CN101526501A - Unidirectional low-loss love wave sensor - Google Patents
Unidirectional low-loss love wave sensor Download PDFInfo
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- CN101526501A CN101526501A CN200810101503A CN200810101503A CN101526501A CN 101526501 A CN101526501 A CN 101526501A CN 200810101503 A CN200810101503 A CN 200810101503A CN 200810101503 A CN200810101503 A CN 200810101503A CN 101526501 A CN101526501 A CN 101526501A
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Abstract
The invention relates to a unidirectional low-loss love wave sensor. The love wave sensor comprises a piezoelectric substrate, an input interdigital transducer and an output interdigital transducer, where in the input interdigital transducer and the output interdigital transducer are respectively deposited at both ends of the piezoelectric substrate, a waveguide layer is covered on the piezoelectric substrate and adopts a low acoustic velocity film which has lower shear wave velocity than the piezoelectric substrate, and a sensitive film is covered at the middle part of the waveguide layer and is placed between the input interdigital transducer and the output interdigital transducer. The unidirectional low-loss love wave sensor is characterized in that both the input interdigital transducer and the output interdigital transducer adopt a single-phase unidirectional transducer; the waveguide layer adopts gold, silicon dioxide, polymethylmethacrylate or epoxy rein; the sensitive film can be biological sensitive film according to the demand of substance detection; and the input interdigital transducer and the output interdigital transducer can be covered inside the waveguide layer or fully exposed outside the waveguide layer. The invention can reduce the bidirectional loss of the transducers, thereby the insertion loss of the entire unidirectional low-loss love wave sensor is reduced.
Description
Technical field
The present invention relates to a kind of happy Pu's type sound wave (abbreviation Love wave) sensor, particularly relate to the unidirectional low-loss love wave sensor of the interdigital device of a kind of employing single phase single direction structure (SPUDT).
Background technology
The Love wave is a kind of of sound wave, is the surface shear shear wave of propagating in the thin layer acoustic duct on piezoelectric substrate surface.The particle vibration direction of Love wave is parallel to basic surface, so when substrate surface contacted with liquid load, its propagation was subjected to load effect little.Again because the thin layer acoustic duct is strapped in the surface with the Love wave energy, so the Love wave is very sensitive to surface disturbance.It is uncomplicated to add device making technics, and love wave sensor is suitable for liquid phase measuring.
Conventional love wave sensor structure, as shown in Figure 1.Described in Sensors and Actuators A 123-124 (2005) 267-273,5216312,5283037 and 5,321,331 3 pieces of documents of United States Patent (USP), on piezoelectric substrate 5, make two-way interdigital transducer 1, then, cover low velocity of sound film 4, at last, in the middle of two transducers 1, place object under test.Because what interdigital transducer adopted is bidrectional transducer, sound wave is propagated towards the both sides of transducer, and the actual sound wave that has only two transducers to propagate in opposite directions is utilized effectively, and the acoustic wave energy of Chuan Boing is lost dorsad, thereby the loss of sensor common bigger (greater than 15dB).
Conventional single phase single direction interdigital transducer (SPUDT) as shown in Figure 2, as a kind of structure (as shown in Figure 2) that can effectively reduce the two-way loss of transducer, is widely used in Surface Acoustic Wave Filter.As document IEEE Ultrasonics Symp., 1986, p.59-64 (Ddistributed Acoustic Reflection TransducerDART distributed acoustic reflection single phase unidirectional transducer), IEEE 1989 Ultrasonics Symposium Proceedingpp79-89 (Electrode Width Controlled SPUDT EWC/SPUDT electrode width control single phase unidirectional transducer), 1995 Ultrasonics Symposium Proceeding pp39-50 (Resonant SPUDT RSPUDT resonant mode single phase unidirectional transducer), 2000 IEEE Ultrasonics Symposium pp105-108, (Different-WidthSplit-Finger SPUDT, the division of the inhomogeneous width of DWSF SPUDT refers to single phase unidirectional transducer) four pieces of documents are described, when the reflection kernel of interdigital transducer departs from transducing center 3/8 λ and 5/8 λ (λ: in the time of the transducer Cycle Length), sound wave is propagated toward a direction and is strengthened, the another one direction weakens, and forms check configuration.
