Direct-Write Laser Patterning of PDMS/Graphite Composites for Dual-Functional Surfaces with Tunable Conductivity and Wettability

Abstract

A novel approach is presented for creating multifunctional polydimethylsiloxane (PDMS) surfaces through the integration of PDMS/graphite composites with blue laser-induced transformations. By systematically varying graphite concentration (0-10 wt.%) and laser power (740 mW - 2 W), precise control over surface properties is achieved, enabling tunable electrical conductivity (1-1000 k Omega sq(-1)) and wettability (contact angles 5 degrees-145 degrees). Compared to traditional infrared or UV laser systems, the blue laser method offers unique advantages through graphite-enhanced selective heating, enabling precise surface modification with improved cost-effectiveness. The resulting laser-induced graphene (LIG) structures demonstrate exceptional stability due to graphite particles serving as anchoring points, successfully withstanding multiple cycles of adhesive tape peeling tests. The practical utility of this single-step fabrication technique is demonstrated through a functional microfluidic chip capable of precise droplet manipulation through electrowetting. This facile, direct-write approach provides a promising platform for applications in flexible electronics, microfluidics, and smart materials.