Characterization of application specific probes for SPMs

This paper addresses the problem of determining the absolute force constant of Atomic Force Microscope (AFM) cantilevers. In the method presented, the cantilever under test is deflected against a reference cantilever of known spring constant. The relative deflection of the two cantilevers is related to their spring constants. The novelty of our approach is in the use of a micromachined reference cantilever of a precisely controlled force constant. Preliminary results show that our method is capable of measuring the force constant of cantilevers in the range of 0.1 to 10 N/m with an accuracy of better than 20%. The error is dominated by the non-linear effects in the force versus distance curves used for the measurement.