Bistable asymmetric anti-false-triggering self-energized MEMS inertial switch

Abstract

The invention discloses a bistable asymmetric anti-false-triggering self-powered MEMS (Micro Electro Mechanical System) inertia switch, which relates to the technical field of inertia switches, and comprises an asymmetric bistable movable structure, a miniature solenoid, a fixed electrode and an energy storage device. The asymmetric bistable movable structure causes the change of the internal magnetic flux of the miniature solenoid through small-amplitude in-well oscillation, converts the environmental vibration energy into electric energy, and provides the electric energy for forming a pulse signal. When the environment excitation intensity is higher than the trigger threshold value of the inertia switch, the asymmetric bistable movable structure moves towards the fixed electrode with large-amplitude inter-well oscillation, and pulse signals are formed when the asymmetric bistable movable structure makes contact with the fixed electrode. On one hand, the problem of energy supply of the inertia switch is solved by collecting environmental vibration energy through bistable in-well oscillation, and on the other hand, the problems of energy supply and false triggering of the existing inertia switch are solved by strengthening the in-well oscillation barrier height through a bistable asymmetric principle, and the self-energized micro-mechanical inertia switch capable of preventing false triggering is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of inertial switches, and in particular to a bistable asymmetric anti-false triggering self-powered MEMS inertial switch. Background Art

[0002] An inertial switch is a sensor that uses inertial impact to achieve the on / off function. When the impact excitation intensity exceeds the threshold designed for the inertial switch, the movable parts inside the inertial switch can move toward the fixed electrode, thereby closing the switch and generating a pulse trigger signal.

[0003] At present, micro-electro-mechanical systems (MEMS) inertial switches consume energy to generate pulse trigger signals only when they are closed. Although the power consumption is low, they are still not self-powered MEMS components. Therefore, in scenarios where large-scale deployment is required and regular maintenance is difficult, it is very easy for the monitoring system to fail due to battery exhaustion. Existing research generally realizes self-powered MEMS inertial switches by integrating vibration energy harvesters on the basis of MEMS inertial switches. However, the above schemes also include multiple independent movable components such as inertial sensing and energy collection, which not only increases the difficulty of system design and integrated manufacturing, but also makes the circuit design more complicated. Therefore, how to achieve energy collection and inertial sensing at the same time through a single movable component has become a key problem that needs to be solved urgently to restrict its engineering application. After searching the existing technical literature, it was found that in the article "A Self-Powered MEMS Inertial Switch for Potential Zero Power Consumption Wake-Up Application" published in the Journal of Microelectromechanical Systems in 2021, researchers achieved the integrated manufacturing of linear support movable electrodes and electret electrostatic films through an integrated manufacturing process. The linear support movable electrode proposed by the institute can, on the one hand, convert environmental mechanical energy into electrical energy through large-scale resonance, and store the electrical energy in a capacitor through a rectifier circuit; on the other hand, under the excitation of the target impact, the linear support movable electrode can move toward the bottom fixed electrode to achieve the closure of the inertial switch, and form a pulse trigger signal by releasing the electrical energy stored in the capacitor. This study simultaneously realizes energy harvesting and inertial sensing through a single movable component, providing a reference for the design and preparation of self-powered MEMS inertial switches, but there are still the following shortcomings: (1)Narrow working frequency range: The above solutions use a linear support structure to achieve ambient vibration energy harvesting. However, the linear structure can only efficiently harvest vibration energy around the natural frequency of the device. Once the ambient excitation frequency deviates from the natural frequency of the device, the energy harvesting efficiency will be significantly reduced, resulting in the inability to provide energy for forming a pulse trigger signal. (2)High risk coefficient of mis-triggering: The above solutions respectively use the resonance of the linear support structure at the natural frequency and the large displacement under impact excitation to achieve the functions of energy harvesting and inertial sensing. However, the amplitude of the linear support structure during resonance is extremely easy to exceed the distance between the movable electrode and the fixed electrode of the device, resulting in the phenomenon of mis-triggering of the switch. The above solutions not only have a high design difficulty, but also are difficult to completely eliminate the risk of mis-triggering. Summary of the Invention

