CN201535702U - Wireless temperature sensor of acoustic surface wave - Google Patents
Wireless temperature sensor of acoustic surface wave Download PDFInfo
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- CN201535702U CN201535702U CN2009201080243U CN200920108024U CN201535702U CN 201535702 U CN201535702 U CN 201535702U CN 2009201080243 U CN2009201080243 U CN 2009201080243U CN 200920108024 U CN200920108024 U CN 200920108024U CN 201535702 U CN201535702 U CN 201535702U
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Abstract
The utility model relates to a wireless temperature sensor of acoustic surface wave, which comprises manufacturing an interdigital transducer with an EWC/SPUDT structure and 11 reflectors of a short-circuit gate structure on a piezoelectric substrate. The EWC/SPUDT receives electromagnetic wave signals emitted by a wireless reading unit through a wireless antenna, and the electromagnetic wave signals are converted into acoustic surface wave to spread along the direction of the reflectors on the surface of the piezoelectric substrate and are reflected by the reflectors; the reflected acoustic wave is re-converted into electromagnetic wave signals through EWC/SPUDT2, is sent back to the wireless reading unit by the wireless antenna, so as to evaluates the phase change of the time domain response to realize temperature detection through a signal processing method. For reducing multiple reflections between the reflectors, 11 reflectors of an SAW reflective delay line are divided into two ways: 8 devices in one way are used as 8-bit tags and 3 reflectors in the other way are used for temperature detection. The uniform-response time-domain S11 reflection peak is obtained through adjusting the number of electrodes of the reflector.
Description
Technical field
The utility model relates to a kind of surface acoustic wave (surface acoustic wave:SAW) temperature sensor of integrated electronic label, particularly relates to a kind of radio temperature sensor that adopts the SAW reflective delay line of control electrode width single phase unidirectional transducer and short-circuit gate reflector structure.
Background technology
The velocity of propagation of SAW exist with the linear correlation of temperature relation be Δ v=v
0* TCD * (T-T
Ref), wherein TCD is the first-order lag temperature coefficient (depending on the crystal structure of piezoelectric substrate material and tangential) of piezoelectric substrate, Δ v is a velocity variations, v
0Be SAW speed, T
RefBe reference temperature.Utilizing some higher temperature coefficients like this is the piezoelectric substrate such as the LiNbO of high TCD value
3, LiTaO
3And La
3Ga
5SiO
4Can realize detection to temperature.In recent years, by means of wireless recognition technique, a kind of SAW reflective delay line begins to be applied to the SAW radio temperature sensor and uses.This SAW reflective delay line by a piezoelectric substrate with constitute (its reverberator number depends on practical application) along an interdigital transducer and several reverberators of sonic propagation direction setting, interdigital transducer receives the electromagnetic wave signal that comes from wireless reading unit (Reader unit) emission by wireless antenna, and convert to along the SAW of piezoelectric substrate surface propagation, and the device that is reflected reflects, the SAW of reflection converts electromagnetic wave signal to again by interdigital transducer, send it back wireless reading unit by wireless antenna, because the linear correlation of SAW speed and temperature causes the linear response of SAW reflective delay line time domain phase place, realize radio detection to temperature with this.
As an example, conventional structure is applied to a SAW reflective delay line 1 of radio temperature sensor, comprise a piezoelectric substrate, with an interdigital transducer of making of semiconductor planar technology on piezoelectric substrate and three reverberators that are provided with along the sonic propagation direction, as shown in Figure 1, wherein 9 is piezoelectric substrate, 2 is interdigital transducer, 3,4 and 5 is three reverberators, and the distance between reverberator 3 and interdigital transducer 2 and the reverberator is determined according to delay requirement.6,7 and 8 are respectively from first, second and the 3rd reflection echo signal of reverberator 3,4 and 5 reflections.Piezoelectric substrate 9 adopts the LiNbO with high-temperature coefficient usually
3, LiTaO
3Deng material, utilize its high sensitivity to temperature, acoustic velocity presents linear change with the peripheral environment variation of temperature, thereby causes SAW reflective delay line reflection coefficient S
11Time domain time delay/phase response, realize detection with this to temperature.
