3D printing liquid drop friction generator imitating natural leaves

Abstract

The invention relates to the technical field of new energy, in particular to a natural-leaf-imitated 3D printing liquid drop friction generator which comprises a bionic blade main body structure, a bottom electrode, a friction layer and a top electrode which are sequentially arranged from bottom to top, the bionic blade main body structure serves as a substrate, and a rigid supporting framework is formed through a bionic vein network of the bionic blade main body structure; when liquid drops impact the prismatic surface, the liquid drops axially and directionally flow along a connecting channel of the vein network and are in contact with the friction layer, charge transfer between the bottom electrode and the top electrode is induced through a solid-liquid triboelectrification effect, meanwhile, a rigid skeleton of the vein limits excessive deformation of the FEP film, the spreading area of the liquid drops and the charge output density are synergistically improved, and the charge output density is increased. And the stability of an electrical path and the signal output efficiency are ensured.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a 3D-printed droplet friction generator that imitates natural leaves and can efficiently convert droplet kinetic energy into electrical energy. Background Art

[0002] As a new type of energy harvesting technology, friction nanogenerators can convert mechanical energy into electrical energy by using the principles of friction electrification and electrostatic induction, and have shown great application potential in self-driven sensors, wearable electronic devices and other fields.

[0003] Currently, traditional triboelectric generators (TGGs) have limitations in terms of energy conversion efficiency and environmental energy utilization. For example, most existing TGGs rely on concentrated mechanical energy sources such as mechanical vibration and human movement, making them inefficient at utilizing small, naturally occurring energies such as falling droplets and gentle breezes. However, leaves in nature, under the action of raindrops, cleverly convert the mechanical energy of these droplets into other forms of energy, such as their own vibrational energy. This natural energy conversion mechanism has provided inspiration for the design of novel TGGs.

[0004] Droplet-based electricity generators (DEGs), as an emerging energy harvesting technology, can convert the kinetic energy of droplets (such as rainwater and condensed water) found in the environment into electrical energy, offering broad application prospects. However, existing DEGs still face numerous challenges in terms of energy conversion efficiency, stability, and durability.

[0005] Natural leaves, through millions of years of evolution, possess surface structures that efficiently capture and utilize droplet energy. For example, the superhydrophobicity and microscopic protrusions on the surface of lotus leaves allow droplets to roll off quickly, carrying away surface contaminants. The leaves of some other plants, through their complex vein structures and micro- and nano-scale textures, enable efficient droplet spreading. These natural properties provide important biomimetic inspiration for the design of high-performance droplet triboelectric generators.

[0006] Although some studies have attempted to apply bionic principles to the design of droplet triboelectric generators, the following problems still exist:

[0007] 1) Low energy conversion efficiency: Existing devices have insufficient charge generation and collection efficiency to fully utilize the kinetic energy of droplets.

[0008] 2) Complex structure: The preparation process of some bionic structures is complicated and difficult to achieve large-scale production.

[0009] 3) Poor durability: The device is susceptible to droplet impact and environmental factors during long-term use, resulting in performance degradation. Summary of the Invention

[0010] The purpose of the present invention is to address the problems of low energy conversion efficiency, complex structure, and poor durability in the above-mentioned prior art droplet friction generators. The present invention proposes a 3D printed droplet friction generator that imitates natural leaves. By simulating the prismatic structure on the surface of natural leaves, the soft mesophyll and rigid veins are reproduced, which are a combination of soft and hard, and hard and flexible. The mechanical energy of the falling droplets is efficiently converted into electrical energy, thereby improving the efficiency of utilizing tiny energy in nature. At the same time, it has the advantages of simple structure, low cost, and easy manufacturing, so as to achieve efficient, stable, and durable droplet energy collection.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] A 3D printed droplet friction generator that mimics a natural leaf, comprising a bionic leaf main structure, a bottom electrode, a friction layer, and a top electrode;

[0013] The bionic leaf main structure is integrally formed using polycarbonate (PC) material using 3D printing technology to form a rigid support skeleton with a bionic leaf vein network. The vein network consists of prismatic protrusions and connecting channels, and its topology mimics the secondary vein distribution of natural leaves. The connecting channels are smooth transition grooves between adjacent prismatic protrusions, together forming the fluid-guiding topology of the bionic leaf main structure. The PC material has excellent bending strength (>108MPa) and impact strength (>9.0kJ / m2), ensuring structural stability under droplet impact and complex mechanical loads.

