Confocal Micro-PIV/PTV Measurements of the Blood Flow in Micro-channels - Bioanalysis Advanced Materials Methods and Devices - page 132

9.3 Confocal Micro-PIV/PTV System

9.3.1 Conventional Micro-PIV System

A conventional micro-PIV system consists essentially of a microscope, an objective
lens, optical filters, a light source for flow illumination and a high speed camera.
Figure 9.4 gives a schematic illustration of a conventional micro-PIV system.
Briefly, the light enters the microscope and is reflected 90 upwards by a dichro-
matic mirror to be transmitted through the objective lens which illuminates the
entire flow volume. The objective lens collects the light emitted from the particles
which goes back to the dichromatic mirror and to a high speed camera to record the
signals from the trace particles. Finally, the recorded images are transferred to a
computer to use a PIV post-processing method such as the cross-correlation tech-
nique. It is worth mentioning that the resolution of a micro-PIV system is influenced
by several factors such as: out-of-focus particle images due to the volume illumi-
nation, and density and size of the tracer particles. By using a confocal system, most
of the out-of-focus particles can be removed, consequently reducing the errors
generated in the velocity field measurements.

9.3.2 Confocal Micro-PIV System

A confocal micro-PIV system consists usually of an inverted microscope combined
with a confocal scanning unit (CSU), a high resolution objective lens, a high power

Microchannel

Syringe
pump

High speed
camera

Light
source

Mirror

Laser

Inverted microscope

PC

Fig. 9.4 Experimental setup of a conventional micro-PIV system.