Attachable flexible temperature sensor and manufacturing process thereof

Abstract

The invention discloses an attachable flexible temperature sensor and a manufacturing process thereof. The flexible sensor comprises a flexible substrate layer made of a polyimide material; the flexible temperature sensitive layer is arranged on the flexible substrate layer and is formed by polymerizing a carbon material and conductive metal nanoparticles, and the carbon material is graphene or graphene oxide; and the flexible electrode is arranged on the flexible temperature sensitive layer. Compared with a traditional temperature sensor, the flexible temperature sensor has flexibility and still has good sensitivity and response speed on the premise of bending deformation.

Description

Technical Field

[0001] The invention relates to the field of flexible sensors, and in particular to an attachable flexible temperature sensor and a manufacturing process thereof. Background Art

[0002] Temperature measurement has always been a key parameter in many application scenarios of modern technology. Traditional temperature sensors are usually made of rigid materials, such as metals and ceramics, which makes them have many limitations and shortcomings when facing objects with complex surfaces.

[0003] For human body temperature monitoring, traditional rigid sensors cannot fit perfectly with the skin surface, especially in joints, fingers and other parts that move and bend frequently, making it difficult to accurately measure the temperature. This has caused great troubles in disease diagnosis, rehabilitation treatment and daily health monitoring. In the biomedical field, accurate and continuous body temperature monitoring is crucial for timely detection of disease changes and evaluation of treatment effects, but the limitations of traditional sensors make it impossible to meet these high-precision and high-fit requirements.

[0004] In the field of robotics, as the application scenarios of robots continue to expand, the requirements for their tactile perception capabilities are getting higher and higher. When the robot gripper operates an object, it needs to accurately sense the temperature of the object's surface to achieve smarter and safer operations. However, traditional rigid temperature sensors cannot adapt to the shape changes and complex movements of the gripper, and cannot provide accurate temperature information, which limits the application of robots in some temperature-sensitive operations.

[0005] In addition, traditional temperature sensors also have certain limitations in terms of response speed, sensitivity and accuracy. They often take a long time to respond to temperature changes, are not sensitive enough to detect small temperature fluctuations, and their measurement accuracy is difficult to meet some high-precision application scenarios. For example, in some industrial production processes that require precise temperature control, traditional sensors may lead to unstable production quality or low production efficiency.

[0006] In summary, the rigid structure and performance limitations of traditional temperature sensors can no longer meet the high requirements for temperature measurement in current fields such as biomedicine, smart wearable devices, and robot tactile sensing. There is an urgent need for a new type of temperature sensor with good flexibility and high performance to fill this gap. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems in the above-mentioned technology to a certain extent. To this end, one object of the present invention is to provide an attachable flexible temperature sensor, which is soft and bendable, attached to a bent part, and can still effectively measure temperature data after deformation;

[0008] Another object of the present invention is to provide a manufacturing process.

[0009] To achieve the above object, an embodiment of the present invention provides an attachable flexible temperature sensor, comprising:

[0010] Flexible base layer: polyimide material;

[0011] Flexible temperature sensitive layer: arranged on the flexible base layer, formed by polymerization of carbon material and conductive metal nanoparticles, wherein the carbon material is graphene or graphene oxide;

[0012] Flexible electrode: arranged on the flexible temperature sensitive layer.

[0013] Compared with traditional temperature sensors, an attachable flexible temperature sensor according to an embodiment of the present invention has flexibility and can still have good sensitivity and response speed under the premise of bending and deformation.

[0014] In addition, the attachable flexible temperature sensor proposed in the above embodiment of the present invention may also have the following additional technical features:

[0015] Optionally, the flexible temperature sensitive layer is a mosquito coil type or a continuous S type.

[0016] To achieve the above object, an embodiment of the present invention provides a manufacturing process, including:

[0017] Step 1: Select polyimide as the flexible substrate layer, put the flexible substrate layer into a mixture of ethanol and acetone for ultrasonic treatment for 90 to 150 minutes, rinse with deionized water, and blow dry with nitrogen;

[0018] Step 2: Surface treatment of the film substrate using argon oxygen plasma;

[0019] Step 3: preparing graphite oxide;

[0020] Step 4: The graphite oxide is washed with a centrifuge until the pH of the supernatant is neutral, the lower layer of solid is taken out, and dried at 60°C for 20 hours to obtain a single-layer graphene oxide flake. 90 mg of a single-layer graphene oxide flake is added with 200 mL of deionized water and stirred until the single-layer graphene oxide flake is completely dispersed, followed by adding 0.05 g of silver nitrate and 0.05 g of polyvinylpyrrolidone, stirring for 30 minutes, heating the mixture to 100°C, adding 100 mL of 0.6 mg / mL sodium borohydride aqueous solution (3 mL / min), and centrifuging and washing until neutral after 180 minutes, and drying to obtain the desired product.

