Preparation method and structure of underwater pressure sensing skin

Abstract

The invention discloses a preparation method and structure of an underwater pressure sensing skin in the technical field of flexible sensors and underwater detection. The preparation method comprises the steps of freeze thawing forming of the PVA hydrogel substrate, electrode integration, microneedle injection forming of the conductive gel micro dome and the like, and integrated preparation of the full-hydrogel material is achieved. Meanwhile, an underwater pressure sensing skin structure composed of a PVA hydrogel substrate and a PVA / PEDOT: PSS conductive gel micro-dome-shaped hemispherical structure array is designed, the osmotic pressure principle of a hydrogel semi-permeable membrane is utilized, the osmotic pressure inside the dome structure and the hydrostatic pressure outside the dome structure spontaneously reach balance, and therefore hydrostatic pressure interference is effectively shielded; the device has the advantages of static pressure self-compensation, sensitive dynamic response, conformal fitting, simple preparation process, low cost and the like, and is suitable for broadband and high-precision underwater dynamic pressure sensing in the fields of ocean engineering, underwater equipment and the like.

Description

Technical Field

[0001] This invention relates to the field of flexible sensors and underwater sensing technology, specifically to a method and structure for preparing an underwater pressure sensing skin. Background Technology

[0002] Underwater dynamic pressure is a core physical parameter characterizing the dynamic properties of the underwater environment and the service status of engineering systems. Its accurate detection has significant academic and engineering value in various fields, including marine engineering, underwater equipment engineering, marine environmental science, and marine resource development. Currently, underwater dynamic pressure measurement mainly relies on two technical routes: traditional rigid pressure sensors and flexible pressure sensors, both of which have obvious limitations. Traditional rigid pressure sensors use metal / ceramic as the core sensing carrier, offering high structural stiffness and excellent mechanical strength. However, when their rigid structure is inserted into a fluid flow field, it disrupts the boundary layer distribution, causing boundary layer separation and vortex shedding, leading to distortion of the local pressure field around the probe and deviation of the measured value from the true dynamic pressure. Furthermore, the "intrusive" installation method can easily damage the structural integrity of the carrier, and the installation gap may become a leakage channel, altering the local flow field state. Flexible pressure sensors, relying on organic polymer materials, have advantages in mechanical compliance and structural scalability, enabling conformal fitting with complex curved surfaces and large-area distributed sensing. However, in high-pressure marine environments, low-modulus polymer matrices are prone to creep and stress relaxation, leading to irreversible deformation of the sensitive layer microstructure, sensitivity decay, and zero-point drift. The interface stability between flexible materials and conductive fillers is insufficient, and microcracks and interface slippage are easily generated under long-term high-pressure-low-pressure cyclic loading, shortening service life. At the same time, it is difficult to achieve the synergistic optimization of Pascal-level resolution and kilopascal-level full-scale range while ensuring low bending stiffness and stretchability. Flexible pressure sensors face challenges such as creep and poor stability under high-pressure environments.

[0003] In real flow fields, accurate measurement of fluid dynamic pressure requires separating the static pressure component from the total pressure. However, the dynamic fluctuations and magnitude of static pressure often interfere with this separation process. Traditional differential pressure measurement methods, such as Pitot tubes and differential pressure sensors, struggle to clearly distinguish between "static pressure fluctuations" and "true dynamic pressure," easily leading to misinterpretation of static pressure changes as dynamic pressure signals or masking the true characteristics of low-amplitude dynamic pressure (such as low-frequency pulsations in turbulence), resulting in deviations in dynamic pressure amplitude and frequency spectrum analysis. For strain gauge sensors, prolonged exposure to high static pressure causes creep deformation in the elastic sensitive region, causing the initial zero point of the strain gauge to drift and disrupting the linear relationship between pressure and strain. For piezoelectric sensors, high-intensity static pressure compresses the lattice structure of the piezoelectric crystal, reducing its piezoelectric coefficient and consequently decreasing the sensor's sensitivity to dynamic pressure. For capacitive sensors, changes in static pressure adjust the electrode spacing or dielectric layer thickness of the sensitive capacitor, causing a shift in the capacitance baseline and further amplifying the systematic error in dynamic pressure measurement. In long-term dynamic monitoring applications, such as fatigue load monitoring of marine engineering structures, this type of drift will gradually accumulate and eventually affect the long-term reliability of dynamic pressure data.

