Effects of Environments on the Noise of Atomic Force Microscopy Cantilevers

Abstract

Thermal vibration of the cantilevers is the main source of noise in atomic force microscopy (AFM). When immersed in liquids, the dynamic behavior of the cantilevers will be significantly affected by the environment. In this study, the effects of environments on the noise of AFM were investigated. The results show that the V-shaped cantilever exhibited very low noise in high vacuum. The noise in atmospheric environment was also satisfactory. In liquid environments, the noise dramatically increased. The systematic noise was low and dependent on the distance between the tip and substrate. As the velocity increased, the noise of V-shaped cantilever was increased in a similar trend. It is also found that the variation trend was more pronounced as the liquid viscosity increased. The noise of rectangular cantilever was lower than that of V-shaped cantilever in the same environment. The present study indicates that high vacuum is an ideal environment for single molecule force spectroscopy (SMFS) due to the lower noise and higher resolution. For a better signal-to-noise ratio, both the cantilever velocity and liquid viscosity should be as low as possible. These results will be helpful when a lower noise is desired in weak force detection.