Effect of annealing on structure and haemocompatibility of tetrahedral amorphous hydrogenated carbon films

Tetrahedral amorphous hydrogenated carbon (ta–C:H) films with higher sp3 C fraction were prepared using a magnetic-field-filter plasma stream deposition system. The influences of annealing on the microstructure, optical properties and blood compatibility of ta–C:H films were investigated by using Raman spectra, UV–visible optical absorption spectroscopy and tests of platelet adhesion, respectively. Results show that the graphitization of ta–C:H films is significantly promoted when annealing temperature over 400 °C, resulting in a decrease of optical band gap from 2.3 to 0.2 eV in a annealing temperature range of 200 °C–600 °C. The quantity and morphology of the adherent platelets on the surface of samples indicated that the blood compatibility of ta–C:H films significantly depend on annealing temperature, and retrogression origin of the blood-compatibility of ta–C:H films were analyzed and discussed.