Polyurethane elastomers and flexible pressure sensing arrays and their constituent structures

Abstract

The application discloses a polyurethane elastomer and a flexible pressure sensing array and a structure thereof. The polyurethane elastomer comprises internally distributed hydrogen bond-rich hard phase microzones and surface-distributed low-polarity polyether soft phases, the surface is wetted by the homogenous interface, the internally distributed hydrogen bonds migrate to the surface, and the soft and hard phases at the interface tend to be homogenized. The flexible pressure sensing array comprises sequentially superimposed upper electrode packaging layer structures, gaskets and lower electrode-packaging layer structures, the packaging layer and the gasket used by the flexible pressure sensing array are the same kind of tough polyurethane elastomer rich in hydrogen bond elements, the three-layer structure of the flexible pressure sensing array is stacked, the homogenous interfaces are wetted by each other, the molecular chain segments between the interfaces diffuse and entangle, the hydrogen bond action between the interfaces is cooperated, self-adhesion between the multilayer structures of the device is induced, and the flexible pressure sensing array is further endowed with strong interface structure stability under an extreme mechanical environment.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, in particular to a polyurethane elastomer and a flexible pressure sensing array and their component structures. Background Art

[0002] The encapsulation of flexible sensors and the integration of sensors with robots are key challenges in the field of flexible electronics and intelligent robotics. Encapsulation can protect devices from mechanical damage or leakage, thereby achieving stable functionality. However, most existing flexible sensors are encapsulated with commercial tapes or silicone-based encapsulation, in which the interfacial interactions (such as van der Waals forces) between the functional layers of the sensor are usually weak. When the sensor is subjected to large shear stress or deformation, especially when there is a large mechanical mismatch between the interlayers, the interlayers are prone to separation or delamination. In addition, many encapsulation materials (such as Ecoflex) exhibit poor strength and are prone to cohesive fracture. Some other soft devices rely on strong interfacial interactions between the encapsulation layers, such as covalent bonds and interconnections, but the process usually introduces specific surface treatments (such as plasma treatment to produce temporary hydrophilicity) or the use of hazardous chemicals, which increases costs and is usually time-consuming.

[0003] Another strategy is to use self-adhesive polymers instead of glue. An ideal self-adhesive polymer for device encapsulation or integration should not only have fast and strong adhesion, but also have high cohesive fracture toughness for protection. Although many soft elastomers are sticky, they cannot form encapsulation-level adhesion through physical contact and are easily punctured. For example, styrene-ethylene-butadiene-styrene (SEBS) is a thermoplastic copolymer whose mobile chain ends can penetrate each other to form interfacial welding for plug-and-play assembly of stretchable devices. The self-assembled interface of two layers of SEBS-gold nanoparticle composites can reach a toughness of 240 J·m after being compressed at a pressure of ~98 kPa for 1 hour. -2 However, SEBS often needs to be dissolved in the harmful solvent toluene to form a thin film, and its self-adhesiveness requires pre-pressure to promote welding, which is unsafe and time-consuming.

[0004] In view of this, the present invention is proposed.

[0005] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a polyurethane elastomer and a flexible pressure sensor array and their component structures, which can realize fast, stable and reliable self-adhesive packaging processing, and solve the problem of instability of the device multi-layer structure interface under extreme stress environments caused by the use of commercial adhesives such as tape or silicone in current flexible sensor arrays.

[0007] To achieve the above objectives, the present invention provides a polyurethane elastomer comprising internally distributed hydrogen-bonded hard phase microdomains and surface-distributed low-polarity polyether soft phases. After the surfaces come into contact with each other through wetting, the internally distributed hydrogen bonds migrate to the surface. The chemical structure is as follows:

[0008]

[0009] In one embodiment of the present invention, a reaction system consisting of polytetramethylene glycol, dicyclohexylmethane diisocyanate, and diazolidinyl urea is prepared under dibutyltin dilaurate catalysis conditions, the molecular weight of polytetramethylene glycol is 1000, the molar ratio of polytetramethylene glycol, dicyclohexylmethane diisocyanate, and diazolidinyl urea is 1:1.2:0.3, and the total molar number of hydroxyl groups in the reaction system is 1.3 times that of the isocyanate groups.

