Micro-tube flow sensor and micro-flow measurement method

Abstract

The present invention belongs to the technical field of intelligent sensing, and specifically relates to a micro-tube flow sensor and a micro-flow measurement method. The micro-tube flow sensor comprises: a resistive film base provided with a micro-flow channel; and a flow measurement module arranged on the resistive film base. The flow measurement module is located on an extension path of the micro-flow channel and used for measuring the flow of a fluid in the micro-flow channel. The micro-flow channel is recessed at an end part of the resistive film base, such that a cantilever beam is formed at the end part of the resistive film base, the flow measurement module being embedded in the cantilever beam. In the present invention, the micro-flow channel is integrated into the resistive film base, and the fluid to be measured is not in direct contact with the flow measurement module. Instead, as the micro-flow channel is in contact with the cantilever beam, said fluid flowing in the micro-flow channel transfers heat from the cantilever beam, and then the flow measurement module measures the temperature difference of the cantilever beam, thus achieving higher accuracy of measurement.

Description

Microtube flow sensor and microflow detection method Technical Field

[0001] This invention belongs to the field of intelligent sensing technology, specifically relating to microtube flow sensors and microflow detection methods. Background Technology

[0002] A flow sensor is a device used to measure the flow rate or velocity of a fluid (such as a gas or liquid) through a pipe or channel. These sensors are commonly used in various industrial applications, such as process control, environmental monitoring, and chemical analysis.

[0003] However, traditional micro-flow detection, such as CN102445246A, discloses a flow sensor chip and a cap bonded to the flow sensor chip. The flow sensor chip has a sensor sensitive area, which is equipped with a micro-heat source and a temperature sensor. The cap has a fluid flow channel, and the sensor sensitive area is located inside the fluid flow channel of the cap. The cap-type structure lacks the structural stability of a one-piece molding, and the fluid channel and the flow sensor chip are separate. In use, the sensor chip is placed directly at the fluid movement position to achieve flow sensing. When the gas flow rate is low and the flow is weak, the airflow is difficult to pass through the encapsulation shell and contact the chip, resulting in defects in the measurement accuracy and low sensitivity of traditional flow detection modules. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a microtube flow sensor and a microflow detection method to solve the problems of the lack of integral molding structural stability, measurement accuracy defects, and low sensitivity of the cap-type structure of the existing flow sensor.

[0005] One aspect of the present invention provides a microtube flow sensor, comprising:

[0006] A resistive film substrate, wherein microfluidic channels are provided on the resistive film substrate;

[0007] A flow detection module is disposed on the resistive film base and located on the extension path of the microfluidic channel and is used to detect the fluid flow rate in the microfluidic channel.

[0008] The microfluidic channel is recessed at the end of the resistive membrane base, forming a cantilever beam at the end of the resistive membrane base, and the flow detection module is embedded in the cantilever beam.

[0009] In one embodiment, the resistive film base includes a first connector and a second connector. The first connector and the second connector have a first groove and a second groove respectively formed on their opposite end faces. When the first connector and the second connector are closed and connected, the first groove and the second groove communicate to form the microfluidic channel. The cantilever beam is formed at the end of the first connector or the second connector facing away from the microfluidic channel.

[0010] In one embodiment, both the first connector and the second connector are fabricated from silicon wafers and are bonded together using MEMS technology.

[0011] In one embodiment, the resistive film base includes two sets of support platforms, which are respectively disposed at both ends of the cantilever beam. The microfluidic channel is formed between the two sets of support platforms. The overall cross-section of the cantilever beam and the two sets of support platforms is arranged in a U-shape. The thickness of the two sets of support platforms is greater than that of the cantilever beam. A receiving groove is formed between the two sets of support platforms. The microfluidic channel is laid on the groove wall of the receiving groove. Both ends of the microfluidic channel extend to the outside of the receiving groove. The microfluidic channel is tightly fitted to the cantilever beam.

[0012] In one embodiment, the resistive film base further includes a limiting seat that covers the two sets of support platforms, with the end of the limiting seat extending into the receiving groove and limiting the microfluidic channel within the receiving groove.

[0013] In one embodiment, the resistive film base is made of alloy ceramic and has a rectangular cross-section. The resistive film base is integrally formed by pressing or injection molding. The microfluidic channel is formed inside the resistive film base, and both ends of the microfluidic channel are connected to the outside of the resistive film base. The cross-section of the microfluidic channel is shaped like a geometric shape. The middle section of the microfluidic channel is close to the top of the resistive film base. The end of the resistive film base near the middle section of the microfluidic channel forms a cantilever beam. The flow detection module is located at the top of the resistive film base.

