阅读说明：本技术 一种基于可调谐聚合物微瓶的乙醇气体传感器 (Ethanol gas sensor based on tunable polymer micro-bottle ) 是由 张亚男 朱耐思 史卜凡 孙洋 郑万禄 于 2019-10-22 设计创作，主要内容包括：本发明公开了一种基于可调谐聚合物微瓶的乙醇气体传感器,其包括宽谱光源、传感单元、光谱仪、气室、真空泵和注射器；其中宽谱光源经第一单模光纤与传感单元连接,传感单元经第二单模光纤与光谱仪连接,所述的传感单元设置于气室内,传感单元包括设置有可调谐聚合物微瓶的第三单模光纤和微纳光纤,第三单模光纤与微纳光纤相互垂直设置,微纳光纤两端分别与第一单模光纤和第二单模光纤熔接；所述的注射器通过管路与气室连接,用于控制气室中乙醇气体浓度。本发明提供的基于可调谐聚合物微瓶的乙醇气体传感器制备工艺简单、成本低、结构稳定、可调谐的聚合物微瓶,实现乙醇气体浓度测量。(The invention discloses an ethanol gas sensor based on a tunable polymer micro-bottle, which comprises a wide-spectrum light source, a sensing unit, a spectrometer, a gas chamber, a vacuum pump and an injector, wherein the wide-spectrum light source is connected with the sensing unit; the wide-spectrum light source is connected with a sensing unit through a first single mode fiber, the sensing unit is connected with a spectrometer through a second single mode fiber, the sensing unit is arranged in the air chamber and comprises a third single mode fiber and a micro-nano fiber, the third single mode fiber and the micro-nano fiber are provided with a tunable polymer micro bottle, the third single mode fiber and the micro-nano fiber are perpendicular to each other, and two ends of the micro-nano fiber are respectively welded with the first single mode fiber and the second single mode fiber; the injector is connected with the gas chamber through a pipeline and is used for controlling the concentration of the ethanol gas in the gas chamber. The ethanol gas sensor based on the tunable polymer micro-bottle provided by the invention is simple in preparation process, low in cost, stable in structure and capable of tuning the polymer micro-bottle, and the concentration of ethanol gas is measured.)

1. The ethanol gas sensor based on the tunable polymer micro-bottle is characterized by comprising a wide-spectrum light source (1), a sensing unit (2), a spectrometer (3), a gas chamber (4), a vacuum pump (5) and an injector (8); wherein:

the wide-spectrum light source (1) is connected with the sensing unit (2) through a first single-mode fiber (6), the sensing unit (2) is connected with the spectrometer (3) through a second single-mode fiber (7), and the sensing unit (2) is arranged in the air chamber (4);

the sensing unit (2) comprises a third single-mode fiber (23) and a micro-nano fiber (22), wherein the third single-mode fiber (23) is provided with a tunable polymer micro bottle (21), the third single-mode fiber (23) and the micro-nano fiber (22) are perpendicular to each other, and two ends of the micro-nano fiber (22) are respectively welded with the first single-mode fiber (6) and the second single-mode fiber (7);

the injector (8) is connected with the gas chamber (4) through a pipeline and is used for controlling the concentration of the ethanol gas in the gas chamber (4);

after light emitted by the wide-spectrum light source (1) is transmitted to the micro-nano optical fiber (22) through the first single mode fiber (6), due to the evanescent field effect, the light is coupled into the tunable polymer micro bottle (21) and generates a resonance effect, light meeting the resonance wavelength is localized in the tunable polymer micro bottle (21), and the rest light enters the second single mode fiber (7) through the micro-nano optical fiber (22) and is transmitted to the spectrometer (3) to display an output spectrum; when the concentration of the ethanol gas is changed, the effective refractive index and the volume of the tunable polymer micro bottle (21) are changed, so that the resonance wavelength of the tunable polymer micro bottle (21) is shifted, and the change of the concentration of the ethanol gas can be obtained by monitoring the change of the resonance wavelength in an output spectrum.

2. The tunable polymer micro-bottle based ethanol gas sensor according to claim 1, wherein the tunable polymer micro-bottle (21) is made by mixing two reagents of polydimethylsiloxane and tetraethoxysilane; the mass ratio of the polydimethylsiloxane to the tetraethoxysilane is 10: 1.

