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Programmable Flow Control in Rotating Microfludic Systems using elastic patch valves

Authors :

Zohreh Mohammadi Zadeh¹ Amin Dehghan² Esmail Pishbin³ Mahdi Navidbakhsh⁴

1- دانشگاه علم و صنعت ایران 2- دانشگاه علم و صنعت ایران 3- سازمان پژوهش علمی و صنعتی ایران 4- دانشگاه علم و صنعت ایران

Keywords :

Centrifugal microfluidics،Lab-on-a-Disc (LoaD)،Elastic Patch Valves (EPV)،programmable flow control،point-of-care diagnostics

Abstract :

We present a compact elastic patch valve (EPV) for centrifugal Lab-on-a-Disc (LoaD) that achieves accurate, fully passive flow control without the need for pneumatic, electrical, or magnetic actuation. The valve is realized as a multilayer PC–adhesive–SILICON–PC stack fabricated through cleanroom-light, rapid-prototyping steps that are compatible with low-cost manufacturing. To evaluate valve performance, we systematically investigated three primary design parameters: source-reservoir volume, radial placement on the disc, and SILICON membrane thickness. Standardized rotation protocols and image-based evidence (disc photographs and time-lapse frames) were employed to compare flow initiation, closure, and stability. The results demonstrate that opening behavior is largely independent of reservoir volume once proper priming is achieved. Placement at larger radii consistently reduced the opening threshold and enabled earlier, more robust flow initiation, while variations in membrane thickness strongly influenced actuation sensitivity: thicker membranes required higher rotational input, whereas thinner membranes opened more readily yet reseated cleanly. Across multiple discs and repeated cycles, the valve exhibited reproducible operation, remained leak-free at rest, and delivered reliable sequencing from semi-open restriction to complete reservoir transfer. Collectively, these findings establish a practical design window—outer-half radial positioning, mid-range volume, and intermediate membrane thickness—that enables programmable on-disc fluid transport, mixing, separation, and washing using rotation alone, without external hardware.