阅读说明：本技术 一种基于镂空振膜的mems压电声学与振动能量采集器 (MEMS piezoelectric acoustics and vibration energy collector based on hollow vibrating diaphragm ) 是由 徐佳文 于 2021-08-30 设计创作，主要内容包括：本发明涉及一种基于镂空振膜的MEMS压电声学与振动能量采集器,可用于同时将声学与环境振动的机械能转化为电能；包括：衬底；质量块,产生振幅,用于与外部声学耦合膜连接；背腔,位于中间区域；绝缘层；振膜,用于支撑压电薄膜并将其采集的机械能传递给质量块；顶电极；压电薄膜层,通过压电效应将机械转化为电能；底电极。本发明中振膜采用镂空结构,与非镂空振膜MEMS压电声学与振动能量采集器相比,镂空结构的引入可降低压电能量采集器的刚度,降低MEMS压电声学与振动能量采集器第一谐振频率,且有效增加器件机电耦合系数,利用镂空结构降低谐振频率并不减薄压电换能器整体厚度,以维持压电薄膜的应变,最终提高能量转换效率。(The invention relates to an MEMS piezoelectric acoustic and vibration energy collector based on a hollow vibrating diaphragm, which can be used for simultaneously converting mechanical energy of acoustic and environmental vibration into electric energy; the method comprises the following steps: a substrate; a mass block generating an amplitude for connection with the external acoustic coupling membrane; a back cavity located in the middle region; an insulating layer; the vibrating diaphragm is used for supporting the piezoelectric film and transmitting the mechanical energy collected by the piezoelectric film to the mass block; a top electrode; the piezoelectric film layer converts machinery into electric energy through a piezoelectric effect; a bottom electrode. The vibrating diaphragm adopts a hollow structure, compared with a non-hollow vibrating diaphragm MEMS piezoelectric acoustics and vibration energy collector, the introduction of the hollow structure can reduce the rigidity of the piezoelectric energy collector, reduce the first resonant frequency of the MEMS piezoelectric acoustics and vibration energy collector, effectively increase the electromechanical coupling coefficient of the device, reduce the resonant frequency by using the hollow structure and not reduce the whole thickness of the piezoelectric transducer so as to maintain the strain of the piezoelectric film and finally improve the energy conversion efficiency.)

1. An MEMS piezoelectric acoustics and vibration energy collector based on a hollowed-out vibrating diaphragm comprises an MEMS piezoelectric acoustics and vibration energy collector (6), wherein the MEMS piezoelectric acoustics and vibration energy collector (6) comprises a substrate (14); a mass (16) generating an amplitude for connection with an external acoustic coupling membrane; a back cavity (15) located in the middle region; an insulating layer (13); the vibrating diaphragm (9) is used for supporting the piezoelectric film and transmitting the collected mechanical energy to the mass block; a top electrode layer (10); a piezoelectric thin film layer (11) for converting mechanical energy into electric energy by a piezoelectric effect; and a bottom electrode layer (12); the method is characterized in that: the diaphragm (9) is a single or composite film and is made of inorganic or organic materials; the diaphragm (9) is composed of three parts: the structure beam part is positioned on the upper part of the peripheral substrate and the mass block (16), positioned on the upper part or the lower part of the piezoelectric film layer (11) and used for connecting the middle mass block (16) with the piezoelectric film (11); the vibrating diaphragm positioned above or below the piezoelectric film (11) adopts a hollow structure, and the hollow structure is processed to form a grating type strip structure or raised grains or a net-shaped or porous structure.

2. The MEMS piezoelectric acoustics and vibration energy collector based on the hollowed-out diaphragm as claimed in claim 1, wherein: the structural beam part of the diaphragm (9) is in an L-shaped or S-shaped or C-shaped curve shape or other connectable structural shapes.

3. The MEMS piezoelectric acoustic and vibration energy harvester based on the hollowed-out diaphragm as claimed in claim 1, wherein the substrate (14) is rectangular, and the central region is a back cavity (15).

4. The MEMS piezoelectric acoustic and vibration energy collector based on the hollowed-out diaphragm as claimed in claim 1, wherein the number of the mass blocks (16) is 1-10, and the mass blocks are located in the middle of the device.