[0014] The bottom electrode is covered on the surface of the main structure of the bionic leaf by a conductive silver paint spraying process, conforming to the prismatic protrusions of the leaf vein network and the transitional connecting channels therebetween to form a continuous conductive layer;

[0015] The friction layer is provided on the surface of the bottom electrode, and its bottom surface forms a support point in the prismatic protrusion area, while the smooth transition groove area is in a suspended state due to the lack of prismatic protrusion support;

[0016] The top electrode is bonded to the upper surface of the friction layer through a conductive adhesive, and forms a spatially isolated triboelectric coupling pair with the bottom electrode.

[0017] Furthermore, the friction layer is a fluorinated ethylene propylene copolymer (FEP) film, which is adhered to the surface of the bottom electrode by adhesive tape to ensure that the film is taut.

[0018] Furthermore, the surface of the friction layer is plasma treated to form a micro-nano rough structure to enhance the friction charge density.

[0019] Furthermore, the aluminum electrode adopts patterned aluminum tape.

[0020] Furthermore, the friction layer has a thickness of 20-100 μm, preferably 50 μm.

[0021] Furthermore, the top electrode is made of aluminum tape, and the width of the top electrode layer is 0.1-0.5 mm, preferably 0.1 mm.

[0022] Furthermore, the tilt angle is 0°-90°, and the tilt angle refers to the angle between the tangent line of the ridge-like protrusions in the leaf vein network structure and the direction in which the droplets slide down.

[0023] Furthermore, the connecting channel is a smooth transition groove between adjacent prismatic protrusions, and the bottom surface width is 2mm-7mm.

[0024] The present invention provides a 3D printed droplet friction generator that imitates natural leaves. It uses the main structure of a bionic leaf as a substrate, and sprays a bottom electrode that conforms to the substrate on it. The bottom surface of the friction layer cooperates with the prismatic protrusion area to form a support point. The smooth transition groove area is designed to be suspended due to the lack of prismatic protrusion support. When the droplet falls on the top electrode, it carries an equal amount of opposite charges due to the friction electrification effect with the top electrode. As the droplet rolls or slides on the surface of the top electrode and the friction layer, the charge distribution changes and induces electrostatic induction, causing the bottom electrode to generate induced charges and form current through the collection system, thereby realizing the conversion of mechanical energy into electrical energy; and when the droplet hits the prismatic surface, it will flow axially along the connecting channel of the leaf vein network and contact the friction layer, inducing charge transfer between the bottom electrode and the top electrode through the solid-liquid friction electrification effect. At the same time, the rigid skeleton of the leaf vein limits excessive deformation of the FEP film, synergistically improving the droplet spreading area and charge output density, thereby ensuring the stability of the electrical path and signal output efficiency.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The generator of the present invention can make full use of the abundant droplet energy in nature, such as rainwater, dew, etc., and broaden the energy source range of the friction generator.

[0027] 2. The soft and hard spacer structure of the present invention effectively increases the spreading area of ​​droplets on the device surface, greatly improving the generator's capture of droplets and energy conversion efficiency. Compared with traditional friction generators, it effectively increases the spreading area of ​​droplets on the device surface, and the voltage output is increased by about 116%, and the current output is increased by about 133%.

