High-sensitivity wide-measurement-range pressure distribution monitoring ultra-thin flexible pad system capable of being printed in any size

Abstract

A wide measurement range pressure distribution monitoring flexible planar pad system includes a first electrode layer, a first piezoelectric composite dielectric layer, a second piezoelectric composite dielectric layer facing the first piezoelectric composite dielectric layer, and a second electrode layer. The first and second piezoelectric composite dielectric layers each include an elastomeric matrix having conductive particles and dielectric particles embedded therein. The relative dimensions of the conductive particles and the dielectric particles form a micro-rough interface between these layers and form a range of contact area with the electrode layers, resulting in a pressure detection range of 0-3000 kPa. The flexible planar pad system also includes a data collector for collecting pressure signals from the planar pad, and a pressure profile data processor for receiving and calculating data from the data collector, creating a two-dimensional pressure profile from the flexible planar pad.

Description

Cross - reference to related applications

[0001] This application claims the priority of U.S. Application No. 18 / 426,301, filed on January 29, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical field

[0002] The present invention relates to the technical field of pressure distribution monitoring sensors. More specifically, the present invention relates to an ultra - thin, flexible, and highly sensitive pressure distribution sensor array for measuring dynamic forces and pressure distributions between relative objects over a wide pressure range. Background art

[0003] Traditional pressure sensors are rigid and large in volume and can only be used for single - point pressure monitoring. Therefore, they are not suitable for shape scenarios that require thinness and flexibility or applications that require the ability to depict pressure mapping. Pressure mapping depicts the pressure distribution caused by the interaction of two objects at multiple contact points. Pressure mapping is widely used to determine the pressure distribution between the human body and a mattress, the foot and an insole, the head and a pillow, etc. The pressure distribution obtained from pressure mapping can also be widely used in the scientific analysis of sports, the adjustment of pressure uniformity for pressure - based machines, game and music pads, the flatness inspection of products, the design assistance of sports equipment, and electronic skin.

[0004] However, the pressure sensing range of most pressure sensors is very narrow, which limits their practical applications. For example, some sensors can only test pressures below 50 kPa, while other sensors can only sense pressures above 50 kPa. Generally, such sensors with a relatively high pressure level are not sensitive to small pressures below 50 kPa and are prone to saturation at relatively high pressures. Therefore, to meet the test requirements for sensing a wide pressure range, traditional tests require replacing pressure sensors with different pressure sensing specifications; however, such techniques cannot be used for continuous and dynamic monitoring of pressures that vary over a wide range.

[0005] CN 112835468 mentions a sensor for measuring touches in a multi - touch system. The sensor uses conductive first and second particles in a dielectric elastomer layer. This document requires that the first and second particles be vertically arranged with a gap in between; the upper surface of the first particle is at the same height as the upper side of the elastic dielectric layer; the lower surface of the second particle is at the same height as the lower surface of the elastic dielectric. Under the action of force (for example, when a user presses the pressure receiving plate with a finger), some of the first and second particles are connected to each other, and a closed circuit is formed between the first electrode and the second electrode, and a certain resistance can be detected. Although this document provides touch tension, its pressure sensing range is very narrow, and it requires precise particle spacing and orientation, and the manufacturing process is also very complex.

[0006] U.S. Patent 11,740,143 describes a fabric-based pressure sensor array for determining the pressure distribution of soft and curved contact surfaces such as cushions and car seats. However, this fabric-based pressure sensor array also has its inherent disadvantages; for example, the irregular surface of the fabric affects the accuracy and consistency of the printed circuit; deformation (such as stretching and twisting of the fabric) will change its impedance and affect the test results, while the electrode material printed on the fabric surface has relatively poor fastness. In addition, fabric-based sensors typically have high crosstalk effects, low sensitivity, small measurement range and complex production process. Therefore, there is a need in the art for an improved pressure sensor array for a pressure distribution mapping system, which pressure sensor array needs to have high sensitivity and accuracy, excellent consistency and durability, a wide measurement range and a convenient production process. The present invention addresses this need. Summary of the Invention

