Myungsu Park

Laser-diffraction slit rheometer to measure red blood cell deformability

The laser-diffraction technique has been applied to design a slit rheometer for measuring red blood cell deformability over a range of shear stress. Flow-rate and pressure-drop measurements are replaced with a measurement of pressure variation with time. Using a precision pressure transducer, one can measure the variation of pressure in the vacuum chamber, p(t), from which the shear stress and shear rate are mathematically calculated. In addition, a laser beam traverses a diluted blood suspension and is diffracted by red blood cells (RBCs) in the volume. The diffraction patterns are captured by a charge coupled device-video camera, linked to a frame grabber integrated with a computer. When deforming under decreasing shear stress, RBCs change gradually from the prolate ellipsoid towards a circular biconcave morphology. The elongation index as a measure of RBC deformability is determined from an isointensity curve in the diffraction pattern using an ellipse-fitting program. The advantages of this design are...

Light-transmission aggregometer using a vibration-induced disaggregation mechanism

The vibration-induced disaggregation technique of red blood cell (RBC) aggregates has been applied to design a new light-transmission aggregometer for measurement of aggregation index. For disaggregation of RBCs, the rotational shear flow in the Couette system is replaced with a simple low-frequency vibration in a disposable cavity slide glass. Using a vibration generator, one can disaggregate the RBC aggregates stored in the cavity slide glass. After applying the vibration for a specified duration, RBCs tend to reaggregate and instantaneous light-transmittance intensity is measured over time. A syllectogram (the transmitted light intensity versus time) consists of an initial decrease caused by the vibration-induced disaggregation, immediately followed by an increase in the light intensity due to RBC aggregation. The indices of aggregation are determined from the syllectogram using a curve-fitting program. The noble feature of this design is the vibration-induced disaggregation mechanism, which enables to...

Disposable biosensor for measuring red blood cell deformability using laser-diffraction technique

The laser-diffraction technique has been applied to design a microfluidic channel for measuring red blood cell deformability over a range of shear stress. A laser beam traverses a diluted blood suspension and is diffracted by RBCs in the volume. The diffraction patterns are captured by a CCD-video camera, linked to a frame grabber integrated with a computer. When deforming under decreasing shear stress in the microchannel, RBCs change gradually from the prolate ellipsoid towards a circular biconcave morphology. Both the laser-diffraction image and pressure were measured with respect to time, which enable to determine the elongation index (EI) and the shear stress. The range of shear stress is 0~20Pa and the measuring time is less than 2min. The elongation index (EI) is determined from an isointensity curve in the diffraction pattern using an ellipse-fitting program. The key advantage of this design is the incorporation of a disposable element that holds the blood sample, which enables the present system to be easily used in a clinical setting.

Disposable laser-diffraction ektacytometry to measure red blood cell deformability

The laser-diffraction technique has been applied to design a slit rheometer for measuring red blood cell deformability over a range of shear stress. A laser beam traverses a diluted blood suspension and is diffracted by RBCs in the volume. The diffraction patterns are captured by a CCD-video camera, linked to a frame grabber integrated with a computer. When deforming under decreasing shear stress, RBCs change gradually from the prolate ellipsoid towards a circular biconcave morphology. Both the laser-diffraction image and pressure were measured with respect to time. Which enable to determine the elongation index (EI) and the shear stress. The range of shear stress is 0~35 Pa and the measuring time is less than 2 min. The elongation index (EI) is determined from an isointensity curve in the diffraction pattern using an ellipse-fitting program. The key advantage of this design is the incorporation of a disposable element that holds the blood sample, which enables the present system to be easily used in a clinical setting.