A semiconductor gas sensor based on a single-pass porous substrate

Abstract

The present invention relates to a semiconductor gas sensor based on a single-pass porous substrate, which at least includes a sensing layer, and detects gas based on a deposited gas-sensitive material. The sensing layer can be divided into a functional area for detecting a target detection gas based on a sensing reaction at a first temperature and a non-functional area for filtering at least part of the impurity gas other than the target detection gas based on a sensing reaction at a temperature lower than the first temperature. The functional area and the non-functional area are connected by a plurality of suspensions, wherein the suspensions can transfer heat from the functional area to the non-functional area by heat conduction. The present invention reduces the influence of impurity gas on the detection results during the detection process by designing a non-functional area outside the traditional sensing area.

Description

Technical Field

[0001] The present invention relates to the field of sensor equipment, and in particular to a semiconductor gas sensor based on a single-pass porous substrate. Background Art

[0002] In recent years, major media outlets have frequently reported on sudden toxic gas leaks, raising concerns about detecting them. Toxic gases such as carbon monoxide, hydrogen sulfide, carbon dioxide, and sulfur dioxide pose significant risks to the human body. However, traditional toxic gas detection methods have been limited in adoption due to their lengthy testing times, the need for specialized personnel to operate the instruments, the complexity of the operation, and the difficulty of on-site use. Generally, toxic gas detection devices are used by non-professionals. To rapidly detect toxic gases over a large area, these devices must be fast-response, simple to operate, miniaturized, and portable.

[0003] Gas sensors, particularly metal oxide semiconductor (MOX)-based resistive gas sensors, are widely used in various fields, including environmental pollution monitoring, hazardous gas leaks, and chemical detection. With the development of the Internet of Things (IoT) and the advancement of precision medicine strategies, traditional MOX gas sensors hold great potential for application in emerging fields such as wearable portable devices, point-of-care diagnostics (POCT), smart cities, and smart homes. However, they also face numerous challenges.

[0004] In the prior art, a semiconductor sensor device proposed in patent document with publication number CN105900236B includes: 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 electrically communicating with the at least one electrode, wherein the porous sensing layer defines multiple grain boundaries formed by spaced-apart nucleation on the unsuitable seed layer using atomic layer deposition.

[0005] CN113092542A discloses a planar nano gas sensor, an array, and a preparation method thereof, relating to the technical field of gas sensors. The gas sensor comprises, from top to bottom, a planar sensing electrode, a sensing layer, an electrical insulating layer, and a micro heater. The sensing layer is formed by depositing nano-scale sensing material in a double-through-hole substrate. The double-through-hole substrate is composed of a plurality of double-through-hole nanotubes. The double-through-hole nanotubes are nanotubes with one end open and the other end connected. The nano-scale sensing material is deposited on the tube wall of the double-through-hole nanotubes. The heating area of the micro heater overlaps with the sensing area of the planar sensing electrode in the vertical direction.

[0006] Most MOX gas sensors currently on the market suffer from high power consumption and poor selectivity. Gas sensors are mostly planar, two-dimensional thin-film structures and must operate at high temperatures (300-400°C). Heating activates the adsorption capacity between the sensor and the target gas, thereby increasing its sensitivity to the gas. This makes these gas sensors unsuitable for low-power applications and also faces challenges in long-term stability and service life. Furthermore, as society develops at an ever-increasing pace, wireless connection technology, network technology, and electronic technology are increasingly integrated, leading to higher demands for intelligent and user-friendly features. Combining gas sensors with wireless connection technology and network technology for simultaneous detection and real-time monitoring of toxic gases greatly facilitates timely detection of toxic gases. Therefore, it is crucial to develop a miniature, reliable, portable, highly sensitive detection system capable of real-time monitoring of different toxic gases.

[0007] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventor studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0008] To address at least some of the shortcomings of the above-mentioned prior art, the present application provides a semiconductor gas sensor based on a single-pass porous substrate, comprising at least a sensing layer. Gas detection is performed based on a deposited gas-sensitive material. The sensing layer is characterized in that the sensing layer can be divided into a functional region for detecting a target gas based on a sensing reaction at a first temperature and a non-functional region for filtering at least some impurity gases other than the target gas based on a sensing reaction at a temperature lower than the first temperature. The functional and non-functional regions are connected by a plurality of suspensions, wherein the suspensions are capable of transferring heat from the functional region to the non-functional region via thermal conduction. Studies have shown that even if most of the heat generated by the heater electrode is radiated to the functional region, the non-functional region, due to the combined effects of the residual heat radiated by the heater electrode and the heat transferred from the functional region via the suspensions, forms a temperature field in which the closer the distance to the suspension connection and the heater electrode, the higher the temperature. The second temperature at the highest point in the temperature field is lower than the first temperature due to heat loss during heat transfer. Therefore, the non-functional region can also be used to sense certain gas molecules that are less sensitive to 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 may enter the functional area and cause a sensing reaction, affecting the sensing results. By applying different temperatures to the non-functional and functional areas, the impurity gases are removed by the sensing reaction when they enter the non-functional area, reducing the proportion of impurity gases in the mixed gas entering the functional area, thereby improving sensing efficiency.