5. The MEMS piezoelectric acoustics and vibration energy collector based on the hollowed-out diaphragm as claimed in claim 1, wherein: the diaphragm (9), the top and bottom electrode layers (10, 12) and the piezoelectric film layer (11) jointly form an organic diaphragm layer (18) which is formed on the back cavity (15).

6. The MEMS piezoelectric acoustic and vibration energy harvester based on the hollowed-out diaphragm as claimed in claim 5, wherein the organic diaphragm layer (18) is a connected whole or a plurality of discrete units, and is not limited to include the components, and can also include additional structures of an insulating layer, a passivation layer and a protective layer.

7. The MEMS piezoelectric acoustics and vibration energy collector based on the hollowed-out diaphragm as claimed in claim 5, wherein: the top and bottom electrode layers (10 and 12) and the piezoelectric thin film layer (11) are of a sandwich structure (17), the piezoelectric thin film layer (11) is 1-5 layers, and the upper surface and the lower surface of the piezoelectric thin film layer are covered by the electrode layers.

8. The MEMS piezoelectric acoustics and vibration energy collector based on the hollowed-out diaphragm as claimed in claim 7, wherein: the sandwich structure (17) can be positioned on the upper surface or/and the lower surface of the diaphragm (9).

9. The organic vibration film (18) of claim 5, wherein the sandwich structure (17) is disposed on two sides of the organic vibration film (18), and the single side has a shape of 1-10 rectangles, trapezoids, or sectors, and is symmetrical with respect to the left and right.

10. The MEMS piezoelectric acoustics and vibration energy collector based on the hollowed-out diaphragm as claimed in claim 1, wherein: the piezoelectric material of the piezoelectric film layer (11) is PZT, AlN, ZnO or other piezoelectric film materials.

Technical Field

The invention relates to the field of micro-electro-mechanical systems, in particular to an MEMS piezoelectric acoustics and vibration energy collector based on a hollow vibrating diaphragm.

Background

MEMS, a micro electro mechanical system, represents a new device manufactured by micro-electronics and micro-machining technology, and has the advantages of small size, simple process, easy integration, convenient mass production, low cost, etc. The MEMS piezoelectric acoustics and vibration energy collector is an environmental energy collector prepared by an MEMS process, has the advantages of small volume, easy integration and the like, and can reduce the cost due to the batch process. MEMS energy harvesters can be divided into electromagnetic MEMS acoustics and vibration energy harvesters, electrostatic MEMS acoustics and vibration energy harvesters, and piezoelectric MEMS acoustics and vibration energy harvesters. The MEMS piezoelectric type acoustic and vibration energy collector is simpler in structural design, processing technology and integration technology, and is easier to realize a light and thin miniature high-performance acoustic and vibration energy collector.

In the related technology, the MEMS piezoelectric transducer is connected with the mass block and the acoustic coupling membrane, so that the mass block can vibrate under the excitation of external vibration and generate electric energy, and the acoustic coupling membrane can drive the mass block to vibrate under the excitation of an external sound field so as to generate electric energy and effectively convert vibration energy and acoustic energy in the environment into electric energy.

However, the first resonant frequency of the MEMS device in the related art is high, which results in poor low-frequency performance and is difficult to satisfy practical use. The first resonant frequency is limited by the resonant frequency of the MEMS piezoelectric transducer and is mainly determined by the rigidity of the MEMS piezoelectric transducer. Meanwhile, since the MEMS piezoelectric ring energy device has a small size, it is difficult to improve the efficiency of the acoustic and vibration energy harvester, and therefore, the system layer electromechanical coupling coefficient of the MEMS piezoelectric acoustic and vibration energy harvester needs to be optimized. In the design of the traditional MEMS piezoelectric acoustics and vibration energy collector, two means are mainly adopted to reduce the first resonant frequency of the device, and one means is to increase the mass of the mass block; and secondly, the thickness of the piezoelectric transducer is reduced. The mass is increased, the size of the electromechanical coupling coefficient of the system is not changed, and the improvement of the overall efficiency of the energy collector is not facilitated; the thickness of the piezoelectric acoustics and the vibration energy collector is reduced, the rigidity of the piezoelectric acoustics and the vibration energy collector is reduced, strain in the piezoelectric transducer is weakened, positive contribution to improvement of the electromechanical coupling coefficient of the piezoelectric acoustics and the vibration energy collector is avoided, and the electromechanical coupling coefficient of a device is difficult to reduce while the rigidity of the device is reduced by a traditional method. Thus. The traditional design of the MEMS piezoelectric acoustics and vibration energy collector is difficult to realize if two conditions of high efficiency and low first resonant frequency of the acoustics and vibration energy collector are simultaneously met.

