WO2023093471A1

WO2023093471A1 - Fluid detection apparatus, microphone, and electronic device

Info

Publication number: WO2023093471A1
Application number: PCT/CN2022/129048
Authority: WO
Inventors: 于媛媛; 李英明; 朱梦尧; 陈家熠; 卢明辉; 许相园
Original assignee: 华为技术有限公司; 南京大学
Priority date: 2021-11-24
Filing date: 2022-11-01
Publication date: 2023-06-01
Also published as: CN116165396A

Abstract

A fluid detection apparatus (1), comprising a substrate (17), a first electrode pair, a second electrode pair, and a heating unit (12) and a sensitive unit (11) arranged in parallel in a spaced mode. The heating unit (12) is electrically connected to a positive electrode (141) and a negative electrode (142) of the first electrode pair, the sensitive unit (11) is electrically connected to a positive electrode (151) and a negative electrode (152) of the second electrode pair, and the sensitive unit (11) is used for sensing the temperature of the environment where the sensitive unit is located; the sensitive unit (11) comprises a plurality of sensitive wires (111), and the plurality of sensitive wires (111) are distributed in parallel along a direction perpendicular to the length direction of the sensitive wires (111); the plurality of sensitive wires (111) are connected in series or in parallel to the positive electrode (151) and the negative electrode (152) of the second electrode pair. The signal-to-noise ratio of the fluid detection apparatus (1) can be increased without changing the size of the sensitive wires (111) or increasing the working temperature. Also provided are a microphone (2) and an electronic device.

Description

Fluid detection device, microphone and electronic equipment

This application claims the priority of a Chinese patent application with application number CN202111405550.8 and application title "Fluid Detection Device, Microphone and Electronic Equipment" filed with the China Patent Office on November 24, 2021, the entire contents of which are incorporated herein by reference In this application.

technical field

The present application relates to the field of acoustic sensors, in particular to a fluid detection device, a microphone and electronic equipment.

Background technique

As a fluid detection device, the thermal acoustic vector sensor can directly measure the vibration velocity of particles in the medium sound field by using temperature changes. It is generally composed of three thermal resistance wires arranged in parallel with a certain distance, and the middle thermal resistance wire is used as a heating wire, which is symmetrical. The thermal resistance wires on both sides are used as sensitive wires, because of their simple structure, frequency-independent figure-of-eight directivity (only pick up the sound in the front and rear directions, not the side sound), high low frequency response, easy integration and miniaturization. It has become one of the important directions of intelligent terminal sound pickup technology.

The thermal stress of the device (such as thermal resistance wire) of the thermal acoustic vector sensor at high temperature will cause a large thermal deformation of the device, and even cause the device to bend and break, thereby greatly reducing the reliability of the device.

In the prior art, in order to ensure the reliability of the device, a device with a large thickness/length ratio (such as a thermal resistance wire) is generally used, but a device with a large thickness/length ratio will cause the sensitivity of the thermal acoustic vector sensor to decrease, and then resulting in poor signal-to-noise ratio.

It can be seen that there is a problem of poor signal-to-noise ratio of fluid detection devices (such as thermal acoustic vector sensors) in the prior art.

Contents of the invention

The purpose of this application is to solve the problem of poor signal-to-noise ratio of fluid detection devices in the prior art. Therefore, the embodiment of the present application provides a fluid detection device, a microphone, and an electronic device. By connecting a plurality of sensitive wires distributed in parallel in series or in parallel to the positive electrode and the negative electrode of the electrode pair, the size (such as the length) of the sensitive wire is not changed. , width, thickness, etc.) so that the fluid detection device can satisfy the reliability of the device to a certain extent, and at the same time improve the signal-to-noise ratio of the fluid detection device.

An embodiment of the present application provides a fluid detection device, including a substrate, a first electrode pair, a second electrode pair, and a heating unit and a sensitive unit arranged side by side at intervals, and the first electrode pair and the second electrode pair are both fixed on the substrate; The heating unit is electrically connected to the positive electrode and the negative electrode of the first electrode pair, the sensitive unit is electrically connected to the positive electrode and the negative electrode of the second electrode pair, and the sensitive unit is used to sense the ambient temperature; the sensitive unit includes a plurality of sensitive A plurality of sensitive wires are distributed side by side along the length direction perpendicular to the sensitive wires; the plurality of sensitive wires are connected in series or in parallel to the positive electrode and the negative electrode of the second electrode pair.

In this embodiment, by adopting a sensitive unit composed of multiple sensitive wires in series, it is helpful to increase the input voltage of the sensitive unit through the series structure of multiple sensitive wires, thereby increasing the output voltage value of the sensitive unit in the circuit several times, As a result, the voltage difference between the sensitive units is increased several times. Since the voltage difference is related to the sensitivity of the fluid detection device, it can be achieved without changing the size of the sensitive wire (such as length, width, thickness, etc.) Under the premise of temperature, improving the sensitivity and signal-to-noise ratio of the fluid detection device not only ensures that the reliability of the device is not affected, but also improves the performance (including sensitivity and signal-to-noise ratio). The sensitive unit can effectively reduce the noise floor (or thermal noise) of the fluid detection device, thereby improving the signal-to-noise ratio of the fluid detection device. Furthermore, in the present application, by arranging a plurality of sensitive wires in parallel, compared with the scheme of serial arrangement, the size of the fluid detection device along the length direction of the sensitive wires can be greatly reduced, which contributes to the miniaturization of the fluid detection device.

In some embodiments, the ends of each of the plurality of sensitive wires connected in series that are not connected to the second electrode pair are respectively fixed to the base.

In some embodiments, the substrate is provided with a channel for fluid flow, and when the fluid flows in the channel, the fluid flows through the sensitive unit.

Fixing the end of each sensitive wire not connected to the second electrode pair among the multiple sensitive wires connected in series can strengthen the stability of the sensitive wire and improve the reliability of the sensitive unit.

In some embodiments, the heating unit includes a plurality of heating wires, and the plurality of heating wires are arranged in parallel along the length direction perpendicular to the heating wires; the plurality of heating wires are connected in series or in parallel to the positive electrode and the negative electrode of the first electrode pair.

In this embodiment, by setting up multiple heating wires and arranging multiple heating wires in parallel, on the one hand, compared with the fluid detection device with a single heating wire, under the condition of satisfying the same working temperature, multiple heating wires arranged in parallel The heating wire can reduce the temperature of each heating wire to a certain extent, thereby helping to avoid the self-melting phenomenon of the heating wire at high temperature. On the other hand, compared with the fluid detection device with a single heating wire, due to the application The temperature of each heating wire in the example is lower, so the embodiment of the present application can effectively improve the working sensitivity of the fluid detection device under the unit power consumption. Further, the embodiment of the present application can ensure that the heating wire can work normally (or can It is understood that in order to ensure the reliability of the fluid detection device), the maximum operating temperature of the fluid detection device is increased, thereby helping to improve the sensitivity and signal-to-noise ratio of the fluid detection device.

In some embodiments, the end of each heating wire not connected to the first electrode pair among the plurality of heating wires connected in series is respectively fixed to the base.

Fixing the end of each heating wire not connected to the first electrode pair among the plurality of heating wires connected in series can strengthen the stability of the heating wire and improve the reliability of the heating unit.

In some embodiments, the heating unit is reused as another sensitive unit, and the heating wire in the heating unit that is reused as another sensitive unit doubles as a sensitive wire, and the structure of the heating unit and the structure of the sensitive unit are reused as another sensitive unit. same.

In this embodiment, by reusing the heating unit as a sensitive unit, the structure of the fluid detection device can be simplified, the production cost can be saved, and the miniaturization of the fluid detection device can also be realized.

In some embodiments, the fluid detection device further includes another sensitive unit and a third electrode pair, the third electrode pair is fixed on the substrate, another sensitive unit is electrically connected to the positive electrode and the negative electrode of the third electrode pair, the heating unit, The sensitive unit is arranged side by side with another sensitive unit at intervals, and the structure of the other sensitive unit is the same as that of the sensitive unit.

In some embodiments, at least part of the wire segments of the sensitive wire are in a zigzag or wavy shape, and/or: when the heating unit includes multiple heating wires, at least a part of the wire segments of the heating wire are in a zigzag or wavy shape.

In some embodiments, some wire segments of the heating wire are zigzag or wavy, and other wire segments of the heating wire are straight; some wire segments of the sensitive wire are zigzag or wavy, and the other wire segments of the sensitive wire are In a straight line.

In this embodiment, by designing at least part of the sensitive wire and/or the heating wire in a serrated or wavy shape, since the serrated or wavy heating wire/sensitive wire has a high thermal deformation capacity at high temperature , so that more thermal stress can be released, so that the heating wire and/or sensitive wire are not easy to bend and break, which can effectively improve the reliability of the fluid detection device. Further, in some solutions, the sensitive wire/heating wire adopts a zigzag shape Or wavy, and linear composite structure, on the one hand, can reduce the maximum thermal stress of the sensitive wire/heating wire through the jagged or wavy wire segment, thereby improving the reliability of the fluid detection device, on the other hand, it can also pass The linear wire segment avoids excessive thermal deformation of the heating wire/sensitive wire, thereby ensuring that the sensitivity of the fluid detection device is not affected.

In some embodiments, the fluid detection device further includes a first bracket; the first bracket is supported between the serrated or wavy wire segments of two adjacent sensitive wires;

When the heating unit includes a plurality of heating wires, the fluid detection device further includes a second bracket, and the second bracket is supported between the zigzag or wavy segments of two adjacent heating wires.

In this embodiment, by arranging the first bracket between the adjacent two sensitive wires and the second bracket between the adjacent two heating wires, the heating between the adjacent two sensitive wires and the adjacent two heating wires can be improved. The stability between the wires makes the heating wire and/or the sensitive wire difficult to bend and break, thereby effectively improving the reliability of the fluid detection device.

In some embodiments, the first support includes a plurality of first support segments, the plurality of first support segments are distributed along the length direction of the sensitive wire, and each first support segment is supported on the corresponding two adjacent sensitive wires. Between some wire segments;

The second support includes a plurality of second support segments distributed along the length direction of the heating wire, and each second support segment is supported between corresponding two adjacent partial wire segments of the heating wire.

