Heterogeneous Immunoassay Considerations towards Point-of-Care Microfluidics-based Diagnostics

Numerous non-conventional heterogeneous immunoassay substrates have been developed to improve the capture and detection of biomolecules from a liquid sample, but many remain unutilized for point-of-care, microfluidics-based diagnostics. These non-conventional substrates often exhibit unique behaviors making the universal assay principles less applicable and more challenging to resolve when unexpected results arise during microfluidic integration. This thesis demonstrates one example of integrating a non-conventional immunoassay with microfluidics. A nitrocellulose-based microarray immunoassay is integrated with centrifugal disc (CD) microfluidics. The CD microfluidics was used to generate reciprocating fluid flow over the immunoassay reaction surface to improve the capture of biomolecules during the liquid sample incubation step of the assay. The CD microfluidic flow generation technique was characterized, simulated, and tuned for characteristic flow conditions before testing the immunoassay. Unexpected assay results contradicting theoretical expectations were obtained, requiring additional substrate assay troubleshooting. During the process, the substrate behavior was characterized and interesting revelations specific to its microfluidic integration were discovered. With the newfound knowledge, the assay was retested, and results explained. Ultimately, this study demonstrates the multifaceted complexities when combining two conceptually simple technologies towards point-of-care, microfluidics-based diagnostics