A method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene

Abstract

This invention discloses a method based on Ti3C2T x The fabrication method of MXene's flexible pressure sensor includes the preparation of carbon nanotube coils, Ti3C2Tx powder preparation, and Ti3C2T... x The process involves steps such as MXene fabrication, PDMS solution preparation, mold selection, and thin film coating. This invention utilizes Ti3C2T, which exhibits good responsiveness and high sensitivity. x MXene is incorporated into PDMS to improve the shortcomings of traditional sensors with insignificant response. The porous nature of the composite structure makes the material compressible, improves the contact of the conductive layer, and enhances the resistance change. Through the conversion of "pressure → deformation → resistance change", it can be used to sensitively capture strain signals such as motion.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, and particularly relates to a sensor based on Ti3C2T. x Method for fabricating MXene's flexible pressure sensor. Background Technology

[0002] Carbon nanotube coils (CNCs) have demonstrated broad application potential in various fields in recent years due to their unique helical structure, excellent mechanical properties, and electrical characteristics, especially in the field of sensors where they have made significant progress. In strain sensors, the helical coil's one-dimensional structure possesses inherent elasticity. Under pressure, the helix expands / contracts, and upon release, it quickly rebounds without structural breakage. Simultaneously, the conductivity is precisely controlled by altering the contact state (contact area / number) between coils, which is the core mechanism of piezoresistive sensing. The high specific surface area further enhances interface contact and signal response efficiency. Furthermore, it exhibits high sensitivity (helical deformation amplifies conductivity changes, resulting in a more significant response under low pressure), a wide dynamic range (covering micro-pressure Pa levels to high-pressure kPa / MPa levels, with small-amplitude helical deformation suitable for micro-pressure and large-amplitude compression suitable for high-pressure), fast response / recovery speed, and low hysteresis (the helical structure has good rebound characteristics with no significant deformation hysteresis), and a low detection limit, enabling it to capture weak pressure signals such as pulses and touch input.

[0003] As emerging two-dimensional nanomaterials, transition metal carbonitrides (MXenes) show great application potential in electrochemistry, electromagnetic shielding, and various types of sensors. Ti3C2T x MXene nanosheets have been proven to possess two-dimensional layered stacking, with easy interlayer slippage and adjustable spacing, directly altering the conductive pathway under pressure, providing a natural basis for efficient piezoresistive sensing. Surface functional groups can flexibly modulate electron transport and interfacial interactions. They exhibit extremely low detection limits, capable of capturing weak pressure signals such as pulse and respiration. However, overcoming the problems of layer self-stacking effect, high brittleness, low tensile strength, and susceptibility to cracking during the fabrication of flexible pressure sensors, and constructing flexible pressure sensors with a stable three-dimensional porous conductive network, high sensitivity, wide measurement range, and excellent mechanical durability, remains a critical technical challenge urgently needing to be addressed in the industry. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a method based on Ti3C2T. x Method for fabricating MXene's flexible pressure sensor.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A Ti3C2T-based xThe fabrication method of the MXene flexible pressure sensor includes the following steps:

[0007] (1) Add 1~2g of LiF to 10~20mL of HCl and 5~10mL of deionized water, and stir magnetically for 5~10 min to fully dissolve and obtain etching solution;

[0008] (2) 1g of Ti3AlC2 was slowly added to the etching solution and continuously magnetically stirred for 18-26 hours to obtain Ti3C2T. x Mixed solutions;

[0009] (3) Wash Ti3C2T repeatedly by centrifugation with dilute hydrochloric acid and deionized water. x Mix the solution until Ti3C2T x The pH of the mixed solution was 6.5-7.5 to obtain Ti3C2T. x Dispersion;

[0010] (4) The obtained Ti3C2T x The dispersion was vacuum dried for 8-12 hours to obtain Ti3C2T x powder;

[0011] (5) Weigh an appropriate amount of Ti3C2T x Deionized water was added to the powder and ultrasonically dispersed for 1 hour. After mixing and centrifugation, Ti3C2T was obtained. x MXene dispersion;

[0012] (6) Weigh carbon nanotubes and Ti3C2Tx MXene dispersion in a test tube at a mass ratio of 1:1, add deionized water and shake thoroughly. Then, sonicate the test tube and shake it again after sonication. Repeat the sonication-shaking operation 5 times to obtain a mixture of carbon nanotubes and Ti3C2Tx.