[0028] 3. The use of simple structural design and 3D printing technology makes the generator low-cost, easy to manufacture and mass-produce, and has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a photo of the invention's direct use of natural leaves to make a liquid droplet friction generator;

[0030] Figure 2 This is a schematic diagram of the overall structure of the 3D-printed droplet friction generator that imitates natural leaves of the present invention;

[0031] Figure 3 Schematic diagram of the dynamic behavior of droplets spreading on the surface of the 3D-printed droplet triboelectric generator imitating natural leaves of the present invention compared with that of a traditional droplet triboelectric generator;

[0032] Figure 4 This is a comparison chart showing the effect of the leaf vein stripe angle on the open-circuit voltage of the device in the 3D-printed droplet friction generator imitating natural leaves of the present invention;

[0033] Figure 5 This is a comparison chart showing the effect of the width of the leaf vein gap on the open-circuit voltage of the device in the 3D-printed droplet friction generator imitating natural leaves of the present invention;

[0034] Figure 6 This is a graph showing the open-circuit voltage output performance of the 3D-printed droplet triboelectric generator imitating natural leaves of the present invention compared with a traditional droplet triboelectric generator;

[0035] Figure 7 This is a graph showing the short-circuit current output performance of the 3D-printed droplet triboelectric generator imitating natural leaves of the present invention compared with a traditional droplet triboelectric generator;

[0036] Reference numerals:

[0037] 1-Bionic blade main structure; 2-Bottom electrode; 3-FEP film; 4-Top electrode. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] like Figure 2 As shown, the present invention provides a 3D printed droplet friction generator that imitates natural leaves, including a bionic leaf main structure, a bottom electrode, a friction layer and a top electrode.

[0040] The bionic leaf main structure is integrally molded from polycarbonate (PC) using 3D printing technology, forming a rigid support skeleton with a bionic leaf vein network. This vein network consists of prismatic projections and connecting channels, whose topology mimics the secondary vein distribution of natural leaves. The connecting channels are smooth transition grooves between adjacent prismatic projections, together forming the fluid-guiding topology of the bionic leaf main structure. PC material has a high glass transition temperature, typically around 140-150°C. This property enables it to maintain excellent physical properties even in high-temperature environments, preventing softening or deformation due to rising ambient temperatures, thereby ensuring the normal operation of the generator under various climatic conditions. Furthermore, the PC substrate exhibits minimal dimensional changes under varying temperature and humidity conditions, enabling the 3D-printed leaf main structure to maintain its accuracy over time, thereby ensuring the stability of the generator's performance. PC material possesses excellent tensile, flexural, and impact strengths, ensuring structural stability under droplet impact and complex mechanical loads.

[0041] The bottom electrode is covered on the surface of the main structure of the bionic leaf by spraying conductive silver paint, conforming to the ridge-like protrusions of the leaf vein network and the transitional connecting channels between them to form a continuous conductive layer. The silver particles in the conductive silver paint have extremely high conductivity, and its conductivity can usually reach 10 7 On the order of S / m, compared to the conductivity of general copper tape, conductive silver paint can conduct charges more efficiently. When the generator is working, when the droplets and the top electrode are electrified by friction, the bottom electrode generates induced charges. The conductive silver paint can quickly transfer the charges to the collection system, reducing the transmission loss of the charges inside the electrode, thereby improving the stability and intensity of the current output, and helping to improve the overall power generation efficiency of the generator. In addition, the conductive silver paint can firmly adhere to the surface of the insulating isolation layer and other substrate materials. During the manufacturing process, it can better fit closely with the PC-made substrate with a complex structure imitating natural leaves, and it is not easy to fall off. This feature ensures the stability of the electrode during long-term use, avoids generator failure due to electrode shedding, and extends the service life of the generator.

[0042] The friction layer is applied to the bottom electrode surface, with the prismatic protrusions forming support points on its bottom surface. The smooth transition groove area, lacking prismatic support, is suspended in the air. The friction layer, made of a fluorinated ethylene propylene copolymer (FEP) film, is applied to the bottom electrode surface, with a vertical distance of 5-8 mm between the friction layer and the groove area. FEP film is highly resistant to most chemicals and maintains stable performance in a variety of harsh environments. In natural environments, whether acidic rain or chemically laden dew, FEP film is resistant to corrosion or chemical reactions, significantly extending the lifespan of the generator. Compared to polytetrafluoroethylene (PTFE) film, FEP film can adapt to more complex chemical environments, ensuring long-term stability of triboelectric performance. Furthermore, FEP film has an extremely low coefficient of friction, making it easier for droplets to roll and slide off its surface. When droplets come into contact with the friction layer, the low coefficient of friction reduces energy loss, allowing the droplets' mechanical energy to be more efficiently converted into electrical energy. Under the same conditions, the generator using FEP film as the friction layer is significantly more efficient in capturing the mechanical energy of droplets than using PTFE film, thereby improving the overall power generation efficiency.

