acceleration sensing device

Abstract

A sensing device (200, 250, 900, 1000) comprising an acceleration sensor (100) having a first resonant frequency, the acceleration sensor (100) comprising a housing (110, 610) and a sensing element (120, 400, 500, 600, 800, 910, 1010), the sensing element (120, 400, 500, 600, 800, 910, 1010) being located within a cavity (610) formed by the housing (110, 610); and at least one resonant system (210, 260) coupled to the sensing element (120, 400, 500, 600, 800, 910, 1010), wherein the at least one resonant system (210, 260) provides the sensing device (200, 250, 900, 1000) with at least one second resonant frequency, the at least one second resonant frequency being the same or different from the first resonant frequency.

Description

[0001] Cross-references

[0002] This application claims priority to Chinese patent application No. 202110445739.3 filed on April 23, 2021, the entire contents of which are incorporated into this application by reference. Technical Field

[0003] The present application relates to a sensing device, and in particular to an acceleration sensing device. Background Art

[0004] For an acceleration sensor (for example, a capacitive, piezoelectric or piezoresistive acceleration sensor), when subjected to an external force or external acceleration with a frequency close to its natural resonant frequency, a larger amplitude will be generated, thereby outputting a larger electrical signal. Therefore, its response to the external force or external acceleration will be manifested as a resonance peak in the frequency response curve near the resonant frequency. Near the resonant frequency, its sensitivity is higher, while the sensitivity at other frequencies is lower, resulting in a higher quality factor Q value and unstable output gain. At the same time, in the working state, the acceleration sensor is often subjected to a large external impact. When the external impact load is high, it may cause damage to the internal components of the acceleration sensor. Therefore, it is hoped to provide an acceleration sensor device that can adjust the quality factor Q value of the device, improve the sensitivity of the device, have a stable output gain, and improve impact resistance reliability. Summary of the Invention

[0005] An embodiment of the present application provides a sensing device. The sensing device includes: an acceleration sensor having a first resonant frequency, the acceleration sensor including a housing and a sensing element, the sensing element being located within a cavity formed by the housing; and at least one resonant system coupled to the sensing element, wherein the at least one resonant system provides the sensing device with at least one second resonant frequency, the at least one second resonant frequency being the same as or different from the first resonant frequency.

[0006] In some embodiments, the sensing element includes: a substrate; a mass element that moves relative to the substrate in response to external acceleration, and at least one movable electrode is provided on the mass element; and at least one fixed electrode fixed on the substrate, and the at least one movable electrode and the at least one fixed electrode constitute at least one detection capacitor for determining the magnitude of the external acceleration.

[0007] In some embodiments, the at least one moving electrode comprises: at least one set of first moving electrodes arranged along a first direction and perpendicular to the first direction, each set of first moving electrodes comprising one or more first moving electrodes; and at least one set of second moving electrodes arranged along a second direction and perpendicular to the second direction, each set of second moving electrodes comprising one or more second moving electrodes; the at least one fixed electrode comprises: a first fixed electrode arranged parallel to and opposite to each first moving electrode, the at least one set of first moving electrodes and the corresponding first fixed electrode forming a first direction detection capacitor; and a second fixed electrode arranged parallel to and opposite to each second moving electrode, the at least one set of second moving electrodes and the corresponding second fixed electrode forming a second direction detection capacitor, the at least one set of first moving electrodes and the at least one set of second moving electrodes and the corresponding first fixed electrode and second fixed electrode forming a third direction detection capacitor.

[0008] In some embodiments, the second direction is perpendicular to the first direction.

[0009] In some embodiments, the at least one set of first moving electrodes comprises an even number of first moving electrodes, the even number of first moving electrodes being located on both sides of the mass element along the first direction; and the at least one set of second moving electrodes comprises an even number of second moving electrodes, the even number of second moving electrodes being located on both sides of the mass element along the second direction.

[0010] In some embodiments, each set of first moving electrodes is provided with a first moving electrode shaft along the first direction and a first fixed moving electrode perpendicular to the first direction, the first moving electrode shaft and the first fixed moving electrode being connected to the substrate by a first elastic element; each set of second moving electrodes is provided with a second moving electrode shaft along the second direction and a second fixed moving electrode perpendicular to the second direction, the second moving electrode shaft and the second fixed moving electrode being connected to the substrate by a second elastic element, the sensing device further comprising: for each set of first moving electrodes, a pair of first fixed electrode shafts symmetrically arranged opposite to the first direction and a pair of first fixed fixed electrodes perpendicular to the first direction, the first moving electrode shaft of each set of first moving electrodes being clamped between the pair of first fixed electrode shafts and the first fixed moving electrode being clamped between the pair of first fixed fixed electrodes; and for each set of second moving electrodes, a pair of second fixed electrode shafts symmetrically arranged opposite to the second direction and a pair of second fixed fixed electrodes perpendicular to the second direction, the second moving electrode shaft of each set of second moving electrodes being clamped between the pair of second fixed electrode shafts and the second fixed moving electrode being clamped between the pair of second fixed fixed electrodes.

[0011] In some embodiments, a pair of first fixed electrodes and a pair of first fixed electrodes form a triangular region with respect to each set of first fixed electrodes; a pair of second fixed electrodes and a pair of second fixed electrodes form a triangular region with respect to each set of second fixed electrodes.

[0012] In some embodiments, the first fixed electrodes and the second fixed electrodes are parallel to each other and have a certain distance.

[0013] In some embodiments, each first fixed electrode has a first fixed electrode top surface and a first fixed electrode bottom surface, each second fixed electrode has a second fixed electrode top surface and a second fixed electrode bottom surface, the first fixed electrode top surface is farther away from the top surface of the mass element than the second fixed electrode top surface.

[0014] In some embodiments, the first fixed electrode top surface and the second fixed electrode top surface have the same horizontal height.

[0015] In some embodiments, the sensing element further comprises a first support member fixed on the substrate, the mass element is connected to the first support member through an elastic connecting unit, the first support member is located at the center of the mass element, the elastic connecting unit extends along a first direction, the center line of the elastic connecting unit coincides with the center line of the mass element in the first direction, and in a second direction, the mass of the portions of the mass element on both sides of the elastic connecting unit are not equal, wherein the at least one fixed electrode comprises at least two first direction fixed electrodes, at least two second direction fixed electrodes extending along the first direction, the second direction fixed electrodes are located on the center line of the mass element in the second direction and are symmetrical with respect to the first support member, and at least two third direction fixed electrodes arranged on both sides of the elastic connecting unit, the at least one moving electrode comprises first direction moving electrodes, second direction moving electrodes and third direction moving electrodes corresponding to the at least two first direction fixed electrodes, the at least two second direction fixed electrodes and the at least two third direction fixed electrodes respectively, and the first direction moving electrodes, the second direction moving electrodes and the third direction moving electrodes form first direction detection capacitors, second direction detection capacitors and third direction detection capacitors respectively.

[0016] In some embodiments, the at least two first-direction fixed electrodes extend along a second direction, and are distributed on two sides of a substrate position corresponding to a center line of the mass element along the second direction, and are symmetric with respect to an axis of the center line along the second direction or symmetric with respect to a center of the first support component.

[0017] In some embodiments, the at least two first-direction fixed electrodes are not on a center line of the mass element along a first direction.

[0018] In some embodiments, each first-direction fixed electrode comprises two first-direction fixed electrode units arranged in parallel, a first-direction moving electrode corresponding to the first-direction fixed electrode comprises two first-direction moving electrode units, and the two first-direction fixed electrode units and the two first-direction moving electrode units form a first-direction differential capacitor structure; each second-direction fixed electrode comprises two second-direction fixed electrode units arranged in parallel, a second-direction moving electrode corresponding to the second-direction fixed electrode comprises two second-direction moving electrode units, and the two second-direction fixed electrode units and the two second-direction moving electrode units form a second-direction differential capacitor structure.

[0019] In some embodiments, the at least two first-direction fixed electrodes are on a center line of the mass element along a first direction.

[0020] In some embodiments, each first-direction fixed electrode comprises two first-direction fixed electrode units arranged in parallel, a first-direction moving electrode corresponding to the first-direction fixed electrode comprises two first-direction moving electrode units, and the two first-direction fixed electrode units and the two first-direction moving electrode units form a first-direction differential capacitor structure; each second-direction fixed electrode comprises two second-direction fixed electrode units arranged in parallel, a second-direction moving electrode corresponding to the second-direction fixed electrode comprises two second-direction moving electrode units, and the two second-direction fixed electrode units and the two second-direction moving electrode units form a second-direction differential capacitor structure, wherein a first-direction fixed electrode unit on one side of at least one first-direction fixed electrode of the at least two first-direction fixed electrodes is electrically connected to a first-direction fixed electrode unit on an opposite side of another first-direction fixed electrode symmetric with respect to the at least one first-direction fixed electrode with respect to an axis of a center line of the mass element along a second direction.

[0021] In some embodiments, the at least two third-direction fixed electrodes are lower electrodes of the at least two third-direction detection capacitors respectively, and the at least two third-direction moving electrodes are upper electrodes of the at least two third-direction detection capacitors respectively.

[0022] In some embodiments, one side of the mass element is provided with a weight-reducing hole or a counterweight, so that the masses on two sides of the mass element are not equal.

[0023] In some embodiments, the sensing element further comprises a second support member fixed to the substrate, the mass member is connected to the substrate through the second support member, the at least one fixed electrode comprises a coupling member, the coupling member surrounds the mass member and is provided with a gap between the coupling member and the mass member, and the at least one detection capacitor is formed.

[0024] In some embodiments, the substrate is made of silicon, and the second support member, the mass member and the coupling member are made of doped silicon.

[0025] In some embodiments, the sensing device further comprises an integrated chip, the integrated chip is electrically connected to the second support member and the coupling member, respectively.

[0026] In some embodiments, the integrated chip is located on the outer surface of the housing, the housing is provided with a through hole, and a conductive element passes through the through hole to connect the integrated chip with the second support member and the coupling member.

[0027] In some embodiments, the mass member comprises a first mass member and a second mass member, the sensing device further comprises a first fixing member connected to the substrate and surrounding the first mass member, the first fixing member is connected to the first mass member through at least one first flexible member, the second mass member surrounds the first fixing member, and a second fixing member connected to the substrate and surrounding the second mass member, the second fixing member is connected to the second mass member through at least one second flexible member, the at least one movable electrode comprises a plurality of first movable electrodes arranged inside the second mass member and extending inwardly, the plurality of first movable electrodes are distributed at least along a first direction and a second direction, and a second movable electrode arranged at the bottom of the first mass member, the at least one fixed electrode comprises a plurality of first fixed electrodes arranged at the periphery of the first fixing member and extending outwardly, the plurality of first fixed electrodes are arranged correspondingly and spaced apart from the plurality of first movable electrodes to form first and second direction detection capacitors, and a second fixed electrode arranged on the substrate to form a third direction detection capacitor with the second movable electrode.

[0028] In some embodiments, a plurality of holes are arranged on the first mass member and / or the second mass member.

[0029] In some embodiments, at least one of the first mass member, the second mass member, the first fixing member or the second fixing member has a square profile.

[0030] In some embodiments, the at least one resonant system comprises a first resonant system, and the first resonant system is a spring-mass-damper system.

[0031] In some embodiments, the first resonant system is composed of a first medium, the first medium fills the cavity, the acceleration sensing element is immersed in the first medium.

[0032] In some embodiments, the first medium is a liquid, the liquid includes at least one of silicone oil, glycerin, engine oil, lubricating oil, hydraulic oil.

[0033] In some embodiments, the first resonant system is at least one first elastic structure connected to the acceleration sensing element, the first elastic structure includes an elastic component and a mass unit.

[0034] In some embodiments, the at least one resonant system includes a second resonant system, the second resonant system is a combination of a spring-mass-damping system and a spring-damping system.

[0035] In some embodiments, the second resonant system is composed of a first medium and a second medium, the first medium and the second medium fill the cavity, the acceleration sensing element is at least partially immersed in the first medium and / or the second medium.

[0036] In some embodiments, the first medium is a liquid, the second medium is a gas, the gas is distributed in the liquid in the form of bubbles.

[0037] In some embodiments, the size of the bubbles accounts for 30%-50% of the volume of the cavity.

[0038] In some embodiments, the bubbles can be formed by at least one of air not discharged from the cavity, an air bag, or a hydrophobic material.

[0039] In some embodiments, the first medium and the second medium are liquids with different properties and are not mutually soluble.

[0040] In some embodiments, the second resonant system includes at least one second elastic structure connected to the acceleration sensing element, the second elastic structure includes a first elastic structure and at least one lightweight elastic component. BRIEF DESCRIPTION OF DRAWINGS

[0041] The present application will be further illustrated in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, the same numbers represent the same structures, wherein:

[0042] Figure 1 is a schematic diagram of an exemplary acceleration sensor 100 provided according to some embodiments of the present application.

[0043] Figure 2A is a mechanical equivalent schematic diagram of an exemplary sensing device 200 according to some embodiments of the present application.

[0044] Figure 2B is a schematic diagram of a sensing device 200 filled with liquid inside according to some embodiments of the present application.

[0045] Figure 2C is a mechanical equivalent schematic diagram of an exemplary sensing device 250 according to some embodiments of the present application.

[0046] Figure 2D is a schematic diagram of a sensing device 250 filled with liquid and air bubbles inside according to some embodiments of the present application.

[0047] Figure 3A is an exemplary frequency response curve of a sensing device 200 or 250 according to some embodiments of the present application.

[0048] Figure 3B is an exemplary frequency response curve of a sensing device 200 or 250 according to some embodiments of the present application.

[0049] Figure 3C is an exemplary frequency response curve of a sensing device 200 or 250 according to some embodiments of the present application.

[0050] Figure 4A and 4B is an exemplary structural schematic diagram of a sensing element 400 according to some embodiments of the present application.

[0051] Figures 5A-5D is an exemplary structural schematic diagram of a sensing element 500 according to some embodiments of the present application.

[0052] Figures 6A-6E is an exemplary structural schematic diagram of a sensing element 600 according to some embodiments of the present application.

[0053] Figure 7A is an exemplary flow of a method for manufacturing an acceleration sensor comprising a sensing element 600 according to some embodiments of the present application.

[0054] Figure 7B is an exemplary flow of a method for manufacturing an acceleration sensor comprising a sensing element 600 according to some other embodiments of the present application.

[0055] Figure 7C is an exemplary flow of a method for manufacturing an acceleration sensor comprising a sensing element 600 according to yet some other embodiments of the present application.

[0056] Figure 8Aand 8B is an exemplary structural schematic diagram of a sensing element 800 provided according to some embodiments of the present application.

[0057] Figure 9 is an exemplary structural schematic diagram of a sensing device 900 provided according to some embodiments of the present application.

[0058] Figure 10 is an exemplary structural schematic diagram of a sensing device 1000 provided according to some embodiments of the present application. DETAILED DESCRIPTION

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some examples or embodiments of the present application, and for those skilled in the art, the present application can be applied to other similar scenarios without creative labor on the basis of these drawings. Unless it is clear from the language context or otherwise indicated, the same reference numbers in the drawings represent the same structure or operation.

[0060] It should be understood that the "system", "device", "unit" and / or "module" used herein is a method for distinguishing different components, elements, parts, sections or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0061] As shown in the present application and claims, unless the context clearly indicates otherwise, the words "one", "a", "an", and / or "the" do not necessarily refer to the singular, but can also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements.

[0062] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or subsequent operations are not necessarily performed in sequence. On the contrary, each step can be processed in reverse order or simultaneously. At the same time, other operations can be added to these processes, or one or more steps of operation can be removed from these processes.

[0063] An acceleration sensing device (hereinafter referred to as a sensing device) is provided in embodiments of the present specification. The sensing device includes an acceleration sensor and at least one resonant system coupled with the acceleration sensor. The sensor can be a capacitive acceleration sensor, i.e., a variable-capacitance acceleration sensor. The acceleration sensor can have a first resonant frequency related to the properties (e.g., shape, size, structure, material, etc.) of the acceleration sensor itself. The at least one resonant system can be formed by a solid structure, a liquid, a gas, or any combination thereof coupled with the acceleration sensor (e.g., the moving electrode). For example, the cavity of the acceleration sensor can be filled with a liquid. The liquid and the gas (if any) in the cavity affect the response of the acceleration sensor to an external acceleration signal, forming the at least one resonant system. For another example, the acceleration sensor (e.g., the moving electrode) can be connected with a vibration assembly composed of an elastic component and a mass unit (e.g., a mass block), which affects the response of the acceleration sensor to an external acceleration signal, forming the at least one resonant system. The at least one resonant system can provide the sensing device with at least one second resonant frequency in addition to the first resonant frequency. The at least one second resonant frequency is different from the first resonant frequency. By adjusting the parameters (e.g., liquid viscosity, bubble size, etc.) of the acceleration sensor (e.g., the housing and / or the sensing element) and / or the substance / structure forming the at least one resonant system, the relationship between the first resonant frequency and the at least one second resonant frequency can be changed, so as to achieve the purposes of, for example, adjusting the Q value of the sensing device, improving the sensitivity of the sensing device, improving the reliability of the sensing device, or making the output gain of the sensing device more stable in a desired frequency band (e.g., low frequency).

[0064] Figure 1 FIG. 1 is a schematic diagram of an exemplary acceleration sensor 100 according to some embodiments of the present application.

[0065] The acceleration sensor 100 can be a capacitive acceleration sensor, a piezoelectric acceleration sensor, a piezoresistive acceleration sensor, etc. By way of example only, the acceleration sensor 100 is described herein with reference to a capacitive acceleration sensor, and is not limited thereto. The acceleration sensor includes a housing and an acceleration sensing element. The acceleration sensing element is located in a cavity formed by the housing. The acceleration sensing element includes at least one electrode pair. Each electrode pair includes a fixed electrode and a moving electrode, thereby forming a capacitor. In response to an external acceleration signal, the moving electrode is displaced relative to the fixed electrode, so that the distance and / or the facing area between the fixed electrode and the moving electrode are changed, thereby changing the capacitance of the capacitor. The change in capacitance causes the amount of electricity stored in the capacitor to change, thereby generating a measurable current signal.

[0066] For example, Figure 1 As shown, the acceleration sensor 100 includes a housing 110 and a sensing element 120. The housing 110 can be a regular or irregular three-dimensional structure with a cavity (i.e., a hollow portion) within. For example, it can be a hollow frame structure, including but not limited to regular shapes such as a cube, sphere, cylinder, regular polyhedron, or any irregular shape. The housing 110 is used to accommodate the sensing element 120. The housing 110 can be made of metal (e.g., stainless steel, copper), plastic (e.g., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS)), inorganic non-metallic materials (e.g., single crystal silicon, doped silicon), composite materials (e.g., metal-based composite materials or non-metal-based composite materials), etc. In some embodiments, the housing 110 is made of silicon. The sensing element 120 can be located in the cavity of the housing 110 or at least partially suspended in the cavity of the housing 110. The sensing element 120 includes a mass element 121 (e.g., a mass block). The mass element 121 may be in a shape such as a cube, a cuboid, a cylinder, or a ring. This is not specifically limited in the present application. The mass element 121 is disposed on an elastic film 124. The elastic film 124 may be a polymer elastic film such as a polytetrafluoroethylene (PTFE) film or a polydimethylsiloxane (PDMS) film, or a composite film (e.g., a plastic film (such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyester (PET)), cellophane, paper, and / or metal foil AL).

[0067] The mass element 121 includes upper and lower surfaces. The upper and lower surfaces are respectively provided with electrodes 122 and 123. For example, the upper and lower surfaces of the mass element 121 are respectively coated with conductive layers to form the electrodes 122 and 123. For another example, the upper and lower surfaces of the mass element 121 are respectively connected with conductive layers to form the electrodes 122 and 123. Exemplary conductive layers can include metals, alloy materials, metal oxide materials, graphene, silicon, etc., or any combination thereof. In some embodiments, the metals and alloy materials can include nickel, iron, lead, platinum, titanium, copper, molybdenum, zinc, or any combination thereof. In some embodiments, the alloy materials can include copper-zinc alloy, copper-tin alloy, copper-nickel-silicon alloy, copper-chromium alloy, copper-silver alloy, etc., or any combination thereof. In some embodiments, the metal oxide materials can include RuO2, MnO2, PbO2, NiO, etc., or any combination thereof. The "connection" described in the present application can be understood as the connection between different parts of the same structure, or after separately preparing different components or structures, the independent components or structures are fixedly connected by welding, riveting, clamping, bolting, adhesive bonding, etc., or in the preparation process, the first component or structure is deposited on the second component or structure by physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition).

[0068] Correspondingly, the upper and lower inner walls of the shell 110 are respectively provided with electrodes 125 and 126. The electrodes 125 and 126 can be respectively arranged opposite to the electrodes 122 and 123. In some embodiments, the shape and / or size of the electrodes 125 and 126 can be the same as or similar to those of the electrodes 122 and 123. The arrangement of the electrodes 125 and 126 can be the same as or different from that of the electrodes 122 and 124. For example, the conductive layers are generated on the upper and lower inner walls of the shell 110 by physical growth to form the electrodes 125 and 126. The materials of the electrodes 125 and 126 can be the same as or different from those of the electrodes 122 and 124. For example, the electrodes 122, 123, 125 and 126 can all adopt a certain metal material. The electrode 125 and the electrode 122 constitute two poles of a first capacitor, and the electrode 126 and the electrode 123 constitute two poles of a second capacitor.

[0069] When an acceleration signal (e.g., an acceleration signal along the vertical direction in the figure) exists outside, the mass element 121 disposed on the elastic diaphragm 124 vibrates along the direction of the acceleration signal. For example, when the mass element 121 moves upward, the distance between the electrode 125 and the electrode 122 constituting the first capacitor decreases, and the capacitance becomes larger; the distance between the electrode 126 and the electrode 123 constituting the second capacitor increases, and the capacitance becomes smaller, thereby forming a differential capacitance output signal. At the same time, the greater the amplitude of the acceleration signal (i.e., the greater the acceleration), the greater the displacement of the mass element 121, the smaller the distance between the electrode 125 and the electrode 122 of the first capacitor, the greater the capacitance; the greater the distance between the electrode 126 and the electrode 123 of the second capacitor, the smaller the capacitance, and the greater the amplitude of the differential capacitance output signal. Therefore, it can be seen that the differential capacitance output signal is proportional to the size of the acceleration signal. Therefore, the differential capacitance output signal generated by the acceleration sensor 100 can represent the size of the external acceleration signal.

[0070] It should be noted that the above description of the acceleration sensor 100 is for the convenience of description, and cannot limit the application to the scope of the embodiments. It can be understood that, for those skilled in the art, after understanding the principle of the system, various devices / modules can be combined or connected with other devices / modules to form a subsystem without departing from the principle. For example, the mass element 121 and the elastic diaphragm 124 in the sensing element 120 can be replaced by a vibrating rod (e.g., a cantilever beam). The vibrating rod can be a strip or plate structure, one end of which is connected to the upper and lower inner walls or side walls of the shell 110, and the other end is not connected or in contact with the shell 110, so that the other end is suspended in the cavity of the shell 110. In some embodiments, the vibrating rod is a multi-layer structure. The multi-layer structure includes at least one elastic layer and at least one damping layer. The damping layer can refer to a structure with damping properties. The upper and lower surfaces of the vibrating rod are respectively provided with the electrodes 122 and 123. When an external acceleration exists, the shell 110 drives the vibrating rod to move, and because the properties of the vibrating rod and the shell 110 are different, the vibrating rod and the shell 110 cannot maintain consistent movement, thereby generating relative movement, and further changing the distance between the vibrating rod and the upper and lower inner walls of the shell 110, so that the capacitances of the first capacitor and the second capacitor change, and a differential capacitance output signal is generated.

[0071] Figure 2A is a mechanical equivalent schematic diagram of an exemplary sensing device 200 according to some embodiments of the application.

