A printing head narrower than a human hair delivers a toothpaste-consistency stream of a special lithium ink that hardens after discharge. The head travels back and forth, building up cathodes or anodes for a microbattery more powerful than any battery that has been achieved with traditional thin film printing methods.
One comb-like cathode will be interlaced into another comb-like anode. The secret of producing more power lies in this tightly packed structure. Previous attempts to develop such miniature batteries relied on the thin-film technologies that have evolved for use in manufacturing miniature electronic devices. But the thin films cannot provide sufficient energy to effectively power electrical equipment.
Senior author of the paper 3D Printing of Interdigitated Li-Ion Microbattery Architectures, Jennifer Lewis, Ph.D., of the Wyss Institute for Biologically Inspired Engineering at Harvard University describes the team's achievement:
Not only did we demonstrate for the first time that we can 3D-print a battery, we demonstrated it in the most rigorous way.
Of course, microbatteries create one more challenge for recycling systems and another responsibility for designers to use the technology for worthwhile purposes (think medical or scientific uses rather than disposable consumer gizmos). We can imagine tracking devices to help us better understand the miniature creatures so critical to the base of any ecosystem, for example.
The 3-D printing technology itself also represents a breakthrough. Wyss Founding Director Donald Ingber, M.D., Ph.D remarks:
Jennifer's innovative microbattery ink designs dramatically expand the practical uses of 3D printing, and simultaneously open up entirely new possibilities for miniaturization of all types of devices, both medical and non-medical. It's tremendously exciting.