A piezoelectric crystal gas sensor with dual working modes

Abstract

The invention discloses a piezoelectric crystal gas sensor with two working modes. The piezoelectric crystal gas sensor comprises a quartz wafer and electrodes, wherein the electrodes include a first metal electrode, a second metal electrode and a third metal electrode, the first metal electrode and the second metal electrode are arranged on the front surface of the quartz wafer and form a staggered annular interdigital electrode structure, the third metal electrode is arranged on the rear surface of the quartz wafer, and the third metal electrode, the first metal electrode and the second metal electrode form an up-down unsymmetrical quartz crystal microbalance electrode structure. By utilizing a three-electrode structure, a mass sensitive piezoelectric resonant frequency measurement method and a resistance sensitive gas measurement manner can be combined; and the first metal electrode and the second metal electrode form the staggered annular interdigital electrode structure, so that the normal working of a piezoelectric resonant body is guaranteed, the initial resistance value of a gas sensitive material in an impedance test is decreased, and the signal to noise ratio in the impedance test is increased.

Description

technical field [0001] The invention relates to a piezoelectric crystal gas sensor, in particular to a piezoelectric crystal gas sensor with dual working modes. Background technique [0002] Quartz Crystal Microbalance (QCM) is a new type of tiny mass detection instrument that emerged in the 1960s, and its core component is the QCM mass sensor. The QCM mass sensor is a very sensitive mass sensor, and its mass determination can be accurate to the nanogram level. The QCM quality sensor is a high-resolution piezoelectric sensor formed by plating metal electrodes on the upper and lower surfaces of an AT-cut quartz wafer. Under certain external conditions, when other substances are adsorbed on the surface of the quartz crystal oscillator, according to the principle that the change of the piezoelectric resonance frequency of the quartz oscillator is proportional to the change of the mass of the substance attached to the crystal surface, the resonance frequency of the quartz cryst...

AI Technical Summary

Problems solved by technology

[0004] There is a significant problem in the application of the above-mentioned traditional technology: the performance of the piezoelectric gas sensor based on QCM is affected by the sensitive material characteristics of the metal electrode surface modification

For example, organic polymers commonly used as surface sensitive substances have good reversibility of gas adsorption and high sensitivity, but their selectivity is poor. 2 , NH 3 , CO, CH 4 , SO 2 and many other gases have response characteristics

Due to the poor selectivity, the QCM-based piezoelectric gas sensor can only achieve the purpose of measuring the concentration of a specific gas in a relatively single gas atmosphere.

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