TriArtiJoints

Tri-ArtiJoints: Tribology of artificial joints
Axes: Surfaces & Interfaces, Engineering for Health
Leaders: Koshi ADACHI (TU) & Hassan ZAHOUANI (LTDS, ECL)
Participants: Koki KANDA (TU), Stéphane VALETTE (LTDS, ECL), Roberto VARGIOLU (LTDS, ECL), Philippe KAPSA (LTDS, ECL)
Through the years, the design of artificial joints has been improved, with the introduction of ceramic-ceramic contact, and titanium-based coatings. Indeed, as the artificial parts are implanted in human body, the use of non-aggressive materials such as titanium is highly required. These solutions, although much better than metal-metal contact, still present drawbacks in terms of impact on patient’s health. In fact, as the rubbing parts of the joint are subjected to wear during the lifetime of the prosthesis, the resulting wear particles can be scattered in the patient body, potentially causing damages because of their high hardness. Practically, it affects the length of the joint lifetime. In order to limit wear in artificial joints, the double network gel (DN gel), a kind of polymer gel containing a high proportion of water, has shown several advantages as friction material, such as low friction (μ << 0.1) with water lubrication, biocompatibility and, more importantly, mechanical strength clearly superior to usual polymer gels. Firstly, considered as a potential replacement for titanium-based coating in artificial joints, the DN gel can now be considered for various machine designs. In order to do so, many aspects of gel friction should be studied.
In this project, we may develop further the knowledge obtained during previous studies by considering the use of different subtracts materials (until now only ceramics have been used as counter materials), like metals. This may be assisted by the help of bi-photonic confocal microscope, which will eventually give information about gel structure.  Until now, all tests have been made with the help of a ball-on-disk type tribometer, which provide a circular motion. However, it could be useful to test linear friction influence.Then, the design and introduction of multi-scale texturing on or the ceramic subtract surface with the help of a Femtosecond laser may allow to study the static and dynamic contact between textured subtract and gel for several speed and load. It should enable to model the textured subtract – gel contact for different shapes of texture, allowing to know the impact on the pressure repartition. The study of DN gel surface texturing and its effect on friction may also be investigated.