Micro-patterned PDMS

De Silva MN, Desai R, Odde DJ. Micro-patterning of animal cells on PDMS substrates in the presence of serum without use of adhesion inhibitors. Biomed Microdevices 2004 6 219-22. 

Another possible application using the hierarchical nature of the wrinkles has been discussed by Efimenko and coworkers [46], They treated a mechanically stretched PDMS sheet with UV-ozone in order to create a stiff surface layer. A detailed analysis with AFM and profilometry of the wrinkles after releasing the strain showed that the wrinkling patterns are hierarchical themselves. They observed up to five generations of different wavelengths with different periodicities. These features made so structured surfaces valuable candidates for separate colloidal particles of different sizes by acting as a micro fluidic sieve. A suspension... 

In order to fuUy exploit the scalability of DE actuators, it necessary to be able to pattern electrodes on the micro scale as well. Rosset el al have explored the use of ion implanted metal electrodes in PDMS [221-224]. Their results show that conductivity can be maintained for strains up to 175% and can remain conductive over 10 cycles at 30% strain. This is of particular importance for MEMS microfluidic devices where the DE micro-actuators could be used as micro-pumps. The ion-implanted films maintained high breakdown fields (>100 MV m ) while the Young s modulus increased by 50-200% depending on the dose. 

The efficiency of the micro orifice-based fusion method has been experimentally demonstrated as a high-yield (>90 %) fusion process [6]. A microfluidic device consists of two microfluidic channels separated with micro slit array was fabricated in PDMS (Fig. 4). The fabricated microfluidic channel was integrated with a substrate with patterned electrodes. Two different types of cells were introduced into each microfluidic channel. Cell pairing was achieved by using dielectrophoresis and... 

In recent years, self-assembly was successfully applied in micrometer-scale structures. Self-assembled monolayer (SAM) [11] is the representative example of self-assembly microfabrication, in which stufaces consist of a single layer of molecules on a substrate. SAMs can be prepared simply by adding a solution of the desired molecule onto the substrate surface and washing off the excess. The technique was utilized on the metal substrates with PDMS stamps to form the combined system for controlling of crystal nucleation [12]. Another example involves a fluidic technique based on patterned hydrophobic SAMs and capillary forces to self-assemble micro-fabricated sihcon blocks onto silicon and quartz substrates [13]. 

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