Gas sensor having structurally improved sensing accuracy and method of manufacturing same

Abstract

Disclosed are a gas sensor having structurally improved sensing accuracy and a method of manufacturing same. One aspect of the present embodiment provides a gas sensor comprising: a substrate; a sensing material for desorbing a predetermined gas component to be detected; a heater for separating gas components adsorbed on the sensing material; a first insulating layer disposed on the substrate and electrically separating the substrate from the heater; a sensing electrode configured to receive a signal from the outside to generate an electric field corresponding thereto and sense changes in voltage amplitude and frequency; and a second insulating layer disposed on the heater and electrically separating the heater from the sensing electrode.

Description

Gas sensor with structurally improved sensing accuracy and its manufacturing method

[0001] The present invention relates to a gas sensor with structurally improved sensing accuracy and a method for manufacturing the same.

[0002] The content described in this section merely provides background information for the present embodiment and does not constitute prior art.

[0003] Gas sensors analyze the presence and concentration of specific gaseous components present in the air, such as carbon monoxide (CO), methane (CH4), ethylene (C2H4), or ethane (C2H6).

[0004] Conventional gas sensors input a signal to a sensing unit and detect changes in the signal due to changes in resistance value or electric field that vary accordingly due to the presence of the aforementioned gaseous components. In this way, conventional gas sensors have been able to detect the presence and concentration of the desired gaseous components from changes in the signal.

[0005] However, since the conventional gas sensor structurally has the same terminal for inputting a signal and the terminal for detecting the signal, there was a problem in that the accuracy of detection was low when detecting changes in the signal.

[0006] One embodiment of the present invention aims to provide a gas sensor with structurally improved sensing accuracy and a method for manufacturing the same.

[0007] According to one aspect of the present embodiment, a gas sensor is provided, characterized in that it includes a substrate and a sensing material that desorbs a preset gas component to be detected, a heater that separates the gas components adsorbed on the sensing material, a first insulating layer disposed on the substrate and electrically separating the substrate and the heater, a sensing electrode that receives a signal from the outside and generates an electric field corresponding thereto and senses changes in voltage intensity and frequency, and a second insulating layer disposed on the heater and electrically separating the heater and the sensing electrode.

[0008] According to one aspect of the present embodiment, the heater is characterized in that it separates the adsorbed gas components by applying heat to the sensing material.

[0009] According to one aspect of the present embodiment, the heater is characterized by including an input terminal and a heating unit.

[0010] According to one aspect of the present embodiment, the input terminals are formed at each end of the heating unit, and are characterized in that they receive power to be applied to the heating unit.

[0011] According to one aspect of the present embodiment, the preset gas component is characterized in that it includes carbon monoxide (CO), methane (CH4), ethylene (C2H4) or ethane (C2H6).

[0012] According to one aspect of the present embodiment, the first insulating layer and the second insulating layer are made of SiO2 or SiN. x It is characterized by being implemented as .

[0013] According to one aspect of the present embodiment, the sensing electrode is characterized by including an input terminal, a body, a protruding electrode, and an output terminal.

[0014] According to one aspect of the present embodiment, a gas sensor is provided, characterized in that it includes a power source for applying DC power, a signal generator for receiving DC power from the power source and generating a signal having a frequency for detecting a preset gas component, a sensing unit for receiving an input signal from the signal generator and sensing the presence or absence and concentration of the preset gas component, a filter unit for filtering noise in a sensing value sensed by the sensing unit, an amplifier for amplifying a signal passing through the filter unit, and a detection unit for receiving a signal passing through the amplifier and detecting the presence or absence and concentration of the preset gas component.

[0015] According to one aspect of the present embodiment, the filter unit and amplifier are characterized in that they are included in the number of gas components to be detected.

[0016] According to one aspect of the present embodiment, the signal generator is characterized by generating an AC signal.

[0017] According to one aspect of the present embodiment, the signal generator is characterized in that it generates an AC signal having a frequency suitable for detecting a gas component.

