Piezoelectric MEMS pressure sensor and electronic cigarette comprising same

Abstract

The present invention relates to the manufacturing of sensitive elements and sensors in the core electronics industry, and in particular to a piezoelectric MEMS pressure sensor and an electronic cigarette comprising same. The piezoelectric MEMS pressure sensor of the present invention comprises: an MEMS chip, wherein the MEMS chip comprises a piezoelectric layer, a central electrode, which is formed on the piezoelectric layer and is arranged close to the center of the MEMS chip, and a peripheral electrode, which is formed on the piezoelectric layer, arranged on the periphery of the central electrode, and insulated from the central electrode; and an ASIC chip, wherein signals collected by the central electrode and the peripheral electrode of the MEMS chip are respectively input into two input ends of the ASIC chip, and the ASIC chip is used for using the two signals to determine the state of the MEMS chip. In the present invention, the state of the MEMS chip is determined by means of electrical signals output by the central electrode and the peripheral electrode, so that the problem of the unintended activation of the electronic cigarette caused by a sudden temperature change can be effectively avoided.

Description

Piezoelectric MEMS pressure sensor and electronic cigarette including the same Technical Field

[0001] The present invention relates to the manufacture of sensitive components and sensors in the core electronics industry, and in particular to a piezoelectric MEMS pressure sensor and an electronic cigarette including the same. Background Art

[0002] E-cigarettes are electronic products that mimic cigarettes. They heat liquid e-liquid to produce an aerosol that is inhaled, mimicking the effects of smoking a real cigarette. Because e-cigarettes lack major harmful substances like carbon monoxide and tar, they are far less harmful than real cigarettes, making them increasingly popular among ex-smokers and young people. When smokers use an e-cigarette, a certain degree of negative pressure is generated in the smoke passage, causing the pressure sensor membrane to deform, outputting an electrical signal and activating the e-cigarette. When the e-cigarette stops smoking, it shuts down. Currently, pressure sensors in e-cigarettes are mostly capacitive, but the relationship between applied pressure differential and capacitance change is nonlinear. However, due to the interlayer between the diaphragm and the backplate, the intrusion of moisture and e-liquid can cause abnormal capacitance changes in the sensor, leading to malfunction. In contrast, piezoelectric MEMS pressure sensors utilize a single-layer, sealed membrane design, offering advantages such as dust, water, and oil resistance, and can operate stably in harsh environments with high humidity and strong corrosion.

[0003] Piezoelectric materials exhibit a pyroelectric effect under non-isothermal conditions, limiting their operation to environments with minimal temperature fluctuations. When an e-cigarette is operating, the electronic components within it generate heat, causing the piezoelectric pressure sensor to experience a rapid temperature change, leading to a pyroelectric effect. The pyroelectric output signal can interfere with the output signal caused by the pressure differential, resulting in false triggering and a negative impact on the user experience. Summary of the Invention

[0004] (1) Technical issues to be resolved

[0005] The present invention is intended to at least partially solve one of the above technical problems.

[0006] (2) Technical solution

[0007] The first aspect of the present invention provides a piezoelectric MEMS pressure sensor. The piezoelectric MEMS pressure sensor comprises a MEMS chip including a piezoelectric layer; a central electrode formed on the piezoelectric layer and disposed near the center of the MEMS chip; peripheral electrodes formed on the piezoelectric layer and disposed peripherally of the central electrode, the peripheral electrodes being insulated from the central electrode; and an ASIC chip having two input terminals that respectively input signals collected by the central electrode and the peripheral electrodes of the MEMS chip, for determining the state of the MEMS chip using the two signals.

[0008] In some embodiments of the present invention, the ASIC chip includes: a divider, whose input terminal inputs the signals collected by the central electrode and the peripheral electrode of the MEMS chip, and whose output terminal outputs the quotient of the two signal voltages; a first comparator, which compares the quotient with the size of a first preset threshold α, 0<α≤100.

[0009] In some embodiments of the present invention, the ASIC chip further includes: a third comparator, whose input terminal receives a signal collected by the central electrode of the MEMS chip and compares the voltage of the signal with a third preset threshold value; the ASIC chip further includes: a main logic circuit, whose input terminal is connected to the output terminals of the first comparator and the third comparator, and is used to determine the status of the MEMS chip based on the outputs of the two comparators.

[0010] In some embodiments of the present invention, the ASIC chip further includes: a multiplier, whose input terminal inputs the signals collected by the central electrode and the peripheral electrodes of the MEMS chip, and whose output terminal outputs the product of the two signal voltages; a second comparator, which compares the product with the size of a second preset threshold; and a total logic circuit, whose input terminal is connected to the output terminals of the first comparator, the second comparator, and the third comparator, and is used to judge the status of the MEMS chip based on the outputs of the three.

[0011] In some embodiments of the present invention, for the first comparator, when the quotient is less than the first preset threshold, the output is "0"; otherwise, the output is "1"; for the second comparator, when the product is greater than the second preset threshold, the output is "0"; otherwise, the output is "1"; for the third comparator, when the voltage of the signal collected by the central electrode of the MEMS chip is greater than the third preset threshold, the output is "1"; otherwise, the output is "0"; the overall logic circuit includes: an AND gate, which outputs "1" when the outputs of the first comparator, the second comparator, and the third comparator are all "1"; otherwise, the output is "0".

[0012] In some embodiments of the present invention, the ASIC chip includes: a differential amplifier module, whose two input terminals respectively input signals collected by the central electrode and peripheral electrodes of the MEMS chip, and whose output terminal outputs the difference between the two signal voltages; an Ath comparator, which compares the difference with the size of the Ath comparison threshold β, 50mV<β≤500mV; a logic control module, whose input terminal is connected to the output terminal of the Ath comparator, and is used to: ① output "1" when the difference is greater than or equal to the Ath comparison threshold β; ② output "0" when the difference is less than the Ath comparison threshold β.

[0013] A second aspect of the present invention provides an electronic cigarette. The electronic cigarette comprises: an electronic cigarette body, an atomizer disposed therein; a controller disposed within the electronic cigarette body; and a piezoelectric MEMS pressure sensor, as described above, encapsulated within the electronic cigarette body and connected to the controller. When the piezoelectric MEMS pressure sensor senses a user's inhalation signal, the controller controls a drive circuit to activate the atomizer.

