High-sensitivity pressure-temperature dual-mode sensor and preparation method thereof

Abstract

This invention relates to the field of sensor technology, specifically to a highly sensitive pressure-temperature dual-mode sensor and its preparation method, comprising: reacting carbon nanotubes with an acid-treated silane coupling agent KH550 to obtain aminated carbon nanotubes; reacting a phosphorus source with an aqueous solution of graphene oxide via hydrothermal reaction to obtain phosphorus-doped reduced graphene oxide; synthesizing an Au-Ag heterojunction nano-dispersion using an Au nanoseed method; mixing the three components and sonicating to obtain a mixed dispersion; modifying a PDMS substrate with KH560 and polyethylene glycol diamine to obtain a modified PDMS substrate; coating the mixed dispersion onto the modified substrate to form a sensitive layer, and fabricating electrodes to obtain the sensor. Aminated carbon nanotubes and phosphorus-doped reduced graphene oxide construct a three-dimensional conductive network to achieve highly sensitive pressure detection; phosphorus-doped reduced graphene oxide and the Au-Ag heterojunction form a Schottky barrier to achieve stable temperature sensing; and the modified PDMS strongly bonds with the sensitive layer to improve mechanical durability.

Description

Technical Field

[0001] This application relates to the field of sensor technology, specifically to a highly sensitive pressure-temperature dual-mode sensor and its fabrication method. Background Technology

[0002] With the rapid development of flexible electronics, health monitoring, and artificial intelligence, there is an urgent need for flexible sensors that can simulate the functions of human skin and simultaneously detect multiple physical signals (such as pressure, temperature, and humidity). Among them, dual-mode sensors that can simultaneously and with high sensitivity detect pressure and temperature show great application potential in fields such as intelligent robots, wearable health monitoring, and human-computer interaction interfaces.

[0003] Significant progress has been made in the research of single flexible pressure or temperature sensors. For example, sensors based on nanomaterials such as carbon nanotubes, graphene, and metal nanowires have been widely reported. However, efficiently integrating pressure and temperature sensing functions into the same device while ensuring that the two signals do not interfere with each other, and achieving high sensitivity and fast response performance, still faces significant challenges. The resistance of most materials changes with both pressure and temperature, leading to severe crosstalk between the pressure and temperature signals, making it difficult to achieve accurate decoupling and independent measurement of the two parameters. Many sensor structures, in trying to achieve both functions, often sacrifice the sensitivity of one, resulting in poor continuity of the conductive network and limited sensitivity of the piezoresistive path, making it difficult to meet the requirements for detecting weak signals. At the same time, some solutions use complex multilayer stacked structures or rigid components, reducing the overall flexibility, comfort, and durability of the device. The sensitive functional layer is mostly physically attached to the flexible substrate, with weak interfacial bonding, making it prone to detachment under repeated deformation, leading to sensor performance degradation.

[0004] Therefore, developing a pressure-temperature dual-mode flexible sensor with high sensitivity and good stability is of great significance for promoting the development of electronic skin technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a highly sensitive pressure-temperature dual-mode sensor, which achieves high sensitivity and rapid response detection of pressure and temperature signals by compositing aminated carbon nanotubes, phosphorus-doped reduced graphene oxide, and Au-Ag heterojunction nanoparticles on an interface-modified PDMS (polydimethylsiloxane) substrate.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a method for fabricating a highly sensitive pressure-temperature dual-mode sensor, comprising the following:

[0008] Step 1. After acid treatment, carbon nanotubes are reacted with silane coupling agent KH550 to obtain aminated carbon nanotubes;

[0009] Step 2. After mixing the phosphorus source with the aqueous solution of graphene oxide, a hydrothermal reaction is carried out to obtain phosphorus-doped reduced graphene oxide;

[0010] Step 3. React chloroauric acid solution with the first reducing agent to obtain Au nanoseeds; add AgNO3 solution and the second reducing agent to the system containing Au nanoseeds to react and obtain Au-Ag heterojunction nanodispersion;

[0011] Step 4. Mix the aminated carbon nanotubes, the phosphorus-doped reduced graphene oxide, and the Au-Ag heterojunction nanodispersion, and then treat with ultrasound to obtain a mixed dispersion.

