Figure 4 from From Light-Powered Motors, to Micro-Grippers, to Crawling Caterpillars, Snails and Beyond—Light-Responsive Oriented Polymers in Action | Semantic Scholar (2024)

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Recent progress in soft microrobotics is highlighted based on light-responsive liquid-crystal elastomers and polymer networks, focusing on photomobile devices such as walkers, swimmers, and mechanical oscillators, which may ultimately lead to flyingmicrorobots.

The elastomer growth technique readily offers micrometer-scale, remotely controlled functional structures with different modes of actuation as building blocks for the microtoolbox.

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 propulsion mechanisms and motion behaviors of the so far developed light-driven MNMs are illustrated in detail involving light-induced phoretic propulsion, bubble recoil and interfacial tension gradient, followed by recent progress in the light- driven movement of liquid crystalline elastomers based on light- induced deformation.

A centimeter-scale light-powered linear inchworm motor, driven by two liquid crystal elastomer (LCE) accordion-like actuators, demonstrating how LCE light-driven actuators with a limited stroke can be used to drive more complex mechanisms, where large displacements can be achieved.

New sophisticated motions of LCEs and their composite materials are demonstrated, including a first lightdriven plastic motor with laminated films composed of an LCE film and a flexible polyethylene (PE) sheet, leading to a reversible deformation of L CEs containing azobenzene chromophores just by changing the wavelength of actinic light.

The photo-mechanical response of a linear light-driven LCE actuator is characterized by measuring its response to laser beams with varying power, pulse duration, pulse energy, and the energy spatial distribution.

This tutorial review includes an introduction to liquid crystal (LC)-based materials and highlights developments in light-responsive LC polymers, shape programmability and sustained motions to finally achieve bioinspired untethered soft robots able to perform locomotion and tasks.

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