[0072] The sensing device 200 includes the acceleration sensor 100 and a first resonant system 210. In some embodiments, the sensing device 200 can be considered as adding the first resonant system 210 to the acceleration sensor 100. For example, in the present embodiment, the first resonant system 210 can be a spring (Km4)-mass (Mm4)-damping (Rm4) system. For example only, in the case of a cantilever beam acceleration sensor, the first resonant system 210 can be coupled between the housing 110 and the sensing element 120. As a result of the first resonant system 210, when the housing 110 receives an external vibration signal, the external vibration signal will be transmitted to the sensing element 120 through both the housing region connected to the sensing element 120 and the housing region connected to the first resonant system 210. Thus, the mechanical response of the sensing device 200 is changed from that of the acceleration sensor 100. Accordingly, the electrical, acoustic, and / or thermal response of the sensing device 200 is changed from that of the acceleration sensor 100.

[0073] In some embodiments, the first resonant system 210 can be formed by an elastic structure (e.g., an elastic rod, an elastic sheet, an elastic block, an elastic net-like support, a composite structure of an elastic connecting structure (e.g., a light spring) and a mass element (e.g., a mass block), etc.) having a mass connected to the sensing element 120. For example, the first resonant system 210 can include at least one elastic rod. The two ends of the at least one elastic rod are fixedly connected to the housing 110 and the sensing element 120, respectively. For another example, the first resonant system 210 can be a combination of at least one set of elastic connecting structures (e.g., a light spring, a light elastic rod, etc.) and a mass element. The two ends of each elastic connecting structure in the at least one set of elastic structures are connected to the housing 110 and the mass element, respectively. The mass element is fixedly connected to or placed in the sensing element 120. In some embodiments, the first resonant system 210 can also be integrally formed with the sensing element 120. For example, the first resonant system 210 in the form of an elastic rod can be integrally formed with the sensing element 120 by injection molding or physical growth.

[0074] In some embodiments, the first resonant system 210 can be formed by filling a liquid into the cavity of the acceleration sensor 100. For example, the liquid fills the cavity in the housing 110, and the sensing element 120 is wrapped in the liquid. Figure 2BFIG. 1 is a schematic diagram of an internal liquid-filled sensing device 200 according to some embodiments of the present application. The liquid can be selected from liquids with safety properties (e.g., non-flammable and non-explosive), stability properties (e.g., non-volatile, non-degradation at high temperature, etc.). For example, the liquid can include oil (e.g., silicone oil, glycerin, castor oil, motor oil, lubricating oil, hydraulic oil (e.g., aviation hydraulic oil), etc.), water (including pure water, aqueous solution of other inorganic or organic substances (e.g., saline), etc.), oil-water emulsion, or other liquid that meets the performance requirements thereof, or a combination of one or more thereof.

[0075] The density and kinematic viscosity of the liquid are within a certain density range and kinematic viscosity range, respectively. In some embodiments, the density range and kinematic viscosity range can be set by a user or determined based on the performance (e.g., sensitivity, noise floor level, peak-to-peak value of resonance, frequency range of resonance, peak-to-valley value, and / or quality factor Q, etc.) of the sensing device 200. In some embodiments, the liquid can be selected from silicone oil. Silicone oil has the characteristics of high temperature resistance, non-volatility, wide viscosity range, etc., and has a density of about 0.94 kg / m3. The kinematic viscosity range of the optional silicone oil is relatively wide (e.g., 0.1-1000 centistokes (cst)).

[0076] In some embodiments, the frequency response curve of the sensing device 200 includes at least two resonance peaks. The at least two resonance peaks include a first resonance peak and a second resonance peak. The first resonance peak is a resonance peak corresponding to the acceleration sensor 100, and the corresponding resonance frequency is mainly related to the properties (e.g., shape, material, structure, etc.) of the sensing element 120. The second resonance peak is a resonance peak generated by the additional system (for the sensing device 200, the additional system is the first resonant system 210) of the acceleration sensor 100, and the corresponding resonance frequency is mainly related to one or more mechanical parameters (e.g., equivalent spring (Km4), mass (Mm4), damping (Rm4), etc.) of the additional system. In order to make the sensing device 200 applicable to different scenarios, the resonance frequency corresponding to the first resonance peak (also called the first resonance frequency) and the resonance frequency corresponding to the second resonance peak (also called the second resonance frequency) can satisfy different relationships. For example, the second resonance frequency can be less than, equal to, or greater than the first resonance frequency.

[0077] For the purpose of illustration, due to the existence of the second resonance peak corresponding to the first resonant system 210, the frequency response curve of the sensing device 200 in a certain frequency band (e.g., low-mid frequency band, high-mid frequency band, etc.) will be improved, so that the sensitivity of the sensing device 200 will be improved compared with the acceleration sensor 100. In addition, due to the effect of the first resonant system 210 on the sensing element 120, the vibration characteristics of the acceleration sensor 100 will be changed compared with the case without the first resonant system 210. Specifically, the first resonant system 210 acting on the sensing element 120 can affect the mass, stiffness and / or damping of the acceleration sensor 100, and the effect is equivalent to changing (e.g., reducing) the Q value of the first resonance peak of the sensing device 200 relative to the Q value of the acceleration sensor 100 without the first resonant system 210. For more specific description of the frequency response curve of the sensing device 200 and the first resonance peak and the second resonance peak, reference can be made to other places in the specification of the present application, for example Figure 3A and Figure 3B and the description thereof.

[0078] Meanwhile, the first resonant system 210 can reduce the external impact received by the sensing element to protect the sensing element. For example, if the first resonant system 210 is a liquid filling the cavity of the acceleration sensor 100, due to the viscous effect of the liquid and the small stiffness of the liquid relative to the material of the device, when the sensing device 200 receives an external impact load, the first resonant system 210 can improve the impact resistance reliability of the sensing device 200. Specifically, due to the viscous effect of the liquid, part of the impact energy can be absorbed and consumed, so that the impact load received by the sensing element 120 is greatly reduced, thereby protecting the sensing element 120 and prolonging the service life of the sensing element 120.

[0079] In addition, due to the existence of stress during the processing of the acceleration sensor 100, especially for cantilever beam type devices, device deformation such as bending (along the length, width), twisting, etc. often occurs. However, cantilever beam structure is commonly used in acceleration sensors. The sensing device 200 can correct the deformation of the device by using the gravity, surface tension, viscous force, etc. of the liquid in the cavity, so that the deformation of the device is smaller, the output is more stable, and the actual design effect is closer.

[0080] Figure 2C is a mechanical equivalent schematic diagram of an exemplary sensing device 250 according to some embodiments of the present application.

[0081] The sensing device 250 includes the acceleration sensor 100 and the second resonance system 260. In some embodiments, the sensing device 250 can be regarded as adjusting the first resonance system 210 based on the sensing device 200 to form the second resonance system 260. For example, in this embodiment, the second resonance system 260 has a spring (Km3) and a damper (Rm3) added to the first resonance system 210. The second resonance system 260 can be arranged between the housing 110 and the sensing element 120. For example, Figure 2C As shown, the spring (Km3)-damper (Rm3) of the second resonant system 260 can be connected in series with the spring (Km4)-mass (Mm4)-damper (Rm4) of the first resonant system 210, and indirectly act on the sensing element 120. For another example, the spring (Km3)-damper (Rm3) of the second resonant system 260 can be connected in series with the spring (Km4)-mass (Mm4)-damper (Rm4) of the first resonant system 210, and directly act on the sensing element 120. Due to the action of the second resonant system 260, when the housing 110 receives an external vibration signal, the external vibration signal will be transmitted to the sensing element 120 through the housing area connected to the sensing element 120 and the housing area connected to the second resonant system through the second resonant system 260. Therefore, the mechanical response of the sensing device 250 is changed compared to both the sensing device 200 and the acceleration sensor 100. Accordingly, the electrical, acoustic, and / or thermal responses of sensing device 250 are changed compared to sensing device 200 and accelerometer 100. Furthermore, due to the newly introduced spring (Km3) and damping (Rm3) of second resonant system 260, the vibration characteristics (e.g., stiffness-damping, etc.) of sensing device 250 are changed compared to sensing device 200 and accelerometer 100.

[0082] In some embodiments, the second resonant system 260 can be an elastic structure connected to the sensing element 120. The elastic structure can include a plurality of elastic rods, elastic strings, elastic sheets, springs, elastic net supports, elastic blocks, etc. connected in series. For example, the second resonant system 260 can include at least one elastic rod and / or spring with a small mass and one elastic rod and / or spring with a large mass. In this case, the elastic rod and / or spring with the large mass can be equivalent to the spring (Km4)-mass (Mm4)-damping (Rm4) described above, and the elastic rod and / or spring with the small mass can be equivalent to the spring (Km3) and damping (Rm3) described above. The two ends of the elastic rod and / or spring are fixedly connected to the housing 110 and the sensing element 120, respectively. In some embodiments, the elastic rod with the small mass (e.g., made of a low-density material) and the elastic rod with the large mass (e.g., made of a high-density material) in the second resonant system 260 can be integrally formed by injection molding, physical growth, etc. In some embodiments, the multi-stage elastic structure of the second resonant system 260 can also be integrally formed with the sensing element 120.

[0083] In some embodiments, the second resonant system 260 can be formed by filling different media into the cavity of the acceleration sensor 100. For example, the cavity of the acceleration sensor 100 can be filled with a portion of liquid to form the second resonant system 260 in which liquid and gas bubbles coexist in the cavity. The gas bubbles can be formed by air not expelled from the cavity, by a gas-filled bladder (e.g., a polyester film, a nylon film, a plastic film, a composite film, etc.), and / or by a hydrophobic coating applied to the sensing element. The gas in the gas bubbles can be air, oxygen, nitrogen, an inert gas, etc. In this case, the liquid in the cavity can be equivalent to the spring (Km4)-mass (Mm4)-damping (Rm4) described above, and the gas bubbles can be equivalent to the spring (Km3) and damping (Rm3) described above. For another example, the cavity of the acceleration sensor 100 can be filled with liquids with different densities and immiscible with each other to form the second resonant system 260. In some embodiments, the media filled into the cavity of the acceleration sensor 100 can be set by a user or determined based on the performance (e.g., sensitivity, noise floor, peak-to-peak value of the resonance peak, frequency range of the resonance peak, peak-to-valley value, and / or quality factor Q, etc.) of the sensing device 250.

[0084] Figure 2DFIG. 25 is a schematic diagram of a sensing device 250 filled with liquid and bubbles according to some embodiments of the present application. In the sensing device 250, the cavity of the housing 110 is filled with liquid and bubbles. The liquid in the sensing device 250 can be the same or different from the liquid in the sensing device 200. For example, the sensing device 250 and the sensing device 200 are both filled with silicon oil with the same kinematic viscosity. For another example, the sensing device 250 and the sensing device 200 are filled with different kinds of liquid or the same kind of liquid with different kinematic viscosities (e.g., silicon oil with kinematic viscosities of 0.65 cSt and 200 cSt, respectively). The liquid and the bubbles can be injected or formed in the cavity of the housing 110 in a specific manner.

[0085] In some embodiments, the frequency response curve of the sensing device 250 includes at least two resonance peaks. The at least two resonance peaks include a third resonance peak and a fourth resonance peak. The third resonance peak is the resonance peak corresponding to the acceleration sensor 100, and the fourth resonance peak is the resonance peak generated by the additional system (for the sensing device 250, the additional system is the second resonant system 260) of the acceleration sensor 100.

[0086] In some embodiments, the third resonant frequency (the resonant frequency corresponding to the third resonance peak) and the fourth resonant frequency (the resonant frequency corresponding to the fourth resonance peak) of the sensing device 250 can satisfy different relationships. For example, when the second resonant system 260 is formed by the liquid and the bubbles, due to the large compressibility and small stiffness of the bubbles (compared to the case of pure liquid), the sensing device 250 can have a resonant frequency in the low frequency or low-middle frequency band or in the middle-high frequency band. For example, the fourth resonant frequency is in the low frequency, low-middle frequency, or middle-high frequency, and the third resonant frequency can be greater than the fourth resonant frequency, for example, the third resonant frequency is in a higher frequency band. For another example, the fourth resonant frequency is in the low-middle frequency, where the low frequency, low-middle frequency, and middle-high frequency refer to frequencies within a certain range. For example, the low frequency or low-middle frequency or middle-high frequency is in a frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, or 50 Hz, and the higher frequency band corresponds to a frequency range of 2000 Hz or more, 5000 Hz or more, 8000 Hz or more, etc. The third resonant frequency is higher than the fourth resonant frequency, and optionally, the difference between the two resonant frequencies is 100-6000 Hz. When the sensing device 250 has a resonant frequency in the low frequency or low-middle frequency range, its sensitivity in the low frequency range is higher than that of the acceleration sensor 100. When the sensing device 250 further has a resonant frequency in the high frequency or middle-high frequency range, its frequency response curve is also flatter in the low-middle frequency range, which is more conducive to obtaining effective signals in this frequency range.

[0087] In addition, due to the second resonant system 260 acting on the sensing element 120, the vibration characteristics of the acceleration sensor 100 will change compared to the case without the second resonant system 260. Specifically, the second resonant system 260 acting on the sensing element 120 can affect the stiffness and / or damping of the acceleration sensor 100, and the effect is equivalent to changing (e.g., reducing) the Q value of the third resonance peak of the sensing device 250 relative to the acceleration sensor 100 without the second resonant system 260. For more specific descriptions of the frequency response curve of the sensing device 250 and the third and fourth resonance peaks, please refer to other parts of this specification, for example Figure 3A and Figure 3B and their descriptions.

[0088] At the same time, the second resonant system 260 can reduce the external impact received by the sensing element to protect the sensing element. For example, if liquid and gas bubbles are introduced into the cavity of the shell 110, the impact resistance reliability of the sensing device 250 when receiving external impact loads can be improved. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load received by the sensing element 120 is greatly reduced, thereby protecting the sensing element 120 and prolonging its service life.

[0089] In addition, due to the second resonant system 260 acting on the sensing element 120, the vibration characteristics of the acceleration sensor 100 will change compared to the case without the second resonant system 260. Specifically, the second resonant system 260 acting on the sensing element 120 can affect the stiffness and / or damping of the acceleration sensor 100, and the effect is equivalent to changing (e.g., reducing) the Q value of the third resonance peak of the sensing device 250 relative to the acceleration sensor 100 without the second resonant system 260. For more specific descriptions of the frequency response curve of the sensing device 250 and the third and fourth resonance peaks, please refer to other parts of this specification, for example

[0090] It should be noted that the above description of the sensing devices 200 and 250 is only exemplary and does not limit the scope of the present specification to the embodiments described. It can be understood that, for those skilled in the art, after understanding the principles of the system, the structure and modules can be combined arbitrarily or connected to other modules to form a subsystem without departing from the principles. For example, the sensing element therein can be a mass element 121 supported by an elastic diaphragm 124 as shown in Figure 1 , which has the same or similar mechanical equivalence, frequency response curve, etc.

[0091] Figure 3A is an exemplary frequency response curve of the sensing device 200 or 250 according to some embodiments of the present application.

[0092] Exemplarily, as Figure 3AAs shown, the frequency response curve 310 represented by the dashed line is the frequency response curve of the acceleration sensor 100, and the frequency response curve 320 represented by the solid line is the frequency response curve of the sensing device 200 or 250. The horizontal axis represents the frequency in hertz (Hz), and the vertical axis represents the sensitivity in decibel of volt (dBV). 1 dBV = 20lg(S), and the unit of the sensitivity S is V / g. The frequency response curve 310 includes a resonance peak 311, which corresponds to the resonance frequency of the acceleration sensor 100. The frequency response curve 320 includes a first (or third) resonance peak 321 and a second (or fourth) resonance peak 322. For the sensing device 200, the first resonance peak 321 corresponds to the first resonance frequency, and the second resonance peak 322 is formed by the action of the first resonance system 210 and corresponds to the second resonance frequency. For the sensing device 250, the third resonance peak 321 corresponds to the third resonance frequency, and the fourth resonance peak 322 is formed by the action of the second resonance system 260 and corresponds to the fourth resonance frequency.

[0093] It should be noted that the second (or fourth) resonance peak 322 shown in the figure is on the left side of the first (or third) resonance peak 321, that is, the frequency corresponding to the second (or fourth) resonance peak 322 is less than the frequency corresponding to the first (or third) resonance peak. In some embodiments, by changing the mechanical parameters in the sensing element or the first (or second) resonance system, the frequency corresponding to the second (or fourth) resonance peak 322 can be greater than the frequency corresponding to the first (or third) resonance peak 321, that is, the second (or fourth) resonance peak 322 is on the right side of the first (or third) resonance peak 321. For example, for the sensing device 200 filled with liquid inside, the second (or fourth) resonance peak 322 can be on the left side or the right side of the first (or third) resonance peak 321, and its position can be related to the properties of the filled liquid (for example, density, kinematic viscosity, volume, etc.). For example, if the density of the liquid becomes smaller or the kinematic viscosity becomes larger, the resonance peak will shift to high frequency.

[0094] In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 10 Hz - 12000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 10 Hz - 10000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 50 Hz - 10000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 100 Hz - 7000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 1500 Hz - 5000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 200 Hz - 5000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 200 Hz - 4000 Hz. In some embodiments, the frequency corresponding to the resonance peak 311 is in the range of 300 Hz - 4000 Hz.

[0095] In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 10 Hz - 12000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 50 Hz - 10000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 100 Hz - 10000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 150 Hz - 7000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 150 Hz - 5000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 200 Hz - 5000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 200 Hz - 4000 Hz. In some embodiments, the frequency corresponding to the first (or third) resonance peak 321 is in the range of 300 Hz - 4000 Hz.

[0096] In some embodiments, the resonance frequency corresponding to the first (or third) resonance peak 321 (first resonance frequency or third resonance frequency) is different from the resonance frequency corresponding to the resonance peak 311. For example, for a sensing device 200 with a cavity of the housing 110 filled with liquid, the liquid acts as a first resonance system 210, and due to the incompressibility of the liquid, the stiffness of the system itself becomes larger, so the first frequency corresponding to the first resonance peak 321 becomes larger than the resonance frequency corresponding to the resonance peak 311, i.e., the first resonance peak 321 is shifted to the right relative to the resonance peak 311.

[0097] In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 1 Hz - 12000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 1 Hz - 10000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 1 Hz - 6000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 10 Hz - 5000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 10 Hz - 5000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 50 Hz - 5000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 50 Hz - 3000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 50 Hz - 2000 Hz. In some embodiments, the second (or fourth) resonance peak 322 corresponds to a frequency in the range of 100 Hz - 2000 Hz.

[0098] In some embodiments, the fourth resonance frequency is lower than the second resonance frequency. For a liquid filled sensor 200 in the cavity of the housing 110, the liquid acts as the first resonant system 210, and for a sensor 250 containing both liquid and air bubbles in the cavity of the housing 110, the liquid and air bubbles act as the second resonant system 260, respectively. The combined overall stiffness of the second resonant system 260 is lower than that of the liquid, and thus the fourth resonance frequency is lower than the second resonance frequency.

[0099] In some embodiments, the output quality of the sensing device 200 or 250 can be improved by adjusting the structure, material of the sensing element, and one or more mechanical parameters in the first (or second) resonant system (e.g., the kind of filling liquid, the bubble size, etc.) such that the frequency response curve 320 is relatively flat between the two resonance peaks 321 and 322. In some embodiments, the difference in sensitivity between the trough between the resonance peaks 321 and 322 and the peak value of the higher peak of the resonance peaks 321 and 322 is no more than 30 dBV, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than 0.2. In some embodiments, the difference in sensitivity between the trough between the resonance peaks 321 and 322 and the peak value of the higher peak of the resonance peaks 321 and 322 is no more than 20 dBV, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than 0.15. In some embodiments, the difference in sensitivity between the trough between the resonance peaks 321 and 322 and the peak value of the higher peak of the resonance peaks 321 and 322 is no more than 15 dBV, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than 0.12. In some embodiments, the difference in sensitivity between the trough between the resonance peaks 321 and 322 and the peak value of the higher peak of the resonance peaks 321 and 322 is no more than 10 dBV, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than 0.1. In some embodiments, the difference in sensitivity between the trough between the resonance peaks 321 and 322 and the peak value of the higher peak of the resonance peaks 321 and 322 is no more than 8 dBV, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than 0.08. In some embodiments, the difference in sensitivity between the trough between the resonance peaks 321 and 322 and the peak value of the higher peak of the resonance peaks 321 and 322 is no more than 5 dBV, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than 0.05.

[0100] Accordingly, when the difference in the resonant frequencies corresponding to the resonance peaks 321 and 322 (the frequency of the resonance peak 321 is represented by f0 (close to the resonance peak 311), the frequency of the resonance peak 322 is represented by f1, and the difference in the resonant frequencies corresponding to the resonance peaks 321 and 322 is represented by the frequency difference Δf1) is within a certain range, the frequency response curve between the resonance peaks 321 and 322 can be made relatively flat. In some embodiments, the frequency difference Δf1 is in the range of 20-3000 Hz, and the ratio of the frequency difference Δf1 to f0 is in the range of 0.02-0.7. In some embodiments, the frequency difference Δf1 is in the range of 20-2000 Hz, and the ratio of the frequency difference Δf1 to f0 is in the range of 0.02-0.65. In some embodiments, the frequency difference Δf1 is in the range of 50-2000 Hz, and the ratio of the frequency difference Δf1 to f0 is in the range of 0.05-0.65. In some embodiments, the frequency difference Δf1 is in the range of 50-1500 Hz, and the ratio of the frequency difference Δf1 to f0 is in the range of 0.05-0.6. In some embodiments, the frequency difference Δf1 is in the range of 80-1500 Hz, and the ratio of the frequency difference Δf1 to f0 is in the range of 0.1-0.6. In some embodiments, the frequency difference Δf1 is in the range of 100-1500 Hz, and the ratio of the frequency difference Δf1 to f0 is in the range of 0.15-0.6.

[0101] like Figure 3A As shown, compared to frequency response curve 310, frequency response curve 320 has a higher and more stable sensitivity improvement (i.e., difference, represented by ΔV1) within the frequency range within the resonant frequency f1 corresponding to the second (or fourth) resonance peak 322. In some embodiments, the improvement ΔV1 is within the range of 10 dBV to 60 dBV. In some embodiments, the improvement ΔV1 is within the range of 10 dBV to 50 dBV. In some embodiments, the improvement ΔV1 is within the range of 15 dBV to 50 dBV. In some embodiments, the improvement ΔV1 is within the range of 15 dBV to 40 dBV. In some embodiments, the improvement ΔV1 is within the range of 20 dBV to 40 dBV. In some embodiments, the improvement ΔV1 is within the range of 25 dBV to 40 dBV. In some embodiments, the improvement ΔV1 is within the range of 30 dBV to 40 dBV.

[0102] The presence of the first resonant system 210 or the second resonant system 260 can cause the corresponding resonant peak of the acceleration sensor 100 in the sensing device 200 or 250 to be suppressed, such that the Q value at the first (or third) resonant peak 321 of the frequency response curve 320 is relatively low, the frequency response curve is more flattened in the desired frequency range (e.g., low-mid frequency), and the difference between the peak value of the highest peak and the valley value of the lowest valley (also referred to as the peak-valley value, denoted as AV2) of the overall frequency response curve 320 is within a certain range. In some embodiments, the peak-valley value is not more than 30 dBV, and the ratio of the peak-valley value to the peak value of the highest peak is not more than 0.2. In some embodiments, the peak-valley value is not more than 20 dBV, and the ratio of the peak-valley value to the peak value of the highest peak is not more than 0.15. In some embodiments, the peak-valley value is not more than 10 dBV, and the ratio of the peak-valley value to the peak value of the highest peak is not more than 0.1. In some embodiments, the peak-valley value is not more than 8 dBV, and the ratio of the peak-valley value to the peak value of the highest peak is not more than 0.08. In some embodiments, the peak-valley value is not more than 5 dBV, and the ratio of the peak-valley value to the peak value of the highest peak is not more than 0.05.

