Porous PDMS (polydimethylsiloxane) sponge-based underwater pressure sensor as well as preparation method and application thereof

Abstract

The invention relates to a porous PDMS sponge-based underwater pressure sensor and a preparation method and application thereof. The porous PDMS sponge-based underwater pressure sensor comprises: a porous elastomer dielectric layer, wherein the material of the porous elastomer dielectric layer is a porous PDMS sponge in which an ionic liquid is uniformly attached; the electrode layers are arranged on the upper surface and the lower surface of the porous elastomer dielectric layer and keep in contact with the porous elastomer dielectric layer; and the packaging layer is used for performing waterproof packaging on the sensor. The sensor can monitor the pressure of at least 10 kPa underwater, has stable response to the water depth of 2 mm, and shows good cycle stability. Moreover, the adopted preparation process is simple and low in cost, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flexible sensors, and relates to a porous PDMS sponge-based underwater pressure sensor and a preparation method and application thereof. BACKGROUND

[0002] With the continuous exploration of the underwater environment by humans, underwater flexible sensors have become increasingly important in underwater exploration and detection. In recent years, flexible pressure sensors have made considerable progress in land applications; however, due to the huge differences between underwater and land environments, these sensors are easily corroded and degraded by various underwater environments, which has an irreversible impact on the performance of the sensors. Therefore, the implementation of wearable sensors for underwater sensing applications still faces many great challenges.

[0003] A flexible pressure sensor is a device that can convert mechanical stimulation into an electrical signal and has been widely used in human-computer interaction, artificial intelligence, and health monitoring. According to the sensing mechanism, pressure sensors can be divided into four common types, including piezoelectric, piezoresistive, piezocapacitive, and triboelectric sensors. Compared with other types, piezocapacitive sensors have the advantages of high precision, high stability, and simple device structure, and are widely used to achieve high-performance pressure sensing. They usually adopt a parallel plate capacitor structure or a microstructure capacitor structure, which is composed of two parallel electrode plates. When the pressure of the medium changes, the distance between the electrode plates or the dielectric constant of the dielectric layer changes, resulting in a change in the capacitance value. Therefore, a highly deformable dielectric layer is a key component for improving the sensitivity of capacitive pressure sensors.

[0004] Currently, in terms of dielectric layer structure, researchers mainly improve the sensitivity and detection range of flexible capacitive pressure sensors by designing the surface microstructure (pyramid, hemisphere, lotus leaf surface papilla, etc.) of the dielectric layer or the bulk porous structure of the dielectric layer. On the one hand, the microstructure on the surface of the dielectric layer generally requires techniques such as photolithography, 3D printing, and biomimetic template replication, which have defects such as complex process, high cost, and long time-consuming. On the other hand, since the deformation of the surface micro-nano structure under pressure quickly reaches a saturation state, it can only improve a part of the detection range. The bulk porous structure of the dielectric layer undergoes processes of pore size reduction, pore wall contact, and further pore wall extrusion under pressure, delaying the process of deformation reaching a saturation state, thereby improving the detection range. Therefore, the porous structure has more obvious advantages in the design of sensors. In terms of dielectric layer materials, the effective dielectric constant of the dielectric layer is improved by adding high dielectric constant and low dielectric loss fillers to form a composite dielectric layer, thereby improving the sensitivity and detection range. Generally, it can be divided into conductive fillers (carbon black, carbon nanotubes, graphene, etc.), piezoelectric fillers (polyvinylidene fluoride, barium titanate, etc.), and magnetic fillers (metallic nickel, etc.).

[0005] Most of the sensors currently have a limited detection range when meeting high sensitivity, and it is difficult to maintain high sensitivity when pursuing a larger detection range. Therefore, designing a flexible pressure sensor with high sensitivity and underwater pressure sensing still faces many challenges. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a porous PDMS sponge-based underwater pressure sensor and its preparation method and application, which has the advantages of high sensitivity, good stability, simple preparation process, low preparation cost, etc., and can realize underwater pressure detection.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows.

[0008] In a first aspect, the present application provides a porous PDMS sponge-based underwater pressure sensor, comprising: a porous elastomer dielectric layer, the material of the porous elastomer dielectric layer is a porous PDMS sponge with internal attached ionic liquid; an electrode layer, the electrode layer is arranged on the upper surface and the lower surface of the porous elastomer dielectric layer and maintains contact with the porous elastomer dielectric layer; and a packaging layer for waterproof packaging of the sensor.

