Oligomodal Mechanical Metamaterials

Mechanical metamaterials are artifical composites that exhibit a wide range of advanced functionalities such as negative Poisson's ratio, shape-shifting, topological protection, multistability, extreme strength-to-density ratio and enhanced energy dissipation. To date, most metamaterials have a single property, e.g. a single shape change, or are pluripotent, i.e. they can have many different responses, but require complex actuation protocols. Here, we introduce a novel class of oligomodal metamaterials that encode a few but fixed number of distinct properties that can be selectively controlled under uniaxial compression. In particular, we realise a metamaterial that has a negative (positive) Poisson's ratio for low (high) compression rate. The ability of our oligomodal metamaterials to host multiple mechanical responses within a single structure makes them an early example of multi-functional matter and paves the way towards robust and adaptable devices.