Fluid flow velocity sensor and system based on surface acoustic waves

Abstract

The invention relates to a fluid flow velocity sensor and system based on surface acoustic waves, in particular to the field of fluid sensing. The fluid flow velocity sensor comprises a substrate, a first electrode and a second electrode, when the flow velocity of a fluid to be measured needs to be measured, a radio frequency signal with a specific frequency is inputted to the sensor, resonance occurs at the first electrode to generate an electric signal, the electric signal is converted into an acoustic signal through the inverse piezoelectric effect due to interaction of the first electrodeand the substrate, and therefore the acoustic surface waves can be generated on the surface of the substrate. Under the action of fluid in the adhesion layer, the dielectric constant of the substrateis correspondingly changed so that the frequency of the surface acoustic waves is correspondingly changed, at the second electrode, the substrate and the second electrode interact with each other to convert an acoustic signal into an electric signal through a piezoelectric effect, and frequency detection of the changed surface acoustic waves is realized. The flow velocity of the fluid to be measured is obtained according to the corresponding relation between the flow velocity of the fluid and the frequency of the surface acoustic waves.

Description

technical field [0001] The invention relates to the field of fluid sensing, in particular to a surface acoustic wave-based fluid velocity sensor and system. Background technique [0002] Fluid is an object form corresponding to solid, and it is a general term for liquid and gas. It is composed of a large number of molecules that are constantly in thermal motion and have no fixed equilibrium position. Its basic characteristics are that it has no definite shape and has fluidity. Fluid has the same mass and density as other substances, and has certain compressibility. The compressibility of liquid is small, while the compressibility of gas is relatively large. When the shape of the fluid changes, there is also a certain gap between the layers of the fluid. Resistance to movement (i.e. viscosity). When the viscosity and compressibility of the fluid are small, it can be regarded as an ideal fluid approximately. It is an ideal model introduced by people to study the motion and s...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a surface acoustic wave fluid flow velocity sensor and system to solve the problems in the prior art that the volume of the buoy is large and the corresponding resistance is relatively large, so that the fluid to be measured There is a certain error in the measurement of the measured fluid, which makes the problem of low sensitivity and low precision in measuring the flow rate of the fluid to be measured

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