Novel frictionless approach mechanism for a scanning tunneling microscope

A novel coarse approach mechanism for a scanning tunneling microscope (STM) is described. Any approach mechanism, which brings a tip close to the sample, suffers from dry frictional force, which makes positioning of the tip over the sample rather difficult. In this unique design, we have reduced the friction to a minimum by oscillating the normal force on the sliding sapphire surfaces. This technique allows us to precisely position the tip over the sample after traveling a distance greater than 100 μm while maintaining a compact STM design. This technique of reducing friction is also very useful in an automatic inertial approach mechanism (or “stick–slip” motor), where the motion often becomes clamped due to excessive friction. We believe that this technique will be extremely useful for applications where high precision positioning is required.