Pumpless Open-Surface Microfluidic Device for Protein Detection

The present work focuses on the development of an open-air, passive microfluidic device to be employed for the detection of antigens, with the ultimate goal of performing the analysis and quantification of proteins contained within human skin oil. In the prototyping step, bovine serum albumin proteins (BSA) are detected by implementing a bicinchoninic acid (BCA) assay. The design of the device allows pumpless transport of a solution, made of BSA and DI water, and the coverage of a detection zone. The latter zone is silane-functionalized, so that proteins can be immobilized on its surface. Different wettability-patterned designs are considered and tested. Ultimately, the optimal design is composed of an axial, silane-functionalized track located between two superhydrophilic transport tracks, where the three tracks are patterned on a superhydrophobic background. The geometry (\textit{e.g.} wedge angles) of the detection and transport tracks is optimized in order to obtain the largest covered detection area, with the lowest possible sample volume. Subsequently, BCA detection is performed on the substrate characterized by the aforementioned design and a standard curve is obtained by analyzing samples with a known concentration of proteins.