[0014] In one embodiment, the flow detection module includes a thermistor film and a heating unit. The thermistor film and the heating unit are sequentially and spaced apart along the length of the cantilever beam at the end of the cantilever beam away from the microfluidic channel. The thermistor film is electrically connected to a control system and provides real-time feedback of its resistance value to the control system. The heating unit is used to heat the thermistor film.

[0015] In one embodiment, the number of thermistor films is two sets, with the two sets of thermistor films spaced apart on both sides of the heating unit.

[0016] In one embodiment, the resistive film base further includes a heat-insulating cover, which is arranged in a U-shape. The two ends of the heat-insulating cover are connected to the two ends of the cantilever beam, and the middle position of the heat-insulating cover is suspended above the cantilever beam. An isolation cavity for accommodating the thermistor film and the heating unit is formed between the heat-insulating cover and the cantilever beam.

[0017] One of the solutions also describes a micro-flow detection method, which includes the following steps:

[0018] When the heating unit is working, heat is conducted to the thermistor film through the cantilever beam of the resistive film base, so that the two sets of thermistor films are heated synchronously.

[0019] The fluid to be tested moves along the microfluidic channel, and the fluid conducts heat with the cantilever beam of the resistive film base, so that the heat of the cantilever beam is transferred along a preset path.

[0020] After being affected by the fluid, the heating rates of the two sets of thermistor films deviate, and the resistance parameters fed back to the control system by the two sets of thermistor films have a resistance difference.

[0021] The control system calculates the fluid flow parameters in the current microfluidic channel by measuring the resistance difference.

[0022] The beneficial effects of the microtube flow sensor and microflow detection method provided by the above solutions of the present invention are as follows:

[0023] 1. By integrating the microfluidic channel into the resistive film substrate, the fluid to be measured does not directly contact the flow detection module. Instead, it contacts the cantilever beam through the microfluidic channel. The fluid to be measured flowing inside the microfluidic channel transfers heat from the cantilever beam, interfering with the original heat flow direction of the flow detection module on the cantilever beam. Thus, by detecting the temperature difference of the resistance on the flow detection module, higher measurement accuracy can be achieved.

[0024] 2. The cantilever beam is heated by the operation of the heating film. Under no-flow (static) conditions, the temperature distribution around the heating film is symmetrical, forming a symmetrical temperature field, and the resistance value of the thermistor remains stable. When there is fluid flow in the microfluidic channel, the fluid transfers heat from the cantilever beam, and the resistance value of the thermistor set adjacent to the heating film changes. The temperature change is obtained by the change in resistance value, thereby realizing the measurement of fluid flow rate.

[0025] 3. The thermal films placed on both sides of the heating film are very sensitive to temperature changes and can detect the temperature difference of the cantilever beam caused by fluid flow. By measuring the temperature difference of the cantilever beam, the flow velocity or flow rate of the fluid can be deduced; thus solving the problem of low sensitivity of microtube flow sensor when the gas flow velocity is low and the flow rate is weak. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 shows a schematic diagram of the microtube flow sensor of the present invention;

[0028] Figure 2 shows a schematic diagram of the structure of the first connecting seat of the present invention;

[0029] Figure 3 shows a schematic diagram of the structure of the second connecting seat of the present invention;

[0030] Figure 4 shows a schematic diagram of the microfluidic channel structure of the present invention;

[0031] Figure 5 shows a schematic diagram of the structure of a microtube flow sensor according to another embodiment of the present invention;

[0032] Figure 6 shows a schematic diagram of the internal structure of the microtube flow sensor of the present invention;

[0033] Figure 7 shows a cross-sectional view of the microtube flow sensor of the present invention;

[0034] Figure 8 shows a schematic diagram of the structure of a microtube flow sensor according to another embodiment of the present invention;

[0035] Figure 9 shows a three-dimensional structural schematic diagram of the microtube flow sensor of the present invention;

[0036] Figure 10 shows a cross-sectional view of the microtube flow sensor of the present invention;

[0037] Figure 11 shows a schematic diagram of the heating unit of the present invention;

[0038] Figure 12 shows a schematic diagram of the flow detection module according to another embodiment of the present invention.

