Tiny gears increase light-to-work conversion efficiency by five orders of magnitude

Scientists have demonstrated that pinwheel-shaped microgears floating on a liquid surface can rotate at speeds of up to 300 r.p.m. when illuminated by an ordinary LED. This light-driven motion, which arises because the light creates a tiny temperature difference and, subsequently, a surface tension difference in the surrounding fluid, is about five orders of magnitude more efficient than other mechanisms that convert light into work. As the effect is not size-dependent, the scientists expect that the system could be scaled to both the macroscale and the nanoscale.