Laminated three-dimensional pressure sensing equipment

Abstract

A laminated three-dimensional pressure sensing device disclosed by the present invention comprises a force sensitive part, an insulating part and an electrode, the force sensitive part and the insulating part are sheet-shaped, the force sensitive part is formed by stacking at least two flexible piezoresistive conductive layers, the insulating part is arranged between every two flexible piezoresistive conductive layers, and the electrode is arranged between the insulating part and the force sensitive part. The insulating part is made of an insulating elastic deformable material, a plurality of electrodes are arranged on the periphery of each flexible piezoresistive conducting layer, and the electrodes are used for leading out resistance distribution data in each flexible piezoresistive conducting layer through wires. On the basis, the laminated three-dimensional pressure sensing equipment has the characteristics that the structure is simple, the whole body is made of a full-flexible material, electrodes and wires only need to be arranged on the periphery, no wire is needed in the interior, good attachment can be achieved according to the shape of a curved surface, a flat touch interface can be achieved, and the application range is wide. And the three-dimensional pressure measuring range is very wide, and the sensitivity is higher, so that the sensitivity and the measuring range of three-dimensional force measurement are improved.

Description

Technical Field

[0001] Embodiments of the present invention relate to, but are not limited to, the field of pressure sensing technology, and in particular, to a stacked three-dimensional pressure sensing device. Background Art

[0002] At present, with the booming development of emerging technology fields such as the Internet of Things, the metaverse, smart homes and furniture, humanoid and flexible robots, the demand for pressure measurement technology for human-computer interaction interfaces is becoming increasingly urgent. These industries expect the device interface to accurately capture the pressure changes of the user or the environmental interface to achieve a more natural, safe, and intelligent interaction experience. For example, if a humanoid robot can have an electronic skin, that is, a tactile function similar to the human skin, its interaction ability with the environment and humans will be greatly improved. Existing flexible tactile sensors, such as linear piezoresistive and array tactile sensors, have many drawbacks. Their manufacturing processes and wiring are complex, the costs are high, and the sensing functions are relatively single. Moreover, when detecting the touch position, the intensity of the force, and the shape, such sensors often cannot achieve multi-dimensional pressure detection, and thus the application range is limited.

[0003] Traditional pressure monitoring technology uses a pressure sensor matrix for measurement, which has very obvious limitations. Since each sensor unit has to be connected by an independent wire, the number of wires in the sensor matrix is extremely large, which not only makes the device more complex and the cost skyrocket, but also has a negative impact on the flexibility, stretchability, and ability to conform to complex surfaces of the device. If each sensor unit in the pressure sensor matrix is upgraded to a three-dimensional pressure sensor, the number of wires for each sensor will soar from two to six, eight, or even more, and the device complexity and cost problems will become more serious, greatly limiting the flexibility and application scenarios of the device. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail in this document. This overview is not intended to limit the scope of protection of the claims.

[0005] Embodiments of the present invention provide a stacked three-dimensional pressure sensing device, which has the characteristics of simple structure and all-flexible materials throughout. Only electrodes and wires need to be arranged around it, and no wires are required inside. Moreover, it can achieve good fitting for curved surfaces, can realize a flat touch interface, and has a very wide three-dimensional pressure measurement range and higher sensitivity, thereby improving the sensitivity and range of three-dimensional force measurement.

[0006] An embodiment of the present invention provides a stacked three-dimensional pressure sensing device, including: a force-sensitive part, an insulating part, and electrodes. The force-sensitive part and the insulating part are in sheet form. The force-sensitive part is stacked by at least two layers of flexible piezoresistive conductive layers, and the insulating part is disposed between every two layers of the flexible piezoresistive conductive layers. The insulating part is made of an insulating, elastic and deformable material. A plurality of the electrodes are arranged around the periphery of each layer of the flexible piezoresistive conductive layer. The electrodes are used to lead out the resistance distribution data inside each layer of the flexible piezoresistive conductive layer through wires, so that the backend circuit device can respectively and real-time read the resistance distribution data inside each layer of the flexible piezoresistive conductive layer by means of electrical impedance scanning imaging, calculate the pressure distribution data at each position on the surface of each layer of the flexible piezoresistive conductive layer at each moment according to the resistance distribution data, and then calculate each layer of the pressure distribution data to obtain the three-dimensional pressure distribution information received on the surface of the stacked three-dimensional pressure sensing device. Among them, the resistance distribution data includes normal pressure data and shear pressure data. The normal pressure data at the pressure-receiving positions on the surfaces of all the flexible piezoresistive conductive layers is obtained through the pressure distribution data of the first layer of the flexible piezoresistive conductive layer, and the shear pressure data is obtained through the differential calculation of the pressure distribution data of multiple layers of the flexible piezoresistive conductive layers.

[0007] In some embodiments, the force-sensitive part is made of a flexible conductive material sheet, film or fabric. Each layer of the flexible piezoresistive conductive layer has a solid planar layer structure, or a planar network structure, or some regions in the planar network structure contain holes.

[0008] In some embodiments, the insulating part uses an insulating material with elasticity and flexibility. The insulating part is in an overall sheet form or flat form, and the thickness of the insulating part is maintained at the millimeter or micron order of magnitude.

[0009] In some embodiments, the electrodes are also arranged in a preset area of each layer of the flexible piezoresistive conductive layer according to a preset density.

[0010] In some embodiments, the flexible piezoresistive conductive layer uses a conductive composite material, or a conductor or semiconductor material rich in conductive ions, or a piezoresistive conductive fiber aggregate, or an elastomer containing an intrinsically conductive polymer.

