Humidity sensor and system based on surface acoustic waves

Abstract

The invention relates to a humidity sensor and system based on surface acoustic waves, in particular to the field of humidity sensing. According to the humidity sensor, when the humidity to be measured needs to be measured, a radio frequency signal with a specific frequency is given to the humidity sensor, resonance occurs at the first electrode and an electric signal is generated, and the electric signal is converted into an acoustic signal through an inverse piezoelectric effect under the action of the first electrode and the substrate, and thus an acoustic surface wave is generated on the surface of the substrate; the surface acoustic wave passes through the adsorption part during propagation, the dielectric constant of the adsorption part is influenced by humidity, the dielectric constant of the substrate is further changed, and at the second electrode, the substrate and the second electrode interact with each other to convert the acoustic signal into the electric signal through the piezoelectric effect, Frequency detection of the changed surface acoustic wave is realized, the amount of moisture in air absorbed by the adsorption part is obtained through change of the dielectricconstant of the substrate, and the humidity in the air to be detected is calculated.

Description

technical field [0001] The invention relates to the field of humidity sensing, in particular to a surface acoustic wave-based humidity sensor and a system. Background technique [0002] Humidity is a physical quantity that expresses the degree of dryness of the atmosphere. The less water vapor there is in a given volume of air at a given temperature, the drier the air; the more water vapor, the wetter the air. The degree of dryness and humidity of the air is called "humidity". In this sense, it is often expressed by physical quantities such as absolute humidity, relative humidity, comparative humidity, mixing ratio, saturation difference, and dew point; if it expresses the weight of water vapor in wet steam as a percentage of the total weight (volume) of steam, it is called is the humidity of the steam. The humidity that the human body feels comfortable is: the relative humidity is lower than 70%. [0003] The methods for detecting humidity in the prior art include: wet ...

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Problems solved by technology

[0005] The object of the present invention is to provide a humidity sensor and system based on surface acoustic waves in view of the deficiencies in the above-mentioned prior art, so as to solve the problem that the methods for detecting humidity in the prior art have large errors, so that the sensitivity of measuring humidity is not enough. question

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