[0021] Step 5: The product of step 4 was treated with sodium carboxymethyl cellulose as a binder, and the masses of water (10 mL) and the binder (5 mg) were fixed to prepare a conductive ink;

[0022] Step 6: The conductive ink is printed on the flexible substrate processed in step 1 according to the designed pattern to form a flexible temperature sensitive layer;

[0023] Step 7: Curing the structure of step 6 at high temperature in an inert gas atmosphere;

[0024] Step 8: Print the flexible electrode layer on the flexible temperature sensitive layer using conductive silver paste and cure at high temperature.

[0025] The attachable flexible temperature sensor manufactured by the manufacturing method according to the embodiment of the present invention has flexibility compared to the traditional temperature sensor, and can still have good sensitivity and response speed under the premise of bending and deformation.

[0026] In addition, a manufacturing process proposed in the above embodiment of the present invention may also have the following additional technical features:

[0027] Optionally, in step 2, the specific parameters of the argon oxygen plasma are: an argon flow rate of 60 sccm, an oxygen flow rate of 6 sccm, a discharge parameter of a power of 100 W; a surface treatment time of 50 s, and a pressure in the reaction chamber of 200 mTorr.

[0028] Optionally, the graphite oxide in step 3 is prepared in the following manner:

[0029] Low temperature reaction: Mix natural graphite powder, sodium nitrate and concentrated sulfuric acid, stir in an ice water bath, and then add potassium permanganate in portions. Control the temperature not to exceed 20°C, stir for a period of time, remove the ice bath, and continue stirring for 24 hours.

[0030] Medium temperature reaction: Raise the temperature of the reaction system to 35°C and continue stirring for a while.

[0031] High temperature reaction: raise the temperature of the reaction system to 98°C, maintain it for a while, then add hydrogen peroxide to reduce the residual oxidant, turning the solution into bright yellow;

[0032] Optionally, the inert gas in step 7 is nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A three-dimensional overall diagram of the structure according to an embodiment of the present invention;

[0034] Figure 2 A three-dimensional exploded view of a structure according to an embodiment of the present invention;

[0035] Figure 3 FIG. 4 is a structural stereogram according to another embodiment of the present invention.

[0036] Description of labels:

[0037] Flexible base layer 1

[0038] Flexible temperature sensitive layer 2

[0039] Flexible electrode 3

[0040] Wire 4. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] Due to its excellent flexibility, the present invention can be tightly attached to objects with complex curved surfaces such as human skin and robot grippers, greatly expanding the applicable scenarios of temperature measurement and providing an accurate and reliable temperature monitoring method for biomedicine, smart wearable devices, and robot tactile sensing.

[0043] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0044] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0045] Figures 1 to 3 An attachable flexible temperature sensor according to an embodiment of the present invention comprises:

[0046] Flexible base layer 1: polyimide material;

[0047] Flexible temperature sensitive layer 2: arranged on the flexible base layer, formed by polymerization of carbon material and conductive metal nanoparticles, wherein the carbon material is graphene or graphene oxide;

[0048] Flexible electrode 3: arranged on the flexible temperature sensitive layer and electrically connected to an external circuit via a wire 4.

[0049] Optionally, the flexible temperature sensitive layer is a mosquito coil type or a continuous S type.

[0050] Example 1: Human skin temperature monitoring

[0051] According to the shape of the inside of the human wrist, a sheet sensor pattern with a length of 3 cm and a width of 1 cm is designed; the ink is printed on the treated flexible substrate using high-precision inkjet printing technology to form a flexible temperature-sensitive layer with a thickness of about 50 microns; then, a flexible electrode with a width of 1 mm is printed using silver paste by screen printing; after printing, the sensor is placed in a high-temperature oven and cured at 150°C for 1 hour to form the sensor; the prepared sensor is attached to the inside of the human wrist, and the temperature data is transmitted to the mobile phone APP through the Bluetooth module. Users can monitor the changes in human skin temperature in real time and accurately, and can provide stable and reliable temperature data whether at rest or during exercise.

[0052] Example 2: Robot gripper temperature measurement

[0053] Prepare a polyimide flexible substrate with a thickness of 0.2 mm; design a wraparound sensor pattern according to the shape and size of the robot gripper, with a length determined by the circumference of the gripper and a width of 2 mm; when preparing the flexible temperature-sensitive layer material ink, select graphene oxide and gold nanoparticles, and adjust the ratio of each component; use gravure printing technology to print the ink on the treated flexible substrate to form a flexible temperature-sensitive layer; use silver paste to print the flexible electrode by pad printing; after curing at 180°C for 2 hours, install the sensor on the inner surface of the robot gripper and connect it to the robot's control system via a data cable; when the gripper grasps objects of different temperatures, the sensor can quickly sense and transmit temperature information to help the robot system make more accurate control decisions, such as avoiding damage caused by grasping high-temperature objects or adjusting the grasping force according to the temperature of the object.

