CN221303207U

CN221303207U - Testing device for gas-sensitive characteristic of hydrogen sensor

Info

Publication number: CN221303207U
Application number: CN202323205175.XU
Authority: CN
Inventors: 谭粤; 徐瑶; 周池楼; 叶知秋; 吴昊; 段祺耀; 曹嘉喜; 吴政桦; 黄彦; 冯基桉
Original assignee: GUANGDONG INSTITUTE OF SPECIAL EQUIPMENT INSPECTION; South China University of Technology SCUT
Current assignee: GUANGDONG INSTITUTE OF SPECIAL EQUIPMENT INSPECTION; South China University of Technology SCUT
Filing date: 2023-11-27
Publication date: 2024-07-09
Anticipated expiration: 2033-11-27

Abstract

The utility model provides a testing device for the gas sensitivity characteristic of a hydrogen sensor, which comprises a gas distribution instrument, a tube furnace, a digital source meter and a computer, wherein the gas distribution instrument is used for mixing diluent gas and hydrogen gas and outputting gas with set concentration; the gas outlet of the gas distribution instrument is communicated with the tube furnace, mixed hydrogen is introduced into a testing cavity of the tube furnace, air for recovering resistance is introduced into the testing cavity of the tube furnace, and a test sample to be detected is arranged in the testing cavity; the digital source table is used for being connected with the test sample wafer through a wire, and the digital source table is connected with a computer. The utility model judges the concentration change of the hydrogen by checking the resistance of the sample, and can measure the sensing characteristic by the utility model as long as the resistance of the sample to be tested can be measured, when the resistance is reduced, the hydrogen is detected, and when the surrounding gas environment is restored to the air, the resistance is restored to the original resistance again. The device does not need preheating for testing, and has low working temperature and high response speed.

Description

Testing device for gas-sensitive characteristic of hydrogen sensor

Technical Field

The utility model relates to the technical field of gas testing, in particular to a testing device for the gas sensitivity characteristic of a hydrogen sensor.

Background

The hydrogen sensor is a testing device capable of monitoring the concentration of hydrogen in the process of producing and using hydrogen. It is widely applied to the fields of hydrogen energy infrastructures such as hydrogen energy automobiles, hydrogen stations and the like, chemical processes, metal smelting, aerospace and the like. Hydrogen sensors can be classified into catalytic combustion sensors, optical sensors, thermal conductivity change sensors, electrochemical sensors, semiconductor gas sensors, and the like according to the principle. Electrochemical and chemiresistive H ₂ sensors are considered currently the most advanced H ₂ sensor technology. (ACSNano 2020,14,11,14284-14322) to test the sample performance parameters of the sensor is a key factor in advancing the hydrogen sensor experiments.

In the application of the existing hydrogen sensor testing device, patent CN114414044a proposes a testing device with both the characteristics of testing photosensitivity and hydrogen sensitivity, which is simple to operate, and the user can quickly complete the test. Patent CN116678997a introduces a multifunctional hydrogen sensor evaluation testing device, which not only can perform temperature and humidity control, but also can test interference/toxic gas, patent CN218350223U invents a testing device capable of obtaining an accurate gas sensor response value, patent CN218727057U discloses a hydrogen sensor testing device for preparing hydrogen by using ammonia gas in a testing cavity, which is convenient and fast, can improve testing efficiency, can test anti-interference capability and false alarm prevention capability simultaneously, and has more reliable and comprehensive results. However, the above test device still has the problems of complex structure, difficult instrument construction and the like, and the test result is not comprehensive enough.

Disclosure of utility model

In order to solve at least one of the problems existing in the prior art, the utility model provides a device for testing the gas-sensitive characteristic of a hydrogen sensor, which can detect the gas-sensitive characteristic of a material capable of measuring the change of the hydrogen concentration, and has the advantages of simple structure, convenient operation and high sensitivity.

