WO2022078028A1 - Formaldehyde gas sensor module - Google Patents

Abstract

A formaldehyde gas sensor module, comprising: a circuit board, a sensitive component used for sensing formaldehyde, a heating component used for enhancing the sensing effect of the sensitive component in low-temperature conditions, an analog circuit used for amplifying and converting a detection signal of the sensitive component, a housing, and a control device. The sensitive component, the heating component, and the analog circuit are provided on the circuit board. The circuit board is provided in the housing. The control device is connected to the sensitive component and to the analog circuit via a first control circuit so as to acquire detection data. The control device is connected to the heating component via a second control circuit so as to control the operation of the heating component. The first control circuit and the second control circuit are provided on the circuit board. The formaldehyde gas sensor module provided in the present invention is capable of sensing and effectively detecting the concentration of formaldehydes in low-temperature conditions, that is, the working temperature of the formaldehyde sensor can be effectively reduced, thus reducing energy consumption, further stabilizing the performance of a formaldehyde sensor, and extending the service life thereof.

Description

A formaldehyde gas sensor module

This application claims the priority of the Chinese patent application filed on October 13, 2020 with the application number 202011090576.3 and the invention titled "A formaldehyde gas sensor module", the entire contents of which are incorporated into this application by reference .

technical field

The invention relates to the technical field of formaldehyde gas detection, and more particularly, to a formaldehyde gas sensor module.

Background technique

Formaldehyde is a colorless, but irritating gas to the eyes and nose of the human body. It is a toxic and harmful substance in indoor air. When the concentration of formaldehyde in indoor air is greater than 0.08mg/ ^m3 , it may cause red eyes, itchy eyes, throat discomfort or pain, hoarseness, sneezing, chest tightness, asthma, dermatitis and other phenomena. However, in newly renovated rooms, decorative materials and furniture will release a large amount of formaldehyde, which makes the indoor formaldehyde content high, which may cause many diseases in the human body. Therefore, effective detection of indoor formaldehyde concentration is required.

In the prior art, a formaldehyde sensor is usually used to detect the indoor formaldehyde concentration in real time, and the formaldehyde sensor mainly includes an electrochemical sensor, an optical sensor, and a photobiochemical sensor. Among them, electrochemical sensors have simple structure, low cost, stable product performance, and the detection range and resolution can basically meet the requirements of indoor environmental detection, but they have the disadvantage of many interfering substances and short working life; optical sensors are expensive and bulky, not suitable for Online real-time analysis, and its performance is unstable and lacks practicability. Optical sensors are expensive and bulky, and are not suitable for on-line real-time analysis; although photobiochemical sensors are highly selected and only respond to a single gas, their performance is unstable due to the stability of enzymes and lacks practicability. Semiconductor sensors are favored by the market due to their simple working principle, short response time, simple fabrication and low cost. Therefore, the most commonly used formaldehyde sensors on the market are semiconductor sensors, but the semiconductor sensor needs to have a significant response to ppm and sub-ppm formaldehyde at a higher working temperature, which makes the semiconductor formaldehyde sensor less accurate.

To sum up, how to provide a semiconductor formaldehyde sensor with low working temperature and high response intensity is a problem to be solved urgently by those skilled in the art at present.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a formaldehyde gas sensor module, which can sense and effectively detect the formaldehyde concentration under low temperature conditions, that is, the working temperature of the formaldehyde sensor can be effectively reduced, energy consumption can be reduced, and the performance of the formaldehyde sensor can be improved. More stable and longer service life.

In order to achieve the above object, the present invention provides the following technical solutions:

A formaldehyde gas sensor module, comprising: a circuit board, a sensitive element for sensing formaldehyde, a heating element for enhancing the sensing effect of the sensitive element under low temperature conditions, and a detection for amplifying and converting the sensitive element Signal analog circuit, a housing for fixing the circuit board, and a control device, the sensitive element, the heating element and the analog circuit are all arranged on the circuit board, and the circuit board is arranged on the inside the shell;

The control device is connected with the sensitive element and the analog circuit through a first control circuit to obtain detection data, and the control device is connected with the heating element through a second control circuit to control the operation of the heating element, Both the first control circuit and the second control circuit are provided on the circuit board.

Preferably, the sensitive element is a porous TiO ₂ nanomaterial, and the heating element is an ultraviolet lamp.

