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3. OPTO-ELECTRONIC INTEGRATION OF THICK-ELECTRODE DEP MICROFLUIDIC CHIP
5. Dual-ber optical stretcher methods. Figure 3.2(b) is a schematic diagram of the
basic structure of a dual-ber optical stretcher method [188], the principle of which
is based on two beams with a Gaussian intensity distribution to form an optical
trap. e capture of particles (such as single cells, liposomes, etc.) is achieved by the
scattering and refractive power of the beam, and then the stretch deformation is
achieved by increasing the optical power [189, 190]. Since the laser beam of the ber
is divergent, the radiation damage to the cell is small. And the optical trap formed
by the optical stretcher acts on the whole cell surface, therefore the measured results
can directly reect the mechanical properties of the whole cell. e dual-ber optical
stretcher method is also easy to combine with microuidic technology to achieve
high-throughput single-cell mechanical property measurement [191, 192].
is chapter is based on DEP and optical stretcher techniques to achieve single-cell
multi-parameter measurement. Based on the thick-electrode rotation chip of the previous chapter,
an optical stretcher was integrated with the thick-electrode structure. e mechanical properties are
measured according to the dynamic deformation during the stretching process, and the electrical
property measurement is realized by electro-rotation.
3.3 ELECTROROTATION CHIP FUNCTION EXPANSION
3.3.1 ELECTROROTATION CHIP FUNCTION EXPANSION
REQUIREMENTS
e thick-electrode DEP techniques have some shortcomings which need to be overcome.
1. Instability of spatial position when single-cell rotates. Cells are easily aected by
external forces such as ow force. Although they can adapt to position under DEP
force, they are susceptible to uids due to the small DEP force. Once the cell position
shifts, the rotation speed will be dierent because the electric eld distribution in
the horizontal direction is dierent, which aects the measurement accuracy of the
electrical parameters.
2. Single-cell manipulation. eoretically, mechanical parameters can be obtained
by measuring electro-deformation generated by DEP forces [193]. However, the
single-cell electro-rotation chip mainly utilizes nDEP force, the deformation is not
obvious when the cells are far from electrode, so that accurate mechanical deforma-
tion measurement could be very challenging. Based on the simplicity of the structure
of the electro-rotation chip, the optical stretcher which is perpendicular to the mi-
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