Flexible temperature sensor and preparation method and application thereof

Abstract

The invention belongs to the technical field of sensors, and particularly relates to a flexible temperature sensor and a preparation method and application thereof. The preparation method of the flexible temperature sensor comprises the following steps: preparing a flexible substrate; preparing ink containing a transition metal oxide and a conductive polymer, and depositing the ink on the surface of the flexible substrate to form a temperature sensing layer; preparing an electrode on the surface of the temperature sensing layer; and preparing a packaging layer, wherein the packaging layer packages a device comprising the flexible substrate, the temperature sensing layer and the electrode. According to the method, a high-temperature annealing form is not needed, the temperature sensing layer containing the transition metal oxide can be prepared under a relatively low temperature condition, the limitation of a high-temperature condition on selection of a flexible substrate material is avoided, and the selection range of the substrate material is widened. By adjusting the ratio of the transition metal oxide to the conductive polymer in the ink, the sensitivity of the flexible temperature sensor can be flexibly adjusted, and development of a larger application range and potential is facilitated.

Description

Technical Field

[0001] The present application belongs to the field of sensor technology, and in particular relates to a flexible temperature sensor and a preparation method and application thereof. Background Art

[0002] Temperature is one of the most basic physical signals in human activities and can reflect biological activities and health. The process of industrial modernization and the continuous high-speed growth of the electronic information industry have driven the rapid rise of the sensor market. As an important type of sensor, temperature sensors account for a large proportion of the total sensor demand market and have a wide range of uses. Temperature sensors are semiconductor devices that use the characteristics of power thermistors (NTCs) that the resistance value changes with temperature to convert non-electrical physical quantities into electrical quantities, thereby enabling accurate temperature measurement and automatic control. At present, most thermal resistor temperature sensors are made of metal. The most commonly used thermal resistors are platinum thermal resistors and copper thermal resistors. However, these sensors are made of non-flexible materials and are mostly rod-shaped or block-shaped. When in use, they are directly placed at the measuring point of the device to be measured or inserted into the device. These temperature sensors generally cannot be bent and can only measure the temperature of objects with flat surfaces. They have poor biocompatibility and require additional sensor packaging. In some scenarios, there may be complex structural designs, limited layout space, or the measuring point position of the structural parts is a complex surface such as a curved surface or a cylindrical surface.

[0003] Flexible temperature sensors can be directly and conformally attached to the surface of the skin and can continuously track the skin surface temperature in real time, thereby improving the quality of life. Thermistor-type flexible temperature sensors have attracted the interest of researchers due to their high sensitivity, simple device structure and low cost. Transition metal oxides have excellent stability and high temperature sensitivity and are promising materials for making thermistor-type flexible temperature sensors. However, typical transition metal oxide-based thermosensitive materials often require high-temperature annealing (above 200°C) to form or activate. However, most flexible substrates are not compatible with such high-temperature annealing conditions, which limits the choice of flexible substrates and also increases energy consumption. Summary of the invention

[0004] The purpose of the present application is to provide a flexible temperature sensor and a preparation method and application thereof, aiming to solve to a certain extent the problem that existing thermosensitive materials based on transition metal oxides often require high temperature annealing, which limits the selection of flexible substrates in flexible temperature sensors.

[0005] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0006] In a first aspect, the present application provides a method for preparing a flexible temperature sensor, comprising the following steps:

[0007] preparing a flexible substrate;

[0008] Preparing an ink comprising a transition metal oxide and a conductive polymer, and depositing the ink on the surface of the flexible substrate to form a temperature sensing layer;

[0009] Prepare electrodes on the surface of the temperature sensing layer;

[0010] A packaging layer is prepared, wherein the packaging layer forms a package for the device including the flexible substrate, the temperature sensing layer and the electrode.

[0011] In some possible implementations, the transition metal oxide includes at least one of vanadium dioxide, nickel oxide, and tungsten oxide.

[0012] In some possible implementations, the conductive polymer includes at least one of PEDOT:PSS, polypyrrole, and S-PEDOT.

[0013] In some possible implementations, in the ink, the mass ratio of the transition metal oxide to the conductive polymer is 100:(2.5-7.5).

[0014] In some possible implementations, the ratio of solute to solvent in the ink is 50 mg: (3-8) ml.

