Biomedical Engineering Reference
In-Depth Information
Figure 7.8  Principle of biorecognition of macromolecules submitted to diffusion-advection in a
circulating microchannel.
At this stage we can make a distinction between two types of biochips: a first cat-
egory where the buffer liquid (the liquid containing the samples) is at rest (Figure 7.7)
or moving (Figure 7.8) inside a microchannel or microchamber. We will see later in
this chapter the difference in the process of capture.
Figure 7.9 schematizes one of the first biochip. At the beginning there were only
a few recognition sites, but nowadays some biochips have more than 10,000 recog-
nition sites and thus can recognize many DNA sequences or antigens in one run.
The presentation of biochip technology would not be complete if the detection
problematic was left aside. Both the requirements of miniaturization and of ultra
precise sensitivity have led to improvements in detection methods. Ultra sensitive
detection is a subject of many studies and is not the subject of this topic. However,
one has to keep in mind that any development of a biochip must take into account
Figure 7.9  Schematic view of one of the first “biochip”(Kharpo 1989). Miniaturization is not yet
achieved, the dimensions of the plate are 2.2 ´ 2.2 mm.
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