A veinlet bio-based breathable and transparent wearable temperature sensor and a preparation method thereof

Abstract

The application discloses a kind of leaf vein biobased breathable transparent wearable temperature sensor and preparation method thereof, it is related to novel sensing material field, temperature sensor includes natural leaf vein skeleton, copper seed layer being arranged on the surface of natural leaf vein skeleton, silver conductive layer being arranged on the surface of copper seed layer and electrode being arranged at the both ends of natural leaf vein skeleton respectively;The thickness of copper seed layer is 20~40nm, and the thickness of silver conductive layer is 30~70nm;Copper seed layer and silver conductive layer form continuous metal conductive network on the surface of natural leaf vein skeleton, and natural leaf vein skeleton retains its natural hierarchical porous network structure;Its preparation method includes: washing and drying and ultraviolet ozone pretreatment to natural leaf vein, evaporates copper seed layer, silver conductive layer is electroplated, and electrode is set.The application uses natural leaf vein as biobased skeleton, utilizes its hierarchical interconnected porous structure, so that sensor has good breathability, flexibility and transparency, stable performance, and is suitable for real-time monitoring of human body surface temperature and intelligent wearable device.

Description

Technical Field

[0001] This invention relates to the field of novel sensing materials, and in particular to a leaf vein-based, breathable, transparent, wearable temperature sensor and its preparation method. Background Technology

[0002] Human body temperature is one of the important physiological parameters reflecting human health status. Real-time and continuous monitoring of body surface temperature can provide important data support for fever early warning, sports health management, chronic disease monitoring, postoperative recovery assessment, and wearable medical devices. With the development of flexible electronics and wearable devices, adhesive temperature sensors have gradually become an important research direction in the field of human health monitoring. Existing wearable temperature sensors mostly use metal thin films, conductive polymers, carbon materials, or inorganic semiconductor materials as the sensitive layer, and are usually fabricated on flexible substrates such as polyimide, polydimethylsiloxane, and polyethylene terephthalate. Although these sensors can achieve a certain degree of flexible adhesion and temperature response, they still have significant shortcomings in actual human wear. First, most traditional flexible temperature sensors are opaque, and after the device is attached to the skin surface, it easily obscures the original texture and color of the skin, affecting the aesthetics and concealment of wearing, making it difficult to meet the needs of thinness, transparency, and comfort in medical monitoring, sports monitoring, and daily wearable scenarios. Especially when used on exposed areas such as the face, hands, and neck for a long time, opaque sensors will reduce user acceptance. Secondly, existing temperature sensors typically employ continuous, dense polymer substrates or encapsulation layers, resulting in poor overall breathability. When the sensor is attached to the skin for extended periods, it hinders sweat evaporation and air exchange, leading to localized heat and moisture buildup, which can cause stuffiness, itching, redness, and even contact dermatitis. Therefore, insufficient breathability is a significant factor limiting the long-term stable wearability of wearable temperature sensors. Furthermore, while some transparent temperature sensors achieve a degree of light transmittance through transparent conductive films, their substrates or conductive networks often remain continuous film structures, making it difficult to simultaneously achieve high transparency, good breathability, flexible fit, and stable temperature response. Although some porous sensors improve breathability, their disordered pore structure and discontinuous conductive pathways can easily lead to unstable resistance, decreased response sensitivity, or insufficient mechanical reliability.

[0003] Natural leaf veins possess a hierarchical, interconnected, continuously conductive, and naturally porous network structure. The main vein, lateral veins, and fine veins together form highly efficient material transport channels. Simultaneously, leaves themselves are characterized by their thinness, flexibility, biodegradability, and bio-based origin. If a temperature-sensitive conductive network can be constructed using leaf vein structures, natural breathable channels can be formed while maintaining a continuous conductive path, potentially achieving a synergistic improvement in transparency, breathability, flexibility, and temperature sensing performance. Therefore, there is an urgent need to develop a bio-based wearable breathable and transparent temperature sensor based on leaf vein structures and its fabrication method. This sensor should possess good optical transparency and skin adhesion, as well as excellent breathability, temperature response characteristics, and wearing comfort to meet the needs of real-time human health monitoring and long-term wearable applications. Summary of the Invention

[0004] The purpose of this invention is to provide a leaf vein-based, breathable, transparent, wearable temperature sensor to solve the problems of poor breathability, opacity, and insufficient comfort during long-term wear of existing sensors. This invention uses natural leaf veins as a framework to construct a metal conductive network, which combines high light transmittance, good breathability, and stable temperature response performance.