[0015] In some possible implementations, the solvent in the ink includes at least one of water, ethanol, and acetone.

[0016] In some possible implementations, the thickness of the flexible substrate is 80-200 μm.

[0017] In some possible implementations, the porosity of the flexible substrate is 60-90%.

[0018] In some possible implementations, the temperature sensing layer has a thickness of 1 to 10 μm.

[0019] In some possible implementations, the thickness of the electrode is 150-250 nm.

[0020] In some possible implementations, the encapsulation layer has a thickness of 1 to 1.5 μm.

[0021] In some possible implementations, the step of preparing the temperature sensing layer includes: spraying the ink on the surface of the flexible substrate, low-temperature drying at a temperature of 25 to 100° C., and forming the temperature sensing layer on the surface of the flexible substrate.

[0022] In some possible implementations, the preparation step of the flexible substrate includes: using a high molecular polymer as a raw material, forming a porous flexible layer by electrospinning, and performing a hydrophilic treatment on the surface of the porous flexible layer to obtain the flexible substrate.

[0023] In some possible implementations, the step of preparing the electrode includes: depositing electrode material on the surface of the temperature sensing layer by at least one method of electron beam evaporation, screen printing or inkjet printing to form the electrode, and the electrode is used to form an electrical connection with a power source.

[0024] In some possible implementations, the step of preparing the encapsulation layer includes: forming the encapsulation layer from an insulating polymer material by chemical vapor deposition or spin coating.

[0025] In some possible implementations, the total loading amount of the transition metal oxide and the conductive polymer in the ink on the surface of the flexible substrate is 4 to 6 mg / cm 2 .

[0026] In some possible implementations, the hydrophilic treatment method includes oxygen plasma treatment.

[0027] In some possible implementations, the high molecular polymer includes at least one of styrene-butadiene-styrene triblock polymer, polyurethane, polyimide, and styrene butadiene block copolymer.

[0028] In some possible implementations, the electrode material includes at least one of silver, gold, copper, platinum, palladium, iridium, carbon nanotubes, graphene, and PEDOT:PSS.

[0029] In some possible implementations, the insulating polymer material includes at least one of polyparaxylene and polydimethylsiloxane.

[0030] In a second aspect, the present application provides a flexible temperature sensor, which is manufactured using the above method.

[0031] In some possible implementations, the sensitivity of the flexible temperature sensor is -1%℃ -1 ~-3%℃ -1 .

[0032] In a third aspect, the present application provides a flexible device, which includes the flexible temperature sensor prepared by the above method or the above flexible temperature sensor.

[0033] The preparation method of the flexible temperature sensor provided in the first aspect of the present application, after mixing transition metal oxides and conductive polymers to configure ink, the ink is deposited on the surface of the flexible substrate, and the transition metal oxides in the ink have excellent stability and high temperature sensitivity. The conductive polymer can be used as a conductive agent to assist the transmission of electrons between transition metal oxides, and can also be used as a binder to connect transition metal oxide particles into one under the action of chemical bonds and intermolecular forces, forming a temperature sensing layer on the surface of the flexible substrate. Therefore, without the need for high-temperature annealing, a temperature sensing layer containing transition metal oxides can be prepared under low temperature conditions, which not only saves energy and is environmentally friendly, but also avoids the restrictions of high temperature conditions on the selection of flexible substrate materials, and broadens the selection range of substrate materials. In addition, by adjusting the ratio of transition metal oxides and conductive polymers in the ink, the sensitivity of the flexible temperature sensor can be flexibly adjusted, which is conducive to the development of a larger range of applications and potential. In addition, the preparation method of the flexible temperature sensor is simple and suitable for industrial large-scale production and application needs.

[0034] The flexible temperature sensor provided in the second aspect of the present application is manufactured by the above method, has high flexibility and detection sensitivity, and has a wide range of flexible substrate materials to choose from, and has a greater range of applications and potential.

