Improved protein-adsorption resistance of digital microfluidic device via surface coating and structure modification

The surface of solid indium tin oxide (ITO) glass supports for samples in electrowetting system needs to be protein-resistant. Since Teflon is the most conventional coating material used to improve the contact angle between the glass and solvent, it still unable to prevent nonspecific proteins adsorption absolutely under the applied potential. In this paper, we described a feasible method that could minimize non-specific proteins adsorption most probably during droplet processing. A regular micro-scale structure was patterned by photolithography, and dielectric layer was covered on the electrodes. Finally a thin layer of Sigmacoat® was coated by physical vapor deposition. The surface characteristic of our chip was analyzed by atomic force microscopy and Contact Angle Analyzer. We found that the adhesion of bio-molecule was efficiently decreased by this modified processing, and could prevent electrolysis more efficiently.