Figure 3.

(A–E) The extracellular potentials (V_e) recorded from points A–E in Fig. 2 are shown. (F) shows the signal at point E (Fig. 2) while the contact pressure gradually increases (pressure ramp) by decreasing ${\sigma }_e^{\text{∗}}/{\sigma }_e={\sigma }_b^{\text{∗}}/{\sigma }_b$ from 1 on the left to 0.1 on the right. The vertical bars represent 1 mV. The horizontal bars are 100 ms in duration.