[0013] (7) The mixture of carbon nanotube coil and Ti3C2Tx was placed in a vacuum filtration flask and filtered for 24 hours. After filtration, a carbon nanotube coil & Ti3C2Tx composite film was obtained.

[0014] (8) Select carbon nanotube coils & Ti3C2T x The composite film is cut to a predetermined size, and then silver paste is used to bond and fix the fine copper wire to the composite film to form a resistor.

[0015] (9) Pour a mixture of polydimethylsiloxane (PDMS) and curing agent in a mass ratio of 10:1 into the mold, and then place the resistive component obtained in step (8) into it to overcome Ti3C2T xThe flexible pressure sensor is fabricated by layer self-stacking effect, followed by room temperature for 24 hours for complete curing, and finally peeling the cured PDMS from the mold.

[0016] The innovation of this invention lies in the use of highly sensitive Ti3C2T x MXene is incorporated into carbon nanotube coils to improve the shortcomings of pure MXene sheets, such as high brittleness, low tensile strength, weak interlayer bonding, and easy cracking under large deformation and bending, thereby improving the pressure sensor.

[0017] Furthermore, the molar concentration of HCl in step (1) is 10~15 mol / L. Deionized water is used to dilute the HCl. An appropriate amount of dilute HCl can fully dissolve with LiF to generate HF in situ to form an etching solution.

[0018] Furthermore, in step (2), the stirring temperature of the etching solution is 30~60 ℃, preferably 50 ℃. At this temperature, Ti3AlC2 can accelerate the reaction without reacting too violently and reducing the etching efficiency.

[0019] Furthermore, the centrifugation rate in steps (3) and (5) is 3000 rpm, and the centrifugation time is 5~20 min. The purpose of centrifugation in step (3) is to precipitate the synthesized MXene nanosheets at the bottom and separate them from the acidic solution; the purpose of centrifugation in step (5) is to separate the undispersed and dispersed Ti3C2T x MXene separation, undispersed Ti3C2T x MXene particles compared to dispersed Ti3C2T x MXene tablets are large and can settle at the bottom after centrifugation.

[0020] Furthermore, the vacuum drying temperature in step (4) is 30~60 ℃, which can ensure the drying of Ti3C2T x The structural properties of MXene powder are not altered or destroyed.

[0021] Furthermore, the sensor with the best performance is achieved when the carbon nanotube coil weighs 500 mg and the Ti3C2Tx MXene dispersion concentration is 5 mg / mL, as measured in step (6).

[0022] Furthermore, in step (9), the composite film is cut to a size of 1cm. 2 The resistive element formed in this area has a fast response and high sensitivity, and the flexible pressure sensor made from it is easier to fit the skin.

[0023] Furthermore, the surface of the mold has a micro-dot structure with a diameter of 20~30 µm. By constructing a micro-dot array on the surface of the mold, the problem of low sensitivity, high detection lower limit, and narrow linear range of traditional planar sensors is successfully solved by utilizing the mechanism of nonlinear change of contact area with pressure. At the same time, this structure, as a micro-spring unit, significantly enhances the elastic recovery ability and cycle stability of the composite material, and is a key structural basis for realizing high-performance flexible pressure sensing.

[0024] The advantages of this invention are: the technology of this invention controls the carbon nanotube coil and Ti3C2T x The ratio of carbon nanotube coils to their helical elastic structure can effectively block Ti3C2T. x Nanosheets aggregate between layers, supporting a loose conductive network, widening the interlayer slip space, and significantly improving the elasticity, flexibility, and fatigue resistance of the composite film; Ti3C2T x Its ultra-high conductivity enhances electron transmission efficiency and significantly improves sensing sensitivity. The composite membrane has both a wide dynamic detection range and a low pressure detection limit. It has a fast response recovery speed, low hysteresis, and minimal performance degradation after cyclic pressure. It also has a tight interface bond, good compatibility with flexible substrates, and is easy to process and mold, making it suitable for flexible detection scenarios such as wearable sensing and electronic skin. Attached Figure Description

[0025] Figure 1 This is a basic unit structure diagram of the flexible pressure sensor of the present invention;

