Electronic medical implants have worked wonders for lots of people, and we're only just realizing what is potentially possible in the future. What we need, though, is a power source that doesn't involve opening people up and replacing batteries every few years, and these spinal fluid powered glucose fuel cells could make that happen.
The cells in our bodies are powered by glucose. When we eat stuff, our bodies suck glucose out of the food we're digesting and send it through our bloodstream to keep all of our cells up and running. MIT engineers have figured out that they can pilfer some of this glucose out of the cerebrospinal fluid surrounding your brain and spine and strip it of electrons to power ultra-efficient electronic devices.
These latest glucose fuel cells are especially cool because they can be fabricated out of silicon, and since they don't rely on chemicals or enzymes that break down or wear out (just a platinum catalyst), they can continue providing power as long as you keep eating things. At peak output, the fuel cells can generate hundreds of microwatts of power (comparable to what it takes to run one of those little solar-powered calculators), which isn't a heck of a lot, but it's enough to run a brain or spinal implant that could potentially transmit neural signals to bypass damaged areas.
While the hardware is just proof of concept at the moment, researchers are envisioning self-powered medical implants becoming a standard medical tool in just "a few" years.