Capacitance measurement via mechanical self-excited vibration of a cantilever in the electrostatic field

This paper presents a capacitance measurement method based on the self-excited vibration of a cantilever in a steady electrostatic field. The capacitance C_b to be measured is connected to the fixed end of the cantilever and its magnitude is reflected by the pulse voltage difference across the sampling resistance. The test results indicate that capacitance C_b is in a good linear relationship with the pulse voltage difference. When the applied DC voltage is 2.5 kV, the output voltage signal can reach 482.9 V and the measured capacitance to voltage ratio is 14.2 fF/V. The test results also show that the proposed method is insensitive to the geometrical and material parameters of the vibratory cantilever. The lower limit of the capacitance measurement is determined by the parasitic capacitance C_{b, para}, and its characteristic provides a new approach to measuring the parasitic capacitance of isolated conductors at fF level.