Electrokinetic a ccumulation of Enzymatic Product Enhances Detection s ensitivity in Microfluidic Elisa

We present a method to enhance detection sensitivity of microfluidic bead-based ELISA by accumulating fluorescent product molecules using nanofluidic electrokinetic preconcentration. Bead-based ELISA integrated on a microchip has been shown to provide a lower detection limit and require a shorter assay time [1], but signal intensity does not increase with time as the reaction product is continuously flushed away. We circumvent this limit by utilizing a nanofluidic electrokinetic preconcentrator to accumulate fluorescent product molecules downstream of the reaction zone and show that signal intensity increases with time, therefore greatly improving the detection sensitivity.