In the prior art,, be to need the key issue that solves as the insertion loss of the transducer of one of detection lower limit key factor of decision love wave sensor always.Conventional love wave sensor adopts bi-directional configuration, because the existence of the two-way loss of transducer, the detection lower limit that has limited sensor reduces.
Summary of the invention
The objective of the invention is to, overcome the defective of prior art, improve sensor performance, reduce the two-way loss of the existing love wave sensor of device, thereby a kind of unidirectional low-loss love wave sensor is provided from the configuration aspects of sensor.
The object of the present invention is achieved like this:
Unidirectional low-loss love wave sensor provided by the present invention, comprise piezoelectric substrate 5 and be deposited on the input interdigital transducer 1 and the output interdigital transducer 2 at its two ends respectively, be coated with ducting layer 4 on the described piezoelectric substrate 5, described ducting layer 4 adopts the shear wave velocities low velocity of sound film lower than piezoelectric substrate 5, the middle part of this ducting layer 4 is coated with sensitive membrane 3, described sensitive membrane 3 is placed in the middle of input interdigital transducer 1 and the output interdigital transducer 2, and it is characterized in that: described input interdigital transducer 1 and output interdigital transducer 2 all adopt single phase unidirectional transducer (SPUDT).
As a kind of selection of the present invention, described ducting layer adopts silicon dioxide (SiO2), polymethyl methacrylate (PMMA), zinc paste (ZnO), gold (Au) or epoxy resin (Epoxy); Described sensitive membrane 3 can be bio-sensitive film according to the needs of detection material.
As a kind of improvement of the present invention, described input interdigital transducer 1 and output interdigital transducer 2 parts can be coated within the ducting layer 4 or be exposed to fully outside the ducting layer, respectively as shown in Figures 2 and 3.
As another selection of the present invention, described input interdigital transducer 1 and output interdigital transducer 2 adopt electrode width control single phase single direction interdigital transducer (EWC/SPUDT), distributed single phase single direction interdigital transducer (DART), resonant mode single phase single direction interdigital transducer (RSPUDT) or bipolar electrode single phase single direction interdigital transducer (DWSF).Whether input and output use unidirectional this of a certain class individual event not limit simultaneously, but conventional design generally all is with of a sort.
As another selection of the present invention, described input interdigital transducer 1 and output interdigital transducer 2 adopt Al film, Au film or Cu film.
As another kind of selection the of the present invention, described piezoelectric substrate 5 adopts various tangential materials, can adopt lithium niobate LiNbO3, lithium tantalate LiTaO3, quartz or piezoelectric ceramics.
As shown in Figure 1, technical scheme of the present invention contains piezoelectric substrate 5, input interdigital transducer 1, output interdigital transducer 2, ducting layer 4 and sensitive membrane 3, it is characterized in that: input interdigital transducer 1 excite sound waves in piezoelectric substrate 5 and ducting layer 4 is propagated, output transducer 2 receives sound wave, characteristic (as frequency, the speed etc.) variation that measured object that loads and sensitive membrane 3 react and cause sound wave, these variations can obtain the conclusion about described measured object.Described input interdigital transducer 1 and output interdigital transducer 2 all adopt single phase single direction interdigital transducer structure, and the sound wave that transducer excites is mainly propagated towards the direction of another transducer, has reduced the two-way loss of transducer.
Described love wave sensor adopts the Love wave pattern, covers ducting layer 4 on piezoelectric substrate 5, and this ducting layer material shear wave velocity must lower than the substrate (being called for short low velocity of sound film).Low velocity of sound film adopts Au, SiO2, PMMA, Epoxy etc. usually, and its body shear wave velocity is as shown in table 1 respectively, and low velocity of sound film makes the Love wave propagate along ducting layer and substrate surface.
Table 1:
| Low velocity of sound membrane material | Au | SiO2 | PMMA | Epoxy |
| Body shear wave velocity [m/s] | 1215 | 2800 | 1180 | 1210 |
The invention has the advantages that the input and output transducer of love wave sensor of the present invention all adopts single phase single direction interdigital transducer (SPUDT).Because the employing of SPUDT structure can reduce the two-way loss of transducer, thereby reduce the insertion loss of entire device.Compared to existing technology, single phase single direction love wave sensor of the present invention loss is low, can realize lower detection lower limit.
