Precise sample positioning for multipoint immunoassay using nanofluidic preconcentrator

In this paper, we design, fabricate and package a novel micro/nanofluidic biochip that combines the high rate sample preconcentration and the precise positioning of the concentrated sample to achieve a highly sensitive detection and a multipoint sensing of protein biomarkers. To apply the preconcentrator to the immunoassay, thin layers of Au which provide sensing areas for antibody immobilization and antibody-antigen binding are sputtered. In order to overcome the limitation of diffusion on the sensitivity of immunoassay and show the significance of this manipulation capability, we preconcentrate the antigen near the nanofluidic channels and then move the preconcentrated band to the site of binding. This protocol greatly enhances the antibody-antigen interaction and thus increases the intensity of the signal. Therefore, sensitivity of our device can be significantly improved without an impractically long period of incubation (From typically >; 1 hour to <; 10 minutes) to achieve the detection limit.