Electronic Inks Make 3-D Printing More Promising

Three cofounders of Voxel8, a Harvard spinoff, are showing me a toy they’ve made. At the company’s lab space—a couple of cluttered work benches in a big warehouse it shares with other startups—a bright-orange quadcopter takes flight and hovers above tangles of wires, computer equipment, coffee mugs, and spare parts.

Voxel8 isn’t trying to get into the toy business. The hand-sized drone serves to show off the capabilities of the company’s new 3-D printing technology. Voxel8 has developed a machine that can print both highly conductive inks for circuits along with plastic. This makes it possible to do away with conventional circuit boards, the size and shape of which constrain designs and add extra bulk to devices.

Conductive ink is just one of many new materials Voxel8 is planning to use to transform 3-D printing.

The new ink is not only highly conductive and printable at room temperature; it also stays where it’s put. Voxel8 uses the ink to connect conventional components—like computer chips and motors—and to fabricate some electronic components, such as antennas.

The company made the quadcopter by printing its plastic body layer by layer, periodically switching to printing conductive lines that became embedded by successive layers of plastic. At the appropriate points in the process, the Voxel8 team would stop, manually add a component, such as an LED, and then start the printer again.

The toy looks like something that could be made with conventional techniques. The real goal is to work with customers to discover new applications that can only be produced via 3-D printing. A video the company made to show off its technology starts by asking: “What would you do if you could 3-D print electronics?” While the founders have some ideas, they really don’t know what the technology is going to be particularly useful for.

Voxel8’s business plan is to start by selling the conductive ink and a desktop 3-D printer. The machine is designed primarily to produce prototypes, not to manufacture large quantities of finished product. The company’s long-term goal, however, is to create industrial manufacturing equipment that can print large numbers of specialized materials simultaneously, which will enable new kinds of devices.

The founders will draw on a large collection of novel materials—and strategies for designing new ones—developed over the last decade by cofounder Jennifer Lewis, a professor of biologically inspired engineering at Harvard (see “Microscale 3-D Printing).

One of Lewis’s key insights has been how to design materials that flow under pressure—such as in a printer-head nozzle—but immediately solidify when the pressure is removed. This is done by engineering microscopic particles to spontaneously form networks that hold the material in place. Those particles can be made of various materials: strong structural ones that can survive high temperatures, as well as epoxies, ceramics, and materials for resistors, capacitors, batteries, motors, and electromagnets, among many other things (see “Printing Batteries”).

“The long-term possibility is almost endless numbers of materials being coprinted together with superfine resolution,” says cofounder and hardware lead Michael Bell. “That’s far more interesting than printing a single material.”