Researchers in Oregon State University's (OSU) College of Engineering believe that its work in 3D printing tall (up to 10mm high and 20mm wide), complex structures with a highly conductive gallium alloy may be the key.
The team put nickel nanoparticles into the liquid metal, galinstan, to thicken it into a paste with a consistency suitable for additive manufacturing
"The runny alloy was impossible to layer into tall structures," explains Yiit Mengüç, assistant professor of mechanical engineering at OSU. "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, where the layers weaved in and out of each other without touching."
Prior to this modification developed, OSU says that previous methods used sonication to mix the nickel particles and the oxidised gallium into the liquid metal, meaning alloy’s printability was restricted to 2-dimensional.
"Liquid metal printing is integral to the flexible electronics field," adds Doan Yirmibeolu, a robotics Ph.D. student at OSU. "Additive manufacturing enables fast fabrication of intricate designs and circuitry."
The researchers believe this system could show promise for electrically conductive textiles, bendy displays, sensor for torque, wearable sensor suits and biomedical sensors.
"The future is very bright," Yirmibeolu continues. "It's easy to imagine making soft robots that are ready for operation – that will just walk out of the printer."
OSU believes the gallium alloy paste demonstrates several features new to the field of flexible electronics.
"It can be made easily and quickly," Uranbileg Daalkhaijav, Ph.D. candidate in chemical engineering at OSU, explains. "The structural change is permanent, the electrical properties of the paste are comparable to pure liquid metal, and the paste retains self-healing characteristics."
The researchers say future work will explore the exact structure of the paste, how the nickel particles are stabilised and how the structure changes as the paste ages.
