MEMS three-dimensional wind field sensor

Abstract

The invention discloses an MEMS (Micro Electro Mechanical System) three-dimensional wind field sensor, which comprises cilia, a cilia chassis, a flaky probe, a rigidity block, a fixed pile, an X-direction torsion beam, a Y-direction torsion beam, a Z-direction torsion beam and a piezoresistive stress sensor, the cilium chassis is connected to the sheet-shaped probe through the X-direction torsion beam, the sheet-shaped probe is connected to the rigidity block through the Y-direction torsion beam, and the rigidity block is connected to the fixing pile through the Z-direction torsion beam. Wherein the X-direction torsion beam, the Y-direction torsion beam and the Z-direction torsion beam are respectively provided with the piezoresistive stress sensors, and each piezoresistive stress sensor adopts a Wheatstone bridge circuit type structure. According to the MEMS three-dimensional wind field sensor provided by the invention, the sensing sensitivity of the sensor is effectively improved, three-dimensional direction sensing signal decoupling can be realized, and the whole sensor structure can be integrated and miniaturized.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a MEMS three-dimensional wind field sensor. Background Art

[0002] With the continuous advancement of science and technology, accurate acquisition of wind field information has become crucial in many fields. Weather forecasts require more sophisticated wind field data to improve prediction accuracy, so as to better provide early warning and guidance information for people's production and life. In the field of aerospace, the safe operation of aircraft depends on the accurate perception of the surrounding wind field to optimize the flight path and ensure stability. In the field of new energy, the efficiency improvement of wind power generation and solar power generation is also inseparable from the precise monitoring of wind fields. However, traditional wind field sensors have certain shortcomings in terms of accuracy, response speed, miniaturization, etc. MEMS (Micro-Electro-Mechanical System) wind field sensors are gradually replacing traditional wind field sensors in various industries based on their advantages of small integration, low power consumption, light weight, and easy mass production.

[0003] At present, MEMS wind field sensors can be mainly divided into thermal, piezoelectric and piezoresistive types according to the sensing principle. Among them, piezoresistive MEMS wind field sensors have attracted widespread attention and have been studied by many scholars due to their wide measurement range, simple process and low power consumption.

[0004] The MEMS three-dimensional vector anemometer developed by North University of China is mainly composed of a cilia with a disc and a cross beam. The cilia are fixed on the central connector of the cross beam, and a piezoresistor is arranged at the root of the cross beam. The sensing principle is that when the wind pressure acts on the cilia, the cilia deflect or move, causing the cross beam to bend and deform, generating stress at the root of the cross beam. The resistance of the piezoresistor changes with the stress at the root, and then outputs an electrical signal to complete the collection of wind field information. Analysis of its sensing principle shows that the sensitivity of the piezoresistive sensor is related to the degree of deformation of the cross cantilever beam, that is, at the same wind speed, the greater the deformation of the cantilever beam, the higher the sensitivity. However, in this structure, the torque generated at the central connection by the wind pressure in a certain direction on the cilia is not fully utilized. Part of the torque is used to deform the cantilever beam in that direction to sense the wind force in that direction, and the other part of the torque acts on the cantilever beam in the other direction to cause it to produce useless torsional deformation. In addition, since the elastic modulus of silicon is greater than the shear modulus, under the same torque, the bending deformation of the cantilever beam is smaller than the torsional deformation, and the sensitivity of the device using bending deformation as the sensing principle is relatively low. In addition, the wind pressure reception in the Z-axis direction in this structure mainly relies on the disk on the cilia, which is not integrally formed in the micro-nano processing of the device, thus increasing the difficulty of integration and the error of sensing accuracy.

[0005] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a MEMS three-dimensional wind field sensor, which effectively improves the sensing sensitivity of the sensor, can realize the decoupling of three-dimensional directional sensing signals, and can integrate and miniaturize the overall sensor structure.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention discloses a MEMS three-dimensional wind field sensor, comprising cilia, a cilia chassis, a sheet probe, a stiffness block, a fixed pile, an X-direction torsion beam, a Y-direction torsion beam, a Z-direction torsion beam and a piezoresistive stress sensor, wherein the cilia are fixedly connected to the cilia chassis, the cilia chassis is connected to the sheet probe through the X-direction torsion beam, the sheet probe is connected to the stiffness block through the Y-direction torsion beam, the stiffness block is connected to the fixed pile through the Z-direction torsion beam, wherein the piezoresistive stress sensor is respectively arranged on the X-direction torsion beam, the Y-direction torsion beam and the Z-direction torsion beam, and each piezoresistive stress sensor adopts a Wheatstone bridge circuit structure.

