Gas sensor array and gas sensor chip

Abstract

The invention discloses a gas sensor and a gas sensor calibration method. The gas sensor comprises a shell, a gas sensitive part, a gas suction part, a gas release part and a plurality of micro hot plates, a sealing baffle is arranged in the shell, and the sealing baffle is used for shielding or opening the ventilation opening; the gas suction part is used for absorbing gas in the shell so as to calibrate a zero point; the gas releasing part is used for releasing gas to calibrate the full scale. The ventilation opening is blocked through the sealing baffle, and a sealed cavity can be formed in the shell. The gas suction part can absorb gas in the cavity, the resistance value of the gas sensitive part at the moment is measured, and calibration of the zero point of the gas sensor can be achieved. The gas releasing part is used for releasing gas, after the shell is filled with the gas, the resistance value of the gas sensitive part at the moment can be measured, and full-scale calibration of the gas sensor is achieved. According to the gas sensor, the defect that the calibration process of a traditional sensor is complex can be overcome, automatic correction calibration of the gas sensor can be achieved, the calibration complexity can be reduced, and the use cost of the gas sensor can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of gas detection, and particularly to a gas sensor array and a gas sensor. Background Art

[0002] Metal Oxide Semiconductor (MOS) is a type of sensitive material commonly used in gas sensors, which has advantages such as low cost and high sensitivity. Therefore, MOS is widely used in the field of gas sensing. Its sensitive mechanism is that when target gas molecules adsorb to the surface of the MOS material, they interact with the oxygen atoms on the material surface, causing oxygen adsorption and desorption, and then affecting the resistance of the gas-sensitive material. By detecting the resistance value of the gas-sensitive material of the gas sensor, the detection of the concentration of the target gas in the environment can be achieved.

[0003] Gas sensors can detect gas leakage and remind people to take safety measures such as personnel evacuation, forced ventilation, and equipment shutdown by emitting alarm signals such as sound and light. They are indispensable instruments in industrial production and daily life.

[0004] Gas sensors do not always accurately measure gas concentration. Under the influence of factors such as long-term degradation of the sensor, poor sensor quality, sensor poisoning, and harsh environmental conditions, the zero point of the sensor will fluctuate, which is called "calibration drift". In order to ensure the accuracy of the gas sensor and the integrity of the system, the gas sensor needs to be calibrated. The fixed installation position of the sensor is very important, and the position must make calibration easy to complete. The calibration interval varies depending on the sensor, and generally, calibration is performed once every 3 - 6 months. The more times of calibration, the less likely the detector is to drift, and the better the detection effect. By regularly calibrating, the error of the detection result is minimized and the accuracy reaches the highest.

[0005] Currently, the calibration process of traditional gas sensors is very complex and requires specific calibration equipment, including gas sources, flow meters, connectors, pressure gauges, etc. The operation process is relatively complex. At the same time, the calibration period is short, resulting in a relatively high maintenance and use cost of gas sensors. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defect that the calibration process of gas sensors in the prior art is very complex, and to provide a gas sensor calibration method and a gas sensor.

[0007] The present invention solves the above technical problem through the following technical solutions:

[0008] A gas sensor, the gas sensor comprising: a housing, a gas-sensitive part, a gas absorption part, a gas release part, and a plurality of micro-hotplates. The housing has a ventilation opening, and a sealing baffle is provided inside the housing. The sealing baffle is used to block or open the ventilation opening. The gas-sensitive part is deposited on the micro-hotplate. The gas absorption part is deposited on the micro-hotplate. The gas absorption part is used to absorb the gas inside the housing to calibrate the zero point of the gas sensor. The gas release part is deposited on the micro-hotplate. The gas release part is used to release gas to calibrate the full scale of the gas sensor.

[0009] In this solution, by adopting the above structure, by arranging the gas-sensitive part, the gas absorption part, the gas release part, and a plurality of micro-hotplates inside the housing, and using the sealing baffle to block the ventilation opening, a sealed cavity can be formed inside the housing. The gas absorption part can absorb the gas in the cavity, measure the resistance value of the gas-sensitive part at this time, and the zero point calibration of the gas sensor can be realized. By using the gas release part to release gas, after the released gas fills the housing, the resistance value of the gas-sensitive part can be measured to realize the full scale calibration of the gas sensor. The gas sensor can avoid the defect of complex calibration process of traditional sensors, can realize the automatic correction calibration of the gas sensor, can reduce the calibration complexity, and can reduce the use cost of the gas sensor.

[0010] Optionally, the gas absorption part can form a stable compound with the active gas at room temperature; the gas absorption part is activated by heating through the micro-hotplate.

[0011] Optionally, the material of the gas absorption part includes non-evaporable getter material; or the material of the gas absorption part includes one or two of titanium-zirconium-vanadium getter or zirconium-vanadium-iron getter.