[0035] The flexible device provided in the third aspect of the present application, because it includes the above-mentioned flexible temperature sensor, can continuously track temperature changes in real time, has high sensitivity and good flexibility. It is directly attached to the skin surface in a conformal manner and can continuously track the skin surface temperature in real time, thereby improving the quality of life. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 It is a schematic diagram of a process for preparing a flexible temperature sensor provided in an embodiment of the present application;

[0038] Figure 2 is a schematic diagram of the structure of the flexible temperature sensor provided in an embodiment of the present application;

[0039] Figure 3 is a schematic diagram of the preparation process of the flexible temperature sensor provided in Example 1 of the present application;

[0040] Figure 4 is a curve showing a change in resistance versus temperature of the flexible temperature sensor provided in Example 1 of the present application;

[0041] Figure 5 This is a test chart of the response time and recovery time of the flexible temperature sensor provided in Example 1 of the present application under the condition of a temperature of 24° C. to 42° C.;

[0042] Figure 6 is a curve diagram showing the change in device resistance versus temperature of the flexible temperature sensor provided in Example 1 of the present application;

[0043] Figure 7 This is a bending stability test diagram of the flexible temperature sensor provided in Example 1 of the present application;

[0044] Figure 8 This is a test chart of the absolute value of the sensitivity of the flexible temperature sensor provided in Examples 1, 2, and 3 of the present application. DETAILED DESCRIPTION

[0045] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0046] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0047] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0048] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0049] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0050] The weight of the relevant components mentioned in the embodiments of the present specification can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components in the embodiments of the present specification is proportionally enlarged or reduced, it is within the scope disclosed in the embodiments of the present specification. Specifically, the mass in the embodiments of the present specification can be μg, mg, g, kg and other mass units known in the chemical industry.

[0051] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0052] As attached Figure 1 As shown, a first aspect of an embodiment of the present application provides a method for preparing a flexible temperature sensor, comprising the following steps:

[0053] S10. Preparing a flexible substrate;

[0054] S20. preparing an ink comprising a transition metal oxide and a conductive polymer, and depositing the ink on a surface of a flexible substrate to form a temperature sensing layer;

[0055] S30. Preparing an electrode on the surface of the temperature sensing layer;

[0056] S40. Prepare a packaging layer, which packages the device including the flexible substrate, the temperature sensing layer and the electrode.

[0057] The preparation method of the flexible temperature sensor provided in the first aspect of the embodiment of the present application, after mixing the transition metal oxide and the conductive polymer to configure the ink, the ink is deposited on the surface of the flexible substrate, and the transition metal oxide in the ink has excellent stability and high temperature sensitivity. The conductive polymer can be used as a conductive agent to assist the transmission of electrons between the transition metal oxides, and can also be used as a binder to connect the transition metal oxide particles into one under the action of chemical bonds and intermolecular forces, forming a temperature sensing layer on the surface of the flexible substrate. Therefore, without the need for high-temperature annealing, the temperature sensing layer containing the transition metal oxide can be prepared under low temperature conditions, which not only saves energy and is environmentally friendly, but also avoids the restriction of high temperature conditions on the selection of flexible substrate materials, and broadens the selection range of substrate materials. The high-sensitivity flexible temperature sensor is prepared by a low-temperature and efficient manufacturing process, which improves the problem that the traditional transition metal oxide-based temperature sensor requires high-temperature annealing, thereby limiting the selection of flexible substrate materials. In addition, by adjusting the ratio of the transition metal oxide and the conductive polymer in the ink, the sensitivity of the flexible temperature sensor can be flexibly adjusted, which is conducive to the development of a larger range of applications and potential. In addition, the preparation method of the flexible temperature sensor is simple and suitable for industrial large-scale production and application needs.

[0058] In the above step S10, a flexible substrate is prepared. In some possible implementations, the preparation steps of the flexible substrate include: using a high molecular polymer as a raw material, making a porous flexible layer by electrospinning, and hydrophilizing the surface of the porous flexible layer to obtain a flexible substrate. In this case, the flexible substrate prepared by electrospinning has a porous structure, and the high porosity is conducive to improving the flexibility of the substrate and increasing the air permeability of the substrate. It can effectively avoid skin allergies and inflammatory reactions caused by sweat accumulation when the flexible temperature sensor is applied to the real-time continuous tracking of the skin surface temperature, making it possible for the sensor to achieve long-term stable temperature monitoring.