[0103] For the sensing device 250, in some embodiments, the frequency corresponding to the fourth resonant peak 322 (i.e., the fourth resonant frequency) is a low-mid frequency, and the frequency corresponding to the third resonant peak 321 (i.e., the third resonant frequency) is a mid-high frequency. In some embodiments, the difference between the minimum sensitivity value of the frequency response curve 320 within the frequency range within the resonant frequency fl and the peak value of the fourth resonant peak is not more than 30 dBV, and the ratio thereof is not more than 0.2. In some embodiments, the difference between the minimum sensitivity value of the frequency response curve 320 within the frequency range within the resonant frequency fl and the peak value of the fourth resonant peak is not more than 20 dBV, and the ratio thereof is not less than 0.15. In some embodiments, the difference between the minimum sensitivity value of the frequency response curve 320 within the frequency range within the resonant frequency fl and the peak value of the fourth resonant peak is not more than 10 dBV, and the ratio thereof is not more than 0.1.

[0104] In some embodiments, the frequency response of the sensing device 200 or 250 can be described by one or more of the relevant parameters of the curve 320, such as the peak value, frequency of the first (or third) resonance peak 321, the peak value, frequency of the second (or fourth) resonance peak 322, Q value, Af1, AV1, AV2, the ratio of Af1 to f0, the ratio of the peak-to-valley value to the peak value of the highest peak, the first order coefficient, the second order coefficient, the third order coefficient of the equation determined by fitting the frequency response curve, etc. In some embodiments, the frequency response of the sensing device 200 or 250 can be related to the properties of the filled liquid and / or the parameters of the acceleration sensor 100. The properties of the liquid can include, for example, the liquid density, the liquid kinematic viscosity, the liquid volume, whether there is a bubble, the bubble volume, the bubble location, the bubble number, etc. The parameters of the acceleration sensor 100 can include, for example, the internal structure, size, stiffness of the housing 110, the mass of the acceleration sensor 100, and / or the size, stiffness of the sensing element 120 (e.g., a cantilever beam), etc.

[0105] In some embodiments, to obtain a desired output frequency response (e.g., the frequency response curve 320) of the sensing device 200 or 250, the ranges of the above-listed parameters (also referred to as frequency response influencing factors, including the properties of the filled liquid and / or the parameters of the acceleration sensor 100) that affect the frequency response can be determined by computer simulation, modal experiments, etc. In some embodiments, based on the simulation, the effect of each factor on the frequency response of the sensing device 200 or 250 can be determined one by one by controlling the variable. For example, the performance of sensing devices with different cavity structure characteristics is tested under the premise of the same liquid and full filling. For another example, the performance of devices with different housing stiffness characteristics is tested under the premise of the same liquid and full filling. For another example, the performance of the sensing device is tested under the premise of the same housing size in the case of filling liquid and filling liquid and bubbles. For another example, the performance of the sensing device is tested under the premise that the bubble does not cover the sensing element (e.g., a piezoelectric transducer) with different bubble size characteristics. For another example, the performance of the sensing device is tested under the premise that the bubble covers the sensing element (e.g., a piezoelectric transducer) with different bubble size characteristics.

[0106] In some embodiments, the effects of some factors on the frequency response of the sensing device 200 or 250 are correlated with the effects of other factors, and thus the effects of a parameter pair or a parameter group on the frequency response of the sensing device 200 or 250 can be determined in the form of a corresponding parameter pair or parameter group. For example, when the height of the housing of the acceleration sensor 100 is increased, the volume of the cavity is increased, the mass of the housing is increased, and the volume of the liquid filled in the cavity is also increased accordingly, and thus the height of the housing, the mass of the housing, and / or the volume of the liquid (or a ratio of any two parameters, or a product of at least two parameters, etc.) can be used as a parameter group to test the performance of the sensing device with different parameter pairs on the parameter group characteristics. For another example, the viscosity and the density of the liquid can be used as a parameter pair to test the effects of the parameter pair (or a ratio, a product, etc.) on the frequency response of the sensing device 200 or 250.

[0107] In some embodiments, the effects of a factor or a plurality of factors on the frequency response of the sensing device 200 or 250 can be determined by a model test.

[0108] For example, for the sensing device 200 or 250 filled with a liquid with different viscosities, the greater the viscosity of the liquid, the greater the system damping, and the smaller the Q value of the frequency response of the sensing device 200. For the sensing device 250 filled with a liquid and air bubbles, within a certain range of kinematic viscosity, the greater the kinematic viscosity of the liquid, the greater the sensitivity of the sensing device 250.

[0109] In some embodiments, the kinematic viscosity of the liquid can be 0.1-5000 cst. In some embodiments, the kinematic viscosity of the liquid can be 0.1-1000 cst. In some embodiments, the kinematic viscosity of the liquid can be 0.3-1000 cst. In some embodiments, the kinematic viscosity of the liquid can be 0.5-500 cst. In some embodiments, the kinematic viscosity of the liquid can be 0.5-200 cst. In some embodiments, the kinematic viscosity of the liquid can be 50-200 cst.

[0110] For example, for the sensing device 200 filled with a liquid, by increasing the size of the cavity, the sensitivity of the sensor in the medium frequency can be improved, the inhibitory effect of the liquid on the frequency response of the sensing device in the medium frequency is reduced, and the frequency response curve is more flat.

[0111] For example, for the sensing device 200 filled with a liquid with different cavity heights, within a certain range, the higher the cavity height, the higher the output sensitivity of the sensing device 200 in the low and medium frequency.

[0112] In some embodiments, the length, width, and height of the sensor device cavity are 1-30 mm, 1-30 mm, and 0.5-30 mm, respectively. In some embodiments, the length, width, and height of the sensor device cavity are 2-30 mm, 2-30 mm, and 1-30 mm, respectively. In some embodiments, the length, width, and height of the sensor device cavity are 5-10 mm, 5-10 mm, and 1-10 mm, respectively. In some embodiments, the length, width, and height of the sensor device cavity are 8-10 mm, 5-10 mm, and 1-5 mm, respectively. Optionally, the sensor device cavity has larger dimensions. In some embodiments, the length, width, and height of the sensor device cavity are 10-200 mm, 10-100 mm, and 10-100 mm, respectively. In some embodiments, the length, width, and height of the sensor device cavity are 10-100 mm, 10-50 mm, and 10-50 mm, respectively. In some embodiments, the length, width, and height of the sensor device cavity are 10-50 mm, 10-30 mm, and 10-30 mm, respectively.

[0113] Exemplarily, compared to the liquid-filled sensor device 200, the liquid and bubble-filled sensor device 250 has a higher overall output gain due to the compressibility of the gas, which is less rigid, and the incompressibility of the liquid, which can cause over-stiffness and over-damping. For example, in some cases, the second resonance peak of the sensor device 200 can "disappear" due to over-damping, thereby affecting the improvement of the sensitivity of the sensor device 200 at medium and low frequencies.

[0114] Exemplarily, the liquid and bubble-filled sensor device 250 has an increasing sensitivity as the volume of the bubble increases when the bubble does not cover the sensing element (e.g., a piezoelectric transducer).

[0115] In some embodiments, the ratio of the volume of the bubble to the volume of the liquid can be 5%-90%. In some embodiments, the ratio of the volume of the bubble to the volume of the liquid can be 10%-80%. In some embodiments, the ratio of the volume of the bubble to the volume of the liquid can be 20%-60%. In some embodiments, the ratio of the volume of the bubble to the volume of the liquid can be 30%-50%.

[0116] It should be noted that the above description of the frequency response curve of the sensor device 200 or 250 is only an exemplary description and does not limit the present specification to the embodiments described. It can be understood that, for those skilled in the art, after understanding the principles of the system, they can make any adjustment to the structure and composition of the system without departing from the principles. Such modifications are within the scope of protection of the present application.

[0117] Figure 3Bis an exemplary frequency response curve of the sensing device 200 or 250 provided according to some embodiments of the present application.

[0118] For example, Figure 3B As shown, the frequency response curve 360 ​​represented by the dashed line is the frequency response curve of the accelerometer 100, and the frequency response curve 370 represented by the solid line is the frequency response curve of the sensing device 200 or 250. Frequency response curve 360 ​​includes a resonance peak 361, which corresponds to the resonant frequency of the accelerometer 100. In some embodiments, the higher resonant frequency corresponding to the accelerometer 100 is not within the desired frequency range (e.g., 10-5000 Hz, 50-7000 Hz, etc.). In some embodiments, the resonant frequency corresponding to the accelerometer 100 can be within a higher frequency range. For example, in some embodiments, the resonant frequency corresponding to the accelerometer 100 is higher than 7000 Hz. In some embodiments, the resonant frequency corresponding to the accelerometer 100 is higher than 10000 Hz. In some embodiments, the resonant frequency corresponding to the accelerometer 100 is higher than 12000 Hz. Accordingly, the sensing device 200 or 250 may have higher rigidity, which also provides the sensing device 200 or 250 with higher impact resistance and reliability.

[0119] The frequency response curve 370 includes a first (or third) resonance peak (not shown) and a second (or fourth) resonance peak 372. In some embodiments, the frequency corresponding to the first (or third) resonance peak is close to or the same as the resonance frequency corresponding to the acceleration sensor 100 in the frequency response curve 360. In some embodiments, the frequency response curve 370 is similar to the Figure 3A The frequency response curve 320 in FIG is substantially the same except that the first (or third) resonance peak is shifted to the right. The frequency corresponding to the second (or fourth) resonance peak 372 is Figure 3A The frequency range corresponding to the second (or fourth) resonance peak 322 is the same or similar.

[0120] In some embodiments, the difference between the maximum and minimum sensitivity in the frequency response curve 370 should be kept within a certain range in a desired frequency range (e.g., within 200 Hz, within 300 Hz, within 500 Hz, etc.) to ensure the stability of the frequency response of the sensing device 200 or 250. In some embodiments, the difference between the maximum and minimum sensitivity is no more than 40 dBV, and the ratio of the sensitivity difference to the maximum sensitivity is no more than 0.3, in the desired frequency range. In some embodiments, the difference between the maximum and minimum sensitivity is no more than 30 dBV, and the ratio of the sensitivity difference to the maximum sensitivity is no more than 0.25, in the desired frequency range. In some embodiments, the difference between the maximum and minimum sensitivity is no more than 20 dBV, and the ratio of the sensitivity difference to the maximum sensitivity is no more than 0.15, in the desired frequency range. In some embodiments, the difference between the maximum and minimum sensitivity is no more than 10 dBV, and the ratio of the sensitivity difference to the maximum sensitivity is no more than 0.1, in the desired frequency range.

[0121] In some embodiments, the difference between the resonant frequencies corresponding to the first (or third) resonance peak and the second (or fourth) resonance peak 372 (the frequency of the first (or third) resonance peak is denoted as f0(approximately corresponding to the resonance peak 361), and the frequency of the second (or fourth) resonance peak 372 is denoted as f1) is within a certain range. In some embodiments, the frequency difference Af2is within the range of 100-8000 Hz, and the ratio of the frequency difference Af2to f0is within the range of 0.02-0.8. In some embodiments, the frequency difference Af2is within the range of 100-6000 Hz, and the ratio of the frequency difference Af2to f0is within the range of 0.02-0.65. In some embodiments, the frequency difference Af2is within the range of 200-6000 Hz, and the ratio of the frequency difference Af2to f0is within the range of 0.05-0.65. In some embodiments, the frequency difference Af2is within the range of 300-5000 Hz, and the ratio of the frequency difference Af2to f0is within the range of 0.1-0.5. In some embodiments, the frequency difference Af2is within the range of 300-4000 Hz, and the ratio of the frequency difference Af2to f0is within the range of 0.1-0.4.

[0122] Compared with the frequency response curve 360, the frequency response curve 370 has a higher and more stable sensitivity improvement (i.e. difference, denoted as AV3) within the frequency range within the second (or fourth) resonance peak 372 corresponding to the resonance frequency f1. In some embodiments, the improvement AV3 is within the range of 10 dBV-60 dBV. In some embodiments, the improvement AV3 is within the range of 10 dBV-50 dBV. In some embodiments, the improvement AV3 is within the range of 15 dBV-50 dBV. In some embodiments, the improvement AV3 is within the range of 15 dBV-40 dBV. In some embodiments, the improvement AV3 is within the range of 20 dBV-40 dBV. In some embodiments, the improvement AV3 is within the range of 25 dBV-40 dBV. In some embodiments, the improvement AV3 is within the range of 30 dBV-40 dBV.

[0123] For the sensing device 250, in some embodiments, the frequency corresponding to the fourth resonance peak 372 (i.e. fourth resonance frequency) is a low-mid frequency, and the frequency corresponding to the third resonance peak (i.e. third resonance frequency) is a mid-high frequency. In some embodiments, the difference between the minimum sensitivity within the frequency range within the resonance frequency f1 and the peak value of the fourth resonance peak is no more than 30 dBV, and the ratio is no more than 0.2. In some embodiments, the difference between the minimum sensitivity within the frequency range within the resonance frequency f1 and the peak value of the fourth resonance peak is no more than 20 dBV, and the ratio is no less than 0.15. In some embodiments, the difference between the minimum sensitivity within the frequency range within the resonance frequency f1 and the peak value of the fourth resonance peak is no more than 10 dBV, and the ratio is no more than 0.1.

[0124] In some embodiments, the frequency response of the sensing device 200 or 250 can be described by one or more of the relevant parameters of the curve 370, such as the peak value, frequency of the primary resonance peak, the peak value, frequency, Q value of the secondary resonance peak 372, AV3, the ratio of AV3 to f0, the ratio of the maximum sensitivity to the minimum sensitivity within the required frequency range, the first order coefficient, the second order coefficient, the third order coefficient of the equation determined by fitting the frequency response curve, etc. In some embodiments, the frequency response of the sensing device 200 or 250 can be related to the properties of the filled liquid and / or the parameters of the acceleration sensor 100. In some embodiments, to obtain the desired output frequency response (e.g. the frequency response curve 370) of the sensing device 200 or 250, the ranges of the above-mentioned parameters (also referred to as frequency response influencing factors, including the properties of the filled liquid and / or the parameters of the acceleration sensor 100) affecting the frequency response can be determined in the same or similar manner as described in the method in the Figure 3A section, which will not be repeated here.

[0125] Figure 3C is an exemplary frequency response curve of the sensing device 200 or 250 provided according to some embodiments of the present application.

[0126] For example, Figure 3C As shown, the dashed frequency response curve 380 represents the frequency response curve of accelerometer 100, and the solid frequency response curve 390 represents the frequency response curve of sensing device 200 or 250. Frequency response curve 380 includes a resonance peak 381, which corresponds to the resonant frequency of accelerometer 100. Frequency response curve 390 includes a first (or third) resonance peak and a second (or fourth) resonance peak. The frequency of resonance peak 391 is represented by f0 (close to resonance peak 381), the frequency of resonance peak 392 is represented by f1, and the difference in the resonant frequencies corresponding to resonance peaks 391 and 392 is represented by a frequency difference Δf3. In some embodiments, f1 can be close to or equal to f0 to further improve the output of sensing device 200 or 250 at resonant frequency f0. Figure 3C The figure shows the case where f1 is close to or equal to f0.

[0127] In some embodiments, to improve the sensitivity of the sensing device 200 or 250 to the acceleration signal at f_1 and / or f_0, the structural parameters of the first resonant system 210 or the second resonant system 260 can be set so that the absolute value of the difference Δf3 between f_1 and f_0 is no greater than a set threshold. In some embodiments, the absolute value of Δf3 can be no greater than 1000 Hz. In some embodiments, the absolute value of Δf3 can be less than 1000 Hz. In some embodiments, the absolute value of Δf3 can be less than 800 Hz. In some embodiments, the absolute value of Δf3 can range from 100 Hz to 200 Hz. In some embodiments, the absolute value of Δf3 can range from 0 Hz to 100 Hz. In some embodiments, the absolute value of Δf3 can be 0, meaning that f1 and f0 are equal. In some embodiments, the structural parameters of the first resonant system 210 or the second resonant system 260 and / or the acceleration sensor 100 can be set to a relatively small absolute value of Δf3. In this case, since the sensing device 200 or 250 resonates with the external acceleration signal at f_0 and f_1, respectively, the frequency components within a certain frequency band including f_0 or f_1 are amplified. When the absolute value of Δf3 is close to 0 (i.e., f1 is substantially equal to f0), the frequency components near f_0 and f_1 can be further "amplified," resulting in the sensing device 200 or 250 having a higher sensitivity at f_0 and f_1. For example, Figure 3CThe resonance peaks 391 and 392 in the frequency response curve of the sensing device 200 or 250 correspond to substantially the same frequency point. The resonance peaks 391 and 392 jointly cause the sensitivity near the frequency point to be greatly improved. In some embodiments, the sensitivity of the sensing device 200 or 250 at f_1 can be greater than the sensitivity of the acceleration sensor 100 at f_1, as shown in the following equation: Figure 3C The difference between the two can be represented by AV1, as shown in the following equation.

[0128] In some embodiments, the sensitivity of the sensing device 200 or 250 in different resonance frequency ranges can be improved by 5dBV-60dBV compared to the acceleration sensor 100. In some embodiments, the sensitivity of the sensing device 200 or 250 in different resonance frequency ranges can be improved by 10dBV-40dBV.

[0129] Figure 4A and 4B is an exemplary structural diagram of a sensing element 400 according to some embodiments of the present application.

[0130] As shown in Figure 4A and 4B , the sensing element 400 includes a substrate (not shown in the figure), a mass element 420, and one or more detection capacitors for determining the magnitude of an external acceleration. The substrate can be a flat plate structure. The material of the substrate can be polysilicon, polysilicon germanium, etc. In some embodiments, the mass element 420 can be disposed at the center of the upper portion of the substrate. The mass element 420 can include upper and lower surfaces 421 and 422 that are parallel to each other and side surfaces (not shown in the figure) connecting the upper and lower surfaces. The mass element 420 can move relative to the substrate in response to an external acceleration.

[0131] In each direction (e.g., the first direction, the second direction, the third direction), the sensing element 400 can include at least one detection capacitor. In each direction, the sensing element 400 can include at least one moving electrode and at least one corresponding fixed electrode to form a detection capacitor for the direction to determine the acceleration magnitude in the direction. The at least one moving electrode can be disposed on the mass element 420. In some embodiments, the sensing element 400 can include at least one set of first moving electrodes arranged along the first direction and perpendicular to the first direction, and at least one set of second moving electrodes arranged along the second direction and perpendicular to the second direction. Each set of first moving electrodes includes one or more first moving electrodes. Each set of second moving electrodes includes one or more second moving electrodes. Correspondingly, the sensing element 400 can also include first fixed electrodes disposed parallel to and relative to each first moving electrode, and second fixed electrodes disposed parallel to and relative to each second moving electrode. The at least one set of first moving electrodes and the corresponding first fixed electrodes form a first direction detection capacitor. The at least one set of second moving electrodes and the corresponding second fixed electrodes form a second direction detection capacitor. The at least one set of first moving electrodes and the at least one set of second moving electrodes and the corresponding first fixed electrodes and second fixed electrodes collectively form a third direction detection capacitor.

[0132] In some embodiments, the at least one set of first moving electrodes includes an even number of first moving electrodes (e.g., two sets). The even number of first moving electrodes are located on two sides of the mass element 420 along the first direction. The even number of first moving electrodes and the corresponding first fixed electrodes can form a differential capacitor structure to more accurately determine the acceleration magnitude in the first direction. Similarly, the at least one set of second moving electrodes includes an even number of second moving electrodes (e.g., two sets). The even number of second moving electrodes are located on two sides of the mass element 420 along the second direction. The even number of second moving electrodes and the corresponding second fixed electrodes can form a differential capacitor structure to more accurately determine the acceleration magnitude in the second direction.

[0133] In some embodiments, each first moving electrode has a first moving electrode top surface parallel to the upper surface of the mass element and a first moving electrode bottom surface, and the corresponding first fixed electrode has a first fixed electrode top surface parallel to the upper surface of the mass element and a first fixed electrode bottom surface. The first moving electrode top surface is further away from the upper surface of the mass element than the first fixed electrode top surface. Each second moving electrode has a second moving electrode top surface parallel to the upper surface of the mass element and a second moving electrode bottom surface, and the corresponding second fixed electrode has a second fixed electrode top surface parallel to the upper surface of the mass element and a second fixed electrode bottom surface. The second moving electrode top surface is closer to the upper surface of the mass element than the second fixed electrode top surface. This can form a differential capacitor structure to more accurately determine the acceleration magnitude in the third direction.

[0134] Specifically, each group of first moving electrodes is provided with a first moving electrode axis along the first direction and a first fixed moving electrode perpendicular to the first direction. The group of first moving electrodes is distributed along the first moving electrode axis. The distance between each first moving electrode is the same or different. The first moving electrode axis and the first fixed moving electrode are connected to the substrate by a first elastic element (e.g., a spring, an elastic rod, an elastic net, etc.). Each group of second moving electrodes is provided with a second moving electrode axis along the second direction and a second fixed moving electrode perpendicular to the second direction. The group of second moving electrodes is distributed along the second moving electrode axis. The distance between each second moving electrode is the same or different. The second moving electrode axis and the second fixed moving electrode are connected to the substrate by a second elastic element (e.g., a spring, an elastic rod, an elastic net, etc.).

[0135] Correspondingly, the sensing element 400 can include a pair of first fixed electrode axes and a pair of first fixed moving electrodes corresponding to each group of first moving electrodes. The pair of first fixed electrode axes are symmetrically arranged relative to the first direction. For example, the pair of first fixed electrode axes are arranged at an angle (e.g., 90 degrees). The first moving electrode axis of each group of first moving electrodes is clamped between the pair of first fixed electrode axes. The pair of first fixed moving electrodes is perpendicular to the first direction. The first fixed moving electrode is clamped between the pair of first fixed moving electrodes. In some embodiments, the first fixed moving electrode is on a straight line with the pair of first fixed moving electrodes. The sensing element 400 can also include a pair of second fixed electrode axes and a pair of second fixed moving electrodes corresponding to each group of second moving electrodes. The pair of second fixed electrode axes are symmetrically arranged relative to the second direction. For example, the pair of second fixed electrode axes are arranged at an angle (e.g., 90 degrees). The second moving electrode axis of each group of second moving electrodes is clamped between the pair of second fixed electrode axes. The pair of second fixed moving electrodes is perpendicular to the second direction. The second fixed moving electrode is clamped between the pair of second fixed moving electrodes. In some embodiments, the second fixed moving electrode is on a straight line with the pair of second fixed moving electrodes. In some embodiments, the pair of first fixed electrode axes and the first fixed moving electrode and the first fixed moving electrode corresponding to each group of first moving electrodes can form a triangular region. The pair of second fixed electrode axes and the second fixed moving electrode and the second fixed moving electrode corresponding to each group of second moving electrodes can form a triangular region.

[0136] To more clearly illustrate the structure of the sensing element 400, the first direction is set as the horizontal direction and the second direction is set as the vertical direction. Figure 4AThe first direction is the X-axis shown in the figure, the second direction is the Y-axis direction, the X-axis direction and the Y-axis direction are perpendicular to each other, and the third direction is the Z-axis direction (not shown in the figure), which is perpendicular to the XY plane. For example, the sensing area of ​​the sensor element 400 can be divided into four triangular areas 410A, 410B, 410C and 410D. The sensing areas 410A and 410B are symmetrically arranged relative to the Y axis, and the sensing areas 410C and 410D are symmetrically arranged relative to the X axis; the sensing areas 410A and 410B are arranged along the X axis, and the sensing areas 410C and 410D are arranged along the Y axis.