In some embodiments, the sensitive wires have a grid-like structure, or multiple sensitive wires form a grid-like structure; and/or:

When the heating unit includes multiple heating wires, the heating wires are in a grid structure, or the multiple heating wires form a grid structure.

In this embodiment, since the grid-shaped sensitive wire/heating wire has greater thermal deformation capacity, more thermal stress can be released at a higher working temperature, and it is not easy to break, thereby improving the sensitivity of the sensitive wire/heating wire. The reliability of the wire, further, because the sensitive wire/heating wire of the embodiment of the present application can be applied to a higher working temperature, thus helping to improve the sensitivity of the fluid detection device, further, because the grid of this embodiment The shaped structure design increases the contact area between the sensitive wire/heating wire and the air under the same cross-sectional area, which is beneficial to the heat exchange between the sensitive unit/heating unit, thus helping to improve the signal-to-noise ratio of the fluid detection device.

In some embodiments, along the direction perpendicular to the length of the sensitive wires, a first beam structure is connected between multiple sensitive wires; and/or: when the heating unit includes multiple heating wires, along the direction perpendicular to the length of the heating wires , a second beam structure is connected between the plurality of heating wires.

In some embodiments, a third beam structure is connected between the sensitive unit and the heating unit along the length direction perpendicular to the sensitive wire;

In some possible embodiments, along the direction perpendicular to the length of the sensitive wires, a beam structure is connected between some of the multiple sensitive wires; when the heating unit includes multiple heating wires, along the length perpendicular to the heating wires direction, and a beam structure is connected between some of the multiple heating wires.

In this embodiment, the stability between the sensitive wires, between the heating wires, and between the heating wires and the sensitive wires can be improved by setting a beam structure between the sensitive wires, between the heating wires, and between the sensitive unit and the heating unit. , so that the heating wire and/or the sensitive wire are not easy to bend or break, thereby effectively improving the reliability of the fluid detection device.

In some embodiments, the distance between two adjacent sensitive wires in the sensitive unit is greater than or equal to 1 μm and less than or equal to 10 μm; and/or:

When the heating unit includes multiple heating wires, the distance between two adjacent heating wires is greater than or equal to 1 μm and less than or equal to 10 μm.

An embodiment of the present application provides a microphone, including the fluid detection device provided in any one of the above embodiments or any possible embodiment.

In some possible embodiments, the microphone further includes a power supply module, a noise filtering module and a signal processing module, the power supply end of the fluid detection device is electrically connected to the power supply module, and the signal output end of the fluid detection device is electrically connected to the input end of the noise filtering module , to obtain the processed electrical signal through the noise filtering module, the output end of the noise filtering module is electrically connected to the input end of the signal processing module, so that the processed electrical signal is amplified by the signal processing module and then output.

An embodiment of the present application provides an electronic device, including the microphone provided in any one of the foregoing embodiments or any possible embodiment.

Description of drawings

Figure 1a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, in which multiple sensitive wires are connected in series;

Figure 1b is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, in which multiple sensitive wires are connected in parallel;

Figure 1c is a schematic diagram of a three-dimensional structure of a fluid detection device according to an embodiment of the present application, in which multiple sensitive wires are connected in parallel;

Fig. 2a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein a plurality of sensitive wires are connected in series and a plurality of heating wires are connected in series;

Fig. 2b is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein multiple sensitive wires are connected in parallel and multiple heating wires are connected in parallel;

Fig. 2c is a schematic diagram of a three-dimensional structure of a fluid detection device according to an embodiment of the present application, wherein a plurality of sensitive wires are connected in parallel and a plurality of heating wires are connected in parallel;

Figure 3a is a schematic structural diagram of the heating wire of the fluid detection device of the embodiment of the present application also serving as a sensitive wire, wherein multiple heating wires are connected in series and multiple sensitive wires are connected in series;

Fig. 3b is a schematic structural diagram of the fluid detection device of the embodiment of the present application when the heating wire also serves as a sensitive wire, wherein multiple heating wires are connected in parallel and multiple sensitive wires are connected in parallel;

Fig. 3c is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein there are four sensitive units and one heating unit;

Fig. 3d is a schematic diagram of a three-dimensional structure of a fluid detection device according to an embodiment of the present application, wherein there are four sensitive units and one heating unit;

Fig. 4 is the frequency response curve when the sensitive unit of the fluid detection device of the embodiment of the present application adopts different numbers of sensitive wires;

Fig. 5 is a schematic structural diagram of the fluid detection device of the embodiment of the present application, in which the sensitive wire and the heating wire are both zigzag;

Fig. 6 is a structural schematic diagram of the fluid detection device of the embodiment of the present application, wherein, some wire segments of the sensitive wire are zigzag, and other wire segments are straight; some wire segments of the heating wire are zigzag, and other wire segments are straight shape;

Fig. 7 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein both the sensitive wire and the heating wire are wavy;

Fig. 8 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein a first beam structure is connected between a plurality of sensitive wires of the sensitive unit;

9 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein a first beam structure is connected between multiple sensitive wires, a second beam structure is connected between multiple heating wires, and a heating unit and a sensitive unit are connected. connected with a third beam structure;

Fig. 10 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein both the sensitive wire and the heating wire have a grid-like structure;

Fig. 11 is a schematic diagram of a grid-like structure in a fluid detection device according to an embodiment of the present application;

Fig. 12a is a schematic diagram of the system structure of the microphone of the embodiment of the present application;

Figure 12b is a schematic diagram of the circuit principle of the microphone of the embodiment of the present application;

Fig. 13a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein the number of sensitive wires is 3 and the 3 sensitive wires are connected in parallel, the number of heating wires is 3 and the 3 heating wires are connected in parallel;

Fig. 13b is a schematic diagram of an equivalent circuit of the microphone of the embodiment of the present application, in which multiple sensitive wires are connected in parallel;

Fig. 14a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein the number of sensitive wires is 3 and 3 sensitive wires are connected in series, and the number of heating wires is 3 and 3 heating wires are connected in series;

Fig. 14b is a schematic diagram of an equivalent circuit of the microphone of the embodiment of the present application, in which a plurality of sensitive wires are connected in series;

Fig. 15 is a schematic diagram of an equivalent circuit of a microphone according to an embodiment of the present application, wherein the number of sensitive units is 4, and the number of heating units is 1.

Explanation of reference signs:

1: Fluid detection device;

101: first beam structure; 102: beam structure; 11: sensitive unit; 111: sensitive wire; 11A: sensitive unit; 111A: sensitive wire; 112: first bracket; 1121: first bracket segment; 12: heating unit; 121: heating wire; 122: second bracket; 1221: second bracket section; 13: sensitive unit; 131: sensitive wire; 13A: sensitive unit; 131A: sensitive wire; 141: positive electrode; 142: negative electrode; 151: Positive electrode; 152: negative electrode; 153 positive electrode; 154: negative electrode; 161: positive electrode; 162: negative electrode; 163: positive electrode: 164: negative electrode; 17: substrate; 171: first substrate part; 172: The second base part; 173: the third base part;

2: Microphone;

21: noise filtering module; 22: signal processing module; 23: power supply module;

R0, R1, R2, R3, R4, R5, R6, R 11 , R _11A , R ₁₃ _, R _13A : resistance; C: capacitance; A: amplifier; V+: power supply terminal; Vout: output terminal;

L: Length direction.

Detailed ways

The implementation of the present application will be illustrated by specific specific examples below, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Although the description of the present application will be presented in conjunction with some embodiments, this does not mean that the features of the application are limited to the embodiments. On the contrary, the purpose of introducing the application in conjunction with the embodiments is to cover other options or modifications that may be extended based on the claims of the present application. The following description contains numerous specific details in order to provide an in-depth understanding of the present application. The application may also be practiced without these details. Furthermore, some specific details will be omitted from the description in order to avoid obscuring or obscuring the focus of the application. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

It should be noted that in this specification, similar numerals and letters denote similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be identified in subsequent drawings. for further definition and explanation.

In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplification of the description, rather than indicating or implying that the referred device or element must have a specific orientation, use a specific orientation construction and operation, therefore should not be construed as limiting the application. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

In the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

In the description of this application, it should be understood that "electrical connection" in this application can be understood as the physical contact and electrical conduction of components; it can also be understood as the connection between different components in the circuit structure through printed circuit boards , PCB) copper foil or wires and other physical lines that can transmit electrical signals for connection. "Communication connection" may refer to electrical signal transmission, including wireless communication connection and wired communication connection. A wireless communication connection does not require a physical medium and does not belong to a connection relationship that defines a product configuration.

In order to make the purpose, technical solution and advantages of the present application clearer, the implementation manner of the present application will be further described in detail below in conjunction with the accompanying drawings.

Please refer to Figures 1a to 1c, Figure 1a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein multiple sensitive wires are connected in series; Figure 1b is a schematic structural diagram of a fluid detection device according to an embodiment of this application, wherein multiple sensitive wires Parallel connection, Fig. 1c is a schematic diagram of the three-dimensional structure of the fluid detection device according to the embodiment of the present application, wherein a plurality of sensitive wires are connected in parallel.

As shown in Figures 1a to 1c, the embodiment of the present application provides a fluid detection device 1, including a substrate 17, a first electrode pair, a second electrode pair, and a heating unit 12 and a sensitive unit 11 arranged in parallel and spaced apart. The first electrode pair (comprising the positive electrode 141 and the negative electrode 142) and the second electrode pair (comprising the positive electrode 151 and the negative electrode 152) are fixed on the base 17 (including the first base part 171 and the second base mentioned later). Section 172). Among them, if the power supply is direct current, the positive electrode can be understood as the electrode connected to the positive pole of the power supply, and the negative electrode can be understood as the electrode connected to the negative pole of the power supply; if the power supply is alternating current, the positive electrode can be understood as the electrode of the live wire, and the negative electrode can be understood as The electrode connected to the neutral wire.

In some embodiments, the first pair of electrodes and the second pair of electrodes may be indirectly fixed to the substrate 17 through an electrode insulating layer fixed to the substrate 17 (including the first substrate part 171 and the second substrate part 172). In other embodiments , can also be fixed on the base 17 by other means. Wherein, the material of the electrode insulating layer is not limited. In one example, the electrode insulating layer can be silicon dioxide (SiO ₂ ), and in other examples, it can also be silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN ), alumina (Al ₂ O ₃ ) and so on.