[0054] Example 3: Integrated application in wearable devices

[0055] For smart bracelets, a polyimide substrate with a thickness of 0.05 mm and excellent flexibility is selected; according to the arc structure of the bracelet, a slender arc sensor pattern is designed with a length of 5 cm and a width of 0.5 cm; when preparing the flexible temperature-sensitive layer material ink, a combination of graphene and platinum nanoparticles is used, and the choice of solvent is optimized; the ink is accurately printed on the flexible substrate through photolithography technology to form a flexible temperature-sensitive layer; the silver paste is deposited by magnetron sputtering to form a flexible electrode. The curing treatment is carried out at 120°C for 1.5 hours; the sensor is integrated into the bracelet and connected to a mobile phone or other terminal device via Bluetooth to provide users with real-time body temperature or ambient temperature information for health management or environmental adaptation prompts.

[0056] The above sensor can be manufactured by the following processes, including:

[0057] Step 1: Select polyimide as the flexible substrate layer, put the flexible substrate layer into a mixture of ethanol and acetone for ultrasonic treatment for 90 to 150 minutes, rinse with deionized water, and blow dry with nitrogen;

[0058] Step 2: Surface treatment of the film substrate using argon oxygen plasma;

[0059] Optionally, in step 2, the specific parameters of the argon oxygen plasma are: an argon flow rate of 60 sccm, an oxygen flow rate of 6 sccm, a discharge parameter of a power of 100 W; a surface treatment time of 50 s, and a pressure in the reaction chamber of 200 mTorr.

[0060] Step 3: preparing graphite oxide;

[0061] Optionally, graphite oxide is prepared in the following manner:

[0062] Low temperature reaction: Mix natural graphite powder, sodium nitrate and concentrated sulfuric acid, stir in an ice water bath, then add potassium permanganate in portions, control the temperature not to exceed 20°C, stir for a period of time, remove the ice bath, and continue stirring for 24 hours.

[0063] Medium temperature reaction: Raise the temperature of the reaction system to 35°C and continue stirring for a while.

[0064] High temperature reaction: Raise the temperature of the reaction system to 98°C, maintain it for a while, then add hydrogen peroxide to reduce the residual oxidant, turning the solution into bright yellow.

[0065] Step 4: Wash the graphite oxide with a centrifuge until the pH of the supernatant is neutral, take out the lower solid, and dry it at 60°C for 20 hours to obtain a single-layer graphene oxide flake. Take 90 mg of a single-layer graphene oxide flake and add 200 mL of deionized water and stir until the single-layer graphene oxide flake is completely dispersed, then add 0.05 g of silver nitrate and 0.05 g of polyvinylpyrrolidone and stir for 30 minutes. Heat the mixture to 100°C, add 100 mL of 0.6 mg / mL sodium borohydride aqueous solution (3 mL / min), centrifuge and wash until neutral after 180 minutes, and dry to obtain the desired product.

[0066] The scheme of the present invention adopts thermosensitive materials to make sensors in terms of material selection. This thermosensitive material is a polymer material based on carbon materials (such as graphene or graphene oxide) and composited with conductive metal nanoparticles. It has the characteristic of producing significant electrical signal changes due to temperature changes and can sensitively sense slight changes in temperature. Among them, carbon materials have extremely high temperature sensitivity, and their resistance-temperature characteristics show good linearity, and the resistance changes when bent at different angles are negligible. In addition, metal materials such as platinum, gold and some metal oxides are also suitable temperature-sensitive materials. By optimizing the polymer of carbon materials and metal nanoparticles, the high-temperature resistivity is improved, thereby significantly improving the temperature sensing performance.

[0067] Step 5: The product of step 4 was treated with sodium carboxymethyl cellulose as a binder, and the masses of water (10 mL) and the binder (5 mg) were fixed to prepare a conductive ink;

[0068] Step 6: The conductive ink is printed on the flexible substrate processed in step 1 according to the designed pattern to form a flexible temperature sensitive layer;

[0069] Step 7: Curing the structure of step 6 at high temperature in an inert gas atmosphere;

[0070] Step 8: Print the flexible electrode layer on the flexible temperature sensitive layer using conductive silver paste and cure at high temperature.