[0137] like Figure 4A As shown, for the sensing regions 410A and 410B, the mass element 420 can extend in the X-axis (positive and negative) directions, forming first moving electrode axes 411A and 411B. The first moving electrode axes 411A and 411B are connected to the substrate via first elastic elements (e.g., first spring structures 412A and 412B). A group of first moving electrodes is formed along the first moving electrode axes 411A and 411B. The group of first moving electrodes includes a plurality of first moving electrodes (e.g., first moving electrodes 418A and 418B). The plurality of first moving electrodes are perpendicular to the first moving electrode axes 411A and 411B (i.e., in the X-axis direction) and are arranged sequentially along the first moving electrode axes 411A and 411B. The distance between each first moving electrode can be the same or different. The plurality of first moving electrodes are connected to the substrate via first elastic elements. For example, the first moving electrodes 418A and 418B are connected to the substrate via first spring structures 412A and 412B, respectively. A plurality of first fixed electrodes (e.g., first fixed electrodes 419A and 419B) are parallel to the first movable electrodes (e.g., first movable electrodes 418A and 418B) and fixedly connected to the substrate. The first movable electrodes (e.g., 418A and 418B) each overlap with the first fixed electrodes (e.g., 419A and 419B).

[0138] For sensing regions 410C and 410D, the mass element 420 can extend in the Y-axis direction to form second movable electrode axes 411C and 411D. The second movable electrode axes 411C and 411D are connected to the substrate by second elastic elements (e.g., second spring structures 412C and 412D). A set of second movable electrodes is formed along the second movable electrode axes 411C and 411D. The set of second movable electrodes includes a plurality of second movable electrodes (e.g., second movable electrodes 418C and 418D). The plurality of second movable electrodes are arranged in sequence perpendicular to the second movable electrode axes 411C and 411D (i.e., the Y-axis direction) and along the second movable electrode axes 411C and 411D. The distance between each second movable electrode is the same or different. The plurality of second movable electrodes are connected to the substrate by the second elastic elements. For example, the second movable electrodes 418C and 418D are connected to the substrate by the second spring structures 412C and 412D, respectively. A plurality of second fixed electrodes (e.g., second fixed electrodes 419C and 419D) are parallel to the second movable electrodes (e.g., second movable electrodes 418C and 418D) and fixedly connected to the substrate. The second movable electrodes (e.g., 418C and 418D) and the second fixed electrodes (e.g., 419C and 419D) have overlapping areas, respectively. The above-mentioned first and second movable electrodes (e.g., 418A, 418B, 418C, and 418D) and the first and second fixed electrodes (e.g., 419A, 419B, 419C, and 419D) cross each other to form a comb-tooth capacitance system.

[0139] The mass element 420 further includes first fixed movable electrodes (e.g., 413A and 413B). The first fixed movable electrodes are connected to the substrate by the first elastic elements (e.g., first spring structures 412A and 412B) or directly. The mass element 420 also includes a plurality of pairs of first fixed electrode axes (e.g., 415A and 417A, 415B and 417B) connected to the substrate. Each pair of first fixed electrode axes connects a corresponding first fixed electrode (e.g., 414A, 416A, 414B, and 416B) to the substrate. For example, the first fixed electrode axes 415A, 417A, 415B, and 417B connect the first fixed electrodes 414A, 416A, 414B, and 416B to the substrate, respectively. For each sensing region, the first movable electrode, the first movable electrode axis, and the first fixed movable electrode are sandwiched between a pair of first fixed electrode axes. For example, for the sensing region 410A, the first movable electrode 418A, the first movable electrode axis 411A, and the first fixed movable electrode 413A are sandwiched between the pair of first fixed electrode axes 415A and 417A. The pair of first fixed electrode axes and the first fixed electrode, the first fixed movable electrode form a triangular region for the sensing region. For example, for the sensing region 410A, the first fixed electrode axes 415A and 417A and the first fixed electrodes 414A and 416A and the first fixed movable electrode 413A form a triangular region.

[0140] Similarly, the mass element 420 further comprises second fixed dynamic electrodes (e.g., 413C, 413D). The second fixed dynamic electrodes are connected to the substrate through the second elastic elements (e.g., second spring structures 412C, 412D) or directly. The mass element 420 further comprises pairs of second fixed electrode shafts (e.g., 415C and 417C, 415D and 417D) connected to the substrate. Each first fixed electrode shaft connects a corresponding second fixed dynamic electrode (e.g., 414C, 416C, 414D, 416D) to the substrate. For example, the second fixed electrode shafts 415C, 417C, 415D, 417D connect the first fixed dynamic electrodes 414C, 416C, 414D, 416D to the substrate, respectively. For each sensing region, the second dynamic electrode, the second dynamic electrode shaft and the second fixed dynamic electrode are sandwiched between a pair of second fixed electrode shafts. For example, for the sensing region 410C, the second dynamic electrode 418C, the second dynamic electrode shaft 411C and the second fixed dynamic electrode 413C are sandwiched between the pair of second fixed electrode shafts 415C and 417C. The pair of second fixed electrode shafts of the sensing region forms a triangular region with the second fixed dynamic electrodes, the second fixed dynamic electrodes. For example, for the sensing region 410C, the second fixed electrode shafts 415C and 417C form a triangular region with the second fixed dynamic electrodes 414A, 416A and the first fixed dynamic electrode 413A. In this way, the sensing regions of the sensing element 400 are divided into four regions 410A, 410B, 410C, 410D. In some embodiments, the first / second fixed electrode shafts of adjacent sensing regions are arranged in parallel. For example, the first fixed electrode shafts 415A, 417A, 415B, 417B are arranged in parallel with the second fixed electrode shafts 417C, 415D, 417D, 415C, respectively, with a certain spacing.

[0141] In some embodiments, the height of the plurality of first / second dynamic electrodes in the third direction (i.e., the Z-axis direction) is different from the height of the plurality of first / second fixed electrodes. For example, the first dynamic electrodes 418A, 418B have a first dynamic electrode top surface 4181A and a first dynamic electrode bottom surface 4182A parallel to the upper surface 421 of the mass element 420, and the corresponding first fixed electrodes 419A, 419B have a first fixed electrode top surface and a first fixed electrode bottom surface (not shown in the figure) parallel to the upper surface 421 of the mass element 420. The height of the first dynamic electrodes 418A, 418B is smaller than the height of the first fixed electrodes 419A, 419B. If the first dynamic electrode bottom surface and the first fixed electrode bottom surface are on the same plane, the first dynamic electrodes 418A, 418B and the first fixed electrodes 419A, 419B have a height difference H2, as shown in FIG. 4B. In some embodiments, the height of the second dynamic electrodes 418C, 418D is different from the height of the second fixed electrodes 419C, 419D. For example, the second dynamic electrodes 418C, 418D have a second dynamic electrode top surface 4181C and a second dynamic electrode bottom surface 4182C parallel to the upper surface 421 of the mass element 420, and the corresponding second fixed electrodes 419C, 419D have a second fixed electrode top surface and a second fixed electrode bottom surface (not shown in the figure) parallel to the upper surface 421 of the mass element 420. The height of the second dynamic electrodes 418C, 418D is smaller than the height of the second fixed electrodes 419C, 419D. If the second dynamic electrode bottom surface and the second fixed electrode bottom surface are on the same plane, the second dynamic electrodes 418C, 418D and the second fixed electrodes 419C, 419D have a height difference H2, as shown in FIG. 4B. Figure 4BAs shown, the first moving electrode bottom surface and the first fixed electrode bottom surface are in the same plane, and the height difference between the top surface 4181A of the first moving electrode 418A and the top surface 4191A of the first fixed electrode 419A is H2. The second moving electrodes 418C, 418D have a second moving electrode top surface 4181C parallel to the upper surface 421 of the mass element 420 and a second moving electrode bottom surface 4182C, and the second fixed electrodes 419C, 419D have a second fixed electrode top surface 4191D parallel to the upper surface 421 of the mass element 420 and a second fixed electrode bottom surface 4192D. The height of the second moving electrodes 418C, 418D is greater than the height of the second fixed electrodes 419C, 419D. If the second moving electrode bottom surface and the second fixed electrode bottom surface are in the same plane, the second moving electrodes 418C, 418D and the second fixed electrodes 419C, 419D have a distance height difference H1, as shown in FIG. 4B. Figure 4B As shown, the second moving electrode bottom surface and the second fixed electrode bottom surface are in the same plane, and the height difference between the top surface 4181C of the second moving electrode 418C and the top surface 4191C of the second fixed electrode 419C is H1. In some embodiments, to improve the accuracy of the measurement and ensure the reliability of the manufacturing process, the first fixed electrode top surface and the second moving electrode top surface have the same horizontal height, as shown in FIG. 4B. Figure 4B For example, the first fixed electrode 419A top surface of the sensing region 410A and the second moving electrode top surface 4181D of the sensing region 410D have the same horizontal height, making the surface of the entire sensing element 420 more flat.

[0142] The plurality of first moving electrodes and the corresponding first fixed electrodes form a plurality of first and third direction detection capacitors for determining the acceleration magnitude in the first and third directions. The plurality of second moving electrodes and the corresponding second fixed electrodes form a plurality of second and third direction detection capacitors for determining the acceleration magnitude in the second and third directions. When there is an external acceleration in the first direction, the distance between the plurality of first moving electrodes and the corresponding first fixed electrodes changes, for example, when the mass element 420 moves in the positive direction of the X axis, the distance between the first moving electrodes and the first fixed electrodes of the sensing region 410A becomes smaller, the capacitance becomes larger, while the distance between the first moving electrodes and the first fixed electrodes of the sensing region 410B becomes larger, the capacitance becomes smaller, thereby generating a differential capacitance output signal proportional to the acceleration magnitude, so as to detect the acceleration in the first direction. When there is an external acceleration in the second direction, the distance between the plurality of second moving electrodes and the corresponding second fixed electrodes changes, for example, when the mass element 420 moves in the positive direction of the Y axis, the distance between the second moving electrodes and the second fixed electrodes of the sensing region 410C becomes smaller, the capacitance becomes larger, while the distance between the second moving electrodes and the second fixed electrodes of the sensing region 410D becomes larger, the capacitance becomes smaller, thereby generating a differential capacitance output signal proportional to the acceleration magnitude, so as to detect the acceleration in the second direction. When there is an external acceleration in the third direction, the facing area between the plurality of first moving electrodes or the second moving electrodes and the corresponding first fixed electrodes or the second fixed electrodes changes, for example, when the mass element 420 moves in the positive direction of the Z axis, the facing area between the first moving electrodes and the first fixed electrodes of the sensing regions 410A and 410B does not change, the capacitance does not change, while the facing area between the second moving electrodes and the second fixed electrodes of the sensing regions 410C and 410D becomes smaller, the capacitance becomes smaller, thereby detecting the acceleration in the third direction. The sensing element 400 is accommodated in the cavity formed by the housing 110 to form an acceleration sensor for detecting acceleration in three dimensions, while its structure is simple and reliable, and the overall size is small.

[0143] A sensing device (e.g., the sensing device 200 or 250) can be formed by coupling at least one resonant system to the acceleration sensor (e.g., between the housing 110 and the sensing element 400). The at least one resonant system can include Figure 2A and 2B a first resonant system 210 as shown in FIG. 2A or Figure 2C and 2D a second resonant system 260 as shown in FIG. 2B.

[0144] In some embodiments, the first resonant system 210 and the second resonant system 260 can include a liquid. Illustratively, the first resonant system 210 can be a liquid with a specific density and viscosity. For example, the liquid can be a silicone oil with a density of 0.94 kg / m3, and a kinematic viscosity of 0.5 cSt, 1 cSt, 5 cSt, 10 cSt, 100 cSt, 200 cSt, 1000 cSt, etc. The liquid can be equivalent to a spring (Km4) - mass (Mm4) - damping (Rm4) system. The first resonant system 210 can be coupled to the sensing element 400 by filling the cavity of the acceleration sensor with the liquid, such that the sensing element 400 is completely immersed in the liquid. The second resonant system 210 can be a liquid with bubbles, for example, a silicone oil with bubbles, where the proportion of the volume of the cavity occupied by the bubbles can be any value between 5% and 95%. The number of bubbles can be one, two, three, four, or more. The liquid can be equivalent to a spring (Km4) - mass (Mm4) - damping (Rm4) system, and the bubbles can be equivalent to a spring (Km3) and damping (Rm3) system. The second resonant system 260 can be coupled to the sensing element 400 by partially filling the cavity of the acceleration sensor with the liquid, partially filling the cavity with bubbles (e.g., bubbles formed by air not expelled from the cavity when filling the cavity with the liquid, bubbles formed by a bladder, and / or bubbles formed by applying a hydrophobic coating to the sensing element 400), such that the sensing element 400 is at least partially immersed in the liquid.

[0145] In some embodiments, the first resonant system 210 and the second resonant system 260 can comprise an elastic structure. Exemplarily, the first resonant system 210 can be an elastic structure (e.g., an elastic rod, an elastic sheet, an elastic block, an elastic net, etc.) with a certain mass, or a combination of a lightweight elastic structure (e.g., a lightweight spring, a lightweight elastic rod, etc.) and a mass unit. The elastic structure with a certain mass or the combination of the lightweight elastic structure and the mass unit can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The two ends of the elastic structure can be connected between the housing 110 and the sensing element 400 (e.g., the upper surface 421, the lower surface, and / or the side surface 423 of the mass element 420 or the plurality of first / second dynamic electrodes extending along the X / Y axis thereof), so as to couple the first resonant system 210 with the sensing element 400. The second resonant system 260 can be a combination of a lightweight elastic rod and / or spring and a relatively massive elastic rod. The relatively massive elastic rod can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The lightweight elastic rod and / or spring can be equivalent to a spring (Km3) and a damping (Rm3) system. The two ends of the elastic rod and / or spring can be fixedly connected between the housing 110 and the sensing element 400 (e.g., the upper surface 421, the lower surface, and / or the side surface 423 of the mass element 420 or the plurality of first / second dynamic electrodes extending along the X / Y axis thereof), so as to couple the second resonant system 260 with the sensing element 400.

[0146] Due to the existence of the second resonant frequency corresponding to the first resonant system 210 or the second resonant system 260, the frequency response curve of the sensing device containing the sensing element 400 can be improved in a certain frequency band (e.g., low frequency, medium-low frequency, medium frequency, medium-high frequency, and / or high frequency), so that the sensitivity of the acceleration sensor is improved compared with an acceleration sensor without the first resonant system 210 or the second resonant system 260. In addition, due to the action of the first resonant system 210 or the second resonant system 260 on the sensing element 400, the vibration characteristics of the acceleration sensor can be changed compared with the acceleration sensor without the first resonant system 210. Specifically, the action of the first resonant system 210 or the second resonant system 260 on the sensing element 400 can affect the mass, stiffness, and / or damping of the acceleration sensor, and the effect is equivalent to changing (e.g., reducing) the Q value of the first resonance peak of the sensing device containing the sensing element 400 relative to the Q value of the acceleration sensor without the first resonant system 210 or the second resonant system 260. In some embodiments, the existence of the first resonant system 210 or the second resonant system 260 can have a suppression effect on the resonance peak corresponding to the acceleration sensor in the sensing device, so that the Q value at the resonance peak in the frequency response curve is relatively low, and the frequency response curve is more flattened in the required frequency band (e.g., medium-low frequency, medium frequency, etc.).

[0147] Meanwhile, the first resonant system 210 or the second resonant system 260 can reduce external impact received by the sensing element 400 to protect the sensing element 400. For example, if a liquid or a liquid and bubbles are introduced into the cavity of the housing 110, when receiving an external impact load, the first resonant system 210 or the second resonant system 260 can improve the impact resistance reliability of the sensing device containing the sensing element 400. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load received by the sensing element 400 is greatly reduced, thereby protecting the sensing element 400 and prolonging its service life. In addition, due to the presence of stress during the processing of the sensing element 400, the device often deforms. By injecting a liquid and bubbles into the chamber, the deformation of the device can be corrected by using the gravity, surface tension, viscous force, etc. of the liquid, so that the sensing device has smaller deformation, more stable output, and is closer to the design effect.

[0148] In some embodiments, by adjusting the parameters of the acceleration sensor (for example, the internal structure, size, stiffness of the housing 110, and / or the mass, size, stiffness of the sensing element 400) and / or the parameters of the substance / structure forming the at least one resonant system (for example, the size, mass, stiffness, elasticity of the elastic rod, the type, density, viscosity, volume of the liquid, whether it is filled with bubbles, and the proportion, size, position, number of bubbles, etc.), the relevant parameters of the frequency response curve of the sensing device (for example, the relationship between the first resonant frequency and the at least one second resonant frequency, the corresponding peak height, Q value, the difference, ratio of the first resonant frequency and the second resonant frequency, the ratio of the peak value and the highest peak, etc.) can be changed, so as to achieve the purpose of adjusting the Q value of the sensing device, improving the sensitivity and reliability of the sensing device, or making the output gain of the sensing device more stable in the required frequency band (for example, low frequency).

[0149] In some embodiments, the dip between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 10 dBV, 20 dBV, 30 dBV, etc.) and the difference in sensitivity between the peak of the higher one of the resonant peaks corresponding to the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 0.05, 0.1, 0.2, etc.). The difference in frequency between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 20-3000 Hz, 20-2000 Hz, 50-2000 Hz, 50-1500 Hz, 80-1500 Hz, 100-1500 Hz, etc.) and / or the ratio of the difference to the first resonant frequency or the second resonant frequency is within a range (e.g., 0.02-0.7, 0.15-0.6) can result in a relatively flat frequency response curve between the resonant peaks corresponding to the first resonant frequency and the at least one second resonant frequency. The sensitivity of the sensor device including the sensing element 400 can be increased and stabilized within the second resonant frequency. For example, the increase in sensitivity can be within a range of 10 dBV-60 dBV, 20 dBV-50 dBV, 30 dBV-40 dBV, etc.

[0150] In some embodiments, the at least one resonant system can be a liquid containing bubbles. The bubbles can occupy a volume of the cavity by a percentage of 5%, 10%, 20%, 30%, 50%, 70%, 95%, etc. The bubbles can be small bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 2%-10%), medium-small bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 10%-20%), medium bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 20%-50%), large bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 50%-90%), etc. The number of bubbles can be one, two, three, four, or more. The bubbles can be located at different locations within the cavity (e.g., inside the sensing element 400). In some embodiments, the bubbles are located between the first moving electrode and the corresponding first stationary electrode (e.g., 418A and 419A or 418B and 419B) or between the second moving electrode and the corresponding second stationary electrode (e.g., 418C and 419C or 418D and 419D). In some embodiments, the bubbles are attached to the mass element 420 (e.g., the upper surface, the lower surface, and / or the side surface) or the first / second moving electrode disposed on the mass element 420 (e.g., the upper surface, the lower surface, or the side surface opposite to the first stationary electrode 419A of the first moving electrode 418A). In some embodiments, the bubbles are attached to at least one stationary electrode (e.g., the upper surface, the lower surface, or the side surface opposite to the first moving electrode 418A of the first stationary electrode 419A).

[0151] The frequency response curve of a sensing device comprising the sensing element 400 varies (e.g., the magnitude of the at least one second resonant frequency and the corresponding peak sensitivity vary) when the bubble is located at different positions within the cavity (e.g., inside the sensing element 400). In some embodiments, the sensitivity of the sensing device can be improved to some extent (e.g., 10-60 dBV, 10-40 dBV, 15-40 dBV, etc.) in the low or mid-low or mid-high frequency before band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) regardless of whether the bubble is attached to the sensing element 400 (e.g., attached to the at least one moving electrode and / or the fixed electrode) or not (e.g., located between the first moving electrode 418A and the corresponding first fixed electrode 419A). The magnitude of the improvement is also related to the size and / or position of the bubble.

[0152] In some embodiments, when the bubble is not attached to the sensing element 400 (e.g., located between the first moving electrode 418A and the corresponding first fixed electrode 419A), the sensitivity of the sensing device increases as the volume of the bubble increases. Exemplarily, the sensitivity of the sensing device containing a medium-small bubble is improved by about 5-30 dBV in the low or mid-low or mid-high frequency before band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to the sensing device containing a small bubble. The sensitivity of the sensing device containing a medium bubble is improved by about 5-30 dBV in the low or mid-low or mid-high frequency before band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to the sensing device containing a medium-small bubble.

[0153] Figures 5A-5D is an exemplary structural schematic of a sensing element 500 according to some embodiments of the present application.

[0154] As shown in Figures 5A-5D , the sensing element 500 comprises a substrate 514, a mass element 501 disposed above the substrate 514, and one or more detection capacitors for determining the magnitude of the external acceleration. The substrate 514 can be made of any suitable material, such as silicon, glass, etc. Figure 4A and 4B, and are not described in detail here. A supporting component (for example, a supporting rod, a supporting spring, a supporting bracket, etc., also referred to as a first supporting component) is provided on the substrate 514. The supporting component is used to support the mass element 501 above the substrate 514. In this embodiment, the supporting component may be an anchoring portion 502. The anchoring portion 502 can support the mass element 501 above the substrate 514. The mass element 501 can be connected to the supporting component by an elastic connecting unit (for example, an elastic beam, a spring, etc.). The elastic connecting unit extends along a first direction. In some embodiments, the midline (along the first direction) of the elastic connecting unit coincides with the midline of the mass element 501 in the first direction. In the second direction, the masses of the parts of the mass element 501 located on both sides of the elastic connecting unit are not equal.

[0155] In this embodiment, the elastic connection unit may be an elastic torsion beam 503. The mass element 501 is connected to the sidewalls of the anchor portion 502 via the elastic torsion beams 503 symmetrically disposed on both sides thereof, i.e., the two elastic torsion beams 503 are symmetrically distributed on both sides of the anchor portion 502. The anchor portion 502 may be located at the center (e.g., the structural center) of the mass element 501. The midline of the elastic torsion beam 503 in the longitudinal direction may coincide with the midline of the mass element 501.

[0156] In order to more clearly illustrate the structure of the sensor element 500, the first direction (X-axis direction) is set as Figure 5A The second direction (Y-axis direction) is perpendicular to the first direction and is located in the plane where the mass element 501 is located, and the third direction (Z-axis direction) is the length direction of the anchoring portion 502 (perpendicular to the XY plane).

[0157] The mass distribution of the mass element 501 is uneven. In some embodiments, with the elastic torsion beam 503 as the boundary, the mass of the mass element 501 on both sides of the elastic torsion beam 503 is not equal, that is, the mass of the mass element 501 on both sides of the elastic torsion beam 503 in the Y-axis direction is not equal. Figure 5A In the viewing direction, with the elastic torsion beam 503 as the boundary, the masses of the upper half and the lower half of the mass element 501 are not equal.

[0158] In one embodiment, to make the mass on both sides of the mass block not equal, the mass element 501 is provided with a weight-reducing hole 506 on one side. In some embodiments, the mass element 501 can be provided with a plurality of weight-reducing holes 506. The plurality of weight-reducing holes are arranged in a matrix. The weight-reducing hole 506 can be a through hole, which can be formed by etching during manufacturing. The weight-reducing hole 506 can also be a blind hole, which can be etched by setting a mask. In another embodiment, a counterweight can also be added to make the mass on both sides of the mass element 501 not equal.

