The man-made diamond produces a charge simply by being placed in close proximity to a radioactive source. There are no moving parts and no emissions involved and no maintenance is needed. The researchers created a prototype 'diamond battery' using radioactive isotope Nickel-63 as the radiation source. They are now working on improving the efficiency of the battery. To do this, they are using carbon-14, a radioactive version of carbon, which is generated in graphite blocks used to moderate the reaction in nuclear power plants. The carbon-14 is concentrated at the surface of these blocks, making it possible to process it to remove the majority of the radioactive material. The extracted carbon-14 is then incorporated into a diamond to produce a nuclear-powered battery.