Researchers from Oregon State University (OSU) United States, have taken a decisive step towards manufacturing of flexible electronics like computer screens, wearable devices and other devices including soft robots. The research supported by Office of Naval Research Young Investigator Program has made a novel modification in the manufacturing of flexible electronics devices.
Oregon State University College of Engineering is one of US’s largest engineering programs with a stringent focus on research which amount to a huge $37.2 million expenditure. The college’s Collaborative Robotics and Intelligent Systems Institute team recently made a significant advancement for additively manufacturing tall & complicated structures from gallium alloy which is highly conductive and hence suitable for electronics.
According to the OSU study published in Advanced Materials Technologies (AMT), the alloy, Galinstan, which has extremely low viscosity, was injected with nickel nanoparticles to thicken it into a paste making it suitable for 3D printing flexible electronics.
Speaking on the thickening process Yiğit Mengüç, assistant professor of mechanical engineering and co-corresponding author on the study said, “The runny alloy was impossible to layer into tall structures. 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.”
Above: 3D Printed parts made from liquid metal, Galinstan/Image Credit: Oregon State University (OSU)
Use of gallium alloys in flexible electronics is not new, in fact, the advantages of high conductivity and low toxicity of the alloy make it one of the most favourable material to be used in flexible electronics. Additionally, the alloy is ‘Self-healing’ – able to join back together at breakpoints. The cheap availability makes it even more suitable for experimentation purpose and hopefully as the core element in actual flexible electronic devices.
The initial research with gallium alloy was restricted to two-dimensional printing due to inherent limitations but the OSU research team used sonication – using sound energy – to mix nickel nanoparticles and the oxidized gallium into the liquid metal. But the thick consistent paste can now be used to 3D print the alloy. The researchers have already 3D printed 10×20 millimetre structures to check the feasibility.
Co-author & a robotics Ph.D. student at OSU, Doğan Yirmibeşoğlu said, “Liquid metal printing is integral to the flexible electronics field. Additive manufacturing enables fast fabrication of intricate designs and circuitry.” He continued, “The future is very bright. It’s easy to imagine making soft robots that are ready for an operation that will just walk out of the printer.”
Co-corresponding author & Ph.D. candidate in chemical engineering, Uranbileg Daalkhaijav, added that the newly created paste has demonstrated some unique features new to the field of flexible electronics.
Daalkhaijav continued, “It can be made easily and quickly. The structural change is permanent, the electrical properties of the paste are comparable to pure liquid metal, and the paste retains self-healing characteristics.”
Additive manufacturing has helped the research in a great way and the research will go a long way in 3D printing flexible electronics. The possibilities for flexible electronics are endless and products like electrically conductive textiles bendable displays; sensors for torque, pressure and other types of strain; wearable sensor suits, such as those used in the development of video games; antennae; and biomedical sensors will be the biggest beneficiary when the research is successful and commercially viable.
The research team has suggested that the further work will continue on the exact structure of the paste and how the nanoparticles can be stabilised and its long-term aging effects.
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