The frequency of operation based on this SAW reflective delay line of prior art be the prototype SAW radio temperature sensor sensing range of 2.4GHz in (room temperature～200 ℃), its sensitivity has reached 34 °/℃, and has obtained the temperature detection resolution less than 0.1K.Because this SAW temperature sensor is made of individual devices, simple in structure, adopt as document 1:L.M.Reindl:Wireless measurement of temperature using surface acoustic wavesensors, IEEE Trans.UFFC, 51,1457-1463 (2004). described three reflector structures and corresponding signal processing method can effectively be eliminated owing to surpass the signal ambiguity that 360 degree occur in the phase-detection, might obtain good temperature control and improve; Adopt phase place as sensor output signal in addition, have higher sensitivity resolution, and device itself can realize definitely passively, be suitable under hot conditions, working, therefore this SAW radio temperature sensor has a good application prospect, and causes the great interest of people.For this wireless SAW temperature sensor, the design of SAW reflective delay line has directly determined every performance index, particularly sensing range etc. of sensor, because along with the rising of temperature, the also corresponding increase of sonic propagation decay directly translates into the time domain response S of SAW reflective delay line
11Loss with temperature (the document 2:R.S.Hauser that raises, et al:A wirelessSAW-based temperature sensor for harsh environment, Proceeding of IEEE Sensors, Vol.2pp:860-863,2004), this just needs a kind of low-loss, high s/n ratio and have the SAW reflection model lag line at the steep sharp-pointed Time Domain Reflectometry of homogeneous peak.But be applied to the SAW reflective delay line of radio temperature sensor at present because there is bigger problem in the device architecture design, for example:
1. what the interdigital transducer 2 that above-mentioned conventional SAW reflective delay line 1 is adopted adopted is a kind of bidrectional transducer structure, causes sound wave two-way propagation, thereby has increased the acoustic propagation loss (generally all 50～60dB); Signal to noise ratio (S/N ratio) is lower, this has just badly influenced the temperature detection scope and the wireless distance that reads (is inverse relation with device loss, document 3:C.E.Cook, M.Bernfeld:Radar signals, Norwood, MA, Artech House, 1993), the more direct temperature detection scope that has had influence on sensor.In addition, the reflective delay line of prior art fails to realize steep sharp-pointed reflection coefficient S
11The Time Domain Reflectometry peak, this just is unfavorable for the accurate extraction of time domain delay time signal, thus cause detection signal than large deviation.
2. the conventional SAW reflective delay line 1 common employing of the above-mentioned SAW of being applied to radio temperature sensor singly refers to type or the interdigital transducer type reverberator as lag line.Therefore the reverberator of interdigitation has bigger reflection coefficient, can improve device loss and signal to noise ratio (S/N ratio) preferably, but since interdigital electrode refer between reflection and the bigger time domain noise of acoustic-electric regeneration causing.The reverberator that singly refers to type can reduce device time domain noise, but less reflection coefficient causes device loss bigger, and signal to noise ratio (S/N ratio) is low.
3. because sonic propagation decay, it is poor that the long travel path of lag line causes being derived from the reflection peak homogeneity of each reverberator usually, and far away more from transducer, its loss is big more, and signal to noise ratio (S/N ratio) is low more, directly has influence on the extraction of time domain delay time signal.
4. present, an important development trend of sensing system is integration of function, helps realizing the real-time detection to many reference amounts like this, also helps system's miniaturization and portable realization; And the existing radio temperature sensor function singleness that adopts the SAW reflective delay line; Therefore, it has directly hindered some performance improvements and the practical application of SAW radio temperature sensor.
Summary of the invention
The purpose of this utility model is to solve the above-mentioned existing problem of SAW radio temperature sensor; In order to realize that the SAW reflective delay line has low-loss, high s/n ratio, hang down the characteristics of time domain noise and homogeneous time domain response, thereby provide a kind of employing 41 ° of YXLiNbO
3Piezoelectric substrate is an interdigital electrode with aluminium, adopts the SAW reflective delay line that is used for temperature detection of control electrode width single phase unidirectional transducer (EWC/SPUDT) and short-circuit gate reverberator; 11 short-circuit gate reverberators divide the two-way setting, and one tunnel 8 reverberator is used for 8 electronic tags, and other 3 reverberators then are used for temperature detection, realize a kind of SAW radio temperature sensor of portable integrated electronic label of the real-time detection to many reference amounts.
The purpose of this utility model is achieved in that
A kind of surface acoustic wave wireless temperature sensor that the utility model provides shown in Fig. 2 a, comprises SAW reflective delay line 11; Described SAW reflective delay line 11 is by a piezoelectric substrate 9 with in described piezoelectric substrate 9 upper edge sonic propagation directions, applies out two conducting films 10 and a transducer 2 is set on both sides up and down and form with reverberator; It is characterized in that: also comprise Surface Mount potted element (surface mount device:SMD) 12, sound absorption glue, impedance matching network 13, wireless antenna 14 and reading unit 17), and the reverberator that is provided with at this piezoelectric substrate 9 is 11;
Described piezoelectric substrate 9 is that a Y is to 41 ° of lithium niobate (LiNbO that propagate along directions X of rotation
3) substrate, and be chosen in the end on described piezoelectric substrate 9 long limits, and applying two conducting films 10 in both sides up and down along upper surface, and in the middle of described two conducting films 10, apply the first sound absorption glue 18, described EWC/SPUDT2 is provided with along the limit of conducting film 10; Also the other end on described piezoelectric substrate 9 long limits apply the second sound absorption glue 18 ';
Described element pasted on surface 12 is used for the sealed package with SAW reflective delay line 11, formation is to EWC/SPUDT2, the protection on 11 reverberators 19～29 and piezoelectric substrate 9 surfaces, and finish being electrically connected of SAW reflective delay line 11 and peripheral impedance matching network 13;
Described transducer 2 is a control electrode width single phase unidirectional transducer (EWC/SPUDT), and this control electrode width single phase unidirectional transducer is done electrode with aluminium, and concrete structure is shown in Fig. 3 a; This control electrode width single phase unidirectional transducer to 31, and is provided with the reflecting electrode 30 that an electrode width is 1 λ/4, wherein λ by at least 2 above interdigital electrodes between 2 interdigital electrodes are to 31: wave length of sound; Described reflecting electrode 30 and described interdigital electrode are 3 λ/16 to the distance between 31, and this interdigital electrode is made up of the electrode of two 1 λ/8 31; Wherein the material with substrate and reflecting electrode 30 is depended in the position of reflecting electrode 30, for example, and with 41 ° of YX LiNbO
3Piezoelectric substrate and aluminium electrode, reflecting electrode 30 place interdigital electrode to 31 left side, and promptly opposite with one-way radiation sound wave direction is to obtain the sonic propagation of one-way radiation;
The input end N1 of described control electrode width single phase unidirectional transducer, by the signal end N3 of described wireless antenna 14, a series inductance 32 and a shunt inductance 33 in the connecting circuit; The earth terminal N4 of this wireless antenna 14 is electrically connected with the earth terminal N2 of described transducer 2, realizes impedance matching between SAW reflective delay line 11 and the wireless antenna 14 with this;
Receive the electromagnetic wave signal 15 that comes from described reading unit 17 emissions by described wireless antenna 14, convert SAW to by described control electrode width single phase unidirectional transducer 2, and along piezoelectric substrate 9 surface propagation and by this control electrode width single phase unidirectional transducer of 11 reflector sections reflected backs, again convert electromagnetic wave signal 16 to, and pass reading unit 17 back by wireless antenna 14, because the variation of peripheral temperature also causes the variation of acoustic velocity, thereby the time domain phase response that causes SAW reflective delay line 11 is estimated to realize the real-time detection to temperature by reading unit.
