Light activated non-reciprocal motion in liquid crystalline networks by designed microactuator architecture

Abstract

Light responsive liquid crystalline networks were prepared by photopolymerization of azobenzene-doped mesogen mixtures and applied for production of micro-actuators by a laser writing technique. Adjusting the cross-linker content was found to be an efficient and easy way to control the dynamics of lightinduced deformation from the micro- up to the macro-meter length scales. Starting from a complete characterization of the response of millimeter-sized stripes under irradiation with different sources (LED and laser light), micro-structures based on different monomer mixtures were analyzed for micro-actuator preparation. Double stripes, able to perform a light driven asymmetric movement due to the different mixture properties, were created by a double step process through a laser writing system. These results are a simple demonstration of an optically activated non-reciprocal movement in the microscale by a chemical material manipulation. Moreover, we demonstrate a rapid actuator dynamics that allows a movement in the second time scale for macrostructures and a millisecond actuation in the microscale

An Autonomous Soft Actuator with Light‐Driven Self‐Sustained Wavelike Oscillation for Phototactic Self‐Locomotion and Power Generation

“…They prepared light‐responsive LCNs by the photopolymerization of azobenzene‐doped mesogen mixtures and controlled the light response by adjusting the cross‐linker content. Based on these, different LCN stripes were integrated into a monolithic actuator that was deformed with different velocities at the two ends, resulting in nonreciprocal movements, applicable in complex robotic structures such as microswimmers 68. However, up to now, the realization of phototactic locomotion in an artificial soft robot in air remains rare.…”

Advances in Cell Scaffolds for Tissue Engineering: The Value of Liquid Crystalline Elastomers

“…Subsequently, the laser focal spot is scanned by moving the sample in all the three dimensions by a piezoelectric translation stage, thus creating point by point the computer designed 3D structure (Figure d). The technique also allows one to obtain microstructures integrating different alignments, to integrate LCE with different mechanical properties and to create suspended elements with resolution up to 160 nm …”

“…[29] On the other hand, the polymers obtained are generally in the glassy statea tr oom temperature, with higherg lass transition temperatures (Tg) and elastic modulus with respectt ot he polysiloxane LCEs, and, for theser easons, they are generally called LCNs insteado fL CEs. However,m echanical properties can be adjusted by modifying the monomer mixture composition, for example, the elastic modulus can be decreased by decreasingt he crosslinker content, [34] resulting in materials with elastic behaviour at reasonable temperatures.…”

“…Subsequently,t he laser focal spot is scanned by movingt he sample in all the three dimensions by ap iezoelectric translation stage, thus creating point by point the computer designed 3D structure (Figure 6d). The technique also allows one to obtain microstructures integrating different alignments, [55] to integrate LCE with different mechanical properties [34] and to create suspendede lementsw ith resolution up to 160 nm. [56] Moving to biodegradable polyester based LCEs, different 3D scaffolds have been prepared through dissolution of the starblock copolymer in as olvent followed by molding on customized 3D templates.After solventr emoval and crosslinking completion, templater emoval results in 3D scaffolds showinga complementary morphologyw ith respect to the templates.…”

Light‐Responsive Shape‐Changing Polymers

“…The fabrication of miniaturized soft swimming robots with complex movements is of great interest for the soft robotic field. Here, LCP materials could be used for light‐driven actuation of the microbots . As shown by Fischer and co‐workers, soft swimming microbots composed of LCEs can be driven by structured monochromatic light to perform complex biomimetic motions (Figure c) .…”