This is what has fueled development of “soft actuators” that can flex like a bicep and have a fine-tuned sense of touch as in the human hand. Like your stereotypical robot, soft actuators convert energy—such as electricity, heat, or light—into mechanical motion, but they look nothing like the metal and wire constructs that the word “robot” most often evokes. One variety of these soft robots, known as bioactuators, utilizes the functions of living cells to generate motion.