Development and optimization of an integrated capillary-based opto-microfluidic device for chemiluminescence quantitative detection

A capillary-action driven device amenable for integration of organic photodiodes (OPDs) was developed for monitoring parallel chemiluminescence (CL) reactions. Device characterization was conducted using finite element method (FEM) simulations. Definition of the simulation setup, dimensional optimization of the reaction chamber and overall geometrical characterization of the microfluidic device were the main simulation results. Furthermore, a non-uniform filling process was observed during the final simulation of the capillary device. Validation of this result and the proposed capillary-driven filling process was later confirmed by experimental results. Experimental testing performed on a single chamber defined an optimal exposure time to the luminescent substrate of 5 min, indicating a quick analyte detection time. Further tests using one chamber presented a linear relation between the signal-to-noise ratio and increasing concentrations of the protein used. A measured limit of detection of 28 nM was obtained for streptavidin. Regarding the tests performed on the whole device, acceptable values of 39 s±5 s were obtained for the luminescent substrate total filling times. Also, the microfluidic device showed the capability to perform a quantitative detection of the occurring CL reactions. Weaker optical signals, due to the occurrence of CL reactions, were detected in the chambers with a later filling process, as predicted by simulation results. Notwithstanding these results, the capillary-based device is promising for quantitative detection of proteins in future point-of-care systems, presenting an unprompted filling process and parallel quantitative detection capability.