Researchers at the University of Illinois have created world's smallest working fuel cell. The device measures just 3mm x 3mm x 1mm and has four components: a water reservoir, a thin membrane, a chamber with metal hydride and an assembly of electrodes.
Because the device is so small - just 3 mm by 3 mm by 1 mm - surface tension, not gravity, controls the flow of water through the system. This means that the cell operates even if moved and rotated - perfect for life inside a pocket gadget.
The first designs generated 0.7 volts and a current of 0.1 milliamps for 30 hours before the fuel ran out, but Moghaddam says the latest designs give currents of around 1 milliamp at a similar voltage. That's not yet enough to drive cellphones, which use batteries typically rated at a few volts, but it's enough for simpler electronic systems or microrobots, he says.