2892-LB: Improving the Reproducibility of Red Blood Cell Transit Velocity Distributions for HbA1c Estimation Using a Microfluidic Sensor

Introduction and Objective: In our previous study, RBC stiffness was evaluated using RBC transit velocity measured with a microfluidic chip, showing a higher proportion of stiff RBCs at elevated HbA1c levels. However, limited reproducibility of velocity distributions restricted quantitative HbA1c estimation. This study aimed to improve measurement precision and develop a formula to estimate HbA1c from RBC velocity distributions. Methods: Blood samples were diluted in DPBS and a surfactant was added to the dilution buffer to minimize cell adhesion. More than 500 RBC velocities were measured per sample and normalized by flow velocity. Results: Without surfactant, RBC-glass adhesion varied across sensors and caused large variation in velocity distributions, shifting them toward slower velocities. With surfactant, velocities were tightly distributed and reproducible across sensors. RBCs from individuals with diabetes showed reduced velocity dispersion compared with non-diabetic individuals. A slope-based index near the distribution peak strongly correlated with HbA1c (R² = 0.8696). Conclusion: Surface adhesion in glass microfluidic chips distorts RBC velocity distributions and reduces reproducibility. Reducing adhesion with surfactant improved distribution stability, and the resulting dispersion index correlated with HbA1c. This power-free sensor may enable simple HbA1c estimation in point-of-care settings. Disclosure E. Park: Employee; Current; Orange Biomed Co., Ltd. Stock/Shareholder; Current; Orange Biomed Co., Ltd. S. Kang: Employee; Current; Orange Biomed Co., Ltd. Stock/Shareholder; Current; Orange Biomed Co., Ltd. J. Oh: Employee; Current; Orange Biomed Co., Ltd. U. Ko: Employee; Current; Orange Biomed Co., Ltd. Stock/Shareholder; Current; Orange Biomed Co., Ltd.