Fully soft valve for autonomous pressure control

Entirely soft robots require various functional parts made of soft materials. This paper proposes a fully soft valve for autonomous pressure control in soft robots. The valve contains an elastomeric popper which snappily shifts between two stable positions under two critical control pressures -which can vary with respect to the thickness of the popper. As the popper can remain in either position, it acts as a mechanical switch to “open” or “close” the airflow channels in of the valve. Either state (i.e., open or close) can be maintained permanently without further actuation. By optimizing the geometry, the valve functions as a relief valve in a pneumatic circuit. The valve is then used to control the pneumatic pressure in a soft gripper system. When the system pressure is higher than the critical pressure of the valve, the compressed air is relieved through a vent, for the system to remain safe and stable. This work provides a strategy to develop entirely soft components for soft robotic control.