As shown in Figures 1a to 1c, the substrate 17 is provided with a channel for fluid flow, and when the fluid flows in the channel, the fluid flows through the sensitive unit (such as the sensitive unit 11 and the sensitive unit 13 mentioned later), in other embodiments , when the fluid flows in the channel, the fluid can also flow through the sensitive unit (such as the sensitive unit 11 and the sensitive unit 13 mentioned later) and the heating unit 12. In one embodiment, the base 17 can include the first A base portion 171 and a second base portion 172, and the first base portion 171 and the second base portion 172 may be independent of each other, the space formed by the first base portion 171 and the second base portion 172 being spaced apart constitutes a supply fluid The flow channel, the sensing unit 11 and the heating unit 12 are all bridged between the first base portion 171 and the second base portion 172 of the base 17 . In other embodiments, the base may also be two parts formed on the same member. For example, in some embodiments, the base 17 is provided with a groove (not shown in the figure), and the sensitive unit 11 and the heating unit 12 are both connected to each other. On the two side walls in the groove, one of the two side walls in the groove can be understood as the first base part, and the other side wall in the two side walls in the groove can be understood as the first base part. Two base parts, the space in the groove constitutes the channel for fluid flow. In other embodiments, the substrate 17 can also be of other structures, as long as the electrode pairs (such as the first electrode pair and the second electrode pair) can be fixed and the sensitive unit 11 and the heating unit 12 can be electrically connected to the corresponding electrode pairs, it will not deviate from the present invention. scope of examples. In addition, the material of the substrate 17 is not limited, for example, it may be a silicon substrate, and in other embodiments, it may also be made of other materials, which is not limited in this application.

The heating unit 12 is electrically connected to the positive electrode 141 and the negative electrode 142 of the first electrode pair, and the sensitive unit 11 is electrically connected to the positive electrode 151 and the negative electrode 152 of the second electrode pair. Specifically, the heating unit 12 includes at least one heating wire 121, one end of the heating wire 121 is connected to the positive electrode 141 of the first electrode pair, and the other end is connected to the negative electrode 142 of the first electrode pair. Finally, heat is generated to meet the working temperature of the fluid detection device. In this embodiment, the number of the heating wire 121 is one, and in other embodiments, the number of the heating wire 121 may also be multiple.

In one embodiment, the heating wire 121 includes a heating wire metal layer, and the heating wire metal layer is electrically connected to the positive electrode 141 and the negative electrode 142 of the first electrode pair for generating heat after being energized. The material of the metal layer of the heating wire is not limited. It can be a material with high thermal conductivity, such as metal wire, highly doped silicon, etc., or a metal composite laminate, such as a composite laminate of platinum, cadmium, and silicon nitride. In other embodiments, other materials may also be used. In one embodiment, the heating wire 121 also includes a heating wire insulation layer, the heating wire insulation layer is used to support the heating wire metal layer and fix the heating wire to the base (such as the first base part 171 or the second base part 172), heating The material of the silk insulating layer is not limited, for example, it can be silicon dioxide (SiO ₂ ), in other examples, it can also be silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ )etc.

The sensitive unit 11 is used to sense the temperature of its environment. The sensitive unit 11 can change its own temperature and output a corresponding electrical signal when the fluid flows through. The electrical signal changes with the temperature of the sensitive unit 11 itself. The sensitive unit 11 includes a plurality of sensitive wires 111, which are arranged side by side along the length direction L perpendicular to the sensitive wires. The "perpendicular" mentioned in this application includes approximately vertical, that is, it may deviate from a certain angle perpendicular to the length direction L of the sensitive wire, such as 0.1°, 0.5°, 1° and so on. A plurality of sensitive wires 111 are connected in series or in parallel to the positive electrode 151 and the negative electrode 152 of the second electrode pair. The number of sensitive wires is not limited. In one embodiment, the number of sensitive wires is 5, and in other embodiments, other numbers may also be used. The spacing between any two adjacent sensitive wires among the plurality of sensitive wires 111 can be the same or different. The sensitive wire 111 is used to sense particle vibration velocity, and generally adopts a high thermal resistivity material, such as a thermal resistance wire. According to the thermal resistance effect, the thermal resistance wire has the characteristic of changing its resistance value with its own temperature, so it can respond to the fluid flow in the environment, produce temperature changes, and output electrical signals corresponding to the resistance value by changing its own resistance value, such as voltage change value wait. In other examples, the sensitive wire 111 may also be other devices, as long as the device can change its own temperature and output a corresponding electrical signal when the fluid flows through, it will not depart from the scope of this embodiment. Further, the shapes of the sensitive wire 111 and the heating wire 121 may be straight, or other shapes, such as zigzag, wave, spring, etc., or a composite shape of straight and other shapes.

In one embodiment, the sensitive wire 111 includes a sensitive wire metal layer electrically connected to the positive electrode 151 and the negative electrode 152 of the second electrode pair for sensing temperature changes. The material of the metal layer of the sensitive wire is not limited, it can be a material with high thermal resistivity, for example, it can be a composite laminate of platinum, cadmium, and silicon nitride, and in other embodiments, it can also be made of other materials. In one embodiment, the sensitive wire 111 also includes a sensitive wire insulating layer, which is used to support the metal layer of the sensitive wire and fix the sensitive wire to the base (such as the first base part 171 or the second base part 172), and the sensitive wire The material of the silk insulating layer is not limited, for example, it can be silicon dioxide (SiO ₂ ), in other examples, it can also be silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ )etc.

Further, the size of the heating wire and the sensitive wire is not limited, as long as the above functional requirements can be met, it will not deviate from the scope of this embodiment. In an exemplary embodiment, the thickness of the sensitive wire and the heating wire is generally 0.3 μm, where , the metal layer is 0.1 μm, the insulating layer is 0.2 μm, the length of each sensitive wire 111 of the sensitive unit 11 and each heating wire 121 of the heating unit 12 is 0.5mm-2mm, generally 1mm, and the width is 0.5-2mm. 2 μm.

In addition, the distance between the sensitive unit 11 and the heating unit 12 is generally less than 500 μm.

Further, the distance between two adjacent sensitive wires 111 in the fluid detection device sensitive unit 11 of the embodiment of the present application is greater than or equal to 1 μm and less than or equal to 10 μm, such as 1 μm, 2 μm, 5 μm, 10 μm, etc. The distance between the heating wires 121 is less than or equal to 10 μm. Since the distance is small, when the fluid is disturbed, all the heating wires and all the sensitive wires work simultaneously. However, the spacing should not be too small. If the spacing is too small, it is not easy to process, and adjacent heating wires or adjacent sensitive wires will be bonded together. The distance should not be too large. If the distance is too large, the frequency response characteristics of adjacent sensitive wires or adjacent heating wires will be inconsistent, and then all heating wires and all sensitive wires cannot work at the same time.

Those skilled in the art can understand that there are at least two sensitive units. In some embodiments, the two sensitive units can be two sensitive units that work independently. In other embodiments, one of the two sensitive units is an independent The working sensitive unit, and the other uses a heating unit to reuse as a sensitive unit. For the specific structure, please refer to the following text for understanding.

As shown in Figures 1a and 1b, the fluid detection device 1 also includes a third electrode pair (including a positive electrode 161 and a negative electrode 162) fixed on the substrate 17, wherein the positive electrode 161 of the third electrode pair is fixed on the first substrate In part 171 , the negative electrode 162 of the third electrode pair is fixed on the second base part 172 , and the structure and fixing method of the third electrode pair are similar to those of the first electrode pair and the second electrode pair described above, and will not be repeated here. The number of sensitive units is 2, which are respectively sensitive unit 11 and sensitive unit 13, and the sensitive unit 11 and the sensitive unit 13 are distributed on both sides of the heating unit 12, the distance between the sensitive unit 11 and the heating unit 12 and the sensitive unit 13 The distance from the heating unit 12 may be the same or different. In other alternative embodiments, the sensitive unit 11 and the sensitive unit 13 can also be located on the same side of the heating unit 12, the sensitive unit 11 is electrically connected to the positive electrode 151 of the second electrode pair and the negative electrode 152 of the second electrode pair, and the sensitive The unit 13 is electrically connected to the positive electrode 161 of the third electrode pair and the negative electrode 162 of the third electrode pair. The sensitive unit 11 has a plurality of sensitive wires 111, and the sensitive unit 13 has a plurality of sensitive wires 131. In one embodiment, The number of sensitive wires in both the sensitive unit 11 and the sensitive unit 13 is 5, and in other embodiments, it may be other numbers, such as 3, 7 and so on.

It should be noted that the structure and the number of sensitive wires in the sensitive unit 11 and the sensitive unit 13 are the same, thereby ensuring that the resistance variation of the two sensitive units is the same and only related to the vibration velocity of the acoustic particle. Among them, the same structure can be specifically understood as: if the multiple sensitive wires 111 in the sensitive unit 11 adopt the series structure described above, the multiple sensitive wires 131 in the sensitive unit 13 also adopt the same series structure, and the multiple sensitive wires The number of 131 is the same as the number of multiple sensitive wires 111. If the multiple sensitive wires 111 in the sensitive unit 11 adopt the aforementioned parallel structure, the multiple sensitive wires 131 in the sensitive unit 13 also adopt the same parallel structure. The number of sensitive wires 131 is the same as the number of multiple sensitive wires 111 .

It should be understood that the thermal stress refers to the internal stress of the structure caused by the temperature change, and the thermal deformation refers to the expansion or contraction deformation of the structure due to the temperature change.

The signal-to-noise ratio refers to the ratio of signal to noise in an electronic device or electronic system, and the unit is dB. The signal-to-noise ratio can also be expressed by the ratio of the power of the output signal to the noise power output at the same time. The higher the signal-to-noise ratio of the device, the less noise it produces and the higher the sound quality.

Sensitivity can be understood as the ability to convert fluid disturbances into electrical signals. Taking thermal acoustic vector sensors as an example, sensitivity refers to the conversion of fluid disturbances disturbed by sound waves (or sound pressure) by thermal acoustic vector sensors. It is the capability of the electrical signal in dBV. The higher the sensitivity, the better the performance of the characterization sensor.

