Gas flow sensor and gas flow detection method

Abstract

The present invention discloses a gas flow sensor and a gas flow detection method. The gas flow sensor includes a chip body, a cover body, a detection chip and a self-cleaning chip. The cover body is arranged on the chip body, and the cover body and the chip body enclose a gas flow channel. The gas flow channel includes a main flow channel and auxiliary flow channels arranged on both sides of the main flow channel. The detection chip is arranged in the main flow channel, and the detection chip includes a pair of heating resistor films and a temperature measuring resistor film. The paired heating resistor films and the temperature measuring resistor films are arranged alternately along the gas flow channel. The self-cleaning chip is arranged outside the gas flow channel, and the self-cleaning chip includes a pair of self-cleaning electrodes. The paired self-cleaning electrodes excite an alternating electric field to drive the particles in the gas into the auxiliary flow channel along a direction having an angle with the gas flow channel, thereby avoiding the attachment of micro-particles to the detection chip in the main flow channel, thereby effectively solving the problem that the sensor chip is easily affected by the attachment of micro-particles.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a gas flow sensor and a gas flow detection method. Background Art

[0002] The intelligent metering of electric energy has made great progress. However, my country's natural gas metering still uses traditional mechanical gas meters, which cannot achieve intelligent metering of gas energy. Therefore, the development of intelligent gas flow sensors compatible with the Internet of Things has become a hot spot in scientific and technological research and development. Due to the advantages of small size, light weight, low power consumption, high reliability, high sensitivity, compatibility with the Internet of Things, and easy integration, MEMS sensors are considered by the industry to be a highly potential emerging technology for solving the intelligent metering of gas flow.

[0003] However, literature research shows that one of the important reasons why the existing MEMS gas flow sensors have not yet been commercialized is that due to the presence of microparticles with a particle size of several microns to tens of microns in the gas, it was found during the MEMS sensor test process that they would slowly adhere to the surface of the sensor detection chip, resulting in a significant decrease in the sensor's measurement accuracy. The experimental research results show that when the chip is used for more than 1,500 hours, the sensor chip's measurement accuracy will drop by more than 20%, and as the use time continues, the accuracy will continue to decline, which seriously hinders the commercialization of MEMS intelligent gas flow sensors. Summary of the invention

[0004] Based on this, it is necessary to provide a gas flow sensor and a gas flow detection method to address the problem that in existing MEMS gas flow sensors, microparticles in the gas adhere to the surface of the sensor detection chip, resulting in a significant decrease in sensor measurement accuracy.

[0005] A gas flow sensor, comprising:

[0006] Chip body;

[0007] A cover body is arranged on the chip body, wherein the cover body and the chip body form a gas flow channel, and the gas flow channel includes a main flow channel and auxiliary flow channels arranged on both sides of the main flow channel;

[0008] A detection chip is arranged in the main flow channel, the detection chip comprises a temperature measuring resistor film and a heating resistor film, a plurality of the temperature measuring resistor films are arranged in sequence and at intervals along the gas flow channel, and the heating resistor film is arranged between two adjacent temperature measuring resistor films; and

[0009] A self-cleaning chip is arranged outside the gas flow channel. The self-cleaning chip includes a pair of self-cleaning electrodes. The pair of self-cleaning electrodes excite an alternating electric field to drive particles in the gas into the auxiliary flow channel along a direction having an angle with the gas flow channel.

[0010] In the above-mentioned gas flow sensor, the detection chip is arranged in the main channel for flow detection, and the self-cleaning chip is used to generate an alternating electric field to drive the particles in the gas into the auxiliary flow channel in a direction with an angle to the gas flow channel, thereby avoiding the adhesion of microparticles to the detection chip in the main channel, thereby effectively solving the problem that the sensor chip is easily affected by the adhesion of microparticles.

[0011] In one embodiment, a first groove is formed on the cover body, and two second grooves are formed at intervals on the bottom wall of the first groove. After the cover body is disposed on the chip body, the surrounding walls of the first groove, the second groove and the side walls of the chip body form the gas flow channel.

[0012] In one embodiment, the gas flow channel includes an inlet section, a middle section and an outlet section, the middle section is straight, and the inlet section and the outlet section are arc-shaped and transitionally connected to the middle section.

