A surface acoustic wave resonator, temperature sensor, and temperature detection method

Abstract

The application relates to a surface acoustic wave resonator based on a multi-layer structure, a temperature sensor and a temperature detection method, wherein the surface acoustic wave resonator comprises, from bottom to top, a piezoelectric layer, an electrode layer and a temperature-sensitive layer; and the temperature-frequency coefficient of the temperature-sensitive layer is greater than that of the piezoelectric layer. The application increases the temperature-sensitive layer with a relatively large temperature-frequency coefficient to improve the overall temperature-frequency coefficient of the surface acoustic wave resonator, overcomes the technical defects that the detection precision (depending on the overall temperature-frequency coefficient of the surface acoustic wave resonator) of the existing surface acoustic wave resonator is limited by the temperature-frequency coefficient of the piezoelectric layer, and further improves the temperature detection precision of the surface acoustic wave resonator.

Description

Technical Field

[0001] This invention relates to the field of radio frequency sensing technology, and in particular to a surface acoustic wave resonator, a temperature sensor, and a temperature detection method. Background Technology

[0002] The frequency response of surface acoustic wave (SAW) resonators exhibits temperature-dependent characteristics. This characteristic can be used to determine the corresponding temperature by measuring the frequency response of acoustic devices. However, the overall temperature-frequency coefficient of existing SAW resonators mainly depends on the temperature-frequency coefficient of the piezoelectric layer. Due to limitations in piezoelectric materials, further improvements in the temperature-frequency coefficient of the piezoelectric layer are restricted, which in turn limits the overall temperature-frequency coefficient. The overall temperature-frequency coefficient, in turn, determines the temperature detection accuracy of the SAW resonator, thus hindering the improvement of temperature detection accuracy. Summary of the Invention

[0003] In view of this, the present invention provides a surface acoustic wave resonator, a temperature sensor, and a temperature detection method to overcome the limitations of piezoelectric materials and further improve the temperature detection accuracy of the surface acoustic wave resonator.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A surface acoustic wave resonator based on a multilayer structure, the surface acoustic wave resonator comprising a piezoelectric layer, an electrode layer and a temperature-sensitive layer arranged sequentially from bottom to top; the temperature-frequency coefficient of the temperature-sensitive layer is greater than the temperature-frequency coefficient of the piezoelectric layer.

[0006] Optionally, the temperature-sensitive layer is made of lithium niobate, lithium tantalate, or aluminum nitride.

[0007] Optionally, the electrode layer includes a transducer, a reflective grating symmetrically arranged on both sides of the transducer, and two antennas respectively connected to the two electrodes of the transducer.

[0008] Optionally, the transducer is an interdigital transducer.

[0009] Optionally, the electrode layer is made of a metallic material.

[0010] Optionally, the piezoelectric layer is made of quartz.

[0011] A temperature sensor, comprising the aforementioned surface acoustic wave resonator, further comprising an electromagnetic signal transmitting module, an electromagnetic signal receiving module, and a signal processing module;

[0012] Both the electromagnetic signal transmitting module and the electromagnetic signal receiving module are wirelessly connected to the surface acoustic wave resonator.

[0013] The electromagnetic signal receiving module is connected to the signal processing module;

[0014] The electromagnetic signal transmitting module is used to transmit a first electromagnetic signal to the surface acoustic wave resonator.

[0015] The electromagnetic signal receiving module is used to receive the second electromagnetic signal returned by the surface acoustic wave resonator.

[0016] The signal processing module is used to process the second electromagnetic signal to obtain the resonant frequency of the second electromagnetic signal, and to calculate the temperature of the environment under test based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator.

[0017] Optionally, the formula for calculating the temperature of the environment to be measured is:

[0018]

[0019] Where TCF is the temperature-frequency coefficient of the surface acoustic wave resonator, T0 is the reference temperature, f0 is the reference resonant frequency corresponding to the reference temperature, T1 is the temperature of the environment under test, and f1 is the resonant frequency of the second electromagnetic signal.

[0020] A temperature detection method, the method being based on the aforementioned surface acoustic wave resonator, the method comprising the following steps:

[0021] The surface acoustic wave resonator is placed in the environment to be tested;

[0022] A first electromagnetic signal is transmitted to the surface acoustic wave resonator;

[0023] Receive the second electromagnetic signal returned by the surface acoustic wave resonator;

[0024] The second electromagnetic signal is processed to obtain the resonant frequency of the second electromagnetic signal;

[0025] The temperature of the environment under test is calculated based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator.

