Optical Fiber Waveguiding Soft Photoactuators Exhibiting Giant Reversible Shape Change

Abstract

Soft actuators, an emerging field in robotics, have great potential for wide‐ranging applications in biology, medicine, engineering, and oceanography. Photoactuators that are stimulated by light to produce reversible mechanical deformation have attracted significant interest in recent years owing to their advantages of high resolution, fast switching, flexible controllability, and electromagnetic interference immunity. Conventional photoactuators rely on free‐space illumination, which limits the control in light‐obstructed surroundings. A low loss optical fiber waveguide‐based soft photoactuator composed of photothermally responsive material hinges and high‐transparency elastomer fiber arms is proposed. When light travels in the elastomer fiber arms, the hinges exhibit a very large shape change so that the arms bend by themselves, with a maximum repeatable bending angle of approximately 145°. The angle is determined by the injected optical power. A fiber photoactuator with dual hinges is designed that is capable of reversible complex deformation. Moreover, in a narrow silicone tube, the fiber photoactuator can still be stimulated with considerable deformation by the light injected along the fiber. A fiber photoactuator‐constructed microhook is demonstrated for grabbing object in water.

Rapidly responsive liquid metal/polyimide photothermal actuators designed based on the bilayer structure difference in coefficient of thermal expansion

“…The bending angle increased approximately linearly with the increase of power, and a linear fit was performed. The LM/PI photothermal actuator responds rapidly, the LM/PI-8% photoactuator bends 60.161 in 2.75 s and the bending speed reaches 21.891 s À1 , which exceeds that of most of the reported photoactuators, [39][40][41][42][43][44][45][46][47][48][49][50][51] as shown in Fig. 5g and h.…”

Photomotion of Hydrogels with Covalently Attached Azo Dye Moieties—Thermoresponsive and Non-Thermoresponsive Gels

“…Photoactuated polymer-based hydrogels are water-swollen networks with macromolecular chain segments that experience mechanical deformation under light irradiation. The photoactuation of these systems can be traced to essentially two mechanisms: A photothermal mechanism, in which, e.g., embedded nanoscaled materials serving as absorbers are heated by light and act on either elastomers or thermoresponsive polymers [ 1 , 2 , 3 ], or a photochemical mechanism, in which dyes such as spiropyranes, hexaarylbiimidazoles, and azobenzenes lead to deformation upon light-induced changes in their molecular structure [ 4 , 5 ].…”

Recent advances in photoresponsive fluorescent materials based on [2+2] photocycloaddition reactions

“…14–16 Among the various external stimuli, light is an ideal source with a high spatial and temporal resolution, clean, easy access, and simple operation. 17 Functional materials can spontaneously undergo structural transformations between at least two conformations through light-induced reversible or irreversible photochemical reactions with changes in physical properties such as viscosity, 18–20 shape, 21–24 fluorescence intensity, and colour 25–28 when irradiated by the light of a specific wavelength.…”

“…[14][15][16] Among the various external stimuli, light is an ideal source with a high spatial and temporal resolution, clean, easy access, and simple operation. 17 Functional materials can spontaneously undergo structural transformations between at least two conformations through light-induced reversible or irreversible photochemical reactions with changes in physical properties such as viscosity, [18][19][20] shape, [21][22][23][24] fluorescence intensity, and colour [25][26][27][28] when irradiated by the light of a specific wavelength. Among all response signals, fluorescent signals are increasingly gaining popularity in the research of light-stimulated responsive materials due to their designability, high sensitivity, and instantaneous visual feedback.…”