## 4 Methods and Devices for Assessing Erythrocyte (RBC) Aggregation
### Image Analysis Method in a Flow Chamber
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Metric** & **Traditional Methods (e.g., Micropipette, Ektacytometry, Visometry)** & **Microfluidic Methods (e.g., High-Throughput Microchannel Devices)** \\ \hline Sample Volume & Moderate to large (typically 0.5–5 mL) & Low (often \(<\) 100 \(\mu\)L) \\ \hline Required Equipment & Bulky, specialized lab equipment (micropipette manipulators, rheoscopes, viscometers) & Compact microfluidic chips, pumps, microscope/camera setup \\ \hline Throughput & Low to moderate (single-cell or small sample batch analysis) & High (hundreds to thousands of cells per run) \\ \hline Analysis Type & Single-cell (micropipette) or population average (viscometry, ektacytometry) & Single-cell, with population-scale statistical power \\ \hline Automation Potential & Low to moderate & High (compatible with automated image analysis and fluid handling) \\ \hline Operator Skill Required & High (manual control, calibration, pipette fabrication) & Moderate (once setup is established) \\ \hline Diagnostic Readiness & Moderate (established but less scalable for clinical use) & High (more adaptable to point-of-care and personalized diagnostics) \\ \hline Physiological Relevance & Moderate to high (especially ektacytometry, viscometry) & High (mimics capillary-scale flow conditions) \\ \hline Cost per Test & High (due to complex setup and manual labor) & Potentially low (mass-producible chips, scalable testing) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of traditional vs. microfluidic methods used to measure RBC deformability. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Method/Device** & **Principle/Technique** & **Measured Parameters** & **Key Features/Limitations** & **Applications/ Disease Focus** \\ \hline Erythrocyte Sedimentation & Rate of RBC sedimentation in a vertical tube & Indirect RBC aggregation & Simple, low-cost; non-specific, affected by many factors & States of general inflammation \\ \hline Optical Agregometers (e.g., LORCA, Myrenne [25; 26; 27; 41]) & Light transmission/reflection under shear conditions & Aggregation index, light intensity curves & Widely used; complex, high maintenance, not suitable for routine clinical use & Research, diabetes, thrombosis, CVD clinical use \\ \hline Laser Optical Techniques & Laser diffractometry, optical trapping, diffuse scattering, capillaries & Aggregation force (Fagg), FSC, SSC & Combines in vitro and in vivo; quantifies biomechanics and aggregation force with high sensitivity & Fibrinogen/HSA effects, diabetes, RBC biomechanics \\ \hline Viscometric Index (IAE) [2; 44] & Ratio of blood viscosity at low vs. high shear rates & IAE = \(\eta_{11.02}\)/\(\eta_{94.5}\) & Strong correlation with low-shear blood viscosity; shear-dependent & T2 DM, microcirctimapimient \\ \hline Image Analysis in Flow Chambers [PERSON] et al. [14; 15], [PERSON] et al. [17; 1], [PERSON] et al. [29; 45; 46] & Microscopy in static/dynamic flow chambers & RBC aggregation index (RBCA), Cell-depleted layer (CDL) & Real-time visualization of aggregation, shear control; high level of imaging detail & Diabetes, PVD, cancer, CVD, drug effects \\ \hline Vibration-Based Microfluidic Aggregometer [PERSON] et al., 2006 [33] & Vibration disrupts RBC backscatter measured & I(t), p(t), aggregation dynamics & Disposable, low-cost, correlates with blood viscosity, shear-dependent; innovative clinical potential & Clinical monitoring, heated RBCs \\ \hline \hline \end{tabular}
\end{table} 
Table 5: RBC aggregation measurement techniques. [PERSON] et al. [46] used microscope imaging techniques to simultaneously observe RBC aggregation and velocity fields in microchannel flows. Their analysis of aggregate transport at bifurcations revealed unexpected behavior: smaller aggregates appeared in low-shear daughter branches, contradicting traditional views on the aggregation-shear relationship.