7.2 Microchannels (PSA)
A layer of PSA directs fluid from each chamber towards further unit operations as
the disc spin rate is changed, these microchannels are usually 50μm in width and
maintain a constant height of 86μm due to the thickness of the PSA. The surfaces of
these channels are hydrophilic by virtue of the innate properties of PSA and
PMMA.
7.3 Microchambers (PMMA)
Relatively large chambers are cut from the PMMA to form structures responsible
for incubation, mixing and liquid storage. This layer can also contain part of the
pneumatic chamber responsible for back-pump controlled mixing.
7.4 DF Cover (PSA)
In order to seal each chamber above a layer of PSA was inserted below the
microchambers. This layer contains specific cuts to allow the passage of fluid from
Fig. 5.23 Graphical
representation of the order
in which the Lab-on-a-disk
platform is layered
5 The Centrifugal Microfluidic: Lab-on-a-Disc Platform 139