[0014] (3) Beneficial effects

[0015] It can be seen from the above technical solutions that the present invention has at least one of the following beneficial effects compared to the prior art:

[0016] (1) The present invention divides the upper electrode layer into two parts, the middle and the outer ring, by design. The lower electrode serves as the electrode common end (the common end generally refers to the position of the baseline, which can be the ground or a constant voltage). The central electrode and the outer ring electrode respectively output electrical signals. The state of the MEMS chip is judged by the electrical signals output by the central electrode and the outer ring electrode, which can effectively avoid the problem of false start of the electronic cigarette due to sudden temperature changes.

[0017] (2) In the present invention, the quotient of the signal voltages collected by the central electrode and the peripheral electrode is determined. If the quotient is less than the first preset threshold value α, it can be determined that the pyroelectric effect affects the piezoelectric effect. If the quotient is greater than or equal to the first preset threshold value α, it can be determined that the pyroelectric effect can be ignored when processing the piezoelectric signal, thereby providing a basis for the credibility of the subsequent piezoelectric signal and greatly improving the anti-interference ability of the piezoelectric MEMS pressure sensor.

[0018] (3) In order to adapt to the judgment of whether there is a pyroelectric effect by the quotient of the signal voltage, the present invention provides four typical MEMS chips that can achieve the voltage sensitivity ratio of the central electrode to the outer ring electrode. of adjustment.

[0019] (4) The present invention proposes a new MEMS chip in which the lower electrodes are all grounded, and the piezoelectric layer and the upper electrode are divided into a center and an outer ring. The outer side of the outer ring piezoelectric layer is aligned with the outer edge of the substrate, and the inner side is aligned with the edge of the back cavity. The outer diameter of the outer ring electrode is larger than the back cavity radius R, and the inner diameter is consistent with the back cavity radius R. The radius of the center electrode and the center piezoelectric layer are consistent and smaller than the back cavity radius R.

[0020] For this MEMS chip, the sensitivity ratio of the central electrode to the outer ring electrode is The ratio of the pyroelectric output voltage of the central electrode and the outer ring electrode is is a finite value. The central piezoelectric layer radius is smaller than the back cavity radius R, which helps release the degree of freedom of the central piezoelectric layer to reduce bending stiffness, increase the bending deformation amplitude of the piezoelectric composite vibration layer, and all stresses on the piezoelectric layer's mid-surface have the same sign. Compared to other MEMS chip structures with fully covered piezoelectric layers, this MEMS chip structure can increase the area of ​​the central electrode, reduce output impedance, increase output charge, and facilitate further device miniaturization.

[0021] (5) In the present invention, the ASIC includes a multiplication comparison circuit. In the logic of the multiplication comparison circuit, the center electrode and the outer ring electrode are multiplied by V1×V2. When V1×V2 is greater than a certain set threshold (the user can set the threshold according to the actual application scenario), the circuit design can lock the temperature rise rate MAX or the maximum suction force MAX for the user. When the threshold is exceeded, the airflow sensor will automatically cut off the output, playing a safety protection role. When V1×V2 is less than the set threshold (which can be adjusted according to the user's actual application plan), the device is in normal operation.

[0022] (6) In the present invention, the difference method is used to process the signals of the central electrode and the peripheral electrode, which can improve the measurement accuracy and enhance the anti-interference performance, while simplifying the signal processing circuit and achieving lower cost.

[0023] (7) In the present invention, the ASIC chip also has a periodic reset design, which can effectively eliminate the extra superposition state of the MEMS chip, so that the MEMS chip can operate stably in the initial trigger state for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a circuit diagram of a piezoelectric MEMS pressure sensor according to a first embodiment of the present invention.

[0025] 2A and 2B are respectively a perspective view and a cross-sectional view of the MEMS chip in the piezoelectric MEMS pressure sensor shown in FIG. 1 .

[0026] FIG3 is a simplified model of the piezoelectric composite vibration layer structure and a schematic diagram of the normalized stress distribution on the mid-surface of the piezoelectric layer.

[0027] 4A to 4D are schematic diagrams of outer ring electrodes and middle electrodes of four typical MEMS chip electrodes in the present invention.

[0028] FIG5 is a schematic cross-sectional view of another MEMS chip in the present invention.

[0029] FIG6 is a circuit diagram of a divider according to an embodiment of the present invention.

[0030] FIG7 is a circuit diagram of a second embodiment of a piezoelectric MEMS pressure sensor according to the present invention.

[0031] FIG8 is a schematic diagram of signal processing of the ASIC chip in the piezoelectric MEMS pressure sensor shown in FIG7 . DETAILED DESCRIPTION

[0032] The present invention proposes a piezoelectric MEMS pressure sensor with a pyroelectric recognition function, which can effectively avoid false start-up caused by pyroelectricity during operation.

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods and with reference to the accompanying drawings.

[0034] A first aspect of the present invention provides a piezoelectric MEMS pressure sensor. Figure 1 is a circuit diagram of a piezoelectric MEMS pressure sensor according to a first embodiment of the present invention. Figures 2A and 2B are, respectively, a perspective view and a cross-sectional view of the MEMS chip in the piezoelectric MEMS pressure sensor shown in Figure 1. Referring to Figures 1, 2A, 2B, and 3, the piezoelectric MEMS pressure sensor of this embodiment includes a MEMS chip and an ASIC chip, with electrical signals connected between the two chips via gold wire bonding.

[0035] The MEMS chip includes: a substrate including an outer ring and a cavity; a support layer formed on the substrate; a lower electrode formed on the support layer and electrically grounded; a piezoelectric layer formed on the lower electrode; a central electrode formed on the piezoelectric layer and disposed near the center of the MEMS chip; and peripheral electrodes formed on the piezoelectric layer and disposed around the central electrode, wherein the peripheral electrodes are insulated from the central electrode.

[0036] The ASIC chip includes: a divider, whose input terminal inputs the signals collected by the central electrode and the peripheral electrodes of the MEMS chip, and whose output terminal outputs the quotient of the two signal voltages; a first comparator, which compares the quotient with a first preset threshold value. If the quotient is less than the first preset threshold value, it is determined that when the pressure on the MEMS chip is obtained using the signal obtained by the central electrode, there is a non-negligible pyroelectric effect, and the pyroelectric influence should be considered in advance.

[0037] In this embodiment, the quotient is Wherein, V1 and V2 are the voltage values ​​of the signals collected by the central electrode and the peripheral electrode of the MEMS chip, respectively. The first preset threshold α satisfies: 0≤α≤100. Preferably, 0.5≤α≤2.

