Mechanical energy collecting device based on bionic structure and preparation method thereof

Abstract

The invention belongs to the technical field of energy collection, and particularly relates to a mechanical energy collection device based on a bionic structure and a preparation method thereof. The mechanical energy collecting device comprises a polytetrafluoroethylene planar film, a water film, a first electrode, a second electrode, a carbon black film and a porous polytetrafluoroethylene film, the carbon black film is arranged on the porous polytetrafluoroethylene film, the first electrode and the second electrode are arranged on the carbon black film, the water film is arranged on the carbon black film, and the polytetrafluoroethylene planar film is arranged on the water film. According to the invention, the porous membrane is loaded with carbon black to form an electric bilayer with a random porous microstructure, and an ion transport mechanism of a natural plant is simulated. Along with the increase of the pressure, the contact area of the micro-structure electric double-layer coupling capacitor in the solid-liquid channel is increased, and the stored charge quantity is correspondingly increased, which is similar to a liquid charge pump mechanism, so that the energy conversion efficiency of the device is improved.

Description

Technical Field

[0001] This invention belongs to the field of energy harvesting technology, specifically relating to a mechanical energy harvesting device based on a biomimetic structure and its preparation method. Background Technology

[0002] With the rapid development of the Internet of Things (IoT) and smart devices, especially in the application of remote sensors, wearable devices, and automated systems, traditional energy supply methods (such as battery replacement) face problems such as high costs, environmental pollution, and maintenance difficulties. Environmental mechanical energy harvesting technology provides a solution to this problem by collecting mechanical energy from the surrounding environment, such as vibration, wind energy, and human movement, and converting it into electrical energy to power the autonomous operation of the equipment.

[0003] Through piezoelectric effect and triboelectric nanotechnology, clean energy supply with zero pollution and no consumables can be achieved, complementing solar and wind power and enhancing the resilience and coverage of energy systems. Despite challenges such as low energy density and material durability, breakthroughs in nanomaterials and biomimetic coatings are rapidly improving its efficiency and economics. In the future, it may become an "invisible power grid" in smart cities, industrial energy conservation, and even space exploration, capturing energy in a small but continuous manner to drive humanity's transition to a carbon-free society and embody the sustainable development concept of "nature empowering humanity."

[0004] Solid-liquid hybrid generators, as an emerging "blue energy" technology, utilize the kinetic and potential energy of water resources to provide innovative solutions for the field of sustainable energy. Their core value lies in converting widely distributed but unused water energy (such as rainwater, condensate, and domestic wastewater) into electricity, filling the gap in self-powered power supply scenarios. They are particularly suitable for low-power applications such as IoT devices and monitoring devices in remote areas.

[0005] Solid-liquid power generation is a technology that converts mechanical energy in the environment into electrical energy based on the physical or chemical effects between a solid and a liquid interface. It involves factors such as friction, piezoelectricity, electrostatics, and fluid dynamics at the solid-liquid interface. When a solid material (such as a piezoelectric material) comes into contact with a liquid (such as water or an electrolyte solution) and is subjected to external forces (such as vibration, waves, or water flow), energy conversion occurs at the solid-liquid interface. For example, when a piezoelectric material is subjected to external pressure or vibration, a charge difference can be generated at the solid-liquid interface, thereby generating an electric current. Solid-liquid power generation is characterized by high efficiency, low maintenance, and environmental friendliness, and is particularly suitable for energy harvesting in dynamic environments such as water flow, tides, or ocean waves. Solid-liquid power generation offers new possibilities for distributed energy systems, especially in remote areas where grid connection is difficult, becoming an important source of clean energy.

