Mobile renewable energy has received innovations with limited usefulness. Solar or other methods have so far given us little to power our mobile phones, laptops, music players, etc. But our own bodies may provide the means to energize this category of devices. A type of rubber film can now be used to store the negligible power generated from walking, breathing, or other previously non-optimized activities. Engineers from Princeton have improved upon previous piezoelectric films with a combination of silicone and lead zirconate titanate (PZT) nanoribbons. Paraphrasing the Britannica Concise Encyclopedia, piezoelectric materials generate electricity in response to applied mechanical pressure. PZT is the most efficient of kinetic-energy harvesting materials, "converting as much as 80% of mechanical energy into electrical energy," according to TreeHugger.

The Princeton engineers have broadened the energy-collecting applications immensely by successfully embedding it into silicone. Not only can it be used in all manner of products and materials, it can even be used inside the body.

The medical uses immediately available include pacemakers. The material could be implanted near the lungs, and energy from the movement of breathing could reduce or eliminate the current need to perform surgery just to replace the heart-regulating device's battery.

In the external world, shoes and other garments could collect power for an ever increasing number of personal mobile devices.

Harvesting enough power to actually keep a device running has been a major stalemate for kinetic-energy collection. The PZT/silicone development could create more interest in this research category.

PZT is one hundred times more efficient than quartz, another piezolectric material, said Michael McAlpine, professor of mechanical and aerospace engineering in Science Daily earlier this week. "You don't generate that much power from walking or breathing, so you want to harness it as efficiently as possible. McAlpine led the project at Princeton.