“…The image in the cross section of DNA is dominated by the tip feature because DNA feature (2 nm) is sharper than the tip (nominal 20 nm). The width of DNA in the image under AFM could not be narrowed by using carbon nanotube tip [10] because the diameter of a carbon nanotube tip is still much larger than that of DNA. The image of both DNA and the tip on the z-direction is the same, which can be understood by referring in Fig.…”