Dual-mode hydrodynamic railing and arraying of microparticles for multi-stage signal detection in continuous flow biochemical microprocessors

Continuous flow particulate-based microfluidic processors are in critical demand for emerging applications in chemistry and biology, such as point-of-care molecular diagnostics. Challenges remain, however, for accomplishing biochemical assays in which microparticle immobilization is desired or required during intermediate stages of fluidic reaction processes. Here we present a dual-mode microfluidic reactor that functions autonomously under continuous flow conditions to: (i) execute multi-stage particulate-based fluidic mixing routines, and (ii) array select numbers of microparticles during each reaction stage (e.g., for optical detection). We employ this methodology to detect the inflammatory cytokine, interferon-gamma (IFN-gamma), via a six-stage aptamer-based sandwich assay.