[0007] The present invention provides a flexible planar pad system for monitoring pressure distribution, which has a wide range of pressure measurement capabilities. The flexible planar pad includes a first electrode layer and a first piezoelectric composite dielectric layer. The second piezoelectric composite dielectric layer faces the first piezoelectric composite dielectric layer, and the second electrode layer is located below the second piezoelectric composite dielectric layer. Each of the first and second piezoelectric composite dielectric layers includes an elastomeric matrix having a first group of conductive particles embedded therein. The conductive particles are selected from one or more of carbon nanotubes, graphite particles, carbon fibers, carbon spheres, activated carbon, acetylene black, semiconductors, metals or graphene, with a content of approximately 2% to 10% by weight. Dielectric particles are also embedded in the elastomeric matrix, selected from one or more of silicon dioxide, zirconium oxide, aluminum oxide, boron nitride, aluminum nitride, silicon nitride, zinc oxide, silicon carbide, titanium dioxide or calcium carbonate, with a content of approximately 1% to 5% by weight and a particle size of approximately 0.5-1 micrometer.

[0008] The flexible planar pad has a total thickness of less than approximately 0.30 mm. The relative sizes of the conductive particles and the dielectric particles are configured such that the interface between the piezoelectric composite dielectric layer and the electrode layer presents a micro-rough surface, resulting in a contact area of 0-10% of the layer surface area under a low pressure load of 50 kPa or less and a contact area of 10-100% of the layer surface area under a high pressure load of 50-3000 kPa, such that the total pressure detection range of the pressure distribution monitoring flexible planar pad system is 0-3000 kPa.

[0009] Optionally, the flexible planar pad system further includes a data collector and a pressure distribution data processor, wherein the data collector is configured to collect pressure signals from the flexible planar pad. The pressure distribution data processor is configured to receive data from the data collector, perform calculations, and create a two-dimensional pressure distribution map from the flexible planar pad.

[0010] In another embodiment, the first electrode layer and the second electrode layer are each formed on a substrate having a thickness of 50 to 100 micrometers.

[0011] In yet another embodiment, the substrate is selected from polyethylene terephthalate or polyimide.

[0012] In yet another embodiment, the first electrode layer and the second electrode layer include screen-printed circuits, and the screen-printed circuits include a first set of electrode conductive particles.

[0013] In yet another embodiment, the electrode conductive particles are selected from one or more of silver, copper, or aluminum.

[0014] In yet another embodiment, the data collector includes a resistor, a signal amplifier, an analog-to-digital converter, and a data transmitter. The resistor is configured to measure and record the resistance of each pressure sensor in the flexible planar pad under different pressures.

[0015] In yet another embodiment, the pressure distribution data processor provides a static or dynamic two-dimensional pressure distribution pattern of the applied pressure.

[0016] In yet another embodiment, the piezoelectric composite dielectric layer includes a second set of conductive particles different from the first set of conductive particles.

[0017] In yet another embodiment, the second set of conductive particles may be one or more of carbon nanotubes, graphite particles, carbon fibers, carbon spheres, activated carbon, acetylene black, semiconductors, metals, or graphene.

[0018] In yet another embodiment, the elastomeric matrix includes nitrile rubber, silicone-based polymers, butyl rubber, polyurethane elastomers, bromobutyl rubber, chlorobutyl rubber, polyurethanes, natural rubber, polyisoprene rubber, polybutadiene rubber, ethylene-propylene rubber, polysulfides, ethylene-propylene-diene rubber, poly(styrene-butadiene) rubber, poly-isoprene-co-butadiene rubber, styrene-isoprene-butadiene rubber, or combinations thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of the present invention are described in more detail below with reference to the accompanying drawings, in which:

[0020] Figure 1 A pressure mapping system 10 according to an embodiment of the present invention is shown.

[0021] Figure 2A [[ID=3�]]Shown for Figure 1 The layer structure of the pressure sensing pad of the pressure mapping system.

[0022] Figure 2B Shown for Figure 2AThe screen-printed patterns of various layers in, including (i) the upper surface of the electrode layer; (ii) the lower surface of the electrode layer; (iii) the piezoresistive dielectric double sandwich layer.

[0023] Figures 3A - 3C Schematically depicts the deformation of the pressure sensing pad and the change of the sensing mode as the pressure in the pressure sensor pad increases. Figure 3A Cross-section of the pressure sensor array in the sensing pad with the upper and lower electrode piezoresistive dielectric double sandwich layers; Figure 3B The point-to-point contact mode of the sensor array at lower pressure; Figure 3C The area-to-area contact mode and the compressive deformation of the piezoresistive dielectric at higher pressure.

