This work presents the use of integrated, liquid core, optical waveguides for measuring immunoagglutination-induced light
scattering in a microfluidic device, towards rapid and sensitive detection of avian influenza (AI) viral antigens in a real
biological matrix (chicken feces). Mie scattering simulations were performed and tested to optimize the scattering efficiency
of the device through proper scatter angle waveguide geometry. The detection limit is demonstrated to be 1 pg mL−1 in both clean buffer and real biological matrix. This low detection limit is made possible through on-chip diffusional mixing
of AI target antigens and high acid content microparticle assay reagents, coupled with real-time monitoring of immunoagglutination-induced
forward Mie scattering via high refractive index liquid core optical waveguides in close proximity (100 μm) to the sample
chamber. The detection time for the assay is <2 min. This device could easily be modified to detect trace levels of any biological
molecules that antibodies are available for, moving towards a robust platform for point-of-care disease diagnostics.
Keywords Lab-on-a-chip - Optofluidic - Immunoassay - Bird flu - Latex agglutination - Influenza A
Parts of the preliminary results of this work were presented at SPIE Defense, Security and Sensing, Orlando, Florida, 13–17
April 2009: Conference number 7313, paper number 73130J.