[0012] Step 5. The pretreated PDMS substrate is first immersed in KH560 ethanol solution, then taken out, cleaned and dried, and then immersed in polyethylene glycol diamine solution for crosslinking reaction to obtain modified PDMS substrate;

[0013] Step 6. Coat the mixed dispersion onto the modified PDMS substrate, dry it to obtain a sensitive layer, and fabricate electrodes at both ends of the sensitive layer to obtain a highly sensitive pressure-temperature dual-mode flexible sensor.

[0014] In this application, firstly, a three-dimensional interconnected conductive network is constructed by π-π stacking and hydrogen bonding between one-dimensional aminated carbon nanotubes and two-dimensional phosphorus-doped reduced graphene oxide. The carbon nanotubes are acid-treated to introduce carboxyl groups (-COOH), and then reacted with KH550 silane coupling agent to graft amino groups (-NH2) onto their surface. Amination not only improves the dispersibility of the carbon nanotubes but also strengthens the network interweaving through hydrogen bonding between the amino groups and the oxygen-containing functional groups of the phosphorus-doped reduced graphene oxide. Under external pressure, the three-dimensional network undergoes elastic deformation, leading to an increase in contact points between the nanomaterials, thereby reducing contact resistance. Furthermore, the quantum tunneling distance between the aminated carbon nanotubes and the phosphorus-doped reduced graphene oxide is shortened, further reducing tunneling resistance. This allows the sensor to generate a significant resistance change under micro-pressure, achieving highly sensitive pressure detection.

[0015] Secondly, during the phosphorus doping process of phosphorus-doped reduced graphene oxide, phosphorus atoms replace carbon atoms or form CP bonds with oxygen-containing functional groups, acting as an n-type dopant to provide electrons to the graphene π system, thereby increasing the carrier concentration and conductivity. Simultaneously, the work function of phosphorus-doped reduced graphene oxide differs from the Fermi level of Au-Ag heterojunction nanoparticles, thus forming a Schottky barrier. With temperature changes, the system follows the hot electron emission theory, and the height of the Schottky barrier decreases with increasing temperature. Simultaneously, the intrinsic carrier thermal excitation of phosphorus-doped reduced graphene oxide is enhanced, collectively leading to a monotonic change in resistance with temperature. Furthermore, the interfacial electronic coupling effect of the Au-Ag heterojunction further amplifies the temperature response signal of the resistance. Uniformly dispersed in the three-dimensional network, it acts as a thermosensitive active site, ensuring spatial uniformity of temperature detection and achieving stable temperature sensing over a wide range.

[0016] Finally, KH560 reacts with the hydroxyl groups on the PDMS surface to form siloxane bonds, introducing epoxy groups. Subsequently, the amino groups of polyethylene glycol diamine undergo ring-opening reactions with the epoxy groups, forming an amino-rich terminal layer on the PDMS surface. The aminated carbon nanotubes and phosphorus-doped reduced graphene oxide surfaces in the sensitive layer contain functional groups such as carboxyl groups, which bind to the amino groups on the modified PDMS surface through amide bonds and hydrogen bonds, forming strong interfacial adhesion. This ensures that the sensitive layer is not easily detached under flexible deformation, improving the mechanical durability and signal stability of the sensor.

[0017] Preferably, in step 1, the acid used for acid treatment is nitric acid or sulfuric acid; the concentration of the acid is 68wt.%-98wt.%; and the mass ratio of the carbon nanotubes, acid and silane coupling agent KH550 is 1:(50-200):(1-5).

[0018] Preferably, in step 1, the acid treatment reaction temperature is 60-100℃ and the reaction time is 2-6h; the reaction temperature with silane coupling agent KH550 is 70-90℃ and the reaction time is 2-4h.

[0019] Preferably, in step 2, the phosphorus source includes any one of phosphoric acid, phosphorous acid, and red phosphorus; the concentration of the graphene oxide solution is 0.1 wt.%-0.2 wt.%; the mass ratio of the phosphorus source to the graphene oxide solution is 1:(10-50); the temperature of the hydrothermal reaction is 150-200℃, and the reaction time is 6-12 h.

