Gravity‐induced convective flow in microfluidic systems: Electrochemical characterization and application to enzyme‐linked immunosorbent assay tests

A way of using gravity flow to induce a linear convection within a microfluidic system is presented. It is shown and mathematically supported that tilting a 1 cm long covered microchannel is enough to generate flow rates up to 1000 nL·min‐1, which represents a linear velocity of 2.4 mm·s‐1. This paper also presents a method to monitor the microfluidic events occurring in a covered microchannel when a difference of pressure is applied to force a solution to flow in said covered microchannel, thanks to electrodes inserted in the microfluidic device. Gravity‐induced flow monitored electrochemically is applied to the performance of a parallel‐microchannel enzyme‐linked immunosorbent assay (ELISA) of the thyroid‐stimulating hormone (TSH) with electrochemical detection. A simple method for generating and monitoring fluid flows is described, which can, for instance, be used for controlling parallel assays in microsystems.

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