LED Excitation of an Imaging Cytometer for Bead-Based Immunoassay

We present and demonstrate a light-emitting diode (LED)-excited imaging cytometer for the detection of bead-based immunoassay samples. A broad area green LED illuminates the specimen plane using a set of aspheric lenses and an excitation filter. The imaging module was comprised of an objective lens, filters, tube lens, and camera. To demonstrate the multiplex capability of the presented system, a panel of three sets of beads with varying classification fluorescence intensity was employed. Experimental results revealed that the LED light source provides uniform illumination across the specimen plane, and therefore permits the multiplex detection of three biomarkers. Detection of a sepsis biomarker, procalcitonin, was used to demonstrate the detection sensitivity and measurement range of the system. The imaging cytometer can detect the concentration of procalcitonin as low as 24.4 pg/mL and it holds the potential for being developed for point-of-care testing applications.