Underwater wearable triboelectric sensor based on flexible ionic gel electrode and preparation method thereof

Abstract

The application discloses an underwater wearable triboelectric sensor based on a flexible ionic gel electrode and a preparation method thereof, which comprises a bottom packaging layer, a first shielding layer, a second shielding layer and a top packaging layer stacked in sequence along the vertical direction; a flexible ionic gel electrode assembly is arranged between the first shielding layer and the second shielding layer; the bottom packaging layer or the top packaging layer is used for generating triboelectric charges when contacting with human skin; the first shielding layer and the second shielding layer are used for inhibiting environmental stray electric field interference and reducing triboelectric charge dissipation; and the flexible ionic gel electrode assembly is used for collecting induced charges and outputting a periodic alternating electric signal. The application solves the problem that the existing sensor generally relies on a rigid electrode and is easily affected by the outside world, leading to unstable electric signals and difficult long-term reliable work in a complex underwater environment; in addition, the existing single-electrode triboelectric sensor has poor airtightness and is prone to water seepage when working underwater, which greatly reduces the environmental adaptability of the sensor.

Description

Technical Field

[0001] This invention relates to the field of triboelectric sensor technology, and in particular to an underwater wearable triboelectric sensor based on a flexible ion gel electrode and its fabrication method. Background Technology

[0002] Currently, traditional underwater wearable sensors typically rely on rigid electrodes. However, these electrodes are susceptible to moisture intrusion, humidity, pressure changes, and mechanical dynamic deformation, leading to unstable electrical signals and making it difficult to operate reliably in complex underwater environments for extended periods. Furthermore, existing single-electrode triboelectric sensors often employ a sandwich-style structure with poor sealing, making them prone to water leakage during underwater operation and significantly reducing the sensor's environmental adaptability. Summary of the Invention

[0003] This invention provides an underwater wearable triboelectric sensor based on a flexible ion gel electrode and its fabrication method to overcome the aforementioned technical problems.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: An underwater wearable triboelectric sensor based on a flexible ion gel electrode includes a bottom encapsulation layer, a second shielding layer, a first shielding layer, and a top encapsulation layer stacked vertically in sequence; a flexible ion gel electrode assembly is disposed between the first shielding layer and the second shielding layer; the bottom encapsulation layer or the top encapsulation layer is used to generate triboelectric charge when in contact with human skin; the first shielding layer and the second shielding layer are used to suppress interference from environmental stray electric fields and reduce triboelectric charge dissipation; the flexible ion gel electrode assembly is used to collect induced charges and output a periodic alternating electrical signal.

[0005] Furthermore, both the bottom encapsulation layer and the top encapsulation layer are made of Ecoflex00-20 silicone rubber.

[0006] Furthermore, the first and second shielding layers are made of cast polypropylene.

[0007] Furthermore, the flexible ion gel electrode assembly is composed of two flexible ion gel electrodes stacked together, and the preparation method of each flexible ion gel electrode is as follows: S101: A mixture is formed by mixing hydroxyethyl acrylate monomer, 2-methoxyethyl acrylate monomer and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent in a certain mass ratio. S102: Add anhydrous ethanol solution of the prepared photoinitiator 184 to the mixture and stir at room temperature to obtain a precursor mixture solution; S103: After drying the precursor mixture solution, it is poured into a glass mold treated with a release agent, and then irradiated under ultraviolet light to finally obtain a flexible ion gel electrode.

[0008] Furthermore, the mass of the anhydrous ethanol solution of the photoinitiator 184 accounts for 1% of the total mass of the hydroxyethyl acrylate monomer, the 2-methoxyethyl acrylate monomer, and the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent.

[0009] Furthermore, the mass ratio of the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent, the hydroxyethyl acrylate monomer, and the 2-methoxyethyl acrylate monomer is any one of 0.5:1:1, 0.75:1:1, 1:1:1, and 1.25:1:1.