In above-mentioned technical scheme, described lithium niobate (LiNbO
3) coupling coefficient of substrate is 17.2%, acoustic propagation velocity is 4750m/s, the first-order lag temperature coefficient is 85ppm/ ℃.
In above-mentioned technical scheme, the reflected phase will of reflecting electrode 30 is depended in the position of described reflecting electrode 30, and it is then relevant with the material of reflecting electrode 30 with piezoelectric substrate 9; The reflection coefficient of short circuit metal grizzly bar is caused the piezoelectricity short circuit of substrate surface and mechanics load effect by the metal grizzly bar, the condition of the sound wave one-way radiation of 11 reverberator directions is that reflecting electrode 30 places interdigital electrode to 31 left side, promptly opposite with the sound wave of one-way radiation direction in obtaining as Fig. 2 b in the control electrode width single phase unidirectional transducer structure shown in Fig. 3 a.
In above-mentioned technical scheme, EWC/SPUDT 2 refers to that logarithm is 10-20, to obtain comparatively steep sharp-pointed Time Domain Reflectometry peak.
In above-mentioned technical scheme, for reducing repeatedly reflection and the Time Domain Reflectometry peak-to-peak noise between the reverberator, 11 reverberators are divided into the two-way setting, and A reverberator 19～a H reverberator 26 is used for 8 and is electronic tag for placing a paths; I reverberator 27～a K reverberator 29 is arranged at another path, is used for temperature detection; In addition, influence for the compensation sound wave propagation attenuation, the electrode number average of 11 reverberators is according to the certain rule setting, promptly has minimum number of electrodes (for example 5 electrodes that width is λ/4) from A-C nearest reverberator 19～21 of EWC/SPUDT2, along with the increase of reverberator from the EWC/SPUDT distance, the also corresponding increase of reflector electrode number, D reverberator 22～a F reverberator 24 has 6 electrodes, G 26 of reverberator 25～a H reverberator has 7 electrodes, the number of electrodes of I reverberator 27～a J reverberator 28 is 8, has maximum number of electrodes (adopting 9 electrodes in the utility model) from EWC/SPUDT K reverberator 29 farthest.
In above-mentioned technical scheme, A reverberator 27～a K reverberator 29 that is used for temperature detection is provided with according to certain rules, to obtain higher accuracy of detection, and the signal ambiguity that occurs above 360 degree in the elimination phase-detection, promptly the distance between K reverberator 28 and J the reverberator 29 need be much larger than the distance between I reverberator 27 and J the reverberator 28, but along with the increase of sonic propagation distance, the also corresponding increase of sonic propagation loss.Therefore, take all factors into consideration, the distance between J reverberator 28 and K the reverberator 29 is 3 times of distance between I reverberator 27 and J the reverberator 28.
In above-mentioned technical scheme, the distance between described A reverberator 19 and the EWC/SPUDT2 is 3272.4 μ m, provides with this to separate enough time delays that neighbourhood noise echo and sensor reflected signal surpass 1.2 μ s.
In above-mentioned technical scheme, the distance of described control electrode width single phase unidirectional transducer and A reverberator 19 is 2727 μ m, distance between B reverberator 20 and A the reverberator 19 is 383 μ m, distance between C reverberator 21 and B the reverberator 20 is 386.1 μ m, distance between D reverberator 22 and C the reverberator 21 is 388.8 μ m, distance between E reverberator 23 and D the reverberator 22 is 391.5 μ m, distance between F reverberator 24 and D the reverberator 23 is 394.2 μ m, distance between G reverberator 25 and F the reverberator 24 is 396.9 μ m, distance between H reverberator 26 and G the reverberator 25 is 399.6 μ m, distance between I reverberator 27 and H the reverberator 26 is 437.4 μ m, distance between J reverberator 28 and I the reverberator 27 is 442.8 μ m, and the distance between K reverberator 29 and J the reverberator 28 is 1309.5 μ m.
