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A thin film gas sensor

A gas sensor and thin film technology, which is applied in the field of gas detection, can solve the problems of poor selectivity and inability to distinguish several gas concentrations, and achieve the effect of overcoming poor selectivity

Active Publication Date: 2018-01-09
安徽中科春谷激光产业技术研究院有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the broad-spectrum thin-film gas sensor has the problem of poor selectivity. When the thin film absorbs several gases at the same time, it is impossible to distinguish the respective concentrations of several gases because the detection is an electrical signal.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] figure 1 Shown is the basic structure and working principle of this embodiment.

[0035] This embodiment adopts the principle of photothermal deflection. The pumping light source 1 emits pumping laser light, the pumping light 1-1 is first incident on the beam splitter 2, and a small part of the light is incident on the light intensity detector 3 as a normalized signal to eliminate the 1 measurement errors caused by power fluctuations; the light intensity detector 3 inputs the received signal into the A / D conversion module 4-1, and then into the host computer 4 for data collection; most of the light passes through the beam splitter 2, Then chopping by a chopper 5 performs amplitude modulation, and the effect of the chopper 5 is to give a periodic modulation signal to the pump light 1-1; the signal of the chopper 5 is connected to the lock-in amplifier 10-2 , to suppress optical noise; finally, the pump light 1-1 is focused by the focusing lens 6 onto the selective abso...

Embodiment 2

[0038] Such as figure 2 As shown, different from Embodiment 1, this embodiment adopts the principle of photothermal amplification. The detection light 8-1 is obliquely incident on the selective absorption film 7 at a certain angle; when the selective absorption film 7 has a strong reflection on the detection light, the pinhole light intensity detector 9-2 is placed on the detection light 8-1 on the reflected light path. Such as Figure 3a As shown, when the selective absorption film 7 does not absorb the gas, the reflected light 8-2 reflected by the selective absorption film 7 is not amplified; when the selective absorption film 7 absorbs the gas, and the wavelength of the pump light 1-1 is in the gas absorption peak, then the selective absorption film 7 will rise to a height due to heat absorption, forming a bulge 7-1 such as Figure 3b As shown, at this time, part of the detection light 8-1 will expand the beam due to the protrusion 7-1, forming a defocused reflected lig...

Embodiment 3

[0040]The difference between this embodiment and embodiment 2 is that when the selective absorption film 7 has strong transmission for the detection light, the pinhole light intensity detector 9-2 is placed on the transmission light path of the detection light 8-1. Such as Figure 4a As shown, when the selective absorption film 7 does not absorb gas, the transmitted light 8-5 transmitted by the detection light 8-1 through the selective absorption film 7 is not amplified; as Figure 4b As shown, when the selective absorption film 7 absorbs the gas, and the wavelength of the pump light 1-1 is at the absorption peak of the gas, then the selective absorption film 7 will bulge to form a bulge 7-1 due to heat absorption, and at this time part of the detection light 8-1 will cause beam expansion due to this protrusion 7-1, forming defocused transmitted light 8-6, so that the light intensity incident on the pinhole light intensity detector 9-2 will become weaker, and it can be inferre...

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Abstract

A thin-film gas sensor that uses a selective absorption thin film that can absorb specific types of gas molecules in the air, focuses a beam of tunable wavelength pump light on the film, and adjusts the wavelength of the pump light to the absorption of specific gas molecules At the wavelength, the gas molecules will generate heat due to the absorption of the pump light, thereby generating a temperature gradient in the selective absorption film and the adjacent medium, and then letting a beam of detection light pass through the temperature gradient, the detection light will be deflected or defocused, according to the detection The amount of deflection or defocus detected by the photodetector is used to infer the gas content. The present invention adopts the method of spectral detection, and can select appropriate spectral lines of several kinds of gas molecules, so that these spectral lines are staggered from each other, which overcomes the problem of poor selectivity caused by the inability to distinguish signals of different gas molecules in traditional sensors for detecting electrical signals. question.

Description

technical field [0001] The invention relates to the field of gas detection, in particular to a thin-film gas sensor based on photothermal spectroscopy. Background technique [0002] With the development of industrialization in today's society, the problem of air pollution is becoming more and more prominent. The greenhouse effect, acid rain, and the destruction of the ozone layer are imminent. The key to solving these problems is to quickly and accurately detect these toxic and polluting gas substances. In addition, gas detection is also very important in home safety, mine operations, fire alarms, etc., which provides the best objective conditions for the development of gas sensors. [0003] Gas sensors based on thin films are a type of gas sensors that are being developed mainly because of their low cost and simple detection devices. It converts the type and concentration of the gas adsorbed by the film into electrical signals, and the information of the gas to be measured...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/25
Inventor 王欢陈昱李建春闫国枫
Owner 安徽中科春谷激光产业技术研究院有限公司
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