[0009] Preferably, the sensing layer can adjust the number of suspensions based on the relationship between the first temperature at which the target gas is sensed and the second temperature at which the impurity gas is sensed. The number of suspensions decreases as the difference between the second temperature and the first temperature increases, with a minimum number of suspensions of 1. A greater number of suspensions transfers more heat to the non-functional area, raising the overall temperature of the non-functional area and the maximum temperature it can reach. When the temperature required for the impurity gas sensing reaction is high, even approaching the first temperature at which the target gas is sensed, the temperature of the non-functional area can be increased by adding suspensions to ensure that the impurity gas is sensed and filtered in the non-functional area. When the second temperature at which the impurity gas is sensed is higher than the first temperature, the sensing result will not be affected because the sensor's maximum temperature, the first temperature, is insufficient for the impurity gas to sense. Furthermore, in the present invention, the non-functional area is larger than the functional area, making it easier for the non-functional area to filter and remove impurity gas.

[0010] Preferably, the end of the suspension connected to the functional area is positioned at a corner away from the geometric center of the functional area, so that most of the heat transferred from the suspension to the non-functional area comes from the edge away from the core of the functional area. The two connection angles formed by the suspension connecting to the functional area are obtuse, so that the degree of deformation of the connection angles when thermally expanded is consistent. Obtuse connection angles can ensure that deformation of the connection is not restricted when the connection is thermally expanded, thereby reducing the risk of fracture at the connection due to high thermal stress. In the present invention, the two connection angles at the connection are set to the same size, further avoiding the problem of fracture caused by unbalanced thermal stress due to different angles on the left and right sides of the connection.

[0011] Preferably, the displacement tendency of the functional area when it expands under heating conditions can be limited under the tensile stress of the non-functional area connected to the functional area through the suspension, so that the functional area can maintain matching with the heating area that provides the heat source for the functional area. Since the functional area is at a relatively high temperature, the expansion effect during heating causes the functional area to displace, and the higher the temperature, the greater the displacement. After the functional area is displaced, it no longer matches the heating area, which can easily cause uneven heating of the functional area and lead to poor sensing effect. In order to avoid this problem, the present invention connects the functional area to the non-functional area through a suspension. When the non-functional area is fixed or with the help of the friction force of the non-functional area, the displacement of the functional area can be limited, so that the functional area always remains in the heating area, ensuring that the sensing reaction of the functional area is carried out normally.

[0012] Preferably, the sensing layer can be formed from a porous single-pass substrate with sensing particles deposited on its surface. A particular example of a porous single-pass substrate can be a porous single-pass alumina substrate. Specifically, the porous single-pass alumina substrate can be formed from an array of multiple single-hole nanotubes, each having an opening communicating with the outside. The other end of the nanotube, opposite the opening, is connected to the aluminum substrate via a barrier layer. Sensing particles are deposited within the nanotubes and near the opening.

[0013] Preferably, the semiconductor sensor also includes a sensing electrode, which is arranged on a side of the functional area with an opening. The sensing electrode includes at least a pair of interdigitated electrodes, which are electrically connected to the sensing particles deposited on the functional area. When an external voltage source is applied, the electrical changes in the sensing particles when a sensing reaction occurs can be transmitted based on the sensing electrodes.

[0014] Preferably, the semiconductor sensor also includes a heating layer and an isolation layer. The isolation layer is arranged between the heating layer and the sensing layer. The isolation layer can transfer the heat generated by the heating layer to the functional area in a uniform conduction manner. The isolation layer is reserved with heating electrode holes for leading the heating layer to an external heating power supply.

[0015] Preferably, the heating layer includes a heating electrode and a thermal resistance wire. The heating electrode is electrically connected to the thermal resistance wire through a connecting wire. The shape of the heating electrode matches the heating electrode hole, so that the heating electrode can be arranged in the heating electrode hole in a nested manner and maintain electrical connection with an external heating power supply. The shape of the heating area formed by the winding thermal resistance wire matches the functional area, so that the thermal resistance wire can heat the functional area as a whole.

[0016] Preferably, the sensor also includes a supporting layer, which is arranged on the other side of the thermal resistance wire relative to the sensing layer. The supporting layer is provided with a bearing area to prevent the heat generated by the thermal resistance wire from dissipating from one side of the supporting layer. The bearing area is arranged to match the heating area formed by the thermal resistance wire.

