Preparation method of MXene gradient fold strain sensor
By constructing a gradient micro-fold structure on an elastic substrate, the MXene strain sensor resolves the contradiction between sensitivity and strain range, achieving a balance between high sensitivity and wide strain range, making it suitable for fields such as health monitoring and electronic skin.
Patent Information
- Application Number
- CN202610124166.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-29
- Publication Date
- 2026-04-14
AI Technical Summary
Existing flexible strain sensors have a trade-off between sensitivity and strain range, making it difficult to achieve high-performance applications in complex scenarios.
By spraying different numbers of MXene film layers onto an elastic substrate, a gradient micro-wrinkled structure is constructed. Combined with pre-stretch stress, controllable micro-wrinkles are formed, thus optimizing the strain transmission path of the sensor.
It achieves a balance between high sensitivity response under low strain and wide strain range under high strain. The sensor exhibits good structural stability and signal reliability during cyclic stretching. The process is simple and efficient, making it suitable for mass production.
Smart Images
Figure CN121855378A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of flexible sensor technology, specifically relating to a method for fabricating an MXene gradient wrinkle strain sensor. Background Technology
[0002] Flexible strain sensors have been widely used in fields such as artificial intelligence, medical health, and electronic skin due to their ultra-high sensitivity response, low manufacturing cost, controllable measurement range, flexibility, and ease of fitting. With the continuous development of flexible electronics technology, the demand for the performance and function of flexible strain sensors in human vital sign signal detection and human-machine interface interaction is constantly increasing, especially the demand for the multi-dimensional strain capability of flexible strain sensors.
[0003] The performance of a sensor is primarily measured by key indicators such as sensitivity (GF value) and strain range. However, these indicators often have mutually restrictive relationships: for example, while introducing microstructural failure mechanisms such as microcracks can significantly improve sensitivity, it often leads to a reduction in the maximum tensile strain range of the material; conversely, designs that pursue a wide strain range often struggle to achieve a high-sensitivity signal response. This inherent contradiction between sensitivity and strain range limits the high-performance application of existing flexible strain sensors in complex scenarios. Summary of the Invention
[0004] This invention aims to provide a method for fabricating a strain sensor by simultaneously constructing a controllable micro-wrinkled structure through gradient spraying of an MXene film onto a pre-stretched elastic substrate. This method can optimize the strain transfer path between MXene nanosheets and control the film thickness by controlling the number of spraying layers, thus solving the key contradiction between the sensitivity and strain range of flexible sensors.
[0005] To achieve the above objectives, the present invention provides a method for fabricating an MXene gradient wrinkle strain sensor, comprising the following steps: S1. Multilayer MXene is prepared by etching, and then the multilayer MXene is ultrasonically peeled off and centrifuged to obtain an MXene solution, which is then dispersed in deionized water to form a uniform MXene dispersion. S2. Provide an elastic substrate, apply pre-tension stress to the elastic substrate, spray the MXene dispersion obtained in S1 onto different areas of the elastic substrate according to different preset layers, and then release the pre-tension stress applied to the elastic substrate to obtain a gradient micro-wrinkled MXene film of preset thickness. S3. Assemble copper electrodes at both ends of the gradient micro-wrinkled MXene film of the preset thickness obtained in S2 using conductive silver paste, and dry and cure at 50~60℃ for 0.5~1.5h to obtain a sensor with assembled electrodes. Then encapsulate it with polydimethylsiloxane solution to obtain an MXene gradient wrinkled strain sensor.
[0006] In the above method, the etching method in S1 is as follows: lithium fluoride and hydrochloric acid are added sequentially to a reaction vessel lined with polytetrafluoroethylene and stirred for 15-20 min. Then, titanium aluminum carbide powder is added in small amounts several times. The mixture is stirred continuously for 40-45 h in a sealed environment to carry out a chemical etching reaction. The chemical etching reaction temperature is 35-40℃ and the stirring rate is 500-600 r / min.
[0007] In the above method, the molar concentration of hydrochloric acid is 9 mol / L, and the ratio of lithium fluoride, hydrochloric acid and titanium aluminum carbide is 6~8g:60~90mL:3~5g.
[0008] In the above method, the small amount is divided into 8 to 9 times within 25 to 30 minutes.
