CN113624290B - Flexible airflow sensor and preparation method and application thereof - Google Patents
Flexible airflow sensor and preparation method and application thereof Download PDFInfo
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- CN113624290B CN113624290B CN202110912092.0A CN202110912092A CN113624290B CN 113624290 B CN113624290 B CN 113624290B CN 202110912092 A CN202110912092 A CN 202110912092A CN 113624290 B CN113624290 B CN 113624290B
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- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
Abstract
The invention provides a flexible airflow sensor and a preparation method and application thereof, wherein the flexible airflow sensor sequentially comprises a substrate, an interdigital electrode, an adhesive layer and a carbon fiber fluff array structure from bottom to top; and the carbon fibers in the carbon fiber fluff array structure penetrate through the adhesive layer and are in contact with the interdigital electrodes. The carbon fiber fluff array structure of the flexible airflow sensor can deform under the action of weak airflow, so that the contact resistance among the fluff is changed, and the response to the external airflow is realized. The flexible airflow sensor can detect the flow velocity of gas, has the characteristics of high response speed, low detection limit, wide detection range, good stability and the like, and is simple in preparation process, free of complex equipment and low in cost.
Description
Technical Field
The invention belongs to the technical field of sensors, relates to a flexible airflow sensor and a preparation method and application thereof, and particularly relates to a flexible airflow sensor based on a carbon fiber fluff array structure and a preparation method and application thereof.
Background
The airflow sensor is widely applied in various fields such as meteorology, biomedicine, industrial production and the like. Many applications require that airflow sensors be compact, lightweight, flexible, highly reliable, easily manufactured, and low in cost. Current airflow sensors include mechanical airflow sensors, hot wire thermal film airflow sensors, laser doppler flow velocity detection sensors, and the like. These measuring devices are complex, have large volume and weight, and are difficult to meet the requirements of various application scenarios.
In nature, organisms develop a plurality of ingenious micro sensing structures through long-term evolution, and the micro sensing structures are worth researching and using for reference. For example, many animal and plant epidermis or surfaces are covered by cilia (or hair), and a weak airflow or vibration can cause deformation of the cilia, and the tiny deformation triggers the impulse of nerve cells under the cilia, thereby obtaining the perception capability. The characteristics of tiny size, flexibility, sensitivity and quickness are often beyond the capability of artificial sensors.
There are many related works disclosed. CN112858717A discloses a bionic airflow sensor, wherein under the action of airflow, a bristle bar structure in a through hole deflects relative to a base, at least one slit in a measurement area is extruded, and airflow velocity detection is realized. The invention has simple structure, is difficult to meet the requirements of compactness, portability and flexibility, and has higher detection limit. CN112858716A discloses a micro air flow sensor. When the micro gas acts on the graphene layer, the graphene layer is deformed, the carrier density of the graphene layer is changed, and the flow velocity of the gas flow is measured through input current. The method has the advantages that the units are too many and are not easy to operate, and the detection range is narrow aiming at micro airflow. CN112881478A discloses a miniaturized dual-function airflow sensor based on silicon micro/nanowire, which utilizes a single silicon micro/nanowire to form a conductive loop for airflow sensing, and the method has simple preparation process and high sensitivity, and if the substrate adopts flexible polymer, the wearable requirement can be realized, but if a single silicon micro/nanowire is adopted, the problem of stability may exist. CN109322147A discloses a carbonized fabric loaded with carbon nanotubes and a method for preparing an airflow sensor thereof, the invention has the advantages of flexibility and excellent airflow sensing performance, but the temperature in the preparation process is too high (> 500 ℃), and the adhesion may be poor.
Accordingly, it is desirable in the art to develop an efficient, simple, flexible airflow sensor.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a flexible airflow sensor and a preparation method and application thereof, and particularly provides a flexible airflow sensor based on a carbon fiber fluff array structure and a preparation method and application thereof. The flexible airflow sensor has excellent airflow sensing performance, can detect the flow rate of gas, has high response speed, low detection limit, wide range, good stability and good operability, is flexible, can be attached to the surface of a substrate with any shape, and has a simple preparation method without high temperature conditions. The flexible airflow sensor has great application prospect in practical scenes of monitoring the flow speed, judging the air leakage position of a complex pipeline and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a flexible airflow sensor, which sequentially comprises a substrate, an interdigital electrode, an adhesive layer and a carbon fiber fluff array structure from bottom to top;
and the carbon fibers in the carbon fiber fluff array structure penetrate through the adhesive layer to be in contact with the interdigital electrodes.
