CN103674909A - Sensor for detecting gas nitro-aromatics explosives - Google Patents

Abstract

The invention relates to a sensor for detecting gas nitroaromatic explosives. The core-exposed microstructure optical fiber sensor head is placed in an air chamber, and the core surface of the fiber core-exposed microstructure optical fiber sensor head is coated with paranitrogen. MEH-PPV is a fluorescent material sensitive to aromatic hydrocarbons and explosives. There are gas inlets and outlets on the gas chamber, which are used to pass through different concentrations of explosive gases. The light emitted by the laser is focused and coupled into the core exposed micro In the structural fiber sensor head, the output laser and fluorescence are filtered by a high-pass filter with a cut-off wavelength of 510nm, and finally focused into the spectrometer by the second lens. The concentration of gas explosives is detected by detecting the fluorescence intensity of the fluorescent material with a spectrometer. Compared with similar products, the invention can improve the detection lower limit and sensitivity. Because the fiber core is exposed, the fluorescent material coated around the air holes can directly interact with gas explosives, and has the advantages of fast detection speed, stable working performance, and small required sample volume.

Description

A sensor for detecting gaseous nitroaromatic explosives

technical field

The invention relates to a sensor, in particular to a sensor which uses a core-exposed microstructure optical fiber as a sensing head to detect gas nitroaromatic explosives.

Background technique

Explosive detection technology can be used in anti-terrorism, non-metal mine detection and environmental quality monitoring and other fields. Especially in recent years, international terrorist activities have become increasingly rampant. According to relevant statistics, terrorist bombings alone account for 57% of global terrorist activities. Nitroaromatic explosives such as trinitrotoluene (TNT) are often used by terrorists due to their high explosive power and low cost, and TNT is contained in 21 explosive-related compounds as by-products and degradation products . Therefore, in order to effectively control and combat terrorist activities and maintain the safety of the country and the people, it is of great and far-reaching economic and social significance to develop new methods and new equipment for the detection of nitroaromatic explosives with high sensitivity, short detection time, and stable working conditions. become the focus of attention of countries all over the world.

At present, the detection of micro-trace nitroaromatic explosives can be carried out by electrochemical methods, molecular imprinting methods, ion mobility spectrometry, biosensing methods and optical methods. Among them, the optical method, especially the fluorescence quenching method, has attracted the most attention. This is because compared with other methods, the fluorescence quenching method has high sensitivity, good selectivity, fast detection speed, small sensor volume, low cost, and easy operation. It is considered to be one of the most ideal technologies for the detection of trace explosives due to its simplicity and simplicity.

As shown in Figure 1, the cross-sectional schematic diagram of the core-exposed microstructure optical fiber sensor head, the middle core 4-2 of the core-exposed microstructure optical fiber has a diameter of 10 microns, and there are two air holes 4-2 with a diameter of 8 microns around it. 1. Another air hole 4-4 is not closed to expose part of the fiber core, and the outer diameter 4-3 is 125 microns. The advantage of this sensor head is that the fluorescent indicator can be directly coated around the air hole, and the detected gas nitroaromatic explosives can directly interact with the fluorescent indicator, and the detection time is short.

The main technical problem of the current micro-trace explosives sensor based on the principle of fluorescence quenching is that the fluorescence intensity of the fluorescent indicator is weak, which increases the difficulty of detecting the fluorescent signal and reduces the sensitivity and detection limit of the system.

Contents of the invention

The present invention aims at the problem that the current micro-trace explosive sensor based on the principle of fluorescence quenching reduces the detection sensitivity due to the weak fluorescence intensity of the fluorescent indicator, and proposes a sensor for detecting gas nitroaromatic explosives, a fluorescent indicator The intensity of the explosive will decrease with the increase of the concentration of the explosive, and the detection sensitivity of the concentration of the explosive by detecting the fluorescence intensity of the fluorescent indicator will decrease. Since the evanescent wave intensity of the exposed core microstructure fiber is relatively large, the fluorescence intensity will be improved. The luminous intensity of the indicator achieves the purpose of improving the sensitivity and detection limit of the system, and can well solve the problems existing in this type of sensor at present.

