阅读说明：本技术 一种压电传感器 (Piezoelectric sensor ) 是由 马春林 程菊 冯小勤 于 2020-05-19 设计创作，主要内容包括：本发明涉及传感器技术领域,具体的说是一种压电传感器,包括基板、设置于基板上的下部电极、设置于下部电极上的压电薄膜及设置于压电薄膜上的上部电极；所述基板包括硅基底板、柔性弧形基底及柔性顶板,所述硅基底板之间设置有辅助槽口,所述辅助槽口两侧边之间设置有向上拱起的柔性弧形基底,所述柔性弧形基底及柔性顶板所用的材料为聚二甲基硅氧烷；本发明通过改变压电传感器的结构以优化对应的谐振频率和有效质量分布状态,进而提高压电传感器的灵敏度。(The invention relates to the technical field of sensors, in particular to a piezoelectric sensor, which comprises a substrate, a lower electrode arranged on the substrate, a piezoelectric film arranged on the lower electrode and an upper electrode arranged on the piezoelectric film, wherein the piezoelectric film is arranged on the upper electrode; the substrate comprises silicon substrate plates, flexible arc-shaped substrates and flexible top plates, wherein auxiliary notches are formed among the silicon substrate plates, the flexible arc-shaped substrates which are arched upwards are arranged between two side edges of each auxiliary notch, and the flexible arc-shaped substrates and the flexible top plates are made of polydimethylsiloxane; the invention optimizes the corresponding resonance frequency and effective mass distribution state by changing the structure of the piezoelectric sensor, thereby improving the sensitivity of the piezoelectric sensor.)

1. A piezoelectric sensor, characterized by: comprises a substrate, a lower electrode (5) arranged on the substrate, a piezoelectric film (6) arranged on the lower electrode (5) and an upper electrode (7) arranged on the piezoelectric film (6); the substrate comprises silicon substrate plates (1), flexible arc-shaped substrates (3) and flexible top plates (4), auxiliary notches (2) are formed between the silicon substrate plates (1), the flexible arc-shaped substrates (3) which are arched upwards are arranged between two side edges of the auxiliary notches (2), and the flexible arc-shaped substrates (3) and the flexible top plates (4) are made of polydimethylsiloxane; be provided with flexible roof (4) on flexible arc basement (3), side bonding is gone up with flexible arc basement (3) to flexible roof (4) middle part downside, flexible roof (4) both ends downside extends to flexible roof (4) upper surface and bonds rather than, flexible roof (4) upper surface and lower surface bonding of lower part electrode (5).

2. A piezoelectric transducer according to claim 1, wherein: the piezoelectric thin film (6) is a laminate in which a plurality of film-like piezoelectric bodies are laminated, and the film-like piezoelectric bodies are vinylidene fluoride-tetrafluoroethylene copolymer piezoelectric bodies.

3. A piezoelectric transducer according to claim 1, wherein: and an upward convex boss is arranged at the upper end of the upper electrode (7) along the edge of the upper electrode.

4. A piezoelectric transducer according to claim 1, wherein: a plurality of first hollow-out grooves (11) are formed in the flexible top plate (4) at intervals, and the first hollow-out grooves (11) are communicated with the external space through first release holes (8) which penetrate through the lower electrode (5), the piezoelectric film (6) and the upper electrode (7) in sequence.

5. A piezoelectric transducer according to claim 4, wherein: the upper electrode (7) upper end interval is provided with a plurality of first heavy grooves (9), first heavy groove (9) all arrange along the fore-and-aft direction, first heavy groove (9) are located adjacently between first fretwork groove (11).

6. A piezoelectric transducer according to claim 5, wherein: and a second hollow-out groove (12) is correspondingly arranged on the lower electrode (5) below the first sinking groove (9), and the second hollow-out groove (12) is communicated with the first sinking groove (9) through a second release hole (10).

Technical Field

The invention relates to the technical field of sensors, in particular to a piezoelectric sensor.

