If you’re going to build a swarm of nanobots to take over the world, you’ll need a lot of very tiny batteries. You could build microscopic AAs with exceedingly diminutive tools, or turn to the best nano-scale builder known: Nature. Scientists at Yale were studying how some cells turn chemical energy into electrical energy (brain cells, the cells that give electric eels their zap) when they inadvertently created synthetic cell batteries.

The simple cells are essentially lipid sacks filled with salt water and a modified protein. When two of the synthetic cells touch, they stick together. The proteins create pores between the two cells. If the two cells have different salt concentrations, positive or negative ions will pass through the pores shared wall until salt concentrations in both cells reach an equilibrium. Stick the cells with electrodes to siphon off the ions and you’ve got a microscopic battery.

Two 200-nanoliter drops of the cells in solution can deliver electricity for about 10 minutes. An 11-microleter volume can put out a charge for more than four hours.

Researchers say the cells turn chemical energy into electrical energy at about 10 percent efficiency, which is frankly pretty terrible for a battery. But it’s pretty good when compared to tiny solar cells or piezoelectric devices that generate electricity from mechanical stress.

Link to Gizmag article