Zothecula writes: As development of micro- and nano-scale devices continues to advance, so does the need for an equally-tiny method of powering them. There’s not much point in developing a surveillance micro air vehicle the size of a housefly, for instance, if it requires a watch battery in order to fly. That’s why DARPA (the U.S. Defense Advanced Research Projects Agency) is funding a project to create really tiny batteries. Just how tiny are we talking, here? Well, they’re aiming for something smaller than a grain of salt.