Morphogenetic Metals through Topology-Driven Stiffness Changes and Electrochemical Activation.

Morphogenesis enables the adaptive capabilities of living organisms and has been realized in soft materials that heal, change stiffness, and grow. Metals, despite their importance, do not have the tools to enable morphogenesis near ambient temperatures because metal atoms require intense temperatures and energy to move. This paper reports a method for reversibly controlling the physical properties of metal lattices with minimal energy, power, and material input through electrochemically activated topology changes. Switching between two topological states in individual cells enables programmable material moduli between 1.1 MPa and 2.6 GPa. The room temperature electrochemical morphogenesis is reversible and provides in situ phase control of a vibrating mass. A topology optimization technique that solves for two extreme topologies with minimal change in part volume realizes metamaterials that switch between negative and positive Poisson's ratios. The presented approaches for changing mechanical properties through topology provide a new path for endowing metals with the adaptive characteristics of organisms.