This robo-stingray made from rat heart cells is controlled by light

Researchers placed muscle cells, or cardiomyocytes, along the top of the robo-ray

08 Jul 2016
Karaghen Hudson

Inspired by the elegant and highly efficient movement of a stingray, researchers have created a robotic equivalent made using cells from the heart of a rat that can be controlled by light.

Batoid fish, which include stingrays, are instantly recognisable by their flat bodies and long, wing-like fins extending from their heads.

These fins move in such a way to generate the most movement while using the least amount of energy possible. These energy-efficient waves emulate from the front of the fin to the back, allowing batoids to glide gracefully through water.

Karaghen Hudson/Science

Inspired by this design, Sung-Jin Park from Harvard University endeavoured to build a miniature, soft tissue robot with similar qualities and efficiency. His team created 'charged' gold skeletons that mimic the stingray's shape. These were then overlaid with a thin layer of stretchy polymer.

Along the top of the robotic ray, the researchers placed muscle cells from rats, known as cardiomyocytes. The cardiomyocytes, when stimulated, contract the fins downward.

Karaghen Hudson/Science

Since stimulating the fins to turn in an upward motion would require a second layer of cardiomyocytes, the researchers instead designed the gold skeleton in a shape that stores some downward energy which is later released as the cells relax, allowing the fins to rise.

Each of these cells were genetically engineered to respond to light, and this meant the researchers could control the robot's movement using flashes and light cues. Asymmetrical pulses of light can be used to turn the robot to the left or right, the researchers showed, and different frequencies of light can be used to control its speed, as demonstrated in a series of videos.

The method works well enough to guide the robot through a basic obstacle course. The robotic stingray, containing roughly 200,000 cardiomyocytes, is 16 millimeters long and weighs just 10 grams.