[0004] While existing technologies include research on biomimetic crocodile mechanoreceptors and biomimetic dome structures that can achieve a certain level of pressure sensing, they still suffer from problems such as complex fabrication processes, high structural rigidity, difficulty in conformal fitting, limited measurement range, and insufficient long-term stability. Current solutions struggle to simultaneously achieve both "scale-mass-conformal surface" and "accuracy-range-long-term robustness," necessitating innovative technological solutions. Summary of the Invention

[0005] The purpose of this invention is to provide a method and structure for preparing underwater pressure sensing skin, which solves the technical problems of existing underwater pressure sensors, such as large static pressure interference, low dynamic response accuracy, difficulty in conformal bonding, limited range, and insufficient long-term stability. It can maintain zero drift suppression and stable sensitivity under high pressure conditions, conformally bond to complex curved surfaces, and has low cost, making it suitable for accurate underwater dynamic pressure detection in fields such as marine engineering.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for manufacturing an underwater pressure sensing skin includes the following steps:

[0008] S1. Prepare a polyvinyl alcohol (PVA) solution, wherein the mass ratio of PVA to H2O is 1:15 to 1:5, and dissolve the PVA at high temperature;

[0009] S2. Spin-coat the prepared PVA solution in S1 onto the substrate, and then perform a cyclic freeze-thaw treatment to form the base layer of the PVA hydrogel polymer network;

[0010] S3. Attach the electrode wires to the substrate layer of the PVA hydrogel polymer network prepared in S2;

[0011] S4. A layer of PVA hydrogel polymer is then coated over the electrode wires again using a cyclic freeze-thaw process to form an encapsulation layer;

[0012] S5. Mix the PVA solution with the conductive polymer solution PEDOT:PSS at a mass ratio of 10:1 to 1:3 and stir continuously at high temperature to obtain a PVA / PEDOT:PSS conductive gel prepolymer solution.

[0013] S6. The conductive gel prepolymer prepared in S5 is injected into the surface of the encapsulation layer to form a microdome-shaped hemispherical structure array, thereby obtaining an underwater pressure sensing skin structure.

[0014] Furthermore, the high temperature in steps S1 and S5 is 90°C.

[0015] Furthermore, the cyclic freeze-thaw treatment in steps S2 and S4 is carried out at -20°C. The number of cyclic freeze-thaw cycles is determined according to the crosslinking density of the required PVA hydrogel polymer network to ensure the mechanical properties and semi-permeable membrane characteristics of the hydrogel.

[0016] Furthermore, the stirring time in S5 is 6 hours.

[0017] Furthermore, the microneedle injection parameters in S6 are determined based on the radius and wall thickness of the required microdome-shaped hemispherical structure to ensure that the microdome-shaped hemispherical structure can effectively achieve osmotic pressure and hydrostatic pressure balance and dynamic pressure sensing.

[0018] An underwater pressure sensing skin structure, comprising:

[0019] The base layer is made of polyvinyl alcohol (PVA) hydrogel material.

[0020] Electrode wires disposed on the substrate layer;

[0021] An encapsulation layer covering the electrode wires, wherein the encapsulation layer is made of PVA hydrogel polymer;

[0022] And a plurality of microdome-shaped hemispherical structures disposed on the surface of the encapsulation layer, wherein the microdome-shaped hemispherical structures are formed by mixing PEDOT:PSS conductive polymer into PVA hydrogel to form a conductive gel.

[0023] Furthermore, the microdome-shaped hemispherical structure has semi-permeable membrane properties, allowing only solvent molecules to selectively pass through, thereby balancing external hydrostatic pressure.

[0024] Furthermore, the underwater pressure sensing skin structure can conformally attach to complex curved surfaces for underwater pressure sensing.