[0059] In some possible implementations, the hydrophilic treatment method includes oxygen plasma treatment. By subjecting the surface of the porous flexible layer made by electrospinning to oxygen plasma treatment, the oxygen-containing functional groups on the surface are increased, and the hydrophilicity of the surface is increased, which is beneficial to improving the bonding effect between the subsequent temperature sensing layer and the flexible substrate.

[0060] In some possible implementations, the high molecular polymer includes at least one of styrene-butadiene-styrene triblock polymer, polyurethane, polyimide, and styrene-butadiene block copolymer; these high molecular polymers used in the embodiments of the present application as materials for preparing flexible substrates not only have good flexibility, but also have chemical stability, safety, and non-cytotoxicity. In some specific embodiments, the high molecular polymer uses styrene-butadiene-styrene triblock polymer.

[0061] In some possible implementations, the porosity of the flexible substrate is 60-90%; specifically, the porosity of the flexible substrate can be 60-70%, 70-80%, 80-90%, etc. A highly porosity flexible substrate is beneficial for improving the flexibility of the substrate and increasing the air permeability of the substrate.

[0062] In some possible implementations, the thickness of the flexible substrate is 80-200 μm; specifically, the thickness of the flexible substrate may be 80-100 μm, 100-120 μm, 120-150 μm, 150-180 μm, 180-200 μm, etc. The flexible substrate of this thickness ensures the flexibility of the sensor and can provide sufficient support for the temperature sensing layer, the electrode layer, etc.

[0063] In the above step S20, an ink containing a transition metal oxide and a conductive polymer is prepared. In some possible implementations, after the transition metal oxide and the conductive polymer solution are mixed, ultrasonic dispersion treatment is performed to obtain a uniformly mixed ink.

[0064] In some possible implementations, the transition metal oxide includes at least one of vanadium dioxide, nickel oxide, and tungsten oxide; these transition metal oxides have excellent stability and high temperature sensitivity. In some specific embodiments, the transition metal oxide uses vanadium dioxide, which has a high temperature coefficient of resistance and can show high temperature sensitivity in the human skin temperature range.

[0065] In some possible implementations, the conductive polymer includes at least one of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid)), polypyrrole, and S-PEDOT (S-poly(3,4-ethylenedioxythiophene monomer)). These conductive polymers can be used as conductive agents to assist the transmission of electrons between transition metal oxides, and can also be used as binders to connect transition metal oxide particles into one body under the action of chemical bonds and intermolecular forces, forming a temperature sensing layer on the surface of the flexible substrate. In some specific embodiments, the conductive polymer uses PEDOT:PSS, which is easily soluble in water and is configured into a water-based ink, which is environmentally friendly, safe and non-toxic.

[0066] In some possible implementations, in the ink, the mass ratio of transition metal oxide and conductive polymer is 100:(2.5~7.5). In the embodiment of the present application, as the mass of conductive polymer in the ink increases, the resistance of the device decreases, but the sensitivity to temperature measurement first increases and then decreases. The transition metal oxide and conductive polymer in this ratio ensure both the detection sensitivity of the temperature sensing layer to temperature and the transmission efficiency of electrons in the sensing layer. Within this ratio range, by adjusting the ratio of transition metal oxide and conductive polymer in the ink, the sensitivity of the flexible temperature sensor can be flexibly adjusted, which is conducive to the development of a wider range of applications and potential. In some specific embodiments, in the ink, the mass ratio of transition metal oxide and conductive polymer can be 100:(2.5~3), 100:(3~4), 100:(4~5), 100:(5~6), 100:(6~7.5), etc.

[0067] In some possible implementations, the ratio of solute to solvent in the ink is 50 mg: (3-8) ml; the ratio of solute to solvent makes the ink have a suitable viscosity, which is conducive to the subsequent deposition and preparation of the temperature sensing layer by spraying and other processes. In some specific embodiments, the ratio of solute to solvent in the ink can be 50 mg: (3-4) ml, 50 mg: (4-5) ml, 50 mg: (5-6) ml, 50 mg: (6-7) ml, 50 mg: (7-8) ml, etc.

[0068] In some possible implementations, the solvent in the ink includes at least one of water, ethanol, and acetone. These solvents have a high dissolution and dispersion effect on transition metal oxides and conductive polymers, and have a low temperature, and can be volatilized and removed under low temperature conditions to form a temperature sensing layer on the surface of the flexible substrate.

