CN-122016076-A - Surface acoustic wave temperature sensor, manufacturing method and demodulation system

CN122016076ACN 122016076 ACN122016076 ACN 122016076ACN-122016076-A

Abstract

The invention provides a surface acoustic wave temperature sensor, a manufacturing method and a demodulation system, and belongs to the technical field of sensors. The sensor comprises a piezoelectric substrate, four groups of interdigital transducers, four groups of reflecting grids and a group of planar antennas, wherein the four groups of interdigital transducers, the four groups of reflecting grids and the group of planar antennas are formed on the piezoelectric substrate, the surface of the piezoelectric substrate between the two groups of interdigital transducers is covered with a temperature sensitive film, the two groups of reflecting grids, the two groups of interdigital transducers, the temperature sensitive film and the piezoelectric substrate form a detection resonance area, the other two groups of interdigital transducers, the other two groups of reflecting grids and the piezoelectric substrate form a reference resonance area, isolation grooves are formed in the piezoelectric substrate between the detection resonance area and the reference resonance area, one end of the planar antennas are connected with one group of interdigital transducers of the detection resonance area, and the other end of the planar antennas are connected with one group of interdigital transducers of the reference resonance area. According to the invention, differential compensation of common-mode interference is realized, and the propagation of the acoustic surface wave of the detection resonance region to the reference resonance region is blocked by the isolation groove, so that the coupling interference between the two resonators is reduced.

Inventors

FANG DONGMING
JIANG SHUAI
LI PEIXIAO
WANG MANRONG
LI YAN
ZHOU XIANZI
WEN ZHIGUO
YUAN JUNFENG
JIA MENGYU
CHEN SIYUAN
WU YONGCHAO
FU WEIPING
HAN JIANZHEN
TAO YI
Ji Runke
WANG ZHIQIANG
LIU YONG
JIANG FAN
LIU ZIWEI
SUN HENGCHAO

Assignees

北京智芯微电子科技有限公司
国网河北省电力有限公司衡水供电分公司

Dates

Publication Date: 20260512
Application Date: 20260225
Priority Date: 20260211

Claims (15)