Advantage of the present utility model is:
SAW temperature sensor of the present utility model is an integrated form, its basic structure is to make one to have the interdigital transducer of EWC/SPUDT structure and the reverberator of 11 short-circuit gate structures on piezoelectric substrate, come from the electromagnetic wave signal that wireless reading unit is launched by EWC/SPUDT by the wireless antenna reception, and convert surface acoustic wave to, propagate along a reverberator direction on the piezoelectric substrate surface, and reflected by described reverberator respectively, reflected sound wave converts electromagnetic wave signal to again by EWC/SPUDT2, pass wireless reading unit back by wireless antenna, and by signal processing method, realize detection to temperature with the phase change of estimating time domain response.
Because SAW reflective delay line 11 of the present utility model, designed the structure of the unidirectional single-phase transducer of a kind of control electrode width, it is the forward direction that causes of the reflective electrodes reflects that utilize to distribute and the sound wave phase place of backpropagation superposes, effectively promote the forward direction sound wave, and suppress even offset the propagation of reverse sound wave, so just can effectively improve device loss, improve the signal-to-noise performance of reflective delay line.
In SAW reflective delay line 11, designed a kind of structure of short-circuit gate reverberator,, made the SAW reflective delay line have good signal-to-noise, reduced the reflection peak-to-peak noise simultaneously because this reverberator has higher reflection coefficient and zero acoustic-electric regenerative reflector.
The utility model has adopted 41 ° of YX LiNbO with high tension electricity coefficient (17.2%) and acoustic propagation velocity (4750m/s) and higher first-order lag temperature coefficient (85ppm/ ℃)
32 as piezoelectric substrate.And the EWC/SPUDT and the short-circuit gate reflector structure of employing aluminium electrode, reduced device loss (time domain S in the utility model
11The about 40dB of reflection peak loss in the signal), improved the signal to noise ratio (S/N ratio) of sensor; By reflector electrode index, the reverberator sound aperture of optimal design SAW reflective delay line, travel path etc., the time-domain reflector reflection peak of acquisition homogeneous loss and signal to noise ratio (S/N ratio).Position by the design configurations reverberator optimized obtains the temperature compensation and the sensitivity improving of sensor with this.
The utility model provide 11 adopts the reverberator of short-circuit gate structures two paths that are placed in, and 8 reverberators are that a path is used for 8 electronic tags, and other 3 reverberators are arranged at an other paths, to realize the detection to temperature.
The utility model adopts at piezoelectric substrate 9 two ends and applies sound absorption glue 18, is mainly used in the edge reflections of eliminating sound wave, to reduce the time domain noise that the device edge reflection causes.
The utility model adopts the finger logarithm (10 to 20 pairs) of limited reduction EWC/SPUDT 2 for obtaining comparatively steep sharp-pointed Time Domain Reflectometry peak, is a comparatively valid approach with respect to prior art.
Description of drawings
Fig. 1 is conventional SAW reflective delay line structural representation
Fig. 2 a is that integrated form SAW radio temperature sensor of the present utility model is formed synoptic diagram
Fig. 2 b is the SAW reflective delay line that is used for the integrated form radio temperature sensor of the present utility model
Fig. 3 a is the structural representation of the utility model SAW reflective delay line (EWC/SPUDT) that adopted
Fig. 3 b is the structural representation of the short-circuit gate reverberator that adopted of SAW reflective delay line of the present utility model
Fig. 4 is the structural design drawing of SAW reflective delay line of the present utility model
Fig. 5 is the impedance matching network between integrated form SAW radio temperature sensor and the wireless antenna in the utility model scheme
Fig. 6 is the test time-domain response curve figure of SAW reflective delay line of the present utility model
Drawing is described as follows:
1. conventional SAW reflective delay line 2. transducers 3. first reverberators
4. second reverberator 5. the 3rd reverberator, 6. first echo signals
7. second echo signal 8. the 3rd echoed signal 9. piezoelectric substrates
10. conducting film 11.SAW reflective delay line
12. surface mount device (SMD) 13. impedance matching networks 14. wireless antennas
15. electromagnetic wave signal 16. sensor signals 17. wireless reading units
18. the first sound absorption glue, 19. an A reverberator, 20. a B reverberator
21. C reverberator 22. a D reverberator 23. E reverberator
24. F reverberator 25. a G reverberator 26. H reverberator
27. I reverberator 28. a J reverberator 29. K reverberator
30. reflecting electrode 31. interdigital electrodes are to 32. polyphone inductance
33. and connect inductance 18 '. second the sound absorption glue
Embodiment
In order to make the purpose of this utility model, technical scheme and advantage clearer, the utility model is described in further details below in conjunction with drawings and Examples.
With reference to figure 2a, make an integrated form SAW temperature sensor, comprising :-SAW reflective delay line 11, element pasted on surface 12, and the impedance matching network 13 between SAW reflective delay line 11 and the wireless antenna 14.
With reference to figure 2b, the SAW reflective delay line 11 of the utility model embodiment, by 2 and 11 short-circuit gate reverberator compositions of a piezoelectric substrate 9 and the transducer made at this piezoelectric substrate 9 (transducer of present embodiment adopt be control electrode width single phase unidirectional transducer, i.e. EWC/SPUDT).SAW reflective delay line 11 usefulness element pasted on surface 12 sealed package are with protection piezoelectric substrate 9 and EWC/SPUDT 2 and 11 short-circuit gate reverberators; The element pasted on surface 12 of present embodiment adopts the general potted element with 10 pins in this area.
