Technical Papers and Presentations

A millimeter-scale soft crawling robot is demonstrated that uses a similar mechanism to move efficiently in a variety of configurations: on horizontal, vertical, as well as upside-down surfaces; on smooth and rough surfaces; and through obstacles comparable in size to its dimensions. The traveling deformation of the robot soft body is generated via a local light-induced phase transition in a liquid crystal elastomer and resembles the pedal waves of terrestrial gastro pods. We report a natural-scale soft caterpillar robot based on an optomechanical liquid crystalline elastomer monolith. The robot’s body is made of a light sensitive elastomer strip with patterned molecular alignment that enables us to drive travel ling deformations by sequential, nonreciprocal illumination. By controlling the travelling deformation pattern the robot exhibits different gaits while walking on horizontal surfaces. The simulation results demonstrated how the local increase in temperature decreased the molecular order in the elastomer and thus generated the traveling deformation. We demonstrate how a traveling deformation, induced in a liquid crystal polymer ring by a spatially modulated laser beam, can be used to drive the ring (the rotor) to rotate around a stationary element (the stator), thus forming a light-powered micromotor.

The finite element numerical simulations of the rotor ring deformation dynamics were performed using the Solid Mechanics Module, Comsol. In the model, laser illumination locally raises the temperature of the LCE ring and thus reduces the liquid crystal order, causing the ring to contract along the local director, at the same time swelling in the perpendicular dimensions. The photo-mechanical deformation is modeled by introducing a local photo-strain tensor into the stress–strain constitutive relation. A linear or nonlinear constitutive relation can be assumed depending on the limit considered. When a nonlinear, say Neo Hookean model is applied, more complex phenomena with director reorientation can be simulated. Comsol proves successful in reproducing a snail, caterpillar, rotating motor robot respectively, in good agreement with physical experiment.