[0011] In some embodiments, the insulating part uses a polyurethane film or a silicone insulating sheet.

[0012] In some embodiments, the electrodes use a coating or plating of a good conductor, or a micro-nano structure material, or a carbon-based conductive material, or a metal-plated fiber material, or an intrinsically conductive polymer, or a liquid metal.

[0013] In some embodiments, the insulating portion is disposed between two layers of the flexible piezoresistive conductive layers by a bonding method, and the bonding method includes any one of hot pressing, adhesion, and roll pressing.

[0014] In some embodiments, the surface of the force-sensitive portion is covered with a packaging layer, and the packaging material of the packaging layer is a flexible polymer elastomer with a low elastic modulus.

[0015] In some embodiments, between the force-sensitive portion and the insulating portion, a multi-layer weaving or three-dimensional weaving method is adopted to prepare an upper flexible piezoresistive conductive layer, a lower flexible piezoresistive conductive layer, and an intermediate insulating layer having a piezoresistive effect. The upper flexible piezoresistive conductive layer, the lower flexible piezoresistive conductive layer, and the intermediate insulating layer are connected by yarns between layers. Conductive wires are embroidered around the circumferences of the upper flexible piezoresistive conductive layer and the lower flexible piezoresistive conductive layer as required, and the conductive wires are any one of stainless steel fibers, silver-plated nylon yarns, copper-nickel-plated nylon yarns, and micron-level pure copper filaments; alternatively, between the force-sensitive portion and the insulating portion, a sewing method is adopted to sew together the upper flexible piezoresistive conductive layer, the lower flexible piezoresistive conductive layer, and the intermediate insulating layer, and silver-plated nylon wires are sewn at designated positions around each flexible piezoresistive conductive layer.

[0016] A stacked three-dimensional pressure sensing device provided by an embodiment of the present invention includes: a force-sensitive part, an insulating part, and electrodes. The force-sensitive part and the insulating part are in sheet form. The force-sensitive part is stacked by at least two layers of flexible piezoresistive conductive layers. An insulating part is arranged between every two layers of flexible piezoresistive conductive layers. The insulating part is made of an insulating elastic deformable material. A plurality of electrodes are arranged around each layer of flexible piezoresistive conductive layer. The electrodes are used to lead out the resistance distribution data inside each layer of flexible piezoresistive conductive layer through wires, so that the backend circuit device can respectively and real-time read the resistance distribution data inside each layer of flexible piezoresistive conductive layer in the way of electrical impedance scanning imaging, calculate the pressure distribution data at each position on the surface of each layer of flexible piezoresistive conductive layer at each moment according to the resistance distribution data, and then calculate each layer of pressure distribution data to obtain the three-dimensional pressure distribution information received on the surface of the stacked three-dimensional pressure sensing device. Among them, the resistance distribution data includes normal pressure data and shear pressure data. The normal pressure data at the pressure-receiving positions on the surfaces of all flexible piezoresistive conductive layers is obtained through the pressure distribution data of the first-layer flexible piezoresistive conductive layer, and the shear pressure data is obtained through the differential calculation of the pressure distribution data of multiple layers of flexible piezoresistive conductive layers. In the embodiment of the present invention, at least two layers of flexible piezoresistive conductive materials are used to form the force-sensitive part. This conductive material has piezoresistive characteristics, that is, the resistance changes regularly when being squeezed or stretched. Therefore, this conductive material is made into a sheet to construct the planar data of the pressure distribution. Stacking two or more sheets of conductive materials, and adding a sheet of insulating elastic material between every two layers of conductive materials can form a stacked three-dimensional pressure sensing structure. A plurality of electrodes are arranged around each layer of conductive material, and the electrodes are used to connect wires to lead out signals. By using the method of electrical impedance scanning imaging to respectively and real-time read the resistance distribution data inside each layer of flexible conductive material, the pressure distribution at each position of each force-sensitive plane can be known. Then, the normal pressure at all pressing positions is mainly obtained through the first-layer piezoresistive conductive material, while the shear pressure data is obtained through the differential calculation of the pressure data of multiple layers of piezoresistive conductive materials, so as to realize a stacked three-dimensional pressure touch sensing device that is internally electrode-free or only has partial electrodes, fully flexible, based on electrical impedance scanning imaging, and capable of multi-point simultaneous detection, that is, functionally equivalent to a three-dimensional pressure sensor matrix. Based on this, the stacked three-dimensional pressure sensing device of the present invention has the advantages of simple structure and fully flexible material throughout the body. Only electrodes and wires need to be arranged around, and no wires are required inside. And it can achieve good fitting for curved surfaces, can realize a flat touch interface, and has a very wide three-dimensional pressure measurement range and higher sensitivity, thereby improving the sensitivity and range of three-dimensional force measurement.

[0017] Other features and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention can be realized and attained by the structure particularly pointed out in the specification, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings are used to provide a further understanding of the technical solution of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention, and do not constitute a limitation to the technical solution of the present invention.