The piezoelectric substrate 9 of present embodiment adopts along Y to rotating 41 °, the niobic acid reason (LiNbO of directions X propagation
3) substrate is as vibrating membrane; Its piezoelectric substrate 9 is of a size of that (b:18mm), promptly long 18mm, wide 6mm, thickness are 41 ° of YXLiNbO of 350 μ m for a * b, a:6mm
3This piezoelectric substrate has higher acoustic velocity (4750m/s), piezoelectric coupling coefficient (17.2%) and first-order lag temperature coefficient (85ppm/ ℃).And be chosen in an end on described piezoelectric substrate 9 long limits, apply out two conducting films 10 in both sides up and down along upper surface, and apply the first sound absorption glue 18 in the middle of described two conducting films 10, described EWC/SPUDT2 is provided with along a limit of conducting film 10; Also the other end on these piezoelectric substrate 9 long limits applies the second sound absorption glue 18 ' (adopting this professional routine techniques to implement).Be mainly used in the edge reflections of eliminating sound wave, to reduce the time domain noise that the device edge reflection causes.
With reference to figure 3a, the transducer of present embodiment 2 is for doing the control electrode width single phase unidirectional transducer (EWC/SPUDT) of electrode with aluminium, wherein interdigital electrode to 31 and reflecting electrode 30 by
The aluminium film production; To 31, and form by the reflecting electrode 30 that 5 electrode widths that are provided with between 6 interdigital electrodes are to 31 are 1 λ/4 by 6 interdigital electrodes for this single phase unidirectional transducer, and interdigital electrode can also be any number between the 10-20 to 31 certainly; Reflecting electrode 30 and interdigital electrode are 3 λ/16 to the distance between 31 (electrode by two 1 λ/8 is formed).The determining positions of reflecting electrode 30 is in piezoelectric substrate 9 and reflecting electrode 30 materials.In the utility model embodiment, adopt 41 ° of YXLiNbO
3Substrate with
It is that reflecting electrode 30 places interdigital electrode to 31 left side, promptly opposite with the sound wave of one-way radiation direction that aluminium electrode material, control electrode width single phase unidirectional transducer shown in Fig. 3 a obtain condition as the sound wave one-way radiation of three reverberator directions among Fig. 2 a.
11 reverberators (A reverberator 19～a K reverberator 29) all adopt short-circuit gate reflector structure (concrete structure is shown in Fig. 3 b), are that 2 electric pole short circuits that obtain 3 to 10 1 λ/4 width form by minimum.The acoustic attenuation that causes for the repeatedly reverberator that reduces between the reverberator, 11 reverberators, two paths that are placed in, A reverberator 19～a H reverberator 26 places a paths, be used for 8 electronic tags, I reverberator 27～a K reverberator 29 is arranged at an other paths, is used for temperature detection.Cause the linear change of acoustic wave propagation velocity based on acoustic velocity and temperature linearity associate feature owing to the peripheral temperature variation, thereby the Time Domain Reflectometry peak time delay that causes I reverberator 27～a K reverberator 29 that is used for temperature (T) detection changes, and its temperature phse sensitivity ΔΦ can through type ΔΦ=l
2/ l
1* 2 π f
0l
1/ v
0* TCD * (T-T
Ref)=l
2/ l
1* 2 π f
0* Δ τ assesses (document 5:L.M.Reindl, et al, Wireless measurement of temperature using surface acoustic waves sensors, IEEE, Trans.UFFC, Vol.51, No.11,2004, PP.1457-1463), wherein, l
1With l
2Be respectively the distance between J reverberator 28 and K reverberator 29 and I reverberator 27 and the J reverberator 28, f
0Be working sensor frequency, v
0Be acoustic velocity under reference temperature (the being generally room temperature) condition, TCD is the single order temperature coefficient of substrate material, T
RefBe reference temperature (being room temperature).l
2/ l
1Value is big more might to obtain higher detection sensitivity more, yet, to be that propagation distance is far away more will cause very big propagation loss to the propagation attenuation of considering sonic propagation, therefore sonic propagation is controlled within limits to reduce the acoustic propagation loss apart from needs, in the utility model scheme, take all factors into consideration l
2/ l
1Value is about 3.
The basic structure of the integrated form SAW temperature sensor of present embodiment is: the reverberator of making an EWC/SPUDT2 and above-mentioned 11 short-circuit gate structures on piezoelectric substrate 9, come from the electromagnetic wave signal 15 that wireless reading unit 17 is launched by EWC/SPUDT 2 by wireless antenna 14 receptions, and convert surface acoustic wave to, propagate along 11 reverberator directions on piezoelectric substrate 9 surfaces, and reflected by described 11 reverberators respectively, reflected sound wave converts electromagnetic wave signal 16 to again by EWC/SPUDT2, pass wireless reading unit 17 back by wireless antenna 14, and, realize detection to temperature with the phase change of estimating time domain response by signal processing method (this is that those skilled in the art of the present technique are adequate).
