Self-sensing morphing device

Abstract

The present application relates to the field of intelligent sensing and deformation control, and provides a self-sensing deformation device and a preparation method thereof, wherein the self-sensing deformation device is composed of a plurality of composite sensing material layers and deformation polymer layers which are alternately stacked, the top layer and the bottom layer of the self-sensing deformation device are both composite sensing material layers, at least one deformation polymer layer is arranged, and electrodes are arranged at both ends or the outer surface of the self-sensing composite sensing material layer; in the design, the graphene network functions as a resistance deformation driving circuit and a strain sensing circuit, after being connected with the electrodes, the strain detection capability with high sensitivity and wide detection range is realized while the deformation of the deformation material is stably driven, the self-sensing deformation control of the overall deformation device is realized, and the self-sensing deformation device can be applied to the fields of intelligent deformation machinery and flexible robots.

Description

Technical Field

[0001] This invention relates to the fields of electronic device technology, sensor technology, intelligent machinery and composite material technology, and specifically to a self-sensing deformation device. Background Technology

[0002] With the development of fields such as intelligent machinery and intelligent electronics, the demand for intelligent deformable devices is becoming increasingly prominent. Intelligent deformable devices require both excellent deformability and effective monitoring and feedback capabilities to facilitate closed-loop control during intelligent system integration.

[0003] Traditional methods for deformation and morphology monitoring typically require at least two separate circuit structures: one to drive the deformation of the material, and the other connected to sensors or a sensor network to monitor the deformation. For example, patent CN201610221899.9 uses a polyelectrolyte flexible curved surface plated electrode to form sensing and driving elements. Each sensing or driving unit requires separate circuit control, resulting in inaccurate measurement of deformation by the sensing element. Patent CN202011058609.6 uses micron-scale piezoelectric ceramics as sensing and driving elements, employing different microdevices and controlled by different circuit networks. Notably, the piezoelectric ceramics provided in this document can only function as either sensing or driving elements, not simultaneously. Patent CN 201721013852.X uses only a boron nitride / graphene / boron nitride three-layer nanofilm structure as the sensing element. This device has good deformation sensing performance but lacks deformation driving capability. The discrete sensing and driving circuit structures described above will lead to a superlinear increase in circuit design and wiring complexity when there are a large number of smart devices distributed over a large area. This will make manufacturing difficult and significantly reduce reliability. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a self-sensing deformation device that can both monitor deformation in real time and drive the deformation back to a predetermined shape. The deformation driving circuit also serves as a deformation sensing circuit, greatly reducing the number of leads, lowering installation difficulty, and avoiding problems such as circuit aging. At the same time, real-time monitoring and self-driving can reduce manual labor intensity and enable timely responses to minimize unnecessary losses.

[0005] The preparation scheme of the composite sensing material adopted by the present invention to achieve the above-mentioned objectives is as follows:

[0006] First, this application provides a self-sensing deformation device, which is composed of several composite sensing material layers and deformable polymer layers stacked alternately; the top and bottom layers of the self-sensing deformation device are both composite sensing material layers; the self-sensing deformation device assembly has at least one deformable polymer layer; electrodes are provided at both ends or on the outer surface of the self-sensing composite sensing material layer.

[0007] Preferably, the thickness of the composite sensing material layer is 1-2 mm, and the thickness of each composite sensing material layer can be the same or different.

[0008] Preferably, the thickness of the deformable polymer layer is 0.5-2 mm; the thickness of each deformable polymer layer can be the same or different.

[0009] Secondly, this application provides a method for fabricating the aforementioned self-sensing deformation device, the specific steps of which are as follows:

[0010] 1) The cleaned nickel foam (1-3 mm thick) was placed in a quartz tube with an ultimate vacuum better than 0.1 Pa. The vacuum was then reduced to 0.1 Pa. The temperature was controlled throughout the growth process using a horizontal tube furnace system (OTL 1200, Nanjing Boyuntong). The temperature was raised to 1000℃ in an H2 gas flow (11 sccm) environment and annealed for 30 minutes. Then, CH4 (33 sccm) was continuously introduced for 30 minutes. After the CH4 supply was stopped, the tube furnace was allowed to cool naturally to room temperature while maintaining a hydrogen environment to obtain graphene three-dimensional foam. At this point, the graphene three-dimensional foam, with more than 90% single-atom-layer graphene deposited by chemical vapor deposition, had a sheet resistance of 1-100 ohms and was ready for use.

