Automated immunoassay system based on the colorimetric detection

In this work, an automated immunoassay system is developed based on colorimetric detection for the application of clinical diagnostics. In this system, most of the biological processes of sandwich immunoassay can be performed automatically. The immunoassay result can be represented by color intensity and observed by a regular camera or even naked eye. The biological reactions were performed in a microfluidic chip and the result of sandwich immunoassay could be observed directly. An example of the sandwich immunoassay has been demonstrated using this automated system. Antihuman IgG, human IgG, and anti-human IgG-Biotin conjugates were selected as the primary antibody, target antigen, and secondary antibody, respectively. The target antigen concentration ranging from 0.5 to 160 ng/ml can be detected quantitatively and the detection limit was 0.5 ng/ml. Since the detection method is simplicity, low cost, and miniaturization; therefore, the proposed system has the potential to be developed to an automated disease screening system.