A novel automatic electrokinetically-controlled immunoassay lab-on-a-chip was developed in this paper. The microchip was made of poly(dimethylsiloxane) (PDMS)/glass using photolithography and replica molding. The immunoassay technique using anti-Helicobacter pylori antibody was applied to detect H. pylori protein antigens. Rhodamine-labeled secondary antibody was employed for signal generation. Experiments were first conducted on a straight microchannel to prove the feasibility of an electrokinetically-driven immunoassay. The detection limit for the coating antigen was found to be 1 ng/μL. Automatic electrokinetically-controlled immunoassay experiments were further carried out on a microchannel network. Numerical simulation and experimental studies were combined for the first time to demonstrate an integrated, electrokinetically-controlled immunoassay lab-on-a-chip. The electrokinetically driven, time-dependent reagent delivery processes were simulated using finite element method (FEM). Fully automatic on-chip experiments were accomplished by sequentially changing the applied electric field. It was found that the lab-on-a-chip can realize much shorter assay time, reduced reagent consumptions and automation while the detection limit is better than the conventional colorimetric immunoassay.

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