Many species can dynamically alter their skin textures to enhance their
motility and survivability. Despite the enormous efforts on designing
bio-inspired materials with tunable surface textures, developing
spatiotemporally programmable and reconfigurable textural morphing
without complex control remains challenging. Here we propose a design
strategy to achieve metasurfaces with such properties. The metasurfaces
comprise an array of unit cells with broadly tailored temporal
responses. By arranging the unit cells differently, the metasurfaces can
exhibit various spatiotemporal responses, which can be easily
reconfigured by disassembling and rearranging the unit cells.
Specifically, we adopt viscoelastic shells as the unit cells, which can
be pneumatically actuated to a concave state, and recover the initial
convex state some time after the load is removed. We computationally and
experimentally show that the recovery time can be widely tuned by the
geometry and material viscoelasticity of the shells. By assembling such
shells with different recovery time, we build metasurfaces with
pre-programmed spatiotemporal textural morphing under simple pneumatic
actuation, and demonstrate temporal evolution of patterns, such as digit
numbers and emoji, and spatiotemporal control of friction. This work
opens up new avenues in designing spatiotemporal morphing metasurfaces
that could be employed for programming mechanical, optical and
electrical properties.
Corresponding author: Lihua Jin, Email:
[email protected]