[0009] Preferably, the X-direction torsion beam includes a first X-direction sub-twist beam and a second X-direction sub-twist beam, the Y-direction torsion beam includes a first Y-direction sub-twist beam and a second Y-direction sub-twist beam, the Z-direction torsion beam includes a first Z-direction sub-twist beam, a second Z-direction sub-twist beam, a third Z-direction sub-twist beam and a fourth Z-direction sub-twist beam, the first X-direction sub-twist beam and the second X-direction sub-twist beam are respectively connected between the two sides of the ciliary chassis in the Y direction and the sheet probe, the first Y-direction sub-twist beam and the second Y-direction sub-twist beam are respectively connected between the two sides of the sheet probe in the X direction and the stiffness block, and the first Z-direction sub-twist beam, the second Z-direction sub-twist beam, the third Z-direction sub-twist beam and the fourth Z-direction sub-twist beam are respectively connected between the four corners of the stiffness block and the fixed pile.

[0010] Preferably, the piezoresistive stress sensor includes a first sub-piezoresistive stress sensor, a second sub-piezoresistive stress sensor, a third sub-piezoresistive stress sensor and a fourth sub-piezoresistive stress sensor, wherein the first sub-piezoresistive stress sensor is arranged on the first X-direction sub-torsion beam, the second sub-piezoresistive stress sensor is arranged on the first Y-direction sub-torsion beam, and the third sub-piezoresistive stress sensor and the fourth sub-piezoresistive stress sensor are respectively arranged on the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam.

[0011] Preferably, the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam are connected to two Z-direction torsion beams opposite to each other on the diagonal line of the stiffness block.

[0012] Preferably, the first sub-piezoresistive stress sensor is arranged on the first X-direction sub-torsion beam at an end close to the sheet probe, the second sub-piezoresistive stress sensor is arranged on the first Y-direction sub-torsion beam at an end close to the stiffness block, and the third sub-piezoresistive stress sensor and the fourth sub-piezoresistive stress sensor are respectively arranged on the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam at ends close to the fixed pile.

[0013] Preferably, the first piezoresistive stress sensor adopts a first Wheatstone bridge circuit structure, wherein four first piezoresistors of the first Wheatstone bridge circuit structure are connected end to end to form a first square, and each of the first piezoresistors is 45° to the axial direction of the first X-direction sub-torsion beam, wherein a DC voltage is applied between two points on the first square along a diagonal line in the axial direction of the first X-direction sub-torsion beam, and a voltage difference between two points on the first square along a diagonal line perpendicular to the axial direction of the first X-direction sub-torsion beam is measured as an X-direction output electrical signal.

[0014] Preferably, the second piezoresistive stress sensor adopts a second Wheatstone bridge circuit structure, wherein four second piezoresistors of the second Wheatstone bridge circuit structure are connected end to end to form a second square, and each of the second piezoresistors is at 45° to the axial direction of the first Y-direction sub-torsion beam, wherein a DC voltage is applied between two points on the second square along a diagonal line along the axial direction of the first Y-direction sub-torsion beam, and the voltage difference between the two points on the second square along a diagonal line perpendicular to the axial direction of the first Y-direction sub-torsion beam is measured as an output electrical signal in the Y direction.

[0015] Preferably, the third piezoresistive stress sensor and the fourth piezoresistive stress sensor jointly form a third Wheatstone bridge circuit structure, wherein the third Wheatstone bridge circuit structure is composed of a third A piezoresistance, a third B piezoresistance, a third C piezoresistance and a third D piezoresistance, wherein the third A piezoresistance and the third B piezoresistance are respectively arranged at 45° to the axial direction of the first Z-direction sub-torsion beam and are interconnected on the first Z-direction sub-torsion beam, and the third C piezoresistance and the third D piezoresistance are respectively arranged at 45° to the axial direction of the third Z-direction sub-torsion beam and are interconnected on the third Z-direction sub-torsion beam, wherein a DC voltage is applied between the two ends of the interconnected third A piezoresistance and the third B piezoresistance and between the two ends of the interconnected third C piezoresistance and the third D piezoresistance, respectively; and a voltage difference between a first point where the third A piezoresistance and the third B piezoresistance intersect and a second point where the third C piezoresistance and the third D piezoresistance intersect is measured as a Z-direction output electrical signal.

