High-linearity dynamic and static pressure flexible sensor based on Gaussian height distribution

Abstract

The invention discloses a high-linearity dynamic and static pressure flexible sensor based on Gaussian height distribution. The high-linearity dynamic and static pressure flexible sensor comprises a packaging layer, an upper electrode layer, a piezoelectric layer, a common electrode layer, an insulating layer, a lower electrode layer and a substrate layer which are sequentially stacked from top to bottom, the piezoelectric layer comprises a plurality of PVDF micro-columns, the top ends of the PVDF micro-columns are fixedly connected with the upper electrode layer, the bottom ends of the PVDF micro-columns are provided with micro-electrode layers, and the height of the PVDF micro-columns is of a Gaussian distribution structure from the center to the periphery; the common electrode layer is provided with a plurality of micro-column through holes which are completely overlapped with the PVDF micro-columns; the output leads of the upper electrode layer and the common electrode layer output piezoelectric signals corresponding to dynamic pressure, and the output leads of the common electrode layer and the lower electrode layer output capacitance signals corresponding to static pressure. According to the invention, the dynamic pressure is measured by using the piezoelectricity of PVDF, synchronous measurement of static pressure is realized through a Gaussian distribution structure of a plurality of PVDF micro-columns, and high-sensitivity and high-linearity output of dynamic and static pressure measurement signals is realized.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to a high-linearity dynamic-static pressure flexible sensor based on a Gaussian height distribution. Background Technology

[0002] Existing flexible pressure sensors are mainly divided into piezoelectric and capacitive types, but both have significant drawbacks: (1) Although piezoelectric pressure sensors are sensitive to dynamic signals (such as vibration and sound), they cannot measure static pressure (such as continuous gripping force and water depth) due to charge leakage characteristics, which limits their application scenarios; (2) Although traditional capacitive pressure sensors can measure static pressure, their capacitance value C is inversely proportional to the distance d between the plates, resulting in a severe nonlinearity in the response curve (sensitive at low pressure and sluggish at high pressure). Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a flexible dynamic and static pressure sensor with high linearity based on Gaussian height distribution, which can measure dynamic pressure by utilizing the piezoelectricity of PVDF and realize synchronous measurement of static pressure through the Gaussian distribution structure of PVDF micropillars, thereby achieving the output of dynamic and static pressure measurement signals with high sensitivity and high linearity.

[0004] The technical solution of this invention is as follows: A high-linearity dynamic-static pressure flexible sensor based on a Gaussian height distribution includes, from top to bottom, an encapsulation layer, an upper electrode layer, a piezoelectric layer, a common electrode layer, an insulating layer, a lower electrode layer, and a substrate layer. The piezoelectric layer comprises multiple PVDF micropillars, all with the same horizontal height at their tops and fixedly connected to the bottom surface of the upper electrode layer. Each PVDF micropillar has a microelectrode layer at its bottom. The height of the PVDF micropillars exhibits a Gaussian distribution from the center outwards, with the highest height at the center, radiating outwards. The high-linearity dynamic and static pressure flexible sensor consists of multiple PVDF micropillars with gradually decreasing heights, such that the PVDF micropillars at the edge have the shortest height. When the sensor is not under stress, the piezoelectric layer is suspended directly above the common electrode layer, meaning that the bottom ends of the multiple PVDF micropillars do not contact the common electrode layer. The common electrode layer has multiple micropillar perforations that completely overlap with the multiple PVDF micropillars. The output leads of the upper electrode layer and the common electrode layer output piezoelectric signals corresponding to dynamic pressure, while the output leads of the common electrode layer and the lower electrode layer output capacitive signals corresponding to static pressure.

[0005] Both the encapsulation layer and the substrate layer are made of polyimide film.

[0006] The piezoelectric layer includes an upper PVDF layer and multiple PVDF micropillars. The top end of the upper PVDF layer is fixedly connected to the bottom surface of the upper electrode layer, and the top ends of the multiple PVDF micropillars are all fixedly connected to the bottom surface of the upper PVDF layer. The upper PVDF layer and the multiple PVDF micropillars are an integral molded structure.

[0007] The upper electrode layer, common electrode layer, lower electrode layer and microelectrode layer are all made of deposited gold electrode layer or silver nanowire electrode layer.

[0008] The insulating layer is made of alumina.

