TWI454694B - Gas detecting device, gas detecting system and method for manufacturing gas detecting device - Google Patents

Description

Manufacturer of gas detecting device, gas detecting system and gas detecting device law

The present invention relates to the field of detection devices, and more particularly to a gas detection device for gas detection, a gas detection system, and a method for fabricating the gas detection device.

With the rapid development of industries such as heavy industry, textile industry, plastics and chemicals, people's living needs have been met, and at the same time, many people's health gases have been produced. Many of these gases, such as formaldehyde and carbon monoxide, are odorless and tasteless, causing people to be harmed unconsciously and the environment is polluted. Therefore, a sensor having a sensing harmful gas is produced and widely used. Please refer to the literature ZnO Nanotip-based QCM Biosensors, Zheng Zhang; Hanhong Chen; Jian Zhong; Ying Chen; Yicheng Lu; International Frequency Control Symposium and Exposition, 2006 IEEE, June 2006 Page(s): 545-549.

However, current gas detection systems suffer from problems of low sensitivity, poor selectivity, poor stability, or inability to be used for long periods of time, causing errors in gas detection.

In view of the above, it is necessary to provide a gas detecting device, a gas detecting system, and a method for producing the gas detecting device with high sensitivity and stability.

Hereinafter, a gas detecting device, a gas detecting system, and a method of manufacturing the gas detecting device will be described by way of embodiments.

A gas detecting device comprising a quartz plate, a first electrode, a second electrode, a first active layer and an adsorption layer, the quartz plate having opposite first and second surfaces, the first electrode being formed on the The first surface is formed on the second surface, the first active layer is formed on the surface of the first electrode, and the material of the first active layer is copper oxide for activating the adsorption layer. The adsorption layer is formed on a surface of the first activation layer, and the adsorption layer is composed of a cerium-cerium oxide nanorod, and the adsorption layer is used for adsorbing a gas to be detected, so that the weight of the gas detecting device is changed, thereby obtaining The concentration of the gas to be detected.

A gas detecting system includes: the gas detecting device for adsorbing a gas to change a weight of the gas detecting device to change a frequency of the oscillation; and a detecting chamber for placing the gas detecting device and for passing a gas to be detected, so that the gas detecting device adsorbs the gas to be detected; a frequency detecting device connected to the first electrode and the second electrode for detecting an oscillation frequency of the gas detecting device according to an oscillation frequency of the gas detecting device The change obtains the concentration of the gas to be detected.

A method for fabricating a gas detecting device includes: a method for fabricating a gas detecting device, comprising: providing a quartz plate having a first surface and a second surface opposite to each other; forming a first surface on the first surface of the quartz plate An electrode is disposed on the second surface of the second surface of the quartz plate; forming a first active layer on the surface of the first electrode by chemical vapor deposition, the material of the first active layer is copper oxide; Forming a ceria nanorod layer by metal organic chemical vapor deposition on the surface of the layer; reducing a portion of the ceria in the ceria nanorod layer at a high temperature to form a barium-niobium oxide nanorod The layer is adsorbed to obtain a gas detecting device.

The gas detecting system and the gas detecting device in the technical solution utilize an anti-piezoelectric effect of a quartz crystal, and an adsorption layer and a first active layer are formed on a surface of the quartz plate, and the adsorption layer is composed of a bismuth-niobium oxide nanorod. The first activation layer is composed of copper oxide. The first activation layer activates the adsorption layer during the process of adsorbing gas, and the weight of the gas detection device changes after the adsorption layer adsorbs the gas, thereby causing the oscillation frequency of the gas detection device to occur. By changing, the frequency detecting means measures the change in the frequency of the gas detecting means, and by calculating the processing, the concentration of the gas to be detected can be detected. Therefore, the gas detecting device and the gas detecting system of the present technical solution have high sensitivity. The method for manufacturing the gas detecting device provided by the technical solution has the characteristics of being simple, convenient and easy to control.

