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Self-hold dark discharge carbon nanometer pipe film gas sensor and its gas concentration measuring method

A carbon nanotube thin film and gas concentration measurement technology, which is applied in the direction of measuring devices, instruments, scientific instruments, etc., can solve the problems of no structure, no specific feasible method for measuring gas concentration, and no practical gas sensor.

Inactive Publication Date: 2008-07-16
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The biggest problem with these existing technologies is that they require high technical requirements for implementation, are inconvenient to use, and are expensive to analyze, and are not suitable for environmental detection anytime and anywhere.
[0003] In the prior art before the present invention, someone tries to use the discharge type gas sensor as the means of gas qualitative and quantitative analysis, because the breakdown voltage Vs of the discharge type gas sensor is related to the measured gas concentration There is a positive and negative correlation between them, because the captured signal is affected by many complex factors (such as temperature fluctuations, humidity fluctuations, atmospheric pressure fluctuations, fluctuations in the amount of residual charge in space, and fluctuations in the intensity of various rays in space, etc.), It is often submerged in the noise interference signal. If the useful signal is not separated, the breakdown voltage Vs of the sensor and the concentration of the gas to be measured cannot be used. Therefore, it is impossible to use it as the basis for qualitative and quantitative analysis of gases.
So far, the existing technology has not solved the problem of measurement and identification of the signal captured by the discharge gas sensor, so that the discharge gas sensor cannot enter the practical stage, and it still needs to be integrated with a mass spectrometer or chromatograph
For example, the self-sustained dark discharge type gas sensor with a micron-electrode semiconductor silicon material constructed by Dai Pinghu of Zhejiang University and others has a micron-scale curvature radius at the top of the cathode, and a very high electric field is concentrated in a small area with a distance of 50 μm, which can darken the gas under atmospheric pressure. The operating voltage required for discharge is reduced to one-tenth (above 350V) of the usual value (5000-10000V), and the self-sustaining dark discharge I-V characteristics, sensor discharge current sensitivity and response speed of water vapor and 5 kinds of single organic gases are obtained. Such valuable work results, but the sensor belongs to a micron-scale micro-electrode constructed by micro-machining technology MEMS, the working voltage is still high, and the specific feasibility method for measuring the gas concentration is not given, and it has not formed a practical gas sensor
Another example is the carbon nanotube film anode gas sensor developed by Nikhil Koratkar and Pulickel M.Ajayan in Japan. It uses corona discharge as a mechanism and uses breakdown voltage as a characteristic parameter for qualitative measurement of a single gas species. Although multi-walled carbon nanotubes have been studied tube film cathode spacing and breakdown voltage, but did not give a feasible method for measuring a single gas species mixed in the atmosphere, nor did it give a method for quantitatively measuring the concentration of a single gas mixed in the atmosphere, and has not yet constructed Carbon nanotube thin film gas sensor
At present, the methods and corresponding gas sensors that have solved the problem of signal recognition and entered into practical use have not been reported at home and abroad.

Method used

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  • Self-hold dark discharge carbon nanometer pipe film gas sensor and its gas concentration measuring method
  • Self-hold dark discharge carbon nanometer pipe film gas sensor and its gas concentration measuring method
  • Self-hold dark discharge carbon nanometer pipe film gas sensor and its gas concentration measuring method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0064] Embodiment 1: single gas methane (measurement concentration range 0~50000×10 -6 ) measurement steps:

[0065] The carbon nanotube thin film cathode gas sensor structure is shown in Figure 2(c); a sensor with an electrode spacing of 170 μm (1#) and an electrode area of ​​1.5 mm×4 cm was fabricated, which is called a prototype sensor.

[0066] Step 1: The 1D original initial model of the prototype sensor is obtained:

[0067] Through the discharge characteristics test system (see Figure 3), the one-dimensional original initial model of the 1# carbon nanotube thin film cathode sensor with a pole spacing of 170 μm to methane under normal temperature and pressure is the breakdown voltage of methane gas and the measured methane concentration relationship curve (such as Figure 4 shown).

[0068] Step 2: Establish the initial model database for one-dimensional interpolation of the prototype sensor:

[0069] Using cubic spline interpolation technique to Figure 4 The one-dim...

Embodiment 2

[0100] Methane and carbon monoxide (measurement concentration range is 0~50000×10 -6 , 0~500×10 -6 ) two-component gas mixture measurement steps:

[0101] The carbon nanotube thin film cathode gas sensor structure is shown in Figure 2(c); two sensor arrays with electrode spacing specifications of 170 μm (1# sensor) and 100 μm (2# sensor) and an electrode area of ​​1.5mm×4cm were fabricated.

[0102] Step 1: Obtain the two-dimensional original initial model of the prototype sensor: use a two-sensor array composed of 1# and 2# sensors with electrode spacings of 170 μm and 100 μm respectively, and measure the two groups of methane and carbon monoxide under normal temperature and pressure in a carrier gas environment. The two-dimensional original initial model of the mixed gas is as follows Figure 5 , 6 shown.

[0103] Step 2: Establish the initial model database for the two-dimensional interpolation of the prototype sensor: Figure 5 , 6 The two-dimensional original initia...

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Abstract

The invention relates to a method of using a discharge gas sensor to directly measure the density of gas and nano carbon pipe film gas sensor, including the characteristics that: measure breakdown voltage of the sensor by discharge characteristics testing system to acquire one or two or multiple dimensional original model; use interpolation fitting process to build interpolation original model; do monodromy conversion and build the secondary rebuilt model of the sensor; build verse modle of the secondary rebuilt model the sensor is made of two pieces of ITO film conducting glass or two pieces of conducting glass material, whose two poles both hate multiply holes pasting to carbon millimicron pipe film and the distance of poles is structural characteristic parameter.

Description

technical field [0001] The invention belongs to the technical field of gas analysis and detection, and relates to a method for measuring gas concentration with a discharge type gas sensor and a self-sustained dark discharge carbon nanotube (carbon nanotube, CNT) film gas sensor based on the method. Background technique [0002] As people pay more and more attention to the living environment and environmental protection, higher requirements are put forward for the detection of various toxic and harmful gases, the monitoring of air pollution and industrial waste gas, and the detection of the quality of food and human settlements. As early as the 1990s, the United States developed the most advanced analyzer in the world so far——Atmospheric Pressure Ionization Mass Spectrometer (APIMS), which can detect impurities in gases up to 100×10 -12 range, becoming a solution to a variety of 10 -12 The only means of level gas impurity analysis. The Discharge Ionization Detector invented...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/92G01N27/407
Inventor 刘君华张勇朱长纯李昕
Owner XI AN JIAOTONG UNIV