The high-resolution imaging technique used in liquid environments involving dynamic mode atomic force microscopy (AFM) with a frequency modulation (FM) detection technique has been newly developed on the basis of a commercial atomic force microscopy (AFM) apparatus, which is,
generally, extremely difficult because of the large decrease in Q-factor caused by hydrodynamic damping in liquids. Through various improvements and optimization, the noise density of the improved deflection sensor was 29 fm/Sqr(Hz) (f0 ~141 kHz) in liquid. In addition, the noise
level and bandwidth of the FM detector were improved to 6 mHz/Sqr(Hz) and 6 kHz, respectively. Thermal drift was successfully regulated at less than 1 nm/min in air for a sufficiently long time without any special air conditioning treatments. As a result, we succeeded in obtaining high resolution images of polypropylene sheet, Au thin film, and DNA structures in a buffer solution.