Piezoelectrically biased capacitive universal flexible pressure patch
By using a flexible pressure patch with a piezoelectric bias capacitor structure, the problems of uneven pressure transmission and environmental stability when applying to irregular surfaces are solved, achieving stable output and improved durability in humid environments.
Patent Information
- Application Number
- CN202610747855.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-28
- Publication Date
- 2026-06-23
AI Technical Summary
Existing flexible pressure sensors suffer from uneven pressure transmission when applied to irregular surfaces, are susceptible to humidity and contamination, leading to output errors and decreased sensitivity. Furthermore, the thin film is prone to localized stress concentration and fatigue damage.
It adopts a piezoelectric bias capacitor structure, including a piezoelectric bias module and a pressure-capacitance conversion unit. It provides a stable static bias by generating residual polarization through pre-polarization. Combined with the compressible dielectric structure, the capacitance changes under external pressure, reducing the dependence on external bias circuits and improving environmental stability.
It achieves uniform pressure transmission in humid and long-term contact environments, reduces local stress concentration, improves the stability and durability of the sensor, reduces dependence on external power supply, and is suitable for application on irregular surfaces.
Smart Images
Figure CN122259075A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pressure measurement technology, and in particular to a piezoelectric bias capacitor type universal flexible pressure patch. Background Technology
[0002] Existing flexible pressure sensing technologies include piezoresistive, piezoelectric, capacitive, and ion gel / electrocapacitive types.
[0003] Capacitive sensors have the advantages of good linearity and low noise, but they often rely on external bias voltage or complex circuits. Some self-biasing schemes use electrets, but their surface charge is easily affected by humidity, sweat, pollution, long-term contact and other factors, which can cause zero drift and decreased sensitivity.
[0004] On the other hand, when applied to irregular interfaces such as skin, fabric, rock, concrete, and rough metal surfaces, uneven pressure transmission leads to output errors; at the same time, direct pressure on the film / microstructure can easily cause local stress concentration, fatigue, and damage.
[0005] Therefore, there is a need for a general-purpose flexible pressure patch that can uniformly transmit pressure, reduce local stress concentration, and provide stable bias to reduce external power supply / bias dependence and improve environmental stability. Summary of the Invention
[0006] The purpose of this invention is to overcome the above-mentioned defects of the prior art and propose a piezoelectric bias capacitor type universal flexible pressure patch, which is suitable for application to irregular surfaces, provides more uniform pressure transmission, and can maintain stable output even in humid, sweaty, and long-term contact environments.
[0007] The technical solution of this invention is: a piezoelectric biased capacitor type universal flexible pressure patch, comprising, from top to bottom, the following components arranged sequentially: The bias coupling electrode layer is electrically connected to the piezoelectric bias module. A piezoelectric bias module includes a piezoelectric thin film and electrodes disposed on both sides of the piezoelectric thin film. The electrodes include a bias coupling electrode layer disposed above the piezoelectric thin film and a first electrode layer disposed below the piezoelectric thin film. The electrodes are used to collect, extract, or couple the equivalent bias charge or equivalent bias electric field generated by the piezoelectric bias module. The pressure-capacitance conversion unit includes several electrode layers arranged in a vertical direction and a dielectric layer disposed between two adjacent electrode layers. The dielectric layer includes several spaced micro-protrusions. The uppermost electrode layer in the pressure-capacitance conversion unit is the first electrode layer, which is shared by the piezoelectric bias module and the pressure-capacitance conversion unit.
[0008] In this invention, a first pressure-bearing protective layer is provided above the bias coupling electrode layer; A flexible substrate layer is provided below the pressure-capacitance conversion unit, an adhesive layer is provided on the back of the flexible substrate layer, and a second pressure-resistant protective layer is provided between the pressure-capacitance conversion unit and the flexible substrate layer.