[0020] Preferably, in step 3, the first reducing agent includes any one of sodium citrate, ascorbic acid, and sodium borohydride; the second reducing agent includes any one of sodium citrate, ascorbic acid, and sodium borohydride; the mass ratio of the first reducing agent to the chloroauric acid solution is (1-3):1; the mass ratio of the second reducing agent to the AgNO3 solution is (1-2):1; the mass ratio of the AgNO3 solution to the chloroauric acid solution is (1-5):1; the concentration of the chloroauric acid solution is 0.1wt.%-0.2wt.%; and the concentration of the AgNO3 solution is 0.1wt.%-0.3wt.%.

[0021] Preferably, in step 3, the preparation temperature of the Au nanoseeds is 50-80℃ and the reaction time is 10-30 min; the preparation temperature of the Au-Ag heterojunction nanoparticles is 60-90℃ and the reaction time is 20-60 min.

[0022] Preferably, in step 4, the mass ratio of the aminated carbon nanotubes, phosphorus-doped reduced graphene oxide, and Au-Ag heterojunction nanoparticles is 1:(1-3):(0.5-2); the ultrasonic treatment temperature is 20-40℃ and the time is 30-50min.

[0023] Preferably, the pretreatment is performed using low-temperature oxygen plasma treatment or ultraviolet ozone treatment; the concentration of the KH560 ethanol solution is 1 wt.%-5 wt.%; the concentration of the polyethylene glycol diamine solution is 5 wt.%-15 wt.%; the immersion temperature in the KH560 ethanol solution is 15-35℃ and the reaction time is 30-60 min; the crosslinking reaction temperature is 60-100℃ and the time is 1-4 h.

[0024] Preferably, in step 6, the electrode is made of any one of silver, gold, or copper, and the electrode is prepared by screen printing or sputtering.

[0025] Secondly, this application provides a highly sensitive pressure-temperature dual-mode sensor, which is prepared using the aforementioned preparation method.

[0026] Compared with the prior art, the beneficial effects of this application are as follows:

[0027] This application provides a highly sensitive pressure-temperature dual-mode sensor and its fabrication method. First, one-dimensional aminated carbon nanotubes and two-dimensional phosphorus-doped reduced graphene oxide are stacked on π-π and bonded to form a three-dimensional interconnected conductive network. The carbon nanotubes are acid-treated to introduce carboxyl groups (-COOH), and then reacted with KH550 silane coupling agent to graft amino groups (-NH2) onto their surface. Amination not only improves the dispersibility of the carbon nanotubes but also strengthens the network interweaving through hydrogen bonding between the amino groups and the oxygen-containing functional groups of the phosphorus-doped reduced graphene oxide. Under external pressure, the three-dimensional network undergoes elastic deformation, increasing the contact points between the nanomaterials and reducing the contact resistance. Furthermore, the quantum tunneling distance between the aminated carbon nanotubes and the phosphorus-doped reduced graphene oxide is shortened, further reducing the tunneling resistance. This allows the sensor to produce a significant resistance change under micro-pressure, achieving highly sensitive pressure detection.

[0028] Secondly, during the phosphorus doping process of phosphorus-doped reduced graphene oxide, phosphorus atoms replace carbon atoms or form CP bonds with oxygen-containing functional groups, acting as an n-type dopant to provide electrons to the graphene π system, thereby increasing the carrier concentration and conductivity. Simultaneously, the work function of phosphorus-doped reduced graphene oxide differs from the Fermi level of Au-Ag heterojunction nanoparticles, thus forming a Schottky barrier. With temperature changes, the system follows the hot electron emission theory, and the height of the Schottky barrier decreases with increasing temperature. Simultaneously, the intrinsic carrier thermal excitation of phosphorus-doped reduced graphene oxide is enhanced, collectively leading to a monotonic change in resistance with temperature. Furthermore, the interfacial electronic coupling effect of the Au-Ag heterojunction further amplifies the temperature response signal of the resistance. Uniformly dispersed in the three-dimensional network, it acts as a thermosensitive active site, ensuring spatial uniformity of temperature detection and achieving stable temperature sensing over a wide range.

