A capacitive mems gas sensor

A gas sensor, capacitive technology, applied in the direction of material capacitance, etc., can solve the problems of high environmental requirements, sensor poisoning, and many limiting factors, and achieve the effect of strong anti-electromagnetic interference ability, fast dynamic response speed, and good accuracy and stability.

Active Publication Date: 2020-12-15
CHINA UNIV OF MINING & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The catalytic combustion methane sensor has the risk of ignition and explosion, and the sensor is easily poisoned by the influence of organic vapor; the semiconductor methane sensor has poor stability and has high environmental requirements; the thermal conductivity methane sensor has a narrow application range and is limited. many factors
Capacitive sensors have the advantages of no friction, no wear, good temperature stability, and fast dynamic response, but currently there is no capacitive methane sensor in my country

Method used

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  • A capacitive mems gas sensor
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  • A capacitive mems gas sensor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] The principle of the present invention is that the resistance of the semiconductor material changes with the change of the methane concentration in the ambient gas under a certain temperature condition, and the silicon beam is made of doped single crystal silicon, and a plurality of silicon beams are connected in parallel, and the micro shuttle and the silicon beam are connected in parallel. After the anchor area forms a thermal actuator, a current excitation is applied between the silicon beams. The degree of mechanical deformation after heating is related to the change of its own resistance. The deformation of the thermal actuator drives the capacitance value of the comb capacitor to change, so the capacitance value is used Changes can indicate the concentration of methane.

[0019] According to the experimental measurement, at a certain temperature, when the silicon beam made of doped single crystal silicon is placed in the air, when a certain value of current is appl...

Embodiment 2

[0025] In this example, a specific preparation method of the sensor in Example 1 is described. Specifically, such as Figure 5 shown, including the following steps:

[0026] In the first step, doping is carried out on the SOI silicon wafer including the top layer of silicon, the first silicon dioxide buried layer, and the silicon substrate (3) by diffusion or ion implantation, so that the top layer of silicon can form N-type silicon or P-type silicon ;

[0027] In the second step, a second silicon dioxide layer is prepared on the top layer of silicon;

[0028] The third step is to etch the micro-shuttle region of the second silicon dioxide layer to form the window required for doping;

[0029] The fourth step is to use diffusion or ion implantation to form P-type silicon or N-type silicon in the micro-shuttle (23) region, and the conductivity type of the micro-shuttle region is opposite to that of the top layer of silicon;

[0030] The fifth step is to use hydrofluoric aci...

Embodiment 3

[0039] In the present embodiment, the measurement method of the MEMS capacitive gas sensor of the present invention is specifically introduced, specifically, the following steps may be included:

[0040] (1) Measure the capacitance difference △C of the two comb-tooth capacitors when the MEMS gas sensor is static 0

[0041] (2) At normal temperature and in air, calibrate the corresponding table between the concentration of the gas to be tested and the capacitance change value;

[0042] (3) Apply a first current to the anchor zone III (22), and test the capacitance difference ΔC between the two comb teeth when the thermal actuator is not in action, and the ΔC is a compensation value;

[0043] (4) Apply the measurement current to the anchor area III (22), and test the capacitance difference ΔC of the two combs 1 ;

[0044] (5) The capacitance difference △C 1 The compensation value ΔC is removed, and the corresponding table is compared to obtain the measured gas concentration....

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Abstract

The invention relates to a capacitance type MEMS (micro-electro-mechanical system) gas sensor. The capacitance type MEMS gas sensor is particularly suitable for coal mine safety monitoring as well asdetection on methane gas in the air in production and living, can be applied to detection on the gases such as helium, carbon dioxide and argon in special environments, and comprises a thermal actuator and two comb capacitors, wherein the thermal actuator comprises a plurality pairs of silicon beams, a micro-spindle and an anchor area; and each group of comb capacitor comprises a movable comb, onegroup of folding structure spring, a fixed comb and an anchor area. The sensor can detect the concentration of the methane gas, adopts thermal deformation of the silicon beams to drive the capacitance change of the comb capacitors according to the principle that the resistance of a semiconductor material is changed along with the change of the methane content of the peripheral gas under a certaincurrent, and measures the methane concentration of the air according to the capacitance change. The capacitance type MEMS gas sensor has the following advantages of simple structure, high adaptability, no poisoning influence, no abrasion and no inertness due to capacitance type measurement, high temperature and precision stability, high electromagnetic interference resistance and high dynamic response speed.

Description

technical field [0001] A capacitive micro-electro-mechanical system (MEMS for short) gas sensor, especially suitable for coal mine safety monitoring and the detection of methane gas in the air in production and life, and can also be used for helium, carbon dioxide, argon in special environments gas detection. Background technique [0002] my country is one of the countries with the most gas accidents. Gas accidents not only cause heavy loss of life and property, but also affect the normal operation of coal production. Therefore, prevention and control of gas disasters is a very urgent task for coal mine safety production. In the process of preventing and controlling gas disasters, methane sensors for gas detection are essential. As the country pays more and more attention to mine safety, the demand for methane sensors used to detect methane and other gases is also increasing. The more common methane sensors are catalytic combustion methane sensors, semiconductor methane s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/22
CPCG01N27/22
Inventor 马洪宇王丽影秦顺利
Owner CHINA UNIV OF MINING & TECH
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