[0038] The first comparator determines the quotient of the signal voltages collected by the central electrode and the peripheral electrodes. If this quotient is less than a first preset threshold α, it can be determined that the pyroelectric effect is affecting the piezoelectric effect. If the quotient is greater than or equal to the first preset threshold α, it can be determined that the pyroelectric effect can be ignored when processing the piezoelectric signal. This provides a basis for the credibility of subsequent piezoelectric signals and greatly improves the anti-interference capability of the piezoelectric MEMS pressure sensor. The relevant theory will be described in detail below.

[0039] The following describes in detail each component of the piezoelectric MEMS pressure sensor of this embodiment.

[0040] 2A and 2B , the MEMS chip in this embodiment includes:

[0041] The substrate 10 includes: an outer ring body 11; a back cavity 12 formed inside the outer ring body;

[0042] The piezoelectric composite vibration layer 20 includes: a support layer 20a, a lower electrode 20b, a piezoelectric layer 20c, and an upper electrode, which are sequentially formed on the outer ring body and the back cavity;

[0043] The lower electrode is grounded, and the upper electrode is divided into a peripheral electrode 20d and a central electrode 20e. The peripheral electrode 20d and the central electrode 20e are insulated from each other and output electrical signals respectively.

[0044] The working principle of the present invention is described below.

[0045] The phenomenon of a material's spontaneous polarization intensity changing due to temperature changes, thereby generating a polarized electric field within the material, is called pyroelectricity. The primary pyroelectric effect is when the temperature change directly causes a change in polarization intensity, generating a potential difference. The secondary pyroelectric effect is when the temperature change causes material deformation, generating a potential difference through the piezoelectric effect. The total voltage output is the algebraic sum of the output voltages generated by the two pyroelectric effects, as expressed below:

[0046] Among them, P, d 31 , ε are the pyroelectric coefficient, piezoelectric coefficient, and dielectric constant of the piezoelectric material, A and t represent the electrode area and piezoelectric layer thickness, respectively. ΔT and σ are the temperature change and the in-plane thermal stress caused by the temperature change. Because the area and thickness of the piezoelectric MEMS pressure sensor are very small and the thermal conductivity of the material is very high, the temperature difference from the center to the edge of the piezoelectric layer is less than 1°C, and the temperature change is always approximately uniform. From the expression, it can be seen that the first-stage pyroelectric output voltage is independent of the electrode area. When heated uniformly, for a composite vibration layer with consistent radial bending stiffness, the thermal stress in the piezoelectric layer is also uniformly distributed, and the second-stage pyroelectric output voltage is also independent of the area.

[0047] Based on the above discussion, it can be seen that since the piezoelectric composite vibration layer is heated uniformly and the bending stiffness is continuous, the pyroelectric output voltage ratio of the central electrode to the outer ring electrode is Where V1 represents the output voltage of the center electrode, V2 represents the output voltage of the outer ring electrode, and the subscript ΔT represents the effect of temperature change. Taking into account process errors, the pyroelectric output voltage ratio will fluctuate to a certain extent compared to the above theoretical value.

[0048] Here, a first preset threshold α can be set. When the quotient of the voltages of the signals collected by the central electrode and the peripheral electrodes is less than the first preset threshold α, the pyroelectric effect in the MEMS chip is judged to be strong, affecting normal pressure sensing. When the quotient of the voltages of the signals collected by the central electrode and the peripheral electrodes is greater than or equal to the first preset threshold α, the pyroelectric effect is judged to be weak, and its impact on normal pressure sensing can be ignored.

[0049] Figure 3 is a simplified model of the piezoelectric composite vibration layer structure and a schematic diagram of the normalized stress distribution on the mid-surface of the piezoelectric layer. r (r) and tangential stress σ θ (r) is expressed as:

[0050] Where E is Young's modulus, v is Poisson's ratio, R is the back cavity radius, r is the radial coordinate, p is the uniform pressure, D is the bending stiffness of the composite vibration layer, z p is the distance between the mid-plane of the piezoelectric layer and the neutral plane. The neutral plane is defined as the surface where stress and strain are zero when the composite vibration layer is bent and deformed by a uniformly distributed force. Based on the above equation, the normalized stress distribution curve on the mid-plane of the piezoelectric layer is plotted. It can be seen that the total stress on the mid-plane of the piezoelectric layer follows a parabolic distribution, with stresses of opposite signs in the center and at the edges, and the maximum stress occurs at the center and edges of the composite vibration layer.

[0051] The sensitivity expression of the device is Thanks to the unique structural design of the MEMS piezoelectric chip, we have obtained a variety of pyroelectric output voltage ratios between the center electrode and the outer ring electrode. Voltage sensitivity ratio of the central electrode to the outer ring electrode Special MEMS piezoelectric chip.

[0052] The following is a schematic diagram of four types of top electrode distributions, combined with the stress distribution curve shown in Figure 3. Figures 4A to 4D are schematic diagrams of the outer ring electrode and the middle electrode of four typical MEMS chip electrodes in the present invention. In Figures 4A to 4D, the dotted line a represents the back cavity with a radius of R, and the dotted line b represents the stress change position in the piezoelectric layer with a radius of

[0053] (1) In Figure 4A, the outer diameter of the outer ring electrode is smaller than R, and the inner diameter of the outer ring electrode is equal to The center electrode radius is less than And the minimum distance from the inner diameter of the outer ring electrode is 1um.

[0054] (2) In Figure 4B, the outer diameter of the outer ring electrode is smaller than R and larger than The inner diameter of the outer ring electrode is smaller than The radius of the central electrode is smaller than the inner diameter of the outer ring electrode and the minimum distance between the central electrode and the inner diameter of the outer ring electrode is 1 μm.

[0055] (3) In Figure 4C, the outer diameter of the outer ring electrode is smaller than The radius of the central electrode is smaller than the inner diameter of the outer ring electrode and the minimum distance between the central electrode and the inner diameter of the outer ring electrode is 1 μm.

[0056] (4) In Figure 4D, the outer diameter of the outer ring electrode is larger than R, and the inner diameter is smaller than R and larger than The center electrode radius is less than

[0057] Through the above four designs of upper electrodes, the voltage sensitivity ratio of the central electrode to the outer ring electrode can be achieved. Adjustment, easy to achieve Where V1 represents the output voltage of the central electrode, V2 represents the output voltage of the outer ring electrode, and the subscript p represents the pressure effect.

