CN105510434A - Surface acoustic wave gas sensor - Google Patents
Surface acoustic wave gas sensor Download PDFInfo
- Publication number
- CN105510434A CN105510434A CN201410496871.7A CN201410496871A CN105510434A CN 105510434 A CN105510434 A CN 105510434A CN 201410496871 A CN201410496871 A CN 201410496871A CN 105510434 A CN105510434 A CN 105510434A
- Authority
- CN
- China
- Prior art keywords
- module
- saw
- phase
- wave gas
- power splitter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
A surface acoustic wave (SAW) gas sensor has excellent linearity and sensitivity being 21Hz/mg/cm3 within the concentration range of 1-100 mg/m<3>, and not only ensures output characteristics but also solves a timing problem due to change on working voltage, thereby achieving more real noise simulation. The gas sensor is formed in a dual-sound-path differential structure which is characterized in that one sound path includes a matching network module which is connected to an amplifier module, the amplifier module is connected to a phase-shift network module, the phase-shift network module is connected to a power divider module, the power divider module is connected to the matching network module, and the output of the power divider module is connected to a frequency mixer; and the other one sound path includes a matching network module which is connected to an amplifier module, the amplifier module is connected to a phase-shift network module, the phase-shift network module is connected to a power divider module, the power divider module is connected to the matching network module, and the output of the power divider module is connected to a frequency mixer. A sensitive membrane and a SAW dual-delay module are arranged inside the sensor.
Description
Technical field
The invention belongs to surface acoustic wave field, specifically a kind of sonic surface wave gas sensors.
Background technology
The energy of surface acoustic wave (SAW) mainly concentrates in the scope of following 1 ~ 2 wavelength in surface, and the change of effects on surface characteristic is more responsive.Therefore, by the deposition of material of specific gas sensitivity in SAW device, the physical influence of gas and sensitive membrane will cause the change of SAW speed.Multiple gases can be detected by depositing different sensitive materials.
The performance of SAW gas sensor depends primarily on two aspects: sensitive membrane and SAW oscillator.At present, the research of SAW gas sensor mainly focuses on the characteristic of gas sensitization film, comprise the type of film, thickness, to the analysis viscoelastic change of adsorbate and film technique.The frequency stability of SAW oscillator affects sensitivity, detection thresholding etc., and optimization frequency stability Design will effectively improve the performance of SAW sensor.
The sensitive mechanism of SAW sensor is that the disturbance as SAW travel path causes the change of velocity of wave according to the surface disturbance of gas to sensitive membrane, correspondingly can cause the change of SAW alternator resonant frequency.At present, usually adopt the SAW oscillator of delay-line structure, and consider the corrosion resistance of Au, interdigital transducer (IDT) electrode generally adopts Au.The detection of such SAW gas sensor to gas concentration is reflected by the change of the oscillation frequency of SAW delay line oscillator, but the factor in actual applications, changing oscillator vibrates frequency also has the impact of external environment change (temperature, humidity and vibration etc.) except sensitive membrane quality loading effect or conductance change.In order to ensure the stability of sensing system, the impact of suppression environmental factor of must taking measures.
Summary of the invention
The present invention is exactly for the problems referred to above, makes up the deficiencies in the prior art, provides a kind of at 1 ~ 100mg/m
3concentration range in the linearity that had and 21Hz/mg/cm
3the sonic surface wave gas sensors of sensitivity.
For realizing above-mentioned purpose of the present invention, the present invention adopts following technical scheme.
A kind of sonic surface wave gas sensors of the present invention, wherein have employed alliteration road difference structure; Its design feature is: a sound travel comprises matching network model calling amplifier module, described amplifier module connects phase-shift network module, described phase-shift network model calling power splitter module, described power splitter model calling matching network module, and power splitter module exports and connects frequency mixer; Another means of livelihood comprise matching network model calling amplifier module, described amplifier module connects phase-shift network module, described phase-shift network model calling power splitter module, described power splitter model calling matching network module, and power splitter module exports and connects frequency mixer; Sensor internal comprises sensitive membrane, the two Postponement module of SAW.