[0039] The reference numerals are shown in the figure: 10-resistive film base; 11-microfluidic channel; 12-cantilever beam; 13-support platform; 14-limiting seat; 15-heat insulation cover; 101-first connecting seat; 102-second connecting seat; 103-first groove; 104-second groove; 20-flow detection module; 21-thermistor film; 22-heating unit; 221-substrate; 222-heating coil. Detailed Implementation

[0040] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0042] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0043] Referring to Figures 1-10, one embodiment of the present invention provides a microtube flow sensor, comprising:

[0044] A resistive film base 10, on which a microfluidic channel 11 is provided;

[0045] A flow detection module 20 is disposed on the resistive film base 10. The flow detection module 20 is located on the extension path of the microfluidic channel 11 and is used to detect the fluid flow rate in the microfluidic channel 11.

[0046] The microfluidic channel 11 is recessed at the end of the resistive film base 10, so that the end of the resistive film base 10 is formed with a cantilever beam 12, and the flow detection module 20 is embedded in the cantilever beam 12.

[0047] In this embodiment, the flow detection module 20 is embedded on the cantilever beam 12. The fluid to be measured does not directly contact the flow detection module 20. Instead, after the fluid to be measured in the microfluidic channel 11 contacts the cantilever beam 12, the fluid to be measured flowing in the microfluidic channel 11 transfers the heat on the cantilever beam 12, interfering with the original heat flow direction on the cantilever beam 12. Then, by detecting the change in the resistance value of the thermosensitive element in the flow detection module 20 on the cantilever beam 12, the temperature change is obtained, achieving higher measurement accuracy.

[0048] Please refer to FIGS. 2-4. In one embodiment, the resistive film base 10 includes a first connection base 101 and a second connection base 102. First grooves 103 and second grooves 104 are formed on the end faces of the first connection base 101 and the second connection base 102 that face each other. When the first connection base 101 and the second connection base 102 are covered and connected, the first grooves 103 and the second grooves 104 are connected to form the microfluidic channel 11. The cantilever beam 12 is formed at the end of the first connection base 101 or the second connection base 102 that faces away from the microfluidic channel 11.

[0049] In this embodiment, by covering and connecting the first connection base 101 with the first groove 103 and the second connection base 102 with the second groove 104, the first groove 103 and the second groove 104 are connected to form the microfluidic channel 11. The forming scheme of the microfluidic channel 11 in this solution is simple, and the first groove 103 and the second groove 104 can be flexibly designed according to different application scenarios. For example, the first groove 103 and the second groove 104 are formed into a "冂" - shaped structure to form a "冂" - shaped microfluidic channel 11, which is convenient for arranging the flow detection module 20 on the cantilever beam 12 at the top position of the microfluidic channel 11, enabling the fluid to be measured to fully contact the cantilever beam 12, and thus achieving better measurement accuracy.

[0050] In one embodiment, both the first connection base 101 and the second connection base 102 are made of silicon wafers and are formed by MEMS bonding.

[0051] Bonding is a technology that directly combines two clean and atomically flat homogeneous or heterogeneous semiconductor materials after surface cleaning and activation treatment, and bonds the wafers into one body through van der Waals force, molecular force, or even atomic force under certain conditions. In this embodiment, the first connection base 101 and the second connection base 102 are formed by MEMS bonding, ensuring the mechanical stability, sealing performance of the resistive film base 10 and the microfluidic channel 11, and the functional satisfaction of the device.

[0052] Referring to Figures 5-7, in one embodiment, the resistive film base 10 includes two sets of support platforms 13, which are respectively disposed at both ends of the cantilever beam 12. The microfluidic channel 11 is formed between the two sets of support platforms 13. The overall cross-section of the cantilever beam 12 and the two sets of support platforms 13 is arranged in a U-shape. The thickness of the two sets of support platforms 13 is greater than that of the cantilever beam 12. A receiving groove is formed between the two sets of support platforms 13. The microfluidic channel 11 is laid on the groove wall of the receiving groove. Both ends of the microfluidic channel 11 extend to the outside of the receiving groove. The microfluidic channel 11 is tightly fitted with the cantilever beam 12.