[0017] Preferably, the sensor further comprises a substrate, which is arranged on the other side of the supporting layer. The substrate is provided with a groove hole penetrating the substrate, and the groove hole can improve the bending resistance of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 is a schematic diagram of the sensing electrode of the present invention;

[0020] Figure 3 is a schematic diagram of the heating layer of the present invention;

[0021] Figure 4 Schematic diagram of the sensing layer partitioning of the present invention;

[0022] Figure 5 It is a cross-sectional view of the sensing layer of the present invention.

[0023] Reference Signs List

[0024] 1: Sensing electrode; 11: Interdigital electrode; 12: Interdigital interval; 13: Interdigital end; 14: Interdigital panel; 2: Sensing layer; 21: Functional area; 22: Non-functional area; 23: Suspension; 24: Channel; 25: Aluminum base; 26: Oxide layer; 27: Barrier layer; 3: Sensing particles; 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: Slotted hole. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings.

[0026] To make the above-mentioned purposes, features, and advantages of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0027] The present invention provides a semiconductor gas sensor based on a single-pass porous substrate, such as Figure 1 As shown, it may include the following parts stacked in sequence from top to bottom:

[0028] The sensing electrode 1 is arranged at the top of the entire sensor and is used to transmit the electrical signal when the sensor has a sensing reaction.

[0029] The sensing layer 2 is provided on the bottom layer of the sensing electrode 1 in a manner of at least partially vertically overlapping with the sensing electrode 1 , and comprises sensing particles 3 for generating a sensing reaction with the gas to be detected.

[0030] The isolation layer 4 is provided on a side of the sensing layer 2 opposite to the sensing electrode 1 and is used to uniformly and stably transmit heat required for the sensing particles 3 to generate a sensing reaction to the sensing layer 2 .

[0031] The heating layer 5 is provided at the bottom of the isolation layer 4 and is used to provide heat to the sensing layer 2 . The heat can be evenly conducted to the sensing layer 2 after being blocked by the isolation layer 4 .

[0032] The support layer 6 is arranged on the side of the heating layer 5 opposite to the isolation layer 4 and is used to prevent the heat generated by the heating layer 5 from being dissipated from the side of the support layer 6 .

[0033] The substrate 7 is arranged at the bottom layer of the entire sensor structure and serves as a carrier structure for carrying all the above layer structures. Figure 1 and Figure 5 The sensing electrode 1 is provided on the surface of the sensing layer 2. The sensing electrode 1 is in contact with and electrically connected to the sensing particles 3 on the sensing layer 2. Under the premise that the voltage across the sensing electrode 1 is constant, the sensing particles 3 can react with the gas to be detected when they come into contact with the gas to be detected, causing their own resistance to change, and further causing the current in the circuit to change. By monitoring the current change in the circuit, it can be determined whether there is a gas that can be sensed in the scene where the sensor is located. Preferably, as Figure 2The sensing electrode 1 is composed 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 contactlessly. 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, forming a closed circuit between the two interdigital electrodes 11. Specifically, the interdigital electrodes 11 are constructed as a structure with two branch wires extending toward each other near the end positions of two side-by-side wires. Optionally, the number of branch wires can be any value greater than two.

[0034] According to a preferred embodiment, the sensing electrode 1 is deposited on the surface of the sensing layer 2. In particular, a special case of the sensing layer 2 can be a porous single-pass alumina template. Specifically, the aperture direction of the porous single-pass alumina template is toward the sensing electrode 1, and the interdigital interval 12 formed by the two interdigital electrodes 11 being symmetrically embedded with each other is deposited at the aperture position of the porous single-pass alumina template. The two interdigital electrodes 11 are deposited on the surface of the sensing layer 2 and then contact the sensing particles 3 in the interdigital interval 12 to achieve electrical connection. The sensing particles 3 in the interdigital interval 12 include sensing particles on the surface outside the aperture and sensing particles deposited on the inner wall of the alumina template in the aperture. Preferably, the interdigital interval 12 can be an area of any shape that can be thought of by a person skilled in the art, matching the outline surrounded by the interdigital electrode 11 with which it cooperates. It is set here as a triangle. The two interdigital electrodes 11 are led out through their respective interdigital panels 14, and the interdigital panel 14 is used to be connected to an external voltage source.

[0035] According to a preferred embodiment, the sensing layer 2 can be formed from a porous single-pass alumina template with sensing particles 3 deposited on its surface. It should be understood that the porous single-pass alumina template described in the present invention is merely a preferred embodiment of the sensing layer 2. In some alternative embodiments, the porous single-pass substrate or sensing layer 2 described in the present invention can also be formed from one or more of titanium oxide, silicon oxide, tantalum oxide, zirconium oxide, or gallium nitride.