[0018] According to one aspect of the present embodiment, the filter unit is characterized in that it is implemented as a band-pass filter.

[0019] As described above, according to one aspect of the present embodiment, there is an advantage of improving the sensing accuracy of the gas component to be structurally detected.

[0020] FIG. 1 is a drawing illustrating the configuration of a gas sensor according to one embodiment of the present invention.

[0021] FIG. 2 is a diagram illustrating the configuration of a sensing unit according to one embodiment of the present invention.

[0022] Figure 3 is a plan view of a sensing unit according to one embodiment of the present invention.

[0023] FIG. 4 is a drawing illustrating the configuration of a heater according to one embodiment of the present invention.

[0024] FIG. 5 is a drawing illustrating the configuration of a sensing electrode according to one embodiment of the present invention.

[0025] FIG. 6 is a graph illustrating a signal generated by a signal generator and a signal detected by a detection unit according to one embodiment of the present invention.

[0026] FIG. 7 is a diagram illustrating an implementation example of a filter unit, an amplifier, and a detector unit according to one embodiment of the present invention.

[0027] Figures 8 to 12 are drawings illustrating a process of manufacturing a sensing unit according to one embodiment of the present invention.

[0028] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0029] Terms such as first, second, A, and B may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0030] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0031] The terminology used in this application is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. It should be understood that terms such as "comprise" or "have" in this application do not preclude the presence or possibility of addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification.

[0032] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0033] Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0034] In addition, each configuration, process, procedure or method included in each embodiment of the present invention may be shared within a scope that is not technically inconsistent with each other.

[0035] FIG. 1 is a drawing illustrating the configuration of a gas sensor according to one embodiment of the present invention.

[0036] Referring to FIG. 1, a gas sensor (100) according to one embodiment of the present invention includes a power source (110), a signal generator (120), a sensing unit (130), a filter unit (140), an amplifier (150), and a detection unit (160).

[0037] The gas sensor (100) analyzes the presence and concentration of preset gaseous components, such as carbon monoxide (CO), methane (CH4), ethylene (C2H4), or ethane (C2H6), present in the air. The gas sensor (100) applies a signal and measures the intensity of the signal that changes depending on the presence of gas, thereby analyzing which gas is present and in what amount. At this time, the gas sensor (100) significantly improves the accuracy of the detected signal by ensuring that the detected signal is not structurally affected by the input signal.

[0038] The power source (110) supplies power to enable the signal generator (120) to generate a signal. The power source (110) applies DC power to the signal generator (120), thereby enabling the signal generator (120) to generate a desired signal from the power source.

[0039] The signal generator (120) generates a signal having a frequency suitable for the sensing unit (130) to detect a preset gas component. In order to detect ethylene or ethane with a relatively large molecular weight, a direct current signal or an alternating current signal with a relatively small frequency may be applied. However, in order to detect carbon monoxide or methane with a relatively small molecular weight, it is preferable to apply an alternating current signal with a relatively large frequency. The signal generator (120) may selectively apply a signal suitable for detecting a specific gas component, or may scan the aforementioned frequency band and apply a signal so as to detect all gas components.

[0040] The sensing unit (130) receives an input signal from the signal generator (120) and senses the presence or absence and concentration of a preset gas component. The sensing unit (130) has a structure capable of detaching the preset gas component. When the preset gas component is adsorbed by the sensing unit (130), a change occurs in the resistance value of the sensing unit (130) due to the component, which in turn causes a change in the electric field. The sensing unit (130) detects the change in the resistance value or the change in the electric field to detect whether a specific gas component exists in the air and how much of it exists. In addition, as described above, the sensing unit (130) can detect a component corresponding to the frequency of the input signal applied thereto. At this time, the sensing unit (130) can secure high sensing accuracy by including a structure and configuration as described below with reference to FIGS. 2 to 5.