[0026] Figure 2 This is a curve showing the resistance change characteristics of the flexible pressure sensor of the present invention under pressure of 0~1N;

[0027] Figure 3 This is a curve showing the resistance change characteristics of the flexible pressure sensor of the present invention under pressure of 0~5N;

[0028] Figure 4 This is a curve showing the resistance change characteristics of the flexible pressure sensor of the present invention under pressure of 0~10N;

[0029] Figure 5 This is a curve showing the resistance change characteristics of the flexible pressure sensor of the present invention under pressure of 0~100N. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings:

[0031] This invention combines carbon nanotube coils, which possess excellent flexibility, high specific surface area, and outstanding pressure sensing response characteristics, with Ti3C2Tx MXene, which exhibits superior conductivity, good mechanical compatibility, and stable interfacial bonding capabilities, to create a flexible, wearable, self-powered pressure sensor with high-sensitivity pressure response, rapid response recovery, and good stability. The sensor's composite thin film employs a micro-dome structure design, which effectively improves pressure transmission efficiency, facilitates the design of an array touch structure, and allows for stable integration onto a flexible substrate to fabricate a high-density sensing array. This enables precise detection of pressure changes in specific areas, such as the pressure, touch, and pressure intensity changes of fingers or other body skin, thus meeting the practical application needs of wearable devices.

[0032] Example 1

[0033] A Ti3C2T-based x The fabrication method of the MXene flexible pressure sensor includes the following steps:

[0034] (1) Add 1.0 g of LiF to 10 mL of 7 mol / L HCl and 5 mL of deionized water, and stir magnetically for 5 min to fully dissolve to obtain etching solution;

[0035] (2) 1 g Ti3AlC2 was slowly added to the etching solution and etched by continuous magnetic stirring at 30 °C for 18 hours to obtain a Ti3C2Tx mixed solution;

[0036] (3) Wash Ti3C2T repeatedly by centrifuging with dilute hydrochloric acid and deionized water at a centrifugation rate of 4000 rpm. x Mix the solution until Ti3C2T x The pH of the mixed solution was 6.5-7.5 to obtain Ti3C2T. x Dispersion;

[0037] (4) The obtained Ti3C2T x The dispersion was vacuum dried at 30 °C for 12 hours to obtain Ti3C2T. x powder;

[0038] (5) In Ti3C2T x The powder was ultrasonically dispersed in deionized water for 1 hour, then mixed thoroughly and centrifuged at 4000 rpm for 20 min to obtain Ti3C2T. x MXene dispersion;

[0039] (6) Weigh carbon nanotube coil and Ti3C2Tx MXene dispersion in a test tube at a mass ratio of 1:1. After adding the mixture, add deionized water and shake thoroughly. Then, sonicate the test tube. After sonication, shake again. Repeat the sonication-shaking operation 5 times to obtain a mixture of carbon nanotube coil and Ti3C2Tx.

[0040] (7) Integrating carbon nanotube coils with Ti3C2T x The mixture was placed in a vacuum filtration flask and filtered for 24 hours. After filtration, carbon nanotube coils and Ti3C2T were obtained. x Composite films;

[0041] (8) Select carbon nanotube coils & Ti3C2T x The composite film is cut to a predetermined size, and then the thin copper wire is bonded and fixed to the composite film with silver paste to form a resistor.

[0042] (9) Pour a PDMS and curing agent mixture with a mass ratio of 10:1 into the mold, and place the resistive element obtained in step (8) into it. Then, let it stand at room temperature for 24 hours until it is completely cured. Finally, peel the cured PDMS out of the mold to complete the preparation of the flexible pressure sensor. In this step, the coating and support of the composite film by PDMS effectively overcomes the Ti3C2T x The self-stacking effect of the layers improves the defects of composite films such as high brittleness, low tensile strength and easy cracking, and enhances the mechanical stability and flexibility of the device.