[0013] In one embodiment, the heating resistor film and the temperature measuring resistor film are formed by folding a sensitive resistor film sheet, and the number of folded layers of the heating resistor film is less than the number of folded layers of the temperature measuring resistor film.

[0014] In one embodiment, the electrodes at both ends of the heating resistor film and the temperature measuring resistor film after folding are perpendicular to the gas flow channel.

[0015] In one embodiment, the detection chip also includes a first wire and a first soldering pad, the heating resistor film and the temperature measuring resistor film are arranged on the chip body, and the first soldering pad is located outside the gas flow channel, and the heating resistor film and the temperature measuring resistor film are connected to the first soldering pad through the first wire.

[0016] In one of the embodiments, the chip body includes a substrate, an insulating layer and a heat-insulating layer, and the insulating layer and the heat-insulating layer are sequentially arranged on the upper and lower surfaces of the substrate.

[0017] In one of the embodiments, the self-cleaning electrode is parallel to the extension direction of the gas flow channel, so that the alternating electric field drives particles in the gas to move in a direction perpendicular to the gas flow channel.

[0018] In one embodiment, the self-cleaning chip further comprises an insulating substrate, the substrate is bonded to the chip body, and the self-cleaning electrode is disposed on the substrate.

[0019] A method for detecting gas flow using a gas flow sensor as described in any one of the above, comprising the following steps:

[0020] The gas enters the gas flow channel;

[0021] The detection chip detects the flow rate of gas in the gas flow channel;

[0022] The self-cleaning chip is connected to an alternating voltage, and the self-cleaning electrode excites an alternating electric field;

[0023] The particles in the gas are driven by the alternating electric field to enter the auxiliary flow channel along a direction having an angle with the gas flow channel;

[0024] The particles entering the auxiliary flow channel flow downstream along the auxiliary flow channel along with the air flow, and then flow out of the gas flow channel.

[0025] The above-mentioned method for detecting gas flow rate applies the gas flow rate sensor in the above-mentioned embodiment. The gas flow rate sensor can refer to the description in the above-mentioned embodiment and will not be described in detail here. Since the method for detecting gas flow rate provided by the embodiment of the present invention applies the gas flow rate sensor in the above-mentioned embodiment, the method for detecting gas flow rate provided by the present invention has all the beneficial effects of the gas flow rate sensor in the above-mentioned embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0027] Figure 1 is a schematic diagram of the structure of a gas flow sensor in one embodiment;

[0028] Figure 2 for Figure 1 Design drawing of the detection chip on the chip body;

[0029] Figure 3 for Figure 1 A schematic diagram of the structure of the middle cover body;

[0030] Figure 4 for Figure 3 A cross-sectional view of the cover body shown;

[0031] Figure 5 for Figure 1 Design diagram of the self-cleaning chip

[0032] Figure 6 Flow chart of a gas flow detection method in one embodiment.

[0033] Reference numerals:

[0034] 10-chip body, 12-base, 14-insulating layer, 16-heat-insulating layer, 20-cover, 21-gas flow channel, 211-main flow channel, 212-auxiliary flow channel, 22-first groove, 23-second groove, 24-entrance section, 25-middle section. 26-exit section, 30-detection chip, 31-temperature measuring resistor film, 32-heating resistor film, 33-first pad, 34-first wire, 40-self-cleaning chip, 41-self-cleaning electrode, 42-base, 43-second pad, 44-second wire. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the invention is not limited by the specific implementation disclosed below.

[0036] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0038] See also Figure 1 A gas flow sensor in one embodiment includes a chip body 10 , a cover body 20 , a detection chip 30 and a self-cleaning chip 40 .

[0039] The chip body 10 is the main structure of the flow sensor, and is used to carry other structures of the sensor. In one embodiment, the chip body 10 includes a substrate 12, an insulating layer 14, and a thermal insulation layer 16. The upper and lower surfaces of the substrate 12 are provided with an insulating layer 14 and a thermal insulation layer 16 in sequence. Among them, the insulating layer 14 is used to insulate the substrate 12 from other components of the sensor, and the thermal insulation layer 16 is used to block heat transfer to prevent the heat generated by the detection chip 30 and the self-cleaning chip 40 from being transferred to the substrate 12 to affect the stability of the temperature field in the detection chip 30.

