Australian researchers use 4D printing for soft robots

Researchers at the University of Queensland (UQ) are developing a new 4D printing technology that produces shape-changing liquid metals for soft robotics.

4D printing is an extension of 3D printing in which solid objects are produced from materials that can change shape under the influence of heat, water or light.

At UQ’s Australian Institute for Bioengineering and Nanotechnology (AIBN), researchers are printing 4D structures using novel liquid metal polymers that can be excited by infrared lasers to perform various mechanical tasks. The leaders of the project, Dr. Liwen Zhang and Dr. Ruirui Qiao, explained that the unique fabrication methods they have developed allow 4D designs to be produced that are both strong and durable and can bend, grip, lift and release objects five times their weight or return to a pre-programmed shape.

“4D printing takes traditional 3D printing and adds a new dimension – the dimension of time,” Dr Zhang said. “Our method allows us to produce smart liquid metals that can be customised, shaped and prompted to change over time without needing wires or circuits. This is a new era for robotics applications and a gamechanger for additive manufacturing.”

4D-printed objects typically use a 3D printer that uses specific ingredients to give the finished product new properties and capabilities. In the journal Nature Communications, Dr. Zhang, Dr. Qiao and their colleague Professor Tom Davis explain how they used spherical liquid metal nanoparticles to create printing resins that respond to near-infrared light.

This technology makes it possible to use lasers to direct the materials so that they can bend, grip and release objects. Although the technology is still in its infancy, Dr. Qiao sees great potential in its use in the design of soft robotics that mimic natural movements and interactions. This could have numerous applications in the aerospace and medical fields, including coronary stents, artificial muscles and other devices that adapt and change shape in the body.

“4D printing is a rapidly evolving field that is really only limited by imagination,” Dr Qiao said. “The specific nanoparticles we use allow our materials react to lasers. Other 4D printed materials contain ingredients that react to water, heat, acid, electric, or magnetic energy. The early signs for this technology are incredibly promising, and the wide range of potential applications give us encouragement to continue our research.”