Employing alliteration road of the present invention difference structure a: sound travel covers has optionally sensitive membrane, is used as to measure sound travel; Another sound travel is then as a reference to offset the impact of changes in environmental conditions (temperature, humidity and vibration etc.) to greatest extent; According to differential principle, by getting the difference frequency of two-way oscillator, can from the impact suppressing changes in environmental conditions to a great extent.
As a preferred embodiment of the present invention, described sonic surface wave gas sensors SAW adopts the SAW oscillator of delay-line structure, and considers the corrosion resistance of Au, and interdigital transducer (IDT) electrode generally adopts Au.
As another kind of preferred version of the present invention, the monofilm selectivity of described SAW lag line, is realized by the frequency response combination of long input IDT and short output IDT.
Secondly, the frequency stability of IL and Q value on SAW oscillator of the SAW lag line of the present invention's frequency control elements produces important impact.The easier starting of oscillation of low IL, under the condition meeting starting of oscillation, the gain of amplifier also can be lower, this reduces the power consumption of oscillator, also enhance the temperature stability of oscillator simultaneously, improves stability and the sensitivity of system.
As another kind of preferred version of the present invention, described low IL controls the realization of unidirectional single-phase transducer (EWC/SPUDT) by electrode width; For suppressing sideband, adopt the form of withdraw-weighted.
As another kind of preferred version of the present invention, the raising of SAW surface acoustic wave gas sensor of the present invention sensitivity is beamwriter lithography (EBL) technology adopting resolution higher, adopts EBL and stripping technology to have combined the making of IDT.
The invention has the beneficial effects as follows.
The present invention is directed to the noise simulation source randomizer in sensing system, design proposes and a kind ofly the control signal amplitude of oscillation avoiding can be subject to the circuit structure of sequential impact.By the control of signal swing and the optimization to random series complexity, achieve while guarantee output characteristic, the sequence problem that the change solving operating voltage brings, reach the object of more real noise simulation.
The Design and manufacture of SAW gas sensor of the present invention.For improving stability and sensitivity, the SAW lag line of research filter with low insertion loss (IL) and the performance optimization of sensitive membrane.The present invention have selected gas Simulated gas dimethyl methyl phosphonate (DMMP) as gas to be measured and MUA as gas sensitive, and be improve sensitivity and selectivity, sensitive material adopts Cu2+ chemical modification and molecular self-assembling film technique; Achieve at 1 ~ 100mg/m
3concentration range in the linearity that had and 21Hz/mg/cm
3sensitivity.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of sonic surface wave gas sensors SAW of the present invention.
Embodiment
As shown in Figure 1, be the structural representation of a kind of sonic surface wave gas sensors SAW of the present invention.Wherein have employed alliteration road difference structure; Its design feature is: a sound travel comprises matching network model calling amplifier module, described amplifier module connects phase-shift network module, described phase-shift network model calling power splitter module, described power splitter model calling matching network module, and power splitter module exports and connects frequency mixer; Another means of livelihood comprise matching network model calling amplifier module, described amplifier module connects phase-shift network module, described phase-shift network model calling power splitter module, described power splitter model calling matching network module, and power splitter module exports and connects frequency mixer; Sensor internal comprises sensitive membrane, the two Postponement module of SAW.
Monitoring lower-cut of the present invention and sensitivity are the key indexs evaluating SAW gas sensor performance.From the physical angle analysis of sensor, the key factor affecting these two indexs is frequency of operation and the frequency stability of SAW oscillator.
Frequency stability can be expressed as relative to the single sideband frequency modulation noise in the every hertz bandwidth of oscillator signal in units of dB of described SAW oscillator: 10lgSRF (Δ f)=10lg ［ GkT (NF) f20/ (QP0 Δ f2) ］ (1).Wherein, G is the power amplification multiple of amplifier, and NF is the noise figure of amplifier, f0 is the centre frequency of oscillator, and f is departing from centre frequency, and k is Boltzmann constant, T is absolute temperature, and Q is the equivalent quality factor of SAW lag line, and P0 is the saturation output power of amplifier.The frequency stability of visible light transducer system and the IL of lag line, Q value, loop temperature variation, peripheral oscillatory circuit noises etc. are relevant, here key be to reduce lag line IL and put forward high q-factor.