[0006] Most existing solid-liquid mode generators drive charge transfer by altering the electric double layer (EDL) at the water-solid interface due to dynamic solid-liquid contact, as illustrated in the paper (A Dual-Mode Triboelectric Nanogenerator for Efficiently Harvesting Droplet Energy. Small 20.36(2024): 2400698). Hydroelectric generators using this mode are typically only suitable for energy harvesting in open spaces and discrete distributions. Furthermore, as illustrated in the paper (Discontinuous streaming potential via liquid gate. eScience 2.6(2022): 615-622), most electromechanical conversion devices based on the EDL electrochemical principle rely on significant stress-deformation to generate output, resulting in low output performance and hindering their practical application in energy storage and power generation. Summary of the Invention

[0007] To address the above problems, the present invention provides a mechanical energy harvesting device based on a biomimetic structure, comprising a polytetrafluoroethylene (PTFE) planar membrane, a water film, a first electrode, a second electrode, a carbon black membrane, and a porous PTFE membrane; the carbon black membrane is placed on the porous PTFE membrane, the first electrode and the second electrode are placed on the carbon black membrane, the water film is placed on the carbon black membrane, and the PTFE planar membrane is placed on the water film.

[0008] The working principle of this invention is as follows: When a weak pressure is applied to the top PTFE membrane, the porous structure generates a capillary hydraulic effect, driving the water film to penetrate vertically and drastically increasing the solid-liquid contact area. Water molecules and the carbon black layer instantly form a double-layer charge pump, accumulating a high-density ionic charge at the interface. Simultaneously, the PTFE / water interface triggers an asymmetric double layer, establishing an ion concentration gradient. Furthermore, due to its low work function, the liquid metal can block electron backflow, resulting in a reverse current attenuation of over 90%, achieving highly efficient self-rectified output. Mechanical energy is directly converted into stable direct current, output through the liquid metal-carbon black electrode, completing a closed-loop energy cycle of "mechanical triggering - interface energy storage - DC power supply".

[0009] This invention utilizes the polarization characteristics of water by the triboelectric field and the synergistic effect of redox reactions to establish a charge transport channel with ion-electron coupling at the solid-liquid-solid interface. The extraction of triboelectric charge is enhanced by triggering external mechanical force, thus solving the problems of high impedance and complex device structure in current triboelectric power generation devices.

[0010] This invention utilizes carbon black loaded onto a porous membrane to form an EDL with a random porous microstructure, mimicking the ion transport mechanism of natural plants. As pressure increases, the contact area of ​​the coupling capacitors in the microstructured EDL within the solid-liquid channel increases, and the amount of stored charge also increases accordingly, similar to a liquid charge pump mechanism, thereby improving the energy conversion efficiency of the device.

[0011] Furthermore, the surface of the porous PTFE membrane undergoes surface activation treatment. The main function of plasma treatment is to make the hydrophobic porous PTFE membrane hydrophilic, thereby improving its water permeability and enhancing its surface adhesion.

[0012] Furthermore, the work functions of the first and second electrodes are different. Due to the difference in work functions between the two electrodes, a built-in electric field is formed at their interface. Moreover, the liquid metal is more easily wetted by the conductive ionic liquid (water), and the surface atoms are dispersed with abundant free electrons. The EDL charge density formed at the interface with water is higher, and the two couple to enhance the signal output.

[0013] Furthermore, the first electrode is a strip-shaped silver electrode, and the second electrode is a strip-shaped silver electrode coated with liquid metal. Coating the surface of the silver electrode with liquid metal has the core advantage that the silver electrode is the only substrate that combines resistance to liquid metal corrosion, ultra-high conductivity, and biocompatibility, making the coating system irreplaceable in flexible electronics.

[0014] Furthermore, the liquid metal is a gallium indium tin system.

[0015] Furthermore, the thickness of the water film is 50-200 micrometers.

[0016] Furthermore, the thickness of the polytetrafluoroethylene planar film is 50-150 micrometers.

