Using blood for power

General Questions
#1

Is there any experimental technology in the works for getting chemical power from human blood? I ask this because it seems like the best way to power a prosthetic limb would be to tap the body itself. That way a person could just power that limb the same way as all his other parts. With food and oxygen.

What aspects would have to be addressed? I can think of:

-How do you actually convert the stored energy in blood to usable energy for the limb? And without poisoning the blood with waste products?

-Can it be done efficiently enough that it doesn’t use up too much food and O2? Otherwise, the person would slowly starve and/or asphixiate when the device started using up all the energy.

What else am I missing?

#2

I’ve as yet only skimmed this pdf file about the mechanical efficiency of human muscle tissue, but that strikes me as a potential major hurdle: designing a mechanical system of comparable efficiency, if it could only use the body as an energy source.

#3

Well, there are glucose fuel cells, so the tech to generate power from the necessary form of sugar exists. However, they seem to be envisioning relatively low-power scenarios with the fuel cell getting its glucose from cerebrospinal fluid, not blood–which leads us back to Bryan’s point that artificial substitutes for muscle tissue require lots of power.

#4

If you’re a vampire, AB+ is most nutritious. Preferably fresh from the veins a young virgin girl.

#5

I’ve done some quick reading of piezoelectric motor efficiency (the idea of using piezoelectrics in prostheses is not new) and even then… attaching a prostheses directly into the circulatory or cerebral-spinal system for transfer of fuel and waste strikes me as inviting massive infections.

Rather, I suggest the development of supercapacitors might be more promising. These are already being studied for vehicles and portable electronics, and possibly might be light enough to be carried around in a prosthesis while carrying enough charge for 16 or 18 hours. The artificial limb will have to be “fed” somehow but relying on human biochemistry… tricky.

Heck, DARPA is (or at least was) working on an arm that was fueled by burning hydrogen peroxide, though I assume this required periodic replacement of the power source “about the size of a pencil” with all the risks that entails. It’s possibly not something a person with only one good arm could manage.

#6

Blood glucose is also used in this nifty experimental under-skin visual interface for devices.

http://gizmodo.com/5401714/digital-tattoo-interface-turns-your-skin-into-a-display

Haven’t heard much more about it since it splashed, but I’d be all over this. So many options: a blood glucose monitor for diabetes that’s actually a visual graph on your skin (how much cooler than pricking your finger and using a handheld?) or even for burning a few extra calories (hey guys, look at my animated full-back tat! It burns 20 calories an hour!!) :smiley:

#7

Ah, yes, the steam-powered prosthetic. It showed promising strength, but definitely had hurdles: potentially hazardous fuel, extremely high-precision machining, and burning-hot components. (Of course, these would likely have been selling points with the steampunk crowd.) Given that I don’t see anything new about it since 2007, and the deadline for the DARPA program was 2009 for a commercially available arm, it seems likely that their funding was dropped.

#8

Something is wrong there. You can’t burn hydrogen peroxide. Hydrogen peroxide is already as “burned” (oxidized) as it is possible to get. It says it “burns” to produce pure steam. Either they are using the peroxide to “burn” (oxidize) hydrogen or they are reducing the peroxide to make water plus oxygen. Maybe (I don’t know) the latter is an exothermic reaction that will produce steam if it goes fast enough, but I would not have thought this would provide a very energy dense fuel source, even if it were. All in all, something is definitely not right with the info in that article. There is not way to go from just H[sub]2[/sub]O[sub]2[/sub] to just pure H[sub]2[/sub]O). The numbers don’t add up.

#9

http://en.wikipedia.org/wiki/Hydrogen_peroxide#Decomposition

The decomposition of H[sub]2[/sub]O[sub]2[/sub] into H[sub]2[/sub]O and O[sub]2[/sub] is both an energy producer and just about the most common reaction anybody knows about Hydrogen Peroxide. True, it doesn’t go “to just H[sub]2[/sub]O” but it is used as a propellant in a variety of specialty applications such as rocketry and submarines. http://en.wikipedia.org/wiki/Hydrogen_peroxide#Propellant

#10

Or full body camoflage…

#11

I had one of those robot arms, until it sank in the Barents Sea.

#12

Lucky bastard! Mine keeps trying to launch into the air to intercept Allied bombers! :smiley:

#13

Blood doesn’t power your limbs, nerves do. Blood feeds the nerves and muscles. There is new research into enervated prosthetics that allow the patient to feel what the prosthetic hand touches.

#14

Nerves are the controls. Blood supplies the energy, and thus powers (energy per unit time) the limbs.

#15

Not exactly. Chemicals crossing the nerve synapses cause an electrical reaction that causes the muscle to move. All the blood in the world won’t make a muscle move without the nerve firing.

#16

And all the gasoline in the world won’t make a car move without a functioning engine but we’re still comfortable saying that the gas fuels and powers the car.

#17

I’ve heard of this, but only in connection with things like implanted pacemakers (or which I have one). My battery will have to be replaced one of these years and I am hoping that by the time it happens this will be perfected. (They replace the whole device, not just the battery.)

It would seem to me that powering an arm or leg would require orders of magnitude more power than a pacemaker.

#18

Remember that your pacemaker does not power your heart. It stimulates the cascade that results in muscle contraction, powered by ATP, which is made from glucose, which is carried in the blood. This takes a minuscule amount of energy, such that the battery lasts for years, and a good chunk (half?) of its energy is spent on background functions unrelated to muscle stimulation.

#19

And you have to pull the trigger of a gun to make the bullet fly, but no one claims your finger powers the bullet. Nerves are an electrochemical signaling device.

#20

This makes me wonder what kind of devices could be reasonably powered by glucose? The aforementioned pacemaker and blodd monitor, sure. Could something as large as a cell phone be charged with glucose power? RFID chips get their power from outside induction IIRC. But what about a more active device that could broadcast things like a homing beacon or health monitoring device?