[0024] Figure 4 Shows the fabricated 50×36 pressure sensing pad.

[0025] Figure 5 Shows an experimental pressure distribution monitoring system equipped with a pressure sensing pad, a data collector, and a pressure distribution data processor.

[0026] Figure 6 Shows the pressure sensing pad configurations of other specifications.

[0027] Figure 7A Shows the correlation between conductivity and pressure on a single pressure sensor in the pressure sensing monitoring pad; Figure 7B Is the durability test of the pressure sensor array in the pressure sensing pad.

[0028] Figure 8 Shows the graphical pressure distribution mapping with 2-D image output on the sensing pad under the condition of lower pressure.

[0029] Figure 9 Shows the graphical pressure distribution mapping with 2-D image output on the sensing pad under the condition of higher pressure.

[0030] Figure 10 Shows the surface micro-roughness of the printed electrode lines. Detailed Description of the Invention

[0031] Turning to the drawings, Figure 1 Shows a pressure mapping system 10, which includes a pressure sensing ultra-thin pad 100, and the pressure sensing ultra-thin pad 100 includes a printed pressure sensor array 110, a data collector 200, and a pressure distribution data processor 300.

[0032] Figure 2AThe pressure sensing ultra-thin pad 100 is depicted more schematically in detail. The printed pressure sensor array 110 includes two flexible film substrates 120, 125 having printed silver electrodes 130, 135 and piezoresistive dielectric intermediate layers 140, 145. Using low-cost printing techniques such as screen printing, pressure sensing pads of various sizes can be fabricated according to the desired sensing applications. Figure 2B An example of the electrode pattern for layers 130 and 135 is depicted. The electrode pattern typically uses a conductive paste with a particle size of about 0.5 to 1.0 microns and is optionally deposited by printing. The formed wire pattern forms a micro-rough surface on the flexible film substrates 120 and 125.

[0033] The piezoresistive dielectric intermediate layers 140 and 145 include a unique combination of conductive particles and dielectric particles in a flexible polymer elastomeric phase, which enables the pressure sensing pad to accurately sense pressures in the low pressure range below 50 kPa and the high pressure range above 50 kPa and even up to 3000 kPa. Figures 3A - 3C The sensing members of the pressure sensor array formed by the combination of conductive particles and dielectric particles are depicted schematically. The micro-rough electrode layers 130 and 135 on the substrates 120 and 125 are in contact with the piezoresistive dielectric intermediate layers 140 and 145 respectively. In Figure 3A This micro-rough condition is described. Under the applied low external pressure (e.g., below 50 kPa), the contact between the conductive particles 142 and 147 is point-to-point contact, making the whole system sensitive to extremely low applied pressures. At a larger applied pressure (e.g., pressure above 50 kPa), the gaps between the peaks and valleys supported by the microparticles 148 of the rough surface are compressed / flattened. As a result, the contact mode changes to an area-to-area contact mode. As the pressure increases, the layer composition is further compressed and deformed. However, due to the presence of the micro-dielectric particle additive, the structural integrity of the system is sufficiently maintained, increasing the detection limit of the system to a higher pressure level without overloading the pressure sensor array structure.

[0034] Generally, the micro-rough surface is configured such that a contact area of about 0 - 10% of the layer surface area is generated under a low pressure load of 50 kPa or less, while a contact area of about 10 - 100% of the layer surface area is generated under a high pressure load of 50 - 3000 kPa, enabling the total pressure detection range of the pressure distribution monitoring ultra-thin flexible planar pad system to be 0 - 3000 kPa.

[0035] Layers 140 and 145 are specifically designed to provide this unique multi-mode contact structure, which enables a wide pressure detection range. These layers are formed using a screen-printable piezoresistive dielectric composition. The matrix 149 of the composition provides a partial elastomeric structure, thus forming an elastic layer. Embedded in the elastomeric matrix are conductive particles 142 and 147, which will form conductive paths between layers 140 and 145 and electrode layers 130, 135 under an applied pressure. Insulating / dielectric microparticles 148 contribute to structural support and prevent premature compression / flattening, such that the system will not be overloaded at intermediate pressures. That is, due to the presence of microparticles 148, a greater force is required to reach Figure 3C the state shown. Therefore, a greater pressure sensing range can be achieved in the pressure mapping system 10.