[0009] In the above method, the specific steps of ultrasonic stripping and centrifugal purification in S1 are as follows: First, centrifuge the multilayer MXene, wash the precipitate obtained by centrifugation until neutral, then pour the obtained neutral product into a gas washing bottle, add deionized water, and then place it in an ultrasonic instrument. While ultrasonic treatment, inert gas is introduced for bubbling treatment. Finally, after the bubbling treatment is completed, centrifuge again, retain the upper liquid, and obtain the MXene solution.
[0010] In the above methods, the ultrasonic time is 0.8~1.2h; the inert gas is nitrogen; in the bubbling treatment, the air flow rate is 8~10m / s and the air flow time is 0.8~1.5h; the centrifugation rate is 6000~8000r / min and the centrifugation time is 0.5~0.8h.
[0011] In the above method, the pre-tension stress in S2 is the stress required to be applied when the tension length reaches 100% of the initial length.
[0012] In the above method, the different regions in S2 include the upper part, the middle part and the lower part. The preset number of layers for the upper part is 1, the preset number of layers for the middle part is 2, and the preset number of layers for the lower part is 3.
[0013] In the above method, the polydimethylsiloxane solution is prepared by ultrasonically dispersing polydimethylsiloxane in n-hexane, wherein the mass ratio of n-hexane to polydimethylsiloxane is 10:1, and the ultrasonic dispersion time is 2~2.5h. The specific encapsulation method is as follows: a polydimethylsiloxane solution is drop-coated onto the surface of the sensor with assembled electrodes and cured at 55~60℃ for 4 hours.
[0014] In the above method, the elastic substrate is an ultra-stretched acrylic film.
[0015] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: 1. This invention constructs a gradient micro-wrinkled structure by spraying different preset layers in different areas, enabling the sensor to achieve high sensitivity response under low strain by relying on the rapid unfolding of the regional wrinkles of the thin film, and to maintain wide strain range working capability under high strain by the continuous connection of the regional wrinkles of the thick film. This fundamentally solves the technical problem that it is difficult to achieve both high sensitivity and wide strain range in a single device.
[0016] 2. The gradient micro-fold structure provided by this invention is spontaneously formed during the retraction of the elastic substrate, resulting in a strong bond between the MXene film and the elastic substrate, effectively preventing material detachment. This structure can reversibly unfold and recover during cyclic stretching, ensuring the stability and repeatability of changes in the conductive path, and enabling the sensor output signal to have high reliability.
[0017] 3. The preparation process provided by this invention is simple and efficient. Based on the core process of pre-stretching spraying release, this invention can precisely control the film thickness gradient simply by controlling the number of sprayings and the amount of each spray, without relying on photolithography or template equipment. The process is simple and efficient, significantly reducing preparation complexity and time costs, and has the potential for large-scale production.
[0018] 4. This invention utilizes the high conductivity and rich surface properties of MXene material, combined with the unique strain mechanism of gradient pleated structure, to endow the sensor with fast response characteristics and excellent environmental tolerance, significantly expanding its application value in high-requirement fields such as health monitoring and electronic skin. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 A schematic diagram of the MXene gradient wrinkle strain sensor prepared in Example 1; Figure 2 A schematic diagram showing the sensitivity and strain range of the MXene gradient wrinkle strain sensor prepared in Example 1; Figure 3 This is a schematic diagram showing the sensitivity and strain range of the control group; Figure 4 The images shown are SEM images of the MXene film prepared in Example 1; where a is the upper SEM image, b is the middle SEM image, and c is the lower SEM image. Detailed Implementation
[0021] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental and detection methods described in each embodiment are conventional methods; the reagents and materials described are commercially available unless otherwise specified. Unless otherwise specified, all percentages in the following embodiments refer to mass percentages. Unless otherwise specified, all proportions in the following embodiments refer to mass ratios.
[0022] The experimental instruments and reagents are shown in Tables 1 and 2: Table 1: Reagent Details Table 2: Instrument Details Example 1 This embodiment provides an MXene gradient wrinkle strain sensor and its fabrication method.
[0023] The preparation method in this embodiment includes the following steps: S1. In a polytetrafluoroethylene-lined reactor, 4g of lithium fluoride and 45mL of 9mol / L hydrochloric acid were added sequentially and stirred at a stirring rate of 600r / min for 20min. Then, 2g of titanium aluminum carbide was added in 9 portions over 30min. The mixture was stirred continuously for 45h in a sealed environment at 40℃ to carry out a chemical etching reaction and obtain multilayer MXene. The multilayer MXene was centrifuged at 8000 r / min. The precipitate obtained by centrifugation was washed with 2 mol / L HCl solution until neutral. The resulting neutral product was then poured into a gas washing bottle, deionized water was added, and the bottle was placed in an ultrasonic instrument for ultrasonic treatment for 1.2 h. At the same time, nitrogen gas was introduced for bubbling treatment. The gas flow rate was 10 m / s and the gas flow time was 1.5 h. Finally, after the bubbling treatment, the mixture was centrifuged again at 8000 r / min for 0.8 h, and the supernatant rich in monolayer MXene nanosheets was collected to obtain an MXene solution. This solution was then dispersed in 50 mL of deionized water to form a uniform MXene dispersion.
