In today's episode of "weird shit I stumbled onto on the internet", I bring you: nuclear-powered pacemakers.
Some of the earlier pacemakers made in the US, around the 70's, were powered by a very small amount of plutonium. If you've ever heard of the term radioisotope thermoelectric generator or RTG in relation to eg. satellites, that's what the pacemakers used. The upside of using an RTG was that the device could run for decades without needing to get its power source replaced. The downside is that you now have plutonium sown in to your chest cavity – which actually isn't as bad as it sounds considering the amounts used, but it's still a highly radioactive element and presents some fun challenges, some of which are discussed in the article.
Here's an article on the technical details on how they, and thermoelectric kajiggers in general, work https://blog.plover.com/tech/seebeck-effect.html
to put that into some interesting context that's about what your cell phone uses if you go through the battery over 24hrs. With a battery or big capacitor to act as an accumulator you could in theory have a smart phone that never needs charging, or rarely when you use it a lot in one night.
This article poses the idea of a universal smartphone battery.
Remember when we could just remove and swap the battery? Now we could go back to that, removing the part where we charge it and the battery just... does it.
Not quite there yet, but holy hell this looks far more promising than most things we get. The idea of getting away from cell batteries entirely is... momentous.