[0016] Preferably, the opening direction of the third A piezoresistance connected to the third B piezoresistance and the opening direction of the third C piezoresistance connected to the third D piezoresistance are respectively oriented toward the fixing pile.

[0017] Preferably, the ciliary chassis, the sheet probe, the stiffness block, the fixing pile, the X-direction torsion beam, the Y-direction torsion beam, the Z-direction torsion beam and the piezoresistive stress sensor are arranged in the same plane, and the structure of each part is processed on a silicon wafer by photolithography, etching and ion implantation.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the MEMS three-dimensional wind field sensor disclosed in the present invention uses the piezoresistance sensing torsional deformation of the Wheatstone bridge circuit layout as the three-axis wind sensing principle; and the deformation of the cantilever beams in the X and Y directions is decoupled. When the cilia are subjected to wind in one direction, only the cantilever beam sensing the direction is torsionally deformed, and the cantilever beam in the other direction is basically not torsionally deformed; the Z-axis wind receiving device is integrated into the chip itself, so that it is integrally formed with the device during the micro-nano processing process, reducing the difficulty of secondary integration and the error of sensing accuracy; the layout of the Z-axis wind sensing piezoresistance is designed to complete the decoupling of the three-axis sensing electrical signal output. The present invention effectively improves the sensing sensitivity of the sensor, can realize the decoupling of the three-dimensional direction sensing signal, and can make the overall sensor structure integrated and miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the planar structure design of the MEMS three-dimensional wind field sensor;

[0020] Figure 2This is the design diagram of the piezoresistive stress sensor of the MEMS three-dimensional wind field sensor;

[0021] Figure 3a to Figure 3d They are schematic diagrams of structures of different shapes of the connection between the X-direction torsion beam and the Y-direction torsion beam in other embodiments;

[0022] Figure 4 is a structural diagram of a triangular stiffness block device in other embodiments;

[0023] Figure 5a This is a model diagram of a MEMS three-dimensional wind field sensor;

[0024] Figure 5b This is the simulation effect diagram of the wind force in the X-axis direction on the MEMS three-dimensional wind field sensor;

[0025] Figure 5c This is the simulation effect diagram of the wind force in the Y-axis direction on the MEMS three-dimensional wind field sensor;

[0026] Figure 5d This is the simulation effect diagram of the wind force in the Z-axis direction on the MEMS three-dimensional wind field sensor;

[0027] Figure 6 is a Wheatstone bridge circuit layout diagram of a piezoresistive stress sensor;

[0028] Figure 7a It is the deformation diagram of the torsion beam in the Z direction under the wind input in the X direction;

[0029] Figure 7b It is the deformation diagram of the torsion beam in the Z direction under the wind input in the Y direction;

[0030] Figure 7c It is the deformation diagram of the torsion beam in the Z direction under the wind force input in the Z direction;

[0031] Figure 8a It is the change diagram of the piezoresistance value of the torsion beam in the Z direction when the wind force is input in the X direction;

[0032] Figure 8b It is the change diagram of the piezoresistance value of the torsion beam in the Z direction when the wind force is input in the Y direction;

[0033] Figure 8c It is the change diagram of the piezoresistance value of the torsion beam in the Z direction when the wind force is input in the Z direction;

[0034] Figure 8d It is a schematic diagram of the arrangement of a Z-direction torsion beam piezoresistive Wheatstone bridge.

[0035] Description of Figure Numbers:

[0036] 10. Cilia; 20. Cilia chassis; 30. Sheet probe; 40. Stiffness block; 50. Fixing pile; 60. Piezoresistive stress sensor; 61. X-direction piezoresistive stress sensor; 62. Y-direction piezoresistive stress sensor; 63. First Z-direction piezoresistive stress sensor; 64. Second Z-direction piezoresistive stress sensor; 71. X-direction torsion beam; 72. Y-direction torsion beam; 73. Z-direction torsion beam. DETAILED DESCRIPTION

[0037] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0038] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for both fixing and circuit / signal communication.

