A single-pass porous substrate for a semiconductor gas sensor

Abstract

The application relates to a single-pass porous substrate of a semiconductor gas sensor, characterized in that the single-pass porous substrate comprises a functional area for detecting a sensing reaction of a target detection gas at a first temperature and a non-functional area for filtering at least part of impurity gases other than the target detection gas based on a sensing reaction at a temperature lower than the first temperature, the non-functional area being used for corner compensation of the functional area when the functional area is deformed in a high-temperature environment; the functional area and the non-functional area are connected through a plurality of suspensions to reduce heat loss of the functional area; the suspensions can conduct heat on the functional area to the non-functional area through heat conduction; the displacement trend of the functional area when swelling under a heated condition can be limited under the tensile stress of the non-functional area connected with the functional area through the suspensions, so that the functional area can be kept matched with a heating area providing a heat source of the functional area. The application can reduce the proportion of impurity gases in mixed gases entering the functional area, thereby improving sensing efficiency.

Description

[0001] The original basis for this divisional application is patent application No. 202310383610.3, filed on April 10, 2023, entitled "A Semiconductor Gas Sensor Based on a Single-Pass Porous Substrate", which claims priority to patent application No. 202310158176.9, with a priority date of February 23, 2023. Technical Field

[0002] This invention relates to the field of sensor devices, and more particularly to a single-channel porous substrate for a semiconductor gas sensor. Background Technology

[0003] In recent years, major media outlets have frequently reported on sudden toxic gas leaks, leading to increased public concern about detecting such leaks. Toxic gases such as carbon monoxide, hydrogen sulfide, carbon dioxide, and sulfur dioxide pose significant health risks. However, traditional toxic gas detection methods have not been widely adopted due to their long testing times, the need for specialized personnel to operate the equipment, their complexity, and their difficulty in on-site use. Generally, non-professionals are the primary users of toxic gas detection devices. Therefore, to enable rapid detection of toxic gases over large areas, these devices must be fast-responding, easy to operate, miniaturized, and portable.

[0004] Gas sensors, especially resistive gas sensors based on metal-oxide-semiconductor (MOX) semiconductors, are widely used in environmental pollution monitoring, hazardous gas leak detection, and chemical detection in production and daily life. With the development of Internet of Things (IoT) technology and the advancement of precision medicine strategies, traditional MOX gas sensors have enormous application potential in emerging fields such as wearable portable devices, point-of-care testing (POCT), smart cities, and smart homes, but also face many challenges.

[0005] CN105900236A discloses a semiconductor sensor device comprising: a substrate; an unsuitable seed layer located above the substrate; at least one electrode located above the unsuitable seed layer; and a porous sensing layer directly supported by the unsuitable seed layer and in electrical communication with the at least one electrode, the porous sensing layer defining a plurality of grain boundaries formed by spaced nucleation on the unsuitable seed layer using atomic layer deposition.

[0006] CN113092542A discloses a planar nano gas sensor, array, and fabrication method thereof, relating to the field of gas sensor technology. The gas sensor, from top to bottom, comprises a planar sensing electrode, a sensing layer, an electrically insulating layer, and a micro-heater. The sensing layer is formed by depositing nanoscale sensing material within a dual-hole substrate. The dual-hole substrate is composed of multiple dual-hole nanotubes. Each dual-hole nanotube is open at one end and connected to the other. The nanoscale sensing material is deposited on the wall of the dual-hole nanotubes. The heating area of ​​the micro-heater overlaps vertically with the sensing area of ​​the planar sensing electrode.

[0007] Most MOX gas sensors currently on the market suffer from high power consumption and poor selectivity. These gas sensors are mostly planar two-dimensional thin-film structures and require high-temperature operation (300-400℃). They rely on heating to activate the adsorption capacity with the target gas, thereby improving their response sensitivity. This makes them unsuitable for low-power applications and also presents challenges in long-term stability and lifespan. Furthermore, with the rapid pace of societal development, the integration of wireless connectivity, network technology, and electronic technology is becoming increasingly sophisticated, leading to higher demands for intelligence and user-friendliness. Combining gas sensors with wireless connectivity and network technology for simultaneous and real-time detection of toxic gases greatly facilitates timely detection. Therefore, developing a miniaturized, reliable, portable, highly sensitive detection system capable of real-time monitoring of various toxic gases is of paramount importance.

