Functional coatings for medical applications

The need to increase component performance in the medical industry brings the inevitable requirement to enhance or change the materials and processes they employ. Surface engineering is a critical part of both these industries due to the nature of the technologies. The following examples demonstrate some of the services TWI can offer:

Hydroxyapatite coating

The interaction between materials and the body is one of the major considerations when specifying biomedical materials. The intrinsic properties required of the bulk material do not always fit with the requirements for the surface. Surface engineering has already becoming an intrinsic part of the design process in bioengineering. Wear, corrosion and degradation are not always the main issues, as wear debris formation, surface interactions (surface energy, roughness, porosity, dissolution etc), bio-compatibility and sterilisation all play a very important role when specifying the material.

Example:

The life time of some implants is restricted by loosening e.g. hip and knee replacements. One of the causes is phagocytic engulfment of wear debris, which in turn causes bone erosion and loosening of the implant.

Current developments in thermal spraying have offered novel surface modifications for orthopaedic implants. Porous coatings applied to orthopaedic implants can increase their lifetime by promoting tissue growth into the implant. Through control of the pore size and the porosity type, in-growth of connective tissue and vascular formation can be obtained which delays the loosening effect.

Surface Engineering at TWI