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Microfluidic Applications for Flow Cytometeric Analysis of Cells and Particles
신세현(Sehyun Shin),구윤희(Yunhee Ku),서장수(JangSoo Suh) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Microsystems create new opportunities for conventional cell analysis by combining microfluidics and flow cytometry. This article describes recent developments in conventional flow cytometers and related microfluidic flow cytometers to detect, analyze, and sort cells or particles. Flow cytometry strongly consisted of fluidics, optics and electronics requires a large space to equip various components, which are mostly the fluidic components such as compressor, fluid handling system. Adopting microfluidics into flow cytometry enables volume- and power-efficient, inexpensive and flexible analysis of particulate samples. In this paper, we review various efforts that take advantage of novel techniques to build microfluidic cell analysis systems with high-speed analytical capability. Highly integrated microfluidic cytometry shows great promise for basic biomedical and pharmaceutical research, and robust and portable point-of-care devices could be used in clinical settings.
Rheolocial reconsideration of blood viscosity
Yunhee Ku(구윤희),Gyoseon Yeom(염교선),Sehyun Shin(신세현),Jangsoo Suh(서장수) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Deformability of red blood cells(RBCs) plays an important role in microvascular flow system and impaired RBC deformability causes significant increase blood viscosity. The present study investigated the correlation of RBC rheological properties and blood viscosity. When RBC were heated at 49℃, the deformability was significantly reduced compared to that of control but the corresponding suspension viscosity was almost the same as the normal blood viscosity. This unexpected result was further studied with morphology of RBCs and tank-treading capability. It is found that heat treatment altered the geometry of RBC including cell shape and size, which result in reduction of blood viscosity. Conclusively, the effect of reduced RBC size suppresses the effect of decreased deformability on blood viscosity. Furthermore, we investigated the effect of tank-treading motion of RBCs on blood viscosity.
Analysis of dynamic RBC aggregation in microfluidic device using laser backscattering
Hou Jianxun(호우지엔쉰),Yunhee Ku(구윤희),Sehyun Shin(신세현),Jangsoo Suh(서장수) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The aggregation characteristics of red blood cells (RBCs) play an important role in microvascular flow system and increased RBC aggregation has been observed in various pathological diseases, such as thrombosis and myocardial infarction. This paper presents a novel microfluidic device for evaluating the aggregability of RBCs on the flow of blood by directly measuring aggregating force (critical shear stress) to overcome shearing force due to flow in a microchannel. The device functionality is based on a microfluidic slit rheometry with decreasing pressure-driven flow mechanism with laser light backscattering technique. The present RBC aggregation index shows a higher sensitivity to small changes of aggregation modulated by amount of fibrinogen in blood plasma. The direct measurement of RBC aggregating force represents a new concept for the field of blood rheology and should prove beneficial for basic science and clinical applications.
In-vitro study of hemorheological characteristics of erythrocytes incubated in glucose medium
Gyoseon Yeom(염교선),Yunhee Ku(구윤희),Sehyun Shin(신세현),Jangsoo Suh(서장수) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Deformability of red blood cells (RBCs) plays an important role in microvascular flow system and decreased RBC deformability is frequently observed in diabetic patients. The object of this study was to examine the effect of elevated in vitro glucose concentrations on hemorheological properties of human erythrocytes. Groups were exposed to 0 ~ 5% glucose concentrations. The incubation time effect of any changes was also evaluated. Hemolysis of erythrocytes was evaluated using spectrophotometric methods. Erythrocyte deformability was assessed using a new microfluidic ektacytometry (RheoScan-D 200) and erythrocyte aggregation was measured with LORCA. We found that RBC deformability was significantly decreased with increasing the glucose concentration in the medium. Also the RBC aggregation was decreased in normal plasma condition. Our findings show that oxidative effect of glucose on erythrocytes strongly depends on concentration and incubation time.
Red Blood Cell Deformability and its Hemorheological Consideration
구윤희(Yunhee Ku),장리쥬엔(Lijuan Zhang),박명수(Myungsu Park),신세현(Sehyun Shin),서장수(Jangsoo Suh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The suspension of hardened red blood cells (RBCs) differs from the suspension of normal RBCs with respect to their rheological behavior. The deformability of normal and hardened RBCs (obtained by heating blood at 49°C or by incubating RBCs in a solution of hydrogen peroxide) was measured with a slit diffractometer and RBC suspension viscosity was measured with a rotational viscometer. The peroxidetreated RBCs showed a significant decrease of the deformability and their suspension viscosity increased over a range of shear rates. The suspension viscosity of the heated RBCs, however, where the deformability is even lower than that of the peroxide-treated RBCs, was slightly higher than that of the normal RBC suspension in the high shear rates. The present study found that not all rigid cells cause an increase of blood viscosity at high shear rate, and therefore that decreased membrane deformability is not predictive of high-shear blood viscosity.
RBC aggregation analysis based on a disposable micro-fluidic device using laser backscattering
Hyogyun Kim(김효균),Yunhee Ku(구윤희),Sehyun Shin(신세현),Jangsoo Suh(서장수) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
A microfluidic device for highly effective, minimum sample required, disposable cell-aggregation analysis is reported. Disposability after use, specifically in cell aggregation assay, is a critical element in ‘labon-a-chip’ applications. However, traditional methods of cell aggregation require washing process after each measurement. A simple and effective opto-microfluidic assay system is microfabricated and characterized to quantify the characteristics of cell aggregation. The device functionality is based on light backscattering technique in a microfluidic channel with vibration-induced disaggregating mechanism. Quantitative measurements of aggregation indexes are acquired with optical l of blood sample, the M index, halfμabsorption measurement at 635 ㎚. With 20 time and aggregation index in the micro-aggregometer present showed high reproducibility with low CV values (less than 7.5%) and a strong correlation with a commercial aggregometer with less than a 3.0 % error rate.