Scientists have created a cyborg stingray that is powered by living rat heart cells. The toenail-sized robot, which can be guided by pulses of light and can sail smoothly through the water, may pave the way toward the development of better medical devices such as artificial hearts.
The heart and a stingray may appear to be different, but both have to overcome challenges that involve fluid and motion.
Kit Parker from Harvard University's Wyss Institute, who led the team that developed the robotic stingray, explained that, just as a stingray needs to propel itself through the water, the heart also has to propel blood through the circulatory system.
Parker, who got the idea from a stingray in an aquarium he and his daughter visited, said that an artificial heart made from living muscle cells would likely behave more like the natural heart. It may also be able to grow and change over time.
An artificial heart is usually used to bridge the time to a heart transplant or to permanently replace the heart if transplantation is not possible. Artificial hearts save up to three-quarters of patients who wait for transplants.
Previous versions of this artificial organ were more like a mechanical pump, but better artificial hearts could be on the horizon with the development of the robotic stingray.
"The idea is to get a better insight into the human heart and heart disease by reverse engineering other forms of muscular pumps that we see in nature," Parker said.
Parker and colleagues, who reported their work in the journal Science on Thursday, started to build the soft tissue robot by creating charged gold skeleton overlaid with thin layer of flexible polymer.
The researchers also placed a series of heart muscle cells grown from rat embryos on top of the robot. These cells were genetically altered to make the hybrid creature follow a light source.
When exposed to light, the muscle cells caused the robot's fins to contract in a downward motion. When the cells relax, the gold skeleton, which stores some downward energy, pushes the fins back up, resulting in a swimming robot stingray that is guided by a pair of blue lights.
"Optical stimulation induced sequential muscle activation via serpentine-patterned muscle circuits, leading to coordinated undulatory swimming," the researchers wrote in their study.
"The speed and direction of the ray was controlled by modulating light frequency and by independently eliciting right and left fins, allowing the biohybrid machine to maneuver through an obstacle course."