In addition, because the propagation attenuation of sound wave influence, for keeping the time domain response of homogeneous, the electrode structure of 11 reverberators of SAW reflective delay line 11 needs certain optimal design, to compensate the time domain loss that causes owing to the acoustic propagation decay, adopt minimum number of electrodes (being 5 electrodes among the utility model embodiment) from EWC/SPUDT 2 nearest A reverberator 19～a C reverberator 21, far away more from EWC/SPUDT 2, the reflector electrode number is many more, and (D-F reverberator 22～24 adopts 6 electrodes in the utility model embodiment, G reverberator 25～a H reverberator 26 adopts 7 electrodes, the 1st reverberator 22～a J reverberator 28 adopts 8 electrodes, adopts 9 electrodes from EWC/SPUDT 2 K reverberator 29 farthest).
In the utility model embodiment, matching network 13 annexations between SAW reflective delay line 11 and the wireless antenna 14, as shown in Figure 5, the input end N1 of the transducer 2 of SAW reflective delay line 11, with an inductance 32 and the inductance 33 in parallel of connecting in the signal end N3 connecting circuit of wireless antenna 14; The earth terminal N2 of transducer 2 directly links to each other with the earth terminal N4 of wireless antenna; By reaching the impedance matching state between SAW reflective delay line 11 after these matching network 13 feasible encapsulation and the wireless antenna 14, obtain than low-loss with this, improve the signal-to-noise performance of sensor.
In the present embodiment, be to obtain comparatively steep sharp-pointed Time Domain Reflectometry peak, the finger logarithm of EWC/SPUDT 2 is 15, promptly comprises 15 interdigital electrodes shown in Fig. 3 a to 31, and is distributed in 14 reflecting electrodes 30 between the electrode pair.
In the present embodiment, A reverberator 19 of described SAW reflective delay line 11 and the distance between the EWC/SPUDT 2 are 3272.4 μ m, provide the enough time delays that separate at least 1.2 required μ s of neighbourhood noise echo and sensor signal with this.
What specific embodiment was made is applied in the radio temperature sensor, the concrete structure of SAW reflective delay line 11 as shown in Figure 4, the dependency structure parameter is as follows among the figure:
The frequency of operation of SAW reflective delay line 11: 434MHz; Wave length of sound λ: 10.9 μ m;
The width of a=piezoelectric substrate 9: 6mm
The length of b=piezoelectric substrate 9: 18mm
The length of A=EWC/SPUDT 2: 15 * λ=163.5 μ m;
The sound aperture of B=EWC/SPUDT 2: 110 * λ=1199 μ m;
The bus-bar width of A reverberator 19～the K of a C=reverberator 29: 5 * λ=54.5 μ m;
The sound aperture of A reverberator 19～the K of a D=reverberator 29: 50 * λ=545 μ m; The length of H1=reverberator 19: 9 * (1/4 λ)=24.5 μ m;
H
2The length of=the B reverberator 20: 9 * (1/4 λ)=24.5 μ m; H
3The length of=reverberator 21: 9 * (1/4 λ)=24.5 μ m;
H
4The length of=the D reverberator 22: 11 * (1/4 λ)=30 μ m; H
5The length of=reverberator 23: 11 * (1/4 λ)=30 μ m;
H
6The length of=the F reverberator 24: 11 * (1/4 λ)=30 μ m; H
7The length of=reverberator 25: 13 * (1/4 λ)=35.4 μ m;
H
8The length of=the H reverberator 26: 13 * (1/4 λ)=35.4 μ m; H
9The length of=reverberator 27: 15 * (1/4 λ)=40.9 μ m;
H
10The length of=the J reverberator 28: 15 * (1/4 λ)=40.9 μ m; H
11The length of=reverberator 29: 17 * (1/4 λ)=46.3 μ m;
l
1The distance that=the A reverberator 19 and EWC/SPUDT are 2: 3272.4 μ m;
l
2The distance that=the B reverberator 20 and reverberator are 19: 383.4 μ m;
l
3The distance that=the C reverberator 21 and reverberator are 20: 386.1 μ m;
l
4The distance that=the D reverberator 22 and reverberator are 21: 388.8 μ m;
l
5The distance that=the E reverberator 23 and reverberator are 22: 391.5 μ m;
l
6The distance that=the F reverberator 24 and reverberator are 23: 394.2 μ m;
l
7The distance that=the G reverberator 25 and reverberator are 24: 396.9 μ m;
l
8The distance that=the H reverberator 26 and reverberator are 25: 399.6 μ m;
l
9The distance that=the I reverberator 27 and reverberator are 26: 437.4 μ m;
l
10The distance that=the J reverberator 28 and reverberator are 27: 442.8 μ m;
l
11The distance that=the K reverberator 29 and reverberator are 28: 1309.5 μ m;
By this reflector design, SAW reflective delay line 11 will obtain the reverberator Time Domain Reflectometry peak of homogeneous, and have consistent loss and signal to noise ratio (S/N ratio).Fig. 6 shows from the HP8510 network analyzer response curve of the typical Time Domain Reflectometry coefficient S 11 of 434MHz SAW reflective delay line 11 before the observed encapsulation.11 reflection peaks come from 11 reverberators of SAW reflective delay line, have the comparatively loss and the signal-to-noise performance of homogeneous, corresponding time domain S
11The loss size is 39～43dB; The the 1st to the 8th reflection peak comes from A reverberator 19～a H reverberator 26, is applied to 8 electronic tags, and the corresponding time delay of first reflection peak is 1.4 μ s.The the 9th to the 11st reflection peak comes from I reverberator 27～J reverberator 29, is applied to temperature detection.The 9th the corresponding time delay of reflection peak is 2.81 μ s, and the 10th the corresponding time delay of reflection peak is 3 μ s, and the 11st reflection peak 11 corresponding time delays are 3.54 μ s.The 10th with the 11st reflection peak between delay inequality be the 9th with about 3 times of the 10th the corresponding delay inequality of reflection peak.From above-mentioned testing result, good signal-to-noise, comparatively sharp-pointed reflection peak and lower peak-to-peak noise have been realized than low-loss.
