A thimbleful of some radioactive isotopes could theoretically run a cardiac pacemaker or a sensor on a space probe for decades. However, no one has ever come up with a practical nuclear battery (SN: 8/24/02, p. 125: Available to subscribers at Micromachine runs on nuclear power).
Now, a team of industry and university researchers has demonstrated a tritium-fueled battery with 10 times the efficiency of earlier designs. To perform that feat, the researchers riddled a silicon chip with more than 100 million deep, narrow wells and filled them with tritium gas. When a tritium atom in a well decays, it spits out an energetic electron. Because of the well's depth, that electron rarely escapes. Instead, it plunges into a specially treated layer of the well's wall, unleashing other electrons that contribute to an electric current.