Microcells from organ surface Bonghan corpuscles [B. H. Kim, J. Acad. Med. Sci. DPR Kor. 90, 1 (1963)] of mammals have been studied by using optical microscopy, transmission electron microscopy and immunohistochemistry. In order to further investigate their physical and electrical properties at better resolution, many different modes of scanning probe microscopy were used in this research. Their surface morphology was studied by topography imaging and error-signal imaging of atomic force microscopy and their mechanical properties were investigated by force modulation microscopy. Electrostatic force microscopy was also used for their electrical characterization.
Strictly speaking, “error signal” in this letter does not mean the real topographic data resulted from the regulation of the tip-sample distance but the overshot signal produced while the feedback system meets the set point. So this mode gives more enhanced signal at the edge or boundary of the samples where the gradient exists.