In order to realize the aim of the utility model, the utility model provides a testing device for the gas-sensitive characteristic of a hydrogen sensor, which comprises a gas distribution instrument, a tube furnace, a digital source meter and a computer,

The gas distribution instrument is used for mixing the dilution gas and the hydrogen;

The gas outlet of the gas distribution instrument is communicated with the tube furnace, mixed gas is introduced into a testing cavity of the tube furnace, air for recovering resistance is introduced into the testing cavity of the tube furnace through the same pipeline, and a test sample wafer to be detected is arranged in the testing cavity;

The digital source table is used for being connected with the test sample wafer through a wire, and the digital source table is connected with a computer.

Further, the diluent gas is nitrogen or argon.

Further, a sealing plug is arranged on the tube furnace, a wire guide hole is formed in the sealing plug, and a wire connected with a to-be-detected test sample sheet extends out of the tube furnace from the wire guide hole and then is connected with a digital source meter.

Further, the digital source meter is connected to the test coupon to be tested by four insulated test wires, and the resistance of the coupon is measured by four-wire method.

Further, the to-be-detected test sample wafer comprises a titanium wafer substrate, a titanium dioxide film, interdigital electrodes and conductive silver colloid, wherein the titanium dioxide film is wrapped on the titanium wafer, the interdigital electrodes are positioned above the titanium dioxide film, and the conductive silver colloid points are arranged at two ends of the interdigital electrodes.

Further, the hydrogen gas is 1% hydrogen gas.

Further, the device also comprises a hydrogen bottle and a dilution gas bottle, wherein the hydrogen bottle and the dilution gas bottle are respectively communicated with the gas distribution instrument.

Further, the anti-explosion gas tank is further included, and the hydrogen cylinder and the dilution gas cylinder are stored in the anti-explosion gas tank.

Further, a mass flow controller is included for controlling the flow rates of the hydrogen and diluent gases to the gas distribution apparatus.

The pipeline comprises a hose from an air bottle and a hydrogen bottle to a valve, an inlet at one end of the three-way valve is connected to a gas distribution instrument filled with hydrogen diluted by nitrogen, an inlet at the other end of the three-way valve is connected to air, and an output end of the three-way valve is a tube furnace test cavity.

Further, the nitrogen is introduced into the air inlet A of the air distribution instrument, the hydrogen is introduced into the air inlet B, and the maximum dilution ratio of the air distribution instrument is 1:1000, so that the controllable hydrogen concentration range is 10-10000ppm.

Further, the left end flange of the tube furnace is provided with a hole for the copper wire to pass out, and the sealing plug can prevent the gas in the test cavity from leaking greatly.

The pipeline sources are provided with pressure reducing valves, and the centers of the pipeline sources are provided with control valves.

The nuts and the sealing joints of the gas pipeline are provided with rubber sealing rings, and all the sealing rings are in bayonet connection with the flange.

Compared with the prior art, the utility model at least has the following beneficial effects:

The application provides a hydrogen sensor testing device with simple structure connection, convenient operation and high sensitivity, which can test the gas sensitivity of the test sample by introducing hydrogen to reduce the resistance of the test sample and introducing air to increase the resistance of the test sample, and can facilitate the subsequent acquisition of the sensitivity, response time, minimum detection limit, response mode and the like of the hydrogen sensor, so that the performance index of the obtained hydrogen sensor is more comprehensive.

Drawings

The utility model will be further described with reference to the drawings and examples.

Fig. 1 is a schematic structural diagram of a testing device for gas sensitivity of a hydrogen sensor according to an embodiment of the present utility model.

FIG. 2 is a schematic diagram of the structural composition of a Keithley 2450 digital source table.

Fig. 3 is a schematic structural diagram of a gas distribution instrument.

Fig. 4 is a schematic structural diagram of an explosion-proof gas holder.

Fig. 5 is a schematic diagram of the structural composition of a digital source table.

FIG. 6 is a schematic diagram of the circuit components of a four-wire connection of a digital source meter.

Fig. 7 is a schematic structural diagram of a mask plate.

Fig. 8 is a schematic diagram of the back structure of the gas distribution apparatus.

Fig. 9 is a schematic view of a flange structure of a tube furnace.

Fig. 10 is a schematic view of a sealing plastic gasket.

