Modeling Mismatch Strain Induced Self-Folding of Bilayer Gel Structures

When exposed to a solvent, a gel bilayer beam can bend due to different swelling abilities of the two layers. In this work, an analytical model is derived to obtain the curvature of the bilayer beam. The model is further linearized to obtain an explicit expression for the curvature. The finite element model is used to verify the above analytical solutions. The results show the curvature predicted by the analytical model is in excellent agreement with the finite element results. The linear model predicts a smaller curvature at large swelling ratio. These results suggest the analytical models can provide a design metric for self-folding 3D structures.