CN101644608B - Integrated surface acoustic wave wireless temperature sensor - Google Patents
Integrated surface acoustic wave wireless temperature sensor Download PDFInfo
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- CN101644608B CN101644608B CN 200910084148 CN200910084148A CN101644608B CN 101644608 B CN101644608 B CN 101644608B CN 200910084148 CN200910084148 CN 200910084148 CN 200910084148 A CN200910084148 A CN 200910084148A CN 101644608 B CN101644608 B CN 101644608B
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Abstract
The invention relates to an integrated surface acoustic wave (SAW) wireless temperature sensor, comprising an interdigital transducer with an EWC/SPUDT structure and 11 reflectors with short-circuit gate structures, which are manufactured on a piezoelectric substrate, wherein, the EWC/SPUDT receives an electromagnetic wave signal transmitted from a wireless reading unit by a wireless antenna and transforms the signal into surface acoustic wave which is propagated along the reflectors on the surface of the piezoelectric substrate and is respectively reflected by the reflectors, the reflected acoustic wave is retransformed into the electromagnetic wave signal by an EWC/SPUDT2, the signal is returned to the wireless reading unit by the wireless antenna, and finally temperature detection is realized by evaluation on a phase change of time-domain response via a signal processing method. In the sensor, the 11 reflectors of a SAW reflection delay line are divided into two paths for reducing multiple reflection among the reflectors, wherein, 8 reflectors on one path are used for 8-bit electronic tags, and 3 reflectors on the other path are used for temperature detection; and a reflection peak of a time domain S11 with even response is obtained by adjusting electrode number of the reflectors.
Description
Technical field
The present invention relates to a kind of surface acoustic wave (surface acoustic wave:SAW) temperature sensor of integrated electronic label, particularly relate 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 linear correlation relation that the velocity of propagation of SAW exists with temperature is 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 velocity variations, v
0Be SAW speed, T
refBe reference temperature.Utilizing like this some higher temperature coefficients is piezoelectric substrate such as the LiNbO of high TCD value
3, LiTaO
3And La
3Ga
5SiO
4Can realize the 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 consist of (its reverberator number depends on practical application) along an interdigital transducer and several reverberators of Acoustic Wave 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 reflected by reverberator, the SAW of reflection converts electromagnetic wave signal to again by interdigital transducer, send it back wireless reading unit by wireless antenna, cause the linear response of SAW reflective delay line time domain phase place due to the linear correlation of SAW speed and temperature, 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 technique on piezoelectric substrate and three reverberators that arrange along the Acoustic Wave 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 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 it to the high sensitivity of temperature, acoustic velocity presents linear change with the variation of peripheral environment temperature, thereby causes SAW reflective delay line reflection coefficient S
11Time domain time delay/phase response, realize detection to temperature with this.
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 wave sensors, IEEE Trans.UFFC, 51,1457-1463 (2004). described three reflector structures and corresponding signal processing method can effectively be eliminated the signal ambiguity that occurs owing to surpassing 360 degree in phase-detection, might obtain good temperature control and improve; Adopt in addition phase place as sensor output signal, have higher sensitivity resolution, and device itself can realize definitely passively, be suitable for working under hot conditions, 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 the property indices of sensor, sensing range etc. particularly, because the rising along with temperature, also corresponding increase of Acoustic Wave Propagation decay, directly translate into the loss of time domain response S11 of SAW reflective delay line with temperature (the document 2:R.S.Hauser that raises, et al:A wireless SAW-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 at present the SAW reflective delay line of radio temperature sensor because there is larger problem in device structure design, for example:
1. what the interdigital transducer 2 that adopts of above-mentioned conventional SAW reflective delay line 1 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), more directly had influence on the temperature detection scope of 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, thereby causes the relatively large deviation of detection signal.
2. the common employing of conventional SAW reflective delay line 1 of the above-mentioned SAW of being applied to radio temperature sensor refers to that singly type or interdigital transducer type are as the reverberator of lag line.Therefore the reverberator of interdigitation has larger reflection coefficient, can improve preferably device loss and signal to noise ratio (S/N ratio), but due to interdigital electrode refer between reflection and acoustic-electric regeneration cause larger noise in time domain.The reverberator that singly refers to type can reduce the device noise in time domain, but less reflection coefficient causes device loss larger, and signal to noise ratio (S/N ratio) is low.