Background

As a transducer for converting mechanical energy and electrical energy into each other, a sensor is now widely used in consumer electronics products such as mobile phones, computers, cameras, etc., as well as in the fields of industry, life health monitoring, etc. The traditional sensor mainly comprises a capacitance type sensor and a piezoelectric type sensor, wherein the capacitance type sensor adopts a double-layer membrane structure, and the voltage between conductors is changed by utilizing the charge-discharge principle of the capacitance between the conductors, so that the conversion from mechanical energy to electric energy is realized. Although the capacitive sensor has the advantages of extremely wide frequency response range, quick instant response and the like, the capacitive sensor is fragile, is afraid of damp and falling, needs direct-current voltage and still has a great problem in practical application. The piezoelectric micro mass sensor detects the substance components mainly by measuring the structural resonance frequency change caused by the mass of the substance attached to the sensor surface, has the characteristics of simple structure, quick response, low cost and high precision, and has wide application in the aspects of microbial detection such as bacteria and viruses, micro particles, gas/liquid components and concentration and the like.

At present, most of piezoelectric sensors are manufactured into cantilever beams or partition plate structures with uniform thickness, for example, chinese patent application No. 2014800377487 discloses a piezoelectric sensor, which has great advantages in stability, water resistance, moisture resistance and structural preparation over capacitive sensors, but the piezoelectric performance is reduced to some extent, which results in reducing the sensitivity of the piezoelectric sensor and affecting the performance of the sensor.

For this reason, the present company has designed a piezoelectric sensor, which has improved sensitivity by changing the structure of the piezoelectric sensor to optimize the corresponding resonance frequency and effective mass distribution state.

Disclosure of Invention

The invention provides a piezoelectric sensor, which aims to make up for the defects of the prior art and solve the problem that the low sensitivity of the conventional piezoelectric sensor influences the performance of the sensor.

The technical scheme adopted by the invention for solving the technical problems is as follows: a piezoelectric sensor includes a substrate, a lower electrode disposed on the substrate, a piezoelectric film disposed on the lower electrode, and an upper electrode disposed on the piezoelectric film; the substrate comprises silicon substrate plates, flexible arc-shaped substrates and flexible top plates, wherein auxiliary notches are formed among the silicon substrate plates, the flexible arc-shaped substrates which are arched upwards are arranged between two side edges of each auxiliary notch, and the flexible arc-shaped substrates and the flexible top plates are made of polydimethylsiloxane; the flexible arc-shaped substrate is provided with a flexible top plate, the lower side surface of the middle part of the flexible top plate is bonded with the upper side surface of the flexible arc-shaped substrate, the lower side surfaces of two ends of the flexible top plate extend to the upper surface of the flexible top plate and are bonded with the upper surface of the flexible top plate, and the upper surface of the flexible top plate is bonded with the lower surface of the lower electrode; when the sensor is used, when the sensor senses an audio signal, sound pressure acts on the upper surface of the upper electrode, so that strain deformation of the upper electrode, the piezoelectric film, the lower electrode, the flexible top plate and the flexible arc-shaped substrate is caused, electric charges are generated on the surface of the piezoelectric film under the piezoelectric action of the piezoelectric film, and electric signals are output through the lower electrode and the upper electrode; the flexible arc-shaped substrate that upwards arches is adopted to piezoelectric film below, compares current flat base, and flexible arc-shaped substrate can have better flexural deformation, and piezoelectric film's strain degree obtains strengthening to export stronger signal of telecommunication, promote piezoelectric sensor's sensitivity.

Preferably, the piezoelectric thin film is a laminate in which a plurality of film-like piezoelectric bodies are laminated, and the film-like piezoelectric bodies are vinylidene fluoride-tetrafluoroethylene copolymer piezoelectric bodies; the present invention is a piezoelectric thin film made of a vinylidene fluoride-tetrafluoroethylene copolymer, which has a large output electric signal in a region from an ultra low frequency to a high frequency, compared to a polyvinylidene fluoride material, and therefore, the frequency dependence of the output electric signal of the piezoelectric thin film can be reduced, and the sensitivity of a piezoelectric sensor can be improved; in addition, it still has comparatively ideal compliance and impact strength for polyvinylidene fluoride material, and flexural modulus is lower, consequently can be better with flexible arc base cooperation strengthen the strain degree to output stronger signal of telecommunication, promote piezoelectric sensor's sensitivity.

Preferably, the upper end of the upper electrode is provided with an upward convex boss along the edge thereof; it is known that the propagation of the vibration wave is directly affected by the cut-off frequency in the region, when the boss is provided, the thickness of the upper end edge of the upper electrode is larger than the thickness of the middle of the upper electrode, and the cut-off frequency at the edge of the upper electrode is lower than the cut-off frequency at the middle of the upper electrode according to the mass loading effect, so that when the applied frequency is between the cut-off frequency at the edge of the upper electrode and the cut-off frequency at the middle of the upper electrode, the middle of the upper electrode becomes the propagation region, and the edge of the upper electrode becomes the cut-off region, thereby forming the closed resonance, resulting in less energy loss and improving the sensitivity of the piezoelectric.