[0053] In this embodiment, the cantilever beam 12 and the two sets of support platforms 13 are arranged in a U-shape. A receiving groove is formed between the two sets of support platforms 13. The microfluidic pipe 11 is laid on the wall of the receiving groove. The two sets of support platforms 13 are used to make the microfluidic pipe 11 fit tightly with the cantilever beam 12. When the fluid to be measured flows through the microfluidic pipe 11 through the cantilever beam 12, the pipe wall of the microfluidic pipe 11 is in full contact with the cantilever beam 12, thereby achieving better measurement accuracy.

[0054] Referring to Figures 8-10, in one embodiment, the resistive film base 10 further includes a limiting seat 14, which covers the two sets of support platforms 13. The end of the limiting seat 14 extends into the receiving groove and limits the microfluidic channel 11 within the receiving groove.

[0055] In this embodiment, the limiting seat 14 is used to cooperate with the U-shaped structure formed by the cantilever beam 12 and the two sets of support platforms 13. When the limiting seat 14 is placed on the two sets of support platforms 13, the end of the limiting seat 14 extends into the receiving groove and limits the microfluidic pipe 11 in the receiving groove, ensuring that the pipe wall of the microfluidic pipe 11 is fully in contact with the cantilever beam 12, thereby achieving better measurement accuracy.

[0056] In one embodiment, the resistive film base 10 is made of alloy ceramic and has a rectangular cross-section. The resistive film base 10 is integrally formed by pressing or injection molding. The microfluidic channel 11 is formed inside the resistive film base 10, and both ends of the microfluidic channel 11 are connected to the outside of the resistive film base 10. The cross-section of the microfluidic channel 11 is of a geometric shape. The middle section of the microfluidic channel 11 is close to the top of the resistive film base 10. The end of the resistive film base 10 near the middle section of the microfluidic channel forms the cantilever beam 12. The flow detection module 20 is disposed at the top of the resistive film base 10.

[0057] In this embodiment, the microfluidic channel 11 is integrated onto the resistive film base 10 by integral molding, and the middle section of the microfluidic channel 11 is close to the top of the resistive film base 10 to ensure that the wall of the microfluidic channel 11 is in full contact with the cantilever beam 12. When fluid flows in the microfluidic channel 11, the fluid transfers the heat on the cantilever beam 12, and the resistance value of the thermistor film 21 adjacent to the heating unit 22 changes. The temperature change is obtained by the change in resistance value, thereby achieving better measurement accuracy.

[0058] In one embodiment, the flow detection module 20 includes a thermistor film 21 and a heating unit 22. The thermistor film 21 and the heating unit 22 are sequentially and spaced apart along the length of the cantilever beam 12 at the end of the cantilever beam 12 away from the microfluidic channel 11. The thermistor film 21 is electrically connected to a control system and provides real-time feedback of its resistance value to the control system. The heating unit 22 is used to heat the thermistor film 21.

[0059] In this embodiment, the cantilever beam 12 is heated by the operation of the heating unit 22. Under no-flow (static) conditions, the temperature distribution around the heating unit 22 is symmetrical, forming a symmetrical temperature field, and the resistance value of the thermistor film 21 remains stable. When there is fluid flow in the microfluidic channel 11, the fluid transfers the heat from the cantilever beam 12, and the resistance value of the thermistor film 21 adjacent to the heating unit 22 changes. The temperature change is obtained by the change in resistance value, thereby realizing the measurement of fluid flow rate.

[0060] In one embodiment, the number of thermistor films 21 is two sets, and the two sets of thermistor films 21 are spaced apart on both sides of the heating unit 22.

[0061] Referring to Figures 9-10, in one embodiment, the resistive film base 10 further includes a heat-insulating cover 15. The heat-insulating cover 15 is arranged in a U-shape. The two ends of the heat-insulating cover 15 are connected to the two ends of the cantilever beam 12. The middle position of the heat-insulating cover 15 is suspended above the cantilever beam 12. An isolation cavity for accommodating the thermistor film 21 and the heating unit 22 is formed between the heat-insulating cover 15 and the cantilever beam 12.

[0062] In this embodiment, the insulating cavity formed between the heat-insulating cover 15 and the cantilever beam 12 effectively isolates heat, preventing the thermal influence of the external environment from interfering with the thermistor film 21 and the heating unit 22, ensuring that they can operate normally within a certain temperature range. This improves the stability and reliability of the equipment, ensuring that it operates within the expected temperature range. The heat-insulating cover 15 provides an additional protective layer, preventing external dust, moisture, and other impurities from adhering to the thermistor film 21 and the heating unit 22, thereby protecting them from damage or contamination.