[0071] In terms of structural design, the structure of the flexible temperature sensor is carefully designed to consist of a flexible temperature sensitive layer, a flexible base layer and a flexible electrode; the flexible temperature sensitive layer is directly responsible for temperature perception and signal conversion, the flexible base layer provides support and attachment basis for the entire sensor, and the flexible electrode ensures the stable transmission of electrical signals; the synergistic effect of this layered structure enables the sensor to measure temperature stably and accurately while maintaining flexibility.

[0072] In order to realize the preparation of the above-mentioned flexible temperature-sensitive layer, a flexible temperature-sensitive layer material ink was developed, and the specific development process is as follows: first, the polymer particles are screened and pretreated to ensure that their purity and particle size distribution meet the requirements; then, the selected polymer particles are dissolved in a specific solvent, and the selection of the solvent should take into account its solubility in the polymer and its adaptability to the subsequent printing process; during the dissolution process, the dissolution is accelerated by stirring, heating, etc., and the solution is ensured to be uniform; then, specific additives are added, which may include surfactants to improve the fluidity of the ink, dispersants to enhance the stability of the ink, and cross-linking agents to adjust the curing properties of the ink; the type and amount of additives must be strictly controlled during the addition process to achieve the purpose of optimizing the ink performance; then, the initially prepared ink is filtered and defoamed to remove impurities and bubbles to ensure the purity and uniformity of the ink; finally, the various properties of the ink are tested and evaluated, such as viscosity, surface tension, curing speed, etc., and the ink formula is adjusted and optimized according to the test results until the ideal performance indicators are achieved.

[0073] Optionally, the inert gas in step 7 is nitrogen.

[0074] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0075] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0076] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0077] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An attachable flexible temperature sensor, characterized in that: include Flexible base layer: polyimide material; Flexible temperature sensitive layer: arranged on the flexible base layer, formed by polymerization of carbon material and conductive metal nanoparticles, wherein the carbon material is graphene or graphene oxide; Flexible electrode: arranged on the flexible temperature sensitive layer.

2. The attachable flexible temperature sensor according to claim 1, characterized in that: The flexible temperature sensitive layer is a mosquito coil type or a continuous S type.

3. A process for manufacturing an attachable flexible temperature sensor according to any one of claim 1 or claim 2, characterized in that: include Step 1: Select polyimide as the flexible substrate layer, put the flexible substrate layer into a mixture of ethanol and acetone for ultrasonic treatment for 90 to 150 minutes, rinse with deionized water, and blow dry with nitrogen; Step 2: Surface treatment of the film substrate using argon oxygen plasma; Step 3: preparing graphite oxide; Step 4: Wash the graphite oxide with a centrifuge until the pH of the supernatant is neutral, take out the lower solid, and dry it at 60°C for 20 hours to obtain a single-layer graphene oxide flake; take 90 mg of a single-layer graphene oxide flake and add 200 mL of deionized water and stir until the single-layer graphene oxide flake is completely dispersed, then add 0.05 g of silver nitrate and 0.05 g of polyvinylpyrrolidone and stir for 30 minutes; heat the mixture to 100°C, add 100 mL of 0.6 mg / mL sodium borohydride aqueous solution (3 mL / min), centrifuge and wash until neutral after 180 minutes, and dry to obtain the desired product. ; Step 5: The product of step 4 is treated with sodium carboxymethyl cellulose as a binder, and the masses of water (10 mL) and the binder (5 mg) are fixed to prepare a conductive ink; Step 6: The conductive ink is printed on the flexible substrate processed in step 1 according to the designed pattern to form a flexible temperature sensitive layer; Step 7: Curing the structure of step 6 at high temperature in an inert gas atmosphere; Step 8: Print the flexible electrode layer on the flexible temperature sensitive layer using conductive silver paste and cure at high temperature.

4. The manufacturing process according to claim 3, characterized in that: The specific parameters of the argon oxygen plasma in step 2 are: argon flow rate is 60 sccm, oxygen flow rate is 6 sccm, discharge parameter is power 100 W; surface treatment time is 50 s, and the pressure in the reaction chamber is 200 mTorr.

5. The manufacturing process according to claim 3, characterized in that: Step 3: Graphite oxide is prepared in the following manner: Low temperature reaction: Mix natural graphite powder, sodium nitrate and concentrated sulfuric acid, stir in an ice water bath, then add potassium permanganate in portions; control the temperature not to exceed 20°C, stir for a period of time, remove the ice bath, and continue stirring for 24 hours; Medium temperature reaction: raise the temperature of the reaction system to 35°C and continue stirring for a while; High temperature reaction: Raise the temperature of the reaction system to 98°C, maintain it for a while, then add hydrogen peroxide to reduce the residual oxidant, turning the solution into bright yellow.

6. The manufacturing process according to claim 3, characterized in that: The inert gas in step 7 is nitrogen.

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