CN101750403A - Fluorescent optical fiber sensor for detecting nitrogen dioxide - Google Patents

Abstract

The invention relates to a fluorescent optical fiber sensor for detecting nitrogen dioxide, comprising an excitation light source, a branch optical fiber, and a _NO2 nanometer fluorescent film, the optical path of the excitation light source is coupled with the incident end of the branch optical fiber, the receiving end of the branch optical fiber is connected to the The device is coupled, and the outer side of the total end face of the branch optical fiber is provided with NO ₂ nanometer fluorescent film. The nitrogen dioxide sensor of the invention has the advantages of low cost, high performance, quick response, good stability and easy miniaturization, and can be used for real-time on-line detection of low-concentration nitrogen dioxide gas.

Description

A fluorescent optical fiber sensor for detecting nitrogen dioxide

technical field

The invention relates to a fluorescent optical fiber sensor for detecting nitrogen dioxide, in particular to an optical sensor for on-site and on-line measurement of low-concentration nitrogen dioxide gas in air, which belongs to the sensor field technology.

Background technique

Nitrogen dioxide (NO ₂ ) mainly comes from the waste gas produced by coal combustion and automobile exhaust. It is a highly toxic air pollutant and the main component of environmental problems such as acid rain and photochemical smog, which is harmful to human health. The methods for detecting nitrogen dioxide mainly include chemiluminescence and electrochemical methods. The former is easily affected by coexisting gases, while the latter requires precise control of experimental conditions such as electrode potential and temperature. The detection instruments based on these two methods are mostly large-scale instruments, which are expensive and are not convenient for on-site monitoring of nitrogen dioxide.

Contents of the invention

The purpose of the present invention is to provide a fluorescent optical fiber sensor for detecting low-concentration nitrogen dioxide, which has low cost, high performance, rapid response, good stability, and easy miniaturization; nitrogen dioxide has the ability to quench the fluorescence emitted by specific fluorescent reagents. It can detect the low concentration nitrogen dioxide.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A fluorescent optical fiber sensor for detecting nitrogen dioxide, comprising an excitation light source, a branch optical fiber, and a _NO2 nanometer fluorescent film, the optical path of the excitation light source is coupled to the incident end of the branch optical fiber, and the receiving end of the branch optical fiber is coupled to a photoelectric conversion device , the outside of the total end face of the branch optical fiber is provided with NO ₂ nanometer fluorescent film.

The NO ₂ nanometer fluorescent film is coated on the upper surface of the transparent carrier sheet, and a filter is arranged between the receiving end of the branch optical fiber and the photoelectric conversion device.

The general end of the branch optical fiber is fixedly coupled to the lower surface of the transparent carrier sheet through an optical coupler, corresponding to the _NO2 nanometer fluorescent film coated on the upper surface of the transparent carrier sheet.

The incident end of the branch fiber is fixedly coupled with the excitation light source through an optical coupler, and the receiving end of the branch fiber is fixedly coupled with the photoelectric conversion device through an optical coupler; the total end of the branch fiber is fixed on the top of a detection cell through an optical coupler, And the total end of the branch optical fiber extends into the detection pool, the _NO2 nanometer fluorescent film coated on the transparent carrier sheet is placed in the detection pool, and is located directly below the end face of the branch optical fiber general end, and a reflector is arranged on the lower surface of the transparent carrier sheet , to enhance the fluorescence intensity radiated to the end face of the receiving fiber at the general end of the branch optical fiber; the detection cell is provided with a sample gas inlet and a sample outlet; the optical coupler at the top of the detection cell and the detection cell are gas-sealed through an "O" ring.

The excitation light source is a high-power light-emitting diode or a pulse lamp capable of emitting a suitable wavelength; the incident end of the branch optical fiber transmits the excitation light to the fluorescent sensitive film; the receiving end of the quartz branch optical fiber transmits the fluorescence to the photoelectric A conversion device; the NO ₂ nanometer fluorescent film (201) refers to a fluorescent sensing film embedded with a fluorescent probe perylene or Ti(Pc) ₂ .

The detection cell can be made of metallic or non-metallic materials, such as polyetheretherketone (PEEK) or Teflon (Teflon) or polyvinyl chloride (PVC) and other opaque materials.

The present invention has the following advantages:

The fluorescent optical fiber sensor for detecting nitrogen dioxide is composed of an optical system and a fluorescent nano film of nitrogen dioxide. This sensor has the following advantages:

1. The sensing system can be combined with different nitrogen dioxide fluorescent nano-films, which greatly simplifies the operation and instrument structure, and is conducive to expanding the application range of the instrument.

