A team of researchers from North Carolina State University has achieved a remarkable feat by creating the fastest swimming soft robot to date, drawing inspiration from the graceful movements of manta rays. This innovative design not only improves the robot’s speed but also enhances its ability to control movement in the water.

Lead researcher Jie Yin explains, “Two years ago, we showcased an aquatic soft robot capable of reaching average speeds of 3.74 body lengths per second. Building upon that success, our latest model is more energy-efficient and achieves a speed of 6.8 body lengths per second. Additionally, unlike its predecessor that could only swim on the water’s surface, the new robot can navigate up and down the water column.”

The soft robot features fins designed similar to those of manta rays and is constructed from a stable material that enables the fins to spread wide. These fins are attached to a flexible silicone body housing an air chamber. By inflating the chamber, the fins bend, mimicking the motion of a manta ray’s fins during propulsion. Releasing the air causes the fins to snap back into their original position.

Furthermore, the team studied the fluid dynamics of manta rays to refine the robot’s vertical movement control. Co-author Jiacheng Guo explains, “Observing how manta rays swim, we were able to replicate their behavior to dictate whether the robot moves toward the surface, descends, or remains at a specific depth in the water column. Just like mantas adjust their trajectory by altering their swimming motion, we incorporated a similar mechanism to control the robot’s vertical motion.”

The researchers successfully demonstrated the soft robot’s capabilities in two ways. Firstly, it navigated a course of obstacles placed both on the water’s surface and the tank floor. Secondly, the untethered robot showcased its ability to carry a payload on the water’s surface, including its own air and power source.