The carbon fiber fluff array structure on the flexible airflow sensor is similar to the cilium structure of insects in nature, and can deform under the action of weak airflow, so that the sensor can quickly and accurately react to the airflow.
According to the invention, the carbon fiber fuzz in the carbon fiber fuzz array structure is in mutual lap contact to form a conductive network, the orientation of the conductive network has the characteristic of quasi-verticality, and meanwhile, the carbon fiber penetrating adhesive layer is in contact with the interdigital electrode. Because the adhesive layer is non-conductive, the carbon fibers in the carbon fiber fluff array structure need to be in contact with the interdigital electrodes to transmit current to the interdigital electrodes to form a current loop, so that the sensing function is realized. By "quasi-perpendicular" in the context of the present invention is meant that the carbon fibers are oriented substantially perpendicular to the adhesive layer, i.e., the number of fibers oriented at an angle greater than 45 ° relative to the adhesive layer (or substrate) exceeds 90%.
The sensing principle of the flexible airflow sensor provided by the invention is as follows: the carbon fiber fluff array structure is similar to a cilium structure of an insect in nature, and because the carbon fibers have excellent conductivity, the quasi-vertically oriented carbon fibers are mutually lapped to form a conductive network. The conductive network formed by the carbon fiber fluff array structure deforms under the action of airflow with different flow velocities, and the contact resistance between the carbon fiber fluff arrays is correspondingly changed due to different deformation quantities, so that the airflow is sensed.
Preferably, the carbon fiber fluff array structure is composed of carbon fibers.
Preferably, the carbon fibers include polyacrylonitrile-based carbon fibers or pitch-based carbon fibers.
Preferably, the carbon fibers have a diameter of 7-10 μm, such as 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, or 10 μm, etc.
Preferably, the carbon fibers have a length of 100-500 μm, such as 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, etc.
If the length of the carbon fiber is less than 100 μm, the orientation of the carbon fiber in an electrostatic field is too poor, the carbon fiber is almost completely laid down, the deformation under the action of an air flow is slight, and the sensing performance is poor, and if the length of the carbon fiber is more than 500 μm, the orientation of the carbon fiber in the electric field is excellent, so that the area density is increased, and the excessive area density prevents the deformation of the carbon fiber when being blown by the air flow, so that the sensing performance is reduced.
The accessible is cut up the carbon fiber that obtains above-mentioned length with original carbon fiber, cuts up the back with original carbon fiber, in order to obtain the carbon fiber fine hair that length is close, accessible mechanical vibration's mode adopts the screen cloth to divide the sieve to carbon fiber fine hair, and concrete operation is as follows:
placing the cut carbon fiber fluff into a mechanical vibrating screen, wherein the mesh number of the screen is as follows from top to bottom: 100 meshes, 200 meshes and 300 meshes, and mechanically vibrating and screening for 1-3h. The length of the carbon fibers on each mesh screen is close, e.g., the length of the carbon fibers on a 100 mesh screen is substantially uniform, the length of the carbon fibers on a 200 mesh screen is substantially uniform, and the length of the carbon fibers on a 300 mesh screen is substantially uniform.
Preferably, the substrate is a flexible polymeric film.
Preferably, the flexible polymer film comprises a Polyimide (PI) film or a polyethylene terephthalate (PET) film, preferably a polyimide film.
Preferably, the adhesive layer has a thickness of 5-20 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, and the like. If the thickness of the adhesive layer is less than 5 μm, the carbon fiber fluff array structure cannot be maintained, and the carbon fibers may be detached by the air flow, resulting in failure of the sensor. And if the thickness of the adhesive layer is more than 20 μm, the carbon fibers cannot penetrate through the adhesive layer, and the sensing performance cannot be realized.
