Nuclear batteries have been in use for military and aerospace applications, but are typically far larger. A team at the University of Missouri says that the batteries hold a million times as much charge as standard batteries. They employed a liquid semiconductor to capture and utilize the decay particles.

The team’s solution uses a liquid semiconductor, in which the tiny particles can pass without causing damage. They are now working to further miniaturize the batteries, with hopes of making something appropriate for commercial use.

And although the whole idea hinges on the use of radioactive materials, the devices are safe under normal operating conditions.