An ozone sensor based on etching indium tin oxide film and its preparation method and application

Abstract

The present invention belongs to the field of sensing technology, and specifically relates to an ozone sensor based on an etched indium tin oxide film, as well as its preparation method and application. The preparation method comprises: using a laser to etch the ITO layer on the surface of ITO glass to obtain a patterned ITO film resistor device (resistance of 0.1-5 kΩ); placing the ITO film resistor device in a plasma etcher and performing Ar & H2 plasma etching to obtain an ITO film resistor device with a rough surface and rich surface defects; and annealing and aging treatment in air followed by cooling to produce an ozone sensor based on the etched indium tin oxide film. In self-heating mode, the sensor can highly sensitively detect trace amounts of O3 in the environment, exhibiting low power consumption, high selectivity, resistance to humidity interference, and long-term stability, meeting the requirements for O3 detection in indoor and outdoor environments. This method solves the problems of existing O3 sensors, such as the opaque sensing substrate and complex preparation process (requiring an integrated heater), and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of sensing technology, and in particular to an ozone sensor based on etching an indium tin oxide film, a preparation method thereof, and an application thereof in detecting trace ozone in an environment. Background Art

[0002] Ozone (O3) is a strong oxidant. Ground-level O3 can cause severe damage to the human nervous system, eyes, nose, throat, and respiratory tissues. Studies have shown that ozone exposure increases the risk of premature death from heart and lung disease. While my country's air quality has continued to improve in recent years, O3 pollution is becoming increasingly severe nationwide and in key regions. Developing new O3 monitoring technologies and empowering the fight against O3 pollution through technology is crucial for public health.

[0003] Indium tin oxide (ITO) is by far the most widely used n-type transparent conductive oxide (TCO). ITO glass is widely used in solar cells, LEDs, mobile phones, flat-panel displays, and other fields. Furthermore, ITO is also an important gas-sensing material. When heated, ITO exhibits a good electrical response to O₃.

[0004] Although gas sensors (including O₃) based on metal oxide semiconductors (including ITO) offer advantages such as small size, low cost, fast response, and easy integration, the fabrication of semiconductor gas sensors first requires obtaining nanopowders with controllable composition, size, and morphology. This is then mixed with a binder, pore-forming agent, and solvent to create a sensitive material slurry. This slurry is then applied to a specialized sensing substrate coated with interdigitated electrodes and a microheater via screen printing or microspraying. After aging, a stable sensor is obtained. Although this approach allows for independent control of the sensitive film properties and operating temperature, it also suffers from the following drawbacks: First, the device fabrication process is relatively complex and costly, hindering the large-scale application of sensors. Second, conventional silicon-based and ceramic sensing substrates are generally opaque, making it difficult to fabricate such devices into transparent sensors. Third, existing oxide sensors require integrated heaters, which limits the use of flexible substrates and significantly increases the complexity of device fabrication and sensor power consumption. Summary of the Invention

[0005] One of the purposes of the present invention is to solve the problems of complex device preparation process, device opacity and high sensor power consumption in existing oxide semiconductor (ITO) gas sensors, and to provide an ozone sensor based on etched indium tin oxide film. Conventional ITO glass is used as the raw material, and patterned ITO film resistor units are drawn by laser etching. Ar&H2 plasma etching is then used to obtain an etched ITO film resistor device. After low-temperature air annealing, a highly sensitive ozone sensor capable of detecting trace O3 in the environment in self-heating mode is obtained.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing an ozone sensor based on etching an indium tin oxide film, comprising the following steps:

[0007] Step 1: Using a short-pulse laser to etch the indium tin oxide conductive layer of the ITO glass to obtain an array of patterned ITO film resistor units, and then using a short-pulse laser to cut and separate adjacent patterned ITO film resistor units to obtain a patterned ITO film resistor device for use; the patterned ITO film resistor device includes insulating glass and a patterned ITO film resistor unit on the insulating glass, the patterned ITO film resistor unit includes two independently arranged ITO electrodes and an ITO serpentine resistance wire connecting the two ITO electrodes, and the resistance of the ITO resistance wire is 0.1-5kΩ;

[0008] Step 2: Place the patterned ITO film resistor device in an etcher, and perform Ar&H2 plasma etching on the ITO electrode and the ITO resistor wire to obtain an etched ITO film resistor device with a rough surface and rich surface defects;

[0009] Step 3: annealing and aging the etched ITO film resistor device in air and then cooling it to obtain an ozone sensor based on the etched indium tin oxide film.

