Embodying mechano-fluidic memory in soft machines to program behaviors upon interactions

Animals show richness in adopted behaviors, which are programmed based on interactions with the external world. For instance, the nematode Caenorhabditis elegans switches between fundamental locomotion modes, such as moving straight and steering, based on the history of external cues and the current surroundings. Soft machines already show feats of passive deformation to external cues. Could a soft machine also remember past interactions using its body, without a processor? We harness the bistability of elastic shells to embody mechano-fluidic memory in soft machines. By storing information of past cues from the external world in their physical body, the machines program new stable locomotion behaviors. When provided with antennae where soft tubes kink and unkink, the machines with embodied memory can detect and avoid obstacles in unknown environments by switching between moving straight and steering, all without software or processors. Embodied memory opens the door to robust, autonomous behaviors that are fully embedded in the nonlinear mechanical structure the machines are made of, for applications ranging from responsive microrobots to reliable space exploration in harsh weather.