3. The tunable polymer micro-bottle based ethanol gas sensor according to claim 1 or 2, wherein the center radius of the tunable polymer micro-bottle (21) is 98 μm to 213 μm.

4. The tunable polymer micro-bottle based ethanol gas sensor according to claim 3, wherein the tunable polymer micro-bottle (21) is prepared by the following method: uniformly mixing two reagents, namely polydimethylsiloxane and tetraethoxysilane, according to the mass ratio of 10:1, enabling the reagents to generate a micro-bottle shape on a third single-mode optical fiber (23) through the gravity and the adhesive force of the mixed reagent of the polydimethylsiloxane and the tetraethoxysilane, standing for 0-3 minutes at the room temperature of 25 ℃, then placing the reagents into a constant temperature box at the temperature of 60 ℃ for curing, and controlling the standing time at the room temperature to obtain the tunable polymer micro-bottle (21) with different central radiuses.

5. The ethanol gas sensor based on the tunable polymer micro-bottle as claimed in claim 1, 2 or 4, wherein the micro-nano optical fiber (22) is prepared by the following method: performing non-adiabatic tapering treatment on the fourth single-mode fiber (24) by using a fusion splicer to enable the micro-nano fiber (22) to be composed of two abrupt taper transition sections with the diameter of 44-46 mu m, the waist taper length of 1.5-2mm and the total length of 0.9-1.1 mm; then, further drawing the micro-nano optical fiber (22) by a tapering machine, wherein the heating area is 7.5-8mm wide; finally drawing the micro-nano optical fiber (22) with the diameter of 2-3 mu m, the waist cone length of 8-9mm and the total length of 12-13 mm.

6. The tunable polymer micro-bottle based ethanol gas sensor according to claim 1, 2 or 4, wherein the resonance condition is:

2πRn_eff＝lλ_res(1)

wherein R is the radius of the tunable polymer micro-bottle (21), n_effIs tunable to the effective refractive index of the polymer micro-bottle (21), l is the number of azimuthal modes, lambda_resIs the resonant wavelength;

changes in the radius or effective refractive index of the tunable polymer micro-bottle (21) will change the resonant wavelength, which can be expressed as:

wherein Δ λ represents a change in resonance wavelength, Δ R represents a change in radius of the tunable polymer micro-bottle (21), and Δ n_effRepresents the change of the effective refractive index of the tunable polymer micro-bottle (21).

7. The tunable polymer micro-bottle based ethanol gas sensor according to claim 5, wherein the resonance condition is:

2πRn_eff＝lλ_res(1)

wherein R is the radius of the tunable polymer micro-bottle (21), n_effIs tunable to the effective refractive index of the polymer micro-bottle (21), l is the number of azimuthal modes, lambda_resIs the resonant wavelength;

changes in the radius or effective refractive index of the tunable polymer micro-bottle (21) will change the resonant wavelength, which can be expressed as:

wherein Δ λ represents a change in resonance wavelength, Δ R represents a change in radius of the tunable polymer micro-bottle (21), and Δ n_effRepresents the change of the effective refractive index of the tunable polymer micro-bottle (21).

Technical Field

The invention belongs to the technical field of sensing, and relates to an ethanol gas sensor based on a tunable polymer micro-bottle.

Background

With the increasing socioeconomic level, there is a demand for air quality in daily life, especially in indoor environments where most people are exposed, and Volatile Organic Compounds (VOCs) are major pollutants in indoor environments, and generally, VOC gas is generated from building materials, furniture, inks, etc. which are frequently used and exposed in daily life, and it is estimated that 50 to 300 kinds of VOC gas can be detected in indoor spaces such as libraries, homes, offices, restaurants [ Mirzaei a, Leonardi S G, new g.detection of halogenated Volatile Organic Compounds (VOCs) by metallic oxygen and sulfur sensors [ J ] Ceramics International,2016: S02728842169889 ]. VOC gases are hydrocarbon chemicals that typically have low boiling points and therefore high volatility. Most VOC gas is toxic, has foul smell and can cause cancer, and when the VOC in a room reaches a certain concentration, the gas enters the human body through a respiratory system and can cause symptoms such as headache, vomit, convulsion, hypodynamia and the like; in addition, most of the VOC gases are flammable and explosive, such as ethanol gas, which is prone to fire and explosion at high concentrations. The optical fiber sensing technology is a novel technology which takes light as a carrier and optical fiber as a medium and is used for sensing and transmitting the change of an external environment. When light waves are transmitted in the optical fibers, the characteristic parameters of the light waves are correspondingly changed along with the change of the external environment, and the corresponding relation can be obtained by observing the change of a certain characteristic parameter of the light waves and the external variable, so that the measurement of the parameters to be measured [ Zhao Yong. Qinghua university Press, 2007, 36-37 ].