Accordingly, there is a need for an improved MEMS piezoelectric acoustic and vibration energy harvester that addresses the above-mentioned problems.

Disclosure of Invention

In order to solve the problems, the invention discloses an MEMS piezoelectric acoustics and vibration energy collector based on a hollow vibrating diaphragm, which is used for simultaneously collecting vibration energy and acoustic energy in the environment and converting the vibration energy and the acoustic energy into electric energy.

An MEMS piezoelectric acoustics and vibration energy collector based on a hollow vibrating diaphragm can be used for collecting vibration and acoustics mechanical energy in an environment and converting the vibration and acoustics mechanical energy into electric energy. The MEMS piezoelectric acoustic and vibration energy harvester comprises: a substrate; the mass block is used for being connected with the external acoustic coupling membrane and collecting the environmental vibration energy; a back cavity located in the middle region; an insulating layer; the vibrating diaphragm is used for supporting the piezoelectric film and transmitting the mechanical energy generated by the piezoelectric film to the mass block; a top electrode; the piezoelectric film layer converts mechanical energy into electric energy through a piezoelectric effect; a bottom electrode.

Preferably, the diaphragm is composed of three parts: the piezoelectric thin film layer is arranged on the upper portion of the peripheral substrate, the upper portion or the lower portion of the piezoelectric thin film layer, and the structural beam portion connecting the middle mass block and the piezoelectric thin film. The vibrating diaphragm above or below the piezoelectric film adopts a hollow structure, and is processed to form a strip structure such as a grating or a hollow structure such as a wavy, net-shaped and porous structure.

Preferably, the shape of the structural beam part of the diaphragm can be an L-shaped curve, an S-shaped curve, a C-shaped curve and the like.

Preferably, the substrate is rectangular and the central region is the back cavity.

Preferably, the number of the mass blocks is 1-10, and the mass blocks are located in the middle of the device.

Preferably, the diaphragm, the top and bottom electrode layers and the piezoelectric film layer together form an organic diaphragm layer formed on the back cavity.

Preferably, the organic vibration film layer may be a connected whole or a plurality of discrete units, and is not limited to include the components, but may include additional structures such as an insulating layer, a passivation layer, a protective layer, and the like.

Preferably, the top and bottom electrode layers and the piezoelectric film layer are in a sandwich structure, the piezoelectric film is a single layer or multiple layers, and the upper and lower surfaces of the piezoelectric film are covered by the electrode layers.

Preferably, the sandwich structure may be located on the upper surface or/and the lower surface of the diaphragm.

Preferably, the sandwich structure is distributed on two sides of the organic vibration film layer, and the single side is 1-10 rectangles, trapezoids or sectors and is symmetrical about the left and right.

Preferably, the piezoelectric material is PZT, AlN, ZnO or other piezoelectric thin film material.

Preferably, the diaphragm is a single or composite film, and the material of the diaphragm is inorganic or organic.

The invention has the beneficial effects that:

compared with the related art:

1. the MEMS piezoelectric acoustics and vibration energy collector adopts the vibrating diaphragm with a hollow structure, the structure greatly reduces the structural rigidity of a device, and meanwhile, the strain generated in the piezoelectric film is not reduced; therefore, the dual requirements of reducing the rigidity of the MEMS piezoelectric acoustics and vibration energy collector and improving the electromechanical coupling coefficient are met.

2. The invention improves the low-frequency performance of the MEMS piezoelectric acoustics and vibration energy collector, increases the full-frequency-domain energy conversion efficiency of the device, and can reduce the first resonant frequency of the acoustics and vibration energy collection, improve the low-frequency performance and improve the efficiency of the system composite environment energy collection by being packaged with other parts in the piezoelectric acoustics and vibration energy collection device.

