A biochip reader using super critical angle fluorescence

We present fluorescence chip reader for rapid, multiplexed assay measurements on plastic biochips. The system is designed as a low-cost, compact and robust instrument for point of care testing. Fluorescence imaging of biochip arrays is accomplished with a custom designed piezo-motor-driven scanning stage coupled to an optical element based on supercritical angle fluorescence (SAF). The use of SAF not only provides substantial enhancement of the fluorescence collection efficiency but also confines the fluorescence detection volume strictly to the close proximity of the biochip surface, thereby discriminating against fluorescence background from the analyte solution. The high imaging resolution of the SAF scanner is demonstrated by measuring the point spread function of 200 nm fluorescence beads. The sensitivity of the system is determined by measuring an array of low fluorophore concentrations and by real-time monitoring of a model bioassay.