2. Using cheap light-emitting diodes as light sources can greatly reduce the production cost of the instrument.

3. Compared with the traditional chemiluminescence method and electrochemical method, the fluorescence method has the advantages of high sensitivity and good selectivity. Selecting a fluorescent reagent that has a specific response to nitrogen dioxide can eliminate the interference of other gases, such as SO ₂ , CO, Cl ₂ and NH ₃ .

In a word, the sensor has the advantages of low cost, high performance, rapid response, good stability, easy miniaturization of the sensor, and can be used for real-time on-line detection of low-concentration nitrogen dioxide gas.

Description of drawings

Fig. 1 is a kind of schematic diagram of the fluorescent optical fiber sensor that detects the nitrogen dioxide that has detection cell;

Fig. 2 is a schematic diagram of a fluorescent optical fiber sensor of a probe type nitrogen dioxide without a detection pool;

Among the figure: 101 is an excitation light source (such as: high-power light-emitting diode or pulsed light source), 102 is a branch optical fiber, 103 is a photoelectric conversion device (such as: photomultiplier tube or silicon photocell or CCD spectrometer) that receives fluorescence, and 104 is a filter Optical sheet, 105 is an optical coupler, 201 is a nitrogen dioxide nano fluorescent film, 202 is a transparent carrier sheet, 203 is a reflective mirror, 301 is a detection cell body, 302 is a detection chamber, 303 is a sample inlet, 304 is a sample outlet, 305 is a sealing "O" ring;

Fig. 3 is a fluorescence spectral response diagram of a fluorescent optical fiber sensor for nitrogen dioxide to different concentrations of nitrogen dioxide.

Detailed ways

Example 1

As shown in Figure 1, a kind of fluorescent optical fiber sensor that detects nitrogen dioxide, it is the probe structure that has detection cell, comprises excitation light source 101 (high-power light-emitting diode), branch optical fiber 102, NO ₂ Nano fluorescent film 201, so The optical path of the excitation light source 101 is coupled with the incident end of the branch fiber 102, the receiving end of the branch fiber 102 is coupled with the photoelectric conversion device 103 (CCD spectrometer), and the outside of the total end face of the branch fiber 102 is provided with NO _Nano fluorescent film 201 . The NO ₂ nanometer fluorescent film 201 is coated on the upper surface of the transparent carrier sheet 202 , and a filter 104 is arranged between the receiving end of the branch optical fiber 102 and the photoelectric conversion device 103 .

The incident end of the branch fiber 102 is fixedly coupled with the excitation light source 101 through the optical coupler 105, and the receiving end of the branch fiber 102 is fixedly coupled with the photoelectric conversion device 103 through the optical coupler 105; Be fixed on the top of a detection pool 301, and the general end of branch optical fiber 102 stretches into detection pool 301, be coated on the NO on the transparent carrier sheet 202 _Nano fluorescent film 201 is placed in detection pool 301, and is positioned at branch optical fiber 102 total end Just below the end face, a reflector 203 is provided on the lower surface of the transparent carrier sheet 202 to enhance the fluorescence intensity radiated to the end face of the receiving fiber at the general end of the branch optical fiber 102 .

The detection cell 301 is provided with a sample gas inlet 303 and a sample outlet 304, and the cavity inside the detection cell 301 is a detection cavity 302; an "O" ring 305 is passed between the optical coupler 105 at the top of the detection cell 301 and the detection cell 301 Make a gas seal.

The detection cell body and the optical fiber coupler of the present invention can be processed from non-metallic materials such as metal materials or polymers. Metal materials can be stainless steel, titanium aluminum alloy, etc.; non-metal materials such as ceramics; polymer materials such as polyetheretherketone (PEEK), Teflon (Teflon) or polyvinyl chloride (PVC).

The excitation light source 101 is a high-power light-emitting diode or a pulsed lamp capable of emitting a suitable wavelength; the CCD spectrometer is used to receive and process fluorescent signals; Obtained by embedded technology immobilized in a certain sol-gel matrix or transparent material of organic polymer;

The detection process of nitrogen dioxide is as follows:

1) Detection cell The cell body 301 is coupled to the light emitting diode 101 through the branch optical fiber 102 , and is coupled to the signal receiving and processing system 103 through the branch optical fiber 102 .

2) An optical filter 104 is arranged between the branch optical fiber 102 and the signal receiving and processing system 103 .

3) The sensor adopts a high-power light-emitting diode as the excitation light source 101, the excitation light source 101 is coupled with the branch optical fiber 102 through the fiber coupler 105, and the excitation light is irradiated on the nitrogen dioxide fluorescent sensitive film 201 through the incident end of the branch optical fiber 102, and the generated fluorescence Collected by the receiving end of the branch optical fiber 102 and transmitted through the filter 104 to the CCD spectrometer 103 for detection.