The sensitivity of described SAW sensor is: Δ fv/f0=Δ vR/vR=(k1+k2) × f0 × Δ mv/S (2).Wherein, Δ f is the difference on the frequency produced after film adsorbed gas, and f0 is the centre frequency of oscillator, k1 and k2 is membrane material constant, and Δ mv is the gaseous mass of absorption, and S is sensitizing range area.Sensitivity is relevant with frequency of operation and sensitive membrane, and from physical angle, the raising of frequency of operation is conducive to the raising of transducer sensitivity.
The frequency stability of IL and Q value on SAW oscillator of the SAW lag line of the present invention's frequency control elements produces important impact.The easier starting of oscillation of low IL, under the condition meeting starting of oscillation, the gain of amplifier also can be lower, this reduces the power consumption of oscillator, also enhance the temperature stability of oscillator simultaneously, improves stability and the sensitivity of system.Described low IL controls the realization of unidirectional single-phase transducer (EWC/SPUDT) by electrode width; For suppressing sideband, adopt the form of withdraw-weighted.
The raising of SAW surface acoustic wave gas sensor of the present invention sensitivity is beamwriter lithography (EBL) technology adopting resolution higher, adopts EBL and stripping technology to have combined the making of IDT.
For improving the sensitivity of SAW gas sensor, the frequency improving SAW oscillator is a kind of effective mode, and the present invention devises the SAW delay line that centre frequency is 480MHz.Traditional optical lithography is difficult to the effect obtained at below 800nm to intensive bargraphs, therefore, adopt higher beamwriter lithography (EBL) technology of resolution can solve the branch problem of intensive bargraphs.For avoiding dry etching to the physical damnification of substrate surface, EBL and stripping technology is adopted to have combined the making of IDT.For improving the stability of sensing system, the Piezoelectric Substrates that experiment adopts is that the ST with zero-lag temperature coefficient cuts quartz crystal; Au has inertia and anticorrosion properties, can be elected to be the electrode material of IDT.First in Piezoelectric Substrates, apply 350nm electronic corrosion-resistant ZEP520A, on resist, then evaporate the conductive sacrificial layer of Al as EBL of one deck 10nm.
The performance index of SAW gas sensor depend on the thickness of sensitive membrane, homogeneity and the tack for substrate surface to a great extent, and this just needs the film technique with good reproducibility and controlled chemo-selective sensitive membrane.MUA is as the sensitive membrane material of self assembly, and it has good selectivity and sensitivity to organic phosphorus compound.Due to surperficial at Au, the easy oxidized production Au chemical combination film of hydroxyl, binding ability is strong, so the thin film stability formed is good, the mode of self assembly simultaneously film forming is also very simple.Here the film of numerator self-assembly technique preparation to gas Simulated gas DMMP sensitivity is adopted using MUA as gas sensitive.
Claims (5)
1. a sonic surface wave gas sensors, wherein have employed alliteration road difference structure; It is characterized in that: a sound travel comprises matching network model calling amplifier module, described amplifier module connects phase-shift network module, described phase-shift network model calling power splitter module, described power splitter model calling matching network module, power splitter module exports and connects frequency mixer; Another means of livelihood comprise matching network model calling amplifier module, described amplifier module connects phase-shift network module, described phase-shift network model calling power splitter module, described power splitter model calling matching network module, and power splitter module exports and connects frequency mixer; Sensor internal comprises sensitive membrane, the two Postponement module of SAW.
2. a kind of sonic surface wave gas sensors according to claim 1, is characterized in that: described sonic surface wave gas sensors SAW adopts the SAW oscillator of delay-line structure, and interdigital transducer (IDT) electrode generally adopts Au.