[0036] According to a preferred embodiment, taking a porous single-pass alumina template as an example, the porous single-pass alumina template can be composed of a plurality of single-hole nanotubes, each of which has an opening connected to the outside. In particular, in addition to the porous single-pass structure, the alumina template can also be a porous double-pass structure, that is, the double-pass alumina template is composed of a plurality of openings connected to each other at both ends. The structure of a common porous single-pass alumina template is honeycomb-shaped, which is composed of hundreds, thousands, or even tens of thousands of regular hexagonal columnar oxide units. Figure 5As shown, there is a circular channel 24 in the middle of each regular hexagon. The size of the channel is generally at the nanometer level, and the channel is roughly perpendicular to the surface. The pore size is uniform but relatively adjustable, the structure is simple and the array is orderly. There is a barrier layer 27 between the aluminum base 25 and the oxide layer 26, which is hemispherical. This special structure makes the preparation process of the porous single-pass alumina template in the nano-ordered array simple and low-cost, and suitable for the assembly of various materials. The ratio between the assembled and deposited substances and the morphology of the particles in the porous single-pass alumina template is closely related to the performance of the nanomaterial. The two-step anodizing method can be used to prepare the porous single-pass alumina template. Because this template has the characteristics of high temperature resistance, high strength, and monodisperse pore size, it becomes an ideal preparation method for nano-alumina materials.

[0037] According to a preferred embodiment, the sensing particles 3 are nano zinc oxide materials. Preferably, the sensing particles can also be gas-sensitive materials such as tin dioxide or tungsten trioxide (the gas can cause the electrical properties of the gas-sensitive material to change when in contact with the gas-sensitive material, such as an increase or decrease in resistance). The sensing particles 3 are arranged on the inner wall of the nanotubes and the surface of the nanotube orifices of the porous single-pass substrate by adsorption deposition. The porous single-pass substrate has a high specific surface area, can contact and adsorb more sensing particles 3 as possible, and greatly increases the expansion area of the sensing particles 3, so that the gas molecules to be detected can more easily contact the sensing particles 3 and react with them.

[0038] According to a preferred embodiment, when the sensor particles 3 come into contact with target gas molecules capable of undergoing a sensing reaction, they gain or lose electrons based on the oxidizing and reducing properties of the target gas. This changes the electrical resistance of the sensor particles 3, the current flowing through them, and the magnitude of the current flowing through the sensing electrode 1 electrically connected to the sensor particles 3. Therefore, by monitoring the degree of change in current, it is possible to determine whether the sensor particles 3 have come into contact with target gas molecules capable of undergoing a sensing reaction. By controlling the temperature environment, the sensor particles 3 can be controlled to react only with the target molecules to be detected.

[0039] like Figure 4The porous, single-pass substrate of the sensing layer 2 can be divided into a functional region 21 and a non-functional region 22. The functional region 21 and the non-functional region 22 are connected by a suspension 23. Sensing particles 3 are deposited on both the functional region 21 and the sub-functional region 22. The shape of the functional region 21 is adapted to that of the sensing electrode 1, allowing the shape of the functional region 21 to match the interdigital region 12. Here, the shape of the functional region 21 is configured as a triangle that matches the outline of the sensing electrode 1. The non-functional region 22 is used to compensate for the angle when the functional region 21 deforms in a high-temperature environment. Providing only a single suspension 23 connected to the functional region 21 can reduce heat loss from the functional region 22. The functional region 21 needs to be at a relatively high temperature—denoted as the first temperature—when a sensing reaction occurs. Due to the differences in Young's modulus and thermal expansion coefficients of the constituent materials of the functional region 21 and the stacked sensing electrodes 1 and isolation layer 4 on either side, the surface stress of the functional region 21 increases under high-temperature conditions. The stress at the connection with the suspension 23 is relatively high, making it prone to cracking and breakage. This can be improved through angle compensation. The non-functional area 22, the suspension 23 and the functional area 21 are an integrally generated structure. Preferably, the non-functional area 22, the suspension 23 and the functional area 21 can be cut and separated from the complete porous single-pass substrate by cutting.

[0040] According to a preferred embodiment, the sensing current during a sensing reaction is primarily distributed across the sensing particles 3, including the substrate pore surface and the sensing particles within the substrate nanopores. In the present invention, the contact surface between the sensing electrode 1 and the sensing layer 2 is the overlap between the interdigital region 12 of the sensing electrode 1 and the functional region of the sensing layer 2. That is, the sensing reaction occurs primarily within the nanopore walls, which have a relatively large expanded area, with a smaller portion located within the interdigital region of the sensing electrode 1.