[0026] Optionally, calculating the temperature of the environment under test based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator specifically includes:

[0027] Based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator, the formula is solved. The temperature of the environment to be measured is obtained;

[0028] Where TCF is the temperature-frequency coefficient of the surface acoustic wave resonator, T0 is the reference temperature, f0 is the reference resonant frequency corresponding to the reference temperature, T1 is the temperature of the environment under test, and f1 is the resonant frequency of the second electromagnetic signal.

[0029] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] This invention discloses a surface acoustic wave (SAW) resonator, temperature sensor, and temperature detection method based on a multilayer structure. The SAW resonator includes a piezoelectric layer, an electrode layer, and a temperature-sensitive layer arranged sequentially from bottom to top. The temperature-frequency coefficient of the temperature-sensitive layer is greater than that of the piezoelectric layer. This invention adds a temperature-sensitive layer, so in the SAW resonator of this embodiment, in addition to the piezoelectric layer, there is also a temperature-sensitive layer with temperature-sensitive characteristics. Since the temperature-frequency coefficient of the temperature-sensitive layer is greater than that of the piezoelectric layer, even if the temperature-frequency coefficient of the piezoelectric layer is limited by material constraints, the overall temperature-frequency coefficient of the SAW resonator can still be improved. This overcomes the technical defect of existing SAW resonators where the detection accuracy (which depends on the overall temperature-frequency coefficient of the SAW resonator) is limited by the temperature-frequency coefficient of the piezoelectric layer, further improving the temperature detection accuracy of the SAW resonator. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of a multilayer surface acoustic wave resonator provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the electrode layer structure provided in an embodiment of the present invention;

[0034] Figure 3 A comparison diagram of the temperature frequency coefficients of a multilayer-structured surface acoustic wave resonator provided in this embodiment of the invention and an existing surface acoustic wave resonator.

[0035] Figure 4 A schematic diagram of the temperature sensor provided in this embodiment of the invention;

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Piezoelectric layer; 2. Electrode layer; 3. Temperature-sensitive layer; 21. Transducer; 22. Reflector grating; 23. Antenna. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The purpose of this invention is to provide a surface acoustic wave resonator, a temperature sensor, and a temperature detection method to overcome the limitations of piezoelectric materials and further improve the temperature detection accuracy of the surface acoustic wave resonator.

[0040] Example 1

[0041] like Figure 1 As shown, Embodiment 1 of the present invention provides a surface acoustic wave (SAW) resonator based on a multilayer structure. The SAW resonator includes a piezoelectric layer 1, an electrode layer 2, and a temperature-sensitive layer 3 arranged sequentially from bottom to top; the temperature-frequency coefficient of the temperature-sensitive layer 3 is greater than that of the piezoelectric layer 1. Figure 2 As shown, the electrode layer 2 includes a transducer 21, a reflective grating 22 symmetrically arranged on both sides of the transducer 21, and two antennas 23 respectively connected to the two electrodes of the transducer 21.

[0042] For example, the electrode layer 2 provided in this embodiment of the invention is made of metal material, and the transducer 21 can be an interdigital transducer, which can be obtained by forming a metal interdigital structure on the piezoelectric layer 1. The reflective gratings 22 on both sides of the interdigital transducer can be periodic structures, which reflect mechanical wave energy to improve energy utilization. The antenna 23 is connected to the transducer 21 as a channel for signal transmission and reception.

[0043] The piezoelectric material of piezoelectric layer 1 can be a conventional piezoelectric material such as quartz.

[0044] The temperature-sensitive layer 3 can be made of a material with a temperature-frequency coefficient greater than that of the piezoelectric material. For example, assuming the piezoelectric material is quartz, the temperature-sensitive layer 3 can be made of a material with a large temperature-frequency coefficient (TCF), such as lithium niobate, lithium tantalate, or aluminum nitride with optimized chamfering.

[0045] The temperature-sensitive layer 3 can increase the overall TCF of the surface acoustic wave resonator, making the temperature measurement accuracy of the surface acoustic wave resonator higher.

[0046] Specifically, the temperature measurement accuracy of a surface acoustic wave (SAW) resonator depends on the absolute value of the overall TCF of the SAW resonator. The larger the absolute value of the TCF, the greater the frequency change for the same amount of temperature change, and the higher the accuracy of the corresponding temperature detection.