Preferably, the adhesive layer has a Young's modulus of 500 to 1500kPa, such as 500kPa, 600kPa, 700kPa, 800kPa, 900kPa, 1000kPa, 1100kPa, 1200kPa, 1300kPa, 1400kPa, 1500kPa, or the like.
Preferably, the adhesive layer is formed by curing an adhesive, and the preparation method of the adhesive comprises the following steps:
mixing a flexible polymer and a curing agent to obtain the adhesive.
Preferably, the flexible polymer comprises Dow Corning 184 silicone rubber A component. The modulus of the flexible polymer (namely the Young modulus of the adhesive layer) after the curing agent is added and cured is closer to the modulus of human skin, the deformation of the carbon fiber fluff array structure when blown by airflow is facilitated, and the carbon fiber fluff array structure is non-toxic, odorless, physiologically inert, good in chemical stability, compatible with a human body and beneficial to application in wearable electronic devices.
Preferably, the curing agent comprises Dow Corning 184 silicone rubber B component.
Preferably, the mass ratio of the flexible polymer to the curing agent is (10-20) 1, 11.
Preferably, the mixing is performed in a deaerator mixer.
Preferably, the mixing further comprises a vacuum defoaming step.
In a second aspect, the present invention provides a method for preparing the flexible airflow sensor of the first aspect, the method comprising the following steps:
(1) Fixing a metal mask plate of the interdigital electrode on a substrate, and putting the metal mask plate into a thermal evaporation instrument to deposit a metal target material to obtain the substrate deposited with the interdigital electrode;
(2) Coating an adhesive on the substrate obtained in the step (1) to cover the interdigital part of the interdigital electrode, so as to obtain the substrate coated with the adhesive layer;
(3) And (3) attaching carbon fibers to the adhesive layer of the substrate obtained in the step (2) to obtain a substrate attached with a carbon fiber fluff array structure, and performing post-treatment to obtain the flexible airflow sensor.
In the invention, the flexible airflow sensor has simple preparation method and mild preparation condition, does not need high temperature condition, and can be prepared even at normal temperature.
Preferably, step (1) further includes a step of cleaning the substrate before the metal mask plate for fixing the interdigital electrodes on the substrate. For example, the surface of the substrate may be cleaned using acetone.
Preferably, the fixing manner in the step (1) comprises fixing with an adhesive tape.
Preferably, the metal target material in step (1) comprises chromium or gold.
Preferably, the coating manner of the step (2) comprises coating by a film applicator or wire rod coating.
The step (2) of covering the interdigital electrode with the interdigital portion means that the coating area of the adhesive is larger than the interdigital electrode portion.
Preferably, the step (3) of attaching the carbon fibers to the adhesive layer of the substrate obtained in the step (2) specifically includes the following steps:
dispersing carbon fibers on a lower polar plate of a high-voltage electrostatic device, fixing the substrate obtained in the step (2) on an upper polar plate of the high-voltage electrostatic device, turning on a power switch of the high-voltage electrostatic device, and enabling the carbon fibers to fly to the substrate under the action of a high-voltage electrostatic field to obtain the substrate attached with a carbon fiber fluff array structure.
Preferably, the dispersing manner in the step (3) includes vibration dispersing.
Preferably, the fixing manner in the step (3) includes fixing with an adhesive tape.
Preferably, the voltage of the high voltage electrostatic device in step (3) is 10-30kV, such as 10kV, 15kV, 20kV, 25kV or 30kV, etc., and the energizing time is 10-20s, such as 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s or 20s, etc.
Preferably, the distance between the upper plate and the lower plate in step (3) is 5-15cm, such as 5cm, 6cm, 7cm, 8cm, 9cm, 10cm, 11cm, 12cm, 13cm, 14cm or 15cm.
Preferably, the high voltage electrostatic device has an electric field strength of 1-3kV/cm, such as 1kV/cm, 1.2kV/cm, 1.5kV/cm, 1.8kV/cm, 2kV/cm, 2.2kV/cm, 2.5kV/cm, 2.8kV/cm, or 3kV/cm, and the like.