Preferably, the preparation method of the TiO ₂ nanomaterial includes:

S1: dissolve the porous _TiO2 nanotube powder in terpineol;

S2: Utilize the _TiO nanotube powder dissolved by ultrasonic vibration to make a solvent, and the dissolution time is 10min-40min;

S3: take an appropriate amount of the solvent and evenly apply it on the interdigital electrodes;

S4: performing two high-temperature firings on the interdigital electrodes;

S5: Fix the fired interdigital electrodes on the Al ₂ O ₃ substrate.

Preferably, the S4 includes,

S41: the interdigital electrode is raised from normal temperature to 150°C-200°C at a speed of 3°C/min-5°C/min, kept for 2h-3h and then cooled to normal temperature;

S42: The interdigital electrode is raised from normal temperature to 500°C-600°C at a speed of 3°C/min-5°C/min, kept for 5h-6h and then cooled to normal temperature.

Preferably, the wavelength of the ultraviolet rays emitted by the ultraviolet lamp is 350nm-400nm.

Preferably, the ultraviolet lamp is vertically irradiated on the sensitive element, and the distance between the irradiation end of the ultraviolet lamp and the sensitive element is 1 mm-20 mm.

Preferably, the first control circuit is provided with a voltage dividing resistor.

Preferably, the analog circuit includes three triodes connected in series, and the triodes are all welded on the circuit board.

Preferably, the casing includes an upper casing and a lower casing, and the upper casing and the lower casing are detachably connected.

Preferably, the housing is provided with an air inlet hole and an air outlet hole, and the air inlet hole and the air outlet hole are arranged staggered from the sensitive element.

When using the formaldehyde gas sensor module provided by the present invention, the control device can control the conduction of the first control circuit to turn on the power supply, input a constant voltage, the sensitive element can effectively sense formaldehyde, and the resistance value of the sensitive element when formaldehyde exists There will be changes, so that the current of the first control circuit changes, but the detection signal of the sensitive element is relatively weak, and the detection signal needs to be amplified and effectively converted by the analog circuit, so that the control device can receive valid detection data. At the same time, the control device can control the conduction of the second control circuit, so that the heating element operates and the sensitive element is heated, so that the sensitive element can also effectively sense formaldehyde under low temperature conditions, which is beneficial to improve the detection effect and detection of the sensitive element. Accuracy. Since there is a correlation between the resistance value of the sensitive element and the formaldehyde concentration, the formaldehyde concentration in the air can be obtained by converting the resistance value of the sensitive element by the detected resistance value of the sensitive element and then using the fitting function to convert the resistance value of the sensitive element.

To sum up, the formaldehyde gas sensor module provided by the present invention can sense and effectively detect the formaldehyde concentration under low temperature conditions, that is, it can effectively reduce the working temperature of the formaldehyde sensor, reduce energy consumption, and make the performance of the formaldehyde sensor more stable , longer service life.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative efforts.

1 is a schematic structural diagram of a formaldehyde gas sensor module provided by the present invention;

Figure 2 is a circuit diagram of the formaldehyde gas sensor module.

In Figure 1-Figure 2:

1 is the circuit board, 2 is the sensitive element, 3 is the heating element, 4 is the analog circuit, 5 is the housing, 6 is the first control circuit, 7 is the second control circuit, 8 is the voltage divider resistor, 9 is the triode, 10 11 is the lower casing, 12 is the air inlet hole, 13 is the air outlet hole, and 14 is the external wire.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The core of the invention is to provide a formaldehyde gas sensor module, which can sense and effectively detect the formaldehyde concentration under low temperature conditions, that is, it can effectively reduce the working temperature of the formaldehyde sensor, reduce energy consumption, and make the performance of the formaldehyde sensor more stable and usable. Longer life.

Please refer to FIG. 1 and FIG. 2, wherein, FIG. 1 is a schematic structural diagram of the formaldehyde gas sensor module provided by the present invention; FIG. 2 is a circuit diagram of the formaldehyde gas sensor module.

This specific embodiment provides a formaldehyde gas sensor module, including: a circuit board 1, a sensing element 2 for sensing formaldehyde, a heating element 3 for enhancing the sensing effect of the sensing element 2 under low temperature conditions, amplifying And the analog circuit 4 for converting the detection signal of the sensitive element 2, the housing 5 for fixing the circuit board 1 and the control device, the sensitive element 2, the heating element 3 and the analog circuit 4 are all arranged on the circuit board 1, and the circuit board 1 is provided with The control device is connected with the sensitive element 2 and the analog circuit 4 through the first control circuit 6 to obtain detection data, and the control device is connected with the heating element 3 through the second control circuit 7 to control the operation of the heating element 3, The first control circuit 6 and the second control circuit 7 are both arranged on the circuit board 1 .

