With a flash of light and a ripple of fin, the small aquatic robot set off across the water and into the annals of science as the latest advance in artificial creatures.

A melding of tissue and technology, the robot in question resembles a miniature stingray. It has a thin rubbery body, a skeleton of gold, and an unusual power source: a sheet of heart cells that contract when illuminated with pulses of blue light.



In demonstrations at Harvard University, the 16mm-long robot glided around a water tank at the leisurely pace of 3.2mm per second. Powered by the heart cells, its makers guided the robo-ray through an obstacle course more than 15 times longer than its own body.



Facebook Twitter Pinterest Light-controlled cardiac muscle cells guide swimming of an artificial animal.

Kevin Kit Parker, a professor of bioengineering at Harvard University, said the small, squidgy robot was a “training exercise” that will lead on to other “biohybrid robots” and ultimately reveal how best to build a human heart.



Described as a “technical tour de force” by one independent expert, the “living robot” spent more than a year as an idea on a napkin. When Parker told his postdoc Sung-Jin Park, the plan, he was not overly enthusiastic. “We’re going to take a rat apart and rebuild it into a stingray and make it laser-guided,” Parker told him. The postdoc’s response was “horror and sorrow.”



Parker’s previous forays into what he calls “synthetic beasts” include a robotic jellyfish made by overlaying heart cells on a silicone cup. Zap the cells with electricity and the cup squeezed inwards, propelling the robot forwards.



His latest creation was inspired by a visit with his daughter to the New England Aquarium in Boston. When she reached out to touch a stingray in the petting tank, it veered sharply off to one side. The coordination of the muscles might have similarities with the heart’s behaviour, he thought.



Built to one-tenth the size of a living ray, the 10g robot has a thin polymer body and a gold skeleton printed on top. Over the skeleton is a layer of 200,000 rat heart cells, genetically modified to contract when blue light is shone on them.



Facebook Twitter Pinterest Robo-ray, left, and the real stingray. Photograph: Karaghen Hudson/Science

Because the cells need energy, the robo-ray swims in a tank of warm water, salt and glucose. Light the front of the robotic ray with blue laser light and the heart cells contract, setting off an undulation that sweeps down the fins and propels the machine forwards. To steer the robot left or right, the researchers simply illuminated either side of the robot with more intense light.



The end result is “clearly a technical tour de force,” Adam Summers, a biologist at the University of Washington, Seattle told Science magazine, where the report is published.



Now the ray is built, Parker has started work on a new artificial creature. “It’s like a work of art. You make it and then abandon it for ever,” he said. “We’re moving on to the next one. But i’m not telling anyone what it will be yet,” he said.