The carbon fiber with a certain length can penetrate through an adhesive layer with proper thickness in a quasi-vertical characteristic and contact with the interdigital electrode.
If the distance between the upper polar plate and the lower polar plate is less than 5cm, the upper polar plate and the lower polar plate are easy to be punctured to damage equipment, and if the distance between the upper polar plate and the lower polar plate is more than 15cm, the electric field intensity between the polar plates is small, so that the acceleration of the carbon fiber moving in an electric field is small, and the carbon fiber can not be punctured through the adhesive layer.
Preferably, the post-treatment of step (3) comprises curing.
Preferably, the curing is performed in an oven.
Preferably, the curing temperature is 70-90 ℃, such as 70 ℃, 73 ℃, 75 ℃, 78 ℃, 80 ℃, 83 ℃, 85 ℃, 88 ℃ or 90 ℃ and the like.
Preferably, the curing time is 100-130min, such as 100min, 105min, 110min, 115min, 120min, 125min or 130min, and the like.
The substrate is put into an oven for curing, so that the adhesive layer can be cured quickly. The adhesive layer can be cured for 100-130min at 70-90 ℃ or at normal temperature, but the curing time is longer, namely, the flexible airflow sensor can be prepared at normal temperature.
Preferably, the curing is followed by removing excess carbon fibers from the surface of the carbon fiber fluff array structure using a high pressure air gun or a dust suction device. Some carbon fibers do not penetrate the adhesive layer and float on the surface of the carbon fiber fluff array structure, which can be removed using a high pressure air gun or a vacuum.
In a third aspect, the present invention provides the use of the flexible gas flow sensor of the first aspect for gas flow rate detection.
Preferably, the external signal detectable by the flexible airflow sensor is an airflow signal.
Preferably, the gas flow signal comprises air, nitrogen or argon.
Preferably, the flow rate of the airflow signal detectable by the flexible airflow sensor ranges from 1L/min to 50L/min, such as 1L/min, 5L/min, 10L/min, 20L/min, 30L/min, 40L/min, or 50L/min.
Preferably, the angle of action of the air flow signal is 0-90 °, such as 0 °,10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, or 90 °, etc.
Compared with the prior art, the invention has the following beneficial effects:
the carbon fiber fluff array structure on the flexible airflow sensor is similar to a cilium structure of an insect in the nature, and can deform under the action of weak airflow, so that the sensor can quickly and accurately react to the airflow. The flexible airflow sensor has the advantages of high response speed, low detection limit (1L/min), wide detection range (1L/min-50L/min), good stability, flexibility and capability of being attached to the surface of a substrate in any shape.
Drawings
Fig. 1 is a schematic structural diagram of the flexible airflow sensor provided in example 1, wherein a 1-substrate, a 2-interdigital electrode, a 3-adhesive layer, and a 4-carbon fiber fluff array structure are adopted.
Fig. 2 is a top scanning electron microscope image of the carbon fiber fluff array structure of the flexible airflow sensor provided in example 1.
Fig. 3 is a cross-sectional scanning electron microscope image of the carbon fiber fluff array structure of the flexible airflow sensor provided in example 1.
FIG. 4 is a plot of the areal density of the carbon fiber fluff array structure of the flexible airflow sensor provided in examples 1-3.
Fig. 5 is a graph of air flow test sensitivity for different flow rates for the flexible air flow sensor provided in examples 1-3.
Fig. 6 is a schematic diagram of the detection results of the response time and the recovery time of the flexible airflow sensor provided in example 1.
FIG. 7 is a stability test chart of 500 blowing cycles of the flexible airflow sensor provided in example 1 under the action of an airflow of 20L/min.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.
Example 1
In the present embodiment, a flexible airflow sensor as shown in fig. 1 is provided, which comprises a substrate 1, an interdigital electrode 2, an adhesive layer 3 and a carbon fiber fluff array structure 4 from bottom to top.
Wherein the substrate is a polyimide film; the carbon fiber fluff array structure is composed of polyacrylonitrile-based carbon fibers, the diameter of the carbon fibers is 8 microns, the average length of the carbon fibers is about 300 microns, and the carbon fibers can penetrate through the adhesive layer and contact with the interdigital electrodes; the adhesive layer had a thickness of 10 μm and a Young's modulus of 500kPa.
