Bionic antireflection photothermal sensing material based on continuous gradient micro-nano structure and preparation method thereof

Abstract

The application discloses a kind of based on continuous gradual change micro-nano structure's bionic antireflection light-thermal sensing material and its preparation method, method includes the following steps, provide elastic substrate layer, intermediate conductive layer and upper layer heat-sensitive layer;Wherein, elastic substrate layer is high molecular elastic polymer, intermediate conductive layer includes silicone rubber and carbon nanotube blend, upper layer heat-sensitive layer includes silicone rubber, carbon black and carbon nanotube blend;Elastic substrate layer is formed into elastic plane material using heat curing or light curing mode, on its upper surface, spray conductive layer in normal temperature environment, after drying and annealing, obtain solidified intermediate conductive layer;Subsequently, with light-thermal sensitive layer again spraying, after heating and curing, obtain upper layer heat-sensitive layer, the application is through interface bionic structure, the synergic design of conductive material and light-thermal material, effectively improve the light absorption efficiency and response sensitivity of sensing material.

Description

Technical Field

[0001] This invention relates to the field of micro-nano structure sensing technology, and in particular to a biomimetic anti-reflection photothermal sensing material based on a continuously gradient micro-nano structure and its preparation method. Background Technology

[0002] With the development of flexible electronic products, many high-performance flexible materials have been obtained. However, current research mostly focuses on various high-performance materials. On the one hand, in various practical application scenarios, the single-solid strain monitoring function makes it difficult to effectively apply these flexible components. On the other hand, layered flexible electronics often face technical challenges such as interlayer delamination, affecting the stability and reliability of flexible electronics and making it difficult to meet the sensing needs of non-invasive health monitoring and biomimetic flexible interaction.

[0003] Existing photothermal-strain dual-mode flexible electronics are mainly achieved through three types of methods: material composite (co-blending / coating of carbon-based / liquid crystal elastomer / conductive polymer with PDMS / TPU elastic substrate), structural design (wave / wrinkle / sandwich stacking, laser direct writing of porous graphene), and functional integration (co-integration of photothermal layer-strain sensing layer-electrode). The main challenges are interface delamination and performance drift caused by the mismatch between the modulus / thermal expansion of the photothermal material and the flexible substrate, low photothermal conversion efficiency due to limitations in material properties, and complex integrated processes that make large-scale fabrication difficult.

[0004] At the air-material interface, the difference in refractive index typically leads to significant Fresnel reflection, causing most light energy to return to the air as reflection and preventing absorption and conversion by the material, resulting in low photothermal conversion efficiency. For flexible electronic materials, this leads to insufficient photothermal sensing performance. In nature, organisms such as clear-winged insects have evolved micro- and nanostructure arrays with hemispherical and papillary shapes on their eyes, wings, and other surfaces to enhance camouflage, concealment, and visual acuity. Introducing these biomimetic micro- and nanostructures with continuously gradient characteristics (such as cicada wings, butterfly scales, and moth eyes) can effectively solve the problem of light energy loss caused by excessive reflection.

[0005] These biomimetic structures possess excellent broadband antireflection properties, which can significantly reduce interfacial light reflection loss and improve light absorption efficiency, thereby compensating for the low photothermal conversion efficiency of traditional photothermal materials at the structural level. At the same time, the integrated design of substrate-conductive layer-functional layer materials can avoid obvious interfacial delamination through material similarity, and the mechanical compatibility of their similar components can alleviate the problem of modulus and thermal expansion mismatch, improve the interfacial bonding stability, and provide a new design idea for developing high-performance, high-stability photothermal-strain dual-mode flexible electronics.

[0006] Therefore, from the perspective of coupled biomimetic design, which promotes light energy utilization through functional layer surface structure design and enhances interface bonding through material system design, this paper proposes a biomimetic anti-reflection photothermal sensing material based on continuous gradient micro-nano structure and its preparation method. This material serves the sensing needs in fields such as non-invasive health monitoring and biomimetic flexible interaction, and is both necessary and feasible. However, the existing technology still needs to be improved and developed. Summary of the Invention

[0007] This application proposes a biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure and its preparation method, in order to solve the problems mentioned in the background art.

[0008] A biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure includes an elastic substrate layer, an intermediate conductive layer, and an upper thermally sensitive layer. The elastic substrate layer is a polymer, the intermediate conductive layer is a blend of polymer and conductive filler, and is obtained by curing conductive ink 1. The upper thermally sensitive layer is a blend of polymer and heat-absorbing material, and is obtained by curing conductive ink 2. Conductive ink 1 is sprayed onto an elastic substrate layer and cured by heating to form an intermediate conductive layer. Thermosensitive conductive ink 2 is then sprayed onto the intermediate conductive layer and cured by heating to obtain the upper sensitive layer.