[0010] The present invention also provides an upper electrode-encapsulation layer structure, comprising an upper electrode and an encapsulation layer made of the polyurethane elastomer as described above.

[0011] In one embodiment of the present invention, the upper electrode is a composite of non-ionic aqueous polyurethane emulsion and poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate.

[0012] The present invention also provides a gasket, which is made according to the polyurethane elastomer.

[0013] The present invention also provides a lower electrode-encapsulation layer structure, comprising an ionic liquid gel, a lower electrode and an encapsulation layer made of the polyurethane elastomer as described above.

[0014] In one embodiment of the present invention, the lower electrode is a composite of non-ionic aqueous polyurethane emulsion and poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate.

[0015] In one embodiment of the present invention, the ionic liquid gel is prepared by mixing triethylene glycol divinyl ether, 2,2'-(1,2-ethylenedioxy)bis(ethanediol), trimethylolpropane tris(3-mercaptopropionate), ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide and then curing with ultraviolet light.

[0016] The present invention also provides a flexible pressure sensing array, comprising an upper electrode-packaging layer structure, a gasket, and a lower electrode-packaging layer structure stacked sequentially in a "sandwich" manner;

[0017] The upper electrode-encapsulation layer comprises an upper electrode and an encapsulation layer made of a polyurethane elastomer as described above, and / or

[0018] The gasket is made of a polyurethane elastomer as described above, and / or

[0019] The lower electrode-encapsulation layer structure includes an ionic liquid gel, a lower electrode and an encapsulation layer made of the polyurethane elastomer as described above;

[0020] The upper electrode and the ionic liquid gel are respectively oriented toward the gasket.

[0021] In one embodiment of the present invention, the spacer is provided with holes at positions corresponding to the upper electrode and the lower electrode, so as to make the upper electrode and the lower electrode correspond to each other when superimposed.

[0022] Compared with the prior art, according to the polyurethane elastomer and flexible pressure sensing array and their composition structure of the present invention, the polyurethane elastomer has an intrinsic microphase separation structure, the soft phase is a polyether phase, and the hard phase is a hard phase rich in hydrogen bond interactions. The low-polarity polyether soft phase is mainly enriched on the surface of the polyurethane film, while the hydrogen-bonded hard phase microregions are mainly distributed inside the film matrix. After the homogeneous interface is wetting, the hydrogen bond elements in the hard phase microregions inside the film matrix will spontaneously migrate to the interface, so that the elemental composition of the interface tends to the composition inside the polyurethane film matrix, the soft and hard phases at the interface tend to be uniform, strong hydrogen bonds are formed at the interface, the hyperbranched molecular segments move, and the molecular segments are entangled at the interface, which promotes mutual adhesion of the interface and realizes physical contact to form spontaneous adhesion. Polyurethane elastomers, through their homogeneous interface self-adhesion, can be used for adhesive encapsulation between the multilayer structures of flexible pressure sensing arrays. The homogeneous interfaces between the upper electrode-encapsulation layer structure, the gasket, and the lower electrode-encapsulation layer structure all have identical surface energies, and the ratio of polar to non-polar components in the surface energy is exactly the same. Therefore, the homogeneous polyurethane elastomer interface meets optimal wetting conditions, enabling physical contact and spontaneous adhesion. This homogeneous interface self-adhesion allows for instant, rapid, and efficient integration of self-encapsulated flexible pressure sensing arrays. Molecular chain entanglement occurs at the interface, endowing the flexible pressure sensing array with robust interfacial structural stability under extreme mechanical conditions. Furthermore, this homogeneous interface self-adhesion can also enable instant, rapid, and efficient integration of self-encapsulated flexible pressure sensing arrays with soft robots whose surfaces also consist of polyurethane elastomers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow chart of a self-packaging method for a flexible pressure sensing array according to one embodiment of the present invention;

[0024] Figure 2 is a schematic structural diagram of a flexible pressure sensing array according to an embodiment of the present invention;

[0025] Figure 3 is a graph showing the relationship between the interfacial adhesion toughness of a polyurethane elastomer and time according to one embodiment of the present invention;

[0026] Figure 4 is a graph showing the relationship between the interfacial adhesion toughness and temperature of a polyurethane elastomer according to one embodiment of the present invention;