[0004] Aiming at the above-mentioned defects existing in the prior art, the object of the present invention is to provide a bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch, which not only uses the two stable equilibrium points of the bistable non-linear structure to respectively achieve the functions of vibration energy harvesting and inertial sensing, thereby realizing a self-powered inertial switch, but also further proposes an asymmetric bistable mechanism to achieve an asymmetric bistable structure with both deep potential barrier and shallow potential barrier characteristics, which can solve the problem of mis-triggering of the inertial switch. In addition, due to the adoption of the scheme of a planar single movable structure, the problem of high integration and manufacturing difficulty of the self-powered inertial switch is reduced.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch, comprising an asymmetric bistable movable structure, a micro solenoid, a fixed electrode and an energy storage device. When the ambient excitation intensity is lower than the trigger threshold of the inertial switch, the asymmetric bistable movable structure causes a change in the magnetic flux inside the micro solenoid through small-amplitude oscillation within the well, realizing the conversion of ambient vibration energy into electrical energy to provide electrical energy for forming a pulse signal; when the ambient excitation intensity is higher than the trigger threshold of the inertial switch, the asymmetric bistable movable structure can move towards the fixed electrode with large-amplitude oscillation between wells and form a pulse signal when contacting, realizing self-powered inertial sensing.

[0006] The asymmetric bistable movable structure includes a movable electrode, a movable platform, an insulating support block, a micro spring, a permanent magnet pair and a soft magnetic yoke, wherein, The movable platform is connected to the micro spring, and the movable electrode is arranged on the lower surface of the movable platform; the permanent magnet pair and the insulating support block are arranged on the upper surface of the movable platform; The soft magnetic yoke is composed of a first soft magnetic yoke and a second soft magnetic yoke; the first soft magnetic yoke and the second soft magnetic yoke are respectively arranged on both sides of the permanent magnet pair and fixed on the surface of the first insulating substrate.

[0007] Preferably, the permanent magnet includes an upper permanent magnet and a lower permanent magnet, the polarization directions of the upper permanent magnet and the lower permanent magnet are opposite, and the polarization direction is parallel to the normal direction of the cross-section of the soft magnetic yoke.

[0008] Preferably, the insulating support block is arranged between the upper permanent magnet and the lower permanent magnet.

[0009] Preferably, the shape of the micro spring includes a serpentine spring, a fixed-guided cantilever beam, a cantilever beam fixed at both ends, etc.

[0010] The movable electrode, the movable platform, the insulating support block, and the permanent magnet pair form an oscillating structure; during the movement of the oscillating structure, it is simultaneously subjected to the non-linear magnetic force between the soft magnetic yoke and the permanent magnet pair, and the mechanical restoring force of the micro spring.

[0011] Preferably, by designing the thickness of the insulating support block, the neutral plane of the oscillating structure is not in the same plane as the neutral plane of the soft magnetic yoke, so that the oscillating structure has an upper stable equilibrium point and a lower stable equilibrium point, and the upper stable equilibrium point and the lower stable equilibrium point have an asymmetric relationship with respect to the neutral plane of the oscillating structure, thereby forming the asymmetric bistable movable structure.

[0012] Preferably, the potential barrier depth at the upper stable equilibrium point is greater than the potential barrier depth at the lower stable equilibrium point.

[0013] Preferably, the fixed electrode is arranged at the lower stable equilibrium point.

[0014] The micro solenoid is arranged on the surface of the first insulating substrate. The micro solenoid includes a conductive coil, a magnetic conduction magnetic path, and an insulating filling layer. Among them, The magnetic conduction magnetic path is integrated inside the conductive coil through a micro electroforming process, and the insulating filling layer is used to fill the space between the magnetic conduction magnetic path and the conductive coil.

[0015] Preferably, the conductive coil is made of a material with good conductivity such as copper.

[0016] Preferably, the magnetic conduction magnetic path is made of a material with high magnetic permeability characteristics such as nickel or permalloy.

[0017] Preferably, the insulating filling layer is made of a material that cannot conduct magnetism or electricity, such as polyimide or SU8.