[0010] As a further improvement of the preparation method of ozone sensor based on etching of indium tin oxide film:

[0011] Preferably, the indium tin oxide conductive layer in step 1 is an In2O3 film with a Sn mass fraction of 5-15%, a film thickness of 100-500 nm, and a sheet resistance of 6-20Ω.

[0012] Preferably, the insulating glass is ordinary glass or quartz glass with a thickness of 30-300 μm. The thinner the insulating glass, the lower the sensor power consumption.

[0013] Preferably, the ITO resistance wires in step 1 are arranged in a serpentine bending or serpentine coiling manner, and adjacent ITO resistance wires are arranged at equal intervals.

[0014] Preferably, the ITO resistance wire is arranged in a serpentine bend, the width W0 of the ITO resistance wire is 5-200µm, the spacing W1 between adjacent bend segments is 10-200μm, and the length l1 of each bend segment in the ITO resistance wire is 1-3mm; the ITO electrode is square, the length l2 is 1.4-3.5mm, and the width W2 is 0.5-2mm.

[0015] Preferably, when a short-pulse laser is used to etch the indium tin oxide conductive layer of the ITO glass in step 1, a program is used to control the scanning etching path of the laser; the wavelength of the short-pulse laser is 355nm ultraviolet light or 532nm green light, the laser pulse width is fs to ps, the laser repetition frequency is 10-100kHz, the laser power is 0.1-5W, the laser spot diameter focused on the ITO glass surface is 10-50μm, and the laser scanning speed is 100-2000mm / s.

[0016] Preferably, the etcher in step 2 is a plasma etcher or a reactive ion etcher, the radio frequency of the etcher is 13.56 MHz, the power is 100–300 W, the etching time is 0.5-2 h, and the Ar&H2 gas is a mixture of high-purity Ar and H2, and the volume ratio of H2 in the mixture is 1–5%.

[0017] Preferably, the temperature of the annealing treatment in step 3 is 300-450°C, and the time is 0.5-24h.

[0018] A second object of the present invention is to provide an ozone sensor based on etching an indium tin oxide film, which is prepared by any of the above-mentioned methods for preparing an ozone sensor based on etching an indium tin oxide film.

[0019] A third object of the present invention is to provide an application of the above-mentioned ozone sensor based on etching of an indium tin oxide film in detecting trace ozone, comprising the following steps:

[0020] Step 21. Study the relationship between the temperature of the ozone sensor based on the etched indium tin oxide film and the driving power (by adjusting the sensor driving voltage), and regulate the self-heating temperature of the sensor; within the operating temperature range where the sensitive film does not burn out and self-heating is stable, adjust the operating temperature of the sensor by adjusting the self-heating power, and study the electrical response of the sensor to 1000ppbO3 at different operating temperatures ( R g / R a ),in, R g 、 R a are the resistance values of the sensor in the presence of O3 and in the absence of O3, respectively. The operating temperature corresponding to the maximum response value of the sensor to O3 is obtained and recorded as the optimal operating temperature;

[0021] Step 22: At the optimal operating temperature in step 21, test the electrical response of the sensor to 10-1000 ppbO3 ( R g / R a), obtain the corresponding relationship curve between the O3 response of the sensor and the O3 concentration, which is recorded as the response characteristic curve;

[0022] Step 23: At the optimal operating temperature in step 21, record the resistance value of the sensor in air background and in the presence of O3 gas to obtain the response value of the sensor. R g / R a , and then analyze the concentration of O3 in the current environment according to the response characteristic curve calibrated in step 22.

[0023] The beneficial effects of the present invention compared to the prior art are:

[0024] 1) This invention provides a process for fabricating an ozone sensor based on etching an indium tin oxide film. Laser etching is first used to obtain an array of patterned ITO film resistor units, which are then cut to obtain the patterned ITO film resistor units. This ozone sensor based on etching an indium tin oxide film retains the high visible light transmittance characteristic of transparent conductive indium tin oxide glass. The device is visible light transparent, overcoming the opacity bottleneck of conventional oxide semiconductor gas sensors and meeting the demand for O3 detection in future transparent electronics systems. The resistance of the ITO resistor wire is designed to balance the resistance of the ITO film device (to match the voltage and current system of the driving circuit) with the efficient self-heating of the film device (to reduce the dissipation of Joule heat generated by self-heating).

[0025] The patterned ITO film resistor device was then etched with Ar and H2 plasma to obtain an ITO sensitive film rich in surface defects, which enabled the conventional ITO film to exhibit excellent O3 response characteristics. Annealing and aging were then performed to finally produce an ozone sensor based on the etched indium tin oxide film.

