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CHAPTER 2
ick-Electrode DEP for Single-Cell
3D Rotation
2.1 INTRODUCTION
At present, most of the DEP chips are based on 2D planar electrodes, which have problems such as
fast electric eld attenuation and small working distance. To solve the limitations, thick electrodes
have been widely used in microuidics in recent years because of its large working areas and uni-
formity of electric eld in the vertical direction [148, 149].
With the development of MEMS technology, researchers have proposed a variety of
thick-electrode microuidic chips with dierent functions. For example, in cell-sorting applica-
tions, Wang et al. [150] designed a thick-electrode microuidic chip to achieve cell sorting (Figure
2.1(a)). e thick electrodes are deposited on the SU-8 microstructure by electrodeposition, but the
fabrication is complicated, time-consuming, and costly. Li et al. used a method of heating low-melt-
ing metal microspheres in a microchannel to make thick electrodes and used them for cell sorting
[151]. However, this method has insucient processing precision, and the shape of the metal after
melting is less controllable, and it is easy to overow the ow channel. ick-electrode DEP has
also been used for particle separation. For example, Kang et al. designed a 3D embedded electrodes
microuidic chips for particle separation (Figure 2.1(b)) [152].
(a) (b)
Output I
Inpu
t
Output II
Electrode II
Electrode I
y
z
x
Figure 2.1: Microuidic chips based on thick electrodes: (a) a thick-electrode microuidic chip for cell
sorting [150]; and (b) A thick-electrode microuidic chip for particle separation [152], based on and
used with permission from Elsevier.
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