Table 1.

Contributions of different control parameters to capacitance value C.

Control Parameters	Contribution to C
Central angle θ0	Strictly proportional to C; designed to satisfy various needs
Medium thickness h	Supposed to be large enough to guarantee a large C
Inner radius of inner annular electrode rii	Not necessarily too small to guarantee a large C; designed according to the value of rio
Outer radius of inner annular electrode rio	Determining the distance between two electrodes and assumed to be small enough to guarantee a large C
Inner radius of outer annular electrode roi
Outer radius of outer annular electrode roo	Not necessarily too large to guarantee a large C; designed according to the value of roi