[0058] Furthermore, repeated testing and data analysis have shown that in MEMS chips, in special scenarios such as abnormal e-cigarette charging and atomization output, the output levels of both the center and edge electrodes caused by sudden temperature changes are in the hundreds of millivolts. At room temperature, under a negative pressure of 100 Pa, the output level of the center electrode is generally 10mV, and that of the edge electrodes is generally 0.1-1mV.

[0059] Combining the above discussion on pyroelectricity and piezoelectricity, in the design of MEME chip, the device startup threshold α is set to: in Represents the ratio of the pyroelectric output voltage due to temperature change, are the lower and upper limits of the output voltage ratio during device operation. When the output signal When the electronic cigarette does not work. When the electronic cigarette is turned on, it will start working. This design can effectively avoid the problem of false start caused by the pyroelectric effect. Preferably, the first preset threshold α satisfies: 0.5≤α≤2.

[0060] Figure 5 is a cross-sectional schematic diagram of another MEMS chip according to the present invention. As shown in Figure 5, in this MEMS chip, the lower electrodes are all grounded, and the piezoelectric layer and upper electrode are divided into a center and an outer ring. The outer side of the outer ring piezoelectric layer is aligned with the outer edge of the substrate, and the inner side is aligned with the edge of the back cavity. The outer diameter of the outer ring electrode is larger than the back cavity radius R, and the inner diameter is the same as the back cavity radius R. The center electrode and the center piezoelectric layer have the same radius and are smaller than the back cavity radius R.

[0061] For this MEMS chip, the sensitivity ratio of the central electrode to the outer ring electrode is The ratio of the pyroelectric output voltage of the central electrode and the outer ring electrode is is a finite value. The central piezoelectric layer radius is smaller than the back cavity radius R, which helps release the degree of freedom of the central piezoelectric layer to reduce the bending stiffness, increases the bending deformation amplitude of the piezoelectric composite vibration layer, and all stresses on the piezoelectric layer's mid-surface have the same sign. Compared to the fully covered piezoelectric layer structure shown in Figures 2A and 2B, the MEMS chip structure shown in Figure 5 can increase the area of ​​the central electrode, reduce output impedance, increase output charge, and facilitate further device miniaturization.

[0062] Regarding MEMS chips, the following aspects need to be explained.

[0063] 1. No support layer is required

[0064] In this embodiment, a support layer is provided, and the lower electrode, the piezoelectric layer, and the upper electrode are all formed on the support layer, but the present invention is not limited thereto.

[0065] In other embodiments of the present invention, the support layer may not exist, and the piezoelectric layer itself may be directly used as the support layer. In this case, the lower electrode is formed above the back cavity, and the present invention can also be implemented below the piezoelectric layer, and it is also within the protection scope of the present invention.

[0066] 2. Shape of the center electrode

[0067] In this embodiment, the central electrode is circular, but the present invention is not limited thereto.

[0068] In other embodiments of the present invention, the central electrode can also have other solid shapes, such as square, oval, or ring. The basic principles are similar to those of this embodiment and can also implement the present invention. On this basis, electrodes of arbitrary shapes can be divided on the same piezoelectric composite vibration layer, and the activation of the electronic cigarette can be controlled by determining the ratio of the output voltages of the two electrodes. Therefore, any structure that meets the above principles is within the scope of protection of the present invention.

[0069] 3. Shape of peripheral electrodes

[0070] In this embodiment, the peripheral electrode is located outside the central electrode and is ring-shaped, and is an outer ring electrode, but the present invention is not limited thereto.

[0071] In other embodiments of the present invention, the peripheral electrode may also be in an incomplete ring shape or an irregular ring shape. The peripheral electrode in the present invention refers to an electrode that is not in the center position. As long as the upper electrode is divided into two parts, one part is located in the center area and the other part is in the peripheral area, the present invention can be implemented and is also within the scope of protection of the present invention.

[0072] 4. Position of the central electrode and peripheral electrodes on the horizontal plane

[0073] In this embodiment, the central electrode and the peripheral electrodes are located on the same horizontal plane and are formed by etching the same electrode layer, but the present invention is not limited thereto.

[0074] In other embodiments of the present invention, the central electrode and the peripheral electrode may not be on the same horizontal plane. Typically, the longitudinal section of the piezoelectric layer is trapezoidal, the peripheral electrode is located at the lower step, and the central electrode is formed on the upper plane. The present invention can also be implemented and is also within the scope of protection of the present invention.

[0075] 5. About the lower electrode

[0076] In this embodiment, the voltage of the signal collected by the lower electrode is used as the reference voltage of the signals collected by the central electrode and the peripheral electrodes, but the present invention is not limited thereto.

[0077] In other embodiments of the present invention, other methods may be used to provide a reference voltage, such as using the ground voltage of the ASIC itself, which can also implement the present invention and is also within the scope of protection of the present invention.

[0078] 1 , the ASIC chip of the present invention includes a pre-amplifier, a comparator, a multiplier, a divider, analog processing circuits such as a periodic reset, and related digital output circuits.

[0079] In this embodiment, the pre-operational amplifier has its input end connected to the central electrode and outer ring electrode of the MEMS chip, and its output end connected to the divider, multiplier, and third comparator, and is used to amplify, regularize, and perform other operations on the voltage signals collected by the central electrode and outer ring electrode, and deliver them to the divider, multiplier, and third comparator.

[0080] 1. Division comparison circuit

[0081] The division comparison circuit includes a divider and a first comparator.

[0082] Figure 6 is a schematic diagram of the structure of the divider in the ASIC chip of the piezoelectric MEMS pressure sensor shown in Figure 1. As shown in Figure 6, the first logarithmic circuit takes the logarithm of the center electrode output voltage V1 to obtain lnV1, and the second logarithmic circuit takes the logarithm of the outer ring electrode output voltage V2 to obtain lnV2. The differential proportional operation circuit takes the difference between lnV1 and lnV2. Finally, the exponential circuit performs exponential reduction on the output of the differential proportional operation circuit (lnV1-lnV2) to obtain the division result.

[0083] In the first comparator, when If the value is less than the first preset threshold, it is judged that the pyroelectric effect affects the piezoelectric effect, and the output is "0", that is, the logic is false; otherwise, the output is "1", that is, the logic is true. Among them, the first preset threshold α satisfies: 0.5≤α≤2. In this embodiment, α=1.5. Specifically,

[0084] (1) Once the division comparison circuit detects When the airflow sensor cuts off the output, it will recognize that the current temperature change (the device is in the process of atomizer dry burning, short circuit or high current charging) is far greater than the influence of suction. In this case, the electronic cigarette should not be started.

