Biomedical Engineering Reference
In-Depth Information
Fig. 5 (a) Base station for optical sensor including heating for DNA amplification; (b) electro-
chemical base station (Reprinted from [
9
], permitted)
cartridge). With a maximum heating power of 9.5 W and a heat spreader made
from aluminum the heating is realized. The cooling is performed via a block of
copper, a heat sink, and a fan. Hence, the set-up allows the fast and accurate
temperature profiling necessary for a PCR-reaction to take place.
In summary, especially for antigen and serological assays the base unit has just
to hold the hardware necessary for the specific read-out. Hence, the size can be as
small as possible enabling its use as a handheld device. For example, the current
base unit for electrochemical measurements has a size of 185 9 135 9 85 mm.
For the detection and amplification of DNA the current device including the
optical read-out has a size of 250 9 210 9 314 mm (Fig.
5
).
2.5 Development and Performing an Assay
Beside the technology also the biochemistry plays an essential role for such as
system. In general, there are many different methods for integrating biology into
chips proposed in the literature. One of the most common methods is the use of
particles or beads. In these cases, the reaction between the capture molecule and
the analyte in solution takes place on the surface of such a particle. The main
advantage is that by using magnetic beads separation steps are done very fast and
efficiently. The disadvantage is that starting from a common ELISA which is
performed in a microtiter plate the surface chemistry can be different and can be
more versatile. Hence, within the Fraunhofer ivD-platform microarrays on planar
surfaces are used to target a fast transfer of already established assays into the Lab-
on-Chip system.
For that a whole value chain has to be considered starting from the right choice
of surface chemistry, the right recognition element, the set-up of the sandwich
