Smartphone-based portable fluorescence detection systems using two parabolic reflectors

Abstract

Fluorescence technique is widely used in clinical, bioprocess, and environmental applications. To be practical for the applications, fluorescence technique requires a potable fluorescence detection systems. In this work, we demonstrate effective portable fluorescence detection systems using a smartphone that allows objective quantification of fluorescence signals. Parabolic reflector and compound parabolic concentrator (CPC) were used to enhance the collection efficiency of fluorescence. A smartphone was used as detector to quantify fluorescence light, to analyze the measurement results, and to send the data to the central server for data mining. Using the ray-tracing method, we analyzed the optical characteristics of the detection systems by changing maximum incident half angle of two reflectors. For fluorescent immunochromatographic strip test (FICT), the light collection efficiency of the proposed optical structures was experimentally found to be 100-fold higher than without optical structures. Our study results showed that for a NP antigen, conventional assays, such as dot-blot immunoassay and RDT, have a lower lowest detectable concentration (LDC), $250 ng/ 10 \mu L$, indicating that those methods were 5-fold less sensitive than the FICT assay using the suggested detector. For a subtype of avian influenza A, H7N1, the proposed system can more sensitively detect the antigen over a conventional fluorescence detector. We expect that the proposed fluorescence detection systems are extremely promising approaches for disease outbreak monitoring and real-time surveillance of emerging public health threats.