[0011] 2) Prepare a mixed solution of polydimethylsiloxane (PDMS) and n-heptane in a mass ratio of 11:20. Immerse the graphene three-dimensional foam prepared in step 1) into the mixed solution for 10 seconds. Then take it out and fix it on a spin coater and spin dry at 2000 rpm for 40 seconds. After that, cure at 90°C for 3 hours to obtain a polydimethylsiloxane-graphene foam-nickel composite material.

[0012] Adding heptane as a solvent in this step can significantly reduce the viscosity of the PDMS prepolymer, which is beneficial for improving the porosity of the composite material. However, due to factors such as surface tension, the PDMS prepolymer will aggregate into clusters after the solvent evaporates, affecting the uniformity of the material. Subsequent high-speed rotation can remove the aggregated solution, improving uniformity and increasing porosity.

[0013] The polydimethylsiloxane-graphene foam-nickel composite material obtained in step 2) was rapidly impregnated with anhydrous ethanol and then removed. The metallic nickel was etched away with 0.5 mol / L FeCl3 solution. The entire process was carried out at room temperature. The etching was completed when the graphene floated on the surface of the solution (about 24 hours). Then, it was freeze-dried (preferably at -10°C) to obtain the polydimethylsiloxane-graphene foam layer for later use.

[0014] The hydrophobicity of conventional polydimethylsiloxane and graphene can lead to excessively long etching times, affecting the integrity of the sample; however, this application utilizes the aforementioned ethanol wetting method based on the hydrophobicity of the material to reduce etching time.

[0015] Epoxy resin E51, polysulfide rubber, aminoethyl piperazine, and n-butyl glycidyl ether were mixed and stirred in a ratio of 100:35:24:20 to obtain a deformable polymer precursor. Under a vacuum environment of less than 100 Pa, the polydimethylsiloxane-graphene foam layer obtained in step 3) was laid flat in a quartz mold pre-coated with a polyester release agent (Meishu 606 release agent). The liquid deformable polymer precursor obtained in step 4) was then slowly poured into the mold to fully fill the polydimethylsiloxane-graphene foam from step 3). The mixture was allowed to stand for 3 minutes and then cured at 90°C for 120 minutes to obtain a composite sensing material layer.

[0016] Repeat steps 1)-5) to obtain several composite sensing material layers;

[0017] The deformable polymer precursor obtained in step 4) is bonded between several composite sensing material layers, and the deformable polymer precursor is cured to form a shape memory polymer layer.

[0018] Electrodes are fabricated at both ends or on the outer surface of each composite sensing material layer. The electrode width is not less than 0.5 mm. The electrodes can be fabricated by silver paste coating, metal sputtering, or vapor deposition. Preferably, the electrode length is consistent with the width of the sensing material layer. The electrode width refers to the distance the electrode extends into the sensing material layer.

[0019] This application addresses the limitation of single-layer or multi-layer graphene in low-strain detection by employing a composite sensing material of single-layer graphene foam covered with PDMS, thereby achieving low-strain detection. The self-sensing deformation device of this invention has a simple structure, is easy to implement, and truly achieves integration, effectively reducing manufacturing costs. It can achieve self-detection and self-drive with high measurement accuracy. The voltage can be adjusted according to the sensing signal to supplement and rapidly drive the device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the self-sensing deformation device structure in Embodiment 1 of the present invention;

[0021] Figure 2This is a Raman spectral analysis result of graphene atomic layers in Example 1 of the present invention.

[0022] Figure 3 This is a schematic diagram of the stacked self-sensing deformation device structure according to Embodiment 1 of the present invention;

[0023] Figure 4 This is a diagram illustrating the deformation process of the stacked self-sensing deformation device according to Embodiment 1 of the present invention.