[0005] Another objective of this invention is to provide a method for manufacturing the above-mentioned sensor, which is simple in process, low in cost, and suitable for mass production.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a leaf vein-based, breathable, transparent, wearable temperature sensor, comprising: a natural leaf vein skeleton, a copper seed layer attached to the surface of the natural leaf vein skeleton, a silver conductive layer attached to the surface of the copper seed layer, and electrodes respectively disposed at both ends of the natural leaf vein skeleton; the thickness of the copper seed layer is 20-40 nm, and the thickness of the silver conductive layer is 30-70 nm; the copper seed layer and the silver conductive layer form a continuous metal conductive network on the surface of the natural leaf vein skeleton, and the natural leaf vein skeleton retains its natural hierarchical porous network structure.

[0007] Furthermore, the natural leaf vein framework is a magnolia leaf vein framework.

[0008] Furthermore, the thickness of the copper seed layer is 25–35 nm, and the thickness of the silver conductive layer is 40–50 nm.

[0009] Furthermore, the electrode is one of the following: silver paste electrode, conductive adhesive electrode, copper foil tape electrode, metal wire electrode, or vapor-deposited metal electrode.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned leaf vein bio-based breathable transparent wearable temperature sensor, comprising the following steps: S1. Select intact and clean natural leaf veins, place them under ultraviolet ozone lamp for 3-10 minutes, then wash with deionized water or ethanol and dry. S2, depositing a copper seed layer on the surface of the pretreated natural leaf veins; S3, using the leaf veins after the copper layer is deposited as the cathode and the silver sheet as the anode, a silver conductive layer is electroplated on the surface of the copper seed layer under constant current or constant current density conditions to obtain a copper / silver composite conductive leaf vein network, i.e., metallized leaf veins. S4, electrodes are provided at both ends of the metallized leaf vein.

[0011] Furthermore, in step S2, the copper seed layer is deposited using a thermal evaporation method, with a evaporation vacuum degree lower than 5 × 10⁻⁶. -4 Pa, heating current is 90-120A.

[0012] Furthermore, in step S3, the electroplating temperature of the electroplated silver conductive layer is 15–40°C, and the current density is 0.1–0.5 A / dm³. 2 .

[0013] Furthermore, the electroplating temperature of the silver conductive layer is 20–30°C, and the current density is 0.2–0.3 A / dm³. 2 .

[0014] Further, in step S3, the silver electroplating solution used for electroplating includes the following components: AgNO3 4-6 g / L; Na2S2O3 200-300 g / L; K2S2O5 40-50 g / L; thioaminourea 0.5-0.7 g / L; polyethyleneimine 0.08 g / L; the balance being deionized water.

[0015] Furthermore, prior to step S4, a step of cutting the metallized leaf veins into the desired shape is also included.

[0016] According to the above technical solution, the beneficial effects of the present invention are: 1. This invention uses natural plant leaf veins as a bio-based framework, and utilizes the hierarchical interconnection network structure of the leaf veins themselves to construct a temperature-sensitive conductive pathway. At the same time, it retains the natural porous network structure, so that the sensor has both good breathability and flexible adhesion. It can promote air exchange and sweat evaporation on the skin surface, reduce the risk of stuffiness, dampness and skin discomfort during long-term wear, and the raw materials are widely available and low in cost, with good bio-based characteristics and environmental friendliness.

[0017] 2. This invention utilizes ultraviolet ozone pretreatment, copper seed layer deposition, and silver electroplating to form a continuous and stable conductive metal layer on the leaf vein surface, enabling the sensor to possess high conductivity and stable temperature response performance, with a temperature coefficient of resistance reaching 0.0037–0.0039℃.-1 It closely resembles the intrinsic temperature response characteristics of metallic silver.

[0018] 3. The temperature sensor prepared by this invention has a light transmittance of over 80%, which can reduce the obstruction of the skin appearance by traditional opaque wearable sensors, improve the aesthetics of wearing and user acceptance; at the same time, it has good flexibility and mechanical stability, and can still maintain stable performance after being bent 1000 times at a curvature radius of 5mm, making it suitable for adhesive, dynamic and long-term temperature monitoring on the human skin surface.