Description of drawings
Fig. 1 is the schematic perspective view of unidirectional low-loss love wave sensor structure of the present invention;
Fig. 2 is the vertical view of unidirectional low-loss love wave sensor structure of the present invention;
Fig. 3 is the diagrammatic cross-section of a kind of structure of love wave sensor of the present invention;
Fig. 4 is the diagrammatic cross-section of another structure of love wave sensor of the present invention;
Fig. 5 is the electrode width control single phase single direction interdigital transducer structural drawing in the embodiment of the invention 1;
Fig. 6 is the distributed single phase single direction interdigital transducer structural drawing in the embodiment of the invention 2;
Fig. 7 is the resonant mode single phase single direction interdigital transducer structural drawing in the embodiment of the invention 3;
Fig. 8 is that the inhomogeneous width division in the embodiment of the invention 4 refers to the single phase unidirectional transducer structural drawing.
Embodiment
Embodiment 1: make a low-loss love wave sensor with single phase single direction structure by Fig. 1.
Embodiment 2: make a low-loss love wave sensor with single phase single direction structure by Fig. 1, its basic structure is identical with embodiment 1.
Do not exist together and adopt 36 degree YX lithium tantalate LiTaO3 for: piezoelectric substrate 1; Input interdigital transducer 3 and output interdigital transducer 4 adopt distributed single phase single direction interdigital transducer (DART) structure, and as shown in Figure 3, cycle λ is 40 microns, the gold thickness is 1000 dusts, refers to that logarithm is 60, and the aperture is 4 millimeters, 4 millimeters of two transducer Center Gap, centre frequency f
0Be about 104MHz; The Love wave ducting layer adopts polymethyl methacrylate, and thickness is 0.2 micron.The phase electrode width is 1/8th wavelength weekly, and the reflecting electrode width is eight/three-wavelength, and distributed white space is arranged on the reflecting electrode.
Embodiment 3: make a low-loss love wave sensor with single phase single direction structure by Fig. 1, its basic structure is identical with embodiment 1.
Do not exist together for: input interdigital transducer 3 and output interdigital transducer 4 adopts resonant mode single phase single direction interdigital transducer (RSPUDT) structures, as shown in Figure 4, cycle λ is 50 microns, the aluminium thickness is 2000 dusts, refer to that logarithm is for being respectively 16 and 64, the aperture is 2 millimeters, 4.5 millimeters of two transducer Center Gap, centre frequency f
0=90MHz; Comprise 1 forward in each acoustic resonance cavity and excite the unit, 1 negative sense excites the unit, and 1 length is quarter-wave transition element.The Love wave ducting layer adopts zinc paste, and thickness is 2.8 microns.
Embodiment 4: make a low-loss love wave sensor with single phase single direction structure by Fig. 1, its basic structure is identical with embodiment 1.
Do not exist together and adopt 31 degree XY cuttings quartzy for: piezoelectric substrate 1; Input interdigital transducer 3 and output interdigital transducer 4 adopt inhomogeneous width division to refer to single phase unidirectional transducer (DWSF RSPUDT) structure, and as shown in Figure 4, cycle λ is 52 microns, copper film is thick to be 4500 dusts, refer to that logarithm is 50, the aperture is 3 millimeters, centre frequency f
0Be about 86MHz; Phase is contained width be respectively the interdigital electrode of L1 and L2 each is a pair of weekly.The Love wave ducting layer adopts silicon dioxide, and thickness is 5 microns.
Claims (7)
1, a kind of unidirectional low-loss love wave sensor, comprise piezoelectric substrate (5) and be deposited on the input interdigital transducer (1) and the output interdigital transducer (2) at its two ends respectively, be coated with ducting layer (4) on the described piezoelectric substrate (5), described ducting layer (4) adopts the shear wave velocity low velocity of sound film lower than piezoelectric substrate (5), the middle part of this ducting layer (4) is coated with sensitive membrane (3), described sensitive membrane (3) is placed in the middle of input interdigital transducer (1) and the output interdigital transducer (2), and it is characterized in that: described input interdigital transducer (1) and output interdigital transducer (2) all adopt single phase unidirectional transducer.
