Powerpoint Templates Page 1 Powerpoint Templates Optically induced flow cytometry for continuous microparticle counting and sorting Student: Chin – wei

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Optically induced flow cytometry for continuous microparticle counting and sorting

Student: Chin – wei 　 HsuProfessor: Yi-Chu Hsu Class: Nano-electro mechanical SystemsDate ： Nov 04 2011


Outline

IntroductionChip designResultsConclusion


Introduction• This enables it to continuously count and to sort micro particles based on optically induced dielectrophoretic(ODEP) forces.

• Using 20.9 and 9.7um polystyrene microparticles, the average light intensity were about 63.67 and 8.80 units,with a coefficient-of-variation (CV) of 7.46 and 25.57%, respectively

• The development of the OIFC device is a major advancement in the design of micro particle counting and sorting devices


(a)Schematic illustration of the optically induced flow cytometer chip for counting and sorting of microparticles. (b) Conceptual illustration of continuous separation of microparticles.

Chip design


An alternating current (ac) voltage is supplied between the top and bottom ITO layers. Since amorphous silicon has a high electric impedance prior to illumination, it causes a weak, uniform electric field inside the liquid layer.

Thus, the microparticles do not sustain any non-uniform ODEP force. When a projected light source hits the amorphous silicon layer, electron–hole pairs are excited, thus decreasing the impedance of the amorphous silicon layer by 4 to 5 orders of magnitude


(c)The negative ODEP force is induced by an ac voltage when illuminating an amorphous silicon layer to form a non-uniform electric field(d)Exploded view of the microfluidic chip.


After the fabrication processes, the ITO glass with the SU-8 structures were then bonded with another ITO glass with the photoconductive layer by using an epoxy glue. A Teflon tube was connected with the upper ITO glass to mechanically drilled via holes using epoxy glue


(a)Simplified fabrication process for the microfluidic chip(b)SEM image of the etched optical fiber inserted in the SU-8 structure. The diameter of the etched optical fiber is 55m.


Experimental setup for counting, analyzing and sorting of microparticles by using the optically induced flow cytometer chip


Results

• In this study we proposed a new device utilizing the ODEP force to focus the particles in the sample flow and to sort the microparticles dynamically into the subsequent virtual channels.

• A pair of buried optical fibers were inserted into the device to count the number of the microparticles. Note that all these functions were achieved without using any lithography process to pattern the metal electrodes.


(a)Microparticles are focused by virtual electrodes induced by illuminating the photoconductive layer to generate a negative ODEP force.

(b)When the virtual channel is increased to 130um, the trajectory of the microparticles is an arc line as marked in the figure. While the microparticles passed though the optical fiber, the ODEP switch is activated


(c)Smaller microparticles are switched upwards

(d)Larger microparticles are switched downwards


Fig. 6. Microparticles are continuously separated by weaker and stronger virtual electrodes induced by different illumination intensities.


Conclusion

Experimental data showed that a perfect total count of 83 particles was achieved for 20.9m diameter microparticles.For 9.7um microparticles, 77 particle counts, with 3 missed counts, were observed.

The intensity of the detection signals was reasonably stable due to the fact that microparticles were aligned in the vertical direction inside the fluid channel.

Finally, the 9.7 and 20.9um microparticles were successfully sorted by an ODEP switch.

continuous microparticle separator was also demonstrated by using different illumination intensities.


Thank you for your attention

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Powerpoint Templates Page 1 Powerpoint Templates Optically induced flow cytometry for continuous microparticle counting and sorting Student: Chin – wei