[0069] In some possible implementations, the step of depositing ink on the surface of a flexible substrate to form a temperature sensing layer includes: spraying the ink on the surface of the flexible substrate, drying at a temperature of 25 to 100°C, and forming a temperature sensing layer on the surface of the flexible substrate. In the embodiment of the present application, the water in the ink is fully volatilized under relatively low temperature conditions to obtain a temperature sensing layer containing a transition metal oxide, which not only saves energy and is environmentally friendly, but also avoids the limitation of high temperature conditions on the selection of flexible substrate materials, thereby broadening the selection range of substrate materials. In some specific embodiments, the drying temperature can be 25 to 40°C, 40 to 50°C, 50 to 60°C, 60 to 70°C, 70 to 80°C, 80 to 90°C, 90 to 100°C, etc.

[0070] In some possible implementations, the total loading of the transition metal oxide and the conductive polymer in the ink on the surface of the flexible substrate is 4 to 6 mg / cm 2This loading ensures the mechanical stability and electrical performance stability of the formed temperature sensor. In some specific embodiments, the total loading of the transition metal oxide and the conductive polymer in the ink on the surface of the flexible substrate can be 4 to 5 mg / cm 2 , 5~6mg / cm 2 wait.

[0071] In some possible implementations, the thickness of the temperature sensing layer is 1 to 10 μm; the increase in the thickness of the temperature sensing layer in the embodiment of the present application is likely to cause cracks in the sensing layer, affecting the mechanical stability and electrical performance stability of the device during use. The temperature sensing layer with a thickness of 1 to 10 μm ensures both the detection sensitivity of the sensing layer and the stability of the sensing layer. In some specific embodiments, the thickness of the temperature sensing layer can be 1 to 2 μm, 2 to 3 μm, 3 to 4 μm, 4 to 5 μm, 5 to 6 μm, 6 to 7 μm, 7 to 8 μm, 8 to 9 μm, 9 to 10 μm, etc.

[0072] In the above step S30, an electrode is prepared on the surface of the temperature sensing layer; in some possible implementations, the step of preparing the electrode includes: depositing an electrode material on the surface of the temperature sensing layer by at least one method of electron beam evaporation, screen printing or inkjet printing to form an electrode, and the electrode is used to form an electrical connection with a power source. In some specific embodiments, a copper wire is connected to the electrode with silver glue to connect to the power source.

[0073] In some possible implementations, the electrode material includes metal materials such as silver, gold, copper, platinum, palladium, iridium, or at least one organic conductive material selected from carbon nanotubes, graphene, and PEDOT:PSS.

[0074] In some possible implementations, the thickness of the electrode is 150-250 nm, specifically, the thickness may be 150-180 nm, 180-200 nm, 200-230 nm, 230-250 nm, etc. Electrodes of this thickness ensure a conductive effect.

[0075] In some specific embodiments, a silver electrode is prepared on the electrode temperature sensing layer by electron beam evaporation, and a copper wire is connected to the silver electrode by silver glue.

[0076] In the above step S40, preparing the encapsulation layer, in some possible implementations, the step of preparing the encapsulation layer includes: forming the encapsulation layer from an insulating polymer material by chemical vapor deposition or spin coating. The encapsulation layer encapsulates the device including the flexible substrate, the temperature sensing layer and the electrode.

[0077] In some possible implementations, the insulating polymer material includes at least one of parylene and polydimethylsiloxane. In some specific embodiments, parylene is deposited by chemical vapor deposition, or PDMS is spin-coated on the temperature sensing layer by spin coating to prepare the encapsulation layer.

[0078] In some possible implementations, the thickness of the encapsulation layer is 1 to 1.5 μm. Specifically, the thickness of the encapsulation layer can be 1 to 1.1 μm, 1.1 to 1.2 μm, 1.2 to 1.3 μm, 1.3 to 1.4 μm, 1.4 to 1.5 μm, etc. The encapsulation layer of this thickness has a good encapsulation effect and will not affect the flexibility of the device.

[0079] In a second aspect, an embodiment of the present application provides a flexible temperature sensor, which is manufactured using the above method.

