Photo-regulated stick-slip switch of water droplet mobility

Water droplet mobility can be reversibly manipulated by using a photo-responsive coating on a rough surface. The surface coating consists of silicone elastomer as the basic hydrophobic material and the incorporated azobenzene compound as photosensitizer that assumes trans/cis conformation change under visible and UV illumination. The surface thus could switch between slippery and sticky states when the azo-compound assumes trans- and cis- conformation, while the surface superhydrophobicity doesn't change apparently.