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.