Research Areas > Circulatory Vascular Flows and Biomedical Imaging

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Speckle analysis for measurement of RBC aggregation

Post Image A simple microfluidic-based method is proposed to achieve sensitive detection of hyperaggregation. Given that formation of erythrocyte aggregation (EA) in the channel creates clear speckle patterns, the EA extent can be estimated by calculating a speckle area (ASpeckle) through a normalized autocovariance function. EA variations caused by dextran treatment are quantitatively evaluated using characteristic time (λSpeckle) obtained by fitting the variations of ASpeckle. As a result, it is found that the proposed method can detect variation of EA reasonably.   내용 보기

Relation between velocity profile and blood viscosity

Post Image Variations in hemorheological properties alter flow resistance and wall shear stress in blood vessels. To investigate blood flows according to hemorheological variations, the flow rate of blood samples (RBCs suspended in autologous plasma, dextran-treated plasma and in PBS solution) was precisely controlled with a syringe pump. Velocity profiles of blood flows were measured by using a micro-particle image velocimetry (micro-PIV) technique. The shape of velocity profiles was quantified by using a curve-fitting equation. It is found that the shape of the velocity profiles is highly corre...   내용 보기

3-D Visualization of in vitro disease model using phase-contrast digital holographic microscopy

Post Image   The biophysical properties of HUVECs grown on normal or enzyme-degraded collagen films were measured using phase-contrast digital holographic microscopy. Two collagen films were prepared as bio-inspired ECM models. At the top of the surface-treated glass slides, we prepared two different types of collagen films: normal collagen film, which mimics the extracellular matrix of normal blood vessels, and broken collagen film, which mimics the extracellular matrix of abnormal blood vessels. The collagen structure was intentionally broken using collagenase. HUVECs were incubated on the top of...   내용 보기

Fabrication of microbubble for X-ray PIV technique

Post Image   X-ray imaging has been used to visualize various bio-fluid flow phenomena in a nondestructive manner. X-ray particle image velocimetry (PIV) was developed to measure velocity fields of blood flows to obtain hemodynamic parameters related with cardiovascular diseases. Recently, a time-resolved X-ray PIV technique was employed to measure velocity fields of blood flows under actual physiological conditions. In this study, CO2 microbubbles were tested to find the most suitable conditions for practical applications of X-ray PIV to blood flows. The optimal fabricate condition was suggested i...   내용 보기

Variation of velocity profile and RBC aggregation under pulsatile flow

Post Image Under pulsatile flow conditions, red blood cells (RBCs) are aggregated and dispersed. The RBC aggregation is an influential factor in hemorheological properties. Velocity profile was measured by SIV analysis. RBC aggregation was estimated ultrasound echogenicity distribution analysis. The bluntness quantified as K value was cyclically varied. This variation may be closely related to the variation of RBC aggregation.       내용 보기

Improvement of SIV and CLAHE

Post Image Speckle image velocimetry (SIV), which applies a cross-correlation algorithm to B-mode images of blood flow. The grayscale intensity of images varies along the radial direction. This inhomogeneous distribution decreases signal-to-noise ratio of cross-correlation analysis and produces spurious results. Contrast-limited adaptive histogram equalization (CLAHE) could minimize errors of SIV technique under in vitro and in vivo conditions.   내용 보기

Effect of swirling inlet condition on the flow field in a stenosed arterial" vessel model

Post Image   Blood flow in an artery is closely related to atherosclerosis progression. Hemodynamic environments influence platelet activation, aggregation, and rupture of atherosclerotic plaque. The existence of swirling flow components in an artery is frequently observed under in vivo conditions. However, the fluid-dynamic roles of spiral flow are not fully understood to date. In this study, the spiral blood flow effect in an axisymmetric stenosis model was experimentally investigated using particle image velocimetry velocity field measurement technique and streakline flow visualization. Spiral i...   내용 보기

Biophysical property measurement of blood using a microfluidic chip

Post Image Viscosity and viscoelasticity of blood were quantitatively measured using flow control techniques in microfluidic analogue of Wheastone-bridge circuit. Thereafter, the proposed method was successfully applied to measure biophysical properties of rat blood circulating in an extracorporeal rat bypass loop.     내용 보기

Extracorporeal bypass loop for basic hemodynamic and pathogenic research

Post Image A rat extracorporeal bypass model was developed as in vivo and in vitro models. This bypass loop was constructed between the jugular vein and femoral artery of a rat. Three pinch valves were installed in the loop.    The flow velocity and the pulsatility index of the blood flow in the microtube can be controlled by adjusting the three pinch valves.   내용 보기

Chitosan microparticles incorporating gold as an enhanced contrast flow tracer in dynamic X-ray imag...

Post Image  X-ray imaging has significant advantages as one of the most popular diagnostic tools to seethrough various biological systems. We have developed chitosan microparticles incorporating gold nanoparticles (AuNP) as a new enhanced contrast flow tracer for dynamic X-ray imaging. Gold is a useful material possessing high X-ray absorption ability and also biocompatibility. We chose chitosan as an AuNP delivery system because it can effectively trap AuNPs at high yield. In particular, the unique gold ion reduction ability of and compatibility with surface-modified chitosans are effectively utili...   내용 보기