Surface Engineering of Artificial Heart Valve Disks Using Nanostructured Thin Films Deposited By Sol-gel and CVD Methods

摘要

Pyrolytic carbon (PyC) is widely used in manufacturing commercial artificial heart valve disks (HVD). Although, PyC is commonly used in HVD, it is not the best material for this application since its blood compatibility is not ideal for prolonged clinical use. As a result thrombosis often occurs and the patients are required to take anti-coagulation drugs on a regular basis in order to minimise the formation of thrombosis. However, the anti-coagulation therapy gives rise to some detrimental side effects in patients. Therefore, it is extremely urgent that newer and more technically advanced materials with better surface and bulk properties are developed. In this paper, we report the mechanical properties of PyC-HVD, namely, strength, wear resistance and coefficient of friction. The strength of the material was assessed using Brinell indentation tests. Furthermore, wear resistance and the coefficient of friction values were obtained from the pin-on-disk testing. The micro-structural properties of PyC were characterised using XRD, Raman spectroscopy and SEM analysis. Also, in this paper we report the preparation of freestanding nanocrystalline diamond films (FSND) using the time-modulated chemical vapor deposition (TMCVD) process. Furthermore, the solgel technique was used to uniformly coat PyC-HVD with dense, nanocrystalline-titanium oxide (nc-TiO{sub}2) coatings. The as-grown nc-TiO{sub}2 coatings were characterised for microstructure using SEM and XRD analysis.