Drawings

FIG. 1 is a schematic structural diagram of a MEMS piezoelectric acoustic and vibration energy harvesting device in the related art;

FIG. 2 is a schematic structural diagram of a first embodiment of a MEMS piezoelectric acoustic and vibration energy harvester provided by the present invention;

FIG. 3 is a schematic cross-sectional view of a MEMS piezoelectric acoustic and vibrational energy harvester taken along plane A-A in accordance with an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a diaphragm of the MEMS piezoelectric acoustic and vibration energy harvester shown in FIG. 3;

FIG. 5 is a schematic cross-sectional view of a second embodiment of a MEMS piezoelectric acoustic and vibration energy harvester according to the present invention;

FIG. 6 is a schematic diagram of a three-diaphragm structure of an embodiment of the MEMS piezoelectric acoustic and vibration energy harvester provided by the present invention;

list of reference numerals:

wherein: 1-a MEMS acoustic and vibrational energy harvester device; 2-a sound membrane; 3-a coupling plate; 4-a PCB board; 5-a shell; 6-MEMS piezoelectric acoustics and vibration energy collector; 6-1 the MEMS piezoelectric acoustic and vibration energy harvester of embodiment one;

6-2 the MEMS piezoelectric acoustic and vibration energy harvester of embodiment two; 7, a rear cavity; 8, a dust screen; 9 vibrating diaphragm; 9-1 the diaphragm of embodiment one; 9-2 the diaphragm of embodiment three; 10 top electrodes; 11 a piezoelectric film; 12 a bottom electrode; 13 an insulating layer; 14 a substrate; 15 a back cavity; 16 mass blocks; 17 a piezoelectric thin film sandwich structure; 18 organic vibration film layer.

Detailed Description

The present invention will be further illustrated with reference to the accompanying drawings and specific embodiments, which are to be understood as merely illustrative of the invention and not as limiting the scope of the invention. It should be noted that the terms "front," "back," "left," "right," "upper" and "lower" used in the following description refer to directions in the drawings, and the terms "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of a particular component.

Fig. 1 is a schematic structural diagram of a MEMS piezoelectric acoustic and vibration energy harvester device in the related art, which includes: a housing 5 for supporting other components of the device; a sound diaphragm 2 capable of vibrating in a vertical direction with respect to the PCB board 4; the coupling plate 3 is used for connecting the sound membrane 2 and the mass block and transmitting acoustic and vibration mechanical energy in the environment to the MEMS piezoelectric transducer through the sound membrane and the mass block; the MEMS piezoelectric acoustics and vibration energy collector 6 converts mechanical energy in the environment into electric energy through an electromechanical coupling effect; the PCB 4 is used for exciting the MEMS piezoelectric acoustics and vibration energy collector 6; a dust screen 8 and a rear chamber 7. The MEMS piezoelectric acoustics and vibration energy collector 6 is a core component, and directly determines the sensitivity and the first resonant frequency of the acoustics and vibration energy collector.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In one embodiment of the invention, a MEMS piezoelectric acoustic and vibration energy harvester is provided.

Fig. 2 to fig. 4 are schematic structural diagrams of a first embodiment of the present invention. Fig. 2 is a schematic overall structure diagram of a first embodiment of the present invention; FIG. 3 is a schematic cross-sectional view of a MEMS piezoelectric acoustic and vibrational energy harvester taken along plane A-A in accordance with an embodiment of the present invention; fig. 4 is a schematic structural diagram of a diaphragm of an MEMS piezoelectric acoustic and vibration energy harvester according to an embodiment of the present invention.

Referring to fig. 2-3, the MEMS piezoelectric acoustic and vibration energy harvester 6 comprises: a substrate 14 for fixing the edge of the organic vibration film layer 18; a mass 16 generating an amplitude for connection with an external acoustic membrane; a back cavity 15 located in the middle region; an insulating layer 13; the vibrating diaphragm 9 is used for supporting the piezoelectric film sandwich structure 17 and transmitting the mechanical energy collected by the piezoelectric film sandwich structure to the mass block; a top electrode 10; the piezoelectric thin film layer 11 converts mechanical energy into electric energy through a piezoelectric effect; a bottom electrode 12.

