Accelerating the stimuli-responsive bending of a gel using mechanical constraints.

Gel bends in response to external stimuli, which has important technical applications ranging from artificial muscle to drug delivery. Here, we predict a simple and effective method to accelerate the bending of gel using mechanical constraints. We propose an exact theory of the bending dynamics of gel, which gives analytical solutions for the time evolution of the gel curvature and the relaxation time with which the system approaches to its final equilibrium state. The theory shows that the relaxation time of a slender gel confined between two parallel and rigid plates is smaller than it of a free gel with no constraints, indicating that gel bends faster when swollen in the direction parallel to the two confined plates by adding more mechanical constraints. The advantages of this new method is no need to change the microstructure and components of gel itself as previous methods. This finding brings valuable approach in designing soft robotics and healthcare devices, and is subject to experimental test.