[0043] Example 2

[0044] A Ti3C2T-based x The fabrication method of the MXene flexible pressure sensor includes the following steps:

[0045] (1) Add 2.0 g of LiF to 120 mL of 10 mol / L HCl and 10 mL of deionized water, and stir magnetically for 10 min to fully dissolve and obtain etching solution;

[0046] (2) 1 g of Ti3AlC2 was slowly added to the etching solution and etched by continuous magnetic stirring at 60 °C for 26 hours to obtain Ti3C2T x Mixed solutions;

[0047] (3) Wash Ti3C2T repeatedly by centrifuging with dilute hydrochloric acid and deionized water at a centrifugation rate of 4000 rpm. x Mix the solution until Ti3C2T x The pH of the mixed solution was 6.5-7.5 to obtain Ti3C2T. x Dispersion;

[0048] (4) The obtained Ti3C2T x The dispersion was vacuum dried at 60 °C for 12 hours to obtain Ti3C2Tx powder;

[0049] (5) In Ti3C2T x The powder was ultrasonically dispersed in deionized water for 1 hour, then mixed thoroughly and centrifuged at 4000 rpm for 20 min to obtain Ti3C2T. x MXene dispersion; centrifugation rate: 4000 rpm;

[0050] (6) Weigh carbon nanotube coil and Ti3C2Tx MXene dispersion in a test tube at a mass ratio of 1:1. After adding the mixture, add deionized water and shake thoroughly. Then, sonicate the test tube. After sonication, shake again. Repeat the sonication-shaking operation 5 times to obtain a mixture of carbon nanotube coil and Ti3C2Tx.

[0051] (7) Integrating carbon nanotube coils with Ti3C2T x The mixture was placed in a vacuum filtration flask and filtered for 24 hours. After filtration, carbon nanotube coils and Ti3C2T were obtained. x Composite films;

[0052] (8) Select carbon nanotube coils & Ti3C2T x The composite film is cut to a predetermined size, and then the thin copper wire is bonded and fixed to the composite film with silver paste to form a resistor.

[0053] (9) Pour a PDMS and curing agent mixture solution with a mass ratio of 10:1 into the mold, and put the resistive component obtained in step (8) into it. Then place it at room temperature for 24 hours until it is completely cured. Finally, peel the cured PDMS out of the mold to complete the preparation of the flexible pressure sensor.

[0054] Example 3

[0055] A Ti3C2T-based x The fabrication method of the MXene flexible pressure sensor includes the following steps:

[0056] (1) Add 1.6 g of LiF to 15 mL of 9 mol / L HCl and 10 mL of deionized water, and stir magnetically for 10 min to fully dissolve to obtain etching solution;

[0057] (2) 1 g of Ti3AlC2 was slowly added to the etching solution and etched by continuous magnetic stirring at 50 °C for 24 hours to obtain Ti3C2T x Mixed solutions;

[0058] (3) Wash Ti3C2T repeatedly by centrifuging with dilute hydrochloric acid and deionized water at a centrifugation rate of 4000 rpm. x Mix the solution until Ti3C2T x The pH of the mixed solution was 6.5-7.5 to obtain Ti3C2T. x Dispersion;

[0059] (4) The obtained Ti3C2T x The dispersion was vacuum dried at 60°C for 12 hours to obtain Ti3C2T. x powder;

[0060] (5) In Ti3C2T x The powder was ultrasonically dispersed in deionized water for 1 hour, then mixed thoroughly and centrifuged at 4000 rpm for 20 min to obtain Ti3C2T. x MXene dispersion; centrifugation rate: 4000 rpm;

[0061] (6) Weigh carbon nanotube coil and Ti3C2Tx MXene dispersion in a test tube at a mass ratio of 1:1. After adding the mixture, add deionized water and shake thoroughly. Then, sonicate the test tube. After sonication, shake again. Repeat the sonication-shaking operation 5 times to obtain a mixture of carbon nanotube coil and Ti3C2Tx.

[0062] (7) Integrating carbon nanotube coils with Ti3C2T x The mixture was placed in a vacuum filtration flask and filtered for 24 hours. After filtration, carbon nanotube coils and Ti3C2T were obtained. x Composite films;

[0063] (8) Select carbon nanotube coils & Ti3C2T x The composite film is cut to a predetermined size, and then the thin copper wire is bonded and fixed to the composite film with silver paste to form a resistor.

[0064] (9) Pour a PDMS and curing agent mixture solution with a mass ratio of 10:1 into the mold, and put the resistive component obtained in step (8) into it. Then place it at room temperature for 24 hours until it is completely cured. Finally, peel the cured PDMS out of the mold to complete the preparation of the flexible pressure sensor.