[0029] Finally, modified PDMS reacts with hydroxyl groups on the PDMS surface via KH560 to form siloxane bonds, introducing epoxy groups. Subsequently, the amino groups of polyethylene glycol diamine undergo ring-opening reactions with the epoxy groups, forming an amino-rich terminal layer on the PDMS surface. The aminated carbon nanotubes and phosphorus-doped reduced graphene oxide in the sensitive layer contain functional groups such as carboxyl groups, which bond with the amino groups on the modified PDMS surface through amide bonds and hydrogen bonds, forming strong interfacial adhesion. This ensures that the sensitive layer is not easily detached under flexible deformation, improving the mechanical durability and signal stability of the sensor. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the fabrication process of a high-sensitivity pressure-temperature dual-mode sensor according to the present invention;

[0031] Figure 2 This is a SEM image of the sensitive layer of a high-sensitivity pressure-temperature dual-mode sensor according to Embodiment 1 of the present invention. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0033] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0034] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] The following will describe in detail, with reference to different embodiments, a highly sensitive pressure-temperature dual-mode sensor and its fabrication method provided in this application.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment provides a method for fabricating a highly sensitive pressure-temperature dual-mode sensor, including the following steps:

[0039] Step 1. Take carbon nanotubes and sulfuric acid with a concentration of 68 wt.%, and react at 60°C for 2 h; after acid treatment, wash until pH 7, add silane coupling agent KH550, and react at 70°C for 2 h. After centrifugation and drying, aminated carbon nanotubes are obtained, wherein the mass ratio of carbon nanotubes, sulfuric acid and silane coupling agent KH550 is 1:50:1.

[0040] Step 2. After mixing phosphoric acid with a 0.1 wt.% aqueous solution of graphene oxide, the mixture is transferred to a hydrothermal reactor with a mass ratio of phosphoric acid to graphene oxide solution of 1:10. The hydrothermal reaction is carried out at 150°C for 6 hours. After the reaction is completed, the mixture is washed and dried to obtain phosphorus-doped reduced graphene oxide.

[0041] Step 3. Take a 0.1 wt.% chloroauric acid solution and sodium borohydride and react them at 50℃ for 10 min, wherein the mass ratio of sodium borohydride to chloroauric acid solution is 1:1, to obtain Au nano-seed dispersion; add a 0.1 wt.% AgNO3 solution and ascorbic acid to the above Au nano-seed dispersion, wherein the mass ratio of AgNO3 solution to chloroauric acid solution is 1:1, and the mass ratio of the second reducing agent to AgNO3 solution is 1:1, and react at 60℃ for 20 min to obtain Au-Ag heterojunction nano-dispersion.

[0042] Step 4. Mix the aminated carbon nanotubes, phosphorus-doped reduced graphene oxide and Au-Ag heterojunction nanoparticle dispersion in a mass ratio of 1:1:0.5 and sonicate at 20°C for 30 min to obtain a mixed dispersion.

[0043] Step 5. The PDMS substrate is pretreated by low-temperature oxygen plasma treatment. The pretreated PDMS substrate is immersed in a 1 wt.% KH560 ethanol solution and reacted at 15°C for 30 min. After removal, it is washed and dried. Then it is immersed in a 5 wt.% polyethylene glycol diamine solution and crosslinked at 60°C for 1 h. After drying, the modified PDMS substrate is obtained.

[0044] Step 6. Coat the mixed dispersion obtained in step 4 onto the modified PDMS substrate, and dry it to form a sensitive layer; prepare silver electrodes at both ends of the sensitive layer using a screen printing method to obtain a high-sensitivity pressure-temperature dual-mode flexible sensor.

[0045] Example 2

[0046] like Figure 1 As shown, this embodiment provides a method for fabricating a highly sensitive pressure-temperature dual-mode sensor, including the following steps:

[0047] Step 1. Take carbon nanotubes and 72wt.% concentrated nitric acid and react at 80℃ for 4h; after acid treatment, wash until pH is 7, add silane coupling agent KH550, react at 80℃ for 3h, and after centrifugation and drying, obtain aminated carbon nanotubes, wherein the mass ratio of carbon nanotubes, sulfuric acid and silane coupling agent KH550 is 1:100:3.

