Multi-band piezoelectric bionic sound source localization sensor based on membrane bridge

Abstract

The present invention discloses a multi-band piezoelectric bionic sound source localization sensor based on an inter-membrane bridge, comprising an external diaphragm, an internal diaphragm, a piezoelectric film, a sensing electrode, an output electrode and a base, wherein both the external diaphragm and the internal diaphragm comprise two winglets of different sizes, and the external diaphragm is embedded in a hollowed-out base in the middle; the internal diaphragm is embedded in the hollowed-out structure of the large winglet of the external diaphragm, and the internal diaphragm and the external diaphragm are orthogonally embedded at 90°; there is a gap between the external diaphragm and the base, and between the external diaphragm and the internal diaphragm; the surfaces of the external diaphragm and the internal diaphragm are both deposited with piezoelectric films, sensing electrodes are deposited on the piezoelectric films, the piezoelectric films detect the displacement of the internal and external diaphragms, and the displacement of the diaphragms is converted into a voltage, and the voltage induced by the sensing electrode is connected to an external detection amplifier circuit by the output electrode. The present invention can realize multi-band acoustic sensing and broadband sound source localization, and is suitable for occasions with high requirements for size and positioning accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of sound source localization sensors, and in particular relates to a multi-band piezoelectric bionic sound source localization sensor based on an inter-membrane bridge. Background Art

[0002] Directional microphones have been studied since the 1930s, and with the increasing popularity of smartphones and other mobile devices and the focus on the development of miniaturized hearing aids, directional microphone manufacturers are focusing not only on their performance but also on their size and miniaturization potential. Therefore, the development of MEMS directional microphones has become a key area of ​​focus, which can achieve device miniaturization while providing high acoustic sensitivity and low noise. In order to increase the pressure gradient and improve the sensitivity of accurately locating the sound source, a series of directional MEMS microphones have been developed that mimic the membrane bridge structure in the hearing mechanism of the Omea palm fly. However, these previous designs only operate in no more than two frequency bands, and the operating frequency bands are few and narrow, which cannot achieve broadband sound source localization. In addition, most acoustic sensors based on the membrane bridge structure design use optical sensing or comb-tooth capacitance sensing. Among them, optical sensing has high sensitivity but cannot be miniaturized, and comb-tooth capacitance sensing is prone to initial position displacement of the comb teeth during processing, so it has low sensitivity and high noise. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a miniaturized and highly sensitive multi-band piezoelectric bionic sound source localization sensor based on membrane bridges.

[0004] Technical solution: The multi-band piezoelectric bionic sound source localization sensor based on the membrane bridge described in the present invention comprises: an external diaphragm, an internal diaphragm, a piezoelectric film, a sensing electrode, an output electrode and a base, the external diaphragm and the internal diaphragm each comprise two winglets of different sizes, the external diaphragm is embedded in the hollowed-out base in the middle and fixedly connected to the base; the internal diaphragm is embedded in the hollow structure of the large winglet of the external diaphragm, and the internal diaphragm and the external diaphragm are orthogonally embedded at 90° and fixedly connected; there are gaps between the external diaphragm and the base, and between the external diaphragm and the internal diaphragm; piezoelectric films are deposited on the surfaces of the external diaphragm and the internal diaphragm, and the displacements of the external diaphragm and the internal diaphragm are detected in the form of piezoelectric sensing, and the displacements of the external diaphragm and the internal diaphragm are converted into voltage quantities; sensing electrodes are deposited on the piezoelectric film for sensing voltage quantities, and the voltage quantities sensed by the sensing electrodes are connected to an external detection amplifier circuit by the output electrode. The external diaphragm and the internal diaphragm are orthogonally interlocked at 90°, which can not only realize the positioning of the pitch angle in the XZ plane, but also realize the positioning of the direction angle in the XY plane; by increasing the pressure difference between the wings on both sides of the internal diaphragm and the wings on both sides of the external diaphragm, the response of the sensor in the swing mode is improved.