[0026] 2) In the ozone sensor prepared by the present invention, the ITO resistor wire is arranged in a serpentine bend or serpentine coil. By reducing the resistance area of the ITO resistor wire, thinning the glass substrate thickness, or using pulse heating, the sensitive area (serpentine resistor) can be quickly heated to 150-250°C at low driving power consumption, achieving high sensitivity and rapid response to ppb-level O3 in the environment.

[0027] 3) The preparation process of the present invention is simple, and does not require multiple steps such as ITO nanopowder synthesis, slurry preparation, and coating. Laser etching and plasma treatment are compatible with conventional micro-nano etching processes. The batch preparation cost is low and the device consistency is good. Low-cost industrial ITO glass is directly used as the raw material, which is conducive to the large-scale production and application of sensors.

[0028] 4) Compared with conventional four-pin oxide sensors (two pins are used to measure the resistance of the sensitive film, two pins are used for the heater to control the operating temperature of the sensor, and the sensitive film and heater are isolated by insulating ceramic), the ozone sensor based on etched indium tin oxide film does not require an integrated external heater, has a simple structure (two-electrode structure), and there is no isolation between the sensitive film and the insulating glass. The ITO sensitive film is also used as a heating layer. The operating temperature of the sensor (150–250°C) is adjusted by driving power through the ITO sensitive film (snake resistor). The device can directly control the operating temperature of the sensitive film through self-heating mode, thereby controlling the sensor's response to O3. The advantages of self-heating are fast heat conduction rate, low heat dissipation, and low power consumption.

[0029] 5) The present invention also provides an application of an ozone sensor based on an etched indium tin oxide film. By studying the relationship between the sensitive film temperature and the driving power of the ozone sensor based on the etched indium tin oxide film at different driving powers, the self-heating temperature of the sensor is regulated to obtain the operating temperature when the sensor's response value to O3 is the largest, which is recorded as the optimal operating temperature; at the optimal operating temperature, the electrical response of the sensor to 10-1000 ppb O3 is tested. R g / R a , forming a response characteristic curve; in actual testing, at the optimal working temperature, the resistance value of the sensor in the air background and in the presence of O3 gas is recorded successively to obtain the response value of the sensor R g / R a , corresponding to the response characteristic curve, analyze the concentration of O3 in the current environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram and a physical picture of the preparation process of the ozone sensor based on etching of the indium tin oxide film of the present invention.

[0031] Figure 2 is the geometrical dimension of the ITO film resistor in the ITO sensor of the present invention.

[0032] Figure 3 The morphologies and X-ray diffraction patterns of the ordinary ITO sensor 1 prepared in Comparative Example 1 (not subjected to Ar&H2 plasma etching) and the etched ITO ozone sensor 1 prepared in Example 1 (Ar&H2 plasma etching for 60 min), where (a) and (b) are scanning electron microscope (SEM) images, (c) and (d) are atomic force microscope (AFM) images, and (e) is an X-ray diffraction (XRD) pattern.

[0033] Figure 4The etched ITO ozone sensor 1 prepared in Example 1 shows the sensor center peak temperature and infrared thermal imaging photos at different driving powers (controlling the driving voltage at both ends of the sensor).

[0034] Figure 5 These are the resistance response curves of the common ITO sensor 1 prepared in comparative example 1, the common ITO sensor 2 prepared in comparative example 2, and the etched ITO ozone sensor 1 prepared in example 1 to 1 ppm O 3 at a self-heating temperature of 180°C.

[0035] Figure 6 The response characteristics of the ordinary ITO sensor 1 prepared in Comparative Example 1 and the etched ITO ozone sensor 1 prepared in Example 1 to O3: (a) The response of the two sensors to 1 ppm O3 at different operating temperatures; (b) The response and recovery characteristic curves of the two sensors to 25–1000 ppb O3 at 180°C; (c) The relationship curve between O3 response and O3 concentration of the two sensors at 180°C; (d) The selectivity of the two sensors in response to multiple gases at 180°C; (e) The humidity dependence characteristic of the etched ITO ozone sensor 1 of Example 1 to 1 ppm O3 at 180°C; (f) The long-term stability of the response of the two sensors to 1 ppm O3 at 180°C.

[0036] Figure 7 Response characteristics of the etched ITO ozone sensor 1 prepared in Example 1 to 1 ppm O₃ in pulse heating mode (peak temperature 180°C, duty cycle of sensor drive voltage adjusted): (a) dynamic response curve; (b) sensor response to 1 ppm O₃ and power consumption at different duty cycles.