[0009] During manufacturing, the piezoelectric bias module generates residual polarization through pre-polarization, which enables the piezoelectric bias module to provide a stable static bias. When subjected to external pressure, the piezoelectric bias module generates additional charge under dynamic load, which dynamically modulates the output signal, improving the amplitude and signal-to-noise ratio (SNR) of the transient signal.
[0010] The true pressure value is obtained after the output voltage measured by the flexible pressure patch is corrected by the formula. , in, The actual pressure value represents the real physical pressure applied to the flexible pressure patch. It is a pressure inversion function and a pressure-capacitance calibration function. The inverse function is used to calculate the actual pressure value from the compensated and corrected capacitance value. The static bias charge represents the equivalent static bias charge established between the upper and lower electrodes of the capacitor by the residual polarization formed after polarization by the piezoelectric bias module; this parameter is obtained by measuring the reference capacitance under reference pressure conditions. With corresponding output voltage And calculate get; The actual measured output voltage is the output voltage signal that the flexible pressure patch acquires in real time by the readout circuit during operation. Dynamic piezoelectric interference charge represents the transient piezoelectric charge changes generated by the piezoelectric bias module under dynamic stress, vibration, or impact and coupled to the measurement node. The reference capacitance represents the equivalent capacitance value of the pressure-capacitance conversion unit under conditions of no external pressure or known reference pressure. This parameter represents the change in capacitance of the pressure-capacitance conversion unit relative to a reference state under pressure. The instantaneous capacitance value is obtained by initially estimating the measured voltage and comparing it with the reference capacitance. Obtained by doing something else.
[0011] The thickness of the piezoelectric film is 3 μm–80 μm; When the electrode is a metal film electrode, the electrode thickness is 50 nm–500 nm; when the electrode is prepared by screen printing or inkjet printing, the electrode thickness is 1 μm–15 μm.
[0012] The shapes of the micro-protrusions include, but are not limited to, cylindrical, square, pyramidal, and conical shapes.
[0013] The overall thickness of the pressure-capacitance conversion unit is 50 μm–1500 μm; The height of the micro-protrusions ranges from 10 μm to 500 μm, the width or diameter of the bottom of the micro-protrusions ranges from 20 μm to 800 μm, and the spacing between the micro-protrusions ranges from 30 μm to 1200 μm.
[0014] Flexible pressure patches are arranged in an array on the surface of the object being tested. At this point, the piezoelectric bias modules or pressure-capacitance conversion units in each flexible pressure patch are arranged in a continuous, integrated manner, or in separate zones.
[0015] The beneficial effects of this invention are: (1) This application proposes a structural design based on a combination of a compressible dielectric structure and capacitance readout: wherein the compressible dielectric structure deforms under external pressure, causing a change in capacitance value, and signal conversion is achieved through capacitance readout. The structure itself has good linear response characteristics and can maintain stable sensitivity over a wide pressure range. At the same time, the capacitance detection method has the advantages of low noise and low power consumption, and the structure is simple and easy to realize large-scale array integration, meeting the requirements of high spatial resolution and large-area distributed sensing; (2) The flexible pressure patch introduces a piezoelectric bias module: the module can provide a stable equivalent bias charge or bias electric field, so that the capacitance change is converted into output under low power consumption; at the same time, dynamic pressure can generate accessory charge adjustment, improving the transient signal-to-noise ratio; effectively reducing the dependence on traditional external bias circuits, simplifying the design of peripheral systems, and exhibiting stronger stability and reliability in complex environments such as temperature changes and humidity fluctuations. (3) The piezoelectric bias module is set away from the main pressure area: This layout design effectively avoids fatigue damage to the piezoelectric material under long-term cyclic load, ensures the long-term stability of the bias performance, and significantly improves the overall mechanical fatigue life. It is suitable for high reliability and long-term continuous monitoring application scenarios.