[0024] Figure 5 This is a graph showing the relationship between relative resistance, recovery speed, and time during the deformation process of the stacked self-sensing deformation device in Embodiment 1 of the present invention.

[0025] Figure 6 This is a schematic diagram of the stacked self-sensing deformation device structure of Embodiment 4 of the present invention;

[0026] Figure 7 This is a schematic diagram of the self-sensing deformation device structure in Example 6;

[0027] In the figure, 1-composite sensing material layer; 2-deformable polymer layer; 3-composite sensing material layer; 4-electrode. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments are merely for explanation and illustration of the present invention, and the present invention is not limited to these embodiments.

[0029] Sources of equipment and materials involved in the embodiments:

[0030] Nickel foil (0.1 mm thick) was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0031] Epoxy resin E51 was purchased from Nantong Xingchen Synthetic Materials Co., Ltd.

[0032] n-Butyl glycidyl ether was purchased from Changzhou Runxiang Co., Ltd.

[0033] The glass plate mold was purchased from Fangyuan Glass Technology Co., Ltd. Example 1

[0034] 1. Fabrication of a self-sensing deformation device, the specific fabrication steps are as follows:

[0035] 1) Pretreatment of nickel foil.

[0036] Cut the nickel foil into 80 mm × 20 mm pieces, immerse it in a 1:1 mixture of anhydrous ethanol and acetone for 5 minutes, then ultrasonically clean it at 20 kHz for 30 minutes, polish it in 85% analytical grade phosphoric acid for 4 minutes at a polishing current of 0.35 A, then rinse it repeatedly in deionized water three times, and finally dry it with nitrogen gas for later use.

[0037] Single-atom-layer graphene was prepared by chemical vapor deposition.

[0038] In this embodiment, graphene was grown on a treated nickel foil using chemical vapor deposition (CVD). A 1 mm thick nickel foam was placed inside a quartz tube with an ultimate vacuum better than 0.1 Pa. The CVD produced a three-dimensional graphene foam with over 90% single-atom-layer graphene. Typical conditions were 1000 °C, 11 sccm H₂, 33 sccm CH₄, and a growth time of 30 minutes. Raman spectroscopy confirmed that the graphene atoms were single-layered. The test results are as follows: Figure 2 As shown.

[0039] 3) Immerse the graphene three-dimensional foam obtained in step 2) into a mixed solution of PDMS and n-heptane in a mass ratio of 11:20 for 10 seconds, remove it and spin dry in a gyroscope at 2000 rpm for 40 seconds, and then cure at 90°C for 120 minutes.

[0040] 4) Etching

[0041] The graphene foam obtained in step 3) was rapidly impregnated with anhydrous ethanol and then removed. It was then etched in a 0.5 mol / L FeCl3 solution for 24 hours to remove metallic nickel. After that, it was dried in a freeze dryer at -10°C for 24 hours to obtain a polydimethylsiloxane-graphene foam layer for later use.

[0042] 5) Mix epoxy resin E51, polysulfide rubber, aminoethyl piperazine and n-butyl glycidyl ether in a mass ratio of 100:35:24:20 and stir for 3 minutes to obtain a liquid deformable polymer precursor for later use.

[0043] 6) Pour the liquid shape memory polymer precursor prepared in step 5) into a quartz mold pre-coated with a polyester release agent (Meishu 606 release agent). The mold size is 80 mm × 20 mm × 2 mm. Then, flatly lay the polydimethylsiloxane-graphene foam layer obtained in step 4) in the quartz mold. Then, slowly pour the liquid deformable polymer precursor obtained in step 5) into the mold to fully fill the polydimethylsiloxane-graphene foam of step 4).

[0044] 7) Curing

[0045] Place the entire assembly from step 6) in an oven and cure at 90°C for 3 hours before demolding to obtain the composite sensing material layer.