[0040] In one embodiment, the substrate 12 is made of a semiconductor material, such as single crystal silicon. In this embodiment, the substrate 12 is made of N-type single crystal silicon. Of course, in other embodiments, the substrate 12 can also be made of other semiconductor materials, such as compound semiconductors, such as gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), etc.

[0041] In one embodiment, the insulating layer 14 is made of SiO2. Since the substrate 12 is made of N-type single crystal silicon, the SiO2 of the insulating layer 14 can be directly oxidized on the upper and lower surfaces of the substrate 12. The manufacturing of the insulating layer 14 is simple and convenient, and the bonding process of the insulating layer 14 and the substrate 12 is avoided. It can be understood that in other embodiments, the insulating layer 14 can also be made of other insulating materials, and the insulating layer 14 can also be bonded to the substrate 12.

[0042] In one embodiment, the heat insulating layer 16 is made of Si3N4, which has a good heat insulating effect on one hand, and has a good bonding performance with the insulating layer 14 SiO2 on the other hand. It is understandable that in other embodiments, the heat insulating layer 16 can also be made of other materials, as long as it can achieve heat insulation under the premise of insulation.

[0043] Please also read Figure 2 The cover body 20 is arranged on the chip body 10, and the cover body 20 and the chip body 10 form a gas flow channel 21. The gas flow channel 21 includes a main channel 211 and auxiliary flow channels 212 arranged on both sides of the main channel 211. The main channel 211 is relatively wide and is the main channel for the airflow. The auxiliary flow channel 212 is used to receive particulate matter in the gas.

[0044] Please also read Figure 3 and Figure 4 In one embodiment, the gas flow channel 21 is mainly made on the cover body 20. Specifically, the cover body 20 is provided with a first groove 22, and the bottom wall of the first groove 22 is provided with two second grooves 23 at intervals. After the cover body 20 is provided on the chip body 10, the peripheral walls of the first groove 22 and the second groove 23 and the side wall of the chip body 10 form the gas flow channel 21.

[0045] In this embodiment, the peripheral walls of the first groove 22 and the second groove 23 and the side walls of the heat insulation layer 16 of the chip body 10 form a gas flow channel 21. The space corresponding to the bottom wall of the first groove 22 constitutes a main flow channel 211, and the space corresponding to the second groove 23 constitutes an auxiliary flow channel 212.

[0046] In one embodiment, the cover 20 is made of a transparent material so that after the detection chip 30 is installed in the main channel 211, the operation of the detection chip 30 can be observed from the outside. Specifically, the cover 20 is made of glass with a thickness of 6 mm. Of course, the cover 20 can also be made of other transparent materials, such as inorganic glass and other plastics. Alternatively, when there is no need to observe the detection chip 30, the cover 20 can be made of an opaque material.

[0047] In one embodiment, the gas flow channel 21 includes an inlet section 24, a middle section 25 and an outlet section 26, the middle section 25 is located between the inlet section 24 and the outlet section 26, the middle section 25 is straight, the inlet section 24 and the outlet section 26 are in an arc shape that expands outward, and the inlet section 24 and the outlet section 26 are connected to the middle section 25 by an arc transition. The design of the gas flow channel 21 conforms to the streamline law of the airflow, which can effectively reduce the turbulence of the airflow when entering and leaving the flow channel, thereby affecting the accuracy of the flow velocity measurement, and effectively improves the accuracy of the gas flow measurement.

[0048] The detection chip 30 is arranged in the main flow channel 211, and the detection chip 30 is used to detect the flow rate of the gas in the flow channel. In one embodiment, the detection chip 30 includes a temperature measuring resistor film 31 and a heating resistor film 32, and a plurality of temperature measuring resistor films 31 are arranged in sequence along the gas flow channel 21, and the heating resistor film 32 is arranged between two adjacent temperature measuring resistor films 31. In other words, a temperature measuring resistor film 31 is arranged on both sides of each heating resistor film 32, and the two temperature measuring resistor films 31 are symmetrically distributed about the heating resistor film 32. In one embodiment, a temperature measuring resistor film 31 is provided at the entrance of the gas flow channel 21, and the temperature measuring resistor film 31 is used to measure the ambient temperature at the entrance of the gas flow channel 21.

