Rational Design and Fabrication Method for Bioinspired Directional Droplet Sliding Surfaces

A rational design and fabrication method is proposed for fabricating polymeric directional droplet sliding surfaces inspired by butterfly wing microline arrays. The bioinspired structures are fabricated using a simple and well-designed process that combines the conventional micro-electromechanical system process with subsequent soft lithography. Three criteria to avoid fabrication errors during silicon mold production are suggested. The fabricated silicon master serves as a reliable and robust semi-permanent mold for polymeric replication, resulting in bioinspired surfaces with high fidelity. The successfully fabricated bioinspired fabricated structure surface has a re-entrant shape line structure and exhibits directional omniphobic properties while maintaining transparency. The fabricated surface is found to transport droplets in the direction where microlines are formed without wetting by various droplets, including water and oil. The results show that this surface can be applied to various fields. This study has implications for the development of artificial surfaces inspired by nature for various fields, including microfluidics, biotechnology, and energy-harvesting devices.