[0065] The preparation method of carbon nanotube coils (CNCs) in this invention

[0066] (S1) Adjust the balance so that the liquid droplet is centered. Fold the weighing paper and return it to zero. Weigh Fe2(SO4) and SnCl4·5H2O in a certain ratio (M: Fe2(SO4)3 = 399.86, M: SnCl4·5H2O = 350.6).

[0067] (S2) Take Fe 3+ :Sn 4+ (Molar ratio) is 15:1, 10:1, weighing

[0068] 15:1 Fe2(SO4)30.04g SnCl4·5H2O 0.00468g

[0069] 10:1 Fe2(SO4)3 0.04g SnCl4·5H2O 0.00701g

[0070] Since the amount of solid to be weighed is very small, you can use a spoon to take the sample and pour it into the weighing paper, then slowly push it onto the balance. SnCl4·5H2O can be dripped directly onto the inner wall, and finally rinsed with liquid.

[0071] (S3) Two catalyst synthesis methods

[0072] ① Rinse SnCl4·5H2O with ethanol until the solution volume is about two-thirds of that in the reactor.

[0073] ② Rinse SnCl4·5H2O into the solution with N,N-dimethylformamide, filling the reactor to about two-thirds of its volume.

[0074] (S4) Add the magnetic stir bar, transfer the solution to the stirring table, set the temperature to room temperature, and adjust the speed to 600-700 r / min. If using method ①, the stirring time is 60 min; if using method ②, the stirring time is 30 min.

[0075] (S5) Heating

[0076] Using method ①, the solution was refilled into an alloy kettle and placed in an oven for a reaction time of 8 hours (480 minutes) at a temperature of 160°C.

[0077] Method ② was used, and similarly, the reaction time was 30 hours (1800 minutes) and the temperature was 180°C.

[0078] (S6) Open the reaction vessel and pour the waste liquid into the alkaline waste liquid tank. A red solid will precipitate out. Add ethanol to the reaction vessel and transfer the resulting solution to a test tube to the 20mL mark.

[0079] (S7) Centrifuge at 8000 rpm for 5 minutes. Add water → add ethanol → add water → add ethanol → add water. Centrifuge for 5 minutes each time, rinsing repeatedly. Pour the water from the last centrifugation into a beaker, and transfer the water from the beaker to an alkaline waste container.

[0080] (S8) Drying: Open the lid of the test tube and place it in a drying oven to dry for 12 hours.

[0081] (S9) Ultrasound, 30 minutes each time, 6 times in total, 3 hours in total. Note that the water should be changed every two ultrasounds.

[0082] (S10) Spin coating: Prepare a 300µm silicon wafer with a size of 1cm×1cm. Turn on the vacuum pump, place the silicon wafer at the adsorption point, adjust the spin speed to 3000 rpm, and spin coating time to about 25 seconds. Experiments have shown that the growth effect is best when the number of spin coatings is 10, 15, 20, and 25.

[0083] (S11) Calcination 1: Mount the silicon wafer, place the furnace plug, and connect the device. First, check the airtightness of the device. Open the main hydrogen valve (rotate counterclockwise), then turn it clockwise to the next level. Open the argon inlet valve and control the argon flow rate to approximately 700 scam. Use a cotton swab soaked in foam to check for leaks. Then click "close" for argon. Rotate counterclockwise to open the main acetylene valve, and turn the pressure reducing valve clockwise to the next level. Open the acetylene inlet valve and set the acetylene flow rate to 30 scam. Click "run" and check for leaks again. Replace the exhaust gas treatment bottle with an oil bottle.

[0084] (S12) Calcination 2: Turn on the main switch of the heating chamber, click, (Set reaction conditions: 25 (room temperature), 40 min (time for temperature rise), 710 (target temperature), 180 min (reaction time), 710 (final temperature). When -121 is displayed, press and hold, then click again to exit the device settings. Click the green Heating Reading button, press and hold the left oven run button, wait 40 min, then click to introduce acetylene. After reacting for 180 min, end the calcination, close the acetylene main valve, return the pressure reducing valve to 0, click the acetylene close button, wait for the temperature to drop below 500℃, open the oven, wait for it to cool to room temperature, close the argon main valve, and return the pressure reducing valve to zero. Open the device, remove the sample, and turn off the oven power.

