Photo-Motile Structures

TL;DR

This paper introduces a modeling framework for light-induced actuation in soft robotics, highlighting how coupling between light absorption and deformation can generate cyclic motion, enabling remote and efficient actuation.

Contribution

It presents a novel modeling approach and examples demonstrating cyclic motion through light-structure coupling, advancing light-based actuation methods in soft robotics.

Findings

Coupling between light absorption and deformation enables cyclic motion.

Steady illumination can produce periodic actuation.

Light-induced actuation can be achieved with simple models.

Abstract

Actuation remains a signifcant challenge in soft robotics. Actuation by light has important advantages: objects can be actuated from a distance, distinct frequencies can be used to actuate and control distinct modes with minimal interference and signifcant power can be transmitted over long distances through corrosion-free, lightweight fiber optic cables. Photo-chemical processes that directly convert photons to configurational changes are particularly attractive for actuation. Various researchers have demonstrated light-induced actuation with liquid crystal elastomers combined with azobenzene photochromes. We present a simple modeling framework and a series of examples that studies actuation by light. Of particular interest is the generation of cyclic or periodic motion under steady illumination. We show that this emerges as a result of a coupling between light absorption and deformation. As the structure absorbs light and deforms, the conditions of illumination change, and this in turn changes the nature of further deformation. This coupling can be exploited in either closed structures or with structural instabilities to generate cyclic motion.