[0025] By adopting the above technical solution, the present invention has the following advantages:

[0026] 1. This invention provides a method for preparing an underwater pressure sensing skin, which uses a hydrogel swelling-equilibrium mechanism to perform real-time self-compensation for hydrostatic pressure. This method can maintain zero drift suppression and stable sensitivity even under high pressure conditions, effectively bridging the long-term tension between range expansion and accuracy improvement in traditional sensors, and providing a feasible path for long-term service in extreme environments.

[0027] 2. This invention provides a method for preparing an underwater pressure sensing skin, which adopts an integrated molding strategy using homologous organic polymer materials. The base layer and the encapsulation layer are made of the same material, which simplifies the traditional "multi-material-multi-process" manufacturing process, reduces material consumption and processing costs, reduces the risk of interface mismatch, and improves the reliability of interface bonding and environmental stability. The preparation process is simple and low-cost, and is suitable for large-area, large-scale production.

[0028] 3. This invention provides an underwater pressure sensing skin structure, based on flexible electronics technology. Through process chain simplification and parameter optimization, it reduces material consumption and processing steps. Compared with traditional rigid devices, this strategy significantly reduces manufacturing costs and energy consumption, and improves production line yield, laying an economically feasible foundation for the large-scale deployment of the technology.

[0029] 4. This invention provides an underwater pressure sensing skin structure. The sensing skin structure is thin and flexible, and can be conformally attached to complex surfaces with arbitrary curvature. Its thin design significantly reduces the coupling disturbance between the device and the fluid. With its low areal density and small thickness, the unit hardly changes the original flow field distribution during the measurement process, thereby maximally restoring the real pressure pulsation and providing a guarantee for reliable signal acquisition in high-precision scenarios. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the principle of underwater dynamic pressure detection.

[0031] Figure 2 This is a flowchart illustrating the fabrication process of the underwater pressure sensing skin structure of the present invention.

[0032] Figure 3 This is a schematic diagram of the underwater pressure sensing skin structure of the present invention;

[0033] Figure 4 The resistivity change rate of the underwater pressure sensing skin structure under different pressures in an artificial seawater environment;

[0034] Figure 5 Pressure load cycling experiments were conducted on the underwater pressure sensing skin structure in an artificial seawater environment. Detailed Implementation

[0035] The technical solution of the present invention will be specifically described below with reference to the accompanying drawings. It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0036] Figure 1 A schematic diagram of underwater dynamic pressure detection is shown. Specifically, the hydrogel-based dome-shaped dynamic pressure sensing unit is as follows: Figure 1 As shown in figure a, its hemispherical surface is in direct contact with the fluid medium on one hand and physically cross-linked with the hydrogel matrix on the other, and can be regarded as a semi-permeable membrane component. Because it only allows solvent molecules (H2O) to pass through, this semi-permeable membrane component has high selective permeability and can prevent the migration of solute molecules / ions. As an osmotic pressure medium, the osmotic pressure of the hydrogel hemispherical structure follows the van der Hoff equation:

[0037] Π=cRT

[0038] Where Π is the osmotic pressure, which can be quantitatively controlled by adjusting the solute concentration, c is the molar concentration of the solute, R is the gas constant, and T is the thermodynamic temperature.

[0039] Meanwhile, the hydrogel-based microdome-shaped hemispherical structure contains a conductive polymer (PEDOT:PSS) network, which undergoes certain deformation under external load, resulting in a change in its own resistance. Therefore, it can be regarded as a pressure-sensitive unit with high dynamic resolution.

[0040] External hydrostatic pressure acts on the outside of the semipermeable membrane through the fluid environment, triggering the transmembrane migration of solvent molecules, and finally establishing a steady-state equilibrium between osmotic pressure and hydrostatic pressure, thus achieving the construction of a "hydrostatic neutral" environment. This process mainly includes three stages.

