CN111174933A - FBG temperature sensor based on bimetal cantilever beam and application thereof - Google Patents
FBG temperature sensor based on bimetal cantilever beam and application thereof Download PDFInfo
- Publication number
- CN111174933A CN111174933A CN202010006596.1A CN202010006596A CN111174933A CN 111174933 A CN111174933 A CN 111174933A CN 202010006596 A CN202010006596 A CN 202010006596A CN 111174933 A CN111174933 A CN 111174933A
- Authority
- CN
- China
- Prior art keywords
- cantilever beam
- temperature sensor
- bimetal
- fbg temperature
- thermal
- 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.)
- Withdrawn
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
Abstract
The invention relates to the technical field of fiber bragg grating sensing, in particular to an FBG temperature sensor based on a bimetallic cantilever beam and application thereof. The FBG temperature sensor comprises a thermal bimetallic cantilever beam formed by a thermal bimetallic strip, wherein an optical fiber Bragg grating is arranged on the outer side of an active layer of the thermal bimetallic strip and extends in the direction between the fixed end and the free end of the thermal bimetallic cantilever beam. This application is achieved by the FBG temperature sensor described above. The invention can better carry out sensitization on the existing FBG temperature sensor.
Description
Technical Field
The invention relates to the technical field of fiber bragg grating sensing, in particular to an FBG temperature sensor based on a bimetallic cantilever beam and application thereof.
Background
The temperature is one of basic physical quantities given by international units, is one of main parameters needing to be measured and controlled frequently in industrial and agricultural production and scientific experiments, and is an important physical quantity most closely related to daily life of people. At present, the most common electrical temperature sensors are thermocouple temperature sensors and thermistor temperature sensors, but both of the two types of sensors have the defects of low measurement accuracy, poor long-term stability, incapability of long-distance transmission, no electromagnetic interference resistance and the like, and cannot meet the working and using requirements in severe environments such as strong electromagnetic interference radiation and the like.
The k.o.hill et al, the ottawa communication research center in canada, first discovered the photosensitive effect of the fiber in germanium-doped silica fiber in 1978, and made the first Fiber Bragg Grating (FBG) in the world by the standing wave writing method. The temperature sensitive characteristic of the FBG is discovered later, and a sensing technology using the FBG for temperature measurement is gradually developed, and a temperature sensor with the FBG as a main core device is called an FBG temperature sensor. The FBG temperature sensor has the advantages of small volume, low loss, high sensitivity, electromagnetic interference resistance, good electrical insulation, large bandwidth and the like, can realize multipoint distributed measurement, is widely applied to industrial and agricultural production and scientific experiments, and has rich research results.
However, the practical requirements of temperature measurement have been driving researchers to improve the resolution and sensitivity of temperature measurement, such as protective packaging and sensitized packaging of FBGs. The protective packaging and the sensitization packaging mainly comprise: the metal substrate type packaging is adopted, two ends of the FBG are respectively fixed on the surface of the substrate material to play a role in protecting the FBG, and if the thermal expansion coefficient of the substrate is greater than that of the optical fiber, the temperature sensitivity of the sensor can be improved; the polymer packaging selects a polymeric region material (such as polyimide fiber) with a larger thermal expansion coefficient as a substrate, and compared with the metal substrate packaging, the FBG temperature sensor manufactured by the polymer packaging method has higher sensitivity. Whether the metal substrate type package or the polymer package has a defect in damage resistance, so that the metal tube package or the box-shaped package is used for protective packaging on the outside on the basis of the metal substrate type package or the polymer package to meet the actual use requirement. In addition, the sensitivity of the sensor is improved by means of metallization coating packaging, micro-nano processing packaging, special optical fibers and the like, but the technology is high in cost and far from practical application.
With the rapid development of social economy, the requirements of various industries on the sensitivity of the temperature sensor are higher and higher. Therefore, the method and the structure for improving the sensitivity of the FBG temperature sensor are continuously researched, the FBG sensor with high temperature sensitivity is developed, and the method and the structure have great significance for industrial and agricultural production and scientific experimental development.
Disclosure of Invention
The present invention provides a bi-metallic cantilever beam based FBG temperature sensor that overcomes some or all of the disadvantages of the prior art.
The FBG temperature sensor based on the bimetal cantilever beam comprises the bimetal cantilever beam formed by the bimetal strip, wherein the outer side of the bimetal strip active layer is provided with the fiber Bragg grating, and the fiber Bragg grating extends in the direction between the fixed end and the free end of the bimetal cantilever beam.
