Light-Controlled Biohybrid Robot from MIT Engineers: Aquabot

Moving in water requires more force than moving in air. However, the new robot developed by MIT engineers showed that, with an appropriate design, even single-layered muscle cells can produce enough power to swim.

Introduced in the study published in the journal Advanced Functional Materials, the 'aquabot' consists of a gel layer approximately the length and width of a stick of gum. The two halves of this layer, which forms the skeleton of the robot, serve as fins.

Above each fin is a layer of living muscle cells much thinner than a strand of hair. These genetically modified cells contract when exposed to light.

When researchers shine a light on one of the fins, contraction of the muscles on that surface causes the fin to flap. This movement moves the robot forward in the water. The direction and speed of the robot can be controlled by changing which fin and at what intervals the light is given.

PASSED THE LABYRINTH IN WATER

Engineers showed that the robot could navigate and turn through a simple water maze. At its highest speed, the robot covered a distance of approximately four times its own body length in one minute.

This speed is considerably lower than that of Olympic swimmers, who can reach a distance of approximately 65 body lengths per minute. However, the researchers note that the robot's speed, calculated based on its body length, is comparable to some slower-swimming sharks.

One of the authors of the study, MIT Mechanical Engineering Department faculty member Ritu Raman, emphasized that moving in water requires much more force than moving in air, and said that the robot is quite strong for its size.

According to the research team, the study provides the first example in which a muscle-powered robot with a very thin and two-dimensional structure can move.

Such systems, which combine living tissues and artificial materials, are called biohybrid robots.

Researcher Ritu Raman noted that current biohybrid robots developed by her group and other research teams generally rely on bulky, three-dimensional pieces of skeletal muscle grown in the laboratory, requiring millions of cells to produce.

It is thought that thinner structures such as the new design can be produced at a lower cost and move more efficiently.

According to researchers, the softness of living muscle tissue, its ability to react to its environment and its capacity to repair itself may provide an advantage for sensitive tasks in the future. These robots can be used in fragile or unpredictable environments where traditional hardware may struggle to operate.

FROM THE IRIS OF THE EYE TO THE SWIMMING ROBOT

Last year, Raman's team developed an artificial disk of muscle tissue inspired by the movements of the iris in the human eye.

The researchers placed concentric rings and grooves extending from the center to the gel surface, and then grew live muscle cells on this surface. When the cells were stimulated with light, the disc stretched and compressed, similar to a pupil dilating and contracting.

This study showed that a thin layer of muscle cells can produce controlled movements in different directions. However, the magnitude of the movements was limited to approximately 100 micrometers.

In the new research, the team aimed to strengthen these movements and take a robot to a level that can move forward in water. To do this, he focused on the structure of the gel skeleton on which the cells grow.