[0009] The high linearity dynamic and static pressure flexible sensor, in the unloaded state, has an initial capacitance signal output by the output leads of the common electrode layer and the lower electrode layer with a capacitance value of When the high-linearity dynamic-static pressure flexible sensor is subjected to downward static pressure, multiple PVDF micropillars in the piezoelectric layer are pressed into the micropillar perforations of the common electrode layer, and the microelectrode layer at the bottom of the PVDF micropillars contacts the insulating layer. At this time, the capacitance signal output by the output leads of the common electrode layer and the lower electrode layer has a capacitance value of The calculation formula is shown in the following formula (1): (1); In equation (1), Represents the vacuum dielectric constant; The relative permittivity of the insulating layer; This represents the distance between the common electrode layer and the lower electrode layer, i.e., the thickness of the insulating layer; The area representing the contact area between the microelectrode layer and the insulating layer at the bottom of multiple PVDF micropillars is calculated using the following formula (2). (2); In equation (2), This represents the total number of PVDF micropillars; This represents the area of ​​the microelectrode layer at the bottom of a single PVDF micropillar. This represents the height of the PVDF micropillar located at the center, i.e., the maximum height of the PVDF micropillar; This represents the downward displacement of the piezoelectric layer, compared to hydrostatic pressure. Linear correlation, , The equivalent elastic modulus of the piezoelectric layer is obtained through calibration. Represents the height of PVDF micropillars, and the height of multiple PVDF micropillars. Follows the probability density function .

[0010] The probability density function It conforms to the following formula (3): (3); In equation (3), Represents the height in a Gaussian distribution The mean, Represents the height in a Gaussian distribution The variance; Substituting equation (3) into equation (2) yields equation (4): (4); In equation (4), This represents the total area of ​​all microelectrode layers at the bottom of multiple PVDF micropillars. ; Represents the error function. The calculation formula is shown in the following formula (5): (5); In equation (5), The index representing the number of terms in a Taylor series expansion. .

[0011] The open-circuit voltage of the piezoelectric signal corresponding to the dynamic pressure output from the output leads of the upper electrode layer and the common electrode layer. Satisfy the following equation (6): (6); In equation (6), The pressure value representing dynamic pressure; Represents open-circuit voltage. This represents the calibration coefficient, which is obtained by calibrating the open-circuit voltage using known dynamic pressure. .

[0012] Advantages of this invention: (1) The capacitance value of the capacitance signal collected by the present invention is proportional to the area between the common electrode layer and the lower electrode layer. That is, when the area between the common electrode layer increases, the capacitance value collected increases. After the PVDF (polyvinylidene fluoride) micropillar of the present invention is pressed down and moves into the micropillar perforation, the microelectrode layer contacts the insulating layer, and the area between the common electrode layer and the lower electrode layer is increased by the microelectrode layer at the bottom of the PVDF micropillar. When the number of microelectrode layers in contact with the insulating layer increases, the area between the common electrode layer and the lower electrode layer increases linearly, thereby realizing the linear relationship between capacitance and pressure. Moreover, the height of multiple PVDF micropillars is a Gaussian distribution structure, so that the rate of increase of the contact area between the microelectrode layer and the insulating layer just compensates for the nonlinear trend.

[0013] (2) The upper electrode layer and the common electrode layer of the present invention form a piezoelectric pressure sensor. When the dynamic pressure wave is applied, the PVDF micropillars that are in contact with the insulating layer at the bottom act as rigid fulcrums, thereby efficiently converting the dynamic pressure into the vertical compressive stress inside the PVDF micropillars. This allows the PVDF micropillars that have established contact with the common electrode layer to participate in the piezoelectric conversion, thereby realizing the continuous acquisition of dynamic pressure. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention.

[0015] Figure 2 This is a three-dimensional structural diagram of the piezoelectric layer of the present invention.

[0016] Figure 3 This is a schematic diagram of the planar structure of the common electrode layer of the present invention.

[0017] Reference numerals: 1-Encapsulation layer, 2-Upper electrode layer, 3-Piezoelectric layer, 4-Common electrode layer, 5-Insulating layer, 6-Lower electrode layer, 7-Base layer, 31-Upper PVDF layer, 32-PVDF micropillar, 33-Microelectrode layer, 41-Micropillar perforation. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] See Figure 1 A high linearity dynamic and static pressure flexible sensor based on Gaussian height distribution includes an encapsulation layer 1, an upper electrode layer 2, a piezoelectric layer 3, a common electrode layer 4, an insulating layer 5, a lower electrode layer 6, and a substrate layer 7 stacked sequentially from top to bottom. See Figure 2The piezoelectric layer 3 includes an integrally molded upper PVDF layer 31 and multiple PVDF micropillars 32. The top of the upper PVDF layer 31 is fixedly connected to the bottom surface of the upper electrode layer 2. The top of the multiple PVDF micropillars 32 is fixedly connected to the bottom surface of the upper PVDF layer 31. The bottom of the multiple PVDF micropillars 32 is provided with a microelectrode layer 33. The height of the multiple PVDF micropillars 32 presents a Gaussian distribution structure from the center to the periphery. That is, the PVDF micropillars 32 located at the center are the tallest, and the height of the multiple PVDF micropillars 32 spreading from the center to the periphery gradually decreases, so that the height of the PVDF micropillars 32 located at the edge is the shortest. When the high linearity dynamic and static pressure flexible sensor is not under force, the piezoelectric layer 3 is suspended directly above the common electrode layer 4, that is, the bottom of the multiple PVDF micropillars 32 does not contact the common electrode layer 4. See Figure 3 Multiple micropillar perforations 41 are formed on the common electrode layer 4, and the multiple micropillar perforations 41 completely overlap with multiple PVDF micropillars 32; the output leads of the upper electrode layer 2 and the common electrode layer 4 output piezoelectric signals corresponding to dynamic pressure, and the output leads of the common electrode layer 4 and the lower electrode layer output capacitive signals corresponding to static pressure.

