Thin Bistable Valves for Origami Robots

Overview

Pneumatic actuation naturally complements origami-inspired robots, but onboard fluidic control remains elusive: conventional valves are bulky, while custom soft or microfabricated options trade off flow capacity, pressure range, manufacturability, and system integration. This work presents a family of thin, layered bistable pneumatic valves designed to be embedded directly within origami-inspired structures.

The valves integrate a compliant serpentine double-beam bistable mechanism (3D-printed in low-creep TPU), SMA coil-spring actuators, and embedded pneumatic channels inside a laminated fiberglass body. A brief electrical pulse snaps the mechanism between its two stable states; the valve then remains mechanically latched with zero holding power.

Key results

• The 2/2-way valve is 2.9 mm thick and reaches 5150 sccm at 310 kPa; the 3/2-way valve is 3.0 mm thick and reaches 1520 sccm at −88 kPa for vacuum operation.
• At 3.0 mm or less in thickness, the valves are roughly 25% thinner than the most compact commercial miniature valve identified in our survey, and comparable to the smallest fully packaged MEMS gas microvalve, while avoiding wafer-level fabrication.
• An analytical strain-energy model, finite element analysis, and experiments characterize the bistable snap-through response, and a 1000-cycle lifetime test shows stable switching with leakage that does not degrade over the tested range.

Demonstrations

The valves are demonstrated in three origami-inspired robotic systems: a multi-module Kresling manipulator that performs pick-and-place through a single shared vacuum line and lifts a 500 g payload; an active hinge panel (3.1 mm thick) whose pouch actuator lifts a 100 g payload within 7 s; and a self-sensing Waterbomb pneumagami module that achieves three-degree-of-freedom shape reconfiguration from a single pressure input.