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Patterned shape changes in liquid crystal elastomers: when the material is the machine

Liquid crystal elastomers are a remarkable new class of active soft solid, often advertised as artificial muscles. This name arrises because LCEs reversibly elongate and contract, often by hundreds of percent, when they go through a solid-solid phase transition from isotropic to aligned. This transition can be tuned to occur around room temperature, or can be driven by illumination. Recently, experimentalists have learnt to 3-D print LCE structures in which this elongation can be patterned so that, at each point in the structure, it points in any desired direction. Upon heating/illumination, these 3-D structures will morph into entirely different shapes. Such shape-morphing via patterned shape-change is common in biology, where complex shapes arise via patterned growth during development and are actuated by patterns of muscular contraction to drive the key processes of life, including digestion, locomotion, and respiration, but is novel in human science and technology. In this project, we will develop a numerical platform to design and analyze LCE structures with patterned elongations, learning the basic vocabulary of effects achievable by patterning shape changes into materials. Specifically, we will use our code to design soft machines, including heart like soft pumps, snapping shells and non-inertial oscillators. We will work closely with experimentalists in th US, who will fabricate and test our designs.