[0037] Figure 8 Test results of the ozone response uniformity of ITO film resistor unit arrays (18×12=216) and corresponding etched ITO ozone sensors prepared in batches using the preparation method of the present invention: (a) ITO glass pattern (the ITO film is retained in the dark area, and the ITO film in the light area is laser etched away to expose the glass substrate), 18×12 sensor array, and dimensions and actual image of a single film resistor device; (b) Dimensional comparison of the ITO sensor (transparent) prepared by the present invention with existing MEMS sensors, Japanese Fis, and Zhengzhou Weisheng MQ131O3 sensors; (c) Response characteristics of ozone sensors selected from the same batch but at different locations to 1 ppm O3 at a self-heating temperature of 180°C. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] This embodiment provides a method for preparing an ozone sensor based on an indium tin oxide film, which specifically includes the following steps:

[0041] S1. Take ITO glass. The ITO glass structure includes an indium tin oxide conductive layer and ordinary glass. The indium tin oxide conductive layer has a thickness of 185 nm, a Sn mass fraction of 10%, and a square resistance of 10 Ω. The ordinary glass has a thickness of 300 μm.

[0042] The ITO glass surface is cleaned with anhydrous ethanol and then dried. The indium tin oxide conductive layer of the ITO glass is etched with a short-pulse laser. The laser control system is used to control the laser to move along the designed etching path to obtain an array of patterned ITO film resistor units. The adjacent patterned ITO film resistor units are then cut using a short-pulse laser to separate them, thereby obtaining a patterned ITO film resistor device for standby use.

[0043] The short pulse laser is an ultraviolet laser with a wavelength of 355nm, a laser pulse width of 1ps, a laser repetition frequency of 50kHz, a laser power of 1.2W, a laser spot diameter of 20μm, and a laser scanning speed of 500mm / s. It is repeated 3 to 5 times until the indium tin oxide conductive layer in the set area is completely etched away;

[0044] The patterned ITO film resistor device prepared is as follows Figure 2 As shown, it includes insulating glass and a patterned ITO film resistor unit on the insulating glass. The patterned ITO film resistor unit includes two independently arranged ITO electrodes and an ITO resistance wire connecting the two ITO electrodes. The resistance of the ITO resistance wire is 0.56kΩ; the ITO resistance wire is arranged in a serpentine shape, the width W0 of the ITO resistance wire is 100µm, the distance W1 between adjacent bending segments is 100μm, and the length l1 of each bending segment in the ITO resistance wire is 1mm; the ITO electrode is square as a whole, with a length l2 of 1.4mm and a width W2 of 0.5mm.

[0045] S2. Load the patterned ITO film resistor device into a plasma etcher and perform Ar&H2 plasma etching on the ITO substrate. The plasma radio frequency frequency is 13.56 MHz, the power is 150 W, and the etching time is 1 hour. The Ar&H2 gas is high-purity Ar containing 5% H2 by volume, to obtain an etched ITO film resistor device with a rough surface and rich in surface defects.

[0046] S3. Annealing and aging the etched ITO film resistor device in air at a temperature of 450° C. for 3 hours, and then cooling the device to obtain an ozone sensor 1 based on the etched indium tin oxide film, which is referred to as etched ITO ozone sensor 1.

[0047] Comparative Example 1

[0048] This comparative example provides a method for preparing a common ITO sensor. The specific steps are similar to those of Example 1, except that the Ar & H2 plasma treatment in step S2 is omitted, and only steps S1 and S3 are performed. A common ITO sensor 1 is obtained.

[0049] Comparative Example 2

[0050] This comparative example provides a method for preparing a common ozone sensor. The specific steps are similar to those of Example 1, except that: in step S2, Ar & H2 plasma etching is not performed. Instead, the patterned ITO film resistor device prepared in step S1 is placed in a tube furnace and annealed in an Ar & H2 atmosphere. The Ar & H2 gas flow rate is 100 sccm, and the heating rate of the tube furnace is 5°C / min. The temperature is raised from room temperature to 450°C, maintained at this temperature for 5 hours, and then naturally cooled to room temperature after the end of the insulation, thereby obtaining an ITO film resistor device annealed in an Ar & H2 atmosphere.

[0051] S3. The device is subjected to annealing and aging treatment in air at a temperature of 450° C. for 3 hours, and then cooled to obtain a common ITO sensor 2.