3. due to Acoustic Wave 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, from transducer more away from, its loss is larger, signal to noise ratio (S/N ratio) is lower, directly has influence on the extraction of time domain delay time signal.
4. present, an important development trend of sensing system is the integrated of function, is conducive to like this to realize the real-time detection to many reference amounts, also is conducive to 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 object of the invention 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 noise in time domain and homogeneous time domain response, thereby provide a kind of employing 41 ° of YXLiNbO
3Piezoelectric substrate take aluminium as interdigital electrode, 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 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 object of the present invention is achieved like this:
The surface acoustic wave wireless temperature sensor of a kind of integrated form provided by the invention as shown in Fig. 2 a, comprises SAW reflective delay line 11; Described SAW reflective delay line 11 is by a piezoelectric substrate 9, and on described piezoelectric substrate 9 along the Acoustic Wave Propagation direction, two conducting films 10 that apply out on the both sides, up and down, an and set transducer 2 forms with reverberator; It is characterized in that: also comprise element pasted on surface (surface mount device:SMD) 12, sound absorption glue, impedance matching network 13, wireless antenna 14 and reading unit 17, and the reverberator that arranges at this piezoelectric substrate 9 is 11;
Described piezoelectric substrate 9 is 41 ° of lithium niobate (LiNbO that propagate along directions X of a Y-direction rotation
3) substrate, and be chosen in the end on described piezoelectric substrate 9 long limits, and applying two conducting films 10 along both sides, upper surface up and down, and apply the first sound absorption glue 18 in the middle of described two conducting films 10, described EWC/SPUDT2 arranges along the limit of conducting film 10; The other end of also growing limits at described piezoelectric substrate 9 applies the second sound absorption glue 18;
The sealed package that described element pasted on surface 12 is used for SAW reflective delay line 11, formation is to EWC/SPUDT2, the protection on 11 reverberators 19～29 and piezoelectric substrate 9 surfaces, and complete being electrically connected to of SAW reflective delay line 11 and peripheral impedance matching network 13;
Described transducer 2 is 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 as shown in Fig. 3 a; To 31, and an electrode width is set between every 2 interdigital electrodes are to 31 is that the reflecting electrode 30 of 1 λ/4 forms to this control electrode width single phase unidirectional transducer by 2 above interdigital electrodes, wherein λ: 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 forms 31 electrodes by two 1 λ/8; 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 are placed in interdigital electrode to 31 left side, and namely the direction opposite with the one-way radiation sound wave is to obtain the Acoustic Wave Propagation of one-way radiation;
Be connected a series inductance 32 in connecting circuit between the input end N1 of the transducer of described SAW reflective delay line 11 and the signal end N3 of described wireless antenna 14, be connected the inductance 33 of a ground connection in the connecting circuit between the signal end N3 of described series inductance 32 and described wireless antenna 14; The earth terminal N4 of this wireless antenna 14 is electrically connected to the earth terminal N2 of described transducer 2, realizes impedance matching between SAW reflective delay line 11 and wireless antenna 14 with this;
receive by described wireless antenna 14 electromagnetic wave signal 15 that comes from described reading unit 17 emissions, convert SAW to by described control electrode width single phase unidirectional transducer 2, and propagate and be reflected back this control electrode width single phase unidirectional transducer by 11 reflector sections along piezoelectric substrate 9 is surperficial, again convert electromagnetic wave signal 16 to, and pass reading unit 17 back by wireless antenna 14, also cause the variation of acoustic velocity due to the variation of peripheral temperature, thereby the time domain phase response that causes SAW reflective delay line 11, realized real-time detection to temperature by reading unit estimate.
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 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, in obtaining as Fig. 2 b in the control electrode width single phase unidirectional transducer structure shown in Fig. 3 a, the condition of the sound wave one-way radiation of 11 reverberator directions is that reflecting electrode 30 is placed in interdigital electrode to 31 left side, the i.e. direction opposite with the sound wave of one-way radiation.
