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Ranjini Raghunath for redOrbit.com – Your Universe Online
A tiny, patch-like battery that uses the natural movement of organs such as the heart or lungs to generate electricity inside the human body has been developed by engineers at the University of Illinois at Urbana-Champaign.
A paper describing the device was recently published online in the journal Proceedings of National Academy of Sciences.
The device, about the size of a stamp, is made up of a metal nanoribbon embedded in ultra-thin, flexible plastic material that’s “almost like Saran Wrap,” lead author and University of Illinois material scientist John Rogers told Popular Mechanics. “It can cling to the surface of an organ.”
Many artificial devices – pacemakers for treating irregular heartbeats or nerve stimulators for treating Parkinson’s, for instance – use batteries that run out after a few years. The new invention could one day take over for such batteries and save patients the repetitive, painful and expensive surgeries needed to replace their expired batteries.
The device works on the principle of piezoelectricity, where a metal or metal composite – lead zirconate titanate, in this case – generates electricity under mechanical stress. The device can generate up to 8 volts of electricity as it bends and stretches with the movement of the heart, lungs or diaphragm it is implanted upon.
It can generate more electricity than needed by conventional implants, the authors wrote. Its flexible design also ensures that it harvests power from the organ without hampering or adding strain to the organ’s movements.
The Illinois team, along with doctors at the University of Arizona, surgically implanted the device onto the organs of live sheep, cows and pigs. Their most recent prototypes were able to generate three to five times more electricity than previous trials in living animals.
“In addition to uses on internal organs, the same types of systems can be implemented in skin-mounted configurations for health/wellness monitors or non-biomedical devices,” the authors wrote.
The device could also be used one day to harvest energy from arm or leg muscles, or skin cells, or “pretty much anything that moves,” Rogers said.
Although the device prototypes have been tested for their capacity for only a few hours, Rogers’ team is working on testing and checking their electric output over longer time periods. They are also working on additional tests to make sure it is safe and compatible for long-term use inside the human body.
The challenge would be to make the batteries last longer than the lifetime of current pacemaker batteries, which can last for 5 to 10 years without needing to be replaced.
Rogers’ previous work includes a similar “tattoo” patch to monitor patients’ heart and brain activity, and the world’s first flexible lithium-ion battery.
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