[0019] 4. The preparation method of the present invention is simple and controllable, without the need for complex micro-nano processing technology. The conductivity, light transmittance and temperature response performance of the sensor can be controlled by adjusting parameters such as copper layer thickness, silver electroplating time and current density. It has good potential for large-scale preparation and practical application, and can be used in fields such as real-time monitoring of human body surface temperature, fever early warning, sports health monitoring, rehabilitation medicine and smart wearable electronic devices. Attached Figure Description

[0020] Figure 1 A schematic diagram (a) and a photograph (b) of the sensor provided in an embodiment of the present invention; Figure 2 A schematic diagram of the microstructure of the sensor provided in an embodiment of the present invention; Figure 3 The resistance change rate of the sensor provided in this embodiment of the invention is shown as a function of temperature. Detailed Implementation

[0021] 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, and 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.

[0022] The leaf vein-based bio-based breathable transparent wearable temperature sensor provided by this invention is prepared by the following steps: (1) Leaf vein pretreatment. Select intact and clean natural leaf veins as the bio-based framework and treat them under ultraviolet ozone lamp for 3-10 min to remove organic pollutants and impurities on the surface of the leaf veins, while improving the surface activity of the leaf veins and the adhesion of the metal layer. After treatment, wash with deionized water or ethanol and dry at room temperature or low temperature for later use.

[0023] (2) Copper seed layer deposition. The pretreated natural leaf veins were placed in a thermal evaporation equipment and the vacuum was reduced to below 5 × 10⁻⁶. -4Pa is used to heat and evaporate a copper source under vacuum at a heating current of 90–120 A, depositing a continuous or semi-continuous copper seed layer on the leaf vein surface. The copper layer thickness is 20–40 nm, preferably 25–35 nm. This copper seed layer is used to improve the conductivity of the leaf vein surface and serves as a conductive base layer for subsequent silver electroplating.

[0024] (3) Preparation of the silver conductive layer. Using the leaf veins after copper deposition as the cathode and a silver sheet as the anode, silver electroplating is performed in a silver plating solution under constant current or constant current density conditions, so that the silver layer is uniformly deposited on the surface of the copper layer, forming a copper / silver composite conductive leaf vein network. The electroplating temperature is 15-40℃, preferably 20-30℃, and the current density is 0.1-0.5A / dm³. 2 Preferably 0.2–0.3 A / dm 2 The silver layer thickness is 30–70 nm, preferably 40–50 nm. The silver layer thickness, leaf vein network resistance, and temperature response performance can be adjusted by regulating the electroplating time, current density, and electroplating solution concentration.

[0025] The silver plating solution can be a commercially available silver plating solution or can be prepared in-house. A self-prepared silver plating solution comprises the following components: AgNO3 4–6 g / L; Na2S2O3 200–300 g / L; K2S2O5 40–50 g / L; thioaminourea 0.5–0.7 g / L; polyethyleneimine 0.08 g / L; the balance being deionized water. Na2S2O3 acts as a complexing agent, K2S2O5 is used to improve the stability of the plating solution, and thioaminourea and polyethyleneimine are used to regulate the silver deposition morphology and improve the density and smoothness of the coating.

[0026] (4) Sensor Structure Fabrication. After silver electroplating, the metallized leaf veins are removed, cleaned with deionized water, and dried. Subsequently, according to actual application requirements, the metallized leaf veins are processed into the required sensor shape using methods such as cutting, laser cutting, or die-cutting. Electrodes are then placed at both ends of the sensor. The electrodes can be one of silver paste electrodes, conductive adhesive electrodes, copper foil tape electrodes, metal wire electrodes, or vapor-deposited metal electrodes, and are fixed with encapsulating adhesive or flexible tape to form a temperature sensor that can be attached to the surface of human skin.

[0027] like Figure 1 The diagram shown is a schematic diagram and a photograph of the temperature sensor fabricated according to the present invention. Figure 2 As shown, the natural hierarchical porous network structure of the leaf veins is still completely preserved after metallization treatment.

[0028] Example 1

[0029] This embodiment provides a leaf vein-based, breathable, transparent, wearable temperature sensor with low metal layer thickness, the preparation method of which includes the following steps: (1) Selection and cleaning of leaf veins. Select magnolia leaf veins with complete morphology, clear main and lateral vein structures, no obvious damage or breakage as the bio-based framework. Gently rinse the magnolia leaf veins in deionized water to remove surface dust and soluble impurities, and then wash them in ethanol for 1-3 minutes to further remove surface organic residues.