It should be noted that the control device can be set as an electronically controlled switch. The electronically controlled switch is connected to the circuit board 1, the sensitive element 2, the heating element 3 and the analog circuit 4. The electronically controlled switch can be controlled by the first control circuit 6 and the second control circuit. The opening and closing of the control circuit 7 is used to control the opening and closing of the device. The electric control switch can be arranged on the casing 5 to facilitate the operation and use of the user. An external wire 14 can also be welded on the circuit board 1, and the external wire 14 is used to connect an external power source, so as to supply power to the whole device and transmit electrical signals to effectively measure the formaldehyde concentration.

The shape, structure and position of the circuit board 1, the sensitive element 2, the heating element 3, the analog circuit 4, the casing 5 and the control device can be determined in the actual application process according to the actual situation and actual demand.

When using the formaldehyde gas sensor module provided by the present invention, the control device can control the first control circuit 6 to conduct, so as to turn on the power supply, input a constant voltage, and the sensitive element 2 can effectively sense formaldehyde. When formaldehyde exists, the sensitive element 2. The resistance value will change, so that the current of the first control circuit 6 changes, but the detection signal of the sensitive element 2 is relatively weak, and the detection signal needs to be amplified and effectively converted by the analog circuit 4, so that the control device can receive effective detection. data. At the same time, the control device can control the second control circuit 7 to conduct, so as to make the heating element 3 operate and heat the sensitive element 2, so that the sensitive element 2 can also effectively sense formaldehyde under low temperature conditions, which is beneficial to improve the sensitive element 2. detection effect and detection accuracy. Since there is a correlation between the resistance value of the sensitive element 2 and the formaldehyde concentration, the formaldehyde concentration in the air can be obtained by converting the resistance value of the sensitive element 2 through the detected resistance value of the sensitive element 2 and using the fitting function to convert the resistance value of the sensitive element 2 .

To sum up, the formaldehyde gas sensor module provided by the present invention can sense and effectively detect the formaldehyde concentration under low temperature conditions, that is, it can effectively reduce the working temperature of the formaldehyde sensor, reduce energy consumption, and make the performance of the formaldehyde sensor more stable , longer service life.

On the basis of the above embodiment, preferably, the sensitive element 2 is a porous Al ₂ O ₃ nanomaterial, and the heating element 3 is an ultraviolet lamp.

It should be noted that the device can greatly reduce the operating temperature of the semiconductor sensor and improve the loudness, precision and selectivity of the semiconductor sensor by using the TiO ₂ nanometer gas-sensing material and irradiating the TiO ₂ nanometer gas-sensing material with an ultraviolet lamp. , so that the device can effectively sense formaldehyde at a lower working temperature. Moreover, since the sensitive element 2 is made of porous TiO ₂ nanomaterials, the porous structure can effectively increase the contact area between the sensitive element 2 and formaldehyde, thereby improving the sensing effect of the sensitive element 2 .

Preferably, the preparation method of TiO ₂ nanomaterials includes,

S1: dissolve the porous _TiO2 nanotube powder in terpineol;

S2: the TiO ₂ nanotube powder dissolved by ultrasonic vibration is used to prepare a solvent, and the dissolution time is 10min-40min;

S3: Take an appropriate amount of solvent and apply it evenly on the interdigital electrode;

S4: Two high-temperature firings are performed on the interdigital electrodes;

S5: Fix the fired interdigital electrodes on the Al ₂ O ₃ substrate.

It should be noted that ultrasonic vibration can ensure that the _TiO2 nanotube powder is dissolved more uniformly, and the _two high-temperature firings are to make the _TiO2 nanomaterials better fix on the _Al2O3 substrate and ensure that the _TiO2 nanomaterials It is not easy to fall off, that is, the phenomenon of sensor failure due to the falling off of TiO ₂ nanomaterials can be avoided.

Preferably, S4 includes,

S41: The interdigital electrode is raised from normal temperature to 150°C-200°C at a rate of 3°C/min-5°C/min, kept for 2h-3h and then cooled to normal temperature;

S42: The interdigital electrode is raised from normal temperature to 500°C-600°C at a speed of 3°C/min-5°C/min, kept for 5h-6h and then cooled to normal temperature.

