A simple and low-cost portable paper-based ABO blood typing device for point-of-care testing

ABO blood group is the most important blood type system for transfusion medicine. A paper-based analytical device (PAD) for ABO blood typing has been proposed. The device was composed of Whatman No. 113 paper, an absorbent gel pad, and a 3D-printing cassette. The 3D-printing cassette contained two circular holes for display of letters "A" and "B" on the PAD. Whole blood was dropped onto hydrophilic letters A and B on the PAD, in which the anti-A and anti-B were pre-immobilized, respectively. An absorbent gel pad was used to adsorb excess blood sample and washing solution during the washing step. The particle size of agglutinated red blood cells (RBCs) could not be eluted out of the paper by the elution solution. In contrast, non-agglutinated RBCs were washed out by means of elution solution. The devices could be used for real blood samples in a wide range of hematocrit levels, 21-59%. Unknown blood group samples (n = 500) were identified by the developed device and the results were compared with the conventional method, revealing 100% accuracy. Because of its compact size with low-cost fabrication, the portable ABO blood typing device has great potential for point-of-care testing, particularly in developing countries.