[0030] (2) Drying treatment. Place the cleaned magnolia leaf veins in a room temperature environment to dry naturally.

[0031] (3) Ultraviolet ozone pretreatment. The dried magnolia leaf veins were placed under an ultraviolet ozone lamp for 3 minutes to further remove organic pollutants from the leaf vein surface and improve the adhesion of the leaf vein surface to the subsequent metal layer.

[0032] (4) Copper seed layer deposition. The pretreated magnolia leaf veins were fixed on the sample stage of the thermal evaporation equipment, and the vacuum was drawn to 5×10⁻⁶. -4 The pressure was below Pa. Subsequently, the copper source was heated and evaporated at a heating current of 90 A to deposit a copper seed layer on the surface of the magnolia leaf veins. The copper layer thickness was 20 nm.

[0033] (5) Preparation of silver electroplating solution. The silver electroplating solution comprises: AgNO3 4 g / L, Na2S2O3 200 g / L, K2S2O5 40 g / L, thioaminourea 0.5 g / L, polyethyleneimine 0.08 g / L, with the remainder being deionized water. The above components are stirred thoroughly until completely dissolved to obtain a homogeneous silver electroplating solution.

[0034] (6) Silver electroplating. Using the magnolia leaf veins after copper deposition as the cathode, and connecting a silver sheet to the positive terminal of the power supply as the anode, electroplating was performed in the aforementioned silver electroplating solution. Constant current density electroplating was conducted at 20°C, with a current density of 0.1 A / dm³. 2 The silver layer was electroplated to a thickness of 30nm.

[0035] (7) Cleaning and drying. After electroplating, the metallized leaf veins are removed and rinsed with deionized water 2 to 3 times to remove residual electroplating solution on the surface. Then, they are naturally dried at room temperature to obtain a copper / silver composite metallized leaf vein conductive network.

[0036] (8) Electrode setup. Conductive silver paste is coated at both ends of the metallized leaf veins and connected with metal wires to form two test electrodes.

[0037] Performance testing: The obtained sensor has a transmittance greater than 85% and a temperature coefficient of resistance of 0.0037℃. -1 It has good transparency, breathability and flexible adhesion properties.

[0038] Example 2

[0039] This embodiment provides a leaf vein-based, breathable, transparent, wearable temperature sensor with medium to low metal layer thickness, the preparation method of which includes the following steps: (1) Selection and cleaning of leaf veins. Select magnolia leaf veins with complete morphology, clear main and lateral vein structures, no obvious damage or breakage as the bio-based framework. Gently rinse the magnolia leaf veins in deionized water to remove surface dust and soluble impurities, and then wash them in ethanol for 1-3 minutes to further remove surface organic residues.

[0040] (2) Drying treatment. Place the cleaned magnolia leaf veins in a 40℃ oven for 20 minutes to keep the surface of the leaf veins dry.

[0041] (3) Ultraviolet ozone pretreatment. The dried magnolia leaf veins were placed under an ultraviolet ozone lamp for 5 minutes to further remove organic pollutants from the leaf vein surface and improve the adhesion of the leaf vein surface to the subsequent metal layer.

[0042] (4) Copper seed layer deposition. The pretreated magnolia leaf veins were fixed on the sample stage of the thermal evaporation equipment, and the vacuum was drawn to 5×10⁻⁶. -4 The pressure was below Pa. Subsequently, the copper source was heated and evaporated at a heating current of 100A to deposit a copper seed layer on the surface of the magnolia leaf veins, with a copper layer thickness of 25nm.

[0043] (5) Preparation of silver electroplating solution. The silver electroplating solution includes: AgNO3 5g / L, Na2S2O3 220g / L, K2S2O5 42g / L, thioaminourea 0.55g / L, polyethyleneimine 0.08g / L, and the balance is deionized water.

[0044] (6) Silver electroplating. Using the magnolia leaf veins after copper deposition as the cathode, and connecting a silver sheet to the positive terminal of the power supply as the anode, electroplating was performed in the aforementioned silver electroplating solution. Constant current density electroplating was conducted at 25°C, with a current density of 0.2 A / dm³. 2 The silver layer was electroplated to a thickness of 40nm.

[0045] (7) Cleaning and drying. After electroplating, the metallized leaf veins are removed and rinsed with deionized water 2 to 3 times to remove residual electroplating solution on the surface. Then, they are naturally dried at room temperature to obtain a copper / silver composite metallized leaf vein conductive network.

