Micro-mechanical resonant electrometer with ultra-high sensitivity

Abstract

The invention, which belongs to the MEMS field, discloses a micro-mechanical resonant electrometer with ultra-high sensitivity. The method comprises a mechanical structure design method of an electrometer header and a testing circuit design method. Compared with the prior art using a movable resonator charge input polar plate, the mechanical structure design enables the conversion efficiency between the electrostatic force and the axial stress to be improved; and with a micro-mechanical lever, the electrostatic force increases to improve mechanical sensitivity. When an external charge is inputted, rigidity disturbance on a resonator I increases and thus the localization phenomenon of the mode becomes dramatic. Meanwhile, the two provided resonators with different structures employ differential detection structures; the differential amplification circuit is used for detecting the amplitudes of the resonators and eliminating feed-through signals, so that the signal to noise ratio of the detection signal can be improved. In terms of the testing circuit design, a closed-loop testing plane is employed. To be specific, a signal at a detection electrode passes through a trans-impedance amplifier, a subtracter, a band-pass filter and a comparator and then is loaded at an alternating-current drive electrode to form a closed loop; rectification and filtering are carried out on two paths of outputs of the subtracter and dividing is carried out to obtain a direct-current voltage signal reflecting an amplitude ratio of two resonators. With a closed-loop drive detection circuit, the amplitude and frequency noise of the resonator can be reduced.

Description

[0001] 1. Fields: [0002] The invention relates to an ultrahigh-sensitivity micro-mechanical resonant electrometer, which is used for measuring electric charges, and belongs to the field of micro-electromechanical systems (MEMS). [0003] 2. Background technology: [0004] As an electrical sensor, electrometer is widely used in fields such as textile industry, nuclear industry, space detection and chemical analysis. The electrometer that has been reported and is recognized as the most accurate is a double-junction electrometer based on a single-electron transistor cooled by ultra-low temperature, and its resolution can reach However, due to the extremely low operating temperature (<1K) of the electrometer, it cannot be widely used. The micromechanical electrometer can work at room temperature, and has the characteristics of high sensitivity and large dynamic measurement range. At the same time, it has high precision, small size, light weight, low power consumption, low co...

AI Technical Summary

Problems solved by technology

It usually includes a chargeable gate electrode, a resonator unit and a detection circuit; when an external charge is input, an axial stress will be generated on the elastic beam of the resonator due to electrostatic attraction between the gate electrode and the resonator , the axial stress will change the stiffness of the resonant beam, thereby changing the resonant frequency of the resonator, and the amount of charge loaded on the gate electrode at this time can be obtained by detecting the change of the resonant frequency; but the sensitivity of the traditional micromechanical resonant electrometer and the resolution is not high enough

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