Claims (8)
1. a surface acoustic wave wireless temperature sensor comprises SAW reflective delay line (11); Described SAW reflective delay line (11) is by a piezoelectric substrate (9) with in described piezoelectric substrate (9) upper edge sonic propagation direction, applies out two conducting films (10) and a transducer (2) is set on both sides up and down and form with reverberator; It is characterized in that: also comprise Surface Mount potted element (12), sound absorption glue, impedance matching network (13), wireless antenna (14) and reading unit (17), and the reverberator that is provided with at this piezoelectric substrate (9) is 11;
Described piezoelectric substrate (9) is that a Y is to 41 ° of lithium niobate substrates of propagating along directions X of rotation; And be chosen in an end on the long limit of described piezoelectric substrate (9), both sides up and down along the surface apply out two conducting films (10), the first sound absorption glue (18) is set in the middle of described two conducting films (10), and described transducer (2) is along the end setting of conducting film (10); Also the other end at described piezoelectric substrate (9) is provided with the second sound absorption glue (18 ');
Described transducer (2) is a control electrode width single phase unidirectional transducer; This transducer (2) is done electrode and at least 2 above interdigital electrodes to (31) with aluminium, and the reflecting electrode that an electrode width is 1 λ/4 (30) is set between 2 interdigital electrodes are to (31) forms, and wherein λ is a wave length of sound; Described reflecting electrode (30) and described interdigital electrode are 3 λ/16 to the distance between (31), and described interdigital electrode is made up of the electrode of two 1 λ/8 (31);
Described 11 reverberators are the short-circuit gate reverberator, and wherein, described each short-circuit gate reverberator is made up of the electrode of 21 λ/4 width at least; Described 11 reverberators are divided into the two-way setting, and one the tunnel is used for electronic tag, are made up of the short-circuit gate reverberator word order that 8 sizes, spacing equate; An other paths is used for temperature detection, is made up of 3 short-circuit gate reverberators, position word order below last reverberator of continuing to use in 8 short-circuit gate reverberators of electronic tag is set forms;
The input end N1 of described control electrode width single phase unidirectional transducer (2), by the signal end N3 of described wireless antenna (14), a series inductance (32) in the connecting circuit and a shunt inductance (33); The earth terminal N4 of this wireless antenna (14) is electrically connected with the earth terminal N2 of described control electrode width single phase unidirectional transducer (2), realizes impedance matching between SAW reflective delay line (11) and the wireless antenna (14) with this;
Described element pasted on surface (12) has 10 pins, the sealed package that is used for the SAW radio temperature sensor, formation is to the electrode of the EWC/SPUDT (2) of SAW reflection model lag line (11), 11 reverberators and the protection on piezoelectric substrate (9) surface, and finishes being electrically connected of SAW reflective delay line (11) and matching network (13);
Receive the electromagnetic wave signal (15) that comes from described reading unit (17) emission by described wireless antenna (14), convert SAW to by described control electrode width single phase unidirectional transducer (2), and along the propagation of piezoelectric substrate (9) surface and by this control electrode width single phase unidirectional transducer (2) of 11 reflector sections reflected backs, again convert electromagnetic wave signal (16) to, and pass reading unit (17) back by wireless antenna (14), because the variation of peripheral temperature also causes the variation of acoustic velocity, thereby the time domain phase response that causes SAW reflective delay line (11) is estimated to realize the real-time detection to temperature by reading unit (17).
2. by the described surface acoustic wave wireless temperature sensor of claim 1, it is characterized in that described lithium niobate substrate is that electromechanical coupling factor is 17.2%, acoustic propagation velocity is 4750m/s, 85ppm/ ℃ of first-order lag temperature coefficient.
3. by the described surface acoustic wave wireless temperature sensor of claim 1, it is characterized in that described EWC/SPUDT (2) refers to that logarithm is 10-20.
4. by the described surface acoustic wave wireless temperature sensor of claim 1, it is characterized in that, the number of electrodes of described 11 reverberators is provided with according to following rule: 3 the reverberator A-Cs nearest from control electrode width single phase unidirectional transducer (2) have minimum number of electrodes, along with the increase of distance, the number of electrodes of all the other reverberators increases progressively successively.The D-F reverberator adopts 6 electrodes, and the G-H reverberator adopts 7 electrodes, and the I-J reverberator adopts 8 electrodes, and K reverberator adopts 9 electrodes.