[0052] Example 2

[0053] This example provides a method for fabricating an ozone sensor based on an indium tin oxide film. The specific steps are similar to those in Example 1, with the only difference being that the Ar & H plasma etching power in step S2 is 100 W and the etching time is 0.5 h. All other process parameters remain the same. Finally, an ozone sensor 2 based on an etched indium tin oxide film is produced, referred to as etched ITO ozone sensor 2.

[0054] Example 3

[0055] This example provides a method for fabricating an ozone sensor based on an indium tin oxide film. The specific steps are similar to those in Example 1, with the only difference being that the Ar & H plasma etching power in step S2 is 300 W and the etching time is 2 hours. All other processing parameters remain the same. Finally, an ozone sensor 3 based on an etched indium tin oxide film is produced, referred to as etched ITO ozone sensor 3.

[0056] Example 4

[0057] This example provides a method for fabricating an ozone sensor based on an indium tin oxide film. The specific steps are similar to those in Example 1, except that the width W0 of the ITO resistor wire is 100µm, the distance W1 between adjacent bends is 100µm, and the length l1 of each bend in the ITO resistor wire is 2.1mm. The ITO electrode is square in shape, with a length l2 of 2.1mm and a width W2 of 2.4mm. All other parameters are the same. Finally, an ozone sensor 4 based on an etched indium tin oxide film is fabricated, referred to as etched ITO ozone sensor 4.

[0058] Example 5

[0059] This embodiment provides a method for preparing an ozone sensor based on an indium tin oxide film. The specific steps are similar to those in Example 1, except that the width W0 of the ITO resistor wire is 100µm, the distance W1 between adjacent bends is 100µm, and the length l1 of each bend in the ITO resistor wire is 3.1mm. The ITO electrode is generally square, with a length l2 of 3.5mm and a width W2 of 2.0mm. All other parameters are the same. Finally, an ozone sensor 5 based on an etched indium tin oxide film is produced, referred to as etched ITO ozone sensor 5.

[0060] Example 6

[0061] This embodiment provides an application of an ozone sensor based on etching an indium tin oxide film, which specifically includes the following steps:

[0062] Step 21: By adjusting the sensor driving voltage, the relationship between the temperature and the driving power of the etched ITO ozone sensor 1 prepared in Example 1 is studied, and the self-heating temperature of the sensor is regulated; within the operating temperature range where the sensitive film (snake-shaped resistance wire area) does not burn out and self-heats stably, the operating temperature of the sensor is adjusted by adjusting the self-heating power, and the electrical response of the sensor to 1000 ppbO3 at different operating temperatures is studied ( R g / R a ),in, R g 、 R aThe resistance values of the sensor in the presence of O3 and air are respectively obtained, and the operating temperature at which the sensor's response to O3 is the largest is obtained, which is recorded as the optimal operating temperature. Testing has shown that the temperature of the etched ITO ozone sensor 1 is highly linearly correlated with its power consumption. At the optimal operating temperature (180°C), its power consumption is 350mW, and its maximum operating temperature (stable operation without burning the serpentine resistance wire) can reach 250°C.

[0063] Step 22: At the optimal operating temperature in step 21, test the electrical response of the ITO sensor to different concentrations of O3 within the concentration range of 10-1000ppb. R g / R a ,in R g 、 R a The sensor's resistance values in the presence of O₃ and air backgrounds were plotted, and the sensor's response curves to O₃ at different driving powers (self-heating temperatures) were obtained. Test results showed that the sensor's response to trace ozone at 25 ppb reached 1.5, and to 1 ppm ozone concentration reached 5.2. The change in sensor resistance with ozone concentration was consistent with the sensing characteristics of n-type metal oxide semiconductors, and exhibited a highly linear correlation at ozone concentrations above and below 200 ppb.

[0064] Step 23: At the optimal operating temperature in step 21, record the resistance value of the sensor in air background and in the presence of O3 gas to obtain the response value of the sensor. R g / R a , and then analyze the concentration of O3 in the current environment according to the response characteristic curve calibrated in step 22.

[0065] Performance testing:

[0066] 1) Figure 1 This is a flow chart for preparing an indium tin oxide film-based ozone sensor. The specific process is as follows: ① Laser etching is used to pattern the ITO film resistor unit to obtain a patterned ITO film resistor device; ② Ar and H2 plasma etching is performed on the ITO electrode and ITO resistor wire to obtain an etched ITO film resistor device with a rough surface and rich surface defects. (After this treatment, some In2O3 is reduced to In, causing the originally transparent ITO film to darken and reduce its transmittance; ③ Annealing in air at a low temperature (300–450°C) makes the ITO film transparent again.