[0008] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventors studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0009] To address at least some of the shortcomings of the prior art, this application provides a semiconductor gas sensor based on a single-channel porous substrate, comprising at least a sensing layer. Since the gas is detected based on a deposited gas-sensitive material, the sensing layer is characterized by being able to divide into a functional region for detecting a target gas based on a sensing response at a first temperature and a non-functional region for filtering at least a portion of impurity gases other than the target gas based on a sensing response at a temperature lower than the first temperature. The functional and non-functional regions are connected by a plurality of suspensions, wherein the suspensions can conduct heat from the functional regions to the non-functional regions via thermal conduction. Research shows that even though most of the heat generated by the heating electrode is concentrated in the functional region, the non-functional region, under the combined effect of the residual heat radiated by the heating electrode and the heat conducted through the suspensions in the functional region, forms a temperature field where the temperature increases closer to the suspension connection and the heating electrode. The second temperature at the highest point in this temperature field is lower than the first temperature due to heat loss during heat transfer. Therefore, the non-functional region can also form a sensing response for certain gas molecules (e.g., hydrogen and carbon monoxide) that are not highly sensitive to temperature conditions. When the target molecule to be detected requires a high temperature, some impurity gases that do not require high temperatures and are not needed for detection may also enter the functional region and cause a sensing reaction, affecting the sensing results. By applying different temperatures to the non-functional region and the functional region, impurity gases can be removed upon entering the non-functional region, thus reducing the proportion of impurity gases in the mixed gas entering the functional region and improving sensing efficiency.

[0010] Preferably, the sensing layer can adjust the number of suspensions based on the relationship between the first temperature at which the target gas reacts and the second temperature at which the impurity gas reacts. The number of suspensions decreases as the difference between the second and first temperatures increases, with a minimum number of suspensions of 1. More suspensions allow for greater heat transfer to the non-functional area, resulting in a higher overall temperature and a higher maximum achievable temperature in the non-functional area. When the temperature required for the impurity gas to react is high, even close to the first temperature at which the target gas reacts, the temperature in the non-functional area can be increased by adding more suspensions to ensure that the impurity gas can be sensed and filtered in the non-functional area. When the second temperature at which the impurity gas reacts is higher than the first temperature, the first temperature is insufficient for the sensor to detect the impurity gas, thus not affecting the sensing result. Furthermore, the non-functional area is larger than the functional area in this invention, making it easier for the non-functional area to filter and remove the impurity gas.

[0011] Preferably, the end of the suspension connected to the functional area is located at a corner far from the geometric center of the functional area. This ensures that most of the heat conducted from the suspension to the non-functional area originates from the edge far from the core of the functional area. The two connection angles formed by the suspension and the functional area are obtuse angles, ensuring consistent deformation during thermal expansion. Obtuse angles allow for unrestricted deformation during thermal expansion at the connection point, reducing the risk of breakage due to high thermal stress. Furthermore, setting the two connection angles to the same value in this invention further avoids the problem of fracture caused by unbalanced thermal stress on the left and right sides of the connection due to different angles.

[0012] Preferably, the displacement tendency of the functional area when it expands under heating conditions can be limited by the tensile stress of the non-functional area connected to the functional area via the suspension, so that the functional area can maintain a match with the heating area that provides the heat source for the functional area. Because the functional area is at a higher temperature, the expansion effect during heating causes displacement, and the higher the temperature, the greater the displacement. After displacement, the functional area is no longer matched with the heating area, which can easily lead to uneven heating and poor sensing performance. To avoid this problem, this invention connects the functional area to the non-functional area via the suspension. By fixing the non-functional area or using the friction of the non-functional area, the displacement of the functional area can be limited, ensuring that the functional area remains within the heating area and that the sensing response of the functional area functions normally.

[0013] Preferably, the sensing layer can be formed from a single-channel porous substrate with sensing particles deposited on its surface. In particular, a specific example of a single-channel porous substrate can be a single-channel porous alumina substrate. Specifically, the single-channel porous alumina substrate can be formed by arranging multiple single-pore nanotubes, each nanotube having an opening communicating with the outside. The other end of the nanotube opposite the opening is connected to the aluminum substrate through a barrier layer, and sensing particles are deposited inside the nanotube and near the opening side of the nanotube.

[0014] Preferably, the semiconductor sensor further includes a sensing electrode disposed on the side of the functional region with an opening. The sensing electrode includes at least a pair of interdigitated electrodes that are electrically connected to the sensing particles deposited on the functional region. When an external voltage source is applied, the electrical changes of the sensing particles when they undergo a sensing response can be transmitted based on the sensing electrode.

[0015] Preferably, the semiconductor sensor further includes a heating layer and an isolation layer. The isolation layer is disposed between the heating layer and the sensing layer. The isolation layer can transfer the heat generated by the heating layer to the non-functional area in a uniform conduction manner. The isolation layer has reserved heating electrode holes for the heating layer to be led out to an external heating power supply.

[0016] Preferably, the heating layer includes a heating electrode and a thermal resistance wire. The heating electrode is electrically connected to the thermal resistance wire via a connecting wire. The shape of the heating electrode matches the heating electrode hole, so that the heating electrode can be nested in the heating electrode hole and maintain electrical connection with an external heating power supply. The heating area formed by the meandering thermal resistance wire matches the shape of the functional area, so that the thermal resistance wire can heat the functional area as a whole.

[0017] Preferably, the sensor further includes a support layer disposed on the other side of the thermal resistance wire relative to the sensing layer. The support layer is provided with a bearing area to prevent the heat generated by the thermal resistance wire from being dissipated from one side of the support layer. The bearing area is configured to match the heating area formed by the thermal resistance wire.