[0049] In one embodiment, the temperature measuring resistor film 31 and the heating resistor film 32 are both made of a sensitive resistor film, wherein the sensitive resistor film is in a sheet shape, and the sensitive resistor film is folded to form the temperature measuring resistor film 31 and the heating resistor film 32. The number of folding layers of the temperature measuring resistor film 31 and the heating resistor film 32 is different, and the number of folding layers of the heating resistor film 32 is less than the number of folding layers of the temperature measuring resistor film 31.

[0050] On the basis of the above embodiment, further, the thickness of the sensitive resistor film is 200 microns, the width is 50 microns, and the fold line spacing is 50 microns. The number of folded layers of the heating resistor film 32 is 3 layers, and the number of folded layers of the temperature measuring resistor film 31 is 6 layers. Among them, the number of temperature measuring resistor films 31 is 5, the number of heating resistor films 32 is 3, one temperature measuring resistor film 31 is arranged at the entrance of the gas flow channel 21, and the remaining 4 temperature measuring resistor films 31 are arranged in sequence, and the 3 heating resistor films 32 are arranged in sequence in the gap formed by two adjacent temperature measuring resistor films 31.

[0051] In one embodiment, the detection chip 30 further includes a first pad 33 and a first wire 34, and the temperature measuring resistor film 31 and the heating resistor film 32 are arranged on the chip body. Specifically, the temperature measuring resistor film 31 and the heating resistor film 32 are arranged on the thermal insulation layer 16 of the chip body. The first pad 33 is arranged outside the gas flow channel 21, and the temperature measuring resistor film 31 and the heating resistor film 32 are connected to the first pad 33 through the first wire 34, and the first pad 33 is electrically connected to the substrate 12 of the chip body. Among them, the first pad 33 is arranged outside the gas flow channel 21, which can avoid gas leakage caused by the opening of the gas flow channel 21 to set the first pad 33, thereby reducing the processing difficulty of the flow sensor.

[0052] In this embodiment, after the heating resistor film 32 and the temperature measuring resistor film 31 are folded, the electrodes at both ends are perpendicular to the gas flow channel 21, and the first welding pad 33 is located on the extension line of the electrodes at both ends, so that the first wire 34 connects the temperature measuring resistor film 31 and the heating resistor film 32 to the first welding pad 33 using the shortest distance, which can reduce the amount of the first wire 34 and avoid wire deflection to improve the stability of the connection.

[0053] Specifically, first solder pads 33 are arranged on both sides of the gas flow channel 21, the electrodes at both ends of the heating resistor film 32 are respectively connected to the first solder pads 33 on different sides, the electrodes at both ends of the temperature measuring resistor film 31 face the same side of the chip body 10, and the electrodes at both ends of the temperature measuring resistor film 31 are connected to the first solder pads 33 on the same side.

[0054] Please also read Figure 5 The self-cleaning chip 40 is arranged outside the gas flow channel 21. The self-cleaning chip 40 includes a pair of self-cleaning electrodes 41. The pair of self-cleaning electrodes 41 are connected to a 220V / 50Hz alternating voltage to excite an alternating electric field, which drives the particles in the gas into the auxiliary flow channel 212 in a direction with an angle to the gas flow channel 21, thereby avoiding the attachment of microparticles to the detection chip 30 in the main flow channel 211, thereby effectively solving the problem that the sensor chip is easily affected by the attachment of microparticles.

[0055] In one embodiment, the self-cleaning chip 40 further includes an insulating substrate 42, the substrate 42 is bonded to the chip body 10, and the self-cleaning electrode 41 is disposed on the substrate 42. Specifically, the substrate 42 is made of an insulating material, such as polyimide, which has excellent electrical insulation and reliably ensures electrical safety. It is understood that in other embodiments, the material of the substrate 42 can be selected from other materials with excellent electrical insulation.

[0056] In one embodiment, the self-cleaning electrode 41 is parallel to the extension direction of the gas flow channel 21, so that the alternating electric field drives the particles in the gas to move in a direction perpendicular to the gas flow channel 21, thereby allowing the particles to enter the auxiliary flow channel 212 from the shortest distance, thereby improving the cleaning effect of the self-cleaning chip 40 on the particles.