[0009] The polymer is silicone rubber.

[0010] The sensing material consists of three layers, all of which are primarily made of silicone rubber. There is no obvious interfacial delamination, making it difficult for the layers to separate.

[0011] The silicone rubber includes, but is not limited to, PDMS; the conductive fillers include, but are not limited to, carbon nanotubes, graphene, metal particles, and MXene.

[0012] A method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure, used to prepare the aforementioned biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure. The specific steps include: Step 1, the preparation process of the PDMS layer of the substrate includes: uniformly mixing the PDMS main agent and curing agent at a mass fraction ratio of 10:1 and then curing; Step 2, the preparation process of conductive ink 1 includes: first, mixing PDMS main agent and curing agent at a mass fraction of 8:1 to 10:1, adding ethyl acetate at 5 times the total mass of the mixture, stirring continuously until uniform, then adding conductive filler modified multi-walled carbon nanotubes at a mass fraction of 3.5%-4% of the mixed solution, stirring for 1 hour, and then ultrasonically vibrating for 15-30 minutes; Step 3, the preparation process of the thermosensitive conductive ink 2 includes: first, mixing the PDMS main agent and curing agent evenly at a mass fraction of 8:1 to 10:1, adding 7 times the total mass of ethyl acetate of the mixture, stirring continuously until uniform, then adding 0.38% of the mass fraction of modified multi-walled carbon nanotubes and 3.8% of carbon black of the mixed solution, stirring for 1 hour, and then ultrasonically vibrating for 15-30 minutes; Step 4, Layer-by-layer spraying process: First, conductive ink 1 is sprayed onto the PDMS substrate, controlling the number of sprays and the spraying distance. The whole process is carried out in a fume hood. Then, it is placed in a vacuum drying oven for heating. Then, the thermosensitive conductive ink 2 is sprayed on. Then, it is placed in a vacuum drying oven for heating and curing. Finally, the biomimetic flexible superhydrophobic strain sensor is successfully prepared.

[0013] The base silicone rubber elastic layer is cured at 80 degrees Celsius for 1 hour. The heating and curing temperature of conductive ink 1 and thermosensitive conductive ink 2 is 80-90 degrees Celsius, and the heating time is 45 min-1 h.

[0014] During the layer-by-layer spraying process, the distance between each layer is 15-20cm, and the number of spraying times is 3-5.

[0015] The surface microstructure morphology can be controlled by adjusting the ratio of carbon nanotubes, carbon black, and ethyl acetate solution in the upper photothermal sensitive layer.

[0016] The beneficial effects of this invention are as follows: Through the synergistic design of interface biomimetic structure, conductive material and photothermal material, this invention effectively improves the light absorption efficiency and response sensitivity of sensing materials, enhances the stability and reliability of flexible electronics, meets the sensing needs of non-invasive health monitoring and biomimetic flexible interaction, and adopts an integrated design of substrate-conductive layer-functional layer materials to avoid obvious interface delamination through material similarity. The mechanical compatibility of their similar components can alleviate the problem of modulus and thermal expansion mismatch, improve the stability of interface bonding, and provide a new design idea for developing high-performance, high-stability photothermal-strain dual-mode flexible electronics. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of the interface bonding state of the present invention; Figure 2 These are micro / nano structure diagrams of the surface functional layers of the present invention with different proportions; Figure 3 This is a curve showing the strain sensing performance of the present invention. Figure 4 This is a graph showing the photothermal sensing performance of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] A biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure includes an elastic substrate layer, an intermediate conductive layer, and an upper thermally sensitive layer. The elastic substrate layer is a polymer, the intermediate conductive layer is a blend of polymer and conductive filler, and is obtained by curing conductive ink 1. The upper thermally sensitive layer is a blend of polymer and heat-absorbing material, and is obtained by curing conductive ink 2. Conductive ink 1 is sprayed onto an elastic substrate layer and cured by heating to form an intermediate conductive layer. Thermosensitive conductive ink 2 is then sprayed onto the intermediate conductive layer and cured by heating to obtain the upper sensitive layer.

[0020] The polymer is silicone rubber.

[0021] The sensing material consists of three layers, all primarily made of silicone rubber, with a cross-sectional structure as shown below. Figure 1 As shown, this further illustrates that the photothermal sensing material has good interfacial bonding, no cavities between layers, no obvious interfacial delamination, and is not easily separated between layers.

[0022] The silicone rubber includes, but is not limited to, PDMS; the conductive fillers include, but are not limited to, carbon nanotubes, graphene, metal particles, and MXene.

