SHENYANG, Aug. 25 (Xinhua) -- Chinese scientists have built a tiny robot that swims like a manta ray -- a large, flat fish that glides through the ocean with wing-like fins -- and it is powered by real frog muscle.
Their findings were recently published in the international journal Advanced Functional Materials.
The robot, developed by researchers at the Shenyang Institute of Automation under the Chinese Academy of Sciences (SIACAS), needs no wire or battery to move. Instead, near-infrared light controls it. When light shines on small solar panels on the robot's back, they generate tiny electric signals that are transmitted to the nerves on the surface of muscle tissue to control muscle contraction and locomotion.
The research team used a small piece of natural muscle taken from a bullfrog's leg. Unlike lab-grown muscle, which is often weak, this natural tissue has a very neat fiber structure and can produce much stronger force. In lab culture, the muscle stayed responsive for up to 11 days and actuated the robot reliably for a full week.
According to the study, the robot can swim straight, turn left or right, cruise in circles, and even make U-turns -- all without any physical connection to a controller. By shining laser light on the left or right solar panel, the researchers can make one side of the muscle contract while the other relaxes, steering the robot like a real manta ray.
Moreover, the robot is surprisingly fast for its size. It swims at an average speed of 0.54 body lengths per second -- about 2.7 centimeters per second -- and can reach a top speed of 2 body lengths per second. The robot can turn in a very small space, completing a full circle in just 17 seconds. It can also carry small loads up to 5 grams and even move slowly on land.
Zhang Chuang, the study's corresponding author and a researcher at SIACAS, said this is the first time natural muscle has been combined with wireless, light-controlled stimulation. The team showed that real muscle tissue can serve as a powerful, reliable engine for robots.
For future work, the researchers want to keep the muscle alive longer, develop softer electrodes for better control, and add energy storage, so the robot can run on its own.
Zhang said this small swimming robot could help monitor shallow-water environments and observe aquatic life without causing disturbance.
The researchers also believe their method of using electrical signals to control muscles might help in medical fields, such as repairing nerve-damaged muscles or building better lab systems for growing tissue. ■
