Passive Micro Elastofluidic Controller for Constant Flow Rate

Abstract Precise flow rate control is critical for microfluidic systems in biomedical, chemical, and analytical applications. Conventional flow‐regulating microvalves often depend on complex, active components for sensor‐based feedback. Active flow rate control increases system complexity and cost. For applications that require a constant flow rate, independent of the inlet pressure, a passive controller is a more favorable option. This paper presents a passive micro elastofluidic device that achieves autonomous flow control through elastic membrane deformation, eliminating the need for external actuation and power supply. The device incorporates a single elastic polydimethylsiloxane (PDMS) membrane integrated into a compact, multi‐layer polymethyl methacrylate (PMMA) device. Utilizing both fluid‐structure interaction (FSI) simulation in COMSOL and experimental validation, the influence of membrane shape (rectangular, circular, elliptical) and thickness (300–350 µm) on flow regulation is investigated. The results demonstrate that circular membranes offer the most stable flow control with minimum variation (2.63%), while thicker membranes improve regulation precision but raise threshold pressures. Experimental results closely matched simulation predictions, confirming the robust self‐regulating behavior of the device. This work offers a simple, cost‐effective solution for consistent passive flow control in microfluidic platforms, with applications in precise drug delivery, chemical synthesis, and lab on a chip.