Plasma processing for polymeric microfluidics fabrication and surface modification: Effect of super-hydrophobic walls on electroosmotic flow

• Published in: Microelectronic engineering Vol. 85; no. 5-6; pp. 1124 - 1127
• Main Authors: Vourdas, N., Tserepi, A., Boudouvis, A.G., Gogolides, E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-2008; Elsevier Science
• Subjects: Applied fluid mechanics; Applied sciences; Electronics; Electroosmotic flow; Exact sciences and technology; Flow in superhydrophobic channels; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); Microelectronic fabrication (materials and surfaces technology); Microfluidics; Physics; Plasma etching; PMMA; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Superhydrophilic; Superhydrophobic; Electroosmotic flow; Superhydrophobic; PMMA; Plasma etching; Flow in superhydrophobic channels; Microfluidics; Superhydrophilic; Performance evaluation; Fluid mechanics; Mass production; In situ; Roughness; Plasma assisted processing; Etching rate; Hydrophobicity; Coatings; Flexibility; Surface effect; Microelectronic fabrication; Anisotropy; Surface properties; Resist
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2007.12.032

We report on the fabrication and electrokinetic characterization of poly-methyl methacrylate (PMMA) microfluidics by deep O2 plasma etching, utilizing a photosensitive poly-(dimethyl siloxane) (PDMS) as a resist (in situ mask). The mass production amenability, the high throughput without the use of mold, the dry character along with the flexibility to control surface properties towards specific demands are some of the advantages of this method. Intense ion bombardment ensures high etch rates (∼1.5μm/min) and anisotropy. A PMMA lid was thermally bonded to the plasma fabricated microchannel under 1.8kg/cm2 at 120°C. Surface roughness and hydrophilization are some unique features induced by plasma processing, affecting the electrokinetic performance of the microfluidic and resulting in relatively high electroosmotic flow (EOF) mobilities of 2.83×10−4cm2/Vs. Teflon-like coating deposition on the engraved part modified the surface into a super-hydrophobic and resulted in even higher EOF mobility (3.89×10−4cm2/Vs), thus proposing an alternative means in microfluidic surface modification and EOF control.