Self-adaptive flexible valve as passive flow regulator

Valves are widely used in fluidic channel systems to regulate flows. In many applications, maintaining a constant flow rate under varying input conditions is critical. However, current active or passive valves suffer from several drawbacks, such as complex structures, complicated fabrication processes, and complex operational procedures. This paper presents a novel design concept for fluidic channels using a simple structure that can serve as self-adaptive passive valves to regulate flow under external pressure. The design relies on embedding a cantilever-like flap inside a channel to provide a self-regulated closed-loop control of the flow. The flap can passively deform to adapt to the variation of the fluid pressure. A theoretical model is developed and validated by finite-element simulations to understand the flow characteristics of this design. Based on the theoretical model, we provide the design rules for obtaining valves with desired pressure-flow rate responses. Furthermore, by integrating the quantitative design tool and 3D printing, a valve that can maintain a constant flow rate over a certain pressure range is designed, fabricated, and characterized. With support from systematic analysis and rapid manufacturing techniques, the valve design proposed here can open routes for applications in microfluidic systems and drug infusion systems.