(Nanowerk News) Traditionally, soft robots have been made using synthetic polymers, rubber, and plastics. These materials provide soft robots with a long operational life and a stable structure, but can pose a risk to the environment if lost or damaged during use. Researchers are working to minimize this risk by creating new ways to build biodegradable robots.
An interdisciplinary team at Carnegie Mellon University, led by faculty members Victoria Webster-Wood and Adam Feinberg in collaboration with Carmel Majidi and Lining Yao, is developing new ways to make biodegradable actuators for marine applications. Using a bio-ink made from a material sourced from common brown seaweed, the research team identified the design and printing parameters that would allow water-resistant structures to be printed using the FRESH Printing method.
“We are excited to expand the fabrication capabilities of the FRESH Printing method and optimize it for soft robotic applications,” said Wenhuan Sun, Ph.D. mechanical engineering students. “The unique benefits of FRESH make it possible to create robotic structures with unusual combinations of properties.”
Their approach, recently published in Advanced Functional Materials (“Continuous and Continuous Hydrogel Actuators with Shape Morphing and Rigidity Capabilities via Embedded 3D Printing”), enabling small scale, very malleable actuators that can extend, bend, and rotate to be fabricated. They can also be combined into a structure for gripping and positioning. The seaweed-based ink used by the research team relies on calcium to cross-link and form a gel. This allows researchers to take advantage of material properties to create actuators that can change shape and stiffness by varying the degree of crosslinking in the actuator.
“How do we balance the need for advanced soft robotic structures with the potential environmental impact resulting from their creation? We believe that biodegradable actuators printed using FRESH are a promising solution, and we are excited to continue making improvements,” said Ravesh Sukhnandan, Ph.D. mechanical engineering students.
The actuator’s capabilities don’t stop there. In addition to its robotic function, the actuator is fully biodegradable, degrading under natural ocean conditions within seven days. Actuators can also be safely consumed by marine organisms. This means that if lost or damaged in use, the actuator poses minimal risk to the environment.
Wenhuan Sun graduated in the fall of 2023, but he keeps in touch with the research team to assist and train the next generation of biodegradable robotics researchers. MS-BRIDGE Fellow Avery Williamson and GEM University Fellow Ravesh Sukhnandan continue to develop the technology under the guidance of Webster-Wood, Feinberg, Majidi and Yao. They hope to better understand actuator performance in natural environments and extend this molding approach to complement robotic structures.
“We are very pleased to be able to continue this project that Wen left behind,” said Williamson. “It’s great fun to develop new tools and methods for technologies with clear sustainable applications.”