[0019] Figure 1A FIG. is a top view structural schematic diagram of a stacked three-dimensional pressure sensing device provided by an embodiment of the present invention;

[0020] Figure 1B is Figure 1A a sectional view structural schematic diagram along the dotted line position in the top view;

[0021] Figure 2 FIG. is a sectional view structural schematic diagram of a stacked three-dimensional pressure sensing device provided by another embodiment of the present invention;

[0022] Figure 3 FIG. is a sectional view structural schematic diagram of a stacked three-dimensional pressure sensing device provided by another embodiment of the present invention;

[0023] Figure 4A FIG. is a sectional view structural schematic diagram of a stacked three-dimensional pressure sensing device provided by another embodiment of the present invention;

[0024] Figure 4B is Figure 4A a structural schematic diagram of the insulating layer in the figure;

[0025] Figure 5 FIG. is a sectional view structural schematic diagram of a stacked three-dimensional pressure sensing device provided by another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] It should be understood that in the description of the embodiments of the present invention, the meaning of "a plurality of (or multiple)" is more than two. "Greater than", "less than", "exceeding", etc. are understood not to include the present number, and "above", "below", "within", etc. are understood to include the present number. If there is a description of "first", "second", etc., it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0028] At present, with the booming development of emerging technology fields such as the Internet of Things, the metaverse, smart homes and furniture, humanoid and flexible robots, the demand for pressure measurement technology of human-computer interaction interfaces is becoming increasingly urgent. These industries expect that the device interface can accurately capture the pressure changes of the user or the environmental interface to achieve a more natural, safe and intelligent interaction experience. For example, if a humanoid robot can have an electronic skin, that is, a tactile function similar to that of the human skin, its interaction ability with the environment and humans will be greatly improved. Existing flexible tactile sensors, such as linear piezoresistive and array tactile sensors, have many drawbacks. The manufacturing process and wiring are complicated, the cost remains high, and the sensing function is relatively single. Moreover, when detecting the touch position, the intensity of the force and the shape, such sensors often cannot achieve multi-dimensional pressure detection, and thus the application range is limited.

[0029] The traditional pressure monitoring technology uses a pressure sensor matrix for measurement, which has very obvious limitations. Since each sensor unit has to be connected by an independent wire, the number of wires in the sensor matrix is extremely large, which not only makes the device more complex and the cost skyrocket, but also has a negative impact on the flexibility, stretchability of the device and the ability to fit complex surfaces. If each sensor unit in the pressure sensor matrix is upgraded to a three-dimensional pressure sensor, the number of wires per sensor will soar from two to six, eight or even more, and the device complexity and cost problems will become more serious, greatly limiting the flexibility and application scenarios of the device.

[0030] To solve the above technical problems, an embodiment of the present invention provides a stacked three-dimensional pressure sensing device, including: a force-sensitive part, an insulating part, and electrodes. The force-sensitive part and the insulating part are in sheet form. The force-sensitive part is formed by stacking at least two layers of flexible piezoresistive conductive layers. An insulating part is disposed between every two layers of flexible piezoresistive conductive layers. The insulating part is made of an insulating elastic deformable material. A plurality of electrodes are arranged around each layer of flexible piezoresistive conductive layer. The electrodes are used to lead out the resistance distribution data inside each layer of flexible piezoresistive conductive layer through wires, so that the backend circuit device can respectively and real-time read the resistance distribution data inside each layer of flexible piezoresistive conductive layer by means of electrical impedance scanning imaging, calculate the pressure distribution data at each position on the surface of each layer of flexible piezoresistive conductive layer at each moment according to the resistance distribution data, and then calculate each layer of pressure distribution data to obtain the three-dimensional pressure distribution information received on the surface of the stacked three-dimensional pressure sensing device. Among them, the resistance distribution data includes normal pressure data and shear pressure data. The normal pressure data at the pressed positions on the surfaces of all flexible piezoresistive conductive layers is obtained through the pressure distribution data of the first layer of flexible piezoresistive conductive layer, and the shear pressure data is obtained through the differential calculation of the pressure distribution data of multiple layers of flexible piezoresistive conductive layers. In the embodiment of the present invention, at least two layers of flexible piezoresistive conductive materials are used to form the force-sensitive part. This conductive material has piezoresistive characteristics, that is, the resistance changes regularly when being squeezed or stretched. Therefore, this conductive material is made into a sheet to construct the planar data of the pressure distribution. Stacking two or more sheets of conductive materials, and adding a sheet of insulating elastic material between every two layers of conductive materials can form a stacked three-dimensional pressure sensing structure. A plurality of electrodes are arranged around each layer of conductive material, and the electrodes are used to connect wires to lead out signals. By using the method of electrical impedance scanning imaging to respectively and real-time read the resistance distribution data inside each layer of flexible conductive material, the pressure distribution at each position of each force-sensitive plane can be known. Then, the normal pressure at all pressed positions is mainly obtained through the first layer of piezoresistive conductive material, while the shear pressure data is obtained through the differential calculation of the pressure data of multiple layers of piezoresistive conductive materials, so as to realize a stacked three-dimensional pressure touch sensing device that is internally electrode-free or has only partial electrodes, fully flexible, based on electrical impedance scanning imaging, and capable of multi-point simultaneous detection, that is, functionally equivalent to a three-dimensional pressure sensor matrix. Based on this, the stacked three-dimensional pressure sensing device of the present invention has the advantages of simple structure and fully flexible material throughout the body. Only electrodes and wires need to be arranged around, and no wires are required inside. And it can achieve good fitting for curved surfaces, can realize a flat touch interface, and has a very wide three-dimensional pressure measurement range and higher sensitivity, thereby improving the sensitivity and range of three-dimensional force measurement.

[0031] The stacked three-dimensional pressure sensing device of the present invention is composed of three parts, including: a force-sensitive part, an insulating part, and electrodes.