[0057] In one embodiment, a plurality of self-cleaning electrodes 41 are arranged in sequence along the width direction of the substrate 42, and a second pad 43 is provided on the substrate 42, and the self-cleaning electrode 41 is connected to the second pad 43 through a second wire 44. Two groups of the second pad 43 are provided on the substrate 42, and are located at both ends of the substrate 42. The positive self-cleaning electrode 41 is connected to the same second pad 43 through the second wire 44, and the negative self-cleaning electrode 41 is connected to the same second pad 43 through the second wire 44, and the positive self-cleaning electrode 41 and the negative self-cleaning electrode 41 are arranged alternately in sequence.

[0058] See also Figure 6 The present invention also provides a gas flow detection method, and to implement the detection method, the above-mentioned gas flow sensor is used. Specifically, the detection method includes the following steps:

[0059] Step S110 : gas enters the gas flow channel 21 .

[0060] Specifically, the gas flow sensor is connected to the pipeline, and the external gas is introduced into the gas flow channel 21, and the gas mainly flows in the main flow channel 211. The gas can be a fuel gas, and there are microparticles with a particle size of several microns to tens of microns in the fuel gas. Of course, in other embodiments, the gas can also be other gases with particulate matter.

[0061] Step S120 : the detection chip 30 detects the flow rate of the gas in the gas flow channel 21 .

[0062] Specifically, the detection chip 30 can measure the flow rate of gas in the gas flow channel 21. Since the sensor is a MEMS flow sensor, the temperature measuring resistor film 31 and the heating resistor film 32 form a thermocouple stack and a heating resistor. When the fluid is stationary, the temperature of the symmetrical positions on both sides of the heating resistor is the same. When the fluid flows from left to right, the isotherms tilt to the right, and the temperature of the symmetrical positions on both sides of the heating resistor is no longer the same. The temperature difference can be measured by the thermocouple stacks placed on both sides of the heating resistor. Since the heat transfer of the fluid is only related to the mass of the fluid and the heat capacity of the fluid, the sensor can directly measure the mass flow of the fluid.

[0063] Step S130: the self-cleaning chip 40 is connected to an alternating voltage, and the self-cleaning electrode 41 excites an alternating electric field.

[0064] Specifically, the self-cleaning chip 40 is connected to an alternating voltage of 220V / 50Hz, and the two pairs of self-cleaning electrodes 41 excite an alternating electric field, which can generate a force perpendicular to the gas flow channel 21 on the particles.

[0065] Step S140 : driven by the alternating electric field, the particles in the gas enter the auxiliary flow channel 212 along a direction that forms an angle with the gas flow channel 21 .

[0066] Specifically, the microparticles, driven by the alternating electric field, move laterally in a direction having an angle with the gas flow channel 21, so that the microparticles can be driven into the auxiliary flow channels 212 on both sides of the main flow channel 211. In this embodiment, the microparticles, driven by the alternating electric field, move in a direction perpendicular to the gas flow channel 21, and the lateral movement distance of the microparticles is the shortest, which can improve the effect of the microparticles moving into the auxiliary flow channel 212. Of course, in other embodiments, the angle between the movement direction of the microparticles and the gas flow channel 21 can be specifically set as needed, and is not necessarily perpendicular as in this embodiment.

[0067] Step S150 : the particles entering the auxiliary flow channel 212 flow downstream along the auxiliary flow channel 212 along with the air flow, and then flow out of the gas flow channel 21 .

[0068] Specifically, the microparticles entering the auxiliary flow channel 212 flow downstream along the auxiliary flow channel 212 along with the airflow in the auxiliary flow channel 212, and then flow out of the gas flow sensor. After the microparticles are driven away to the auxiliary flow channel 212, the detection chip 30 located in the central main flow channel 211 effectively avoids the problem of being easily affected by the microparticles.