Preferably, a plurality of first hollow-out grooves are arranged on the flexible top plate at intervals, and the first hollow-out grooves are communicated with the external space through first release holes which sequentially penetrate through the lower electrode, the piezoelectric film and the upper electrode; due to the existence of the first hollow-out groove, the flexural deformation of the piezoelectric film is increased, the strain degree of the piezoelectric film is enhanced, a stronger electric signal is output, and the sensitivity of the piezoelectric sensor is improved.

Preferably, a plurality of first sinking grooves are arranged at intervals at the upper end of the upper electrode, the first sinking grooves are arranged along the front-back direction, and the first sinking grooves are positioned between the adjacent first hollow-out grooves; the arrangement of the first sinking groove can increase the flexural deformation of the piezoelectric film and improve the sensitivity of the piezoelectric sensor; meanwhile, the arrangement of the first sinking groove can facilitate the etching of the second hollow-out groove, and the production efficiency is improved; in addition, the arrangement of the first sinking groove reduces the whole weight of the upper electrode to a certain extent, and reduces the cost.

Preferably, a second hollow-out groove is correspondingly arranged on the lower electrode below the first sinking groove and is communicated with the first sinking groove through a second release hole; the second hollow groove is provided to increase the flexural deformation of the piezoelectric film and enhance the strain degree of the piezoelectric film, thereby outputting a stronger electric signal and improving the sensitivity of the piezoelectric sensor, and the second hollow groove and the first hollow groove have different capacities to obtain different frequency characteristics, thereby achieving a good filtering characteristic, preventing pressure fluctuations in other frequency bands than a desired frequency band between the different frequencies, and further having a good sensitivity to pressure fluctuations in the desired frequency band.

The invention has the following beneficial effects:

1. according to the piezoelectric sensor, the flexible arc-shaped substrate which is arched upwards is adopted below the piezoelectric film, compared with the existing flat-bottom substrate, the flexible arc-shaped substrate can be better in flexural deformation, the strain degree of the piezoelectric film is enhanced, and therefore a stronger electric signal is output, and the sensitivity of the piezoelectric sensor is improved.

2. According to the piezoelectric sensor, the vinylidene fluoride-tetrafluoroethylene copolymer is adopted to prepare the piezoelectric film, so that the frequency dependence of the output electric signal of the piezoelectric film is reduced, and the sensitivity of the piezoelectric sensor is improved; in addition, compared with a polyvinylidene fluoride material, the polyvinylidene fluoride piezoelectric sensor has ideal flexibility and impact strength and low bending modulus, so that the polyvinylidene fluoride piezoelectric sensor can be better matched with a flexible arc-shaped substrate to enhance the strain degree, further output a stronger electric signal and further improve the sensitivity of the piezoelectric sensor.

3. According to the piezoelectric sensor, the upper end of the upper electrode is provided with the convex boss along the edge, the thickness of the edge of the upper end of the upper electrode is larger than the thickness of the middle of the upper electrode, and the cutoff frequency at the edge of the upper electrode is lower than the cutoff frequency at the middle of the upper electrode according to the mass load effect calculation, so that when the applied frequency is between the cutoff frequency at the edge of the upper electrode and the cutoff frequency at the middle of the upper electrode, the middle of the upper electrode becomes a propagation region, and the edge of the upper electrode becomes a cutoff region, so that closed resonance is formed, the energy loss is less, and the sensitivity of the piezoelectric sensor is improved.

4. According to the piezoelectric sensor, through the arrangement of the first sinking groove, the first hollow groove and the second hollow groove, the flexural deformation of the piezoelectric film can be increased, the strain degree of the piezoelectric film is enhanced, so that a stronger electric signal is output, and the sensitivity of the piezoelectric sensor is improved; and simultaneously, the filter can realize good filtering characteristics, can prevent pressure fluctuation of other frequency bands except for a desired frequency band among different frequencies, and further has good sensitivity to the pressure fluctuation of the desired frequency band.

Drawings

The invention will be further explained with reference to the drawings.

