Figure 4. Key instrumentation in a patch-clamp set-up and an equivalent circuit for a pipette sealed on a cell membrane patch containing a single ion channel molecule.

While a gap is shown between the pipette tip and the cell membrane to show the effect of finite R_seal, useful patch-clamp recordings require isolation of the membrane patch under the annulus of the pipette through covalent interactions between the pipette tip and cell surface. See the text for discussion of each component in this drawing.

A/D: Analog-to-digital; C_cell: Equivalent total capacitance of the cell membrane; R_cell: Equivalent total resistance of the cell membrane; R_chn: Resistance of a single channel molecule; R_pip: Pipette resistance; R_seal: Seal resistance.