[0047] Figure 3 This is a comparison of the temperature-frequency variation of a multilayer surface acoustic wave (SAW) resonator with existing SAW resonators when the temperature-sensitive layer 3 uses lithium niobate and the piezoelectric layer 1 uses quartz. Figure 3 It can be seen that the surface acoustic wave resonator provided in the embodiments of the present invention has a larger absolute value of slope, that is, a larger TCF. Therefore, the accuracy of temperature detection is higher than that of existing surface acoustic wave resonators.

[0048] Through the Figure 3 The characterization results were calculated, and the overall TCF of the existing surface acoustic wave resonator is -17.4 ppm / ℃, while the overall TCF of the surface acoustic wave resonator provided in this embodiment of the invention is -74.06 ppm / ℃. The larger the absolute value of the TCF, the higher the temperature detection accuracy. Therefore, the multilayer surface acoustic wave resonator with the temperature-sensitive layer 3 has higher temperature measurement accuracy.

[0049] Example 2

[0050] Embodiment 2 of the present invention provides a temperature sensor, the principle of which for temperature detection is as follows: Figure 4 As shown, when the surface acoustic wave resonator receives an external electromagnetic signal (first electromagnetic signal) through the antenna, it generates a mechanical wave on the piezoelectric layer through the inverse piezoelectric effect. The mechanical wave then returns to the electromagnetic signal (second electromagnetic signal) through the piezoelectric effect in the piezoelectric layer. The second electromagnetic signal can be transmitted through the antenna. After the external device captures the second electromagnetic signal, the temperature of the environment under test can be measured according to the temperature-frequency coefficient.

[0051] Based on the above principles, the temperature sensor provided in Embodiment 2 of the present invention includes the surface acoustic wave resonator provided in Embodiment 1. The temperature sensor further includes an electromagnetic signal transmitting module, an electromagnetic signal receiving module, and a signal processing module. Both the electromagnetic signal transmitting module and the electromagnetic signal receiving module are wirelessly connected to the surface acoustic wave resonator, and the electromagnetic signal receiving module is connected to the signal processing module. The electromagnetic signal transmitting module is used to transmit a first electromagnetic signal to the surface acoustic wave resonator; the electromagnetic signal receiving module is used to receive a second electromagnetic signal induced by the surface acoustic wave resonator; the signal processing module is used to process the second electromagnetic signal to obtain its resonant frequency, and calculate the temperature of the environment to be measured based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator.

[0052] The temperature-frequency coefficient of the surface acoustic wave resonator in this embodiment of the invention can be determined by experimental calibration. Specifically, at least two ambient temperatures are detected using a standard tool for ambient temperature detection, and the resonant frequency in the second electromagnetic signal returned by the surface acoustic wave resonator is determined accordingly. Based on the two ambient temperatures and their corresponding resonant frequencies, the temperature-frequency coefficient of the surface acoustic wave resonator is calculated using the formula for calculating the temperature of the environment under test.

[0053] The formula for calculating the temperature of the environment under test is as follows:

[0054]

[0055] Where TCF is the temperature-frequency coefficient of the surface acoustic wave resonator, T0 is the reference temperature, usually the ambient temperature, with a value of 25℃, f0 is the reference resonant frequency corresponding to the reference temperature, T1 is the temperature of the environment to be measured, and f1 is the resonant frequency of the second electromagnetic signal.

[0056] When calculating the temperature-frequency coefficient (TCF) of a surface acoustic wave (SAW) resonator, T0 in the above formula can be taken as one of the aforementioned ambient temperatures, and f0 can be the resonant frequency of the second electromagnetic signal at that ambient temperature. T1 can be taken as another of the aforementioned ambient temperatures, and f1 can be the resonant frequency of the second electromagnetic signal at that ambient temperature. In this way, the specific value of TCF can be calculated.

[0057] Example 3

[0058] Embodiment 3 of the present invention provides a temperature detection method, the method being based on the surface acoustic wave resonator provided in Embodiment 1, and the method comprising the following steps:

[0059] The surface acoustic wave resonator is placed in the environment to be tested.

[0060] A first electromagnetic signal is transmitted to the surface acoustic wave resonator.

[0061] Receive the second electromagnetic signal returned by the surface acoustic wave resonator.