[0041] According to a preferred embodiment, an isolation layer 4 is disposed beneath the sensing layer 2 to isolate the sensing layer 2 from the heating layer 5. This isolation layer 4 prevents the heating layer 5 from experiencing rapid temperature changes, which could lead to failure of the sensing particles 3. Rapid temperature changes can also cause large variations in thermal stress and thermal expansion in the device, which can easily cause material deformation and fracture. While ensuring heat conduction, the isolation layer 4 also serves to electrically isolate the sensing layer 2 from the heating layer 5. The isolation layer 4 can be formed from a silicon oxide layer structure.

[0042] According to a preferred embodiment, the isolation layer 4 is provided with a first overlapping area 41 of the matching functional area 21, the suspension 23 and the interdigital electrode 11 for connecting the wires of the interdigital panel 14. Figure 1As shown, the first overlapping region 41 is formed by cutting away a plurality of trapezoids whose mid-vertical lines intersect at a point and whose short sides face each other, through the isolation layer. In the present invention, the first overlapping region 41 is formed by removing three trapezoids. The triangular area enclosed by the trapezoids matches the shape of the functional region 21, and the area of the triangular area is slightly larger than that of the functional region 21 to ensure that the functional region 21 is completely within the triangular area. A reserved area is reserved between adjacent trapezoids for matching and overlapping with the suspension 23 and part of the wires of the interdigital electrode 11.

[0043] According to a preferred embodiment, the heating layer 5 is arranged on the side of the isolation layer 4 opposite to the sensing layer 2. Figure 3 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 mainly uses the thermal resistance wire 53 to provide the heat source required for the sensing reaction for the entire sensor. The thermal resistance wire 53 is formed by winding a triangular area of a material with a relatively high resistivity to match the first overlapping area 41, so that under the premise of a certain overall shape, the thermal resistance wire 53 can have a longer length to pass through the isolation layer 4 to centrally heat the functional area 21 of the sensing layer 2. The material of the connecting wire 52 can be the same as that of the thermal resistance wire 53. Even if the connecting wire 52 generates heat when current passes through it, since the thermal resistance wire 53 has a relatively long heat-generating length, the heat is more concentrated, so the heat of the connecting wire 52 has less impact on the sensing reaction of the functional area 21. The economic benefit brought by the thermal resistance wire 53 and the connecting wire 52 being able to be generated in one piece without the need to select other wires to be electrically connected to the thermal resistance wire 53 is the highest, and material loss during the manufacturing process is saved. The connecting wire 52 is led to the heating electrode 51 by overlapping the reserved area. The heating electrode 51 is preferably rectangular and has a relatively large area, allowing for easy electrical connection to a voltage source. The heating electrode 51 is nested within a reserved heating electrode hole on the isolation layer 4 and disposed on the isolation layer 4, leaving one side of the heating electrode 51 exposed, facilitating connection to a heating voltage source.

[0044] According to a preferred embodiment, the heating area formed by the meandering thermal resistance wire 53 matches the shape of the functional area 21, so that the thermal resistance wire 53 can heat the entire functional area 21. When passing through the isolation layer 4, the heat generated by the thermal resistance wire 53 can be collected in the isolation layer 4 and evenly transferred to the functional area 21 on one side of the isolation layer 4, so that the heat generated by the thermal resistance wire 53 does not directly act on the functional area, avoiding thermal stress imbalance caused by uneven heating in the functional area 21, resulting in deformation of the functional area 21 or shedding of the sensor particles 3 on the functional area 21.

[0045] According to a preferred embodiment, the support layer 6 is arranged at the bottom layer of the heating layer 5. A second overlapping area 61 is provided at the position of the support layer 6 corresponding to the first overlapping area 41. The shape and size of the second overlapping area 61 match the first overlapping area 41. The second overlapping area 61 is used to be the bearing area of the thermal resistance wire 53 when the heating layer 5 is deposited on the support layer 6. The second overlapping area 61 includes three cantilever beams for connecting to the remaining area of the support layer 6. When the heat generated by the heating layer 5 is transferred to the bearing area, since the bearing area is only connected by three cantilever beams, the heat on the bearing area is dissipated through the cantilever beams at a slow thermal conductivity rate, so that the bearing area can concentrate the heat radiated from the heating layer 5 to the support layer 6, so that the temperature of the functional area 21 adapted to the first overlapping area 41 and the second overlapping area 61 can reach the first sensing temperature. The support layer 6 can be formed by slotting a silicon nitride or silicon oxide layer structure.

