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3. OPTO-ELECTRONIC INTEGRATION OF THICK-ELECTRODE DEP MICROFLUIDIC CHIP
Figure 3.16 shows the optical trap process of a HeLa cell. Each power of optical ber is 100
mW. When the cell was close to the position of the optical axis, the cell was rst accelerated to the
optical axis with the highest light intensity by the axial force. en the cell was pushed away under
the action of the axial force, and since the cell was conned by the two bers, the speed of the cell
gradually decreased. Finally, it was trapped in the middle of two optical bers at equilibrium. Under
the action of the double bers, the position of the cell can be stable, which can provide a stable
spatial position for mechanical and electrical property measurement of cells.
3.6.4 SINGLECELL OPTICAL STRETCH EXPERIMENT
Since the strength of the gradient force and the axial force are related to the optical power, stretch
of the single cell can be achieved by increasing optical power. e greater optical power applied, the
larger the axial force applied to the cell, and the larger the deformation is. Mechanical properties
of dierent types of cells are dierent, and the corresponding deformations are dierent under the
same optical power.
A549 MCF7
Figure 3.17: Comparison of stretch deformation of A549 and MCF7 cells at the same power.
Figure 3.17 shows the results of stretch deformation of two cells (A549 and MCF7). It can
be found that the two cells can maintain a stable spatial position at a total power of 200 mW. When
increasing the optical power to 800 mW, both cells have signicant stretch deformations. e
maximum deformation of A549 cells reached 14%, while the deformation of MCF7 was smaller,
only 8%.
To measure the relationship between cell deformation and optical power, A549 cells were
used as an example to measure the deformations of cells at dierent optical powers, as shown in
Figure 3.18(a). e optical power is gradually increased from 200 mW to 800 mW, and the cell
deformation is gradually increased. e cell deformation and the optical power have a good linear
relationship. e stretch deformation of the ve types of cells (10 per cell sample) at 800 mW were
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measured, as shown in Figure 3.18(b). HepaRG cells have the smallest deformation (about 5%),
while A549 has the largest deformation (about 15%), and MCF7 has about twice the deformation
of normal breast cell MCF10A.
18
16
14
12
10
8
6
4
2
0
18
16
14
12
10
8
6
4
2
200 300 400 500
Laser Power (mW)
(a)
600 700 800 HeLa A549 MCF7 MCF10AHepa RG
Cell Types
(b)
Deformation (%)
Deformation (%)
Deformation
Linear Fit of Deformation
Figure 3.18: (a) e deformations of A549 cells at dierent optical powers, and (b) the deformations
of ve types of cells at 800 mW.
In addition to capturing individual cells, dual bers are capable of simultaneously capture and
stretch multiple cells. When multiple cells are located in the center of a dual bers, the cells form
a cells chain under the optical force, and increasing the optical power can simultaneously stretch
the cell chain. Figure 3.19 shows the simultaneous capture of two MCF10A cells (200 mW) and
stretch (800 mW) with deformation of approximately 4.5%.
(a) (b)
Figure 3.19: Optical stretcher captured and stretched two cells: (a) cell captured; and (b) cell stretched.
3.6 SINGLECELL MANIPULATION AND MULTIPARAMETER ANALYSIS
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