1. Teacher : Cheng-Hsien Liu Student : Chien-Yu Chen(陳鍵瑜)
LATERAL CELL SEPARATION IN MICROFLUIDIC CHANNEL BY 3D ELECTRODE DIELECTROPHORESIS
Teacher : Cheng-Hsien Liu
Student : Chien-Yu Chen(陳鍵瑜)
Date : 06/20/2007
Reference : μTAS2006, p
Chien-Yu Chen
MSCL

2. Outline Introduction Design & simulation Fabrication
Experiment results
Conclusion
Chien-Yu Chen
MSCL

3. Introduction Dielectrophoresis (DEP) : determined by frequency
Positive DEP
Negative DEP
Most of current DEP electrodes utilize planar electrodes on the surface of the substrate to generate DEP force.
The electric field decays exponentially with the height of the channel for the planar electrode configuration
Chien-Yu Chen
MSCL

4. Design concept Inlet 3-D vertical electrode Outlet
The force balance plot of the cells in
the separation zone.
Chien-Yu Chen
MSCL

5. Simulation：side-wall vertical electrodes
Planar electrodes at bottom
of channel.
(b) Trapezoidal channel from
silicon wet etching.
(c) Electrodes embedded in
the vertical side wall of the
channel.
Electrodes at the side walls
produce uniform field in the
Chien-Yu Chen
MSCL

6. Simulation：electrical field gradient
The center of the channel：
minimum electrical field.
Close to the electrodes：
maximum electrical field.
Chien-Yu Chen
MSCL

7. Fabrication The curvature of the channel top
surface from the previous lithography
step makes it difficult for the rigid
glass cover slip to seal the channel.
The flexible PDMS sheet can
conformably seal the channels.
Chien-Yu Chen
MSCL

8. DEP forces The equilibrium points (zero DEP
The equilibrium points (zero DEP
forces) of two objects with different polarization factors can be tuned to
away from the center as shown by the
dashed line.
Chien-Yu Chen
MSCL

9. Experiment result : fabrication
The final channel with electrodes embedded
in the sidewall.
SEM of vertical electrode before channel
layer is constructed.
Chien-Yu Chen
MSCL

10. Experiment result : separation method1: both electrodes are turned on
Cells (white circles) are sorted to top channel outlet and beads (black circles)
are sorted to bottom outlet.
Left : free flow without DEP forces.
Right : with DEP separation.
Chien-Yu Chen
MSCL

11. Experiment result : separation method2: only top electrode are turned on
N115 cells repelled from the top
electrodes and flow into the
bottom channel.
HEK293 cells are released from the
top electrodes and flow into the top channel.
Chien-Yu Chen
MSCL

12. Conclusion Advantage:
Vertical electrodes in the side wall of the micro-channels to generate electric field.
The electrical field can extend to the entire channel space to avoid any dead electrical field region.
Continuous flow through separation system enables high throughput microfluidic sorting.
Disadvantage:
Need to find the frequencies to fit the two kinds of cells/beads simultaneously.
Only two kinds of cells/beads can be separated in the meantime.
Only a small amount of cells/beads can be separated.
Chien-Yu Chen
MSCL

13. Thank you !
Chien-Yu Chen
MSCL

14. Other references :
Side-Wall Vertical Electrodes for Lateral Field Microfluidic Applications, Lisen Wang, Lisa Flanagan, and Abraham P. Lee, 2007 IEEE.
Chien-Yu Chen
MSCL