Creator of 3D Printed Sea Slug Robots Works to Organize Nascent Organismal Engineering Field

When is the last time you thought about the many amazing capabilities of the California sea slug? I’m going to guess it’s been quite a while. The squishy creature is a mollusk, about the size of a guinea pig, and lives in tide pools in the Pacific Ocean. The sea slug eats seaweed, can release ink when it’s distressed just like squids and cuttlefish, and is very durable, able to survive in the constantly changing conditions of tide pools.

This last quality is what caught the attention of Victoria (Vickie) Webster-Wood, a post-doctorate researcher in the Department of Mechanical and Aerospace Engineering at Case Western Reserve University (CWRU). Last summer, her team published on their work with sea slugs, turning them into biohybrid robots, powered by the slugs’ living muscle tissue, with the help of 3D printing technology. Her research has continued, and evolved, since then, and she is currently working to further organize the field as a whole.

Vickie Webster-Wood

“This is a very young field, really—the merging of the two fields of tissue engineering and robotics—and right now, there is no consistency in the vocabulary and really no universal lexicon,” Webster-Wood explained. 

“There has been, over the last decade, an increase in developments of tissue engineering, in the ability to fabricate different things out of living materials. And while there has been parallel acceleration in robotics, researchers from these two fields tend to use different vocabularies.”

By now a renowned sea slug robotics expert, Webster-Wood is also the lead author of a paper, titled “Organismal engineering: Toward a robotic taxonomic key for devices using organic materials” and published in the journal Science Robotics, which explains how important it is to build a comprehensive foundation for the emerging field it calls organismal engineering, which combines robotics and tissue engineering.

The abstract reads, “Engineers are often inspired by the behavioral flexibility and robustness seen in nature. Recent advances in tissue engineering now allow the use of organic components in robotic applications. By integrating organic and synthetic components, researchers are moving toward the development of engineered organisms whose structural framework, actuation, sensing, and control are partially or completely organic. This review discusses recent exciting work demonstrating how organic components can be used for all facets of robot development. On the basis of this analysis, we propose a robotic taxonomic key to guide the field toward a unified lexicon for device description.”

Webster-Wood and the other authors of the paper – Ozan Akkus, Professor of Mechanical and Aerospace Engineering and Director of the Tissue Fabrication and Mechanobiology Lab; Assistant Professor of Mechanical and Aerospace Engineering and Director of the Case Biomanufacturing and Microfabrication Laboratory Umat A. Gurkan; Biology, Biomedical Engineering, and Neuroscience Professor Hillel J. Chiel; and Roger D. Quinn, Professor of Engineering and Director of the Biologically Inspired Robotics Lab – are working to build a taxonomy and lexicon for the nascent field that will be widely accepted, so other researchers can eventually work together in an effort to create the first organic robot that’s fully functioning sometime in the next several decades.

“That’s my goal and, hopefully, I’ll even be the one to create it. But there are a lot of steps yet to be taken to get there, and this is a big one,” said Webster-Wood.

Since introducing the world to her swimming, 3D printed biohybrid robots, which were built from sea slug muscle tissue attached to a 3D printed polymer, Webster-Wood and her team have been evaluating the space shared by tissue engineering and robotics, both of which also share space with 3D printing technology often.

For the paper, her team developed an robotic taxonomic key (RTK), that can be used to describe and organize organic robots and other biohybrids. The key was built around the four basic robotics components, each of which is based on the commonalities between living creatures and robots:

• Structure – in a biological organism, this is the body; for a traditional robot, it’s metal or plastic components bolted together
• Actuators – the device which makes the structure move, like a muscle (biological) or motor (robot)
• Sensors – antennae, eyes, or skin in living organisms; range finder or camera in robots
• Controller – these are neurons in a living creature, and a computer in a robot

The researchers wrote in the paper, “For each wedge, there is a simple question: Is the component organic (solid), hybrid (striped), or synthetic (open)? By asking these questions, we can categorize all existing devices, whether that device has organic components or is fully synthetic, as well as devices yet to come.”

The team’s paper has also set up an organized list of terms, the first of its kind, that describe organic and biohybrid robots. It also mentions most of the important published papers on these devices.

“You’ve got to have those things in place. That way, people aren’t inventing a wheel and then saying ‘Oh, a dozen other people have already invented that!” Webster-Woods explained.

“To our knowledge, this is the first time an article has been published that looks at organic materials being used for all four of these components and how that could lead to completely organic robots. It’s not as sensational as sea slugs, but we think it will be just as important.”

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[Images: Case Western Reserve University]