[0027] Figure 5 This is a comparison chart of the adhesion toughness of the interface between a commonly used packaging material for flexible electronics and a polyurethane elastomer according to one embodiment of the present invention;

[0028] Figure 6 is a signal strength diagram of a flexible pressure sensing array according to an embodiment of the present invention after undergoing 10,000 cycles of compression at a pressure of 500 kPa;

[0029] Figure 7 is a signal intensity diagram of a flexible pressure sensing array according to one embodiment of the present invention after 10,000 cycles of friction under a shear stress of 34 kPa;

[0030] Figure 8 is a diagram showing a state in which a flexible pressure sensing array according to an embodiment of the present invention is damaged by extreme stress;

[0031] Figure 9 This is a graph of pressure sensing signal strength collected by multiple channels of a flexible pressure sensing array during vehicle driving according to an embodiment of the present invention;

[0032] Figure 10 FIG. 1 is a scanning electron microscope image of a longitudinal cross-section of a flexible pressure sensing array after driving under vehicle pressure according to one embodiment of the present invention.

[0033] Description of main reference numerals:

[0034] 1-flexible pressure sensing array, 11-encapsulation layer, 12-upper electrode, 13-gasket; 14-lower electrode, 15-ionic liquid gel. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0036] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0037] The invention provides a polyurethane elastomer and a flexible pressure sensing array and a component structure thereof, which are used for preparing a flexible pressure sensor.

[0038] like Figure 2 As shown, the flexible sensing array 1 according to a preferred embodiment of the present invention includes three parts, an upper electrode-packaging layer structure, a gasket 13 and a lower electrode-packaging layer structure.

[0039] like Figure 1 As shown, the self-packaging processing method of the flexible pressure sensing array 1 includes the following steps:

[0040] S1. Processing of the upper electrode-encapsulation layer structure: a non-ionic aqueous polyurethane emulsion is mixed with poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS) in a mass ratio of 1:1 and then coated on a glass surface. The mixture is dried at room temperature overnight and then dried in an oven for 8 hours the next day. A customized upper electrode 12 array structure is obtained by laser cutting. A hyperbranched polyurethane elastomer solution is coated on a glass surface and dried at 60°C until the solvent is completely evaporated. The encapsulation layer 11 is obtained by laser cutting the polyurethane elastomer. The upper electrode 12 is then transferred to the surface of the encapsulation layer 11 using double-sided tape to obtain the upper electrode-encapsulation layer structure.

[0041] The polyurethane elastomer is a hyperbranched polyurethane elastomer with abundant hydrogen bonding units, and its specific chemical structure is as follows:

[0042]

[0043] The hyperbranched polyurethane elastomer is prepared from polytetramethylene glycol (1000 molecular weight), dicyclohexylmethane diisocyanate (DID) and diazolidinyl urea (DID) under dibutyltin dilaurate catalysis. The molar ratio of polytetramethylene glycol, DID and DID is 1:1.2:0.3, so that the total number of hydroxyl groups in the entire reaction system is 1.3 times the number of isocyanate groups. The polyurethane elastomer thus prepared has a hyperbranched structure. The reaction of polytetramethylene glycol with DID produces a soft phase (the right half of the above chemical formula), while the reaction of DID with DID produces a hard phase (the left half of the above chemical formula).

[0044] The above-mentioned polyurethane elastomer has an intrinsic microphase separation structure. The soft phase is a polyether phase, and the hard phase is a hard phase rich in hydrogen bond interactions. The low-polarity polyether soft phase (low surface energy) is mainly enriched on the surface of the polyurethane film, while the hydrogen-bonded hard phase microregions are mainly distributed inside the film matrix. After the homogeneous interface is wetted, the hydrogen bonding elements in the hard phase microregions inside the film matrix will spontaneously migrate to the interface, causing the elemental composition of the interface to tend to the composition inside the polyurethane film matrix, forming strong hydrogen bonds at the interface and achieving spontaneous adhesion. The interaction mode of hydrogen bonds in polyurethane is as follows:

[0045]

[0046] After the homogeneous interfaces of the polyurethane elastomers mentioned above are in mutual wetting contact, the hyperbranched molecular segments move, and the molecular segments entangle at the interface, which promotes mutual adhesion of the interface and can form encapsulation-level adhesion through physical contact.

