Engineers at University of California, Los Angeles have come up with a tiny new robot that can be controlled and powered using a beam of light. Called OsciBot, because of its oscillating motion, the robot is made entirely out of a light-responsive hydrogel and doesn’t carry its own power source, relying on an external constant light source to help it push itself along. The technology has significant medical implications, as it allows for very small, soft robots to operate within the body as a drug delivery vehicle or to surgically repair tissues.
The team’s first working prototype was a cylinder that is two centimeters long, positioned at the bottom of a water vessel. They were able to use a constant light source to get the cylinder to wobble about once per second, and by moving the light source around, the team was able to control the direction of the movement. Changing the length and width of the cylinder, as well as other parameters, can be used to change how the cylinder moves.
The team then created an actual robot that looks like a tiny surfboard. The tail is used to absorb the incoming light, and to heat up. This causes the hydrogel to expand and push out some of its water content, making the robot move toward the light source. The tail then cools, since it comes into the shadow of the rest of the hydrogel, and relaxes. As it relaxes, it is again exposed to the light, making it expand and eject water again. This process can be repeated indefinitely, and doesn’t require the outside source of light to do any complicated pulsing. Moving the light around can be used to change the direction in which the robot moves.
“This is really a fundamental demonstration that direct and constant light can power and determine movement,” said the study’s lead author, Yusen Zhao, in a press release. “It could be a step toward a variety of robotic designs that are untethered and powered solely by the available light in their surroundings, rather then relying on heavy batteries or power cables.”
Here’s a UCLA video showing off how the robot moves:
Study in Science Robotics: Soft phototactic swimmer based on self-sustained hydrogel oscillator