[0039] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0041] like Figure 1As shown, a preferred embodiment of the present invention discloses a MEMS three-dimensional wind field sensor, including cilia 10, a cilia chassis 20, a sheet probe 30, a stiffness block 40, a fixed pile 50, an X-direction torsion beam 71, a Y-direction torsion beam 72, a Z-direction torsion beam 73 and a piezoresistive stress sensor 60, wherein the cilia 10 are fixedly connected to the cilia chassis 20, the cilia chassis 20 is connected to the sheet probe 30 through the X-direction torsion beam 71, the sheet probe 30 is connected to the stiffness block 40 through the Y-direction torsion beam 72, and the stiffness block 40 is connected to the fixed pile 50 of the device through the Z-direction torsion beam 73, wherein the X-direction torsion beam 71, the Y-direction torsion beam 72 and the Z-direction torsion beam 73 are respectively provided with a piezoresistive stress sensor 60, and each piezoresistive stress sensor 60 adopts a Wheatstone bridge circuit structure. Among them, the cilia 10 and the sheet probe 30 serve as wind receiving components, which amplify the wind pressure and transmit force through the lever principle; the ciliary chassis 20 supports the cilia 10; each torsion beam connects the fixed pile 50 and the wind receiving component, and converts the wind force into tangential stress through torsion; the stiffness block 40 can increase the stiffness of the connection between the Z-direction torsion beam and the Y-direction torsion beam, and better concentrate the stress on the root of the Z torsion beam; the piezoresistive stress sensor 60 can convert mechanical information into electrical signals; the fixed pile 50 can fix the device (i.e., the MEMS three-dimensional wind field sensor) as a whole to the PCB circuit board.

[0042] The X-direction torsion beam 71 includes a first X-direction sub-torsion beam and a second X-direction sub-torsion beam, the Y-direction torsion beam 72 includes a first Y-direction sub-torsion beam and a second Y-direction sub-torsion beam, and the Z-direction torsion beam 73 includes a first Z-direction sub-torsion beam, a second Z-direction sub-torsion beam, a third Z-direction sub-torsion beam and a fourth Z-direction sub-torsion beam. The first X-direction sub-torsion beam and the second X-direction sub-torsion beam are respectively connected between the two sides of the ciliary chassis 20 in the Y direction and the sheet probe 30, the first Y-direction sub-torsion beam and the second Y-direction sub-torsion beam are respectively connected between the two sides of the sheet probe 30 in the X direction and the stiffness block 40, and the first Z-direction sub-torsion beam, the second Z-direction sub-torsion beam, the third Z-direction sub-torsion beam and the fourth Z-direction sub-torsion beam are respectively connected between the four corners of the stiffness block 40 and the fixed pile 50.

[0043] Combination Figure 2The piezoresistive stress sensor 60 includes a first sub-piezoresistive stress sensor 61, a second sub-piezoresistive stress sensor 62, a third sub-piezoresistive stress sensor 63 and a fourth sub-piezoresistive stress sensor 64, wherein the first sub-piezoresistive stress sensor 61 is arranged on the first X-direction sub-torsion beam, the second sub-piezoresistive stress sensor 62 is arranged on the first Y-direction sub-torsion beam, the third sub-piezoresistive stress sensor 63 and the fourth sub-piezoresistive stress sensor 64 are arranged on the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam, respectively. In this embodiment, the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam are connected to two Z-direction torsion beams 73 opposite to each other on the diagonal line of the stiffness block 40. Furthermore, the first sub-piezoresistive stress sensor 61 is arranged on the first X-direction sub-torsion beam at the end close to the sheet probe 30, the second sub-piezoresistive stress sensor 62 is arranged on the first Y-direction sub-torsion beam at the end close to the stiffness block 40, and the third sub-piezoresistive stress sensor and the fourth sub-piezoresistive stress sensor are respectively arranged on the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam at the ends close to the fixed pile 50.

[0044] The first piezoresistive stress sensor 61 adopts a first Wheatstone bridge circuit structure, wherein four first piezoresistors of the first Wheatstone bridge circuit structure are connected end to end to form a first square, and each first piezoresistor is 45° with the axial direction of the first X-direction sub-torsion beam, wherein a DC voltage is applied between two points on the first square along the diagonal line of the axial direction of the first X-direction sub-torsion beam (i.e., two points ab along the diagonal line in the Y-axis direction), and a voltage difference between two points on the first square along the diagonal line perpendicular to the axial direction of the first X-direction sub-torsion beam (i.e., two points cd along the diagonal line in the X-axis direction) is measured as an X-direction output electrical signal.

[0045] The second piezoresistive stress sensor 62 adopts a second Wheatstone bridge circuit structure, wherein four second piezoresistors of the second Wheatstone bridge circuit structure are connected end to end to form a second square, and each second piezoresistor is at 45° to the axial direction of the first Y-direction sub-torsion beam, wherein a DC voltage is applied between two points on the second square along the diagonal of the axial direction of the first Y-direction sub-torsion beam (i.e., two points ab along the diagonal in the X-axis direction), and the voltage difference between two points on the second square along the diagonal perpendicular to the axial direction of the first Y-direction sub-torsion beam (i.e., two points cd along the diagonal in the Y-axis direction) is measured as an output electrical signal in the Y direction.