[0018] Preferably, the sensor further includes a substrate, which is disposed on the other side of the support layer. The substrate has a through-hole that can improve the bending resistance of the substrate. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the sensing electrode of the present invention;

[0021] Figure 3 This is a schematic diagram of the heating layer of the present invention;

[0022] Figure 4 This is a schematic diagram of the sensor layer partitioning of the present invention;

[0023] Figure 5 This is a cross-sectional view of the sensing layer of the present invention.

[0024] List of reference numerals

[0025] 1: Sensing electrode; 11: Interdigitated electrode; 12: Interdigitated region; 13: Interdigitated end; 14: Interdigitated panel; 2: Sensing layer; 21: Functional area; 22: Non-functional area; 23: Suspension; 24: Channel; 25: Aluminum substrate; 26: Oxide layer; 27: Barrier layer; 3: Sensing particle; 4: Isolation layer; 41: First overlapping area; 42: Heating electrode hole; 5: Heating layer; 51: Heating electrode; 52: Connecting wire; 53: Thermal resistance wire; 6: Support layer; 61: Second overlapping area; 7: Substrate; 71: Hole. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings.

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a semiconductor gas sensor based on a single-channel porous substrate, such as... Figure 1 As shown, it can include the following parts stacked from top to bottom:

[0029] Sensing electrode 1, which is located at the very top of the entire sensor, is used to transmit electrical signals when the sensor generates a sensing response.

[0030] The sensing layer 2 is disposed on the bottom layer of the sensing electrode 1 in such a way that it at least partially overlaps the sensing electrode 1 vertically, and has sensing particles 3 for sensing reactions with the gas to be detected.

[0031] An isolation layer 4 is disposed on the side of the sensing layer 2 opposite to the sensing electrode 1, and is used to uniformly and stably transfer the heat required for the sensing particles 3 to undergo a sensing response to the sensing layer 2.

[0032] The heating layer 5, which is located at the bottom of the isolation layer 4, is used to provide heat to the sensing layer 2. This heat can be evenly conducted to the sensing layer 2 after being blocked by the isolation layer 4.

[0033] A support layer 6 is disposed on the side of the heating layer 5 opposite to the isolation layer 4 to prevent the heat generated by the heating layer 5 from being lost from the side located on the support layer 6.

[0034] Substrate 7, disposed at the bottom layer of the entire sensor structure, serves as a carrier structure to support all the above-mentioned layers. According to a preferred embodiment, combined with... Figure 1 and Figure 5 Sensing electrode 1 is disposed on the surface of sensing layer 2. Sensing electrode 1 is in contact with and electrically connected to sensing particles 3 on sensing layer 2. Under the premise that the voltage across sensing electrode 1 is constant, when sensing particles 3 come into contact with the gas to be detected that can react with them, a sensing reaction occurs, causing a change in their own resistance, which in turn changes the current in the circuit. By monitoring the change in current within the circuit, it can be determined whether a gas capable of reacting with the sensor exists in the scene where the sensor is located. Preferably, as shown... Figure 2As shown, the sensing electrode 1 consists of a pair of interdigital electrodes 11 whose combined shape matches the functional area 21 of the sensing layer 2. The interdigital electrodes 11 are arranged symmetrically and without contact. The interdigital interval 12 between the two interdigital electrodes 11 is electrically connected to the interdigital ends 13 of the interdigital electrodes 11 through the sensing particles 3 on the sensing layer 2, so that a closed loop is formed between the two interdigital electrodes 11. Specifically, the interdigital electrode 11 is constructed as a structure in which two parallel wires extend towards each other near their ends, and optionally, the number of branch wires can be any value greater than two.

[0035] According to a preferred embodiment, a sensing electrode 1 is deposited on the surface of a sensing layer 2. Specifically, a particular example of the sensing layer 2 can be a single-pass porous alumina substrate. Specifically, the orifice of the single-pass porous alumina substrate faces the sensing electrode 1, and an interdigitated region 12 formed by two interdigitated electrodes 11 that are centrally symmetrically embedded in each other is deposited at the orifice position of the single-pass porous alumina substrate. The two interdigitated electrodes 11 achieve electrical connection by contacting the sensing particles 3 within the interdigitated region 12 after being deposited on the surface of the sensing layer 2. The sensing particles 3 within the interdigitated region 12 include sensing particles 3 located on the surface outside the orifice and sensing particles 3 deposited on the inner wall of the single-pass porous alumina substrate within the orifice. Preferably, the interdigitated region 12 can be any shape that can be conceived by those skilled in the art, matching the contour formed by its mating interdigitated electrodes 11. Here, it is set as a triangle. The two interdigitated electrodes 11 are led out through their respective interdigitated panels 14, which are used to connect to an external voltage source.

