The hexagonal network-type PDMS microstructures were fabricated and they were employed to low-friction drag surfaces. While the lowest contact angle measured from the smooth surface was 108°, the highest contact angle measured from the microstructured surfaces was 145°. The moving speed of bullet-type capsule attached with a PDMS pad of smooth surface (CA=108°) was 0.1261 ㎧ and that with a PDMS pad of microstructured surface (CA=145°) was 0.1464 ㎧. Compared with the smooth surface, the microstructured surface showed 16.1% higher moving speed. The network-type microstructures have a composite surface that is composed with air and PDMS solid. Therefore, the surface does not wet: rather water is lifted by the microstructures. Because of the composite surface, water shows slip-flow on the microstructures, and thus friction drag can be reduced.
