The electrophoretic extraction runs at field strengths of 5 Vm –1 and 10 Vm –1 ,
indicated by the bar diagrams in Fig. 9a, b, respectively.
Electrophoretic extraction results of the latex particles are shown in
Fig. 10a, b. From these figures it can be noted that when the field strength was
doubled the cell extraction was completed in a much lower number of transfers.
For instance, in case of latex particles (size 3.4 mm) at 0.05 Vm –1 field strength,
about 450 particles were extracted in 5 transfers (Fig. 10a) and when field
strength was increased to 0.01Vm –1 the similar number was extracted in 3
transfers only (Fig. 10b). This can be appreciated from the fact that in Eq. (20)
(in Sect. 2.2.3), the cell transport velocity increases proportional to the applied
electric field strength under otherwise similar conditions. An almost equal
number of cells/particles are electrophoretically extracted in each transfer step
as described by the physical model in Fig. 14 (in Sect. 2.2.4) and also by Eq. 20).
The exception for this was observed in case of smallest latex particles (size
2.6 mm, data not shown). This is due to the carry over of small particles by the
electrode gassing at higher field strength and the extent of this effect being
prominent at initial transfers where the particle concentration will be high.
The parity plot of the predicted and experimental values of the electrophoretically extracted cells/particles is shown in Fig. 11. A good agreement can
be seen for fixed blood cells but not for latex particles, especially those of lower
size range. Two main reasons for this situation are gassing near the cathode and
heating of the buffer. Gassing results in a gas/liquid dispersion instead of liquid
buffer between the electrodes, distorting the effective electric field. Further, it is
causing carryover of smaller latex particles into the top chambers, causing the
extracted particles to be higher than the predicted ones. Heating of the buffer
causes convection current, which will have more effect on smaller particles in
being swapped to the top chambers during transfers. Heating may also lower
Multistage Magnetic and Electrophoretic Extraction of Cells, Particles and Macromolecules
161
Fig. 8. Schematic diagram indicating the swapping of liquid and flow pattern during alignment and separation of the chambers
indicated by the bar diagrams in Fig. 9a, b, respectively.
Electrophoretic extraction results of the latex particles are shown in
Fig. 10a, b. From these figures it can be noted that when the field strength was
doubled the cell extraction was completed in a much lower number of transfers.
For instance, in case of latex particles (size 3.4 mm) at 0.05 Vm –1 field strength,
about 450 particles were extracted in 5 transfers (Fig. 10a) and when field
strength was increased to 0.01Vm –1 the similar number was extracted in 3
transfers only (Fig. 10b). This can be appreciated from the fact that in Eq. (20)
(in Sect. 2.2.3), the cell transport velocity increases proportional to the applied
electric field strength under otherwise similar conditions. An almost equal
number of cells/particles are electrophoretically extracted in each transfer step
as described by the physical model in Fig. 14 (in Sect. 2.2.4) and also by Eq. 20).
The exception for this was observed in case of smallest latex particles (size
2.6 mm, data not shown). This is due to the carry over of small particles by the
electrode gassing at higher field strength and the extent of this effect being
prominent at initial transfers where the particle concentration will be high.
The parity plot of the predicted and experimental values of the electrophoretically extracted cells/particles is shown in Fig. 11. A good agreement can
be seen for fixed blood cells but not for latex particles, especially those of lower
size range. Two main reasons for this situation are gassing near the cathode and
heating of the buffer. Gassing results in a gas/liquid dispersion instead of liquid
buffer between the electrodes, distorting the effective electric field. Further, it is
causing carryover of smaller latex particles into the top chambers, causing the
extracted particles to be higher than the predicted ones. Heating of the buffer
causes convection current, which will have more effect on smaller particles in
being swapped to the top chambers during transfers. Heating may also lower
Multistage Magnetic and Electrophoretic Extraction of Cells, Particles and Macromolecules
161
Fig. 8. Schematic diagram indicating the swapping of liquid and flow pattern during alignment and separation of the chambers