[0018] Preferably, the thickness of the magnetic conduction magnetic path is 10 to 300 microns.

[0019] The fixed electrode includes a first fixed electrode and a second fixed electrode, and the first fixed electrode and the second fixed electrode are kept insulated from each other.

[0020] Preferably, both the first fixed electrode and the second fixed electrode are array-type flexible electrodes. The array-type flexible electrode is composed of a plurality of flexible electrodes, and the flexible electrode includes a flexible limiting cantilever beam and a conductive column. Among them, the conductive column is arranged on the surface of the second insulating substrate, and the flexible limiting cantilever beam is arranged on the surface of the conductive column; the plurality of flexible electrodes in the array-type flexible electrode are connected by wires; the first fixed electrode and the second fixed electrode are located directly below the movable electrode and are both inside the projection of the movable electrode on the surface of the second insulating substrate; the flexible electrode is made of a material with good conductivity such as copper; the thickness of the flexible limiting cantilever beam and the conductive column is 10-100 microns; the energy storage device includes a DC / AC rectification circuit and a charge / discharge capacitor. The DC / AC rectification circuit is connected to the micro solenoid by a wire and is used to convert the alternating current generated in the micro solenoid into direct current and charge the charge / discharge capacitor to realize electric energy storage.

[0021] Preferably, the charge / discharge capacitor is connected to the first fixed electrode and the second fixed electrode by wires to form a circuit for generating a pulse induction voltage signal. When the movable electrode contacts the first fixed electrode and the second fixed electrode at the same time, the pulse induction voltage signal circuit forms a pulse induction signal to realize self-powered inertial sensing.

[0022] Preferably, the bistable asymmetric anti-mistrigger self-powered MEMS inertial switch further includes any one or more of the following, When the environmental excitation intensity is lower than the trigger threshold of the inertial switch, the asymmetric bistable movable structure moves near the upper stable equilibrium point. The pulse induction voltage signal circuit is in an open state. The magnetic flux of the permanent magnet pair passes through the soft magnetic yoke and the magnetic conduction path through the micro solenoid to form an induced current, and the electric energy is stored through the energy storage device.

[0023] When the environmental excitation intensity is higher than the trigger threshold of the inertial switch, the asymmetric bistable movable structure can overcome the potential well barrier and move from the upper stable equilibrium point to the lower stable equilibrium point. When the movable electrode contacts the fixed electrode, the pulse induction voltage signal circuit is turned on to form a pulse induction signal to realize self-powered inertial sensing.

[0024] Preferably, the potential barrier depth at the upper stable equilibrium point is higher than the potential barrier depth at the lower stable equilibrium point, thereby ensuring that the asymmetric bistable movable structure cannot cross the potential barrier depth at the upper stable equilibrium point under a small environmental excitation intensity, so as to realize the anti-mistrigger function.

[0025] By designing the distance between the neutral plane of the oscillation structure and the neutral plane of the soft magnetic yoke, the barrier depth at the upper stable equilibrium point and the barrier depth at the lower stable equilibrium point can be adjusted to achieve the design of the trigger threshold of the MEMS inertial switch.

[0026] Preferably, the distance between the neutral plane of the oscillation structure and the neutral plane of the soft magnetic yoke can be adjusted by adjusting the thickness of the insulating support block, so as to achieve the design of the trigger threshold of the MEMS inertial switch, where By increasing the thickness of the insulating support block, the distance between the neutral plane of the oscillation structure and the neutral plane of the soft magnetic yoke can be increased, thereby increasing the barrier depth at the upper stable equilibrium point to increase the trigger threshold of the MEMS inertial switch; By reducing the thickness of the insulating support block, the distance between the neutral plane of the oscillation structure and the neutral plane of the soft magnetic yoke can be reduced, thereby reducing the barrier depth at the upper stable equilibrium point to reduce the trigger threshold of the MEMS inertial switch; Preferably, the thickness of the insulating support block is 100 - 1000 microns, and the distance between the fixed electrode and the neutral plane of the soft magnetic yoke is 100 - 1000 microns.