[0069] Gas flow sensor and gas flow detection method, the inlet section 24 and the outlet section 26 of the gas flow channel 21 are designed as arc flow channels, which can reduce the turbulence of the air flow at the inlet and outlet, and effectively improve the accuracy of the air flow velocity measurement. The self-cleaning chip 40 is used to generate an alternating electric field to drive the particles in the gas into the auxiliary flow channel 212 along the direction with an angle with the gas flow channel 21, thereby avoiding the micro-particles from adhering to the detection chip 30 in the main flow channel 211, thereby effectively solving the problem that the sensor chip is easily affected by the adhesion of micro-particles.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A gas flow sensor, characterized in that: include: Chip body; A cover body is disposed on the chip body, wherein the cover body and the chip body enclose a gas flow channel, wherein the gas flow channel includes a main flow channel and auxiliary flow channels disposed on both sides of the main flow channel, and the auxiliary flow channels are connected to the main flow channel; A detection chip is arranged in the main flow channel, the detection chip comprises a temperature measuring resistor film and a heating resistor film, a plurality of the temperature measuring resistor films are arranged in sequence along the gas flow channel, and the heating resistor film is arranged between two adjacent temperature measuring resistor films; and A self-cleaning chip is arranged outside the gas flow channel, and the self-cleaning chip includes a pair of self-cleaning electrodes. The pair of self-cleaning electrodes excite an alternating electric field to drive particles in the gas into the auxiliary flow channel along a direction having an angle with the gas flow channel; The self-cleaning electrode is parallel to the extension direction of the gas flow channel, so that the alternating electric field drives the particles in the gas to move in a direction perpendicular to the gas flow channel; The self-cleaning chip further comprises an insulating substrate, the substrate is bonded to the chip body, and the self-cleaning electrode is arranged on the substrate; A plurality of self-cleaning electrodes are arranged in sequence along the width direction of the substrate, and a second welding pad is provided on the substrate, and the self-cleaning electrode is connected to the second welding pad through a second wire; two groups of the second welding pad are provided on the substrate, located at both ends of the substrate; the self-cleaning electrode of the positive pole is connected to the same second welding pad through the second wire, and the self-cleaning electrode of the negative pole is connected to the same second welding pad through the second wire, and the self-cleaning electrode of the positive pole and the self-cleaning electrode of the negative pole are arranged alternately in sequence.

2. The gas flow sensor according to claim 1, characterized in that: The cover body is provided with a first groove, and the bottom wall of the first groove is provided with two second grooves at intervals. After the cover body is arranged on the chip body, the peripheral walls of the first groove, the second groove and the side wall of the chip body form the gas flow channel.

3. The gas flow sensor according to claim 1, characterized in that: The gas flow channel comprises an inlet section, a middle section and an outlet section, the middle section is in a straight line shape, and the inlet section and the outlet section are in an arc shape and are transitionally connected with the middle section.

4. The gas flow sensor according to claim 1, characterized in that: The heating resistor film and the temperature measuring resistor film are formed by folding a sensitive resistor film sheet, and the number of folded layers of the heating resistor film is less than the number of folded layers of the temperature measuring resistor film.

5. The gas flow sensor according to claim 4, characterized in that: The electrodes at both ends of the heating resistor film and the temperature measuring resistor film after folding are perpendicular to the gas flow channel.

6. The gas flow sensor according to claim 1, characterized in that: The detection chip also includes a first wire and a first pad. The heating resistor film and the temperature measuring resistor film are arranged on the chip body, and the first pad is located outside the gas flow channel. The heating resistor film and the temperature measuring resistor film are connected to the first pad through the first wire.

7. The gas flow sensor according to claim 1, characterized in that: The chip body comprises a substrate, an insulating layer and a heat-insulating layer. The insulating layer and the heat-insulating layer are sequentially arranged on the upper and lower surfaces of the substrate.

8. A method for detecting gas flow rate using the gas flow sensor according to any one of claims 1 to 7, characterized in that: The following steps are involved: The gas enters the gas flow channel; The detection chip detects the flow rate of gas in the gas flow channel; The self-cleaning chip is connected to an alternating voltage, and the self-cleaning electrode excites an alternating electric field; The particles in the gas are driven by the alternating electric field to enter the auxiliary flow channel along a direction having an angle with the gas flow channel; The particles entering the auxiliary flow channel flow downstream along the auxiliary flow channel along with the air flow, and then flow out of the gas flow channel.

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