[0041] The filter unit (140) filters out noise within the sensing value of the sensing unit (130). The filter unit (140) is implemented as a band pass filter (BPF) and filters out the remaining noise other than the signal detected by the sensing unit (130). The number of filter units (140) is the number of components to be detected, and only a preset band is passed based on the center frequency corresponding to each component to be detected. Accordingly, each filter unit (140) filters out noise within the sensed sensing value according to the presence of each component.

[0042] The amplifier (150) amplifies the signal (sensing value) that has passed through each filter unit (140). A problem may occur in which the size of the sensing value decreases as it passes through the filter unit (140). This may cause inaccurate detection by the detection unit (160). The amplifier (150) receives the signal (sensing value) that has passed through each filter unit (140) and amplifies it. The amplifier (150) is also implemented in the same number as the number of each component to be detected, similar to the filter unit (140), and amplifies the signal that has passed through each filter unit (140).

[0043] The detection unit (160) receives the signal that has passed through the amplifier (150) and detects the presence or absence and concentration of a preset gas component. If the preset gas component exists, a change occurs in the input signal (of a frequency that affects the corresponding component), and the greater the concentration of the corresponding component (the more corresponding components there are), the greater the occurrence of the change. Considering these circumstances, the detection unit (160) detects whether the sensed value is different from the input signal and, if so, how much it has changed. The detection unit (160) can detect the presence or absence and concentration of the preset gas component based on the detected content. The detection unit (160) may be implemented as many times as the number of each component to be detected, and may detect by receiving each signal that has passed through each amplifier (150), or may include only one, and detect by sequentially or separately receiving each signal that has passed through each amplifier (150).

[0044] FIG. 2 is a drawing showing the configuration of a sensing unit according to one embodiment of the present invention, and FIG. 3 is a plan view of a sensing unit according to one embodiment of the present invention.

[0045] Referring to FIGS. 2 and 3, a sensing unit (130) according to one embodiment of the present invention includes a substrate (210), an insulating layer (220, 240), a heater (230), a sensing electrode (250), and a sensing material (260).

[0046] The substrate (210) provides a space in which each component within the sensing unit (130) is deposited or grown. The substrate (210) may be implemented as a silicon substrate or an aluminum oxide (Al2O3) substrate.

[0047] An insulating layer (220) is disposed on the substrate (210) to electrically isolate the substrate (210) and the heater (230). The heater (230) includes electrodes and can electrically generate heat. Therefore, when the heater (230) and the substrate (210) are disposed in direct contact, a problem of short circuiting between the two may occur. Therefore, an insulating layer (220) is disposed on the substrate (210) to prevent the substrate (210) and the heater (230) from short circuiting. The insulating layer (220) is made of SiO2 or SiN. x can be implemented as

[0048] The heater (230) is disposed on the insulating layer (220) to separate gas components adsorbed on the sensing material (260). When the sensing material (260) is heated (when the temperature of the sensing material increases), the adsorbed gas components can be separated. When the detection of a specific gas component is completed, the heater (230) applies heat to the sensing material (260) so that the detected gas component can be separated from the sensing material (260). Accordingly, the sensing material (260) and the sensing unit (130) including the same can detect newly preset gas components. The heater (230) can be implemented with platinum (Pt), nickel (Ni), tungsten (W), polycrystalline silicon (Poly Si), or ITO. The heater (230) can be implemented as shown in FIG. 4.

[0049] FIG. 4 is a drawing illustrating the configuration of a heater according to one embodiment of the present invention.

[0050] Referring to FIG. 4, a heater (230) according to one embodiment of the present invention includes an input terminal (410, 415) and a heating unit (420).

[0051] Input terminals (410, 415) are formed at each end of the heating unit (420) and receive power to be applied to the heating unit (420).

[0052] The heating unit (420) receives power input from the input terminals (410, 415) and generates heat. The heating unit (420) is implemented with the aforementioned components and generates heat by receiving power. To improve the amount of heat generated per unit area, the heating unit (420) may be arranged in a shape that is bent multiple times.