In above-mentioned technical scheme, EWC/SPUDT 2 finger logarithms are 10-20, to obtain comparatively steep sharp-pointed Time Domain Reflectometry peak.
in above-mentioned technical scheme, for reducing Multi reflection and the Time Domain Reflectometry peak-to-peak noise between reverberator, 11 reverberators are divided into the two-way setting, and A reverberator 19～a H reverberator 26 is for being placed in a paths, and being used for 8 is electronic tag, I reverberator 27～a K reverberator 29 is arranged at another path, is used for temperature detection, in addition, impact for the compensation sound wave propagation attenuation, the electrode number average of 11 reverberators is according to the certain rule setting, namely 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 reflector electrode number is corresponding increase also, 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 present invention) 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 arranges according to certain rule, to obtain higher accuracy of detection, and the signal ambiguity that occurs over 360 degree in the elimination phase-detection, namely the distance between K reverberator 28 and J reverberator 29 need to be much larger than the distance between I reverberator 27 and J reverberator 28, but along with the increase of Acoustic Wave Propagation distance, the Acoustic Wave Propagation loss is corresponding increase also.Therefore, consider, the distance between J reverberator 28 and K reverberator 29 is 3 times of distance between I reverberator 27 and J reverberator 28.
In above-mentioned technical scheme, the distance between described A reverberator 19 and 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.
The invention has the advantages that:
SAW temperature sensor of the present invention is integrated form, its basic structure is to make the reverberator of an EWC/SPUDT2 and 11 short-circuit gate structures on piezoelectric substrate, received by wireless antenna by EWC/SPUDT and come from the electromagnetic wave signal that wireless reading unit is launched, and convert surface acoustic wave to, a reverberator direction is propagated on edge, piezoelectric substrate surface, and reflected by described reverberator respectively, the sound wave of reflection converts electromagnetic wave signal to again by EWC/SPUDT2, pass wireless reading unit back by wireless antenna, and pass through signal processing method, change to realize detection to temperature with the phase place of estimating time domain response.
Due to SAW reflective delay line 11 of the present invention, 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 Stacking of backpropagation, effectively promote the forward direction sound wave, and the propagation of reverse sound wave is even offset in inhibition, so just can effectively improve device loss, improve the signal-to-noise performance of reflective delay line.
Design a kind of structure of short-circuit gate reverberator in SAW reflective delay line 11, because this reverberator has higher reflection coefficient and zero acoustic-electric regenerative reflector, made the SAW reflective delay line have good signal to noise ratio (S/N ratio), reduced simultaneously the reflection peak-to-peak noise.
The present invention 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 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 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).Configure the position of reverberator by optimum design, obtain temperature compensation and the sensitivity improving of sensor with this.
11 reverberators that adopt the short-circuit gate structures provided by the invention, two paths that are placed in, 8 reverberators are that a path is used for 8 electronic tags, other 3 reverberators are arranged at an other paths, to realize the detection to temperature.
The present invention adopts at piezoelectric substrate 9 two ends coating sound absorption glue 18, is mainly used in eliminating the edge reflections of sound wave, the noise in time domain that causes to reduce the device edge reflections.
The present invention 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 effectively 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 invention forms schematic diagram;
Fig. 2 b is the SAW reflective delay line for the Integral wireless temperature sensor of the present invention;
Fig. 3 a is the structural representation of SAW reflective delay line of the present invention (EWC/SPUDT) that adopt;
Fig. 3 b is the structural representation of the short-circuit gate reverberator that adopts of SAW reflective delay line of the present invention;
Fig. 4 is the structural design drawing of SAW reflective delay line of the present invention;
Fig. 5 is the impedance matching network between integrated form SAW radio temperature sensor and wireless antenna in the present invention program;
Fig. 6 is the test time-domain response curve figure of SAW reflective delay line of the present invention.
Drawing is described as follows:
1. conventional SAW reflective delay line 2. transducer 3. first reverberators
4. the 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. element pasted on surface (SMD) 13. impedance matching network 14. wireless antennas
15. the electromagnetic wave signal 16. wireless reading units of sensor signal 17.
