An image based quantitative fluorescence immunoassay reader for HbA1c testing: Calibration & repeatability study

Image based readers for quantitative fluorescence immunoassays offer advantages of reliability and robustness over traditional scanning readers and has potential applications in point-of-care diagnostics. We had previously demonstrated an image based quantitative method to scan fluorescence labeled lateral flow test strips. Here we present an improved design, and report the calibration method and repeatability of the instrument. A new wideband emission filter was used instead of the previous narrowband filter and enhanced signal levels were obtained. Standard HbA1c calibrator set was used to evaluate the area ratios for various concentration levels of the analyte and generate the calibration curve. A straight line fit to the calibration data showed R-squared value to be 0.99. Repeatability of the instrument in successive test runs was evaluated to be fairly good with CV less than 4%. Inter-day repeatability of the instrument was also studied and the results were moderate.