Among them, the two high-temperature firing parameters can be set as follows: from normal temperature to 150°C at a speed of 3°C/min, then drop to normal temperature after holding for 2 hours, and then rise to 500°C at a speed of 3°C/min, keep After 5 hours, the temperature is lowered to normal temperature, which can better fix the TiO ₂ nanomaterial without causing damage to the TiO ₂ nanomaterial.

On the basis of the above embodiments, preferably, the wavelength of ultraviolet light emitted by the ultraviolet lamp is 350nm-400nm.

It should be noted that the UV lamp can be set as a small UV lamp with a length of about 1 cm and a width of about 0.3 cm. Since the wavelength of ultraviolet light is smaller than the semiconductor oxide gap, when the _TiO2 nanomaterial is irradiated with ultraviolet light, the _TiO2 nanomaterial will be excited to generate electron-hole pairs, which will assist the _TiO2 nanomaterial to increase its sensitivity to formaldehyde gas, thereby reducing the working temperature. The _TiO2 nanomaterials do not need to be heated to high temperature to work, which can effectively prolong the service life of the sensor.

Preferably, the ultraviolet lamp is vertically irradiated on the sensitive element 2, and the distance between the irradiation end of the ultraviolet lamp and the sensitive element 2 is 1 mm-20 mm. The ultraviolet lamp radiates the sensitive element 2 at a close distance and vertically, which can make the light more concentrated, so that the ultraviolet light can excite the sensitive element 2 more effectively.

It should also be noted that, in the formaldehyde gas sensor module provided by the present invention, the sensitive element 2 is a specially treated porous TiO ₂ nanomaterial, and the heating element 3 is an ultraviolet lamp. This combination can be very effective for low-concentration formaldehyde. Sensitivity and selectivity, at the same time, can also reduce the operating temperature of the gas sensor, reduce energy consumption, and make the sensor stable in performance and long in life.

On the basis of the above embodiment, preferably, the first control circuit 6 is provided with a voltage dividing resistor 8 .

It should be noted that when the sensitive element 2 of the semiconductor sensor is not processed, the sensitivity of the sensitive element 2 to formaldehyde gas is not strong, so the resistance value of the sensitive element 2 is relatively large, about 800kΩ. However, when the sensitive element 2 is irradiated by ultraviolet rays, the sensitivity of the sensitive element 2 increases, and the resistance value becomes very small, about 20kΩ, so the resistance value of the sensitive element 2 changes in a relatively large range. When the circuit is burned out, a large resistor with a large resistance value needs to be connected in series to divide the voltage. Therefore, a voltage dividing resistor 8 needs to be set on the first control circuit 6 to protect the circuit. For example, the voltage dividing resistor 8 can be set to 100MΩ-1GΩ. The circuit board 1 can be arranged inside the housing 5 , and components such as a sensitive element 2 , a heating element 3 , an analog circuit 4 , a voltage dividing resistor 8 and an external wire 14 are arranged on the circuit board 1 .

Preferably, the analog circuit 4 includes three triodes 9 connected in series, and the triodes 9 are all welded on the circuit board 1 .

It should be noted that since the resistance value of the voltage dividing resistor 8 is too large, the current of the first control circuit 6 will be too small during operation, so it is necessary to amplify the current so that the current is within the normal measurement range, so it is necessary to use the analog Circuit 4 amplifies the current. The analog circuit 4 is composed of three triodes 9 connected in series, and the three triodes 9 are connected to the circuit board 1 by welding. The amplification effect of the three triodes 9 is better, and the circuit amplification effect can be effectively ensured. In addition, the three triodes 9 can be welded on the circuit board 1 , which can make the overall structure of the device more compact, the volume is smaller, and the manufacturing process can be simplified.

On the basis of the above embodiment, preferably, the casing 5 includes an upper casing 10 and a lower casing 11 , and the upper casing 10 and the lower casing 11 are detachably connected.

It should be noted that if the parts in the casing 5 are damaged, the upper casing 10 and the lower casing 11 can be disassembled to replace the internal parts, and the new parts can be used together with other undamaged parts. , in order to improve the overall service life of the device.

The shape, size, structure, material and connection method of the upper casing 10 and the lower casing 11 can be determined in the actual application process according to the actual situation and actual demand.

Preferably, the housing 5 is provided with an air inlet hole 12 and an air outlet hole 13 , and the air inlet hole 12 and the air outlet hole 13 are arranged staggered from the sensitive element 2 .