[0085] (S13) Scrape the carbon layer on the silicon wafer onto weighing paper with a blade, put it into a small test tube and sonicate for 8 seconds. Use a dropper to take out a piece of carbon and drop it onto a glass slide at 60°C. Then observe it with an electron microscope. Open the Steam start software and click to watch in real time.

[0086] In step (S3), a catalyst with a molar ratio of 10:1 was used. Experiments showed that the catalyst with a molar ratio of 10:1 produced a large number of carbon nanotube coils.

[0087] The carbon nanotube coils with 15 spin-coating cycles in step (S10) showed the best growth effect.

[0088] The LiF, HCl, Ti3AlC2, and Ti3C2T used in the embodimentsx The amounts of PDMS, curing agent, and deionized water used are proportionally reduced or increased depending on the amount of film to be produced. Furthermore, the amounts used in the examples are not fixed. Different curing agent ratios can be used in the examples, such as 2.5:1, 5:1, 7.5:1, and 10:1. The selected mold surface has a micro-dot structure with a diameter of 20-30 μm. The micro-dot structure increases the contact area with the skin, resulting in optimal pressure conversion performance after adhesion to the flexible electrode. The film is cut to a size of 1 cm x 1 cm.

[0089] Figures 1–5 show the performance test results of the basic unit of the flexible pressure sensor prepared in this invention. The performance characterization uses a device with a size of 1 cm × 1 cm, whose initial resistance at zero pressure is 9 kΩ. It should be noted that the geometric area of ​​the sensor only changes the initial resistance and absolute resistance amplitude of the device, and does not affect its intrinsic sensing performance. Therefore, the sensing performance law obtained in this study has universality.

[0090] Figure 1 In the diagram, 1 represents a carbon nanotube coil and a Ti3C2Tx composite film, 2 represents silver paste, 3 represents a PDMS film, and 4 represents a fine copper wire. The flexible pressure sensor is constructed by bonding fine copper wires to both ends of the carbon nanotube coil and Ti3C2Tx composite film with silver paste, and then encapsulating it with a PDMS film and a curing agent.

[0091] Figure 2 The graph in the middle shows the resistance change characteristic of the flexible pressure sensor under pressure of 0~1N. As can be seen from the graph, within the micro-pressure range of 0~1N, the resistance value of the sensor shows a significant and continuous change trend with increasing pressure, without obvious signal hysteresis and fluctuation. Even under extremely low pressure below 0.2N, the resistance can still produce changes that can be accurately captured. This indicates that the sensor has ultra-high detection sensitivity and extremely low detection limit in micro-pressure detection scenarios, and can effectively capture weak pressure signals such as pulse and light touch, which is fully suitable for the application requirements of micro-pressure sensing.

[0092] Figure 3 The graph in the middle shows the resistance change characteristic of the flexible pressure sensor under pressure of 0~5N. As can be seen from the graph, in the low-to-medium pressure range of 0~5N, the resistance of the sensor maintains good linear response as the pressure increases, the correlation between pressure and resistance change is stable, and there is no obvious signal saturation phenomenon. Moreover, the resistance change amplitude is uniform during pressure loading, and it can quickly recover to the initial resistance value after the pressure is unloaded. This demonstrates the excellent response recovery characteristics and low hysteresis of the sensor in this pressure range, making it suitable for detection scenarios with medium pressure such as daily touch and light pressure on the limb.

[0093] Figure 4The figure shows the resistance change characteristic curve of the flexible pressure sensor under pressure of 0~10N. As can be seen from the figure, the sensor maintains stable piezoresistive response characteristics in the medium pressure range of 0~10N. The resistance value changes continuously with the increase of pressure, and the conductive network does not show structural failure due to the increase of pressure. At the same time, the signal-to-noise ratio of the sensor's resistance change signal is high and there is no obvious noise interference. This indicates that the three-dimensional porous conductive network of the composite film is structurally stable in this pressure range, has good mechanical compression resistance and signal stability, and can be adapted to medium pressure sensing scenarios such as limb bending and conventional pressing.