[0010] A method for fabricating an underwater wearable triboelectric sensor based on a flexible ion-gel electrode, specifically including the following steps: S1: Mix component A and component B of Ecoflex 00-20 silicone rubber evenly at a mass ratio of 1:1, and pour into a pre-set 3D printing mold; S2: Place the 3D printed mold in a 45℃ oven to cure for 1 h to form a bottom encapsulation layer; then prepare two flexible ion gel electrodes and label them as electrode A and electrode B respectively; place electrode A on electrode B to form a flexible ion gel electrode assembly. S3: The first shielding layer and the second shielding layer are respectively attached to the upper surface of electrode A and the lower surface of electrode B to form a CPP / ion gel composite structure. S4: Place a copper wire between the two ion gel electrodes, namely electrode A and electrode B, on the side where the first shielding layer and the second shielding layer are not attached, to form a sandwich electrode structure containing CPP - flexible ion gel - CPP. S5: Place the sandwich electrode structure in the center of the solidified bottom encapsulation layer, then obtain the top encapsulation layer in the same way as obtaining the bottom encapsulation layer, and make the top encapsulation layer completely cover the sandwich electrode structure and combine it with the bottom encapsulation layer to obtain a completely sealed underwater wearable triboelectric sensor.

[0011] Beneficial effects: This invention provides an underwater wearable triboelectric sensor based on a flexible ion gel electrode, comprising a bottom encapsulation layer, a first shielding layer, a second shielding layer, and a top encapsulation layer stacked vertically. Specifically, this invention constructs a synergistic water-blocking encapsulation structure using a CPP shielding layer and an Ecoflex encapsulation layer, effectively reducing the interference of the aquatic environment on the charge transfer process. Simultaneously, the flexible ion gel electrode in the flexible ion gel electrode assembly possesses stable ion conductivity and excellent environmental stability, enabling the output of periodic alternating electrical signals in complex underwater environments to achieve stable, rapid, and highly sensitive motion sensing. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the multilayer structure of the underwater wearable triboelectric sensor based on a flexible ion gel electrode according to the present invention. Figure 2 This is the electrochemical impedance spectroscopy of the flexible ion-gel electrode in this embodiment; Figure 3 This is a schematic diagram of the overall sensor structure and a photograph taken in this embodiment; Figure 4 These are the test results for sensor response time and recovery time in this embodiment; Figure 5 This is a graph showing the relationship between the sensor output voltage and the operating frequency in this embodiment; Figure 6 This is a test image showing the sensor's stable operation underwater for an extended period of time in this embodiment; Figure 7 This is a schematic diagram of the sensor detecting finger bending motion underwater in this embodiment; Figure 8 This is a schematic diagram of the working mechanism of the sensor triboelectric nanogenerator in this embodiment.

[0014] In the figure: 1. Top encapsulation layer; 2. First shielding layer; 3. Flexible ion gel electrode assembly; 4. Second shielding layer; 5. Bottom encapsulation layer. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] This embodiment provides an underwater wearable triboelectric sensor based on a flexible ion gel electrode, comprising a bottom encapsulation layer 5, a first shielding layer 2, a second shielding layer 4, and a top encapsulation layer 1 stacked vertically; a flexible ion gel electrode assembly 3 is disposed between the first shielding layer 2 and the second shielding layer 4; the bottom encapsulation layer 5 or the top encapsulation layer 1 is used to generate triboelectric charge when in contact with human skin; the first shielding layer 2 and the second shielding layer 4 are used to suppress interference from environmental stray electric fields and reduce triboelectric charge dissipation; the flexible ion gel electrode in the flexible ion gel electrode assembly 3 is used to collect induced charges and output a periodic alternating electrical signal. The bottom encapsulation layer 5 and the top encapsulation layer 1 are both made of Ecoflex 00-20 silicone rubber. The first shielding layer 2 and the second shielding layer 4 are made of cast polypropylene.

[0017] The structural schematic diagram of the underwater wearable triboelectric sensor involved in this embodiment is shown below. Figure 1 As shown, the sensor consists of a multi-layer structure: the outermost layer is an Ecoflex encapsulation layer (including a bottom encapsulation layer 5 and a top encapsulation layer 1). Ecoflex is a highly electron-gathering material in the triboelectric series, and it easily becomes negatively charged when in contact with skin, nylon, etc. Furthermore, once cured, it has no internal pores or channels, and can prevent water from penetrating the electrodes during long-term underwater immersion, thus avoiding short circuits and leakage. The interior includes a CPP shielding layer (i.e., a first shielding layer 2 and a second shielding layer 4) to suppress stray electric fields from the environment and reduce triboelectric charge leakage. The core of the sensor in this embodiment is the flexible ion gel electrode assembly 3. Figure 1 The diagram shows the arrangement and positional relationships between the layers, providing a clear reference for subsequent production methods.