[0046] (8) Cutting. Cut the metallized leaf veins into long strips that are suitable for human skin to adhere to.

[0047] (9) Electrode setup. Copper foil tape is attached to both ends of the metallized leaf veins as electrodes.

[0048] Performance testing: The obtained sensor has a transmittance greater than 83% and a temperature coefficient of resistance of 0.0038℃. -1It can maintain a stable resistance response after being bent 1000 times at a radius of curvature of 5mm.

[0049] Example 3

[0050] This embodiment provides a leaf vein-based, breathable, transparent, wearable temperature sensor under preferred parameter conditions, and its preparation method includes the following steps: (1) Selection and cleaning of leaf veins. Select magnolia leaf veins with complete morphology, clear main and lateral vein structures, no obvious damage or breakage as the bio-based framework. Gently rinse the magnolia leaf veins in deionized water to remove surface dust and soluble impurities, and then wash them in ethanol for 1-3 minutes to further remove surface organic residues.

[0051] (2) Drying treatment. Place the cleaned magnolia leaf veins at 40℃ for 30 minutes to dry.

[0052] (3) Ultraviolet ozone pretreatment. The dried magnolia leaf veins were placed under an ultraviolet ozone lamp for 8 minutes to further remove organic pollutants from the leaf vein surface and improve the adhesion of the leaf vein surface to the subsequent metal layer.

[0053] (4) Copper seed layer deposition. The pretreated magnolia leaf veins were fixed on the sample stage of the thermal evaporation equipment, and the vacuum was drawn to 5×10⁻⁶. -4 Pa below. Subsequently, the copper source was heated and evaporated at a heating current of 110 A, and a copper seed layer with a thickness of 30 nm was deposited on the surface of the magnolia leaf veins.

[0054] (5) Preparation of silver electroplating solution. The silver electroplating solution comprises: AgNO3 5 g / L, Na2S2O3 250 g / L, K2S2O5 45 g / L, thioaminourea 0.6 g / L, polyethyleneimine 0.08 g / L, with the balance being deionized water. The above components are stirred thoroughly until completely dissolved to obtain a homogeneous silver electroplating solution.

[0055] (6) Silver electroplating. Using the magnolia leaf veins after copper deposition as the cathode, and connecting a silver sheet to the positive terminal of the power supply as the anode, electroplating was performed in the aforementioned silver electroplating solution. Constant current density electroplating was conducted at 25°C, with a current density of 0.25 A / dm³. 2 The silver layer was electroplated to a thickness of 45nm.

[0056] (7) Cleaning and drying. After electroplating, the metallized leaf veins are removed and rinsed with deionized water 2 to 3 times to remove residual electroplating solution on the surface. Then, they are naturally dried at room temperature to obtain a copper / silver composite metallized leaf vein conductive network.

[0057] (8) Cutting. Cut the metallized leaf veins into curved strips.

[0058] (9) Electrode setup. Conductive silver paste is used to fix metal wires at both ends of the metallized leaf veins to form two test electrodes.

[0059] Performance testing: The obtained sensor was placed under different temperature environments to test its resistance change. The transmittance was greater than 82%, and the temperature coefficient of resistance was 0.0038℃. -1 When this structure is attached to the back of the hand or wrist, it adheres well to the skin surface and exhibits good breathability due to the natural porous structure of the leaf veins.

[0060] Example 4

[0061] This embodiment provides a leaf vein-based, breathable, transparent wearable temperature sensor with high conductivity, the preparation method of which includes the following steps: (1) Selection and cleaning of leaf veins. Select magnolia leaf veins with complete morphology, clear main and lateral vein structures, no obvious damage or breakage as the bio-based framework. Gently rinse the magnolia leaf veins in deionized water to remove surface dust and soluble impurities, and then wash them in ethanol for 1-3 minutes to further remove surface organic residues.

[0062] (2) Drying treatment. Place the cleaned magnolia leaf veins in a room temperature environment to dry naturally.

[0063] (3) Ultraviolet ozone pretreatment. The dried magnolia leaf veins were placed under an ultraviolet ozone lamp for 10 minutes to further remove organic pollutants from the leaf vein surface and improve the adhesion of the leaf vein surface to the subsequent metal layer.