The adhesive layer is formed by curing an adhesive, and the preparation method of the adhesive comprises the following steps:
mixing the Dow Corning 184 silicon rubber component A and the Dow Corning 184 silicon rubber component B in a defoaming stirrer according to the mass ratio of 20.
The preparation method of the flexible airflow sensor comprises the following steps:
(1) Cutting the substrate into a proper size, repeatedly cleaning the surface of the substrate with acetone, fixing a metal mask plate of the interdigital electrode on the substrate with an adhesive tape, and depositing chromium in a thermal evaporation instrument to obtain the substrate deposited with the interdigital electrode;
(2) Coating an adhesive on the substrate obtained in the step (1) by using a film coater, and covering the substrate on the interdigital part of the interdigital electrode to obtain the substrate coated with the adhesive;
(3) Dispersing 1g of carbon fibers on a lower polar plate of a high-voltage electrostatic device by adopting a vibration dispersion method, fixing the substrate obtained in the step (2) on an upper polar plate of the high-voltage electrostatic device by using an adhesive tape, wherein the distance between the upper polar plate and the lower polar plate is 10cm, turning on a power switch of the high-voltage electrostatic device, setting the voltage to be 30kV, enabling the carbon fibers to fly to the substrate under the action of a high-voltage electrostatic field, turning off the power after 10s, taking out the substrate of the upper polar plate, placing the substrate in an oven at 80 ℃ for curing for 120min, and removing redundant carbon fibers on the surface by using a high-pressure air gun after the curing is finished to obtain the flexible airflow sensor.
The microscopic morphology of the carbon fiber fluff array structure of the flexible airflow sensor provided in this embodiment was characterized by using a scanning electron microscope, and the results are shown in fig. 2 and fig. 3. As can be clearly seen from the figure, the carbon fiber fuzz has the characteristic of quasi-verticality, and due to the inclination of the carbon fiber fuzz, the carbon fiber fuzz is mutually overlapped to form a conductive network structure. The carbon fiber fluff has a small diameter and a relatively large length-diameter ratio, and the root of the carbon fiber fluff is pricked on the soft adhesive layer and is easy to swing under the action of air flow, so that the contact resistance is changed.
Example 2
This example is different from example 1 only in that the average length of the carbon fiber is about 500 μm, and the other conditions are the same as example 1.
Example 3
This example is different from example 1 only in that the average length of the carbon fiber is about 100 μm, and the other conditions are the same as example 1.
Example 4
This example is different from example 1 only in that the diameter of the carbon fiber is 7 μm and the thickness of the adhesive layer is 5 μm, and the other conditions are the same as example 1.
Example 5
This example is different from example 1 only in that the diameter of the carbon fiber is 10 μm and the thickness of the adhesive layer is 20 μm, and the other conditions are the same as example 1.
Example 6
The difference between the present example and example 1 is only that the distance between the upper and lower plates in step (2) of the method for manufacturing a flexible airflow sensor is 5cm, the voltage is 10kV, and the other conditions are the same as those in example 1.
Example 7
The difference between this example and example 1 is only that the distance between the upper and lower plates in step (2) of the method for manufacturing a flexible airflow sensor is 15cm, the voltage is 15kV, and the other conditions are the same as those in example 1.
Comparative example 1
This comparative example is different from example 1 only in that the thickness of the adhesive layer was 30 μm, and the other conditions were the same as example 1.
Comparative example 2
This comparative example is different from example 1 only in that the carbon fiber was replaced with a nylon fiber, and the other conditions were the same as example 1.
The weights of the carbon fibers in the carbon fiber fluff array structures of the flexible airflow sensors of examples 1-3 were weighed using an analytical balance, and the weights per unit area were calculated to obtain the areal density of the carbon fiber fluff array structure, as shown in fig. 4. It can be seen from the figure that the area density of example 2 is the largest, the area density of example 1 is the second largest, and the area density of example 3 is the smallest, because as the length of the carbon fiber increases, the carbon fiber is more easily oriented in the electrostatic field, resulting in a more vertical array morphology when penetrating into the glue layer, resulting in more carbon fibers per unit area, resulting in a greater area density.
