Surface acoustic wave temperature sensor based on annular interdigital electrode

Abstract

The invention discloses a surface acoustic wave temperature sensor based on an annular interdigital electrode. The sensor is a resonance type surface acoustic wave sensor and comprises a metal film layer and a piezoelectric substrate. The metal film layer comprises an annular interdigital electrode, an annular reflecting grating, bus bars and a bonding pad, the annular interdigital electrode extends from the opposite bus bars on the same straight line to the two sides in the circumferential direction, and the annular reflecting grating is arranged on the periphery of the annular interdigital electrode. The metal film layer is prepared on the surface of the substrate in a metal patterning mode through a micro-nano machining technology. The sensor can convert the environment temperature into the acoustic surface wave resonant frequency of the sensor, and the change of the frequency of the sensor is read by using a sweep frequency electric signal to sense the change of the external temperature. The sensor has the advantages of high temperature resistance, large measuring range, high signal-to-noise ratio, high accuracy, easiness in processing and the like.

Description

Technical Field

[0001] The invention relates to the technical field of temperature sensors, and in particular to a surface acoustic wave temperature sensor based on annular interdigital electrodes. Background Art

[0002] High-temperature sensing technology is very important for the fine control and green and efficient operation of high-end industrial equipment such as metallurgical kilns, power generation equipment, and aerospace engines. Through real-time monitoring of various indicators and equipment operating status in the industrial production process through sensing technology, accurate data support is provided for production control and optimization, thereby improving production efficiency and ensuring equipment and production safety. However, industrial processes generally have harsh environmental conditions such as closed high temperature, multi-phase and multi-field, numerous interferences, and dust obstruction that are not conducive to sensing and monitoring. This requires high-temperature sensors to have high sensitivity, high precision, strong anti-interference ability, and wireless passivity. Although existing surface acoustic wave sensors have shown good application prospects in high-temperature process monitoring in power plants, industrial kilns, gas turbines, aerospace engines, chemical processing, and other manufacturing facilities, the non-singularity of their surface acoustic wave propagation modes, scattering phenomena, and the existence of other transverse modes have a non-negligible negative impact on the performance of the device. Especially in the measurement of high temperature and wide temperature range, existing surface acoustic wave sensors face problems such as insufficient frequency selection characteristics, low quality factor, and poor transverse mode and spurious suppression performance. These challenges limit their performance and reliability in extreme industrial environments.

[0003] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0004] The main purpose of the present invention is to overcome the defects existing in the above-mentioned background technology and provide a surface acoustic wave temperature sensor based on annular interdigital electrodes.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A surface acoustic wave temperature sensor based on an annular interdigital electrode, comprising:

[0007] A double-layer structure formed by a metal film layer and a piezoelectric substrate;

[0008] The metal film layer is located on the piezoelectric substrate and includes an annular interdigitated electrode, an annular reflective grid, a bus bar and a pad;

[0009] The annular interdigitated electrodes extend from the opposite bus bars on the same straight line to both sides along the circumferential direction, and the sum of the electrode line width and the spacing is half the wavelength of the surface acoustic wave;

[0010] The annular reflection grating is arranged at the periphery of the annular interdigitated electrode, and the sum of the line width and the spacing of the reflection grating is half the wavelength of the surface acoustic wave;

[0011] The piezoelectric substrate can convert the external temperature into the surface acoustic wave resonance frequency, and input the metal electrode through the frequency sweeping electrical signal to induce resonance with the reflection grating, and read the corresponding resonance frequency to sense the external temperature.

[0012] Furthermore, the metal film layer includes a metal adhesion layer adhered to the piezoelectric substrate and a high temperature resistant metal conductive layer adhered to the metal adhesion layer.

[0013] Furthermore, the material of the metal adhesion layer includes chromium or titanium.

[0014] Furthermore, the material of the high temperature resistant metal conductive layer includes platinum or gold.

[0015] Furthermore, the thickness of the metal adhesion layer is 5nm-15nm.

[0016] Furthermore, the thickness of the high temperature resistant metal conductive layer is 80nm-300nm.

[0017] Furthermore, the piezoelectric substrate is a piezoelectric crystal, a piezoelectric ceramic or a piezoelectric film. When the piezoelectric substrate is a piezoelectric film, the piezoelectric film is attached to a high temperature resistant substrate.