[0053] Referring again to FIGS. 2 and 3, an insulating layer (240) is disposed on the heater (230) to electrically isolate the heater (230) and the sensing electrode (250).

[0054] The sensing electrode (250) receives a signal generated from the signal generator (120), generates an electric field corresponding to the signal, and senses changes in voltage intensity and frequency. As the sensing electrode (250) has the structure illustrated in Fig. 5, it can sense the changing voltage intensity and frequency while minimizing the influence on the input signal.

[0055] FIG. 5 is a drawing illustrating the configuration of a sensing electrode according to one embodiment of the present invention.

[0056] Referring to FIG. 5, a sensing electrode (250) according to one embodiment of the present invention includes an input terminal (510, 515), a body (520, 525), a protruding electrode (530, 535), and an output terminal (540, 545).

[0057] The input terminals (510, 515) receive a signal generated from a signal generator (120). The input terminals (510, 515) are each implemented at one end of the body (520, 525), and receive a signal generated from the signal generator (120) and transmit it to the body (520, 525) and the protruding electrodes (530, 535).

[0058] The body (520, 525) provides a space in which each configuration within the sensing electrode (250) is implemented, and transmits a signal input from the input terminal (510, 515) to the protruding electrode (530, 535) and the output terminal (540, 545). The body (520, 525) can be implemented with gold (Au), platinum (Pt), or polycrystalline silicon (Poly si).

[0059] The bodies (520, 525) are arranged with a preset interval. Here, the preset interval may mean an interval sufficient to prevent each protruding electrode (530, 535) from contacting the facing bodies (525, 520).

[0060] The protruding electrodes (530, 535) sequentially cross and protrude from each body (520, 525) in the direction of the facing body (525, 520), thereby forming an electric field between adjacent protruding electrodes (530, 535). Since the protruding electrodes (530, 535) are implemented in the above-described form within the body (520, 525), they form an electric field between adjacent protruding electrodes (530, 535) according to an applied signal without physical contact between the bodies (520, 525) and the protruding electrodes (530, 535). In a typical case, an electric field is formed in this manner, and a signal applied along the bodies (520, 525) and the protruding electrodes (530, 535) is transmitted to the output terminals (540, 545). However, when a preset gas component to be detected is adsorbed on the sensing material (260), a change occurs in the resistance value, which in turn causes a change in the electric field formed by the adjacent protruding electrodes (530, 535). Accordingly, a change occurs in the intensity and frequency of the signal transmitted to the output terminal (540, 545) through the body (520, 525) and the protruding electrodes (530, 535).

[0061] Output terminals (540, 545) are implemented at opposite ends of the body (520, 525), respectively, and transmit signals transmitted through the body (520, 525) and the protruding electrodes (530, 535) to the outside. The output terminals (540, 545) are electrically connected to the detection unit (160) through the filter unit (140) and the amplifier (150), so that the signals transmitted to the output terminals (540, 545) are ultimately received by the detection unit (160). At this time, the output terminals (540, 545) are implemented structurally separate from the input terminals (510, 515). In the conventional sensing unit, the same terminal has been used to apply an input signal and detect a detection signal. However, when the configuration for applying a signal and the configuration for detecting a signal are electrically connected to the same terminal and operate separately, there may be cases where the applied signal is applied to the configuration for detecting a signal instead of the detection signal that should actually be detected, and even if the applied signal is not configured entirely for detecting a signal, a problem may occur in which it affects the detection signal and acts as noise. Accordingly, in the conventional sensing unit, cases in which the presence of a gas component to be detected is detected frequently occur even when the component is not present, or vice versa. However, the sensing unit (130) structurally separates the input terminals (510, 515) and the output terminals (540, 545), thereby fundamentally preventing the occurrence of the aforementioned problem.

