The goal is to develop medical-grade implants with energy sources that will last decades without charging.

We've covered Arkenlight's diamond-based betavoltaic battery technology in detail before. In brief, this company was formed by researchers at the University of Bristol who developed a means for taking bits of radioactive waste from nuclear power stations – specifically, carbon-14 and tritium from reactor parts that have been exposed to fuel rod radiation – and converting them into diamonds that can harvest the high-energy electrons, or beta particles, that it emits, and turn them into usable electricity.

These beta-voltaic batteries will generate power for an extremely long time – some can be designed to last for decades, others for thousands of years, depending on the half-life of the specific isotope they use. And despite the fact that they're made from radioactive nuclear waste, Arkenlight CEO Morgan Boardman tells us via email that they're very safe for use near, or even inside the human body.

"Externally," writes Boardman, "beta radiation of this kind doesn't penetrate human skin. Internally, there is no measurable surface emission of activity, so the the risk is minimal. The extreme hardness of the diamond structure makes it almost impossible to break, and even if it fractured the risk is still low - though this requires destructive testing to demonstrate. One must consider a force strong enough to damage a diamond – at that moment, a very low dose leak on a broken edge of the power cell would likely be the least of a patient's worries!"

It's important to note, though, that we're talking about tiny amounts of power here, and that other companies promising to power consumer devices and electric cars with nuclear diamond batteries are yet to demonstrate how they'll do so without having batteries bigger and heavier than the devices themselves.