Temperature-switchable metamaterials

We designed metamaterials whose mechanics reconfigure with temperature alone, with no actuators, power, or electronics, by combining two polymers whose stiffness contrast collapses on heating. A multi-material topology-optimization algorithm finds the two-phase layout that realizes a prescribed pair of behaviors, one cold and one warm, which is then printed directly. This yields temperature-switchable cushioning, lattices whose effective Poisson's ratio reverses sign between cold and warm, and cubes that switch their axis of expansion. Encoding the response in geometry makes the material its own sensor and actuator; the work was featured on the cover of Science Advances.