100, 200, 320‧‧‧ gas detection devices

110‧‧‧Quartz plate

111‧‧‧ first surface

112‧‧‧ second surface

121, 221‧‧‧ first electrode

1211‧‧‧First electrode body

1212‧‧‧First Extension

122, 222‧‧‧ second electrode

1221‧‧‧Second electrode body

1222‧‧‧Second extension

130, 231‧‧‧ first activation layer

140‧‧‧Adsorption layer

150, 242‧‧‧ second activation layer

241‧‧‧First adsorption layer

232‧‧‧ third activation layer

242‧‧‧Second adsorption layer

252‧‧‧4th activation layer

300‧‧‧Gas detection system

310‧‧‧Test room

311‧‧‧ top wall

312‧‧‧ bottom wall

313‧‧‧ side wall

314‧‧‧Detection chamber

315‧‧‧Inlet

316‧‧‧ venting holes

317‧‧‧Insulation

318‧‧‧heating plate

319‧‧‧Support column

330‧‧‧ Frequency detection device

340‧‧‧ processor

1 is a schematic view of a gas detecting device provided by a first embodiment of the present technical solution.

Figure 2 is a schematic cross-sectional view taken along line II-II of Figure 1.

Figure 3 is a schematic cross-sectional view taken along line III-III of Figure 1.

Figure 4 is a schematic cross-sectional view of a scanning electron microscope of a gas detecting device.

FIG. 5 is a schematic diagram of a gas detecting device provided by a second embodiment of the present technical solution.

6 is a schematic diagram of a gas detection system provided by the technical solution.

The gas detecting device, the gas detecting system and the method for manufacturing the gas detecting device provided by the technical solution are further described below with reference to the accompanying drawings and the plurality of embodiments.

Referring to FIGS. 1 and 2 together, the gas detecting device 100 includes a quartz plate 110, a first electrode 121, a second electrode 122, a first active layer 130, an adsorption layer 140, and a second active layer 150.

The quartz plate 110 is made of a quartz crystal for use as a plating substrate on which the first electrode 121, the second electrode 122, the first active layer 130, the adsorption layer 140, and the second active layer 150 are formed. The quartz plate 110 may have a rectangular parallelepiped shape or a cylindrical shape. In this embodiment, the quartz plate 110 is cylindrical and has a first surface 111 and a second surface 112 opposite thereto. The first surface 111 and the second surface 112 are both circular planes. The quartz plate 110 has an anti-piezoelectric effect, that is, an electric field is applied thereto, and strain occurs in some directions of the crystal. If the electric field is an alternating electric field, mechanical oscillation is caused in the crystal lattice, and the frequency of the mechanical oscillation is generated. It is equal to the frequency of the applied alternating electric field. Therefore, the initial oscillation frequency of the quartz crystal can be obtained by applying a certain frequency alternating electric field to the piezoelectric quartz crystal. In addition, when the weight of the quartz piezoelectric crystal changes, that is, when the surface of the quartz piezoelectric crystal is adsorbed or tightly bonded to other objects, the frequency of the quartz crystal oscillation changes, and the frequency changes and the weight of the object adsorbed on the surface of the quartz crystal. Follow the relationship below (Sauerbery, 1959):

Where Δ f is the oscillation frequency change value corresponding to the weight Δ m (g), f ₀ is the reference frequency, and AQCM is the electrode surface area (cm 2 ).

The first electrode 121 and the second electrode 122 are used to connect the gas detecting device 100 with an external frequency detecting device to detect the frequency of the gas detecting device 100. The first electrode 121 includes a first electrode body 1211 and a first extension portion 1212. The first electrode body 1211 is formed on the first surface 111 of the quartz plate 110 and covers the center of the first surface 111. The first extending portion 1212 is integrally formed with the first electrode body 1211 and extends to the edge of the first surface 111 to facilitate other circuit connection of the first electrode body 1211. . The second electrode 122 includes a second electrode body 1221 and a second extension portion 1222. The second electrode body 122 is formed on the second surface 112 of the quartz plate 110, and is disposed opposite to the first electrode body 1211 at a central position covering the second surface 112. The second extension portion 1222 is integrally formed with the second electrode body 1221 and extends to the edge of the second surface 111 to facilitate other circuit connection of the second electrode body 1221. The first electrode body 1211 and the second electrode body 1221 are both circular, and the diameter thereof can be set according to the size of the quartz plate 110. In the embodiment, the diameters of the first electrode body 1211 and the second electrode body 1221 are 0.38 cm. The thickness of the first electrode body 1211 and the second electrode body 1221 is 0.05 μm to 1 μm, preferably 0.1 μm to 0.3 μm. The first electrode 121 and the second electrode 122 are both made of gold, and of course, may be made of a metal such as silver or platinum. The first electrode 121 and the second electrode 122 may be formed on the first surface 111 and the second surface 112 of the quartz plate 110 by sputtering.

