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Implantable Medical Device Draws Energy Directly from Human Body

  Implantable Medical Device Draws Energy Directly from Human Body

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: Dr. Maher El-Kady/UCLA and Dr. Islam Mosa/University of Connecticut

Researchers from UCLA and the University of Connecticut have designed a biofriendly energy-storage system called a biological supercapacitor, which operates using charged particles, 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.

Pacemakers — which help regulate abnormal heart rhythms — and other implantable devices have saved countless lives. But they’re powered by traditional batteries that eventually run out of power and must be replaced, meaning another painful surgery and the accompanying risk of infection. In addition, batteries contain toxic materials that could endanger the patient if they leak. The researchers propose storing energy in those devices without a battery.

The supercapacitor researchers invented 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. “Combining energy harvesters with supercapacitors can provide endless power for lifelong implantable devices that may never need to be replaced,” says Maher El-Kady, PhD, postdoctoral researcher in the lab of team leader Richard Kaner, PhD, distinguished professor of chemistry and biochemistry and of materials science and engineering.

Modern pacemakers typically are about 6-to-8 millimeters thick and about the same diameter as a 50-cent coin; about half of that space is usually occupied by the battery. The supercapacitor developed by Dr. Kaner and his team is only 1 micrometer thick — much smaller than the thickness of a human hair — meaning that it could improve implantable devices’ energy efficiency. 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.

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 also eventually be used to develop next-generation implantable devices to speed up bone growth, promote healing or stimulate the brain, says Dr. Kaner, who is a member of UCLA’s California NanoSystems Institute. Although supercapacitors have not yet been widely used in medical devices, the study shows they may be viable for that purpose.

“Ultrathin Graphene-Protein Supercapacitors for Miniaturized Bioelectronics,” Advanced Energy Materials, May 9, 2017


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