In order to measure the sensing performance of the airflow sensor of the present examples 1-3 on the airflow, the Keithley-DMM7510 semiconductor property analysis system was used to measure the sensing performance of the examples 1-3 at different airflow rates, the airflow rate of the applied gas was controlled by the gas rotameter, and the measured airflow rate ranged from 1L/min to 50L/min, and as a result, as shown in fig. 5, it can be seen that the sensitivity of the flexible airflow sensor of the examples 1-3 was increased and the detection range was wide as the airflow rate was increased, but the detection limit of the examples 1 and 2 was low (1L/min). And it can be seen that the sensing performance of example 1 is the best, and the sensing performance of example 2 is decreased linearly when the air flow rate exceeds 30L/min, because the area density of the carbon fiber in the carbon fiber fluff array structure of example 2 is too high, and the carbon fiber fluff array should be deformed greatly when the air flow rate exceeds 30L/min, but the area density of the carbon fiber array is too high, so that the carbon fiber array is blocked by other fibers in the deformation process, thereby hindering the deformation process. And the shorter carbon fiber fluff is less deformed by the air flow, and thus, example 3 provides a flexible air flow sensor having lower sensitivity than examples 1-2.
The response time and recovery time of the flexible airflow sensor provided in example 1 at an airflow rate of 30L/min are shown in fig. 6, and it can be seen that the flexible airflow sensor has a relatively fast response time (1.7 s) and recovery time (3.4 s).
Fig. 7 shows a stability test chart of the flexible airflow sensor provided in example 1, in which 500 blowing cycles are performed at an air flow rate of 20L/min, and it can be seen that the flexible airflow sensor provided in example 1 has excellent cycle stability.
The performance tests of the examples 4-7 are carried out by the same method as the example 1, and the flexible airflow sensors prepared in the examples 4-7 can be deformed under the action of weak airflow, and the sensors can quickly and accurately react to the airflow.
When comparative examples 1 to 2 were subjected to the performance test in the same manner as in example 1, the thickness of the adhesive layer in comparative example 1 was too thick, so that the carbon fiber fluff could not penetrate through the adhesive layer and contact the electrode when flying up to the adhesive layer, resulting in failure to form a conductive path, and there was no response of an electric signal to the action of the air flow. In comparative example 2, although the nylon fiber fluff can also form an array structure similar to the carbon fiber fluff and can also deform under the action of the air flow, since the nylon fiber itself is not conductive, the deformation signal of the nylon fiber itself cannot be converted into an electrical signal, and comparative example 2 cannot realize the sensing of the air flow signal.
Therefore, the flexible airflow sensor based on the carbon fiber fluff array structure and used for detecting the gas flow rate signal is developed, the airflow sensor is simple and quick to prepare, has the characteristics of high response speed, low detection limit, wide detection range, good stability and the like, is flexible as a whole, can be cut into any size, can be attached to substrates of different types, and is suitable for wearable equipment and electronic equipment.
The applicant states that the present invention is illustrated by the above embodiments of the flexible airflow sensor and the preparation method and application thereof, but the present invention is not limited to the above embodiments, that is, the present invention does not mean that the present invention must be implemented by the above embodiments. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.
Claims (33)
1. The flexible airflow sensor is characterized by sequentially comprising a substrate, an interdigital electrode, an adhesive layer and a carbon fiber fluff array structure from bottom to top;
carbon fibers in the carbon fiber fluff array structure penetrate through the adhesive layer and are in contact with the interdigital electrodes;
the carbon fiber piles in the carbon fiber pile array structure are in lap joint contact with one another to form a conductive network, and the adhesive layer is not conductive.
2. The flexible airflow sensor of claim 1 wherein the carbon fiber fluff array structure is comprised of carbon fibers.
3. The flexible airflow sensor of claim 2 wherein the carbon fibers comprise polyacrylonitrile-based carbon fibers or pitch-based carbon fibers.
