Effect of atmospheric-plasma treatments for enhancing adhesion of Au on parylene-c-coated protein chips

Abstract

We have developed a new passivation method of MEMS-based biosensors using parylene-c for application of an electrical protein mass detection system in a liquid environment. Because the adhesion property of gold for protein-protein interactions on parylene-c is poor, we performed atmospheric-plasma treatment of the parylene-c surface for adhesion enhancement. The surface properties of the treated parylene-c surfaces were investigated by measuring the contact angle, calculating the surface energy, observing the microstructure with a scanning electron microscope images, measuring the root-mean-square (RMS) roughness, and performing tape-test analysis. The surface energy increase of parylene-c due to the atmospheric-plasma treatment was demonstrated using the water-drop method with water and formamide. An atmospheric-plasma treatment for 120 seconds was beneficial, resulting in a surface energy increase of gold on the parylene-c films. The adhesion improvement of gold on the parylene-c was attributed to increased grain size and increased BMS roughness.