18. first, second sound absorption glue 19. an A reverberator 20. B reverberators
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. series winding inductance
33. and connect inductance
Embodiment
In order to make purpose of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is described in further details.
With reference to figure 2a, make an integrated form SAW temperature sensor, comprising: a SAW reflective delay line 11, element pasted on surface 12, and the impedance matching network 13 between SAW reflective delay line 11 and wireless antenna 14.
With reference to figure 2b, the SAW reflective delay line 11 of the embodiment of the present invention, by a piezoelectric substrate 9, and 2 and 11 short-circuit gate reverberator compositions of the transducer of making at this piezoelectric substrate 9 (transducer of the present embodiment adopt be control electrode width single phase unidirectional transducer, i.e. EWC/SPUDT).SAW reflective delay line 11 use 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 the present embodiment adopts the general potted element with 10 pins in this area.
The piezoelectric substrate 9 of the present embodiment adopts along 41 ° of Y-direction rotations, the niobic acid reason (LiNbO that directions X is propagated
3) substrate is as vibrating membrane; Its piezoelectric substrate 9 is of a size of (a * b, a:6mm, b:18mm), i.e. long 18mm, and wide 6mm, thickness are 41 ° of YXLiNbO of 350 μ m
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 along both sides, upper surface up and down, and apply the first sound absorption glue 18 in the middle of described two conducting films 10, described EWC/SPUDT2 arranges along a limit of conducting film 10; The other end of also growing limits at this piezoelectric substrate 9 applies the second sound absorption glue 18 (adopting this professional routine techniques to implement).Be mainly used in eliminating the edge reflections of sound wave, the noise in time domain that causes to reduce the device edge reflections.
With reference to figure 3a, the transducer of the 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 the reflecting electrode 30 that 5 electrode widths that arrange between 6 interdigital electrodes are to 31 are 1 λ/4 forms this single phase unidirectional transducer by 6 interdigital electrodes, and interdigital electrode can also be any number between 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 forms).The determining positions of reflecting electrode 30 is in piezoelectric substrate 9 and reflecting electrode 30 materials.Adopt in embodiments of the present invention 41 ° of YXLiNbO
3Substrate with
It is that reflecting electrode 30 is placed in interdigital electrode to 31 left side, the i.e. direction opposite with the sound wave of one-way radiation 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 in Fig. 2 a.
11 reverberators (A reverberator 19～a K reverberator 29) all adopt short-circuit gate reflector structure (concrete structure is as 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 Multi reflection device that reduces between reverberator, 11 reverberators, two paths that are placed in, A reverberator 19～a H reverberator 26 is placed in 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.Because the peripheral temperature variation causes the linear change of acoustic wave propagation velocity based on acoustic velocity and temperature linearity associate feature, thereby the Time Domain Reflectometry peak time delay that causes I reverberator 27～a K reverberator 29 that detects for temperature (T) 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 J reverberator 28, f
0Be working sensor frequency, v
0Be acoustic velocity under reference temperature (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 more large more might obtain higher detection sensitivity, yet to be that propagation distance is far away will cause very large propagation loss to the propagation attenuation of considering Acoustic Wave Propagation, therefore Acoustic Wave Propagation is controlled within limits to reduce the acoustic propagation loss apart from needs, in the present invention program, consider l
2/ l
1Value is about 3.
the basic structure of the integrated form SAW temperature sensor of the present embodiment is: the reverberator of making an EWC/SPUDT2 and above-mentioned 11 short-circuit gate structures on piezoelectric substrate 9, received by wireless antenna 14 by EWC/SPUDT 2 and come from the electromagnetic wave signal 15 that wireless reading unit 17 is launched, and convert surface acoustic wave to, propagate along 11 reverberator directions on piezoelectric substrate 9 surfaces, and reflected by described 11 reverberators respectively, the sound wave of reflection converts electromagnetic wave signal 16 to again by EWC/SPUDT2, pass wireless reading unit 17 back by wireless antenna 14, and by signal processing method (this is that those skilled in the art of the present technique are adequate), change to realize detection to temperature with the phase place of estimating time domain response.