[0159] For the sensing element 500, the anchor portion 502 is located at the structural center of the mass element 501, and the center line of the length direction of the elastic torsion beam 503 coincides with the center line of the mass element 501, and the mass on both sides of the mass element 501 is not equal, so that the moment on both sides of the mass element 501 is unbalanced. When there is an external acceleration input in the third direction (Z-axis direction), the mass element 501 can produce a seesaw-like motion with the anchor portion 502 as the fulcrum. When there is an external acceleration input in the first direction (X-axis direction), since the anchor portion 502 is located at the structural center of the mass element 501, the center line of the length direction of the elastic torsion beam 503 coincides with the center line of the X-axis direction of the mass element 501, and the mass on both sides of the X-axis center line of the mass element 501 is not equal, the mass element 501 can rotate with the anchor portion 502 as the fulcrum. When there is an external acceleration input in the second direction (Y-axis direction), since the anchor portion 502 is located at the structural center of the mass element 501, the center line of the length direction of the elastic torsion beam 503 coincides with the center line of the X-axis direction of the mass element 501, and the mass element 501 can move in the Y-axis direction.

[0160] In each direction (e.g., the first direction, the second direction, the third direction), the sensing element 500 can include at least one detection capacitor. In the direction, the sensing element 500 can include at least one moving electrode and at least one corresponding fixed electrode to form the detection capacitor in the direction to determine the acceleration magnitude in the direction. In some embodiments, the sensing element 500 can include at least two first direction fixed electrodes, at least two second direction fixed electrodes, and at least two third direction fixed electrodes disposed on the substrate. The at least two first direction fixed electrodes extend along the second direction and are distributed on both sides of the substrate position corresponding to the center line of the mass element 501 along the second direction, and are symmetric with respect to the center line axis of the second direction or symmetric with respect to the center of the anchor portion 502. The at least two second direction fixed electrodes can extend along the first direction and can be located on the center line of the mass element 501 along the second direction, and are symmetric with respect to the anchor portion 502. The third direction fixed electrodes can be disposed on both sides of the elastic torsion beam 503. The mass element 501 is provided with first direction moving electrodes, second direction moving electrodes, and third direction moving electrodes corresponding to the at least two first direction fixed electrodes, the at least two second direction fixed electrodes, and the at least two third direction fixed electrodes, respectively, to form first direction detection capacitors, second direction detection capacitors, and third direction detection capacitors, respectively.

[0161] In some embodiments, the at least two first direction fixed electrodes are not on the center line of the mass element 501 along the first direction. When two first direction fixed electrodes are located on the center line of the mass element 501 along the first direction, the two first direction detection capacitors formed correspondingly increase or decrease at the same time, and cannot form a differential capacitor structure that can output a first direction acceleration change signal. Thus, each first direction fixed electrode includes two first direction fixed electrode units arranged in parallel. The first direction moving electrode corresponding to the first direction fixed electrode includes two first direction moving electrode units. The two first direction moving electrode units and the two first fixed electrode units form a first direction differential capacitor structure. Each second direction fixed electrode includes two second direction fixed electrode units arranged in parallel. The second direction moving electrode corresponding to the second direction fixed electrode includes two second direction moving electrode units. The two second direction moving electrode units and the two second direction fixed electrode units form a second direction differential capacitor structure.

[0162] In some embodiments, the at least two first direction fixed electrodes are located on the middle line of the mass element 501 along the first direction. Each of the first direction fixed electrodes comprises two first direction fixed electrode units arranged in parallel. The first direction moving electrodes corresponding to the first direction fixed electrodes comprise two first direction moving electrode units. The two first direction moving electrode units and the two first direction fixed electrode units form a first direction differential capacitive structure. Each of the second direction fixed electrodes comprises two second direction fixed electrode units arranged in parallel. The second direction moving electrodes corresponding to the second direction fixed electrodes comprise two second direction moving electrode units. The two second direction moving electrode units and the two second direction fixed electrode units form a second direction differential capacitive structure. Different from the above-mentioned at least two first direction fixed electrodes not being located on the middle line of the mass element along the first direction, when the at least two first direction fixed electrodes are located on the middle line of the mass element along the first direction, the first direction fixed electrode unit on one side of at least one of the at least two first direction fixed electrodes is electrically connected to the first direction fixed electrode unit on the opposite side of another first direction fixed electrode which is axially symmetric to the at least one first direction fixed electrode about the middle line of the mass element along the second direction.

[0163] Exemplarily, as shown in FIG. 5, the substrate 514 is provided with the third direction fixed electrodes 513 and 512 distributed on both sides of the elastic torsion beam 503. Correspondingly, the mass element 501 is provided with the third direction moving electrodes 504 and 505. The third direction moving electrodes 504 and 505 and the third direction fixed electrodes 513 and 512 form different third direction detection capacitors, respectively. The third direction fixed electrodes 513 and 512 can be the capacitor electrode plate structures well known to those skilled in the art, which can be fixed on the substrate 514. The third direction moving electrodes 504 and 505 can also be the capacitor electrode plate structures well known to those skilled in the art. In some embodiments, the third direction moving electrodes 504 and 505 are part of the mass element 501. For example, the third direction moving electrodes 504 and 505 are the side walls on opposite sides of the mass element 501. Figure 5C 5D Exemplarily, as shown in FIG. 5, the substrate 514 is provided with the third direction fixed electrodes 513 and 512 distributed on both sides of the elastic torsion beam 503. Correspondingly, the mass element 501 is provided with the third direction moving electrodes 504 and 505. The third direction moving electrodes 504 and 505 and the third direction fixed electrodes 513 and 512 form different third direction detection capacitors, respectively. The third direction fixed electrodes 513 and 512 can be the capacitor electrode plate structures well known to those skilled in the art, which can be fixed on the substrate 514. The third direction moving electrodes 504 and 505 can also be the capacitor electrode plate structures well known to those skilled in the art. In some embodiments, the third direction moving electrodes 504 and 505 are part of the mass element 501. For example, the third direction moving electrodes 504 and 505 are the side walls on opposite sides of the mass element 501.

[0164] In a specific embodiment, the third direction fixed electrodes 513 and 512 are the lower electrodes of the third direction detection capacitors, respectively, and the third direction moving electrodes 504 and 505 are located at the lower end surface of the edge position of the mass element 501 as the upper electrodes of the third direction detection capacitors. The third direction fixed electrodes 513 and 512 are symmetric to the elastic torsion beam 503 in the Y-axis direction, so that the two third direction detection capacitors form a differential capacitive structure.

[0165] When there is an external acceleration input in the third direction (i.e., the Z-axis direction), for example, referring to FIG. 5, the third direction detection capacitors are changed. The third direction detection capacitors are changed by the same amount as the amount of change of the third direction detection capacitors caused by the external acceleration input in the third direction. The third direction detection capacitors are changed by the same amount as the amount of change of the third direction detection capacitors caused by the external acceleration input in the third direction. Figure 5C ​When there is an upward acceleration input, the distance between the third direction movable electrode 504 on the side provided with the weight-reducing hole 506 and the third direction fixed electrode 513 becomes larger, and the distance between the third direction movable electrode 505 on the side with more mass and the third direction fixed electrode 512 becomes smaller, so the capacitance of the third direction detection capacitor formed by the third direction movable electrode 504 and the third direction fixed electrode 513 becomes smaller, and the capacitance of the third direction detection capacitor formed by the third direction movable electrode 505 and the third direction fixed electrode 512 becomes larger, thus the two third direction detection capacitors form a third direction differential capacitor structure.

[0166] Conversely, referring to Figure 5D , when there is an upward acceleration input, the distance between the third direction movable electrode 504 on the side provided with the weight-reducing hole 506 and the third direction fixed electrode 513 becomes larger, and the distance between the third direction movable electrode 505 on the side with more mass and the third direction fixed electrode 512 becomes smaller, so the capacitance of the third direction detection capacitor formed by the third direction movable electrode 504 and the third direction fixed electrode 513 becomes smaller, and the capacitance of the third direction detection capacitor formed by the third direction movable electrode 505 and the third direction fixed electrode 512 becomes larger, thus the two third direction detection capacitors form a third direction differential capacitor structure.

[0167] In one specific embodiment, referring to Figure 5A , Figure 5C and Figure 5D , the weight-reducing hole 506 is arranged on the mass element 501 at the position of the third direction movable electrode 504, so that the mass difference on both sides of the mass element 501 is larger, thus increasing the deflection amplitude of the mass element 501, and thus increasing the sensitivity of the third direction detection capacitor. Since the weight-reducing hole 506 is arranged at the position of the third direction movable electrode 504, the normal area of the third direction movable electrode 504 and the third direction fixed electrode 513 is reduced. To ensure the consistency of the above two third direction detection capacitors, a process hole corresponding to the weight-reducing hole 506 on the third direction movable electrode 504 can be arranged on the third direction fixed electrode 512, so that the normal area of the third direction movable electrode 504 and the third direction fixed electrode 513 is consistent with the normal area of the third direction movable electrode 505 and the third direction fixed electrode 512, that is, the consistency of the above two third direction detection capacitors is ensured.

[0168] As Figure 5A and 5BAs shown, a second direction fixed electrode 508 and 507 are also disposed on the substrate 514, respectively. The second direction fixed electrodes 508 and 507 are located on the Y-axis center line of the mass element 501, and symmetrically distributed on both sides of the anchor portion 502; correspondingly, the mass element 501 is provided with two second direction movable electrodes. The two second direction movable electrodes and the second direction fixed electrodes 508 and 507 form two second direction detection capacitors. The second direction fixed electrodes 508 and 507 can adopt the capacitor plate mechanism well known to those skilled in the art, which is fixed on the substrate 514; the above-mentioned two second direction movable electrodes can also adopt the capacitor plate mechanism well known to those skilled in the art. In some embodiments, the above-mentioned two second direction movable electrodes can be part of the mass element 501, for example, the above-mentioned two second direction movable electrodes can be the side wall of the mass element 501. In a specific embodiment, the mass element 501 is provided with a plurality of hollow matching holes 511 at the corresponding positions, and the second direction fixed electrodes 508 and 507 are extended into the matching holes 511. The side wall of the matching hole 511 can be used as a movable electrode, which respectively forms two second direction detection capacitors with the second direction fixed electrodes 508 and 507, thereby improving the temperature characteristics of the chip and the ability to resist external interference.

[0169] The second direction fixed electrodes 508 and 507 extend along the first direction (i.e. the X-axis direction) and are parallel to the elastic torsion beam 503. When there is an external acceleration input in the second direction (i.e. the Y-axis direction), due to the action of the elastic torsion beam, the mass element 501 moves in the Y-axis direction, thereby causing the distance between the second direction fixed electrode 508 and the corresponding second direction movable electrode to increase or decrease, and the distance between the second direction fixed electrode 507 and the corresponding second direction movable electrode to decrease or increase, so that the two second direction detection capacitors form a second direction differential capacitor structure.

[0170] For the second direction fixed electrodes 508 and 507, when there is an external acceleration input in the first direction (i.e. the X-axis direction), the mass element 501 rotates clockwise or counterclockwise with the anchor portion 502 as the fulcrum, thereby causing the distance between the second direction fixed electrode 508 and the corresponding second direction movable electrode to increase or decrease at the same time as the distance between the second direction fixed electrode 507 and the corresponding second direction movable electrode, and the change is consistent, and through the differential capacitor structure, the changing signal can be differentiated, at this time, the second direction differential capacitor structure formed by the two second direction detection capacitors does not output the changing capacitor signal, so as to prevent the second direction detection capacitor from outputting the acceleration signal in the first direction.

[0171] In some embodiments, the second direction fixed electrode 508 includes second fixed electrode units 508a and 508b arranged in parallel. The second fixed electrode units 508a and 508b are fixed on the substrate 514 and extend into the matching hole 511 formed on the mass element 501. The two opposite side walls of the matching hole 511 serve as the moving electrode units of the second direction moving electrode, and form a pair of differential capacitance structures with the second fixed electrode units 508a and 508b, further improving the detection accuracy of the Y-axis acceleration signal. Based on the same principle, the second direction fixed electrode 507 includes second fixed electrode units 507a and 507b arranged in parallel. The second fixed electrode units 507a and 507b are fixed on the substrate 514 and extend into the matching hole 511 formed on the mass element 501. The two opposite side walls of the matching hole 511 serve as the moving electrode units of the second direction moving electrode, and form a pair of differential capacitance structures with the second fixed electrode units 507a and 507b, further improving the detection accuracy of the Y-axis acceleration signal.

[0172] The substrate 514 is also provided with first direction fixed electrodes 509 and 510. Correspondingly, the mass element 501 is provided with two first direction moving electrodes. The two first direction moving electrodes form two first direction detection capacitances with the first direction fixed electrodes 509 and 510. The first direction fixed electrodes 509 and 510 can be the capacitor plate structure known to those skilled in the art, which can be fixed on the substrate 514 through an anchor. Among them, the first direction fixed electrode 509 and the corresponding first direction moving electrode can form a side capacitance type first direction detection capacitance, and the first direction fixed electrode 510 and the corresponding first direction moving electrode can also form a side capacitance type first direction detection capacitance. Of course, the above two first direction detection capacitances can also be an up-down plate type capacitor structure. In some embodiments, the above two first direction moving electrodes can be the side wall of the mass element 501. The mass element 501 is provided with a hollow matching hole 511 at the corresponding position. The first direction fixed electrodes 509 and 510 are fixed on the substrate 514 and extend into the corresponding matching hole 511. At this time, the hole wall of the matching hole 511 can serve as the first direction moving electrode, and form two first direction detection capacitances with the first direction fixed electrodes 509 and 510, thereby improving the temperature characteristics of the chip and the ability to resist external interference.

[0173] In a specific embodiment, reference is made to Figure 5B, the first direction fixed electrodes 509 and 510 can extend along the Y-axis direction, i.e. the length direction of the first direction fixed electrodes 509 and 510 is in the Y-axis direction. When there is an external acceleration input in the second direction (i.e. the Y-axis direction), the mass element 501 translates in the Y-axis direction, while the distance and relative area between the first direction fixed electrode 509 and the corresponding first direction movable electrode do not change, and the distance and relative area between the first direction fixed electrode 510 and the corresponding first direction movable electrode do not change, i.e. the two first direction detection capacitances do not output a change signal of the capacitance, so as to prevent the first direction detection capacitances from outputting a Y-axis acceleration signal.

[0174] The first direction fixed electrodes 509 and 510 are symmetric about the Y-axis direction of the mass element 501 or symmetric about the center of the anchor portion 502. When there is an external acceleration input in the first direction (i.e. the X-axis direction), the mass element 501 rotates clockwise or counterclockwise about the anchor portion 502 as the fulcrum, so that the distance between the first direction fixed electrode 509 and the corresponding first direction movable electrode increases or decreases, and the distance between the first direction fixed electrode 510 and the corresponding first direction movable electrode decreases or increases, so that the two first direction detection capacitances can jointly constitute a differential capacitance structure of the first direction. Among them, the first direction fixed electrodes 509 and 510 cannot be arranged on the Y-axis direction of the mass element 501. Because when the two first direction fixed electrodes 509 and 510 are arranged on the Y-axis direction of the mass element 501, the two first direction detection capacitances formed by the two first direction fixed electrodes 509 and 510 increase or decrease at the same time, and the two first direction detection capacitances cannot constitute a differential capacitance structure that can output an X-axis direction acceleration change signal.

[0175] In some embodiments, with reference to Figure 5B The first direction fixed electrode 509 includes first fixed electrode units 509a and 509b arranged in parallel. The first fixed electrode units 509a and 509b are fixed on the substrate and extend into the matching hole 511 formed on the mass element 501. The two opposite side walls of the matching hole 511 serve as movable electrode units of the first direction movable electrode, and form a pair of differential capacitance structures with the first fixed electrode units 509a and 509b, further improving the detection accuracy of the X-axis acceleration signal. Based on the same principle, the first direction fixed electrode 510 includes first fixed electrode units 510a and 510b arranged in parallel. The first fixed electrode units 510a and 510b are fixed on the substrate 514 and extend into another matching hole 511 formed on the mass element 501. The two opposite side walls of the matching hole 511 serve as movable electrode units of the first direction movable electrode, and form a pair of differential capacitance structures with the first fixed electrode units 510a and 510b, further improving the detection accuracy of the X-axis acceleration signal.

[0176] In another specific embodiment, with reference to Figure 5AThe first direction fixed electrodes 509 and 510 can extend along the X-axis direction. The first direction fixed electrodes 509 and 510 can be symmetrically distributed on both sides of the Y-axis centerline of the mass element 501, or symmetrically distributed on both sides of the Y-axis centerline of the mass element 501 and opposite the center of the anchor portion 502. When the mass element 501 rotates clockwise or counterclockwise about the anchor portion 502 as a fulcrum, the capacitance changes of the two first direction detection capacitors are completely opposite, and together constitute a first direction differential capacitor structure.

[0177] Further, the first direction fixed electrodes 509 and 510 are located on the X-axis centerline of the mass element 501 and are symmetric about the center of the anchor portion 502, so that when subjected to acceleration in the X-axis direction, the capacitance changes of the two first direction detection capacitors are the same. In the present embodiment, the first direction fixed electrode 509 can adopt the structure of the first fixed electrode units 509a and 509b described above, and the first direction fixed electrode 510 can also adopt the structure of the first fixed electrode units 510a and 510b described above. At the same time, one of the first fixed electrode units 509a or 509b on one side of the first direction fixed electrode 509 is connected together with the first fixed electrode unit 510a or 510b on the opposite side of the first direction fixed electrode 510.

[0178] Reference Figure 5Aview direction, the first fixed electrode unit 509a is located at the lower side, and the first fixed electrode unit 509b is located at the upper side; the first fixed electrode unit 510a is located at the lower side, and the first fixed electrode unit 510b is located at the upper side. At this time, the first fixed electrode unit 509b needs to be connected with the first fixed electrode unit 510a, and the first fixed electrode unit 509a needs to be connected with the first fixed electrode unit 510b, so that the first fixed electrode unit 509b, the movable electrode unit corresponding to the first fixed electrode unit 509b, the first fixed electrode unit 510a, and the movable electrode unit corresponding to the first fixed electrode unit 510a together form a first direction differential capacitor structure, and the first fixed electrode unit 509a, the movable electrode unit corresponding to the first fixed electrode unit 509a, the first fixed electrode unit 510b, and the movable electrode unit corresponding to the first fixed electrode unit 510b together form another first direction differential capacitor structure. When an external acceleration in the second direction (i.e., the Y-axis direction) is input, the mass element 501 moves in the Y-axis direction, the distance between the first fixed electrode unit 509b and the movable electrode unit corresponding to the first fixed electrode unit 509b increases or decreases, and the distance between the first fixed electrode unit 510a and the movable electrode unit corresponding to the first fixed electrode unit 510a increases or decreases, and the change amounts are consistent, so that the differential capacitor structure can differentiate the changed capacitor signal at this time. Based on the same principle, the differential capacitor formed by the first fixed electrode unit 509a, the movable electrode unit corresponding to the first fixed electrode unit 509a, the first fixed electrode unit 510b, and the movable electrode unit corresponding to the first fixed electrode unit 510b can also differentiate the changed capacitor signal at this time, so as to prevent the first direction detection capacitor from outputting the Y-axis acceleration signal.

[0179] The sensing element 500 integrates the acceleration detection structures in three dimensions on a single structure, the center of the structure is the anchor point of the movable mass element 501, and the mass element 501 is connected to the anchor point through the elastic torsion beam 503, so that the mass element 501 moves in each dimension when an acceleration input is input, thereby realizing the detection of the acceleration signal in each direction. When an acceleration input is input in the first direction, the mass element 501 rotates around the anchor point to realize the detection of the X-axis direction acceleration; when an acceleration input is input in the second direction, the mass element 501 moves in the Y-axis direction to realize the detection of the Y-axis direction acceleration; and when an acceleration input is input in the third direction, the mass element 501 twists in the X-axis direction around the elastic beam 503 to realize the detection of the Z-axis direction acceleration.

[0180] A sensing device (e.g., sensing device 200 or 250) can be constructed by coupling at least one resonant system to the acceleration sensor (e.g., between the housing 110 and the sensing element 500). The at least one resonant system can include Figure 2A and 2B a first resonant system 210 as shown in FIGS. 1A and 1B, or Figure 2C and 2D a second resonant system 260 as shown in FIGS. 2A and 2B.

[0181] In some embodiments, the first resonant system 210 and the second resonant system 260 can include a liquid. Exemplarily, the first resonant system 210 can be a liquid with a specific density and viscosity. For example, the liquid can be a silicone oil with a density of 0.94 kg / m3, and a kinematic viscosity of 0.5 cSt, 1 cSt, 5 cSt, 10 cSt, 100 cSt, 200 cSt, 1000 cSt, etc. The liquid can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The first resonant system 210 can be coupled to the sensing element 500 by filling the cavity of the acceleration sensor with the liquid, such that the sensing element 500 is completely immersed in the liquid. The second resonant system 210 can be a liquid with air bubbles, for example, a silicone oil with air bubbles, where the air bubbles can occupy any value between 5% and 95% of the volume of the cavity. The number of air bubbles can be one, two, three, four, or more. The liquid can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system, and the air bubbles can be equivalent to a spring (Km3) and damping (Rm3) system. The second resonant system 260 can be coupled to the sensing element 500 by partially filling the cavity of the acceleration sensor with the liquid, partially filling air bubbles (e.g., air bubbles formed when air is not expelled from the cavity when filling the cavity with the liquid, air bubbles formed by an air bladder, and / or air bubbles formed by applying a hydrophobic coating to the sensing element 500), such that the sensing element 500 is at least partially immersed in the liquid.

[0182] In some embodiments, the first resonant system 210 and the second resonant system 260 can comprise an elastic structure. Exemplarily, the first resonant system 210 can be an elastic structure with mass (e.g., an elastic rod, an elastic sheet, an elastic block, an elastic net, etc.), or a combination of a lightweight elastic structure (e.g., a lightweight spring, a lightweight elastic rod, etc.) and a mass unit. The elastic structure with mass or the combination of the lightweight elastic structure and the mass unit can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The two ends of the elastic structure can be connected between the housing 110 and the sensing element 500 (e.g., one or more positions on the mass element 501), so as to couple the first resonant system 210 with the sensing element 500. The second resonant system 260 can be a combination of a lightweight elastic rod and / or a spring and a relatively massive elastic rod. The relatively massive elastic rod can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The lightweight elastic rod and / or the spring can be equivalent to a spring (Km3) and a damping (Rm3) system. The two ends of the elastic rod and / or the spring can be fixedly connected between the housing 110 and the sensing element 500 (e.g., one or more positions on the mass element 501), so as to couple the second resonant system 260 with the sensing element 500.

[0183] Due to the existence of the second resonant frequency corresponding to the first resonant system 210 or the second resonant system 260, the frequency response curve of the sensing device containing the sensing element 500 can be improved in a certain frequency band (e.g., low frequency, medium-low frequency, medium frequency, medium-high frequency, and / or high frequency), so that the sensitivity of the acceleration sensor is improved compared with an acceleration sensor without the first resonant system 210 or the second resonant system 260. In addition, due to the action of the first resonant system 210 or the second resonant system 260 on the sensing element 500, the vibration characteristics of the acceleration sensor can be changed compared with the acceleration sensor without the first resonant system 210. Specifically, the action of the first resonant system 210 or the second resonant system 260 on the sensing element 500 can affect the mass, stiffness, and / or damping of the acceleration sensor, and the effect is equivalent to changing (e.g., reducing) the Q value of the first resonance peak of the sensing device containing the sensing element 500 relative to the Q value of the acceleration sensor without the first resonant system 210 or the second resonant system 260. In some embodiments, the existence of the first resonant system 210 or the second resonant system 260 can have a suppression effect on the resonance peak corresponding to the acceleration sensor in the sensing device, so that the Q value at the resonance peak in the frequency response curve is relatively low, and the frequency response curve in the required frequency band (e.g., medium-low frequency, medium frequency, etc.) is more flattened.