[0005] Preferably, the external diaphragm is fixedly connected to the inner wall of the base through a pair of external diaphragm support beams, and the external diaphragm support beams are offset in the y-axis direction, so that the external diaphragm is divided into two parts, an external diaphragm small wing and an external diaphragm large wing, with the pair of external diaphragm support beams as the axis, wherein a hollow structure is provided on the external diaphragm large wing adjacent to the external diaphragm small wing.

[0006] Preferably, the external diaphragm support beam is offset from the center of the y-axis by 0.3 mm to 1 mm.

[0007] Preferably, the internal diaphragm includes an internal diaphragm small wing and an internal diaphragm large wing, and the internal diaphragm small wing and the internal diaphragm large wing are interconnected by a coupling bridge and a torsion beam with a hollow middle portion; the internal diaphragm is fixedly connected to the two wings of the external diaphragm through a coupling bridge and a pair of internal diaphragm support beams.

[0008] Preferably, both the external diaphragm and the internal diaphragm have two vibration modes, namely the rocking mode and the bending mode. In the rocking mode, the two wings of the external diaphragm vibrate in opposite phases, and the two wings of the internal diaphragm vibrate in opposite phases; in the bending mode, the two wings of the external diaphragm vibrate in the same phase, and the two wings of the internal diaphragm vibrate in the same phase.

[0009] Preferably, the sound source localization sensor includes four characteristic modes, the first characteristic mode is the rocking mode of the external diaphragm, and the main vibration is concentrated on the large wing of the external diaphragm; the second characteristic mode is the bending mode of the external diaphragm, and the main vibration is concentrated on the small wing of the external diaphragm; the third characteristic mode is the rocking mode of the internal diaphragm, and the main vibration is concentrated on the large wing of the internal diaphragm; the fourth characteristic mode is the bending mode of the internal diaphragm, and the main vibration is concentrated on the small wing of the internal diaphragm.

[0010] Preferably, in the four characteristic modes, the amplitudes of the internal diaphragm and the external diaphragm present a uniform cosine response curve along with the incident pitch angle of the sound source.

[0011] Preferably, the piezoelectric film is an aluminum nitride piezoelectric film, which adopts the d33 working mode; the sensing electrode is an interdigitated electrode made of aluminum material; when the piezoelectric film adopts the d33 working mode, the stress it is subjected to is consistent with the direction of the generated voltage, so depositing the sensing electrode on the piezoelectric film can convert the displacement change of the diaphragm into a voltage output. In the d31 mode, the sensing electrodes need to be deposited on the upper and lower surfaces of the piezoelectric film to output the voltage, and the output voltage is limited by the thickness of the piezoelectric film.

[0012] Preferably, the external diaphragm, the internal diaphragm and the base are all made by etching a single crystal silicon wafer using a micro-electromechanical system (MEMS) processing technology.

[0013] The positioning system of the present invention comprises the multi-band piezoelectric bionic sound source positioning sensor based on the membrane bridge.

[0014] Principle of the invention:

[0015] Traditional directional sound sensing systems use spatially separated microphone arrays to achieve directional sensing by monitoring the arrival time and amplitude of each microphone, and the directional accuracy is determined by the spatial separation of the microphones. In contrast, the ears of the Omya palm fly are only 500 microns apart, but even if the wavelength is two orders of magnitude larger than its auditory structure, it has a significant sensitivity to the direction of sound. The auditory system of the Omya palm fly is coupled to the eardrums on both sides by a special membrane bridge structure. This membrane bridge structure can amplify the amplitude difference and delay difference of the sound signals on both sides to determine the direction of the sound. The present invention is inspired by the membrane bridge coupling structure of the Omya palm fly and is a multi-band bionic sound source localization sensor designed to achieve multi-band sound sensing by using asymmetric wings to enhance the displacement amplitude in the swing mode and the form of internal and external mosaics.