[0024] S2. Using an ultra-stretched acrylic film as an elastic substrate, apply 100% pre-stretch stress to the elastic substrate, spray the MXene dispersion obtained in S1 onto the upper part of the elastic substrate with a preset number of 1 layers, then spray 2 layers onto the middle part of the elastic substrate, and spray 3 layers onto the lower part of the elastic substrate. The spraying time for each layer is the same. Then release the 100% pre-stretch stress applied to the elastic substrate to obtain a gradient micro-wrinkled MXene film of preset thickness. S3. Assemble copper electrodes at both ends of the gradient micro-wrinkled MXene film of the preset thickness obtained in S2 using conductive silver paste. Dry and cure at 60°C for 1.5 hours to obtain a sensor with assembled electrodes. Then, drop-coat the polydimethylsiloxane solution onto the surface of the sensor with assembled electrodes and cure at 60°C for 4 hours to obtain the desired result. Figure 1 The MXene gradient fold strain sensor is shown.
[0025] The preparation method of the polydimethylsiloxane solution is as follows: polydimethylsiloxane is ultrasonically dispersed in n-hexane, wherein the mass ratio of n-hexane to polydimethylsiloxane is 10:1, and the ultrasonic dispersion time is 2.5 h.
[0026] The resistance change of the MXene gradient wrinkle strain sensor obtained in this embodiment was monitored in real time under different strains using a digital multimeter. The test results are as follows: Figure 2 As shown, the strain range can reach 300%, and it exhibits extremely high strain factors in different strain ranges. Specifically, the strain factor (GF) is 119.88 in the 0~150% range, rises to 2172.24 in the 150%~240% range, and reaches 65172.68 in the high strain range of 240%~300%. This embodiment also provides a control group: an MXene sensor without gradient wrinkles. The difference between this control group and Example 1 is that no pre-tension stress was applied to the elastic substrate in S2. The test results are as follows... Figure 3 As shown, the strain range is 300%, but the sensitivity is significantly lower than that of the MXene gradient-wrinkled strain sensor prepared in Example 1. The GF value of the MXene sensor without gradient wrinkles is low in all stages: 31.53 in the range of 0~140%, 161.65 in the range of 140%~210%, 954.99 in the range of 210%~260%, and 2446.58 in the range of 260%~300%. This indicates that the gradient micro-wrinkled structure provided in this example can significantly improve the sensitivity of the sensor in the entire working range, especially under higher strain conditions, the performance improvement is more prominent.
[0027] Electron microscopy analysis was performed on the gradient micro-wrinkled MXene film of the preset thickness obtained in S2 of this embodiment, such as... Figure 4 As shown, a significant gradient decrease in micro-wrinkle density can be observed from top to bottom, indicating that the gradient micro-wrinkled MXene film provided in this embodiment possesses layered deformation response characteristics. The upper high-density wrinkled region preferentially unfolds under low strain, generating high-density microcrack channels, effectively improving initial sensitivity; the lower low-density wrinkled structure maintains a continuous conductive framework during the high strain stage, significantly widening the working strain range. This gradient structure, through a graded release mechanism of strain energy, enables the sensor to maintain response stability and structural integrity within a wide strain range.
[0028] Example 2 This embodiment provides an MXene gradient wrinkle strain sensor and its fabrication method.
[0029] The preparation method in this embodiment includes the following steps: S1. In a polytetrafluoroethylene-lined reactor, 3g of lithium fluoride and 30mL of 9mol / L hydrochloric acid were added sequentially and stirred at a stirring rate of 500r / min for 15min. Then, 1.8g of titanium aluminum carbide was added in 8 portions over 25min. The mixture was stirred continuously for 40h in a sealed environment at 35℃ to carry out a chemical etching reaction and obtain multilayer MXene. The multilayer MXene was centrifuged at 8000 r / min. The precipitate obtained by centrifugation was washed with 2 mol / L HCl solution until neutral. The resulting neutral product was then poured into a gas washing bottle, deionized water was added, and the bottle was placed in an ultrasonic instrument for ultrasonic treatment for 0.8 h. At the same time, nitrogen gas was introduced for bubbling treatment. The gas flow rate was 8 m / s and the gas flow time was 0.8 h. Finally, after the bubbling treatment, the mixture was centrifuged again at 8000 r / min for 0.5 h, and the supernatant rich in monolayer MXene nanosheets was collected to obtain an MXene solution. This solution was then dispersed in 45 mL of deionized water to form a uniform MXene dispersion.
