Fabrication of 3D microstructure array on chip for rapid pathogen detection

An advanced process of free angle photolithography (FAPL) is used for making 3D supercritical angle fluorescence (SAF) structures and transfer them to the polymeric chip by injection molding for low-cost microfluidic devices with the embedded optical sensing. The FAPL was performed via a motorized stage to control the angle of incidence of light and achieve the desired shape with dimension from 50 µm to 150 µm and slope required for the 3D optical structure. These 3D structures are used for enhancement of fluorescent signal through the unique properties of SAF. The presented SAF structure has a reduced active area (50 μm) that allows enrichment of the fluorescence efficiency and reduces the amount of sample required for detection on the polymeric microfluidic chip. Herein, we are presenting reduced dimension of SAF structures, fabricated by FAPL process and increases the number of SAF per mm2 area. This also reduced the volume of sample required per test. Improvement in the limit of detections (LOD) is observed when using the small dimensions of SAF. Solid phase polymerase chain reaction (SP-PCR) on these SAF structures permits for on-chip pathogen detection. These 3D structures have the potential to be widely used in microfluidic chips as a tool for signal enrichment and low-cost point of care systems for optical detection.