A microfluidic approach for hemoglobin detection in whole blood

Diagnosis of anemia relies on the detection of hemoglobin levels in a blood sample.Conventional blood analyzers are not readily available in most low-resource regions whereanemia is prevalent, so detection methods that are low-cost and point-of-care are needed.Here, we present a microfluidic approach to measure hemoglobin concentration in a sampleof whole blood. Unlike conventional approaches, our microfluidic approach does not requirehemolysis. We detect the level of hemoglobin in a blood sample optically by illuminatingthe blood in a microfluidic channel at a peak wavelength of 540 nm and measuring itsabsorbance using a CMOS sensor coupled with a lens to magnify the image onto the detector.We compare measurements in microchannels with channel heights of 50 and 115 μm and foundthe channel with the 50 μm height provided a better range of detection. Since we use wholeblood and not lysed blood, we fit our data to an absorption model that includes opticalscattering in order to obtain a calibration curve for our system. Based on thiscalibration curve and data collected, we can measure hemoglobin concentration within 1g/dL for severe cases of anemia. In addition, we measured optical density for bloodflowing at a shear rate of 500 s-1 and observed it did not affect the nonlinearmodel. With this method, we provide an approach that uses microfluidic detection ofhemoglobin levels that can be integrated with other microfluidic approaches for bloodanalysis