[0036] The matrix 149 can be selected from a variety of polymeric materials, especially elastomers such as rubber can be chosen. Mixtures of elastomeric polymers and non-elastomeric base polymeric materials can also be used. Examples of suitable elastomeric materials include nitrile rubbers (such as hydroxyl-terminated nitrile rubber), silicone-based polymers, butyl rubber, polyurethane elastomers, bromobutyl rubber, chlorobutyl rubber, polyurethanes, natural rubber, polyisoprene rubber, polybutadiene rubber, ethylene-propylene rubber, polysulfides, ethylene-propylene-diene rubber, poly(styrene-butadiene) rubber, poly-isoprene-co-butadiene rubber, styrene-isoprene-butadiene rubber, all of which can optionally be mixed with thermoplastic or thermosetting polymers such as phenoxy resin, PMMA, cellulose acetate butyrate, polyvinyl chloride, propyl alkyl polymer, polycarbonate, polyvinyl chloride, polyester, polyacrylate, butyral resin, polyamide, melamine resin, phenolic resin, and phenoxy resin.

[0037] For solvent-based screen printing, these materials are dissolved or dispersed in one or more solvents, such as polyvinyl acetate, 2-(methoxy)ethanol, 2-butoxyethanol, 2-(isostarchoxy)alcohol, 2-(hexyloxy)alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, liquid polyethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-acetone, dipropylene glycol, dipropylene glycol monomethyl ether, dipropanol monoethyl ether, low molecular weight polypropylene glycol, aniline, ethylene glycol, propylene glycol monoethyl ether acetate, ethyl acetate, isopropyl acetate, methyl ethyl ketone, dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, 2-butoxyethyl acetate, diglycidyl ether, phenyl glycidyl ether, cyclohexanediol diglycidyl ether, resorcinol diglycidyl ester, o-tolyl glycidyl ether, trimethylolpropane triglycidyl ether, glycerol ether, formamide, chlorobenzene, o-xylene, diacetone alcohol, butyl acetate.

[0038] The conductive particles 142, 147 can be selected based on the desired pressure range / sensitivity, and thus particles with different conductivities or a single type of particle with a single conductivity can be combined. Examples of particles include carbon nanotubes, graphite, graphene, carbon black, carbon fiber, carbon spheres, activated carbon, acetylene black, metals such as copper, aluminum, silver, or semiconductors such as silicon, germanium, gallium arsenide, indium phosphide, gallium nitride, zinc oxide, aluminum nitride, silicon carbide, etc. For metals, nanowires or nanoparticles can be used. The conductivity of at least one group of particles should be in the range of 10–10 3 mS / cm, while the conductivity of a second group of particles with higher conductivity can be in the range of 10 4 –10 8 mS / cm. In one embodiment, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of about 5 - 15 nanometers and a length of about 2 micrometers to 10 micrometers. By creating a custom-designed particle mixture with a specific conductivity, the pressure sensing pad can be customized for a specific application to obtain a sensitive pressure response within a specific range. Generally, the particle size ranges from 2 nanometers to 20 micrometers, and different particle shapes such as spherical, flaky, rod-shaped, and cubic can be used.

[0039] The structural / dielectric particles 148 can be ceramic or glass particles, which have a conductivity of 10 -22 -10 -5 mS / cm and a size range of 0.5 micrometers to 1 micrometer. Exemplary ceramic / glass particles include silica, zirconia, alumina, boron nitride, aluminum nitride, silicon nitride, zinc oxide, silicon carbide, titanium dioxide, calcium carbonate particles. Generally, the particle loading in the elastomeric matrix contributes to the micro-roughness on the surfaces 140, 145 of the dielectric layer after curing. This micro-roughness in the surfaces of the dielectric layers 140, 145 can be represented as peaks and valleys, which extend to a height / depth of + / - about 10 - 30% of the average surface height across the layer surface.

[0040] The particle loading can be selected according to the desired application. For a pressure detection range of 0 - 3000 kPa, the weight percentage range of the particles 142 and 147 is 1% to 10% of the weight of the layers 140 and 145. By weight of the layers 140 and 145, the range of the structural particles 148 is 1% to 5%. For a higher pressure range (i.e., the upper end of the pressure range), fewer conductive particles and more structural particles are used, while for a more sensitive pad, more conductive particles and fewer structural particles are used.

