Spontaneous snap-through of strongly buckled liquid crystalline networks

Abstract

The field of soft robotics is ever-changing, and substantial effort is allocated towards designing highly versatile and adaptable machines. However, while the soft robots demonstrate exceptional delicacy and flexibility, their ability to release energy in short timescales is rather unremarkable in contrast to their rigid predecessors. One of the routes to remedy that is to utilise mechanical instabilities, which are capable of accumulating substantial amounts of elastic energy and then releasing it in a very short period of time. In this work, we demonstrate a novel design of partially active liquid crystal network strips, which are then mechanically buckled and then snap-through due to the change in temperature. The experimental work combined with the numerical simulations demonstrate remarkable agreement and show different instability modes of various strengths. We provide a fundamental understanding of what governs the modes and how they can be accessed. The strongest mode results in snap-throughs taking as little as 6 ms with peak speeds as high as 60 cm/s for systems only a few millimetres in size.