TABLE OF CONTENTS Biotechnology is closely linked to microfluidics. Biological targets are nearly always transported by a buffer fluid or carrier fluid, as well in vitro and in vivo. In the human body, any bio-MEMS has to deal with body fluids. In in vitro microsystems, the target molecules/particles are nearly always transported by a buffer fluid for many reasons: first, the target molecules/particles are most of the time extracted from a liquid (e.g., DNA and cells); second, the biochemical reactions on these targets are performed in an aqueous environment; and third, confinement of the targets is easier in a liquid than in a gas. Very few examples of biotechnological microsystems exist that do not require the use of microfluidics. One counterexample might be the "electronic nose," where detection of target molecules transported by ambient air is done directly on a dry contact surface by mass spectrometry. Even for bacteria carried by air, like legionella, it is now thought to extract and concentrate them in a water base.
In this chapter, we deal with liquid microflows, and we will not consider gas flows. For the reader whose concern is gas microflows, useful information can be found in [1].
If liquids are the most frequent carrier of microparticles, the flow pattern can be very different. In the next section, we present the different patterns of microflows currently used in biotechnology.
In biotechnology, microfluidics is present under different...