1. The surface acoustic wave temperature sensor is characterized by comprising a piezoelectric substrate, at least four groups of interdigital transducers, at least four groups of reflecting grids and a group of planar antennas, wherein the at least four groups of interdigital transducers, the at least four groups of reflecting grids and the group of planar antennas are formed on the piezoelectric substrate; The surface of the piezoelectric substrate between the two groups of interdigital transducers is covered with a temperature sensitive film, and the two groups of reflective grids, the two groups of interdigital transducers and the temperature sensitive film between the two groups of interdigital transducers form a detection resonance area with the piezoelectric substrate; The other two groups of interdigital transducers, the other two groups of reflecting grids and the piezoelectric substrate form a reference resonance area; An isolation groove is arranged in the piezoelectric substrate between the detection resonance region and the reference resonance region, and is used for blocking sound surface waves generated by the interdigital transducer of the detection resonance region from propagating to the reference resonance region; One end of the planar antenna is connected with a group of interdigital transducers of the detection resonance area, the other end of the planar antenna is connected with a group of interdigital transducers of the reference resonance area, and the planar antenna is used for receiving radio frequency signals and transmitting the radio frequency signals to the interdigital transducers and transmitting frequency signals of the surface acoustic waves generated by the interdigital transducers under the excitation of the radio frequency signals.
2. The surface acoustic wave temperature sensor according to claim 1, wherein the surface of the piezoelectric substrate between the other two sets of interdigital transducers is covered with an inertia film, and the other two sets of reflective gratings, the other two sets of interdigital transducers, and the inertia film between the two sets of interdigital transducers and the piezoelectric substrate form a reference resonance region.
3. The surface acoustic wave temperature sensor of claim 1, wherein the isolation groove is filled with an insulating dielectric material.
4. The surface acoustic wave temperature sensor of claim 1, wherein the lengths of the individual fingers in each set of interdigital transducers are unequal; the length of each finger is determined by apodization weighting the finger transducers of equal length fingers by a window function.
5. The surface acoustic wave temperature sensor according to claim 1, wherein one of the two sets of interdigital transducers for detecting a resonance region is an input interdigital transducer, and the other set of interdigital transducers is an output interdigital transducer; one group of interdigital transducers is used as an input interdigital transducer, and the other group of interdigital transducers is used as an output interdigital transducer in the two groups of interdigital transducers of the reference resonance region; one end of the planar antenna is connected with the input interdigital transducer of the detection resonance area, and the other end of the planar antenna is connected with the input interdigital transducer of the reference resonance area.
6. A method of manufacturing a surface acoustic wave temperature sensor, comprising: forming at least four sets of interdigital transducers and at least four sets of reflective gratings on the same piezoelectric substrate; Forming a temperature sensitive film on the surface of the piezoelectric substrate between two groups of interdigital transducers, wherein two groups of reflecting grids, two groups of interdigital transducers, the temperature sensitive film between the two groups of interdigital transducers and the piezoelectric substrate form a detection resonance area; Forming an isolation groove in the piezoelectric substrate between the detection resonance region and the reference resonance region, wherein the isolation groove is used for blocking the sound surface wave generated by the interdigital transducer of the detection resonance region from transmitting to the region where the reference resonance region is located; And forming a group of planar antennas on the surfaces of the piezoelectric substrate outside the detection resonance area and the reference resonance area, wherein one end of each planar antenna is connected with a group of interdigital transducers in the detection resonance area, the other end of each planar antenna is connected with a group of interdigital transducers in the reference resonance area, and each planar antenna is used for receiving radio frequency signals and transmitting the radio frequency signals to the interdigital transducers and transmitting frequency signals of surface acoustic waves generated by the interdigital transducers under the excitation of the radio frequency signals.
7. The method of manufacturing a surface acoustic wave temperature sensor according to claim 6, further comprising: And the other two groups of reflecting grids, the other two groups of interdigital transducers and the inertia film between the two groups of interdigital transducers and the piezoelectric substrate form a reference resonance area.
8. The method of manufacturing a surface acoustic wave temperature sensor according to claim 6, further comprising: And filling insulating medium materials in the isolation grooves.
9. The method of manufacturing a surface acoustic wave temperature sensor according to claim 6, wherein forming at least four sets of interdigital transducers and at least four sets of reflective gratings on the same piezoelectric substrate comprises: Coating photoresist on the surface of the cleaned piezoelectric substrate, and forming patterns of an interdigital transducer and a reflecting grating on the photoresist on the surface of the piezoelectric substrate through exposure and development treatment; Sputtering metal on the surface of the piezoelectric substrate to form the patterned metal film, wherein the metal film is used as an interdigital transducer and a reflecting grating.
10. The method of manufacturing a surface acoustic wave temperature sensor according to claim 6, wherein forming an isolation groove in the piezoelectric substrate between the detection resonance region and the reference resonance region, comprises: Grinding and polishing the surface of the piezoelectric substrate between the detection resonance area and the reference resonance area, and removing part of piezoelectric substrate material to form an isolation groove with preset depth; or adopting a dry etching or wet etching process to etch the piezoelectric substrate between the detection resonance region and the reference resonance region to form an isolation groove with a preset depth; The preset depth is greater than or equal to one quarter of the wavelength of the surface acoustic wave.
11. The method of manufacturing a surface acoustic wave temperature sensor according to claim 6, wherein forming a set of planar antennas on the surface of the piezoelectric substrate outside the detection resonance region and the reference resonance region, comprises: Coating photoresist on the surface of the metal film, and forming a pattern of a planar antenna on the photoresist through exposure and development treatment; And etching the piezoelectric substrate by adopting a dry etching or wet etching process to form the planar antenna of the pattern.
12. A demodulation system, which is applied to the surface acoustic wave temperature sensor of claim 1, and comprises a radio frequency transmitting module, a signal receiving module, a differential processing unit and a temperature demodulation unit; the radio frequency transmitting module is used for generating radio frequency signals and transmitting the radio frequency signals to the surface acoustic wave temperature sensor; The signal receiving module is used for receiving a first frequency signal and a second frequency signal from the surface acoustic wave temperature sensor, wherein the first frequency signal represents the frequency of the surface acoustic wave generated by the detection resonance area of the surface acoustic wave temperature sensor under the excitation of the radio frequency signal, and the second frequency signal represents the frequency of the surface acoustic wave generated by the reference resonance area of the surface acoustic wave temperature sensor under the excitation of the radio frequency signal; the difference processing unit is used for calculating the difference value between the frequency represented by the first frequency signal and the frequency represented by the second frequency signal; The temperature demodulation unit is used for determining a temperature value according to the frequency difference value calculated by the difference processing unit.
13. The demodulation system according to claim 12, wherein the temperature demodulation unit pre-stores a calibration curve based on a frequency difference value and a temperature value; and the temperature demodulation unit determines a temperature value corresponding to the frequency difference value calculated by the difference processing unit according to the calibration curve based on the frequency difference value and the temperature value.
14. The demodulation system of claim 13, wherein the calibration curve based on the frequency difference and the temperature value has the expression: T =(Δf -Δf 0 )/(kt - kt') + T 0 ; wherein, T represents an actual temperature value, T 0 represents a preset temperature value, Δf is a frequency difference value between a detection resonance region corresponding to the actual temperature value T and a reference resonance region, Δf 0 is a frequency difference value between the detection resonance region corresponding to the preset temperature value T 0 and the reference resonance region, kt is a temperature coefficient of a temperature sensitive film of the detection resonance region, and kt' is a temperature coefficient of a piezoelectric substrate material of the reference resonance region or a temperature coefficient of an inert film of the reference resonance region.
15. The demodulation system as claimed in claim 12, further comprising a power management module for converting solar or RF energy into electrical energy for powering the demodulation system.

