Mar 6, 2018 | By Benedict

Engineers at Oregon State University have found a way to 3D print tall, complicated structures with a highly conductive gallium alloy. The 3D printing process could be used to make flexible computer screens and other stretchable electronic devices, including soft robots.

Gallium alloys, which typically have low toxicity and good conductivity, are already used as the conductive material in many flexible electronics. They're also inexpensive and “self-healing,” meaning they can reattach at break points.

Until now, however, these gallium alloys have not been 3D printed, limiting their use to specific applications.

The exciting new 3D printing development at OSU, which could open up these alloys to several further applications, involves the use of a process called sonification, which uses sound energy to mix nickel particles and oxidized gallium into a 3D printable metal.

The engineers found that this alloy could be 3D printed into structures up to 10 millimeters high and 20 millimeters wide.

Without the nickel particles, the gallium would be too runny to print. But with the nickel mixed in using sonification, the mixture becomes paste-like and easily 3D printable. Moreover, the electrical properties of the paste are comparable to pure liquid metal, while the paste also retains self-healing characteristics.

“The runny alloy was impossible to layer into tall structures,” explains Yiğit Mengüç, assistant professor of mechanical engineering and co-corresponding author on the study. “With the paste-like texture, it can be layered while maintaining its capacity to flow, and to stretch inside of rubber tubes.”

To demonstrate the power of their new gallium 3D printing technique, the researchers 3D printed a “very stretchy” two-layered circuit whose layers weave in and out of each other without touching. Other future applications could include electrically conductive textiles, bendable displays, strain sensors, wearable sensor suits, antennae, and biomedical sensors.

“The future is very bright,” says co-author Doğan Yirmibeşoğlu, a robotics Ph.D. student at OSU. “It’s easy to imagine making soft robots that are ready for operation, that will just walk out of the printer.”

The research, “Rheological Modification of Liquid Metal for Additive Manufacturing of Stretchable Electronics,” has been published in Advanced Materials Technologies.

Posted in 3D Printing Materials

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