title: Programmable snapping composites with bio-inspired architecture.
abstract: The development of programmable self-shaping materials enables the onset of new and innovative functionalities in many application fields. Commonly, shape adaptation is achieved by exploiting diffusion-driven swelling or nano-scale phase transition, limiting the change of shape to slow motion predominantly determined by the environmental conditions and/or the materials specificity. To address these shortcomings, we report shape adaptable programmable shells that undergo morphing via a snap-through mechanism inspired by the Dionaea muscipula leaf, known as the Venus fly trap. The presented shells are composite materials made of epoxy reinforced by stiff anisotropic alumina micro-platelets oriented in specific directions. By tailoring the microstructure via magnetically-driven alignment of the platelets, we locally tune the pre-strain and stiffness anisotropy of the composite. This novel approach enables the fabrication of complex shapes showing non-orthotropic curvatures and stiffness gradients, radically extending the design space when compared to conventional long-fibre reinforced multi-stable composites. The rare combination of large stresses, short actuation times and complex shapes, results in hinge-free artificial shape adaptable systems with large design freedom for a variety of morphing applications.
authors.affiliation: Laboratory of Composite Materials and Adaptive Structures, Department of Mechanical and Process Engineering ETH Zürich, Zürich 8092, Switzerland. Authors contributed equally.
authors.forename: Jascha U
authors.initials: JU
authors.lastname: Schmied
authors.forename: Hortense
authors.initials: H
authors.lastname: Le Ferrand
authors.forename: Paolo
authors.initials: P
authors.lastname: Ermanni
authors.forename: André R
authors.initials: AR
authors.lastname: Studart
authors.forename: Andres F
authors.initials: AF
authors.lastname: Arrieta
mesh_terms: D000222:Adaptation, Physiological; D016880:Anisotropy; D040761:Biomimetic Materials; D031257:Droseraceae / Q000033:anatomy & histology* / Q000502:physiology*; D004867:Equipment Design; D009068:Movement; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000502:physiology*; D018521:Plant Physiological Phenomena