[0018] Specifically, this embodiment employs a one-pot photopolymerization process to prepare the flexible ionogel electrode 3. The mechanical and electrical properties of the flexible ionogel electrode assembly 3 are synergistically controlled by adjusting the mass ratio of two acrylate monomers—hydroxyethyl acrylate (HEA) and 2-methoxyethyl acrylate (MEA)—to the ionic liquid solvent 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM][TFSI]). Specifically, in this embodiment, the double bonds of the selected hydroxyethyl acrylate participate in free radical polymerization to form a covalently cross-linked polyacrylate backbone, ensuring a stable, elastic, and non-flowing gel shape. Furthermore, the hydroxyethyl acrylate contains a large number of hydroxyl functional groups, further endowing the gel electrode with excellent properties such as high toughness and self-healing. The 2-methoxyethyl acrylate has a longer and more flexible side chain, which can significantly improve the gel stretchability. 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is a typical hydrophobic ionic liquid. This material is almost non-volatile and has high chemical stability, while also exhibiting high compatibility with acrylate monomers. It is the core of the ionic gel's "conductive, extreme-environment-resistant, and long-lasting" properties. Specifically, in this embodiment, the mass ratio of the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid solvent, hydroxyethyl acrylate monomer, and 2-methoxyethyl acrylate monomer, i.e., [EMIM][TFSI]:HEA:MEA, is any one of 0.5:1:1, 0.75:1:1, 1:1:1, and 1.25:1:1. This embodiment uses a mass ratio of 0.5:1:1 as an example to illustrate the specific preparation process of the flexible ionic gel electrode 3. The flexible ionic gel electrode assembly 3 is composed of two stacked flexible ionic gel electrodes, and the preparation method of the flexible ionic gel electrode is as follows: S100: Prepare an anhydrous ethanol solution of photoinitiator 184 with a concentration of 1 g / mL; Specifically, the method for preparing the anhydrous ethanol solution of photoinitiator 184 is as follows: Weigh 10.0000g of photoinitiator 184, i.e., 1-hydroxycyclohexylphenyl ketone, using an electronic balance and pour it into a 50 mL beaker; add 7–8 mL of anhydrous ethanol to the beaker, and then stir with a magnetic stirrer or a glass rod until completely clear and transparent; then transfer the completely clear and transparent solution along the glass rod into a 10 mL volumetric flask; finally, add anhydrous ethanol to the 10 mL mark, shake well, and you will get a 1 g / mL anhydrous ethanol solution of photoinitiator 184. S101: Add a certain mass ratio of hydroxyethyl acrylate monomer, 2-methoxyethyl acrylate monomer, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent to a pre-placed empty glass bottle. Specifically, in this embodiment, 0.5g of [EMIM][TFSI] ionic liquid solvent, 1g of HEA monomer, and 1g of MEA monomer are added to the glass bottle in sequence. S102: Add 0.025 g of the prepared anhydrous ethanol solution of photoinitiator 184, and magnetically stir for 20 min at room temperature to form a homogeneous and transparent precursor mixture solution; and the mass of the anhydrous ethanol solution of photoinitiator 184 accounts for 1% of the total mass of hydroxyethyl acrylate monomer, 2-methoxyethyl acrylate monomer, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent. S103: The precursor mixture solution is placed in a vacuum oven at 60°C for drying to remove residual ethanol and reduce bubble defects during polymerization. The dried precursor solution is then poured into a glass mold treated with a release agent. The mold has dimensions of 38×8×1 mm³. Subsequently, it is irradiated under 365nm ultraviolet light for 10 minutes to allow it to undergo free radical polymerization and completely solidify, ultimately obtaining a flexible ion gel electrode.

[0019] The flexible ion gel electrode assembly 3 obtained in this embodiment possesses high mechanical flexibility, inherent ion conductivity, and excellent environmental stability. It can maintain structural integrity and stable conductivity under significant stretching, bending, and torsion conditions, making it suitable as a flexible electrode in underwater wearable triboelectric sensors. The molecular reaction of the flexible ion gel electrode is as follows:

