Biological Power Supplies for Cyborgs (In theory, Sci-Fi, etc.)?

Pardon my posting, but I was wondering…In Science Fiction, at least, are there any common schemes or theories (cliches, even?) that are used to provide a biological power supply for cybernetic implants, rather than batteries, or some other technological power supply? I’m not looking for anything that would have to be technologically possible at the moment, just not physically impossible. Much like the ever-present fusion engines in Sci-Fi starships-Technologically impossible now, but maybe not in the future. You know what I mean. Does anyone have any tips?
Well, thanks for your patience,

Well, you yourself run on electricity. Without it no brain function and no muscle movement. No reason I can see that an implant couldn’t theoretically use the body’s own generated power to function.

That said whatever it is that needs power better not need very much of it. the movie The Matrix aside humans don’t make all that great of a battery. You can get more juice in less space from more mundane batteries. Think of your car battery…big and heavy yes but still smaller than you and able to start your car engine. I’m reasonably certain your own body couldn’t provide the necessary power in the same timeframe.

Most sci-fi cyborgs I’ve seen use nuclear batteries or some kind of rechargeable power supply.

It would be really cool (if creepy) if someone developed a fuel cell that could use blood sugar as a power source.

Or how about a mass of bioengineered muscle tissue, electronically stimulated, turning a crankshaft driving a turbine? We could even almost build that today, although it probably wouldn’t last long enough or generate enough power to be useful.

I’ve given this some thought actually. :> I think an artificial, genetically engineered organ could be implanted based on the organs that supply electricity to electric eels and rays. I believe these organs are made of cells called electrocytes and are just specialised muscle tissues. If you could do a little gene splicing and make a human electrocyte cell you could grow them and implant them somewhere with some spare room, then do a little surgical wiring or some such to get the electricity where it’s needed. I think I recall reading that these organs can supply a steady but very small charge for sensory purposes or a large all at once jolt for defensive purposes, which is a useful quality to have to handle peak and off peak energy usage when operating your cybernetic implants. ;> I think though that we’re talking SMALL implants (cyberpunk type stuff), not robocop like stuff… a robocop type cyborg would require something else.

Actually, one SF solution i’ve heard is nanomanufactured turbines placed along blood vessels, to tap the energy of blood circulation.

SC_Wolf , you are not too far off…

Sure it could – back in the old days, cars had these cranks on the front. You used muscle power to get 'em running. Really. I’m not kidding.