[0041] The conductive electrode layers 130, 135 can take the form of a first set of parallel lines in layer 130, and another set of parallel lines is at 90 degrees to the first set of lines in layer 135, as Figure 2BAs shown. To form the micro-rough electrode lines, electrode conductive particles sized approximately 0.5 to 1 micrometer are embedded in a matrix to form a conductive paste. The electrode conductive particles (such as silver, copper, aluminum, and their mixtures) can be used in layers 130 and 135. After drying, the protrusions formed by each line form a micro-rough surface, as Figure 10 shown. As Figure 10 shown, the micro-roughness caused by the particles can be in the range of 0.5 micrometer to 1 micrometer because this is the particle size of the particles used in the electrode conductive paste. When the selected particle size changes, this roughness will change. Additionally, if any heating is used to melt or partially melt or fuse the particles, the roughness will be less than the particle size.

[0042] On the other hand, the present invention provides a simple method for manufacturing an ultra-thin pressure sensing pad for a pressure sensing system 10. First, an electrode conductive paste is printed on the surface of a film-type substrate to form layers 130 and 135. In one aspect, the substrate for layers 130 and 135 can be selected from conventional flexible electronic substrates (such as: polyethylene terephthalate (PET) substrate or polyimide (PI) film substrate) to form layers 130 and 135.

[0043] The piezoresistive dielectric composition can be directly coated on the conductive electrode layer by a screen printing method. The combination of layers 130, 135 and 140, 145 is laminated together in a face-to-face direction to obtain a sandwich pressure sensing pad as Figure 2A shown. Note that it is necessary to confirm that the directions of the upper electrode layer 130 and the lower electrode layer 135 are rows and columns respectively. Individual pressure sensors are formed by the intersection between a row conduction path and a column conduction path and a portion of the piezoresistive layer in the area located at the intersection. The thickness of the prepared pressure sensing pad can be in the range of approximately 0.10 - 0.22 millimeters, but other thickness ranges are also possible depending on the application and its desired pressure sensing range.

[0044] The pressure mapping system 10 includes a data collector 200. The data collector 200 includes a resistor, a signal amplifier, an analog-to-digital converter, and a data transmitter. The resistor is used to measure and record the resistance of each pressure sensor in the pad under different pressures. The data collector scans and collects the dynamic resistance data of each pressure sensor in the pad, and transmits the collected data measured from the pressure sensor array to the analog-to-digital converter and the data transmitter. The pressure distribution data processor 300 receives data from the data transmitter of the data collector 200 and calculates, dynamically displaying the pressure distribution record of the object interacting with the pressure sensing pad 100. Specifically, a graphical user interface can be provided, which displays the pressure distribution of the measured object over time. Static images can be stored in a conventional image format file (e.g., JPEG format for static images, MPEG for moving images) or in the original pressure data format (e.g., .csv format). Colors can visually represent the pressure distribution in a color bar (e.g., see Figure 8 ), and the two-dimensional display of the pressure distribution provides a graphical representation. These two-dimensional images collected over time show the dynamic changes in the contact surface pressure.

[0045] The following examples show non-limiting embodiments of the present invention, applicable to specific applications; however, other embodiments can also be formed as described above.

[0046] Embodiment

[0047] Embodiment 1: 50×36 Pressure Sensor Array Pad

[0048] As Figure 2A shown, a 50×36 pressure sensor array pad was designed, including a set of upper surface wires based on silver electrode paste, silver electrode lower surface wires, and a piezoresistive dielectric double sandwich. A screen printing process was used to fabricate the pressure sensor array pad. The printing configuration is shown in Figure 2. On the upper surface of a polyimide film substrate with a thickness of 0.1 mm, 50 silver conductive electrodes were formed using the silver conductive paste described in US10745512 (the disclosure of which is incorporated herein by reference) with a wire width of 3 mm and a wire spacing of 2 mm, and cured at 120°C for 1 hour. After the electrode layer was dried, the piezoresistive dielectric composition was printed onto the electrode layer of the substrate and then cured again at 120°C for 1 hour. The thickness of the lower layer 130 / 140 is 0.11 mm. The composition of layers 140, 145 contains a phenoxy / 2-butoxyethyl acetate solution with carbon nanotubes (particles 142, 147), and a liquid rubber (e.g., hydroxyl-terminated nitrile rubber) / 2-butoxyethyl acetate solution. Micron-grade silica and zirconia particles were used as particles 148.

