Fig. 1. SEM images of the pulsed-laser irradiated PDMS surface under different magnifications.

Fig. 2. (a) Side view of water droplet on the nonirradiated PDMS surface; (b) side view of water droplet on the irradiated PDMS surface at optimized conditions.

Fig. 3. (a) CA of PDMS surface as a function of period; (b) water droplet on a rough surface (Wenzel model); (c) water droplet on a rough surface (Cassie model).

Fig. 4. Raman shift of the PDMS at different laser powers.

Fig. 5. (a) CA of the PDMS surface as a function of the laser power measured from two orthogonal directions; image of a water droplet on an irradiated surface viewed (b) from the direction perpendicular to the microgroove and (c) from the direction parallel to the microgroove.

Fig. 6. Evolution of the CA of the surface (after irradiated by femtosecond laser) measured from the direction perpendicular to the microgrooves.

Fig. 7. Evolution of the CA of the surface (after irradiated by femtosecond laser) measured from the direction parallel to the microgrooves.

Fig. 8. Evolution of the CA of the irradiated surface measured from directions perpendicular and parallel to the microgrooves.