Weird robot uses rat cells

A new robot stingray can swim with help from an unexpected source: muscle cells that were taken from rat hearts, a new study finds. Understanding how to build machines from heart cells could lead to scientists being able to build entire living artificial hearts from muscle cells that would act more like natural hearts, the researchers said. Stingrays and related fish have flat bodies with long wing-like fins. These fins undulate in waves that ripple from the front of the fins to the back, energy-efficient motions that help these fish glide through water. Researchers sought to build a robot that emulates the stingray's efficiency and maneuverability.