Researchers at Case Western Reserve University have combined tissues from a sea slug with flexible 3-D printed components to build “biohybrid” robots that crawl like sea turtles on the beach.

A muscle from the slug’s mouth provides the movement, which is currently controlled by an external electrical field. However, future iterations of the device will include ganglia, bundles of neurons and nerves that normally conduct signals to the muscle as the slug feeds, as an organic controller.

In the future, swarms of biohybrid robots could be released for such tasks as locating the source of a toxic leak in a pond that would send animals fleeing, the scientists say. Or they could search the ocean floor for a black box flight data recorder, a potentially long process that may leave current robots stilled with dead batteries.

Webster worked with Roger Quinn, the Arthur P. Armington Professor of Engineering and director of Case Western Reserve’s Biologically Inspired Robotics Laboratory; Hillel Chiel, a biology professor who has studied the California sea slug for decades; Ozan Akkus, professor of mechanical and aerospace engineering and director of the CWRU Tissue Fabrication and Mechanobiology Lab; Umut Gurkan, head of the CWRU Biomanufacturing and Microfabrication Laboratory, undergraduate researchers Emma L. Hawley and Jill M. Patel and recent master’s graduate Katherine J. Chapin

The researchers chose the sea slug because the animal is durable down to its cells, withstanding substantial changes in temperature, salinity and more as Pacific Ocean tides shift its environment between deep water and shallow pools. Compared to mammal and bird muscles, which require strictly controlled environments to operate, the slug’s are much more adaptable.

Akkus said, “When we integrate the muscle with its natural biological structure, it’s hundreds to 1,000 times better.”

With the goal of making a completely organic robot, Akkus’ lab gelled collagen from the slug’s skin and also used electrical currents to align and compact collagen threads together, to build a lightweight, flexible, yet strong scaffold.

The team is preparing to test organic versions as well as new geometries for the body, designed to produce more efficient movement.

If completely organic robots prove workable, the researchers say, a swarm released at sea or in a pond or a remote piece of land, won’t be much of a worry if they can’t be recovered. They’re likely to be inexpensive and won’t pollute the location with metals and battery chemicals but be eaten or degrade into compost.