Description

Surface acoustic wave temperature sensor, manufacturing method and demodulation system Technical Field The invention relates to the technical field of sensors, in particular to a surface acoustic wave temperature sensor, a manufacturing method of the surface acoustic wave temperature sensor and a demodulation system. Background The surface acoustic wave (Surface Acoustic Wave, SAW) temperature sensor has the advantages of wireless passivity, strong anti-interference capability, long service life and the like, and is applied to the scenes of industrial equipment monitoring, power system operation and maintenance, aerospace and the like. The principle of the SAW temperature sensor is that the elastic characteristic of the piezoelectric substrate is changed by utilizing temperature change, so that the resonance frequency of the surface acoustic wave is shifted, and the temperature measurement is realized by detecting the frequency change. The existing wireless passive SAW temperature sensor generally adopts a single resonator structure, an interdigital transducer (IDT) and a reflecting grating are manufactured on a piezoelectric substrate to form a resonator, an external reader emits radio frequency signals to excite the resonator, the frequency of the signals reflected by the resonator changes along with the temperature, and the reader reversely pushes the temperature value through demodulating the frequency offset. The SAW temperature sensor with the existing single resonator structure improves the precision by improving the stability of the resonant frequency, but cannot solve the problem of common mode interference, and the single resonator signal lacks a reference standard and has larger error in a complex environment. The existing SAW temperature sensor formed by combining two independently packaged temperature-measuring resonator chips and a reference resonator chip adopts a differential mode to compensate errors, but the two independently packaged resonator chips have temperature hysteresis effects, the temperature of the reference resonator and the temperature of the temperature-measuring resonator have errors at the same time, the differential compensation effect is improved to a limited extent, and common-mode interference suppression is poor. Disclosure of Invention In order to solve the defects in the prior art, the invention provides a surface acoustic wave temperature sensor, a manufacturing method and a demodulation system. The invention provides a surface acoustic wave temperature sensor, which comprises a piezoelectric substrate, at least four groups of interdigital transducers, at least four groups of reflecting grids and a group of planar antennas, wherein the at least four groups of interdigital transducers, the at least four groups of reflecting grids and the group of planar antennas are formed on the piezoelectric substrate; The surface of the piezoelectric substrate between the two groups of interdigital transducers is covered with a temperature sensitive film, and the two groups of reflective grids, the two groups of interdigital transducers and the temperature sensitive film between the two groups of interdigital transducers form a detection resonance area with the piezoelectric substrate; The other two groups of interdigital transducers, the other two groups of reflecting grids and the piezoelectric substrate form a reference resonance area; an isolation groove is arranged in the piezoelectric substrate between the detection resonance region and the reference resonance region, and is used for blocking the propagation of the sound surface wave generated by the interdigital transducer of the detection resonance region to the reference resonance region and blocking the propagation of the sound surface wave generated by the interdigital transducer of the reference resonance region to the detection resonance region; One end of the planar antenna is connected with a group of interdigital transducers of the detection resonance area, the other end of the planar antenna is connected with a group of interdigital transducers of the reference resonance area, and the planar antenna is used for receiving radio frequency signals and transmitting the radio frequency signals to the interdigital transducers and transmitting frequency signals of the surface acoustic waves generated by the interdigital transducers under the excitation of the radio frequency signals. In the embodiment of the invention, the surface of the piezoelectric substrate between the other two groups of interdigital transducers is covered with the inertia film, and the other two groups of reflection grids, the other two groups of interdigital transducers, the inertia film between the two groups of interdigital transducers and the piezoelectric substrate form a reference resonance area. In the embodiment of the invention, the isolation groove is filled with an insulating medium material. In the embodiment of the invention, the lengt