[0046] The third piezoresistive stress sensor 63 and the fourth piezoresistive stress sensor 64 together form a third Wheatstone bridge circuit structure, wherein the third Wheatstone bridge circuit structure is composed of a third A piezoresistance, a third B piezoresistance, a third C piezoresistance and a third D piezoresistance, wherein the third A piezoresistance and the third B piezoresistance are respectively arranged at 45° to the axial direction of the first Z-direction sub-torsion beam and are interconnected on the first Z-direction sub-torsion beam, and the third C piezoresistance and the third D piezoresistance are respectively arranged at 45° to the axial direction of the third Z-direction sub-torsion beam and are interconnected on the third Z-direction sub-torsion beam, wherein a DC voltage is applied between the two ends of the interconnected third A piezoresistance and the third B piezoresistance (between points ab) and between the two ends of the interconnected third C piezoresistance and the third D piezoresistance (between points ab), and the voltage difference between the first point (point c) where the third A piezoresistance and the third B piezoresistance intersect and the second point (point d) where the third C piezoresistance and the third D piezoresistance intersect is measured as a Z-direction output electrical signal. Further, the opening direction of the third A piezoresistance connected to the third B piezoresistance and the opening direction of the third C piezoresistance connected to the third D piezoresistance are respectively oriented toward the fixing pile 50 .

[0047] In this embodiment, the ciliary chassis 20, the sheet probe 30, the stiffness block 40, the fixed pile 50, the X-direction torsion beam 71, the Y-direction torsion beam 72, the Z-direction torsion beam 73 and the piezoresistive stress sensor 60 are arranged in the same plane, and the structures of each part are processed on the silicon wafer by photolithography, etching and ion implantation. The cilia 10 is then fixedly connected to the ciliary chassis 20 by bonding. Some existing wind field sensors usually only retain the XY-direction torsion beam, the central connector and the fixed pile, and all other parts are etched away, and then a device for receiving the Z-direction wind force is processed on the cilia; and the device of the present invention, except for the cilia, the rest of the parts are processed on the silicon wafer by photolithography and etching. When etching the XY-direction torsion beam and other parts, the sheet probe part can be retained. Therefore, the processing of the Z-axis sensing probe of the present invention does not require additional processes and steps.

[0048] Figure 1It is a preferred embodiment of the planar structural schematic diagram of the MEMS three-dimensional wind field sensor in the preferred embodiment of the present invention, wherein the sheet probe 30 is a rectangular structure, wherein grooves are respectively opened inwardly at the middle positions of the two side edges parallel to the Y-axis on the sheet probe 30, and the first Y-direction sub-torsion beam and the second Y-direction sub-torsion beam respectively extend outward from the bottom of the two grooves until they are connected to the stiffness block 40. In other embodiments, on the first aspect, the shape of the part of the connected X-direction torsion beam and the Y-direction torsion beam and the shape of the cilia in the MEMS three-dimensional wind field sensor proposed by the present invention are not restricted, and can be all axially symmetrical shapes such as square, ellipse, rectangle, etc., wherein the first Y-direction sub-torsion beam and the second Y-direction sub-torsion beam can also respectively extend outward from the two opposite sides of the sheet probe along the X-axis direction until they are connected to the stiffness block 40, as shown in Figure 3; wherein these structures can realize the inter-axial structural decoupling function, but the sensitivity to wind force sensing in each direction will be different. On the second aspect, the shape of the stiffness block is also not restricted, and can be a triangle, such as Figure 4 The structures in the red boxes on both sides are stiffness blocks, but their sensitivity may be lower than that of rectangular stiffness blocks. Figure 4 As shown, the piezoresistive stress sensors connected to the Z-direction torsion beam can also be arranged on the same side, and the wind force in the Z-axis direction can be further decoupled by data processing.