[0009] Preferably, the ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate.

[0010] Preferably, the material of the packaging layer is any one of thermoplastic polyurethane, polydimethylsiloxane, aliphatic aromatic random copolyester and silica gel. For example, the packaging layer is any one of thermoplastic polyurethane film, PDMS film, Ecoflex film and Dragonskin film.

[0011] Preferably, the electrode layer is an electrode suitable for a capacitive sensor; preferably, the electrode layer is an ITO / PET electrode. For example, the electrode layer is an ITO / PET electrode.

[0012] In a second aspect, the present application provides a preparation method of the porous PDMS sponge-based underwater pressure sensor. The preparation method comprises the following steps: Preparation of a porous elastomer dielectric layer; Assembling the porous elastomer dielectric layer and the electrode layer; Then waterproof packaging is performed by using a packaging film to obtain a porous PDMS sponge-based underwater pressure sensor.

[0013] Preferably, the preparation method of the porous elastomer dielectric layer comprises: uniformly mixing polydimethylsiloxane (PDMS) prepolymer, platinum curing agent, emulsifier and non-polar solvent to obtain a precursor solution; injecting the mixed solution of water and the precursor solution into a mold through micro-channel injection; and obtaining the porous PDMS sponge through heat curing; and obtaining the porous elastomer dielectric layer by immersing the porous PDMS sponge in ionic liquid and then extruding the excess ionic liquid.

[0014] Preferably, the emulsifier is at least one selected from Span 60, Span 80 and Span 85; the non-polar solvent comprises at least one of n-hexadecane, n-pentadecane and n-hexane; and preferably, the mass ratio of the polydimethylsiloxane PDMS prepolymer, platinum curing agent, emulsifier and non-polar solvent in the precursor solution is 1:(0.09-0.15):(0.02-0.04):(0.5-2).

[0015] Preferably, the heat curing temperature is 80-100 DEG C, and the heat curing time is 6-12 hours.

[0016] Preferably, the method for assembling the porous elastomer dielectric layer and the electrode layer comprises: cutting the electrode layer to a suitable size, coating adhesive on the upper surface and the lower surface of the porous elastomer dielectric layer, and then placing the electrode layer.

[0017] In a third aspect, the application provides application of the porous PDMS sponge-based underwater pressure sensor in underwater pressure monitoring.

[0018] Compared with the prior art, the application has the following advantages:

[0019] (1) The application prepares the PDMS sponge with developed void structure through micro-channel injection with water as a template, which greatly improves the compression deformation capacity of the material.

[0020] (2) The porous PDMS sponge prepared by the application has different size pore structures, which improves the sensitivity and widens the detection range. In addition, the application introduces ionic liquid into the porous elastomer dielectric layer, which effectively improves the sensitivity of the sensor by improving the dielectric constant of the dielectric layer.

[0021] (3) The porous PDMS sponge-based underwater pressure sensor prepared by the application can work underwater, can detect at least 10 kPa of pressure underwater, can have stable response to 2 mm of water depth, and has good cycle response stability.

[0022] (4) The porous PDMS sponge-based underwater pressure sensor has the advantages of quick response, simple preparation process, large batch production, light and thin material, excellent deformation performance, and wide application prospect in the field of flexible sensors. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM image of the porous PDMS sponge prepared in Example 1 of the present application; Figure 2 Optical image of the porous PDMS sponge prepared in Example 1 of the present application; Figure 3 Photo of the porous PDMS sponge-based underwater pressure sensor prepared in Example 1 of the present application; Figure 4 Pressure response test results of the porous PDMS sponge-based underwater pressure sensor prepared in Example 1 of the present application in air; Figure 5 Cyclic stability test results of the porous PDMS sponge-based underwater pressure sensor prepared in Example 1 of the present application in air; Figure 6 Pressure response test results of the porous PDMS sponge-based underwater pressure sensor prepared in Example 1 of the present application under water; Figure 7 Cyclic stability test results of the porous PDMS sponge-based underwater pressure sensor prepared in Example 1 of the present application under water; Figure 8 Lowest detection limit results of the porous PDMS sponge-based underwater pressure sensor prepared in Example 1 of the present application in water; Figure 9 Structure schematic diagram of the porous PDMS sponge-based underwater pressure sensor of the present application, 1 - encapsulation layer, 2 - (collection) electrode layer, 3 - lead electrode, 4 - porous elastomer dielectric layer, 5 - ionic liquid; Figure 10 Relative capacitance change curve of the porous PDMS sponge-based underwater pressure sensor prepared in the comparative example of the present application in air. DETAILED DESCRIPTION

[0024] The present application is further illustrated by the following examples, which should be understood as merely illustrative of the present application, rather than limiting the present application. The following exemplary illustrates the porous polydimethylsiloxane (PDMS) sponge-based underwater pressure sensor and its preparation method and application.

