###### Abstract  
Microfluidic methods are an important tool for studying the microrheology of blood and the mechanical properties of blood cells--erythrocytes, leukocytes, and platelets. In patients with diabetes, hypertension, obesity, sickle cell anemia, or cerebrovascular or peripheral vascular diseases, hemorrhagiced alterations are commonly observed. These include increased blood viscosity and red blood cell (RBC) aggregation, along with reduced RBC deformability. Such disturbances significantly contribute to impaired microcirculation and microvascular perfusion. In blood vessels, abnormal hemorheological parameters can elevate resistance to blood flow, exert greater mechanical stress on the endothelial wall, and lead to microvascular complications. Among these parameters, erythrocyte deformability is a potential biomarker for diseases including diabetes, malaria, and cancer. This review highlights recent advances in microfluidic technologies for in vitro assays of RBC deformability and aggregation, as well as leukocyte aggregation and adhesion. It summarizes the core principles of microfluidic platforms and the experimental findings related to hemodynamic parameters. The advantages and limitations of each technique are discussed, and future directions for improving these devices are explored. Additionally, some aspects of the modeling of the microrheological properties of blood cells are considered. Overall, the described microfluidic systems represent promising tools for investigating erythrocyte mechanics and leukocyte behavior. microfluidic; microrheology; modeling Microfluidic Approaches for Evaluation of the Mechanical Properties of Blood Cells] Microheological and Microfluidic Approaches for Evaluation of the Mechanical Properties of Blood Cells [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [2  
(RBCD)--are consistently observed in metabolic diseases [2; 3]. In type 2 diabetes mellitus (T2 DM), these changes are linked to impaired microcirculation, particularly in the skin [2]. Studies by [PERSON] [6] and [PERSON] [7] focus on peripheral occlusive arterial disease (POAD), showing that disrupted RBC microrheological properties contribute to reduced blood fluidity. The research confirms a strong link between vascular disease and blood rheological dysfunction, while also identifying possible intervention strategies. A reduced number of erythrocytes (the main carriers of oxygen), decreased deformability of red blood cells, and an increased extent of aggregation that impaired the oxygen supply to tissue have been observed in patients with cancer [8]. All blood cells interact among themselves and with epithelial cells by mechanisms that depend on adhesion molecules, as well as by several forces involved in the interaction, such as van der Waals attraction forces and repulsive electrostatic forces [9; 10]. Using microchannel flow devices, the in vitro adhesion of flowing leukocytes and erythrocytes, in addition to their aggregation and deformability, can be studied by mimicking the laminar flow in vivo into blood vessels. The flow microchamber studies aim to find a relationship between the microrheological parameters of the blood and the leukocyte adhesion under flow conditions. Microfluidic approaches are becoming increasingly popular for the study of blood microrheology--e.g., RBC deformability, RBC aggregation, and leukocyte aggregation and adhesion [4; 10; 11; 12; 13; 14; 15; 16; 17; 18]. The analysis of the mechanical properties of blood cells has significantly advanced with the progress in microfluidic technology. Microfluidics and blood cell deformability intersect in a powerful area of research and diagnostics, in which micro-scale fluid dynamics are used to study and measure how red blood cells (RBCs) and other blood components deform under flow conditions.