Inspired by the impulsive movements in plants, this research investigates the physics of a novel fluidic origami concept for its pressure-dependent multistability. In this innovation, fluid-filled tubular cells are synthesized by integrating different Miura-Ori sheets into a three-dimensional topological system, where the internal pressures are strategically controlled similar to the motor cells in plants. Fluidic origami incorporates two crucial physiological features observed in nature: one is distributed, pressurized cellular organization, and the other is embedded multi-stability. For a single fluidic origami cell, two stable folding configurations can coexist due to the nonlinear relationships among folding, crease material deformation and internal volume change. When multiple origami cells are integrated, additional multi-stability characteristics could occur via the interactions between pressurized cells. Changes in the fluid pressure can tailor the existence and shapes of these stable folding configurations. As a result, fluidic origami can switch between being mono-stable, bistable and multi-stable with pressure control, and provide a rapid 'snap-through' type of shape change based on the similar principles as in plants. The outcomes of this research could lead to the development of new adaptive materials or structures, and provide insights for future plant physiology studies at the cellular level.

We report a unique collapse mechanism by exploiting the negative stiffness observed in the folding of an origami solid, which consists of pressurized cells made by stacking origami sheets. Such a collapse mechanism is recoverable, since it only involves rigid folding of the origami sheets and it is programmable by pressure control and the custom design of the crease pattern. The collapse mechanism features many attractive characteristics for applications such as energy absorption. The reported results also suggest a new branch of origami study focused on its nonlinear mechanics associated with folding.

This research investigates the nonlinear pressure-induced stiffness characteristics of an origami structure associated to its large amplitude folding. Such structure consists of origami tubes that are formed by stacking and connecting Miura-Ori sheets along their crease lines, so that one can apply pressure to achieve autonomous folding and generate stiffness. We show that the stacked origami can exhibit two unique stiffness characteristics due to the nonlinear relationships between the internal pressure and folding deformation, as well as the interactions between pressurized tubes. One characteristic is negative stiffness, and the other is quasi-zero stiffness (QZS). Both of these stiffness characteristics are programmable by tailoring the Miura-Ori crease design, and controllable by adjusting the pressurization. This research would uncover the physical principles behind these stiffness characteristics, provide design guidelines, and discuss the potentials of developing the stacked origami into an adaptive structure with multiple and embedded dynamic functionalities.