[0025] The porous PDMS sponge-based underwater pressure sensor of the present application is a capacitive sensor. From the sensing mechanism of the sensor, the present application uses a porous PDMS sponge as a dielectric layer, and attaches an ionic liquid inside the PDMS to increase the dielectric constant, thereby realizing high-sensitivity pressure detection. The sensing mechanism is based on capacitance change, and it is a special structure capacitive sensor designed specifically for underwater pressure sensing applications.

[0026] The sensor comprises a porous elastomer dielectric layer made of a porous PDMS sponge with an ionic liquid attached inside. The pore size of the porous elastomer dielectric layer is multi-scale, which is the pore size of the porous PDMS sponge itself. For example, the pore size of the porous PDMS sponge ranges from 100 microns to 1000 microns.

[0027] In the ionic electronic sensor, a double electric layer is formed between the ion-conducting material and the electrode. The existence of this double electric layer can significantly improve the performance of the sensor. Unlike traditional sensors that rely on larger physical space and complex electrical signal processing, the double electric layer can reduce the charge separation distance to below 1 nanometer, thereby greatly improving the sensitivity of the pressure sensor. It should be understood that any kind of ionic liquid is suitable for the underwater pressure sensor of the present application. Basically, ionic liquids can meet the demand of increasing dielectric constant in the present application. Ionic liquids can have good wettability with PDMS, and can also be uniformly loaded on the surface of PDMS elastomer. In addition, ionic liquids have high ionic conductivity, which can form an interfacial double electric layer with the electrode, thereby increasing the capacitance response range and meeting the requirement of increasing dielectric constant. In some embodiments, the ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate.

[0028] The sensor further comprises an electrode layer (for signal acquisition) arranged on the upper surface and the lower surface of the porous elastomer dielectric layer and in contact with the porous elastomer dielectric layer. It should be understood that electrodes suitable for capacitive sensors are suitable for the present application. In some embodiments, the electrode layer is an ITO / PET electrode. The ITO / PET is a signal acquisition electrode. The resistance of the ITO / PET electrode (conductive film) can be 27-150 ohms.

[0029] The sensor further comprises a packaging layer. The design of the packaging layer is a routine operation in the art. The packaging layer can be a cover layer arranged on the periphery of the porous PDMS sponge-based underwater pressure sensor. That is, the packaging layer covers the outside of the electrode layer to serve as waterproof packaging for the sensor. In order to further reinforce the packaging effect, a packaging layer can also be arranged on the outside of the dielectric layer which is not in contact with the electrode layer.

[0030] In an optional embodiment, the thin film material for the waterproof packaging of the sensor is any one of thermoplastic polyurethane film, PDMS film, Ecoflex film and Dragonskin film, preferably PDMS film.

[0031] The following exemplary describes the preparation method of the underwater pressure sensor.

[0032] A porous elastomer dielectric layer is prepared. A polydimethylsiloxane (PDMS) prepolymer, a curing agent, an emulsifier, and a non-polar solvent are mixed uniformly to obtain a precursor solution. The mixed solution of water and the precursor solution is injected into a mold by a micro-channel injection method, and is heat-cured to obtain a PDMS sponge with a porous structure. The porous PDMS sponge is soaked in an ionic liquid, and after the excess ionic liquid is squeezed out, a porous elastomer dielectric layer with the ionic liquid attached inside is obtained. The PDMS prepolymer can be purchased by commercial means.

[0033] The template method for preparing the porous PDMS has problems such as difficulty in removing the template and difficulty in fine control of the pore size. The present application uses a micro-channel injection method to prepare a porous PDMS sponge and soak it in an ionic liquid, which does not require a template and can achieve fine control of the pore size of the porous PDMS by fine adjustment of the micro-channel injection process parameters. The porous PDMS sponge prepared by the micro-channel injection method has excellent compression deformation ability, and the ionic liquid soaking can greatly improve the dielectric constant of the elastomer, thereby improving the detection sensitivity and detection range of the sensor.

