Researchers have come out with an implantable fuel cell which may be a boon to paralysed patients in regaining control of their arms and legs.
Developed and designed by Rahul Sarpeshkar, associate professor of electrical engineering and computer science at MIT, and Benjamin Rapoport, former graduate student in Sarpeshkar's lab, who led the study, the fuel cells runs on the same sugar that powers human cells - glucose.
Researchers fabricated the fuel cell on a silicon chip, allowing it to be integrated with other circuits that would be needed for a brain implant, the journal Public Library of Science ONE reports.
The idea of a glucose fuel cell is not new: In the 1970s, scientists showed they could power a pacemaker with a glucose fuel cell, but the idea was abandoned in favour of lithium-ion batteries, which could provide significantly more power per unit area than glucose fuel cells, according to an MIT statement.
These glucose fuel cells also utilised enzymes that proved to be impractical for long-term implantation in the body, since they eventually ceased to function efficiently.
The new twist to the MIT fuel cell, fabricated from silicon, using the same technology behind semiconductor electronic chips, is that it has no biological components: It consists of a platinum catalyst that strips electrons from glucose, mimicking the activity of cellular enzymes that break down glucose to generate ATP, the cell's energy currency.
Platinum has a proven record of long-term biocompatibility within the body.
So far, the fuel cell can generate up to hundreds of microwatts - enough to power an ultra-low-power and clinically useful neural implant.
"It will be a few more years into the future before you see people with spinal-cord injuries receive such implantable systems in the context of standard medical care, but those are the sorts of devices you could envision powering from a glucose-based fuel cell," says Rapoport.
He calculated that in theory, the glucose fuel cell could get all the sugar it needs from the cerebrospinal fluid (CSF) that bathes the brain and protects it from banging into the skull.
There are very few cells in the CSF, so it's highly unlikely that an implant located there would provoke an immune response.
There is also significant glucose in the CSF, which does not generally get used by the body. Since only a small fraction of the available power is utilized by the glucose fuel cell, the impact on the brain's function would likely be small.
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