New Robot Stingray Is Part Biological -- It's Powered by Living Heart Cells

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. Using a technique called optogenetics, the heart cells are genetically modified to contract when they're hit with a beam of light.