MEMS-based biosensors for environmental monitoring

Biosensors in connection with enzyme linked immunosorbent assay (ELISA) can be applied in many fields of research. In this paper, the reduction in the size of ELISA utilizing micro-chemical reaction is described in a microchamber array chip, and also a micro-flow antibody chip. The chips were fabricated by micro electromechanical system (MEMS) technology. The quantitative determination of dioxins was performed by using the chips. Glass or polystyrene beads were used for immobilization of an antibody at these chips. The antibody-immobilized beads were introduced into micro-flow channel or microchamber. As a competitive ELISA, sample solution mixed with horseradish peroxidase (HRP)-conjugated antigen, and non-HRP conjugated antigen was allowed to react in the microchamber or flow channel. As a sandwich assay, sample solution and HRP-conjugated antibody were sequentially added to the chamber. After the antigen-antibody reaction, addition of PBS buffer, hydrogen peroxide, and fluorogenic substrate produced the fluorescent dye. The resulting change in the fluorescence intensity was monitored by a fluorescence microscope.