[0017] Furthermore, the surface of the PTFE planar membrane has oriented micropores, the direction of which is consistent with the impact direction of water droplets. This oriented microporous structure is essentially a biomimetic fluid gating system (similar to plant stomata). Through the combination of geometric orientation and hydrophobic chemistry, it strengthens the waterproof barrier under dynamic impact, while optimizing the breathability / drainage path, achieving a balance between intelligent protection and comfort.

[0018] On the other hand, the present invention provides a method for preparing a mechanical energy harvesting device based on a biomimetic structure, comprising the following steps: Step 1: Place the porous polytetrafluoroethylene membrane in a plasma treatment device for surface activation treatment; Step 2: Coat the activated porous polytetrafluoroethylene membrane with carbon black to form a carbon black membrane; Step 3: Set the first electrode and the second electrode on the carbon black film; Step 4: Spray deionized water onto the surface of the carbon black film using a sprayer to form a continuous water film; Step 5: Encapsulate the first electrode, the second electrode, and the water film surface with a polytetrafluoroethylene planar film.

[0019] Furthermore, the work functions of the first and second electrodes are different.

[0020] The beneficial effects of this invention are: (1) This invention adapts to the microstructure of carbon black surface by utilizing the zero modulus characteristics of liquid metal electrodes and combines the capillary hydraulic amplification effect of porous PTFE membranes. Under small stress-deformation, the solid-liquid interface double electric layer charge pump mechanism can be triggered, breaking through the dependence of traditional triboelectric devices on macroscopic mechanical deformation.

[0021] (2) The liquid metal electrode of the present invention forms an ultra-low resistance flexible interface with the carbon black layer, eliminating charge transmission loss; the capillary hydraulic effect of the porous structure converts weak mechanical energy into a geometrically increasing solid-liquid contact area, triggering the avalanche release of double-layer charge; in addition, due to its low work function, the liquid metal can block electron backflow, and the reverse current decays by more than 90%, realizing efficient self-rectification output, breaking through the multiple physical bottlenecks of the traditional energy conversion mode, and realizing the synergistic multiplication of microscopic effect to macroscopic electrical energy.

[0022] (3) The present invention has significant advantages in energy storage and power supply applications; these advantages stem from its solid-liquid synergistic energy cycle mechanism. The molecular-level double-layer charge pump converts weak mechanical energy into ultra-high density interface energy storage (supercapacitor-like characteristics) through microporous hydraulic effect, and the liquid metal electrode achieves zero-loss charge capture; and through the low work function of the liquid metal, it achieves efficient self-rectified output, forming a direct conversion chain of "mechanical energy-ion energy-electrical energy", eliminating the multi-stage conversion losses of traditional energy storage systems; its self-powered characteristics and micro-pressure triggering capability can continuously capture energy from environmental vibrations without external power supply, building an efficient, stable, and self-sustaining energy supply ecosystem for microelectronic devices.

[0023] (4) This invention achieves precise localized control of the solid-liquid interface through a closed porous microstructure, converting random environmental energy into directional ion flow; the integrated design eliminates interface volatilization and ion dissipation in open systems, maintaining the stability of double-layer energy storage; the microcavity hydraulic coupling effect breaks through the energy barrier fragmentation of discrete units, forming a collaborative energy amplification network, realizing the full-chain integration of mechanical energy capture-storage-output in a limited space, providing a continuous, stable, and interference-resistant self-powered solution for microelectronic devices.

[0024] (5) The present invention has a simple structure. Through the alternating layering design of solid materials and liquid media, a highly efficient energy conversion interface is formed. The present invention abandons complex multi-layer stacking or external circuits. It uses a solid substrate (porous polytetrafluoroethylene membrane) as the support layer, an intermediate liquid layer (such as a water film) as the charge transport medium, and a functional solid layer (hydrophobic PTFE planar membrane) on top. Through the synergistic effect of solid-liquid-solid, the efficient conversion of mechanical energy into electrical energy is achieved.

[0025] (6) The present invention uses flexible polytetrafluoroethylene planar film, water, and liquid metal; the manufacturing process is simple and does not require complex equipment; it operates at room temperature and pressure and does not require expensive equipment; the material utilization rate is high and waste is reduced.

