Vesicles as Osmotic Motors

Abstract

We report on a quantitative study of the motion of model osmotic motors---lipid vesicles in a solute concentration gradient. The vesicles move through recoil produced by osmotic pumping, but the transformation of entropic osmotic energy into mechanical motion is found to be unexpectedly efficient: The drift velocity is more than 3 orders of magnitude faster than predicted by linearized nonequilibrium thermodynamics.