[0064] (4) Copper seed layer deposition. The pretreated magnolia leaf veins were fixed on the sample stage of the thermal evaporation equipment, and the vacuum was drawn to 5×10⁻⁶. -4 The pressure was below Pa. Subsequently, the copper source was heated and evaporated at a heating current of 115 A to deposit a copper seed layer on the surface of the magnolia leaf veins. The copper layer thickness was 35 nm.

[0065] (5) Preparation of silver electroplating solution. The silver electroplating solution comprises: AgNO3 6 g / L, Na2S2O3 280 g / L, K2S2O5 48 g / L, thioaminourea 0.65 g / L, polyethyleneimine 0.08 g / L, with the balance being deionized water. The above components are stirred thoroughly until completely dissolved to obtain a homogeneous silver electroplating solution.

[0066] (6) Silver electroplating. Using the magnolia leaf veins after copper deposition as the cathode, and connecting a silver sheet to the positive terminal of the power supply as the anode, electroplating was performed in the aforementioned silver electroplating solution. Constant current density electroplating was conducted at 30°C, with a current density of 0.3 A / dm³. 2 The silver layer is electroplated to a thickness of 50nm.

[0067] (7) Cleaning and drying. After electroplating, the metallized leaf veins are removed and rinsed with deionized water 2 to 3 times to remove residual electroplating solution on the surface. Then, they are naturally dried at room temperature to obtain a copper / silver composite metallized leaf vein conductive network.

[0068] (8) Cutting. Cut the metallized veins into the desired shape.

[0069] (9) Electrode setup. Flexible conductive electrodes are set at both ends of the metallized leaf veins. The flexible conductive electrodes are silver paste electrodes.

[0070] Performance testing: The obtained sensor has a transmittance greater than 80% and a temperature coefficient of resistance of 0.0039℃. -1 Due to the good continuity of the silver layer, this structure exhibits low electrical resistance and stable temperature response. After undergoing 1000 bending tests at a 5mm radius of curvature, the structure maintained stable conductivity and temperature response.

[0071] Example 5

[0072] This embodiment provides a leaf vein-based, breathable, transparent, wearable temperature sensor with a high metal layer thickness, the preparation method of which includes the following steps: (1) Selection and cleaning of leaf veins. Select magnolia leaf veins with complete morphology, clear main and lateral vein structures, no obvious damage or breakage as the bio-based framework. Gently rinse the magnolia leaf veins in deionized water to remove surface dust and soluble impurities, and then wash them in ethanol for 1-3 minutes to further remove surface organic residues.

[0073] (2) Drying treatment. Place the cleaned magnolia leaf veins in a room temperature environment to dry naturally.

[0074] (3) Ultraviolet ozone pretreatment. The dried magnolia leaf veins were placed under an ultraviolet ozone lamp for 6 minutes to further remove organic pollutants from the leaf vein surface and improve the adhesion of the leaf vein surface to the subsequent metal layer.

[0075] (4) Copper seed layer deposition. The pretreated magnolia leaf veins were fixed on the sample stage of the thermal evaporation equipment, and the vacuum was drawn to 5×10⁻⁶. -4 The pressure was below Pa. Subsequently, the copper source was heated and evaporated at a heating current of 120 A to deposit a copper seed layer on the surface of the magnolia leaf veins. The copper layer thickness was 40 nm.

[0076] (5) Preparation of silver electroplating solution. The silver electroplating solution comprises: AgNO3 6 g / L, Na2S2O3 300 g / L, K2S2O5 50 g / L, thioaminourea 0.7 g / L, polyethyleneimine 0.08 g / L, with the remainder being deionized water. The above components are stirred thoroughly until completely dissolved to obtain a homogeneous silver electroplating solution.

[0077] (6) Silver electroplating. Using the magnolia leaf veins after copper deposition as the cathode, and connecting a silver sheet to the positive terminal of the power supply as the anode, electroplating was performed in the aforementioned silver electroplating solution. Constant current density electroplating was conducted at 35°C, with a current density of 0.5 A / dm³. 2 The silver layer was electroplated to a thickness of 70nm.

[0078] (7) Cleaning and drying. After electroplating, the metallized leaf veins are removed and rinsed with deionized water 2 to 3 times to remove residual electroplating solution on the surface. Then, they are naturally dried at room temperature to obtain a copper / silver composite metallized leaf vein conductive network.

[0079] (8) Cutting. Cut the metallized leaf veins into curved strips.

[0080] (9) Electrode setup. The metal wires are fixed at both ends of the metallized leaf veins with conductive adhesive, and the electrode connections are fixed with flexible tape.

