Figure 6. The electrical coupling coefficient between neurons and gold mushroom shaped microelectrodes (gMμEs) as a function of the mushroom cap diameters.

Two modes of size change were considered (Fig. 5b,c): in (a) Model A, the stalk diameter was kept constant while the cap diameter was increased; in (b) Model B, the diameter of the mushrooms cap and stalk increased, keeping the gMμE cap diameter 1 μm larger than the stalk. The simulations were conducted assuming a homogeneous membrane-gMμE cleft thickness (d_j) of 10, 25 or 100 nm, for three impulse frequencies depicting membrane oscillations (10 Hz), synaptic potentials (100 Hz, both oscillations and synaptic potentials are depicted by a black curve) and action potentials (1 kHz, red) and for junctional membrane resistivity (R_jm) of 80 Ωcm². All parameters related to the dimensional changes of the simulated gMμEs (R_jm, C_jm; R_s; R_e, C_e) were integrated in the simulations using a specific membrane capacitance of 1 μF/cm².