[0067] The ozone sensor of the present invention can be used for real-time online monitoring of indoor O3 concentration. The ozone sensor is integrated into a smart device and installed on the ceiling of an office with an ozone ultraviolet disinfection lamp. When the ultraviolet disinfection lamp in the office is started (ozone will be generated and diffused into the environment), the portable smart device can collect the resistance change of the ozone sensor in real time, and convert it into the real-time ozone concentration in the environment through the correspondence between the concentration and the resistance change of the ozone sensor, and then transmit it to the mobile phone via Bluetooth. The real-time monitoring of the ozone concentration in the working environment can be achieved through the pre-adapted WeChat applet, and when the safety concentration threshold is exceeded, the user interface will flash a hazard sign in real time.

[0068] 2) Figure 2 This diagram illustrates the geometric dimensions of the patterned ITO film resistor unit in the O3 sensor of the present invention. The patterned ITO film resistor unit consists of two square electrodes at opposite ends and a serpentine resistance wire connecting the two square electrodes. The serpentine resistance wire has a width W0 of 5–200µm, a spacing W1 between adjacent bends of 10–200µm, and a length l1 of each bend of 1–3mm. The length l2 of the square electrodes is 1.4–3.5 mm and equal to the width of the ITO glass, while the width W2 is 0.5–2mm. The total sensor resistance is 0.1–5kΩ (primarily determined by the width and length of the serpentine resistance wire).

[0069] 3) Figure 3 The morphology and XRD patterns of the ITO films on the ozone sensors prepared in Comparative Example 1 and Example 1 are shown, where (a) and (b) are scanning electron microscope (SEM) images, (c) and (d) are atomic force microscope (AFM) images, and (e) is an X-ray diffraction (XRD) pattern. Figure 3 Comparison of the electron microscope images of the film layers on the sensors prepared in Example 1 and Comparative Example 1 shows that the surface of the patterned ITO film (Comparative Example 1) that was only subjected to laser etching is dense and flat, which is not conducive to the adsorption and charge exchange of the gas molecules to be measured, and therefore, the electrical response is weak; while the surface of the ITO film (Example) that was treated with Ar&H2 plasma is rough and rich in various defects, which is conducive to the adsorption and electrical detection of target gas molecules.

[0070] 4) Figure 4 The peak temperature at the center of the sensitive area of the etched ITO ozone sensor 1 prepared in Example 1 at different driving powers (controlling the driving voltage at both ends of the sensor) and its infrared thermal imaging photos.

[0071] Depend on Figure 4As can be seen, the temperature at the center of the sensitive area increases with increasing drive power; at a high drive power of ~450mW, the temperature in the sensitive area can exceed 200°C. The optimized layout of the ITO sensing / heating filaments in the sensitive area enables efficient self-heating of the sensor while maintaining low power consumption. Infrared camera images confirm that the Joule heat generated by self-heating is primarily concentrated in the sensitive area (snake resistor).

[0072] 5) Figure 5 These are the resistance response curves of the common ITO sensor 1 prepared in comparative example 1, the common ITO sensor 2 prepared in comparative example 2, and the etched ITO ozone sensor 1 prepared in example 1 to 1 ppm O 3 at 180° C.

[0073] The O3 sensors in Comparative Examples 1 and 2 have the same ITO pattern dimensions as Example 1. At the same operating temperature (controlling the sensor's drive power), Comparative Example 1 (without Ar & H2 plasma etching) exhibited minimal response to 1 ppm O3, while Comparative Example 2 (annealed in an Ar & H2 atmosphere) also exhibited a weak response to O3. However, the Example exhibited a high response to 1 ppm O3. This indicates that conventional ITO films (with a flat, dense surface) inherently exhibit a weak response to O3. Ar & H2 plasma treatment effectively creates active sites, enabling ITO thin-film devices to achieve gas-sensing properties comparable to those of ITO pellets.

[0074] 6) Figure 6 Figure 1 shows the response characteristics of the ordinary ITO sensor 1 prepared in Comparative Example 1 and the etched ITO ozone sensor 1 prepared in Example 1 to O3: (a) The response of the two sensors to 1 ppm O3 at different operating temperatures; (b) The response and recovery characteristic curves of the two sensors to 25–1000 ppb O3 at 180°C; (c) The relationship curve between the O3 response and O3 concentration of the two sensors at 180°C; (d) The selectivity of the two sensors to various gases at 180°C; (e) The humidity dependence of the etched ITO ozone sensor 1 to 1 ppm O3 at 180°C; (f) The long-term stability of the response of the two sensors to 1 ppm O3 at 180°C.