The first active layer 130 is formed on the entire surface of the first electrode 121. The first active layer 130 is composed of copper oxide. The first activation layer 130 is used to activate the subsequently fabricated adsorption layer 140. The first active layer 130 has a thickness of 10 nm to 20 nm.

Referring to FIG. 4, an adsorption layer 140 is formed on the first activation layer 130 for adsorbing the gas to be detected. The adsorption layer 140 is composed of a cerium-niobium oxide nanorod (Ir-IrO2nanorods). The thickness of the adsorption layer 140 is between 100 nm and 2 microns, preferably between 400 nm and 600 nm. The adsorption layer 140 is formed by metal organic chemical vapor deposition metal organic chemical vapor deposition to form a ruthenium dioxide nanorod layer, and then the ruthenium dioxide is reduced at a high temperature to form a ruthenium-ruthenium dioxide nanorod layer. The adsorption layer 140 has a loose structure. In addition, the adsorption of acid gas by the cerium-cerium oxide nanorod forms an active surface with Ir-OH, and the adsorption of acid gas by the cerium-cerium oxide nanorod forms an activity of Ir-NH. surface. Thereby, the adsorption layer 140 has adsorption to acid gases and amine gases. characteristic. When the acid gas or the amine gas passes through the adsorption layer 140, it is absorbed by the adsorption layer 140.

The second active layer 150 is formed on the adsorption layer 140. The second active layer 150 is also composed of copper oxide and has a thickness of 10 nm to 20 nm. The second active layer 150 is also used to activate the adsorption layer 150, and when the gas is detected, the detection gas is adsorbed together with the adsorption layer 140.

The first active layer 130 and the second active layer 150 are both adjacent to the adsorption layer 140. The copper in the copper oxide in the first active layer 130 and the second active layer 150 is easily oxidized in the adsorption layer 140 adjacent thereto. The enthalpy action, the combination of copper and oxygen in the cerium oxide, causes lattice vacancies in the cerium oxide, thereby increasing the ability of the adsorption layer 140 to adsorb gas during gas adsorption, thereby making the sensitivity of the gas detecting device 100 improve.

Referring to FIG. 5, the gas detecting device 200 according to the second embodiment of the present invention has a structure similar to that of the gas detecting device 100 provided in the first embodiment, except that the first electrode 221 of the gas detecting device 200 is different. A first activation layer 231 is formed on the surface, a first adsorption layer 241 is formed on the first activation layer 231, and a second activation layer 251 is formed on the first adsorption layer 241. A third activation layer 232 is also formed on the surface of the second electrode 222. The second adsorption layer 242 is formed on the third activation layer 232, and the fourth activation layer 252 is formed on the second adsorption layer 242.

In this embodiment, the surfaces of the first electrode 221 and the second electrode 222 are each formed with an adsorption layer, which can improve the signal intensity when the gas detecting device 200 detects the gas, and the gas detecting device 200 has high sensitivity.

A third embodiment of the present technical solution provides a method of manufacturing a gas detecting device, The gas detecting device 100 in the first embodiment will be described as an example. Referring to FIG. 2, the manufacturing method of the gas detecting device 100 includes the following steps:

In a first step, a quartz plate 110 is provided having a first surface 111 and a second surface 112 opposite thereto.

