Despite the excitement that 3-D printing has generated, its capabilities remain rather limited. It can be used to make complex shapes, but most commonly only out of plastics. Even manufacturers using an advanced version of the technology known as additive manufacturing typically have expanded the material palette only to a few types of metal alloys. But what if 3-D printers could use a wide assortment of different materials, from living cells to semiconductors, mixing and matching the “inks” with precision?

Jennifer Lewis, a materials scientist at Harvard University, is developing the chemistry and machines to make that possible.