A new kind of 3D printed material could make technology more heat-resistant.
Unlike most naturally occurring solids, these manmade, mesh-like materials shrink when they’re heated up. By tweaking the materials’ chemical composition, the researchers could control how much they shrank at different temperatures. This work could apply to everything from circuitry to dentistry.
Many devices warp or break at high temperatures because they’re made of metal, glass, or other normal solids that expand as they get hotter. Manufacturers can create sturdier devices if they incorporate some components that contract at higher heat, giving other pieces room to expand without breaking. But such shrinking solids are extremely rare. As a result, scientists have been trying since the mid-’90s to fabricate them in the lab.
The new 3D-printed “lattices” are grid-like structures mere millimeters across and are made up of tiny interlocking rods. Some of the rods are pure plastic; others are infused with copper nanoparticles. As they heat up, the pure-plastic beams swell faster than their copper-infused counterparts, bending in towards the center of the lattice and pulling the copper-reinforced rods along with them. This effectively causes the whole structure to crumple in on itself, said Qiming Wang, an engineer at the University of Southern California and lead author on the new study.
To test the lattices’ shrinkage, Wang’s team placed them inside a glass chamber and turned up the heat. As the chamber went from room temperature to 540 degrees Fahrenheit, the 3D-printed structures initially maintained their size and then gradually contracted. This work is described in Physical Review Letters.
The sugar-cube-sized lattices only shrink about the width of a human hair on each side, said Nick Fang, a mechanical engineer at the Massachusetts Institute of Technology and coauthor on the new study. But even this small change in size could make a big difference to engineers using these materials to build high-precision optical and mechanical devices. “This work is very innovative,” said Akihiro Takezawa, an engineer at Hiroshima University who is unaffiliated with the project.
According to Takezawa, these materials could be especially useful because of their tunable quality. Wang’s team could control how much the lattices shrank at different temperatures by changing how many nanoparticles they injected into the copper-infused rods. It’s also possible to fine-tune the lattices’ shrinkage by altering the width and orientation of their rods, Fang said.
Wang and his colleagues have proposed myriad uses for their new 3D-printed products. Take microchips, for example. When computers operate for a long time, they tend to heat up, which can cause their microchips to crack. Fashioning some microchip components that contract at higher temperatures could help computers withstand overheating. The researchers’ current 3D-printing method could construct samples less than a millimeter across, “so current technology is already good for microchip applications,” Wang said.
The lattices could similarly be used to build sturdier drone cameras, Fang said. If a drone flies up even 10 meters on a hot summer day, the increased temperature can cause the camera lens to expand. A contracting frame around the lens could act as a buffer that would keep a swelling lens from breaking the camera.
Fang said that the new 3D-printed materials could even be used to make something as simple as a dental filling. Unlike normal metal or plastic fillings, non-expanding fillings wouldn’t cause a toothache when the wearer drinks a hot beverage.
The lattices also might be used in ways that scientists haven’t even considered yet, said Jonathan Berger, a mechanical engineer at the University of California, Santa Barbara who was not involved in the study. It’s difficult to compile a full list of applications, he said, “for these materials that theoretically you can do completely new things with.”
The next step for Wang’s team is to devise a speedier method of manufacturing lattices. Some of the biggest structures printed for this study—each only a centimeter or so across—took 12 hours to make. But Wang hopes that eventually 3D-printing will provide a cheap, relatively easy way for designers and engineers to produce tunable materials for more heat-resistant tech.
“It’s a long road to travel to get these kinds of lattices into airplanes or circuit boards where there’s a huge established industry,” Berger said. “But it’ll be really exciting to see where this technology goes.”