[0016] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are: (1) by designing two groups of diaphragms of different sizes to be embedded inside and outside, the working frequency band can be effectively increased and miniaturization can be achieved; (2) by increasing the area of ​​one side wing of the internal diaphragm and offsetting the support beam of the external diaphragm, the displacement amplitude under the swing mode can be increased to achieve multi-band acoustic sensing; (3) the method of measuring the vibration displacement of the diaphragm by d33 mode aluminum nitride piezoelectric sensing has the advantages of high sensitivity and low noise; (4) by adjusting the structural size of the sensor sensitive unit, its modal frequency can be adjusted to improve its sensitivity within a certain frequency range; (5) the sensor is manufactured using micro-electromechanical system processing technology, and has the advantages of small size and miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a multi-band piezoelectric bionic sound source localization sensor based on an inter-membrane bridge in the present invention;

[0018] Figure 2 It is a front view of the sensor structure without piezoelectric film, sensing electrode and output electrode;

[0019] Figure 3 It is a partial view of the internal diaphragm;

[0020] Figure 4 It is a partial view of one side of the outer diaphragm winglet;

[0021] Figure 5 is a schematic diagram of the first characteristic mode;

[0022] Figure 6 is a schematic diagram of the second characteristic mode;

[0023] Figure 7 is the schematic diagram of the third characteristic mode;

[0024] Figure 8 is a schematic diagram of the fourth characteristic mode;

[0025] Fig. 9 This is the simulation diagram of the frequency response of the inner and outer diaphragms;

[0026] Fig.10 This is the polar coordinate response diagram of the diaphragm amplitude changing with the pitch angle of the incident sound at 400Hz;

[0027] Fig.11 This is the polar coordinate response diagram of the diaphragm amplitude changing with the pitch angle of the incident sound at 1000Hz;

[0028] Fig.12 This is the polar coordinate response diagram of the diaphragm amplitude changing with the pitch angle of the incident sound at 1400Hz;

[0029] Fig.13This is the polar coordinate response diagram of the diaphragm amplitude changing with the pitch angle of the incident sound at 2000Hz;

[0030] In the figure: 1. external diaphragm small wing, 2. external diaphragm large wing, 3. internal diaphragm small wing, 4. internal diaphragm large wing, 5. piezoelectric film, 6. sensing electrode, 7. output wire, 8. output electrode, 9. base, 10. external diaphragm support beam, 11. coupling bridge, 12. torsion beam, 13. internal diaphragm support beam. DETAILED DESCRIPTION

[0031] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0032] like Figure 1-3 As shown, a multi-band piezoelectric bionic sound source localization sensor based on an inter-membrane bridge described in the present invention includes: an external diaphragm, an internal diaphragm, a piezoelectric film 5, a sensing electrode 6, an output wire 7, an output electrode 8, a base 9, an external diaphragm support beam 10, a coupling bridge 11, a torsion beam 12 and an internal diaphragm support beam 13, the external diaphragm and the internal diaphragm are sound pressure gradient sensitive diaphragms, which serve as sensor sensitive units; the external diaphragm is embedded in the base 9 with a hollow middle, and is fixedly connected to the inner wall of the base 9 through a pair of external diaphragm support beams 10; the external diaphragm is divided into two parts, an external diaphragm small wing 1 and an external diaphragm large wing 2, with a pair of external diaphragm support beams 10 as the axis, wherein A hollow structure is provided on the outer diaphragm large wing piece 2 adjacent to the outer diaphragm small wing piece 1, the inner diaphragm is embedded in the hollow structure of the outer diaphragm large wing piece 2, and the inner diaphragm and the outer diaphragm are orthogonally embedded at 90°, and are respectively fixedly connected to the outer diaphragm small wing piece 1 and the outer diaphragm large wing piece 2 through a pair of inner diaphragm support beams 13; the inner diaphragm includes an inner diaphragm small wing piece 3 and an inner diaphragm large wing piece 4, the inner diaphragm small wing piece 3 and the inner diaphragm large wing piece 4 are interconnected through a coupling bridge 11 and a torsion beam 12 which are hollowed out in the middle, the coupling bridge 11 and the torsion beam 12 are equivalent to the membrane bridge structure in the auditory system of the Omea palm fly, so as to realize the special acoustic sensing characteristics of the Omea palm fly; Figure 3As shown, the internal diaphragm small wing 3 and the internal diaphragm large wing 4 are respectively connected to the coupling bridge 11 through a pair of torsion beams 12, and the external diaphragm small wing 1 and the external diaphragm large wing 2 are connected to the coupling bridge 11 through a pair of internal diaphragm support beams 13; there are gaps between the external diaphragm and the base 9 and between the external diaphragm and the internal diaphragm; the external diaphragm and the internal diaphragm are parallel to the upper surface of the base 9, and the external diaphragm support beam 10 is offset in the y-axis direction, so the areas of the two wings of the external diaphragm are not equal, and the area of ​​the external diaphragm large wing 2 is larger than the area of ​​the external diaphragm small wing 1; the areas of the two wings of the internal diaphragm are also not equal, and the area of ​​the internal diaphragm large wing 4 is larger than the area of ​​the internal diaphragm small wing 3. By increasing the area of ​​one side of the wing in the internal diaphragm and offsetting the external diaphragm support beam from the y-axis center, the pressure difference between the two sides of the inner and outer diaphragms is actively increased to improve the response of the sensor in the swing mode.

