Plasma stencilling methods for cell patterning.

In this paper we describe plasma stencilling techniques for patterning 10 mammalian cell lines on hydrophobic and cell repellent poly(dimethylsiloxane) (PDMS), methylated glass and bacterial grade polystyrene surfaces. An air plasma produced with a Tesla generator operating at atmospheric pressure was used with microengineered stencils for patterned surface oxidation, selectively transforming the surface to a hydrophilic state to enable cell adhesion and growth. Plasma stencilling obviates the need for directly patterning cell adhesion molecules. Instead, during cell culture, adhesion proteins from the media assemble in a bioactive form on the hydrophilic regions. Critically, the removal of protein patterning prior to cell culture provides the option to also use PDMS-PDMS plasma bonding to incorporate cell patterns within microfluidic systems. Linear patterns were generated using PDMS microchannel stencils, and polyimide stencils with through holes were used for the production of cellular arrays. For the production of smaller cellular arrays, a novel microcapillary-based dielectric barrier discharge system was developed. A numerical method to characterise the cell patterns is also introduced and was used to demonstrate that plasma stencilling is highly effective, with complete patterns confined during long term cell culture (>10 days). In summary, plasma stencilling is simple, rapid, inexpensive, reproducible and a potentially universal cell line patterning capability.

Microplasma writing for surface-directed millifluidics.

Hydrophilic patterns were directly written on a hydrophobic glass substrate with a microplasma jet and used for surface-directed capillary flow operations.