Predicting origami-inspired programmable self-folding of hydrogel trilayers

Imitating origami principles in active or programmable materials opens the door for development
of origami-inspired self-folding structures for not only aesthetic but also functional purposes. A
variety of programmable materials enabled self-folding structures have been demonstrated across
various fields and scales. These folding structures have finite thickness and the mechanical
properties of the active materials dictate the folding process. Yet formalizing the use of origami
rules for use in computer modeling has been challenging, owing to the zero-thickness theory and
the exclusion of mechanical properties in current models. Here, we describe a physics-based
finite element simulation scheme to predict programmable self-folding of temperature-sensitive
hydrogel trilayers. Patterning crease and assigning mountain or valley folds are highlighted for
complex origami such as folding of the Randlett’s flapping bird and the crane. Our efforts
enhance the understanding and facilitate the design of origami-inspired self-folding structures,
broadening the realization and application of reconfigurable structures.