Browsing by Subject "Red blood cell"
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Item Open Access Computational study of scattering from healthy and diseased red blood cells(Society of Photo Optical Instrumentation Engineers, 2010-08-05) Ergül, Özgür; Arslan-Ergül, A.; Gürel, LeventWe present a comparative study of scattering from healthy red blood cells (RBCs) and diseased RBCs with deformed shapes. Scattering problems involving three-dimensional RBCs are formulated accurately with the electric and magnetic current combined-field integral equation and solved efficiently by the multilevel fast multipole algorithm. We compare scattering cross section values obtained for different RBC shapes and different orientations. In this way, we determine strict guidelines to distinguish deformed RBCs from healthy RBCs and to diagnose various diseases using scattering cross section values. The results may be useful for designing new and improved flow cytometry procedures.Item Open Access Focusing-free impedimetric differentiation of red blood cells and leukemia cells: a system optimization(Elsevier, 2020) Bilican, İ.; Güler, M. T.; Serhatlıoğlu, Murat; Kırındı, T.; Elbüken, ÇağlarA focusing-free microfluidic impedimetric cell detection system is developed. The effect of the channel dimensions, solution conductivity, excitation voltage, and particle size on impedimetric signal outputs were optimized to increase the sensitivity of the system. Conventional microfabrication techniques were adapted to obtain low height, resealable microchannels. The geometry optimization was performed by a combination of analytical, numerical and experimental approaches. The results demonstrate that reliable impedimetric particle differentiation can be achieved without any labeling or particle focusing. The system parameters were studied and rule-of-thumb design criteria were provided. Finally, using the developed system, red blood cells and leukemia cells were experimentally detected and differentiated. Thanks to its simplicity, the focusing-free cell differentiation system may find applications in several cellular diagnostic uses.Item Open Access A microfluidic erythrocyte sedimentation rate analyzer using rouleaux formation kinetics(Springer Verlag, 2017-03) Isiksacan, Z.; Asghari, M.; Elbuken, C.Red blood cell aggregation is an intrinsic property of red blood cells that form reversible stacked structures, also called rouleaux, under low shear rates. Erythrocyte sedimentation rate (ESR), commonly performed in clinics, is an indirect inflammation screener and a prognostic test for diseases. We have recently developed a microfluidic system for rapid measurement of ESR from 40 µl whole blood employing the aggregation dynamics. In this work, we propose the use of an aggregation inducer, dextran polyglucose, for the preparation of multiple blood samples with differing aggregation dynamics. Using these samples, we characterized the performance of the system with three aggregation indices and under varying experimental conditions. Additionally, using the same underlying principle, we improved the system for ESR measurement using both venipuncture and fingerprick whole blood samples depending on the user needs. The results demonstrate that the system performs equally well with both samples, which validates the compatibility of the system for both laboratory and point-of-care applications where venous and capillary blood are the primary samples, respectively. The detailed characterization presented in this study legitimates the feasibility of the system for ultrafast and facile measurement of ESR in clinics and diverse off-laboratory settings.Item Open Access Microfluidic platforms for hemorheology and coagulation time analysis(Bilkent University, 2020-01) Işıksaçan, ZiyaBlood is a non-Newtonian fluid consisting of plasma and cells that uninterruptedly circulate the body. Erythrocytes are deformable anucleated discoid blood cells with a viscoelastic membrane, constituting around half of blood volume. Hemorheology investigates blood flow characteristics determined by hemorheological properties comprising aggregation, sedimentation, and deformation of erythrocytes as well as blood/plasma viscoelasticity. These hemorheological properties are intricately interdependent. Hence, acquired or hereditary disorders affecting one hemorheological property (malaria, diabetes, anemia) lead to alterations in other properties. Available techniques lack the ability to measure these properties all-at-once and in physiologically relevant conditions. Blood coagulation is as essential as a healthy blood flow. This is a body defense mechanism involving the interplay of blood constituents for stable clot formation to stop bleeding. Sensitive and periodic measurement of coagulation time is critical for individuals who are under the risk of excessive bleeding or thrombus-originated vessel obstruction. Today, these conditions are responsible for 25 percent of all deaths worldwide. Unfortunately, the conventional practice for coagulation monitoring is fixed-interval hospital visits by patients. In this thesis, we present novel microfluidic platforms and measurement methods for the analysis of hemorheological properties and coagulation time parameters. The assays are based on optical quantification of erythrocyte dynamics inside miniaturized channels. The measurements require only 50 µl undiluted blood and are completed in less than 5 min. Firstly, we demonstrate optical measurement of erythrocyte aggregation and rapid measurement of erythrocyte sedimentation rate (ESR) using aggregation dynamics. Secondly, we present the results of clinical ESR tests performed in a local hospital and compare the performance of the developed platform with the conventional 1-hour test. Simultaneously obtained optical transmission signals and real-time microscopic observations of erythrocytes in custom-developed cartridges validate the proposed measurement principle. Thirdly, we present a method offering a holistic approach to blood flow characterization. The method enables simultaneous analysis of multiple hemorheological properties by optically investigating collective erythrocyte dynamics, primarily deformation, in a channel during unique damped oscillatory sample motion. We create a fluidic environment mimicking in vivo flow: confined, directional, and pulsatile movement of blood at flow rates and hematocrit comparable to physiological levels. Fourthly, we present a method for blood coagulation time measurement by optical quantification of erythrocyte aggregation. We demonstrate the fundamental relationship between aggregation and coagulation. Finally, we present an alternative, entirely disposable microfluidic platform for hemorheology and coagulation time analysis based on migration analysis of blood sample in microfluidic channels. Overall, the microfluidic platforms and measurement methods presented here will potentially initiate routine hemorheological and coagulation time analysis even in resource-poor setting.Item Open Access Rigorous solutions of scattering problems involving red blood cells(IEEE, 2010) Ergül, Özgür; Arslan-Ergül, Ayça; Gürel, LeventWe present rigorous solutions of scattering problems involving healthy red blood cells (RBCs) and diseased RBCs with deformed shapes. Scattering cross-section (SCS) values for different RBC shapes and different orientations are obtained accurately and efficiently using a sophisticated simulation environment based on the electric and magnetic current combinedfield integral equation and the multilevel fast multipole algorithm. Using SCS values, we determine strict guidelines to distinguish deformed RBCs from healthy RBCs and to diagnose related diseases.