Researchers have made a breakthrough in the printing of metal objects with the development of a highly conductive metallic gel that can be used to fabricate 4D-printed parts at room temperature. The technology—developed by researchers at North Carolina State University, Northwestern Polytechnical University, and Tianjin University in China—represents an evolution for metal 3D printing in a couple of ways.
The conductivity of metal objects that are printed with gel is one. This paves the way “to manufacturing a wide range of electronic components and devices,” noted Michael Dickey, a professor of chemical and biomolecular engineering at the university and one of the project’s lead researchers. “Because the printed objects end up being as much as 97.5% metal, they are highly conductive,” he said in a news release. “It’s obviously not as conductive as conventional copper wire, but it’s impossible to 3D print copper wire at room temperature. And what we’ve developed is far more conductive than anything else that can be printed.”
It also moves 3D printing beyond the 3D realm into a 4D world, where 3D structures can alter shape in response external stimulus or according to time. Heat can be applied while the gel structures are drying to change their shape.
In an abstract published with a journal on the researchers’ work, they noted that 4D-printing techniques are currently focused primarily on electrically isolating materials, such as plastics. It is a Matter.
Gel
The researchers began by creating a suspension of copper microns in water. At room temperature they added a tiny amount of liquid indium-gallium metal alloy.
This process caused the liquid metal and copper particles to stick to each other, forming a metallic gel “network” within the aqueous solution—causing a fairly uniform distribution of copper particles throughout the material.
Dickey says that uniformity is important for the gel to work because it has two purposes. Dickey said, “First, the network of particle connects to form electrical pathway,” he explained. “And second, it means that the copper particles aren’t settling out of solution and clogging the printer.”
Gel can be printed using a 3D printer nozzle. It retains its form when it is printed. After drying at room temperatures, the 3D object retains its shape and becomes more solid. If heat is applied to the object while it’s still drying, the 3D object will expand and become a 4D object.
The team published the below video of the metallic gel printing and drying process. The researchers are currently seeking industry partners to explore potential applications and are open to any other collaborators that have ideas for taking the technology in new directions, Dickey said.
The Potential of 4D-Printing Applications
“Ultimately, this sort of four-dimensional printing—the traditional three dimensions, plus time—is one more tool that can be used to create structures with the desired dimensions,” he said. “But what we find most exciting about this material is its conductivity.”