[0026] Based on the above beneficial effects, this invention has good application prospects in the field of energy harvesting technology. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a mechanical energy harvesting device based on a biomimetic structure.

[0028] Figure 2 This is a schematic diagram illustrating the working principle of the present invention.

[0029] Figure 3 This is a comparison diagram of the short-circuit current of the device under the conditions of no water film (left side) and with water film (right side).

[0030] Figure 4 This refers to the short-circuit current in the sliding mode of this invention.

[0031] Figure 5 This refers to the short-circuit current under ultrasound in this invention.

[0032] Figure 6 This refers to the short-circuit current in the hybrid mode of this invention.

[0033] In the figure: 1. Polytetrafluoroethylene planar membrane; 2. Water membrane; 31. First electrode; 32. Second electrode; 4. Carbon black membrane; 5. Porous polytetrafluoroethylene membrane. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments.

[0035] Example 1 This embodiment provides a mechanical energy harvesting device based on a biomimetic structure, such as Figure 1As shown, the structure includes a polytetrafluoroethylene (PTFE) planar membrane 1, a water film 2, a first electrode 31, a second electrode 32, a carbon black film 4, and a porous PTFE membrane 5. The carbon black film 4 is placed on the porous PTFE membrane 5; the first electrode 31 and the second electrode 32 are placed on the carbon black film 4; the water film 2 is placed on the carbon black film 4; and the PTFE planar membrane 1 is placed on the water film 2. The porous PTFE membrane 5 is gradient porous with a porosity of 60%-85% and a thickness of 0.5-3 mm. The surface of the porous PTFE membrane 5 has undergone surface activation treatment. The work functions of the first electrode 31 and the second electrode 32 are different. The first electrode 31 is a strip-shaped silver electrode, and the second electrode 32 is a strip-shaped silver electrode coated with liquid metal; the liquid metal is a gallium-indium-tin system. The thickness of the water film 2 is 50-200 micrometers. The first electrode 31 and the second electrode 32 are arranged in parallel at intervals at the contact interface between the porous polytetrafluoroethylene membrane 5 and the water film 2. The first electrode 31 and the second electrode 32 directly form a charge exchange interface with the water film 2, forming a stacked structure of solid layer-liquid layer-solid layer. The polytetrafluoroethylene planar membrane 1 is a dense thin film with a thickness of 50-150 micrometers and a contact angle >150°. The polytetrafluoroethylene planar membrane 1 has oriented micropores, and the direction of the micropores is consistent with the direction of water droplet impact. In application, the first electrode 31 and the second electrode 32 are connected by external wires to form a complete closed loop.

[0036] Figure 2 This is a schematic diagram illustrating the working principle of the biomimetic mechanical energy harvesting device of the present invention. The working mechanism of the device can be divided into two stages: static and dynamic. In the static state, the top layer of polytetrafluoroethylene (PTFE) planar membrane 1 remains stationary, and PTFE planar membrane 1 does not contact the water film 2, resulting in no significant triboelectric effect or charge transfer, and no significant formation of an electric bilayer. Simultaneously, at the liquid-solid interface (water film 2 and carbon black layer 4), due to the carbon black loading in the porous PTFE membrane 5, an electric bilayer with a random porous microstructure is formed. This structure simulates the ion transport mechanism of natural plants and exhibits good charge storage and transport characteristics. In the contact stage, with the increase of pressure, the contact area of ​​the microstructure EDL coupling capacitor in the solid-liquid channel increases, and the amount of stored charge increases accordingly. Specifically, the negative charge on the PTFE planar membrane is enhanced, leading to the increase of H3O in the water. + Ions migrate towards the carbon black. The COO⁻ groups on the carbon black surface adsorb H₃O⁺, thus thickening the EDL (electrode density layer), and the liquid metal begins to release electrons. These electrons flow through the external circuit to the silver electrode (first electrode 31), generating a stable positive direct current (approximately 5-10 μA / cm). 2During the separation stage, the negative charge on the PTFE planar membrane 1 remains continuously, and some H3O⁺ ions diffuse, while a redox reaction (COOH ⇔ COO⁻ + H⁺) occurs on the carbon black surface. This dynamic equilibrium ion distribution forms a stable charge transfer mechanism. Furthermore, due to its low work function, the liquid metal can block electron backflow, resulting in a reverse current attenuation of over 90%, achieving highly efficient self-rectified output.