2, love wave sensor according to claim 1 is characterized in that: described ducting layer adopts silicon dioxide, polymethyl methacrylate, zinc paste, gold or epoxy resin.
3, love wave sensor according to claim 1 is characterized in that: described sensitive membrane (3) is a bio-sensitive film.
4, love wave sensor according to claim 1 is characterized in that: described input interdigital transducer (1) and output interdigital transducer (2) part can be coated within the ducting layer (4) or be exposed to outside the ducting layer (4).
5, love wave sensor according to claim 1 is characterized in that: described input interdigital transducer (1) and output interdigital transducer (2) adopt electrode width control single phase single direction interdigital transducer, distributed single phase single direction interdigital transducer, resonant mode single phase single direction interdigital transducer or bipolar electrode single phase single direction interdigital transducer.
6, love wave sensor according to claim 1 is characterized in that: described input interdigital transducer (1) and output interdigital transducer (2) adopt Al film, Au film or Cu film.
7, love wave sensor according to claim 1 is characterized in that: described piezoelectric substrate (5) adopts various tangential materials, can adopt lithium niobate LiNbO3, lithium tantalate LiTaO3, quartz or piezoelectric ceramics.
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| CN2008101015032A CN101526501B (en) | 2008-03-07 | 2008-03-07 | Unidirectional low-loss love wave sensor |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102305827A (en) * | 2011-08-24 | 2012-01-04 | 南京航空航天大学 | Love wave sensor testing system based on frequency sweeping technology, and a testing method thereof |
| CN102739188A (en) * | 2012-06-29 | 2012-10-17 | 长安大学 | Unidirectional conductor sound wave restrained type sound surface wave device |
| CN102749130A (en) * | 2012-06-29 | 2012-10-24 | 长安大学 | Measuring device for LOVE-waveform ultramicro matter mass |
| CN109444272A (en) * | 2018-10-22 | 2019-03-08 | 中国人民解放军国防科技大学 | Nonlinear guided wave detection combined transducer and manufacturing method and using method thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5283037A (en) * | 1988-09-29 | 1994-02-01 | Hewlett-Packard Company | Chemical sensor utilizing a surface transverse wave device |
| JP2645674B2 (en) * | 1990-10-15 | 1997-08-25 | 国際電気株式会社 | Surface acoustic wave resonator |
| JP3173300B2 (en) * | 1994-10-19 | 2001-06-04 | 株式会社村田製作所 | Love wave device |
| CN100571026C (en) * | 2004-03-30 | 2009-12-16 | 中国科学院声学研究所 | SAW (Surface Acoustic Wave) delay line with single phase single direction structure |
| CN101055204A (en) * | 2007-04-30 | 2007-10-17 | 电子科技大学 | Love wave chemical sensor with high sensitivity and its preparation method |
-
2008
- 2008-03-07 CN CN2008101015032A patent/CN101526501B/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102305827A (en) * | 2011-08-24 | 2012-01-04 | 南京航空航天大学 | Love wave sensor testing system based on frequency sweeping technology, and a testing method thereof |
| CN102305827B (en) * | 2011-08-24 | 2013-05-29 | 南京航空航天大学 | Love wave sensor testing system based on frequency sweeping technology, and a testing method thereof |
| CN102739188A (en) * | 2012-06-29 | 2012-10-17 | 长安大学 | Unidirectional conductor sound wave restrained type sound surface wave device |
| CN102749130A (en) * | 2012-06-29 | 2012-10-24 | 长安大学 | Measuring device for LOVE-waveform ultramicro matter mass |
| CN102749130B (en) * | 2012-06-29 | 2014-11-05 | 长安大学 | Measuring device for LOVE-waveform ultramicro matter mass |
| CN102739188B (en) * | 2012-06-29 | 2015-07-15 | 长安大学 | Unidirectional conductor sound wave restrained type sound surface wave device |
| CN109444272A (en) * | 2018-10-22 | 2019-03-08 | 中国人民解放军国防科技大学 | Nonlinear guided wave detection combined transducer and manufacturing method and using method thereof |
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