Reversible Snapping of Constrained Anisotropic Hydrogels Upon Light Stimulations

Area of Science:

• Materials Science
• Soft Robotics
• Biomimicry

Background:

• Nature provides models for rapid actuation, like Venus flytraps and hummingbirds, inspiring artificial "snappers."
• Existing artificial snappers often require physical contact for triggering, limiting their applications.

Purpose of the Study:

• To develop a novel soft actuator capable of rapid snapping triggered by light stimulation.
• To investigate the mechanism and parameters influencing light-induced snapping in a constrained hydrogel.

Main Methods:

• Fabrication of anisotropic poly(N-isopropylacrylamide) hydrogel with oriented nanosheets and gold nanoparticles.
• Utilizing UV light for photopolymerization to fix the ordered structure.
• Clamping gel ends to create a bistable buckle, triggered by laser irradiation for snapping.

Main Results:

• Demonstrated fast snapping behavior in the hydrogel upon laser irradiation.
• Investigated the effect of laser power, irradiation angle, gel thickness, and buckle height on snapping.
• Showcased applications in actuating a plastic bead and controlling a switch state.
• Achieved synergetic and oscillated snapping through controlled laser irradiation.

Conclusions:

• Developed a light-steered, fast-snapping hydrogel actuator.
• The study provides insights into designing soft robots and energy harvesting systems inspired by natural rapid movements.