Matthew Sparkes writes: "Scientists have found a way to direct liquid using only the force of light. The discovery could one day offer a new way to control the flow of fluids through extremely narrow channels in devices used for in biomedical analysis. A team of US and French scientists used a laser to produce a surprisingly long and steady jet of liquid in two fluids. With one fluid sitting on top of the other, the jet — about 10 microns wide — extended from the fluid above into the one below in the direction of the beam. When the direction of the beam was reversed, it just pushed the liquid below upwards slightly. It is the first time light has been used to affect the flow of a fluid in this way, the researchers believe."