UTA Scientist Develops Hydrogels Capable of Intricate Movement

Living organisms expand and contract soft tissues to accomplish intricate, 3D movements and functions, but reproducing those movements with man-made materials has proven tough.

Kyungsuk Yum, UTA assistant professor in the Materials Science and Engineering Department (Credit: UTA)

A University of Texas at Arlington scientist recently published innovative research in Nature Communications that shows potential in discovering a solution.

Kyungsuk Yum, an assistant professor in UTA’s Materials Science and Engineering Department, and his doctoral student, Amirali Nojoomi, have developed a method by which 2D hydrogels can be programmed to expand and shrink in a space- and time-controlled manner that applies force to their surfaces, enabling the creation of intricate 3D shapes and motions.

This method could possibly change the way soft engineering systems or devices are designed and fabricated. Potential applications for the technology include bio-inspired soft robotics, artificial muscles — which are soft materials that alter their shapes or move in reaction to external signals as human muscles do — and programmable matter. The concept is also relevant to other programmable materials.

We studied how biological organisms use continuously deformable soft tissues such as muscle to make shapes, change shape and move because we were interested in using this type of method to create dynamic 3D structures.

Kyungsuk Yum, Assistant Professor, Materials Science and Engineering Department, UTA

His method uses temperature-responsive hydrogels with local degrees and rates of swelling and shrinking. Those properties allow Yum to spatially program how the hydrogels swell or shrink in reaction to temperature variation using a digital light 4D printing technique he formulated that includes three dimensions plus time.

Using this technique, Yum can print numerous 3D structures at the same time in a one-step process. Then, he mathematically programs the structures' shrinking and swelling to form 3D shapes, such as saddle shapes, wrinkles and cones, and their direction.

He also has formed design rules founded on the concept of modularity to develop even more multifaceted structures, including bio-inspired structures with programmed sequential motions. This makes the shapes dynamic so they can travel through space. He also can manipulate the speed at which the structures alter shape and thus form complex, sequential motion, such as how a stingray swims in the sea.

Unlike traditional additive manufacturing, our digital light 4D printing method allows us to print multiple, custom-designed 3D structures simultaneously. Most importantly, our method is very fast, taking less than 60 seconds to print, and thus highly scalable.

Kyungsuk Yum

Yum’s paper titled “Bio-inspired 3D structures with programmable morphologies and motions,” was published in the September 12th issue of Nature Communications.

The study is an example of data-driven discovery, one of the themes of UTA’s Strategic Plan 2020: Bold Solutions | Global Impact, said Stathis Meletis, chair of the Materials Science and Engineering Department.

“Dr. Yum’s approach to creating programmable 3D structures has the potential to open many new avenues in bio-inspired robotics and tissue engineering. The speed with which his approach can be applied, as well as its scalability, makes it a unique tool for future research and applications,” Meletis said.

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