Application of vertical microreactor stack with polystylene microbeads to immunoassay

The advantages of vertical microreactor stack with three-dimensional (3D) structure for immunoassay are discussed. The vertical microreactor stack uses vertical fluid flow operation with multifunctional fluid filters. The multifunction of fluid filter is very effective for micromixing and passive valve operation. The mechanism of micromixing is discussed by using computational fluid dynamics (CFD), and the results suggest that the mixing mechanism based on two main effects. One is Coanda effect and the other is Taylor dispersion induced in enormously high aspect ratio capillary and liquid plug. We demonstrated enzyme reaction with unique repeat mixing operation, to evaluate the micromixing performance of fluid filter. As the results, we proved that the fluid filter has very effective mixing performance. The detection limit, which demonstrated by competition enzyme-linked immunosorvent assay (ELISA), is comparable with recommended detection limit, which suggested by Japanese ministry for the environment. (c) 2008 Elsevier B.V. All rights reserved.