[0049] Similarly, a lower layer with a thickness of 0.05 - 0.11 mm is formed using the same process as that used for forming the upper layer. The upper and lower layers are laminated together along the perimeter using an adhesive, while ensuring that the directions of the electrodes on the upper and lower substrates are rows and columns, respectively. A single pressure sensor with a size of approximately 3 mm × 3 mm is formed by the intersection between the row conductive path and the column conductive path and the piezoresistive layer portion located at this intersection. A 50 × 36 flexible pressure sensor array pad with a thickness of 0.10 - 0.22 mm is obtained and tested in system 10.

[0050] In Example 1, the piezoresistive dielectric composition consists of 2 - 10 wt% carbon nanotubes, 70 - 90 wt% of a 30 wt% phenoxy resin / 2 - butoxyethyl acetate solution, 5 - 20 wt% of a 48 wt% liquid rubber (such as hydroxyl - terminated nitrile rubber / 2 - butoxyethyl acetate solution), 1 - 5 wt% of micron - sized SiO2 and ZrO2 particles, and 0.2 - 0.6 wt% of a leveling agent. This piezoresistive dielectric composition is a fluid slurry with a viscosity of 8000 - 11000 cps.

[0051] More specifically, the piezoresistive dielectric composition is prepared as follows: 30 wt% of phenoxy resin is dissolved in 2 - butoxyethyl acetate to produce solution A; 48 wt% of rubber is dissolved in another container of 2 - butoxyethyl acetate to produce solution B. The two solutions are mixed by stirring (A:B = 80 wt%:80 wt%), then 2 wt% of carbon nanotubes, 1 wt% of micron - sized SiO2 and ZrO2 particles, and 0.3 wt% of a leveling agent are added to the previous mixture and dispersed under vigorous stirring. Finally, a black fluid slurry for printing is obtained. The fabricated pressure sensing pads are shown in Figure 4 while the sensing pads of other sizes are shown in Figure 6

[0052] Example 2: Pressure Sensor System

[0053] The 50 × 36 pressure sensor array pad of Example 1 is assembled with a data collector ( Figure 4 ) and connected to a data processor 300 through a USB port to form a Figure 5 pressure distribution monitoring system 10. This system is used to measure the dynamic pressure distribution on the surface of pad 10, which is a 2 - D high - resolution color image displayed on the graphical user interface. Initially, Figure 5 the weights shown in

[0054] Figure 7A ​Describes the test results of the conductivity and pressure correlation of a single pressure sensor in the pad. The results show that the linear sensing range of the pressure pad is 0 - 3000 kPa. Figure 7B Demonstrates the durability of the pressure sensor array in 2,000,000 repeated pressure tests, with a sensitivity greater than 0.01 kPa -1 to achieve a change of less than 10% compared to the initial pressure measurement.

[0055] Example 3: Mapping Results

[0056] Figure 8 Shows the 2-D image output of the pressure distribution mapping of the pressure sensing pad under low-pressure conditions. When four depicted light weights (10 g - 200 g) are placed on the pressure sensing pad, a clear two-dimensional pressure distribution color image is output. The image also clearly shows the different surface flatness of each weight. Importantly, this type of pressure sensing pad can be used to measure the surface flatness of manufactured products, such as batteries like coin cells, which usually require a flat surface for proper electrical contact with devices.

[0057] Example 4: Dynamic Pressure Distribution Mapping

[0058] Figure 9 Shows the 2-D image output of the pressure distribution mapping of the pressure sensing pad under higher pressure conditions. When people of different weights wearing different shoes stand on the pressure sensing pad, a clear two-dimensional pressure distribution color image is output; the image can be recorded over time to generate pressure distribution patterns during walking, running, standing, and jumping, in order to analyze gait, foot structure defects, and injuries, so as to take corrective orthopedic measures, because the image clearly reflects the contact caused by the foot structure of the shoe wearer. It can further be used in the development of products such as insoles and shoe soles.

[0059] The above description of the present invention is for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations will be obvious to those skilled in the art.

