq to 1.9 kΩ/sq, while maintaining low ablation (45.38 % porosity) and high carbon content (84.2 wt%). Lastly, the process is demonstrated to assemble different graphene based electronic devices with miniaturized sizes, including liquid sensors with sensitivity of 2.7 % μL⁻¹ and electrothermal heaters with temperature-ramping rate as high as 24.7 °C/s and working temperature as high as 248 °C.