[0018] Furthermore, the piezoelectric crystal or piezoelectric ceramic has a thickness of 300 μm-1000 μm.

[0019] Furthermore, the thickness of the piezoelectric film is 1-2 wavelengths of surface acoustic waves, and the high temperature resistant substrate to which the piezoelectric film is attached is 300 μm-1000 μm.

[0020] The present invention has the following beneficial effects:

[0021] The present invention provides a surface acoustic wave temperature sensor based on annular interdigital electrodes, which has good spurious and transverse mode suppression performance, and has the advantages of high temperature resistance, large measuring range, high signal-to-noise ratio, high accuracy, easy processing, etc.

[0022] The surface acoustic wave sensor based on the annular interdigital electrodes of the present invention can suppress the transverse mode and spurious of the surface acoustic wave. The annular interdigital electrodes of the sensor extend along both sides of the same bus bar, so that the forces on the interdigital electrodes on the same bus bar are opposite, resulting in the suppression of the transverse mode vibration of the electrode. The surface acoustic wave generated by the annular interdigital electrodes can only propagate in the radial direction, and the other directions are suppressed due to the unequal electrode spacing in the propagation path, which hinders the propagation of the scattered wave. The significant advantages of the sensor include good spurious and transverse mode suppression performance, high temperature resistance, large range, high signal-to-noise ratio, high accuracy, easy processing, etc.

[0023] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of an embodiment of a surface acoustic wave sensor based on annular interdigital electrodes of the present invention;

[0025] Figure 2 It is a schematic diagram of the metal film layer structure of an embodiment of a surface acoustic wave sensor based on annular interdigital electrodes of the present invention;

[0026] Figure 3 yes Figure 1 AA section view;

[0027] Figure 4 is a performance diagram of a surface acoustic wave temperature sensor according to the prior art;

[0028] Figure 5 is a performance diagram of a surface acoustic wave temperature sensor based on annular interdigital electrodes according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0030] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing as well as for coupling or communication.

[0031] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] See also Figures 1 to 3 The embodiment of the present invention provides a surface acoustic wave temperature sensor based on an annular interdigital electrode 2, comprising: a double-layer structure formed by a metal film layer and a piezoelectric substrate 1; the metal film layer is located on the piezoelectric substrate 1, and comprises an annular interdigital electrode 2, an annular reflective grating 3, a bus bar 4 and a pad 5; the annular interdigital electrode 2 extends from the opposite bus bars 4 on the same straight line to both sides along the circumferential direction, and the sum of the electrode line width and spacing is half the wavelength of the surface acoustic wave; the annular reflective grating 3 is arranged on the periphery of the annular interdigital electrode 2, and the sum of the reflective grating line width and spacing is half the wavelength of the surface acoustic wave; wherein the piezoelectric substrate 1 can convert the external temperature into the surface acoustic wave resonant frequency, and the metal electrode is input through a swept frequency electrical signal to induce resonance with the reflective grating, and the corresponding resonant frequency is read to sense the external temperature. As a resonant surface acoustic wave sensor, when working, the sensor can convert the ambient temperature into the surface acoustic wave resonant frequency of the sensor, and use the swept frequency electrical signal to read the change of the sensor frequency to sense the change of the external temperature.

[0034] In some embodiments, the metal film layer includes a metal adhesion layer adhered to the piezoelectric substrate 1 and a high temperature resistant metal conductive layer adhered to the metal adhesion layer.

[0035] In some embodiments, the material of the metal adhesion layer may be chromium or titanium. The material of the high temperature resistant metal conductive layer may be platinum or gold. Preferably, the thickness of the metal adhesion layer is 5nm-15nm. Preferably, the thickness of the high temperature resistant metal conductive layer is 80nm-300nm. The metal film layer may be prepared by metal patterning on the surface of the substrate through micro-nano processing technology.

[0036] In a preferred embodiment, the piezoelectric substrate 1 is a piezoelectric crystal, a piezoelectric ceramic or a piezoelectric film. When the piezoelectric substrate 1 is a piezoelectric film, the piezoelectric film is attached to a high temperature resistant substrate. Preferably, the thickness of the piezoelectric crystal or piezoelectric ceramic is 300 μm-1000 μm. Preferably, the thickness of the piezoelectric film is 1-2 surface acoustic wave wavelengths, and the high temperature resistant substrate to which the piezoelectric film is attached is 300 μm-1000 μm.

