Optimal values of the objective function depending on geometrical parameters for six electrodes. Left axis: maximum values of obtained objective functions normalized by the absolute maximum value of objective function obtained in the parametric study (F/F
); right axis: voltages between rows of electrodes (U) that lead to the maximum values. All the figures show optimal solutions for each given value of the parameter shown on the horizontal axis, while the other parameters change in steps as defined in caption of Figure 3 for six electrodes. F/F
is presented in dependence of: A) the distance between rows of electrodes - d, B) distance between electrode in a row - b, C) depth of electrode insertion - z and D) angle of electric field with respect to muscle fiber orientation - ϕ.