They might sound dangerous, but nuclear batteries have been safely powering devices such as pace-makers, satellites and underwater systems for years. They have an extremely long life and high energy density compared to chemical batteries. However, they are costly and also very large and heavy. Now researchers at the University of Missouri (MU) are developing a nuclear battery that is smaller, lighter and more efficient.

Jae Kwon, assistant professor of electrical and computer engineering at MU, who has been working on building a small nuclear battery, admits that people get the wrong idea when they hear the term "nuclear battery" and think of something hazardous. Although nuclear batteries generate electricity from atomic energy like nuclear reactors, they don't use a chain reaction, instead using the emissions from a radioactive isotope to generate electricity. So there's no risk of the battery in a pace-maker suffering a meltdown.

The battery being developed by Kwon and his research team is currently the size and thickness of a penny, and is intended to power various micro/nanoelectromechanical systems (M/NEMS). The team's innovation is not only in the battery's size, but also in its semiconductor, which is liquid rather than solid.

"The critical part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure of the solid semiconductor," Kwon said. "By using a liquid semiconductor, we believe we can minimize that problem."

Kwon has been collaborating with J. David Robertson, chemistry professor and associate director of the MU Research Reactor, and is working to build and test the battery at the facility. In the future, they hope to increase the battery's power, shrink its size and try various other materials. Kwon said that the battery could be thinner than the thickness of human hair.

Kwon's research appears in the Journal of Applied Physics Letters and Journal of Radioanalytical and Nuclear Chemistry.