[0043] The top electrode is made of patterned aluminum tape, which is bonded to the upper surface of the friction layer with conductive adhesive, forming a spatially isolated triboelectric coupling pair with the bottom electrode. The aluminum tape is soft and flexible, and can be easily bent, folded, and adapted to the needs of electrodes of various shapes and sizes. Especially in the design of non-planar or complex curved electrodes, the aluminum tape can fit tightly to the surface, ensuring the contact accuracy between the electrode and other components, thereby improving the stability and reliability of the system. In addition, it is easy to cut and paste, and the installation process is simple and convenient, which can quickly complete the production and installation of the electrode, effectively improving production efficiency and reducing labor costs. Aluminum easily reacts with oxygen in the air, and a dense aluminum oxide film will form on the surface. This oxide film can prevent further oxidation of the internal aluminum, giving the aluminum tape good corrosion resistance. It can resist the erosion of external corrosive substances such as water vapor, acids and alkalis to a certain extent, thereby extending the service life of the electrode and ensuring that the electrode can maintain excellent performance in different environments.

[0044] This embodiment also provides a preparation process of a 3D printed droplet friction generator imitating a natural leaf, comprising the following steps:

[0045] Step 1: Use 3D modeling software to design a 3D model of the bionic leaf main structure and optimize and adjust it according to requirements. PC material is printed using fused deposition modeling (FDM) 3D printing technology according to the designed bionic leaf main structure 3D model. During the printing process, parameters such as printing temperature, speed, and layer thickness are controlled to ensure structural accuracy and quality. In this example, the printing temperature is 280°, the printing speed is 280 mm / s, and the layer thickness is 0.08 mm.

[0046] Step 2: Evenly spray conductive silver paint onto the surface of the printed bionic blade structure to form the bottom electrode. The bottom electrode is conformally bonded to the bionic blade structure, and the paint layer thickness is controlled to 100 μm during spraying. While ensuring conductivity, excessively thick paint layers that could impact the overall performance of the structure or increase costs are avoided. By optimizing the spray angle to 45° and the spray distance to 15 cm, the resulting conductive silver paint achieves more stable charge transfer. Step 3: Apply a 50 μm thick FEP film over the bottom electrode. The film is inspected for flatness to ensure a smooth surface and minimize energy loss during droplet rolling.

[0047] Step 4: Attach aluminum tape to the FEP film to form a top electrode. Specifically, cut the aluminum tape to match the size and shape of the ridges on the bionic leaf's main structure, ensuring a perfect fit with the FEP film. The width of the top electrode layer is 0.1-0.5 mm, with 0.1 mm being preferred in this embodiment.

[0048] like Figure 3 As shown, when a droplet falls on the top electrode, it carries equal amounts of opposite charges due to the triboelectric effect with the top electrode. As the droplet rolls or slides on the surface of the top electrode and the friction layer, the change in charge distribution triggers electrostatic induction, causing the bottom electrode to generate induced charges and form current through the collection system, realizing the conversion of mechanical energy into electrical energy; and when the droplet hits the prismatic surface, it will flow axially along the connecting channels of the leaf vein network and contact the friction layer, inducing charge transfer between the bottom electrode and the top electrode through the solid-liquid triboelectric effect. At the same time, the rigid skeleton of the leaf vein limits excessive deformation of the FEP film, synergistically improving the droplet spreading area and charge output density to ensure the stability of the electrical path and signal output efficiency.