5. by the described surface acoustic wave wireless temperature sensor of claim 1, it is characterized in that, the distance of described control electrode width single phase unidirectional transducer and A reverberator (19) is 2727 μ m, distance between B reverberator (20) and A the reverberator (19) is 383 μ m, distance between C reverberator (21) and B the reverberator (20) is 386.1 μ m, distance between D reverberator (22) and C the reverberator (21) is 388.8 μ m, distance between E reverberator (23) and D the reverberator (22) is 391.5 μ m, distance between F reverberator (24) and D the reverberator (23) is 394.2 μ m, distance between G reverberator (25) and F the reverberator (24) is 396.9 μ m, distance between H reverberator (26) and G the reverberator (25) is 399.6 μ m, distance between I reverberator (27) and H the reverberator (26) is 437.4 μ m, distance between J reverberator (28) and I the reverberator (27) is 442.8 μ m, and the distance between K reverberator (29) and J the reverberator (28) is 1309.5 μ m.
6. by the described surface acoustic wave wireless temperature sensor of claim 5, it is characterized in that the distance between described J reverberator 28 and K the reverberator 29 is 3 times of distance between I reverberator 27 and J the reverberator 28.
7. by the described surface acoustic wave wireless temperature sensor of claim 1, it is characterized in that the distance between described A reverberator (19) and the described control electrode width single phase unidirectional transducer is 3272.4 μ m.
8. by the described surface acoustic wave wireless temperature sensor of claim 1, it is characterized in that the material of piezoelectric substrate (9) and reflecting electrode (30) is depended in the position of described reflecting electrode (30).
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| CN2009201080243U CN201535702U (en) | 2009-05-20 | 2009-05-20 | Wireless temperature sensor of acoustic surface wave |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102103021A (en) * | 2010-12-31 | 2011-06-22 | 深圳市虹远通信有限责任公司 | Temperature detection method and device based on passive wireless temperature sensor |
| CN105509924A (en) * | 2015-12-18 | 2016-04-20 | 中国电子科技集团公司第四十一研究所 | Non-contact temperature parameter extraction method under super-high-temperature environment |
| CN105606245A (en) * | 2015-12-18 | 2016-05-25 | 中国电子科技集团公司第四十一研究所 | Non-contact temperature parameter extraction device in superhigh temperature environment |
| US9826289B2 (en) | 2013-09-05 | 2017-11-21 | Sh Infotech Co., Ltd. | Sensor, telemeter, wireless sensor system and use method thereof |
| CN108802433A (en) * | 2018-03-15 | 2018-11-13 | 中国科学院苏州纳米技术与纳米仿生研究所 | Atomic force microscope probe, preparation method based on surface acoustic wave and characterizing method |
| CN111238604A (en) * | 2020-01-14 | 2020-06-05 | 湖北楚禹水务科技有限公司 | Acoustic wave water level gauge, water level detection method, electronic device, and storage medium |
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| CN111868745A (en) * | 2018-03-16 | 2020-10-30 | 福瑞斯恩系统 | Composite substrate for SAW tags for RFID and sensor applications |
| CN112729595A (en) * | 2021-02-02 | 2021-04-30 | 上海航天电子有限公司 | Delay line type surface acoustic wave sensor and manufacturing method thereof |
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| CN102103021A (en) * | 2010-12-31 | 2011-06-22 | 深圳市虹远通信有限责任公司 | Temperature detection method and device based on passive wireless temperature sensor |
| US9826289B2 (en) | 2013-09-05 | 2017-11-21 | Sh Infotech Co., Ltd. | Sensor, telemeter, wireless sensor system and use method thereof |
| CN105509924A (en) * | 2015-12-18 | 2016-04-20 | 中国电子科技集团公司第四十一研究所 | Non-contact temperature parameter extraction method under super-high-temperature environment |
| CN105606245A (en) * | 2015-12-18 | 2016-05-25 | 中国电子科技集团公司第四十一研究所 | Non-contact temperature parameter extraction device in superhigh temperature environment |
| CN105509924B (en) * | 2015-12-18 | 2018-06-08 | 中国电子科技集团公司第四十一研究所 | Temperature parameter extracting method under a kind of contactless hyperthermal environments |
| CN105606245B (en) * | 2015-12-18 | 2018-08-17 | 中国电子科技集团公司第四十一研究所 | Temperature parameter extraction element under a kind of contactless hyperthermal environments |
| CN108802433A (en) * | 2018-03-15 | 2018-11-13 | 中国科学院苏州纳米技术与纳米仿生研究所 | Atomic force microscope probe, preparation method based on surface acoustic wave and characterizing method |
| CN108802433B (en) * | 2018-03-15 | 2020-12-22 | 中国科学院苏州纳米技术与纳米仿生研究所 | Atomic force microscope probe based on surface acoustic wave, preparation method and characterization method |
| CN111868745A (en) * | 2018-03-16 | 2020-10-30 | 福瑞斯恩系统 | Composite substrate for SAW tags for RFID and sensor applications |
| CN111366768A (en) * | 2018-12-26 | 2020-07-03 | 中国科学院声学研究所 | Wireless passive surface acoustic wave current sensor based on reflection delay line |
| CN111238604A (en) * | 2020-01-14 | 2020-06-05 | 湖北楚禹水务科技有限公司 | Acoustic wave water level gauge, water level detection method, electronic device, and storage medium |
| US11901875B2 (en) | 2020-10-12 | 2024-02-13 | Applied Materials, Inc. | Surface acoustic wave sensor assembly |
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