Self-melting phenomenon: The phenomenon that the material is broken due to the self-heating effect. Among them, the self-heating effect is the phenomenon that the internal temperature rises due to excessive operating current.

The fluid detection device provided by this application can be applied to various scenarios of detection of fluid velocity and flow rate, such as aerospace, biochemical detection, and medical equipment. In one embodiment, the fluid between sensitive units can be disturbed by incident sound waves Under vibration, when the fluid in the fluid detection device adopts gas, such as air, the particle (or can be called particle) in the air vibrates to transmit the sound wave, at this time the fluid detection device of the present application can be used as a thermal Acoustic vector sensor.

In an exemplary working process of the thermal acoustic vector sensor, the heating unit 12 provides the operating temperature of the thermal acoustic vector sensor. At the operating temperature, when the sound wave is incident on the thermal acoustic vector sensor, the fluid (such as Particles in air, water, castor oil, etc.) undergo reciprocating vibrations to form forced convective heat transfer, thereby transferring heat from one sensitive unit to another, causing the temperature between the sensitive units to change in opposite directions, as shown in Fig. In 1b, the sound wave S1 is incident from the direction indicated by the arrow, disturbing the fluid between the sensitive unit 11 and the sensitive unit 13 to cause convective heat transfer between the sensitive unit 11 and the sensitive unit 13, at this time, the temperature of the sensitive unit 11 decreases, and the sensitive The temperature of the unit 13 rises, that is, the temperature between the sensitive unit 11 and the sensitive unit 13 changes in the opposite direction, and then, the resistance values of each sensitive wire 111 in the sensitive unit 11 and each sensitive wire 131 of the sensitive unit 13 change with temperature. Changes, for example, the temperature of the sensitive unit 11 decreases, so that the resistance value of each sensitive wire 111 of the sensitive unit 11 decreases, and the temperature of the sensitive unit 13 increases, so that the resistance value of each sensitive wire 131 of the sensitive unit 13 increases. The change of the resistance value of each sensitive wire of each sensitive unit is converted into a voltage change output, realizing the process of converting the sound signal into an electrical signal.

In another exemplary working process, the sound wave S2 is incident from the direction shown by the arrow, and the fluid between the disturbing sensitive unit 11 and the sensitive unit 13 causes convection heat transfer between the sensitive unit 11 and the sensitive unit 13. At this time, the sensitive unit 13 the temperature of the sensitive unit 11 increases, that is, the temperature between the sensitive unit 11 and the sensitive unit 13 changes in the opposite direction, and then, each sensitive wire 111 in the sensitive unit 11 and each sensitive wire 131 of the sensitive unit 13 The resistance value changes with temperature, for example, the temperature of the sensitive unit 11 increases, so that the resistance value of each sensitive wire 111 of the sensitive unit 11 increases, and the temperature of the sensitive unit 13 decreases, so that the resistance value of each sensitive wire 131 of the sensitive unit 13 decreases Through the circuit, the change of the resistance of the two sensitive units is converted into a voltage change output, and the process of converting the sound signal into an electrical signal is realized.

Wherein, when the incident sound wave causes air disturbance, the temperature change of the sensitive wire 111 (such as a thermal resistance wire) is caused, and the temperature change value is ΔT, and ΔT can be calculated using the following formula:

Among them, f: the frequency of the sound wave;

v: particle vibration velocity;

P: the total power of the sensitive wire;

k: thermal conductivity of the fluid;

ly: sensitive thread length;

D: thermal diffusivity of the fluid;

a: the distance between the sensitive wire and the heating wire;

γ: Euler's constant, γ=0.577;

L: the width of the metal layer of the sensitive wire;

h: the thickness of the metal layer of the sensitive wire;

(ρCp)air: the product of air density and air specific heat capacity;

(ρCp)sensor: the product of the density of the sensitive wire and the specific heat capacity of the sensitive wire;

f _hc represents the -3dB frequency inflection point caused by parameters such as sensitive wire size and heat capacity;

f _D : -3dB frequency inflection point caused by parameters such as air thermal diffusivity.

The -3dB frequency inflection point can be understood as the frequency of the thermal acoustic vector sensor when the sensitivity is -3dB, and the thermal acoustic vector sensor can meet the normal use requirements when the sensitivity is within -3dB.

Further, the change of the resistance value of the sensitive unit 11 and the sensitive unit 13 causes the voltage difference between the sensitive unit 11 and the sensitive unit 13 to change, and the voltage difference Δu ₀ is proportional to the temperature change value ΔT, and the voltage difference Δu ₀ It can be used to characterize the sensitivity of the thermal acoustic vector sensor, and the voltage difference △u ₀ can be calculated by the following formula:

Among them, V: bias voltage;

v: particle vibration velocity;

α: thermal resistivity.

It can be understood that the larger the voltage difference △ _u0 , the higher the sensitivity and the better the performance of the thermal acoustic vector sensor. Since the signal-to-noise ratio can be expressed by the ratio of the power of the output signal to the noise power output at the same time, in Under the condition of constant noise, the larger the output voltage difference, the higher the signal-to-noise ratio of the thermal acoustic vector sensor.

The embodiment of the present application uses a sensitive unit composed of multiple sensitive wires in series, which helps to increase the input voltage of the sensitive unit through the series structure of multiple sensitive wires, thereby increasing the voltage difference between the sensitive units several times. Due to the voltage difference It is associated with the sensitivity of the fluid detection device (such as a thermal acoustic vector sensor), so the embodiments of the present application can increase the sensitivity without changing the size of the sensitive wire (such as length, width, thickness, etc.) The sensitivity and signal-to-noise ratio of the fluid detection device not only ensures that the reliability of the device is not affected, but also improves the performance (including sensitivity and signal-to-noise ratio). By using multiple sensitive wires in parallel to form a sensitive unit, it can effectively reduce the The noise floor (or can be understood as thermal noise) of a fluid detection device (such as a thermal acoustic vector sensor) improves the signal-to-noise ratio of the fluid detection device. Furthermore, in the present application, by arranging a plurality of sensitive wires in parallel, compared with the scheme of serial arrangement, the size of the fluid detection device along the length direction of the sensitive wires can be greatly reduced, which contributes to the miniaturization of the fluid detection device.

Further, please refer to FIG. 1a, the ends of each sensitive wire 111 not connected to the second electrode pair among the multiple sensitive wires 111 connected in series are respectively fixed on the base 17, or it can be understood as: each of the multiple sensitive wires 111 The sensitive wire segment connecting the sensitive wire 111 with the adjacent sensitive wire 111 overlaps the base 17 . It may be directly bonded to the base 17, or indirectly bonded to the base 17 through a bonding bracket. Specifically, along the direction from left to right in FIG. One end of the positive electrode 151 of the second electrode pair is connected to the second sensitive wire 111 and fixed on the second base part 172 of the base 17, and the last sensitive wire 111 in the multiple sensitive wires 111 connected in series is close to the second electrode One end of the negative electrode 152 of the pair is electrically connected to the negative electrode 152 of the second electrode pair, and one end of the negative electrode 152 away from the second electrode pair is connected to the previous sensitive wire 111 and fixed on the first base portion 171 of the base 17 .

In the embodiment of the present application, by fixing the end of each sensitive wire 111 not connected to the second electrode pair in the multiple sensitive wires 111 connected in series on the base (such as the first base part 171 or the second base part 172), it is possible to strengthen the The stability of the sensitive wire 111 improves the reliability of the sensitive unit 11 .

1b and 1c, among the multiple sensitive wires 111 connected in parallel, the two ends of each sensitive wire 111 are electrically connected to the corresponding electrodes, and meanwhile, the two ends of each sensitive wire 111 are also fixed to the base (such as the first base part 171 and second base part 172), which can be directly fixed on the base through the sensitive wire insulating layer, or indirectly fixed on the base 17 through the sensitive wire insulating layer and the aforementioned electrode insulating layer , in other embodiments, other fixing methods are also possible, as long as both ends of each sensitive wire among the multiple sensitive wires connected in parallel are fixed to the base 17, it does not depart from the scope of this embodiment.

Please refer to Figures 2a to 2c, Figure 2a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, wherein a plurality of sensitive wires 111 are connected in series and a plurality of heating wires 121 are connected in series, and Figure 2b is a structure of a fluid detection device according to an embodiment of the application Schematic diagram, wherein multiple sensitive wires 111 are connected in parallel and multiple heating wires 121 are connected in parallel.

Further, referring to FIG. 2a, the heating unit 12 includes a plurality of heating wires 121, and the plurality of heating wires 121 are arranged in parallel along the length direction L perpendicular to the heating wires; the plurality of heating wires 121 are connected in series or in parallel to the electrodes of the first electrode pair. positive electrode 141 and negative electrode 142 .

By arranging multiple heating wires 121 and arranging multiple heating wires 121 side by side, on the one hand, compared with a fluid detection device with a single heating wire, under the condition of satisfying the same working temperature, multiple heating wires 121 arranged side by side It can reduce the temperature of each heating wire to a certain extent, thereby helping to avoid the self-melting phenomenon of the heating wire at high temperature. On the other hand, compared with the fluid detection device with a single heating wire, it can meet the premise of the same working temperature Under the circumstances, since the temperature of each heating wire in the embodiment of the present application is lower, the embodiment of the present application can effectively improve the working sensitivity of the fluid detection device under the unit power consumption, or, on the premise of meeting certain sensitivity requirements, the implementation of the present application The power consumption of the thermal acoustic vector sensor heating unit of the example is smaller; further, the embodiment of the present application can ensure that the heating wire can work normally (or can be understood as the premise of ensuring the reliability of the fluid detection device), The maximum working temperature of the fluid detection device is increased, thereby helping to improve the sensitivity and signal-to-noise ratio of the fluid detection device.

