Scan control and data acquisition for bidirectional force microscopy

Recent developments in the field of scanning-probe methods show increasing demand for controlling and storing many different experimental parameters in addition to topographic information. In order to be able to perform these experiments (e.g. force spectroscopy, surface modification, friction measurements, etc.) we have designed a versatile acquisition system. Up to four different channels can be measured and displayed at the same time. Scan parameters are under software control, and additional output signals can be easily generated to meet experimental requirements. This flexibility allows the straightforward incorporation of new conditions and modes of measurement. We use a PC/386 system based principally on commercially available electronics. As an illustration of its performance we present the application of this system to a bidirectional atomic-force microscope. With this particular microscope it is important to control lateral as well as normal forces independently. Topography and friction information can be acquired and viewed simultaneously. The versatility of this data-acquisition system also makes it well suited for a variety of other tribological/micromechanical experiments such as friction loops, force-distance curves and surface wear.