[0075] Depend on Figure 6It can be seen that temperature has a significant impact on O3 response. The sensor has almost no response to O3 below 130°C, indicating that O3 detection requires device heating. By regulating the sensor's self-heating drive power and heating the sensor to 180°C, the device's response to O3 can be activated. At this operating temperature, the device has a relatively fast response to O3, with a recovery time of approximately 1 minute. The etched ITO ozone sensor 1 prepared in Example 1 has excellent selectivity for O3, humidity resistance, and long-term stability, meeting the requirements for O3 detection in indoor and outdoor environments. Furthermore, the device has a significant response to O3 as low as 25 ppb, meeting the O3 monitoring requirements of the national standards "Ambient Air Quality Standards" and "Indoor Air Ozone Hygiene Standards."

[0076] 7) Figure 7 Response characteristics of the etched ITO ozone sensor 1 prepared in Example 1 to 1 ppm O₃ in pulse mode (peak temperature 180°C, duty cycle of the sensor drive voltage adjusted): (a) dynamic response curve; (b) sensor response to 1 ppm O₃ and power consumption at different duty cycles.

[0077] Depend on Figure 7 It can be seen that when the etched ITO ozone sensor 1 prepared in Example 1 is subjected to pulse self-heating (periodic start and stop of heating), the duty cycle of the heating waveform is reduced to 10% at a peak temperature of 180°C, and the average power consumption of the sensor is reduced by one order of magnitude. Although the response value of the device is reduced, the device still has a significant response to O3; when the duty cycle is 3%, the average power consumption of the device can be reduced to below 20mW, which is comparable to the power consumption of MEMS devices, which is conducive to the application of sensors in future Internet of Things grid monitoring.

[0078] 8) Figure 8 Test results of the ozone response uniformity of ITO film resistor unit arrays (18×12=216) and corresponding etched ITO ozone sensors prepared in batches using the preparation method of the present invention: (a) ITO glass pattern (the ITO film is retained in the dark area, and the ITO film in the light area is laser etched away to expose the glass substrate), 18×12 sensor array, and dimensions and actual image of a single film resistor device; (b) Dimensional comparison of the ITO sensor (transparent) prepared by the present invention with existing MEMS sensors, Japan Fis, and Zhengzhou Weisheng MQ131O3 sensors; (c) Response characteristics of ozone sensors selected from the same batch but at different locations to 1 ppm O3 at 180°C.

[0079] Depend on Figure 8As can be seen, the fabrication method of the present invention meets the requirements for mass production of devices with uniform performance. Using commercial ITO glass (2.5 cm side length) as a substrate, 216 ozone sensors were obtained through laser etching, scribing, plasma etching, and air annealing. Compared with commercial O3 sensors (Fis from Japan and MQ131 from Zhengzhou Weisheng), the sensors produced by the present invention offer a simpler fabrication process, smaller size, greater transparency, lower batch production costs, and superior device consistency.

[0080] 9) The etched ITO ozone sensors 2, 3, 4, and 5 prepared in Examples 2, 3, 4, and 5 were tested for the relationship between self-heating temperature and power consumption, as well as their gas sensing performance to 1 ppm trace ozone gas at the optimal operating temperature. The results are as follows:

[0081] Due to the reduction in processing time and power consumption, the ITO film of the etched ITO ozone sensor 2 changes little, the resistance of the serpentine ITO resistance wire in the sensitive area is ~0.56 kΩ, its power consumption-temperature relationship is close to that of the untreated comparative example 1, and its response value of 2.1 is also higher than that of comparative example 1.

[0082] As time and processing power consumption increase, the ITO film of the etched ITO ozone sensor 3 undergoes tremendous changes, with the surface showing large granules. The resistance of the serpentine ITO resistor wire in its sensitive area reaches ~2.5kΩ. It can reach a higher temperature under the same power consumption, but is more prone to burnout. Its response value reaches 3.3, and it also achieves a high response to 1ppm trace ozone.

[0083] For the etched ITO ozone sensor 4, the sensitive layer area is expanded to 2.1×2.1mm 2 After that, the total length of the serpentine electrode in the sensitive area increases, so the serpentine resistance wire in the sensitive area increases to 3.2kΩ. It needs to apply a larger voltage at the same power consumption, and due to the increase in area, the temperature of the device is lower than that of the comparative example 1 at the same power consumption. Therefore, its power consumption at the optimal operating temperature is 460mW. Although its power consumption increases at the optimal operating temperature, its response value to 1ppm ozone reaches 3.6, which is also higher than that of the comparative example 1.