[0036] According to a preferred embodiment, the sensing layer 2 can be formed from a single-pass porous alumina substrate with sensing particles 3 deposited on its surface. It should be understood that the single-pass porous alumina substrate described in this invention is merely a preferred example of the sensing layer 2. In some alternative embodiments, the single-pass porous substrate or sensing layer 2 described in this invention can also be formed from one or more of titanium oxide, silicon oxide, tantalum oxide, zirconium oxide, or gallium nitride.

[0037] According to a preferred embodiment, taking a single-pass porous alumina substrate as an example, the single-pass porous alumina substrate can be composed of multiple single-pore nanotubes, each nanotube having an opening communicating with the outside. In particular, besides the single-pass porous structure, the alumina substrate can also be a porous double-pass structure, that is, a double-pass alumina substrate is composed of multiple openings connected to each other at both ends. A common single-pass porous alumina substrate has a honeycomb structure, which is composed of hundreds, thousands, or even tens of thousands of regular hexagonal prism-shaped oxide units. For example... Figure 5As shown, each regular hexagon has a circular channel 24 in the center. The size of the channel 24 is generally at the nanometer level, and the channel 24 is roughly perpendicular to the surface. The pore size is uniform yet relatively adjustable, with a simple structure and an ordered array. A barrier layer 27, in a hemispherical shape, is located between the aluminum substrate 25 and the oxide layer 26. This special structure makes the fabrication process of the single-channel porous alumina substrate simple, inexpensive, and suitable for assembling various materials. The ratio between the assembled deposited material and the morphology of the particles in the single-channel porous alumina substrate is closely related to the performance of the nanomaterial. The single-channel porous alumina substrate can be prepared using a two-step anodizing method. Due to the high temperature resistance, high strength, and monodisperse pore size of this substrate, it is an ideal method for preparing nano-alumina materials.

[0038] According to a preferred embodiment, the sensing particle 3 is a nano-zinc oxide material. Preferably, the sensing particle 3 can also be a gas-sensitive material such as tin dioxide or tungsten trioxide (when a gas comes into contact with the gas-sensitive material, it can cause changes in the electrical properties of the gas-sensitive material, such as an increase or decrease in resistance). The sensing particle 3 is disposed on the inner wall of the nanotubes and the surface of the nanotube pores of the single-channel porous substrate by adsorption deposition. The single-channel porous substrate has a high specific surface area, which can contact and adsorb as many sensing particles 3 as possible and greatly increase the spread area of ​​the sensing particles 3, making it easier for the gas molecules to be detected to contact the sensing particles 3 and react with them.

[0039] According to a preferred embodiment, when the sensing particle 3 comes into contact with the target gas molecules capable of a sensing reaction, the target gas gains or loses electrons due to its oxidizing and reducing properties. This changes the electrical resistance of the sensing particle 3, alters the current flowing through it, and changes the current magnitude on the sensing electrode 1 electrically connected to the sensing particle 3. Therefore, by monitoring the degree of current change, it can be determined whether the sensing particle 3 has come into contact with the target gas molecules capable of a sensing reaction. Furthermore, by controlling the temperature environment, the sensing particle 3 can be controlled to only react with the target molecules to be detected.

[0040] like Figure 4The single-channel porous substrate of the sensing layer 2 can be divided into a functional area 21 and a non-functional area 22. The functional area 21 and the non-functional area 22 are connected by a suspension 23. Sensing particles 3 are deposited on both the functional area 21 and the non-functional area 22. The shape of the functional area 21 is adapted to the shape of the sensing electrode 1, so that the shape of the functional area 21 can match the interdigital region 12. Here, the shape of the functional area 21 is set as a triangle matching the contour of the sensing electrode 1. The non-functional area 22 is used for angular compensation when the functional area 21 deforms in a high-temperature environment. Only a single suspension 23 is set to connect with the functional area 21 to reduce the heat loss of the functional area 21. The functional area 21 needs to be at a high temperature when a sensing response occurs - denoted as the first temperature. Due to the difference in Young's modulus and thermal expansion coefficient of the constituent materials of the functional area 21 and the sensing electrodes 1 and the isolation layer 4 stacked on both sides, the surface stress of the functional area 21 will increase under high-temperature conditions. The stress at the connection with the suspension 23 is relatively large, which is prone to cracking and damage. This can be improved by angular compensation. The non-functional area 22, suspension 23, and functional area 21 are integrally formed structures. Preferably, the non-functional area 22, suspension 23, and functional area 21 can be separated from the complete single-through porous substrate by cutting.

[0041] According to a preferred embodiment, the sensing current during a sensing response is mainly distributed on the sensing particles 3, including the surface of the substrate pores and the sensing particles 3 within the substrate nanopores. In this invention, the contact surface between the sensing electrode 1 and the sensing layer 2 is the overlapping area of ​​the interdigitated region 12 of the sensing electrode 1 and the functional region 21 of the sensing layer 2. That is, the area where the sensing response occurs is mostly concentrated on the nanopore walls with a high unfolded area, with a small portion located within the interdigitated region of the sensing electrode 1.