[0012] Optionally, the gas release part is solid at room temperature, and the gas release part releases gas after being heated by the micro-hotplate.

[0013] Optionally, the material of the gas release part includes one or two of ammonium salts or metal hydrides.

[0014] Optionally, a plurality of the micro-hotplates form a micro-hotplate array, and the gas-sensitive part, the gas absorption part, and the gas release part are deposited on different micro-hotplates.

[0015] Optionally, the material of the gas-sensitive part is tin oxide; the material of the gas absorption part is titanium-zirconium-vanadium; the material of the gas release part is magnesium hydride.

[0016] Optionally, the material of the gas-sensitive part is zinc oxide; the material of the gas absorption part is zirconium; the material of the gas release part is solid ammonium nitrate.

[0017] A gas sensor calibration method, the gas sensor calibration method uses the gas sensor as described above, and the gas sensor calibration method includes:

[0018] Use the sealing baffle to close the ventilation opening;

[0019] Use the micro-hotplate to heat the gas suction part, and after the gas suction part is heated and activated, it absorbs the gas in the shell;

[0020] After the absorption is completed, measure the resistance value of the gas sensing part and calibrate it as zero point.

[0021] Optionally, after the absorption is completed, the micro-hotplate heats the gas release part, the gas release part releases gas, and when the concentration of the released gas reaches the maximum detection range of the gas sensor, measure the resistance value of the gas sensing part and calibrate it as the full scale.

[0022] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0023] The positive and progressive effects of the present invention are as follows:

[0024] In the present invention, the gas sensing part, the gas suction part, the gas release part and several micro-hotplates are arranged in the shell, and the ventilation opening is blocked by the sealing baffle, so that a sealed cavity can be formed inside the shell. The gas suction part can absorb the gas in the cavity, and by measuring the resistance value of the gas sensing part at this time, the zero point calibration of the gas sensor can be realized. By using the gas release part to release gas, after the released gas fills the shell, the resistance value of the gas sensing part can be measured to realize the full scale calibration of the gas sensor. The gas sensor can avoid the defect of complex calibration process of the traditional sensor, can realize the automatic correction and calibration of the gas sensor, can reduce the calibration complexity, and can reduce the use cost of the gas sensor. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the packaging structure of the gas sensor of the present invention.

[0026] Figure 2 It is a schematic diagram of the structure of the micro-hotplate in the gas sensor of the present invention.

[0027] Figure 3 For Figure 2 Schematic diagram of the temperature rise of the micro-hotplate.

[0028] Figure 4 It is a schematic diagram of the temperature-power consumption curve of a single micro-hotplate in the gas sensor.

[0029] Figure 5 It is a comparison table of the relevant performances of different metal hydrides in the gas sensor.

[0030] Description of the reference numerals:

[0031] Gas sensor 100

[0032] Housing 11

[0033] Sealing baffle 111

[0034] Vent 112

[0035] Gas-sensitive part 12

[0036] Gas suction part 13

[0037] Gas release part 14

[0038] Micro hot plate 15 Specific implementation manner

[0039] The present invention will be more clearly and completely described below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments thereby.

[0040] As Figures 1-5 shown, this embodiment includes a gas sensor 100 and a gas sensor calibration method. Among them, the gas sensor calibration method uses the gas sensor 100.

[0041] The gas sensor 100 includes: a housing 11, a gas-sensitive part 12, a gas suction part 13, a gas release part 14 and a plurality of micro hot plates 15. The housing 11 has a vent 112, and a sealing baffle 111 is provided inside the housing 11. The sealing baffle 111 is used to block or open the vent 112; the gas-sensitive part 12 is deposited on the micro hot plate 15; the gas suction part 13 is deposited on the micro hot plate 15, and the gas suction part 13 is used to absorb the gas inside the housing 11 to calibrate the zero point of the gas sensor 100; the gas release part 14 is deposited on the micro hot plate 15, and the gas release part 14 is used to release gas to calibrate the full scale of the gas sensor 100. By arranging the gas-sensitive part 12, the gas suction part 13, the gas release part 14 and a plurality of micro hot plates 15 inside the housing 11 and using the sealing baffle 111 to block the vent 112, a sealed cavity can be formed inside the housing 11. The gas suction part 13 can absorb the gas in the cavity, and by measuring the resistance value of the gas-sensitive part 12 at this time, the zero point calibration of the gas sensor 100 can be realized. By using the gas release part 14 to release gas, after the released gas fills the housing 11, the resistance value of the gas-sensitive part 12 can be measured to realize the full scale calibration of the gas sensor 100. The gas sensor 100 can avoid the defect of the complex traditional sensor calibration process, can realize the automatic correction calibration of the gas sensor 100, can reduce the calibration complexity, and can reduce the use cost of the gas sensor 100.