It should be noted that the air inlet holes 12 and the air outlet holes 13 are provided on the housing 5 to facilitate the circulation of gas. In addition, the staggered arrangement of the sensitive element 2, the air inlet hole 12 and the air outlet hole 13 is to avoid that when the sensitive element 2 is facing the air inlet hole 12 and the air outlet hole 13, the surface of the sensitive element 2 is easy to accumulate dust, which in turn affects the sensing of the sensitive element 2. Effect.

The position, size, shape, etc. of the air inlet hole 12 and the air outlet hole 13 can be determined according to the actual situation and actual demand.

In order to further illustrate the composition of the formaldehyde gas sensor module provided by the present invention and its use process, an example will be given next.

The sensitive element 2 of the formaldehyde gas sensor module provided by the present invention is made by dissolving porous _TiO2 nanotube powder in terpineol, then ultrasonically oscillating for 10min-40min to make a solvent, and then using a small spoon to take a small amount of solvent and evenly apply it on the Then, the interdigital electrodes are fired twice at high temperature, and then the interdigitated electrodes are fixed on the Al ₂ O ₃ substrate to form the sensitive element 2 of the formaldehyde sensor. Finally, use a gas soldering iron to solder the sensitive element 2 on the circuit board 1, and ensure that the position of the sensitive element 2 and the positions of the air inlet 12 and the air outlet 13 are staggered.

Among them, the two high-temperature firing operations include: first, rising from normal temperature to 150°C at a speed of 3°C/min, cooling to normal temperature after holding for 2 hours, and then rising from normal temperature to 500°C at a speed of 3°C/min, Keep it for 5h and then cool down to room temperature.

In addition, in this device, the heating element 3 is set as an ultraviolet lamp, and the ultraviolet wavelength radiated by the ultraviolet lamp is 350nm-400nm. The distance between the ultraviolet lamp and the sensitive element 2 is 1mm-20mm, and the ultraviolet lamp irradiates the sensitive element 2 vertically to effectively excite the _TiO2 nanomaterial to generate electron-hole pairs, and assist the _TiO2 nanomaterial to increase its sensitivity to formaldehyde gas. Therefore, the working temperature is reduced, so that the TiO ₂ nanomaterial does not need to be heated to a high temperature to work, which can effectively prolong the service life of the sensor.

The preparation method of the porous nanotube TiO ₂ material used in the present invention is simple, the required materials are low in price, and the dosage is small, and the used ultraviolet lamp is small in size. After the shielding effect, the ultraviolet rays will not cause harm to the human body. At the same time, the nanotube _TiO2 material is irradiated with ultraviolet light, so that the nanotube _TiO2 material has good sensitivity and selectivity to low-concentration formaldehyde, and at the same time, it can greatly reduce the operating temperature of the sensitive element 2, reduce energy consumption, and make the sensor performance stable ,long life.

When using the device, the electronic control switch of the first control circuit 6 where the sensitive element 2 is located can be pressed to turn on the power supply, and a constant voltage is input. The sensitive element 2 can sense formaldehyde gas and generate a weak electrical signal. 2 After the output electrical signal passes through the three triodes 9, the weak electrical signal is amplified to a more appropriate current. According to the known resistance value Ro of the voltage dividing resistor 8, the current value I1 of the first control circuit 6, the voltage value Uo of the constant voltage, etc., the resistance value R1 of the sensitive element 2 can be calculated when the UV lamp is not irradiated. It is the zero adjustment value of the resistance value of the sensitive element 2, that is, the situation where the resistance value of the sensitive element 2 is the largest and the current of the first control circuit 6 is the smallest.

After that, the electric control switch of the second control circuit 7 where the heating element 3 is located can be pressed, so that the second control circuit 7 is turned on, so that the ultraviolet lamp in the heating element 3 is turned on. When the nanotube _TiO2 material is irradiated by ultraviolet light, the photon energy of the ultraviolet light can make the nanotube _TiO2 material generate electron-hole pairs, so as to enhance the conductivity of the nanotube _TiO2 material, so that the resistance value of the nanotube _TiO2 material becomes smaller. After the resistance value of the nanotube TiO ₂ material is stable, the current value I2 of the first control circuit 6 is measured again. According to the known resistance value Ro of the voltage dividing resistor 8, the measured current value I2, and the voltage value of the constant voltage Uo, etc., the resistance value Rx of the sensitive element 2 can be calculated when the ultraviolet lamp is irradiated, that is, Rx=Uo/I2-Ro.