[0023] A method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure, used to prepare the aforementioned biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure. The specific steps include: Step 1, the preparation process of the PDMS layer of the substrate includes: uniformly mixing the PDMS main agent and curing agent at a mass fraction ratio of 10:1 and then curing; Step 2, the preparation process of conductive ink 1 includes: first, mixing PDMS main agent and curing agent at a mass fraction of 8:1 to 10:1, adding ethyl acetate at 5 times the total mass of the mixture, stirring continuously until uniform, then adding conductive filler modified multi-walled carbon nanotubes at a mass fraction of 3.5%-4% of the mixed solution, stirring for 1 hour, and then ultrasonically vibrating for 15-30 minutes; Step 3, the preparation process of the thermosensitive conductive ink 2 includes: first, mixing the PDMS main agent and curing agent evenly at a mass fraction of 8:1 to 10:1, adding 7 times the total mass of ethyl acetate of the mixture, stirring continuously until uniform, then adding 0.38% of the mass fraction of modified multi-walled carbon nanotubes and 3.8% of carbon black of the mixed solution, stirring for 1 hour, and then ultrasonically vibrating for 15-30 minutes; Step 4, Layer-by-layer spraying process: First, conductive ink 1 is sprayed onto the PDMS substrate, controlling the number of sprays and the spraying distance. The whole process is carried out in a fume hood. Then, it is placed in a vacuum drying oven for heating. Then, the thermosensitive conductive ink 2 is sprayed on. Then, it is placed in a vacuum drying oven for heating and curing. Finally, the biomimetic flexible superhydrophobic strain sensor is successfully prepared.

[0024] The base silicone rubber elastic layer is cured at 80 degrees Celsius for 1 hour. The heating and curing temperature of conductive ink 1 and thermosensitive conductive ink 2 is 80-90 degrees Celsius, and the heating time is 45 min-1 h.

[0025] During the layer-by-layer spraying process, the distance between each layer is 15-20cm, and the number of spraying times is 3-5.

[0026] Adjusting the ratio of carbon nanotubes, carbon black, and ethyl acetate solution in the upper photothermal sensitive layer can control the surface microstructure morphology, such as... Figure 2 As shown, when the ratio of carbon nanotubes to carbon black increases from 1:1 to 1:9, the micropore size of the surface functional layer decreases from nearly 10 to 2, and the nanoscale morphology distributed on the micropores increases significantly.

[0027] Example: 1) Preparation of substrate material Preparation of PDMS substrate: The ratio of PDMS precursor to crosslinking agent is 10:1. The mixture is stirred evenly in a magnetic stirrer (800 rpm), then poured into a pre-made mold, pre-cured in an oven at 60°C for 2 hours, and then cured at 100°C for 2 hours to successfully obtain PDMS substrate film.

[0028] 2) Preparation of layered conductive ink Conductive ink for intermediate conductive layer 1: First, add 4g of PDMS main agent and 0.4g of curing agent to 25ml of ethyl acetate, stir for 1h, mix evenly, then add 1g of modified multi-walled carbon nanotubes, stir for 1h, and finally use after ultrasonic vibration for 15-30 min.

[0029] Upper heat-sensitive conductive ink 2: First, add 3g of PDMS main agent and 0.3g of curing agent to 25ml of ethyl acetate, stir for 1h, mix evenly, then add 0.1g of multi-walled carbon nanotubes and 0.9g of carbon black, stir for 1h, and then use after ultrasonic vibration for 15-30min. All operations are performed at room temperature.

[0030] Ethyl acetate was chosen as the solvent here because it is a quick-drying solvent, which can drier tightly wound filaments. The siloxane polymer chains are thus untangled. In conductive ink systems, this can dilute the PDMS solution and... The goal is to achieve uniform dissolution of the conductive active material. Some common conductive inks do not contain organic solvents, but... The solubility of conductive active materials is very limited. Secondly, the rapid evaporation of ethyl acetate can construct some surface micro- and nano-structures, which is beneficial for the design of functional layer surface structures.

[0031] 3) Fabrication of a biomimetic flexible superhydrophobic antireflection strain sensor The biomimetic sensor consists of three layers of materials, and its fabrication experimental steps are as follows: (1) First, the pre-made PDMS / CNTs conductive ink is sprayed onto the PDMS substrate film. During the spraying process, the nozzle is kept at a 90-degree angle to the substrate plane, the spraying distance is 20 cm, each spray lasts for 1 second, and is repeated 5 times. The entire process is carried out in a fume hood. (2) Subsequently, the sample was placed in a vacuum drying oven and heated at 80°C for 1 hour. After the PDMS / CNTs conductive ink was cured, a uniform interlayer and entangled conductive network (intermediate layer) could be formed on the flexible PDMS substrate.

[0032] (3) Similarly, the pre-made PDMS / CNTs / CBs conductive ink is evenly sprayed onto the surface of the cured intermediate layer. During the spraying process, the nozzle is kept at a 90-degree angle to the substrate plane, the spraying distance is 20 cm, each spray lasts for 1 second, and is repeated 5 times. The whole process is carried out in a fume hood.

