Hand-powered micro-slit-gated microfluidics for concurrent blood typing and hematocrit estimation

Blood testing is indispensable for clinical diagnostics, transfusion safety, and emergency interventions, with blood type and hematocrit (HCT) being two critical parameters. Conventional methods, though accurate, require bulky instruments, stable electricity, milliliter-scale samples, and skilled personnel, thereby limiting their utility in decentralized or field-based diagnostics, especially in emergencies or resource-limited settings. Here, we present a microfluidic chip integrated with a hand-powered centrifuge platform (hpFuge) for simultaneous blood typing and HCT estimation using only 3 μL of whole blood in total without electricity. A micro-slit (∼7.5 μm) formed at the channel outlet selectively traps agglutinated red blood cells (RBCs), enabling blood type identification, while the length of RBCs agglutination band serves as a quantitative indicator of HCT. Systematic optimization of microchannel length, curvature radius, and channel depth established design parameters that enhance mixing efficiency, flow stability, and signal readability. Band length correlated linearly with HCT values ranging from 10% to 60%, yielding a correlation coefficient of R²=0.99. Validation using 21 clinical samples demonstrated strong agreement with automated analyzers, with a mean bias of 0.126% and 95% limits of agreement of -0.63% to 0.88%. The assay is completed within 1 min, requires no power or complex instrumentation, and provides reliable results with minimal blood volume. This portable and user-friendly platform shows strong potential as a practical diagnostic solution for challenging healthcare environments.