[FoRK] Sugar High (Voltage)

Stephen Williams sdw at lig.net
Sat Jun 16 20:37:19 PDT 2012

Awesome.  Stripping electrons right off of glucose.

MIT creates glucose fuel cell to power implanted brain-computer interfaces
By Sebastian Anthony on June 13, 2012 at 9:55 am

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Neuroengineers at MIT have created a implantable fuel cell that generates electricity from the glucose present in the 
cerebrospinal fluid that flows around your brain and spinal cord. In theory, this fuel cell could eventually drive low-power 
sensors and computers that decode your brain activity to interface with prosthetic limbs.

The glucose-powered fuel cell is crafted out of silicon and platinum, using standard semiconductor fabrication processes. The 
platinum acts as a catalyst, stripping electrons from glucose molecules, similar to how aerobic animal cells (such as our own) 
strip electrons from glucose with enzymes and oxygen. The glucose fuel cell products hundreds of microwatts (i.e. tenths of a 
milliwatt), which is a surprisingly large amount — it’s comparable to the solar cell on a calculator, for example. This should 
be more than enough power to drive complex computers — or perhaps more interestingly, trigger clusters of neurons in the brain. 
In theory, this glucose fuel cell will actually deprive your brain of some power, though in practice you probably won’t notice 
(or you might find yourself growing hungry sooner…)

Size-wise, the MIT engineers have created glucose-powered fuel cells that are as large as 64x64mm (2.5in), or as small as just a 
few millimeters. In the picture above, the large yellow square is a single 64x64mm fuel cell, and it’s surrounded by a bunch of 
smaller versions. Presumably the largest fuel cell produces the most electricity — but at that size, I don’t think it would fit 
inside a human brain at least. You could quite easily implant a few dozen of the smallest fuel cells in your spinal cord, however.

This discovery is exciting for two main reasons: a) The fuel cell is completely synthetic, and b) they can be produced using 
low-tech, decades-old chip fabrication processes. Glucose fuel cells have been created before, primarily to power pacemakers, 
but they used biological enzymes (like your own cells) — and enzymes need to be replenished. Platinum, however, will happily 
strip electrons from glucose indefinitely. Platinum also has the added bonus of being very biocompatible — i.e. your immune 
system doesn’t try to reject it. Cerebrospinal fluid is almost entirely devoid of cells, too — it’s basically just a 
glucose-rich fluid that insulates your brain and spine. Because there are no cells, this means there are no white blood cells 
that can reject the fuel cell.

Ultimately, this fuel cell will hopefully be used to power implanted, ultra-low-power devices that sit inside your skull or 
spinal cord. In actual fact, MIT’s research into this fuel cell was led by Rahul Sarpeshkar, who happens to be one of the 
leaders of hybrid digital-biological devices. So far, implanted devices have mostly been tethered to a wall socket — but now, 
Sarpeshkar’s group can begin work on implants that are completely self-powered.

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