Optofluidic-based deformability cytometry: Characterizing erythrocyte elasticity and assessing storage quality

Abstract

Erythrocyte elasticity is an inherent, label-free marker for both physiological and pathological changes in erythrocytes, serving as a criterion for assessing the quality and suitability of stored blood. Although varieties of cell elasticity measurement techniques have been proposed, a small sample, non-contact, and continuous method is still in need. This article introduces an optofluidic-based deformability cytometry (O-DC) for characterizing erythrocyte elasticity, combining non-contact optical force with microfluidic technology. A tightly focused laser beam optically traps an erythrocyte, and the flow force induces cell deformation, allowing for elasticity characterization through force-dependent elongation. The O-DC technique offers high accuracy and desirable throughput for cell elasticity characterization, facilitated by quasi-static stretching and continuous cell delivery. The characterization throughput of O-DC is ∼3 cells per second at a flow rate of 30 μL/h and a laser power of 200 mW. Fresh erythrocytes exhibit measured elastic strains of 15.4–27.8% across flow rates of 10–30 μL/h, with an estimated elastic modulus of 2.6±0.3 μN/m. Using O-DC, the elasticity trend of erythrocytes stored for 0–6 weeks was analyzed, with their average elastic modulus increasing from 2.6±0.3 μN/m to 6.1±0.8 μN/m as the storage time increased. Our study highlights the potential of O-DC in clinical diagnostics and biomechanical research applications.