The technical solution of the present invention is: a sensor for detecting gaseous nitroaromatic explosives, including a laser, two focusing lenses, an adjustment frame for resting the focusing lenses, a core-exposed microstructure optical fiber sensor head, an air chamber, a high-pass Filters, spectrometers, core-exposed microstructure optical fiber sensing head are placed in the gas chamber, and the surface of the fiber core exposed microstructure optical fiber sensing head is coated with fluorescent material MEH- which is sensitive to nitroaromatic explosives. PPV, there are gas inlets and outlets on the gas chamber, the light emitted by the laser is focused by the first focusing lens, and the laser emitted by the first focusing lens is coupled into the core-exposed microstructure optical fiber sensor head through the end-face coupling method, and the core is exposed The laser light and fluorescence output by the micro-structure optical fiber sensor head are filtered by a high-pass filter with a cut-off wavelength of 510nm, and finally focused by the second lens into the spectrometer. probing.

The light emitted by the laser is focused by the first focusing lens, and the adjusting frame under the first focusing lens is adjusted so that the laser light emitted by the first focusing lens is coupled to the fiber end face of the core-exposed microstructure fiber sensor head.

The beneficial effect of the invention is that: the sensor for detecting gas nitroaromatic explosives of the invention can improve the detection lower limit and sensitivity compared with similar products. In addition, due to the exposed fiber core of this sensor, the fluorescent material coated around the air hole can directly interact with gas explosives, which has the advantages of fast detection speed, stable working performance, and small sample volume.

Description of drawings

Figure 1 is a schematic cross-sectional view of a core-exposed microstructure optical fiber sensing head;

Fig. 2 is a schematic structural diagram of a sensor for detecting gaseous nitroaromatic explosives according to the present invention.

Detailed ways

As shown in Figure 2, a schematic structural diagram of a sensor for detecting gaseous nitroaromatic explosives, including a laser 1, a focusing lens 2, an adjustment frame 3 on which the focusing lens 2 rests, a core-exposed microstructure optical fiber sensing head 4, and an air chamber 5 , high-pass filter 6, focusing lens 7, spectrometer 8. Among them, the core-exposed microstructure optical fiber sensor head is a schematic cross-sectional diagram as shown in FIG. 2 .

Preparation of the core-exposed microstructure optical fiber sensing head 4: firstly, the sensitive material MEH-PPV was dissolved in chloroform at a concentration of 0.5 mg/ml. Then place the 20-centimeter-long core-exposed microstructure optical fiber sensing head 4 in the sensitive material for 5 minutes. After taking it out, put it in an oven with a temperature of 80 degrees for 10 minutes, and take it out of the oven after the chloroform volatilizes.

After the light emitted by the laser 1 is focused by the focusing lens 2, the adjustment frame 3 is adjusted so that the laser light emitted by the focusing lens 2 is coupled into the core-exposed microstructure optical fiber sensor head 4 by the end-face coupling method, and the core-exposed microstructure optical fiber The end face of the sensing head 4 is a schematic cross-sectional view as shown in FIG. 1 .

Place the core-exposed microstructure optical fiber sensing head 4 in the gas chamber 5, and the gas chamber 5 has gas inlets and outlets for passing different concentrations of explosive gases; the laser and fluorescent light in the optical fiber pass through with a cut-off wavelength of 510nm The high-pass filter 6, and finally enters the spectrometer 8 through the lens focus 7. The concentration of gas explosives is detected by detecting the fluorescence intensity of the fluorescent material with a spectrometer.

Claims (2)

1. a sensor that detects gas nitro arene explosive substance, it is characterized in that, comprise laser instrument, two condenser lenses, shelve the adjustment rack of condenser lens, fibre core exposed type microstructure optical fiber sensing head, air chamber, high-pass filter, spectrometer, fibre core exposed type microstructure optical fiber sensing head is placed in air chamber, fibre core exposed type microstructure optical fiber sensing head surface is coated with the fluorescent material MEH-PPV to nitro-aromatic class class explosive sensitivity, on air chamber, there are gas feed and outlet, the light that laser instrument sends focuses on through the first condenser lens, the first condenser lens emitting laser enters in fibre core exposed type microstructure optical fiber sensing head through the coupling of end face coupling process, the laser of fibre core exposed type microstructure optical fiber sensing head output and the high-pass filter of fluorescence through being 510nm by wavelength filter, finally by the second lens focus, enter spectrometer, spectrometer is surveyed the fluorescence intensity of fluorescent material gas burst substrate concentration in air chamber is surveyed.

2. detect according to claim 1 the sensor of gas nitro arene explosive substance, it is characterized in that, the light that described laser instrument sends focuses on through the first condenser lens, regulate the adjustment rack under the first condenser lens, make the first condenser lens shoot laser be coupled to the fiber end face of fibre core exposed type microstructure optical fiber sensing head.

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