A kind of multi-parameter high selectivity cmuts gas sensor and its use and preparation method

Abstract

The invention discloses a multi-parameter high-selectivity capacitive micromachined ultrasonic transducers (CMUTs) gas sensor and methods for using and preparing the same. SnO2, ZnO, Fe2O3, WO3 and other semiconductor metal oxides are used as top electrodes and sensitive identification materials of CMUTs; and on the basis of the characteristics of causing the film mass and top electrode resistancechanges simultaneously after gas absorption, high-selectivity sensitivity of gas molecules with similar physical or chemical properties is realized. The resonant frequency change of the CMUT is caused by the film mass change and the change of the AC voltage amplitude between the top electrode and the bottom electrode of the CMUT is caused by the resistance change of the top electrode, so that change of the vibration amplitude of the CMUT film is caused. The high-selectivity detection of the gas molecules is realized by changes of two output parameters of the resonance frequency and the film vibration displacement amplitude. Besides, since the semiconductor oxide sensitive material can be used repeatedly under the temperature regulation, the CMUT gas sensor has high selectivity and high repeatability.

Description

technical field [0001] The invention relates to MEMS capacitive micromachining ultrasonic sensor technology and semiconductor oxide sensitive materials, in particular to a multi-parameter and high-selectivity CMUTs gas sensor and its use and preparation method. Background technique [0002] The resonant MEMS gas sensor uses the sensitive material layer coated on the surface of its resonant element to absorb the gas to be measured, which causes the quality of the resonant element to change the resonant frequency to achieve gas detection. Resonant MEMS gas sensors have the advantages of small size, high sensitivity, low mass detection limit, low power consumption, compatibility with MEMS technology, and mass production. Capacitive Micromachined Ultrasonic Transducers (CMUTs) were originally developed for ultrasonic medical imaging and treatment. Due to the small film mass and high resonance frequency, one side of the vibrating film is damped by air (the other side is vacuum), ...

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Problems solved by technology

[0003] However, the sensitive material layer and the upper electrode layer of existing CMUTs gas sensors are independently designed, the sensitive material is only used to selectively adsorb the gas to be measured, and the upper electrode is used to load electrostatic excitation to make the film vibrate

After the sensitive film is adsorbed, it only causes changes in the quality of the film, which in turn causes a change in the single parameter of the resonance frequency. When there are gas molecules with similar or similar physical or chemical properties, the sensor cannot effectively distinguish them, resulting in false alarms

Therefore, it is difficult for CMUTs gas sensors based on the current structure and working principle to achieve highly selective detection of similar or similar gas molecules to be measured.

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