[0094] Figure 5 The figure shows the resistance change characteristic curve of the flexible pressure sensor under pressure of 0~100N. As can be seen from the figure, the sensor can still achieve an effective piezoresistive signal response within the high-pressure range of 0~100N. Even under high pressure of 80~100N, the resistance value still fluctuates significantly with pressure changes, without signal saturation or failure. Furthermore, the sensor structure did not suffer irreversible damage throughout the entire pressure range, proving the effectiveness of the carbon nanotube coil and Ti3C2T. x The composite film combined with the PDMS coating structure has excellent mechanical compressive strength and structural stability, which greatly expands the pressure detection range of the sensor and can be adapted to high-pressure sensing scenarios such as heavy object pressing and strong limb squeezing.

[0095] Although the specific embodiments of the present invention have been described and illustrated in detail above, it should be noted that various changes and modifications can be made to the above embodiments without departing from the spirit of the present invention and the scope set forth in the appended claims.

Claims

1. A Ti3C2T-based x The method for fabricating MXene's flexible pressure sensor is characterized by, Includes the following steps: (1) Add 1~2 g of LiF to 10~20 mL of HCl and 5~10 mL of deionized water, and stir magnetically for 5~10 min to fully dissolve and obtain etching solution; (2) 1 g of Ti3AlC2 is slowly added into the etching solution with magnetic stirring for 18-26 hours to obtain Ti3C2T x mixed solution; (3) The Ti3C2Tx mixed solution was repeatedly washed by centrifugation with dilute hydrochloric acid and deionized water until the pH of the mixed solution was 6.5-7.5 to obtain a Ti3C2Tx dispersion x The pH of the mixed solution was 6.5-7.5 to obtain a Ti3C2Tx dispersion (4) The obtained Ti3C2Tx dispersion was vacuum dried for 8-12 hours to obtain Ti3C2Tx powder; (5) Add deionized water to Ti3C2Tx powder and ultrasonically disperse for 1 hour, then mix and centrifuge to obtain Ti3C2TxMXene dispersion; (6) Weigh carbon nanotubes and Ti3C2Tx MXene dispersion in a test tube at a mass ratio of 1:1, add deionized water and shake thoroughly. Then, sonicate the test tube and shake it again after sonication. Repeat the sonication-shaking operation 5 times to obtain a mixture of carbon nanotubes and Ti3C2Tx. (7) The mixture of carbon nanotube coil and Ti3C2Tx was placed in a vacuum filtration flask and filtered for 24 hours. After filtration, a carbon nanotube coil & Ti3C2Tx composite film was obtained. (8) Select carbon nanotube coils of appropriate specifications / Ti3C2T x The composite film is cut to a preset size. At both ends of the film, fine copper wires are symmetrically bonded to the same surface of the film using silver paste to ensure that the copper wires do not contact each other and there is no short circuit. After the silver paste has fully cured, the resistive sensitive element is obtained. (9) Pour a mixture of polydimethylsiloxane and curing agent in a mass ratio of 10:1 into the mold, and then place the resistor obtained in step (8) into it to overcome Ti3C2T x The flexible pressure sensor is fabricated by layer self-stacking effect, followed by room temperature for 24 hours for complete curing, and finally peeling the cured PDMS from the mold.

2. The method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene according to claim 1, characterized in that, The molar concentration of HCl in step (1) is 7~10 mol / L.

3. The method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene according to claim 2, characterized in that, In step (2), the stirring temperature of the etching solution is 30~60 ℃.

4. The method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene according to claim 3, characterized in that, In steps (3) and (5), the centrifugation rate is 4000 rpm and the centrifugation time is 5 to 20 min.

5. The method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene according to claim 4, characterized in that, The vacuum drying temperature in step (4) is 30~60 ℃.

6. The method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene according to claim 5, characterized in that, The carbon nanotube coil weighed in step (6) is 500~800mg.

7. The method for fabricating a flexible pressure sensor based on Ti3C2Tx MXene according to claim 6, characterized in that, In step (6), the concentration of the Ti3C2Tx MXene dispersion is 3~8 mg / mL.

8. A Ti3C2T based method according to claim 7 x The method for fabricating MXene's flexible pressure sensor is characterized by, The surface of the mold described in step (9) has a micro-dot structure with a diameter of 20~30 µm.

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