Experimental validation of theoretical models for the frequency response of atomic force microscope cantilever beams immersed in fluids

Detailed measurements of the frequency responses of a series of rectangular atomic force microscope (AFM) cantilever beams, immersed in a range of flu ids, have been performed to test the validity and accuracy of the recent th eoretical model of Sader [J. Appl. Phys. 84, 64 (1998)]. This theoretical m odel gives the frequency response of a cantilever beam, that is immersed in a viscous fluid and excited by an arbitrary driving force. Very good agree ment between experimental measurements and theoretical calculations is foun d for all fluids considered. Furthermore, a critical assessment of the well -known inviscid model is presented, which demonstrates that this model is n ot applicable to AFM cantilever beams in general. (C) 2000 American Institu te of Physics. [S0021-8979(00)02007-7].