Biomedical Engineering Reference
In-Depth Information
Fig. 9.6 Comparison of particle images from ( a ) conventional and ( b ) confocal micro-PIV system
at 20
m
m depth for pure water
decreases resolution making it difficult to identify the tracer particles within the
flow. Note that the conventional microscopic images were obtained by using an
epifluorescent microscope equipped with a mercury lamp and colour filters. These
images may be improved by using a more powerful light source, such as a laser or
metal halide.
9.4 Confocal Micro-PIV/PTV Measurements and Results
This section shows the most recent studies on blood flow behaviour in micro-
channels performed by our confocal micro-PIV/PTV system. The main emphasis
is on the confocal micro-PIV/PTV results obtained from both glass and
polydimethylsiloxane (PDMS) micro-channels.
9.4.1 Working Fluids, Micro-channels, Experimental
Set-up and Image Analysis
Confocal micro-PIV measuements were performed with different working fluids
such as physiological saline (PS) with fluorescent trace particles, and in vitro blood
containing trace particles and human RBCs with a hematocrit (Hct) up to 20%.
Confocal micro-PTV experiments were carried out also with different working
fluids such as dextran 40 (Dx-40) containing about 3% Hct up to 35% Hct of
human RBCs. For this latter system, rather than employing fluorescent particles
labelled RBCs were used to study the flow in micro-channels. A full description of
the procedure for labeling human RBCs can be found in Lima et al. [ 28 ].
For both confocal systems experiments were performed with different kinds of
micro-channels, such as 100-
m circular and square borosilicate glass
micro-channels as fabricated by Vitrocom (Mountain Lakes, NJ, USA) [ 23 , 25 , 31 ].
By using a soft lithographic technique it was also possible to fabricate rectangular
m
m and 50-
m
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