S. Chung

Single red blood cell deformability test using optical trapping in plastic microfluidic chip

In this study, single red blood cell (RBC) deformability test is performed by using optical trapping in poly(dimethylsiloxane) PDMS microfluidic chip. The salient feature of this method is to provide more extensional recovery time of individual RBCs in order to tell the minor difference of RBC deformability between normal and abnormal blood.

Flow characteristics of hydrophilic/hydrophobic capillaries considering surface tension

The surface tension driven flow characteristics should be considered for the initial priming of microfluidic chips with the hydrophilic or hydrophobic surfaces. The hydrophobic capillaries have been prepared by exposing the hydrophilic glass capillaries to pure hexadecane and an octadecyltrichlorosilane (OTS) solution. The displacements and velocities of fluid menisci in two kinds of tubes are measured while changing the inlet pressures. Numerical solutions of fluidic equation show a comparable agreement with experimental results when considering the surface tension. It is also shown that partially coated hydrophobic region of capillary could be used as a passive valve.

Microfabricated fluorescence-activated cell sorter with hydrodynamic flow manipulation

Presented is a novel flow manipulation and particle detection method for microfabricated fluorescence-activated cell sorter (/spl mu/FACS). With hydrodynamic flow manipulation, our system guarantees fast and robust operation while sorting fluorescent particles. Moreover by detecting with synchronized imaging, we also developed an on-line calibration technique for accurate timing between detection and actuation.

Optofluidic packaging of silicon microchips for applications in light emitting devices

We demonstrate optofluidic packaging of silicon microchips using image processing-based optofluidic maskless lithography (IP-OFML). Optofluidic maskless lithography (OFML) is a dynamic photopolymerization technique for free-floating microstructures within a fluidic channel using a MEMS spatial light modulator. OFML via computer vision-aided image processing enables individual polymer packaging of each microdevice for protection. Furthermore, our technology is applicable to phosphor coating of light emitting diodes (LEDs).

Development of micro Hemocytometer for human erythrocyte analysis for the early detection of cancer

The relation between erythrocyte deformability and cancer has been proved in medical fields, but it is very difficult to systemize and commercialize the traditional schemes for erythrocyte deformability assessment. In this work, a desk-top type RBC Hemocytometer system with PDMS microchip has been developed for the assessment. Macrochannels with microfiltering structure in the microchip make the erythrocyte deformed, and with an UV optical array system and C language based image processing software, filter-pass-shape and filter-pass-velocity of erythrocytes are sequentially analyzed. In the comparative studies with blood from cancerous patients and control blood, we could obtain statistically acceptable data that can distinguish cancerous from control regardless of the cancer infected regions. To enhance the performance of the system, comparative studies changing the materials of the chip (silicon-glass, PDMS and PMMA) and sectional surface characteristics control have been accomplished with notable results. This RBC Hemocytometer system can be applied as a practical diagnostic apparatus in early detection of cancer.