4) The fluorescent sensitive film 201 is usually coated on the upper surface of the carrier glass sheet 202, the lower surface of the carrier glass sheet 202 is fixed on the upper surface of the reflector 203, and the reflector 203 is fixed at the center of the bottom of the flow cell 301, opposite to the general end of the branch optical fiber 102 .

5) Selection of nitrogen dioxide fluorescent sensitive film: choose a nitrogen dioxide fluorescent sensitive film embedded with fluorescent probes, such as perylene [Sens.Actuators B Chem.2001, 72:51.] or Ti(Pc) ₂ (Sens.Actuators B Chem.2001, 74:12.] and other fluorescent probe molecules are used as fluorescent sensing membranes.

Application example

The nitrogen dioxide fluorescence-sensitive film embedded with the fluorescent probe perylene is installed in the flow cell described in Example 1, and a purple high-power light-emitting diode with a center wavelength of 390 nm is used as the light source, and one end of the branch optical fiber is sensitive to nitrogen dioxide fluorescence. The membrane is excited, and the emitted fluorescence is transmitted through the other end of the emission branch fiber, and then enters the CCD spectrometer (USB4000) through the long-pass filter (LP400) for detection. When nitrogen dioxide exists, the excited state perylene molecules react with nitrogen dioxide molecules to produce fluorescence quenching. The result is shown in Figure 3. Nitric oxide in response to the effect of perylene on fluorescence emission. When used as a sensor, only the fluorescence with a wavelength of 470nm is taken.

Example 2

As shown in Figure 2, a kind of fluorescence optical fiber sensor that detects nitrogen dioxide, it is open no pool probe structure, comprises excitation light source 101, branch optical fiber 102, NO ₂ nanometer fluorescent film 201, the optical path of described excitation light source 101 and The incident end of the branch optical fiber 102 is coupled, the receiving end of the branch optical fiber 102 is coupled with the photoelectric conversion device 103 , and an NO ₂ nanometer fluorescent film 201 is arranged outside the general end face of the branch optical fiber 102 . The NO ₂ nanometer fluorescent film 201 is coated on the upper surface of the transparent carrier sheet 202 , and a filter 104 is arranged between the receiving end of the branch optical fiber 102 and the photoelectric conversion device 103 .

The general end of the branch optical fiber 102 is fixedly coupled to the lower surface of the transparent carrier sheet 202 through an optical coupler 105 , corresponding to the NO ₂ nanometer fluorescent film 201 coated on the upper surface of the transparent carrier sheet 202 .

Claims (7)

1. A fluorescent optical fiber sensor for detecting nitrogen dioxide, comprising excitation light source (101), branch optical fiber (102), NO _Nano fluorescent film (201), is characterized in that: the light path and branch of described excitation light source (101) The incident end of the optical fiber (102) is coupled, the receiving end of the branch optical fiber (102) is coupled with the photoelectric conversion device (103), and the outside of the total end face of the branch optical fiber (102) is provided with NO _Nano fluorescent film (201). 2. according to the described sensor of claim 1, it is characterized in that: described NO _Nano fluorescent film (201) is coated on transparent carrier sheet (202) upper surface, the receiving end of branch optical fiber (102) and photoelectric conversion device ( 103) is provided with a filter (104). 3. The sensor according to claim 2, characterized in that: the general end of the branch optical fiber (102) is fixedly coupled to the lower surface of the transparent carrier sheet (202) through an optical coupler (105), and is coated on the transparent carrier The NO ₂ nanometer fluorescent film (201) on the upper surface of the sheet (202) is corresponding. 4. The sensor according to claim 2, characterized in that: the incident end of the branch optical fiber (102) is fixedly coupled with the excitation light source (101) through an optical coupler (105), and the receiving end of the branch optical fiber (102) passes through Optical coupler (105) is fixedly coupled with photoelectric conversion device (103); The end extends into the detection pool (301), and the _NO2 nanometer fluorescent film (201) coated on the transparent carrier sheet (202) is placed in the detection pool (301) and is located directly below the total end face of the branch optical fiber (102). A reflection mirror (203) is arranged on the lower surface of the transparent carrier sheet (202) to enhance the fluorescence intensity radiated to the end face of the receiving fiber at the general end of the branch fiber (102). 5. The sensor according to claim 4, characterized in that: the detection cell (301) is provided with a sample gas inlet (303) and a sample outlet (304); the optical coupler (105) at the top of the detection cell (301) ) and the detection cell (301) are sealed by an "O" ring (305). 6. The sensor according to claim 4, characterized in that: the detection cell (301) is made of opaque metal material or non-metal material, and the non-metal material is polyether ether ketone or Teflon or polyvinyl chloride. 7. The sensor according to claim 1, characterized in that: said NO ₂ nanometer fluorescent film (201) refers to a fluorescent sensing film embedded with fluorescent probe perylene or Ti(Pc) ₂ .

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