Rapid controlled transport of water droplets by sunlight-powered pump
(PHYSorg.com Chemistry)

Driven by natural or artificial sunlight, a novel `microtube pump` transports water droplets over long distances. As reported by Chinese researchers in the Journal Angewandte Chemie, the pump consists of a tube whose properties can be changed asymmetrically through irradiation. This results in capillary forces and a wettability gradient in the inner wall which work together to accelerate the water droplets to exceptional high speeds.