An Ink-Enhanced Strategy for High-Fidelity Microstructure and Surface Functionalization of Transparent PDMS Using a UV Nanosecond Laser

Abstract

Functional micro- and nanostructures are essential for polymer-based devices in biomedicine, sensing, and optics. Yet conventional fabrication methods such as lithography and mold transfer remain expensive, slow, and poorly suited for large-scale production. In this study, we present an ink-enhanced photothermal strategy for the direct fabrication of high-quality polydimethylsiloxane (PDMS) microstructures using a UV nanosecond laser. By precoating the transparent PDMS surface with a thin layer of black ink, laser energy absorption and localized photothermal conversion are significantly improved, effectively overcoming PDMS’s intrinsic transparency. This enhancement allows for precise material ablation at reduced laser power, enabling the creation of well-defined micro/nanostructures and smooth, burr-free microchannels with high structural fidelity. Additionally, the surface wettability of PDMS is readily tunable across a wide range - from intrinsic hydrophilicity (77.8°) to superhydrophilicity (3.26°) or enhanced hydrophobicity (127.4°) simply by adjusting the ink-enhanced laser-induced surface morphology. The versatility of this method is demonstrated through practical applications, including patterned droplet arrays, self-driven liquid transport, and integrated microfluidic channels. This ink-enhanced UV nanosecond laser processing strategy offers a simple, cost-effective approach for the high-precision structuring of transparent polymer materials and devices.