A STUDY OF HIGH ADHESION PROPERTIES OF GOLD ON SURFACE-MODIFIED FLEXIBLE POLYTETRAFLUOROETHYLENE SUBSTRATES FOR USE IN MEDICAL IMPLANTS

A study of 13.56MHz rf plasma modified polytetrafluoroethylene (PTFE) was shown to relate directly to the enhancement of polymer surface energy. Argon, oxygen and nitrogen plasmas all gave rise to enhanced polymer surface energy. In the case of nitrogen, surface energies were increased from 37 Dynes/cm to 60 Dynes/cm with exposures of less than 10Watts and power on times of only ten seconds. X-ray PhotoeIectron Spectroscopy (XPS) studies of nitrogen plasma modified PTFE, showed significant increases in oxygen and nitrogen content, small fluorine reductions, as well as significant changes in carbon functionality signatures. AFM studies revealed a large increase in average surface roughness when PTFE was plasma modified. Adhesion between thermally evaporated gold and plasma modified PTFE was dramatically increased, with z-axis pull tests exhibiting bond strengths of 120N/cm. Long lifetime testing in saline solutions indicate that the observed fine grained structure is maintained and film adhesion and quality do not deteriorate. Medical implant sensor devices were fabricated with 50 mu m features and are presently undergoing bio-compatability and chemical evaluation.