[0085] (2) When When , it can be seen that the impact of temperature changes is smaller than that of suction, and the airflow sensor is considered to be in normal working condition. At this time, the division comparison circuit outputs "1", and judgment condition ① is obtained. In this case, whether to start the e-cigarette can be determined based on whether other conditions are met.

[0086] 2. Multiplication comparison circuit

[0087] The multiplication comparison circuit includes: a multiplier, whose two input ends respectively input the voltage signals collected by the central electrode and the outer ring electrode of the MEMS chip, and whose output end outputs the product of the signal strengths of the two; a second comparator, which compares the size of the product with a second preset threshold; for the second comparator, when the product is greater than the second preset threshold, it is judged that it exceeds the preset pressure range and outputs "0"; otherwise, it outputs "1".

[0088] In this embodiment, the ASIC includes a multiplication and comparison circuit. Within the logic of the multiplication and comparison circuit, the center electrode and the outer ring electrode are multiplied by V1 × V2. When V1 × V2 exceeds a certain threshold (users can set the threshold based on the actual application scenario), the circuit design can lock the temperature rise rate MAX or the maximum suction force MAX for the user. When this threshold is exceeded, the airflow sensor will automatically cut off its output, providing a safety protection. When V1 × V2 is less than the set threshold (which can be adjusted based on the user's actual application plan), the device is in normal operation, the multiplication circuit output is "1", and judgment condition ② is obtained.

[0089] 3. Third Comparison

[0090] The ASIC chip further includes: a third comparator, whose input terminal receives a voltage signal collected by the central electrode of the MEMS chip and compares the voltage signal with a third preset threshold value; when the voltage signal collected by the central electrode of the MEMS chip is greater than the preset threshold value, the third comparator determines that stress and strain in the piezoelectric layer exist and outputs "1"; otherwise, the third comparator outputs "0";

[0091] In this embodiment, due to the voltage sensitivity ratio of the central electrode to the outer ring electrode It is impossible to accurately identify the size of the air pressure acting on the composite piezoelectric vibration layer. Therefore, the ASIC chip of the present invention is further provided with a set of comparators, and the built-in threshold value of the comparator is equal to the V of the air pressure acting on the center electrode of -100Pa. -100Pa When V1 is less than V -100Pa When V1 is greater than or equal to V -100Pa When , it can be seen that the current negative pressure force is greater than -100Pa, the user is in a normal smoking state, the comparator circuit outputs "1", and the judgment condition ③ is obtained.

[0092] 4. AND Gate

[0093] The ASIC chip further includes: a total logic circuit, whose input end is connected to the output ends of the first comparator, the second comparator and the third comparator, and is used to judge the state of the MEMS chip according to the outputs of the three comparators.

[0094] In this embodiment, the overall logic circuit includes: an AND gate, which outputs "1" when the outputs of the first comparator, the second comparator, and the third comparator are all "1"; otherwise, it outputs "0".

[0095] In this embodiment, the ASIC chip finally outputs "1" only when the overall logic circuit determines that conditions ①, ②, and ③ are all true; otherwise, it outputs "0".

[0096] Furthermore, the ASIC chip of this embodiment features a periodic reset design. Specifically, the overall logic circuit is configured to periodically send a "reset" command to the MEMS chip when the AND gate outputs "0"; and to suspend sending "reset" commands when the AND gate outputs "1." This periodic reset design effectively eliminates any extraneous superposition states in the MEMS chip, allowing the chip to operate stably and long-term in its initial trigger state.

[0097] In this embodiment, based on cost considerations, hardware circuits are used to implement the relevant logical operations, but the present invention is not limited thereto. In other embodiments of the present invention, digital circuits or single-chip microcomputer circuits can be used to implement the relevant logical operations, and all of these can implement the present invention and are also within the scope of protection of the present invention.

[0098] As can be seen from the above description, the present invention divides the upper electrode layer into two parts, a middle part and an outer ring. The lower electrode is grounded, and the center electrode and outer ring electrodes respectively output electrical signals. The activation of the electronic cigarette is controlled by the ratio of the electrical signals output by the center electrode and the outer ring electrodes. This can effectively distinguish the output voltage caused by pressure and the output voltage caused by temperature changes, effectively avoiding the problem of false activation of the electronic cigarette due to sudden temperature changes.

[0099] Regarding ASIC chips, the following aspects need to be explained:

[0100] 1. The multiplication comparison circuit can be omitted

[0101] In this embodiment, a multiplication comparison circuit is used to provide a safety protection function, but this is only a preferred embodiment of the present invention. In other embodiments of the present invention, the multiplication comparison circuit can be omitted and the present invention can still be implemented and is also within the scope of protection of the present invention.

[0102] 2. The pre-operational amplifier can be omitted

[0103] In this embodiment, the signals generated by the central electrode and the outer ring electrodes are amplified and conditioned by a pre-operational amplifier, which facilitates subsequent signal processing by the division comparison circuit, the multiplication comparison circuit, and the third comparison unit. However, this is only a preferred embodiment of the present invention. In other embodiments of the present invention, the multiplication comparison circuit can be omitted and the present invention can still be implemented, which is also within the scope of protection of the present invention.

[0104] 3. Specific form of divider

[0105] The specific structure of the divider is given in this embodiment, but it is only a preferred embodiment of the present invention. In other embodiments of the present invention, those skilled in the art can also use other analog circuits or digital circuits that can implement division operations to implement the present invention.

[0106] 4. Analog circuits can be replaced by digital circuits

[0107] In this embodiment, analog circuits are used to implement related division and multiplication operations, but in other embodiments of the present invention, digital circuits can also be used to implement related operations, which can also implement the present invention and is also within the scope of protection of the present invention.

[0108] 5. Basis for the Third Comparative Section

[0109] In this embodiment, the input terminal of the third comparator directly inputs the voltage signal collected by the central electrode of the MEMS chip and compares it with the third preset threshold, but the present invention is not limited thereto.

[0110] In other embodiments of the present invention, the third comparator can also compare the voltage difference of the signals collected by the central electrode and the outer ring electrode of the MEMS chip with the third preset threshold, which can also implement the present invention and is also within the protection scope of the present invention.

