There seems to be a bit of a buzz at the moment about \”nano\” computers you can spray on out of a can.
Well, aside from currently being sci-fi, these designs don’t need batteries. There are lots of other ways to do it.
The most promising and common is simply to make it micropowered, and run it off a capacitor. Another way is to use a coil and leach off RF or magnetic fields from 50/60Hz AC hum (very viable in a modern home or hospital). Another one is this bit of advanced magic for picking up higher-energy RF, called the \”solar cell\”, which neatly sidesteps problems with antenna lengths.
The neatest, and most tricky to counter, is a built in generator which leaches energy from movement directly, by the movement of a tiny magnet inside a coil, with some charging logic. Store it in a thin-film capacitor for a while.
Another clever way, which would be good for small devices, would be a peizoelectric skin over a small air bubble, which would generate voltage from changes in air pressure, or sound.
So you don’t even want a battery, most of the time. Given the tiny amounts of power being used, you would also be lucky to pick up any difference in power consumption for an area.
Frying these things would get quite tricky, too, as they are going to be made almost totally from silicon, and so it will be like trying to kill sand!
Killing the nano-computers would be very dependant on what they were using for energy generation, and how hardy they were, plus the shear number of them.
If they were using RF, for example, using a hot flame would be effective, but if they used a tiny stirling engine, it wouldn’t be, as they would covert that heat into electric, and be able to broadcast a warning, for example…
Someone needs to give though to how we deal with the clean-up of these things. Otherwise we will have billions of tiny computers all over the place, until they form one or two enormous networks that are no use to us at all!