[0020] A method for fabricating an underwater wearable triboelectric sensor based on a flexible ion gel electrode is disclosed. In this embodiment, the designed underwater wearable triboelectric sensor employs a five-layer sandwich structure, including a bottom encapsulation layer 5, a first shielding layer 2, a flexible ion gel electrode assembly 3, a second shielding layer 4, and a top encapsulation layer 1. The specific steps include: S1: Mix component A and component B of Ecoflex 00-20 silicone rubber evenly at a mass ratio of 1:1, and pour the mixture into a pre-placed 3D printing mold with a mold size of 40×15×6 mm³. S2: Place the 3D printed mold in a 45℃ oven to cure for 1 h to form the bottom encapsulation layer 5; then prepare two flexible ion gel electrodes with a size of 10×8×1 mm³ and label them as electrode A and electrode B respectively; place electrode A on electrode B to form a flexible ion gel electrode assembly 3. S3: The first shielding layer 2 and the second shielding layer 4 are respectively attached to the upper surface of electrode A and the lower surface of electrode B to form a CPP / ion gel composite structure. S4: A copper wire is placed between the two ion gel electrodes, namely electrode A and electrode B, on the side where the first shielding layer 2 and the second shielding layer 4 are not attached, to establish an external electrical connection, thereby forming a sandwich electrode structure containing CPP - flexible ion gel - CPP. S5: Place the sandwich electrode structure in the center of the cured bottom encapsulation layer 5, and then obtain the top encapsulation layer 1 in the same way as obtaining the bottom encapsulation layer 5; after the top encapsulation layer 1 completely covers the sandwich electrode structure and combines with the bottom encapsulation layer 5, a completely sealed underwater wearable triboelectric sensor is obtained. Alternatively, freshly prepared Ecoflex precursor is poured in again, completely covering the sandwich electrode structure and combining with the bottom encapsulation layer 5; finally, the entire structure is cured again at 45°C to obtain a completely sealed underwater wearable triboelectric sensor. Wherein: the bottom encapsulation layer 5 or the top encapsulation layer 1 is mainly used to achieve flexible encapsulation and triboelectric charge generation; the first shielding layer 2 and the second shielding layer 4, i.e., the CPP film, are used to suppress stray electric field interference and reduce charge dissipation; the flexible ion gel electrode in the flexible ion gel electrode assembly 3 is used to collect induced charges and output electrical signals.

[0021] In this embodiment, a synergistic water-blocking encapsulation structure is formed by CPP film and Ecoflex encapsulation layer, which can effectively avoid problems such as water seepage, electrode expansion and interface failure in the underwater environment of traditional sandwich structures, thereby significantly improving the stability and reliability of the sensor in complex underwater environments.

[0022] The working mechanism of the underwater wearable triboelectric sensor described in this embodiment is as follows: Based on the typical working mechanism of a single-electrode triboelectric nanogenerator, this embodiment designs an underwater wearable triboelectric sensor, whose sensing principle is mainly based on the contact electrification effect and the electrostatic induction effect. When human skin or an external object comes into contact with the Ecoflex surface, triboelectric charge is generated at the contact interface due to the difference in electron gain and loss capacity between the two materials. Taking human skin as an example, the working mechanism of the sensor is explained in detail: as the human skin gradually separates from the Ecoflex surface, the capacitance between the contact interface decreases, thereby forming a potential difference between the flexible ion gel electrode and the ground. This potential difference drives the directional flow of electrons in the external circuit, thereby generating a current signal. As the separation distance between the human skin and the Ecoflex surface further increases, the system reaches the maximum separation state, at which point the sensor corresponds to the maximum open-circuit voltage and the maximum amount of transferred charge. When the human skin approaches the Ecoflex surface again, the interface potential changes in the opposite direction, and the electrons in the external circuit flow in the reverse direction, thereby forming a reverse current signal. Therefore, in the continuous contact-separation cycle, the sensor can continuously output a periodic alternating electrical signal, realizing real-time sensing of mechanical stimuli such as human movement, knocking, and bending. In underwater environments, traditional single-electrode triboelectric sensors are susceptible to the effects of water's dielectric constant and conductivity, leading to charge shielding and leakage problems. In this embodiment, a synergistic water-blocking encapsulation structure is constructed using a CPP shielding layer and an Ecoflex encapsulation layer, effectively reducing the interference of the aquatic environment on the charge transfer process. Simultaneously, the flexible ion-gel electrode assembly 3 possesses stable ionic conductivity and excellent environmental stability, maintaining stable output even in long-term underwater environments. Therefore, the underwater wearable triboelectric sensor designed in this embodiment can achieve stable, rapid, and highly sensitive motion sensing in complex underwater environments.