Compared with the traditional sensor structure which only adopts the fiber Bragg grating for temperature measurement, the invention can introduce additional deformation amount for the fiber Bragg grating by utilizing the characteristic of thermal deformation of the thermal bimetallic strip, thereby better improving the sensing sensitivity of the fiber Bragg grating. In addition, the thermal bimetal cantilever beam is built, and the fiber Bragg grating extends in the direction between the fixed end and the free end of the thermal bimetal cantilever beam, so that the linearity of the fiber Bragg grating in the sensing process can be ensured in a teaching mode. Through the structure, the FBG temperature sensor has the advantages of better anti-interference performance, good long-term stability, high measurement precision and the like, and further can carry out high-precision and high-resolution temperature measurement in a severe environment with high temperature, high voltage and strong electromagnetic interference.
In addition, compared with the traditional sensitivity enhancing mode aiming at the FBG temperature sensor, the sensitivity enhancing device does not need a special packaging structure, and when the sensitivity enhancing device is used specifically, one end of the thermal bimetallic strip can be directly fixed at the measuring surface or through the fixing structure described below, so that the construction of the thermal bimetallic cantilever beam is realized, and the sensitivity enhancing device is convenient to produce, manufacture and use.
Preferably, the thermal bimetal is rectangular, one end of the thermal bimetal in the length direction is configured as a fixed end of the thermal bimetal cantilever, and the other end of the thermal bimetal in the length direction is configured as a free end of the thermal bimetal cantilever. The shape through setting up hot bimetallic strip is the rectangle, and makes hot bimetallic strip be stiff end A, the other end is free end B along length direction's one end, keeps fiber bragg grating to set up along hot bimetallic strip's length direction simultaneously, can guarantee the linear relation between extra strain and the temperature change that introduces through hot bimetallic strip better to can guarantee FBG temperature sensor's linearity better.
Preferably, the thermal bimetal cantilever beam fixing structure further comprises a fixing structure arranged at the fixing end of the thermal bimetal cantilever beam, and the fixing structure is fixedly connected with the corresponding end of the thermal bimetal. Thereby the fixing of the thermal bimetal cantilever beam can be preferably realized.
Preferably, the fixing structure comprises a fixing plate or a fixing surface. Thereby facilitating the setup.
Preferably, the fiber bragg grating is applied at the thermal bimetal. So that the transfer of strain can be preferably facilitated.
Preferably, the fiber bragg grating is welded to the thermal bimetallic strip. Thereby being better convenient for fixing.
The invention also provides an application of the FBG temperature sensor based on any bimetallic cantilever beam in measuring temperature. So that the measurement of the temperature can be preferably facilitated.
Preferably, the FBG temperature sensor is calibrated and then the temperature is measured. So that the FBG temperature sensor can be preferably calibrated.
Drawings
Fig. 1 is a schematic view of an FBG temperature sensor in example 1 when the thermal bimetal is not deformed;
fig. 2 is a schematic view of the FBG temperature sensor in example 1 when the thermal bimetal is deformed.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples. It is to be understood that the examples are illustrative of the invention and not limiting.
Example 1
As shown in fig. 1 and 2, the present embodiment provides an FBG temperature sensor based on a bimetal cantilever, which includes a bimetal cantilever 120 formed by a bimetal strip 110, wherein a fiber bragg grating 130 is disposed on an outer side of an active layer 111 of the bimetal strip 110, and the fiber bragg grating 130 extends in a direction between a fixed end a and a free end B of the bimetal cantilever 120.
The thermal bimetal 110 in this embodiment may be of a conventional structure, and in the prior art, the thermal bimetal is a very important thermal sensitive element, and is a composite material mainly composed of two or more metal materials with different thermal expansion coefficients, where the metal material layer with a larger thermal expansion coefficient is used as an active layer, and the metal material layer with a lower thermal expansion coefficient is used as a passive layer.
The thermal bimetal 110 in this embodiment has a double-layer structure including an active layer 111 and a passive layer 112. The material of the active layer 111 can be nickel, brass, or an alloy of nickel, copper, manganese, chromium and iron; the passive layer 112 can be invar alloy containing 34% to 50% nickel.
In this embodiment, the thermal bimetal cantilever 120 is preferably formed by fixing one end of the thermal bimetal strip 110, wherein the fixed end of the thermal bimetal cantilever 120 is a fixed end a, and the opposite end is a free end B.
