CN109506808B - SAW temperature sensor with monotone and linear output characteristics and design method thereof - Google Patents

SAW temperature sensor with monotone and linear output characteristics and design method thereof Download PDF

Info

Publication number
CN109506808B
CN109506808B CN201811601602.7A CN201811601602A CN109506808B CN 109506808 B CN109506808 B CN 109506808B CN 201811601602 A CN201811601602 A CN 201811601602A CN 109506808 B CN109506808 B CN 109506808B
Authority
CN
China
Prior art keywords
saw
temperature sensor
saw resonators
tcf
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN201811601602.7A
Other languages
Chinese (zh)
Other versions
CN109506808A (en
Inventor
彭斌
朱瑞浩
张万里
李凌
张文旭
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Electronic Science and Technology of China
Original Assignee
University of Electronic Science and Technology of China
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Electronic Science and Technology of China filed Critical University of Electronic Science and Technology of China
Priority to CN201811601602.7A priority Critical patent/CN109506808B/en
Publication of CN109506808A publication Critical patent/CN109506808A/en
Application granted granted Critical
Publication of CN109506808B publication Critical patent/CN109506808B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/22—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of acoustic effects

Abstract

A SAW temperature sensor with monotonous and linear output characteristics and a design method thereof belong to the technical field of surface acoustic wave sensors. Book (I)The invention designs two SAW resonators at any position except the parallel position on the same piezoelectric substrate and connects the two SAW resonators to be used as the SAW temperature sensor, and the structural parameters of the two SAW resonators are designed to ensure that the resonant frequency of the two SAW resonators meets the TCF21f01＝TCF22f02And further designs a SAW temperature sensor with monotonic linear output characteristic. The SAW temperature sensor provided by the invention only needs two calibration parameters during testing, and the output of the SAW temperature sensor shows monotone linear change along with the temperature change. Compared with the traditional SAW temperature sensor, the full-range temperature measurement is realized, the calibration process of the test is obviously simplified, and the calculation complexity is reduced.