[0080] The flexible temperature sensor provided in the second aspect of the embodiment of the present application is manufactured by the above method, as shown in the attached Figure 2 As shown, it includes a flexible substrate, a temperature sensing layer attached to the surface of the flexible substrate, an electrode attached to the surface of the temperature sensing layer, and a packaging layer that encapsulates the flexible substrate, the temperature sensing layer and the electrode. The flexible temperature sensor has high flexibility and detection sensitivity, and the flexible substrate material has a wide range of choices, and has a larger application range and potential.

[0081] In some possible implementations, the temperature sensing layer includes a transition metal oxide and a conductive polymer. Further, the mass ratio of the transition metal oxide to the conductive polymer is 100:(2.5-7.5).

[0082] In some possible implementations, the thickness of the flexible substrate is 80-200 μm.

[0083] In some possible implementations, the porosity of the flexible substrate is 60-90%.

[0084] In some possible implementations, the temperature sensing layer has a thickness of 1-10 μm.

[0085] In some possible implementations, the thickness of the electrode is 150-250 nm.

[0086] In some possible implementations, the thickness of the encapsulation layer is 1-1.5 μm.

[0087] The beneficial effects of the above embodiments of the present application have been discussed in the previous text and will not be repeated here.

[0088] In some possible implementations, the sensitivity of the flexible temperature sensor is -1%°C -1 ~-3%℃-1 By adjusting the ink composition ratio, a sensitivity of -1%℃ can be obtained. -1 ~-3%℃ -1 Flexible temperature sensor. The sensitivity can be calculated by the negative temperature coefficient of resistance (TCR), the calculation formula is TCR = (R t -R0) / ((T t -T0)·R t ), where R t and R0 are the temperatures at T t ℃ and T0℃(25℃), T t And T0 refers to K degrees, which is the Kelvin temperature.

[0089] In a third aspect, an embodiment of the present application provides a flexible device, which includes the flexible temperature sensor prepared by the above method or the above flexible temperature sensor.

[0090] The flexible device provided in the third aspect of the embodiment of the present application, because it includes the above-mentioned flexible temperature sensor, can continuously track temperature changes in real time, and has high sensitivity and good flexibility. It is directly attached to the skin surface in a conformal manner, and can continuously track the skin surface temperature in real time, thereby improving the quality of life.

[0091] In order to enable those skilled in the art to clearly understand the implementation details and operations of the present application, as well as to demonstrate the significant improvement in performance of the flexible temperature sensor and its preparation method and application in the embodiment of the present application, the above technical solution is illustrated by multiple embodiments below.

[0092] Example 1

[0093] A flexible temperature sensor, the preparation diagram of which is shown in the attached figure Figure 3 As shown, the steps include:

[0094] 1. Preparation of SBS fabric flexible substrate by electrospinning: SBS was dissolved in a mixed solvent (THF:DMF=3:1) by magnetic stirring to form a transparent and viscous 14wt.% SBS solution at 65°C. Spinning was performed at a speed of 1ml / h under 18 kV DC, and the working distance between the collection roller and the spinning needle was 15cm. Finally, SBS fabric with a thickness of about 100 microns was collected on the collection roller. Afterwards, the electrospun fabric was treated with oxygen plasma for 30 minutes to obtain a hydrophilic surface and a soft SBS fabric substrate.

[0095] 2. Fabrication of VO2 / PEDOT:PSS temperature sensing layer: VO2 powder and PEDOT:PSS aqueous solution were dispersed in deionized water to form ink. The weight ratio of VO2 to PEDOT:PSS was 100:5. The aqueous dispersion of VO2 and PEDOT:PSS was first ultrasonically treated for 20 minutes with an intelligent ultrasonic processor, and then the mixed ink was sprayed on the surface of the hydrophilic SBS fabric. The SBS fabric was heated to 70°C while spraying. The area mass loading of VO2 and PEDOT:PSS was 5 mg cm -2 and 0.25mgcm -2 , to obtain a temperature sensing layer.

[0096] 3. Prepare electrodes: Prepare a template with a designed pattern as a mask, and use electron beam evaporation technology to deposit silver electrodes on the temperature sensing layer in a coplanar structure. The thickness of the electrode is 200nm and the gap is 200μm. After removing the template mask, a composite fabric with a designed circuit deposited is obtained. In order to evaluate the sensing device, copper wires are glued to the silver electrodes using silver glue.

