Biomedical Engineering Reference
In-Depth Information
Figure 4.37
Principle of dispensing an electrode.
4.3 Multiphase Microflows
4.3.1 Introduction
Two-phase or multiphase microflows have gained a lot of attention recently. They
have proved to be unavoidable for applications like extraction of targets from a
carrier fluid, or for making microemulsions, and above all for encapsulation. This
section presents the generality of two-phase microflows. The next section focuses
on droplet microfluidics.
4.3.2 Droplet and Plug Flow in Microchannels
It is common to have two immiscible fluids flowing in a microchannel. They can be
a gas and a liquid or two immiscible liquids, like water and oil. In such a case, it is
common to speak of the water or oil phase. Often, the biologic targets are trans-
ported by the aqueous phase; the second organic or gas phase is used to separate the
droplets or plugs. There are different two-phase flow regimes, but the most common
are droplet and plug flows (Figure 4.38).
Figure 4.38
Microdrops and plugs in a capillary tube.
