reference: A Bio-Hybrid Stingray Robot Powered By Rat Muscle, Kit Parker, Harvard University's Department of Bioengineering and Applied Sciences, 2016
A Bio-Hybrid Stingray Robot Powered By Rat Muscle
Animating each ray are about 200,000 heart cells harvested from 2-day-old rat embryos and placed on top of the silicone. The silicone bears a template consisting of an extracellular protein, fibronectin, which guides the growth of the cells into a radiating pattern similar to the muscles in the real ray.
Real rays have two sets of muscles within each pectoral fin, pulling in opposite directions to move a fin down, then up. The ray robot has just one set of muscles, which bend the fins downward; the spring action of the gold skeleton pulls the fins back up.
Infected with a virus that delivers the gene encoding the optogenetic molecular switch, the modified cardiac cells twitch when blue light shines on them. But translating that effect into coherent motion took months of tweaking; simply getting a robot ray to move forward when light stimulated the front of its fin took Park 200 tries. Ultimately, he built 100 more robots and showed they could navigate underwater obstacle courses. To negotiate turns, Park guides a ray with two light sources, one pointed at each fin. Changing the frequency of the light slows or speeds up the contraction rate; by making one side beat faster than the other, he steers the robot left or right.
The rays move only about 9 meters per hour and turn slowly (more on: http://www.sciencemag.org/news/2016/07/robotic-stingray-powered-light-activated-muscle-cells)
These muscles would allow the fins to flex downward, but to ensure they would return to the starting position, the team reverse-engineered a stingray's physiology to create a skeleton made of gold. Because, Parker says, "Cells like gold, just like people do." A final layer of polymer, and the biohybrid stingray was complete. At just 16 millimeters long, and weighing just ten grams, the tiny robot looked a little like a transparent coin with a tail. (more on: http://www.popsci.com/soft-robotic-stingray#page-4 )
The robotic stingrays are made in four layers on a titanium mold. A stretchy polymer layer is laser cut into the stingray shape, followed by a thin gold skeleton. This is covered with a second stretchy layer before the heart muscle cells are seeded.
When the heart muscle cells are activated, the signal to contract spreads down the cells in a line. Park aligned the cells he obtained from a rat heart in a serpentine zig-zag pattern along the fins of the stingray. This allows the fins to move in wavelike undulations as the contraction spreads from front to rear. (more on: https://www.technologyreview.com/s/601834/robotic-stingrays-made-with-rat-heart-algae-and-plastic-fins/)
Comments
Post a Comment