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A NEW CELL COUNTING AND SORTING SYSTEM USING MICROPUMPS/VALVES FOR MULTI-WAVELENGTH DETECTION APPLICATIONS
Chen-Min Chang, Suz-Kai Hsiung and Gwo-Bin Lee
Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan 701
Abstract
This study presents a new chip-based cell counting and sorting system utilizing several crucial microfluidic devices for biological applications.
Micromachine-based flow cytometry has been widely investigated for cell counting/sorting applications. By using a cell sampling and
hydrodynamic focusing controller, cell sample driving and hydrodynamic focusing were generated. For the purpose of fluorescence detection,
multiple buried optical fibers were then used to transmit the light source and collect emitted fluorescence signals in/out of the chip device. Lastly, a
fluidic switching mechanism consisting of three pneumatic micro-valves were used for cell sorting.
Design and Fabrication
(a)
Cell sampling and
hydrodynamic
focusing controller
(b)
Laser
light
sources
Optical
detectors
and microvalve
controllers
(a) Schematic illustration of the integrated micro flow cytometer. (b)
Dye-labeled samples were transmitted and focused through the
detection region, excited and detected the fluorescence signals by the
optical fibers, and finally sorted by the microvalves.
Owing to the different depth between the sample flow channel and
optical fiber channels, the cell samples would be vertically focused and
pass through the optical detection area in the central of the stream, thus
passing through the core of the optical fibers.
Experimental
SEM images of microchannels on the master mold (a) and the micro
chip (b) after de-molding process, respectively.
(a)
(b)
Photograph of the flow switching generated by three micro-valve
devices.
Real-time fluorescence signals for cell counting test. Fluorescence
signals of cells labeled by (a) FITC and (b) MitoTracker® Red 580
were shown.
Conclusions
 A simple method by fabricating different depth between the flow and
fiber channels has been used to force cells flowing through the center of
the stream such that the quality of the signals could be enhanced.
 Different fluorescent dye labeled cell samples could be successfully
detected by using light source transmitted by buried optical fibers with
different wavelength. Mice oocyte and lung cancer cells labeled with
fluorescent dyes were successfully counted using the proposed chip and
sorted.
 The microfluidic device could be used for specific cell-level
applications such as profiling, counting, and sorting.
A photograph of the assembled flow cytometer system. The
dimensions of the flow cytometer system are 37cm in length,
16cm in width, and 18cm in height.
Acknowledgement
The authors gratefully acknowledge the financial support provided to this study by
the National Science Council of Taiwan under Grant No. NSC 93-3112-B-006-004.
2006
MML
MEMS design and Micro-fabrication Lab