[0034] In the precursor solution, the mass ratio of the polydimethylsiloxane PDMS prepolymer, the platinum curing agent, the emulsifier, and the non-polar solvent is 1:(0.09-0.15):(0.02-0.04):(0.5-2). The emulsifier can be selected from at least one of Span 60, Span 80, and Span 85. The non-polar solvent includes but is not limited to at least one of n-hexadecane, n-pentadecane, and n-hexane. The heat curing temperature is 80-100°C, and the heat curing time is 6-12 hours. The mass ratio of water to the precursor solution can be 1-10:1-10. For example, the mass ratio of water to the precursor solution is 1:1. The amount of the porous PDMS sponge and the ionic liquid is not particularly limited, as long as the porous PDMS sponge can be completely immersed in the ionic liquid.

[0035] The porous elastomer dielectric layer and the electrode layer are assembled to prepare the underwater pressure sensor. For example, the electrode conductive film is cut to a suitable size, and a thin layer of silica gel is coated on the upper surface and the lower surface of the porous elastomer dielectric layer. The collection electrode is placed on the upper surface and the lower surface of the porous elastomer dielectric layer after the thin layer of silica gel is coated. After the silica gel is completely cured, the lead wire (lead electrode) is connected. The material of the lead electrode is not particularly required, as long as it is conductive. The lead electrode is arranged at the end side of the collection electrode. The arrangement of the lead electrode is also a conventional arrangement of the capacitive electrode.

[0036] The underwater pressure sensor is waterproofly packaged by using a packaging film to obtain the porous PDMS sponge-based underwater pressure sensor. For example, the packaging film is attached to and bonded to the outer surface of the ITO / PET electrode.

[0037] The application also provides the application of the porous PDMS sponge-based underwater pressure sensor in underwater pressure monitoring.

[0038] On the basis of common sense in the art, the above-mentioned preferred conditions can be combined arbitrarily, that is, to obtain each preferred example of the application.

[0039] The application will be further described by way of examples below, but the application is not limited to the scope of the examples. The experimental methods in the following examples are not specified, and are selected according to conventional methods and conditions, or according to the instructions of the commodity. The reagents and raw materials used in the application are commercially available.

[0040] Example 1

[0041] Preparation of the porous elastomer dielectric layer: 9 g of polydimethylsiloxane prepolymer (Dow Corning DC184), 0.9 g of platinum gold curing agent, and 0.18 g of Span 80 were respectively added to 6 g of n-hexadecane and magnetically stirred to mix uniformly to obtain a precursor solution; 10 g of the precursor solution and 10 g of deionized water were respectively taken by two 10 mL syringes, and the precursor solution and the water were mixed by micro-channel injection and then injected into a cylindrical mold to obtain an emulsion with micro-water droplets. The emulsion was placed in an oven at 80°C for heat curing for 12 h to obtain a cylindrical PDMS sponge with a porous structure, and the diameter of the sponge was about 2 cm. The porous PDMS sponge was completely immersed in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, and the excess ionic liquid was squeezed out to obtain the porous elastomer dielectric layer.

[0042] Preparation of underwater pressure sensor: according to the size of the porous PDMS sponge, ITO / PET conductive film is cut into 3cm╳2.5cm, a thin layer of 706 silicone rubber is coated on the upper and lower surfaces of the porous elastomer dielectric layer, and then ITO / PET electrodes are placed on the upper and lower surfaces of the porous elastomer dielectric layer, which is left at room temperature overnight to allow the 706 silicone rubber to fully cure, so that the porous elastomer dielectric layer is bonded with the upper and lower ITO / PET electrode conductive surfaces; two electrodes are respectively connected with two wires, and the preparation of the underwater pressure sensor is completed.

[0043] Packaging of underwater pressure sensor: the upper and lower ITO / PET electrode surfaces of the prepared underwater pressure sensor are attached with thermoplastic polyurethane film, and the two films are completely bonded by hot pressing, and the electrode lead-out part is coated with 706 silicone rubber, and the packaging of the underwater pressure sensor is completed after complete curing, and the porous PDMS sponge-based underwater pressure sensor is obtained.

[0044] Example 2

[0045] Compared with Example 1, except that the addition ratio of polydimethylsiloxane PDMS prepolymer to n-hexadecane in step (1) is 1.2:1, the rest of the operation and conditions are the same as Example 1.

