You're looking at one of the smallest batteries ever made. Measuring less than a millimeter on each side, the tiny lithium-ion device was actually produced by a 3D printer. Which is nothing short of incredible when you think about it.
Most additive manufacturing techniques lay down layers of plastic. But to produce this battery, Harvard engineers built a custom machine that laid down new materials loaded with lithium-metal-oxide particles.
Scientific American explains:
While squeezing out the nanoparticles like toothpaste, the printer's nozzle drew a pair of five-fingered electrodes interlocked together like hands clasped in prayer. The paste hardened and the process was repeated, again and again, to add more layers and thicken the rechargeable battery.
The final product included up to 16 strata submerged in an electrolyte solution and weighed less than 100 micrograms. Yet it stored almost as much energy, gram for gram, as larger lithium-ion batteries that run laptops and electric cars. And the power it dished out, 2.7 milliwatts per square centimeter of area covered, rivaled the capabilities of other cutting-edge microbatteries developed in recent years at the Massachusetts Institute of Technology and the University of Illinois at Urbana-Champaign.
In future, this battery could provide power for tiny medical devices or miniature robots – like RoboBees!