[0033] The larger the offset of the external diaphragm support beam 10 in the y-axis direction, the higher the response of the sound source localization sensor in the swing mode, and the two characteristic frequencies of the external diaphragm will change. The offset of the external diaphragm support beam is determined comprehensively based on the overall size of the external diaphragm. If the offset is too small, the response increase in the swing mode will be small. If the offset is too large, the bending mode characteristic frequency of the external diaphragm will be greater than the swing mode characteristic frequency of the internal diaphragm, that is, the order of the four characteristic frequencies described above is not satisfied. In this embodiment, the offset of the external diaphragm support beam of 0.3-1 mm is comprehensively determined based on the given "overall length of the external diaphragm is 5 mm to 8 mm, and the width is 4 mm to 6 mm".

[0034] The greater the difference between the areas of the two wings in the internal diaphragm, the greater the pressure difference between the wings on both sides, and the higher the response of the sound source localization sensor in the swing mode. The difference between the areas of the two wings in the internal diaphragm can be changed according to the target frequency.

[0035] Assume that the areas of the two wings on the inner diaphragm are equal, both , the sound is incident from the front of the diaphragm, and the force acting on the two wing surfaces due to the sound pressure is expressed in exponential form as and ,in, and are the forces exerted by the sound pressure on the surfaces of the two fins, and the subscripts 1 and 2 represent the physical quantities of the two fins, respectively. is the time delay of the sound wave reaching the two wings, is the sound pressure of the incident sound, is the frequency of the incident sound.

[0036] The displacement response of the two side wing pieces is analyzed by modal analysis, and the frequency response of the displacement of the two side wing pieces can be obtained. and for:

[0037] ,

[0038] ,

[0039] ,

[0040] in, is the rocking mode characteristic frequency, is the bending mode characteristic frequency, is the mass of a single wing, is the damping coefficient of the two side fins, is the damping coefficient of the coupling bridge and torsion beam connecting the two side wings, is the imaginary number symbol. Approaching When Proportional term drive; when Approaching When The angle between the incident sound and the diaphragm normal is , the distance between the centers of the two side wings is , is the speed of sound, time delay is equivalent to .because Very small, therefore:

[0041] ,

[0042] ,

[0043] Therefore, the displacement amplitudes of the two blades in the rocking mode are and the displacement amplitude in the bending mode for:

[0044] ,

[0045] ,

[0046] It can be concluded that the rocking mode is the result of the difference in sound pressure between the two wings, while the bending mode is driven by the sum of the sound pressure on both sides. This causes the displacement amplitude of the diaphragm in the bending mode to be much larger than that in the rocking mode. Therefore, in order to improve the response in the rocking mode, the pressure difference between the two wings is actively increased by increasing the area of ​​one wing in the inner diaphragm and offsetting the support beam of the outer diaphragm from the center of the y-axis to increase the response in the rocking mode.

