A mobile phone-based approach to detection of hemolysis

Preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome are pregnancy-related complications with high rates of morbidity and mortality. HELLP syndrome, in particular, can be difficult to diagnose. Recent work suggests that elevated levels of free cell hemoglobin in blood plasma can, as early as the first trimester, potentially serve as a diagnostic biomarker for impending complications. We therefore developed a point-of-care mobile phone-based platform that can quickly characterize a patient's level of hemolysis by measuring the color of blood plasma. The custom hardware and software are designed to be easy to use. A sample of the whole blood (~10 µL or less) is first collected into a clear capillary tube or microtube, which is then inserted into a low-cost 3D-printed sample holder attached to the phone. A 5-10 min period of quiescence allows for gravitational sedimentation of the red blood cells, leaving a layer of yellowish plasma at the top of the tube. The phone camera then photographs the capillary tube and analyzes the color components of the cell-free plasma layer. The software converts these color values to a concentration of free hemoglobin, based on a built-in calibration curve, and reports the patient's hemolysis level: non-hemolyzed, slightly hemolyzed, mildly hemolyzed, frankly hemolyzed, or grossly hemolyzed.. The accuracy of the method is ~1 mg dL−1. This phone-based point-of-care system provides the potentially life-saving advantage of a turnaround time of about 10 min (versus 4+hours for conventional laboratory analytical methods) and a cost of approximately one dollar USD (assuming you have the phone and the software are already available).