Cornell researchers have built a microscopic robotic array that senses temperature and coordinates tiny paddles to move liquid, a laboratory step toward machines that could collectively change their surroundings.
The work combines sensing, electronic communication and fluid pumping in one system. Researchers say it is the first demonstration of microscopic robots responding together to alter their physical environment, but proposed medical and agricultural uses remain possibilities for future designs, not demonstrated applications.
The study, “Microscopic Robots that Sense and Reshape Their Environment,” was published Sept. 23 in Nature Electronics. Postdoctoral researcher Jinsong Zhang and former Cornell doctoral student Wei Wang are co-first and corresponding authors, and physics professor Itai Cohen is a corresponding author.
Fifty-four paddles work as a team
The researchers arranged 54 hinged artificial cilia in an array with two temperature-sensing circuits. One circuit acts as a leader and the other as a follower, sending electronic signals that synchronize the paddles and set the direction in which they pump liquid.
When the sensed temperature crosses a set point, the circuits direct the cilia to pump one way; below that point, they reverse. The coordinated motion can move liquid from hotter areas to cooler ones or in the opposite direction, according to the Cornell Chronicle's account of the research.
Zhang drew on the way natural cilia help single-celled organisms move and pump fluid. The team's artificial version does not copy their shape directly. Each paddle has two hinges whose programmed, sequential motion pushes surrounding liquid, and many paddles are needed to produce a collective effect.
Engineering professor Alyssa Apsel developed the temperature-dependent electronic component used in the array. The chips exchange voltage pulses so the paddles keep a shared rhythm, a synchronization strategy the researchers compared with fireflies flashing together.
Future uses remain experimental
Cohen's lab has previously developed microscopic robots that can walk, sense, image, measure and communicate. This study adds coordinated manipulation of the environment to that set of capabilities, though the demonstrated device is a static array rather than a group of independently moving robots.
Later versions might respond to light or acidity and trigger chemical or mechanical actions, Cohen said. The researchers also envision robots that could walk separately and react to cues in medical or agricultural settings, but the study does not report testing those uses.
The project was supported primarily by the Army Research Office and the National Science Foundation, with additional support from Cornell's Kavli Institute for Nanoscale Science. Some work was done at the Cornell NanoScale Science and Technology Facility. The research team also included collaborators at the universities of Cambridge, Illinois Chicago and Chicago.
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