In the second step, the first electrode 121 is formed on the first surface 111 of the quartz plate 110, and the second electrode 122 is formed on the second surface 112 of the quartz plate 110. First, the region where the first surface 111 of the quartz plate 110 does not need to form the first electrode 121 and the region where the second surface 112 does not need to form the second electrode 122 are shielded by a masking film. Then, the first electrode 121 and the second electrode 122 are formed in a region where the quartz plate 110 is not shielded by sputtering.

In the third step, the first active layer 130 is formed on the surface of the first electrode 121. First, the entire surface of the second electrode 122 is shielded to prevent the copper oxide layer from being formed on the surface of the second electrode 122 when the first active layer 130 is subsequently formed. Then, the shielded quartz plate 110 is placed on the brass substrate in the chemical vapor deposition reaction chamber such that the masking film of the second electrode 122 is in contact with the brass substrate, and the first electrode 121 is exposed to the reaction chamber. Finally, the temperature of the brass substrate is raised to 350 degrees Celsius, and the reaction gas oxygen is introduced into the reaction chamber. The volume flow rate of oxygen is 80 to 100 standard milliliters per minute, and the vacuum in the reaction chamber is less than 1 Pa. The time is 10 minutes. Under this condition, the copper oxide vapor generated by the reaction of oxygen and brass diffuses to the surface of the first electrode 121, thereby forming the first active layer 130.

In the fourth step, a thin film of ruthenium dioxide nanorods is formed on the surface of the first active layer 130. The cerium oxide nanorods are prepared by metal organic chemical vapor deposition metal organic chemical vapor deposition. The reaction gas oxygen was continuously introduced into the reaction chamber at a volume flow rate of 100 standard milliliters per minute, and the temperature in the reaction chamber was maintained at 350 degrees Celsius. Passing into the reaction chamber The precursor is (methylcyclopentadiyne) (1,5 cyclooctadiene) ruthenium gas, and the temperature at which the precursor is volatilized is from 80 degrees Celsius to 120 degrees Celsius. The vapor and oxygen of the precursor before the volatilization in the reaction chamber reach the surface of the reduction layer and react, so that a film of the ruthenium dioxide nanorod is formed on the surface of the first activation layer 130. The degree of vacuum in the reaction chamber during the reaction was from 7.1 to 7.3 torr. In this embodiment, the deposition time of the ruthenium dioxide nanorod film is 1 hour.

In the fifth step, a second activation layer 150 is formed on the surface of the ruthenium dioxide nanorod film.

The introduction of the precursor gas into the reaction chamber is stopped, and the oxygen gas is continuously supplied for 10 minutes, so that the surface of the ruthenium dioxide nanorod film forms a second activation layer 150 composed of copper oxide.

In the sixth step, a portion of the cerium oxide in the cerium oxide nanorod film is reduced at a high temperature to form an adsorption layer 140 composed of a cerium-cerium oxide nanorod. The reaction gas oxygen was stopped, and the temperature in the reaction chamber was 500 to 600 ° C. The vacuum in the reaction chamber was 5 × 10 -3 Pa, and the reduction time was 1 hour. Part of the oxygen in the cerium oxide layer is removed under this condition, so that part of the cerium oxide nanorod is reduced to cerium, thereby forming the adsorption layer 140 formed of the cerium-niobium dioxide nanorod.

In the seventh step, the masking film is removed to form the gas detecting device 100.

In the manufacturing method of the gas detecting device 100 described above, after the quartz plate 110 is formed and shielded by the first electrode 121 and the second electrode 122, it is only necessary to change the temperature and the degree of vacuum in the reaction chamber, and to pass the gas as needed. Therefore, the quartz plate is not required to be taken out from the reaction chamber. Therefore, the method for manufacturing the gas detecting device provided by the embodiment has the characteristics of being simple, quick, and easy to control.

The technical solution also provides a gas detection system using the above gas detecting device, Hereinafter, a gas detecting system including the gas detecting device provided in the first embodiment will be described as an example.