[0097] 4. Packaging: A layer of parylene with a thickness of 1.2 μm is deposited by chemical vapor deposition to finally complete the packaging of the temperature sensor and obtain a flexible temperature sensor.

[0098] Example 2

[0099] A flexible temperature sensor, the preparation of which is different from that of Example 1 in that: in step 2, the preparation of the VO2 / PEDOT:PSS temperature sensing layer: VO2 powder and PEDOT:PSS aqueous solution are dispersed in deionized water to form ink. The weight ratio of VO2 to PEDOT:PSS is 100:2.5. First, the aqueous dispersion of VO2 and PEDOT:PSS is ultrasonically treated for 20 minutes with an intelligent ultrasonic processor, and then the mixed ink is sprayed on the surface of a hydrophilic SBS fabric, and the SBS fabric is heated to 70°C while spraying. The area mass loading of VO2 and PEDOT:PSS is 5 mg cm -2 and 0.125 mg cm -2 , to prepare a VO2 / PEDOT:PSS temperature sensing layer with a weight ratio of 100:2.5.

[0100] Example 3

[0101] A flexible temperature sensor, the preparation of which is different from that of Example 1 in that: in step 2, the preparation of the VO2 / PEDOT:PSS temperature sensing layer: VO2 powder and PEDOT:PSS aqueous solution are dispersed in deionized water to form ink. The weight ratio of VO2 to PEDOT:PSS is 100:7.5. First, the aqueous dispersion of VO2 and PEDOT:PSS is ultrasonically treated for 20 minutes with an intelligent ultrasonic processor, and then the mixed ink is sprayed on the surface of a hydrophilic SBS fabric, and the SBS fabric is heated to 70°C while spraying. The area mass loading of VO2 and PEDOT:PSS is 5 mg cm -2 and 0.375 mg cm -2 , to prepare a VO2 / PEDOT:PSS temperature sensing layer with a weight ratio of 100:7.5.

[0102] Comparative Example 1

[0103] A flexible temperature sensor, the preparation of which is different from that of Example 1 in that: in step 2, the VO2 temperature sensing layer is prepared by dispersing VO2 powder in deionized water to form ink. First, the VO2 aqueous dispersion is ultrasonically treated for 20 minutes with an intelligent ultrasonic processor, and then the mixed ink is sprayed on the surface of a hydrophilic SBS fabric, and the SBS fabric is heated to 70°C while spraying. The area mass loading of VO2 is 5 mg cm -2 , to produce a temperature sensing layer containing only VO2.

[0104] Further, in order to verify the progress of the embodiments of the present application, the flexible temperature sensors prepared in the above embodiments and comparative examples were subjected to the following performance tests:

[0105] 1. A temperature control system was used to heat and cool the flexible temperature sensors prepared in the embodiment and the comparative example, so as to perform temperature sensing measurements on the flexible temperature sensors prepared in the embodiment and the comparative example respectively. The test results are shown in the attached figure. Figure 4 and 5 As shown in the attached Figure 4 The test results of the resistance-temperature curve of the flexible temperature sensor prepared in Example 1 show that the flexible temperature sensor has excellent sensitivity. Figure 5 The test results show that the flexible temperature sensor prepared in Example 1 has a faster response time and recovery time.

[0106] 2. The electrical characteristics of the flexible temperature sensors prepared in the embodiment and the comparative example were analyzed using a CHI660e electrochemical workstation in an environment with a relative humidity of 65%. The test results are shown in the attached Figure 6 As shown in the attached Figure 6The test results show that the resistance of the flexible temperature sensor prepared in Example 1 is relatively stable as the temperature changes.

[0107] 3. The bending stability test of the flexible temperature sensor prepared in Example 1 was carried out. The test results are shown in the attached figure. Figure 7 As shown in the attached Figure 7 The test results show that the flexible temperature sensor prepared in Example 1 has excellent bending stability and exhibits good flexibility.

[0108] 4. From the comparison of Examples 1 to 3, it can be seen that by changing the ratio of transition metal oxide and conductive polymer as a variable, as the relative content of PEDOT:PSS increases, the sensor resistance gradually decreases, and the absolute value of sensitivity first increases and then decreases, showing excellent temperature measurement capabilities within a certain range. Figure 8 shown.

