By modifying a commonly used alloy, researchers may soon be able to 3D print tall and complicated structures like flexible computer screens and soft robots.
A team from Oregon State University’s College of Engineering have created a highly conductive gallium alloy by putting nickel nanoparticles into galinstan, a liquid metal that enables them to thicken the alloy into a paste with a consistency suitable for additive manufacturing.
“The runny alloy was impossible to layer into tall structures,” Yiğit Mengüç, an assistant professor of mechanical engineering and co-corresponding author on the study, said in a statement. “With the paste-like texture, it can be layered while maintaining its capacity to flow, and to stretch inside of rubber tubes. We demonstrated the potential of our discovery by 3D printing a very stretchy two-layered circuit whose layers weave in and out of each other without touching.”
Gallium alloys are currently used as the conductive material in flexible electronics because they have low toxicity and good conductivity. They are also inexpensive and are able to attach back together at break points.
However, the alloys’ printability has always been restricted to 2D. To overcome this hurdle, the scientists used sonication—the energy of sound—to mix the nickel particles and the oxidized gallium into the liquid metal.
This move enabled them to print structures up to 10 millimeters high and 20 millimeters wide.
The alloys could enable a wide range of products, including electrically conductive textiles, bendable displays, sensors for torque, pressure and other types of strain, wearable sensor suits like those used in the development of video games, antennae and biomedical sensors.
“Liquid metal printing is integral to the flexible electronics field,” co-author Doğan Yirmibeşoğlu, a robotics PhD student at OSU, said in a statement. “Additive manufacturing enables fast fabrication of intricate designs and circuitry.
“The future is very bright,” Yirmibeşoğlu added. “It’s easy to imagine making soft robots that are ready for operation, that will just walk out of the printer.”
Co-corresponding author Uranbileg Daalkhaijav, a PhD candidate in chemical engineering, added that the gallium alloy paste could be made easily and quickly. The structural change for the paste is also permanent and comparable to pure liquid metal while retaining its self-healing characteristics.
The study was published in Advanced Materials Technologies.