[0049] The piezoresistive MEMS three-dimensional wind field sensor proposed in the above embodiment of the present invention decouples the sensing principle of the X, Y, and Z three-axis wind force through structural design and piezoresistive arrangement design, which can effectively improve the sensitivity of wind field sensing and increase the stability of the device. Due to the mutual restrictions and constraints of the beams in each axial direction, the traditional cross-beam structure wind field sensor cannot maximize the conversion of wind force into stress at the root of the beam. In order to obtain a larger stress, the device thickness is often designed to be thinner, which also reduces the resonant frequency, structural strength and stability of the device, and the sensitivity is low. The device proposed in the present invention separates the beams that sense the wind force in the three-axis direction, so that it is not affected by other axial wind forces when sensing the torsional deformation of its own axial wind force, eliminates the mutual restrictions of deformation between the three axes, and maximizes the use of the torque generated by wind pressure on the torsion beam. Under the condition of ensuring that the full-scale output signal of the wind force sensing in the X direction is 100mV, the thickness of the device layer is as high as 62.5μm (that is, the thickness of the device layer can be greater than or equal to 50μm, preferably, greater than or equal to 60μm), so that the sensor has excellent structural strength and stability. By analyzing the stress state of the beam root, a new piezoresistive arrangement was designed to eliminate the influence of wind forces in the X and Y axis directions on wind force sensing in the Z axis direction, thereby improving the sensitivity of wind force sensing.

[0050] The following further explains how the piezoresistive MEMS three-dimensional wind field sensor proposed in the present invention can achieve decoupling of the X, Y, and Z axis wind forces in the sensing principle, and how the piezoresistive arrangement method eliminates the influence of the wind forces in the X and Y axis directions on the wind force sensing in the Z axis direction.

[0051] like Figure 5a , is a model diagram of the MEMS three-dimensional wind field sensor of the preferred embodiment of the present invention. The cilia are manufactured by ultra-precision 3D printing and fixed to the device by UV glue. The principle of the MEMS three-dimensional wind field sensor is: when the sensor is subjected to wind force in the X and Y directions, the cilia deflect in the corresponding direction, driving the cilia chassis and the sheet probe to deflect around the X-direction torsion beam and the Y-direction torsion beam respectively. Figure 5b and Figure 5c As shown in the figure, when the sensor is subjected to the wind force in the Z direction, the sheet probe moves along the Z axis and applies a torque to the middle position of one side of the stiffness block through the Y direction torsion beam, causing the stiffness block to deflect around the Z direction torsion beam as shown in the figure. Figure 5d As shown. When the torsion beams in three directions are twisted, stress is generated at the root of the torsion beams. The silicon-based piezoresistive stress sensor senses the magnitude of the tangential stress at the root of the torsion beams and outputs a voltage difference of the corresponding value, thereby constructing the relationship between the wind force magnitude and the electrical signal in the three directions of X, Y, and Z. By performing vector synthesis of the wind forces in the three directions, the real-time wind force magnitude and direction are calculated, and the wind field is sensed.

[0052] The MEMS three-dimensional wind field sensor provided by the present invention adopts a piezoresistive type, and in the structural design of the silicon-based piezoresistive stress sensor, a Wheatstone bridge is used as the basic circuit structure, such as Figure 6 As shown in the figure, four piezoresistors are connected end to end to form a square. They are placed at the position where the stress at the root of the torsion beam is the largest to obtain the highest sensitivity. The piezoresistors are at an angle of 45° to the axis of the torsion bar. A DC voltage V is applied to points a and b. cc , measure the voltage difference between points c and d as the output signal V out When the torsion beam is torsionally deformed, the root stress changes, causing the resistance of R1 and R4 to increase or decrease. The resistance of R2 and R3 changes in the opposite trend to that of R1 and R4. out When the beam bends, the resistance values ​​of R1 and R2 change the same, the resistance values ​​of R3 and R4 change the same, the voltages at points c and d are the same, V out Using this feature, the root stress can be effectively sensed, the wind force corresponding to the stress can be calculated, and the X and Y axes can be decoupled from each other. Figure 2 Points a, b, c, and d in each piezoresistive stress sensor in the MEMS three-dimensional wind field sensor are respectively Figure 6 Points a, b, c, and d in the figure correspond to each other.

