Future neural prosthetics could not only tap into brain signals, but also brain fluids, using the cerebrospinal medium to power a fuel cell. Researchers at MIT designed a new silicon wafer with several embedded fuel cells that generate power using glucose.
The fuel cell creates a small electric current by harvesting electrons from glucose molecules — essentially the same method employed by cells, which degrade glucose into ATP. ATP transports energy within cells, driving metabolism. In this case, the fuel cell uses electrons to generate a few hundred microwatts of electricity.
Engineers led by Rahul Sarpeshkar fabricated the device on a silicon wafer, using the same methods employed by semiconductor fabricators. It uses a nanostructured platinum anode, which oxidizes glucose molecules, and single-walled carbon nanotubes form the cathode, which completes chemical reactions that reduce oxygen to water. The presence of the two components of the redox reaction could short-circuit the device, but Sarpeshkar's team structured it to shield the anode while exposing the cathode to the body's environs.
They ran some computer models to determine how much energy would be available in cerebrospinal fluid, and how much the device would need to operate effectively. Since spinal fluid circulates continually and contains plenty of glucose, the team figures they could harness at least 1 megawatt of energy without any adverse effects on the brain. Another benefit is the lack of immune cells in that fluid, so there would likely be no immune response causing the body to reject the fuel cell.
This is still a long way from powering an implant, but it's proof that it could work — the body may be able to provide all the energy the device would need. A paper describing the fuel cell appears in the journal PLoS One.
Guy's, get your facts straight. I can tell without even looking into this further that the below statement is a very obvious typo, or just plain ignorance from the editor in terms of how much power 1 Megawatt actually is:
"the team figures they could harness at least 1 megawatt of energy without any adverse effects on the brain"
For reference, 1 Megawatt = 1 Million watts! There is no way a tiny implant can generate this. You can power an entire home with this much energy.
Your statement of:
"This is still a long way from powering an implant,"
Implies that perhaps you meant 1 Milliwatt? Fix your typo please, this is supposed to be a tech magazine. I'm surprised you folks let this kind of thing get past your editors.
1 megawatt, lol. Hello, brain-powered Iron Man suit!
And dameatman, since you love accuracy so much, I would love to be the first to point out that you can power way more than an 'entire' home with 1MW of power. Get your facts straight.
"...(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...".
yosifcuervo, yes you are correct. 1 million watts is enough to power about 1000 average homes for a very brief period of time.
micro, mega, embiggen, smiggen, its all the same, eh.
See life in all its beautiful colors, and
from different perspectives too!
wow awesome. soon this will make all our dreams come true!! super strong artificial limbs here we come!!!!!!!
"You take the blue pill – the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill – you stay in Wonderland and I show you how deep the rabbit-hole goes." -Morpheus
Just encase anyone doesn't think that's a typo.
Human body consumes 2000 Calories a day (average). That is actually 2000 kilo-calories, or 2 million calories.
A Calorie is the number of Joules it takes to heat 1 gram (cm3 or ml) of water 1 degree Kelvin (Celsius), which is ~4.17J/g*K.
So over the course of a day, you consume:
2e6 * 4.17 = some 8 million Joules. Over 1 day.
Now lets look at Megawatts. That equals 1 million Joules per second. In 8 seconds, that powers us for a day. Lets look at the actual power we consume:
Seconds in a day? 24 hours per day. 3600 seconds per hour.
8 e6 / 24 / 3600 = 92.6 J/s = 92.6 W = .0000926 MegaWatts
So yes, the brain has a good chance of missing a Mega-Watt of energy. As does the rest of your body, and a quarter of your small town.
For an equally dispelling concept; The human body can be assumed to turn all burnt calories into waste heat. Lets see what happens when our brain uses 1 Mega-Watt.
One Mega-Watt of energy used equates to One Mega-Watt of waste heat. 1 million Joules of energy turned to heat each second.
Remember that Calorie conversion? It works both ways. Assume your brain weighs 2kg. That's 2000 grams of material with specific heat roughly equal to water (4.17J/g*K).
1,000,000g*K / 2000g / 4.17 = 119 K (+119 C each second)
That much energy, each second, is enough to boil your brain. As my bio-mechanics professor would have said in his perfect engrish:
"You would have... Instant - Steak".
This message brought to you by Stoichiometrics-Anonymous: because SOMEONE had to pay attention in Middle school Chemistry.