[0062] The second electromagnetic signal is processed to obtain its resonant frequency.

[0063] The temperature of the environment under test is calculated based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator.

[0064] Specifically, calculating the temperature of the environment under test based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator includes:

[0065] Based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator, the formula is solved. The temperature of the environment to be measured is obtained;

[0066] Where TCF is the temperature-frequency coefficient of the surface acoustic wave resonator, T0 is the reference temperature, f0 is the reference resonant frequency corresponding to the reference temperature, T1 is the temperature of the environment under test, and f1 is the resonant frequency of the second electromagnetic signal.

[0067] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0068] This invention improves the overall temperature-frequency coefficient of the surface acoustic wave (SAW) resonator by adding a temperature-sensitive layer with a larger temperature-frequency coefficient. This overcomes the technical limitation of existing SAW resonators, whose detection accuracy is restricted by the temperature-frequency coefficient of the piezoelectric layer (which depends on the overall temperature-frequency coefficient of the SAW resonator), and further improves the temperature detection accuracy of the SAW resonator.

[0069] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0070] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A temperature sensor, characterized in that, The temperature sensor includes a surface acoustic wave resonator, which includes a piezoelectric layer, an electrode layer, and a temperature-sensitive layer arranged sequentially from bottom to top; the temperature-frequency coefficient of the temperature-sensitive layer is greater than the temperature-frequency coefficient of the piezoelectric layer. The temperature sensor also includes an electromagnetic signal transmitting module, an electromagnetic signal receiving module, and a signal processing module; Both the electromagnetic signal transmitting module and the electromagnetic signal receiving module are wirelessly connected to the surface acoustic wave resonator. The electromagnetic signal receiving module is connected to the signal processing module; The electromagnetic signal transmitting module is used to transmit a first electromagnetic signal to the surface acoustic wave resonator. The electromagnetic signal receiving module is used to receive the second electromagnetic signal returned by the surface acoustic wave resonator; The signal processing module is used to process the second electromagnetic signal to obtain the resonant frequency of the second electromagnetic signal, and to calculate the temperature of the environment under test based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator.

2. The temperature sensor according to claim 1, characterized in that, The formula for calculating the temperature of the environment to be measured is: in, The temperature-frequency coefficient of the surface acoustic wave resonator. T 0 For reference temperature, f 0 The reference resonant frequency is the reference temperature. T 1 The temperature of the environment to be measured. f 1 The resonant frequency of the second electromagnetic signal is given.

3. The temperature sensor according to claim 1, characterized in that, The temperature-sensitive layer is made of lithium niobate, lithium tantalate, or aluminum nitride.

4. The temperature sensor according to claim 1, characterized in that, The electrode layer includes a transducer, a reflective grating symmetrically arranged on both sides of the transducer, and two antennas respectively connected to the two electrodes of the transducer.

5. The temperature sensor according to claim 4, characterized in that, The transducer is an interdigital transducer.

6. The temperature sensor according to any one of claims 1, 4, and 5, characterized in that, The electrode layer is made of a metallic material.

7. The temperature sensor according to claim 1, characterized in that, The piezoelectric layer is made of quartz.

8. A temperature detection method, characterized in that, The method is based on a surface acoustic wave resonator, which includes a piezoelectric layer, an electrode layer, and a temperature-sensitive layer arranged sequentially from bottom to top; the temperature-frequency coefficient of the temperature-sensitive layer is greater than the temperature-frequency coefficient of the piezoelectric layer. The method includes the following steps: The surface acoustic wave resonator is placed in the environment to be tested; A first electromagnetic signal is transmitted to the surface acoustic wave resonator; Receive the second electromagnetic signal returned by the surface acoustic wave resonator; The second electromagnetic signal is processed to obtain the resonant frequency of the second electromagnetic signal; The temperature of the environment under test is calculated based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator.

9. The temperature detection method according to claim 8, characterized in that, The calculation of the temperature of the environment under test based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator specifically includes: Based on the resonant frequency and the temperature-frequency coefficient of the surface acoustic wave resonator, the formula is solved. The temperature of the environment to be measured is obtained; in, The temperature-frequency coefficient of the surface acoustic wave resonator. T 0 For reference temperature, f 0 The reference resonant frequency is the reference temperature. T 1 The temperature of the environment to be measured. f 1 The resonant frequency of the second electromagnetic signal is given.

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