Since there is a fitting function relationship between the formaldehyde concentration and the response of the sensitive element 2, the current formaldehyde concentration can be calculated through the fitting function, that is, C=f(Rx). Among them, C is the formaldehyde concentration, Rx is the response of the sensor to formaldehyde, and is also the resistance value of the sensitive element 2 when the ultraviolet lamp is irradiated, so the device can effectively detect the formaldehyde concentration.

It should be noted that, in the first control circuit 6 and the second control circuit 7 mentioned in this application document, the first and the second are only to distinguish the difference of the position, and there is no order of precedence.

In addition, it should also be noted that the orientation or positional relationship indicated by “upper” and “lower” in the present application is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of simplified description and easy understanding, rather than An indication or implication that the referred device or element must have a particular orientation, be constructed and operate in a particular orientation, is not to be construed as a limitation of the invention.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. Any combination of all the embodiments provided by the present invention falls within the protection scope of the present invention, and is not repeated here.

The formaldehyde gas sensor module provided by the present invention has been described in detail above. The principles and implementations of the present invention are described herein by using specific examples, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (10)

A formaldehyde gas sensor module, characterized by comprising: a circuit board (1), a sensitive element (2) for sensing formaldehyde, and a heating for enhancing the induction effect of the sensitive element (2) under low temperature conditions an element (3), an analog circuit (4) for amplifying and converting the detection signal of the sensitive element (2), a housing (5) for fixing the circuit board (1), and a control device, the sensitive The element (2), the heating element (3) and the analog circuit (4) are all arranged on the circuit board (1), and the circuit board (1) is arranged in the housing (5); The control device is connected to the sensitive element (2) and the analog circuit (4) through a first control circuit (6) to acquire detection data, and the control device communicates with the sensitive element (2) and the analog circuit (4) through a second control circuit (7). A heating element (3) is connected to control the operation of the heating element (3), and both the first control circuit (6) and the second control circuit (7) are provided on the circuit board (1). The formaldehyde gas sensor module according to claim 1, characterized in that, the sensitive element (2) is a porous _TiO2 nanomaterial, and the heating element (3) is an ultraviolet lamp. The formaldehyde gas sensor module according to claim 2, wherein the preparation method of the TiO ₂ nanomaterial comprises: S1: dissolve the porous _TiO2 nanotube powder in terpineol; S2: Utilize the _TiO nanotube powder dissolved by ultrasonic vibration to make a solvent, and the dissolution time is 10min-40min; S3: take an appropriate amount of the solvent and evenly apply it on the interdigital electrodes; S4: performing two high-temperature firings on the interdigital electrodes; S5: Fix the fired interdigital electrodes on the Al ₂ O ₃ substrate. The formaldehyde gas sensor module according to claim 3, wherein the S4 comprises: S41: the interdigital electrode is raised from normal temperature to 150°C-200°C at a speed of 3°C/min-5°C/min, kept for 2h-3h and then cooled to normal temperature; S42: The interdigital electrode is raised from normal temperature to 500°C-600°C at a speed of 3°C/min-5°C/min, kept for 5h-6h and then cooled to normal temperature. The formaldehyde gas sensor module according to any one of claims 2 to 4, wherein the ultraviolet light emitted by the ultraviolet lamp has a wavelength of 350nm-400nm. The formaldehyde gas sensor module according to claim 5, characterized in that the ultraviolet lamp is vertically irradiated on the sensitive element (2), and the irradiated end of the ultraviolet lamp and the sensitive element (2) are located between The distance is 1mm-20mm. The formaldehyde gas sensor module according to any one of claims 1 to 4, wherein the first control circuit (6) is provided with a voltage dividing resistor (8). The formaldehyde gas sensor module according to claim 7, wherein the analog circuit (4) comprises three triodes (9) connected in series, and the triodes (9) are all welded to the circuit board (1) superior. The formaldehyde gas sensor module according to any one of claims 1 to 4, wherein the casing (5) comprises an upper casing (10) and a lower casing (11), and the upper casing ( 10) and the lower casing (11) are detachably connected. The formaldehyde gas sensor module according to any one of claims 1 to 4, wherein the housing (5) is provided with an air inlet (12) and an air outlet (13), the air inlet (12) and the air outlet hole (13) are arranged staggered from the sensitive element (2).

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