[0060] The selected and described embodiments are intended to best explain the principles of the invention and its practical applications, so that other technicians in the technical field can understand the various embodiments of the invention and the various modifications suitable for specific purposes.

[0061] As used herein, the terms "substantially", "essentially", "about", and "approximately" are used to describe and account for a small variation. When used in connection with an event or circumstance, the term can refer to instances where the event or circumstance occurs exactly as well as instances where it occurs approximately. For example, when used in connection with a numerical value, these terms can encompass a variation range of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.

[0062] As used herein, the singular terms "a", "an", and "the" can include plural referents unless the context clearly dictates otherwise. In the description of some embodiments, a component provided "on" or "upon" another component can include instances where the former component is directly on the latter component (e.g., in physical contact with the latter component), as well as instances where one or more intervening components are located between the former component and the latter component.

[0063] Although the present invention has been described and illustrated with specific embodiments, such description and illustration are not limiting. Those skilled in the art will appreciate that various changes can be made and equivalents can be substituted without departing from the true spirit and scope of the invention as defined by the appended claims. The drawings are not necessarily to scale. Due to manufacturing processes and tolerances, there may be differences between the processes presented in the present invention and the actual devices. There may be other embodiments of the present disclosure that are not specifically shown. The specification and drawings are to be regarded as illustrative rather than restrictive, and may be modified to adapt a particular situation, material, composition of matter, method, or process to the purpose, spirit, and scope of the invention. All such modifications fall within the scope of the appended claims. Although the methods disclosed in the present invention have been described with reference to specific operations performed in a particular order, it should be understood that these operations can be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the present invention. Accordingly, the order and grouping of operations are not limited unless specifically stated herein.

Claims

1. A flexible planar pad system for pressure distribution monitoring, characterized in that, The system includes: A flexible planar pad, comprising: A first electrode layer; A first piezoelectric composite dielectric layer; A second piezoelectric composite dielectric layer facing the first piezoelectric composite dielectric layer; A second electrode layer located below the second piezoelectric composite dielectric layer, wherein the first piezoelectric composite dielectric layer and the second piezoelectric composite dielectric layer include: An elastomeric matrix having a first set of conductive particles embedded therein, the first set of conductive particles being selected from one or more of carbon nanotubes, graphite particles, carbon fibers, carbon spheres, activated carbon, acetylene black, semiconductors, metals, or graphene, and the content of the conductive particles being 2% to 10% by weight; Dielectric particles selected from one or more of silica, zirconia, alumina, boron nitride, aluminum nitride, silicon nitride, zinc oxide, silicon carbide, titanium dioxide, or calcium carbonate, and the content of the dielectric particles being 1% to 5% by weight; wherein the relative sizes of the particles in the first set of conductive particles and the dielectric particles are configured such that the interface between the piezoelectric composite dielectric layer and the electrode layer presents a micro-rough surface, such that the contact area at a low pressure load of 50 kPa or less is 0 - 10% of the layer surface area and the contact area generated at a high pressure load of 50 - 3000 kPa is 10 - 100% of the layer surface area, such that the total pressure detection range of the pressure distribution monitoring flexible planar pad system is 0 - 3000 kPa; A data collector for collecting pressure signals from the flexible planar pad; A pressure distribution data processor for receiving calculations of data from the data collector and creating a two-dimensional pressure distribution map from the flexible planar pad.

2. The pressure distribution monitoring flexible planar pad system according to claim 1, wherein the first electrode layer and the second electrode layer are each formed on a substrate having a thickness of 50 to 100 microns.

3. The pressure distribution monitoring flexible planar pad system according to claim 2, wherein the substrate is selected from polyethylene terephthalate or polyimide.

4. The pressure distribution monitoring flexible planar pad system according to claim 2, wherein the first electrode layer and the second electrode layer include screen-printed circuits, and the screen-printed circuits include electrode conductive particles.

5. The pressure distribution monitoring flexible planar pad system according to claim 4, wherein the electrode conductive particles are selected from one or more of silver, copper, or aluminum.

6. The pressure distribution monitoring flexible planar pad system according to claim 1, wherein the data collector includes a resistor, a signal amplifier, an analog-to-digital converter, and a data transmitter, and the resistor is used to measure and record the resistance of each pressure sensor in the flexible planar pad at different pressures.

7. The pressure distribution monitoring flexible planar pad system according to claim 1, wherein the pressure distribution data processor provides a static or dynamic two-dimensional pressure distribution pattern of the applied pressure.