[0042] According to a preferred embodiment, an isolation layer 4 is disposed at the bottom of the sensing layer 2 to isolate the sensing layer 2 from the heating layer 5. The isolation layer 4 prevents the sensing particles 3 from malfunctioning due to excessively rapid temperature changes in the heating layer 5. Excessive temperature changes can lead to large variations in thermal stress and rapid thermal expansion, easily causing material deformation and fracture. The isolation layer 4, while ensuring heat conduction, also maintains electrical isolation between the sensing layer 2 and the heating layer 5. The isolation layer 4 can be formed from a silicon oxide layer structure.

[0043] According to a preferred embodiment, the isolation layer 4 is provided with a first overlapping area 41 for connecting the wires of the interdigital panel 14 portion, including a mating functional area 21, a suspension 23, and interdigital electrodes 11. Figure 1As shown, the first overlapping area 41 is formed by cutting away several trapezoids from the isolation layer, where the perpendicular bisectors intersect at a point and the shorter sides face each other. In this invention, the first overlapping area 41 is formed by removing three trapezoids. The triangular region enclosed by the trapezoids matches the shape of the functional area 21, and the area of ​​the triangular region is slightly larger than the area of ​​the functional area 21 to ensure that the functional area 21 is completely within the triangular region. A reserved area is reserved between adjacent trapezoids for matching and overlapping with some of the wires of the suspension 23 and the interdigitated electrode 11.

[0044] According to a preferred embodiment, the heating layer 5 is disposed on the side of the insulating layer 4 opposite to the sensing layer 2. For example... Figure 3 As shown, the heating layer 5 includes a heating electrode 51 and a thermal resistance wire 53. The thermal resistance wire 53 is connected to the heating electrode 51 via a connecting wire 52. The present invention primarily utilizes the thermal resistance wire 53 to provide the heat source required for the entire sensor's sensing response. The thermal resistance wire 53 is formed by meandering along a triangular region matching the first overlapping area 41 from a material with high resistivity. This allows the thermal resistance wire 53 to have a relatively long length, enabling concentrated heating of the functional area 21 of the sensing layer 2 through the isolation layer 4, while maintaining a fixed overall shape. The connecting wire 52 can be made of the same material as the thermal resistance wire 53. Even though the connecting wire 52 generates heat when current passes through it, the relatively long heat-generating length of the thermal resistance wire 53 results in more concentrated heat, thus minimizing the impact of the heat from the connecting wire 52 on the sensing response of the functional area 21. The economic benefits of integrally generating the thermal resistance wire 53 and the connecting wire 52 without requiring additional wires for electrical connection to the thermal resistance wire 53 are the highest, saving material waste during manufacturing. The connecting wire 52 is led out to the heating electrode 51 by overlapping into a reserved area. The heating electrode 51 is preferably rectangular in structure, and its relatively large area makes it easy to make contact with a voltage source for electrical connection. The heating electrode 51 is nested in the isolation layer 4 through the pre-reserved heating electrode hole 42 and disposed on the isolation layer 4, so that one side of the heating electrode 51 is exposed, which facilitates the connection of the heating voltage source.

[0045] According to a preferred embodiment, the heating area formed by the meandering thermal resistance wire 53 matches the shape of the functional area 21, enabling the thermal resistance wire 53 to heat the functional area 21 as a whole. The heat generated by the thermal resistance wire 53 is collected and evenly conducted to the functional area 21 located on one side of the isolation layer 4 as it passes through the isolation layer 4. This prevents the heat generated by the thermal resistance wire 53 from directly acting on the functional area 21, avoiding uneven heating and thermal stress imbalance that could lead to deformation of the functional area 21 or detachment of the sensing particles 3 from the functional area 21.

[0046] According to a preferred embodiment, a support layer 6 is disposed at the bottom of the heating layer 5. A second overlapping region 61 is disposed on the support layer 6 corresponding to the first overlapping region 41. The shape and size of the second overlapping region 61 match those of the first overlapping region 41. The second overlapping region 61 serves as a carrier region for the thermal resistance wire 53 when the heating layer 5 is deposited on the support layer 6. The second overlapping region 61 includes three cantilever beams for connecting to the remaining areas of the support layer 6. When the heat generated by the heating layer 5 is transferred to the carrier region, the heat conduction rate through the cantilever beams is relatively slow because the carrier region is only connected by three cantilever beams. This allows the carrier region to concentrate the heat radiated from the heating layer 5 towards the support layer 6, facilitating the temperature of the functional area 21 adapted to the first overlapping region 41 and the second overlapping region 61 to reach the first sensing temperature. The support layer 6 can be formed by slotting a silicon nitride or silicon oxide layer structure.