[0016] In summary, the flexible pressure patch proposed in this application is suitable for application on irregular surfaces, resulting in more uniform pressure transmission; it can maintain stable output even in humid, sweaty, and long-term contact environments; it reduces dependence on external bias power supplies, lowers power consumption, and improves wearability; and it enhances durability and resistance to impact / local stress concentration, demonstrating good engineering applicability and industrialization prospects. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the layered structure of this application; Figure 2 This is a schematic cross-sectional view of the pressure-capacitor conversion unit when the longitudinal cross-section of the micro-protrusion is square; Figure 3 This is a schematic diagram of the cross-sectional structure of a pressure-capacitor conversion unit when the longitudinal cross-section of the micro-protrusion is triangular.
[0018] In the figure: 1 First pressure-bearing protective layer; 2 Bias coupling electrode layer; 3 Piezoelectric thin film; 4 First electrode layer; 5 Dielectric layer; 501 Micro protrusion; 6 Second electrode layer; 7 Second pressure-bearing protective layer; 8 Flexible substrate layer; 9 Adhesion layer. Detailed Implementation
[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0020] Specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0021] like Figure 1 As shown, the piezoelectric bias capacitor type universal flexible pressure patch proposed in this application adopts a multi-layer stacked structure, which includes, from top to bottom, a pressure protection layer, a piezoelectric bias module, a pressure-capacitance conversion unit, and a flexible substrate layer 8.
[0022] In this embodiment, the top layer of the flexible pressure patch is provided with a first pressure-bearing protective layer 1, and a second pressure-bearing protective layer 7 is provided between the pressure-capacitance conversion unit and the flexible base layer 8. The pressure-bearing protective layer serves to prevent wear, evenly distribute pressure, and isolate external liquids / sweat.
[0023] The pressure-bearing protective layer can be made of PI, TPU, Parylene-C, PET, silicone rubber film, or composite film. The thickness of the pressure-bearing protective layer is 10 μm–300 μm, preferably 30–120 μm. The surface of the pressure-bearing protective layer can be provided with a micro-frosted / anti-slip texture, with a texture depth of 5–50 μm.
[0024] A piezoelectric bias module is disposed on the back side of the first pressure-bearing protective layer 1. The piezoelectric bias module includes a piezoelectric thin film 3 and electrodes for applying a bias voltage, wherein the thickness of the piezoelectric thin film is 3 μm–80 μm, preferably 8–25 μm. The electrodes include a bias coupling electrode layer 2 located above the piezoelectric thin film 3 and a first electrode layer 4 located below the piezoelectric thin film 3, i.e., the piezoelectric thin film 3 is located between the bias coupling electrode layer 2 and the first electrode layer 4. The electrodes are electrically connected to the piezoelectric thin film 3 and are used to collect, extract, or couple the equivalent bias charge or equivalent bias electric field generated by the piezoelectric bias module. The equivalent bias charge or equivalent bias electric field provides initial bias conditions for the pressure-capacitance conversion unit, enabling capacitance changes to be stably read out under conditions of no external bias power supply or low power consumption. The electrodes are used to transfer the equivalent bias charge / bias electric field formed by the pre-polarization of the piezoelectric thin film and to couple additional piezoelectric charges under dynamic pressure.
[0025] The polarization methods of the piezoelectric bias module 3 include, but are not limited to, corona polarization, contact polarization, and thermally assisted polarization. The piezoelectric bias module 3 can be made of PVDF, PVDF-TrFE, or PVDF-based composite thin films.
[0026] The thickness of the electrode varies depending on the preparation method: metal film electrodes prepared by processes such as evaporation / sputtering have a thickness controlled between 50 nm and 300 nm; while electrodes prepared by methods such as screen printing and inkjet printing have a thickness range of 1 μm to 15 μm.
[0027] The piezoelectric thin film 3 proposed in this application can not only cooperate with the electrode to provide a stable equivalent bias charge or bias electric field, so that the capacitance change is converted into output under low power consumption; but also the dynamic pressure acting on the piezoelectric bias module can generate additional charge modulation, thereby improving the transient signal-to-noise ratio.