[0020] Both the encapsulation layer 1 and the substrate layer 7 are made of polyimide (PI) film. The upper electrode layer 2, the common electrode layer 4, the lower electrode layer 6, and the microelectrode layer 33 are all made of deposited gold electrode layer or silver nanowire electrode layer. The insulating layer 5 is made of alumina insulating layer.

[0021] In the unloaded state, the initial capacitance signal output by the output leads of the common electrode layer 4 and the lower electrode layer 6 of the high linearity dynamic and static pressure flexible sensor has a capacitance value of When the high-linearity dynamic-static pressure flexible sensor is subjected to downward static pressure, the multiple PVDF micropillars 32 of the piezoelectric layer 3 are pressed into the micropillar perforations 41 of the common electrode layer 4, and the microelectrode layer 33 at the bottom of the PVDF micropillars contacts the insulating layer 5. At this time, the capacitance value of the capacitance signal output by the output leads of the common electrode layer 4 and the lower electrode layer 6 is... The calculation formula is shown in the following formula (1): (1); In equation (1), Represents the vacuum dielectric constant; Represents the relative permittivity of insulating layer 5; This represents the distance between the common electrode layer 4 and the lower electrode layer 6, i.e., the thickness of the insulating layer 5; The area representing the contact area between the microelectrode layer 33 at the bottom of multiple PVDF micropillars and the insulating layer 5 is calculated using the following formula (2). (2); In equation (2), Represents the total number of PVDF micropillars 32; This represents the area of ​​the microelectrode layer 33 at the bottom of a single PVDF micropillar; This represents the height of the PVDF micropillar 32 located at the center, which is the maximum height of the PVDF micropillar; This represents the downward displacement of piezoelectric layer 3, compared to static pressure. Linear correlation, , The equivalent elastic modulus of piezoelectric layer 3 is obtained through calibration; This represents the height of a single PVDF micropillar 32, and the height of multiple PVDF micropillars 32. Follows the probability density function probability density function It conforms to the following formula (3): (3); In equation (3), Represents the height in a Gaussian distribution The mean, Represents the height in a Gaussian distribution The variance; Substituting equation (3) into equation (2) yields equation (4): (4); In equation (4), This represents the total area of ​​all microelectrode layers 33 at the bottom of multiple PVDF micropillars. ; Represents the error function. The calculation formula is shown in the following formula (5): (5); In equation (5), The index representing the number of terms in a Taylor series expansion. ; Combining equations (1) and (4), and displacement With static pressure The linear relationship is used to obtain the capacitance value. With static pressure The specific relation is shown in equation (7) below: (7); In equation (7), For the sensitivity coefficient of static pressure measurement, equation (7) shows that within the designed operating range (i.e., Gaussian distribution), Within the range), capacitance value With static pressure The height exhibits a linear proportional relationship, which can be achieved by adjusting the standard deviation σ of the height of multiple PVDF micropillars (i.e., height). The discrete program allows for precise adjustment of the sensor's linear operating range and sensitivity in static pressure measurement. The larger the value, the wider the linear range, but the lower the sensitivity. The smaller the value, the higher the sensitivity and the narrower the linear range.

[0022] The open-circuit voltage of the piezoelectric signal corresponding to the dynamic pressure output from the output leads of the upper electrode layer 2 and the common electrode layer 4. Satisfy the following equation (6): (6); In equation (6), The pressure value representing dynamic pressure; Represents open-circuit voltage. This represents the calibration coefficient, which is obtained by calibrating the open-circuit voltage using known dynamic pressure. .