[0111] 6. Scope of application of this embodiment

[0112] In this embodiment, a piezoelectric MEMS pressure sensor used in an electronic cigarette determines the presence of a non-negligible pyroelectric effect when the voltage quotient of the signals collected by the central electrode and the peripheral electrodes is less than a first preset threshold, thereby disabling the electronic cigarette. However, this is not an example of the present invention.

[0113] In the application scope of piezoelectric MEMS pressure sensors, in many scenarios, it is necessary to determine whether there is a non-negligible pyroelectric effect. When the first comparator determines that there is a non-negligible pyroelectric effect, or that the existing pyroelectric effect can be ignored in subsequent processing, the overall logic unit can perform the corresponding operation. These operations are determined according to the actual scenario and are well known to those skilled in the art, so they will not be described here. The above scenarios can all be applied to the present invention and should also be within the scope of protection of the present invention.

[0114] This concludes the introduction to the first embodiment of the piezoelectric MEMS pressure sensor of the present invention.

[0115] Figure 7 is a circuit diagram of the second embodiment of the piezoelectric MEMS pressure sensor according to the present invention. This embodiment differs from the first in that it uses a difference method to extract the effective signal, resulting in a different ASIC chip structure and operating principle. Regarding the MEMS chip, this embodiment is identical to the first embodiment, and the relevant details of the first embodiment are incorporated into this embodiment and will not be repeated here.

[0116] As shown in Figure 7, in this embodiment, the piezoelectric structure corresponding to the central electrode is equivalent to a parallel combination of capacitor Cp1, resistor Rp1, and charge source Q1. The piezoelectric structure corresponding to the peripheral electrodes is equivalent to a parallel combination of capacitor Cp2, resistor Rp2, and charge source Q2.

[0117] The ASIC chip includes: a differential amplifier module, whose two input terminals respectively input the signals collected by the central electrode and peripheral electrodes of the MEMS chip, and whose output terminal outputs the difference between the two signal voltages; an Ath comparator, which compares the difference with the Ath comparison threshold β, 50mV<β≤500mV; a logic control module, whose input terminal is connected to the output terminal of the Ath comparator, and is used to: ① output "1" when the difference is greater than or equal to the Ath comparison threshold β; ② output "0" when the difference is less than the Ath comparison threshold β.

[0118] In order to prevent the output of the Ath comparator from being disturbed by noise (5-10 mV), the Ath comparison threshold β is selected to be: 50 mV < β ≤ 500 mV. Preferably, 100 mV < β ≤ 200 mV.

[0119] Similarly, in this embodiment, the ASIC chip has a periodic reset design, wherein the logic control module is further used to: when the difference is less than the Ath comparator threshold β, control the MEMS chip to perform a predetermined periodic reset according to the periodic setting.

[0120] In this embodiment, the differential amplifier module performs a differential operation on the voltage signal V1 obtained by the center electrode and the voltage signal V2 obtained by the edge electrode, and outputs a difference signal (V1-V2). The (V1-V2) is divided into two parts: (V1-V2) = (V1-V2) p +(V1-V2) ΔT

[0121] Among them, (V1-V2) p It is the voltage difference caused by the piezoelectric effect due to the change in external pressure. (V1-V2) ΔT It is the voltage difference caused by the pyroelectric effect due to temperature changes.

[0122] Figure 8 is a schematic diagram of the ASIC chip signal processing in the piezoelectric MEMS pressure sensor shown in Figure 7. (A) shows the negative pressure sensitivity and pyroelectric voltage of the MEMS chip's central and peripheral electrodes, respectively; (B) shows the analog signal output by the differential amplifier module in the ASIC chip; and (C) shows the digital signal output by the logic control module in the ASIC chip. As shown in Figures 7 and 8, for the difference signal (V1-V2):

[0123] 1. Negative pressure sensitivity

[0124] For the first part (V1-V2) p , because the peripheral electrodes in the MEMS chip are fixed. Therefore, the external pressure change does not generate voltage on the peripheral electrodes, so V 2p ≈0, as shown by the blue line in Figure 8(A); the pressure change generates a large voltage on the central electrode, as shown by the green line in Figure 8(A). The negative pressure sensitivity is expressed as follows: (V1-V2) p =V 1p -V 2p ≈V 1p -0=V 1p

[0125] 2. Voltage difference caused by pyroelectricity

[0126] For the second part (V1-V2) ΔT , when the area of ​​the peripheral electrode and the central electrode is the same, the output voltage of the central electrode and the peripheral electrode due to the pyroelectric effect of the central electrode and the outer ring electrode satisfies: V 1ΔT =V 2ΔT , which are shown as the red and yellow lines in Figure 8 (A) respectively. The voltage difference caused by pyroelectricity is: (V1-V2) ΔT =V 1ΔT -V 2ΔT =0

[0127] 3. Superposition of negative pressure sensitivity and pyroelectric effect

[0128] When MEMS is working, when pyroelectricity and sensitivity are superimposed, the difference between the two electrodes is approximately: (V1-V2) = (V1-V2) p +(V1-V2) ΔT ≈V 1p -0=V 1p

[0129] The analog signal output by the differential amplifier module in FIG7 is shown in FIG8B , and the digital signal output by the logic control module is shown in FIG8C .

[0130] The advantages of using the difference method in this embodiment are:

[0131] 1. Improve measurement accuracy

[0132] Differential processing of MEMS chip signals can offset common mode errors, such as those caused by temperature variations and power supply fluctuations. In piezoelectric sensors, these errors can cause output signal drift or instability, affecting measurement accuracy. The use of differential circuits can effectively reduce these errors, improving measurement accuracy and stability.

[0133] 2. Enhanced anti-interference

[0134] Piezoelectric sensors may be subject to various external interferences during operation, such as electromagnetic interference and mechanical vibration. These interferences can increase noise in the sensor's output signal, affecting signal reliability and accuracy. Differential processing can suppress these interfering signals as common-mode signals, thereby enhancing interference resistance and improving the signal-to-noise ratio.

[0135] 3. Simplify signal processing circuit to achieve low cost

[0136] The signal processing circuitry of a piezoelectric sensor typically requires signal amplification, filtering, and linearization. The application of differential circuits can simplify the design of these processing circuits. For example, differential amplifier circuits can directly amplify differential signals without worrying about interference from common-mode signals. Furthermore, differential circuits can be used to linearize signals, improving sensor linearity.