8. The pressure distribution monitoring flexible planar pad system according to claim 1, wherein the piezoelectric composite dielectric layer includes a second set of conductive particles different from the first set of electrode conductive particles.

9. The pressure distribution monitoring flexible planar pad system according to claim 7, wherein the second group of conductive particles is selected from one or more of carbon nanotubes, graphite particles, carbon fibers, carbon spheres, activated carbon, acetylene black, semiconductors, metals, or graphene.

10. The pressure distribution monitoring flexible planar pad system according to claim 1, wherein the elastomeric matrix comprises nitrile rubber, silicone-based polymer, butyl rubber, polyurethane elastomer, bromobutyl rubber, chlorobutyl rubber, polyurethane, natural rubber, polyisoprene rubber, polybutadiene rubber, ethylene-propylene rubber, polysulfide, ethylene-propylene-diene rubber, poly(styrene-butadiene) rubber, poly-isoprene-co-butadiene rubber, styrene-isoprene-butadiene rubber, or a combination thereof.

11. A printable flexible planar pressure sensing pad, characterized in that, Comprising: A printable first electrode layer; A printable first piezoelectric composite dielectric layer; A printable second piezoelectric composite dielectric layer facing the printable first piezoelectric composite dielectric layer; A printable second electrode layer located below the printable second piezoelectric composite dielectric layer, wherein the printable first piezoelectric composite dielectric layer and the printable second piezoelectric composite dielectric layer comprise: The total thickness of the flexible planar pressure sensing pad is less than 0.30 mm; An elastomeric matrix having a second group of conductive particles embedded therein, the conductive particles being selected from one or more of carbon nanotubes, graphite particles, carbon fibers, carbon spheres, activated carbon, acetylene black, semiconductors, metals, or graphene, the content of the conductive particles being 2% to 10% by weight and the particle size being 0.5 to 1 micron; Dielectric particles selected from one or more of silica, zirconia, alumina, boron nitride, aluminum nitride, silicon nitride, zinc oxide, silicon carbide, titanium dioxide, or calcium carbonate, the content of the dielectric particles being 1% to 5% by weight; Wherein the relative sizes of the conductive particles and the dielectric particles are configured such that the interface between the piezoelectric composite dielectric layer and the electrode layer presents a micro-rough surface, such that the contact area at a low pressure load of 50 kPa or less is 0 - 10% of the layer surface area and the contact area generated at a high pressure load of 50 - 3000 kPa is 10 - 100% of the layer surface area, such that the total pressure detection range of the pressure distribution monitoring flexible planar pad system is 0 - 3000 kPa.

12. The printable flexible planar pressure sensing pad according to claim 11, wherein the first electrode layer and the second electrode layer are each formed on a substrate having a thickness of 50 to 100 microns.

13. The printable flexible planar pressure sensing pad according to claim 12, wherein the substrate is selected from polyethylene terephthalate or polyimide.

14. The printable flexible planar pressure sensing pad according to claim 11, wherein the first electrode layer and the second electrode layer comprise screen printing lines, the screen printing lines comprising a first group of electrode conductive particles.

15. The printable flexible planar pressure sensing pad according to claim 14, wherein the first group of electrode conductive particles is selected from one or more of silver, copper, or aluminum.

16. The printable flexible planar pressure sensing pad according to claim 11, wherein the piezoelectric composite dielectric layer comprises a second group of conductive particles different from the first group of electrode conductive particles.

17. The printable flexible planar pressure sensing pad according to claim 11, wherein the second group of conductive particles is selected from one or more of carbon nanotubes, graphite particles, carbon fibers, carbon spheres, activated carbon, acetylene black, semiconductors, metals, or graphene.

18. The printable flexible planar pressure sensing pad according to claim 10, wherein the elastomeric matrix comprises nitrile rubber, silicone-based polymer, butyl rubber, polyurethane elastomer bromobutyl rubber, chlorobutyl rubber, polyurethane, natural rubber, polyisoprene rubber, polybutadiene rubber, ethylene-propylene rubber, polysulfide, ethylene-propylene-diene rubber, poly(styrene-butadiene) rubber, poly-isoprene-co-butadiene rubber, styrene-isoprene-butadiene rubber, or a combination thereof.

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