Microscale tribology (friction) measurement and influence of crystal orientation and fabrication process

A microscale tribology test system has been developed at UCLA to measure friction and wear in MEMS components. Test results indicate that microscale friction may not follow Amontons' law that states the friction force is only related to the normal force with a coefficient of friction. In this study, test data indicate that the friction coefficient is not constant and it's influenced by crystal orientation, apparent contact area, MEMS material, and fabrication process, as well as the normal force applied. Explanation for the discrepancy may be related to adhesion, which is a critical issue at microscale.