Colorimetric Smartphone-Based Dry Assay for the Determination of Hemoglobin

A novel smartphone-based dry assay was developed for quantitative determination of hemoglobin concentration ([Hb]) in blood. Hemoglobin ((Hb) test strips and smartphone imaging enabled analysis of multiple color parameters, with the G value providing the highest sensitivity (slope = 3.36). Analytical models based on the G value showed that the G0–G model was most robust to variations in light intensity and color temperature (maximum deviations: −48% and −7.76%, respectively). Optimal sensitivity was achieved at +1 EV exposure compensation. The regression equation was y = 4.33[Hb] − 12.3 (R² = 0.995, n = 3), and the detection limit was 0.62 g/dL. The assay exhibited good repeatability at low, medium, and high [Hb] levels (RSDs: 4.8%, 1.3%, 2.1%; n = 10) and strong agreement with a commercial HemoCue analyzer (R² = 0.910, n = 30). This method offers a cost-effective tool for on-site Hb testing.