[0028] The working principle of existing pressure sensor patches is usually as follows: pressure applied to the patch causes dielectric compression, resulting in a capacitance change ΔC. An external circuit reads ΔC and converts it into an electrical signal. This process requires an external bias voltage and is prone to noise.
[0029] The working principle of the piezoelectric bias module proposed in this application is as follows: When pressure is applied to the flexible pressure patch described in this application, dielectric compression is also generated, resulting in a capacitance change ΔC. At this time, the piezoelectric bias module provides built-in bias to achieve low-power output of electrical signals; at the same time, the piezoelectric bias module is subjected to external dynamic pressure, resulting in piezoelectric additional modulation, improving SNR, reducing external dependence, and improving stability.
[0030] During manufacturing, the piezoelectric bias module generates residual polarization through pre-polarization, which is equivalent to having a built-in stable equivalent charge / electric field source. This bias does not rely on amplitude generated by external pressure to form the bias; rather, the bias itself is a stable value provided by pre-polarization—a static bias—allowing the capacitance change ΔC to be directly converted into a voltage output without an external power supply or with low power consumption. When external pressure is applied, the piezoelectric film generates additional charge—dynamic modulation—further improving the amplitude and signal-to-noise ratio (SNR) of the transient signal, making it particularly suitable for dynamic / pulsating pressures such as pulses and vibrations.
[0031] Therefore, the piezoelectric bias module in this application performs two different functions: on the one hand, the stable static bias comes from the residual polarization formed after the piezoelectric thin film 3 is pre-polarized. This residual polarization can provide a relatively constant built-in bias electric field, which is independent of external pressure and provides a reference electric field, so that the capacitance change ΔC is converted into an electrical signal with low power consumption; on the other hand, when the piezoelectric bias module is subjected to external dynamic pressure, its dynamic signal is enhanced. The additional charge generated by the piezoelectric effect when the external pressure changes changes is transient with the pressure change rate, which improves the transient signal amplitude and signal-to-noise ratio.
[0032] In this application, the piezoelectric bias module 3 can also be arranged in a ring along the circumferential edge of the patch. In this case, the piezoelectric bias module does not affect the compression of the dielectric layer in the pressure-capacitance conversion unit.
[0033] In this application, when several flexible pressure patches are arranged in an array, the several flexible pressure patches can share a single piezoelectric bias module 3; or the array can be divided into several regions, each region being configured with a single piezoelectric bias module 3.
[0034] The pressure-capacitance conversion unit includes several electrode layers and a dielectric layer disposed between adjacent electrode layers. In this embodiment, the electrode layers are planar electrodes, and the dielectric layer is compressible.
[0035] When a metal thin-film electrode is used as the electrode layer, its thickness is 50 nm–500 nm, preferably 80–200 nm; when a printed electrode is used, its thickness is 1 μm–30 μm, preferably 3–10 μm. The effective area of the electrode layer is consistent with the measurement area, or it is arranged in zones, ranging from 0.5 cm² to 100 cm². The linewidth and spacing of the electrode layer array traces are 50 μm–1000 μm, preferably 150 μm–400 μm. The electrode layer material can be Au, Cr, Ag, ITO, PEDOT:PSS, carbon / graphene conductive layer, or other conductive fabrics.
[0036] The dielectric layer includes several spaced microbumps 501, which are used for sensitization and linear range modulation. The dielectric layer can be made of PDMS, Ecoflex, PU, silicone gel, or composite materials thereof. Under external pressure, the thickness of the dielectric layer decreases, and the contact area between the microbumps increases, thereby changing the effective dielectric environment and consequently changing the capacitance ΔC.
[0037] In this embodiment, the pressure-capacitance conversion unit includes a first electrode layer 4 and a second electrode layer 6 arranged from top to bottom, and a dielectric layer 5 located between the first electrode layer and the second electrode layer. Therefore, in this application, the piezoelectric bias module and the pressure-capacitance conversion unit share the first electrode layer 4, but the first electrode layer 4 plays a different role in the piezoelectric bias module and the pressure-capacitance conversion unit.
