Bio-inspired pneumatic shape-morphing elastomers

Abstract

Shape-morphing structures are at the core of future applications in aeronautics 1 , minimally invasive surgery 2 , tissue engineering 3 or smart materials 4. Current engineering technologies, based on inhomogeneous actuation across the thickness of slender structures, are however intrinsically limited to one-directional bending 5. Here, we describe a strategy where mesostructured elastomer plates undergo fast, controllable and complex shape transformations under applied pressure. Similarly to pioneering techniques based on soft hydro-gel swelling 6-10 , these pneumatic shape morphing elastomers, termed here as baromorphs, are inspired by the morphogenesis of biological structures 11-15. Geometric restrictions are overcome by controlling precisely the local growth rate and direction through a specific network of airways embedded inside the rubber plate. We show how arbitrary 3D shapes can be programmed using an analytic theoretical model, propose a direct geometric solution to the inverse problem and illustrate the versatility of the technique with a collection of configurations.

Programming curvilinear paths of flat inflatables

“…tension field theory | wrinkling instability | programmable structures A domain of application for pneumatic structures has emerged with the current development of soft robotics actuators (1). Unidirectional bending of elastomeric pneumatic structures can be easily controlled by internal pressure (2), and recently, more general complex shape morphing was achieved (3). As they rely on large material strains, these structures are based on elastomers and therefore, have a relatively low stiffness, which makes them unsuitable for large-scale structures and heavy loads.…”

Moulding three-dimensional curved structures by selective heating

“…The fact that the constant γ is not zero imposes limitations on what can be molded. For the metric mold-ing and distance molding methods, the molding function ϕ : D → M needs to satisfy certain inequalities (namely (16), (26), and (33)) which have the generic form minimum multiplier maximum multiplier ≥ γ,…”

Gait-optimized locomotion of wave-driven soft sheets

“…4 Crawling has the advantage over traditional mechanical systems of being highly adaptable against changing terrain, and it requires far fewer specialized parts than a multipedal system. [5][6][7][8][9] Until recently, most research on the topic has focused on slender designs inspired by the peristaltic motions found in snails, worms, and certain snakes. 10,11 Locomotion of active solids in one dimension has been studied extensively in the context of swelling gels, shape memory polymers, or dielectric and ferromagnetic materials.…”