New Rubber Film Could Harvest Energy From Breathing, Walking to Power Gadgets

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Princeton University engineers have come up with a rubber film that harvests kinetic energy. But it's not just another piezoelectric film. The team has been able to combine silicone and naonoribbons of lead zirconate titanate (PZT). PZT is the most efficient of kinetic-energy harvesting materials, converting as much as 80% of mechanical energy into electrical energy. By being the first team to successfully embed it into silicone, the Princeton engineers have opened up a whole slew of possibilities for where piezoelectric materials can be used - from inside the body to the soles of our shoes. Science Daily reports that the material is made of ceramic nanoribbons embedded in silicone rubber sheets. When flexed, they generate electricity. The material is also very efficient at converting mechanical energy to electrical energy. Currently, the efficiency of this conversion is what holds back kinetic energy from being a viable power source for devices - not enough energy can get harvested, compared to solar, wind and other alternative energy options to make kinetic energy all that appealing on a wide scale. While this material doesn't increase the efficiency - as some other advancements we've seen recently have done - it does increase the potential for where and how kinetic energy can be used when it is the most appropriate choice.

"PZT is 100 times more efficient than quartz, another piezoelectric material," said Michael McAlpine, a professor of mechanical and aerospace engineering, at Princeton, who led the project. "You don't generate that much power from walking or breathing, so you want to harness it as efficiently as possible."

Because the material will be able to be manufactured in sheets on virtually limitless size, the Princeton engineers see potential for the material in powering everything from pacemakers to cell phones by putting the material in clothing, shoes, and other wearable materials. But more exciting for devices like pacemakers is that the material can be implanted in, and accepted by, the body so that the devices they power would not have to be surgically replaced due to batteries losing their charge.

More research is needed, of course, but the success of the team advances the potential usefulness of kinetic energy for easy charging.