PDMS device

Fig. 6. a PDMS device for sol-gel synthesis of core shell Si02-Ti02 colloids, b SEM image of synthesized colloids, c TEM image of colloids TiC>2 is shell-visible (Khan 2006)... 

Figure 4.6 PDMS microchip, (a) PDMS microchip with (E) a graphite-coated emitter tip, (S) reservoirs for sample, (SW) sample waste and (B) buffer, (b) Double-T injection cross of the PDMS-device (1) channel path and (2) buffer flow [8].

FIGURE 2.13 Electron micrograph showing the sample injection region of the PDMS device. Channel cross section, 50 pm (width) x 20 pm (height). The geometrical features of the channel junction result from the anisotropy of the wet etching process of the Si master [159]. Reprinted with permission from the American Chemical Society. 

A micromixer in which the fluid can be stirred by periodically pumping through the side channels is shown in Figure 3.45 [481]. The periodic perturbation applied via the side channel allows liquids A and B to be mixed. Other mixers based on oscillating pressure-pumped flow have also been reported [482,483]. Two droplets (600 pL) were merged and mixed by a push-pull (shuttling) method in a PDMS device consisting of a hydrophobic microcapillary vent (HMCV) [364]. 

In cell culture, 02 is needed. The amount of 02 that could be supplied into a PDMS device per day (Finax) can be estimated by the equation... 

Thiebaud, P., Lauer, L., Knoll, W., Offenhausser, A., PDMS device for patterned application of microfluids to neuronal cells arranged by microcontact printing. Biosens. Bioelectronics 2002, 17, 87-93. 

For less-motile bacteria, longer imaging times may be needed. The advantage of the PDMS device is that it greatly reduces evaporation and allows for extended imaging on the microscope. 

The PDMS devices can be kept in purified water for later use. However, storage increases the chances of air bubbles and dirt getting trapped inside the channel. 

Bonding of PDMS devices, in general, is much simpler than the thermal bonding required for glass devices. To obtain a reversible bond between PDMS and any number of complimentary substrates... 

---