[0023] From equation (6) above, we can see that the open-circuit voltage With dynamic pressure It is a linear relationship, i.e., dynamic pressure. The increase of open circuit voltage That is, it increases linearly.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution, characterized in that: The flexible sensor comprises a packaging layer, an upper electrode layer, a piezoelectric layer, a common electrode layer, an insulating layer, a lower electrode layer and a substrate layer which are sequentially stacked from top to bottom; the piezoelectric layer comprises a plurality of PVDF micro columns, the top ends of the plurality of PVDF micro columns have a same height and are fixedly connected to the bottom surface of the upper electrode layer, the bottom ends of the plurality of PVDF micro columns are provided with a micro electrode layer, and the heights of the plurality of PVDF micro columns present a Gaussian distribution structure from the center to the periphery, that is, the PVDF micro column at the center has the highest height, the heights of the plurality of PVDF micro columns gradually shorten from the center to the periphery, so that the PVDF micro columns at the edge have the shortest height; when the flexible sensor is not stressed, the piezoelectric layer is suspended above the common electrode layer, that is, the bottom ends of the plurality of PVDF micro columns are not in contact with the common electrode layer; a plurality of micro column perforations are formed in the common electrode layer, and the plurality of micro column perforations completely overlap the plurality of PVDF micro columns; the upper electrode layer and the common electrode layer output piezoelectric signals corresponding to dynamic pressure through output leads, and the common electrode layer and the lower electrode layer output capacitance signals corresponding to static pressure through output leads.

2. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 1, characterized in that: The packaging layer and the substrate layer are both polyimide films.

3. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 1, characterized in that: The piezoelectric layer comprises an upper PVDF layer and a plurality of PVDF micro columns, the top end of the upper PVDF layer is fixedly connected to the bottom surface of the upper electrode layer, the top ends of the plurality of PVDF micro columns are fixedly connected to the bottom surface of the upper PVDF layer, and the upper PVDF layer and the plurality of PVDF micro columns are integrally molded.

4. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 1, characterized in that: The upper electrode layer, the common electrode layer, the lower electrode layer and the micro electrode layer are all deposited gold electrode layers or silver nanowire electrode layers.

5. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 1, characterized in that: The insulating layer is an aluminum oxide insulating layer.

6. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 1, characterized in that: The initial capacitance signal outputted by the output lead of the common electrode layer and the lower electrode layer in the unstressed state of the high linearity dynamic and static pressure flexible sensor has a capacitance value of When the high linearity dynamic and static pressure flexible sensor is subjected to a downward static pressure, the plurality of PVDF micro columns of the piezoelectric layer are pressed into the micro column perforations of the common electrode layer, and the micro electrode layer at the bottom end of the PVDF micro column is in contact with the insulating layer, at this time, the capacitance signal outputted by the output lead of the common electrode layer and the lower electrode layer has a capacitance value of The calculation formula is shown in the following formula (1): （1）； In formula (1), represents the vacuum dielectric constant; represents the relative dielectric constant of the insulating layer; represents the distance between the common electrode layer and the lower electrode layer, i.e. the thickness of the insulating layer; represents the area of the contact between the plurality of PVDF micro-column bottom micro-electrode layers and the insulating layer, and the calculation formula is shown in formula (2) below; （2）； In formula (2), represents the total number of PVDF micro-pillars; represents the area of the bottom micro-electrode layer of a single PVDF micro-pillar; represents the height of the PVDF micro-pillar located at the center, i.e. the maximum height of the PVDF micro-pillar; represents the amount of displacement of the piezoelectric layer downward, which is linearly related to the static pressure , , represents the equivalent elastic modulus of the piezoelectric layer, which is obtained by calibration; represents the height of the PVDF micro-pillar, and the heights of the plurality of PVDF micro-pillars subject to the probability density function .

7. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 6, characterized in that: The probability density function complies with the following equation (3): （3）； In formula (3), represents a mean value of the height in the Gaussian distribution, represents a variance of the height in the Gaussian distribution; Formula (3) is brought into formula (2) to obtain the following formula (4): （4）； In formula (4), represents the total area of all microelectrode layers at the bottom end of the plurality of PVDF microcolumns, ; represents the error function, The calculation formula of is shown in formula (5) below. （5）； In formula (5), represents the index of the number of terms of the Taylor series expansion, .

8. The high linearity dynamic-static pressure flexible sensor based on Gaussian height distribution according to claim 1, characterized in that: The output lead output of the upper electrode layer and the common electrode layer corresponds to a piezoelectric signal whose open circuit voltage satisfies the following equation (6): （6）； In formula (6), a pressure value representing dynamic pressure; represents open circuit voltage, represents a calibration coefficient, which is obtained by calibrating open circuit voltage with known dynamic pressure .

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