[0032] It can be understood that the force-sensitive part includes at least two layers of flexible piezoresistive conductive layers. The flexible piezoresistive conductive layers are made of piezoresistive conductive materials. Electrodes are arranged around each layer of the flexible piezoresistive conductive layer. The resistance distribution of each layer of the flexible piezoresistive conductive layer is monitored in real time by means of electrical impedance tomography, so as to respectively deduce the pressure distribution information at each position on the surface of the flexible piezoresistive conductive layer of different sensing layers of the device at each moment. Then, the data of each layer of the flexible piezoresistive conductive layer are calculated to obtain the three-dimensional pressure distribution information received by the device as a whole.

[0033] It can be understood that the force-sensitive part and the insulating part of the present invention are in sheet form and can truly simulate the flat state of the human skin surface. Therefore, good fitting can be achieved for a curved surface shape, and a pure flat touch interface can be realized.

[0034] It can be understood that the present invention measures three-dimensional force through at least two layers of piezoresistive conductive materials. In this way, when there is a shear force, since the shear force is applied in the horizontal direction, it will cause a horizontal displacement at the stressed position of each layer of material. Obviously, the horizontal displacement of the upper layer of material is the largest, the second layer of material is the second largest, and the third layer is even smaller. This is because an elastic material with a certain thickness can disperse the surface stress. Therefore, the projection area of the three-dimensional force transmitted to the lower layer expands, the projected stress attenuates, and the horizontal displacement of the projection slows down. That is, it causes a dislocation of the pressure in each layer. Therefore, the mapping of the three-dimensional force will have different two-dimensional topological graphs in the piezoresistive materials of different layers. By comparing the differences in the piezoresistive data distribution between different layers, the magnitude and direction of the three-dimensional pressure can be deduced inversely. Based on this method, to a certain extent, it is similar to computer tomography technology. First, the mapping of the three-dimensional force information on each layer is captured layer by layer, and then the data of all layers are combined and calculated to reconstruct the entire three-dimensional pressure distribution data.

[0035] It should be noted that for the calibration of the stacked three-dimensional pressure sensing device, due to individual differences in materials and slight differences in the assembly process, there will be deviations in the initial measurement of the device. Using a standard pressure generating device, known pressures are applied to the device from multiple pressure angles and different pressure amplitudes, and the output data of the device are collected and compared to accurately adjust the parameters of the backend circuit, so that the stacked three-dimensional pressure sensing device can accurately feedback the real pressure situation.

[0036] It can be understood that the force-sensitive part is made of flexible conductive material sheets, films or fabrics. Each layer of conductive material presents a solid planar layer structure or a planar network structure, that is, some regions contain holes. Such flexible conductive materials have a characteristic that when subjected to pressure, the resistance at the corresponding position will change, which is the piezoresistive characteristic. In addition, even if it is not a piezoresistive material in the conventional sense, it doesn't matter as long as the resistance at the stressed position can show regular and repeatable changes under the pressure state.

[0037] It is understandable that the insulating part is made of an insulating material with excellent elasticity and flexibility. This insulating part is in a sheet-like form / flattened form as a whole, and its thickness is preferably maintained at the millimeter or micron order of magnitude to ensure both effective isolation and not excessive space occupation. It has uniform texture and can also be a planar network structure, that is, some areas contain holes, but it is necessary to ensure that each area can stably play the insulating effect and prevent accidental conduction between the conductive materials of the force-sensitive parts of different layers. The sheet-like insulating material can be closely combined with the upper and lower flexible conductive materials. During various deformation processes such as compression, bending, and torsion of the device, the insulating material will not be easily damaged, building an insulating barrier for the stable operation of the entire sensing device. Therefore, whether it is static placement or dynamic use scenarios, the insulating part can always maintain good insulating performance.

[0038] It is understandable that the electrodes can be evenly arranged around each force-sensitive layer. The electrodes can be evenly spaced, or the density of the electrodes can be adjusted according to the requirements of resolution and accuracy at different positions. In addition to arranging electrodes around the device, electrodes can also be selectively added at different positions under the force-sensitive material to significantly improve the position accuracy and pressure accuracy during sensor measurement. Under the same backend processing circuit and algorithm framework, the electrode layout is like a "precision regulating valve". The more electrodes and the more optimized the distribution, the richer the information obtained by electrical impedance tomography, and the normal pressure measurement accuracy, shear force resolution accuracy, and position recognition accuracy are improved simultaneously.

[0039] It is understandable that the material of the force-sensitive part is preferably a conductive composite material. To enhance the piezoresistive characteristics, the resistance of this kind of conductive material should be in the semiconductor range. The force-sensitive part is preferably a piezoresistive rubber material, a graphite / silicone composite material, a multi-walled carbon nanotube / polyurethane composite material, etc.; the material of the force-sensitive part can also be a conductor or semiconductor material with certain fluidity such as gallium-indium alloy, or a gel and liquid rich in conductive ions; a conductive fiber aggregate with piezoresistive characteristics can also be used as the material of the force-sensitive part, such as pure cotton knitted fabric with graphene and carbon nanotubes attached to the surface, or spandex warp-knitted mesh completely coated with carbon black / polyurethane composite material prepared by screen printing technology; in addition, an elastomer containing an intrinsically conductive polymer, for example, a composite film of polypyrrole and polyurethane, is also within the optional range. In short, as long as it is a sheet-like material with elasticity and continuous conductivity, whether it is sheet-like mesoporous or sheet-like solid, as long as the resistance at the compressed position changes repeatedly and regularly when compressed, it meets the usage conditions of the force-sensitive part of the present invention. The force-sensitive part can be designed as a flat planar structure or with protrusions according to requirements.