[0184] Meanwhile, the first resonant system 210 or the second resonant system 260 can reduce external impact on the sensing element 500 to protect the sensing element 500. For example, if a liquid or a liquid and bubbles are introduced into the cavity of the housing 110, when receiving an external impact load, the first resonant system 210 or the second resonant system 260 can improve the impact resistance reliability of the sensing device containing the sensing element 500. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load on the sensing element 500 is greatly reduced, thereby protecting the sensing element 500 and prolonging its service life. In addition, due to the presence of stress during the processing of the sensing element 500, the device often deforms. By injecting a liquid and bubbles into the chamber, the deformation of the device can be corrected by using the gravity, surface tension, viscous force, etc. of the liquid, so that the deformation of the sensing device is smaller, the output is more stable, and the design effect is closer.

[0185] In some embodiments, by adjusting the parameters of the acceleration sensor (for example, the internal structure, size, stiffness of the housing 110, and / or the mass, size, stiffness of the sensing element 500) and / or the parameters of the substance / structure forming the at least one resonant system (for example, the size, mass, stiffness, elasticity of the elastic rod, the type, density, viscosity, volume of the liquid, whether it is filled with bubbles, and the proportion, size, position, number of bubbles, etc.), the relevant parameters of the frequency response curve of the sensing device (for example, the relationship between the first resonant frequency and the at least one second resonant frequency, the corresponding peak height, Q value, the difference, ratio of the first resonant frequency and the second resonant frequency, the ratio of the peak value and the highest peak, etc.) can be changed, so as to achieve the purpose of adjusting the Q value of the sensing device, improving the sensitivity, reliability of the sensing device, or making the output gain of the sensing device more stable in the required frequency band (for example, low frequency).

[0186] In some embodiments, the dip between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 10 dBV, 20 dBV, 30 dBV, etc.) of the difference in sensitivity of the peak value of the higher peak of the resonance peaks corresponding to the first resonant frequency and the at least one second resonant frequency, and the ratio of the difference in sensitivity to the peak value of the higher peak is no more than a threshold value (e.g., 0.05, 0.1, 0.2, etc.). The difference in frequency between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 20-3000 Hz, 20-2000 Hz, 50-2000 Hz, 50-1500 Hz, 80-1500 Hz, 100-1500 Hz, etc.) and / or the ratio of the difference to the first resonant frequency or the second resonant frequency is within a range (e.g., 0.02-0.7, 0.15-0.6) that can result in a relatively flat frequency response curve between the resonance peaks corresponding thereto. The sensitivity of the sensing device including the sensing element 500 is increased and relatively stable within the second resonant frequency. For example, the increase in sensitivity can be within a range of 10 dBV-60 dBV, 20 dBV-50 dBV, 30 dBV-40 dBV, etc.

[0187] In some embodiments, the at least one resonant system can be a liquid containing bubbles. The bubbles can occupy 5%, 10%, 20%, 30%, 50%, 70%, 95%, or any value in between of the volume of the cavity. The bubbles can be small bubbles (e.g., bubbles occupying 2%-10% of the volume of the cavity), medium-small bubbles (e.g., bubbles occupying 10%-20% of the volume of the cavity), medium bubbles (e.g., bubbles occupying 20%-50% of the volume of the cavity), large bubbles (e.g., bubbles occupying 50%-90% of the volume of the cavity), or the like. The number of bubbles can be 1, 2, 3, 4, or more. The bubbles can be located at different locations within the cavity (e.g., inside the sensing element 500). In some embodiments, the bubbles are located between the first direction moving electrode (e.g., the side wall of the mating hole 511 located on the center line of the mass element 501 along the second direction) and the corresponding first direction stationary electrode (e.g., 509 or 510), between the second direction moving electrode (e.g., the side wall of the mating hole 511 located on both sides of the center line of the mass element 501 along the second direction, and symmetric about the center line along the second direction or symmetric with respect to the center of the anchor 502) and the corresponding second direction stationary electrode (e.g., 507 and 508), or between the third direction moving electrode and the corresponding third direction stationary electrode (e.g., 504 and 513, 505 and 512). In some embodiments, the bubbles are attached to the mass element 420 (e.g., the upper surface, the lower surface, and / or the side surface) or the first / second / third direction moving electrode provided on the mass element 420 (e.g., the side of the first direction moving electrode opposite to the first direction stationary electrode (e.g., 509 or 510), the side of the second direction moving electrode opposite to the second direction stationary electrode (e.g., 507 or 508), or the side of the third direction moving electrode (e.g., 504 or 505) opposite to the third direction stationary electrode (e.g., 513 or 512)). In some embodiments, the bubbles are attached to at least one stationary electrode (e.g., the side of the first direction stationary electrode (e.g., 509 or 510) opposite to the first direction moving electrode, the side of the second direction stationary electrode (e.g., 507 or 508) opposite to the second direction moving electrode, or the side of the third direction stationary electrode (e.g., 513 or 512) opposite to the third direction moving electrode (e.g., 504 or 505)).

[0188] The frequency response curve of a sensing device comprising the sensing element 500 varies (e.g., the magnitude of the at least one second resonant frequency and the corresponding peak sensitivity vary) when the bubble is located at different positions within the cavity (e.g., inside the sensing element 500). In some embodiments, the sensitivity of the sensing device can be improved to some extent (e.g., 10-60 dBV, 10-40 dBV, 15-40 dBV, etc.) in the low or mid-low or mid-high frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) regardless of whether the bubble is attached to the sensing element 500 (e.g., attached to the at least one moving electrode and / or the fixed electrode) or not (e.g., located between the first direction moving electrode (e.g., the sidewall of the mating hole 511) and the corresponding first direction fixed electrode (e.g., 509 or 510)). The magnitude of the improvement is also related to the size and / or position of the bubble.

[0189] In some embodiments, the sensitivity of the sensing device increases as the volume of the bubble increases when the bubble is not attached to the sensing element 500 (e.g., located between the first direction moving electrode (e.g., the sidewall of the mating hole 511) and the corresponding first direction fixed electrode (e.g., 509 or 510)). Exemplarily, the sensitivity of the sensing device comprising a medium-small bubble can be improved by about 5-30 dBV in the low or mid-low or mid-high frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to the sensing device comprising a small bubble. The sensitivity of the sensing device comprising a medium bubble can be improved by about 5-30 dBV in the low or mid-low or mid-high frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to the sensing device comprising a medium-small bubble.

[0190] Figures 6A-6E is an exemplary structural schematic of a sensing element 600 according to some embodiments of the present application.

[0191] The sensing element 600 can comprise a substrate 611 and a detection assembly 620 (e.g., a mass element, at least one moving electrode disposed on the mass element, and at least one fixed electrode fixed on the substrate) disposed on the substrate. The substrate 611 can be the same as or similar to the substrate in the sensing element 500, and thus will not be described again here. As shown in FIG. 6, the detection assembly 620 can be disposed on the substrate 611. Figures 4A-5D The substrate 611 can be the same as or similar to the substrate in the sensing element 500, and thus will not be described again here. As shown in FIG. 6, the detection assembly 620 can be disposed on the substrate 611. Figure 6AAs shown, the detection assembly 620 can include a mass element 621, a support member (e.g., a support rod, a support spring, a support bracket, etc., also referred to as a second support member), and a coupling member 623. In this embodiment, the support member is a support rod 622. The mass element 621 is connected to the substrate 611 by the support rod 622.

[0192] The mass element 621 can be circular, polygonal, etc. In some embodiments, when the mass element 621 is polygonal, the number of sides is greater than or equal to 4, e.g., the mass element 621 can be pentagonal, hexagonal, octagonal, etc. The support rod 622 can be deformable. For example, the support rod 622 can be an elongated cylinder or prism. Under the action of an external acceleration or force, the support rod 622 can be elastically deformed. In some embodiments, the center of the mass element 621 is connected to one end of the support rod 622. The coupling member 623 is connected to the substrate and surrounds the mass element 621. A gap is provided between the coupling member 623 and the mass element 621. In some embodiments, the width of the gap is uniform. In some embodiments, the width of the gap can not be uniform in at least one direction. The coupling member 623 and the mass element 621 can form at least one detection capacitor. Assuming that the sensing element 600 is placed on a horizontal plane, if the sensing element 600 moves horizontally, the support rod 622 is subjected to an external force corresponding to the direction of movement, and the support rod 622 is deformed under the action of the external force, thereby causing the mass element 621 to move relative to the substrate 611 and the coupling member 623, resulting in a change in the distance between the mass element 621 and the coupling member 623, and thus a change in the capacitance in the direction of movement. According to the changed capacitance, the acceleration in the direction of movement can be determined. In some embodiments, the materials of the components in the detection assembly 620 can be silicon-based materials doped with other elements. For example, the materials of the components in the detection assembly 620 can be silicon-based materials doped with boron. At this time, the entire mass element 621 can serve as a movable electrode, and the coupling member 623 can serve as a fixed electrode. It should be noted that, in some embodiments, the mass element 621 can also include a conductive layer (e.g., a conductive layer provided on the upper and lower surfaces of the mass element 121) to form the movable electrode. Similarly, the coupling member 623 can also include a conductive layer to form the fixed electrode.

[0193] In some embodiments, the width of the gap between the coupling member 623 and the mass element 621 is uniform, at which time the shape of the coupling member 623 that is wrapped around is the same as the shape of the mass element 621, and the shape of the inner wall of the coupling member is the same as the shape of the outer wall of the mass element 621. Exemplarily, as shown in FIG. 6A, the coupling member 623 is a circular ring, and the mass element 621 is a circular disk. In some embodiments, the width of the gap between the coupling member 623 and the mass element 621 is not uniform in at least one direction. Exemplarily, as shown in FIG. 6B, the coupling member 623 is a polygonal ring, and the mass element 621 is a polygonal disk. In some embodiments, the coupling member 623 can be a polygonal ring, and the mass element 621 can be a circular disk. In some embodiments, the coupling member 623 can be a circular ring, and the mass element 621 can be a polygonal disk. Figure 6BAs shown, the mass element 621 is circular, and the coupling element 623 is an annular shape concentric with the circular shape. In other embodiments, the mass element 621 can be a hexagonal shape, in which case the inner wall of the coupling element 623 is hexagonal, and the sides of the inner wall of the coupling element 623 are parallel to the sides of the outer wall of the mass element 621.

[0194] In some embodiments, a plurality of through holes are further provided on the substrate 611. A conductive element 614 is provided in the through holes, for connecting the components of the detection assembly 620 to an external circuit (e.g., an integrated chip, etc.). The conductive element 614 can be metal filled in the through holes, a wire, etc. Since the material of the detection assembly 620 is borosilicate material, the conductive element 614 can be electrically connected to the coupling element 623 and the support rod 622. The support rod 622 is further electrically connected to the mass element 621. By energizing the coupling element 623 and the support rod 622 through a power supply, the coupling element 623 and the mass element 621 form a detection capacitor.

[0195] Referring to Figure 6B When there is an external acceleration input in the Y-axis direction, the acceleration is ay. The coupling element 623 is fixedly connected to the substrate 611. The mass element 621 has a large mass and is affected by inertia, causing the support rod 622 to elastically deform and bend to a certain extent, resulting in a decrease in the distance d between the mass element 621 and the coupling element 623 in the acceleration direction. The mass element 621 acts as a moving electrode, and the coupling element 623 acts as a fixed electrode. As the distance between them decreases, the capacitance C1 of the detection capacitor increases. The size of the capacitance C1 is inversely proportional to the distance d between the mass element 621 and the coupling element 623. By measuring the size of the capacitance C1, the size of the acceleration can be determined. Based on the above method, the acceleration ax in the X-axis direction, the acceleration a45° in the direction at a 45° angle with the X-axis, etc. can be measured. Since the mass element 621 is a circular structure, accelerations in any direction can be measured, achieving 360° omnidirectional measurement. When the mass element 621 is a polygon, and the number of sides of the polygon is greater than or equal to four, the sensing element 600 can detect accelerations in more than four directions. For example, when the mass element 621 is a pentagon, the sensing element 600 can detect accelerations in five directions.

[0196] The sensing element 600 is accommodated in a cavity formed by a housing. The housing 610 can include an upper housing 612 and a substrate 611. In some embodiments, the upper housing 612 and the substrate 611 are both silicon substrates. The upper housing 612 and the substrate 611 cooperatively form a first cavity 613. In some embodiments, the housing 610 further includes an external circuit, e.g., an integrated chip. The integrated chip is electrically connected to the support rod 622 and the coupling element 623, respectively. The integrated chip can calculate the capacitance between the mass element 621 and the coupling element 623. The integrated chip can be provided on the outer surface of the upper housing 612. Figure 6CThe integrated chip 630 is disposed on the outer surface of the upper housing 612. The integrated chip 630 is electrically connected to the support rod 622 and the coupling member 623 through the conductive element 614. The support rod 622 is further electrically connected to the mass element 621. In this embodiment, the integrated chip 630 is attached to the upper housing 612, so that the size of the acceleration sensor is consistent with the size of the chip, thereby reducing the size of the acceleration sensor.

[0197] In some embodiments, referring to Figure 6D The acceleration sensor is further provided with a cover 640. The cover 640 is disposed on the outer surface of the housing 610, i.e. the cover 640 is disposed on the outer surface of the upper housing 612, thereby forming a second cavity 641 accommodating the integrated chip 630. The cover 640 is used to protect the integrated chip 630 from external damage. In some embodiments, the material of the cover 640 is silicon. In some embodiments, the material of the cover 640 can also be metal, plastic, etc.

[0198] In some embodiments, referring to Figure 6E The outer surface of the substrate 611 is further provided with a plurality of pins 615, each pin 615 being connected to the conductive element 614, so that the acceleration sensor can be electrically connected to external devices or electronic components (such as printed circuit board, PCB) through the pins 615.

[0199] In some embodiments, the acceleration sensor and its internal components (such as the detection assembly 620) can be cut by wafer-level processing. The housing 110 can be square, i.e. the front view of the acceleration sensor is square. The acceleration sensor prepared by wafer-level processing has a smaller size.

[0200] Figure 7A According to some embodiments of the present application, an exemplary flow 705 of a preparation method of an acceleration sensor containing a sensing element 600 is provided.

[0201] In step 710, a doped silicon (such as boron-doped silicon) layer of a manufacturing silicon substrate is etched to etch a detection assembly on a single crystal silicon layer of the manufacturing silicon substrate, the detection assembly including a support rod, a mass element connected to the support rod, and a coupling member wrapping the mass element and having a gap between the mass element and the coupling member.

[0202] In some embodiments, the gap between the mass element and the coupling member is equal in width. The mass element is circular or polygonal. When the mass element is polygonal, the number of vertices or the number of sides is greater than or equal to four.

[0203] In the embodiment, the manufacturing substrate includes a single crystal silicon layer with a first thickness and a doped silicon (e.g., boron-doped silicon) layer with a second thickness. The single crystal silicon layer with the first thickness can serve as a substrate, and the detection component can be etched on the doped silicon layer with the second thickness. For example, the detection component can be etched on the doped silicon layer by a deep reactive ion etching technique. Specifically, a manufacturing substrate needs to be prepared first. The process of preparing the manufacturing substrate includes taking a single crystal silicon wafer with a certain thickness, and then using an ion implantation technique to implant boron ions into the single crystal silicon wafer, so that the boron ions are doped between silicon atoms, thereby forming a doped silicon layer with the second thickness, and the layer of silicon atoms that are not implanted with boron ions is the single crystal silicon layer. After the manufacturing substrate is prepared, a first mask is arranged on the manufacturing substrate, and a deep reactive ion etching technique is used to etch the doped silicon layer, while the etching thickness needs to be controlled to avoid the doped silicon layer being etched through. The area where the first mask is arranged is not etched, thereby etching a coupling member and a support rod in the doped silicon layer. Then, a second mask is arranged on the doped silicon layer that is not etched through, the center of the second mask is the support rod, and the second mask can be circular or polygonal (the number of sides is greater than or equal to four). The doped silicon layer where the second mask is arranged is etched again, and the doped silicon layer is etched through, thereby etching a mass element connected to the support rod and a coupling member. Since the second mask is circular or polygonal, the mass element etched is also circular or polygonal. It should be noted that the solution used to etch the doped silicon layer does not etch the single crystal silicon layer, thereby etching the detection component on the single crystal silicon layer.

[0204] The etched coupling member surrounds the mass element. The mass element and the coupling member have a gap therebetween, and the width of the gap is equal everywhere. Therefore, the shape of the inner wall of the coupling member is the same as the shape of the outer wall of the mass element. When the shape of the mass element is circular, the shape of the coupling member is annular; when the shape of the mass element is polygonal, the shape of the inner wall of the coupling member is also polygonal, and the edges of the inner wall of the coupling member are parallel to the edges of the outer wall of the mass element.

[0205] In step 720, the free end of the support rod and the coupling member is bonded to the surface of the first silicon substrate, and the single crystal silicon layer is removed.

[0206] After etching the detection component, the surface of the first silicon substrate (i.e. the substrate) is bonded to the free end of the support rod and the coupling member, i.e. the surface of the doped silicon layer is bonded to the surface of the substrate. Exemplarily, the bonding can be by way of bonding, i.e. the surface of the substrate is bonded to the free end of the support rod and the coupling member by using a silicon-silicon bonding process. Since the silicon-silicon bonding has high strength, the detection component can be firmly connected to the surface of the substrate. It should be noted that before the bonding, a through hole can be formed on the substrate by using a through silicon via technology. For example, the through hole is formed on the substrate by using an etching technology. The through hole can be used to bond the support rod and the coupling member. A conductive element can be arranged in the through hole to connect the support rod and the coupling member to the conductive element. When a voltage is applied to the conductive element, the mass element and the coupling member form a detection capacitor. The conductive element can be a wire or a metal filled in the through hole.

[0207] After the substrate is bonded, the single crystal silicon layer is removed to release the detection component. The single crystal silicon layer can be etched by using a sodium hydroxide solution to remove the single crystal silicon layer without damaging the detection component made of doped silicon.

[0208] At step 730, a receiving groove is etched on the second silicon substrate, and the side of the second silicon substrate etched with the receiving groove is bonded to the first silicon substrate, so that the first silicon substrate and the receiving groove enclose a cavity for accommodating the detection component.

[0209] The surface of the second silicon substrate (i.e. the upper housing) is etched to form a receiving groove on the surface of the upper housing. Then, the side of the upper housing etched with the receiving groove is bonded to the first silicon substrate (i.e. the substrate), so that the substrate and the receiving groove enclose a cavity for accommodating the detection component. Further, after the substrate and the upper housing are bonded, wires can be arranged on the through hole opening on the outer surface of the substrate to form a wiring area. Then, balls are planted on the wiring area to form pins, so that the support rod and the coupling member can be connected to a power source through the pins.

[0210] In this embodiment, a plurality of detection components can be etched on one manufacturing substrate, i.e. a plurality of acceleration sensors can be prepared on the substrate. Since each detection component is located on the same silicon substrate, the housing containing the detection component can be cut by using a wafer-level process to obtain a plurality of square acceleration sensors. Since the wafer-level process is used, it is beneficial to mass-produce the acceleration sensors, improve the production efficiency and reduce the production cost.

[0211] The mass element prepared in this embodiment is a circular acceleration sensor, which is different from the conventional single-axis or dual-axis acceleration sensor. The acceleration sensor described in this embodiment can realize 360° omnidirectional acceleration measurement, and the placement orientation of the acceleration sensor is not limited.

[0212] Figure 7B An exemplary flow 735 of a method of manufacturing an acceleration sensor comprising the sensing element 600 is provided according to some embodiments of the present application. The flow 735 is shown in conjunction with the flow 705. Figure 7A The flow 735 further comprises steps 740-760 after step 730, as shown.

[0213] At step 740, a through hole is etched on the second silicon substrate, and a conductive element is disposed in the through hole.

[0214] At step 750, an integrated chip is bonded to the second silicon substrate at a position where the through hole is disposed.

[0215] At step 760, the integrated chip is electrically connected to the support rod and the coupling element via the conductive element.

[0216] In the present embodiment, an integrated chip, such as an ASIC (Application Specific Integrated Circuit) chip, can be provided for the acceleration sensor comprising the sensing element 600. After the first silicon substrate (i.e., the substrate) is bonded to the second silicon substrate (i.e., the upper housing), the integrated chip is bonded to the outer surface of the upper housing. The upper housing can be provided with a through hole in advance, and a conductive element is disposed in the through hole. The integrated chip is bonded to the upper housing at a position where the through hole is disposed, so that the integrated chip is electrically connected to the support rod and the coupling element via the conductive element disposed in the through hole. In some embodiments, a wire can be provided at the through hole, so that the integrated chip is electrically connected to the support rod and the coupling element via the wire, and then the integrated chip is bonded to the outer surface of the upper housing. The through hole on the upper housing is aligned with the through hole on the substrate, so that the conductive element in the through hole on the upper housing is connected to the conductive element in the through hole on the substrate, thereby electrically connecting the integrated chip to the support rod and the coupling element, respectively.

[0217] In the present embodiment, the integrated chip can measure the capacitance between the coupling element and the mass element, and obtain the acceleration value through signal amplification, AD conversion and / or algorithm processing. The information of the acceleration value is transmitted from the integrated chip to an external circuit (e.g., a central processor of a device comprising the acceleration sensor) via the wires and the through holes on the upper housing and the wires and the through holes on the substrate.

[0218] Figure 7C An exemplary flow 765 of a method of manufacturing an acceleration sensor comprising the sensing element 600 is provided according to some other embodiments of the present application. The flow 765 is shown in conjunction with the flow 705 and the flow 735. Figure 7A and 7B The flow 765 further comprises steps 770 and 780 after step 760, as shown.

[0219] At step 770, a receiving groove is etched on the third silicon substrate.

[0220] Step 780, bonding the side of the third silicon substrate etched with the accommodating groove with the outer surface of the second silicon substrate, so that the second silicon substrate and the accommodating groove form a cavity for accommodating the integrated chip.

[0221] In this embodiment, the integrated chip needs to be protected. To this end, after the integrated chip is connected with the support rod and the coupling member, the third silicon substrate (i.e., the cover body) is etched to form the accommodating groove on the cover body. The side of the cover body etched with the accommodating groove is bonded with the outer surface of the upper shell, so that the upper shell and the accommodating groove form a cavity for accommodating the integrated chip. Thus, the integrated chip is protected by the cover body.

[0222] A sensing device (e.g., sensing device 200 or 250) can be formed by coupling at least one resonant system to the acceleration sensor (e.g., between the shell 110 and the sensing element 600). The at least one resonant system can include Figure 2A and 2B a first resonant system 210 as shown in FIG. 2A, or Figure 2C and 2D a second resonant system 260 as shown in FIG. 2B.

[0223] In some embodiments, the first resonant system 210 and the second resonant system 260 can include a liquid. For example, the first resonant system 210 can be a liquid with a specific density and viscosity. For example, the liquid can be a silicone oil with a density of 0.94 kg / m3, and a kinematic viscosity of 0.5 cSt, 1 cSt, 5 cSt, 10 cSt, 100 cSt, 200 cSt, 1000 cSt, etc. The liquid can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The first resonant system 210 can be coupled to the sensing element 600 by filling the cavity of the acceleration sensor with the liquid, so that the sensing element 600 is completely immersed in the liquid. The second resonant system 210 can be a liquid containing bubbles, for example, a silicone oil containing bubbles, wherein the proportion of bubbles in the cavity can be any value between 5% and 95%. The number of bubbles can be one, two, three, four, or more. The liquid can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system, and the bubbles can be equivalent to a spring (Km3) and damping (Rm3) system. The second resonant system 260 can be coupled to the sensing element 600 by partially filling the cavity of the acceleration sensor with the liquid, and partially filling the cavity with bubbles (e.g., bubbles formed by air not expelled from the cavity when filling the cavity with the liquid, bubbles formed by airbags, and / or bubbles formed by applying a hydrophobic coating to the sensing element 600), so that the sensing element 600 is at least partially immersed in the liquid.

