Figure 1.
A spherical particle with radius R, permittivity and conductivity
, which is covered by a uniform layer of thickness
, permittivity
and conductivity
, and surrounded by a solution of permittivity
and conductivity
.
Figure 2.
Illustration of an ODEP system.
Experimental setup for manipulating cells with opto-electrokinetic device.
Figure 3.
The opto-electrokinetics device (OEK).
An illustration of the OEK used to manipulate biological cells. The patterned optical image is focused by a condenser lens and projected onto the hydrogenated amorphous silicon surface.
Figure 4.
DEP force acting on the peripheral WBCs.
Three optical images were projected onto an a-Si:H surface. A 10 µm diameter micro polystyrene bead acted as a control. (A) Peripheral WBCs experienced a negative DEP force at the applied frequency of 50 kHz and a voltage of 10 Vpp. They lay in the dark-field region and between the square and the ring image. (B) When the frequency was 200 kHz, 10 Vpp, a positive DEP force caused the cells to shift into the image. The polystyrene beads stayed in the same position in both cases because they only experienced a negative DEP force in 0.2 M sucrose solution.
Table 1.
The response of white blood cell samples in the DEP field.
Table 2.
The response of melan-a cells and macrophages to the DEP field.
Figure 5.
Illustration of cell rotation in an OEK.
The cells in the dark-field region rotated toward the 30 µm spot image. Their z-axes were normal to the positive DEP force vectors. The axis of rotation was at the x-axis perpendicular to the E-field.
Figure 6.
Time lapse for a melan-a cell completing one revolution with the applied frequency of 40 kHz at 6 Vpp as recorded by a CCD camera after grey-scale treatment. The similarity coefficients were 1 (A), 0.9973 (B), 0.9964 (C), 0.99656 (D), 0.9951(E) and 0.9963(F). Images were taken 0.155 seconds apart. The rotational speed was recorded as 65 rpm.
Figure 7.
Rotational speed of the melan-a and lymphocytes in 0.2 M sucrose solution versus applied voltage from 0 Vpp to 20 Vpp at 40 kHz.
Figure 8.
Rotational speed of the melan-a in 0.2 M sucrose solution versus applied frequency from 40 kHz to 1 MHz at 20 Vpp.
Figure 9.
Rotational speed of the lymphocytes in 0.2 M sucrose solution versus applied frequency from 40 kHz to 1 MHz at 20 Vpp.
Table 3.
Rotation behavior of white blood cell samples in the DEP field.