[0047] In addition to being applicable to the adhesion packaging between multi-layer structures of the flexible pressure sensing array 1, the self-adhesion through the homogeneous interface can also be extended to the integration between the flexible sensing array and the soft robot.

[0048] S2. Processing of the gasket 13: coating a hyperbranched polyurethane elastomer solution on a glass surface, drying at 60° C. until the solvent is completely evaporated, and then laser cutting the polyurethane elastomer to obtain the gasket 13;

[0049] S3. Processing of the lower electrode-encapsulation layer structure: a non-ionic aqueous polyurethane emulsion is mixed with poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS) in a mass ratio of 1:1 and then coated on a glass surface. The mixture is dried at room temperature overnight and then dried in an oven for 8 hours the next day. A customized lower electrode 14 array structure is obtained by laser cutting. The lower electrode 14 is then transferred to the surface of the encapsulation layer 11 using double-sided tape. A layer of photocurable ionic liquid gel precursor liquid is in situ coated on the surface of the lower electrode 14. The surface of the precursor liquid is covered with a sandpaper counter-template of polydimethylsiloxane (PDMS). After UV curing, the sandpaper counter-template of the PDMS is peeled off to obtain a layer of ionic liquid gel 15 with a sandpaper microstructure on the surface, thereby obtaining a lower electrode-encapsulation layer structure.

[0050] The above-mentioned ionic liquid gel 15 is formed by ultraviolet curing of a mixture of triethylene glycol divinyl ether, 2,2'-(1,2-ethylenedioxy)bisethanethiol, trimethylolpropane tris(3-mercaptopropionate), ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, wherein the mass ratio of triethylene glycol divinyl ether, 2,2'-(1,2-ethylenedioxy)bisethanethiol, trimethylolpropane tris(3-mercaptopropionate), ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide is 2.6:2.1:0.34:0.01:1.

[0051] The upper electrode 12 and the lower electrode 14 are respectively a composite of a non-ionic aqueous polyurethane emulsion and poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS).

[0052] PEDOT:PSS is an aqueous solution of a high molecular polymer with high conductivity. Depending on the formulation, aqueous solutions with different conductivity can be obtained. This product is composed of two substances, poly (3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonate (PSS). PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer). The combination of PEDOT and PSS greatly improves the solubility of PEDOT. Aqueous solution conductors are mainly used in hole transport layers of organic light-emitting diodes (OLEDs), organic solar cells, organic thin-film transistors or supercapacitors.

[0053] S4. The upper electrode-encapsulation layer structure, the gasket 13, and the lower electrode-encapsulation layer structure are sequentially stacked in a "sandwich" manner. During stacking, the upper electrode 12 and the ionic liquid gel 15 are respectively oriented toward the gasket 13. The contact interface of the three-layer structure can achieve instant and rapid self-adhesive packaging through a wetting-adhesion process. The upper electrode 12 and the lower electrode 14 are positioned correspondingly, and the gasket 13 is provided with holes at the positions of the upper electrode 12 and the lower electrode 14 to enable the upper electrode 12 and the lower electrode 14 to correspond.

[0054] like Figure 2 As shown, the three-layer structure of the upper electrode-packaging layer structure, the gasket 13 and the lower electrode-packaging layer structure of the flexible pressure sensing array are superimposed to form upper and lower homogeneous polyurethane elastomer contact interfaces. The surface energy of the homogeneous interfaces is the same, and the ratio of the polar component to the non-polar component in the surface energy is exactly the same. Therefore, the homogeneous polyurethane elastomer interface meets the optimal wetting conditions.

[0055] The self-packaged flexible pressure sensing array and the soft robot with the same polyurethane elastomer surface can also be integrated instantly, quickly and efficiently through homogeneous interface self-adhesion.

