Biomedical Engineering Reference
In-Depth Information
of the membrane was measured at 11 locations using a UV laser
microscope. The relation between transmittance and thickness was
then deduced (Figs. 4.3 and 4.4).
White Light
1
0mm
a)
Blue Filter
Staircase Shaped
Membrane
1
0m
m
c)
b)
Figure 4.3
(a) Stair case-shaped casting mold. (b) Variable-thickness
urethane elastomer membrane. (c) Blue light transmittance
measurement optic system.
Measurement Locations
1
5
9
9
8
7
6
5
4
10
1
3
2
2
6
10
3
7
11
10 mm
4
8
11
2mm
0
1
a)
b)
Figure 4.4
(a) Location of thickness and blue light intensity measurements
in the variable thickness membrane. (b) UV Laser Microscope
Images: Location 1 shows the depth difference between the
base plate and the border of the membrane. Locations 2-11
show the difference between the border of the membrane and
the level of the stair case shape.
The plot describing the relation between the measurements
done with the UV laser microscope against the values of blue light
transmittance is shown in Fig. 4.5. The obtained mathematical model
of the relation is
D
= -
T
c
ln(
I
B
/
I
BMax
) (4.6)
where
I
B
is the blue light intensity at the studied location,
I
BMax
=
132.08 is the average blue light intensity in the area where there is no
membrane covering the ilter, and
T
c
=
1666.66 is the transmittance
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