[0053] In order to solve the problem that the X- and Y-axis wind direction input causes errors in the output of the Z-axis wind direction sensor, the present invention proposes a new type of piezoresistive layout. The Wheatstone bridge is still used in the circuit principle, but the upper and lower parts of the bridge are respectively arranged at the root positions of two diagonal Z-direction torsion beams among the four Z-direction torsion beams to balance the stress changes at the roots of the Z-direction torsion beams caused by the X-direction wind input. The specific principle is as follows: the cilia 10, the cilia chassis 20, the sheet probe 30 and the stiffness block 40 are connected to the fixed pile 50 by four Z-direction torsion beams 73 as an internal whole. When the internal whole is subjected to force, it is bound to cause stress changes at the connection with the outside (i.e., the Z-direction torsion beam 73). If only the stress change of one of the Z-direction torsion beams 73 is detected, it is impossible to determine whether the stress change is caused by the wind force in the X- and Y-axis directions or the wind force in the Z-direction. However, the wind force input in different directions of the X-, Y- and Z-axis causes different deformations of the four Z-direction torsion beams 73, such as Figure 7a , Figure 7b and Figure 7c They are respectively the deformation of the Z-direction torsion beam 73 when the wind directions of the X, Y and Z axes are input. By analyzing these three situations, the change of each piezoresistance in the Wheatstone bridge at the root of the four Z-direction torsion beams 73 can be obtained, as shown in FIG. Figure 8a , Figure 8b , Figure 8c As shown, the dotted rectangle represents the device, the large blue arrow in the center represents the movement of the cilia, the diamond edges at the four corners represent the piezoresistance at that position, and the arrows on the diamond edges represent the change of the piezoresistance. It can be seen that the piezoresistance in the elliptical circle has the same resistance change when the wind direction of the X and Y axes is input, and the resistance change is opposite when the wind direction of the Z axis is input. These four piezoresistances are connected to form a Wheatstone bridge, as shown Figure 8d As shown in the figure, for Z-direction wind force sensing, half of the Wheatstone bridge is placed in the ellipse in the upper right corner of the device, and the other half is placed in the ellipse in the lower left corner, and then the two parts are connected with a wire, so that V out The X and Y axis wind force input is zero, and the Z axis wind force input is normal. Therefore, the piezoresistive stress sensor of the entire device can be as follows Figure 2 In the layout design shown in the figure, each piezoresistive stress sensor is respectively arranged at the root of the torsion beam. For the piezoresistive stress sensor at the root of the torsion beam in the X and Y directions, the line connecting the two points a and b in the circuit is along the axis direction of the beam. For the piezoresistive stress sensor at the root of the torsion beam in the Z direction, the line connecting the two points a and b in the circuit is perpendicular to the axis direction of the beam. Figure 2 The middle color indicates the potential of the position, red represents high potential, and blue represents low potential. The layout of each piezoresistive stress sensor in the MEMS three-dimensional wind field sensor of the present invention can effectively realize the sensing function, complete the sensing decoupling of the X, Y, and Z three-axis wind force, and has high sensitivity.

[0054] The background section of the present invention may contain background information about the problem or environment of the present invention, rather than describing the prior art by others. Therefore, the content contained in the background section is not an admission by the applicant that the prior art is available.

[0055] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, in the absence of mutual contradiction, the technical personnel in this field can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope defined by the attached claims.

Claims

1. A MEMS three-dimensional wind field sensor, characterized in that: The invention comprises cilia, a cilia chassis, a sheet probe, a stiffness block, a fixed pile, an X-direction torsion beam, a Y-direction torsion beam, a Z-direction torsion beam and a piezoresistive stress sensor, wherein the cilia are fixedly connected to the cilia chassis, the cilia chassis is connected to the sheet probe through the X-direction torsion beam, the sheet probe is connected to the stiffness block through the Y-direction torsion beam, the stiffness block is connected to the fixed pile through the Z-direction torsion beam, wherein the piezoresistive stress sensors are respectively arranged on the X-direction torsion beam, the Y-direction torsion beam and the Z-direction torsion beam, and each piezoresistive stress sensor adopts a Wheatstone bridge circuit structure.

2. The MEMS three-dimensional wind field sensor according to claim 1, characterized in that: The X-direction torsion beam includes a first X-direction sub-twist beam and a second X-direction sub-twist beam, the Y-direction torsion beam includes a first Y-direction sub-twist beam and a second Y-direction sub-twist beam, the Z-direction torsion beam includes a first Z-direction sub-twist beam, a second Z-direction sub-twist beam, a third Z-direction sub-twist beam and a fourth Z-direction sub-twist beam, the first X-direction sub-twist beam and the second X-direction sub-twist beam are respectively connected between the two sides of the ciliary chassis in the Y direction and the sheet probe, the first Y-direction sub-twist beam and the second Y-direction sub-twist beam are respectively connected between the two sides of the sheet probe in the X direction and the stiffness block, and the first Z-direction sub-twist beam, the second Z-direction sub-twist beam, the third Z-direction sub-twist beam and the fourth Z-direction sub-twist beam are respectively connected between the four corners of the stiffness block and the fixed pile.

