Battery-free implantable medical device draws energy directly from human body

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UCLA and University of Connecticut scientists design supercapacitor that could make pacemakers and other instruments safer and more durable

The supercapacitor invented by researchers from UCLA and the University of Connecticut could lead to pacemakers and other implantable medical devices that last a lifetime. Image Courtesy : UCLA

Human body is a vast reservoir of charged particles, called ions. So, why is it that none of the medical devices can harness electrical energy from this flow of ions in the human body for their functioning? Seems like researchers from UCLA and the University of Connecticut were successful in designing a system which does exactly that!

These scientists designed a new biofriendly energy storage system called a biological supercapacitor, which operates using or ions from fluids in the human body. The device is harmless to the body’s biological systems, and it could lead to longer-lasting cardiac pacemakers and other implantable medical devices.

The UCLA team was led by Richard Kaner, a distinguished professor of chemistry and biochemistry, and of materials science and engineering, and the Connecticut researchers were led by James Rusling, a professor of chemistry and cell biology. This design and their work has been published last week in the journal Advanced Energy Materials.

Pacemakers — which help regulate abnormal heart rhythms — are powered by traditional batteries that eventually run out of power and must be replaced. This poses another risk of a painful surgery and the accompanying risk of infection. This combined to the toxic constituents of the batteries that could endanger the patient if they leak.

Kaner’s and Rusling’s groups have invented a supercapacitor that charges using electrolytes from biological fluids like blood serum and urine, and it would work with another device called an energy harvester, which converts heat and motion from the human body into electricity — in much the same way that self-winding watches are powered by the wearer’s body movements. That electricity is then captured by the supercapacitor. Essentially, energy is thus stored in those devices without a battery.

“Combining energy harvesters with supercapacitors can provide endless power for lifelong implantable devices that may never need to be replaced,” said Maher El-Kady, a UCLA postdoctoral researcher and a co-author of the study.

This new supercapacitor is only 1 micrometer thick — much smaller than the thickness of a human hair — as compared to the size of modern pacemakers that are about 6 to 8 millimeters thick.  It also can maintain its performance for a long time, bend and twist inside the body without any mechanical damage, and store more charge than the energy lithium film batteries of comparable size that are currently used in pacemakers.

“Unlike batteries that use chemical reactions that involve toxic chemicals and electrolytes to store energy, this new class of biosupercapacitors stores energy by utilizing readily available ions, or charged molecules, from the blood serum,” said Islam Mosa, a Connecticut graduate student and first author of the study.

The new biosupercapacitor comprises a carbon nanomaterial called graphene layered with modified human proteins as an electrode, a conductor through which electricity from the energy harvester can enter or leave. The new platform could eventually also be used to develop next-generation implantable devices to speed up bone growth, promote healing or stimulate the brain, said Kaner, who also is a member of UCLA’s California NanoSystems Institute.

Although supercapacitors have not yet been widely used in medical devices, the study shows that they may be viable for that purpose.

“In order to be effective, battery-free pacemakers must have supercapacitors that can capture, store and transport energy, and commercial supercapacitors are too slow to make it work,” El-Kady said. “Our research focused on custom-designing our supercapacitor to capture energy effectively, and finding a way to make it compatible with the human body.”

The research was supported by the National Institute of Health’s National Institute of Biomedical Imaging and Bioengineering, the NIH’s National Institute of Environmental Health Sciences, and a National Science Foundation EAGER grant.

This press release has been reproduced from UCLA Newsroom.