[0040] It is understandable that the materials for the insulating part focus on substances with excellent flexibility and outstanding insulating performance. Commonly used ones include polyurethane films or silicone insulating sheets, etc. They are all very soft in texture, have good elasticity and strong plasticity, and can easily adapt to device structures of different shapes, ensuring a tight fit and not giving the conductive part a chance to "cross over". The materials for the insulating part are mostly in the form of thin sheets, and the thickness is accurately controlled within a range that can prevent leakage and short circuits without hindering the compact assembly of the entire device. It is seamlessly connected to the adjacent force-sensitive part, ensuring that the insulating effect remains consistent and stable and durable whether the device encounters daily minor vibrations or frequent deformations during long-term use.

[0041] It is understandable that the materials for the electrode part can be coatings, deposits of good conductors such as gold, silver, copper, etc., or micro-nano structure materials (such as silver nanowire / silicone composites, such as silver powder particle / epoxy resin composites), or carbon-based conductive materials (such as carbon fibers, etc.), or metal-coated fiber materials, or also intrinsic conductive polymers (such as poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, etc.) or liquid metals (such as gallium indium alloy, etc.).

[0042] It is understandable that placing an insulating flexible film between two layers of flexible conductive materials can ensure accurate fitting, no wrinkles or air bubbles remaining through methods such as hot pressing, bonding, roll pressing, etc. The electrode layer can be arranged before or after fitting. The electrode layer adopts high-precision processes such as screen printing and chemical vapor deposition, and attaches electrode materials at designated electrode sites according to different position requirements; or uses simple processes such as applying silver paste resin and embroidering electrodes with silver-plated nylon yarn. After completing the electrode attachment, the connecting wire is connected to the backend circuit. For some special designs, if an additional mechanical conduction strengthening structure needs to be added, although there is no separate conduction part, a similar function can be achieved by means of external accessories. For example, select silicone or rubber blocks with moderate hardness and a shape that fits, and use a dispensing machine to adhere them to the corresponding sites on the surface of the force-sensitive part; or use 3D printing to customize a three-dimensional structure and attach it to the key stress points below the force-sensitive material to assist in more efficiently transmitting the pressure to the force-sensitive part, and then connect the electrodes and wires after assembly.

[0043] It is understandable that optionally, a packaging layer is covered on the upper and lower surfaces of the device, especially in the key areas where the force-sensitive part may contact the pressure source. It is preferred to select a flexible high-polymer elastomer with a low elastic modulus, which can not only protect the internal flexible conductive materials and insulating films from moisture and dust erosion, but also evenly disperse the pressure at the moment of pressure contact, avoid local stress concentration from damaging the device, ensure the stable operation of the device, and maintain the measurement accuracy. It can also make the surface of the non-flat force-sensitive layer flat by using the packaging layer.

[0044] It can be understood that the three-way elasticity of the force-sensitive part and the insulating part lays the foundation for the adaptability of the device. The excellent three-way elasticity enables the device to break through the planar limitation and conform to spherical and irregular curved surfaces. For example, when it is attached to the joint part of a smart prosthetic limb, even if it is stretched and deformed, after calibration, the device can still capture complete and accurate three-dimensional pressure information, which greatly enriches the application scenarios. The piezoresistive property of the force-sensitive material is the key to sensitivity. Under the same conditions, the more significant the piezoresistive effect, the more sensitive the device is to detecting tiny pressures. At the same time, the size and stiffness of the force-sensitive part jointly affect the measurement range and sensitivity. A large size combined with high stiffness, although the stress concentration effect is strong and the sensitivity is improved, the upper limit of the measurable force is easily limited. The auxiliary conduction structures with different layouts will also change the pressure conduction effect to varying degrees in terms of quantity, distribution, and density, thereby adjusting the range and accuracy of three-dimensional force measurement.

[0045] It can be understood that in addition to using the polymer film or sheet material proposed in the above claims for preparation, fiber materials and textile processes can also be fully or partially used to process the laminated three-dimensional pressure sensing device. For example, multi-layer weaving and three-dimensional weaving can be used to prepare the upper force-sensitive layer, the lower force-sensitive layer, and the middle insulating layer with piezoresistive effect at one time. The layers are connected by yarns. Finally, wires are embroidered around the upper force-sensitive layer and the lower force-sensitive layer as required, preferably stainless steel fibers, silver-plated nylon yarns, copper-nickel-plated nylon yarns, and micron-scale pure copper filaments, etc. Or, by sewing, the upper piezoresistive fabric layer, the lower piezoresistive fabric layer, and the middle insulating fabric layer are sewn together, and silver-plated nylon wires are sewn at designated positions around each piezoresistive fabric layer.

[0046] Based on this, the stacked three-dimensional pressure sensing device of the present invention is mainly composed of elastic materials and is divided into three parts according to functions: a force-sensitive part, an insulating part, and electrodes. The force-sensitive part is made of a flexible conductive material with piezoresistive characteristics, that is, the resistance changes regularly when it is squeezed or stretched. Therefore, when this conductive material is made into a sheet (or called a film), it can be used to construct the planar data of the pressure distribution. Stack two or more sheets of conductive material, and add a sheet of insulating elastic material between every two sheets of conductive material to form a stacked three-dimensional pressure sensing structure. A plurality of electrodes are arranged around each sheet of conductive material, and the electrodes are used to connect wires to lead out signals. By using the method of electrical impedance scanning imaging to respectively and real-time read the resistance distribution data inside each layer of flexible conductive material, the pressure distribution at each position of each force-sensitive plane can be obtained. Then, the normal pressure at all pressing positions is mainly obtained through the first-layer piezoresistive conductive material, while the shear pressure data is obtained through the differential calculation of the pressure data of multiple layers of piezoresistive conductive materials, so as to realize a stacked three-dimensional pressure touch sensing device that is internally electrode-free or has only partial electrodes, fully flexible, based on electrical impedance scanning imaging, and capable of multi-point simultaneous detection, that is, functionally equivalent to a three-dimensional pressure sensor matrix.