Compared with the conventional sensor structure that only uses the fiber bragg grating 130 for temperature measurement, in the present embodiment, by using the thermal deformation characteristic of the thermal bimetallic strip 110, an additional deformation amount can be introduced into the fiber bragg grating 130, so that the sensing sensitivity of the fiber bragg grating 130 can be better improved. In addition, by constructing the thermal bimetal cantilever beam 120 and extending the fiber bragg grating 130 in the direction between the fixed end a and the free end B of the thermal bimetal cantilever beam 120, the linearity of the fiber bragg grating 130 in the sensing process can be ensured in a teaching mode. Through the structure, the FBG temperature sensor in the embodiment has the advantages of better anti-interference performance, good long-term stability, high measurement precision and the like, and further can carry out high-precision and high-resolution temperature measurement in a severe environment with high temperature, high voltage and strong electromagnetic interference.
In addition, compare in the traditional sensitization mode to FBG temperature sensor, need not special packaging structure in this embodiment, it when specifically using, can be with the one end direct fixation of thermal bimetal piece 110 in the measuring face department or through the fixed knot structure department that will follow after, and then realize the building of thermal bimetal cantilever beam 120 to be convenient for production, manufacturing and use.
Fig. 1 is a schematic diagram of the FBG temperature sensor in the present embodiment when the thermal bimetal 110 is not deformed. Wherein the active layer 111 has a thickness h1length l, width c, coefficient of thermal expansion α1Young's modulus of E1(ii) a The passive layer 112 has a thickness h2length l, width c, coefficient of thermal expansion α2Young's modulus of E2。
When the temperature changes, the thermal bimetal 110 may generate bending deformation, i.e. convert thermal energy into mechanical energy, due to the different thermal expansion coefficients and the uneven thermal stress distribution of the active layer 111 and the passive layer 112. Since the thermal expansion coefficient of the active layer 111 is large, the thermal bimetal strip 110 will bend toward the passive layer 112; meanwhile, due to the structure of the thermal bimetal cantilever 120, the free end B will be displaced to the passive layer 112 side by a certain amount.
As shown in connection with FIG. 2, assume that the temperature of the state shown in FIG. 1 is T0The temperature of the state shown in fig. 2 is T, and the temperature change amount is Δ T ═ T-T0The free end displacement of the cantilever beam is d.
According to the coupled mode theory, the basic formula of the FBG sensing measurement is as follows:
in the above formula, λBIs the central reflection wavelength, Δ λ, of the fiber Bragg grating 130BIs λBamount of change of (a)Fis the thermal expansion coefficient of the optical fiber, ξ is the thermo-optic coefficient of the optical fiber, peΔ ε is the change in axial strain for the elasto-optic coefficient of the fiber.
When the temperature of the existing FBG temperature sensor is measured, no extra strain is introduced, namely the measurement formula is as follows:
therefore, the sensitivity coefficient of the conventional FBG temperature sensor is as follows: kT＝αF+ξ。
With reference to fig. 1 and 2, the center of the fiber bragg grating 130 in the present embodiment is set to be located at a position x away from the free end B of the thermal bimetal cantilever 120.
The knowledge of material mechanics shows that the relationship between the displacement d of the free end B and the temperature change amount delta T is as follows:
in the above formula, K is 4+6n +4n2+βn3+1/βn，n＝h1/h2，β＝E1/E2。
The relationship between the strain at the position where the fiber bragg grating 130 is disposed and the displacement d at the free end B is:
therefore, it can be obtained that the relationship between the strain at the position where the fiber bragg grating 130 is disposed and the temperature change Δ T is:
in the above formula, ∈xI.e. relative to T at a temperature T0The change in strain Δ ∈ in time.
Thus, the temperature sensing expression of the FBG temperature sensor in this embodiment is:
therefore, it can be known that the sensitivity coefficient of the FBG temperature sensor in this embodiment is:
according to KTAnd K'TAs can be seen from the expression in (1), in the present embodiment, an extra strain can be introduced to the fiber bragg grating 130 during temperature measurement through the thermal bimetal cantilever 120, so that the temperature sensitivity coefficient can be effectively improved, and the resolution and sensitivity of temperature measurement can be effectively improved.
In this embodiment, the thermal bimetal 110 is rectangular, one end of the thermal bimetal 110 along the length direction is configured as a fixed end a of the thermal bimetal cantilever 120, and the other end of the thermal bimetal 110 along the length direction is configured as a free end B of the thermal bimetal cantilever 120.
In this embodiment, by setting the thermal bimetal 110 to be rectangular, and making one end of the thermal bimetal 110 along the length direction be a fixed end a and the other end be a free end B, and simultaneously keeping the fiber bragg grating 130 along the length direction of the thermal bimetal 110, the linearity between the extra strain and the temperature change introduced by the thermal bimetal 110 can be better ensured, so as to better ensure the linearity of the FBG temperature sensor.
