Towards photo-induced swimming: Actuation of liquid crystalline elastomer in water
Authors: Cerretti G., Martella D., Zeng H., Parmeggiani C., Palagi S., Mark A.G., Melde K., Qiu T., Fischer P., Wiersma D.
Autors Affiliation: European Laboratory for Non-Linear Spectroscopy (LENS), Universite di Firenze, via Nello Carrara 1, Sesto Fiorentino, 50019, Italy; Dipartimento di Chimica Ugo Schiff, Universite di Firenze, via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy; Istituto Nazionale di Ottica, Consiglio Nazionale Delle Ricerche (INO-CNR), via Nello Carrara 1, Sesto Fiorentino, 50019, Italy; Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart, 70569, Germany; Institut Fur Physikalische Chemie, Universitut Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany
Abstract: Liquid Crystalline Elastomers (LCEs) are very promising smart materials that can be made sensitive to different external stimuli, such as heat, pH, humidity and light, by changing their chemical composition. In this paper we report the implementation of a nematically aligned LCE actuator able to undergo large light-induced deformations. We prove that this property is still present even when the actuator is submerged in fresh water. Thanks to the presence of azo-dye moieties, capable of going through a reversible trans-cis photo-isomerization, and by applying light with two different wavelengths we managed to control the bending of such actuator in the liquid environment. The reported results represent the first step towards swimming microdevices powered by light.
KeyWords: Actuators; Azo dyes; Crystalline materials; Elastomers; Manufacture; Plastics, Chemical compositions; External stimulus; Light-induced; Liquid crystalline elastomers; Liquid environment; Micro robots; Optical energy; Two different wavelengths, Liquids