Bio supercapacitor implants that run for life on body power
A graphine based energy storage system that charges itself using ions from the human body has been developed by researchers at the University of California at Los Angeles and the University of Connecticut. The biological supercapacitor is harmless to the body's systems, making it a useful alternative to the batteries used by pacemakers and other medial implants which need to be removed for battery replacement. The supercapacitor is one micrometre thick and can theoretically make energy available to an implanted device indefinitely.
A new energy storage system charges itself using ions from inside the human body – providing an exciting alternative to traditional batteries used in pacemakers, according to researchers at the University of California at Los Angeles and the University of Connecticut.

Researchers at the universities developed a bio-friendly energy storage system called a biological supercapacitor; it’s harmless to the biological systems in the body. The device could enable cardiac pacemakers and other implantable medical devices that last longer.

Pacemakers are small battery-powered devices that help the heart beat in a regular rhythm. They create electrical impulses that help stimulate the heart to beat, according to the American Heart Association. A pacemaker has a sensing mode that allows it to send impulses when the heartbeat is above a certain level and can fire when the heartbeat is too slow. However, the batteries need to be replaced after awhile, which forces the patient to undergo another surgery.

A 2012 study suggests that pacemaker implants are on the rise with 2.9 million patients receiving some sort of pacemaker between 1993 and 2009, an increase of 55.6%. As the use of pacemakers continues to rise, battery-free implantable devices couldn’t come soon enough.

The researchers suggest that storing energy in the devices without a battery could be beneficial. Their device, the supercapacitor, uses electrolytes found in biological fluids like blood serum and urine to charge. It works with an energy harvester device that converts heat and motion from the body into electricity. The supercapacitor captures that electricity.

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

Researchers developed the new supercapacitor device to be 1 micrometer thick. Normal pacemakers are 6-8mm thick with about half of the device having a battery. It can also bend and twist in the body without being damaged and can store more of a charge than the lithium film batteries in regular pacemakers.

“Unlike batteries that use chemical reactions that involved 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 University of Connecticut graduate student and first author on the study.

The biosupercapacitor is made of graphene layered with modified human proteins that act as an electrode for electricity from the energy harvester to come and go. The researchers hope this technology will help develop implantable devices that can expedite bone growth, promote healing or stimulate the brain.

“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,” said El-Kady. “Our research focused on custom-designing our super capacitor to capture energy effectively, and finding a way to make it compatible with the human body.”

The National Institute of Health’s National Institute of Biomedical Imaging and Bioengineering, the National Institute of Health’s National Institute of Environmental Health Sciences and a National Science Foundation EAGER grant funded the research. It was published online in the journal Advanced Energy Materials.

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