Light‑Powered Gel Robot That Swims Like a Leech

A new soft robot moves through water by using light instead of batteries. The device is made from a single sheet of liquid‑crystal gel that has been patterned so its internal molecules twist in a way that produces a traveling wave when it is illuminated. When a laser scans across the sheet, the gel bends in a rhythmic fashion that pushes it forward at about half a millimetre per second. The robot can change direction by shining light on specific parts of its body. A focused beam near the head turns the robot upward, to the left or right, allowing it to swim freely in three‑dimensional space. Experiments show a gel “leech” navigating through a narrow tunnel in salty water, demonstrating true underwater mobility without any tether.The creators also joined two of these gel leeches into one larger piece. By controlling where the light hits over time, the combined robot can swim straight or spin around itself. This dual‑mode movement lets it carry small objects along a user‑designed path, opening possibilities for tiny medical devices that deliver drugs or perform inspections inside the body. What makes this approach unique is that all the motion comes from the material’s internal structure and external light. No electronics or power cords are needed, which keeps the robot lightweight and flexible. The technology shows how precise molecular design can translate simple optical signals into complex, lifelike motion in fluid environments.