Fig. 11 is a schematic diagram of an air path system in an embodiment of the utility model.

In the figure: 1. computer, 2.USB cable, 3.Keithley 2450 digital source meter, 4. Insulated cable, 5. Tube furnace flange, 6. Tube furnace, 7. Plastic piping, 8. Gas distributor, 9. Steel piping, 10. Explosion proof gas cabinet, 11. Hydrogen bottle, 12. Dilution gas bottle, 13. Dilution gas pipe, 14. Hydrogen pipe, 15. Mixed gas pipe (delivering hydrogen and nitrogen mixture), 16. Three-way valve port a, 17. Three-way valve port c, 18. Three-way valve port b, 19. Gas outlet.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Referring to fig. 1, the device for testing the gas sensitivity of a hydrogen sensor provided by the utility model comprises an explosion-proof gas holder 10, a mass flow controller, a gas distribution instrument 8, a tube furnace 6, a digital source table 3 and a computer 1. The explosion-proof gas holder 10 and the gas distribution instrument 8 are connected with the previous gas distribution instrument 8 through a steel pipeline 9, diluent gas and hydrogen gas are introduced into the previous gas distribution instrument 8, the gas distribution instrument 8 and the tubular furnace 6 are connected with the previous tubular furnace 6 through a plastic pipeline 7, the tubular furnace 6 comprises a test cavity, a test sample to be detected is arranged in the test cavity, the test sample is connected with the digital source meter 3 through copper wires, the digital source meter 3 is connected with the computer 1 through a USB cable 2, and a test system of the digital source meter 3 is regulated through KICKSTART software on the computer 1; the test piece to be detected is arranged in the test cavity, and air for recovering the resistance of the test piece can be introduced into the test cavity of the tube furnace 6.

The gas distribution instrument 8 comprises a mass flow controller, an air inlet A, an air inlet B, a power switch, a control panel and an air outlet, wherein diluting gas is introduced through the air inlet A, hydrogen is introduced through the air inlet B, and the concentration of the hydrogen is diluted by the diluting gas. After the diluted gas and the hydrogen are mixed in the gas distributing instrument 8, the hydrogen with preset concentration is output to the tubular furnace 6 through the gas outlet.

In some embodiments of the utility model, the diluent gas is nitrogen. Of course, in other embodiments, other gases, such as argon, may be used.

In some embodiments of the utility model, the hydrogen gas introduced is 1% hydrogen gas.

In some embodiments of the present utility model, as shown in fig. 11, the explosion proof gas tank 10 stores nitrogen gas and hydrogen gas cylinders, and the gas inlet hole a of the gas distributor 8 is connected to the dilution gas cylinder 12 through the dilution gas pipe 13, and the gas inlet hole B is connected to the hydrogen gas cylinder 11 through the hydrogen gas pipe 14 and the two-way valve. The related pipeline systems are all connected by clamping sleeves and hoses.

The compressed air is compressed by an air compressor, and water, oil and other impurities are filtered out by an air compressor air source dryer.

In some embodiments of the present utility model, the input of dilution gas and hydrogen in the gas distributor 8 is controlled by a mass flow controller to control the output hydrogen concentration. Table 1 shows that the gas distribution instrument 8 dilutes the gas and the hydrogen is introduced at a rate of 1:1000 when the preset hydrogen concentration is obtained, and the controllable hydrogen concentration range is 10-10000ppm.

TABLE 1

Sequence number	Output Hydrogen concentration (ppm)	Hydrogen rate	Nitrogen rate
				1	10000	120sccm	0slm
2	3000	120sccm	0.28slm
				3	1000	111.111 sccm	1slm
4	500	52.6 sccm	1slm
				5	100	10.1sccm	1slm
6	10	1 sccm	1slm

The tube furnace 6 comprises a test cavity, a thermocouple, a left flange, a right flange, an air inlet hole arranged on the left flange, an air outlet hole arranged at the left flange and the right flange, a pressure gauge, an intelligent regulator, an insulating layer, a tube plug, a cavity cover and a sealing ring, wherein the air inlet hole on the tube furnace 6 is communicated with the air outlet hole of the air distribution instrument 8, and the test cavity of the tube furnace 6 is filled with hydrogen with preset concentration. Hydrogen is introduced into the test cavity of the tube furnace 6 from the left flange, the resistance is reduced after the hydrogen contacts the test sample to be detected, and residual air is introduced from the air outlet holes of the left flange and the right flange and controlled by a valve.