[0056] The present invention experiments on the relationship between the interfacial adhesion toughness of polyurethane elastomer and time, such as Figure 3 As shown in Figure 2, the transient adhesion toughness of the homogeneous interface of polyurethane elastomer can reach 283 J·m –2 After extending the adhesion time to 24h and 30 days, the adhesion toughness can reach 1001J·m –2 and 1176 J·m –2 . Figure 4 This indicates that increasing the adhesion temperature can further improve the interfacial adhesion toughness. After 24 hours of adhesion at room temperature (RT), the adhesion toughness can reach 1001 J·m –2 After 24h adhesion at 60℃ and 80℃, the homogeneous interface toughness can be increased to 2372J·m –2 and 5054 J·m –2 . Figure 5 The homogeneous interfacial adhesion data of commonly used packaging materials for commercial flexible electronics are consistent with the experimental data on interfacial self-adhesion reported in the literature for SEBS (a linear triblock copolymer with polystyrene as the terminal segment and ethylene-butene copolymer obtained by hydrogenation of polybutadiene as the middle elastic block, the full English name is Styrene Ethylene Butylene Styrene) (Nature, 2023, 614(7948):456-462.). It can be seen that the adhesion toughness of SEBS interfacial self-adhesion is 60 J·m –2 The researchers found that the homogeneous interfacial self-adhesion toughness of the hyperbranched polyurethane elastomer used in this invention was significantly higher than that of commercial materials and those reported in the literature. The excellent adhesion results are primarily due to the strong hydrogen bonding between the hyperbranched polyurethane interfaces and the entanglement of the molecular chains after diffusion.

[0057] like Figure 6 As shown in the figure, the signal of the flexible pressure sensing array is stable after 10,000 cycles of compression at a pressure of 500 kPa. It can be seen that the flexible pressure sensing array has strong signal stability at a pressure of 500 kPa. Figure 7 As shown in the figure, the signal of the flexible pressure sensor device is stable after 10,000 cycles of friction under 34 kPa shear stress, indicating that the flexible pressure sensor array has strong signal stability under 34 kPa shear stress. This shows that the strong adhesion stability of the interface gives the flexible pressure sensor array reliable signal sensing capabilities in extreme mechanical environments.

[0058] Figure 8This is a picture of the flexible pressure sensing array suffering from extreme stress damage. A wild thorn with a tip diameter of 500μm pierced the sensing array with a maximum puncture force of ~6N and a pressure of about ~760MPa at the tip. It can be seen that the designed flexible pressure sensing array can withstand strong external force damage and is puncture-resistant.

[0059] The flexible pressure sensor array is attached to the surface of the car tire. The car is moving at a speed of 7-10 km / h. –1 Speed ​​​​1.8km, Figure 9 The flexible pressure sensing array records multi-channel pressure sensing signals in real time during driving. Throughout the vehicle's driving process, the multi-channels simultaneously collected uniform pressure signals, demonstrating the excellent structural stability of the flexible pressure sensing array. Figure 10 This is a scanning electron microscope image corresponding to a microscope scale of 100μm of the longitudinal section of the flexible pressure sensing array after driving under vehicle pressure. It can be clearly seen from the image that the contact interface of the polyurethane elastomer after adhesion is tightly bonded and the structure is stable.

[0060] The packaged flexible pressure sensor array is integrated on the surface of a soft robot whose surface is a hyperbranched polyurethane elastomer. The flexible pressure sensor array packaging layer and the surface of the soft robot are both hyperbranched polyurethane elastomers. Therefore, the flexible pressure sensor array and the soft robot can be quickly and efficiently integrated by simply sticking the flexible pressure sensor array on the surface of the soft robot.

[0061] In summary, the present invention implements a novel packaging method for a flexible pressure sensing array, in which the packaging layer and gasket used in the design of the flexible pressure sensing array are both constructed from the same tough, hyperbranched polyurethane elastomer, rich in hydrogen bonding motifs. After the three layers of the flexible pressure sensing array are stacked and their homogeneous interfaces mutually wet, the diffusion and entanglement of molecular segments between the interfaces, combined with hydrogen bonding between the interfaces, synergistically induce self-adhesion between the device's multilayer structures, thereby endowing the flexible pressure sensing array with robust interfacial structural stability under extreme mechanical conditions. Furthermore, this homogeneous interfacial self-adhesion has also been successfully extended to the integration of the flexible pressure sensing array with the interface of a soft robot.

[0062] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A top electrode-encapsulation layer structure, characterized in that: The invention comprises an upper electrode and an upper electrode packaging layer; the upper electrode packaging layer is made of a polyurethane elastomer; the polyurethane elastomer comprises internally distributed hard phase micro-regions rich in hydrogen bonds and a surface-distributed low-polarity polyether soft phase. After the surfaces are in mutual wetting contact, the internally distributed hydrogen bonds migrate to the surface. The chemical structure is as follows:

2. The upper electrode-encapsulation layer structure according to claim 1, characterized in that: The upper electrode is a composite of non-ionic aqueous polyurethane emulsion and poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate.

