Figure 3 : FEM simulations of the QSCM mode.

From: Mapping surface charge density of lipid bilayers by quantitative surface conductivity microscopy

Figure 3

Approach curves from PNP simulations are given to a negatively charged substrate of −25 mC m−2 (a) and a positively charged substrate of +25 mC m−2 (b) with bias potentials of 100 mV (red) and −100 mV (blue). The scanning height (99% of unperturbed current) is marked with straight dashed lines in a and b, and plotted as a function of SCD in c. The difference (scanning at negative potential minus positive potential) is shown in d and a linear fit is given. The slope (mh=0.172 nm (mC m−2)−1 or mσ=5.79 (mC m−2) nm−1) of the linear fit can be used to convert observed changes in scanning height into differences in the SCD.