[0038] When several flexible pressure patches are arranged in an array, the electrode layer and dielectric layer in the flexible pressure patches can be arranged as a whole continuously or in sections.
[0039] The micro-protrusion 501 can be cylindrical or cubic in shape, in which case the longitudinal cross-section of the micro-protrusion is square, such as... Figure 2 As shown; the shape of the micro-protrusion 501 can also be pyramidal or conical, in which case the longitudinal cross-section of the micro-protrusion is triangular, such as... Figure 3 As shown.
[0040] In this embodiment, the overall thickness, including the dielectric layer and the electrode layer, is 50 μm–1500 μm, preferably 150–600 μm; the height of the micro-protrusions is 10 μm–500 μm, preferably 30–200 μm; the width or diameter of the bottom of the micro-protrusions is 20 μm–800 μm, preferably 80–300 μm; and the spacing between the micro-protrusions is 30 μm–1200 μm, preferably 150–500 μm.
[0041] In this application, the shape of the dielectric layer, including parameters such as the height, spacing, and porosity of the micro-bumps, and the elastic modulus of the dielectric layer, can be precisely controlled.
[0042] (1) Range: Increasing the dielectric layer thickness or increasing the spacing between the micro-protrusions essentially expands the compression volume of the structure, enabling the flexible pressure patch to cover a wide range of stresses from low pressure to medium and high pressure.
[0043] (2) Sensitivity: By selecting a low elastic modulus material and combining it with a pyramid-shaped micro-protrusion structure with local stress concentration, a local stress concentration effect can be formed at the contact interface, thereby inducing significant dielectric layer deformation Δd and dielectric constant change Δεr under small pressure, achieving a high sensitivity response to weak pressure.
[0044] The combination of the pressure-capacitance conversion unit and the piezoelectric bias module proposed in this application results in lower power consumption, higher stability, and greater resistance to humidity / sweat attenuation and zero drift in the entire flexible pressure patch.
[0045] The flexible substrate layer 8 is used to support electrode traces, improve structural integrity and bendability, and has a thickness of 10 μm–300 μm, preferably 25–120 μm. It can be made of materials such as PI, PET, Parylene, TPU, and fabric composite substrates.
[0046] An adhesive layer 9 is provided on the back of the flexible base layer 8, through which the flexible pressure patch can be attached to the surface of the relevant article. The thickness of the adhesive layer 9 is 20 μm–800 μm, preferably 80–250 μm, and can be medical pressure-sensitive adhesive, reusable gel, removable adhesive, or structural adhesive.
[0047] The flexible pressure patch proposed in this application can be used at a single point or in an array on the surface of the object being tested. The output voltage measured by this flexible pressure patch needs to be corrected using the following formula to obtain the true pressure value: , in, The true pressure value represents the actual physical pressure applied to the flexible pressure patch, which is the target physical quantity to be measured. This pressure acts on the surface of the flexible pressure patch and is applied to the pressure-capacitance conversion unit through the pressure transmission structure, causing compression and capacitance changes in the dielectric layer. Because the output signal of the flexible pressure patch is also affected by factors such as the dynamic response of the piezoelectric bias module, etc. It cannot be obtained directly from the measured voltage, but needs to be obtained by compensating and correcting the measured signal and combining it with the calibration relationship for inversion.
[0048] This is the pressure inversion function, and also the pressure-capacitance calibration function. The inverse function is used to calculate the actual pressure value from the compensated capacitance value. This inversion process can be achieved through analytical inversion, numerical iteration, or table lookup interpolation, and is a key step in converting the output of the flexible pressure patch from an electrical signal to a physical pressure quantity. By introducing... It can be flexibly adapted to different range and sensitivity requirements in different application scenarios.
