A light push

USING only a beam of light, researchers in Japan have managed to move liquid
around. They say the technique could help manoeuvre minute quantities of fluids
around “labs on chips”. Kunihiro Ichimura and his colleagues at the Tokyo
Institute of Technology in Yokohama placed droplets of olive oil on a special
photosensitive surface. Light alters the surface’s chemical configuration, which
in turn affects the surface tension of any fluid on it. So focusing light on one
side of a droplet makes it flow away from the beam (Science, vol 288, p
1624).