Researchers at Harvard University have created a biohybrid stingray. No larger than the average coin, the ray contains both biological and artificial parts—rat heart cells grown on a silicon mold fitted over a 3D printed gold skeleton. And it can move. Using a technique called optogenetics, the heart cells are genetically modified to contract when they’re hit with a beam of light.
Watch how it's done:
The heart cells are taken from two-day-old rat embryos and grown inside a pattern on a stingray-shaped mold to mimic the muscles of a living ray. The biohybrid ray’s muscles move in one direction and the gold skeleton counters them like a spring. Various light sources are used to move the ray around different obstacles at speeds up to nine meters per hour.
How does the biohybrid ray compare to similar robots? In some ways, it’s more advanced than earlier biomimetic UAV-style jellyfish or flying robot jellyfish because of the biological components. But to be fair, the robotic ray isn’t quite an underwater species yet. It requires nutrient fluids kept at around the temperature of a rat’s body to keep those muscle cells alive—so it isn’t leaving the lab to do practical work in the field anytime soon.
Still, it’s a pretty amazing invention with interesting implications for robots that aren’t entirely mechanical. By integrating advances in genetic engineering, cell culture, biomimetics, and optogenetics, the ray offers a fascinating glimpse of how new technologies can converge. (And this isn't the only biohybrid creature in development.)
“We’re getting to the point where there really is a fusion between biology and engineering,” says Frank Fish, a biomechanist at West Chester University in Pennsylvania.
Why start with a biohybrid ray?
Kevin Kit Parker, an applied physicist at Harvard University and the maker of the biohybrid ray, has dedicated his life to building an artificial heart. While working on a project using heart muscle cells, he visited an aquarium and was fascinated by the jellyfish. He realized the pumping motion a jellyfish makes was reminiscent of a beating heart and wondered if he could make an artificial "jellyfish" with heart cells.
He made a simple silicone mold shaped like a jellyfish, embedded heart cells in it, and controlled it with electrical current. He got further inspiration from a second trip to the aquarium, watching a stingray’s fluid movements after his daughter touched one. Then remembering how he used to guide her on walks with a laser pointer — she'd jump on the beam when it hit the sidewalk — he had an idea for light as a novel control mechanism. Four years on, combining progress from the jellyfish experiment, stingray anatomy, and light to control movement — we now have his biohybrid ray.
In the end, Parker is still after an artificial heart and these experiments are steps in that direction.
“Everyone is going to see something different,” muses Parker. “I’m looking at it and I’m trying to understand the heart — and impress my 7-year-old daughter.”
Image courtesy of Captain DJ on Flickr