[0047] According to a preferred embodiment, the substrate 7 is located at the bottom of the entire sensor device to improve the overall physical strength of the sensor. For example... Figure 1 As shown, the substrate 7 is a cubic structure with a relatively high thickness. A slotted hole 71 is formed on the substrate 7, extending vertically through the entire substrate. In this invention, the slotted hole 71 is shaped as a triangular structure with high stability. Preferably, the shape of the slotted hole 71 can also be square, trapezoidal, or other shapes conceived by those skilled in the art. By slotting the substrate 7, its bending resistance can be increased, further avoiding the risk of the sensor device bending upon impact, thereby further improving the reliability of the sensor device.

[0048] The shape of the notch 71 matches the first overlapping region 41 and the second overlapping region 61, and the size of the triangle of the notch 71 is larger than that of the first overlapping region 41, so that the sensor device passes through the notch 71, the second overlapping region 61, the thermal resistance wire 53, the first overlapping region 41, and the sensing layer 2 sequentially from bottom to top. The gas to be detected can enter from one side of the sensor device and exit from the other side, and the device has strong gas flow, making it easier for the gas to be detected to enter for detection. Preferably, in order to provide higher physical strength, the substrate 7 is preferably selected as a silicon substrate. In particular, when the substrate 7 of the present invention is made of silicon material, such as Figure 1 The support layer 6 shown may be unnecessary. However, when the substrate 7 is selected from one or more of sapphire, gallium nitride, or silicon carbide, Figure 1 The support layer 6 shown is usually necessary, taking into account the electrical insulation between the substrate 7 and other layer structures.

[0049] According to a preferred embodiment, the non-functional area 22 of the sensing layer 2 is connected to the functional area 21 via a suspension 23. When the functional area 21 is heated by the thermal resistance wire 53, due to the differences in Young's modulus and coefficient of thermal expansion of the materials in each layer, the functional area 21 of the sensor will experience significant thermal stress and deformation at high temperatures. Excessive thermal stress can affect the stability of the sensor, and may even lead to problems such as breakage at the suspension 23 connection or membrane cracking in the membrane structure formed by the sensing particles 3 during use, directly impacting the reliability and lifespan of the sensor. During heating, the functional area 21 deforms and displaces due to the thermal stress, with higher temperatures resulting in greater deformation and displacement. At a maximum temperature of 500 degrees Celsius, the displacement of the functional area 21 can reach 1.5 μm. Under prolonged thermal deformation, the position of functional region 21 will inevitably change, no longer overlapping with the first overlap region 41 where the heating electrode 51 is located. The heat generated by the heating electrode 51 can only heat a portion or a small portion of functional region 21, resulting in uneven temperature distribution and further causing the membrane structure on functional region 21 to detach and fail. This invention fixes the position of functional region 21 by using a suspension 23 to connect the functional region to the non-functional region 22 and the non-functional region 22 to the isolation layer 4. When functional region 21 expands and deforms due to heat, its displacement tendency is limited by the non-functional region 22 through the suspension 23, ensuring it remains in a position matching the heating electrode 51.

[0050] The non-functional region 22 can receive heat radiated from the heating electrode 51 through the trapezoidal slot on the insulating layer 4 and heat conducted from the functional region 21 to the non-functional region 22 through the suspension 23, reaching a second temperature required for a sensing reaction to occur in a portion of the non-functional region 22. The highest temperature that can be reached in the second temperature is lower than the first temperature at which the functional region 21 undergoes a sensing reaction. The sensing particles 3 can react with different types of gas molecules at different temperatures. For example, the catalytic ignition temperature of methane is usually above 400 degrees Celsius, while the catalytic ignition temperature of hydrogen, carbon monoxide, or other alkanes is usually below 260 degrees Celsius. Studies have shown that even though most of the heat generated by the heating electrode 51 is concentrated in the functional area 21, the non-functional area 22, under the combined effect of the residual heat radiated by the heating electrode 51 and the heat conducted through the suspension 23 to the functional area 21, forms a temperature field where the closer the distance between the suspension 23 and the heating electrode 51, the higher the temperature. The second temperature at the highest point in this temperature field is lower than the first temperature due to heat loss during heat transfer, and the overall temperature reaches 300 degrees Celsius. Therefore, the non-functional area 22 can also form a sensing response for some gas molecules that do not require high temperature conditions (such as hydrogen and carbon monoxide). When the target molecule to be detected requires a high temperature, some impurity gases that do not require high temperature conditions will also enter the functional area 21 and undergo a sensing response, affecting the sensing results. By applying different temperatures to the non-functional area 22 and the functional area 21, impurity gases can be removed upon entering the non-functional area 22, thus reducing the proportion of impurity gases in the mixed gas entering the functional area 21 and improving sensing efficiency. Furthermore, the area of ​​the non-functional region 22 is much larger than that of the functional region 21, making it easier for the non-functional region 22 to come into contact with impurity gases in the mixed gas and remove them based on a sensing reaction. When entering the sensor, some of the impurity gases that can undergo a sensing reaction on the non-functional region 22 are adsorbed in the non-functional region 22 in the form of a sensing reaction, increasing the proportion of the gas to be detected in the mixed gas entering the sensor. This increases the probability that the functional region 21 can undergo a sensing reaction with the gas to be detected, thereby improving the sensitivity of the sensor.