[0047] In summary, the embodiment of the present invention provides a three-dimensional pressure sensing device with a simple structure, low cost, easy processing, fully flexible material, only requires electrodes and wires to be arranged around, can have no wires inside, and has a good fit for curved surfaces. It adopts a multi-layer stacked structure with a flat surface, can cover the measurement ranges of large pressure, medium pressure, and small pressure, and can detect three-dimensional pressure with high sensitivity.

[0048] The following further elaborates on the embodiment of the present invention in conjunction with the accompanying drawings.

[0049] Embodiment 1

[0050] Please refer to Figure 1A and Figure 1B, this embodiment provides a stacked flexible three-dimensional pressure sensing device. The device includes three parts: a force-sensitive part 1, an insulating part 2, and an electrode part 3. The force-sensitive part 1 uses silicone rubber filled with graphene and carbon nanotubes, and the filled conductive particles endow it with piezoresistive characteristics. When a certain part is pressed, the resistance of this part will change regularly accordingly. Two layers of such flexible conductive materials up and down are the key to the whole measurement. Under the action of external three-dimensional multi-point pressure, the resistance changes at different positions of them all carry the pressure information at this position, providing basic data support for subsequent calculation of the three-dimensional pressure distribution; The silicone rubber material with excellent flexibility and insulation is used as the insulating part 2, which is in a sheet shape as a whole, and the preferred thickness is in the millimeter level. By means of processes such as hot pressing, vacuum, and roll pressing, it is firmly placed between the upper and lower force-sensitive parts 1, which can not only ensure close fitting, eliminate gaps and bubbles, but also effectively prevent accidental conduction between the two conductive materials. Under various deformation conditions such as the device being pressed and bent, the insulating part 2 can always maintain a stable insulating effect to ensure that the measurement is not interfered; The electrode part 3 is made of a composite material of silver nanowires and silicone rubber. First, apply the silver nanowire ethanol dispersion liquid at the electrode position. After the ethanol volatilizes, add a small amount of silicone rubber to form. Thanks to the silicone rubber component, it can be tightly bonded to the force-sensitive part 1, and the silver nanowires therein also achieve a reliable electrical connection with the force-sensitive part 1. The electrodes are evenly arranged around the device. The electrode spacing can be evenly distributed to meet the basic measurement requirements, and can also be flexibly adjusted according to the accuracy requirements of different positions as needed.

[0051] During operation, due to the piezoresistive characteristics of the force-sensitive part 1, being pressed will cause different resistance changes in the upper and lower conductive materials respectively. By sequentially applying current to the electrodes around the device and simultaneously measuring the voltage distribution of the remaining electrodes, that is, using electrical impedance scanning imaging technology, the real-time distribution of the resistance of the two force-sensitive materials can be read in real time. By performing a difference calculation on the resistance distribution data corresponding to the two materials, the three-dimensional pressure distribution at each position on the upper plane of the device can be accurately deduced.

[0052] This device only arranges electrodes around it. Compared with the traditional three-dimensional pressure sensor matrix, the number of wires required is greatly reduced, and the dependence on stretchable wire technology when making an overall stretchable flexible device is avoided, with outstanding practicality. Moreover, this embodiment achieves real-time monitoring of three-dimensional pressure at multiple points in the plane. Compared with the position recognition function only available in inductive or capacitive pressure touchpads, and the single normal pressure measurement function of conventional electrical impedance scanning imaging, it can give the shear force distribution at multiple points, with remarkable innovation.

[0053] (1) The first variant of Embodiment 1:

[0054] Refer to Figure 2, based on the above device architecture, this embodiment also has an optional configuration: encapsulation layer 4. Using a casting process, a layer of silicone is evenly covered on the surface of the entire device, and a layer of silicone is also covered on the lower surface. After this treatment, the surface of the device becomes smooth and flat, and it can play the roles of insulation, aesthetics, and protection. In terms of material selection, it is preferable to use the same silicone material as the force-sensitive layer 1, or it is also possible to preferably use a silicone material with a lower elastic modulus than the force-sensitive layer 1 as the encapsulation layer 4. In this way, when an external pressure is applied to the surface of the encapsulated device, the normal pressure and transverse shear force borne by each position can be transmitted without hindrance, efficiently and accurately, maximizing the effectiveness and stability of pressure conduction and maintaining the accuracy of device measurement.

[0055] (2) The second variant of Embodiment 1:

[0056] Referring to Figure 2 , to achieve weak pressure measurement, the force-sensitive part 1 can also use a composite structure of polyurethane sponge and ionic liquid. Polyurethane sponge has a unique three-dimensional porous structure with rich and interconnected pores, providing a smooth channel for the movement of ions; the ionic liquid is filled in these pores. The ionic liquid is rich in various ions (such as cations and anions in imidazole-based ionic liquids) and has good conductivity itself. When subjected to an external pressure, the pores of the polyurethane sponge will deform, squeezing or stretching the ionic liquid therein, resulting in changes in the distribution density and movement path of ions, and thus causing a significant change in resistance. The overall elastic modulus of this composite structure is low, and it is sensitive to weak pressures. Even the slightest external touch can be accurately captured and converted into a measurable resistance signal. Matched with this force-sensitive part 1, the insulating part 2 also uses a polyurethane sponge structure, and the encapsulation layer 4 also uses polyurethane sponge. Such a stacked device can achieve the measurement of three-dimensional weak pressures.

