Bio-Fuel Cells, Batteries not required

"So, how long do you live? I mean, last?"
"My fuel cell lasts for 120 years."

While killer cyborgs with long-lasting fuel cells is uber cool (unless you are the one they are after), one doesn't require a Terminator to be a cyborg or claim long-lasting fuel cells.

Most of us are anyway part human part machine using spectacles, hearing aids, cochlear implants, pacemakers, deep-brain stimulation devices, urinary sphincters, insulin pumps and so on. Apart from making us cybernetic organisms (cyborgs in vernacular) it also adds to us something in common with the terminators.

Batteries.

All these devices require power to work. Power provided by cells which are usually implanted within the body. The best of these run out of juice in 5-8 years, after which one must undergo a surgery to replace them or wait around while you plug yourself in to recharge with wires penetrating the skin and connected to an external battery.

While its an acceptable alternative to death, all masochism aside, it is inconvenient.
They are also something of a dweeb as to the amount of power they can provide, so that power-hungry, artificial, implantable kidneys and hearts are still in the dark.

A team of scientists seem hell-bent on correcting this disparity between humans and terminators. But rather than simply use batteries, which must be charged up, they have invented fuel cells which generate their own power, like a mini generator.

Cells which run off the glucose found naturally in the blood!

The Glucose bio-fuel cell or GBFC has graphite discs for electrodes, wrapped in semipermeable-biocompatible plastic used in dialysis machines. The plastic packs the enzymes- Glucose Oxidase (GOX), Catalase and Urease, Ubiquinone at anode and Quinhydrone at cathode. The semi-permeable plastic allows glucose molecules to seep in while keeping most other things out. GOX strips electrons from glucose molecules locally and reduces the pH while Urease increases the pH, the difference driving electron exchange. These electron displacement occurs to and from the electrodes via electron-shuttles Ubiquinone and Quinhydrone, respectively. This leads to electric current. Catalase breaks down the toxic hydrogen peroxide generated as a consequence of GOX activity also providing additional oxygen for GOX to work with.

The breakthrough can be attributed to a change of approach, where instead of chemically attaching the enzymes with the electrodes (which the enzymes don't like) they are just tightly packed within a plastic sheath. The enzymes used are immune to interference from the ions in the body and can work stably at physiological pH. Earlier ones used needed acidic conditions.

The electrodes take up around 0.266 mL in a merely 5 mL cell. The present device can generate around 24.4 µW per mL of peak power and a stable power of 7.52 µW/mL, while a typical pacemaker requires 10 µW.
The scientists claim they have made a 50 fold improvement in the power characteristics of the cell since the paper was published.

While this fuel cell has shown a great improvement in peak power output and actively integrates the device with glucose from the body, the reliability and lifetime of such a new technology still needs various medical certifications/approvals before we benefit from a revolution in biomedical technology.

"So, how long do you live? I mean, last?"