Self-sensing and self-actuating probe based on quartz tuning fork combined with microfabricated cantilever for dynamic mode atomic force microscopy

A novel probe based on a commercial quartz tuning fork and a microfabricated cantilever is presented. The U-shaped cantilever with a monolithic tip is combined with the tuning fork in a symmetrical arrangement, such that each of the two legs of the cantilever is fixed to one of the prongs of the tuning fork. The tuning fork is used as an oscillatory force sensor. Its frequency and amplitude governs that of the vibrating tip, while the cantilever determines the spring constant of the whole probe. Several probes with different cantilevers in terms of material and spring constant are studied. A typical silicon nitride cantilever has a spring constant of 0.1 N/m and those made of silicon have 1.2–319 N/m. Monoatomic terraces of highly oriented pyrolytic graphite (HOPG) was successfully imaged in the intermittent contact mode with the silicon probes. Both types of probes are suited for batch fabrication and assembling and, therefore enlarges the applications of the tuning fork based AFM.