Metal metamaterials with electrochemical activation

Morphogenesis enables the adaptive ability of living organisms, and artificial materials inspired by morphogenetic features have been extensively explored, including metamaterials, which can modulate their mechanical properties. However, morphogenetic metal remains a challenge due to its low diffusivity at room temperature. In this work, we present a novel method for electrochemically activating the topology of metal lattices, which can switch their modulus and Poisson's ratio. Our stainless steel rectangular lattice can reversibly modulate its modulus between 1.1 MPa and 2.6 GPa for 200 cycles. We also achieve mechanical metamaterials that switch between negative and positive Poisson's ratio through topology optimization. In addition, we envision this topological change to endow metals with the flexible characteristics of organisms and advance applications of multi-functional devices.