[0027] Preferably, the upper permanent magnet and the lower permanent magnet are blocks with the same size, and the thickness is 1000 - 2000 microns, and the thickness of the soft magnetic yoke is 500 - 1000 microns.

[0028] Compared with the prior art, the beneficial effects of the present invention are: Compared with the existing inertial switches powered by batteries, which have problems such as limited lifespan and high maintenance costs, the present invention proposes an asymmetric bistable structure. On the one hand, energy harvesting is achieved by using the oscillation within the small well of the bistable state, and on the other hand, impact sensing is achieved by using the large movement between the wells of the bistable state. Thus, self-powered inertial sensing is realized through a single movable structure; Compared with the problem of high false trigger risk existing in the existing self-powered inertial switches, the present invention proposes an asymmetric bistable structure, and at the same time introduces deep barriers and shallow barriers into the bistable system. On the one hand, the deep barrier is used to eliminate the risk that the movable electrode crosses the deep barrier under environmental excitation, thereby causing false triggering of the switch; on the other hand, the shallow barrier enables the movable electrode to stably return to the deep barrier after contacting and closing with the fixed electrode, thereby truly realizing an anti-false-touch self-powered inertial switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a bistable asymmetric anti-false-trigger self-powered MEMS inertial switch according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of a fixed electrode according to an embodiment of the present invention; Figure 3 is a schematic diagram of an asymmetric bistable movable structure and its potential energy curve according to an embodiment of the present invention; Figure 4 is a schematic diagram of the working principle of a bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch according to an embodiment of the present invention during energy harvesting; Figure 5 is a schematic diagram of the working principle of a bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch according to an embodiment of the present invention during inertial sensing; Figure 6 is a displacement-time relationship curve according to an embodiment of the present invention under impulse excitation. The dashed line and the solid line respectively represent the cases when the acceleration amplitude is 25g and 30g, and the threshold of the self-powered inertial switch is 26g; Figure 7 is the change of the capacitance voltage according to an embodiment of the present invention during the energy harvesting and inertial sensing working stages. The dashed line represents the capacitance charging curve under an environmental excitation of 1.0g, and the pulse induction signal with an amplitude of 216 mV formed after applying a 30g impact excitation; the solid line represents the capacitance charging curve under an environmental excitation of 2.0g, and the pulse induction signal with an amplitude of 262 mV formed after applying a 30g impact excitation.

[0030] List of reference numerals in the drawings: movable electrode 1-1, movable platform 1-2, insulating support block 1-3, micro spring 1-4, upper permanent magnet 2-1, lower permanent magnet 2-2, first soft magnetic yoke 3-1, second soft magnetic yoke 3-2, conductive coil 4-1, magnetic conduction path 4-2, insulating filling layer 4-3, first fixed electrode 5-1, second fixed electrode 5-2, flexible limiting cantilever beam 5-3, conductive column 5-4, AC / DC rectifier circuit 6-1, charge / discharge capacitor 6-2, first insulating substrate 7, second insulating substrate 8, neutral plane A of the soft magnetic yoke, neutral plane B of the oscillation structure, upper stable equilibrium point S-1, lower stable equilibrium point S-2, potential barrier depth H1 at the upper stable equilibrium point, potential barrier depth H2 at the lower stable equilibrium point. Detailed implementation manners

[0031] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made. These all belong to the protection scope of the present invention.

[0032] The core idea of the present invention is to provide a bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch to solve the problems of energy supply, mis-triggering and integrated manufacturing of existing inertial switches.

[0033] As Figures 1 to 7As shown in the figure, it is a schematic diagram of a partial embodiment of a bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch according to the present invention. A bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch in this embodiment includes an asymmetric bistable movable structure, a micro solenoid, a fixed electrode, and an energy storage device. Among them, The asymmetric bistable movable structure includes a movable electrode 1-1, a movable platform 1-2, an insulating support block 1-3, a micro spring 1-4, a permanent magnet pair, and a soft magnetic yoke; The movable platform 1-2 is connected to the micro spring 1-4, and the movable electrode 1-1 is arranged on the lower surface of the movable platform 1-2; the permanent magnet pair and the insulating support block 1-3 are arranged on the upper surface of the movable platform 1-2; The soft magnetic yoke is composed of a first soft magnetic yoke 3-1 and a second soft magnetic yoke 3-2; the first soft magnetic yoke 3-1 and the second soft magnetic yoke 3-2 are respectively arranged on both sides of the permanent magnet pair and fixed on the surface of the first insulating substrate 7.