[0046] 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. Figure 1 As shown, substrate 7 is a thick cubic structure. A slotted hole 71 is provided throughout substrate 7, extending vertically and vertically. In the present invention, slotted hole 71 is configured as a triangular structure for high stability. Preferably, slotted hole 71 can also be shaped like a square, trapezoid, or other shapes conceivable by those skilled in the art. Slotting substrate 7 increases its bending resistance, further reducing the risk of bending in the event of a drop, thereby further improving the reliability of the sensor device.

[0047] The shape of the groove hole 71 matches the first overlapping area 41 and the second overlapping area 61, and the triangular size of the groove hole 71 is larger than the first overlapping area 41, so that the sensor device passes through the groove hole 71, the second overlapping area 62, the thermal resistance wire 53, the first overlapping area 41, and the sensing layer 2 from bottom to top. The gas to be detected can enter from one side of the sensor device and then pass out from the other side. The gas flowability of the device is strong, and it is easier for the gas to be detected to enter for detection. Preferably, in order to provide higher physical strength, the substrate 7 can preferably be selected as a silicon substrate. In particular, when the substrate 7 described in the present invention is made of silicon material, such as Figure 1 The support layer 6 shown may be unnecessary. 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 generally necessary in order to ensure electrical insulation between the substrate 7 and the further layer structure.

[0048] 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 thermal expansion coefficient of each layer of material, the functional area 21 of the sensor will have large thermal stress and deformation at high temperature. When the thermal stress is too large, it will affect the stability of the sensor, and may even cause problems such as breakage at the connection of the suspension 23 and cracking of the membrane structure formed by the sensing particles 3 during use, which will directly affect the reliability and life of the sensor. When the functional area 21 is heated, due to the existence of thermal stress, the functional area 21 will deform and displace during the process of thermal expansion, and the higher the temperature, the greater the deformation and the greater the displacement. When the maximum temperature is 500 degrees Celsius, the displacement of the functional area 21 can reach 1.5um. Under conditions of long-term thermal deformation, the position of the functional area 21 is bound to change to the point where it no longer overlaps and matches the first overlapping area 41 where the heating electrode 51 is located. The heat generated by the heating electrode 51 can only heat part or a small part of the functional area 21, resulting in uneven temperature distribution on the functional area 21, which further causes the membrane structure on the functional area 21 to fall off and fail. The present invention fixes the position of the functional area 21 by connecting the functional area to the non-functional area 22 using a suspension 23 and connecting the non-functional area 22 to the isolation layer 4. When the functional area 21 expands and deforms due to heat and tends to displace, its displacement tendency is limited by the non-functional area 22 through the suspension 23, so that it always remains in a position that matches the heating electrode 15.

[0049] The non-functional area 22 can receive heat radiated toward the non-functional area 22 by the heating electrode 51 through the trapezoidal slots on the isolation layer 4, and heat conducted to the non-functional area 22 by the functional area 21 through the suspension 23, reaching the second temperature required for the sensing reaction to occur in the upper portion of the non-functional area 22. The maximum temperature that the second temperature can reach is lower than the first temperature at which the sensing reaction occurs in the functional area 21. The sensing particles 3 can sense different types of gas molecules to be detected at different temperatures. For example, the catalytic ignition temperature of methane is generally above 400 degrees Celsius, while the catalytic ignition temperature of hydrogen, carbon monoxide, or other alkanes is generally below 260 degrees Celsius. Research has shown that even though most of the heat generated by the heating electrode 51 is concentrated and radiated to the functional area 21, the residual heat radiated by the heating electrode 51 and the heat conducted from the functional area 21 via the suspension 23 in the non-functional area 21 form a temperature field where the temperature increases the closer to the connection point between the suspension 23 and the heating electrode 51. The second temperature at the highest point in the 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 reaction for certain gas molecules that do not require high temperature conditions (such as hydrogen and carbon monoxide). When the target molecule to be detected requires a higher temperature, some impurity gases that do not require high temperature conditions and do not need to be detected will enter the functional area 21 and undergo a sensing reaction, affecting the sensing results. By applying different temperatures to the non-functional area 22 and the functional area 21, the impurity gas can be removed by the sensing reaction when it enters the non-functional area 22, reducing the proportion of impurity gases in the mixed gas entering the functional area 21, thereby improving sensing efficiency. Furthermore, the non-functional region 22 is much larger than the functional region, making it easier for the non-functional region 22 to contact impurity gases in the mixed gas and remove them through a sensing reaction. Upon entering the sensor, some impurity gases that could undergo a sensing reaction on the non-functional region 22 are adsorbed there, causing a sensing reaction. This increases the proportion of the target gas in the mixed gas entering the sensor, thereby increasing the probability that the functional region 21 will undergo a sensing reaction with the target gas, thereby improving the sensitivity of the sensor.