[0048] Step 2. After mixing phosphorous acid with a 0.15 wt.% aqueous solution of graphene oxide, the mixture is transferred to a hydrothermal reactor with a mass ratio of phosphorous acid to graphene oxide solution of 1:20. The hydrothermal reaction is carried out at 180°C for 10 hours. After the reaction is completed, the mixture is washed and dried to obtain phosphorus-doped reduced graphene oxide.

[0049] Step 3. Take ascorbic acid and chloroauric acid solution with a mass ratio of 2:1 and react them at 60℃ for 20 min to obtain Au nano-seed dispersion; add AgNO3 solution with a concentration of 0.2wt.% and sodium citrate to the above Au nano-seed dispersion, wherein the mass ratio of AgNO3 solution to chloroauric acid solution is 3:1 and the mass ratio of the second reducing agent to AgNO3 solution is 2:1, and react at 70℃ for 30 min to obtain Au-Ag heterojunction nano-dispersion.

[0050] Step 4. Mix the aminated carbon nanotubes, phosphorus-doped reduced graphene oxide and Au-Ag heterojunction nanoparticle dispersion in a mass ratio of 1:2:1, and sonicate at 30°C for 40 min to obtain the mixed dispersion.

[0051] Step 5. Pre-treat the PDMS substrate using ultraviolet ozone treatment; immerse the pre-treated PDMS substrate in a 2% KH560 ethanol solution and react at 20℃ for 40 min, then remove, wash and dry; then immerse it in a 10% polyethylene glycol diamine solution and perform a crosslinking reaction at 80℃ for 2 h, and dry to obtain the modified PDMS substrate.

[0052] Step 6. Coat the mixed dispersion obtained in step 4 onto the modified PDMS substrate, and dry it to form a sensitive layer; fabricate gold electrodes at both ends of the sensitive layer using a screen printing method to obtain a highly sensitive pressure-temperature dual-mode flexible sensor.

[0053] Example 3

[0054] like Figure 1 As shown, this embodiment provides a method for fabricating a highly sensitive pressure-temperature dual-mode sensor, including the following steps:

[0055] Step 1. Take carbon nanotubes and sulfuric acid with a concentration of 98 wt.%, and react them at 100℃ for 6 h; after acid treatment, wash until pH=7, add silane coupling agent KH550, and react at 90℃ for 4 h. After separation and drying, aminated carbon nanotubes are obtained, wherein the mass ratio of carbon nanotubes, sulfuric acid and silane coupling agent KH550 is 1:200:5.

[0056] Step 2. After mixing red phosphorus with a 0.2 wt.% aqueous solution of graphene oxide, the mixture is transferred to a hydrothermal reactor with a mass ratio of red phosphorus to graphene oxide solution of 1:50. The hydrothermal reaction is carried out at 200℃ for 12 hours. After the reaction is completed, the mixture is washed and dried to obtain phosphorus-doped reduced graphene oxide.

[0057] Step 3. Take sodium citrate and chloroauric acid solution with a concentration of 0.2 wt.% and react them at 80℃ for 30 min to obtain Au nano-seed dispersion; wherein the mass ratio of sodium citrate to chloroauric acid solution is 3:1; add 0.3 wt.% AgNO3 solution and sodium borohydride to the above Au nano-seed dispersion, wherein the mass ratio of AgNO3 solution to chloroauric acid solution is 5:1, and the mass ratio of the second reducing agent to AgNO3 solution is 3:1, and react at 90℃ for 60 min to obtain Au-Ag heterojunction nano-dispersion.

[0058] Step 4. Mix aminated carbon nanotubes, phosphorus-doped reduced graphene oxide and Au-Ag heterojunction nanoparticle dispersion in a mass ratio of 1:3:2; sonicate at 40℃ for 50 min to obtain mixed dispersion.

[0059] Step 5. Pre-treat the PDMS substrate using ultraviolet ozone treatment; immerse the pre-treated PDMS substrate in a 5% KH560 ethanol solution and react at 35°C for 60 min, then remove, wash and dry; then immerse it in a 15% polyethylene glycol diamine solution and perform a crosslinking reaction at 100°C for 4 h, and dry to obtain the modified PDMS substrate.