[0081] Performance testing: The obtained sensor was subjected to different temperature conditions to test its resistance change. The obtained structure has low resistance, with a temperature coefficient of resistance of 0.0039℃. -1 With a light transmittance greater than 80%, it maintains stable conductivity after being bent 1000 times at a radius of curvature of 5mm. Due to the large number of natural pores retained in the leaf vein network, this structure maintains air exchange and sweat evaporation channels when attached to the skin, providing excellent breathability and wearing comfort.

[0082] like Figure 3 As shown, the bio-based wearable breathable and transparent temperature sensor prepared using the methods of the above embodiments uses a leaf vein metal conductive network as the temperature-sensitive layer. When the external temperature changes, the resistance change rate of the metal conductive layer on the leaf vein surface increases linearly with increasing temperature, thereby achieving temperature detection. The temperature coefficient of resistance of the sensor is 0.0037–0.0039℃. -1 With a light transmittance greater than 80%, it maintains stable resistance response performance even after being bent 1000 times at a curvature radius of 5mm. Furthermore, due to the natural porous network structure of the leaf vein skeleton, the fabricated sensor exhibits excellent breathability, flexibility, skin fit, and wearing comfort, making it suitable for real-time monitoring of human body surface temperature, health alerts, motion monitoring, and wearable electronic devices.

[0083] It should be noted that the above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A leaf vein-based, breathable, transparent, wearable temperature sensor, characterized in that: include: The natural leaf vein skeleton comprises a copper seed layer attached to the surface of the natural leaf vein skeleton, a silver conductive layer attached to the surface of the copper seed layer, and electrodes disposed at both ends of the natural leaf vein skeleton. The thickness of the copper seed layer is 20–40 nm, and the thickness of the silver conductive layer is 30–70 nm. The copper seed layer and the silver conductive layer form a continuous metallic conductive network on the surface of the natural leaf vein skeleton, and the natural leaf vein skeleton retains its natural hierarchical porous network structure.

2. The leaf vein-based bio-based breathable transparent wearable temperature sensor according to claim 1, characterized in that: The natural leaf vein framework is the magnolia leaf vein framework.

3. The leaf vein-based bio-based breathable transparent wearable temperature sensor according to claim 1, characterized in that: The thickness of the copper seed layer is 25–35 nm, and the thickness of the silver conductive layer is 40–50 nm.

4. The leaf vein-based bio-based breathable transparent wearable temperature sensor according to claim 1, characterized in that: The electrode is one of the following: silver paste electrode, conductive adhesive electrode, copper foil tape electrode, metal wire electrode, or vapor-deposited metal electrode.

5. A method for preparing a leaf vein bio-based breathable transparent wearable temperature sensor as described in any one of claims 1 to 4, characterized in that: Includes the following steps: S1. Select intact and clean natural leaf veins, place them under ultraviolet ozone lamp for 3-10 minutes, then wash with deionized water or ethanol and dry. S2, depositing a copper seed layer on the surface of the pretreated natural leaf veins; S3, using the leaf veins after the copper layer is deposited as the cathode and the silver sheet as the anode, a silver conductive layer is electroplated on the surface of the copper seed layer under constant current or constant current density conditions to obtain a copper / silver composite conductive leaf vein network, i.e., metallized leaf veins. S4, electrodes are provided at both ends of the metallized leaf vein.

6. The preparation method according to claim 5, characterized in that: In step S2, the copper seed layer is deposited using a thermal evaporation method with a evaporation vacuum degree lower than 5×10⁻⁶. -4 Pa, heating current is 90-120A.

7. The preparation method according to claim 5, characterized in that: In step S3, the electroplating temperature of the silver conductive layer is 15–40°C, and the current density is 0.1–0.5 A / dm³. 2 .

8. The preparation method according to claim 7, characterized in that: The electroplating temperature for the silver conductive layer is 20–30℃, and the current density is 0.2–0.3 A / dm³. 2 .

9. The preparation method according to claim 5, characterized in that: In step S3, the silver electroplating solution used for electroplating includes the following components: AgNO3 4-6 g / L; Na2S2O3 200-300 g / L; K2S2O5 40-50 g / L; thioaminourea 0.5-0.7 g / L; polyethyleneimine 0.08 g / L; and the balance is deionized water.

10. The preparation method according to claim 5, characterized in that: Before step S4, there is also a step of cutting the metallized leaf veins into the desired shape.

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