[0037] Figure 3 The short-circuit current images of the device are shown in the cases of no water film (left) and with water film (right). The signal is represented as discrete pulses varying over time, reflecting the charge transfer process at the solid-liquid-solid interface caused by contact separation or ultrasonic action. The positive and negative half-axis signals of the current pulses indicate the flow characteristics of electrons within the system during contact and separation, demonstrating the device's DC-like output characteristics. Further analysis shows that the current of the device is 10µA without water film 2, while it rises to nearly 50µA with water film 2. This indicates that water film 2 is not only the basis for the device's conductivity and power generation, but also forms an EDL with a random porous microstructure through carbon black loaded on the porous membrane, thus simulating the ion transport mechanism of natural plants. With further increase in pressure, the contact area of ​​the EDL coupling capacitor in the solid-liquid channel further increases, and the amount of stored charge also increases accordingly, similar to the mechanism of a liquid charge pump, significantly improving the energy conversion efficiency of the device, thereby achieving efficient utilization of the triboelectric effect and efficient charge transfer.

[0038] This invention, when pressed by external force, enhances the negative charge of the polytetrafluoroethylene planar film 1 → H3O⁺ migrates towards the carbon black electrode → COO on the carbon black surface - The adsorption of H3O⁺ thickens the EDL → the liquid metal releases electrons → the electrons flow to the silver electrode through the external circuit, generating a positive DC current.

[0039] Example 2 This embodiment provides a method for preparing a mechanical energy harvesting device based on a biomimetic structure, including the following steps: Step 1: Place the porous polytetrafluoroethylene membrane 5 in a plasma treatment device for surface activation treatment.

[0040] Specifically, the plasma treatment gas is a mixture of oxygen and argon in a volume ratio of 1:3, the treatment pressure is 10-30 Pa, and after treatment, the oxygen concentration on the surface of the porous polytetrafluoroethylene membrane 5 increases by ≥20%, and the contact angle decreases from the initial 120-140° to 80-100°.

[0041] Step 2: Coat the activated porous polytetrafluoroethylene membrane 5 with carbon black to form a carbon black membrane 4.

[0042] Specifically, carbon black is coated by a blade coating method, with a coating thickness of 10-50 micrometers.

[0043] Step 3: Set the first electrode 31 and the second electrode 32 on the carbon black film 4.

[0044] Specifically, the work functions of the first electrode 31 and the second electrode 32 are different. The first electrode 31 and the second electrode 32 are coplanar electrodes. The first electrode 31 (silver electrode) undergoes plasma treatment at a power of 70W for 300 seconds to improve surface activity. For the second electrode 32, a gallium indium tin (CITi) liquid metal is coated onto the silver electrode. Liquid metal wets more easily with conductive ionic liquids (water), and its surface atoms are dispersed with abundant free electrons, resulting in a higher EDL charge density at the interface with water.

[0045] Step 4: Spray deionized water onto the surface of the carbon black film using a sprayer to form a continuous water film 2.

[0046] Specifically, water droplets are sprayed onto the substrate using a sprayer, and the water droplets are observed until a continuous water film 2 is formed, at which point the process stops.

[0047] Step 5: Encapsulate the surface of the first electrode 31, the second electrode 32, and the water film 2 with a polytetrafluoroethylene planar film 1.