[0033] (4) Finally, the sample was placed in a vacuum drying oven and heated at 80°C for 1 hour. After the PDMS / CNTs / CBs conductive ink was cured, a porous and rough functional layer (upper layer) was formed. This layer-by-layer spraying strategy and elastomer interface curing technology can successfully prepare a biomimetic flexible strain sensor. The biomimetic sensor has a response time of 50 milliseconds at 10% tensile strain. This fast response characteristic is due to the flexibility and elasticity of the substrate and the design of the double conductive layer sensing mechanism. In addition, the element can detect a minimum tensile strain of 0.7%. At strain rates of 40%, 70%, and 90%, the element's R... 2 The values ​​are greater than 0.996, 0.998, and 0.992 respectively, demonstrating high linearity. Figure 3 Under solar radiation, the temperature of the biomimetic sensor can rise from room temperature to 63°C, with a response speed of 0.403°C / second. Furthermore, this biomimetic sensor exhibits stable and reliable response characteristics in continuous on / off light cycling experiments, with a resistance change rate reaching 0.2 (…). Figure 4 ).

Claims

1. A biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure, characterized in that, It includes an elastic base layer, an intermediate conductive layer, and an upper heat-sensitive layer. The elastic base layer is a polymer, the intermediate conductive layer is a blend of polymer and conductive filler, and is obtained by curing conductive ink 1. The upper heat-sensitive layer is a blend of polymer and heat-absorbing material, and is obtained by curing conductive ink 2. Conductive ink 1 is sprayed onto an elastic substrate layer and cured by heating to form an intermediate conductive layer. Thermosensitive conductive ink 2 is then sprayed onto the intermediate conductive layer and cured by heating to obtain the upper sensitive layer.

2. The biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure according to claim 1, characterized in that, The polymer is silicone rubber.

3. The biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure according to claim 2, characterized in that, The sensing material consists of three layers, all of which are primarily made of silicone rubber. There is no obvious interfacial delamination, making it difficult for the layers to separate.

4. The biomimetic antireflective photothermal sensing material based on a continuously gradient micro / nano structure according to claim 3, characterized in that, The silicone rubber includes, but is not limited to, PDMS; the conductive fillers include, but are not limited to, carbon nanotubes, graphene, metal particles, and MXene.

5. A method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure, used to prepare the biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure as described in any one of claims 1 to 4, characterized in that, The specific steps include: Step 1, the preparation process of the PDMS layer of the substrate includes: uniformly mixing the PDMS main agent and curing agent at a mass fraction ratio of 10:1 and then curing; Step 2, the preparation process of conductive ink 1 includes: first, mixing PDMS main agent and curing agent at a mass fraction of 8:1 to 10:1, adding ethyl acetate at 5 times the total mass of the mixture, stirring continuously until uniform, then adding conductive filler modified multi-walled carbon nanotubes at a mass fraction of 3.5%-4% of the mixed solution, stirring for 1 hour, and then ultrasonically vibrating for 15-30 minutes; Step 3, the preparation process of the thermosensitive conductive ink 2 includes: first, mixing the PDMS main agent and curing agent evenly at a mass fraction of 8:1 to 10:1, adding 7 times the total mass of ethyl acetate of the mixture, stirring continuously until uniform, then adding 0.38% of the mass fraction of modified multi-walled carbon nanotubes and 3.8% of carbon black of the mixed solution, stirring for 1 hour, and then ultrasonically vibrating for 15-30 minutes; Step 4, Layer-by-layer spraying process: First, conductive ink 1 is sprayed onto the PDMS substrate, controlling the number of sprays and the spraying distance. The whole process is carried out in a fume hood. Then, it is placed in a vacuum drying oven for heating. Then, the thermosensitive conductive ink 2 is sprayed on. Then, it is placed in a vacuum drying oven for heating and curing. Finally, the biomimetic flexible superhydrophobic strain sensor is successfully prepared.

6. The method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure according to claim 5, characterized in that, The base silicone rubber elastic layer is cured at 80 degrees Celsius for 1 hour.

7. The method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure according to claim 5, characterized in that, The heating and curing temperature of conductive ink 1 and thermosensitive conductive ink 2 is 80-90 degrees Celsius, and the heating time is 45 min-1 h.

8. The method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure according to claim 5, characterized in that, During the layer-by-layer spraying process, the distance between each layer is 15-20cm, and the number of spraying times is 3-5.

9. The method for preparing a biomimetic antireflective photothermal sensing material based on a continuously graded micro / nano structure according to claim 5, characterized in that, The surface microstructure morphology can be controlled by adjusting the ratio of carbon nanotubes, carbon black, and ethyl acetate solution in the upper photothermal sensitive layer.

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