[0109] 5. The resistance of the flexible temperature sensor prepared in Comparative Example 1 is very large due to the lack of conductive polymer, which exceeds the test range of the CHI660e electrochemical workstation and makes it impossible to record the resistance. This is because: on the one hand, there is no conductive polymer as a pathway for electron transmission between discrete transition metal oxide particles, and the sensor as a whole has a large contact resistance; on the other hand, there is only van der Waals force between the rigid transition metal oxide particles, and the lack of adhesive makes it easy to produce large cracks, further increasing the sensor resistance.

[0110] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a flexible temperature sensor, characterized in that: The following steps are involved: preparing a flexible substrate; Preparing an ink comprising a transition metal oxide and a conductive polymer, and depositing the ink on the surface of the flexible substrate to form a temperature sensing layer; Prepare electrodes on the surface of the temperature sensing layer; A packaging layer is prepared, wherein the packaging layer forms a package for the device including the flexible substrate, the temperature sensing layer and the electrode.

2. The method for preparing the flexible temperature sensor according to claim 1, characterized in that: The transition metal oxide includes at least one of vanadium dioxide, nickel oxide, and tungsten oxide; And / or, the conductive polymer includes at least one of PEDOT:PSS, polypyrrole, and S-PEDOT.

3. The method for preparing the flexible temperature sensor according to claim 2, characterized in that: In the ink, the mass ratio of the transition metal oxide to the conductive polymer is 100:(2.5-7.5); And / or, the ratio of solute to solvent in the ink is 50 mg: (3-8) ml; And / or, the solvent in the ink includes at least one of water, ethanol and acetone.

4. The method for preparing the flexible temperature sensor according to any one of claims 1 to 3, characterized in that: The thickness of the flexible substrate is 80 to 200 μm; and / or, the porosity of the flexible substrate is 60-90%; And / or, the thickness of the temperature sensing layer is 1 to 10 μm; And / or, the thickness of the electrode is 150 to 250 nm; And / or, the encapsulation layer has a thickness of 1 to 1.5 μm.

5. The method for preparing the flexible temperature sensor according to claim 4, characterized in that: The step of preparing the temperature sensing layer comprises: spraying the ink on the surface of the flexible substrate, and performing low-temperature drying at a temperature of 25 to 100° C. to form the temperature sensing layer on the surface of the flexible substrate; And / or, the preparation step of the flexible substrate comprises: using a high molecular polymer as a raw material, preparing a porous flexible layer by electrospinning, and performing a hydrophilic treatment on the surface of the porous flexible layer to obtain the flexible substrate; And / or, the step of preparing the electrode comprises: depositing electrode material on the surface of the temperature sensing layer by at least one method of electron beam evaporation, screen printing or inkjet printing to form the electrode, wherein the electrode is used to form an electrical connection with a power source; And / or, the step of preparing the encapsulation layer includes: forming the encapsulation layer from an insulating polymer material by chemical vapor deposition or spin coating.

6. The method for preparing the flexible temperature sensor according to claim 5, characterized in that: The total loading amount of the transition metal oxide and the conductive polymer in the ink on the surface of the flexible substrate is 4 to 6 mg / cm 2 ; And / or, the hydrophilic treatment method comprises oxygen plasma treatment.

7. The method for preparing the flexible temperature sensor according to claim 5 or 6, characterized in that: The high molecular polymer includes at least one of styrene-butadiene-styrene triblock polymer, polyurethane, polyimide, and styrene butadiene block copolymer; And / or, the electrode material includes at least one of silver, gold, copper, platinum, palladium, iridium, carbon nanotubes, graphene, and PEDOT:PSS; And / or, the insulating polymer material includes at least one of polyparaxylene and polydimethylsiloxane.

8. A flexible temperature sensor, characterized in that: The flexible temperature sensor is manufactured by the method according to any one of claims 1 to 7.

9. The flexible temperature sensor according to claim 8, characterized in that: The sensitivity of the flexible temperature sensor is -1 to -3% °C. -1 .

10. A flexible device, characterized in that: The flexible device comprises a flexible temperature sensor prepared by the method according to any one of claims 1 to 7 or a flexible temperature sensor according to any one of claims 8 to 9.

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