Biomedical Engineering Reference
In-Depth Information
Figure 6.76
Sketch of a plasma extraction device using the Zweifach-Fung bifurcation law.
6.6 Conclusion
In this chapter, we have presented the governing equations for the transport of biologi-
cal substance. Two different approaches are possible depending on the size and mass
of the molecules/particles of the substance. If they are sufficiently small, the advection-
diffusion equation is the one to choose. If the particles are larger and submitted to non-
negligible gravity forces, it may be interesting to calculate individually their trajectory,
with or without the introduction of a Brownian perturbation. This is the case for the
transport of cells in a continuous flow—for separation and/or immobilization pur-
poses. To that extent, cellular microfluidics has become essential in biotechnology.
Figure 6.77
Contour plot of the
y
-velocity (transverse velocity) showing recirculating flows in the
smallest enclosures only (25 and 50
m
m). Particles are trapped differently in recirculating and nonre-
circulating regions. (COMSOL calculation).
