Biomedical Engineering Reference
In-Depth Information
Figure 6.43
Superposition of the location of particles at different times.
6.4 Separation/Purification of Bioparticles
Separation and purification of bioparticles are required for many different applica-
tions and targets (purification of proteins, separation of DNA strands by length,
and so forth). Several techniques have been developed to perform these processes.
We present here, mostly qualitatively, the principle of field flow fractionation and
chromatography columns.
6.4.1 The Principle of Field Flow Fractionation (FFF)
Field flow fractionation (FFF) is a group of techniques to separate different types of
particles [18]. The principle is shown in Figures 6.49, 6.50, and 6.51. The principle
here is that particles in a liquid flow separate according to their physical properties
such as volume, mass, electric charge, or magnetic moment. Suppose a horizontal
flow drag force depends on the size of the particle. If another force field is applied
vertically (such as gravitation), the particles will gather at different places on the
lower solid wall.
Figure 6.44
(a) Image of the particles in a cross section. (b) Radial distribution of particles
corresponding to (a).