[0023] Compared with existing technologies, the underwater wearable triboelectric sensor described in this embodiment has the following advantages: 1. High-performance flexible ionogel electrode design: A highly flexible ionogel electrode, prepared by photoinitiated polymerization of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt (EMIM TFSI) ionic liquid solvent and hydroxyethyl acrylate / 2-methoxyethyl acrylate (HEA / MEA) comonomer, possesses both high mechanical tensile strength and inherent ionic conductivity. The flexible electrode can withstand significant deformation without damage, providing comfort and reliability for wearable applications.

[0024] 2. Innovative Packaging Process: By co-casting CPP film and silicone rubber, moisture intrusion is effectively prevented, avoiding electrode expansion and interface failure. The CPP film serves as an insulating shielding layer to suppress stray electric fields and reduce charge dissipation. Compared to traditional sandwich packaging, the co-packaging method proposed in this embodiment can effectively eliminate interference caused by the underwater environment, ensuring stable operation of the TENG underwater.

[0025] 3. High Response Speed ​​and Signal Sensitivity: The underwater wearable triboelectric sensor designed in this embodiment features a fast response time of 36 milliseconds and a recovery time of 45 milliseconds, which is superior to most existing flexible wearable sensors (the response time of existing wearable sensors is approximately 100 milliseconds). This ultra-fast response characteristic enables the sensor to accurately capture instantaneous action signals such as tapping. Simultaneously, the sensor can effectively distinguish between tapping actions of different frequencies, with a regression coefficient as high as 0.99571, demonstrating high sensitivity.

[0026] 4. Significantly improved underwater stability: Thanks to the combination of each flexible ion gel electrode and the co-encapsulation structure in the flexible ion gel electrode assembly 3, the sensor in this embodiment can work stably when placed underwater for a long time (7 days), and is not affected by charge shielding or leakage caused by the dielectric constant and conductivity of water, and can reliably sense mechanical movements such as finger bending underwater.

[0027] In summary, this embodiment, through the combination of flexible ion-gel electrode assembly 3 and CPP+Ecoflex co-casting and encapsulation, achieves high environmental adaptability, high signal stability, and high flexibility in the underwater wearable triboelectric sensor. This significantly surpasses existing technologies and provides a new technical solution for underwater wearable sensing devices, as detailed in Table 1. Figures 2 to 8 As shown; Table 1. Performance comparison of the sensor designed in this embodiment with other flexible wearable sensors.

[0028] Figure 2 This is the electrochemical impedance spectroscopy of the flexible ion-gel electrode in the flexible ion-gel electrode assembly 3 in this embodiment. The vertical axis represents the imaginary part of the impedance, and the horizontal axis represents the real part of the impedance, showing the impedance characteristics of the electrode at low and high frequencies. This demonstrates that the electrode possesses inherent ion conductivity, providing a fundamental guarantee for a stable signal output by the sensor.

[0029] Figure 3 This diagram shows the sensor structure and actual photographs in this embodiment. The upper part is a 3D structural diagram, and the lower part is a photograph of the actual object, visually presenting the overall packaging and electrode layout. It can be clearly seen that the flexible ion gel electrode assembly 3 in this embodiment is encapsulated inside Ecoflex and does not directly contact the outside environment.

[0030] Figure 4 This is a graph showing the test results of the sensor's response time and recovery time in this embodiment. The horizontal axis represents time, and the vertical axis represents the output voltage signal, with the start of response, peak response, and recovery time points marked. This graph shows that the sensor has a sub-50 millisecond fast response capability.

[0031] Figure 5 The graph shows the relationship between the sensor current signal and the operating frequency in this embodiment. The regression coefficient of the fitted curve in the graph is as high as 0.99571, which reflects that the sensor has excellent frequency sensitivity and provides a basis for sensing dynamic actions.

[0032] Figure 6 This figure shows the test results of the sensor's stable operation underwater for an extended period in this embodiment. The figure displays the output voltage change of the sensor after seven consecutive days of underwater placement. This illustrates that the CPP+Ecoflex co-packaging structure effectively prevents water infiltration while maintaining the electrical performance of the electrodes, ensuring the sensor's long-term reliable operation underwater.