[0050] Specifically, when a mixed gas of methane, hydrogen, and carbon monoxide exists in the sensor's environment, but only the presence of methane needs to be detected, in this case, to ensure that the sensor particles 3 in the sensor can sense methane, the functional area 21 needs to be heated to 400 degrees Celsius. However, hydrogen and carbon monoxide will also sense and react with the sensor particles 3, thereby affecting the measurement of the sensing current. The present invention adopts an external non-functional area 22. By using only the dissipated heat to heat the non-functional area 22 to the temperature required for the hydrogen or carbon monoxide sensing reaction, the hydrogen and carbon monoxide are filtered out. 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. The non-functional area 22 can more easily contact and sense hydrogen and carbon monoxide gases. The non-functional area 22 does not require an additional heat source for heating, nor does it require an additional electrode plate for sensing the current, further improving the utilization rate of heat.

[0051] Preferably, when the sensing current of hydrogen and carbon monoxide needs to be detected under certain specific factors, electrodes can be deposited in the non-functional area 22 for detection, so that the non-functional area 22 serves as another form of functional area. Preferably, different areas can be divided into functional areas based on the temperature distribution of the temperature field on the non-functional area 22, thereby achieving detection of corresponding gas types at different temperatures on the same sensing layer. The core area functional area 21 measures gases requiring higher temperatures for sensing reactions, and the non-functional area 22 is set from the inside to the outside according to temperature changes to corresponding functional areas requiring lower temperatures for sensing reactions.

[0052] According to a preferred embodiment, when packaging the sensor, the channel for the mixed gas to enter the interior of the sensor can be set around the non-functional area 22, so that the mixed gas flows from around the non-functional area 22, passes 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 a way that some impurity gases are removed in the non-functional area 22.

[0053] According to a preferred embodiment, because the thermal emissivity of heat conducted through air is much lower than the thermal conductivity of heat conducted through the suspension 23, the overall temperature change in the temperature field of the non-functional area 22 is primarily determined by the heat directly transferred to the non-functional area 22 by the suspension 23 via thermal conduction. In conventional suspension designs, to reduce heat loss in the functional area 21, the number of suspensions 23 is typically minimized to reduce heat loss from the functional area 21 through conduction along the suspensions 23. Furthermore, when the number of suspensions 23 cannot be reduced, the suspensions 23 are improved to form a slender support beam structure. In the present invention, the heat transferred to the non-functional area 22 along the suspensions 23 provides the heat required for sensing by the sensing particles 3 in the non-functional area 22, allowing them to reach the sensing temperature. Therefore, there is no need to reduce the number of suspensions 53 or adjust the suspension 23 to a slender structure, further reducing the workload associated with reducing the width of the suspension 23 and reducing material loss.

[0054] According to a preferred embodiment, see Figure 4 To ensure that the heat transferred to the non-functional area 22 via the suspensions 23 can meet the heat requirements of the non-functional area 22 for filtering impurity gases, as many suspensions 23 as possible should be installed on the functional area 22 to connect to the non-functional area 22. However, installing too many suspensions 23 can cause heat to be dissipated 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, when increasing the number of suspensions 23, the temperature variation trend of the functional area 21 should also be considered.

[0055] Preferably, a suspension 23 is provided at each corner of the functional area 21 that is farthest from the core position (geometric center) of the functional area 21 and connected to the non-functional area. While minimizing the impact on the temperature of the functional area 21, the heat conducted from the functional area 21 to the non-functional area 22 can be increased to expand the overall temperature gradient of the temperature field in the non-functional area 22 and the radiation range of the temperature field, so that the non-functional area 22 can filter impurity gases in the environment, further improving the sensing sensitivity of the functional area 21.

[0056] Furthermore, the minimum temperature required for the temperature field in the non-functional area 22 can be determined based on the type and properties of the impurity gas, and the range of the first temperature in the functional area 21 can be determined based on the properties of the target detection gas, and the number of suspensions 23 provided can be adjusted. When the sensed temperature of the impurity gas is much lower than the sensed temperature of the target detection gas, that is, when the minimum temperature required for the temperature field is much lower than the first temperature, the non-functional area 22 does not need to conduct excessive heat from the functional area 21 to reach the temperature required for impurity gas filtration. At this time, energy conservation can be achieved by reducing the number of suspensions 23 and reducing heat loss in the functional area 21. When the minimum temperature required for the temperature field is close to the first temperature, the non-functional area 22 needs to transfer a large amount of heat from the functional area 21 via the suspensions 23. Therefore, the number of suspensions 23 needs to be increased until each corner of the functional area is provided with a suspension 23 connected to the non-functional area. In particular, when the number of corners in the functional area 21 is greater, the maximum temperature in the temperature field can be infinitely close to the first temperature in the functional area 21.