[0046] Example 3

[0047] Compared with Example 1, except that the addition ratio of polydimethylsiloxane PDMS prepolymer to n-hexadecane in step (1) is 1:1, the rest of the operation and conditions are the same as Example 1.

[0048] Example 4

[0049] Compared with Example 1, except that the emulsion heat curing temperature in step (1) is 90℃, the rest of the operation and conditions are the same as Example 1.

[0050] Example 5

[0051] The difference between this example and Example 1 is that the packaging material for preparing the porous PDMS sponge-based underwater pressure sensor is different:

[0052] The upper and lower ITO / PET electrode surfaces of the prepared porous PDMS sponge-based underwater pressure sensor are attached with Ecoflex film, and the two films are completely bonded by 706 silicone rubber, and the electrode lead-out part is coated with 706 silicone rubber, and the packaging of the underwater pressure sensor is completed after complete curing, and the porous PDMS sponge-based underwater pressure sensor is obtained. Among them, the Ecoflex model used is TM 0030, the ratio of components A and B is 1:1.

[0053] Example 6

[0054] The difference between the present embodiment and embodiment 1 is that the packaging material of the porous PDMS sponge-based underwater pressure sensor is different:

[0055] The upper and lower ITO / PET electrode surfaces of the prepared porous PDMS sponge-based underwater pressure sensor are attached with Dragon skin films, and the two films are completely bonded by using 706 silicone rubber. The electrode lead-out part is coated with 706 silicone rubber. After complete curing, the packaging of the underwater pressure sensor is completed, and the porous PDMS sponge-based underwater pressure sensor is obtained. The Dragon skin used is TM 10, the ratio of components A and B is 1:1.

[0056] Morphology characterization

[0057] The SEM image of the porous PDMS sponge prepared in embodiment 1 is shown in Figure 1 , and the optical photograph of the porous PDMS sponge prepared in embodiment 1 is shown in Figure 2 . It can be seen from the SEM image and the optical photograph that the prepared porous PDMS sponge has a porous structure with different pore sizes. The porous PDMS sponge-based underwater pressure sensor prepared in embodiment 1 is shown in Figure 3 .

[0058] Performance test analysis of the porous PDMS sponge-based underwater pressure sensor in air.

[0059] The porous PDMS sponge-based underwater pressure sensor prepared in embodiment 1 is tested in air in the range of 0-10 kPa. The sensor is connected to an LCR meter, and the sensor is subjected to pressure by a mechanical testing machine. The sensitivity test results of the sensor are shown in Figure 4 . The average sensitivity of the porous PDMS sponge-based underwater pressure sensor in air in the range of 0-10 kPa is 6.664 kPa -1 .

[0060] Due to the different sizes of the pores in the elastomer dielectric layer, the Young's modulus of the porous dielectric layer will change compared to the Young's modulus of the non-porous dielectric layer. Compared with the non-porous PDMS sensor, when the same force acts on the sensor, the sensor with the porous PDMS dielectric layer will have a larger compression amount, and thus a larger relative capacitance change, and the sensitivity of the sensor will be improved. At the same time, the dielectric constant will also change during compression. When external pressure acts on the sensor, the volume of the pores in the porous PDMS dielectric layer gradually decreases, and the proportion of the volume of the pores in the volume of the porous PDMS dielectric layer also gradually decreases, and the dielectric constant of the dielectric layer increases. This additional factor further improves the sensitivity of the sensor.

[0061] To evaluate the cyclic stability of the sensor in air, the sensor was subjected to 50 cycles of response recovery test at 7 kPa pressure. As shown in Figure 5 The amplitude of the sensor's capacitance change rate did not change significantly, and the capacitance change rate curve waveform remained good consistency, which proved that the sensor had good cyclic stability in air.

[0062] Performance test analysis of the porous PDMS sponge-based underwater pressure sensor in water.

[0063] The porous PDMS sponge-based underwater pressure sensor prepared in Example 1 was subjected to pressure test in water in the range of 2-10 kPa. The sensor was placed underwater and connected to an LCR meter, and the sensor was subjected to pressure by a mechanical testing machine. The sensor sensitivity test results are shown in Figure 6 The average sensitivity of the porous PDMS sponge-based underwater pressure sensor in air in the range of 2-10 kPa was 1.0399 kPa -1 , and the sensor sensitivity in water was slightly lower than in air, but still maintained a high sensitivity.