[0049] The static bias charge represents the equivalent static bias charge established between the upper and lower electrodes of the capacitor by the residual polarization formed after polarization by the piezoelectric bias module. This bias charge provides the initial electric field for capacitance measurement in the absence of an external bias power supply, enabling minute capacitance changes to be converted into a measurable electrical signal. The value remains approximately constant during the measurement process, and its magnitude depends on the polarization state of the piezoelectric material, the electrode structure, and the electrical connection method. This parameter is obtained by measuring the reference capacitance under reference pressure conditions. With corresponding output voltage And calculate get.
[0050] The actual measured output voltage is the output voltage signal acquired in real time by the readout circuit during the operation of the flexible pressure patch, and it is the only directly measurable quantity. This voltage signal comprehensively reflects the capacitance change caused by pressure, the effect of static bias charge across the capacitor, and the transient charge coupling effect generated by the piezoelectric bias module under dynamic stress or vibration. Therefore, It is not solely determined by pressure, but rather by the superposition of multiple electrical effects, the value of which is directly obtained through a high-impedance voltage follower, charge amplifier, or analog-to-digital converter circuit.
[0051] The dynamic piezoelectric interference charge represents the transient piezoelectric charge change generated by the piezoelectric bias module under dynamic stress, vibration, or impact and coupled to the measurement node. This charge is not generated by the pressure-capacitance conversion unit itself, but is an inherent dynamic response of the piezoelectric material, and is a significant interference factor causing the measured signal to deviate from the true pressure response. This parameter is obtained by individually leading out the electrodes of the piezoelectric bias module and connecting them to a high-impedance circuit or charge amplifier for real-time acquisition, and then converting it using a pre-calibrated charge-voltage relationship.
[0052] The reference capacitance represents the equivalent capacitance of the pressure-capacitance conversion unit under conditions of no external pressure or a known reference pressure. It reflects the device's initial geometry, dielectric material properties, and assembly structure. This parameter serves as a reference for subsequent capacitance changes and pressure inversion and is considered a constant during measurement. It can be obtained by direct measurement using an LCR meter, impedance analyzer, or on-chip self-test circuit under pressure-free conditions, or by theoretical calculation combined with experimental correction.
[0053] This represents the change in capacitance of the pressure-capacitance conversion unit relative to a reference state under pressure. It directly reflects physical processes such as dielectric layer compression, changes in effective contact area, and changes in equivalent dielectric constant. Because there is a nonlinear coupling relationship between capacitance change and bias charge, It is introduced as a second-order correction term to improve the accuracy of pressure inversion. This parameter is obtained by initially estimating the instantaneous capacitance value through the measured voltage and comparing it with the reference capacitance. Obtained by doing something else.
[0054] Example 1
[0055] In this embodiment, the flexible pressure patch is used at a single point, and the flexible pressure patch at this time meets the measurement requirements of wearable contact pressure.
[0056] At this point, the flexible pressure patch has an external dimension of 40 mm × 40 mm, an effective measurement area of 30 mm × 30 mm, and a total thickness of approximately 1.1 mm.
[0057] The pressure protection layer is made of TPU material with a thickness of 80μm.
[0058] In its pressure-capacitance conversion unit, both the first and second electrode layers are made of Au and have a thickness of 120 nm. The dielectric layer is made of PDMS and has a thickness of 400 μm; within the dielectric layer, the micro-bumps have a height of 120 μm, a diameter of 220 μm, and a spacing of 350 μm.
[0059] The piezoelectric bias module is a prepolarized PVDF-TrFE with a thickness of 15 μm, which is located on the back of the pressure protection layer.
[0060] The bias coupling electrode layer has a thickness of 10 nm. The flexible substrate layer is made of PI material and has a thickness of 50 μm. The adhesion layer is made of medical pressure-sensitive adhesive and has a thickness of 120 μm.
[0061] The flexible pressure patch in this embodiment supports two front-end modes: high-impedance input voltage follower and charge amplification. The sampling rate can be flexibly configured between 100 Hz and 5 kHz.
[0062] Example 2
[0063] In this embodiment, the flexible pressure patch is arranged in an 8×8 array on the surface of the object being tested. The flexible pressure patch can be used in scenarios such as robot skin, smart cushions, and foot pressure distribution.
