A biomimetic smart kirigami soft metamaterial with multimodal remote locomotion mechanisms

Several efforts have been made to develop walking smart soft robots through different strategies such as the use of complex aligned magneto-active materials. Here, we show a simple approach for the design of a smart soft robot using an elastomer film with randomly distributed ferrimagnetic nanoparticles able to be remotely controlled by a magnetic field. The magneto-active robot has a rotating-square kirigami geometry resulting in a flexible smart auxetic metamaterial (i.e., a negative Poisson-ratio structure). Alongside the standard translational locomotion on a smooth-surface under a steady magnetic force, the auxetic kirigami structure mimics the crawling-locomotion of worms over a high-roughness surface under an oscillatory horizontal field, even climbing vertical-obstacles. A theoretical understanding for this new locomotion mechanism stresses the relevance of the kirigami metamaterial design and the ferrimagnetic response of the particles. The soft robot can also transport a payload having weights higher than the weight of the smart elastomeric film. The smart auxetic structure further presents a rolling locomotion by properly orienting the magnetic field, meaning multiple remote locomotion mechanisms.