[0034] As Figure 1 And Figure 3 As shown, the permanent magnet includes an upper permanent magnet 2-1 and a lower permanent magnet 2-2, and the insulating support block 1-3 is arranged between the upper permanent magnet 2-1 and the lower permanent magnet 2-2; the polarization directions of the upper permanent magnet 2-1 and the lower permanent magnet 2-2 are opposite, and the polarization direction is parallel to the normal direction of the cross-section of the first soft magnetic yoke 3-1 and the second soft magnetic yoke 3-2.

[0035] In some embodiments, the polarization directions of the upper permanent magnet 2-1 and the lower permanent magnet 2-2 can also be perpendicular to the normal direction of the cross-section of the first soft magnetic yoke 3-1 and the second soft magnetic yoke 3-2.

[0036] In some embodiments, the shape of the micro spring 1-4 includes a serpentine spring, a fixed-guided cantilever beam, a double-ended fixed cantilever beam, etc.

[0037] As Figure 1 And Figure 3 As shown, the movable electrode 1-1, the movable platform 1-2, the insulating support block 1-3, and the permanent magnet pair form an oscillating structure; the oscillating structure is simultaneously subjected to the non-linear magnetic force between the soft magnetic yoke and the permanent magnet pair and the mechanical restoring force of the micro spring 1-4 during the movement. Among them, By designing the thickness of the insulating support block 1-3, the neutral plane B of the oscillating structure is not in the same plane as the neutral plane A of the soft magnetic yoke, so that the oscillating structure has an upper stable equilibrium point S-1 and a lower stable equilibrium point S-2, and the upper stable equilibrium point S-1 and the lower stable equilibrium point S-2 have an asymmetric relationship with respect to the neutral plane B of the oscillating structure, thereby forming the asymmetric bistable movable structure; As Figure 3 shown, the barrier depth H1 at the upper steady-state equilibrium point is greater than the barrier depth H2 at the lower steady-state equilibrium point; As Figure 1 shown, the micro solenoid is provided on the surface of the first insulating substrate 7. The micro solenoid includes a conductive coil 4-1, a magnetic conduction magnetic circuit 4-2, and an insulating filling layer 4-3. Among them, the magnetic conduction magnetic circuit 4-2 is integrated inside the conductive coil 4-1 through a micro electroforming process, and the insulating filling layer 4-3 is used to fill the space between the magnetic conduction magnetic circuit 4-2 and the conductive coil 4-1.

[0038] In some embodiments, the magnetic conduction magnetic circuit 4-2 is made of materials with high magnetic permeability characteristics such as nickel and permalloy; the insulating filling layer 4-3 is made of materials that cannot conduct magnetism or electricity, such as polyimide and SU8.

[0039] As Figure 1 and Figure 2 shown, the fixed electrode is provided on the surface of the second insulating substrate 8, including a first fixed electrode 5-2 and a second fixed electrode 5-3, and the first fixed electrode and the second fixed electrode are kept insulated from each other. Among them, both the first fixed electrode 5-2 and the second fixed electrode 5-3 are arrayed flexible electrodes. The arrayed flexible electrode is composed of a plurality of flexible electrodes, and each flexible electrode includes a flexible limiting cantilever beam 5-3 and a conductive column 5-4; the conductive column 5-4 is provided on the surface of the second insulating substrate 8, and the flexible limiting cantilever beam 5-3 is provided on the surface of the conductive column 5-4; the plurality of flexible electrodes in the arrayed flexible electrode are connected by wires; both the first fixed electrode 5-2 and the second fixed electrode 5-3 are located directly below the movable electrode 1-1 and are both inside the projection of the movable electrode 1-1 on the surface of the second insulating substrate 7; the energy storage device includes a DC / AC rectification circuit 6-1 and a charge / discharge capacitor 6-2. The DC / AC rectification circuit 6-1 is connected to the micro solenoid by a wire, which is used to convert the alternating current generated in the micro solenoid into direct current and charge the charge / discharge capacitor 6-2 to achieve electrical energy storage; the charge / discharge capacitor 6-2 is also connected to both the first fixed electrode 5-2 and the second fixed electrode 5-3 by wires to form a circuit for generating a pulsed induced voltage signal. When the movable electrode 1-1 contacts both the first fixed electrode 5-2 and the second fixed electrode 5-3 simultaneously, the circuit for generating the pulsed induced voltage signal is turned on to form a pulsed induced signal, realizing self-powered inertial sensing.