In some embodiments of the utility model, a plastic sealing plug is arranged on the left flange of the tube furnace 6, two wire holes are formed in the plastic sealing plug, and wires connected with the to-be-detected test sample sheet extend out of the wire holes and then are connected with the digital source meter 3, so that real-time resistance change of the test sample sheet is obtained.

In some embodiments of the present utility model, as shown in fig. 11, the three-way valve further comprises a three-way valve comprising a three-way valve a port 16, a three-way valve c port 17 and a three-way valve b port 18, wherein the three-way valve a port 16 is connected to an air compressor, and the air compressor compresses air and then filters the air to the three-way valve a port 16. The gas outlet 19 in the gas distribution instrument 8 is connected with the b port 18 of the tee joint through the mixed gas pipeline 15, the c port 17 of the tee joint valve is connected to a sealed test cavity of the tubular furnace 6, when the tee joint valve is broken up, the hydrogen-nitrogen mixed gas with preset concentration is output to the tubular furnace 6, when the tee joint valve is positioned at the middle position, any gas is not led out, and when the tee joint valve is broken down, the air is output to the tubular furnace.

The connectors of the valve train instrument and the pipeline, such as nuts, two-way valves, three-way valves and the like are all 316L materials.

The digital source table 3 comprises a front panel, a rear panel, a power line, a touch screen display, four insulation test wires, a USB connecting wire and a 2450SourceMeter main body, wherein the test is mainly connected to a test sample wafer through the front panel by a four-wire method, and four connecting holes are respectively formed in the test sample wafer: the Sense HI, force HI, senseLo, force Lo are connected to the resistor (test piece) being measured by four insulated test wires, four wire measurement eliminating the resistance of the test wire under measurement.

In some embodiments of the present utility model, the digital source table 3 employs keithley 2450 digital source tables.

In some embodiments of the utility model, the test sample wafer to be detected comprises a titanium wafer substrate, a titanium dioxide film, interdigital electrodes made of platinum and conductive silver colloid, wherein the titanium dioxide film is wrapped on the titanium wafer through a Micro Arc Oxidation (MAO) process, the interdigital electrodes are sputtered above the titanium dioxide film through a mask plate, and the conductive silver colloid is dotted at two ends of the interdigital electrodes.

The test sample wafer is placed in the central position in the test cavity of the tube furnace 6, the copper clamp is clamped on the conductive silver adhesive at the two ends of the test sample wafer, the copper wire is welded on the copper clamp, the flange and the tube furnace main body are connected through the rubber ring gasket, the copper wire penetrates out of two holes in the left flange plastic sealing plug to be connected to the digital source meter 3, the left flange and the right flange are respectively provided with an air outlet which can be controlled by a valve, the right flange is plugged into the tube plug, and the resistance of the sample wafer is measured by a four-wire method.

In some embodiments of the utility model, the main body of the test cavity of the tube furnace 6 is a furnace tube, the diameter is 5cm, the length is 60cm, the material is a quartz tube, the hearth material is alumina fiber, the sealing ring is high-temperature silica gel, the flange is 304L stainless steel, and the heating element of the high-temperature furnace is an alloy resistance wire: the positive electrode of the thermocouple is nickel-chromium alloy (KP) containing 10% of chromium, the negative electrode of the thermocouple is nickel-silicon alloy (KN) containing 3% of silicon, and the pipe plug is foamed ceramic. The insulated wire matched with the digital source meter 3 is Keithley Instruments 8608 type high-performance clamp type wire suite, the length is 120cm, the digital source meter 3 comprises a 15cm needle type test meter pen, and a new safety wire with the inner diameter of a jack of 5.5mm and the outer diameter of 8.6mm is arranged. The test sample piece is made of pure titanium, and is changed into niobium doped titanium dioxide after micro-arc oxidation, the number of the interdigital electrodes is 7, the interdigital gap is 0.5mm, and the side length is 13.5cm.

