METHOD FOR THE FABRICATION OF HIGH SURFACE AREA RATIO AND HIGH ASPECT RATIO SURFACES ON SUBSTRATES

摘要

Thiw invention provides a method for the fabrication of surfaces of high surface area ratio on polymeric/plastic materials and their application in the control, of the wetting properties of surfacesof the transport of liquids on such fabricated surfaces, or of the separation of liquids in microchannels of said surfaces. The fabrication of surfaces of high surface area ratio comprises the following steps: (a) selection of a polymer/plastic layer which contains two or more componenents differing in their plasma etching behaviour (b) exposure of said polymer/plastic layer to an etcing plasmato provide selective removal of one polymer component versus a second plasma-resistant componenent so as to result in a randomly rough columnar-like surface. In addition, exposure of the said surface to an oxidizing plasma or to a fluorocarbon deposititng plasma renders the surface fully hydrophilic or super-hydropholic, respectively. Furthermore, the present invention provides a method for modifying the interior surface of microchannels appropriate for open tubular liquid chromatography or electochromatography or other related separation technique, based on the described methodology. Thisis due to the fact that the said hydrophilic randomlyrough columnar-like surfaces enchance device resolution due to their high surface to volume ratio. In addition, the present invention provides amethod for fasilitating dropler transport on said super - hydrophobic surfaces or transport ofliquids inside microfluidic channels of which the inside surface is modified as described in thiw invention. This is due to the fact that the said hydropholic randomly rough columnar-like surfaces combine the advantages of exhibiting very-high contact angles and low contact angle hysteresis, thus reducing the flow resistance of liquids on such surfaces. Moreover, control of droplet transport on said super-hydrophobic surfaces can easily be achieved by means of electric fields, since surfaces provide smal