3. a kind of sonic surface wave gas sensors according to claim 1, is characterized in that: the monofilm selectivity of described SAW lag line, is realized by the frequency response combination of long input IDT and short output IDT.
4. a kind of sonic surface wave gas sensors according to claim 1, is characterized in that: described low IL controls the realization of unidirectional single-phase transducer (EWC/SPUDT) by electrode width, adopts the form of withdraw-weighted.
5. a kind of sonic surface wave gas sensors according to claim 4, it is characterized in that: the raising of described SAW surface acoustic wave gas sensor sensitivity is beamwriter lithography (EBL) technology adopting resolution higher, adopt EBL and stripping technology to have combined the making of IDT.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410496871.7A CN105510434A (en) | 2014-09-25 | 2014-09-25 | Surface acoustic wave gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410496871.7A CN105510434A (en) | 2014-09-25 | 2014-09-25 | Surface acoustic wave gas sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN105510434A true CN105510434A (en) | 2016-04-20 |
Family
ID=55718565
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410496871.7A Pending CN105510434A (en) | 2014-09-25 | 2014-09-25 | Surface acoustic wave gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN105510434A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110231399A (en) * | 2019-07-08 | 2019-09-13 | 电子科技大学 | A kind of Surface Acoustic Waves Humidity Sensor based on bacteria cellulose sensing membrane |
-
2014
- 2014-09-25 CN CN201410496871.7A patent/CN105510434A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110231399A (en) * | 2019-07-08 | 2019-09-13 | 电子科技大学 | A kind of Surface Acoustic Waves Humidity Sensor based on bacteria cellulose sensing membrane |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7219536B2 (en) | System and method to determine oil quality utilizing a single multi-function surface acoustic wave sensor | |
| US8658097B2 (en) | Sensor for detecting substance in liquid | |
| CN101135670B (en) | Two-channel sonic surface wave gas sensors having humidity compensate function | |
| TWI427290B (en) | A gas sensor and method thereof | |
| CN101726538A (en) | Surface acoustic wave gas sensor and manufacturing method thereof | |
| CN108872063B (en) | Trace substance detection device and method based on parameter excitation and synchronous resonance | |
| CN101458230A (en) | Multichannel surface acoustic wave chemical sensing system | |
| CN105738470B (en) | A kind of sonic surface wave gas sensors | |
| CN109506808B (en) | SAW temperature sensor with monotone and linear output characteristics and design method thereof | |
| US7762124B2 (en) | Sensor for detecting substance in liquid | |
| CN106895803A (en) | A kind of device and methods influenceed using two SAW resonator separation temperatures | |
| CN105510434A (en) | Surface acoustic wave gas sensor | |
| Pang et al. | Selective detection of CO 2 and H 2 O dual analytes through decoupling surface density and shear modulus based on single SAW resonator | |
| CN107040234A (en) | A kind of highly sensitive both-end is to resonant mode surface acoustic wave detector | |
| KR100698439B1 (en) | Surface acoustic wave gas sensor for detecting volatile chemicals | |
| CN108933579B (en) | Acoustic surface wave single-end-to-resonator | |
| CN205647458U (en) | High sensitivity's bi -polar is to resonant mode surface acoustic wave detector | |
| KR20160009374A (en) | Using lithium niobate surface acoustic wave biosensor | |
| Wen et al. | Carbon dioxide gas sensor using SAW device based on ZnO film | |
| CN114942444A (en) | Flexible surface acoustic wave icing sensor based on wireless and passive | |
| CN204068886U (en) | A kind of testing circuit of SAW gas sensor | |
| Becker et al. | Multistrip couplers for surface acoustic wave sensor application | |
| Ndao et al. | Sensitivity range optimization of surface acoustic wave humidity ultrasonic sensors incorporating a polyvinyl alcohol (PVA) layer | |
| Le et al. | Highly sensitive AIN surface acoustic wave humidity sensor based on uniform graphene oxide thin film formed by surface tension | |
| Pang et al. | A humidity sensor based on lamb wave resonator with different graphene oxide film |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20160420 |
|
| WD01 | Invention patent application deemed withdrawn after publication |