[0051] Specifically, when the sensor is set up in an environment containing a mixture of methane, hydrogen, and carbon monoxide, but only the presence of methane needs to be detected, the functional area 21 needs to be heated to 400 degrees Celsius to ensure that the sensing particles 3 in the sensor can react with methane. However, hydrogen and carbon monoxide will also react with the sensing particles 3, thus affecting the measurement of the sensing current. This invention uses an external non-functional area 22. By using the dissipated heat to heat the non-functional area 22 to the temperature required for the hydrogen or carbon monoxide to react, the hydrogen and carbon monoxide are filtered out. Furthermore, the sensing area of ​​the non-functional area 22 that can react with hydrogen and carbon monoxide is much larger than the sensing area of ​​the functional area 21, allowing the non-functional area 22 to more easily contact and react with the hydrogen and carbon monoxide gases. The non-functional area 22 does not require an additional heat source for heating, nor does it require additional electrode plates for sensing current detection, further improving heat utilization.

[0052] Preferably, when it is necessary to detect the sensing current of hydrogen and carbon monoxide under certain specific conditions, the detection can be performed by depositing an electrode in the non-functional region 22, thus making the non-functional region 22 another form of functional region 21. Preferably, different regions can be divided into functional regions 21 based on the temperature distribution of the temperature field on the non-functional region 22, thereby realizing the detection of corresponding gas types at different temperatures on the same sensing layer 2. The core functional region 21 measures gases that require higher temperatures for sensing responses, while the non-functional regions 22 are set from the inside out according to temperature changes to correspond to functional regions 21 that require lower temperatures for sensing responses.

[0053] According to a preferred embodiment, when packaging the sensor, the channel for the mixed gas to enter the sensor can be set around the non-functional area 22, so that the mixed gas flows from around the non-functional area 22, over the non-functional area 22, and then flows to the functional area 21, encouraging the mixed gas to enter the functional area 21 in such a way that some impurity gas is removed in the non-functional area 22.

[0054] According to a preferred embodiment, since the thermal emissivity of heat conducted through air is much lower than the thermal conductivity through suspension 23, the overall temperature change of the temperature field on the non-functional area 22 mainly depends on the heat directly transferred to the non-functional area 22 by suspension 23 via thermal conduction. In conventional suspension designs, to reduce heat loss on functional area 21, the number of suspensions 23 is usually minimized to reduce heat loss along the suspension 23. Furthermore, when the number of suspensions 23 cannot be reduced, the suspension 23 is modified by designing it as a slender support beam structure. In this invention, the heat transferred along suspension 23 to non-functional area 22 provides the sensing particles 3 in non-functional area 22 with the heat required for sensing, allowing them to reach the sensing temperature. Therefore, it is not necessary to reduce the number of suspensions 23 or adjust the suspension 23 to a slender structure, further reducing the workload and material waste associated with refining the width of suspension 23.

[0055] According to a preferred embodiment, see Figure 4 To ensure that the heat transferred from the suspension 23 to the non-functional area 22 is sufficient for the non-functional area 22 to filter impurity gases, as many suspensions 23 as possible should be installed on the functional area 21 to connect to the non-functional area 22. However, installing too many suspensions 23 will cause the heat to dissipate from the functional area 21 too quickly, preventing the functional area 21 from reaching the first temperature or requiring a higher power heating electrode 51 to reach the first temperature. Therefore, while increasing the number of suspensions 23, the temperature change trend of the functional area 21 should also be considered.

[0056] Preferably, a suspension 23 is provided at each corner of the functional area 21 that is furthest from the core position (geometric center) of the functional area 21, connecting it to the non-functional area 22. This reduces the impact on the temperature of the functional area 21 as much as possible, while increasing the heat conducted from the functional area 21 to the non-functional area 22. This expands the overall temperature gradient and radiation range of the temperature field on the non-functional area 22, enabling the non-functional area 22 to filter impurity gases in the environment and further improve the sensing sensitivity of the functional area 21.

[0057] Furthermore, the minimum temperature required for the temperature field on the non-functional zone 22 can be determined based on the type and properties of the impurity gas. The range of the first temperature on the functional zone 21 can be determined based on the properties of the target gas, and the number of suspensions 23 can be adjusted accordingly. When the sensing temperature of the impurity gas is much lower than the sensing temperature of the target gas, i.e., when the minimum temperature required for the temperature field is much lower than the first temperature, the non-functional zone 22 does not need the functional zone 21 to conduct excessive heat to reach the temperature required for impurity gas filtration. In this case, reducing the number of suspensions 23 reduces heat loss on the functional zone 21, achieving energy saving. When the minimum temperature required for the temperature field is close to the first temperature, the non-functional zone 22 needs to transfer a large amount of heat from the functional zone 21 through the suspensions 23. Therefore, the number of suspensions 23 needs to be increased so that each corner of the functional zone 21 is connected to the non-functional zone 22 by a suspension 23. Especially when the number of corners in the functional zone 21 is greater, the maximum temperature in the temperature field can approach the first temperature on the functional zone 21.