in addition, propagation attenuation impact due to sound wave, 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 due to the acoustic propagation decay, A reverberator 19～the Cs the reverberator 21 nearest from EWC/SPUDT 2 adopts minimum number of electrodes (being 5 electrodes in the embodiment of the present invention), from EWC/SPUDT 2 more away from, the reflector electrode number is more, and (D-F reverberator 22～24 adopts 6 electrodes in embodiments of the present invention, G reverberator 25～a H reverberator 26 adopts 7 electrodes, I reverberator 22～a J reverberator 28 adopts 8 electrodes, adopt 9 electrodes from EWC/SPUDT 2 K reverberator 29 farthest).
In embodiments of the present invention, matching network 13 annexations between SAW reflective delay line 11 and wireless antenna 14, as shown in Figure 5, the input end N1 of the transducer 2 of SAW reflective delay line 11, with the inductance 32 of connecting in the signal end N3 connecting circuit of wireless antenna 14, and inductance 33 in parallel; The earth terminal N2 of E transducer 2 directly is connected with the earth terminal N4 of wireless antenna; Make between SAW reflective delay line 11 after encapsulation and wireless antenna 14 by this matching network 13 to reach the impedance matching state, 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, namely comprises 15 interdigital electrodes as shown in Fig. 3 a to 31, and is distributed in 14 reflecting electrodes 30 between electrode pair.
In the present embodiment, A reverberator 19 of described SAW reflective delay line 11 and the distance between EWC/SPUDT 2 are 3272.4 μ m, provide with this enough time delays that separate neighbourhood noise echo and the required at least 1.2 μ s of sensor signal.
What specific embodiment was made is applied in radio temperature sensor, the concrete structure of SAW reflective delay line 11 as shown in Figure 4, in figure, the dependency structure parameter is as follows:
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～a K reverberator 29 of C=: 5 * λ=54.5 μ m;
The sound aperture of A reverberator 19～a K reverberator 29 of D=: 50 * λ=545 μ m; H
1The length of=reverberator 19: 9 * (1/4 λ)=24.5 μ m;
H
2The length of the=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=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=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=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=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=the A reverberator 19 and EWC/SPUDT are 2: 3272.4 μ m;
l
2The distance that the=the B reverberator 20 and reverberator are 19: 383.4 μ m;
l
3The distance that the=the C reverberator 21 and reverberator are 20: 386.1 μ m;
l
4The distance that the=the D reverberator 22 and reverberator are 21: 388.8 μ m;
l
5The distance that the=the E reverberator 23 and reverberator are 22: 391.5 μ m;
l
6The distance that the=the F reverberator 24 and reverberator are 23: 394.2 μ m;
l
7The distance that the=the G reverberator 25 and reverberator are 24: 396.9 μ m;
l
8The distance that the=the H reverberator 26 and reverberator are 25: 399.6 μ m;
l
9The distance that the=the I reverberator 27 and reverberator are 26: 437.4 μ m;
l
10The distance that the=the J reverberator 28 and reverberator are 27: 442.8 μ m;
l
11The distance that the=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 the typical Time Domain Reflectometry coefficient S of 434MHz SAW reflective delay line 11 before the encapsulation of observing from the HP8510 network analyzer
11Response curve.11 reflection peaks come from 11 reverberators of SAW reflective delay line, have 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 the corresponding time delay of reflection peak 11 is 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 ratio (S/N ratio), comparatively sharp-pointed reflection peak and lower peak-to-peak noise have been realized than low-loss.
Above-described embodiment, the present invention embodiment a kind of more preferably just, the common variation that those skilled in the art carries out in technical solution of the present invention and replacing all should be included in protection scope of the present invention.
