Biomedical Engineering Reference
In-Depth Information
Figure 5.12
Biodiagnostic detection device. Left: view of the main and detection microchambers.
Right: enlargement of the detection chamber (courtesy of LETI/Biomérieux).
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5.3.7 Diffusion Inside a Microchamber
The standard procedure for biodiagnostic DNA recognition is the polymerase chain
reaction (PCR). However, recently there has been development of new microde-
vices to directly detect DNA by fluorescence in microchambers (Figure 5.12). The
principle is to bring the DNA strands inside the microchamber (for example using
magnetic particles) and then let them diffuse so that the DNA strands can hybrid-
ize on a labeled surface. Because the system must be very sensitive and work with
very few DNA strands, it is important to block any back diffusion towards the inlet
channel.
A very simple analysis of the diffusion inside the microchamber may be done by
considering the diffusion equation in the 2D geometry defined by Figure 5.13, and
using standard numerical techniques. The results presented in Figure 5.14 have been
Figure 5.13
Schematic view of the computation domain.