Further, referring to FIG. 2a, the ends of each heating wire 121 not connected to the first pair of electrodes in the multiple heating wires 121 connected in series are respectively fixed to the base (the first base part 171 or the second base part 172), or can be It is understood that: each heating wire 121 of the plurality of heating wires 121 is connected to the heating wire segment adjacent to the heating wire 121 to overlap the base (the first base part 171 or the second base part 172 ). Specifically, along the direction from right to left in FIG. 2a, one end of the first heating wire close to the positive electrode 141 of the first electrode pair is electrically connected to the positive electrode 141 of the first electrode pair among the plurality of heating wires 121 connected in series, away from One end of the positive electrode 141 of the first electrode pair is connected to the second heating wire 121 and fixed on the second base part 172 of the base, and the last heating wire 121 in the plurality of heating wires 121 connected in series is close to the first electrode pair One end of the negative electrode 142 of the first electrode pair is electrically connected to the negative electrode 142 of the first electrode pair, and one end of the negative electrode 142 away from the first electrode pair is connected to the previous heating wire 121 and fixed on the first base part 171 of the base by connecting the series The end of each of the plurality of heating wires 121 that is not connected to the first electrode pair is fixed on the base, which can enhance the stability of the heating wire and improve the reliability of the heating unit.

Please refer to Figures 3a to 3b, Figure 3a is a schematic structural diagram of the heating wire of the fluid detection device of the embodiment of the present application as a sensitive wire, and Figure 3b is a schematic structural diagram of the heating wire of the fluid detection device of the embodiment of the present application when it is also used as a sensitive wire, Figure 3a The structure of the fluid detection device 1 shown in FIG. 1a is basically the same as that of FIG. 1a, and the structure of the fluid detection device described in FIG. 3b is basically the same as that of FIG. In addition to the sensitive unit 13 and the third electrode pair, the heating unit 12 includes a plurality of heating wires 121 and the heating unit 12 can be reused as another sensitive unit, and the heating wire 121 in the heating unit 12 can also be used as a sensitive wire of another sensitive unit.

It should be noted that when the heating unit 12 is not reused as another sensitive unit, the multiple heating wires in the heating unit 12 can adopt the same structure as the sensitive unit 11, or can adopt a different structure from the sensitive unit 11, for example , the number of the multiple heating wires in the heating unit 12 can be the same number as the multiple sensitive wires 111 in the sensitive unit 11, or different numbers, and the multiple heating wires in the heating unit 12 can be connected in series The positive electrode 141 and the negative electrode 142 of the first electrode pair may also be connected in parallel to the positive electrode 141 and the negative electrode 142 of the first electrode pair. When the heating unit 12 is reused as another sensitive unit, the heating unit 12 should adopt the same structure as the sensitive unit 11 , and the number of heating wires 121 should be the same as that of the sensitive wires 111 . Those skilled in the art can understand that, when the heating unit 12 is reused as another sensitive unit, the material of the heating wire can be selected to have both high thermal resistivity and high thermal conductivity. In the embodiment shown in Fig. 3 a, the quantity of the sensitive wire in the sensitive unit 11 is 5, and the 5 sensitive wires are connected in series with the positive electrode 151 and the negative electrode 152 of the second electrode pair, the heating unit 12 (multiplexed as another The number of heating wires in the sensitive unit) is 5, and the 5 heating wires 121 are connected in series to the positive electrode 141 and the negative electrode 142 of the first electrode pair. In the embodiment shown in Figure 3b, the number of sensitive wires in the sensitive unit 11 5, and 5 sensitive wires are connected in parallel to the positive electrode 151 and the negative electrode 152 of the second electrode pair, the number of heating wires in the heating unit 12 (multiplexed into another sensitive unit) is 5, and 5 heating wires 121 is connected in parallel to the positive electrode 141 and the negative electrode 142 of the first electrode pair.

Those skilled in the art can understand that the various embodiments of the present application can be combined, for example, when the heating unit 12 is not reused as another sensitive unit, and there are multiple heating wires in the heating unit 12, Regardless of the connection mode of the sensitive wires in the sensitive units (such as the sensitive unit 11 and the sensitive unit 13 ), the heating wires can be connected in series or in parallel.

By reusing the heating unit 12 as a sensitive unit, the structure of the fluid detection device 1 can be simplified, the production cost can be saved, and the miniaturization of the fluid detection device 1 can also be realized.

Further, please refer to Figure 3c and Figure 3d, Figure 3c is a schematic structural diagram of the fluid detection device of the embodiment of the present application, and Figure 3d is a schematic diagram of the three-dimensional structure of the fluid detection device of the embodiment of the present application; wherein, there are 4 sensitive units, and the heating unit The structure of the fluid detection device shown in Fig. 3c and Fig. 3d is basically the same as Fig. 1b, the difference is that:

The fluid detection device 1 also includes a fourth electrode pair (including a positive electrode 153 and a negative electrode 154), a fifth electrode pair (including a positive electrode 163 and a negative electrode 164), and also includes a sensitive unit 11A and a sensitive unit 13A, and the substrate 17 also includes The third base portion 173 . The sensitive unit 11A and the sensitive unit 13A are arranged side by side, and are connected across the second base portion 172 and the third base portion 173. The sensitive unit 11A is electrically connected to the positive electrode 153 and the negative electrode 154 of the fourth electrode pair, and the sensitive unit 13A is electrically connected to the positive electrode 153 and the negative electrode 154 of the fourth electrode pair. It is connected to the positive electrode 163 and the negative electrode 164 of the fifth electrode pair. The structure and quantity of the sensitive wires in the sensitive unit 11A and the sensitive unit 13A are the same as those of the sensitive unit 11 . The sensitive unit 11A and the sensitive unit 13A are distributed on both sides of the heating unit 12 , and may also be located on the same side of the heating unit 12 in other embodiments. In this embodiment, there is one heating wire 121 of the heating unit 12 , and in other embodiments, the number of heating wires 121 may also be multiple, such as 3, 5, 7 and so on.

The four sensitive units share one heating unit 12 , wherein the sensitive unit 11A and the sensitive unit 13A can be understood as a sensitive unit group, and the sensitive unit 11 and the sensitive unit 13 can be understood as another sensitive unit group. Each group of sensitive units works independently. When the fluid flows through each sensitive unit group, heat transfer occurs between the two sensitive units in each sensitive unit group, causing the temperature change of each sensitive unit. The sensitive wire in each sensitive unit The resistance value of the sensor changes with the temperature, and then the resistance value change of each sensitive wire in the two groups of sensitive unit groups is converted into a voltage change output through the circuit.

The embodiment of the present application uses the sensitive unit 11, the sensitive unit 13, the sensitive unit 11A and the sensitive unit 13A to construct a Wheatstone full-bridge differential output on the circuit structure, so that the output voltage difference of the fluid detection device is increased several times, and then the fluid The sensitivity of the detection device is effectively improved.

This application conducts performance testing and analysis on the fluid detection devices of the 3-wire structure sensitive unit, 5-wire structure sensitive unit and 11-line structure sensitive unit respectively, and obtains the frequency response curve shown in Figure 4 and the performance improvement shown in Table 1 below Analysis Table;

Table 1

It should be noted that the 3-wire structure is a reference design structure of a fluid detection device, which has a heating wire and 2 sensitive wires, and the 5-wire structure is the structure of a fluid detection device in an embodiment of the application, and its sensitive unit 11 is two, each sensitive unit has 2 sensitive wires and 2 sensitive wires are connected in series, there is 1 heating unit, and the heating unit has 1 heating wire, and the 7-wire structure is fluid detection in another embodiment of the application The structure of the device has two sensitive units 11, each sensitive unit has three sensitive wires connected in series, one heating unit has one heating wire.

Please refer to FIG. 4 . FIG. 4 is a frequency response curve when the sensitive unit of the fluid detection device according to the embodiment of the present application uses different numbers of sensitive wires. In FIG. 4, the abscissa represents frequency in Hz, and the ordinate represents sensitivity in dBV. It should be understood that the background noise is also called the background noise, which generally refers to the total noise in the electro-acoustic system except the useful signal.

It can be seen from Figure 4 and Table 1 that when the frequency is 100Hz, the noise floor of the 7-wire structure is about 5dBV, and the noise floor of the 11-wire structure is about 7dBV. Compared with the 3-wire structure, the signal-to-noise of the 7-wire structure The signal-to-noise ratio of the 11-wire structure is increased by about 10dB. When the frequency is 1kHz, compared with the 3-wire structure, the SNR of the 7-wire structure is increased by about 7dB, and the sensitivity is increased by about 12dBV. The noise ratio is increased by about 9dB, and the sensitivity is increased by about 16dBV. When the frequency is 10kHz, compared with the 3-wire structure, the signal-to-noise ratio of the 7-wire structure is increased by about 3dB, the sensitivity is increased by about 8dBV, and the signal-to-noise ratio of the 11-wire structure is increased by about 3dB. , the sensitivity is increased by about 10dBV.

Further, at least part of the wire segments of the sensitive wire are in a zigzag or wavy shape, and at least a part of the wire segments of the heating wire are in a zigzag or wavy shape. Wherein, at least part of the wire segments can be understood as: only part of the wire segments may be in a zigzag or wavy shape, or the entire wire segment may be in a zigzag or wavy shape.

Please refer to Fig. 5, Fig. 5 is a schematic structural diagram of the fluid detection device of the embodiment of the present application, the structure of the fluid detection device 1 shown in Fig. 5 is basically the same as Fig. The number of heating wires in the heating unit is two, and the sensitive wire 111 and the heating wire 121 are both zigzag. It should be noted that, in other embodiments, the number of sensitive wires 111 in the sensitive unit can also be more than 2, and the number of heating wires can also be 1 or more.

In one embodiment, when the fluid detection device further includes another sensitive unit 13 , the sensitive wire 131 in the sensitive unit 13 is also in a zigzag shape.

By designing at least part of the sensitive wire (such as the sensitive wire 111, the sensitive wire 131) and/or the heating wire 121 to be serrated or wavy, since the serrated or wavy heating wire/sensitive wire has a relatively high High thermal deformation ability, so more thermal stress can be released, and the maximum thermal stress of the heating wire/sensitive wire can be reduced, so that the heating wire and/or sensitive wire are not easy to bend and break, thereby effectively improving the reliability of the fluid detection device sex.

In other alternative embodiments, multiple sensitive wires 111 can be interwoven to form a grid-like structure. If the heating unit 12 has multiple heating wires 121, multiple heating wires 121 can also be interwoven to form a grid-like structure. Structure, because the grid-shaped sensitive wire/heating wire has greater thermal deformation capacity, so it can release more thermal stress at a higher working temperature, and is not easy to break, thereby improving the reliability of the sensitive wire/heating wire At the same time, due to the mesh structure design, the contact area between the sensitive wire/heating wire and the air increases under the same cross-sectional area, which is conducive to the heat exchange between the sensitive unit/heating unit, thus helping to improve the fluid detection device signal-to-noise ratio.