[0224] In some embodiments, the first resonant system 210 and the second resonant system 260 can comprise an elastic structure. Exemplarily, the first resonant system 210 can be an elastic structure with mass (e.g., an elastic rod, an elastic sheet, an elastic block, an elastic net, etc.), or a combination of a lightweight elastic structure (e.g., a lightweight spring, a lightweight elastic rod, etc.) and a mass unit. The elastic structure with mass or the combination of the lightweight elastic structure and the mass unit can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The two ends of the elastic structure can be connected between the housing 110 and the sensing element 600 (e.g., one or more positions on the mass element 621), so as to realize the coupling between the first resonant system 210 and the sensing element 600. The second resonant system 260 can be a combination of a lightweight elastic rod and / or a spring and a relatively massive elastic rod. The relatively massive elastic rod can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The lightweight elastic rod and / or the spring can be equivalent to a spring (Km3) and a damping (Rm3) system. The two ends of the elastic rod and / or the spring can be fixedly connected between the housing 110 and the sensing element 600 (e.g., one or more positions on the mass element 621), so as to realize the coupling between the second resonant system 260 and the sensing element 600.

[0225] Due to the existence of the second resonant frequency corresponding to the first resonant system 210 or the second resonant system 260, the frequency response curve of the sensing device containing the sensing element 600 can be improved in a certain frequency band (e.g., low frequency, medium-low frequency, medium frequency, medium-high frequency and / or high frequency), so that the sensitivity of the acceleration sensor is improved compared with an acceleration sensor without the first resonant system 210 or the second resonant system 260. In addition, due to the action of the first resonant system 210 or the second resonant system 260 on the sensing element 600, the vibration characteristics of the acceleration sensor can be changed compared with the acceleration sensor without the first resonant system 210. Specifically, the action of the first resonant system 210 or the second resonant system 260 on the sensing element 600 can affect the mass, stiffness and / or damping of the acceleration sensor, and the effect is equivalent to changing (e.g., reducing) the Q value of the first resonance peak of the sensing device containing the sensing element 600 relative to the Q value of the acceleration sensor without the first resonant system 210 or the second resonant system 260. In some embodiments, the existence of the first resonant system 210 or the second resonant system 260 can produce a suppression effect on the resonance peak corresponding to the acceleration sensor in the sensing device, so that the Q value at the resonance peak in the frequency response curve is relatively low, and the frequency response curve in the required frequency band (e.g., medium-low frequency, medium frequency, etc.) is more flattened.

[0226] Meanwhile, the first resonant system 210 or the second resonant system 260 can reduce external impact received by the sensing element 600 to protect the sensing element 600. For example, if a liquid or a liquid and bubbles are introduced into the cavity of the housing 110, when receiving an external impact load, the first resonant system 210 or the second resonant system 260 can improve the impact resistance reliability of the sensing device containing the sensing element 600. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load received by the sensing element 600 is greatly reduced, thereby protecting the sensing element 600 and prolonging its service life. In addition, due to the presence of stress during the processing of the sensing element 600, the device often deforms. By injecting a liquid and bubbles into the chamber, the deformation of the device can be corrected by using the gravity, surface tension, viscous force, etc. of the liquid, so that the deformation of the sensing device is smaller, the output is more stable, and the design effect is closer.

[0227] In some embodiments, by adjusting the parameters of the acceleration sensor (for example, the internal structure, size, stiffness of the housing 110, and / or the mass, size, stiffness of the sensing element 600) and / or the parameters of the substance / structure forming the at least one resonant system (for example, the size, mass, stiffness, elasticity of the elastic rod, the type, density, viscosity, volume of the liquid, whether it is filled with bubbles, and the proportion, size, position, number of bubbles, etc.), the relevant parameters of the frequency response curve of the sensing device (for example, the relationship between the first resonant frequency and the at least one second resonant frequency, the corresponding peak height, Q value, the difference, ratio of the first resonant frequency and the second resonant frequency, the ratio of the peak value and the highest peak, etc.) can be changed, so as to achieve the purpose of adjusting the Q value of the sensing device, improving the sensitivity, reliability of the sensing device, or making the output gain of the sensing device more stable in the required frequency band (for example, low frequency).

[0228] In some embodiments, the dip between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 10 dBV, 20 dBV, 30 dBV, etc.) and the difference between the peak of the higher peak of the resonance peaks corresponding to the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 0.05, 0.1, 0.2, etc.). The difference between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 20-3000 Hz, 20-2000 Hz, 50-2000 Hz, 50-1500 Hz, 80-1500 Hz, 100-1500 Hz, etc.) and / or the ratio of the difference to the first resonant frequency or the second resonant frequency is within a range (e.g., 0.02-0.7, 0.15-0.6) can result in a relatively flat frequency response curve between the resonance peaks corresponding to the first resonant frequency and the at least one second resonant frequency. The sensitivity of the sensing device including the sensing element 600 can be increased and stabilized within the second resonant frequency. For example, the increase in sensitivity can be within a range of 10 dBV-60 dBV, 20 dBV-50 dBV, 30 dBV-40 dBV, etc.

[0229] In some embodiments, the at least one resonant system can be a liquid containing bubbles. The bubbles can occupy a volume of the cavity by a percentage of 5%, 10%, 20%, 30%, 50%, 70%, 95%, etc. The bubbles can be small bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 2%-10%), medium-small bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 10%-20%), medium bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 20%-50%), large bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 50%-90%), etc. The number of bubbles can be one, two, three, four, or more. The bubbles can be located at different locations within the cavity (e.g., inside the sensing element 600). In some embodiments, the bubbles are located between the mass element 621 and the coupling element 623. In some embodiments, the bubbles are attached to the mass element 621 (e.g., the upper surface, the lower surface, and / or the side opposite to the coupling element 623). In some embodiments, the bubbles are attached to the coupling element 623 (e.g., the upper surface, the lower surface, and / or the side opposite to the mass element 621).

[0230] The frequency response curve of a sensing device comprising the sensing element 600 varies (e.g., the magnitude of the at least one second resonant frequency and the corresponding peak sensitivity vary) when the bubble is located at different positions within the cavity (e.g., inside the sensing element 600). In some embodiments, the sensitivity of the sensing device can be improved (e.g., by 10-60 dBV, 10-40 dBV, 15-40 dBV, etc.) in the low or mid-low or mid-high before frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) regardless of whether the bubble is attached to the sensing element 600 (e.g., attached to the mass element 621 and / or the coupling 623) or not attached to the sensing element 600 (e.g., located between the mass element 621 and the coupling 623). The magnitude of the improvement can also be related to the size and / or position of the bubble.

[0231] In some embodiments, the sensitivity of the sensing device can be improved as the volume of the bubble increases when the bubble is not attached to the sensing element 600 (e.g., located between the mass element 621 and the coupling 623). For example, the sensitivity of a sensing device comprising a medium-small bubble can be improved by about 5-30 dBV in the low or mid-low or mid-high before frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to a sensing device comprising a small bubble. The sensitivity of a sensing device comprising a medium bubble can be improved by about 5-30 dBV in the low or mid-low or mid-high before frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to a sensing device comprising a medium-small bubble.

[0232] Figure 8A and 8B is an exemplary structural schematic of a sensing element 800 according to some embodiments of the present application.

[0233] The sensing element 800 can comprise a substrate 820 and a detection assembly (e.g., a mass element, at least one moving electrode disposed on the mass element, and at least one stationary electrode fixed on the substrate) disposed on the substrate. The substrate 820 can be the same as or similar to the substrate in Figures 4A-6E and will not be repeated here. As shown in FIG. 8, the sensing element 800 can comprise a mass element 821, a coupling 823, and a substrate 820. The mass element 821 can be disposed on the substrate 820. The coupling 823 can be disposed on the mass element 821. The coupling 823 can be electrically connected to the mass element 821. The coupling 823 can be electrically connected to the substrate 820. Figure 8AAs shown, in order from the center of the substrate 820, the detection assembly includes a first mass element 811, at least one first flexible member 812, a first fixed element 813, a plurality of first fixed electrodes 814, a plurality of first movable electrodes 815, a second mass element 816, at least one second flexible member 817, and a second fixed element 818. In some embodiments, the first mass element 811 is disposed at the center of the substrate 820. The first mass element 811 can be circular, square, polygonal, or other regular or irregular shape. The first mass element 811 can be made of, for example, single crystal silicon or other materials. The first fixed element 813 can support the first mass element 811 and fix the first fixed electrodes 814. The first fixed element 813 is connected to the substrate 820 and surrounds the first mass element 811. At least one first flexible member 812 is disposed on the inner wall of the first fixed element 813. Through the at least one first flexible member 812, the first fixed element 813 is connected to the first mass element 811 (e.g., the outer wall of the first mass element), so that the first mass element 811 is suspended over the substrate 820. The plurality of first fixed electrodes 814 is disposed at the periphery of the first fixed element 813 and extends outward. Exemplarily, the plurality of first fixed electrodes 814 is flat, perpendicular to the outer wall of the first fixed element 813, and arranged along the outer wall of the first fixed element 813. In some embodiments, the plurality of first fixed electrodes 814 is distributed along at least a first direction (e.g., the X-axis direction) and a second direction (e.g., the Y-axis direction).

[0234] The second mass element 816 is at the periphery of the first fixed element 813 and surrounds the first fixed element 814. The second mass element 816 can be made of, for example, single crystal silicon or other materials. The second fixed element 818 can support the second mass element 816. The second fixed element 818 is connected to the substrate 820. At least one second flexible member 817 is disposed on the inner wall of the second fixed element 818. Through the at least one second flexible member 817, the second fixed element 818 is connected to the second mass element 816 (e.g., the outer wall of the second mass element), so that the second mass element 816 is suspended over the substrate 820. The plurality of first movable electrodes 815 is disposed inside the second mass element 816 and extends inward. Exemplarily, the plurality of first movable electrodes 815 is flat, perpendicular to the inner wall of the second mass element 816, and arranged along the inner wall of the second mass element 816. In some embodiments, the plurality of first movable electrodes 815 is disposed in parallel with and spaced apart from the plurality of first fixed electrodes 814, forming first and second direction detection capacitors.

[0235] Referring to Figure 8BThe sensing element 800 can further include a second fixed electrode 821 and a second movable electrode disposed on the lower surface of the first mass element. The second fixed electrode 821 is connected to the substrate 820 and is disposed opposite to the lower surface of the first mass element 811. The second movable electrode can be a conductive layer disposed on the lower surface of the first mass element 811. Exemplary conductive layers can include metals, alloy materials, metal oxide materials, graphene, doped silicon, etc., or any combination thereof. In some embodiments, the conductive layer can be fixedly connected or deposited, doped, physically grown, etc. on the lower surface of the first mass element 811 by welding, riveting, clamping, bolting, adhesive bonding, etc. The second fixed electrode 821 and the second movable electrode can constitute a third direction detection capacitor.

[0236] In some embodiments, the first fixed element 813, the second mass element 816, and the second fixed element 818 have central holes, the first mass element 811 is located in the central hole of the first fixed element 813, the first fixed element 813 is located in the central hole of the second mass element 816, and the second mass element 816 is located in the central hole of the second fixed element 818. The outer contours of the first mass element 811, the first fixed element 813, the second mass element 816, and the second fixed element 818 can be circular, square, rectangular, polygonal, etc.

[0237] In some embodiments, the outer contours of the first mass element 811, the first fixed element 813, the second mass element 816, and the second fixed element 818 can be square. Exemplarily, the at least one first flexible component 812 includes four first flexible components 812. Each of the four first flexible components 812 connects each of the four outer walls of the first mass element 811 and the corresponding inner wall of the first fixed element 813, thereby supporting the first mass element 811 and allowing the first mass element 811 to move in the third direction (e.g., the Z-axis direction). Exemplarily, the at least one second flexible component 817 includes eight second flexible components 817. Each of the eight second flexible components 817 connects each of the four outer walls of the second mass element 816 and the corresponding inner wall of the second fixed element 818, thereby supporting the second mass element 816 and allowing the second mass element 816 to move in the first direction (e.g., the X-axis direction) and / or the second direction (e.g., the Y-axis direction) parallel to the substrate 820. In some embodiments, the at least one first flexible component 812 and / or the at least one second flexible component 817 can be a curved arm structure as shown in the figure.

[0238] In some embodiments, a plurality of holes 819 can be provided on the first mass element 811 and / or the second mass element 822. The holes can provide damping for the movement of the first mass element 811 and / or the second mass element 822, making the movement of the first mass element 811 and / or the second mass element 822 more stable.

[0239] Referring to Figure 8A , the plurality of first moving electrodes 815 and the plurality of first fixed electrodes 814 are arranged in parallel and cross each other, forming a comb-shaped capacitance system, wherein each first moving electrode 815 and a corresponding first fixed electrode 814 form a detection capacitance.

[0240] When there is an external acceleration input in the first or second direction (i.e., the X or Y axis direction), due to the action of the at least one second flexible component 817, the second mass element 816 moves in the X-Y plane, so that the distance and / or the facing area between the plurality of first fixed electrodes 814 and the corresponding first moving electrodes 815 changes, the first and second direction detection capacitances formed thereby change, thereby forming a differential capacitance structure in the first and second directions, to represent the acceleration magnitude in the first and second directions.

[0241] When there is an external acceleration input in the third direction (i.e., the Z axis direction), due to the action of the at least one first flexible component 812, the first mass element 811 moves along the Z axis direction, so that the distance between the second fixed electrode 821 and the corresponding second moving electrode changes, the third direction detection capacitance formed thereby changes, thereby representing the acceleration magnitude in the third direction.

[0242] By coupling at least one resonant system to the acceleration sensor (e.g., between the housing 110 and the sensing element 800), a sensing device (e.g., the sensing device 200 or 250) can be formed. The at least one resonant system can include Figure 2A and 2B a first resonant system 210 as shown in Figure 2C and 2D a second resonant system 260 as shown in

[0243] In some embodiments, the first resonant system 210 and the second resonant system 260 can include a liquid. Illustratively, the first resonant system 210 can be a liquid with a specific density and viscosity. For example, the liquid can be a silicone oil with a density of 0.94 kg / m3, and a kinematic viscosity of 0.5 cSt, 1 cSt, 5 cSt, 10 cSt, 100 cSt, 200 cSt, 1000 cSt, etc. The liquid can be equivalent to a spring (Km4) - mass (Mm4) - damping (Rm4) system. The first resonant system 210 can be coupled to the sensing element 800 by filling the cavity of the acceleration sensor with the liquid, such that the sensing element 800 is completely immersed in the liquid. The second resonant system 210 can be a liquid with bubbles, for example, a silicone oil with bubbles, where the proportion of the volume of the cavity occupied by the bubbles can be any value between 5% and 95%. The number of bubbles can be one, two, three, four, or more. The liquid can be equivalent to a spring (Km4) - mass (Mm4) - damping (Rm4) system, and the bubbles can be equivalent to a spring (Km3) and damping (Rm3) system. The second resonant system 260 can be coupled to the sensing element 800 by partially filling the cavity of the acceleration sensor with the liquid, partially filling the cavity with bubbles (e.g., bubbles formed by air not expelled from the cavity when filling the cavity with the liquid, bubbles formed by a bladder, and / or bubbles formed by applying a hydrophobic coating to the sensing element 800), such that the sensing element 800 is at least partially immersed in the liquid.

[0244] In some embodiments, the first resonant system 210 and the second resonant system 260 can comprise an elastic structure. Exemplarily, the first resonant system 210 can be an elastic structure with mass (e.g., an elastic rod, an elastic sheet, an elastic block, an elastic net, etc.), or a combination of a lightweight elastic structure (e.g., a lightweight spring, a lightweight elastic rod, etc.) and a mass unit. The elastic structure with mass or the combination of the lightweight elastic structure and the mass unit can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The two ends of the elastic structure can be connected between the housing 110 and the sensing element 800 (e.g., one or more positions on the first mass element 811 or the second mass element 816, the first moving electrode 815, the second moving electrode, etc.), so as to couple the first resonant system 210 with the sensing element 600. The second resonant system 260 can be a combination of a lightweight elastic rod and / or spring and a massier elastic rod. The massier elastic rod can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The lightweight elastic rod and / or spring can be equivalent to a spring (Km3) and a damping (Rm3) system. The two ends of the elastic rod and / or spring can be fixedly connected between the housing 110 and the sensing element 800 (e.g., one or more positions on the first mass element 811 or the second mass element 816, the first moving electrode 815, the second moving electrode, etc.), so as to couple the second resonant system 260 with the sensing element 800.

[0245] Due to the existence of the second resonant frequency corresponding to the first resonant system 210 or the second resonant system 260, the frequency response curve of the sensing device containing the sensing element 800 can be improved in a certain frequency band (e.g., low frequency, medium-low frequency, medium frequency, medium-high frequency, and / or high frequency), so that the sensitivity of the acceleration sensor is improved compared with an acceleration sensor without the first resonant system 210 or the second resonant system 260. In addition, due to the action of the first resonant system 210 or the second resonant system 260 on the sensing element 800, the vibration characteristics of the acceleration sensor can be changed compared with the acceleration sensor without the first resonant system 210. Specifically, the action of the first resonant system 210 or the second resonant system 260 on the sensing element 800 can affect the mass, stiffness, and / or damping of the acceleration sensor, and the effect is equivalent to changing (e.g., reducing) the Q value of the first resonance peak of the sensing device containing the sensing element 800 relative to the Q value of the acceleration sensor without the first resonant system 210 or the second resonant system 260. In some embodiments, the existence of the first resonant system 210 or the second resonant system 260 can have a suppression effect on the resonance peak corresponding to the acceleration sensor in the sensing device, so that the Q value at the resonance peak in the frequency response curve is relatively low, and the frequency response curve is more flattened in the required frequency band (e.g., medium-low frequency, medium frequency, etc.).

[0246] Meanwhile, the first resonant system 210 or the second resonant system 260 can reduce external impact on the sensing element 800 to protect the sensing element 800. For example, if a liquid or a liquid and bubbles are introduced into the cavity of the housing 110, when receiving an external impact load, the first resonant system 210 or the second resonant system 260 can improve the impact resistance reliability of the sensing device containing the sensing element 800. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load on the sensing element 800 is greatly reduced, thereby protecting the sensing element 800 and prolonging its service life. In addition, due to the presence of stress during the processing of the sensing element 800, the device often deforms. By injecting a liquid and bubbles into the chamber, the deformation of the device can be corrected by using the gravity, surface tension, viscous force, etc. of the liquid, so that the deformation of the sensing device is smaller, the output is more stable, and the design effect is closer.

[0247] In some embodiments, by adjusting the parameters of the acceleration sensor (for example, the internal structure, size, stiffness of the housing 110, and / or the mass, size, stiffness of the sensing element 800) and / or the parameters of the substance / structure forming the at least one resonant system (for example, the size, mass, stiffness, elasticity of the elastic rod, the type, density, viscosity, volume of the liquid, whether it is filled with bubbles, and the proportion, size, position, number of bubbles, etc.), the relevant parameters of the frequency response curve of the sensing device (for example, the relationship between the first resonant frequency and the at least one second resonant frequency, the corresponding peak height, Q value, the difference, ratio of the first resonant frequency and the second resonant frequency, the ratio of the peak value and the highest peak, etc.) can be changed, so as to achieve the purpose of adjusting the Q value of the sensing device, improving the sensitivity, reliability of the sensing device, or making the output gain of the sensing device more stable in the required frequency band (for example, low frequency).

[0248] In some embodiments, the dip between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 10 dBV, 20 dBV, 30 dBV, etc.) and the difference in sensitivity between the peak of the higher peak of the resonance peaks corresponding to the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 0.05, 0.1, 0.2, etc.). The difference in frequency between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 20-3000 Hz, 20-2000 Hz, 50-2000 Hz, 50-1500 Hz, 80-1500 Hz, 100-1500 Hz, etc.) and / or the ratio of the difference to the first resonant frequency or the second resonant frequency is within a range (e.g., 0.02-0.7, 0.15-0.6) can result in a relatively flat frequency response curve between the corresponding resonance peaks. The sensitivity of the sensing device including the sensing element 800 can be increased and stabilized within the second resonant frequency. For example, the increase in sensitivity can be within a range of 10 dBV-60 dBV, 20 dBV-50 dBV, 30 dBV-40 dBV, etc.

[0249] In some embodiments, the at least one resonant system can be a liquid containing bubbles. The bubbles can occupy a volume of the cavity by a percentage of 5%, 10%, 20%, 30%, 50%, 70%, 95%, etc. The bubbles can be small bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 2%-10%), medium-small bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 10%-20%), medium bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 20%-50%), large bubbles (e.g., bubbles occupying a volume of the cavity by a percentage of 50%-90%), etc. The number of bubbles can be one, two, three, four, or more. The bubbles can be located at different locations within the cavity (e.g., inside the sensing element 800). In some embodiments, the bubbles are located between the first moving electrode 815 and the first stationary electrode 814 and / or between the second moving electrode (e.g., the lower surface of the first mass element) and the second stationary electrode 821. In some embodiments, the bubbles are attached to the first mass element 811 (e.g., the upper surface, the lower surface, or the inner or outer sidewall of the first mass element 811), the second mass element 816 (e.g., the upper surface, the lower surface, or the inner or outer sidewall of the second mass element 816), the first moving electrode 815 (e.g., the upper and lower surfaces or the side surface relative to the first stationary electrode 814), and / or the second moving electrode (e.g., the side surface or the surface relative to the second stationary electrode 821). In some embodiments, the bubbles are attached to the first stationary electrode (e.g., the side surface opposite to the first moving electrode 815) and / or the second stationary electrode 821 (e.g., the surface opposite to the second moving electrode).

[0250] The frequency response curve of a sensing device comprising the sensing element 800 varies (e.g., the magnitude of the at least one second resonant frequency and the corresponding peak sensitivity vary) when the bubble is located at different positions within the cavity (e.g., inside the sensing element 800). In some embodiments, the sensitivity of the sensing device can be improved (e.g., by 10-60 dBV, 10-40 dBV, 15-40 dBV, etc.) in the low or mid-low or mid-high before frequency band (e.g., within a frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) regardless of whether the bubble is attached to the sensing element 800 (e.g., attached to the first mass element 811, the second mass element 816, the first moving electrode 815, and / or the second moving electrode) or not attached to the sensing element 800 (e.g., located between the first moving electrode 815 and the first stationary electrode 814). The magnitude of the improvement can also be related to the size and / or position of the bubble.

[0251] In some embodiments, the sensitivity of the sensing device increases as the volume of the bubble increases when the bubble is not attached to the sensing element 800 (e.g., located between the first moving electrode 815 and the first stationary electrode 814). For example, the sensitivity of a sensing device comprising a medium-small bubble can be improved by about 5-30 dBV in the low or mid-low or mid-high before frequency band (e.g., within a frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to a sensing device comprising a small bubble. The sensitivity of a sensing device comprising a medium bubble can be improved by about 5-30 dBV in the low or mid-low or mid-high before frequency band (e.g., within a frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to a sensing device comprising a medium-small bubble.

[0252] Figure 9 is an exemplary structural schematic of a sensing device 900 according to some embodiments of the present application.

[0253] The sensing device 900 comprises a sensing element 910 and a liquid 920. In the present embodiment, the sensing element 910 can be similar to the sensing element 800 described above. Figures 5A-6DThe sensing element 500 in the sensing device 900 is the same or similar to the sensing element 500 in the sensing device 800, and thus will not be repeated here. The liquid 920 can be a specific liquid with a specific density and viscosity. For example, the liquid 920 can be a silicone oil with a density of 0.94 kg / m3, and a kinematic viscosity of 0.5 cSt, 1 cSt, 5 cSt, 10 cSt, 100 cSt, 200 cSt, 1000 cSt, etc. The liquid 920 can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. The liquid 920 can be coupled to the sensing element 910 by filling the cavity of the sensing element 910 with the liquid 920, such that the detection assembly in the sensing element 910 is completely immersed in the liquid. In some embodiments, the liquid 920 can also contain air bubbles. The air bubbles can occupy 5% to 95% of the volume of the cavity. The number of air bubbles can be one, two, three, four, or more. The air bubbles can be equivalent to a spring (Km3) and damping (Rm3) system. The liquid 920 can be coupled to the sensing element 910 by filling the cavity of the sensing element 910 with the liquid containing air bubbles, such that the sensing element 910 is at least partially immersed in the liquid.