[0048] Specifically, the dense polytetrafluoroethylene planar membrane 1 has a thickness of 50-150 micrometers, a contact angle >150°, and an oriented microporous structure with the micropores aligned with the direction of water droplet impact. The upper hydrophobic polytetrafluoroethylene planar membrane 1 and the intermediate water film 2 form a solid-liquid-solid sandwich structure, resulting in higher mechanical stability of the device.

[0049] Furthermore, it also includes step 6, which, regardless of whether the device is tested in contact separation, sliding mode or mixed mode (contact separation + ultrasound), is to test the device by triggering initial charge separation through triboelectric effect, maintaining charge directional migration through redox reaction, forming a non-equilibrium double layer, and achieving continuous DC output.

[0050] Example 3 This embodiment demonstrates the testing or application of the present invention in a sliding mode. Figure 4 Its short-circuit current. From Figure 4As can be seen, in sliding mode, the device can generate a DC current of 1.5µA. The core principle of this device is based on an electrochemical conductive circuit of metal-liquid-metal series connection. Without external stimulation, the interfaces between the metal and liquid, and between the liquid and metal, are open, therefore there is no steady-state current flow, and the electrochemical circuit is not activated. The system does not generate current in the absence of external interference, and is therefore in a "static" state. However, when external pressure is applied, the liquid-metal interface changes under the influence of the electric field, causing the electrochemical reaction to initiate, thereby generating a stable DC current in the circuit. This indicates that the device can utilize external pressure changes as an excitation mechanism to instantaneously change the conductivity of the electrochemical circuit, forming an electric field channel.

[0051] Example 4 This embodiment demonstrates the testing or application of the present invention in ultrasonic mode and hybrid mode (contact separation + ultrasound). Figure 5 This represents the short-circuit current of the device under ultrasonic conditions. Figure 6 The figure represents the short-circuit current of the device in hybrid mode. It can be seen that in ultrasonic mode, the present invention can stably output a DC current of 0.5µA. In hybrid mode (contact separation + ultrasound), an electrical double-layer charge arrangement is formed through the solid-liquid-solid interface, thereby forming a coupling capacitor. This structure has interface stress-sensitive characteristics, enabling force-to-electricity conversion in low-frequency contact separation mode, and also achieving efficient conversion of mechanical energy to electrical energy in high-frequency mode (40 kHz). This innovation overcomes the limitation of existing mechanical energy generation devices that can only adapt to a single operating frequency, and can output simultaneously in two different modes, possessing significant advantages such as simple structure and low cost.

[0052] Example 5 Based on Example 1, the surface of the carbon black film 4 is designed as a microgroove branch network structure with a dendritic or leaf vein-like morphology. The grooves are 5-20 micrometers wide and 2-10 micrometers deep, formed on the carbon black film 4 using laser etching or template imprinting. This structure mimics the water transport pathway in plant leaves, possessing excellent liquid guidance and ion channel functions. Under external pressure, the groove network preferentially guides the water film into the branch channels, forming a stable and oriented solid-liquid interface, significantly improving the electric double-layer formation rate and contact area. Simultaneously, local electric field enhancement regions are easily formed at each branch node, which facilitates charge accumulation and rapid migration, thereby improving energy conversion efficiency. This microgroove design also reduces interfacial impedance and enhances the device's response sensitivity to small stresses, making it particularly suitable for continuous energy harvesting under sliding or micro-vibration driven modes. It has the advantages of simple structure, strong adaptability, and stable output.

