FIGURE 4.

Current map in response to indentation by an AFM cantilever. (a) For HaCaT cell: (left) representative current response to 10 × 10 grid of indentations over a 5 × 5 μm area; (right) voltage output from the AFM photodiode representing cantilever deflection, followed by current response from the highlighted row, followed by the current response from the same row after addition of GdCl₃. (b) For CHO cell. (c) High-resolution view of current response for a single indentation. The cartoon on the right shows various stages of cantilever movement corresponding to the photodiode voltage read-out. Parameters: t(ind), time over which cantilever is in contact with cell membrane; t(1/2), time between onset of current and current peak value; t(max_depth), time between the max indentation depth and current peak; t(delay), time between membrane contact and onset of current; t(i), time over which the channels are open.