[0084] The sensitive area of the etched ITO ozone sensor 5 is further increased, and the power consumption of the sensor at the optimal operating temperature is further increased to 600mW, but its response value to 1ppm ozone is 2.9, which is also higher than that of comparative example 1, and can also realize the concentration monitoring of ambient O3.

[0085] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive examples. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. An application of an ozone sensor based on etching an indium tin oxide film in detecting trace ozone, characterized in that: The steps include: Step 21. Study the relationship between the temperature and driving power of the ozone sensor based on the etched indium tin oxide film, and regulate the self-heating temperature of the sensor; within the operating temperature range where the sensitive film does not burn out and self-heating is stable, adjust the operating temperature of the sensor by regulating the self-heating power, and study the electrical response of the sensor to 1000 ppb O3 at different operating temperatures. R g / R a ,in, R g 、 R a are the resistance values of the sensor in the presence of O3 and in the absence of O3, respectively. The operating temperature corresponding to the maximum response value of the sensor to O3 is obtained and recorded as the optimal operating temperature; Step 22: Test the electrical response of the sensor to 10-1000 ppb O3 at the optimal operating temperature of step 21. R g / R a , obtain the corresponding relationship curve between the sensor's O3 response and O3 concentration, which is recorded as the response characteristic curve; Step 23: At the optimal operating temperature in step 21, record the resistance value of the sensor in air background and in the presence of O3 gas to obtain the response value of the sensor. R g / R a , then analyze the concentration of O3 in the current environment according to the response characteristic curve calibrated in step 22; The method for preparing the ozone sensor based on etching the indium tin oxide film comprises the following steps: Step 1: Use a short-pulse laser to etch the indium tin oxide conductive layer of the ITO glass to obtain an array of patterned ITO film resistor units, and then use a short-pulse laser to cut and separate adjacent patterned ITO film resistor units to obtain a patterned ITO film resistor device for standby use; the patterned ITO film resistor device includes insulating glass and a patterned ITO film resistor unit on the insulating glass, the patterned ITO film resistor unit includes two independently arranged ITO electrodes and an ITO resistance wire connecting the two ITO electrodes, and the resistance of the ITO resistance wire is 0.1-5 kΩ; Step 2: Place the patterned ITO film resistor device in an etcher, and perform Ar&H2 plasma etching on the ITO electrode and the ITO resistor wire to obtain an etched ITO film resistor device with a rough surface and rich surface defects; Step 3: annealing and aging the etched ITO film resistor device in air and then cooling it to obtain an ozone sensor based on the etched indium tin oxide film.

2. The application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 1 is characterized in that: The indium tin oxide conductive layer in step 1 is an In2O3 film with a Sn mass fraction of 5-15%, a film thickness of 100-500 nm, and a sheet resistance of 6-20 Ω.

3. The application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 1, characterized in that: The insulating glass is ordinary glass or quartz glass, and has a thickness of 30-300 μm.

4. The application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 1, characterized in that: The ITO resistance wires in step 1 are arranged in a serpentine bending or serpentine coiling pattern, and adjacent ITO resistance wires are arranged at equal intervals.

5. The application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 4, characterized in that: The ITO resistance wire is arranged in a serpentine bend, with a width W0 of 5-200 μm, a spacing W1 between adjacent bends of 10-200 μm, and a length l1 of each bend in the ITO resistance wire of 1-3 mm; the ITO electrode is square, with a length l2 of 1.4-3.5 mm and a width W2 of 0.5-2 mm.

6. Application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 1, characterized in that: When a short-pulse laser is used to etch the indium tin oxide conductive layer of the ITO glass in step 1, a program is used to control the scanning etching path of the laser; the wavelength of the short-pulse laser is 355 nm ultraviolet light or 532 nm green light, the laser pulse width is fs to ps, the laser repetition frequency is 10-100 kHz, the laser power is 0.1-5 W, the laser spot diameter focused on the ITO glass surface is 10-50 μm, and the laser scanning speed is 100-2000 mm / s.

7. Application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 1, characterized in that: The etcher in step 2 is a plasma etcher or a reactive ion etcher, the radio frequency of the etcher is 13.56 MHz, the power is 100-300 W, the etching time is 0.5-2 h, and the Ar&H2 gas is a mixture of high-purity Ar and H2, and the volume ratio of H2 in the mixture is 1-5%.

8. The application of the ozone sensor based on etching of indium tin oxide film in detecting trace ozone according to claim 1, characterized in that: The annealing treatment in step 3 is performed at a temperature of 300-450°C and for a time of 0.5-24 h.

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