[0040] As Figure 4 shown, when the oscillation structure is at the upper stable equilibrium point S-1 and the environmental excitation intensity is lower than the inertial switch trigger threshold, the oscillation structure oscillates slightly near the upper stable equilibrium point S-1. At this time, the pulse induction voltage signal circuit is in an open state, and the magnetic flux of the permanent magnet pair passes through the soft magnetic yoke and the magnetic conduction path 4-2 through the wire coil 4-1 to form an induced current, and electrical energy is stored through the energy storage device to provide electrical energy for realizing the pulse induction signal.

[0041] As Figure 5 shown, when the environmental excitation intensity is higher than the inertial switch trigger threshold, the oscillation structure can overcome the potential barrier depth H1 at the upper stable equilibrium point and move from the upper stable equilibrium point S-1 to the lower stable equilibrium point S-2. When the movable electrode 1-1 is in contact with the first fixed electrode 5-1 and the fixed second electrode 5-2 at the same time, the pulse induction voltage signal circuit is turned on to form a pulse induction signal, realizing self-powered inertial sensing.

[0042] By designing the distance between the neutral plane B of the oscillation structure and the neutral plane A of the soft magnetic yoke, the potential barrier depth H1 at the upper stable equilibrium point and the potential barrier depth H2 at the lower stable equilibrium point can be adjusted simultaneously to realize the design of the trigger threshold of the MEMS inertial switch and at the same time realize the anti-mis-trigger function of the inertial switch.

[0043] By adjusting the thickness of the insulating support block 1-3, the distance between the neutral plane B of the oscillation structure and the neutral plane A of the soft magnetic yoke can be adjusted.

[0044] In some embodiments, by increasing the thickness of the insulating support block 1-3, the distance between the neutral plane B of the oscillation structure and the neutral plane A of the soft magnetic yoke can be increased, thereby increasing the potential barrier depth H1 at the upper stable equilibrium point to increase the trigger threshold of the MEMS inertial switch.

[0045] In some embodiments, by reducing the thickness of the insulating support block 1-3, the distance between the neutral plane B of the oscillation structure and the neutral plane A of the soft magnetic yoke can be reduced, thereby reducing the potential barrier depth H1 at the upper stable equilibrium point to reduce the trigger threshold of the MEMS inertial switch.

[0046] In some embodiments, the thickness of the insulating support block 1-3 is 100-1000 microns, and the distance between the fixed electrode and the neutral plane of the soft magnetic yoke is 100-1000 microns.

[0047] In some embodiments, the upper permanent magnet 2-1 and the lower permanent magnet 2-2 are blocks with the same size, and the thickness is 1000-2000 microns. The thickness of the first soft magnetic yoke 3-1 and the second soft magnetic yoke 3-2 is 500-1000 microns.

[0048] In a specific embodiment, the thickness, length and width of the upper permanent magnet 2-1 and the lower permanent magnet 2-2 are 1 mm, 2 mm and 2 mm respectively; the thickness of the insulating support block 1-3 is 300 microns; the thickness of the first soft magnetic yoke 3-1 and the second soft magnetic yoke 3-2 is 500 microns, and the distance between the upper surface of the flexible limiting cantilever beam 5-3 and the neutral plane B of the oscillation structure is 350 microns.

