of harvesting power from a broader range of natural human activities such as walking and exercising. Based on electrochemical principles — the slight bending of a sandwich of metal and polymer sheets, with materials similar to those in lithium ion batteries — the new technology can more effectively capture energy from human motions than previous devices. Those devices, which were based on frictional technology or the compression of crystalline materials, can capture energy from mechanical vibrations, but they are not as compatible with the pace of human movements, the researchers explain in the journal Nature Communications. When bent even a very small amount, the new layered composite produces a pressure difference that squeezes lithium ions through a polymer. The process produces alternating electrical current, the researchers say, which can be used directly to power devices such as cell phones and audio players.
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