Human-Powered Medical Devices

A new biofriendly energy storage device called a biological supercapacitor has been developed by UCLA and University of Connecticut researchers to work using charged particles, or ions, from fluids in the human body. The device is harmless to the biological systems of the body and could contribute to cardiac pacemakers and other implantable medical devices that are longer-lasting. Richard Kaner, a distinguished professor of chemistry and biochemistry and of materials science and engineering, led the UCLA team, and James Rusling, a professor of chemistry and cell biology, led the Connecticut researchers. This week a paper was published in the journal Advanced Energy Materials about their nature.

Pacemakers and other implantable devices that help control irregular heart rhythms have saved countless lives. But they are operated by conventional batteries that inevitably run out of power and have to be replaced, which means another painful operation and the risk of infection that follows it. Furthermore, batteries contain hazardous materials that if they leak, could endanger the patient.

The researchers suggest storing energy without a battery in those devices. They developed the supercapacitor charges using electrolytes from biological fluids such as blood serum and urine, and it would function with another system called an energy harvester, which transforms heat and motion from the human body into electricity, in the same way that the wearer’s body movements power self-winding watches. The supercapacitor then captures the energy.

Maher El-Kady, a UCLA postdoctoral researcher and a co-author of the study, said that combining energy harvesters with supercapacitors would provide infinite power for lifetime implantable devices that might never need to be replaced.

Usually, modern pacemakers are about 6 to 8 millimetres thick, and about the same diameter as a 50-cent coin; the battery typically occupies about half of that space. The new supercapacitor is just 1 micrometre thick, much smaller than the thickness of a human hair, meaning it will increase the energy efficiency of implantable devices. It can also retain its output for a long time, bend and twist without any mechanical damage within the body, and store more charge than the lithiuuu energy

“Unlike batteries that use chemical reactions that involve toxic chemicals and electrolytes to store energy, this new class of biosupercapacitors stores energy by utilising 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 consists of a carbon nanomaterial called graphene coated as an electrode with modified human proteins, a conductor from which electricity can enter or exit from the energy harvester. Eventually, the new platform could also be used to build implantable devices for the next generation to speed up the development of bones, facilitate healing or stimulate the brain, Kaner said.

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