Confocal Micro-PIV/PTV Measurements of the Blood Flow in Micro-channels - Bioanalysis Advanced Materials Methods and Devices - page 138

Fig. 9.9 Trajectory of a labelled RBC at high suspensions of cells (20 % Hct) obtained by the
proposed confocal micro-PTV system. Experiments were carried out in glass micro-channels
(adapted from [ 26 ])

9.4.3.2 RBC-WBC Interactions in Flowing Blood

The hemodynamic interaction effect of WBC on the motion of RBCs was also
investigated by using confocal micro-PTV. Figure 9.12 shows the interaction of a
RBC with the centre upper part of a WBC. Note that the RBC is located in the
in-focus plane (high intensity) whereas part of the WBC is under the in-focus plane
(lower intensity). It is possible to observe that transversal RBC displacement tends
to increase when a collision occurs with a neighbouring WBC.

9.4.3.3 Translational and Rotational Motion of RBCs

The orientation of RBCs was extensively studied at low Hct (values 1%), but this

behaviour differed from that for moderate and high Hcts. Figures 9.13 and 9.14
show the orientation of a RBC without and with an interaction, for flow close to the
wall of a glass micro-channel. By adjusting the image contrast, it was possible to
quantify both translational and rotational motion. The translational motion was
measured at the centre of the RBC whereas the rotational was measured along the
membrane: these are as shown in Figs. 9.13 and 9.14 . The RBC motion without
interaction (Fig. 9.13 ) was measured along the wall of the micro-channel. This RBC
did not suffer any interaction with a neighbouring RBC so that its translational
radial displacement was almost constant: as a result the RBC rotates as a biconcave

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