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2. THICK-ELECTRODE DEP FOR SINGLE-CELL 3D ROTATION
e application of thick electrodes in microuidic chips has demonstrated the potential of
thick-electrode DEP in microuidics. However, the fabrication process of existing thick-electrode
DEP chips is rather complicated, and the electrode structure is relatively simple, which limits the
application of the thick electrodes.
e basic thick-electrode DEP composed of two thick electrodes can generate DEP force
which can translate single cells. However, it is necessary to extend the basic two-electrode struc-
ture to multiple electrodes to achieve more complex manipulations, such as single-cell rotation. In
this work, a thick-electrode DEP chip for single-cell 3D rotation was proposed by using carbon
black-PDMS (C-PDMS, a mixture of nano-conductive carbon powder and PDMS) as electrode
material, which expands the application prospect of thick-electrode DEP in microuidics.
Single-cell 3D rotation means that cells suspended in solution can rotate about X/Y/Z-axis
and play an irreplaceable role in single-cell analysis. For example, when analyzing the biophysical
properties of cells, it is necessary to perform 3D surface imaging of cells [153], and even internal
structure scanning [154]. In order to obtain accurate imaging results, it is essential to rotate the
cells about more than one axis to obtain multi-dimensional image sequences, then reconstruct 3D
model. But 3D rotation is not as easy to implement; most mammalian cells are 10–100 µm in
diameter, and easily sink in solution. Although the current cell rotation can be achieved by various
methods, such as mechanical, optical, magnetic, acoustic, or electrical means, most of the methods
can only achieve in-plane rotation. Even for several existing 3D rotation methods, there is a prob-
lem that the rotation control is unstable.
Cells are polarized in a rotational electric eld and rotated by the torque generated by electric
eld. e electrical parameters of the cells such as cell membrane capacitance and cytoplasmic con-
ductivity of the cells can be measured by analyzing the rotation spectrum. However, at present most
electro-rotation methods using planar electrodes cannot achieve 3D rotation. And the rotation
speeds are dierent when cells are in dierent positions, which makes it impossible to accurately
measure electrical parameters of the cells.
is chapter presents an “Armillary Sphere’’ type single-cell 3D rotation chip. 3D rotation is
realized by the thick-electrode multi-electrode structure, and the electrical and physical properties
are measured based on 3D rotation.
2.2 PROGRESS IN CELL ROTATION MANIPULATION
Single-cell rotation has been widely used in biological operations such as cell injection, cell nuclear
extraction, and cell cloning. With the development of MEMS technology, there have been many
reports on the methods of cell rotation such as mechanical, acoustic, electric, optical, and magnetic.
1. Mechanical methods. Generally, a suction tube and an injection needle are used for
operation. First, the cells are adsorbed by the suction tube, and then the cells are ro-