What’s the one thing standing in the way between ourselves and a future ruled by nanomachines? Well, actually a lot of things are standing in the way, but one of the most prominent is a lack of tiny batteries to power the devices.

Harvard researchers announced on Tuesday that they have finally overcome the tiny battery problem thanks to 3D printers. The team, led by Jennifer A. Lewis, said that it was able to create a battery the size of a grain of sand by printing “precisely interlaced stacks of tiny battery electrodes.”

Lewis captured in a statement the two ways in which this breakthrough is pretty amazing – “Not only did we demonstrate for the first time that we can 3D print a battery; we demonstrated it in the most rigorous way.” It’s the latter that’s most impressive as making batteries small enough to fit inside increasingly smaller, yet more powerful, machines has been a headache for a lot of researchers.

With the advent of these small batteries, researchers hope that they’ll be able to innovate in medical fields. There’s already work being done on tiny machines that could be used for invasive procedures, and these new batteries may provide them the power necessary to work for extended periods of time inside a person’s body.

Speaking of power, the researchers found that the tiny batteries are “comparable to commercial batteries in terms of charge and discharge rate, cycle life and energy densities.”

If you want to see how they did it, watch this video:

[Image: Jennifer A. Lewis/Harvard University]