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.

Now read about a brain-computer interface that bypasses paralyzed limbs, or decoding the brain to integrate a bionic eye

Read more at MIT or download the paper at PLoS ONE (non-paywalled!)