[0058] According to a preferred embodiment, the suspension 23 is connected to one end of the functional area 21 in a manner that equally divides the corners of the functional area 21. This ensures that the connection angles formed between the two sides of the suspension 23 and the functional area 21 at the connection point are the same, reducing the probability of thermal stress unevenness and breakage caused by different connection angles at the connection point. Furthermore, the connection angles formed between the suspension 23 and the two sides of the functional area 21 at the connection point are obtuse angles, further avoiding the risk of breakage on the acute side due to the limited thermal expansion tendency caused by acute angles.

[0059] It should be noted that the specific embodiments described above are exemplary, and those skilled in the art can devise various solutions inspired by the disclosure of this invention. These solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents.

Claims

1. A single-channel porous substrate for a semiconductor gas sensor, characterized in that, The single-channel porous substrate includes a functional region (21) for detecting the target gas based on a sensing reaction at a first temperature and a non-functional region (22) for filtering at least a portion of impurity gases other than the target gas based on a sensing reaction at a temperature lower than the first temperature, wherein the first temperature is the catalytic ignition temperature of the target gas. The functional area (21) and the non-functional area (22) are connected by several suspensions (23) to reduce heat loss from the functional area (21); the suspensions (23) can conduct heat from the functional area (21) to the non-functional area (22) through heat conduction. The displacement tendency of the functional area (21) when it expands under heated conditions can be limited by the tensile stress of the non-functional area (22) connected to the functional area (21) through the suspension (23), so that the functional area (21) can remain matched with the heating area that provides the heat source of the functional area (21); The non-functional area (22) is used for corner compensation when the functional area (21) deforms in a high-temperature environment. The corner compensation is based on the non-functional area (22), suspension (23) and functional area (21) being an integrally generated structure. The suspension (23) is connected to one end of the functional area (21) in a way that divides the corner of the functional area (21) equally. This makes the connection angles formed between the two sides of the suspension (23) and the functional area (21) at the connection point the same, and the connection angles are obtuse angles. This makes the deformation degree of the connection angles consistent when they are heated and expands, reducing the probability of uneven thermal stress and breakage caused by different connection angles.

2. The single-channel porous substrate according to claim 1, characterized in that, One end of the suspension (23) connected to the functional area (21) is located at an angle far from the geometric center of the functional area (21), so that most of the heat conducted by the suspension (23) to the non-functional area (22) comes from the edge position far from the core position of the functional area (21).

3. The single-channel porous substrate according to claim 2, characterized in that, The number of suspensions (23) decreases as the difference between the second temperature when the impurity gas reacts and the first temperature when the target gas reacts increases. The second temperature is the temperature at the highest point of the temperature field that is lower than the first temperature, and the second temperature is the catalytic ignition temperature of the impurity gas. The minimum number of suspensions (23) is 1.

4. The single-channel porous substrate according to claim 3, characterized in that, The single-channel porous substrate is formed by arranging multiple single-pore nanotubes, each nanotube having an opening that connects to the outside, and sensing particles (3) are deposited inside the nanotube and on the side of the opening of the nanotube. The sensing electrode (1) is disposed on the functional area (21) on one side of the opening of the channel (24); The functional area (21) matches the shape of the heating area formed by the meandering thermal resistance wire (53) of the heating layer (5), so that the thermal resistance wire (53) can heat the functional area (21) as a whole.

5. The single-channel porous substrate according to claim 4, characterized in that, The sensing electrode (1) includes a pair of interdigitated electrodes (11) which are electrically connected to the sensing particles (3) deposited on the functional area (21). When an external voltage source is applied, the electrical changes of the sensing particles (3) when they undergo a sensing response can be transmitted based on the sensing electrode (1).

6. The single-channel porous substrate according to claim 4, characterized in that, An isolation layer (4) is provided between the single-pass porous substrate and the heating layer (5); The isolation layer (4) transfers the heat generated by the heating layer (5) to the non-functional area (22) in a uniform conduction manner. The isolation layer (4) has reserved heating electrode holes (42) for the heating layer (5) to be led out to an external heating power supply.

7. The single-channel porous substrate according to claim 6, characterized in that, The heating electrode (51) of the heating layer (5) is nested in the heating electrode hole (42) reserved on the isolation layer (4) and set on the isolation layer (4), so that one side of the heating electrode (51) is exposed, which facilitates the connection of the heating voltage source. The thermal resistance wire (53) is connected to the heating electrode (51) via a connecting wire (52).

8. The single-channel porous substrate according to claim 7, characterized in that, The non-functional area (22) can receive heat radiated from the heating electrode (51) through the trapezoidal slot portion on the isolation layer (4) towards the non-functional area (22) and heat conducted from the functional area (21) to the non-functional area (22) through the suspension (23), reaching the second temperature required for the upper part of the non-functional area (22) to sense the impurity gas.

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