Quantitative analysis of optical transduction in microfluidic biosensing platforms: Nanoporous microbeads coupled with thin-film photodiodes

This work presents a simple and innovative approach for the quantitative analysis of optical transduction signals from fluorescence, chemiluminescence and colorimetry coupled to a model affinity interaction inside a microfluidic device. By coupling nanoporous microbeads packed inside a microfluidic channel with an integrated photodetector, it was possible to quantify (i) the specific number of antibody-label conjugates bound to protein A coated beads at increasing concentrations and (ii) the emitted/absorbed photon flux involved in each of the transduction mechanisms. The measurement of (i) and (ii) allows a full quantitative understanding of a biosensing mechanism in general, providing a generic methodology to design a microfluidic point-of-need device with the appropriate label and probe dissociation constant (Kd) to achieve the required sensitivity.