Water-Responsive Shape-Memory Origami Enabled by a Washi–Bulk pNIPAAm Hydrogel Hybrid Sheet
Year: 2026
Type: preprint
Abstract: Origami transforms two-dimensional sheets into complex three-dimensional forms through folding and has evolved from a traditional art into a versatile design principle for deployable and reconfigurable structures. Here, we develop a water-responsive shape-memory origami sheet by combining highly concentrated poly(N-isopropylacrylamide) (bulk pNIPAAm) hydrogel with Japanese kozo paper. Bulk pNIPAAm undergoes pronounced hydrationinduced softening and recovers its permanent shape upon rehydration, whereas the paper scaffold enables the hydrogel to be fabricated and handled as a thin, foldable sheet. Rather than programming only individual active creases, the hybrid sheet allows complex folded three-dimensional configurations to be programmed directly as permanent shapes. Two complementary programming strategies are demonstrated: photopolymerization of precursorimpregnated paper in a pre-folded configuration and post-fabrication programming by local photopolymerization at selected creases. Kozo washi-based hybrid sheets exhibited more than 90% recovery within several seconds in a simple folding test, and Miura-fold, crane, dolphin, and kirigami structures recovered their memorized geometries after unfolding and dehydration-induced temporary fixation. Finally, simply pouring warm water onto a flowershaped structure triggers spontaneous blooming without full immersion. This approach transforms a bulk shape-memory hydrogel into a fold-programmable sheet material and
Source: ChemRxiv
Authors: Kohei Murata, Hiroaki Suzuki
Institution: Chuo University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7220849327