  A MEMS based tribometer has been developed that can be read out with
nanometer and nano-Newton resolution, approaching the resolution and
sensitivity of a friction force microscope (FFM). It can be used to study
friction of MEMS device sidewall surfaces. We find repeatable but irregular
stick-slip behavior related to the surface roughness or surface modification
(wear), depending on the normal force between the sliding surfaces. In
addition, we show that normal force modulation can decrease the apparent
friction even though the average normal force remains the same. This may be a
technologically viable way to reduce friction and wear in microscopic contacts.