The FBG temperature sensor of the present embodiment can further include a fixing structure disposed at the fixing end of the thermal bimetal cantilever 120, and the fixing structure is fixedly connected to the corresponding end of the thermal bimetal strip 110. Thereby enabling better securing of the thermal bi-metallic cantilever 120.
The fixing structure in this embodiment includes a fixing plate 140, the thermal bimetal strip 110 is connected to the fixing plate 140 to form the thermal bimetal cantilever 120, and the fixing plate 140 can be connected to the workpiece to be tested.
In another preferred embodiment of the present invention, the fixing structure can further include a fixing surface, and the fixing surface can be a connecting surface at the position of the workpiece to be measured and can also be an inner side wall of a protection casing.
In this embodiment, the fiber bragg grating is disposed at the thermal bimetal. So that the transfer of strain can be preferably facilitated.
In this embodiment, the fiber bragg grating 130 is welded to the thermal bimetal 110. Thereby preferably facilitating the attachment and preferably facilitating the transfer of strain at the thermal bimetal 110 to the fiber bragg grating 130.
Based on the FBG temperature sensor in the present embodiment, the present embodiment also provides a specific application for detecting temperature.
In addition, when the FBG temperature sensor is actually applied, the temperature can be measured after the FBG temperature sensor is calibrated. Since it is difficult to precisely set the position of the fiber bragg grating 130 in the actual manufacturing process (i.e. x in this embodiment is difficult to precisely set), the FBG temperature sensor can be calibrated better by calibration.
Through the FBG temperature sensor in the embodiment, the sensitivity of the existing FBG temperature sensor can be better improved, and the realization is simple.
When the FBG temperature sensor in this embodiment is used specifically, the fiber bragg grating 130 can be accessed into the existing data acquisition or processing unit, and related parameters are set according to the calibration result and/or the temperature sensing expression thereof, so that the temperature can be better monitored.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.
Claims (8)
1. FBG temperature sensor based on bimetal cantilever beam, it includes the bimetal cantilever beam of heat that adopts the bimetal of heat to constitute, and the outside on bimetal initiative layer of heat is equipped with the optic fibre Bragg grating, and the optic fibre Bragg grating extends in the direction between bimetal cantilever beam stiff end of heat and free end.
2. The bi-metallic cantilever beam based FBG temperature sensor of claim 1, wherein: the shape of the thermal bimetallic strip is rectangular, one end of the thermal bimetallic strip along the length direction is constructed into a fixed end of the thermal bimetallic cantilever beam, and the other end of the thermal bimetallic strip along the length direction is constructed into a free end of the thermal bimetallic cantilever beam.
3. The bi-metallic cantilever beam based FBG temperature sensor of claim 1, wherein: the fixing structure is arranged at the fixed end of the thermal bimetallic cantilever beam and fixedly connected with the corresponding end of the thermal bimetallic strip.
4. The bi-metallic cantilever beam based FBG temperature sensor of claim 3, wherein: the fixing structure comprises a fixing plate or a fixing surface.
5. The bi-metallic cantilever beam based FBG temperature sensor of claim 1, wherein: the fiber Bragg grating is laid at the position of the thermal bimetallic strip.
6. The bi-metallic cantilever beam based FBG temperature sensor of claim 6, wherein: the optical fiber Bragg grating is connected with the thermal bimetallic strip in a welding mode.
7. The application of the FBG temperature sensor based on the double-metal cantilever beam comprises the step of measuring the temperature by adopting any one of the FBG temperature sensors based on the double-metal cantilever beam.