[0254] Due to the presence of the second resonant frequency corresponding to the liquid 920, the frequency response curve of the sensing device 900 can be improved in a specific frequency band (e.g., low frequency, mid-low frequency, mid-frequency, mid-high frequency, and / or high frequency). In addition, due to the effect of the liquid 920 on the sensing element 910, the vibration characteristics of the sensing element 910 can be changed compared to when there is no liquid 920. Specifically, the effect of the liquid 920 on the sensing element 910 is equivalent to changing (e.g., reducing) the Q value of the first resonance peak of the sensing device 900 relative to the Q value of an acceleration sensor that does not contain the liquid 920. In some embodiments, the presence of the liquid 920 can suppress the resonant peak corresponding to the sensing element 910 in the sensing device 900, such that the Q value at the resonant peak in the frequency response curve is relatively low, and the frequency response curve in the desired frequency band (e.g., mid-low frequency, mid-frequency, etc.) is more flattened.

[0255] Meanwhile, the liquid 920 can reduce external impact on the sensing element 910 to protect the sensing element 910. For example, when receiving external impact load, the liquid 920 can improve the impact resistance reliability of the sensing device 900 containing the sensing element 910. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load on the sensing element 910 is greatly reduced, thus the sensing element 910 can be protected and its service life can be prolonged. In addition, due to the existence of stress in the processing process, the sensing element 910 often appears device deformation. By injecting the liquid 920 in the cavity, the gravity, surface tension, viscous force and the like of the liquid can be used to correct the deformation of the device, so that the sensing device 900 is less deformed, the output is more stable, and is closer to the design effect.

[0256] In some embodiments, by adjusting the parameters of the sensing element 910 (for example, the internal structure, size, stiffness of the shell, and / or the mass, size, stiffness of the internal detection component) and / or the parameters of the liquid 920 (for example, the kind, density, viscosity, volume, whether to fill bubbles, and the proportion, size, position, number of bubbles, etc.), the relevant parameters of the frequency response curve of the sensing device 900 (for example, the relationship between the first resonant frequency and at least one second resonant frequency, the corresponding peak height, Q value, the difference, ratio of the first resonant frequency and the second resonant frequency, the ratio of the peak value and the highest peak value, etc.) can be changed, so as to achieve the purpose of adjusting the Q value of the sensing device 900, improving the sensitivity, reliability of the sensing device 900 or making the output gain of the sensing device 900 more stable in the required frequency band (for example, low frequency).

[0257] In some embodiments, the dip between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 10 dBV, 20 dBV, 30 dBV, etc.) and the difference in sensitivity between the peak of the higher peak of the resonant peaks corresponding to the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 0.05, 0.1, 0.2, etc.). The difference in frequency between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 20-3000 Hz, 20-2000 Hz, 50-2000 Hz, 50-1500 Hz, 80-1500 Hz, 100-1500 Hz, etc.) and / or the ratio of the difference to the first resonant frequency or the second resonant frequency is within a range (e.g., 0.02-0.7, 0.15-0.6) can result in a relatively flat frequency response curve between the corresponding resonant peaks. The sensitivity of the sensor device 900 can be increased and stabilized within the second resonant frequency. For example, the increase in sensitivity can be within a range of 10 dBV-60 dBV, 20 dBV-50 dBV, 30 dBV-40 dBV, etc.

[0258] In some embodiments, the ratio of the volume of the bubble to the volume of the cavity can be 5%, 10%, 20%, 30%, 50%, 70%, 95%, etc. The bubble can be a small bubble (e.g., a bubble with a ratio of 2%-10% of the volume of the cavity), a small-to-medium bubble (e.g., a bubble with a ratio of 10%-20% of the volume of the cavity), a medium bubble (e.g., a bubble with a ratio of 20%-50% of the volume of the cavity), a large bubble (e.g., a bubble with a ratio of 50%-90% of the volume of the cavity), etc. The number of bubbles can be one, two, three, four, or more. The bubble can be located at different locations within the cavity (e.g., inside the sensing element 910).

[0259] When the bubble is located at different locations within the cavity (e.g., inside the sensing element 910), the frequency response curve of the sensor device 900 including the sensing element 910 can be different (e.g., the at least one second resonant frequency and the corresponding peak sensitivity can be different). In some embodiments, the sensitivity of the sensor device 900 can be increased (e.g., 10-60 dBV, 10-40 dBV, 15-40 dBV, etc.) to some extent before the low or mid-low or mid-high frequency band (e.g., within a frequency band of less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) regardless of whether the bubble is attached to the sensing element 910 (e.g., attached to the detection assembly) or not. The size of the increase can also be related to the size and / or location of the bubble.

[0260] In some embodiments, when the bubbles are not attached to the sensing element 910 (e.g., located between the detection assembly and the inner wall of the cavity), the sensitivity of the sensing device 900 increases as the volume of the bubbles increases. Exemplarily, the sensing device 900 containing medium-small bubbles has a sensitivity improvement of about 5-30 dBV in the low frequency or medium-low frequency or medium-high frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to the sensing device e containing small bubbles. The sensing device 900 containing medium bubbles has a sensitivity improvement of about 5-30 dBV in the low frequency or medium-low frequency or medium-high frequency band (e.g., in the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) compared to the sensing device 900 containing medium-small bubbles.

[0261] Figure 10 is an exemplary structural schematic diagram of a sensing device 1000 provided according to some embodiments of the present application.

[0262] The sensing device 1000 includes a sensing element 1010 and a liquid 1020. In the present embodiment, the sensing element 1010 can be the same as or similar to the sensing element 600 in Figures 6A-6E The liquid 1020 can be a specific liquid with specific density and viscosity. For example, the liquid 1020 can be silicone oil with a density of 0.94 kg / m3, and its kinematic viscosity can be 0.5 cst, 1 cst, 5 cst, 10 cst, 100 cst, 200 cst, 1000 cst, etc. The liquid 1020 can be equivalent to a spring (Km4)-mass (Mm4)-damping (Rm4) system. By filling the liquid 1020 into the cavity of the sensing element 1010, the detection assembly in the sensing element 1010 is completely immersed in the liquid, and the coupling between the liquid 1020 and the sensing element 1010 can be achieved. In some embodiments, the liquid 1020 can also contain bubbles. The proportion of bubbles in the cavity can be any value between 5% and 95%. The number of bubbles can be 1, 2, 3, 4, or more. The bubbles can be equivalent to a spring (Km3) and a damping (Rm3) system. By filling the liquid containing bubbles into the cavity of the sensing element 1010, the sensing element 1010 is at least partially immersed in the liquid, so as to achieve the coupling between the liquid 1020 and the sensing element 1010.

[0263] Due to the existence of the second resonant frequency corresponding to the liquid 1020, the frequency response curve of the sensing device 1000 can be improved in a certain frequency band (e.g., low frequency, medium-low frequency, medium frequency, medium-high frequency, and / or high frequency). In addition, due to the action of the liquid 1020 on the sensing element 1010, the vibration characteristics of the sensing element 1010 can be changed compared to when there is no liquid 1020. Specifically, the action of the liquid 1020 on the sensing element 1010 can change (e.g., reduce) the Q value of the first resonance peak of the sensing device 1000 relative to the Q value of an acceleration sensor that does not contain the liquid 1020. In some embodiments, the presence of the liquid 1020 can suppress the resonant peak corresponding to the sensing element 1010 in the sensing device 1000, so that the Q value at the resonant peak in the frequency response curve is relatively low, and the frequency response curve in the desired frequency band (e.g., medium-low frequency, medium frequency, etc.) is more flattened.

[0264] At the same time, the liquid 1020 can reduce the external impact on the sensing element 1010 to protect the sensing element 1010. For example, when receiving external impact load, the liquid 1020 can improve the impact resistance reliability of the sensing device 1000 containing the sensing element 1010. Specifically, due to the viscous effect of the liquid and the large compressibility of the gas, part of the impact energy can be absorbed and consumed, so that the impact load on the sensing element 1010 is greatly reduced, thereby protecting the sensing element 1010 and prolonging its service life. In addition, due to the presence of stress during processing, the sensing element 1010 often deforms. By injecting the liquid 1020 into the chamber, the deformation of the device can be corrected by using the gravity, surface tension, and viscous force of the liquid, so that the deformation of the sensing device 1000 is smaller, the output is more stable, and the design effect is closer.

[0265] In some embodiments, by adjusting the parameters of the sensing element 1010 (e.g., the internal structure, size, stiffness of the shell, and / or the mass, size, stiffness of the internal detection component) and / or the parameters of the liquid 1020 (e.g., type, density, viscosity, volume, whether to fill bubbles, and the proportion, size, position, and number of bubbles), the relevant parameters of the frequency response curve of the sensing device 1000 (e.g., the relationship between the first resonant frequency and at least one second resonant frequency, the corresponding peak height, the Q value, the difference between the first resonant frequency and the second resonant frequency, the ratio, the peak-to-valley value to the peak value of the highest peak, etc.) can be changed, so as to achieve the purposes of, for example, adjusting the Q value of the sensing device 1000, improving the sensitivity and reliability of the sensing device 1000, or making the output gain of the sensing device 1000 more stable in the desired frequency band (e.g., medium-low frequency).

[0266] In some embodiments, the dip between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 10 dBV, 20 dBV, 30 dBV, etc.) and the difference between the peak of the higher peak of the resonant peaks corresponding to the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 0.05, 0.1, 0.2, etc.). The difference between the first resonant frequency and the at least one second resonant frequency is within a range (e.g., 20-3000 Hz, 20-2000 Hz, 50-2000 Hz, 50-1500 Hz, 80-1500 Hz, 100-1500 Hz, etc.) and / or the ratio of the difference to the first resonant frequency or the second resonant frequency is within a range (e.g., 0.02-0.7, 0.15-0.6) can result in a relatively flat frequency response curve between the corresponding resonant peaks. The sensitivity of the sensor device 1000 can be improved and stabilized within the second resonant frequency. For example, the sensitivity can be improved by 10 dBV-60 dBV, 20 dBV-50 dBV, 30 dBV-40 dBV, etc.

[0267] In some embodiments, the ratio of the volume of the bubble to the volume of the cavity can be 5%, 10%, 20%, 30%, 50%, 70%, 95%, etc. The bubble can be a small bubble (e.g., a bubble with a ratio of 2%-10% of the volume of the cavity), a small-to-medium bubble (e.g., a bubble with a ratio of 10%-20% of the volume of the cavity), a medium bubble (e.g., a bubble with a ratio of 20%-50% of the volume of the cavity), a large bubble (e.g., a bubble with a ratio of 50%-90% of the volume of the cavity), etc. The number of bubbles can be one, two, three, four, or more. The bubble can be located at different positions within the cavity (e.g., inside the sensing element 1010).

[0268] When the bubble is located at different positions within the cavity (e.g., inside the sensing element 1010), the frequency response curve of the sensor device 1000 including the sensing element 1010 is different (e.g., the at least one second resonant frequency and the corresponding peak sensitivity are different). In some embodiments, the sensitivity of the sensor device 1000 can be improved to some extent (e.g., 10-60 dBV, 10-40 dBV, 15-40 dBV, etc.) before the low frequency or the medium-low frequency or the medium-high frequency band (e.g., a frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, 50 Hz) regardless of whether the bubble is attached to the sensing element 1010 (e.g., attached to the detection assembly) or not. The size of the improvement can also be related to the size and / or position of the bubble.

[0269] In some embodiments, when bubbles are not attached to the sensing element 1010 (e.g., located between the detection assembly and the inner wall of the chamber), the sensitivity of the sensing device 1000 increases as the bubble volume increases. For example, compared to a sensing device 1000 containing small bubbles, the sensitivity of the sensing device 1000 with small bubbles is improved by approximately 5-30 dBV in low-frequency, mid-low-frequency, or mid-high frequency bands (e.g., within the frequency bands less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, and 50 Hz). Compared to a sensing device 1000 with medium bubbles, the sensitivity of the sensing device 1000 with small bubbles is improved by approximately 5-30 dBV in low-frequency, mid-low-frequency, or mid-high frequency bands (e.g., within the frequency bands less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, 500 Hz, 100 Hz, and 50 Hz).

[0270] The basic concepts have been described above. It will be apparent to those skilled in the art that the detailed disclosure above is merely illustrative and does not limit the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to the present application. Such modifications, improvements, and amendments are suggested in the present application and remain within the spirit and scope of the exemplary embodiments of the present application.

[0271] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other variations may also fall within the scope of this application. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this application may be considered consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly introduced and described in this application.

Claims

1. A sensing device, comprising: an acceleration sensor having a first resonant frequency, the acceleration sensor comprising a housing and a sensing element, the sensing element being located in a cavity formed by the housing; and at least one resonant system coupled to the sensing element, wherein the at least one resonant system comprises a first medium and a second medium filled in the cavity, the first medium being a liquid, the sensing element being immersed in the liquid, the second medium being a gas, the gas being distributed in the liquid in the form of bubbles, a size of the bubbles occupying a proportion of 20%-50% of a volume of the cavity, the at least one resonant system providing the sensing device with at least one second resonant frequency, the at least one second resonant frequency being different from the first resonant frequency, a frequency difference between the first resonant frequency and the at least one second resonant frequency being 100 Hz to 1500 Hz. The sensing element comprises:

2. The sensing device of claim 1, wherein, a substrate; a mass element moving relative to the substrate in response to an external acceleration, the mass element being provided with at least one moving electrode; and at least one fixed electrode fixed on the substrate, the at least one moving electrode and the at least one fixed electrode constituting at least one detection capacitance for determining a magnitude of the external acceleration. 3.The sensing device according to claim 2, wherein the at least one moving electrode comprises: at least one group of first moving electrodes arranged along a first direction and perpendicular to the first direction, each group of first moving electrodes comprising one or more first moving electrodes; and at least one group of second moving electrodes arranged along a second direction and perpendicular to the second direction, each group of second moving electrodes comprising one or more second moving electrodes; the at least one fixed electrode comprises: a first fixed electrode parallel to and relative to each first moving electrode, the at least one group of first moving electrodes and the corresponding first fixed electrode constituting a first direction detection capacitance; and a second fixed electrode parallel to and relative to each second moving electrode, the at least one group of second moving electrodes and the corresponding second fixed electrode constituting a second direction detection capacitance, the at least one group of first moving electrodes and the at least one group of second moving electrodes and the corresponding first fixed electrode and second fixed electrode constituting a third direction detection capacitance. 4.The sensing device according to claim 3, wherein the second direction is perpendicular to the first direction. 5.The sensing device according to claim 3, wherein the at least one group of first moving electrodes comprises an even number of first moving electrodes, the even number of first moving electrodes being located on two sides of the mass element along the first direction; the at least one group of second moving electrodes comprises an even number of second moving electrodes, the even number of second moving electrodes being located on two sides of the mass element along the second direction. 6.The sensing device according to any one of claims 3-5, wherein each group of first moving electrodes is provided with a first moving electrode shaft along the first direction and a first fixed moving electrode perpendicular to the first direction, the first moving electrode shaft and the first fixed moving electrode being connected to the substrate through a first elastic element. ​ Each group of second moving electrodes is provided with a second moving electrode shaft and a second fixed moving electrode perpendicular to the second direction, the second moving electrode shaft and the second fixed moving electrode being connected to the substrate through a second elastic element, The sensing device further comprises: corresponding to each group of first moving electrodes, a pair of first fixed electrodes and a pair of first fixed moving electrodes, the pair of first fixed electrodes being symmetrically arranged relative to the first direction, the pair of first fixed moving electrodes being perpendicular to the first direction, the first moving electrode shaft of each group of first moving electrodes being clamped between the pair of first fixed electrodes, and the first fixed moving electrode being clamped between the pair of first fixed moving electrodes; and corresponding to each group of second moving electrodes, a pair of second fixed electrodes and a pair of second fixed moving electrodes, the pair of second fixed electrodes being symmetrically arranged relative to the second direction, the pair of second fixed moving electrodes being perpendicular to the second direction, the second moving electrode shaft of each group of second moving electrodes being clamped between the pair of second fixed electrodes, and the second fixed moving electrode being clamped between the pair of second fixed moving electrodes.

7. The sensing device according to claim 6, wherein corresponding to each group of first moving electrodes, a pair of first fixed electrodes and a pair of first fixed moving electrodes form a triangular region; corresponding to each group of second moving electrodes, a pair of second fixed electrodes and a pair of second fixed moving electrodes form a triangular region.

8. The sensing device according to claim 7, wherein adjacent first fixed electrodes and second fixed electrodes are arranged in parallel with a certain spacing.

9. The sensing device according to any one of claims 3-8, wherein each first moving electrode has a first moving electrode top surface parallel to the upper surface of the mass element and a first moving electrode bottom surface, and the corresponding first fixed electrode has a first fixed electrode top surface parallel to the upper surface of the mass element and a first fixed electrode bottom surface, the first moving electrode top surface being farther away from the upper surface of the mass element than the first fixed electrode top surface; each second moving electrode has a second moving electrode top surface parallel to the upper surface of the mass element and a second moving electrode bottom surface, and the corresponding second fixed electrode has a second fixed electrode top surface parallel to the upper surface of the mass element and a second fixed electrode bottom surface, the second moving electrode top surface being closer to the upper surface of the mass element than the second fixed electrode top surface.

10. The sensing device according to claim 9, wherein the first fixed electrode top surface and the second moving electrode top surface have the same horizontal height.

11. The sensing device according to claim 2, wherein the sensing element further comprises: a first support member fixed on the substrate, the mass element being connected to the first support member through an elastic connecting unit, the first support member being located at the center of the mass element, the elastic connecting unit extending along the first direction, the center line of the elastic connecting unit coinciding with the center line of the mass element in the first direction, and in the second direction, the masses of the portions of the mass element on both sides of the elastic connecting unit are not equal, wherein the at least one fixed electrode comprises: at least two first direction fixed electrodes; at least two second direction fixed electrodes extending along the first direction, the second direction fixed electrodes being located on a center line of the mass element along the second direction and symmetric with respect to the first support member; and at least two third direction fixed electrodes disposed on both sides of the elastic connection unit, the at least one moving electrode comprises: first direction moving electrodes, second direction moving electrodes and third direction moving electrodes corresponding to the at least two first direction fixed electrodes, the at least two second direction fixed electrodes and the at least two third direction fixed electrodes respectively, and the first direction moving electrodes, the second direction moving electrodes and the third direction moving electrodes form first direction detection capacitors, second direction detection capacitors and third direction detection capacitors respectively.

12. The sensing device according to claim 11, the at least two first direction fixed electrodes extending along the second direction, the at least two first direction fixed electrodes being distributed on both sides of a substrate position corresponding to the center line of the mass element along the second direction and symmetric with respect to an axis of the center line of the mass element along the second direction or symmetric with respect to a center of the first support member.

13. The sensing device according to claim 12, the at least two first direction fixed electrodes not being on a center line of the mass element along the first direction.

14. The sensing device according to claim 13, wherein each first direction fixed electrode comprises two first direction fixed electrode units arranged in parallel, and a first direction moving electrode corresponding to the first direction fixed electrode comprises two first direction moving electrode units, the two first direction moving electrode units and the two first direction fixed electrode units forming a first direction differential capacitor structure; each second direction fixed electrode comprises two second direction fixed electrode units arranged in parallel, and a second direction moving electrode corresponding to the second direction fixed electrode comprises two second direction moving electrode units, the two second direction moving electrode units and the two second direction fixed electrode units forming a second direction differential capacitor structure.

15. The sensing device according to claim 12, the at least two first direction fixed electrodes being located on a center line of the mass element along the first direction.

16. The sensing device according to claim 15, wherein each first direction fixed electrode comprises two first direction fixed electrode units arranged in parallel, and a first direction moving electrode corresponding to the first direction fixed electrode comprises two first direction moving electrode units, the two first direction moving electrode units and the two first direction fixed electrode units forming a first direction differential capacitor structure; each second direction fixed electrode comprises two second direction fixed electrode units arranged in parallel, and a second direction moving electrode corresponding to the second direction fixed electrode comprises two second direction moving electrode units, the two second direction moving electrode units and the two second direction fixed electrode units forming a second direction differential capacitor structure, wherein a first direction fixed electrode unit on one side of at least one first direction fixed electrode of the at least two first direction fixed electrodes is electrically connected to a first direction fixed electrode unit on an opposite side of another first direction fixed electrode symmetric with respect to the at least one first direction fixed electrode about an axis of the center line of the mass element along the second direction.

17. The sensing device of claim 11, wherein the at least two third direction fixed electrodes are lower electrodes of the at least two third direction detection capacitors, and the at least two third direction movable electrodes are upper electrodes of the at least two third direction detection capacitors.

18. The sensing device of claim 11, wherein one side of the mass element is provided with a weight-reducing hole or a counterweight, so that the mass on both sides of the mass element is not equal.

19. The sensing device of claim 2, wherein the sensing element further comprises: a second support member fixed to the substrate, the mass element being connected to the substrate through the second support member, the at least one fixed electrode comprises: a coupling member surrounding the mass element and having a gap between the mass element, forming the at least one detection capacitor.

20. The sensing device of claim 19, wherein the substrate is made of silicon, and the second support member, the mass element and the coupling member are made of doped silicon.

21. The sensing device of claim 20, further comprising: an integrated chip electrically connected to the second support member and the coupling member, respectively.

22. The sensing device of claim 21, wherein the integrated chip is located on an outer surface of the housing, the housing is provided with a through hole, and a conductive element passes through the through hole to connect the integrated chip with the second support member and the coupling member.

20. The sensing device of claim 19, wherein, 23. The sensing device of claim 2, wherein the mass element comprises: a first mass element; and a second mass element, the sensing device further comprises: a first fixing member connected to the substrate and surrounding the first mass element, the first fixing member being connected to the first mass element through at least one first flexible member, and the second mass element surrounding the first fixing member; and a second fixing member connected to the substrate and surrounding the second mass element, the second fixing member being connected to the second mass element through at least one second flexible member, the at least one movable electrode comprises: a plurality of first movable electrodes arranged inside the second mass element and extending inwardly, the plurality of first movable electrodes being distributed along at least a first direction and a second direction; and a second movable electrode arranged at the bottom of the first mass element, the at least one fixed electrode comprises: a plurality of first fixed electrodes arranged at the periphery of the first fixing member and extending outwardly, the plurality of first fixed electrodes corresponding to and being spaced apart from the plurality of first movable electrodes, forming first and second direction detection capacitors; and a second fixed electrode arranged on the substrate, forming a third direction detection capacitor with the second movable electrode.

24. The sensing device of claim 23, wherein the first mass element and / or the second mass element is provided with a plurality of holes.

25. The sensing device of claim 23, wherein at least one of the first mass element, the second mass element, the first fixing member, or the second fixing member has a square profile.

26. The sensing device of claim 1, wherein the liquid comprises at least one of silicone oil, glycerol, engine oil, lubricating oil, or hydraulic oil. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 27. The sensing device of claim 1, wherein the at least one resonant system comprises a spring-mass-damper system and a spring-damper system.

28. The sensing device of claim 27, wherein the bubble has a size that occupies 30-50% of the volume of the cavity.

29. The sensing device of claim 27, wherein the bubble is formed by at least one of air that is not vented from the cavity, a gas bladder, or a hydrophobic material.

30. The sensing device of claim 27, wherein the at least one resonant system comprises at least one second elastic structure coupled to the acceleration sensor, the second elastic structure comprising a first elastic structure and at least one lightweight elastic component.

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