[0060] Step 6. Coat the mixed dispersion obtained in step 4 onto the modified PDMS substrate, and dry it to form a sensitive layer; prepare copper electrodes at both ends of the sensitive layer by sputtering to obtain a high-sensitivity pressure-temperature dual-mode flexible sensor.

[0061] Comparative Example 1

[0062] A method for preparing a highly sensitive pressure-temperature dual-mode sensor differs from Example 1 in that in step 2, the aqueous solution of graphene oxide is directly subjected to a hydrothermal reaction without the addition of a phosphorus source. Other process parameters and operating conditions are exactly the same as in Example 1.

[0063] Comparative Example 2

[0064] A method for preparing a highly sensitive pressure-temperature dual-mode sensor differs from Example 1 in that Au-Ag heterojunction nanoparticle dispersion is not added in step 3, while other process parameters and operating conditions are exactly the same as in Example 1.

[0065] Comparative Example 3

[0066] A method for preparing a highly sensitive pressure-temperature dual-mode sensor differs from Example 1 in that unaminated carbon nanotubes are used in step 1, while other process parameters and operating conditions are exactly the same as in Example 1.

[0067] Comparative Example 4

[0068] A method for preparing a highly sensitive pressure-temperature dual-mode sensor differs from Example 1 in that the flexible substrate PDMS in step 5 is not modified in any way, while other process parameters and operating conditions are exactly the same as in Example 1.

[0069] Performance testing:

[0070] Pressure test: Connect the electrodes of the sensors prepared in Examples 1-3 and Comparative Examples 1-4 to a multimeter with copper wire, apply a pressure of 0-20 kPa to test them, read the resistance of the sensor, and record the change of the sensor electrical signal to calculate the sensitivity S and response time. S = (R-R0) / (R0×ΔP), where R is the resistance when subjected to pressure ΔP, R0 is the resistance when not subjected to pressure, and ΔP is the external pressure applied to the sensor.

[0071] Temperature Test: The sensors prepared in Examples 1-3 and Comparative Examples 1-4 were placed in a drying oven. The two electrodes of the sensor were connected to a multimeter, which was set to the ohm range. The resistance of the sensor was read. The temperature in the drying oven was raised from room temperature to 80°C. The corresponding temperature and resistance were read by the thermocouple and the data were recorded. The temperature coefficient of resistance (TCR) was calculated according to the formula TCR=(R-R0) / (R0×ΔT), where R is the resistance at 80°C, R0 is the resistance at room temperature, and ΔT is the temperature interval. A heatable metal probe was heated to 80°C and stabilized for a period of time. The probe was then gently brought into contact with the temperature-sensitive conductive composite material on the top of the sensor to sense temperature changes. The corresponding response time was recorded.

[0072] Pressure Cyclic Stability Test: Using a pneumatic or motor-driven cyclic pressure device, the sensors prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to 1000 repeated load-unload cycles at 10 kPa. After every 200 cycles, the resistance value of the sensor at 10 kPa was tested once, and the resistance response curve for each cycle was recorded. Finally, the sensitivity decay rate and resistance fluctuation amplitude of the sensor after 1000 cycles were calculated. The long-term pressure sensing stability was evaluated according to the formula: Sensitivity decay rate = (initial sensitivity - sensitivity after 1000 cycles) / initial sensitivity × 100%, and resistance fluctuation amplitude = (maximum resistance during the cycle - minimum resistance during the cycle) / initial resistance × 100%.

[0073] Temperature cycling stability test: The sensors prepared in Examples 1-3 and Comparative Examples 1-4 were placed in a high and low temperature chamber. The temperature cycling program was set (temperature adjusted to 80℃, heating rate 5℃ / min, holding for 10min; then cooled to room temperature, cooling rate 5℃ / min, holding for 10min, which is 1 cycle), and repeated for 1000 cycles. After every 200 cycles, the TCR of the sensor and the resistance value at room temperature were measured according to the temperature test method. The resistance response curve of each cycle was recorded. Finally, the TCR decay rate and resistance fluctuation amplitude of the sensor after 1000 cycles were calculated. According to the formula TCR decay rate = (initial TCR - TCR after 1000 cycles) / initial TCR × 100%, and resistance fluctuation amplitude = (maximum resistance during the cycle - minimum resistance during the cycle) / initial resistance × 100%, the long-term temperature sensing stability was evaluated.