[0049] As Figure 6 shown, the sample of the bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch corresponding to the above parameter design shows that the potential barrier depth H1 at the upper stable equilibrium point is 3 μJ, the potential barrier depth H2 at the lower stable equilibrium point is 0.2 μJ, the upper stable equilibrium point S-1 is 400 microns above the neutral plane B of the oscillation structure, and the lower stable equilibrium point S-2 is 350 microns below the neutral plane B of the oscillation structure. The triggering threshold of the inertial switch is 26g. When the device is excited with an acceleration amplitude of 25g, the oscillation structure vibrates slightly at the upper stable equilibrium point S-1, as shown by the dotted line in Figure 6 . At this time, the pulse induction voltage signal circuit is open, and the charge / discharge capacitor 6-2 is in a charging state; when the device is excited with an acceleration amplitude of 30g, the oscillation structure moves from the upper stable equilibrium point S-1 to the lower stable equilibrium point S-2 and contacts the flexible limiting cantilever beam 5-3, as shown by the solid line in Figure 6 . At this time, the pulse induction voltage signal circuit is closed, the charge / discharge capacitor 6-2 is in a discharging state, and the pulse induction signal is formed. It can be seen from the figure that by designing the potential barrier depth H1 at the upper stable equilibrium point and the potential barrier depth H2 at the lower stable equilibrium point, the energy harvesting and impact sensing can be realized by using the small-amplitude in-well oscillation and the large-amplitude oscillation between wells of the bistable state respectively, and the anti-mis-triggering function of the inertial switch is realized by designing the potential barrier depth H1 at the upper stable equilibrium point, thereby realizing the bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch proposed by the present invention.

[0050] As Figure 7As shown, the energy harvesting and signal sensing performance of the bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch samples corresponding to the above parameters was further tested. When the device was under an acceleration amplitude of 1.0 g excitation intensity, the charge / discharge capacitor 6-2 was in a charged state. Then, a pulse excitation with an acceleration amplitude of 30 g was applied. At this time, the charge / discharge capacitor 6-2 was in a discharged state and formed a pulsed induced signal of 216 millivolts, as shown by the dashed line in Figure 7 ; when the device was under an acceleration amplitude of 2.0 g excitation intensity, the charge / discharge capacitor 6-2 was in a charged state. Then, a pulse excitation with an acceleration amplitude of 30 g was applied. At this time, the charge / discharge capacitor 6-2 was in a discharged state and formed a pulsed induced signal of 262 millivolts, as shown by the solid line in Figure 7 . It can be seen from the figure that the bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch proposed by the present invention can also achieve efficient charging of the charge / discharge capacitor 6-2 under low-intensity environmental excitation, and form the pulsed induced signal when the excitation intensity exceeds the design threshold, indicating that the bistable asymmetric anti-mis-triggering self-powered MEMS inertial switch proposed by the present invention can stably achieve self-powered inertial sensing in the environment.

[0051] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. A bistable asymmetric anti-false trigger self-powered MEMS inertial switch, characterized in that: The bistable asymmetric anti-false triggering self-powered MEMS inertial switch comprises an asymmetric bistable movable structure, a micro solenoid, a fixed electrode and an energy storage device; wherein, When the environmental excitation intensity is lower than the inertial switch triggering threshold, the asymmetric bistable movable structure causes the change of the internal magnetic flux of the micro-solenoid through a small-amplitude intra-well oscillation, converts the environmental vibration energy into electrical energy, and provides electrical energy for forming a pulse signal; when the environmental excitation intensity is higher than the inertial switch triggering threshold, the asymmetric bistable movable structure moves toward the fixed electrode with a large-amplitude inter-well oscillation, and forms a pulse signal when in contact, realizing self-powered inertial sensing.

