Atomic Force Microscopy with Lateral Modulation

Friction is present in our every day lives. There are unwanted phenomena such as energy loss in the relative motion of contacting surfaces (e.g., gears, bearings or sealings). For example, the friction loss in a modern internal combustion engine is approximately 10%, in terms of indicated power at full load. In terms of fuel consumption, a savings of up to 26% has been calculated for the hypothetical case of a ‘frictionless’ engine. It is believed that potential savings in fuel consumption could be 7–9% in real engines [1]. Other parts such as sliding members would not move at all if friction were not taken care of. Estimates claim a loss of up to 1.6% of the gross national product in developed countries, that is 116 billion US-Dollars for the year 1995 in the US, due to inappropriate friction management [2]. On the other hand, friction is essential to an incredible number of processes provided by nature and civilization. If friction were not present, there would be no controlled blood flow; also, we would have difficulties in slowing down vehicles. Although the phenomenon friction does affect our being and doing at least as much as gravity or electricity does, we have not yet understood its origin. Friction has been intensely investigated in macroscopic length scales, at both, low and high velocities. Just recently, much of the tribology research has been devoted to the micrometer level and below [3, 4]. It was at the end of the 1960s when Bowden and Tabor at the Cavendish Laboratory of the University of Cambridge studied friction and tribology of two bodies contacting each other on an area as small as a few micrometers squared [5].