Referring to FIG. 6, the gas detection system 300 includes a detection chamber 310, a gas detecting device 320, a frequency detecting device 330, and a processor 340. The detection chamber 310 is configured to house the detection gas and gas detecting device 320 such that the gas detecting device 320 detects the gas in the detection chamber 310. The detection chamber 310 is cylindrical and has a top wall 311, a bottom wall 312 and side walls 313. The top wall 311, the bottom wall 312 and the side wall 313 enclose a cylindrical detection chamber 314 for receiving gas. In the embodiment, the air inlet 315 and the exhaust hole 316 are defined in the sidewall 313 of the detection chamber 310. The air inlet 315 is used for injecting gas into the receiving cavity 314, and the exhaust hole 316 is used for discharging the gas in the detecting cavity 314. .

In this embodiment, an insulation layer 317 is disposed around the detection chamber 310. The insulation layer 317 is used to supply a heat source to the top wall 311, the sidewall 313 and the bottom wall 312 of the detection chamber 310, so that the detection chamber 314 maintains a certain temperature. In this embodiment, the water of a certain temperature is accommodated in the heat insulating layer 317, so that the temperature in the detecting chamber 314 is kept stable. In the detection chamber 310, a heating plate 318 is provided for heating the detected liquid to volatilize or decompose to generate a gas. In this embodiment, the heating plate 318 is disposed on the bottom wall 312 by the support column 319.

The first electrode and the second electrode of the gas detecting device 320 are connected to the frequency detecting device 330 by wires passing through the top wall 311 of the detecting chamber 310 to detect the frequency of the gas detecting device 320.

The frequency detecting device 330 is connected to the processor 340, and detects the frequency change of the gas detecting device 320 by the instantaneous observation frequency detecting device 330, and calculates the gas concentration to be detected according to the change of the oscillation frequency of the gas detecting device 320.

The gas detection system 300 performs gas detection. First, the gas detection device 310 reference frequency is measured. The background gas such as nitrogen is injected into the detection chamber 314 through the air inlet 315, and the volume flow rate of the background gas injected may be 10 standard milliliters per minute, so that the nitrogen gas is adsorbed by the gas detecting device 310. The processor 340 observes the change in the frequency value of the display. When the frequency value is stabilized, the reading of the frequency value at this time is recorded as the reference frequency f0. Stop injecting background gas.

Then, the frequency value after the gas detecting device 310 adsorbs the detected gas is detected. In the present embodiment, the description will be made by taking hexylamine as an example. The liquid hexamine is injected into the heating plate 318 of the detecting chamber 314 by using an auxiliary device such as a syringe, and the temperature of the heating plate 318 is controlled to cause the liquid to be volatilized or decomposed, and the insulating layer 317 has a heat insulating effect. The gas produced by the liquid condenses. At the same time, the venting hole 316 is in an open state, so that the detecting liquid is gradually dispersed in the detecting chamber 314, and the background gas can escape from the venting hole 316, and the liquid hexamine is continuously injected into the detecting chamber 314 to generate gas. The concentration of the background gas in the detection chamber 314 is gradually reduced until it is nearly zero, and the gas in the detection chamber 315 is a gas generated by the detection liquid, so that the background gas adsorbed by the gas detecting device 320 is replaced by the detection liquid generating gas. When the frequency of the processor 340 is stabilized, the frequency value is denoted as f1, that is, the frequency at which the gas detecting device 320 absorbs the gas volatilized by the gas and changes its weight. Stop injecting the test liquid.

Finally, the gas detecting device 320 is desorbed. Keeping the exhaust hole 316 in an open state, injecting background gas from the air inlet hole 315 until the concentration of the gas volatilized by the detection liquid in the detection chamber 314 becomes small to be close to zero, so that the concentration of the detection gas adsorbed by the gas detecting device 320 is also close to At zero, the processor 340 displays a reading that is equal or close to the reference frequency.

The processor 340 calculates the concentration of the detected gas based on the difference between the detected f1 and f0. In this embodiment, the difference between the detection frequency f1 and the reference frequency f0 after adsorption is up to 1970 Hz, and the time from the change of the reference frequency to 80% of the detection frequency f1 after adsorption is only 40 seconds, and the gas detecting device 100 is in the desorption process. The ratio of the frequency of the rise to the frequency of the decrease in the adsorption of hexylamine is 86%. Therefore, in the above detection process, the difference between the fundamental frequency and the frequency after the adsorption of the detection gas is large, indicating that the sensitivity of the gas detection system 320 is higher. The time from the change of the reference frequency to 80% of the post-adsorption detection frequency f1 is short, indicating that the response time of the gas detecting device 320 is short. The smaller the difference between the frequency of the gas detection device rising during the desorption process and the frequency of the decrease during the adsorption of hexylamine, indicating that the gas detection device can be desorbed more completely, indicating that the gas detection device can be reused more often and the life is longer. .