[0064] To evaluate the cyclic stability of the sensor in water, the sensor was subjected to 50 cycles of response recovery test at 7 kPa pressure. As shown in Figure 7 The amplitude of the sensor's capacitance change rate did not change significantly, and the capacitance change rate curve waveform remained good consistency, which proved that the sensor had good cyclic stability in water.

[0065] Analysis of the minimum detection limit of the porous PDMS sponge-based underwater pressure sensor in water.

[0066] The porous PDMS sponge-based underwater pressure sensor was placed underwater at a depth of about 12 cm, connected to an LCR meter, and 2 mm of water was added in sequence with a syringe to test whether the sensor could detect 2 mm of water depth. The results are shown in Figure 8 As the water depth increased in sequence, the capacitance change rate also increased in sequence, indicating that the sensor had the ability to identify 2 mm of water depth. Therefore, the minimum detection limit of the sensor in water at a depth of 12 cm was about 20 Pa, which showed that the sensor had great potential for underwater monitoring applications.

[0067] Comparative Example 1

[0068] The same as Example 1, the only difference is that pure porous PDMS is used as the porous elastomer dielectric layer. That is, there is no ionic liquid loaded in the porous PDMS sponge.

[0069] Figure 10is the relative capacitance change curve of the pressure sensor in air under the condition of 0-10 kPa gradient pressure. With the increase of pressure, its capacitance gradually increases and shows obvious linear correlation with pressure. Although the capacitance changes with the pressure, the initial capacitance of the sensor is only about 3.5 pF due to the lack of the presence of ionic liquid, and the response sensitivity is also low.

[0070] Although the specific embodiments of the present application are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A porous PDMS sponge-based underwater pressure sensor, characterized in that: The porous PDMS sponge-based underwater pressure sensor includes: a porous elastomeric dielectric layer, the material of the porous elastomeric dielectric layer is a porous PDMS sponge with ionic liquid uniformly attached inside; an electrode layer, the electrode layer is arranged on the upper and lower surfaces of the porous elastomeric dielectric layer and maintains contact with the porous elastomeric dielectric layer; and a packaging layer for waterproofing the sensor.

2. The porous PDMS sponge-based underwater pressure sensor according to claim 1, characterized in that: The ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate.

3. The porous PDMS sponge-based underwater pressure sensor according to claim 1 or 2, characterized in that: The material of the encapsulation layer is at least one of thermoplastic polyurethane, polydimethylsiloxane, aliphatic aromatic random copolyester and silicone.

4. The porous PDMS sponge-based underwater pressure sensor according to any one of claims 1 to 3, characterized in that: The electrode layer is an electrode suitable for a capacitive sensor; preferably, the electrode layer is an ITO / PET electrode.

5. The method for preparing a porous PDMS sponge-based underwater pressure sensor according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: preparing a porous elastomeric dielectric layer; assembling a porous elastomer dielectric layer and an electrode layer; Then, an encapsulation layer is used for waterproof packaging to obtain a porous PDMS sponge-based underwater pressure sensor.

6. The preparation method according to claim 5, characterized in that The preparation method of the porous elastomeric dielectric layer includes: uniformly mixing a polydimethylsiloxane prepolymer, a platinum curing agent, an emulsifier, and a non-polar solvent to obtain a precursor solution; injecting a mixed solution of water and the precursor solution into a mold through microfluidic injection, and obtaining a PDMS sponge with a porous structure through thermal curing; and immersing the porous PDMS sponge in an ionic liquid and squeezing out excess ionic liquid to obtain a porous elastomeric dielectric layer.

7. The preparation method according to claim 6, characterized in that The emulsifier is selected from at least one of Span 60, Span 80, and Span 85; the non-polar solvent includes at least one of n-hexadecane, n-pentadecane, and n-hexane; preferably, in the precursor solution, the mass ratio of polydimethylsiloxane prepolymer, platinum curing agent, emulsifier, and non-polar solvent is 1: (0.09-0.15): (0.02-0.04): (0.5-2).

8. The preparation method according to claim 6 or 7, characterized in that The heat curing temperature is 80-100° C., and the heat curing time is 6-12 hours.

9. The preparation method according to any one of claims 5 to 8, characterized in that The method for assembling the porous elastomer dielectric layer and the electrode layer is as follows: cutting the electrode layer to a suitable size, coating the upper surface and the lower surface of the porous elastomer dielectric layer with adhesive respectively, and then placing the electrode layer.

10. Use of the porous PDMS sponge-based underwater pressure sensor according to any one of claims 1 to 4 in underwater pressure monitoring.

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