[0062] Referring back to FIGS. 2 and 3, the sensing material (260) is placed on the sensing electrode (250) and desorbs a preset gas component. The sensing material (260) is electrically connected to the sensing electrode (250) and acts as a resistor. At this time, when the preset gas component is adsorbed onto the sensing material (260), a change occurs in the resistance value felt by the sensing electrode (250) due to the component, and the magnitude of the resistance value that changes also varies depending on the concentration (amount) of the adsorbed component. Accordingly, when the preset gas component is adsorbed onto the sensing material (260) as described above, a change may occur in the intensity and frequency of the detection signal transmitted to the output terminal (540, 545). Meanwhile, the sensing material (260) adsorbs a preset gas component at room temperature, and when heat is applied by the heater (230) and the temperature rises, the preset gas component can be separated. Accordingly, the sensing material (260) can sense a desired component when desired. The sensing material (260) can be implemented with tungsten trioxide (WO3) or tin oxide (SnO2) so as to be able to adsorb the aforementioned gaseous components (carbon monoxide (CO), methane (CH4), ethylene (C2H4), or ethane (C2H6)). In particular, when the sensing material (260) is implemented with tin oxide, it can be implemented with tin oxide doped with titanium dioxide (TiO2).

[0063] FIG. 6 is a graph illustrating a signal generated by a signal generator and a signal detected by a detection unit according to one embodiment of the present invention, and FIG. 7 is a diagram illustrating an implementation example of a filter unit, an amplifier, and a detection unit according to one embodiment of the present invention.

[0064] As illustrated in Fig. 6(a), the signal generator (120) can generate an AC signal and apply it to the sensing unit (130) to detect even carbon monoxide or methane with relatively small molecular weights. As described above, the signal generator (120) can generate signals of appropriate frequencies for detecting specific components, or can generate signals by scanning a frequency band and adjusting the frequency.

[0065] When an AC signal is applied in this way, a signal is detected in the detection unit (160) as shown in Fig. 6(b). The relatively low-frequency band is a signal generated by a gas component with a relatively large molecular weight and has a relatively large intensity (I). On the other hand, the relatively high-frequency band is a signal generated by a gas component with a relatively small molecular weight and has a relatively small intensity. In this way, the signal detected in the detection unit (160) varies in frequency and intensity (sensitivity) depending on the molecular weight of the gas component to be detected.

[0066] Considering these circumstances, the filter unit (140), amplifier (150), and detection unit (160) can be implemented as shown in FIG. 7a or FIG. 7b.

[0067] As shown in Fig. 7a, the filter unit (140), amplifier (150), and detection unit (160) are each provided with the number of gas components to be detected, so that signals by each component can be separated and processed.

[0068] As illustrated in Fig. 6(b), it can be confirmed that the frequency and intensity of the detected signal vary depending on the type of gas component adsorbed on the sensing unit (130). Accordingly, the filter unit (140) can separate noise by passing only a certain area centered on the frequency band of the detection signal corresponding to each component to be detected.

[0069] The amplifier (150) amplifies the signal that has passed through each filter section (140). The amplification ratio of the amplifier (150) also varies depending on the frequency band. Accordingly, each amplifier (150) optimally amplifies each signal of different frequencies that has passed through the filter section (140).

[0070] The detection unit (160) receives a signal that has passed through each amplifier (150) and detects the presence or absence and concentration of a preset gas component. As illustrated in Fig. 6(b), the presence or absence and concentration of a preset gas component are detected based on whether a signal having a certain intensity is detected in a specific frequency band.

[0071] Alternatively, as illustrated in FIG. 7b, the filter unit (140) and amplifier (150) are provided in the number of gas components to be detected, and only one detection unit (160) is included so that detection can be performed by receiving a signal that has passed through each amplifier (150).

[0072] The detection unit (160) may directly and sequentially receive the signals that have passed through each amplifier (150), or may sequentially receive the signals that have passed through each amplifier (150) using a separate component (not shown), for example, a switch. The detection unit (160) may determine whether and how much of a gaseous component is present based on whether a signal with a certain intensity is detected in a certain frequency band.