[0037] The surface acoustic wave sensor based on the annular interdigital electrodes of the present invention can effectively suppress the transverse mode and stray of the surface acoustic wave. Since the annular interdigital electrodes extend along both sides of the same bus bar, the forces on the interdigital electrodes on the same bus bar are opposite, resulting in the suppression of the transverse mode vibration of the electrode. At the same time, the surface acoustic wave generated by the annular interdigital electrodes can only propagate in the radial direction, and the other directions are suppressed due to the unequal electrode spacing in the propagation path, which hinders the propagation of the scattered wave. Through the above-mentioned innovative design, the surface acoustic wave temperature sensor of the present invention has better performance and reliability in high temperature environment, and has the advantages of high temperature resistance, large range, high signal-to-noise ratio, high accuracy, easy processing, etc., which can well meet the needs of high-end industrial equipment for high temperature sensors.

[0038] The specific embodiments and experimental verification of the present invention are further described below.

[0039] like Figure 1 As shown, the surface acoustic wave temperature sensor based on the annular interdigital electrode includes a metal film layer and a piezoelectric substrate 1, wherein the metal film layer is located on the piezoelectric substrate 1 to form a double-layer structure. The piezoelectric substrate 1 can convert the external temperature into the surface acoustic wave resonant frequency, and input the swept frequency electrical signal into the metal electrode to induce resonance with the reflective grating, read the corresponding resonant frequency, and thus sense the external temperature.

[0040] Further references Figure 2 and Figure 3 The metal film layer includes an annular interdigitated electrode 2, an annular reflector 3, a bus bar 4 and a pad 5. The annular interdigitated electrode 2 extends from the opposite bus bars on the same straight line to both sides in the circumferential direction, and the sum of the electrode line width and the spacing is half the wavelength of the surface acoustic wave. The annular reflector 3 is arranged outside the annular interdigitated electrode, and the sum of the reflector line width and the spacing is half the wavelength of the surface acoustic wave.

[0041] In a preferred embodiment, the metal film layer includes a metal adhesion layer (such as chromium (Cr), titanium (Ti), etc.) adhered to the piezoelectric substrate 1 and a high temperature resistant metal conductive layer (such as platinum (Pt), gold (Au), etc.) adhered to the metal adhesion layer. Among them, the metal adhesion layer is required to enhance the adhesion between the high temperature resistant metal conductive layer and the piezoelectric substrate to improve the reliability of the metal film layer, and the high temperature resistant metal conductive layer is required to have high temperature stability and good conductivity at high temperature.

[0042] In a further preferred embodiment, the thickness of the metal adhesion layer is 5nm-15nm, and the thickness of the high temperature resistant metal conductive layer is 80nm-300nm.

[0043] In a further preferred embodiment, the piezoelectric substrate 1 may be a piezoelectric crystal, a piezoelectric ceramic or a piezoelectric film. The piezoelectric film needs to be attached to a high temperature resistant substrate. The piezoelectric substrate is required to have a high Curie temperature and be able to maintain good piezoelectric properties at high temperatures.

[0044] In a further preferred embodiment, the thickness of the piezoelectric crystal or piezoelectric ceramic is 300 μm-1000 μm, the thickness of the piezoelectric film is 1-2 surface acoustic wave wavelengths, and the high temperature resistant substrate to which the piezoelectric film is attached is 300 μm-1000 μm.

[0045] Example 1

[0046] Surface acoustic wave temperature sensor based on ring-shaped interdigital electrodes Figure 1 As shown. A Y-cut 128° lithium niobate single crystal is selected as a piezoelectric substrate 1, a metal film layer is prepared on the lithium niobate wafer, and a ring-shaped interdigitated electrode 2, a ring-shaped reflective grating 3, a bus bar 4 and a pad 5 are obtained by photolithography, evaporation and stripping processes. The metal adhesion layer is a chromium (Cr) layer, and the high temperature resistant metal conductive layer is a platinum (Pt) layer.