[0046] 8) Electrode terminals are fabricated at both ends of the obtained graphene foam / deformable polymer composite material. The electrodes are fabricated using a silver paste coating method commonly used in the art, extending to the surface of the composite sensing material layer. The encapsulation method used in this step employs conventional methods in the art, such as the encapsulation method disclosed in Chinese Patent CN 108376838A, which can achieve the purpose of this encapsulation step.

[0047] Repeat steps 5) and 7) to obtain the deformed polymer layer.

[0048] 10) Assemble the composite sensing material layer and the deformable polymer layer according to the schematic diagram. Figure 1 By bonding the deformable polymer precursor, a self-sensing deformable device is obtained.

[0049] A schematic diagram of the self-sensing deformation device structure prepared in this embodiment is shown below. Figure 1 As shown in the top two layers, the overall structure of the self-sensing deformation device is composed of a multi-layer structure, consisting of a composite sensing material layer (1) and a deformable polymer layer (2) stacked together, with electrode terminals (4) provided at both ends of the composite sensing material layers (1) and (3).

[0050] In this embodiment, the thickness of the composite sensing material layer (1) is 1 mm; the density of the composite sensing material layer is 1.198 g·cm³. -3 The density of the graphene foam is 1.56 × 10⁻³ g·cm³. -3 Therefore, the graphene doping concentration can be calculated to be 0.13 wt.%, and the mass ratio of liquid shape memory polymer precursor to graphene foam in this embodiment is 767:1.

[0051] In this embodiment, the thickness of the deformable polymer layer (2) is 2 mm.

[0052] Self-sensing deformation test

[0053] The above sample was softened at 85°C and then subjected to a load, pre-deformed into a U-shape (radius of curvature 8 mm, bending angle 120°). After cooling to room temperature, the load was removed, and the bending angle of the middle part was measured. The shape fixation rate was calculated to be 99% by comparing it with the pre-set angle. An electric-driven shape recovery test was performed at 20 V, and the deformation time and final shape recovery rate were recorded. This electric-driven test method is a conventional method in the field and can be found in the published literature "Structural design of flexible Au electrode to enable shape memory polymer for electricalactuation. Smart Materials and Structures, 2015, 24, 045015".

[0054] Actual product image Figure 3 As shown, the results indicate that the sample basically completed its deformation in 101s, with a final shape recovery rate of more than 95%. This device integrates sensing and driving, reducing input and output circuitry and making it simpler.

[0055] like Figure 4 This demonstrates that this embodiment exhibits excellent electrically driven shape recovery performance and a high shape recovery rate. In this process, the monitoring results obtained by measuring the relative resistance change are almost identical to the observed results, indicating that the self-sensing deformation device can sense and detect its own deformation. Figure 5 As shown. Example 2

[0056] The difference between this embodiment and Embodiment 1 is that the nickel foil is cut to a size of 145 mm × 20 mm, and a glass mold with a size of 145 mm × 20 mm × 2 mm is used to prepare the deformable polymer. The composite sensing material layer and the deformable polymer layer prepared in this embodiment both have an area of ​​145 mm × 20 mm, and all other steps are the same as in Embodiment 1.

[0057] The results showed that the sample basically completed the deformation in 132s, and the final shape recovery rate was greater than 95%, which indicates that this embodiment has good electric drive shape recovery performance and high shape recovery rate. Example 3

[0058] The difference between this embodiment and Embodiment 1 is that a glass mold with dimensions of 80 mm × 20 mm × 1 mm is used to prepare the deformable polymer, while all other steps are the same as in Embodiment 1.

[0059] The results showed that the sample basically completed the deformation in 63s, and the final shape recovery rate was greater than 95%, which indicates that this embodiment has good electric drive shape recovery performance and high shape recovery rate. Example 4

[0060] The difference between this embodiment and Embodiment 1 is that the two electrode terminals are fabricated using a gold vapor deposition method, with a gold layer thickness of 50 nanometers.

