Low frequency negative stiffness capacitive sensor

Abstract

The invention relates to a low-frequency negative-stiffness capacitive sensor comprising an insulating base plate, a variable capacitor, and an electrostatic polar plate. The variable capacitor arranged at the insulating base plate consists of a first polar plate, a second polar plate, and a vibrating plate, wherein the first polar plate, the second polar plate, and the vibrating plate are arranged at intervals in parallel. The vibrating plate is clamped between the first polar plate and the second polar plate in a cantilever manner and thus a first capacitor is formed between the first polar plate and the vibrating plate; and a second capacitor is formed between the vibrating plate and the second polar plate. The electrostatic polar plate arranged on the insulating base plate includes a third polar plate and a fourth polar plate, wherein the third polar plate and the fourth polar plate are arranged at intervals in parallel. One part of the vibrating plate extends between the third polar plate and the fourth polar plate; and an electrostatic field between the third polar plate and the fourth polar plate can be adjusted. According to the low-frequency negative-stiffness capacitive sensor, the deflection degree of the vibrating plate can increase by controlling the electric field intensity between the electrostatic polar plates, so that non-linear amplification of a low-frequency signal is realized.

Description

technical field [0001] The invention relates to a low-frequency sensor for vibration detection and early warning, in particular to a low-frequency negative stiffness capacitance sensor. Background technique [0002] Traditional low-frequency sensors can be divided into magnetoelectric sensors, piezoelectric sensors, piezoresistive sensors and variable capacitance sensors according to different working principles. The structure of the magnetoelectric sensor is simple, but because of its large size, it is not conducive to mass installation. Piezoelectric sensors have high reliability, but their frequencies cannot achieve zero-frequency response due to piezoelectric characteristics in theory. Piezoresistive sensors and variable capacitance sensors can achieve smaller volumes with the help of MEMS technology. [0003] However, the structures and circuit principles of these sensors are designed based on positive stiffness. The so-called positive stiffness means that the greater...

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Problems solved by technology

However, since the acceleration component is very small at low frequencies, the output value of the sensor is also very small, thus causing the low-frequency signal of the low-frequency capacitive sensor to be submerged by the noise signal without increasing the mass

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