39
it can be considered from two aspects: (1) the average electric eld strength in one signal period,
and (2) the standard deviation of the electric eld strength change in one signal period.
In order to quantify the above two factors, the center of the rotational chamber is selected
as the calculation probing point. e phase shift of the signals on the electrodes is 0-θ-2θ (Vp-p =
10 V, f = 1 MHz), respectively. e simulation results show that when the phase shift is less than
30° or greater than 170°, a rotational electric eld can’t be generated. Figure 2.20(a) shows the cor-
responding curve of the rotational electric eld strength when the phase shift changes from 30° to
170°. When the phase shift is 110°, the average electric eld strength reaches the maximum. Figure
2.20(b) shows the standard deviation of the change in electric eld strength in one period with
dierent phase shifts. When the phase shift is 130°, the standard deviation of the change in electric
eld strength is minimized. Considering collectively, the value of phase shift is selected as 120°.
9
8
7
6
5
4
3
4
3
2
1
0
20˚ 40˚
×10
4
×10
4
60˚ 80˚ 100˚ 120˚ 140˚ 160˚ 180˚ 20˚ 40˚ 60˚ 80˚ 100˚ 120˚ 140˚ 160˚ 180
˚
E
ms
(V/m)
Standard Deviation (V/m)
Phase Shift (θ)
(a)
Phase Shift (θ)
(b)
8.47×10
4
788
130˚
110˚
Figure 2.20: Out-of-plane rotation electrical signal conguration phase shift analysis: (a) phase shifts
correspond to the electric eld strength in one period; and (b) phase shifts correspond to the standard
deviation of the electric eld strength in one period.
DEP buer solution
In order to minimize Joule heating, it is necessary to use a solution with low conductivity and to
ensure that the solution is an isotonic solution. e DEP buer formulation used is: 82% deionized
water (w/v) +16% sucrose (w/v) + 2% PBS (w/v) with a conductivity of 36.5 mS/m.
2.5.4 3D ROTATION SPEED MEASUREMENT METHOD
Accurate measurement of cell rotation speed not only reects the relationship between rotation
speed and signal parameters, but also provides a basis for measurement of cellular electrical param-
eters. e speed measurement starts with using camera to collect the cell rotation motion, and then
convert the rotation motion video les into frame sequences. One or more cell feature points are
2.5 EXPERIMENTAL SETUP
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