[0061] The results showed that the sample basically completed its deformation in 111 seconds, with a final shape recovery rate greater than 95%. This indicates that this embodiment has good electrically driven shape recovery performance and a high shape recovery rate. The electrode in this embodiment was obtained by gold vapor deposition, which has a slightly larger contact resistance than the electrode obtained by silver paste coating in Example 1, thus resulting in a slightly longer response time than in Example 1. Example 5

[0062] The difference between this embodiment and Embodiment 3 is the fabrication of a three-layer self-sensing deformation device. The specific steps are as follows:

[0063] 1) Repeat the composite sensing material preparation process in Example 3 twice to prepare two composite sensing material layers, and lead the electrodes from both ends of the upper surface to the cross sections at both ends of the material;

[0064] 2) Spray the Meishu 606 release agent onto the surface of an 80 mm × 20 mm × 1.5 mm glass mold, and then bond the composite sensing material sample and the deformable polymer in sequence with a liquid deformable polymer precursor (i.e., using the polymer precursor as a binder) and place them into the mold. After two bonding processes, the overall thickness increases by 0.1 mm.

[0065] 3) Place the above assembly in an oven and cure at 75°C for 3 hours before demolding to obtain a three-layer self-sensing deformation device sample;

[0066] The deformable material prepared in this embodiment has overall dimensions of 80 mm × 20 mm × 3.1 mm, and the structural schematic diagram is shown below. Figure 6 The other steps are the same as in Example 1.

[0067] The results showed that the sample basically completed deformation in 51 seconds, with a final shape recovery rate of over 95%. This embodiment adds a composite sensing material layer compared to Example 3. The composite sensing material layer on the outside can detect strain on both sides, reducing errors and allowing the deformed polymer material to heat up more quickly from both sides simultaneously. This embodiment exhibits excellent electrically driven shape recovery performance and a high shape recovery rate. Example 6

[0068] The difference between this embodiment and Embodiment 5 is the fabrication of a multi-layered self-sensing deformation device. The specific steps are as follows:

[0069] Repeat the composite sensing material preparation process in Example 3 three times to prepare three composite sensing material layers, and extend the electrodes from both ends of the upper surface to the cross sections at both ends of the material.

[0070] Repeat the deformation polymer layer preparation process in Example 3 twice to prepare two deformation polymer layers;

[0071] 3) Spray the Meishu 606 release agent onto the surface of an 80 mm × 20 mm × 1.5 mm glass mold. Then, bond the composite sensing material sample and the deformable polymer in sequence into the mold using a liquid deformable polymer precursor. After four bonding processes, the overall thickness increases by 0.2 mm.

[0072] 3) Place the above assembly in an oven and cure at 75°C for 3 hours before demolding to obtain a multi-layered self-sensing deformation device sample;

[0073] The deformable material prepared in this embodiment has overall dimensions of 80 mm × 20 mm × 5.2 mm, and the structural schematic diagram is shown below. Figure 7 The other steps are the same as in Example 1.

[0074] The results showed that the sample basically completed its deformation within 40 seconds, with a final shape recovery rate greater than 95%. This embodiment has more stacked structures than Embodiment 5, resulting in less heat loss and more accurate device deformation measurement. This embodiment exhibits excellent electrically driven shape recovery performance and a high shape recovery rate.