[0030] S2. Using an ultra-stretched acrylic film as an elastic substrate, apply 100% pre-stretch stress to the elastic substrate, spray the MXene dispersion obtained in S1 onto the upper part of the elastic substrate with a preset number of 1 layers, then spray 2 layers onto the middle part of the elastic substrate, and spray 3 layers onto the lower part of the elastic substrate. The spraying time for each layer is the same. Then release the 100% pre-stretch stress applied to the elastic substrate to obtain a gradient micro-wrinkled MXene film. S3. Assemble copper electrodes at both ends of the gradient micro-wrinkled MXene film of the preset thickness obtained in S2 using conductive silver paste. Dry and cure at 50°C for 0.5 hours to obtain a sensor with assembled electrodes. Then, drop-coat the polydimethylsiloxane solution onto the surface of the sensor with assembled electrodes and cure at 55°C for 4 hours to obtain the desired result. Figure 1 The MXene gradient fold strain sensor is shown.
[0031] The preparation method of the polydimethylsiloxane solution is as follows: polydimethylsiloxane is ultrasonically dispersed in n-hexane, wherein the mass ratio of n-hexane to polydimethylsiloxane is 10:1, and the ultrasonic dispersion time is 2 hours.
[0032] The resistance change of the MXene gradient wrinkle strain sensor obtained in this embodiment was monitored in real time under different strains using a digital multimeter. The test results show that the strain range can reach 300%, and it exhibits extremely high strain factors in different strain ranges.
[0033] Example 3 This embodiment provides an MXene gradient wrinkle strain sensor and its fabrication method.
[0034] The preparation method in this embodiment includes the following steps: S1. 3.5g of lithium fluoride and 40mL of 9mol / L hydrochloric acid were added sequentially to a polytetrafluoroethylene-lined reactor and stirred at a stirring rate of 500r / min for 18min. Then, 1.9g of titanium aluminum carbide was added in 8 portions over 18min. The mixture was stirred continuously at 38℃ for 43h under a sealed environment to carry out a chemical etching reaction and obtain multilayer MXene. The multilayer MXene was centrifuged at 8000 r / min. The precipitate obtained by centrifugation was washed with 2 mol / L HCl solution until neutral. The resulting neutral product was then poured into a gas washing bottle, deionized water was added, and the bottle was placed in an ultrasonic instrument for ultrasonic treatment for 1 h. At the same time, nitrogen gas was introduced for bubbling treatment. The gas flow rate was 9 m / s and the gas flow time was 1 h. Finally, after the bubbling treatment, the mixture was centrifuged again at 8000 r / min for 0.7 h, and the supernatant rich in monolayer MXene nanosheets was collected to obtain an MXene solution. This solution was then dispersed in 48 mL of deionized water to form a uniform MXene dispersion.
[0035] S2. Using an ultra-stretched acrylic film as an elastic substrate, apply 100% pre-stretch stress to the elastic substrate, spray the MXene dispersion obtained in S1 onto the upper part of the elastic substrate with a preset number of 1 layers, then spray 2 layers onto the middle part of the elastic substrate, and spray 3 layers onto the lower part of the elastic substrate. The spraying time for each layer is the same. Then release the 100% pre-stretch stress applied to the elastic substrate to obtain a gradient micro-wrinkled MXene film. S3. Assemble copper electrodes at both ends of the gradient micro-wrinkled MXene film of the preset thickness obtained in S2 using conductive silver paste. Dry and cure at 55°C for 1 hour to obtain a sensor with assembled electrodes. Then, drop-coat the polydimethylsiloxane solution onto the surface of the sensor with assembled electrodes and cure at 60°C for 4 hours to obtain the desired result. Figure 1 The MXene gradient fold strain sensor is shown.
[0036] The preparation method of the polydimethylsiloxane solution is as follows: polydimethylsiloxane is ultrasonically dispersed in n-hexane, wherein the mass ratio of n-hexane to polydimethylsiloxane is 10:1, and the ultrasonic dispersion time is 2.3 h.