3. The upper electrode-encapsulation layer structure according to claim 1, characterized in that: The polyurethane elastomer is prepared by a reaction system consisting of polytetramethylene ether diol, dicyclohexylmethane diisocyanate, and diazolidinyl urea under the catalytic condition of dibutyltin dilaurate. The molecular weight of the polytetramethylene ether diol is 1000, the molar ratio of the polytetramethylene ether diol, the dicyclohexylmethane diisocyanate, and the diazolidinyl urea is 1:1.2:0.3, and the total molar number of hydroxyl groups in the reaction system is 1.3 times that of the isocyanate groups.

4. A lower electrode-encapsulation layer structure, characterized in that: The invention comprises an ionic liquid gel, a lower electrode and a lower electrode packaging layer; the lower electrode packaging layer is made of a polyurethane elastomer; the polyurethane elastomer comprises internally distributed hard phase micro-regions rich in hydrogen bonds and a surface-distributed low-polarity polyether soft phase. After the surfaces are in wetting contact with each other, the internally distributed hydrogen bonds migrate to the surface. The chemical structure is as follows:

5. The lower electrode-encapsulation layer structure according to claim 4, characterized in that: The polyurethane elastomer is prepared by a reaction system consisting of polytetramethylene ether diol, dicyclohexylmethane diisocyanate, and diazolidinyl urea under the catalytic condition of dibutyltin dilaurate. The molecular weight of the polytetramethylene ether diol is 1000, the molar ratio of the polytetramethylene ether diol, the dicyclohexylmethane diisocyanate, and the diazolidinyl urea is 1:1.2:0.3, and the total molar number of hydroxyl groups in the reaction system is 1.3 times that of the isocyanate groups.

6. The lower electrode-encapsulation layer structure according to claim 4, characterized in that: The lower electrode is a composite of non-ionic aqueous polyurethane emulsion and poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate.

7. The lower electrode-encapsulation layer structure according to claim 4, characterized in that: The ionic liquid gel is prepared by mixing triethylene glycol divinyl ether, 2,2'-(1,2-ethylenedioxy)bis(ethylenethiol), trimethylolpropane tris(3-mercaptopropionate), ethyl 2,4,6-trimethylbenzoylphenylphosphonate and 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide and then curing with ultraviolet light.

8. A flexible pressure sensing array, characterized in that: It includes an upper electrode-packaging layer structure, a gasket and a lower electrode-packaging layer structure stacked in sequence in a "sandwich" manner; The upper electrode-packaging layer comprises an upper electrode and an upper electrode packaging layer; the upper electrode packaging layer is made of polyurethane elastomer, and / or The gasket is made of polyurethane elastomer, and / or The lower electrode-encapsulation layer structure includes an ionic liquid gel, a lower electrode and a lower electrode encapsulation layer; the lower electrode encapsulation layer is made of polyurethane elastomer; The polyurethane elastomer comprises internally distributed hard phase micro-regions rich in hydrogen bonds and a surface-distributed low-polarity polyether soft phase. After the surfaces are in wetting contact with each other, the internally distributed hydrogen bonds migrate to the surface. The chemical structure is as follows: The upper electrode and the ionic liquid gel are respectively oriented toward the gasket.

9. The flexible pressure sensing array according to claim 8, characterized in that: The polyurethane elastomer is prepared by a reaction system consisting of polytetramethylene ether diol, dicyclohexylmethane diisocyanate, and diazolidinyl urea under the catalytic condition of dibutyltin dilaurate. The molecular weight of the polytetramethylene ether diol is 1000, the molar ratio of the polytetramethylene ether diol, the dicyclohexylmethane diisocyanate, and the diazolidinyl urea is 1:1.2:0.3, and the total molar number of hydroxyl groups in the reaction system is 1.3 times that of the isocyanate groups.

10. The flexible pressure sensing array according to claim 9, characterized in that: The gasket is provided with holes at positions corresponding to the upper electrode and the lower electrode, so as to make the upper electrode and the lower electrode correspond to each other when they are stacked.

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