A review on non-contact frequency-modulation AFM and its application in biology

Performance and imaging mode of atomic force microscope (AFM) have been in continuous development and now AFMs are operated in contact mode, tapping mode, or non-contact frequency-modulation mode. A non-contact frequency-modulation AFM achieves high resolution, and the sample distortion is greatly reduced because of the very small interaction force between the tip and sample. In this paper, we give a review on high resolution imaging of non-contact frequency-modulation AFM in vacuum and in physiological condition for better application in biology. Applications of the system in structural biology using the DPPC bilayer and IgM are given as samples. (authors)