[0042] The air intake part 13 can be understood as including components or materials capable of absorbing specific gases. As an implementation manner, the air intake part 13 can form a stable compound with active gases at normal temperature; the air intake part 13 is activated by heating through the micro hot plate 15. Specifically, the material of the air intake part 13 includes non-evaporable gettering materials; or the material of the air intake part 13 includes one or both of titanium-zirconium-vanadium getters or zirconium-vanadium-iron getters. Non-evaporable gettering materials can be understood as those that can form stable compounds with active gases for gas absorption at normal temperature, but need to be activated by heating through the micro hot plate 15 before use; for example, titanium-zirconium-vanadium getters, zirconium-vanadium-iron getters, etc.

[0043] The gas release part 14 can be understood as including components capable of releasing gases. As an implementation manner, the gas release part 14 is solid at normal temperature, and the gas release part 14 releases gases after being heated by the micro hot plate 15. Specifically, the material of the gas release part 14 includes one or both of ammonium salts or metal hydrides.

[0044] Combined Figure 2 , the micro hot plate 15 can be fabricated using MEMS (Micro-Electro-Mechanical System) technology. The micro hot plate 15 can convert electrical energy into heat energy to achieve heating of other components and provide a suitable temperature environment.

[0045] As an implementation manner, a plurality of micro hot plates 15 form a micro hot plate 15 array, and the gas sensing part 12, the air intake part 13 and the gas release part 14 are deposited on different micro hot plates 15.

[0046] The gas sensing part 12 can be understood as including components capable of reacting with specific gases. Including but not limited to SnO 2 , ZnO, Fe 2 O 3 , Cr 2 O 3 , MgO, NiO 2 , etc. At high temperatures of the MEMS micro hot plate 15, the composition or concentration of gases is detected by using the change in the resistance value of the gas sensing part 12 when it contacts the gases.

[0047] The material of the sealing baffle 111 can include rubber, metal, etc. The sealing baffle 111 can seal the ventilation opening 112 through pulleys, and the specific driving method can adopt electrostatic, piezoelectric driving and other methods.

[0048] This embodiment further includes a gas sensor calibration method. The gas sensor calibration method uses the gas sensor 100 as described above, and the gas sensor calibration method includes:

[0049] Using the sealing baffle 111 to close the ventilation opening 112;

[0050] The suction part 13 is heated by the micro hot plate 15. After the suction part 13 is heated up and activated, it absorbs the gas inside the housing 11.

[0051] After the absorption is completed, the resistance value of the gas sensing part 12 is measured and calibrated as zero point.

[0052] After the absorption is completed, the micro hot plate 15 heats the gas release part 14. The gas release part 14 releases gas. When the concentration of the released gas reaches the maximum detection range of the gas sensor 100, the resistance value of the gas sensing part 12 is measured and calibrated as the full scale.

[0053] Combined with Figure 2 , when the gas sensor 100 needs to be calibrated, the sealing baffle 111 seals the ventilation port 112 through the pulley. The micro hot plate 15 of the suction part 13 is heated up to activate the suction part 13. The suction part 13 absorbs the organic gas inside the packaging cavity. At this time, zero point calibration is carried out on the gas sensor 100, and the resistance value of the gas sensing part 12 is measured and calibrated to this state as the zero point.

[0054] To ensure that the suction part 13 can completely absorb the organic gas inside the housing 11, it can be achieved by controlling the volume of the material of the suction part 13, controlling the zero point calibration time, etc. The larger the volume of the material of the suction part 13, the more gas can usually be absorbed. The longer the zero point calibration time is controlled, the more thorough the gas absorption can be.

[0055] After the suction is completed, the micro hot plate 15 of the gas release part 14 is heated up to a specific temperature, and the gas release part 14 can be controlled to release gas. Specifically, by calculating the space volume and the gas release volume, the concentration inside the cavity can reach the maximum detection range of the gas sensor 100, that is, the full scale. At the full scale concentration, range calibration is carried out on the gas sensor 100, and the resistance value of the gas sensor 100 is measured and calibrated to this state as the full scale.

[0056] It can be determined through theoretical calculation or experimental verification that the gas density = gas release amount - gas dissipation. At the same time, to ensure the calibration accuracy, it can also be tested multiple times under different concentration states.

[0057] As a specific implementation manner, combined with Figures 2-5 , the material of the gas sensing part 12 is tin oxide; the material of the suction part 13 is titanium zirconium vanadium; the material of the gas release part 14 is magnesium hydride.