[0041] The first stage is the initial imbalance stage. When the system is placed under hydrostatic pressure p... s In a flow field, the hydrostatic pressure outside the semipermeable membrane (fluid environment) is lower than the initial osmotic pressure Π0 inside (osmotic pressure medium cavity). Driven by the pressure difference, solvent molecules migrate through the semipermeable membrane into the cavity. The hydrogel structure absorbs water and swells, specifically as follows: Figure 1 As shown in b;

[0042] The second stage is the equilibrium establishment stage. The influx of solvent molecules dilutes the osmotic medium within the cavity, and the osmotic pressure Π decreases as the concentration c decreases (as can be seen from Π = cRT), until Π equals the external hydrostatic pressure p. s Complete cancellation (Π=p) s When the solvent transmembrane migration rate is zero, the system enters a steady-state equilibrium of osmotic pressure and hydrostatic pressure.

[0043] The third stage is the static pressure neutrality maintenance stage. If the hydrostatic pressure p in the flow field... s When slow fluctuations occur (such as the hydrostatic gradient in a deep-sea vertical profile or pressure fine-tuning in a pipeline system), solvent molecules will dynamically migrate through the semipermeable membrane to readjust the intracavitary osmotic pressure Π, ensuring that Π always tracks p. s The changes in pressure maintain the "static neutrality" of the environment in which the sensitive unit is located—that is, the sensitive unit only bears the residual force of the balance between the osmotic pressure inside the cavity and the external static pressure (usually <1% p). s This essentially eliminates the mechanical effect of static pressure on sensitive elements.

[0044] When the water flow is disturbed, the dynamic pressure (p) d As a transient pulsating load superimposed on hydrostatic pressure, its rate of change is much faster than the relaxation time of osmotic pressure equilibrium (the characteristic time of solvent transmembrane migration is usually on the order of seconds to minutes, while the frequency of dynamic pressure pulsation is mostly on the order of Hz to kHz). Therefore, it cannot trigger the dynamic equilibrium of osmotic pressure and can only be captured by sensitive cells by disturbing the steady-state equilibrium system.

[0045] When dynamic pressure p appears in the flow field d At that time, the total pressure outside the semipermeable membrane becomes p s +p d (or p) s -p d (Depending on the direction of dynamic pressure), instantly breaking "Π=p" s The steady-state equilibrium of "" is formed, resulting in "Δp = (p s +p d )-Π=p d The transient pressure difference directly acts on the flexible walls of the semi-permeable membrane and the osmotic medium cavity, causing micro-deformation of the dome structure, specifically as follows: Figure 1 As shown in c, the transient pressure difference Δp = p d The change is converted into a resistance signal, thereby enabling precise measurement of the amplitude, frequency, and phase characteristics of dynamic pressure.

[0046] A method for preparing an underwater pressure sensing skin includes the following steps: Figure 2 As shown:

[0047] S1. Prepare a polyvinyl alcohol (PVA) solution, wherein the mass ratio of PVA to H2O is 1:15 to 1:5, and dissolve the PVA at a high temperature of 90℃;

[0048] S2. Spin-coat the PVA solution prepared in S1 onto the substrate, and then place it in a -20℃ freezer for cyclic freeze-thaw treatment to form the base layer of the PVA hydrogel polymer network.

[0049] S3. The electrode wires are bonded to the substrate layer of the PVA hydrogel polymer network prepared in S2 for transmitting resistance change signals.

[0050] S4. Cover the electrode wires with a layer of PVA hydrogel polymer by placing them in a -20°C freezer for cyclic freeze-thaw cycles to form an encapsulation layer;

[0051] S5. Mix the PVA solution with the conductive polymer solution PEDOT:PSS at a mass ratio of 10:1 to 1:3, and stir continuously at a high temperature of 90 degrees Celsius for 6 hours to obtain the PVA / PEDOT:PSS conductive gel prepolymer solution.

[0052] S6. The conductive gel prepolymer prepared in S5 is used to form a microdome-shaped hemispherical structure array on the surface of the encapsulation layer by microneedle injection, thereby obtaining the final underwater pressure sensing skin structure.

[0053] The number of freeze-thaw cycles is determined based on the crosslinking density of the required PVA hydrogel polymer network to ensure the mechanical properties and semi-permeable membrane characteristics of the hydrogel. In step S6, the microneedle injection parameters are determined based on the radius and wall thickness of the required microdome-shaped hemispherical structure to ensure that the microdome-shaped hemispherical structure can effectively achieve osmotic pressure and hydrostatic pressure balance and dynamic pressure sensing.

