Biomedical Engineering Reference
In-Depth Information
Figure 6.61
(a) View of the flow focusing. (b) Calculated streamlines and focusing using COMSOL.
A schematic of the flow streamlines can be easily obtained numerically (Figure
6.63). If
w
1
and
w
2
correspond to the widths of the two channels, the deviation of a
cell of diameter
d
initially focused along the upper wall is given by the geometrical
relation
y
w d
-
2
1
»
w
w
2
1
which leads to
2)
w
2
y w d
»
(
-
(6.110)
1
w
1
If we write relation (6.110) for two different types of cells, characterized by a
difference of diameter D
d
, the increase of vertical distance between the two trajec-
tories is
D
d w
2
1
D »
y
(6.111)
2
w
Figure 6.62
Sketch of a pinched segment device. The focusing flow forces the cells along the upper
wall, and the cells follow the streamlines passing by their gravity center.
