Origami and kirigami inspired self-folding for programming three-dimensional shape shifting of polymer sheets with light

Origami and kirigami guided programmable shape shifting is explored via self-folding and spontaneous buckling of a thin sheet of shape memory polymer with light. By patterning the sheet with printed black ink lines as actuating hinges, we show that the folding angle can be well controlled by tuning the ink line width, which is predicted by both a simplified localized bilayer folding model and corresponding finite element method (FEM) simulation. Inspired by the approach of paper origami and kirigami combining folding and cutting, we then explored the design of prescribed patterned creases (i.e. ink lines) and/or cuts in the polymer thin sheet for programming a library of light-responsive three-dimensional (3-D) surfaces in a controlled fashion. Through the design of prescribed straight and curved crease patterns in origami, we demonstrated the generation of light-driven self-folding cylinders, helices, and pyramids with zero Gaussian curvature, as well as spontaneous formation of saddles with negative Gaussian curvature through localized curved folding induced global buckling. The quantitative underlying mechanism governing the geometry of the different self-folded 3-D structures is revealed through simple geometrical modeling and FEM simulations. Lastly, through kirigami combining both folding and cutting in the form of line cuts or cut-outs, we demonstrated the spontaneous formation of light-responsive, more complex pop-up kirigami structures.