[0054] Example 1

[0055] 1. Prepare PVA solution: Weigh 10g of PVA powder, add 100g of deionized water (PVA to H2O ratio 1:10), place in a 90℃ constant temperature water bath, stir until PVA is completely dissolved, and obtain a transparent PVA solution. Cool to room temperature for later use.

[0056] 2. Preparation of the base layer: Take the above PVA solution and spin-coat it evenly onto a clean glass plate using a spin coater. Set the spin-coating speed to 3000 r / min and the spin-coating time to 30 s to form a uniform PVA film. Place the glass plate with the PVA film in a -20℃ freezer for 24 hours, then remove it and thaw it at room temperature for 8 hours to complete one freeze-thaw cycle. Repeat the above freeze-thaw cycle 3 times to allow the PVA to form a cross-linked hydrogel polymer network, which is the base layer of the PVA hydrogel polymer network.

[0057] 3. Install electrode wires: Cut copper wires to a length of 5cm, and attach one end of the wire to the edge of the PVA hydrogel substrate with conductive silver paste. The area of ​​conductive silver paste applied should be approximately 0.5cm × 0.5cm. Allow it to cure at room temperature for 2 hours to ensure that the copper wires are firmly bonded to the hydrogel substrate and that the electrical connection is good.

[0058] 4. Preparation of encapsulation layer: Take the PVA solution prepared in step 1 again and apply it evenly to the surface of the PVA hydrogel base layer with copper wires installed. The coating thickness is about 0.2 mm. Then place it in a -20℃ freezer for 24 hours and thaw at room temperature for 8 hours to complete one freeze-thaw cycle. Repeat 3 times to form an encapsulation layer, so that the copper wires are wrapped between two layers of PVA hydrogel.

[0059] 5. Preparation of PVA / PEDOT:PSS conductive gel prepolymer: Take 50 mL of the PVA solution prepared in step 1 and add 10 mL of PVA / PEDOT:PSS conductive solution (PVA solution to PEDOT:PSS ratio 5:1). Place the mixed solution in a 90℃ constant temperature water bath and stir continuously at 500 r / min for 6 hours with a magnetic stirrer. Observe the state of the solution every hour during the period to ensure that it is mixed evenly and that no precipitation is produced. After stirring, cool to room temperature to obtain a dark blue PVA / PEDOT:PSS conductive gel prepolymer.

[0060] 6. Fabrication of the underwater pressure-sensing skin structure: Using a microneedle injection system, the aforementioned conductive gel prepolymer was injected onto the surface of the encapsulation layer PVA hydrogel, forming a microdome-shaped hemispherical structure array. The microneedle injection needle diameter was set to 100 μm, the injection pressure was controlled at 0.2 MPa, the injection speed was 5 μL / s, the spacing between adjacent microdomes was set to 500 μm, and the radius of the microdome was controlled to be approximately 200 μm. After injection, the entire structure was frozen at -20℃ for 24 hours and thawed at room temperature for 8 hours, completing one freeze-thaw cycle. This was repeated twice to ensure that the conductive gel prepolymer was fully cross-linked and solidified, forming a stable microdome-shaped hemispherical structure array, ultimately yielding the underwater pressure-sensing skin structure.

[0061] Example 2

[0062] 1. Prepare PVA solution: Weigh 8g of PVA powder, add 40g of deionized water (PVA to H2O ratio 1:5), stir in a 90℃ constant temperature water bath until completely dissolved to obtain PVA solution, and cool for later use.

[0063] 2. Preparation of the base layer: The PVA solution was spin-coated onto a glass plate (2500 r / min, 40 s), frozen at -20℃ for 20 hours, thawed at room temperature for 6 hours, and the freeze-thaw cycle was repeated 4 times to obtain the base layer of the PVA hydrogel polymer network.

[0064] 3. Install electrode wires: Use 4cm long copper wires and bond them to the surface of the base layer hydrogel with conductive silver paste. The curing time is 1.5 hours.