[0064] The foregoing has provided a detailed description of a piezoelectric biased capacitor type universal flexible pressure patch provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A piezoelectric biased capacitor type universal flexible pressure patch, characterized in that, Includes, from top to bottom, the following: a bias coupling electrode layer, which is electrically connected to the piezoelectric bias module; A piezoelectric bias module includes a piezoelectric thin film and electrodes disposed on both sides of the piezoelectric thin film. The electrodes include a bias coupling electrode layer disposed above the piezoelectric thin film and a first electrode layer disposed below the piezoelectric thin film. The pressure-capacitance conversion unit includes several electrode layers arranged in a vertical direction and a dielectric layer disposed between two adjacent electrode layers. The dielectric layer includes several spaced micro-protrusions. The uppermost electrode layer in the pressure-capacitance conversion unit is the first electrode layer, which is shared by the piezoelectric bias module and the pressure-capacitance conversion unit.
2. The piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, A first pressure-bearing protective layer is provided above the bias coupling electrode layer; A flexible substrate layer is provided below the pressure-capacitance conversion unit, an adhesive layer is provided on the back of the flexible substrate layer, and a second pressure-resistant protective layer is provided between the pressure-capacitance conversion unit and the flexible substrate layer.
3. The piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, During manufacturing, the piezoelectric bias module generates residual polarization through pre-polarization, which enables the piezoelectric bias module to provide a stable static bias. When subjected to external pressure, the piezoelectric bias module generates additional charge under dynamic load, which dynamically modulates the output signal, improving the amplitude and signal-to-noise ratio (SNR) of the transient signal.
4. The piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, The true pressure value is obtained after the output voltage measured by the flexible pressure patch is corrected by the formula. , in, The actual pressure value represents the real physical pressure applied to the flexible pressure patch. It is a pressure inversion function and a pressure-capacitance calibration function. The inverse function is used to calculate the actual pressure value from the compensated and corrected capacitance value. The static bias charge represents the equivalent static bias charge established between the upper and lower electrodes of the capacitor by the residual polarization formed after polarization by the piezoelectric bias module; this parameter is obtained by measuring the reference capacitance under reference pressure conditions. With corresponding output voltage And calculate get; The actual measured output voltage is the output voltage signal that the flexible pressure patch acquires in real time by the readout circuit during operation. Dynamic piezoelectric interference charge represents the transient piezoelectric charge changes generated by the piezoelectric bias module under dynamic stress, vibration, or impact and coupled to the measurement node. The reference capacitance represents the equivalent capacitance value of the pressure-capacitance conversion unit under conditions of no external pressure or known reference pressure. This parameter represents the change in capacitance of the pressure-capacitance conversion unit relative to a reference state under pressure. The instantaneous capacitance value is obtained by initially estimating the measured voltage and comparing it with the reference capacitance. Obtained by doing something else.
5. A piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, The thickness of the piezoelectric film is 3 μm–80 μm; When the electrode is a metal film electrode, the electrode thickness is 50 nm–500 nm; when the electrode is prepared by screen printing or inkjet printing, the electrode thickness is 1 μm–15 μm.
6. The piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, The shapes of the micro-protrusions include, but are not limited to, cylindrical, square, pyramidal, and conical shapes.
7. A piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, The overall thickness of the pressure-capacitance conversion unit is 50 μm–1500 μm; The height of the micro-protrusions ranges from 10 μm to 500 μm, the width or diameter of the bottom of the micro-protrusions ranges from 20 μm to 800 μm, and the spacing between the micro-protrusions ranges from 30 μm to 1200 μm.
8. A piezoelectric biased capacitor type universal flexible pressure patch according to claim 1, characterized in that, Flexible pressure patches are arranged in an array on the surface of the object being tested. At this point, the piezoelectric bias modules or pressure-capacitance conversion units in each flexible pressure patch are arranged in a continuous, integrated manner, or in separate zones.