Please refer to FIG. 6. FIG. 6 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application. The structure of the fluid detection device 1 shown in FIG. 6 is basically the same as that in FIG. zigzag, and another part of the wire is straight; some of the heating wire 121 is zigzag, and the other part is straight. Specifically, the sensitive wire 111 is close to the electrode (such as the positive electrode 151 and the negative electrode 152). Some wire segments are zigzag, and some wire segments away from electrodes (such as positive electrode 151 and negative electrode 152) are linear. Similarly, some wire segments in heating wire 121 are close to electrodes (such as positive electrode 141 and negative electrode 142). It is zigzag, and the part of the wire away from the electrodes (such as the positive electrode 141 and the negative electrode 142 ) is straight. In one embodiment, when the fluid detection device further includes another sensitive unit 13, the sensitive wire 131 in the sensitive unit 13 adopts the same structure as the sensitive wire 111 in this embodiment.

The sensitive wire (such as sensitive wire 111, sensitive wire 131) and heating wire 121 of the embodiment of the present application adopt a composite structure of zigzag or wavy and straight line. /The maximum thermal stress of the heating wire, thereby improving the reliability of the fluid detection device, on the other hand, it can also avoid excessive thermal deformation of the heating wire/sensitive wire through the linear wire segment (the thermal deformation is too large, which will cause serious damage to the device) deviate from the design parameters, thereby reducing the sensitivity), so as to ensure that the sensitivity of the fluid detection device is not affected.

Further, please refer to FIG. 7. FIG. 7 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application. The structure of the fluid detection device 1 shown in FIG. 7 is basically the same as that in FIG. The wires 121 are all wavy, and further, the fluid detection device 1 also includes a first bracket 112; the first bracket 112 is supported between the zigzag or wavy wire segments of two adjacent sensitive wires 111, the first bracket 112 is arranged along the length direction perpendicular to the sensitive wire 111, and forms a structure similar to "bamboo knot" with two adjacent sensitive wires 111. When the heating unit 12 includes multiple heating wires 121, the fluid detection device 1 also includes a second Two brackets 122, the second bracket 122 is supported between the serrated or wavy wire segments of two adjacent heating wires 121, the second bracket 122 is arranged along the length direction perpendicular to the heating wire 121, and two adjacent The heating wire 121 forms a "bamboo-like" structure.

In one embodiment, the first bracket 112 includes a plurality of first bracket segments 1121, the plurality of first bracket segments 1121 are distributed along the length direction L of the sensitive wire, and each first bracket segment 1121 is supported on a corresponding adjacent Between the serrated or wavy wire segments of the two sensitive wires 111; the second bracket 122 includes a plurality of second bracket segments 1221, and the plurality of second bracket segments 1221 are distributed along the length direction L of the heating wire, and each The second bracket segments 1221 are supported between the corresponding zigzag or wavy wire segments of two adjacent heating wires. In one embodiment, when the fluid detection device further includes another sensitive unit 13, the sensitive wire 131 in the sensitive unit 13 adopts the same structure as the sensitive wire 111 in this embodiment.

In the embodiment of the present application, by arranging a first bracket between two adjacent sensitive wires and a second bracket between two adjacent heating wires, the distance between two adjacent sensitive wires and the distance between two adjacent heating wires can be improved. The stability between them makes the heating wire and/or sensitive wire not easy to bend or break, thereby effectively improving the reliability of the fluid detection device.

It should be noted that the various embodiments of the present application can be combined freely. For example, the sensitive wire in the sensitive unit and the heating wire in the heating unit can adopt the same shape or different shapes. Multiple wires in the same sensitive unit The sensitive wire and the multiple heating wires in the same heating unit can have the same shape or different shapes.

Further, please refer to Fig. 8 to Fig. 9. Fig. 8 and Fig. 9 are schematic structural diagrams of the fluid detection device of the embodiment of the present application. The structure of the fluid detection device 1 shown in Fig. 8 and Fig. 9 is basically the same as Fig. 2b, and its The difference is that: along the length direction perpendicular to the sensitive wires 111 (direction M shown by the arrow in Figure 8), the first beam structure 101 is connected between the multiple sensitive wires 111, and the first beam structure 101 is connected between the multiple sensitive wires 131. The first beam structure 101, in one embodiment, when the heating unit 12 includes a plurality of heating wires 121, along the length direction perpendicular to the heating wires 121 (the direction M shown by the arrow in FIG. 8 ), among the heating wires 121 A second beam structure (not shown) is connected between them. In one embodiment, the sensitive unit 11 is connected to the heating unit 12 along the length direction perpendicular to the sensitive wire (the direction M shown by the arrow in FIG. 8 ). There is a third beam structure (not shown in the figure), and a third beam structure (not shown in the figure) is connected between the sensitive unit 13 and the heating unit 12 . In one embodiment, the above-mentioned multiple beam structures can be integrated to form a beam structure 102 as shown in FIG. The beam structures can be arranged parallel to each other but not on the same straight line. Further, the beam structure may also be connected only between some sensitive wires, or only connected between some heating wires.

In the embodiment of the present application, a beam structure can be set between the sensitive wires 111, between the sensitive wires 131, between the heating wires 121, between the sensitive unit 11 and the heating unit 12, and between the sensitive unit 13 and the heating unit to improve the sensitivity of the sensitive wire 111. between the sensitive wires 131, between the heating wires 121, between the heating wires 121 and the sensitive wires 111, and between the heating wires 121 and the sensitive wires 131, so that the heating wires 121, the sensitive wires 111, the sensitive wires 131 is not easy to be bent or broken, which can effectively improve the reliability of the fluid detection device.

Further, please refer to FIGS. 10 to 11 . FIG. 10 is a schematic structural diagram of a fluid detection device according to an embodiment of the present application, and FIG. 11 is a schematic diagram of a grid structure in a fluid detection device according to an embodiment of the present application.

In one embodiment, the fluid detection device 1 includes a substrate (including a first substrate portion 171 and a second substrate portion 172), a first electrode pair (including a positive electrode 141 and a negative electrode 142), a second electrode pair (including a positive electrode 151 and negative electrode 152), a third electrode pair (including the positive electrode 161 and the negative electrode 162), and the heating unit 12, the sensitive unit 11 and the sensitive unit 13 arranged side by side at intervals.

The first electrode pair (including positive electrode 141 and negative electrode 142), the second electrode pair (including positive electrode 151 and negative electrode 152) and the third electrode pair (positive electrode 161 and negative electrode 162) are all fixed on the substrate 17, specifically The positive electrode 141 of the first electrode pair, the positive electrode 151 of the second electrode pair and the positive electrode 161 of the third electrode pair are all fixed on the first base portion 171, the negative electrode 142 of the first electrode pair, the second electrode pair Both the negative electrode 152 of the third electrode pair and the negative electrode 162 of the third electrode pair are fixed to the second base portion 172 .

In one embodiment, the sensitive unit 11 and the sensitive unit 13 are distributed on both sides of the heating unit 12 , and in other embodiments, the sensitive unit 11 and the sensitive unit 13 may also be distributed on the same side of the heating unit 12 .

The heating unit includes at least one heating wire 121, the sensitive unit 11 includes at least one sensitive wire 111, the sensitive unit 13 includes at least one sensitive wire 131, and the sensitive wire 111, the sensitive wire 131 and the heating wire 121 are all hollow grids shape structure.

In this embodiment, the number of sensitive wires of the sensitive unit 11 and the sensitive unit 13 is one, and the number of heating wires of the heating unit 12 is one. In other embodiments, the number of sensitive wires of each sensitive unit can also be more wires, such as 3 wires, 5 wires, 7 wires, etc., the number of heating wires of the heating unit may be more, such as 3 wires, 5 wires, 7 wires, etc.

It should be noted that the number of sensitive wires in the sensitive unit 11 and the sensitive unit 13 is the same. The number of heating wires 121 in the heating unit 12 may be the same as that of the sensitive unit 11 and the sensitive unit 13, or may be different.

The first electrode pair, the second electrode pair and the third electrode pair may be indirectly fixed to the substrate 17 through an electrode insulating layer fixed to the substrate 17 (including the first substrate part 171 and the second substrate part 172). In other embodiments , can also be fixed on the base 17 by other means. Wherein, the material of the electrode insulating layer is not limited. In one example, the electrode insulating layer can be silicon dioxide (SiO ₂ ), and in other examples, it can also be silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN ), alumina (Al ₂ O ₃ ) and so on.

In one embodiment, the heating wire 121 includes a heating wire metal layer, the heating wire metal layer has a hollow grid structure, and the heating wire metal layer is electrically connected to the positive electrode 141 and the negative electrode 142 of the first electrode pair, for Generate heat. The material of the metal layer of the heating wire is not limited. It can be a material with high thermal conductivity, such as metal wire, highly doped silicon, etc., or a metal composite laminate, such as a composite laminate of platinum, cadmium, and silicon nitride. In other embodiments, other materials may also be used.

In one embodiment, the heating wire 121 also includes a heating wire insulation layer, the heating wire insulation layer is used to support the heating wire metal layer and fix the heating wire to the base (such as the first base part 171 or the second base part 172), the heating wire The material of the insulating layer is not limited, for example, it can be silicon dioxide (SiO ₂ ), in other examples, it can also be silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ) etc.

The sensitive wire 111 and the sensitive wire 131 both include a sensitive wire metal layer, which is a hollow grid structure, and the sensitive wire metal layer is electrically connected to the corresponding positive electrode and the corresponding negative electrode for sensing temperature changes. The corresponding positive electrode and the corresponding negative electrode specifically include: the sensitive wire 111 is electrically connected to the positive electrode 151 and the negative electrode 152 of the second electrode pair, and the sensitive wire 131 is electrically connected to the positive electrode 161 and the negative electrode 162 of the third electrode pair. The material of the metal layer of the sensitive wire is not limited, it can be a material with high thermal resistivity, for example, it can be a composite laminate of platinum, cadmium, and silicon nitride, and in other embodiments, it can also be made of other materials.