FIG. 1 is a perspective view of the present invention;

FIG. 2 is a top view of the present invention;

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2;

FIG. 4 is an enlarged view of a portion of FIG. 3 at B;

in the figure:

the device comprises a silicon substrate plate 1, an auxiliary notch 2, a flexible arc-shaped substrate 3, a flexible top plate 4, a lower electrode 5, a piezoelectric film 6, an upper electrode 7, a first release hole 8, a first sinking groove 9, a second release hole 10, a first hollow groove 11 and a second hollow groove 12.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

As shown in fig. 1 to 4, a piezoelectric sensor includes a substrate, a lower electrode 5 provided on the substrate, a piezoelectric film 6 provided on the lower electrode 5, and an upper electrode 7 provided on the piezoelectric film 6; the substrate comprises silicon substrate plates 1, flexible arc-shaped substrates 3 and flexible top plates 4, auxiliary notches 2 are formed among the silicon substrate plates 1, the flexible arc-shaped substrates 3 which are arched upwards are arranged between two side edges of the auxiliary notches 2, and the flexible arc-shaped substrates 3 and the flexible top plates 4 are made of polydimethylsiloxane; a flexible top plate 4 is arranged on the flexible arc-shaped substrate 3, the lower side surface of the middle part of the flexible top plate 4 is bonded with the upper side surface of the flexible arc-shaped substrate 3, the lower side surfaces of two ends of the flexible top plate 4 extend to the upper surface of the flexible top plate 4 and are bonded with the upper surface of the flexible top plate 4, and the upper surface of the flexible top plate 4 is bonded with the lower surface of the lower electrode 5;

when the sensor is used, when the sensor senses an audio signal, sound pressure acts on the upper surface of the upper electrode 7, so that strain deformation of the upper electrode 7, the piezoelectric film 6, the lower electrode 5, the flexible top plate 4 and the flexible arc-shaped substrate 3 is caused, electric charges are generated on the surface of the piezoelectric film 6 under the piezoelectric action of the piezoelectric film 6, and the electric signal is output through the lower electrode 5 and the upper electrode 7; the flexible arc-shaped substrate 3 that upwards arches is adopted to 6 below piezoelectric film, compares current flat bed base, and flexible arc-shaped substrate 3 can have better flexural deformation, and piezoelectric film 6's strain degree obtains strengthening to export stronger signal of telecommunication, promote piezoelectric sensor's sensitivity.

In one embodiment of the present invention, the piezoelectric thin film 6 is a laminate in which a plurality of film-like piezoelectric bodies are laminated, and the film-like piezoelectric bodies are vinylidene fluoride-tetrafluoroethylene copolymer piezoelectric bodies; most of the conventional piezoelectric films 6 are made of polyvinylidene fluoride, and the voltage of the electrical signal actually measured tends to be lower as the frequency is lower and higher as the frequency is higher, so that the piezoelectric film 6 made of the vinylidene fluoride-tetrafluoroethylene copolymer has a larger output electrical signal in a region from an ultra-low frequency to a high frequency compared with the polyvinylidene fluoride material, and therefore, the frequency dependence of the output electrical signal of the piezoelectric film 6 can be reduced, and the sensitivity of the piezoelectric sensor can be improved; in addition, it still has comparatively ideal compliance and impact strength for polyvinylidene fluoride material, and flexural modulus is lower, consequently can be better with flexible arc base 3 cooperation strengthen the strain degree to output stronger signal of telecommunication, promote piezoelectric sensor's sensitivity.

In one embodiment of the present invention, the upper end of the upper electrode 7 is provided with a convex boss (not shown) along the edge thereof; it is known that the propagation of the vibration wave is directly affected by the cut-off frequency in the region, when the boss is provided, the thickness of the upper end edge of the upper electrode 7 is larger than the thickness of the middle thereof, and the cut-off frequency at the edge of the upper electrode 7 is lower than the cut-off frequency at the middle of the upper electrode 7 as calculated from the mass loading effect, so that when the applied frequency is between the cut-off frequency at the edge of the upper electrode 7 and the cut-off frequency at the middle of the upper electrode 7, the middle of the upper electrode 7 becomes the propagation region, and the edge of the upper electrode 7 becomes the cut-off region, thereby forming a closed resonance, resulting in less energy loss and improved sensitivity of the piezoelectric sensor.

In one embodiment of the present invention, a plurality of first hollow-out grooves 11 are formed at intervals in the flexible top plate 4, and the first hollow-out grooves 11 communicate with an external space through first release holes 8 which sequentially penetrate through the lower electrode 5, the piezoelectric film 6, and the upper electrode 7; due to the existence of the first hollow-out groove 11, the flexural deformation of the piezoelectric film 6 is increased, the strain degree of the piezoelectric film 6 is strengthened, a stronger electric signal is output, and the sensitivity of the piezoelectric sensor is improved.