[0137] However, this embodiment has a defect, that is, it requires (V1-V2) p >>(V1-V2) ΔT Otherwise, it is still susceptible to the pyroelectric effect caused by temperature effect, such as V 1p =10mV, V 2p =0mV, V 1ΔT =200mV, V 2ΔT =190mV, then (V1-V2) p =10mV>>(V1-V2) ΔT =10mV does not hold true. In this case, the influence of the pyroelectric effect caused by the temperature effect cannot be ignored. The quotient rule of the first embodiment can eliminate the pyroelectric effect caused by the temperature effect to the greatest extent.

[0138] Based on the above-mentioned piezoelectric MEMS pressure sensor, the second aspect of the present invention provides an electronic cigarette.

[0139] The first embodiment of the electronic cigarette of the present invention comprises: an electronic cigarette body, an atomizer disposed therein; a controller disposed within the electronic cigarette body; and a piezoelectric MEMS pressure sensor, as described above, encapsulated within the electronic cigarette body and connected to the controller. After the piezoelectric MEMS pressure sensor senses a user's inhalation signal, the controller controls a drive circuit to activate the atomizer. The controller, which can be a single-chip microcomputer or other logic chip, performs the following operation: when an AND gate outputs "1," the controller controls the drive circuit to activate the atomizer, thereby simulating the user's puffing experience. For details regarding the piezoelectric MEMS pressure sensor, please refer to the relevant description of the previous embodiment. For details regarding the atomizer, please refer to the relevant description of the prior art and will not be repeated here.

[0140] The second embodiment of the electronic cigarette of the present invention is similar to the first embodiment, except that it uses a piezoelectric MEMS pressure sensor. The relevant content of the first embodiment of the electronic cigarette is incorporated into this embodiment for reference and will not be repeated here.

[0141] Those skilled in the art should understand that although the above example uses electronic cigarettes, the piezoelectric MEMS pressure sensor of the present invention can also be applied to other pressure sensors, microphones, or other actuators, and can effectively identify false start-ups caused by the pyroelectric effect. The details will not be repeated here.

[0142] Thus, the various embodiments of the present invention have been introduced. According to the above description, those skilled in the art should have a clear understanding of the present invention.

[0143] It should be noted that the directional terms mentioned in the embodiments, such as "center," "transverse," "longitudinal," "top," "bottom," "up," "down," "front," "back," "left," "right," "inside," "outside," etc., indicate positions or positional relationships based solely on the positions or positional relationships shown in the accompanying drawings. They are intended solely to facilitate the description of the present invention and to simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the shapes and sizes of the components in the drawings do not reflect actual size or proportion, but merely illustrate the contents of the embodiments of the present invention.

[0144] It should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms based on specific circumstances.

[0145] The ordinal numbers used in the specification and claims, such as "first", "second", "third", "primary", "secondary", as well as Arabic numerals, letters, etc., to modify the corresponding elements are intended only to clearly distinguish an element with a certain name from another element with the same name, and do not mean that the element (or step) has any ordinal number, nor do they represent the order of one element and another element.

[0146] The present invention can be implemented using hardware comprising several distinct elements and using a suitably programmed computer. The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Physical implementations of the hardware architecture include, but are not limited to, physical devices, including, but not limited to, transistors, memristors, DNA computers, single-chip microcomputers, microprocessors, or digital signal processors (DSPs).

[0147] The present invention may also be implemented as an apparatus or device program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such a program implementing the present invention may be stored on a computer-readable medium or may be in the form of one or more signals. Such signals may be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0148] Those skilled in the art will appreciate that, in the claims and description of the present invention, the word "comprising" does not exclude the presence of elements not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0149] Similarly, it should be understood that in order to streamline the present invention, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the invention should not be interpreted as reflecting the intention that the claimed invention requires more features than those explicitly stated in each claim. More precisely, as reflected in the claims, each inventive aspect consists in less than all the features of the preceding single embodiment. Moreover, the embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments. Therefore, the claims following the specific embodiment are hereby expressly incorporated into the specific embodiment, with each claim itself serving as a separate embodiment of the present invention.

[0150] The above specific embodiments provide a detailed description of the objectives, technical means and beneficial effects of the present invention. It should be understood that the purpose of the detailed description is to enable those skilled in the art to understand the present invention more clearly, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A piezoelectric MEMS pressure sensor, characterized in that, Comprising: A MEMS chip, comprising: a piezoelectric layer; a central electrode formed on the piezoelectric layer and disposed near the center of the MEMS chip; a peripheral electrode formed on the piezoelectric layer, disposed outside the central electrode, and the peripheral electrode is insulated from the central electrode; An ASIC chip, whose two input terminals respectively input signals collected by the central electrode and the peripheral electrode of the MEMS chip, and is used to judge the state of the MEMS chip by using the two signals.

2. The piezoelectric MEMS pressure sensor according to claim 1, wherein The ASIC chip includes: A divider, whose input terminal inputs the signals collected by the central electrode and the peripheral electrode of the MEMS chip, and its output terminal outputs the quotient of the voltages of the two signals; A first comparator, which compares the size of the quotient with a first preset threshold α, where 0 < α ≤ 100.

3. The piezoelectric MEMS pressure sensor according to claim 2, wherein The first preset threshold α satisfies: 0.5 ≤ α ≤ 2; and / or, the quotient is wherein, V1 and V2 are respectively the voltage values of the signals collected by the central electrode and the peripheral electrode of the MEMS chip; And / or, the divider includes: a first logarithmic circuit, a second logarithmic circuit, a differential proportional operation circuit, and an exponential circuit, where: the first logarithmic circuit takes the logarithm of the output voltage V1 of the central electrode to obtain lnV1; the second logarithmic circuit takes the logarithm of the output voltage V2 of the outer ring electrode to obtain lnV2; the differential proportional operation circuit takes the difference between lnV1 output by the first logarithmic circuit and lnV2 output by the second logarithmic circuit to obtain: (lnV1 - lnV2); the exponential circuit performs exponential reduction on (lnV1 - lnV2) output by the differential proportional operation circuit to obtain the division result and / or, in the first comparator, if the quotient is less than the first preset threshold, it is judged that the pyroelectric effect should be considered before calculating the pressure received by the MEMS chip by using the signal obtained by the central electrode.

4. The piezoelectric MEMS pressure sensor according to claim 2, wherein The ASIC chip further includes: a third comparator, whose input terminal inputs the signal collected by the central electrode of the MEMS chip and compares the voltage of this signal with a third preset threshold; The ASIC chip further includes: a total logic circuit, whose input terminal is connected to the output terminals of the first comparator and the third comparator, and is used to judge the state of the MEMS chip according to their outputs.

