## 3 Bio-Inspired Application Prospects
The relaxed state on the left side corresponds to a splay molecular alignment, while the bent state on the right side corresponds to the photothermally deformed LCG construct with disordered molecules. (**C**) The chemical structure of mesogenic monomers and the photothermal agent used to realize the light-fueled deformation of liquid crystalline networks (LCNs) and liquid crystalline gels (LCGs); X represents the amount of the 5 CB added to the original LCN precursor mixture in weight percentage. Adapted with permission from Reference [81], National Academy of Sciences of the United States of America, 2020.  
exposing to light. The most commonly observed phototropic plant; sunflower (_Helianthus annuus_) is the best example, which effectually responds to sunlight with mechanical motion [74; 75; 83]. Concerning the extendable durability, recently fluorinated azobenzene molecules [_ortho_-Fluorozobenzene-(F-azo)] are synthesized and their remarkable stability was reported [84; 85; 86]. Excluding ultraviolet light stimulated photoisomerization, these F-azo compounds tune their transition from _trans_ to _cis_ form in visible wavelengths. [PERSON] et al. designed LC soft actuators with appropriate doping of F-azo-2 (Figure 13c) in addition to LC monomers and crosslinkers. The constructed films demonstrated their ability to self-propelling oscillatory motion upon sunlight exposure, as shown in Figure 13d [87]. Designing light-responsive soft actuators is quite challenging because the selection of materials for device applications involves the understanding of the inherent properties of chosen material. Many factors are to be considered for suitable importunities, such as response time, reversibility, cyclic stability, elastic modulus, etc., of used materials. Figure 13: (**a–c**) Chemical structures of F-azo compounds, (**b**) Schematic illustration of the conversion of sunlight into electric power by combining a solar actuator made of supramolecular film (composed of F-azo-1, hydrogen bonded with agarose polymer matrix) with a piezoelectric transducer. The piezoelectric transducer is polyvinylidene diffiude (PVDF). The bending of the actuator under solar irradiation leads to bending of the piezoelectric transducer and subsequent generation of electricity. Adapted with permission from Reference [82], The Royal Society of Chemistry, 2018, (**d**) Series of photos portraying self-oscillatory motion of the liquid crystalline (LC) film (made of F-azo-2 and other LC monomers) during sunlight exposure. Adapted with permission from Reference [87], Springer Nature, 2016. In addition to LC materials, shape-memory materials (SMMs) and polymer gels plays a significant role in designing light-driven actuators made of soft elastic materials [88]. In order to improve the response time of gel-type actuators driven by light, [PERSON] et al. [89] and [PERSON] et al. [90] reported curdlan polymer gels with host-guest interactions (such as a linear high molecular-weight \(\beta\)-1,3-glucan, decorated with \(\alpha\)-cyclodextrintrins (\(\alpha\)-CDs) as hosts and a poly(acrylic acid) with azobenzene pendants as guests). The works reported by [PERSON] and coworkers involve the design strategy of covalently crosslinked poly-acrylamides decorated with both host \(\alpha\)-CDs and azobenzene moieties [91]. These novel supramolecular gel materials are significant in performing reversible photo-deformation for many successful cycles and with fast response time (<1 s) Consequently, these supramolecular gel-actuators are fascinating and systems thereof suitable for artificial robots that can promisingly perform biomimicking sensitive gesticulations. Apart from azobenzene chromophores, some modified cyanine dyes and coordination complexes thereof can also have light absorption properties [92]. These dye-doped LCE systems can tune the material properties by synergic chemical bond interaction.