Enhanced wick-based liquid supply in patterned laser-induced graphene on flexible substrates

초록

Advances in MEMS technology have enabled the development of smaller and more efficient electronic devices, integrating nanoscale components. Coupled with progress in flexible semiconductors, the potential applications of flexible electronics have significantly broadened. Yet, wearable and flexible electronics often face challenges related to thermal management owing to the low thermal conductivity of polymers-a crucial issue for wearables in direct contact with the skin. This study introduces an innovative approach to enhance wicking performance on flexible substrates aiming to improve thermal management. The approach involves creating intricate porous patterns on graphene structures through direct laser writing, using a CO2 laser on a polyimide substrate with specific parameters. Eight distinct laser-induced graphene (LIG) samples were produced, each with different laser powers ranging from 9 to 23 W. A surface analysis confirmed the successful transformation of polyimide into porous graphene through laser ablation. The surface properties were evaluated before and after the oxygen plasma treatment, supported by XRD and XPS results. The liquid transport capacity of the LIG samples was accurately measured using the capillary rate-of-rise method. Lower powers (9 and 11 W) exhibited slower rates of wicking velocity, ranging from 5.0 mm/s0.5 to 6.3 mm/s0.5, whereas higher powers demonstrated increased rates, reaching 9.5 to 13.6 mm/s0.5. These findings explicitly demonstrate the superior liquid delivery capability of LIG, achieving wicking velocities up to four times higher than those in relevant existing studies.

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