Polymer's flips wring electricity from wet surface

摘要

IT'S quite a mover- but only when damp. A polymer that flips over if it absorbs water has been used to wring electricity from a wet surface. The film could one day allow small devices to run on nothing but sweat, and provide power in remote areas where conventional sources are scarce. When a dry polymer absorbs water, its molecular structure changes. In principle, this can be converted into larger-scale motion and thus supply energy.