4. The flexible airflow sensor of claim 2 wherein the carbon fibers have a diameter of 7-10 μm.
5. The flexible airflow sensor of claim 2 wherein the carbon fibers have a length of 100-500 μm.
6. The flexible airflow sensor of claim 1 wherein the substrate is a flexible polymer film.
7. The flexible airflow sensor of claim 6 wherein the flexible polymer film comprises a polyimide film or a polyethylene terephthalate film.
8. The flexible airflow sensor of claim 7 wherein the flexible polymer film is a polyimide film.
9. A flexible airflow sensor according to claim 1 wherein the adhesive layer has a thickness of 5-20 μm.
10. A flexible airflow sensor according to claim 1 wherein the young's modulus of the adhesive layer is 500-1500kPa.
11. A flexible airflow sensor according to claim 1 wherein the adhesive layer is cured from an adhesive prepared by a method comprising the steps of:
mixing a flexible polymer and a curing agent to obtain the adhesive.
12. The flexible airflow sensor of claim 11 wherein said flexible polymer comprises Dow Corning 184 Silicone rubber A composition.
13. The flexible airflow sensor of claim 11 wherein the curing agent comprises Dow Corning 184 silicone rubber B-component.
14. The flexible airflow sensor of claim 11 wherein the mass ratio of the flexible polymer to the curing agent is (10-20): 1.
15. The flexible airflow sensor of claim 11 wherein the mixing is performed in a debubbling blender.
16. The flexible airflow sensor of claim 11 further comprising the step of vacuum debubbling after said mixing.
17. A method of manufacturing a flexible airflow sensor according to any of claims 1-16, wherein the method of manufacturing includes the steps of:
(1) Fixing a metal mask plate of the interdigital electrode on the substrate, and depositing a metal target in a thermal evaporation instrument to obtain the substrate deposited with the interdigital electrode;
(2) Coating an adhesive on the substrate obtained in the step (1) to cover the interdigital part of the interdigital electrode, so as to obtain the substrate coated with the adhesive layer;
(3) And (3) attaching carbon fibers to the adhesive layer of the substrate obtained in the step (2) to obtain a substrate attached with a carbon fiber fluff array structure, and performing post-treatment to obtain the flexible airflow sensor.
18. The method according to claim 17, wherein the step (1) of cleaning the substrate is further performed before the step of fixing the metal mask plate of the interdigital electrode on the substrate.
19. The method of claim 17, wherein the fixing in step (1) comprises fixing with an adhesive tape.
20. The method according to claim 17, wherein the metal target in step (1) comprises chromium or gold.
21. The method according to claim 17, wherein the coating of step (2) comprises a film coater coating or a wire bar coating.
22. The preparation method according to claim 17, wherein the step (3) of attaching the carbon fibers to the adhesive layer of the substrate obtained in the step (2) specifically comprises the following steps:
dispersing carbon fibers on a lower polar plate of a high-voltage electrostatic device, fixing the substrate obtained in the step (2) on an upper polar plate of the high-voltage electrostatic device, turning on a power switch of the high-voltage electrostatic device, and enabling the carbon fibers to fly to the substrate under the action of a high-voltage electrostatic field to obtain the substrate attached with a carbon fiber fluff array structure.
23. The method of claim 22, wherein the dispersing comprises vibration dispersing.
24. The method of claim 22, wherein the securing comprises securing with tape.
25. The method of claim 22, wherein the high voltage electrostatic device has a voltage of 10-30kV and a power-on time of 10-20s.
26. The method of claim 22, wherein the upper plate and the lower plate are spaced apart by 5-15cm.
27. The method according to claim 22, wherein the high-voltage electrostatic device has an electric field strength of 1 to 3kV/cm.
28. The method of claim 17, wherein the post-treatment of step (3) comprises curing.
29. The method of claim 28, wherein the curing is performed in an oven.
30. The method of claim 28, wherein the curing temperature is 70-90 ℃.
31. The method of claim 28, wherein the curing time is 100-130min.
32. The method of claim 28, further comprising removing excess carbon fibers from the surface of the carbon fiber fluff array structure after the curing using a high pressure air gun or a vacuum.
33. Use of a flexible gas flow sensor according to any of claims 1-16 for gas flow rate detection.
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