[0065] 4. Preparation of encapsulation layer: Apply PVA solution with a thickness of 0.15 mm, freeze at -20℃ for 20 hours, thaw at room temperature for 6 hours, and repeat the freeze-thaw cycle 4 times to form the encapsulation layer.

[0066] 5. Preparation of conductive gel prepolymer: Take 30 mL of PVA solution, add 10 mL of PEDOT:PSS (ratio 3:1), stir at 90℃ for 6 hours to obtain conductive gel prepolymer.

[0067] 6. Preparation of underwater pressure sensing skin structure: The microneedle injection needle has a diameter of 80 μm, an injection pressure of 0.15 MPa, a speed of 4 μL / s, a spacing of 400 μm between adjacent microdomes, and a radius of 150 μm. After injection, two freeze-thaw cycles are performed to obtain the underwater pressure sensing skin structure.

[0068] Example 3

[0069] 1. Prepare PVA solution: Weigh 5g of PVA powder, add 75g of deionized water (ratio 1:15), dissolve at 90℃, and cool for later use.

[0070] 2. Preparation of the substrate layer: spin coating speed 3500 r / min, time 25s, freezing at -20℃ for 28 hours, thawing at room temperature for 10 hours, and repeating the freeze-thaw cycle twice.

[0071] 3. Install electrode wires: 6cm long copper wires, and cure conductive silver paste for 3 hours.

[0072] 4. Prepare the encapsulation layer: apply a 0.25mm thick coating and perform two freeze-thaw cycles.

[0073] 5. Preparation of conductive gel prepolymer: 40 mL of PVA solution, add 20 mL of PEDOT:PSS (ratio 2:1), stir at 90 °C for 6 hours.

[0074] 6. Preparation of underwater pressure sensing skin structure: The underwater pressure sensing skin structure was prepared by microneedle tip diameter of 120 μm, pressure of 0.25 MPa, speed of 6 μL / s, spacing of 600 μm, radius of 250 μm, and freeze-thaw cycle of 3 times.

[0075] The underwater pressure sensing skin structure prepared as described above is specifically as follows: Figure 3 As shown, it includes:

[0076] Base layer 1, all base layers are made of polyvinyl alcohol (PVA) hydrogel material;

[0077] Electrode wires 2 are disposed on the substrate layer 1;

[0078] Encapsulation layer 3 covers the electrode wires, and the encapsulation layer is made of PVA hydrogel polymer;

[0079] And multiple micro-dome-shaped hemispherical structures 4 disposed on the surface of the encapsulation layer, the micro-dome-shaped hemispherical structures 4 being formed by mixing PEDOT:PSS conductive polymer into PVA hydrogel to form a conductive gel.

[0080] The micro-dome-shaped hemispherical structure possesses semi-permeable membrane properties, allowing only solvent molecules (H2O) to pass through while preventing solute molecules / ions from migrating. The conductive gel within the encapsulation layer forms an osmotic pressure medium, with the osmotic pressure following the van der Hoff equation Π = cRT, which can be quantitatively controlled by adjusting the solute concentration. When placed in a flow field containing hydrostatic pressure, solvent molecules migrate across the membrane, establishing a steady-state equilibrium between the osmotic pressure and the hydrostatic pressure, creating a "hydrostatically neutral" environment. At this point, the sensitive unit only experiences minimal residual equilibrium force, eliminating hydrostatic interference and thus balancing the external hydrostatic pressure. When dynamic pressure exists, its rate of change is much faster than the osmotic pressure equilibrium relaxation time, failing to trigger dynamic osmotic pressure equilibrium. The transient pressure difference induces micro-deformation of the micro-dome structure, leading to a change in the resistance of the conductive gel. The resistance signal is output through the conductive component, enabling precise measurement of dynamic pressure.

[0081] Furthermore, the microdome-shaped hemispherical structure can be replaced with a pyramidal or prism structure, and the replaced structure can still achieve the semi-permeable membrane function and the balance between osmotic pressure and external pressure, as well as dynamic pressure sensing. The electrode wire 2 can also be replaced with other compatible conductive materials, such as other metal wires or conductive fibers with good conductivity and compatibility with PVA hydrogel.

[0082] In addition, this underwater pressure sensing skin structure can conformally attach to complex curved surfaces for underwater pressure sensing.