[0057] Due to its unique structure and material application, this stacked flexible device of this embodiment variant shows its full advantages in the field of micro-pressure detection, and is especially suitable for scenarios with strict requirements for weak pressure perception such as micro-force monitoring during the assembly of high-precision electronic components and biological cell mechanics research, expanding the application scope of flexible three-dimensional pressure sensing devices.

[0058] Embodiment 2

[0059] Please refer to Figure 3, this embodiment provides a stacked flexible three-dimensional pressure sensing device with three force-sensitive layers. The device includes three parts: a force-sensitive part 1, an insulating part 2, and an electrode part 3. Different from Embodiment 1, the force-sensitive part 1 in this embodiment has a total of three layers, which can be called the upper force-sensitive part 1, the middle force-sensitive part 1, and the lower force-sensitive part 1 from top to bottom. The insulating part 2 has a total of two layers, which are called the first insulating layer and the second insulating layer from top to bottom. In this embodiment, the thickness and elastic modulus of the first insulating layer and the second insulating layer can be preferably adjusted. For example, the elastic modulus of the first insulating layer is 1 / 5 of the elastic modulus of the second insulating layer, and at the same time, the thickness of the first insulating layer is the same as that of the second insulating layer. In this way, the shear force applied to the surface of the upper force-sensitive part 1 is more likely to cause the slip of the upper force-sensitive part 1, and relatively less likely to cause the slip of the middle force-sensitive part 1. Therefore, the difference in the tangential pressure distribution data between the upper force-sensitive part 1 and the middle force-sensitive part 1 will be larger, while the difference in the tangential pressure distribution data between the middle force-sensitive part 1 and the lower force-sensitive part 1 will be smaller. The advantage of this is that it is easier to measure small shear forces between the upper and middle force-sensitive parts, and it is easier to measure large shear forces between the middle and lower force-sensitive parts. Through such a functional partition, the measurement range of the shear force of the entire device can be effectively increased, and the device can be sensitive to both small and large pressures and shear forces at the same time. Of course, in order to further expand the pressure measurement range of the device, there can be designs with more force-sensitive layers, which are all within the scope of this patent. At the same time, it should be pointed out that the materials of each force-sensitive part can also be adjusted according to needs, and it is not necessary to completely use the same materials and the same ratios. For example, for the measurement of small pressures, a force-sensitive part 1 with higher sensitivity is required, while for the measurement of large pressures, a force-sensitive part 1 with relatively lower sensitivity is required.

[0060] Embodiment 3

[0061] Please refer to Figure 4. This embodiment shows a multi-point supported stacked fully flexible three-dimensional pressure sensing device. Different from Embodiment 1, the middle insulating layer 12 adopts a discontinuous dot matrix arrangement. Each insulator unit shown in Figure 4 is a cylinder, connecting the upper and lower pressure-sensitive layers. Compared with the new material, the discontinuous dot matrix insulator arrangement can effectively reduce the overall stiffness of the insulating layer, thus greatly increasing the dislocation of the upper pressure-sensitive layer when subjected to shear force, and therefore higher shear force measurement sensitivity can be obtained. Each unit of the insulator can be a cylinder, or other three-dimensional shapes, such as a thin cylinder, a frustum of a cone, a triangular pyramid, a cone, a truncated triangular pyramid, a truncated frustum of a cone, etc. That is, in addition to being able to adjust the sensitivity and working range of pressure measurement through parameters such as thickness and elastic modulus shown in Embodiment 2, the dislocation between layers when subjected to shear force can be further increased through the design of the shape parameters of the insulating layer, thereby improving the force measurement sensitivity.

[0062] Example 4

[0063] All of the above embodiments are solid structures. In addition, non-solid materials can also be used. Typically, it is the structure of textiles. Please refer to Figure 5 , the force-sensitive part 101 uses carbon black / polyurethane fiber as the raw material, and the insulating part 102 uses polyurethane fiber. The upper and lower layers of the force-sensitive part 101 and the insulating part 102 are woven in one piece by the method of textile three-dimensional weaving. The electrode part 103 is embroidered with silver-plated nylon yarn at the designated position around the force-sensitive part 101. The carbon black / polyurethane composite material itself has certain piezoresistive characteristics inherent in the material. Therefore, this kind of fabric can be used to measure pressure by scanning impedance. More importantly, since all raw materials are woven with elastic yarns, the prepared laminated device has the ability of multi-directional stretching and large deformation. Therefore, in addition to measuring multi-point three-dimensional pressure on a flat surface, this textile device can also be wrapped on curved surfaces with different curvatures, such as wrapped on the arms, palms and fingers of a robot, giving the robot a three-dimensional pressure measurement surface that fits the skin perfectly.

[0064] Based on this, compared with the prior art, the laminated three-dimensional pressure sensing device of the present invention has at least the following beneficial effects:

[0065] (1) A flat device surface, high sensitivity, and a wide pressure measurement range can be obtained at the same time. The present invention adopts a multi-layer laminated structure, which can not only take care of the measurement ranges of large pressure, medium pressure, and small pressure, but also improve the sensitivity of pressure measurement through the parameters of the insulating layer. The present invention provides a laminated pressure sensing device that can realize that the middle detection part of the device does not require wires, and the middle detection part can be an elastomer with high tensile performance, the surface can be flat, can detect three-dimensional pressure with high sensitivity, and can cover large pressure, medium pressure and small pressure at the same time.