Description

SAW temperature sensor with monotone and linear output characteristics and design method thereof
Technical Field
The invention belongs to the technical field of surface acoustic wave sensors, and particularly relates to a Surface Acoustic Wave (SAW) temperature sensor with monotonic and linear output characteristics and a design method thereof.
Background
A Surface Acoustic Wave (SAW) is an elastic Wave propagating along a solid Surface, and a SAW temperature sensor is a device that senses temperature by relying on modulation of the SAW. The SAW temperature sensor has the characteristics of small volume, high repeatability, excellent performance and the like, can realize communication in a wireless mode, does not need external power supply, can output sensing signals by means of energy stored by the SAW temperature sensor, has the characteristic of wireless passive sensing, and is particularly suitable for realizing wireless temperature detection in a severe environment which is not suitable for direct contact.
The SAW temperature sensor uses an SAW device (a resonator, a delay line or a combined device thereof) as a sensitive and conversion element, an electric excitation signal is converted into mechanical waves by utilizing inverse piezoelectric effect at an input end, then the SAW is converted into an electric signal by utilizing positive piezoelectric effect at an output end, and the electric signal is output, and in the process, the external temperature can affect the SAW propagation characteristic and further reflect various parameters of the SAW device, so that the temperature is measured and monitored. The currently common SAW temperature sensors mainly have two structures: the delay line type temperature sensor and the resonance type temperature SAW sensor are divided into a single port and a double port in each structure. Unlike a delay line type temperature sensor that reflects a temperature value through time lag or phase change caused by temperature, a resonance type temperature SAW sensor reflects a temperature change by measuring a frequency change caused by a temperature change using good frequency selectivity of a SAW resonator. The SAW resonator refers to an interdigital transducer (IDT) and a pair of symmetrical reflection gratings on two sides of the IDT, which form a group of acoustic resonant cavities together, an external electric signal can be converted into an acoustic signal through the IDT due to inverse piezoelectric effect, and the generated SAW generates resonance by the reflection gratings on two sides, so that the SAW resonator only responds to a radio-frequency signal with a specific frequency, and the specific frequency is the resonance frequency of the SAW resonator. After the acoustic signal is transmitted back to the IDT, the acoustic signal of a specific frequency is converted into an electric signal due to the piezoelectric effect and is output. Therefore, the SAW resonator can be used as a temperature sensor after the corresponding relation between the ambient temperature and the resonant frequency is established. The relative change in resonant frequency of the SAW resonator with temperature can be expressed as:
Figure BDA0001922633460000011
in the formula: f. ofrAnd f0Respectively an actual temperature T and a reference temperature T0Resonance frequency of time SAW resonator, Δ T ═ T-T0。TCF1、TCF2And TCF3The first order temperature coefficient, the second order temperature coefficient and the third order temperature coefficient of the resonant frequency of the SAW resonator are respectively.
It has been found that for most piezoelectric materials, the relative change in resonant frequency Δ f isr/f0And is in a quadratic function relation with the temperature change deltat. Therefore, the TCF must be preserved during the actual design process1And TCF2And may omit the TCF3And a higher order temperature coefficient. However,. DELTA.fr/f0The quadratic function relationship with Δ T results in one resonance frequency corresponding to two temperature points, whichTherefore, the traditional SAW temperature sensor can only work in a certain monotone interval of the quadratic function, the application temperature range of the SAW temperature sensor is limited, and meanwhile, the temperature test is inconvenient. In order to solve this problem, a SAW temperature sensor using two SAW resonators and having an angle of less than 180 degrees between the propagation directions of the two SAW resonators is studied. However, the SAW temperature sensor constructed based on the method needs to calibrate a plurality of parameters in the testing process, and needs complex calculation to obtain the temperature, so that the actual operation difficulty is high.
Disclosure of Invention
The invention provides an SAW temperature sensor and a design method thereof, aiming at the problems of multiple calibration parameters and complex calculation in the test process of the SAW temperature sensor in the prior art. The temperature sensor only needs two calibration parameters during testing, and the output of the temperature sensor shows monotonous linear change along with the temperature change, thereby being used for testing in the full temperature range.
In order to solve the problems, the invention adopts the following technical scheme:
a SAW temperature sensor with monotone and linear output characteristics comprises a piezoelectric substrate and two SAW resonators arranged on the piezoelectric substrate, and is characterized in that the two SAW resonators are not in contact with each other and are connected through a circuit, and the acoustic surface wave propagation directions of the two SAW resonators form an included angle alpha which is less than 0 < alpha < 180 degrees; the resonance frequency ratio of the two SAW resonators satisfies the following relationship:
Figure BDA0001922633460000021
in the formula: f. of01And f02Respectively two SAW resonators at a reference temperature T0Resonant frequency of time, TCF21And TCF22The second order frequency temperature coefficients of the two SAW resonators.
Further, the circuit is connected in series or in parallel.
A method of designing a SAW temperature sensor having monotonic and linear output characteristics, comprising the steps of:
step 1: two SAW resonators are sequentially manufactured on the same piezoelectric substrate, the two SAW resonators are not in contact with each other, and the acoustic surface wave propagation directions of the two SAW resonators form an included angle alpha which is less than 0 < alpha < 180 degrees; the resonance frequency ratio of the two SAW resonators satisfies the following relationship:
Figure BDA0001922633460000031
in the formula: f. of01And f02Respectively two SAW resonators at a reference temperature T0Resonant frequency of time, TCF21And TCF22The second-order frequency temperature coefficients of the two SAW resonators are respectively;
step 2: and (3) connecting the two SAW resonators obtained in the step (1) in a series or parallel mode.
The principle of the invention is as follows: the relative resonant frequency shift of the two SAW resonators as a function of temperature can be expressed as:
Δfr1/f01＝TCF11ΔT+TCF21ΔT2 (1)
Δfr2/f02＝TCF12ΔT+TCF22ΔT2 (2)
in the formula: f. ofr1And fr2Respectively the resonance frequencies, Δ f, of the two SAW resonators at the actual temperature Tr＝fr-f0，TCF11And TCF12Temperature coefficient of first order frequency, TCF, of two SAW resonators21And TCF22The second-order frequency temperature coefficients of the two SAW resonators are respectively;
thus, it can be seen that:
