The plastic sheets have slivers of bendable filaments that stand up and are moved by gusts of air. The filaments, which are encased in plastic, work using the piezoelectric effect – the ability of some materials to generate a charge in response to pressure. In this case, when the filaments are moved by gusts of wind, tiny pieces of energy are created. For her prototype, Slingsby used a flexible film of polyvinylidene fluoride. “They have the ability to transform strain or bending energy into electrical energy,” Slingsby said.