50
2. THICK-ELECTRODE DEP FOR SINGLE-CELL 3D ROTATION
2.7.2 KEY FACTORS IN ELECTRICAL PROPERTY ANALYSIS
e rotation spectrum is mainly determined by four dielectric parameters (permittivity and con-
ductivity (ε
mem
, σ
mem
) of the cell membrane and permittivity and conductivity (ε
cyto
, σ
cyto
) of the
cytoplasm). e dielectric parameters of dierent cells are usually dierent. Without loss of gener-
ality, the cell diameter is set to 15 µm, the cell membrane thickness is set to 20 nm according the
literature [170], and the rotation spectrum curves related to these four parameters can be plotted
according to the parameter settings in Table 2.2.
Table 2.2: Cell dielectric parameter settings
Conductivity of
Cell Membrane
σ
mem
(μS/m)
Permittivity of
Cell Membrane
ε
mem
Conductivity of
Cell Cytoplasm
σ
cyto
(S/m)
Permittivity of
Cell Cytoplasm
ε
cyto
Figure 2.34(a) 1–10
12ε
0
0.4
100ε
0
Figure 2.34(b)
10
1–20ε
0
0.4
100ε
0
Figure 2.34(c)
10
12ε
0
0.1–1
100ε
0
Figure 2.34(d)
10
12ε
0
0.4
10–100ε
0
At the whole frequency range, the eect of conductivity of cell membrane on the rotation
spectrum is negligible (Figure 2.34(a)). When the frequency is < 100 MHz, the eect of permit-
tivity of cytoplasm on the rotation spectrum is negligible (Figure 2.34(b)). When the frequency is
< 100 MHz, permittivity of cell membrane and conductivity of cytoplasm have a signicant eect
on the rotation spectrum (Figure 2.34(c, d)). is experiment was limited by the signal generator
frequency range and the maximum frequency was 20 MHz. erefore, the method of extracting
the dielectric properties of cells can’t essentially distinguish conductivity of cell membrane and
permittivity of cytoplasm. erefore, in the experiment, the two parameters were set to 100ε
0
and
10
-6
S/m according to the literature [165].
e electrical parameters of the cell solution also have an eect on the cell rotation spectrum.
e permittivity and conductivity of the cell membrane were set to 12ε
0
and 10 µS/m, respectively,
and the permittivity and conductivity of the cytoplasm were set to 60ε
0
and 0.4 S/m, respectively.
Figure 2.35 shows the eect of solution permittivity and conductivity on the rotation spectrum.
It can be seen that the permittivity of the solution has signicant inuence on the rotation
spectrum only when the frequency is greater than 100 MHz, and has almost no eect on the ro-
tation spectrum when the frequency is lower than 100 MHz. e change in conductivity of the
solution has obviously inuence on the rotation spectrum over the whole frequency range, so a
lower conductivity (36.5 mS/m) solution was used in the experiment.
51
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
σ
med
=36.5mS/cm
ε
med
=60ε
0
ε
mem
=12ε
0
σ
cyto
=0.4S/m
ε
cyto
=60ε
0
σ
med
=36.5mS/cm
ε
med
=60ε
0
σ
mem
=10µS/m
σ
cyto
=0.4S/m
ε
cyto
=60ε
0
σ
med
=36.5mS/cm
ε
med
=60ε
0
σ
mem
=10µS/m
ε
med
=12ε
0
ε
cyto
=60ε
0
σ
med
=36.5mS/cm
ε
med
=60ε
0
σ
mem
=10µS/m
ε
med
=12ε
0
σ
cyto
=0.4S/m
σ
mem
=1µS/m
σ
mem
=2µS/m
σ
mem
=5µS/m
σ
mem
=8µS/m
σ
mem
=10µS/m
ε
mem
=1ε
0
ε
mem
=2ε
0
ε
mem
=5ε
0
ε
mem
=8ε
0
ε
mem
=10ε
0
ε
mem
=20ε
0
σ
cyto
=0.1S/m
σ
cyto
=0.2S/m
σ
cyto
=0.4S/m
σ
cyto
=0.8S/m
σ
cyto
=1S/m
ε
cyto
=10ε
0
ε
cyto
=20ε
0
ε
cyto
=40ε
0
ε
cyto
=60ε
0
ε
cyto
=80ε
0
ε
cyto
=100ε
0
10
4
10
5
10
6
10
7
10
8
10
9
10
10
10
4
10
5
10
6
10
7
10
8
10
9
10
10
10
4
10
5
10
6
10
7
10
8
10
9
10
10
10
4
10
5
10
6
10
7
10
8
10
9
10
10
Frequency (Hz)
Frequency (Hz)
Frequency (Hz)
Frequency (Hz)
Im[K
CM
]Im[K
CM
]
Im[K
CM
]
Im[K
CM
]
(a) (b)
(c) (d)
Figure 2.34: Simulation and analysis results of the inuence of four electrical parameters on the rota-
tion spectrum (K
CM
coecient): (a) eect of cell membrane conductivity; (b) eect of permittivity of
cytoplasmic; (c) eect of cell membrane conductivity; and (d) eect of conductivity of cytoplasm.
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
σ
med
=36.5mS/m
σ
mem
=10µS/m
ε
mem
=12ε
0
σ
cyto
=0.4S/m
ε
cyto
=60ε
0
ε
med
=60ε
0
σ
mem
=10µS/m
ε
mem
=12ε
0
σ
cyto
=0.4S/m
ε
cyto
=60ε
0
ε
med
=10ε
0
ε
med
=20ε
0
ε
med
=40ε
0
ε
med
=60ε
0
ε
med
=80ε
0
ε
med
=100ε
0
σ
med
=0.01S/m
σ
med
=0.05S/m
σ
med
=0.1S/m
σ
med
=0.5S/m
σ
med
=1S/m
σ
med
=2S/m
10
4
10
5
10
6
10
7
10
8
10
9
10
10
10
4
10
5
10
6
10
7
10
8
10
9
10
10
Frequency (Hz)
Frequency (Hz)
Im[K
CM
]
Im[K
CM
]
(a) (b)
Figure 2.35: Eect of cell solution on the rotation spectrum (K
CM
coecient): (a) eect of solution
dielectric constant; and (b) eect of solution conductivity.
2.7 CELLULAR ELECTRICAL PROPERTY ANALYSIS
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