Figure BDA0001922633460000032
at this time, although a temperature change is obtainedLinear relationship between chemical quantity and resonant frequency shift, but f needs to be calibrated during test01，TCF11，TCF21，f02，TCF12，TCF22These several coefficients, and when the resonant frequency f is measuredr1And fr2Later, complex calculations are still required to obtain the temperature. For this reason, we found through further studies that when two SAW resonators are designed at the reference temperature T0The resonant frequency ratio of (A) satisfies TCF21f01＝TCF22f02When, formula (3) can be expressed as follows:
Figure BDA0001922633460000033
wherein:
Figure BDA0001922633460000034
C＝K(f02-f01)
from the simplified expression, K and C are two coefficients related to the piezoelectric substrate material and the device structure parameters. Therefore, when the piezoelectric substrate is determined, i.e., the material parameters are determined, and the structures of the two SAW resonators and the arrangement positions of the two SAW resonators on the piezoelectric substrate are determined, K and C are constants. We have thus found that the difference in resonant frequencies of the two SAW resonators is proportional to temperature. Thus, in conjunction with the common general knowledge in the art, when the piezoelectric substrate material selected and the orientation of the two SAW resonators is determined (i.e., the location on the piezoelectric substrate is determined), the acoustic velocities of the two SAW resonators can be determined, the TCF21And TCF22Was also determined (TCF)21And TCF22Determined by the material properties of the piezoelectric substrate), by TCF21f01＝TCF22f02Can determine f01And f02The ratio of (a) to (b). Assuming that two SAW resonators are respectively denoted as SAW resonator 1 and SAW resonator 2, by designing an interdigital transducer (IDT) of SAW resonator 1, SAW resonator 1 at reference temperature T can be obtained0Harmonic frequency f of time01From the above analysis, it can be seen that f01And f02Is determined so that the SAW resonator 2 is at the reference temperature T0Harmonic frequency f of time02Determining, in turn, by the resonant frequency f02The structure of the SAW resonator 2 can be determined. SAW temperature sensors with single harmonic and linear output characteristics were thus designed. Compared with the traditional method of using two SAW resonators to form a temperature sensor to acquire temperature data, the method simplifies the calibration process of the test, effectively reduces the complexity of calculation, and further realizes simple and convenient temperature measurement of the SAW sensor.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, two SAW resonators at any positions except the parallel position are designed on the same piezoelectric substrate and connected to be used as the SAW temperature sensor, and the structural parameters of the two SAW resonators are designed so that the resonance frequency ratio of the two SAW resonators meets a special relation, so that the SAW temperature sensor obtained by design has monotonous and linear output characteristics. The SAW temperature sensor provided by the invention only needs two calibration parameters during testing, and the output of the SAW temperature sensor shows monotone linear change along with the temperature change. Compared with the traditional SAW temperature sensor, the full-range temperature measurement is realized, the calibration process of the test is obviously simplified, and the calculation complexity is reduced.
Drawings
FIG. 1 is a schematic diagram of a parallel configuration of the present invention.
FIG. 2 is a schematic diagram of a sample in this embodiment.
FIG. 3 shows the Δ T and (f) of the fitting of this embodimentr1-fr2) The relationship between them.
Detailed Description
The technical scheme of the invention is described in detail by combining the drawings and the specific embodiments in the specification: example (b):
(1) preparation of the SAW temperature sensor:
in this embodiment, two SAW resonators are respectively referred to as a SAW resonator 1 and a SAW resonator 2, a main structure of the SAW resonator is shown in fig. 1, and includes an interdigital transducer (referred to as an interdigital electrode, abbreviated as IDT in english) and a reflection grating symmetrical with respect to the IDT, the SAW resonator 1 and the SAW resonator 2 are electrically connected in parallel in fig. 1, and a propagation direction of a surface acoustic wave in the SAW resonator is shown by an arrow in fig. 1.
The euler angles of the SAW resonator 1 and the SAW resonator 2 in this embodiment are set to (0 °,138.5 °,26.6 °) and (0 °,138.5 °,86.6 °), respectively, in which directions the acoustic velocity and the second-order frequency temperature coefficient of the SAW resonator are known, where: in the (0 deg., 138.5 deg., 26.6 deg.) direction, the speed of sound is 2716m/s, TCF21＝4.27×10-8℃-2(ii) a In the (0 deg., 138.5 deg., 86.6 deg.) direction, the speed of sound is 2466m/s, TCF22＝6.4×10-8℃-2. It can be calculated from this that the ratio of the resonance frequencies of the SAW resonator 1 to the SAW resonator 2 is about 3: 2, the ratio of the wavelengths is about 3: 4. The structural parameters of the SAW resonator with equally spaced interdigital electrodes are designed by combining the knowledge in the art, and the wavelengths of the SAW resonator 1 and the SAW resonator 2 are selected to be 12 μm and 16 μm, so that the width of the interdigital electrode of the SAW resonator 1 is 3 μm, and the width of the interdigital electrode of the SAW resonator 2 is 4 μm.
After determining the structural parameters of the SAW resonator, in this embodiment, the SAW resonator 1 and the SAW resonator 2 are fabricated on the LGS piezoelectric substrate based on the microelectronic lithography process, and specifically, a contact ultraviolet lithography technique and a lift-off process are used to pattern electrodes, and as a preferred mode, the interdigital electrode of the SAW resonator 1 in this embodiment is composed of two metal films, and specifically, the operations are as follows: a sample graph shown in FIG. 2 was prepared by first depositing a 10nm thick Ti film as an adhesive layer on an LGS substrate, and then sputtering a 100nm thick Au film on the Ti buffer layer by electron beam evaporation.
(2) And (3) temperature testing:
the SAW temperature sensor manufactured by the embodiment is tested and calibrated at different temperatures, and the room temperature is set as the reference temperature T0The SAW temperature sensor is placed in a high temperature furnace to increase the temperature from room temperature to 50 ℃, 100 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃ and 350 ℃ to 400 ℃ in sequence, and the difference delta f of the resonant frequencies of the two SAW resonators is measured by a vector network analyzer at each temperaturer12(Δfr12＝fr1-fr2) And establishing Δ T and (f)r1-fr2) The relationship between them, as shown in fig. 3. Constants K and C can be obtained by linear fitting, and the constants K and C of the SAW temperature sensor are-0.00011 ℃/Hz and 7988 ℃ respectively, so that the temperature and the delta f are obtainedr12Simple linear relationship between:
ΔT＝K(fr1-fr2)+C；
at this time, only the resonant frequencies f of the two devices are measuredr1And fr2And a unique delta T value can be obtained without complex calculation, so that the temperature is measured.
While the present invention has been particularly shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (3)