[0074] Interface adhesion test: The standard tape peel test was adopted. After the pressure-sensitive tape was firmly attached to the surface of the sensitive layer, it was peeled off at a constant rate of 300 mm / min. The adhesion strength was qualitatively evaluated by observing the residual area (%) of the sensitive layer after the tape was peeled off and measuring the change rate of resistance (%) before and after peeling. The corresponding values ​​were recorded.

[0075] The performance test data analysis is as follows:

[0076] Table 1 Pressure and Temperature Test Data

[0077]

[0078] As shown in Table 1, Example 2 exhibits the best overall performance, with a pressure sensitivity of 28.4 kPa. -1 ) and temperature sensitivity (TCR = -0.89%·℃) -1 All of these were the highest. In contrast, the temperature sensitivity of Comparative Example 2 was significantly reduced (TCR = -0.08%·℃). -1 The lack of a Schottky junction between the Au-Ag heterojunction and the phosphorus-doped reduced graphene oxide resulted in a weak resistance response to temperature changes, confirming that heterojunctions are the core components for achieving high-sensitivity temperature sensing. Comparative Example 1 shows the pressure sensitivity (5.2 kPa). -1 ) and temperature sensitivity (-0.35%·℃) -1 The results were all poor because the intrinsic conductivity of phosphorus-doped reduced graphene oxide was low, and it could not form an effective Schottky barrier with the heterojunction. This demonstrates the importance of phosphorus doping for optimizing the energy level structure of conductive networks and enhancing the transport of hot electrons. Comparative Example 3 showed the lowest pressure sensitivity (3.1 kPa). -1 Furthermore, it has the slowest response time (80ms) because unaminated carbon nanotubes tend to aggregate, making it impossible for them to effectively intertwine with phosphorus-doped reduced graphene oxide to form a uniform and sensitive three-dimensional conductive network. Figure 2 As shown, this highlights the necessity of amination treatment for constructing high-performance pressure sensing networks.

[0079] Table 2 Test data on pressure cycle stability and interfacial adhesion.

[0080]

[0081] As shown in Table 2, Examples 1-3 exhibit superior performance compared to the comparative examples in terms of interfacial bonding, pressure cycling stability, and temperature cycling stability. This is attributed to the multiple chemical bonds formed by the dual modification of the PDMS substrate, which allows the sensitive layer to be tightly integrated with the substrate. During pressure cycling, the sensitivity decay rate was as low as 5.2%, and the resistance fluctuation range was only ±4.5%. This is attributed to the continuous carbon framework constructed by aminated carbon nanotubes and phosphorus-doped graphene, combined with the multi-level conductive pathways formed by Au-Ag heterojunction filling, which can resist repeated mechanical stress and is not easily broken. During temperature cycling, the TCR decay rate was 4.3%, and the resistance fluctuation range was 3.8%. This is the result of the combined effects of phosphorus doping optimizing the electronic structure of graphene, Au-Ag heterojunction stabilizing the thermoelectric response, and modified PDMS suppressing thermal expansion. In contrast, comparative examples 4, due to the lack of PDMS modification, showed reduced interfacial bonding (52% residual area, 62.3% resistance change rate) and complete failure of pressure and temperature cycling stability (48.5% sensitivity decay rate, 32.5% TCR decay rate); comparative example 3, due to the lack of amination of carbon nanotubes, saw its sensitivity decay rate rise to 36.8% during pressure cycling due to aggregation; and comparative example 2, due to the absence of Au-Ag heterojunction, experienced a TCR decay rate of 12.3% during temperature cycling.