[0047] The offset is related to the increase in displacement value and the characteristic frequency under the rocking mode. For the structure of the external diaphragm, changing the size of the wing pieces on both sides and the offset of the support beam are equivalent, and the offset of the support beam is more direct and convenient to implement. Therefore, the present invention realizes the different sizes of the wing pieces on both sides of the external diaphragm by offsetting the external diaphragm support beam.

[0048] The piezoelectric film 5 of d33 mode is deposited on the external diaphragm small wing 1, the external diaphragm large wing 2, the internal diaphragm small wing 3 and the internal diaphragm large wing 4 to sense the displacement change of the diaphragm; at the same time, the sensing electrode 6 is deposited on the piezoelectric film 5. When the piezoelectric film 5 adopts the d33 working mode, the stress it is subjected to is consistent with the direction of the generated voltage. Therefore, the sensing electrode 6 deposited on the piezoelectric film 5 can convert the displacement change of the diaphragm into a voltage output. In the d31 mode, the sensing electrodes need to be deposited on the upper and lower surfaces of the piezoelectric film 5 to output the voltage, and the output voltage is limited by the thickness of the piezoelectric film.

[0049] Furthermore, the outer diaphragm and the inner diaphragm are made of single crystal silicon material, the piezoelectric film 5 is made of aluminum nitride material, which is an aluminum nitride piezoelectric film, the sensing electrode 6 is an interdigital electrode made of aluminum material, and the base 9 is a silicon base.

[0050] like Figure 4 As shown, taking the area of ​​the external diaphragm winglet 1 as an example, aluminum nitride piezoelectric films are deposited on the surfaces of the two groups of diaphragms, and the diaphragm displacement is detected in the form of piezoelectric sensing, and the diaphragm displacement is converted into a voltage. Aluminum nitride has the advantages of low acoustic loss, dielectric loss and compatibility with CMOS circuits; the sensing electrode 6 made of aluminum material is deposited on the aluminum nitride piezoelectric film to sense the voltage. A pair of sensing electrodes is required on each wing to output positive and negative voltages, and is connected to the output electrode 8 through the output wire 7, and finally connected to the external detection amplifier circuit by the output electrode 8.

[0051] The main dimensional parameters of the sensor sensitive unit can be: the diaphragm thickness is 2 microns to 10 microns, the length of the large wing in the internal diaphragm is 1 mm to 2 mm, and the width is 1 mm to 1.5 mm; the length of the small wing in the internal diaphragm is 1 mm to 1.5 mm, and the width is 1 mm to 1.5 mm; the length of the internal diaphragm support beam is 0.2 mm to 0.5 mm, and the width is 0.1 mm to 0.3 mm; the overall length of the external diaphragm is 5 mm to 8 mm, and the width is 4 mm to 6 mm; the length of the external diaphragm support beam is 0.5 mm to 1 mm, the width is 0.2 mm to 0.4 mm, and the offset from the y-axis center is 0.3 mm to 1 mm; the length of the sensing electrode is 80 microns to 120 microns, the width is 15 microns to 25 microns, and the spacing between the sensing electrodes is 60 microns to 80 microns.

[0052] Specific options are: the thickness of the inner and outer diaphragms is 10 microns, the length of the large diaphragm in the internal diaphragm is 1.4 mm, and the width is 1 mm; the length and width of the small diaphragm in the internal diaphragm are both 1 mm; the length of the internal diaphragm support beam is 0.2 mm, and the width is 0.1 mm; the overall length of the external diaphragm is 5.5 mm, and the width is 4 mm; the length of the external support beam is 0.6 mm, the width is 0.2 mm, and it is offset from the center of the y-axis by 0.5 mm; the length of the sensing electrode is 90 microns, the width is 20 microns, and the spacing between the sensing electrodes is 70 microns.

[0053] Furthermore, the sensor sensitive unit and the base are both made by etching a single crystal silicon wafer using a micro-electromechanical system (MEMS) processing technology.