1. A SAW temperature sensor with monotone and linear output characteristics comprises a piezoelectric substrate and two SAW resonators arranged on the piezoelectric substrate, and is characterized in that the two SAW resonators are not in contact with each other and are connected through a circuit, and the acoustic surface wave propagation directions of the two SAW resonators form an included angle alpha which is less than 0 < alpha < 180 degrees; the resonance frequency ratio of the two SAW resonators satisfies the following relationship:
Figure FDA0001922633450000011
in the formula: f. of01And f02Respectively two SAW resonators at a reference temperature T0Resonant frequency of time, TCF21And TCF22The second order frequency temperature coefficients of the two SAW resonators.
2. A SAW temperature sensor according to claim 1, wherein said circuits are connected in series or in parallel.
3. A method of designing a SAW temperature sensor having monotonic and linear output characteristics, comprising the steps of:
step 1: two SAW resonators are sequentially manufactured on the same piezoelectric substrate, the two SAW resonators are not in contact with each other, and the acoustic surface wave propagation directions of the two SAW resonators form an included angle alpha which is less than 0 < alpha < 180 degrees; the resonance frequency ratio of the two SAW resonators satisfies the following relationship:
Figure FDA0001922633450000012
in the formula: f. of01And f02Respectively two SAW resonators at a reference temperature T0Resonant frequency of time, TCF21And TCF22The second-order frequency temperature coefficients of the two SAW resonators are respectively;
step 2: and (3) connecting the two SAW resonators obtained in the step (1) in a series or parallel mode.
CN201811601602.7A 2018-12-26 2018-12-26 SAW temperature sensor with monotone and linear output characteristics and design method thereof Expired - Fee Related CN109506808B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811601602.7A CN109506808B (en) 2018-12-26 2018-12-26 SAW temperature sensor with monotone and linear output characteristics and design method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811601602.7A CN109506808B (en) 2018-12-26 2018-12-26 SAW temperature sensor with monotone and linear output characteristics and design method thereof