To date, many sensing technologies for monitoring VOC gas concentrations have been proposed, such as semiconductor metal oxide Sensors [ Wetchakun K, Samerjai T, Tamaekong N, et al.Semiconduction metals Sensors for environmental halodous gases [ J ]. Sensors and Actuators B: Chemical,2011,160(1):580- & ltd 591 ], SAW [ Hujia, Du-kong, Jiandong ], SAW sensor arrays for detecting VOC vapors [ J ]. instrumentation and Sensors, 2013(02):10-12 ], fiber optic Sensors [ Cesar E, Ignacio R M, Candido B, et al.Volatile organic composite Sensors: Areview [ J ]. 6: 1465 ]. Compared with other VOC gas detection methods, the optical fiber sensor is concerned by small volume, light weight, good electrical insulation performance, strong anti-electromagnetic interference capability, safety and no influence of electric sparks, and supports real-time, online work, remote monitoring and computer connection. The existing optical fiber VOC gas sensor usually coats a VOC gas sensitive film on the surface of an optical fiber, and changes of optical signals are caused by the change of the volume or the refractive index of the sensitive film when the concentration of the VOC gas changes, so that the measurement of the gas concentration is realized. However, the sensitive film is bound to the optical fiber, and the optical fiber needs to be processed, so that the operation is complicated and the uniformity cannot be ensured. In addition, the sensitive film is easily peeled off during the measurement. These not only affect the stability of the measurement, but also introduce errors into the measurement of the gas concentration, even rendering the sensor inoperable.

Disclosure of Invention

The invention aims to overcome the defects of the existing VOC gas sensor based on optical fibers, and provides a tunable polymer micro-bottle with simple preparation process, low cost, stable structure and capability of realizing the measurement of the concentration of ethanol gas.

In order to achieve the purpose, the invention provides an ethanol gas sensor based on a tunable polymer micro-bottle, which comprises a wide-spectrum light source 1, a sensing unit 2, a spectrometer 3, a gas chamber 4, a vacuum pump 5 and an injector 8; the wide-spectrum light source 1 is connected with the sensing unit 2 through a first single-mode fiber 6, the sensing unit 2 is connected with the spectrometer 3 through a second single-mode fiber 7, the sensing unit 2 is arranged in the air chamber 4, the sensing unit 2 comprises a third single-mode fiber 23 and a micro-nano fiber 22, the third single-mode fiber 23 is provided with a tunable polymer micro bottle 21, the micro-nano fiber 22 is perpendicular to the third single-mode fiber 23, and two ends of the micro-nano fiber 22 are respectively welded with the first single-mode fiber 6 and the second single-mode fiber 7; the injector 8 is connected with the gas chamber 4 through a pipeline and is used for controlling the concentration of the ethanol gas in the gas chamber 4.

After light emitted by the wide-spectrum light source 1 is transmitted to the micro-nano optical fiber 22 through the first single mode fiber 6, due to the action of an evanescent field, the light is coupled into the tunable polymer micro bottle 21 and generates a resonance effect, light meeting the resonance wavelength is localized in the tunable polymer micro bottle 21, and the rest light enters the second single mode fiber 7 through the micro-nano optical fiber 22 and is transmitted to the spectrometer 3 to display an output spectrum; when the concentration of the ethanol gas changes, the effective refractive index and the volume of the tunable polymer micro bottle 21 are changed, so that the resonance wavelength of the tunable polymer micro bottle 21 is shifted, and the change of the concentration of the ethanol gas can be obtained by monitoring the change of the resonance wavelength in the output spectrum.

Further, the tunable polymer micro-bottle 21 is prepared by mixing two reagents of polydimethylsiloxane and tetraethoxysilane.

