Responsive and Foldable Soft Materials

Stimulus-responsive soft materials that can enable folding of a 2D sheet into a 3D object have potential significant applications, including wearable electronics, biomimetic machines, soft robotics, drug delivery, biomedical devices, and responsive buildings. The responses can be tuned by the materials chemistry, composition, and type of external stimulus; the direction and magnitude of the deformation can be varied by geometric design and incorporation of nonresponsive materials and nanofillers. In this review, we overview different types of responsive materials (e.g., responsive hydrogels, shape memory polymers, liquid crystal elastomers, and polymer composites) and some of the basic folding mechanisms. We highlight the required material properties, fabrication techniques, and structural designs for desirable folding structures.