2. A bistable asymmetric anti-false triggering self-powered MEMS inertial switch according to claim 1, characterized in that: The asymmetric bistable movable structure is composed of a movable electrode, a movable platform, an insulating support block, a micro spring, a permanent magnet pair and a soft magnetic yoke, wherein: The movable platform can vibrate under the support of the microspring, the movable electrode is arranged on the lower surface of the movable platform; the permanent magnet pair and the insulating support block are arranged on the upper surface of the movable platform; the soft magnetic yoke is arranged on both sides of the permanent magnet pair and fixed on the surface of the first insulating substrate; The movable electrode, the movable platform, the insulating support block and the permanent magnet pair form an oscillating structure; during the movement, the oscillating structure is simultaneously subjected to the nonlinear magnetic force of the soft magnetic yoke and the mechanical restoring force of the microspring. By adjusting the thickness of the insulating support block, the oscillating structure has an upper steady-state equilibrium point and a lower steady-state equilibrium point, and the upper steady-state equilibrium point and the lower steady-state equilibrium point have an asymmetric relationship with respect to the neutral plane of the oscillating structure, thereby forming the asymmetric bistable movable structure.

3. A bistable asymmetric anti-false triggering self-powered MEMS inertial switch according to claim 2, characterized in that: The micro solenoid is arranged on the surface of the first insulating substrate, and the micro solenoid comprises a conductive coil, a magnetic conductive path and an insulating filling layer, wherein: The magnetic conductive circuit is integrated inside the conductive coil by a micro-electroforming process, and the insulating filling layer is used to fill the space between the magnetic conductive circuit and the conductive coil.

4. According to the bistable asymmetric anti-false triggering self-powered MEMS inertial switch according to claim 2, the fixed electrode is arranged on the surface of the second insulating substrate, the fixed electrode includes a first fixed electrode and a second fixed electrode, and the first fixed electrode and the second fixed electrode are kept insulated and have no wire connection; the first fixed electrode and the second fixed electrode are located directly below the movable electrode, and are both inside the projection of the movable electrode on the surface of the second insulating substrate.

5. A bistable asymmetric anti-false triggering self-powered MEMS inertial switch according to claim 4, characterized in that: The energy storage device includes an AC / DC rectifier circuit and a charging / discharging capacitor, wherein: The AC / DC rectifier circuit is connected to the micro solenoid via a wire, and is used to convert the AC power generated in the micro solenoid into DC power, and to charge the charging / discharging capacitor to achieve electrical energy storage; The charge / discharge capacitor is simultaneously connected to the first fixed electrode and the second fixed electrode through a wire to form a pulse induced voltage signal circuit. When the movable electrode contacts the first fixed electrode and the second fixed electrode at the same time, the pulse induced voltage signal circuit is turned on to form a pulse induced signal, thereby realizing self-powered inertial sensing.

6. The bistable asymmetric anti-false triggering self-powered MEMS inertial switch according to claim 3, characterized in that: The potential barrier depth at the upper steady-state equilibrium point is greater than the potential barrier depth at the lower steady-state equilibrium point, and the position of the fixed electrode is set at the lower steady-state equilibrium point. By adjusting the potential barrier depth at the upper steady-state equilibrium point, on the one hand, the inertial switch triggering threshold is designed; on the other hand, it is prevented that the asymmetric bistable movable structure overcomes the potential barrier depth at the upper steady-state equilibrium point and contacts the fixed electrode under low-intensity environmental excitation, thereby realizing the inertial switch anti-false triggering function; When the environmental excitation intensity is lower than the inertial switch triggering threshold, the asymmetric bistable movable structure moves near the upper steady-state equilibrium point, the pulse induced voltage signal circuit is in a disconnected state, and the magnetic flux of the permanent magnet pair passes through the soft magnetic yoke and the magnetic conductive magnetic circuit and passes through the inside of the micro-solenoid to form an induced current, and the energy storage device is used to store electrical energy; When the environmental excitation intensity is higher than the inertial switch triggering threshold, the asymmetric bistable movable structure overcomes the potential barrier depth at the upper steady-state equilibrium point and moves from the upper steady-state equilibrium point to the lower steady-state equilibrium point. When the movable electrode contacts the fixed electrode, the pulse induction voltage signal circuit is turned on to form a pulse induction signal, thereby realizing self-powered inertial sensing.

Images