Further, the mass ratio of the polydimethylsiloxane to the tetraethoxysilane is 10: 1.

Further, the center radius of the tunable polymer micro bottle 21 is 98 μm to 213 μm.

Further, the tunable polymer micro-bottle 21 is prepared by the following method: uniformly mixing two reagents, namely polydimethylsiloxane and tetraethoxysilane, according to the mass ratio of 10:1, enabling the reagents to generate a micro-bottle shape on a third single-mode optical fiber 23 through the gravity and the adhesive force of the mixed reagent of the polydimethylsiloxane and the tetraethoxysilane, standing for 0-3 minutes at the room temperature of 25 ℃, then placing the reagents into a constant temperature box at the temperature of 60 ℃ for curing, and controlling the standing time at the room temperature to obtain the tunable polymer micro-bottle 21 with different central radiuses.

Further, the micro-nano optical fiber 22 is prepared by the following method: performing non-adiabatic tapering treatment on the fourth single-mode fiber 24 by using a fusion splicer, so that the micro-nano fiber 22 consists of two abrupt taper transition sections with the diameter of 44-46 mu m, the uniform waist length of 1.5-2mm and the total length of 0.9-1.1 mm; then, further drawing the micro-nano optical fiber 22 by a tapering machine, wherein the heating area is 7.5-8mm wide; finally, drawing the micro-nano optical fiber 22 with the diameter of 2-3 μm, the uniform waist area length of 8-9mm and the total length of 12-13 mm.

Further, the resonance condition is as follows:

2πRn_eff＝lλ_res(1)

where R is the center radius of the tunable polymer microbore 21, n_effIs effective for tuning polymer micro-bottle 21Refractive index, l is the number of azimuthal modes, λ_resIs the resonant wavelength;

a change in the center radius or effective index of refraction of the tunable polymer micro-bottle 21 will change the resonant wavelength, expressed as:

wherein Δ λ represents a change in resonance wavelength, Δ R represents a change in the center radius of the tunable polymer micro-bottle 21, and Δ n_effRepresenting the change in effective refractive index of the tunable polymer micro-bottle 21.

According to the technical scheme, the invention has the following beneficial effects:

1) the transmission-type optical fiber sensor for measuring the concentration of the ethanol gas, provided by the invention, inherits the advantages of intrinsic safety, electromagnetic interference resistance, high temperature and pressure resistance, corrosion resistance and the like of the traditional optical fiber sensor;

2) the transmission-type optical fiber sensor for measuring the concentration of the ethanol gas, provided by the invention, combines the microcavity manufacturing process and the film coating process into a whole, can form the tunable polymer micro-bottle and has gas sensitivity, the manufacturing process is simple, the cost is low, the structure of the tunable polymer micro-bottle is stable, and the phenomenon that the gas concentration sensitivity is reduced due to the falling of a gas sensitive film in the later measuring stage is avoided.

Drawings

Fig. 1 is a schematic structural diagram of an optical fiber sensor system provided by the present invention.

Fig. 2 is a pictorial view of a continuous tunable polymer micro-bottle.

FIG. 3 is a plot of center radius versus resting time for tunable polymer microbottes.

FIG. 4 is a sensor ethanol gas concentration measurement spectral curve.

FIG. 5 is a sensor ethanol gas concentration measurement sensitivity curve.

In the figure: 1 wide-spectrum light source; 2, a sensing unit; 21 tunable polymer micro-bottles; 22 micro-nano optical fibers; 23 a third single mode optical fiber; 24 a fourth single mode optical fiber; 3, a spectrometer; 4, an air chamber; 5, a vacuum pump; 6 a first single mode optical fiber; 7 a second single mode optical fiber; 8 injector.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following detailed description of the specific structure, principle and operation of the present invention with reference to the accompanying drawings is provided.

Fig. 1 shows a transmission type optical fiber sensor for measuring ethanol gas concentration according to the present invention. The working process is as follows: light emitted by the wide-spectrum light source 1 is transmitted to the micro-nano optical fiber 22 through the first single mode fiber 6, due to an evanescent field generated by the micro-nano optical fiber 22, the light is coupled into the tunable polymer micro bottle 21 and generates a resonance effect, light meeting the resonance wavelength is localized in the tunable polymer micro bottle 21, and the rest light enters the second single mode fiber 7 through the micro-nano optical fiber 22 and is transmitted to the spectrometer 3 to display an output spectrum. The concentration of ethanol gas in the gas cell 4 is controlled by the injector 8 and the amount of spectral shift is monitored in the spectrometer 4.