[0082] In summary, the pressure-temperature dual-mode sensing performance of Examples 1-3 achieved high sensitivity and rapid response detection of pressure and temperature signals by compositing aminated carbon nanotubes, phosphorus-doped reduced graphene oxide, and Au-Ag heterojunction nanoparticles on an interface-modified PDMS substrate.

[0083] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0084] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A method for fabricating a highly sensitive pressure-temperature dual-mode sensor, characterized in that, Including the following: Step 1. After acid treatment, carbon nanotubes are reacted with silane coupling agent KH550 to obtain aminated carbon nanotubes; Step 2. After mixing the phosphorus source with the graphene oxide solution, a hydrothermal reaction is carried out to obtain phosphorus-doped reduced graphene oxide; Step 3. React chloroauric acid solution with the first reducing agent to obtain Au nanoseeds; add AgNO3 solution and the second reducing agent to the system containing Au nanoseeds to react and obtain Au-Ag heterojunction nanodispersion; Step 4. Mix the aminated carbon nanotubes, the phosphorus-doped reduced graphene oxide, and the Au-Ag heterojunction nanodispersion, and then treat with ultrasound to obtain a mixed dispersion. Step 5. The pretreated PDMS substrate is first immersed in KH560 ethanol solution, then taken out, cleaned and dried, and then immersed in polyethylene glycol diamine solution for crosslinking reaction to obtain modified PDMS substrate; Step 6. Coat the mixed dispersion onto the modified PDMS substrate, dry it to obtain a sensitive layer, and fabricate electrodes at both ends of the sensitive layer to obtain a highly sensitive pressure-temperature dual-mode flexible sensor.

2. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 1, the acid used for acid treatment is nitric acid or sulfuric acid; the mass ratio of the carbon nanotubes, acid and silane coupling agent KH550 is 1:(50-200):(1-5).

3. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 1, the acid treatment reaction temperature is 60-100℃ and the reaction time is 2-6h; the reaction temperature with silane coupling agent KH550 is 70-90℃ and the reaction time is 2-4h.

4. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 2, the phosphorus source includes any one of phosphoric acid, phosphorous acid, and red phosphorus; the concentration of the graphene oxide solution is 0.1 wt.%-0.2 wt.%; the mass ratio of the phosphorus source to the graphene oxide solution is 1:(10-50); the temperature of the hydrothermal reaction is 150-200℃, and the reaction time is 6-12 h.

5. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 3, the first reducing agent includes any one of sodium citrate, ascorbic acid, and sodium borohydride; the second reducing agent includes any one of sodium citrate, ascorbic acid, and sodium borohydride; the mass ratio of the first reducing agent to the chloroauric acid solution is (1-3):1; the mass ratio of the second reducing agent to the AgNO3 solution is (1-2):1; the mass ratio of the AgNO3 solution to the chloroauric acid solution is (1-5):1; the concentration of the chloroauric acid solution is 0.1wt.%-0.2wt.%; and the concentration of the AgNO3 solution is 0.1wt.%-0.3wt.%.

6. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 3, the Au nanoseeds are prepared at a temperature of 50-80℃ and a reaction time of 10-30 min; the Au-Ag heterojunction nanoparticles are prepared at a temperature of 60-90℃ and a reaction time of 20-60 min.

7. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 4, the mass ratio of the aminated carbon nanotubes, phosphorus-doped reduced graphene oxide, and Au-Ag heterojunction nanoparticles is 1:(1-3):(0.5-2); the ultrasonic treatment temperature is 20-40℃ and the time is 30-50min.

8. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 5, the pretreatment is performed using low-temperature oxygen plasma treatment or ultraviolet ozone treatment; the concentration of the KH560 ethanol solution is 1wt.%-5wt.%; the concentration of the polyethylene glycol diamine solution is 5wt.%-15wt.%; the immersion temperature in the KH560 ethanol solution is 15-35℃ and the time is 30-60 min; the crosslinking reaction temperature is 60-100℃ and the time is 1-4 h.

9. The method for fabricating a high-sensitivity pressure-temperature dual-mode sensor according to claim 1, characterized in that, In step 6, the electrode is made of any one of silver, gold, or copper, and the electrode is prepared by screen printing or sputtering.

10. A highly sensitive pressure-temperature dual-mode sensor, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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