[0047] In the prepared surface acoustic wave temperature sensor based on annular interdigital electrodes, the surface acoustic wave design wavelength is 12 μm, the annular interdigital electrodes 2 have a line width of 3 μm and a spacing of 3 μm, and the annular reflection grating 3 has a line width of 3 μm and a spacing of 3 μm.

[0048] In the prepared surface acoustic wave temperature sensor based on annular interdigital electrodes, the piezoelectric substrate is 500 μm thick, the chromium layer in the metal film layer is 10 nm thick, and the platinum layer is 100 nm thick.

[0049] As an example, the existing surface acoustic wave temperature sensor is compared with the surface acoustic wave temperature sensor based on the ring-shaped interdigital electrode of the present invention. The comparison results are as follows: Figure 4 and Figure 5 As shown, Figure 4 The performance diagrams of the common surface acoustic wave temperature sensor using the existing interdigital electrodes at 50℃, 250℃, 450℃ and 650℃ are shown below. Figure 5 The performance diagram of the surface acoustic wave temperature sensor using the annular interdigital electrodes of the present invention at 50°C, 250°C, 450°C and 650°C. Figure 4 and Figure 5 It can be seen from the comparison that the stray peaks of the surface acoustic wave temperature sensor based on the annular interdigital electrode are almost invisible, which effectively suppresses the stray and transverse modes and significantly improves the performance of the sensor.

[0050] In summary, the surface acoustic wave temperature sensor based on the annular interdigital electrode of the present invention realizes the precise conversion and reading of the resonant frequency of the surface acoustic wave through its unique double-layer structure of the metal film layer and the piezoelectric substrate, thereby accurately sensing the external temperature changes. Its main technical advantages include excellent stray and transverse mode suppression performance, which is due to the special design of the annular interdigital electrode, so that the interdigital electrode is subjected to opposite forces, effectively suppressing the transverse mode vibration, and only allowing the surface acoustic wave to propagate radially, thereby hindering the propagation of scattered waves. It has the advantages of high temperature resistance, large range, high signal-to-noise ratio, high accuracy, and easy processing.

[0051] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A surface acoustic wave temperature sensor based on an annular interdigital electrode, characterized in that: include: A double-layer structure formed by a metal film layer and a piezoelectric substrate; The metal film layer is located on the piezoelectric substrate and includes an annular interdigitated electrode, an annular reflective grid, a bus bar and a pad; The annular interdigitated electrodes extend from the opposite bus bars on the same straight line to both sides along the circumferential direction, and the sum of the electrode line width and the spacing is half the wavelength of the surface acoustic wave; The annular reflection grating is arranged at the periphery of the annular interdigitated electrode, and the sum of the line width and the spacing of the reflection grating is half the wavelength of the surface acoustic wave; The piezoelectric substrate can convert the external temperature into the surface acoustic wave resonance frequency, and input the metal electrode through the frequency sweeping electrical signal to induce resonance with the reflection grating, and read the corresponding resonance frequency to sense the external temperature.

2. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to claim 1, characterized in that: The metal film layer includes a metal adhesion layer adhered to the piezoelectric substrate and a high temperature resistant metal conductive layer adhered to the metal adhesion layer.

3. The surface acoustic wave temperature sensor based on the annular interdigital electrode according to claim 2, characterized in that: The material of the metal adhesion layer includes chromium or titanium.

4. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to claim 2 or 3, characterized in that: The material of the high temperature resistant metal conductive layer includes platinum or gold.

5. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to any one of claims 1 to 4, characterized in that: The thickness of the metal adhesion layer is 5nm-15nm.

6. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to any one of claims 1 to 5, characterized in that: The thickness of the high temperature resistant metal conductive layer is 80nm-300nm.

7. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to any one of claims 1 to 6, characterized in that: The piezoelectric substrate is a piezoelectric crystal, a piezoelectric ceramic or a piezoelectric film. When the piezoelectric substrate is a piezoelectric film, the piezoelectric film is attached to a high temperature resistant substrate.

8. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to claim 7, characterized in that: The piezoelectric crystal or piezoelectric ceramic has a thickness of 300 μm-1000 μm.

9. The surface acoustic wave temperature sensor based on annular interdigital electrodes according to claim 7, characterized in that: The thickness of the piezoelectric film is 1-2 wavelengths of surface acoustic waves, and the high temperature resistant substrate to which the piezoelectric film is attached is 300 μm-1000 μm.

Images