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Researchers at MIT creates glucose fuel cell to power implanted brain-computer interfaces
By Sebastian Anthony : Original Article @ Extreme Tech
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…)
A Glucose Fuel Cell for Implantable Brain–Machine Interfaces
Benjamin I. Rapoport, Jakub T. Kedzierski, Rahul Sarpeshka
We have developed an implantable fuel cell that generates power through glucose oxidation, producing steady-state power and up to peak power. The fuel cell is manufactured using a novel approach, employing semiconductor fabrication techniques, and is therefore well suited for manufacture together with integrated circuits on a single silicon wafer. Thus, it can help enable implantable microelectronic systems with long-lifetime power sources that harvest energy from their surrounds. The fuel reactions are mediated by robust, solid state catalysts. Glucose is oxidized at the nanostructured surface of an activated platinum anode. Oxygen is reduced to water at the surface of a self-assembled network of single-walled carbon nanotubes, embedded in a Nafion film that forms the cathode and is exposed to the biological environment. The catalytic electrodes are separated by a Nafion membrane. The availability of fuel cell reactants, oxygen and glucose, only as a mixture in the physiologic environment, has traditionally posed a design challenge: Net current production requires oxidation and reduction to occur separately and selectively at the anode and cathode, respectively, to prevent electrochemical short circuits. Our fuel cell is configured in a half-open geometry that shields the anode while exposing the cathode, resulting in an oxygen gradient that strongly favors oxygen reduction at the cathode. Glucose reaches the shielded anode by diffusing through the nanotube mesh, which does not catalyze glucose oxidation, and the Nafion layers, which are permeable to small neutral and cationic species. We demonstrate computationally that the natural recirculation of cerebrospinal fluid around the human brain theoretically permits glucose energy harvesting at a rate on the order of at least 1 mW with no adverse physiologic effects. Low-power brain–machine interfaces can thus potentially benefit from having their implanted units powered or recharged by glucose fuel cells.