Publications (2)

Publication Number Publication Date
CN109506808A CN109506808A (en) 2019-03-22
CN109506808B true CN109506808B (en) 2020-12-18

Family

ID=65755282

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811601602.7A Expired - Fee Related CN109506808B (en) 2018-12-26 2018-12-26 SAW temperature sensor with monotone and linear output characteristics and design method thereof

Country Status (1)

Country Link
CN (1) CN109506808B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111366111B (en) * 2020-03-30 2021-12-03 电子科技大学 Strain sensor composed of three LGS surface acoustic wave resonators and testing method
CN113155305A (en) * 2021-01-18 2021-07-23 国网吉林省电力有限公司长春供电公司 Passive surface acoustic wave temperature measurement reader for high-voltage power cable connector
CN114112102A (en) * 2021-11-24 2022-03-01 之江实验室 Surface acoustic wave temperature sensor with linear output characteristic and preparation method

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2033185B (en) * 1978-09-22 1983-05-18 Secr Defence Acoustic wave device with temperature stabilisation
US6831525B1 (en) * 2002-12-17 2004-12-14 Nortel Networks Limited Oscillator arrangements with improved frequency stability
FR2864618B1 (en) * 2003-12-24 2006-03-03 Temex Sa REMOTE TEMPERATURE OR TEMPERATURE AND PRESSURE SENSOR
JP4622860B2 (en) * 2004-01-09 2011-02-02 パナソニック株式会社 Surface acoustic wave filter
US7434989B2 (en) * 2005-09-07 2008-10-14 Applied Sensor Research & Development Corporation SAW temperature sensor and system
DE102006027060B4 (en) * 2006-06-08 2010-04-01 Leibniz-Institut Für Festkörper- Und Werkstoffforschung Dresden E.V. Oscillator circuit with single-port acoustic surface wave resonators
JP2010068503A (en) * 2008-08-13 2010-03-25 Seiko Epson Corp Surface acoustic wave element
FR2947050B1 (en) * 2009-06-19 2011-07-15 Senseor METHOD FOR THE COLLECTIVE MANUFACTURE OF TEMPERATURE AND / OR DEFORMATION SENSORS WITHOUT CALIBRATION BY MATCHING RESONATORS ON RESONANCE FREQUENCY CRITERIA AND STATIC CAPABILITY
EP2781022B1 (en) * 2011-11-17 2016-10-12 Transense Technologies PLC Resonant monolithic differential surface acoustic wave (saw) temperature sensing device
CN102928111B (en) * 2012-11-17 2014-04-09 中科微声（天津）传感技术有限公司 Surface acoustic wave temperature sensor
EP2980550B1 (en) * 2014-07-28 2017-01-25 Centre National de la Recherche Scientifique (CNRS) Differential temperature surface sensor
CN205843840U (en) * 2016-07-16 2016-12-28 苏文电能科技有限公司 A kind of multi-chip differential type SAW temperature sensor
CN106225948A (en) * 2016-07-27 2016-12-14 电子科技大学 A kind of double SAW Temperature Sensors and method for designing thereof
CN106840056A (en) * 2016-12-28 2017-06-13 电子科技大学 A kind of alliteration surface wave strain transducer and its method for designing
CN108593136A (en) * 2018-05-18 2018-09-28 中国科学技术大学先进技术研究院 A kind of wearable temperature monitoring method based on passive wireless acoustic surface wave

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LGS声表面波双模温度传感器研究;喻恒 等;《压电与声光》;20181031;第40卷(第5期);第17-23页 *

Also Published As

Publication number Publication date
CN109506808A (en) 2019-03-22

Similar Documents

Publication Publication Date Title
US8960004B2 (en) Synchronous one-pole surface acoustic wave resonator
CN109506808B (en) SAW temperature sensor with monotone and linear output characteristics and design method thereof
US5003822A (en) Acoustic wave microsensors for measuring fluid flow
US20060254356A1 (en) Wireless and passive acoustic wave liquid conductivity sensor
US20090114798A1 (en) Circular Surface Acoustic Wave (SAW) Devices, Processes for Making Them, and Methods of Use
TWI427290B (en) A gas sensor and method thereof
JP2007524853A (en) Layered surface acoustic wave sensor
CN108151907B (en) Linear temperature frequency characteristic measuring and calculating method of LGS surface acoustic wave temperature sensor
Kochhar et al. Wave propagation direction and c-axis tilt angle influence on the performance of ScAlN/sapphire-based saw devices
Della Lucia et al. Design, fabrication and characterization of SAW pressure sensors for offshore oil and gas exploration
Fu et al. A stable and highly sensitive strain sensor based on a surface acoustic wave oscillator
Xue et al. LGS-based SAW sensor that can measure pressure up to 1000° C
CN106895803A (en) A kind of device and methods influenceed using two SAW resonator separation temperatures
CN114112102A (en) Surface acoustic wave temperature sensor with linear output characteristic and preparation method
Kalantar-Zadeh et al. Comparison of layered based SAW sensors
Joshi Flow sensors based on surface acoustic waves
Pan et al. The influence of temperature on the pressure sensitivity of surface acoustic wave pressure sensor
CN104101451B (en) Sensitive source surface acoustic wave sensor
Furniss et al. Surface acoustic wave (SAW) sensors for cryogenic temperature and strain sensing
CN111366111B (en) Strain sensor composed of three LGS surface acoustic wave resonators and testing method
Schiopu et al. Development of SAW filters based on GaPO 4
Qian et al. A High Sensitivity Temperature Sensor Using High-Q NS-SAW Resonator
Hauden Elastic waves for miniaturized piezoelectric sensors: applications to physical quantity measurements and chemical direction
Bilobran et al. Thermally tunable surface acoustic wave cavities
Kohler et al. Flexible Surface Acoustic Wave (SAW) Sensors for Cryogenic Sensing Application

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20201218

Termination date: 20211226

CF01 Termination of patent right due to non-payment of annual fee