[0054] Furthermore, the inner and outer diaphragms both have two vibration modes, namely, a rocking mode and a bending mode. The two fins near the rocking mode vibrate in opposite phases, and the two fins near the bending mode vibrate in the same phase.

[0055] like Figures 5 to 8 The figure shows the vibration mode of the diaphragm. Both the external diaphragm and the internal diaphragm have two vibration modes: the rocking mode and the bending mode. In the rocking mode, the wings on both sides of the external diaphragm vibrate in opposite phases, and the wings on both sides of the internal diaphragm vibrate in opposite phases. In the bending mode, the wings on both sides of the external diaphragm vibrate in the same phase, and the wings on both sides of the internal diaphragm vibrate in the same phase. The displacement amplitudes of the external diaphragm and the internal diaphragm are respectively composed of the linear superposition of the two modes. Among them, Figure 5 The first characteristic mode is shown, which is the rocking mode of the external diaphragm, and the main vibration is concentrated on the large wing 2 of the external diaphragm; Figure 6 The second characteristic mode is shown, and the second characteristic mode is the bending mode of the external diaphragm, and the main vibration is concentrated on the small wing piece 1 of the external diaphragm; Figure 7 The third characteristic mode is shown, which is the rocking mode of the inner diaphragm, and the main vibration is concentrated on the inner diaphragm large wing 4; Figure 8 The fourth characteristic mode is shown. The fourth characteristic mode is the bending mode of the internal diaphragm, and the main vibration is concentrated on the small wing 3 of the internal diaphragm.

[0056] Fig. 9 This is a simulation diagram of the displacement amplitude frequency response of the diaphragm. It can be seen that the four characteristic frequencies of the diaphragm are evenly distributed below 2000Hz, which are around 400Hz, 1000Hz, 1400Hz and 2000Hz. At the first characteristic frequency, the displacement amplitude of the large diaphragm wing 2 is the largest; at the second characteristic frequency, the displacement amplitude of the small diaphragm wing 1 is the largest; at the third characteristic frequency, the displacement amplitude of the large diaphragm wing 4 is the largest; at the fourth characteristic frequency, the displacement amplitude of the small diaphragm wing 3 is the largest.

[0057] In order to verify the directivity of the sensor in the XZ plane, the incident azimuth angle of the sound source is set to 0°, the incident pitch angle of the sound source is changed, and it is rotated in the XZ plane to obtain the polar coordinate response diagram of the diaphragm amplitude changing with the incident pitch angle at different frequencies, as shown in Figures 10 to 13 It can be seen that under the four characteristic modes of the sensor, the amplitude of the inner and outer diaphragms presents a uniform cosine response curve with the incident pitch angle of the sound source, which has good directivity and broadband sound source localization capability for the sound source direction.

[0058] The multi-band piezoelectric bionic sound source localization sensor based on the membrane bridge of the present invention is inspired by the membrane bridge coupling mechanism of the auditory system of the Omea palm fly. By designing the two sets of diaphragms to be embedded inside and outside, increasing the area of ​​one side wing in the internal diaphragm and offsetting the external diaphragm support beam, the displacement amplitude of the two sets of diaphragms in the swing mode can be increased to achieve multi-band sound sensing. By designing the two sets of diaphragms to be placed orthogonally at 90°, not only the positioning of the pitch angle in the XZ plane can be achieved, but also the directional angle positioning of the XY plane can be achieved. By using the aluminum nitride piezoelectric film of the d33 mode to realize the sensing of the vibration displacement of the diaphragm, it has the advantages of high sensitivity and low noise. The sensor solves the problems of the single diaphragm bionic sound sensor based on the membrane bridge structure, such as the small response frequency band and small amplitude in the swing mode, and can achieve broadband sound source localization, which is suitable for occasions with high requirements on size and positioning accuracy.

[0059] The positioning system of the present invention comprises the multi-band piezoelectric bionic sound source positioning sensor based on the membrane bridge.