[0053] Example 6 Based on Example 1, the surface of the carbon black film 4 is constructed into a flexible spiked structure layer, whose morphology consists of uniformly distributed micron-sized carbon black spikes with a height of 10-30 micrometers, a diameter of 2-5 micrometers, and a density of 2000-5000 spikes per square millimeter. This structure is prepared using a combination of template transfer and spraying. Under external force, this flexible spiked structure can undergo slight bending and compression deformation, increasing the actual contact area between the carbon black and the water film, while simultaneously enhancing microscopic interface disturbances, thereby rapidly inducing bilayer reconstruction and charge pump response. During the contact-separation cycle, the spiked structure can achieve adaptive deformation and recovery, maintaining stable charge transfer channels and improving the response sensitivity to weak mechanical stimuli (such as low-frequency vibrations and human touch). Furthermore, the gaps between the spikes form a microcapillary structure, which facilitates localized water accumulation and introduction, further enhancing the interfacial charge density. This design possesses excellent mechanical compliance and dynamic energy conversion capabilities, making it particularly suitable for low-stress self-powered applications such as wearable devices and flexible electronics.

[0054] In summary, this invention provides a mechanical energy harvesting device based on a biomimetic structure and its preparation method. The core innovations of this concave surface are mainly reflected in: (1) This invention utilizes the polarization characteristics of water by the triboelectric field and the synergistic effect of redox reactions to promote the transfer of triboelectric charges, thereby realizing the response of DC signals, solving the problems of high impedance and complex device structure of current triboelectric nanogenerators, and providing a simpler and more efficient solution; (2) This invention forms an EDL with random porous microstructure by loading carbon black onto a porous membrane, simulating the ion transport mechanism of natural plants; as the pressure increases, the contact area of ​​the coupling capacitor of the microstructure EDL in the solid-liquid channel increases, and the amount of stored charge also increases accordingly, similar to the liquid charge pump mechanism, thereby improving the energy conversion efficiency of the device.

[0055] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A mechanical energy harvesting device based on a biomimetic structure, characterized in that: The device includes a polytetrafluoroethylene (PTFE) planar membrane, a water film, a first electrode, a second electrode, a carbon black membrane, and a porous PTFE membrane. The carbon black membrane is placed on the porous PTFE membrane, the first electrode and the second electrode are placed on the carbon black membrane, the water film is placed on the carbon black membrane, and the PTFE planar membrane is placed on the water film.

2. The biomimetic mechanical energy harvesting device as described in claim 1, characterized in that: The surface of the porous polytetrafluoroethylene membrane is subjected to surface activation treatment.

3. The biomimetic mechanical energy harvesting device as described in claim 1, characterized in that: The work functions of the first electrode and the second electrode are different.

4. The biomimetic mechanical energy harvesting device as described in claim 3, characterized in that: The first electrode is a strip silver electrode, and the second electrode is a strip silver electrode coated with liquid metal.

5. The biomimetic mechanical energy harvesting device as described in claim 4, characterized in that: The liquid metal is a gallium indium tin system.

6. The biomimetic mechanical energy harvesting device as described in claim 1, characterized in that: The thickness of the water film is 50-200 micrometers.

7. The biomimetic mechanical energy harvesting device as described in claim 1, characterized in that: The thickness of the polytetrafluoroethylene planar film is 50-150 micrometers.

8. The biomimetic mechanical energy harvesting device as described in claim 7, characterized in that: The surface of the polytetrafluoroethylene planar film has oriented micropores, the direction of which is consistent with the direction of water droplet impact.

9. A method for preparing a mechanical energy harvesting device based on a biomimetic structure, characterized in that, Includes the following steps: Step 1: Place the porous polytetrafluoroethylene membrane in a plasma treatment device for surface activation treatment; Step 2: Coat the activated porous polytetrafluoroethylene membrane with carbon black to form a carbon black membrane; Step 3: Set the first electrode and the second electrode on the carbon black film; Step 4: Spray deionized water onto the surface of the carbon black film using a sprayer to form a continuous water film; Step 5: Encapsulate the first electrode, the second electrode, and the water film surface with a polytetrafluoroethylene planar film.

10. The method for preparing the biomimetic mechanical energy harvesting device as described in claim 9, characterized in that: The work functions of the first electrode and the second electrode are different.

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