[0057] According to a preferred embodiment, the suspension 23 is connected to one end of the functional area 21 in a manner that bisects the corners of the functional area 21. This ensures that the connection angles formed between the suspension 23 and the two edges of the functional area 21 at the connection point are the same, reducing the risk of thermal stress unevenness and fracture caused by different connection angles at the connection point. Furthermore, the connection angle formed between the suspension 23 and the two edges of the functional area at the connection point is an obtuse angle, further avoiding the risk of fracture on the acute angle side due to the large thermal stress generated by the restricted thermal expansion tendency when the connection angle is acute.

[0058] It should be noted that the above-described specific embodiments are illustrative only. Those skilled in the art may devise various solutions based on the disclosure of the present invention, and such solutions fall within the scope of the present invention and are intended to be protected by the present invention. Those skilled in the art should understand that the present description and its accompanying drawings are intended to be illustrative only and are not intended to limit the scope of the claims. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A semiconductor gas sensor based on a single-pass porous substrate, comprising at least a sensing layer (2) for detecting gas based on a deposited gas-sensitive material, characterized in that: The sensing layer (2) can be divided into a functional area (21) for detecting a target detection gas based on a sensing reaction at a first temperature and a non-functional area (22) 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, wherein the functional area (21) and the non-functional area (22) are connected via a plurality of suspensions (23), wherein the suspensions (23) can transfer heat from the functional area (21) to the non-functional area (22) by means of heat conduction; One end of the suspension (23) connected to the functional area (21) is connected to the corner of the functional area (21), so that the heat conducted by the suspension (23) to the non-functional area (22) comes from the edge position away from the core position of the functional area (21) and the heating electrode (51), wherein the angle between the two connection angles formed by the suspension (23) and the functional area (21) is an obtuse angle.

2. The semiconductor gas sensor according to claim 1, wherein The sensing layer (2) is capable of adjusting the number of suspensions (23) to be set based on the relationship between a first temperature at which the target detection gas generates a sensing reaction and a second temperature at which the impurity gas generates a sensing reaction, wherein the number of suspensions (23) to be set decreases continuously as the difference between the second temperature and the first temperature increases.

3. The semiconductor gas sensor according to claim 1, wherein The displacement tendency of the functional area (21) when expanding under heating conditions can be limited under 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 maintain matching with the heating area that provides the heat source for the functional area (21).

4. The semiconductor gas sensor according to claim 1, wherein The sensing layer (2) is formed by a porous single-pass substrate with sensing particles (3) deposited on the surface. The porous single-pass substrate is formed by arranging a plurality of single-hole nanotubes. The nanotubes have an opening connected to the outside. The sensing particles (3) are deposited inside the nanotubes and on the opening side of the nanotubes.

5. The semiconductor gas sensor according to claim 4, characterized in that The semiconductor gas sensor further comprises a sensing electrode (1), wherein the sensing electrode (1) is arranged on the functional area (21) at one side of the opening of the pore (24), and the sensing electrode (1) comprises at least a pair of interdigitated electrodes (11), wherein the interdigitated electrodes (11) are electrically connected to the sensing particles (3) deposited on the functional area (21).

6. The semiconductor gas sensor according to claim 1, wherein: The semiconductor gas sensor further comprises a heating layer (5) and an isolation layer (4), wherein the isolation layer (4) is arranged between the heating layer (5) and the sensing layer (2), and the isolation layer (4) can allow the heat generated by the heating layer (5) to be transferred to the functional area (21), and a heating electrode hole (42) is reserved for the heating layer (5) to be led out to an external heating power source.

7. The semiconductor gas sensor according to claim 6, characterized in that The heating layer (5) comprises a heating electrode (51) and a thermal resistance wire (53), wherein the heating electrode (51) is electrically connected to the thermal resistance wire (53) via a connecting wire (52), wherein the shape of the heating area formed by the meandering of the thermal resistance wire (53) matches the functional area (21), so that the thermal resistance wire (53) can heat the functional area (21) as a whole.

8. The semiconductor gas sensor according to claim 7, wherein: The sensor further comprises a supporting layer (6), wherein the supporting layer (6) is arranged on the other side of the thermal resistance wire (53) relative to the sensing layer (2), and a bearing area is provided on the supporting layer (6) for preventing heat generated by the thermal resistance wire (53) from being lost from one side of the supporting layer (6), and the bearing area matches the heating area formed by the thermal resistance wire (53).

9. The semiconductor gas sensor according to claim 8, characterized in that The sensor further comprises a substrate (7), wherein the substrate (7) is arranged on the other side of the support layer (6), and a groove hole (71) is provided on the substrate (7) that penetrates the substrate (7) and is used to improve its anti-bending ability.

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