In one embodiment, the sensitive wire 111 also includes a sensitive wire insulation layer, which is used to support the metal layer of the sensitive wire and fix the sensitive wire to the base (such as the first base part 171 or the second base part 172), and the sensitive wire The material of the insulating layer is not limited, for example, it can be silicon dioxide (SiO ₂ ), in other examples, it can also be silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ) etc.

Further, the size of the heating wire and the sensitive wire is not limited, as long as the above functional requirements can be met, it will not deviate from the scope of this embodiment. In an exemplary embodiment, the thickness of the sensitive wire and the heating wire is generally 0.3 μm, where , the metal layer is 0.1 μm, the insulating layer is 0.2 μm, the length of each sensitive wire 111 or each heating wire 121 of the sensitive unit 11 and the heating unit 12 is 0.5-2 mm, generally 1 mm, and the width is 0.5-2 μm .

Further, when there are multiple heating wires and/or multiple sensitive wires, the distance between two adjacent sensitive wires 111 in the fluid detection device sensitive unit 11 of the embodiment of the present application is greater than or equal to 1 μm and less than or equal to 1 μm. equal to 10 μm, and the distance between two adjacent heating wires 121 is less than or equal to 10 μm. Since the distance is small, when the fluid is disturbed, all the heating wires and all the sensitive wires work simultaneously. However, the spacing should not be too small. If the spacing is too small, it is not easy to process, and adjacent heating wires or adjacent sensitive wires will be bonded together. The distance should not be too large. If the distance is too large, the frequency response characteristics of adjacent sensitive wires or adjacent heating wires will be inconsistent, and then all heating wires and all sensitive wires cannot work at the same time.

Further, in one embodiment, the fluid detection device 1 can cancel the sensitive unit 13 and the third electrode pair, the heating unit 12 can be used as a sensitive unit again, and the heating wire 121 in the heating unit 12 also serves as a sensitive wire.

In the embodiment of the present application, by designing the sensitive wire and the heating wire into a grid-like structure, the sensitive wire and the heating wire can have greater thermal deformation capacity, and can release more thermal stress at a higher working temperature, which is not easy Fracture, thereby improving reliability, further, due to the mesh structure design, the contact area between the sensitive wire/heating wire and the air increases under the same cross-sectional area, which is conducive to the heat exchange between the sensitive unit/heating unit, so It helps to improve the signal-to-noise ratio of the fluid detection device.

Further, when there are multiple heating wires and/or sensitive wires, the multiple sensitive wires are distributed side by side along the length direction perpendicular to the sensitive wires, and the multiple sensitive wires can be connected to corresponding electrode pairs, for example, in series, or can be connected in parallel, for example For the corresponding electrode pair, if the fluid detection device in the embodiment of the present application has multiple sensitive units (such as the sensitive unit 11 and the sensitive unit 13), the multiple sensitive wires in the sensitive unit 11 and the multiple sensitive wires in the sensitive unit 13 should be The same structure, number of sensitive wires, and distance between the sensitive wires are used to ensure that the resistance changes of the two sensitive units are the same and are only related to the vibration velocity of the acoustic particles.

In one embodiment, a plurality of heating wires are distributed side by side along a length direction perpendicular to the heating wires, and the plurality of heating wires may be connected to the first electrode pair in series, or may be connected in parallel to the first electrode pair, for example.

In one embodiment, the ends of each of the multiple sensitive wires in series that are not connected to the electrode pair are respectively fixed to the base 17, taking the multiple sensitive wires 111 in series as an example, each of the multiple sensitive wires 111 is sensitive The sensitive wire segment connecting the wire 111 with the adjacent sensitive wire 111 overlaps the base 17 . It can be directly overlapped on the base 17, or indirectly overlapped on the base 17 through an overlapping bracket. It can be understood that: if there are multiple heating wires and adopt a series connection method, multiple heating wires can also be used The above-mentioned structure is overlapped on the base, if the fluid detection device also includes other sensitive units (such as the sensitive unit 13), and there are multiple sensitive wires in other sensitive units, the multiple sensitive wires in other sensitive units can also be overlapped with the above-mentioned structure on the base.

The embodiment of the present application adopts a sensitive unit composed of multiple sensitive wires in series, which helps to increase the input voltage of the sensitive unit through the series structure of multiple sensitive wires, thereby increasing the output voltage value of the sensitive unit in the circuit several times, so that The voltage difference between the sensitive units increases several times, so that the sensitivity and signal-to-noise ratio of the fluid detection device can be improved without changing the size of the sensitive wire (such as length, width, thickness, etc.) and without increasing the working temperature. By using a plurality of sensitive wires connected in parallel to form a sensitive unit, the noise floor (or thermal noise) of the fluid detection device can be effectively reduced, thereby improving the signal-to-noise ratio of the fluid detection device.

Further, the embodiment of the present application can also reduce the temperature of each heating wire to a certain extent by adopting multiple heating wires arranged side by side, thereby helping to avoid the self-melting phenomenon of the heating wire at high temperature. At the same time, compared with a single A fluid detection device with one heating wire, on the premise of meeting the same working temperature, since the temperature of each heating wire in the embodiment of the present application is lower, it can effectively improve the working sensitivity and signal-to-noise ratio of the fluid detection device under the unit power consumption .

Please refer to Fig. 12a, Fig. 12a is a schematic structural diagram of a microphone system according to an embodiment of the present application. The present application also provides a microphone 2, including the fluid detection device 1 involved in any of the above-mentioned embodiments. The microphone 2 also includes a power supply module 23 , a noise filtering module 21 and a signal processing module 22 .

Please refer to Figure 12b, Figure 12b is a schematic diagram of the circuit principle of the microphone of the embodiment of the present application, the power supply terminal V+ of the fluid detection device is electrically connected to the power supply module (not shown in the figure), and the signal output terminal of the fluid detection device 1 is electrically connected to the noise filter The input end of the module 21 is used to process the processed electrical signal through the noise filtering module 21, and the output end of the noise filtering module 21 is electrically connected to the input end of the signal processing module 22 to pass the processed electrical signal through the signal processing module 22 is amplified and then output through the output terminal Vout of the microphone. Wherein, the noise filtering module 21 can be realized by, for example, a capacitor C, and the signal processing module 22 can be realized by, for example, an amplifier A and two auxiliary resistors R0 connected to the output terminals of the amplifier. Further, the microphone may also include a speaker module, which is electrically connected to the signal processing module 22 to output or play sound.

Please refer to Figures 13a to 13b. Figure 13a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application. The structure of the fluid detection device shown in Figure 13a is basically the same as that in Figure 3b, except that the number of sensitive wires is 3 One and three sensitive wires are connected in parallel, and the number of heating wires is three and three heating wires are connected in parallel. Fig. 13b is a schematic diagram of an equivalent circuit of a microphone according to an embodiment of the present application, and the microphone shown in Fig. 13b adopts the fluid detection device 1 shown in Fig. 13a. Wherein, the resistances of the three sensitive wires 111 can be represented by resistance R1 , resistance R2 and resistance R3 respectively, and the resistances of the three heating wires 121 can be represented by resistance R4 , resistance R5 and resistance R6 respectively. In this embodiment, the heating unit 12 is multiplexed as a sensitive unit, and the heating wire 121 also serves as a sensitive wire.

This embodiment adopts the Wheatstone half-bridge principle to detect the electrical signal difference and then obtain the output voltage difference ΔU. The resistor R0 is an auxiliary resistor in the Wheatstone half-bridge circuit. When the microphone is working, the sound wave incident makes the sensitive unit 11 And the temperature of the heating unit 12 (doubling as the sensitive unit) changes oppositely, for example, the temperature of the sensitive unit 11 decreases, the temperature of the heating unit 12 increases, and then the resistance of the sensitive unit 11 decreases, and the resistance of the heating unit 12 increases , and further collect the voltage difference ΔU between the sensitive unit 11 and the heating unit 12 through the amplifier A, that is, ΔU=U2-U1 and output it through the output terminal Vout after being amplified. ΔU, U2, and U1 can be calculated by the following formula:

Wherein, U1 represents the output voltage of the sensitive unit 11, U2 represents the output voltage of the heating unit 12, and ΔU represents the voltage difference between the output voltage of the sensitive unit 11 and the output voltage of the heating unit 12;

Since the sensitive wires in the sensitive unit 11 and the heating wires in the heating unit 12 have the same structure and number, R represents the resistance value of a single sensitive wire (or a single heating wire) before the incident sound wave, and n represents the sensitive The number of sensitive wires in unit 11, n also characterizes the number of heating wires in heating unit 12, in this embodiment, n=3, in this embodiment, the resistance value of resistor R0 is R/n; ΔR represents each The resistance change value of the root sensitive wire 111 after the incident sound wave also characterizes the resistance change value of each heating wire 121 after the incident sound wave;

V ₊ represents the power supply voltage of the fluid detection device;

N represents the noise floor of the fluid detection device (or can be understood as thermal noise);

K _B is Boltzmann's constant, K _B =1.38×10 ^-23 J/K;

T is the temperature of the fluid detection device;

It can be seen from this that the embodiment of the present application can reduce the noise floor (or thermal noise) of the fluid detection device

times, thereby improving the signal-to-noise ratio of the fluid detection device

times.

Please refer to Figures 14a to 14b. Figure 14a is a schematic structural diagram of a fluid detection device according to an embodiment of the present application. The structure of the fluid detection device shown in Figure 14a is basically the same as that in Figure 3a, except that the number of sensitive wires is 3 One and three sensitive wires are connected in series, and the number of heating wires is three and three heating wires are connected in series. Fig. 14b is a schematic diagram of an equivalent circuit of a microphone according to an embodiment of the present application, and the microphone shown in Fig. 14b adopts the fluid detection device 1 shown in Fig. 14a. Wherein, the resistances of the three sensitive wires 111 can be represented by resistance R1 , resistance R2 and resistance R3 respectively, and the resistances of the three heating wires 121 can be represented by resistance R4 , resistance R5 and resistance R6 respectively. The resistor R0 is an auxiliary resistor constituting the Wheatstone half-bridge circuit. In this embodiment, the heating unit 12 is multiplexed as a sensitive unit, and the heating wire 121 also serves as a sensitive wire.