8. Use according to claim 7, characterized in that: and measuring the temperature after calibrating the FBG temperature sensor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911260950 | 2019-12-10 | ||
| CN2019112609507 | 2019-12-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111174933A true CN111174933A (en) | 2020-05-19 |
Family
ID=70656136
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010006596.1A Withdrawn CN111174933A (en) | 2019-12-10 | 2020-01-03 | FBG temperature sensor based on bimetal cantilever beam and application thereof |
| CN202010954557.4A Pending CN112304469A (en) | 2019-12-10 | 2020-09-11 | FBG temperature sensor based on bimetal cantilever beam and application thereof |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010954557.4A Pending CN112304469A (en) | 2019-12-10 | 2020-09-11 | FBG temperature sensor based on bimetal cantilever beam and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN111174933A (en) |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6175674B1 (en) * | 1999-03-08 | 2001-01-16 | Uconn Technology Inc. | Adjustable compensation device for fiber bragg gratings |
| JP3755601B2 (en) * | 2003-02-28 | 2006-03-15 | エヌ・ティ・ティ・アドバンステクノロジ株式会社 | FBG temperature sensor |
| CN100587458C (en) * | 2008-01-25 | 2010-02-03 | 北京工业大学 | Stress test grid of nano material used for transmission electron microscopy |
| CN101566643B (en) * | 2008-04-22 | 2012-05-09 | 中国计量学院 | Structure of film thermoelectric converter based on bi-material microcantilevel and fabricating method thereof |
| US8195013B2 (en) * | 2009-08-19 | 2012-06-05 | The United States Of America, As Represented By The Secretary Of The Navy | Miniature fiber optic temperature sensors |
| CN102081871A (en) * | 2009-11-30 | 2011-06-01 | 尚新春 | Teaching experimental device for heated bending of bimetallic-strip cantilever beam |
| CN102564623A (en) * | 2011-12-29 | 2012-07-11 | 东南大学 | Temperature sensor structure vertical to structure field emission micro machine |
| CN103115694B (en) * | 2013-01-17 | 2015-02-04 | 中国地震局地壳应力研究所 | Fiber Bragg grating (FBG) high-sensitivity temperature sensor based on low-melting-point glass welding |
| CN103424208B (en) * | 2013-09-02 | 2015-06-17 | 东南大学 | High-sensitivity capacitance type micro-machinery temperature sensor |
| JP6397369B2 (en) * | 2015-05-19 | 2018-09-26 | 株式会社東京測器研究所 | Displacement measuring system and displacement measuring method |
| CN106441659B (en) * | 2016-10-21 | 2022-05-17 | 中国计量大学 | Fiber grating pressure sensor based on cantilever beam |
| CN206208380U (en) * | 2016-11-18 | 2017-05-31 | 中国计量大学 | A kind of optical fiber raster vibration sensor based on cantilever beam structure |
| CN108760109B (en) * | 2018-03-22 | 2020-11-24 | 湖北省路桥集团有限公司 | Variable-range soil pressure measuring device and method based on Bragg fiber grating |
| CN110530548B (en) * | 2019-08-02 | 2020-08-18 | 西安交通大学 | Fiber grating detection method and device for measuring pressure and temperature parameters |
-
2020
- 2020-01-03 CN CN202010006596.1A patent/CN111174933A/en not_active Withdrawn
- 2020-09-11 CN CN202010954557.4A patent/CN112304469A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN112304469A (en) | 2021-02-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Kuang et al. | Packaging and temperature compensation of fiber Bragg grating for strain sensing: a survey | |
| CN107505477B (en) | Three-dimensional fiber Bragg grating wind speed and direction sensor and system | |
| CN101216351B (en) | Bimetal sheet type optical fiber microbending temperature sensor | |
| CN107202545B (en) | Temperature self-compensating fiber grating strain sensor | |
| CN107367240B (en) | Square structure fiber grating reverse differential strain detection sensing device | |
| CN112729597B (en) | Metallized packaged optical fiber grating method-amber sensor | |
| Zhao et al. | Simultaneous measurement of temperature and pressure based on ring-shaped sensing structure with polymer coated no-core fiber | |
| CN201034747Y (en) | Long period optical fiber grating counter modulation optical fiber grating high-temperature sensing system | |
| CN111174933A (en) | FBG temperature sensor based on bimetal cantilever beam and application thereof | |
| CN207850399U (en) | A kind of fiber grating humiture integrative sensor | |
| CN103134609A (en) | High-sensitivity fiber bragg grating temperature sensor with adjustable sensitivity coefficient | |
| CN205748774U (en) | High-temperature resistant optical fiber grating pressure sensor | |
| CN215984960U (en) | A fiber grating sensor sensitization device for measuring small meeting an emergency | |
| CN210862557U (en) | Optical fiber grating sensor device | |
| JP2019109057A (en) | Optical fiber sensor | |
| CN101294855B (en) | Novel design method and production technique for optical fiber and optical grating temperature sensitizing sensor | |
| CN105841878A (en) | High temperature resistance fiber bragg grating pressure sensor | |
| CN219572964U (en) | Fiber bragg grating strain sensor | |
| CN112629697B (en) | Quasi-reciprocal reflection type optical fiber temperature sensor | |
| CN114088240B (en) | Cold-hot extension type fiber bragg grating temperature sensor | |
| CN214308811U (en) | Double-parameter fiber grating sensor | |
| Wang et al. | Development of Fiber Grating Crack Gauge Based on New Temperature Compensation Structure | |
| CN106338349B (en) | Double microballoon temperature sensors based on silica optical fiber | |
| CN112567219A (en) | Temperature measuring device using fiber grating sensor | |
| Yang et al. | Cryogenic temperature sensor based on an optical fiber Fabry-Perot interferometer with high sensitivity |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20200519 |