[0073] As the gas sensor (100) includes the aforementioned configuration, each gas component to be detected can be detected when it is introduced, and even if some or all of the gas components are introduced mixed, it is possible to detect whether the gas components are mixed and which components are mixed.

[0074] Figures 8 to 12 are drawings illustrating a process of manufacturing a sensing unit according to one embodiment of the present invention.

[0075] Referring to FIG. 8, an insulating layer (220) is deposited or grown on a substrate (210).

[0076] Referring to FIG. 9, a heater (230) is deposited or grown on an insulating layer (220).

[0077] Referring to FIG. 10, an insulating layer (240) is again deposited or grown on the heater (230).

[0078] Referring to Fig. 11, a sensing electrode (250) is deposited or grown on an insulating layer (240).

[0079] Referring to FIG. 12, a sensing material (260) is deposited or grown on a sensing electrode (250).

[0080] The above description is merely an example of the technical idea of ​​the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of ​​the present embodiment, but rather to explain it, and the scope of the technical idea of ​​the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present embodiment.

[0081]

[0082] This patent is the result of research conducted with support from the Small and Medium Business Technology Information Promotion Agency (SME Information Promotion Agency) funded by the Korean government (Ministry of SMEs and Startups) (Project ID: 1425172723, Subproject ID: S3316595, Project Name: Development of Integrated Off-Gas Sensor and Fire Sign Prediction Technology for ESS Fire Prevention).

[0083]

[0084] CROSS-REFERENCE TO RELATED APPLICATION

[0085] This patent application claims priority under 35 USC § 119(a) to Korean Patent Application No. 10-2024-0051392, filed in Korea on April 17, 2024, the entire contents of which are incorporated by reference herein. Furthermore, this patent application claims priority in countries other than the United States for the same reasons, the entire contents of which are incorporated by reference herein.

Claims

1. In gas sensors, substrate; A sensing material that desorbs a preset gas component to be detected; A heater that separates gas components adsorbed on the sensing material; A first insulating layer disposed on the substrate and electrically isolating the substrate and the heater; A sensing electrode that receives a signal from the outside, generates an electric field corresponding to the signal, and senses changes in voltage intensity and frequency; and A second insulating layer disposed on the heater to electrically isolate the heater and the sensing electrode. A gas sensor characterized by including:

2. In paragraph 1, The above heater, A gas sensor characterized in that the adsorbed gas components are separated by applying heat to the sensing material.

3. In paragraph 1, The above heater, A gas sensor characterized by including an input terminal and a heating unit.

4. In paragraph 3, The above input terminal is, A gas sensor characterized in that it is formed at each end of the heating unit and receives power to be applied to the heating unit.

5. In paragraph 1, The above preset gas components are: A gas sensor characterized by containing carbon monoxide (CO), methane (CH4), ethylene (C2H4) or ethane (C2H6).

6. In the gas sensor, A power source that supplies DC power; A signal generator that receives DC power from the above power source and generates a signal having a frequency for detecting a preset gas component; A sensing unit that receives an input signal from the signal generator and senses the presence or absence and concentration of a preset gas component; A filter unit that filters out noise in the sensing value sensed by the above sensing unit; An amplifier that amplifies a signal that has passed through the above filter section; and A detection unit that receives a signal passed through the above amplifier and detects the presence or absence and concentration of a preset gas component. A gas sensor characterized by including:

7. In paragraph 6, The above filter section and amplifier, A gas sensor characterized in that it includes the number of gas components to be detected.

8. In paragraph 6, The above signal generator, A gas sensor characterized by generating an AC signal.

9. In paragraph 8, The above signal generator, A gas sensor characterized by generating an alternating current signal having a frequency suitable for detecting a gaseous component.

10. In paragraph 6, The above filter part, A gas sensor characterized by being implemented with a bandpass filter.

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