[0063] One embodiment also discloses a micro-flow detection method, comprising the following steps:

[0064] S10, The heating unit works, and heat is conducted to the thermistor film through the cantilever beam of the resistive film base, so that the two sets of thermistor films are heated synchronously.

[0065] S20. The fluid to be tested moves along the microfluidic channel, and the fluid conducts heat with the cantilever beam of the resistive film base, so that the heat of the cantilever beam is transferred along the preset path.

[0066] S30. After being affected by the fluid, the heating rates of the two sets of thermistor films deviate, and there is a resistance difference in the resistance parameters fed back to the control system by the two sets of thermistor films.

[0067] S40. The control system calculates the fluid flow parameters in the current microfluidic channel by measuring the resistance difference.

[0068] In this solution, by integrating the microfluidic channel into the resistive membrane base, the heating unit operates, and heat is conducted to the thermistor membranes through the cantilever beam of the resistive membrane base, causing the two sets of thermistor membranes to heat up synchronously. When the fluid to be detected moves along the microfluidic channel, heat conduction occurs between the fluid and the cantilever beam of the resistive membrane base, causing the heat of the cantilever beam to transfer along a preset path, interfering with the original heat flow direction of the flow detection module on the cantilever beam. This causes a deviation in the heating rate of the two sets of thermistor membranes, resulting in a resistance difference in the resistance parameters fed back to the control system. The control system calculates the fluid flow parameters in the current microfluidic channel based on the resistance difference, achieving higher measurement accuracy.

[0069] During application, the thermal conduction between the heat source and the substrate can affect the measurement accuracy. By selecting a substrate material with a high thermal conductivity, the convective heat transfer between the heat source and the cantilever beam 12 can become the dominant part of the heat conduction process.

[0070] Therefore, in another embodiment of the present invention, the flow detection module 20 includes a thermistor film 21 and a heating unit 22, wherein the thermistor film 21 and the heating unit 22 are sequentially and spaced apart along the length direction of the cantilever beam 12 at the end of the cantilever beam 12 away from the microfluidic channel 11. The thermistor film 21 is in two sets, and the two sets of thermistor films 21 are spaced apart on both sides of the heating unit 22.

[0071] Referring to Figure 11, the heating unit 22 includes a substrate 221 and a heating coil 222. The substrate 221 has a through hole, and the heating coil 222 is embedded inside the through hole and fits against the edge of the through hole. Alternatively, the heating coil 222 is encapsulated inside the substrate 221 to allow the heat of the heating coil 222 to be uniformly conducted through the substrate 221, thereby enabling the heating unit 22 to obtain good temperature uniformity, reducing heat conduction loss, which is beneficial to forming a symmetrically distributed temperature field on the cantilever beam 12, and effectively reducing the overall power consumption of the device.

[0072] In one application scenario of this embodiment, the heating coil 222 can be arranged in a spiral or bent shape to increase the contact area between the heating coil 222 and the substrate 221. The substrate 221 can be made of a metal material with good thermal conductivity, such as copper alloy, aluminum alloy or nickel-plated alloy material, to enable the heating unit to obtain good temperature uniformity.

[0073] During application, when the ambient temperature changes, the temperature compensation capability of a single heat source is poor. When the ambient temperature is unstable, the flow detection module 20 of a single heat source is greatly affected, and errors are easily made in the flow detection of the fluid.

[0074] Therefore, in another embodiment of the present invention, the flow detection module 20 includes a thermistor film 21 and a heating unit 22, wherein the thermistor film 21 and the heating unit 22 are sequentially and spaced apart along the length direction of the cantilever beam 12 at the end of the cantilever beam 12 away from the microfluidic channel 11. The thermistor film 21 is in two sets, and the two sets of thermistor films 21 are spaced apart on both sides of the heating unit 22.

[0075] Referring to Figure 12, the heating unit 22 includes two heat sources arranged parallel to each other on the cantilever beam 12. One set of thermistor films 21 is arranged on the left side of the heating unit 22, and the other set of thermistor films 21 is arranged on the right side of the heating unit 22. Through the two heat sources contained in the heating unit 22, both the upstream and downstream heat sources have the function of temperature sensing and have excellent response time. At the same time, the dual heat sources have good temperature compensation capability for changes in ambient temperature, which is suitable for working conditions with unstable temperature and can effectively improve measurement accuracy.