The invention uses the testing device of the gas sensitivity characteristic of the hydrogen sensor provided by the previous embodiment to test, and comprises the following steps;

manufacturing a test sample to be detected;

The manufacturing steps are the existing steps, the application does not relate to improvement of the sample wafer manufacturing steps, firstly, a pure titanium sheet is sequentially polished by 200#, 400#, 600#, 800# abrasive paper, a surface oxide layer and impurities are removed, a sample is subjected to Micro Arc Oxidation (MAO) doping to oxidize the pure titanium into titanium dioxide, metal spraying is carried out on the titanium dioxide through a mask plate, interdigital electrodes are obtained, two points of silver colloid are respectively coated on positive and negative poles of the electrodes, and the silver colloid is taken out after drying in an oven for 30 minutes.

Fixing a sample: and welding wires on the copper clamps, respectively clamping the copper clamps of the positive electrode and the negative electrode on two ends of the interdigital electrode, leading out the wires from the plastic sealing plug holes of the through holes of the left flange, and connecting the wires to the digital source meter by a four-wire method.

Test sample: the digital source meter is used for measuring the resistance of the test sample, when the resistance R is less than 1MPa and has obvious resistance change reaction to hydrogen and air (for example, when the resistance is reduced when hydrogen is introduced and the resistance is increased when air is introduced, and the sensitivity S _F＝R_a-R_g/R_a is more than 10 percent, the test sample can be judged to have obvious resistance change, R _g is the resistance of the test sample after hydrogen is introduced, R _a is the resistance of the test sample when air is introduced), the test sample is qualified, otherwise, the test sample is unqualified, the relative positions of the copper clamp and the silver colloid are re-adjusted and then are measured again until the resistance change is qualified, and if the resistance change is always unqualified, the test sample is judged to be a failure sample.

Experiment preparation: the flange cavity cover is covered, and the test software KICKSTART, the digital source meter, the gas distribution instrument, the hydrogen, air, nitrogen gas switch and the pressure reducing valve of the computer 1 are opened.

Gas-sensitive test: after the experiment is ready, the gas-sensitive test is carried out, the three-way valve is shifted to the middle position to enable the gas to not circulate any more, whether the needed gas such as hydrogen and nitrogen is opened or not is checked, the output/scanning point of a test software source is set, an application program is operated, the visual angle is switched to a graph, X is changed to time, Y is changed to resistance, after the initial resistance is stabilized at a certain value (such as the fluctuation amplitude of the resistance is within 10% of the total resistance), the data change curve of the resistance of the test sample is observed and recorded, the hydrogen is regulated to the needed concentration through the gas distributor, firstly 10000ppm (4% is the explosion lower limit) of the maximum concentration source gas is introduced into the universal working temperature (such as 150 ℃) of the TiO ₂ hydrogen sensor, the sensor needs to measure the concentration which is far lower than the explosion lower limit, 1% is the maximum concentration gas during the test, and the other concentrations are all diluted concentrations after the nitrogen doping is changed to the lowest value, all irreversible reactions are completed, then the air is introduced into the original resistance of the test sample is observed, if the original resistance can be returned to the level, the sensor has the repeatability, the repeatability is different from the repeated operation or the hydrogen pollution is required to be detected, the hydrogen is the same with the repeatability or the hydrogen pollution is detected when the hydrogen is the repeatability is the upper limit or the hydrogen is the hydrogen pollution is detected and the hydrogen is the test. And stopping the software application program and deriving data until the gas-sensitive test of all the preset hydrogen concentration is completed.