As an embodiment of the present invention, a plurality of first sinking grooves 9 are arranged at intervals at the upper end of the upper electrode 7, the first sinking grooves 9 are all arranged along the front-back direction, and the first sinking grooves 9 are located between adjacent first hollow-out grooves 11; the arrangement of the first sinking groove 9 can increase the flexural deformation of the piezoelectric film 6 and improve the sensitivity of the piezoelectric sensor; meanwhile, the arrangement of the first sinking groove 9 can also facilitate the etching of the second hollow-out groove 12, and the production efficiency is improved; in addition, the arrangement of the first sinking groove 9 also reduces the whole weight of the upper electrode 7 to a certain extent, and reduces the cost.

As an embodiment of the present invention, a second hollow-out groove 12 is correspondingly disposed on the lower electrode 5 below the first sinking groove 9, and the second hollow-out groove 12 is communicated with the first sinking groove 9 through a second release hole 10; the second hollow-out groove 12 is provided to increase the flexural deformation of the piezoelectric film 6 and to enhance the degree of strain of the piezoelectric film 6, thereby outputting a stronger electric signal and improving the sensitivity of the piezoelectric sensor, and to obtain different frequency characteristics by making the capacities of the second hollow-out groove 12 and the first hollow-out groove 11 different from each other, thereby achieving a good filtering characteristic, preventing pressure fluctuations in other frequency bands than the desired frequency band between the different frequencies, and further having a good sensitivity to pressure fluctuations in the desired frequency band.

When the sensor is used, when the sensor senses an audio signal, sound pressure acts on the upper surface of the upper electrode 7, so that strain deformation of the upper electrode 7, the piezoelectric film 6, the lower electrode 5, the flexible top plate 4 and the flexible arc-shaped substrate 3 is caused, electric charges are generated on the surface of the piezoelectric film 6 under the piezoelectric action of the piezoelectric film 6, and the electric signal is output through the lower electrode 5 and the upper electrode 7; the flexible arc-shaped substrate 3 which is arched upwards is adopted below the piezoelectric film 6, compared with the existing flat substrate, the flexible arc-shaped substrate 3 can be better in flexural deformation, and the strain degree of the piezoelectric film 6 is enhanced, so that a stronger electric signal is output, and the sensitivity of the piezoelectric sensor is improved; the piezoelectric film 6 is made of the vinylidene fluoride-tetrafluoroethylene copolymer, and has a larger output electric signal in a region from ultralow frequency to high frequency compared with a polyvinylidene fluoride material, so that the frequency dependence of the output electric signal of the piezoelectric film 6 is reduced, the sensitivity of the piezoelectric sensor is improved, and in addition, the piezoelectric film has ideal flexibility and impact strength compared with the polyvinylidene fluoride material, and the bending modulus is lower, so that the piezoelectric film can be better matched with the flexible arc-shaped substrate 3 to strengthen the strain degree, thereby outputting a stronger electric signal and improving the sensitivity of the piezoelectric sensor; it is known that the propagation of the vibration wave is directly affected by the cut-off frequency in the region, when the boss is provided, the thickness of the upper end edge of the upper electrode 7 is larger than the thickness of the middle of the upper electrode, and the cut-off frequency at the edge of the upper electrode 7 is lower than the cut-off frequency at the middle of the upper electrode 7 according to the mass load effect calculation, so that when the applied frequency is between the cut-off frequency at the edge of the upper electrode 7 and the cut-off frequency at the middle of the upper electrode 7, the middle of the upper electrode 7 becomes the propagation region, and the edge of the upper electrode 7 becomes the cut-off region, thereby forming the closed resonance, leading to less energy loss and improving the sensitivity of the; the first sinking groove 9, the first hollow groove 11 and the second hollow groove 12 are arranged, so that the flexural deformation of the piezoelectric film 6 can be increased, the strain degree of the piezoelectric film 6 is enhanced, a stronger electric signal is output, the sensitivity of the piezoelectric sensor is improved, different frequency characteristics can be obtained by making the capacities of the second hollow groove 12 and the first hollow groove 11 different, good filtering characteristics can be realized, pressure variations of other frequency bands except for the expected frequency band between the different frequencies can be prevented, and further, the sensitivity to the pressure variations of the expected frequency band is good.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.