[0075] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-aware morphing device, characterized by, The self-sensing deformation device is composed of several composite sensing material layers and deformation polymer layers which are alternately stacked; The top layer and the bottom layer of the self-sensing deformation device are both composite sensing material layers; the self-sensing deformation device is provided with at least one deformation polymer layer; The two ends or the outer surface of the composite sensing material layer are provided with electrodes; The composite sensing material layer is prepared by the following method: 1) Put the foamed nickel into a quartz tube, anneal at 1000 DEG C for 30 minutes under a vacuum degree of 0.1 Pa and H2 atmosphere, then continuously input CH4 for 30 minutes; naturally cool to room temperature to obtain a graphene three-dimensional foam, which is ready for use; 2) Prepare a mixed solution by mixing polydimethylsiloxane and n-heptane according to a mass ratio of 11:20, immerse the graphene three-dimensional foam prepared in step 1) in the mixed solution for 10 seconds, then dry, solidify at 90 DEG C for 3 hours to obtain a polydimethylsiloxane-graphene foam-nickel composite material; 3) Immerse the polydimethylsiloxane-graphene foam-nickel composite material obtained in step 2) in anhydrous ethanol, take it out, then remove the metal nickel, and freeze-dry to obtain a polydimethylsiloxane-graphene foam layer, which is ready for use; 4) Mix epoxy resin E51, polysulfide rubber, aminoethyl piperazine and n-butyl glycidyl ether according to a mass ratio of 100:35:24:20 to obtain a liquid deformation polymer precursor, which is ready for use; 5) Under an environment with a vacuum degree less than 100 Pa, place the polydimethylsiloxane-graphene foam layer obtained in step 3) in a mold which is pre-coated with a polyester release agent, then pour the liquid deformation polymer precursor obtained in step 4) into the mold, stand still, then heat and solidify at 90 DEG C for 120 minutes to obtain a composite sensing material layer; The deformation polymer layer is obtained by mixing epoxy resin E51, polysulfide rubber, aminoethyl piperazine and n-butyl glycidyl ether according to a mass ratio of 100:35:24:20 and then solidifying.

2. The self-aware morphing device of claim 1, wherein, The thickness of the composite sensing material layer is 1-2 mm.

3. The self-aware morphing device of claim 1, wherein, The thickness of the deformation polymer layer is 0.5-2 mm.

4. The method of claim 1-3, wherein the self-sensing deformable device is prepared by the steps of: The specific steps are as follows: 1) Put the foamed nickel into a quartz tube, anneal at 1000 DEG C for 30 minutes under a vacuum degree of 0.1 Pa and H2 atmosphere, then continuously input CH4 for 30 minutes; naturally cool to room temperature to obtain a graphene three-dimensional foam, which is ready for use; 2) Prepare a mixed solution by mixing polydimethylsiloxane and n-heptane according to a mass ratio of 11:20, immerse the graphene three-dimensional foam prepared in step 1) in the mixed solution for 10 seconds, then dry, solidify at 90 DEG C for 3 hours to obtain a polydimethylsiloxane-graphene foam-nickel composite material; 3) Immerse the polydimethylsiloxane-graphene foam-nickel composite material obtained in step 2) in anhydrous ethanol, take it out, then remove the metal nickel, and freeze-dry to obtain a polydimethylsiloxane-graphene foam layer, which is ready for use; 4) Mix epoxy resin E51, polysulfide rubber, aminoethyl piperazine and n-butyl glycidyl ether according to a mass ratio of 100:35:24:20 to obtain a liquid deformation polymer precursor, which is ready for use; 5) The polydimethylsiloxane-graphene foam layer obtained in step 3) is laid flat in a mold coated with a polyester-based mold release agent, and the liquid deformed polymer precursor obtained in step 4) is poured into the mold, left to stand, and then heated and cured at 90°C for 120 minutes to obtain a composite sensing material layer, which is ready for use; 6) Steps 1) - 5) are repeated to obtain several composite sensing material layers; 7) The liquid deformed polymer precursor obtained in step 4) is used to bond the several composite sensing material layers, and the deformed polymer precursor is cured to form a deformed polymer layer; 8) Electrodes are prepared on both ends or the outer surface of each composite sensing material layer to obtain the self-sensing deformation device.

5. The method of claim 4, wherein the self-sensing, deformable device is prepared by, The thickness of the foam nickel in step 1) is 1-3 mm.

6. The method of claim 4, wherein the self-sensing, deformable device is prepared by, The removal of the metal nickel in step 3) refers to etching and removing the metal nickel with FeCl3 solution.

7. The method of claim 4, wherein the self-sensing, deformable device is prepared by, The freezing in step 3) refers to freezing at -10°C.

8. The method of claim 4, wherein the self-sensing, deformable device is prepared by, The preparation of the electrodes in step 8) refers to coating with silver paste, metal sputtering, or evaporation to prepare electrodes on both ends or the outer surface of the composite sensing material layer.

9. The method of claim 8, wherein the self-sensing, deformable device is prepared by, The length of the electrodes in step 8) is the same as the width of the composite sensing material layer.

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