[0058] A single MEMS micro hot plate 15 fabricated by micro-nano technology can be as Figure 2 shown. Multiple MEMS micro hot plates 15 can form an MEMS micro hot plate 15 array. The voltage-temperature rise curve of the MEMS micro hot plate 15 is as Figure 3 shown. By using the microspray process, the gas sensing material - SnO can be deposited on some of the MEMS micro hot plates 15 respectively 2; Depositing MgH on part of the MEMS micro-hotplate 15 through microspray technology 2 , such as common metal hydrides Figure 5 As shown. Depositing titanium zirconium vanadium on part of the MEMS micro-hotplate 15 through microspray technology, titanium zirconium vanadium has a strong chemical adsorption and large solubility for H 2 , and its activation temperature is 200°C.

[0059] When the gas sensor 100 is zero-point calibrated, the sealing baffle 111 keeps the internal closed environment of the packaging shell 11, applies a 1V DC voltage (200°C) to the micro-hotplate 15 of the gas absorption part 13 to activate the titanium zirconium vanadium material; after acting for a period of time, the acting time can be verified by theoretical calculation or single experiment, then applies a 1.6V voltage (350°C) to the MEMS micro-hotplate 15 of the gas sensing part 12, measures the resistance value of the gas sensing part 12, and calibrates this as the zero-point resistance value of the gas sensor 100. The micro-hotplate 15 of the gas absorption part 13 stops working. After waiting for a few minutes, applies a 1.22V voltage (300°C) to the micro-hotplate 15 of the gas release part 14 and acts for a few minutes; measures the temperature resistance value of the gas sensing part 12 and calibrates this as the full-scale resistance value of the gas sensor 100; the micro-hotplate 15 of the gas release part 14 stops working, the sealing baffle 111 is opened, the inside of the packaging shell 11 contacts the outside air, and the calibration process ends.

[0060] In other examples, the material of the gas sensing part 12 can be zinc oxide; the material of the gas absorption part 13 is zirconium; the material of the gas release part 14 is ammonium nitrate solid.

[0061] The gas sensing material ZnO can be deposited on the MEMS micro-hotplate 15 respectively by using the microspray process; ammonium nitrate solid (NH 4 NO 3 ) can be deposited on the MEMS micro-hotplate 15 through microspray technology; active metal Zr and its compounds can be deposited on the MEMS micro-hotplate 15 through microspray technology. Zr and its compounds have a strong chemical adsorption and large solubility for NH 4 , and its activation temperature is 500°C; its calibration process is similar to that of the H 2 gas sensor 100 and will not be elaborated here.

[0062] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that this is only for illustration. The protection scope of the present invention is defined by the appended claims. Without departing from the principle and essence of the present invention, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A gas sensor, characterized in that: The gas sensor comprises: A shell having a vent, a sealing baffle provided inside the shell, and the sealing baffle used to cover or open the vent; Several micro hotplates; A gas sensing portion, the gas sensing portion being deposited on the micro-hotplate; An air intake portion, the air intake portion is deposited on the micro-hotplate, and the air intake portion is used to absorb the gas in the shell to calibrate the zero point of the gas sensor; A gas release portion is deposited on the micro-hotplate and is used for releasing gas to calibrate the full scale of the gas sensor.

2. The gas sensor according to claim 1, characterized in that The air intake part can form a stable compound with the active gas at room temperature; the air intake part is activated by heating through the micro-hot plate.

3. The gas sensor according to claim 2, characterized in that The material of the getter part includes a non-evaporable getter material; or the material of the getter part includes one or both of a titanium-zirconium-vanadium getter or a zirconium-vanadium-iron getter.

4. The gas sensor according to claim 1, wherein: The gas release portion is solid at room temperature, and releases gas after being heated by the micro-hotplate.

5. The gas sensor according to claim 4, characterized in that The material of the gas release portion includes one or both of ammonium salts and metal hydrides.

6. The gas sensor according to claim 1, wherein: A plurality of the micro-hotplates form a micro-hotplate array, and the gas sensing portion, the gas absorption portion, and the gas release portion are deposited on different micro-hotplates.

7. The gas sensor according to claim 1, wherein: The material of the gas sensing part is tin oxide; the material of the air intake part is titanium zirconium vanadium; and the material of the gas release part is magnesium hydride.

8. The gas sensor according to claim 1, wherein: The material of the gas-sensing part is zinc oxide; the material of the air-intake part is zirconium; and the material of the gas-releasing part is solid ammonium nitrate.

9. A gas sensor calibration method, characterized in that: The gas sensor calibration method uses the gas sensor according to any one of claims 1 to 8, and the gas sensor calibration method includes: Using the sealing baffle to close the vent; The air intake part is heated by the micro-hot plate, and the air intake part absorbs the gas in the shell after being heated and activated; After the absorption is completed, the resistance value of the gas-sensitive portion is measured and calibrated as zero point.

10. The gas sensor calibration method according to claim 1, characterized in that: After the absorption is completed, the micro-hotplate heats the gas release part, and the gas release part releases gas. When the concentration of the released gas reaches the maximum detection range of the gas sensor, the resistance value of the gas sensitive part is measured and calibrated as the full scale.

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