[0066] (2) Three-dimensional force: The present invention can realize the multi-functional detection of the touch position, the magnitude and direction of the pressure at each touch position, and the overall shape of the touch pressure, greatly improving the sensing ability of the sensor. In particular, the perception of three-dimensional force can provide richer information compared with the perception of pure normal pressure.

[0067] (3) Simple structure and process: Compared with the pressure sensor matrix, the present invention adopts an integrated structure, without the need to design complex internal microstructures and wirings, reducing the manufacturing difficulty and cost.

[0068] (4) Flexible and stretchable: The sensor material has low cost and is flexible. Without using stretchable wires, it has natural flexibility and stretchability. It can easily cover the surfaces of various irregular three-dimensional objects for all-round tactile coverage and perception, improving the applicability and practicality of the sensor.

[0069] (5) Textile characteristics: When a flexible three-dimensional force sensing device is composed of textile materials, it also has various advantages of textiles and clothing products, including skin-friendly, comfortable, breathable, porous, light, machine washable, dryable, etc. Therefore, it can be perfectly combined with various textile and clothing products.

[0070] The above is a specific description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of the present invention.

Claims

1. A stacked three-dimensional pressure sensing device, characterized in that, Comprising: A force-sensitive part, an insulating part, and electrodes. The force-sensitive part and the insulating part are in sheet form. The force-sensitive part is formed by stacking at least two layers of flexible piezoresistive conductive layers, and the insulating part is disposed between every two layers of the flexible piezoresistive conductive layers. The insulating part is made of an insulating, elastic and deformable material. A plurality of the electrodes are arranged around the periphery of each layer of the flexible piezoresistive conductive layer. The electrodes are used to lead out the resistance distribution data inside each layer of the flexible piezoresistive conductive layer through wires, so that the backend circuit device can respectively and real-time read the resistance distribution data inside each layer of the flexible piezoresistive conductive layer by means of electrical impedance scanning imaging, calculate the pressure distribution data at each position on the surface of each layer of the flexible piezoresistive conductive layer at each moment according to the resistance distribution data, and then calculate each layer of the pressure distribution data to obtain the three-dimensional pressure distribution information received on the surface of the stacked three-dimensional pressure sensing device. Among them, the resistance distribution data includes normal pressure data and shear pressure data. The normal pressure data at the pressure-receiving positions on the surfaces of all the flexible piezoresistive conductive layers is obtained through the pressure distribution data of the first layer of the flexible piezoresistive conductive layer, and the shear pressure data is obtained through the differential calculation of the pressure distribution data of multiple layers of the flexible piezoresistive conductive layers.

2. The stacked three-dimensional pressure sensing device according to claim 1, wherein The force-sensitive part is made of a flexible conductive material sheet, film or fabric. Each layer of the flexible piezoresistive conductive layer has a solid planar layer structure, or a planar network structure, or some regions in the planar network structure contain holes.

3. The stacked three-dimensional pressure sensing device according to claim 1, wherein The insulating part uses an insulating material with elasticity and flexibility. The insulating part is in an overall sheet form or flat form, and the thickness of the insulating part is maintained at the millimeter or micron order of magnitude.

4. The stacked three-dimensional pressure sensing device according to claim 1, wherein The electrodes are also arranged in a preset area of each layer of the flexible piezoresistive conductive layer according to a preset density.

5. The stacked three-dimensional pressure sensing device according to claim 1, wherein The flexible piezoresistive conductive layer uses a conductive composite material, or a conductor or semiconductor material rich in conductive ions, or a piezoresistive conductive fiber aggregate, or an elastomer containing an intrinsically conductive polymer.

6. The stacked three-dimensional pressure sensing device according to claim 1, wherein, The insulating part uses a polyurethane film or a silicone insulating sheet.

7. The stacked three-dimensional pressure sensing device according to claim 1, wherein The electrodes use a coating or plating of a good conductor, or a micro-nano structure material, or a carbon-based conductive material, or a metal-plated fiber material, or an intrinsically conductive polymer, or a liquid metal.

8. The stacked three-dimensional pressure sensing device according to claim 1, wherein The insulating part is placed between two layers of the flexible piezoresistive conductive layers by a fitting method, and the fitting method includes any one of hot pressing, bonding, and roll pressing.

9. The stacked three-dimensional pressure sensing device according to claim 1, wherein The surface of the force-sensitive part is covered with a packaging layer, and the packaging material of the packaging layer uses a flexible high-polymer elastomer with a low elastic modulus.

10. The stacked three-dimensional pressure sensing device according to claim 1, characterized in that, Between the force-sensitive part and the insulating part, a multi-layer weaving or three-dimensional weaving method is adopted to prepare an upper flexible piezoresistive conductive layer, a lower flexible piezoresistive conductive layer and an intermediate insulating layer with piezoresistive effect. The layers of the upper flexible piezoresistive conductive layer, the lower flexible piezoresistive conductive layer and the intermediate insulating layer are connected by yarns. Conductive wires are embroidered around the upper flexible piezoresistive conductive layer and the lower flexible piezoresistive conductive layer according to requirements. The conductive wires are any one of stainless steel fibers, silver-plated nylon yarns, copper-nickel-plated nylon yarns and micron-scale pure copper filaments; or, between the force-sensitive part and the insulating part, a sewing method is adopted to sew the upper flexible piezoresistive conductive layer, the lower flexible piezoresistive conductive layer and the intermediate insulating layer together, and silver-plated nylon wires are sewn at designated positions around each flexible piezoresistive conductive layer.

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