[0049] During implementation, the droplet spreading area and open circuit voltage will be affected by the tilt angle and the width of the bottom surface of the smooth transition groove between adjacent prismatic protrusions, that is, the width of the leaf vein gap. The tilt angle refers to the angle between the tangent line of the prismatic protrusion in the leaf vein network structure and the direction of the droplet sliding. Figure 4 As shown in the figure, this embodiment uses 3D printing technology to prepare devices with different leaf vein inclination angles, including 0°, 30°, 45°, 60°, and 90°; droplet tests are conducted at different inclination angles. The experimental results show that as the leaf vein inclination angle increases, the droplet spreading area and open circuit voltage increase synchronously, reaching a peak at 90°. Figure 5 As shown in the figure, 3D printing technology was used to prepare devices with different leaf vein gap widths, including 2mm, 3mm, 4mm, 5mm, 6mm, and 7mm. Experiments found that as the width of the leaf vein gap increased, the droplet spreading area and open circuit voltage of the device first increased and then decreased, reaching a peak value when the gap width was 5mm.

[0050] In a laboratory environment, this embodiment uses a simulated rainfall device to test the performance of the 3D printed droplet friction generator that imitates natural leaves: the size of the droplet, the falling speed and the frequency are adjusted, and the output voltage, current and power of the generator are measured. The test results show that under standard test conditions (droplet diameter 5mm, falling speed 4m / s, frequency 3Hz), the output voltage of the generator can reach 545V and the output current is 1400μA, showing good power generation performance. Figure 6 and Figure 7 It can be seen that the output voltage and output current of the present invention are much greater than those of the traditional flat-plate liquid droplet friction generator.

[0051] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A 3D-printed droplet triboelectric generator that mimics a natural leaf, comprising a bionic leaf main structure, a bottom electrode, a friction layer, and a top electrode; characterized by: The bionic leaf main structure is integrally formed using polycarbonate (PC) material using 3D printing technology, forming a rigid support skeleton with a bionic leaf vein network. The vein network consists of prismatic protrusions and connecting channels, and its topology mimics the secondary vein distribution of natural leaves. The connecting channels are smooth transition grooves between adjacent prismatic protrusions, together forming the fluid-guiding topology of the bionic leaf main structure. The bottom electrode is covered on the surface of the main structure of the bionic leaf by a conductive silver paint spraying process, conforming to the prismatic protrusions of the leaf vein network and the transitional connecting channels therebetween to form a continuous conductive layer; The friction layer is provided on the surface of the bottom electrode, and its bottom surface forms a support point in the prismatic protrusion area, while the smooth transition groove area is in a suspended state due to the lack of prismatic protrusion support; The top electrode is bonded to the upper surface of the friction layer through a conductive adhesive, and forms a spatially isolated triboelectric coupling pair with the bottom electrode.

2. The 3D printed droplet friction generator imitating a natural leaf according to claim 1, characterized in that: The friction layer is a fluorinated ethylene propylene copolymer (FEP) film, which is adhered to the surface of the bottom electrode by adhesive tape to ensure that the film is taut.

3. The 3D printed droplet friction generator imitating natural leaves according to claim 2, characterized in that: The surface of the friction layer is plasma treated to form a micro-nano rough structure to enhance the friction charge density.

4. The 3D printed droplet friction generator imitating a natural leaf according to claim 1, characterized in that: The aluminum electrode adopts patterned aluminum tape.

5. The 3D printed droplet friction generator imitating natural leaves according to claim 1, characterized in that: The thickness of the friction layer is 20-100 μm, preferably 50 μm.

6. The 3D printed droplet friction generator imitating a natural leaf according to claim 1, characterized in that: The top electrode is made of aluminum tape, and the width of the top electrode layer is 0.1-0.5 mm, preferably 0.1 mm.

7. The 3D printed droplet friction generator imitating a natural leaf according to claim 1, characterized in that: The tilt angle is 0°-90°, and the tilt angle refers to the angle between the tangent line of the ridge-like protrusions in the leaf vein network structure and the direction in which the droplet slides down.

8. The 3D printed droplet friction generator imitating a natural leaf according to any one of claims 1 to 7, characterized in that: The connecting channel is a smooth transition groove between adjacent prismatic protrusions, and the bottom surface width is 2mm-7mm.

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