Claims (7)
1. the surface acoustic wave wireless temperature sensor of an integrated form, comprise SAW reflective delay line (11); Described SAW reflective delay line (11) is by a piezoelectric substrate (9), with upper along the Acoustic Wave Propagation direction at described piezoelectric substrate (9), two conducting films (10) that apply out on the both sides, up and down, and a set transducer (2) forms with reverberator; It is characterized in that: also comprise element pasted on surface (12), sound absorption glue, impedance matching network (13), wireless antenna (14) and reading unit (17), and the reverberator that arranges at this piezoelectric substrate (9) is 11;
Described piezoelectric substrate (9) is 41 ° of lithium niobate substrates of propagating along directions X of a Y-direction 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) arranges the second sound absorption glue;
Described transducer (2) is control electrode width single phase unidirectional transducer; This transducer (2), is reached the reflecting electrode that an electrode width is 1 λ/4 (30) composition is set between every 2 interdigital electrodes are to (31) (31) by 2 above interdigital electrodes, and wherein λ is wave length of sound; Described reflecting electrode (30) and described interdigital electrode are 3 λ/16 to the distance between (31), described interdigital electrode forms (31) electrode by two 1 λ/8 width, and described interdigital electrode is done by aluminum (31) and described reflecting electrode (30);
Described 11 reverberators are the short-circuit gate reverberator, and wherein, described each short-circuit gate reverberator is comprised 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, and the short-circuit gate reverberator word order that is equated by 8 sizes, spacing forms; An other paths is used for temperature detection, is comprised of 3 short-circuit gate reverberators, and setting position word order below last reverberator of continuing to use in 8 short-circuit gate reverberators of electronic tag forms;
Be connected a series inductance (32) in connecting circuit between the input end N1 of the transducer (2) of described SAW reflective delay line (11) and the signal end N3 of described wireless antenna (14), be connected the inductance (33) of a ground connection in the connecting circuit between the signal end N3 of described series inductance (32) and described wireless antenna (14); The earth terminal N4 of this wireless antenna (14) is electrically connected to the earth terminal N2 of described control electrode width single phase unidirectional transducer (2), realizes impedance matching between SAW reflective delay line (11) and 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, the protection of formation to the electrode of the transducer (2) of SAW reflective delay line (11), 11 reverberators and piezoelectric substrate (9) surface, and complete being electrically connected to of SAW reflective delay line (11) and impedance 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 propagate and be reflected back this control electrode width single phase unidirectional transducer (2) by 11 reflector sections along piezoelectric substrate (9) is surperficial, again convert electromagnetic wave signal (16) to, and pass reading unit (17) back by wireless antenna (14), also cause the variation of acoustic velocity due to the variation of peripheral temperature, thereby the time domain phase response that causes SAW reflective delay line (11), estimated to realize real-time detection to temperature by reading unit (17).
2. by the surface acoustic wave wireless temperature sensor of integrated form claimed in claim 1, it is characterized in that, the electromechanical coupling factor of described lithium niobate substrate is 17.2%, and acoustic propagation velocity is 4750m/s, 85ppm/ ℃ of first-order lag temperature coefficient.
3. by the surface acoustic wave wireless temperature sensor of integrated form claimed in claim 1, it is characterized in that, described transducer (2) refers to that logarithm is 10-20.
4. press the surface acoustic wave wireless temperature sensor of integrated form claimed in claim 1, it is characterized in that, the number of electrodes of described 11 reverberators arranges according to following rule: be that the A-C reverberator has minimum number of electrodes from 3 nearest reverberators of control electrode width single phase unidirectional transducer (2), 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. press the surface acoustic wave wireless temperature sensor of integrated form claimed in claim 1, it is characterized in that, the distance of described control electrode width single phase unidirectional transducer and A reverberator (19) is 3272.4 μ m, distance between B reverberator (20) and A reverberator (19) is 383.4 μ m, distance between C reverberator (21) and B reverberator (20) is 386.1 μ m, distance between D reverberator (22) and C reverberator (21) is 388.8 μ m, distance between E reverberator (23) and D reverberator (22) is 391.5 μ m, distance between F reverberator (24) and E reverberator (23) is 394.2 μ m, distance between G reverberator (25) and F reverberator (24) is 396.9 μ m, distance between H reverberator (26) and G reverberator (25) is 399.6 μ m, distance between I reverberator (27) and H reverberator (26) is 437.4 μ m, distance between J reverberator (28) and I reverberator (27) is 442.8 μ m, distance between K reverberator (29) and J reverberator (28) is 1309.5 μ m.