[0033] Figure 7 This is a schematic diagram illustrating the sensor's detection of finger bending motion underwater in this embodiment. The diagram shows the output voltage waveforms corresponding to different finger bending angles (30°, 60°, 90°). This diagram demonstrates that the sensor can distinguish different bending amplitudes, achieving motion recognition functionality, and also verifies the sensor's signal stability and resolution capability underwater.

[0034] Figure 8 This is a schematic diagram of the sensor's working mechanism in this embodiment, describing the principle of a single-electrode triboelectric nanogenerator, including the charge transfer and triboelectric power generation process between human skin A (contact), Ecoflex encapsulation B, CPP shielding layer C, and flexible ion gel electrode assembly 3.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An underwater wearable triboelectric sensor based on a flexible ion-gel electrode, characterized in that, It includes a bottom encapsulation layer (5), a second shielding layer (4), a first shielding layer (2), and a top encapsulation layer (1) stacked vertically; and a flexible ion gel electrode assembly (3) is provided between the first shielding layer (2) and the second shielding layer (4); the bottom encapsulation layer (5) or the top encapsulation layer (1) is used to generate triboelectric charge when in contact with human skin; the first shielding layer (2) and the second shielding layer (4) are used to suppress environmental stray electric field interference and reduce triboelectric charge dissipation; the flexible ion gel electrode assembly (3) is used to collect induced charge and output a periodic alternating electric signal.

2. The underwater wearable triboelectric sensor based on a flexible ion-gel electrode according to claim 1, characterized in that, The bottom encapsulation layer (5) and the top encapsulation layer (1) are both made of Ecoflex00-20 silicone rubber.

3. The underwater wearable triboelectric sensor based on a flexible ion-gel electrode according to claim 2, characterized in that, The first shielding layer (2) and the second shielding layer (4) are made of cast polypropylene.

4. The underwater wearable triboelectric sensor based on a flexible ion-gel electrode according to claim 3, characterized in that, The flexible ion gel electrode assembly (3) is composed of two flexible ion gel electrodes stacked together, and the preparation method of each flexible ion gel electrode is as follows: S101: A mixture is formed by mixing hydroxyethyl acrylate monomer, 2-methoxyethyl acrylate monomer and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent in a certain mass ratio. S102: Add anhydrous ethanol solution of the prepared photoinitiator 184 to the mixture and stir at room temperature to obtain a precursor mixture solution; S103: After drying the precursor mixture solution, it is poured into a glass mold treated with a release agent, and then irradiated under ultraviolet light to finally obtain a flexible ion gel electrode.

5. The underwater wearable triboelectric sensor based on a flexible ion-gel electrode according to claim 4, characterized in that, The anhydrous ethanol solution of photoinitiator 184 accounts for 1% of the total mass of the hydroxyethyl acrylate monomer, 2-methoxyethyl acrylate monomer, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent.

6. The underwater wearable triboelectric sensor based on a flexible ion-gel electrode according to claim 5, characterized in that, The mass ratio of the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid solvent, hydroxyethyl acrylate monomer, and 2-methoxyethyl acrylate monomer is any one of 0.5:1:1, 0.75:1:1, 1:1:1, and 1.25:1:

1.

7. A method for fabricating an underwater wearable triboelectric sensor based on a flexible ionogel electrode as described in any one of claims 1 to 6, characterized in that, The specific steps include: S1: Mix component A and component B of Ecoflex 00-20 silicone rubber evenly at a mass ratio of 1:1, and pour into a pre-set 3D printing mold; S2: Place the 3D printed mold in a 45℃ oven for 1 h to form a bottom encapsulation layer (5); then prepare two flexible ion gel electrodes and label them as electrode A and electrode B respectively; place electrode A on electrode B to form a flexible ion gel electrode assembly (3). S3: The first shielding layer (2) and the second shielding layer (4) are respectively attached to the upper surface of electrode A and the lower surface of electrode B to form a CPP / ion gel composite structure. S4: Place a copper wire between the two ion gel electrodes, namely electrode A and electrode B, on the side where the first shielding layer (2) and the second shielding layer (4) are not attached, to form a sandwich electrode structure containing CPP-flexible ion gel-CPP. S5: Place the sandwich electrode structure in the center of the solidified bottom encapsulation layer (5), and then obtain the top encapsulation layer (1) in the same way as obtaining the bottom encapsulation layer (5). After the top encapsulation layer (1) completely covers the sandwich electrode structure and is combined with the bottom encapsulation layer (5), a completely sealed underwater wearable triboelectric sensor is obtained.

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