When the microphone works, the incident sound wave causes the temperature of the sensitive unit 11 and the heating unit 12 to change oppositely, for example, the temperature of the sensitive unit 11 decreases, and the temperature of the heating unit 12 (doubling as a sensitive unit) increases, and then the resistance of the sensitive unit 11 decreases, the resistance of the heating unit 12 increases, and the voltage difference ΔU between the sensitive unit 11 and the heating unit 12 is further collected through the amplifier A, that is, ΔU=U2-U1, and is amplified and then output through the output terminal Vout, ΔU, U2 , U1 can be calculated by the following formula:

Since the sensitive wires in the sensitive unit 11 and the heating wires in the heating unit 12 have the same structure and quantity, R represents the resistance value of a single sensitive wire (or a single heating wire) before the incident sound wave, and n represents the resistance value of the sensitive unit 11 is the number of sensitive wires, and n also characterizes the number of heating wires in the heating unit 12. In this embodiment, n=3. In this embodiment, the resistance value of resistor R0 is nR; ΔR represents the number of each sensitive wire The resistance change value of 111 after the incident sound wave also represents the resistance change value of each heating wire 121 after the incident sound wave;

V ₊ represents the power supply voltage of each sensitive wire of the fluid detection device;

K _B is Boltzmann's constant, K _B =1.38×10 ^-23 J/K;

T is the temperature of the fluid detection device;

It can be seen from this that, compared with _the traditional fluid detection device, the embodiment of the present application can make the fluid detection The output voltage difference △U of the device is increased by n times, thereby increasing the sensitivity by n times, and at the same time, the noise floor (or thermal noise) is reduced

times, thereby improving the signal-to-noise ratio

times.

FIG. 15 is a schematic diagram of an equivalent circuit of a microphone according to an embodiment of the present application. Please refer to FIG. 3c and FIG. 3d for the structure of the fluid detection device. Wherein, the number of sensitive units is 4, and the number of heating units is 1. The total resistance of the sensitive unit 11 can be characterized by _R11 , the total resistance of the sensitive unit 13 can be characterized by _R13 , the total resistance of the sensitive unit 11A can be characterized by _R11A , and the resistance of the sensitive unit 13A can be characterized by _R13A .

In this embodiment, the sensitive unit 11, the sensitive unit 13, the sensitive unit 11A and the sensitive unit 13A are used to construct a Wheatstone full-bridge circuit, and the Wheatstone full-bridge principle is used to perform differential detection of electrical signals to obtain the output voltage difference ΔU. When the microphone is working, the incident sound wave causes the temperature of the sensitive unit 11 and the sensitive unit 13 to change oppositely, for example, the temperature of the sensitive unit 11 decreases, and the temperature of the sensitive unit 13 increases, and then, the resistance of the sensitive unit 11 decreases, and the temperature of the sensitive unit 13 increases. The resistance of 13 increases, and at the same time, the incident sound wave also makes the temperature of sensitive unit 11A and sensitive unit 13A change oppositely, for example, the temperature of sensitive unit 11A decreases, and the temperature of sensitive unit 13A increases, and then, the resistance of sensitive unit 11A decreases, the resistance of the sensitive cell 13A increases. Further collect the output voltages of the sensitive unit 11 and the sensitive unit 13A through the amplifier A, and the voltage difference ΔU between the output voltages of the sensitive unit 13 and the sensitive unit 11A, that is, ΔU=U2-U1 and amplify it and output it through the output terminal Vout, ΔU, U2, U1 can be calculated by the following formula:

Among them, U1 represents the output voltage of the sensitive unit 11 and the sensitive unit 13A, U2 represents the output voltage of the sensitive unit 13 and the sensitive unit 11A, ΔU represents the output voltage of the sensitive unit 11 and the sensitive unit 13A, and the sensitive unit 13 and the the voltage difference between the output voltages of the sensitive unit 11A;

Since the sensitive wires in the sensitive unit 11, the sensitive unit 13, the sensitive unit 11A and the sensitive unit 13A all adopt the same structure and quantity, therefore, R simultaneously represents the The resistance value before the incident sound wave, △R represents the resistance change value of each sensitive wire after the incident sound wave;

V ₊ represents the power supply voltage of the fluid detection device;

It can be seen from this that the embodiment of the present application can increase the output voltage difference ΔU of the fluid detection device by two times compared with the fluid detection device described in Figure 13b, thereby improving both the sensitivity and the signal-to-noise ratio of the fluid detection device doubled.

Further, the microphone provided by the embodiment of the present application may be, for example, a microphone, which may be installed in an electronic device. Specifically, the microphone may include a circuit board for carrying the above-mentioned circuit, and also include a microphone housing, a micro-electromechanical A system chip and a functional integrated circuit chip, the microphone shell is arranged on the microphone circuit board and forms a microphone cavity with the microphone circuit board. Both the MEMS chip and the functional integrated circuit chip are arranged in the microphone cavity, and the microphone circuit board can be arranged on the circuit board of the electronic device and electrically connected with the circuit board of the electronic device. In other implementation manners, the microphone may also have other structures, which are not limited in this application.

The present application also provides an electronic device, including the microphone involved in the foregoing embodiments. Electronic devices can be, for example, smart TVs, smart speakers, smart large-screen conference systems, smart cars, and so on.

For example, the electronic device provided by the embodiment of the present application needs to pick up sound in the application scenario of smart TV, and can use a microphone to pick up sound in a figure-of-eight pattern to collect the sound from the front and back of the smart TV, such as human voice, which is suitable for man-machine Scenarios such as voice conversations.

Obviously, those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

A fluid detection device, comprising a substrate, a first electrode pair, a second electrode pair, and a heating unit and a sensitive unit arranged side by side at intervals, the first electrode pair and the second electrode pair are fixed to the substrate; The heating unit is electrically connected to the positive electrode and the negative electrode of the first electrode pair, the sensitive unit is electrically connected to the positive electrode and the negative electrode of the second electrode pair, and the sensitive unit is used to sense the ambient temperature; characterized by:

The sensitive unit includes a plurality of sensitive wires, and the plurality of sensitive wires are arranged in parallel along the length direction perpendicular to the sensitive wires; the plurality of sensitive wires are connected in series or in parallel to the positive electrode of the second electrode pair and negative electrode.
The fluid detection device according to claim 1, characterized in that:

The ends of each of the plurality of sensitive wires in series that are not connected to the second electrode pair are respectively fixed to the base.
The fluid detection device according to claim 1 or 2, wherein the substrate is provided with a channel for fluid flow, and when the fluid flows in the channel, the fluid flows through the sensitive unit.
The fluid detection device according to any one of claims 1 to 3, wherein the heating unit comprises a plurality of heating wires, and the plurality of heating wires are arranged side by side along a length direction perpendicular to the heating wires; The plurality of heating wires are connected in series or in parallel to the positive electrode and the negative electrode of the first electrode pair.
The fluid detection device according to claim 4, characterized in that, the ends of each heating wire not connected to the first pair of electrodes among the plurality of heating wires connected in series are respectively fixed to the base.
The fluid detection device according to claim 4 or 5, wherein the heating unit is multiplexed as another sensitive unit, and the heating wire in the heating unit multiplexed as the other sensitive unit doubles as a sensitive wire , the structure of the heating unit multiplexed as the another sensitive unit is the same as that of the sensitive unit.
The fluid detection device according to any one of claims 1-5, characterized in that, the fluid detection device further comprises another sensitive unit and a third electrode pair, the third electrode pair is fixed on the substrate, and the The other sensitive unit is electrically connected to the positive electrode and the negative electrode of the third electrode pair, the heating unit, the sensitive unit and the other sensitive unit are arranged side by side at intervals, and the structure of the other sensitive unit Same structure as the sensitive unit.
The fluid detection device according to any one of claims 1-7, characterized in that at least part of the wire segments of the sensitive wire are jagged or wavy; and/or:

When the heating unit includes a plurality of heating wires, at least part of the wire segments of the heating wires are zigzag or wavy.
The fluid detection device according to claim 8, wherein a part of the heating wire is in a zigzag or wavy shape, another part of the heating wire is in a straight line; a part of the sensitive wire is The segment is jagged or wavy, and the other segment of the sensitive wire is straight.
The fluid detection device according to claim 8 or 9, characterized in that, the fluid detection device further comprises a first bracket; the first bracket is supported by the serrated or wavy wires of two adjacent sensitive wires between paragraphs; and/or:

When the heating unit includes a plurality of heating wires, the fluid detection device further includes a second bracket, and the second bracket is supported between the zigzag or wavy segments of two adjacent heating wires.
The fluid detection device according to claim 10, wherein the first bracket comprises a plurality of first bracket segments, the plurality of first bracket segments are distributed along the length direction of the sensitive wire, and each of the first bracket segments A support segment is supported between the corresponding partial wire segments of two adjacent sensitive wires;

The second support includes a plurality of second support segments, the plurality of second support segments are distributed along the length direction of the heating wire, and each second support segment is supported on the corresponding two adjacent heating wires. Between said partial wire segments.
The fluid detection device according to any one of claims 1 to 7, wherein the sensitive wires are in a grid structure, or the plurality of sensitive wires form a grid structure; and/or:

When the heating unit includes multiple heating wires, the heating wires are in a grid structure, or the multiple heating wires form a grid structure.
The fluid detection device according to any one of claims 1-11, characterized in that, along the length direction perpendicular to the sensitive wires, a first beam structure is connected between the plurality of sensitive wires; and/or:

When the heating unit includes a plurality of heating wires, a second beam structure is connected between the plurality of heating wires along a length direction perpendicular to the heating wires.
The fluid detection device according to any one of claims 1-13, characterized in that, along the length direction perpendicular to the sensitive wire, a third beam structure is connected between the sensitive unit and the heating unit.
The fluid detection device according to any one of claims 1-14, characterized in that:

The distance between two adjacent sensitive wires in the sensitive unit is greater than or equal to 1 μm and less than or equal to 10 μm; and/or:

When the heating unit includes multiple heating wires, the distance between two adjacent heating wires is greater than or equal to 1 μm and less than or equal to 10 μm.
A microphone, characterized by comprising the fluid detection device according to any one of claims 1-15.
An electronic device, characterized by comprising the microphone according to claim 16.