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Technology Review is reporting that new Flexible Sheets Capture Energy from Movement – Material could charge portable electronics with every step.

Researchers at Princeton University have created a flexible material that harvests record amounts of energy when stressed. The researchers say the material could be incorporated into the soles of shoes to power portable electronics, or even placed on a heart patient’s lungs to recharge a pacemaker as he breathes.

Flex your power: A Princeton researcher holds a square of silicone embedded with a ribbon of a crystalline material that generates an electrical current when flexed. Credit: Frank Wojciechowski

The energy-harvesting rubber sandwiches ribbons of a piezoelectric material called PZT between pieces of silicone. When mechanically stressed, a piezoelectric material generates a voltage that can be used to produce electrical current; a current can also be converted back into mechanical movement.

The rubber material can harness 80 percent of the energy applied when it is flexed–four times more than existing flexible piezoelectric materials.

Flexibility could prove vital if energy-harvesting technology is to take off. For example, the military tested stiff-soled piezoelectric shoes as a power source, but soldiers complained of foot pain. And previous flexible energy harvesters–based on piezoelectric polymers, nanowires, or other types of crystal–put out little electrical current.

PZT is the most efficient piezoelectric material known, but its crystalline structure means that it must be grown at high temperatures, which normally melt a flexible substrate. The Princeton researchers, led by mechanical engineering professor Michael McAlpine, got around this by making PZT at high temperatures and then transferring thin ribbons of the material onto silicone.

The possibilities of charging your electronic devises or as used in medical patients with this material is truly astounding.