The preparation method comprises the following steps of uniformly mixing two reagents, namely polydimethylsiloxane and tetraethoxysilane, according to a mass ratio of 10:1, repeatedly lifting and dipping a third single-mode optical fiber 23 in the mixed reagent of the polydimethylsiloxane and the tetraethoxysilane by using a lifting coating machine for the tunable polymer micro-bottle 21, and simultaneously realizing the manufacturing and coating of the tunable polymer micro-bottle 21 through the gravity and the adhesive force of the mixed reagent of the polydimethylsiloxane and the tetraethoxysilane; wherein the single dipping speed of the dip coater is set to 100mm/min, and the third single-mode optical fiber 23 with the length of about 25mm is dipped; setting the single pulling speed to be 150mm/min, and completely pulling out the third single-mode optical fiber 23 from the polydimethylsiloxane; after a single dip and a single pull, a plurality of tunable polymer micro-vials 21 of relatively uniform size and shape can be made, as shown in fig. 2. And curing the mixture in a constant temperature oven at 60 ℃ for 5 hours, and standing the mixture at room temperature for 24 hours to obtain the tunable polymer micro bottle 21 with a smooth and uniform surface. As shown in fig. 3, if the prepared tunable polymer micro bottle 21 is first left to stand at 25 ℃ for different times and then is cured in a thermostat, tunable polymer micro bottles 21 with different center radii can be obtained. The tunable polymer micro bottle 21 is prepared by mixing two reagents, namely polydimethylsiloxane and tetraethoxysilane, wherein the mass ratio of the polydimethylsiloxane to the tetraethoxysilane is 10: 1.

When the micro-nano optical fiber 22 generates an evanescent field, the light is coupled into the polymer micro bottle 21 and generates a resonance effect, the light meeting the resonance wavelength is localized in the tunable polymer micro bottle 21, the rest light enters the second single-mode optical fiber 7 through the micro-nano optical fiber 22 to form an output spectrum, a resonance trough is generated at a specific wavelength, and the resonance condition is as follows:

2πRn_eff＝lλ_res(1)

where R is the radius of the tunable polymer microbore 21, n_effIs tuned to the effective refractive index of the polymer micro-bottle 21, l is the number of azimuthal modes, λ_resIs the resonant wavelength. As can be seen from equation (1), a change in the radius or effective refractive index of the tunable polymer micro-bottle 21 will change the resonant wavelength, which can be expressed as:

wherein Δ λ represents the change of the resonance wavelength, Δ R represents the change of the radius of the tunable polymer micro-bottle 21, Δ n_effRepresenting the change in effective refractive index of the tunable polymer micro-bottle 21.

When the external refractive index moves, the resonance wavelength of the resonance valley moves, and when the sensing unit 2 detects the ethanol gas, the ethanol gas is adsorbed to the tunable polymer micro bottle 21, so that the radius and the effective refractive index of the tunable polymer micro bottle 21 are changed simultaneously, the resonance wavelength of the resonance trough moves, and the measurement of the concentration of the ethanol gas is realized.

In the present invention, when the concentration of ethanol gas is changed, as shown in fig. 4, the radius and effective refractive index of the tunable polymer micro-bottle 21 are changed to shift the resonance wavelength of the resonance trough, and the ethanol gas concentration measurement sensitivity of the sensor is shown in fig. 5.

From the equation (2), the concentration of the ethanol gas can be reversely deduced by observing the amount of movement of the concentration of the ethanol gas corresponding to the resonance valley resonance wavelength. Therefore, the transmission-type optical fiber sensor for measuring the concentration of the ethanol gas, provided by the invention, not only can realize the monitoring of the concentration of the ethanol gas, but also integrates the manufacturing process and the coating process of the microcavity into a whole, thereby avoiding the phenomenon that the sensitivity of the gas concentration is reduced because the gas sensitive film falls off at the later stage of measurement.