Inspired by the movement of insects gliding on the surface of water, University of Waterloo researchers have designed tiny robots controlled by light, offering promising possibilities for environmental remediation and biomedical applications.
"We're moving toward smart, swimming robots with more autonomous behaviour by making them respond to external cues like light, or magnetic fields," said Dr. Hamed Shahsavan, a professor in the Department of Chemical Engineering and director of the SMART-Lab.
Dr. Hamed Shahsavan and his research team led the development of how these tiny robots can move once exposed to ultraviolet light. (University of Waterloo)
The research team was inspired by the movement strategy of Gerridae insects, commonly known as water striders, which release chemicals through their bodies to allow them to glide on water. They also manipulate the water's surface with their legs to control the direction of their motion.
Tiny robots made to mimic the insects feature liquid crystal elastomers, materials that change shape in response to light, and protein-based chemical motors inspired by squid biology.
When exposed to ultraviolet (UV) or visible light, flexible legs on the robots bend upward or downward, altering surface tension with the water and mirroring how water striders steer to move forward, turn or pivot.
A demonstration of a robot that cannot control its movement (left) and one that is self-propelled using light. (University of Waterloo)
A protein taken from the suction cups of squids provides a motor for the devices by absorbing and releasing chemical fuel.
"This combination of propulsion and control of the direction of movement is essential in the field of microrobotics," said Shahsavan, who collaborated with researchers from the University of Michigan. Dr. Abdon Pena-Francesch, and graduate students Chuqi Huang and Natalie Pinchin were also involved in the research.
"With our design, you can control the robot's movement without any physical tethers or external motors."
A demonstration of how the use of light is able to "bend" the leg of the robot. (University of Waterloo)
Development of the tiny swimming robots builds on previous work led by Shahsavan to create soft, hydrogel composite materials, which include sustainable cellulose nanoparticles derived from plants, for just this purpose.
Potential real-world applications of the research, which was conducted using two-dimensional sheets, include autonomous robots deployed to clean up microplastics in bodies of water, or robots guided inside the human body to perform highly specialized medical procedures.
Future work will focus on creating three-dimensional robots capable of navigating both on the surface and underwater. Researchers are also exploring other propulsion methods, such as magnetic fields, to expand the capabilities of their robots.
"We're laying the foundation for a new generation of microrobots," said Shahsavan. "With further development, these smart swimming robots could navigate environments autonomously."
The study, Self-Propelled Morphing Matter for Small-Scale Swimming Soft Robots, was published in the Journal of Advanced Functional Materials.