The various parts of the MEMS piezoelectric acoustic and vibration energy harvester of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to fig. 4, in the present embodiment, the diaphragm 9 is composed of three parts: the piezoelectric thin film layer is arranged on the upper part of the peripheral substrate, the upper part or the lower part of the piezoelectric thin film layer, and the structural beam part connecting the middle mass block and the piezoelectric thin film. The vibrating diaphragm above or below the piezoelectric film is in a hollow structure, and a grating strip structure is formed by etching and is bilaterally symmetrical.

It should be noted that, in the embodiment, the hollow diaphragm of the MEMS piezoelectric acoustic and vibration energy collector is not limited to the grating strip structure, and the invention may also include other hollow structures, such as raised patterns, mesh structures, porous structures, and the like. Meanwhile, the structural beam part connected with the piezoelectric film in the diaphragm can be an L-shaped curve, an S-shaped curve, a C-shaped curve and the like.

Referring to fig. 2 to 3, in the present embodiment, the substrate 14 of the MEMS piezoelectric acoustic and vibration energy harvester 6 is rectangular, the central region is the back cavity 15, and the corners are processed by arc transition; the mass 16 is located in the very middle of the device. The diaphragm 9, the top and bottom electrode layers 10 and 12 and the piezoelectric film layer 11 together form an organic diaphragm layer 18 formed on the back cavity 15. The electrode layers 10 and 12 and the piezoelectric film layer 11 are in a sandwich structure 17, and the upper surface and the lower surface of the piezoelectric film are covered by the electrode layers and are positioned on the lower surface of the vibrating diaphragm 9. The sandwich structure 17 is distributed on two sides of the organic vibration film layer, and the shape of a single side is rectangular.

It should be noted that, in the embodiments, the organic diaphragm layer of the MEMS piezoelectric acoustic and vibration energy harvester may be a connected whole or a plurality of discrete units, and is not limited to include the above components, and may further include additional structures such as an insulating layer, a passivation layer, and a protection layer, which may be selected according to actual requirements. Meanwhile, the piezoelectric material is PZT, AlN, ZnO or other piezoelectric thin film materials and has a single-layer or multi-layer structure; the single-sided sandwich structure 17 may be 1-10 rectangles, trapezoids, or sectors, which are bilaterally symmetric about the center. The diaphragm 9 may be a single or composite film, and the material thereof may be inorganic or organic, and is specifically selected according to actual requirements.

Fig. 5 is a schematic structural cross-sectional view according to a second embodiment of the present invention. In the second embodiment of the invention, a MEMS piezoelectric acoustic and vibration energy harvester is provided; the structure of the piezoelectric acoustic and vibration energy harvester is basically the same as that of the piezoelectric acoustic and vibration energy harvester described in the first embodiment, and the difference is that:

in the embodiment, the sandwich structure 17 of the MEMS piezoelectric acoustic and vibration energy harvester is located on the upper surface of the diaphragm 9. In the specific process steps, the differences from the first embodiment are large, and the specific process steps can be selected according to actual requirements.

Fig. 5 is a schematic view of a diaphragm structure according to a third embodiment of the present invention. In a third embodiment of the present invention, a diaphragm with a mesh structure for an MEMS piezoelectric energy harvester is provided. Compared with the diaphragm with the grating structure in the first embodiment, the diaphragm with the grating structure has higher transverse rigidity, is favorable for structural stability, and can be selected according to actual requirements.

Compared with the prior art, the MEMS piezoelectric acoustics and vibration energy collector adopts the vibrating diaphragm with a hollow structure. The structure greatly reduces the structural rigidity of the device, and simultaneously, the strain generated in the piezoelectric film is not reduced or even increased. Therefore, the dual requirements that the rigidity of the MEMS piezoelectric acoustics and vibration energy collector is reduced and the electromechanical coupling coefficient is not reduced are met. The MEMS piezoelectric acoustics and vibration energy collector is packaged with other parts in the piezoelectric acoustics and vibration energy collector device, so that the low-frequency performance of the energy collector can be improved, and the conversion efficiency of environmental acoustics and vibration energy is improved.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.