3. The MEMS three-dimensional wind field sensor according to claim 2, characterized in that: The piezoresistive stress sensor includes a first sub-piezoresistive stress sensor, a second sub-piezoresistive stress sensor, a third sub-piezoresistive stress sensor and a fourth sub-piezoresistive stress sensor, wherein the first sub-piezoresistive stress sensor is arranged on the first X-direction sub-torsion beam, the second sub-piezoresistive stress sensor is arranged on the first Y-direction sub-torsion beam, and the third sub-piezoresistive stress sensor and the fourth sub-piezoresistive stress sensor are respectively arranged on the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam.

4. The MEMS three-dimensional wind field sensor according to claim 3, characterized in that: The first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam are connected to two Z-direction torsion beams opposite to each other on the diagonal line of the stiffness block.

5. The MEMS three-dimensional wind field sensor according to claim 3, characterized in that: The first sub-piezoresistive stress sensor is arranged on the first X-direction sub-torsion beam at an end close to the sheet probe, the second sub-piezoresistive stress sensor is arranged on the first Y-direction sub-torsion beam at an end close to the stiffness block, and the third sub-piezoresistive stress sensor and the fourth sub-piezoresistive stress sensor are respectively arranged on the first Z-direction sub-torsion beam and the third Z-direction sub-torsion beam at ends close to the fixing pile.

6. The MEMS three-dimensional wind field sensor according to claim 3, characterized in that: The first piezoresistive stress sensor adopts a first Wheatstone bridge circuit structure, wherein four first piezoresistors of the first Wheatstone bridge circuit structure are connected end to end to form a first square, and each of the first piezoresistors is 45° to the axial direction of the first X-direction sub-torsion beam, wherein a DC voltage is applied between two points on the first square along a diagonal line of the axial direction of the first X-direction sub-torsion beam, and a voltage difference between two points on the first square along a diagonal line perpendicular to the axial direction of the first X-direction sub-torsion beam is measured as an X-direction output electrical signal.

7. The MEMS three-dimensional wind field sensor according to claim 3, characterized in that: The second piezoresistive stress sensor adopts a second Wheatstone bridge circuit structure, wherein four second piezoresistors of the second Wheatstone bridge circuit structure are connected end to end to form a second square, and each of the second piezoresistors is 45° to the axial direction of the first Y-direction sub-torsion beam, wherein a DC voltage is applied between two points on the second square along a diagonal line along the axial direction of the first Y-direction sub-torsion beam, and the voltage difference between the two points on the second square along a diagonal line perpendicular to the axial direction of the first Y-direction sub-torsion beam is measured as an output electrical signal in the Y direction.

8. The MEMS three-dimensional wind field sensor according to claim 3, characterized in that: The third piezoresistive stress sensor and the fourth piezoresistive stress sensor together form a third Wheatstone bridge circuit structure, wherein the third Wheatstone bridge circuit structure is composed of a third A piezoresistance, a third B piezoresistance, a third C piezoresistance and a third D piezoresistance, wherein the third A piezoresistance and the third B piezoresistance are respectively arranged at 45° to the axial direction of the first Z-direction sub-torsion beam and are interconnected on the first Z-direction sub-torsion beam, and the third C piezoresistance and the third D piezoresistance are respectively arranged at 45° to the axial direction of the third Z-direction sub-torsion beam and are interconnected on the third Z-direction sub-torsion beam, wherein a DC voltage is applied between the two ends of the interconnected third A piezoresistance and the three B piezoresistance and between the two ends of the interconnected third C piezoresistance and the three D piezoresistance, respectively; and a voltage difference between a first point where the third A piezoresistance and the third B piezoresistance intersect and a second point where the third C piezoresistance and the third D piezoresistance intersect is measured as a Z-direction output electrical signal.

9. The MEMS three-dimensional wind field sensor according to claim 8, characterized in that: The opening direction where the third A piezoresistance is connected to the third B piezoresistance and the opening direction where the third C piezoresistance is connected to the third D piezoresistance are respectively oriented toward the fixing pile.

10. The MEMS three-dimensional wind field sensor according to claim 1, characterized in that: The ciliary chassis, the sheet probe, the stiffness block, the fixing pile, the X-direction torsion beam, the Y-direction torsion beam, the Z-direction torsion beam and the piezoresistive stress sensor are arranged in the same plane, and the structure of each part is processed on a silicon wafer by photolithography, etching and ion implantation.

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