Rapid fabrication of superhydrophobic and transparent surfaces by using a laser-induced deep etching process

Superhydrophobic surfaces have garnered significant attention for their wide-ranging applications in self-cleaning, anti-icing, and liquid manipulation. However, it remains a daunting challenge to precisely and rapidly fabricate superhydrophobic microstructures with the desired layout. In this study, Polydimethylsiloxane (PDMS) microstructures were replicated from a laser-structured glass mold fabricated by laser-induced deep etching (LIDE). The deep microholes/grooves with the desired layouts and geometrics were rapidly fabricated into the glass mold by picosecond laser modification followed by wet etching. The well-arranged high-aspect-ratio micropillars/wall arrays were achieved on a PDMS surface by a subsequent soft lithography process. The influences of the aspect ratio and spacing of the micropillars on the hydrophobicity and transparency of the PDMS surface were investigated. Both good superhydrophobicity and high transparency can be simultaneously achieved by the use of optimized micropillar geometrics. Transmittance loss due to the presence of the high-aspect-ratio micropillars can be less than 1% over the wavelength region measured (300-1100 nm). Furthermore, to enhance the durability and robustness of the micropillars, protective interconnected microwalls were demonstrated without compromising hydrophobicity and transparency. This research opens up the possibility of rapid manufacturing of superhydrophobic and transparent surfaces with flexible layouts of microstructures.