6. press the surface acoustic wave wireless temperature sensor of integrated form claimed in claim 5, it is characterized in that, the distance between described J reverberator (28) and K reverberator (29) is 3 times of distance between I reverberator (27) and J reverberator (28).
7. by the surface acoustic wave wireless temperature sensor of integrated form claimed in 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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| CN 200910084148 CN101644608B (en) | 2009-05-20 | 2009-05-20 | Integrated surface acoustic wave wireless temperature sensor |
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Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102313614B (en) * | 2011-07-14 | 2013-05-08 | 重庆大学 | Method and system for improving detection accuracy of delay line surface acoustic wave (Surface Acoustic Wave) sensor |
| CN102901580B (en) * | 2011-07-25 | 2014-05-28 | 上海工程技术大学 | Multicoupler-based surface acoustic wave temperature sensor |
| CN102853934B (en) | 2012-07-27 | 2015-04-15 | 上海赛赫信息科技有限公司 | Wireless temperature and humidity sensor and system and measuring method |
| CN102840927B (en) * | 2012-09-14 | 2014-09-17 | 中国科学院半导体研究所 | Surface acoustic wave temperature monitoring system suitable for gas insulated switch cabinet |
| CN102914384B (en) * | 2012-10-19 | 2014-04-30 | 武汉烽火富华电气有限责任公司 | Temperature detection method based on passive wireless surface acoustic wave temperature sensor |
| TW201508644A (en) * | 2013-08-16 | 2015-03-01 | guan-rong Zhong | Omnidirectional surface acoustic wave wireless recognition module |
| CN103954823B (en) * | 2014-05-14 | 2016-08-10 | 中国科学院声学研究所 | Surface acoustic wave current sensor |
| US10041842B2 (en) * | 2014-11-06 | 2018-08-07 | Applied Materials, Inc. | Method for measuring temperature by refraction and change in velocity of waves with magnetic susceptibility |
| US20170363483A1 (en) * | 2014-12-30 | 2017-12-21 | 3M Innovative Properties Company | Surface acoustic wave (saw) based temperature sensing for electrical conductor |
| RU2592055C1 (en) * | 2015-06-16 | 2016-07-20 | Открытое акционерное общество "Научно-производственное предприятие "Радар ммс" | Sensitive element on surface acoustic waves for temperature measurement |
| CN105185753A (en) * | 2015-08-13 | 2015-12-23 | 北京中科飞鸿科技有限公司 | Single bare surface acoustic wave chip miniaturized package based on LTCC technology |
| CN105333972A (en) * | 2015-11-26 | 2016-02-17 | 国网智能电网研究院 | Double-acoustic-path acoustic surface wave temperature sensor |
| CN105527994B (en) * | 2016-01-25 | 2017-11-14 | 张津瑜 | A kind of refrigerated case temperature control method based on sound wave thermometric |
| US10374266B2 (en) * | 2016-05-11 | 2019-08-06 | Ford Global Technologies, Llc | Wireless traction battery force sensor |
| US9970993B1 (en) * | 2017-02-16 | 2018-05-15 | Ford Global Technologies, Llc | Sensor system for measuring battery internal state |
| CN107202652A (en) * | 2017-06-07 | 2017-09-26 | 重庆工商大学 | A kind of utilization surface acoustic wave detects the system and detection method of automobile absorber temperature |
| CN108692824A (en) * | 2018-03-21 | 2018-10-23 | 中电科技德清华莹电子有限公司 | A kind of passive wireless acoustic surface wave temperature sensor |
| IT201900000418A1 (en) * | 2019-01-10 | 2020-07-10 | Consiglio Nazionale Ricerche | Sensorized device for the analysis of a fluid by means of acoustic waves |
| CN110836679B (en) * | 2019-11-04 | 2021-08-31 | 兰州中联电子科技有限公司 | SAW surface acoustic wave passive wireless sensor device |
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