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be covered by the following claims.

100‧‧‧Gas detection device

110‧‧‧Quartz plate

111‧‧‧ first surface

112‧‧‧ second surface

121‧‧‧First electrode

1211‧‧‧First electrode body

1212‧‧‧First Extension

122‧‧‧second electrode

1221‧‧‧Second electrode body

1222‧‧‧Second extension

130‧‧‧First activation layer

140‧‧‧Adsorption layer

150‧‧‧Second activation layer

Claims (13)

A gas detecting device comprising a quartz plate, a first electrode, a second electrode, a first activating layer and an adsorption layer, the quartz plate having a first surface and a second surface opposite to each other, the first electrode being formed in the first a surface, the second electrode is formed on the second surface, the first activation layer is formed on the surface of the first electrode, the material of the first activation layer is copper oxide for activating the adsorption layer, and the adsorption layer is formed on The surface of the first activation layer is composed of a cerium-cerium oxide nanorod for adsorbing the gas to be detected to change the weight of the gas detecting device, thereby obtaining the concentration of the gas to be detected. The gas detecting device according to claim 1, wherein the adsorption layer is further formed on a surface of the second electrode. The gas detecting device according to claim 1, wherein the surface of the adsorption layer is further formed with a second activation layer for enhancing the adsorption activity of the adsorption layer. The gas detecting device according to claim 3, wherein the material of the second active layer is copper oxide. The gas detecting device according to claim 1, wherein the adsorption layer has a thickness of from 100 nm to 2 μm. The gas detecting device according to claim 1, wherein the adsorption layer has a thickness of from 400 nm to 600 nm. The gas detecting device according to claim 1, wherein the first active layer has a thickness of 10 nm to 20 nm. A gas detecting system comprising: the gas detecting device according to any one of claims 1 to 7 for adsorbing a gas to change a weight of the gas detecting device, thereby causing a change in an oscillation frequency thereof; a detection chamber for placing a gas detecting device, and for introducing a gas to be detected, so that the gas detecting device adsorbs the gas to be detected; and a frequency detecting device connected to the first electrode and the second electrode of the gas detecting device, It is used for detecting the oscillation frequency of the gas detecting device to obtain the concentration of the gas to be detected according to the change of the oscillation frequency of the gas detecting device. The gas detecting system of claim 8, wherein the detecting chamber is further provided with a heating plate for heating the liquid to generate a gas to be detected. The gas detecting system of claim 8, wherein the periphery of the detecting chamber is provided with a heat insulating layer for preventing condensation of the gas to be detected. The gas detecting system of claim 8, wherein the gas detecting system further comprises a processor connected to the frequency detecting device, configured to calculate the gas to be detected according to the change of the oscillation frequency of the gas detecting device. concentration. A method for fabricating a gas detecting device, comprising: providing a quartz plate having a first surface and a second surface; forming a first electrode on the first surface of the quartz plate and a second electrode in the quartz plate Forming a second electrode; forming a first active layer on the surface of the first electrode by chemical vapor deposition, the material of the first active layer is copper oxide; and the surface of the first active layer is made of a metal organic chemical vapor phase Depositing to form a cerium oxide nanorod layer; at the high temperature, a part of the cerium oxide in the cerium oxide nanorod layer is formed to form an adsorption layer formed of a cerium-cerium oxide nanorod, thereby obtaining a gas detecting device. The method for fabricating a gas detecting device according to claim 12, wherein before the high-temperature reduction of a portion of the cerium oxide layer in the cerium oxide nanorod layer, the surface is further formed on the surface of the cerium oxide nanorod layer The step of the second activation layer.