3D printer uses lasers to create metallic objects in midair

This Harvard-designed machine uses silver nanoparticles as ink.

This Harvard-made 3D printer can create complex metallic objects other printers can't. See, instead of spitting out one layer over another, the machine was designed to ooze out metal that immediately freezes solid. That allows it to print free-form patterns that look like they're suspended in air, like coils. Created by the university's Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences (SEAS), the printer uses "ink" composed of silver nanoparticles. A focused laser then heats the material and solidifies it as it comes out.

According to Mark Skylar-Scott, one of the researchers, the hardest part was perfecting that technique. If the laser gets too close, it would harden the nanoparticles inside the nozzle and clog it. Plus, the structure could collapse if the system doesn't have perfect timing. Since they did manage to make it work, the method could be used to print out flexible and customized materials for wearables, sensors and medical devices in the future.

Wyss Institute Director Donald Ingber believes "This sophisticated use of laser technology to enhance 3-D printing capabilities not only inspires new kinds of products, it moves the frontier of solid free-form fabrication into an exciting new realm, demonstrating once again that previously accepted design limitations can be overcome by innovation." You can see the technique in action in the video below, but you can also read the team's study in detail on PNAS.