5. The piezoelectric MEMS pressure sensor according to claim 4, wherein The ASIC chip further includes: a multiplier, whose input terminal inputs the signals collected by the central electrode and the peripheral electrode of the MEMS chip, and its output terminal outputs the product of the voltages of the two signals; a second comparator, which compares the size of the product with a second preset threshold; The total logic circuit, whose input terminal is connected to the output terminals of the first comparator, the second comparator, and the third comparator, and is used to judge the state of the MEMS chip according to their outputs.

6. The piezoelectric MEMS pressure sensor according to claim 5, characterized in that ； For the first comparator, when the quotient is less than the first preset threshold, output "0"; otherwise, output "1"; For the second comparator, when the product is greater than the second preset threshold, output "0"; otherwise, output "1"; For the third comparator, when the voltage of the signal collected by the central electrode of the MEMS chip is greater than the third preset threshold, output "1"; otherwise, output "0"; The total logic circuit includes: an AND gate, which outputs "1" when the outputs of the first comparator, the second comparator, and the third comparator are all "1"; otherwise, output "0".

7. The piezoelectric MEMS pressure sensor according to claim 6, characterized in that, The ASIC chip further includes: A preamplifier, whose input terminal is connected to the central electrode and the peripheral electrode of the MEMS chip, and whose output terminal is connected to the divider, multiplier, and third comparator, is used to amplify the signals collected by the central electrode and the peripheral electrode respectively and deliver them to the divider, multiplier, and third comparator.

8. The piezoelectric MEMS pressure sensor according to claim 7, wherein, The total logic circuit is further configured to: When the AND gate outputs "0", send a "reset" instruction to the MEMS chip according to the periodic setting; When the AND gate outputs "1", pause sending the "reset" instruction.

9. The piezoelectric MEMS pressure sensor according to claim 1, wherein The ASIC chip includes: A differential amplifier module, whose two input terminals respectively input the signals collected by the central electrode and the peripheral electrode of the MEMS chip, and whose output terminal outputs the difference between the two signal voltages; A comparator A, which compares the magnitude of the difference with a comparator A threshold β, where 50 mV < β ≤ 500 mV; A logic control module, whose input terminal is connected to the output terminal of the comparator A, and is used to: ① output "1" when the difference is greater than or equal to the comparator A threshold β; ② output "0" when the difference is less than the comparator A threshold β.

10. The piezoelectric MEMS pressure sensor according to claim 9, wherein The logic control module is further configured to: When the difference is less than the comparator A threshold β, control the MEMS chip to be reset according to the periodic setting.

11. The piezoelectric MEMS pressure sensor according to claim 1, wherein In the horizontal direction, the central electrode is in a solid shape or a ring shape; And / or, for the central electrode and the peripheral electrode, the two are in the same horizontal plane or different horizontal planes; And / or, the MEMS chip further includes: a lower electrode, disposed below the piezoelectric layer, which is electrically grounded, and whose voltage serves as a reference voltage for the signals collected by the central electrode and the peripheral electrode.

12. The piezoelectric MEMS pressure sensor according to claim 11, wherein In the horizontal direction, the central electrode is circular; the peripheral electrode is in a circular ring shape and is an outer ring electrode; The central electrode and the peripheral electrode are in the same horizontal plane and have equal areas.

13. The piezoelectric MEMS pressure sensor according to claim 12, wherein The cross-section of the back cavity is circular, and its radius is R; The outer diameter of the outer ring electrode is less than R, and the inner diameter is The radius of the central electrode is less than And the minimum distance from the inner diameter of the outer ring electrode is U, where 0.5 μm ≤ U ≤ 5 μm; Or, the outer diameter of the outer ring electrode is less than R and greater than The inner diameter of the outer ring electrode is less than The radius of the central electrode is less than the inner diameter of the outer ring electrode and the minimum distance from the inner diameter of the outer ring electrode is U, where 0.5 μm ≤ U ≤ 5 μm; Or, the outer diameter of the outer ring electrode is less than The radius of the central electrode is less than the inner diameter of the outer ring electrode and the minimum distance from the inner diameter of the outer ring electrode is U, where 0.5 μm ≤ U ≤ 5 μm; Or, the outer diameter of the outer ring electrode is greater than R, and the inner diameter is less than R and greater than The radius of the central electrode is less than 14. The piezoelectric MEMS pressure sensor according to claim 12, wherein The MEMS chip includes: A substrate, including: an outer ring body at the periphery; a back cavity formed inside the outer ring body; A piezoelectric composite vibration layer, including: a lower electrode, the piezoelectric layer, the central electrode, the outer ring electrode, where: The piezoelectric layer is formed above the outer ring body and the back cavity; The lower electrode is formed below the piezoelectric layer and is connected to the ground; The central electrode is formed on the piezoelectric layer and is disposed close to the center of the piezoelectric layer; The outer ring electrode is formed on the piezoelectric layer, is disposed outside the central electrode, and the outer peripheral electrode is insulated from the central electrode; Wherein, the lower electrode is formed above the back cavity and below the piezoelectric layer; or, the MEMS chip further includes: a support layer formed above the outer ring body and the back cavity; wherein, the lower electrode and the piezoelectric layer are sequentially formed on the support layer.

15. The piezoelectric MEMS pressure sensor according to claim 12, wherein the piezoelectric layer includes: a central piezoelectric layer disposed near the center of the MEMS chip; an outer ring piezoelectric layer disposed around the central piezoelectric layer; the central electrode is formed on the central piezoelectric layer, and the outer ring electrode is formed on the outer ring piezoelectric layer; wherein, the outer side of the outer ring piezoelectric layer is aligned with the outer edge of the substrate, and the inner side is aligned with the edge of the back cavity; the outer diameter of the outer ring electrode is greater than the radius of the back cavity, and the inner diameter is the same as the radius of the back cavity; the radius of the central piezoelectric layer is smaller than the radius of the back cavity; the radius of the central electrode is the same as that of the central piezoelectric layer.

16. An electronic cigarette, characterized in that, Comprising: an e-cigarette body with an atomizer disposed inside; a controller disposed inside the e-cigarette body; the piezoelectric MEMS pressure sensor according to any one of claims 1 to 15, encapsulated inside the e-cigarette body and signal-connected to the controller; wherein, when the piezoelectric MEMS pressure sensor senses a user's suction signal, the controller controls the drive circuit to cause the atomizer to start working.

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