Actuation and characterization of atomic force microscope cantilevers in fluids by acoustic radiation pressure

Abstract

An actuation method for atomic force microscope (AFM) cantilevers in fluids is reported. The radiation pressure generated by a focused acoustic transducer at radio frequency (rf) (100–300 MHz) exerts a localized force of controlled amplitude at a desired location on the AFM cantilever. This force can be used to measure the spring constant and other dynamic properties of the cantilever. Furthermore, by amplitude modulating the rf signal input to the acoustic transducer, the cantilever is actuated in the dc–MHz frequency range. This provides a broadband actuation and characterization method for AFM cantilevers with arbitrary geometry. The technique is demonstrated on AFM cantilevers with spring constants in the 0.01–10 N/m range using a micromachined acoustic transducer/Fresnel lens structure operating at 179 MHz in water.

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…Maeda and Senden [90] and Notley et al [91] apply a hydrodynamic force to the whole cantilever. Degertekin et al [92] use acoustic radiation focused in liquid by an acoustic lense onto the cantilever. The acoustic wave causes a known force on the cantilever.…”

High-speed atomic force microscopy for nano-visualization of dynamic biomolecular processes

“…In addition, it is difficult to produce a high-frequency magnetic field generator with high bandwidths. Acoustic radiation pressure (ARP) generated by a focused acoustic transducer with a frequency of 100-300 MHz has recently been used for the direct actuation of a cantilever in liquids [104]. The force generated by the ARP can be focused on an area of a few microns in diameter, and therefore, can be used for the direct actuation of a small cantilever.…”

Water distribution at solid/liquid interfaces visualized by frequency modulation atomic force microscopy

“…For example, Degertekin et al proposed the use of an ultrasonic wave [22,23]. Owing to the short wavelength of an ultrasonic wave, its propagation path can be controlled using a Fresnel lens.…”