[0037] The resistance change of the MXene gradient wrinkle strain sensor obtained in this embodiment was monitored in real time under different strains using a digital multimeter. The test results show that the strain range can reach 300%, and it exhibits extremely high strain factors in different strain ranges.
[0038] In summary, the gradient micro-folded structure provided by this invention generates high-density microcrack channels in the upper high-density folded region under low strain, effectively improving initial sensitivity; the lower low-density folded structure maintains a continuous conductive frame in the high strain stage, widening the working strain range. This gradient structure, through the graded release mechanism of strain energy, enables the sensor to maintain response stability and structural integrity in a wide strain range, significantly improving the sensor's sensitivity throughout the entire working range, especially under higher strain conditions, where the performance improvement is even more prominent.
[0039] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.
Claims
1. A method for fabricating an MXene gradient wrinkle strain sensor, characterized in that, Includes the following steps: S1. Multilayer MXene is prepared by etching, and then the multilayer MXene is ultrasonically peeled off and centrifuged to obtain an MXene solution, which is then dispersed in deionized water to form a uniform MXene dispersion. S2. Provide an elastic substrate, apply a pre-stretch stress to the elastic substrate, spray the MXene dispersion obtained in S1 onto different areas of the elastic substrate according to different preset number of layers, and then release the pre-stretch stress applied to the elastic substrate to obtain a gradient micro-wrinkled MXene film of preset thickness. S3. Assemble copper electrodes at both ends of the gradient micro-wrinkled MXene film of the preset thickness obtained in S2 using conductive silver paste, and dry and cure at 50~60℃ for 0.5~1.5h to obtain a sensor with assembled electrodes. Then encapsulate it with polydimethylsiloxane solution to obtain an MXene gradient wrinkled strain sensor.
2. The method according to claim 1, characterized in that, The etching method described in S1 is as follows: lithium fluoride and hydrochloric acid are added sequentially to a polytetrafluoroethylene-lined reactor and stirred for 15-20 minutes. Then, titanium aluminum carbide powder is added in small amounts several times. The mixture is stirred continuously for 40-45 hours in a sealed environment to carry out a chemical etching reaction. The temperature of the chemical etching reaction is 35-40°C, and the stirring rate is 500-600 r / min.
3. The method according to claim 2, characterized in that, The molar concentration of the hydrochloric acid is 9 mol / L, and the ratio of lithium fluoride, hydrochloric acid and titanium aluminum carbide is 6~8g:60~90mL:3~5g.
4. The method according to claim 2, characterized in that, The term "small quantity, multiple times" refers to 8-9 times within 25-30 minutes.
5. The method according to claim 1, characterized in that, The specific steps of ultrasonic stripping and centrifugal purification described in S1 are as follows: First, the multilayer MXene is centrifuged, and the precipitate obtained by centrifugation is washed until neutral. Then, the obtained neutral product is poured into a gas washing bottle, deionized water is added, and then it is placed in an ultrasonic instrument. While ultrasonic treatment is performed, inert gas is introduced for bubbling treatment. Finally, after the bubbling treatment is completed, it is centrifuged again, and the upper liquid is retained to obtain the MXene solution.
6. The method according to claim 5, characterized in that, The ultrasonic treatment time is 0.8~1.2h; the inert gas is nitrogen; in the bubbling treatment, the air flow rate is 8~10m / s and the air flow time is 0.8~1.5h; the centrifugation rate is 6000~8000r / min and the centrifugation time is 0.5~0.8h.
7. The method according to claim 1, characterized in that, The pre-tension stress mentioned in S2 is the stress required to be applied when the tension length reaches 100% of the initial length.
8. The method according to claim 1, characterized in that, The different regions mentioned in S2 include an upper part, a middle part, and a lower part. The upper part is sprayed with 1 preset layer, the middle part with 2 preset layers, and the lower part with 3 preset layers.
9. The method according to claim 1, characterized in that, The polydimethylsiloxane solution is prepared by ultrasonically dispersing polydimethylsiloxane in n-hexane, wherein the mass ratio of n-hexane to polydimethylsiloxane is 10:1, and the ultrasonic dispersion time is 2~2.5h. The specific encapsulation method is as follows: the polydimethylsiloxane solution is drop-coated onto the surface of the sensor with assembled electrodes, and cured at 55~60℃ for 4 hours.
10. The method according to claim 1, characterized in that, The elastic substrate is an ultra-stretched acrylic film.