Quantitative hematocrit measurement of whole blood in a point-of-care lateral flow device using a smartphone flow tracking app.

We present a rapid and quantitative point-of-care (PoC) system based on a smartphone application that is capable of accurately tracking the flow of red blood cells (RBCs) through a no-reaction lateral flow assay (nrLFA) device. Utilizing only the camera feed from the smartphone and built-in image processing, the nrLFA is identified and RBC fluid flow distances and rates are recorded in parallel with the test without the need of any custom hardware or enclosure. We demonstrated the application by first measuring and then calculating hematocrit (Hct) values of whole blood samples with nominal content of 28%, 35%, 40%, and 45% Hct on the nrLFA platform. The PoC system was able to accurately measure (to within 1% Hct of nominal values) whole blood Hct in ~10-20 s after sample dispensing.