Bioinspired Stimuli‐Responsive Hydrogel with Reversible Switching and Fluorescence Behavior Served as Light‐Controlled Soft Actuators

Abstract

Stimuli-responsive materials with multiple functions occupy a significant position in the research of bionic artificial intelligence materials. It is a challenge to integrate rapid shape deformation and color change synergistically by a simple method in the same system. Herein, an effective strategy to develop an anisotropic bilayer hydrogel actuator with unified complex deformation and color change is proposed via combining the near-infrared (NIR) light-responsive graphene oxide/poly(N-isopropylacrylamide) (GO-PNIPAM) active hydrogel layer and an UV light-responsive fluorescent poly(acrylic acid [4-(1,2,2-triphenylvinyl)] benzyl ester/N-isopropylacrylamide) passive hydrogel layer. The actuator can undergo light-controlled sapphire fluorescence color change and complex shape deformation simultaneously or separately under light irradiation. It can be remotely manipulated without the requirement for additional reagents, and the irradiation dosage can be accurately modulated through adjusting the irradiation parameters. This work provides new perspectives of intelligent systems with synergistic multiple functions, including smart robots, environmental sensors, and intelligent biomimetic devices.

Graphene oxide composite hydrogels for wearable devices

“…The improvement of mechanical properties of composite hydrogels by GO ensures the application of composite hydrogels in the field of wearable devices, which require materials to respond to environmental stimuli, such as temperature [ 33 , 35 , 43 , 57 , 61 , 62 , 65 , 66 ], pH [ 39 , 40 , 67 ], light [ 68 ] and strain. Environmental stimulation will lead to changes in the structure and properties of matrix polymers.…”

Preparation and characterization of temperature‐responsive Ca–alginate/poly(N‐isopropylacrylamide) hydrogel

“…Up to now, the bending or crawling behaviors of PNIPAm hydrogels have been investigated in depth for multilayer response hydrogels. [44][45][46] However, there is also little attention paid to PNI-PAm hydrogels in the shrinkage deformation of tubular specimens. Moreover, the existence of an inert layer is an important segment to realize these deformation responses for double-or multilayer responsive hydrogels.…”

“…Up to now, the bending or crawling behaviors of PNIPAm hydrogels have been investigated in depth for multilayer response hydrogels 44–46 . However, there is also little attention paid to PNIPAm hydrogels in the shrinkage deformation of tubular specimens.…”

Study on characteristics of the electric‐field‐sensitive hydrogel inspired by jelly in the ampullae of Lorenzini of elasmobranchs

“…Based on different compositions of hydrogels, they are mainly classified into two types of which one consists of natural polymer components such as agarose, alginate, chitosan, gelatin, and so forth, whereas the other consists of synthetic polymer components, for example, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide (PAM) and their co‐polymers 5–11 . To meet actual requirements for applications, hydrogels have been designed and programmed for response to the changes of temperature, pH, light, electric field, magnetic field, and so forth, in surroundings 5,12–15 . Among them, the electric‐field‐sensitive hydrogel makes it true that electrical energy is converted into mechanical energy, and the electric field stimuli are easy to apply and regulate in practice, providing a feasible way to develop intelligent response‐type materials for unprecedented technological breakthroughs.…”

“…[5][6][7][8][9][10][11] To meet actual requirements for applications, hydrogels have been designed and programmed for response to the changes of temperature, pH, light, electric field, magnetic field, and so forth, in surroundings. 5,[12][13][14][15] Among them, the electric-field-sensitive hydrogel makes it true that electrical energy is converted into mechanical energy, and the electric field stimuli are easy to apply and regulate in practice, providing a feasible way to develop intelligent response-type materials for unprecedented technological breakthroughs.…”