The testing device provided in the foregoing embodiment can rapidly change the gas type by adjusting the valve of the three-way valve, when the test sample (sensor) is placed in the air, the resistance is R _a, the resistance is reduced to R _g after hydrogen is introduced, the responsiveness is S _r＝R_a/R_g, and the sensitivity is S _F＝(R_a-R_g)/R_a ×100%. The time from the high resistance state to the low resistance state and the exact resistance of the sensor are recorded, and the response time t _res is the time required for the resistance to drop by 90% after the sensor is exposed to a hydrogen atmosphere. The air of the recovery resistor is directly obtained from the air by a compressed air machine, and the air containing impurities is filtered and then is introduced into the tube furnace through a pipeline system. The time required for the resistance value to reach 90% full recovery after the sensor is out of the hydrogen-containing atmosphere is the recovery time (t _rec). The hydrogen concentration is gradually decreased, and the lowest concentration to which the sensor can respond can be observed, so that the detection Limit (LOD) of the sensor (the detection Limit (LOD) is the lowest gas concentration value that the sensor can effectively detect) can be known.

The device provided by the utility model does not relate to improvement of the method.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that it will be apparent to those skilled in the art that modifications and variations can be made without departing from the technical principles of the present utility model, and these modifications and variations should also be regarded as the scope of the utility model.

Claims

1. The device for testing the gas sensitivity characteristic of the hydrogen sensor is characterized by comprising a gas distribution instrument (8), a tube furnace (6), a digital source meter (3) and a computer (1),

The gas distribution instrument (8) is used for mixing the dilution gas and the hydrogen;

The air outlet of the air distribution instrument (8) is communicated with the tube furnace (6), mixed gas is introduced into a test cavity of the tube furnace (6), air for recovering resistance is introduced into the test cavity of the tube furnace (6) through the same pipeline, and a test sample to be detected can be placed in the test cavity;

The digital source table (3) is used for being connected with the test sample wafer through wires, and the digital source table (3) is connected with the computer (1).

2. The device for testing the gas-sensitive property of a hydrogen sensor according to claim 1, wherein the diluent gas is nitrogen or argon.

3. The device for testing the gas-sensitive characteristic of the hydrogen sensor according to claim 1, wherein a sealing plug is arranged on the tube furnace (6), a wire hole is arranged on the sealing plug, and a wire connected with a test sample to be tested is connected with the digital source meter (3) after extending out of the tube furnace (6) from the wire hole.

4. A device for testing the gas-sensitive properties of a hydrogen sensor according to claim 1, characterized in that the digital source meter (3) is connected to the test coupon to be tested by four insulated test wires.

5. The device for testing the gas-sensitive characteristic of a hydrogen sensor according to claim 1, wherein the test sample to be tested comprises a titanium sheet substrate, a titanium dioxide film, an interdigital electrode and conductive silver paste, wherein the titanium dioxide film is wrapped on the titanium sheet, the interdigital electrode is positioned above the titanium dioxide film, and the conductive silver paste is positioned at two ends of the interdigital electrode.

6. The device for testing the gas-sensitive properties of a hydrogen sensor of claim 1, wherein the hydrogen is 1% hydrogen.

7. A device for testing the gas sensitivity characteristics of a hydrogen sensor according to any one of claims 1 to 6, further comprising a hydrogen cylinder (11) and a dilution gas cylinder (12), the hydrogen cylinder (11) and the dilution gas cylinder (12) being in communication with the gas distribution instrument (8), respectively.

8. The device for testing the gas sensitivity characteristics of a hydrogen sensor according to claim 7, further comprising an explosion proof gas tank (10), wherein the hydrogen cylinder (11) and the dilution gas cylinder (12) are stored in the explosion proof gas tank (10).

9. The device for testing the gas-sensitive properties of a hydrogen sensor according to claim 7, further comprising a mass flow controller for controlling the flow rates of the hydrogen gas and the diluent gas introduced into the gas distribution instrument (8).

10. The device for testing the gas sensitivity characteristics of a hydrogen sensor according to claim 7, further comprising a three-way valve, wherein the three-way valve comprises a three-way valve a port (16), a three-way valve c port (17) and a three-way valve b port (18), the three-way valve a port (16) is connected to air, an air outlet (19) of the air distribution instrument (8) is connected with the three-way valve b port (18), and the three-way valve c port (17) is connected with the tube furnace (6) to control the mixed gas or air to be introduced into the tube furnace (6).