[0076] In one application scenario of this embodiment, the heating unit 22 can be configured to include two or more heat sources to improve temperature compensation capability and is suitable for working conditions with unstable temperature.

[0077] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A microtube flow sensor, characterized in that, include: A resistive film substrate, wherein microfluidic channels are provided on the resistive film substrate; A flow detection module is disposed on the resistive film base and located on the extension path of the microfluidic channel and is used to detect the fluid flow rate in the microfluidic channel. The microfluidic channel is recessed at the end of the resistive membrane base, forming a cantilever beam at the end of the resistive membrane base, and the flow detection module is embedded in the cantilever beam.

2. The microtube flow sensor according to claim 1, characterized in that: The resistive film base includes a first connecting seat and a second connecting seat. The first connecting seat and the second connecting seat have a first groove and a second groove respectively formed on their opposite end faces. When the first connecting seat and the second connecting seat are closed and connected, the first groove and the second groove communicate to form the microfluidic channel. The cantilever beam is formed at the end of the first connecting seat or the second connecting seat facing away from the microfluidic channel.

3. The microtube flow sensor according to claim 2, characterized in that: Both the first connector and the second connector are made of silicon wafers and are bonded together using MEMS technology.

4. The microtube flow sensor according to claim 1, characterized in that: The resistive film base includes two sets of support platforms, which are respectively disposed at both ends of the cantilever beam. The microfluidic channel is formed between the two sets of support platforms. The overall cross-section of the cantilever beam and the two sets of support platforms is arranged in a U-shape. The thickness of the two sets of support platforms is greater than that of the cantilever beam. A receiving groove is formed between the two sets of support platforms. The microfluidic channel is laid on the groove wall of the receiving groove. Both ends of the microfluidic channel extend to the outside of the receiving groove. The microfluidic channel is tightly fitted to the cantilever beam.

5. The microtube flow sensor according to claim 4, characterized in that: The resistive film base also includes a limiting seat, which covers the two sets of support platforms. The end of the limiting seat extends into the receiving groove and limits the microfluidic channel within the receiving groove.

6. The microtube flow sensor according to claim 1, characterized in that: The resistive film base is made of alloy ceramic and has a rectangular cross-section. The resistive film base is integrally formed by pressing or injection molding. The microfluidic channel is formed inside the resistive film base, and both ends of the microfluidic channel are connected to the outside of the resistive film base. The cross-section of the microfluidic channel is shaped like a geometric shape. The middle section of the microfluidic channel is close to the top of the resistive film base. The end of the resistive film base near the middle section of the microfluidic channel forms a cantilever beam. The flow detection module is located at the top of the resistive film base.

7. The microtube flow sensor according to any one of claims 1 to 6, characterized in that: The flow detection module includes a thermistor film and a heating unit. The thermistor film and the heating unit are sequentially and spaced apart along the length of the cantilever beam at the end of the cantilever beam away from the microfluidic channel. The thermistor film is electrically connected to a control system and provides real-time feedback of its resistance value to the control system. The heating unit is used to heat the thermistor film.

8. The microtube flow sensor according to claim 7, characterized in that: The thermistor film is in two sets, and the two sets of thermistor films are spaced apart on both sides of the heating unit.

9. The microtube flow sensor according to claim 7, characterized in that: The resistive film base also includes a heat-insulating cover, which is arranged in a U-shape. The two ends of the heat-insulating cover are connected to the two ends of the cantilever beam, and the middle position of the heat-insulating cover is suspended above the cantilever beam. An isolation cavity is formed between the heat-insulating cover and the cantilever beam to accommodate the thermistor film and the heating unit.

10. A micro-flow rate detection method, characterized in that, Includes the following steps: When the heating unit is working, heat is conducted to the thermistor film through the cantilever beam of the resistive film base, so that the two sets of thermistor films are heated synchronously. The fluid to be tested moves along the microfluidic channel, and the fluid conducts heat with the cantilever beam of the resistive film base, so that the heat of the cantilever beam is transferred along a preset path. After being affected by the fluid, the heating rates of the two sets of thermistor films deviate, and the resistance parameters fed back to the control system by the two sets of thermistor films have a resistance difference. The control system calculates the fluid flow parameters in the current microfluidic channel by measuring the resistance difference.

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