[0060] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A multi-band piezoelectric bionic sound source localization sensor based on a membrane bridge, characterized in that: The sensor comprises: an external diaphragm, an internal diaphragm, a piezoelectric film (5), a sensing electrode (6), an output electrode (8) and a base (9); the external diaphragm and the internal diaphragm each comprise two winglets of different sizes; the external diaphragm is embedded in the base (9) which is hollowed out in the middle and is fixedly connected to the base (9); the internal diaphragm is embedded in the hollow structure of the large winglet of the external diaphragm; the internal diaphragm comprises an internal diaphragm small winglet (3) and an internal diaphragm large winglet (4); the internal diaphragm small winglet (3) and the internal diaphragm large winglet (4) are connected to each other via a coupling bridge (11) and a torsion beam (12) which are hollowed out in the middle; the internal diaphragm is connected to the external diaphragm via the coupling bridge (11) and a pair of The internal diaphragm support beam (13) is respectively fixedly connected to the two wings of the external diaphragm, and the internal diaphragm and the external diaphragm are orthogonally interlocked at 90 degrees; there are gaps between the external diaphragm and the base (9), and between the external diaphragm and the internal diaphragm; piezoelectric film (5) is deposited on the surface of the external diaphragm and the internal diaphragm, and the piezoelectric film (5) adopts the d33 working mode to detect the displacement of the external diaphragm and the internal diaphragm in the form of piezoelectric sensing, and converts the displacement of the external diaphragm and the internal diaphragm into voltage; branch comb-shaped forked finger electrodes are deposited on the piezoelectric film (5) for sensing voltage, and the voltage sensed by the forked finger electrodes is connected to the external detection amplifier circuit by the output electrode (8).

2. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 1, characterized in that: The external diaphragm is fixedly connected to the inner wall of the base (9) by a pair of external diaphragm support beams (10), and the external diaphragm support beams (10) are offset in the y-axis direction, so that the external diaphragm is divided into two parts, namely, an external diaphragm small wing (1) and an external diaphragm large wing (2), with the pair of external diaphragm support beams (10) as the axis, wherein a hollow structure is provided on the external diaphragm large wing (2) adjacent to the external diaphragm small wing (1).

3. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 2, characterized in that: The external diaphragm support beam (10) is offset from the center of the y-axis by 0.3 mm to 1 mm.

4. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 1, characterized in that: Both the external diaphragm and the internal diaphragm have two vibration modes, namely the rocking mode and the bending mode. When the external diaphragm is in the rocking mode, its two wings vibrate in opposite phases, and when it is in the bending mode, its two wings vibrate in the same phase. When the internal diaphragm is in the rocking mode, its two wings vibrate in opposite phases, and when it is in the bending mode, its two wings vibrate in the same phase.

5. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 4, characterized in that: The sound source localization sensor comprises four characteristic modes, wherein the first characteristic mode is the rocking mode of the external diaphragm, and the main vibration is concentrated on the large wing piece (2) of the external diaphragm; the second characteristic mode is the bending mode of the external diaphragm, and the main vibration is concentrated on the small wing piece (1) of the external diaphragm; the third characteristic mode is the rocking mode of the internal diaphragm, and the main vibration is concentrated on the large wing piece (4) of the internal diaphragm; and the fourth characteristic mode is the bending mode of the internal diaphragm, and the main vibration is concentrated on the small wing piece (3) of the internal diaphragm.

6. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 5, characterized in that: In the four characteristic modes, the amplitudes of the external diaphragm and the internal diaphragm present a uniform cosine response curve along with the incident pitch angle of the sound source.

7. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 1, characterized in that: The piezoelectric film (5) is an aluminum nitride piezoelectric film; and the interdigital electrodes are made of aluminum material.

8. The multi-band piezoelectric bionic sound source localization sensor based on membrane bridge according to claim 1, characterized in that: The outer diaphragm, inner diaphragm and base are all made by etching single crystal silicon wafers using the micro-electromechanical system (MEMS) processing technology.

9. A positioning system, characterized in that: A multi-band piezoelectric bionic sound source localization sensor based on an inter-membrane bridge as described in any one of claims 1 to 8.

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