Figure 11.

(a) The overall membrane electrical behavior is often more complex than a resistor and a capacitor in parallel. The electrolytes resistance Re and the capacitance of the electrical double layer C_GCS are also present in the electric circuit, but the membrane impedance typically dominates the response. However, the double layer itself and its surrounding can be divided into tuned impedance layers depending on the hypothesis in question and each layer is detected through varying frequencies. (b) A common electrical circuit when investigating channel-forming proteins in membranes: the electrolyte solution resistance, R_e, in series with membrane capacitance, C_m, and membrane resistance, R_m. The latter is variable in the presence of membrane-protein activities. (c) Copied from “Korman, C. E., et al. (2013). “Nanopore-spanning lipid bilayers on silicon nitride membranes that seal and selectively transport ions.”29(14): 4421-4425. Membrane conductance was tracked via EIS investigating the effect of Gramicidin on POPC membranes.