[0083] The underwater pressure sensing skin structure prepared in the above embodiments was subjected to performance testing. Before the performance testing, the underwater pressure sensing skin structure was immersed in artificial seawater for a period of time to reach a swelling equilibrium state. Then, a pressure response experiment was conducted in the artificial seawater environment. Figure 4 As shown, from Figure 4 The experimental results show that, within the range of 0-350 kPa, the resistance change rate of the underwater pressure sensing skin structure increases with increasing pressure, indicating good responsiveness under different pressures. Furthermore, cyclic pressure load tests were conducted on the underwater pressure sensing skin structure, specifically as follows: Figure 5 As shown, from Figure 5It can be seen that after 10,000 load-unload pressure cycle tests, the underwater pressure sensing skin structure still maintains good performance and high stability under different underwater pressures, making it suitable for accurate underwater dynamic pressure detection in fields such as marine engineering.

[0084] Finally, it should be noted that although the present invention has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Various equivalent changes or substitutions can be made without departing from the concept of the present invention. Therefore, any changes or modifications to the above embodiments within the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for preparing an underwater pressure sensing skin, characterized in that, Includes the following steps: S1. Prepare a polyvinyl alcohol (PVA) solution, wherein the mass ratio of PVA to H2O is 1:15 to 1:5, and dissolve the PVA at high temperature; S2. Spin-coat the PVA solution prepared in S1 onto the substrate, and then perform a cyclic freeze-thaw treatment to form the base layer of the PVA hydrogel polymer network; S3. Attach the electrode wires to the substrate layer of the PVA hydrogel polymer network prepared in S2; S4. A layer of PVA hydrogel polymer is then coated over the electrode wires again using a cyclic freeze-thaw process to form an encapsulation layer; S5. Mix the PVA solution with the conductive polymer solution PEDOT:PSS at a mass ratio of 10:1 to 1:3 and stir continuously at high temperature to obtain a PVA / PEDOT:PSS conductive gel prepolymer solution. S6. The conductive gel prepolymer prepared in S5 is injected into the surface of the encapsulation layer to form a microdome-shaped hemispherical structure array, thereby obtaining an underwater pressure sensing skin structure.

2. The method for preparing an underwater pressure sensing skin according to claim 1, characterized in that, The high temperature in steps S1 and S5 is 90°C.

3. The method for preparing an underwater pressure sensing skin according to claim 1, characterized in that, The freeze-thaw cycles in steps S2 and S4 are carried out at -20°C. The number of freeze-thaw cycles is determined based on the crosslinking density of the required PVA hydrogel polymer network to ensure the mechanical properties and semi-permeable membrane characteristics of the hydrogel.

4. The method for preparing an underwater pressure sensing skin according to claim 1, characterized in that, The stirring time in S5 is 6 hours.

5. The method for preparing an underwater pressure sensing skin according to claim 1, characterized in that, The microneedle injection parameters in S6 are determined based on the radius and wall thickness of the required microdome-shaped hemispherical structure to ensure that the microdome-shaped hemispherical structure can effectively achieve osmotic pressure and hydrostatic pressure balance and dynamic pressure sensing.

6. An underwater pressure sensing skin structure, characterized in that, include: The base layer is made of polyvinyl alcohol (PVA) hydrogel material. Electrode wires disposed on the substrate layer; An encapsulation layer covering the electrode wires, wherein the encapsulation layer is made of PVA hydrogel polymer; And a plurality of microdome-shaped hemispherical structures disposed on the surface of the encapsulation layer, wherein the microdome-shaped hemispherical structures are formed by mixing PEDOT:PSS conductive polymer into PVA hydrogel to form a conductive gel.

7. The underwater pressure sensing skin structure according to claim 6, characterized in that, The microdome-shaped hemispherical structure has semi-permeable membrane properties, allowing only solvent molecules to selectively pass through, thereby balancing the external hydrostatic pressure.

8. The underwater pressure sensing skin structure according to claim 1, characterized in that, The underwater pressure sensing skin structure can conformally attach to complex curved surfaces for underwater pressure sensing.

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