Flexible self-driven optical-electric coupling pressure visualization device and preparation method thereof

Abstract

The invention discloses a flexible self-driven optical-electric coupling pressure visualization device and a preparation method thereof, and belongs to the technical field of flexible photoelectric sensors. The device comprises a substrate, an ion storage layer, a VHB packaging layer, a dual-mode electrochromic layer and a liquid metal layer, the ion storage layer and the VHB packaging layer are sequentially arranged between the substrates from top to bottom, the dual-mode electrochromic layer, the liquid metal layer and the VHB packaging layer are of an annular structure, a cavity is formed in the middle of the VHB packaging layer, the raw materials of the substrates are polyethylene glycol terephthalate, and the raw materials of the substrates are polyethylene glycol terephthalate. The raw material of the ion storage layer is mixed gel of polyacrylamide and lithium chloride, the raw material of the dual-mode electrochromic layer is a mixture of Eu < 3 + >-doped WO3 and silver nanowires, and the raw material of the liquid metal layer is indium-based alloy. According to the invention, the structure compactness of the device can be effectively improved, the structure of the device is simplified, the pressure change visualization can be realized under the passive self-driving condition, the energy consumption is low, the use is convenient, and the applicability is excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible optoelectronic sensors, and relates to a flexible self-powered opto-electric coupled pressure visualization device and a preparation method thereof. Background Art

[0002] Electrochromic technology has shown important application prospects in smart windows, displays, and wearable devices due to its ability to electrochemically regulate the optical properties of materials. However, traditional electrochromic devices generally rely on external power sources for driving, resulting in high energy consumption. Moreover, in order to avoid messy wire scattering, rigid ITO substrates are usually required, which limits the flexibility of electrochromic-related devices or apparatuses and makes it difficult to meet the requirements of next-generation flexible electronic devices for light weight, low power consumption, and wearing comfort. In addition, existing electrochromic-related devices or apparatuses adopt rigid encapsulation structures, which are prone to interface peeling or conductive performance attenuation under repeated deformation, restricting their applications in the field of dynamic pressure sensing.

[0003] In the field of pressure visualization, current mainstream technologies rely on the integration of high-density sensor arrays and independent display modules. For example, capacitive or piezoresistive sensors need to cooperate with complex signal processing circuits and pixelated display screens, resulting in large device volume, high cost, and difficulty in achieving real-time and intuitive feedback of pressure distribution. In addition, these systems usually require continuous power supply from an external power source, further restricting their applications in portable or self-powered scenarios.

[0004] Therefore, it is necessary to provide a flexible self-powered opto-electric coupled pressure visualization device and a preparation method thereof to achieve self-driving of the device, improve the structural compactness of the device, and simultaneously display the pressure distribution intuitively, thereby promoting technological progress in the fields of wearable electronics, human-computer interaction, etc. Summary of the Invention

[0005] In order to overcome the problems in the background art, the present invention combines a pressure-sensitive ion migration mechanism with a dual-mode electrochromic luminescent material to achieve intuitive display of pressure distribution without an external power source for the device, improve the structural compactness of the device, endow the device with more excellent performance, and expand the applicable scenarios of the device.

[0006] To achieve the above object, the present invention is realized by the following technical solutions: On the one hand, the present invention provides a flexible self-driven opto-electric coupled pressure visualization device, which comprises a substrate 1, an ion storage layer 2, a VHB encapsulation layer 3, a dual-mode electrochromic layer 5, and a liquid metal layer 6. The ion storage layer 2, the VHB encapsulation layer 3, the dual-mode electrochromic layer 5, and the liquid metal layer 6 are sequentially arranged from top to bottom between the substrates 1. The VHB encapsulation layer 3 has an annular structure, and a cavity 4 is formed in the middle of the VHB encapsulation layer 3. The thickness of the substrate 1 is 200 - 300 μm, the thickness of the ion storage layer 2 is 1 - 2 mm, the thickness of the VHB encapsulation layer 3 is 2 - 3 mm, the thickness of the dual-mode electrochromic layer 5 is 20 - 40 μm, and the thickness of the liquid metal layer 6 is 50 - 100 μm.

[0007] The raw material of the substrate 1 is polyethylene terephthalate, the raw material of the ion storage layer 2 is a mixed gel of polyacrylamide and lithium chloride, and the raw material of the dual-mode electrochromic layer 5 is a mixture of WO3 doped with Eu 3+ and silver nanowires, and the raw material of the liquid metal layer 6 is an indium-based alloy.

[0008] On the other hand, the present invention provides a preparation method of the above device, which comprises the following steps: (1) Bond the mixed gel of polyacrylamide and lithium chloride with the substrate (1) by physical adhesion to form the ion storage layer 2. The substrate 1 is a PET substrate, which can be directly purchased commercially. The mixed gel of polyacrylamide and lithium chloride has high viscosity itself and can be directly bonded to the PET substrate.

[0009] (2) Bond the VHB encapsulation layer 3 with the ion storage layer 2 by physical pasting. VHB is a double-sided tape produced by 3M Company. Thus, the VHB packaging layer 3 can be directly pasted and combined with the ion storage layer 2.

[0010] (3) By hot rolling, in the heating state, roll the liquid metal onto the substrate 1 to form the liquid metal layer 6. Then, while maintaining the heating state, roll the mixture film of WO3 doped with Eu 3+ and silver nanowires onto the liquid metal layer 6 to form the dual-mode electrochromic layer 5. In the heating state, the liquid metal has fluidity, which is convenient for rolling it onto the substrate 1. While maintaining the heating state, the liquid metal still has the characteristics of a liquid, which is convenient for rolling the mixture film of WO3 doped with Eu 3+ and silver nanowires onto the liquid metal layer 6. After completion, cool it, and the liquid metal layer 6 solidifies and forms a good combination with the substrate 1 and the dual-mode electrochromic layer 5.

[0011] (4) After the liquid metal layer 6 in step (3) is cooled, bond the dual-mode electrochromic layer 5 with the VHB encapsulation layer 3 by physical pasting.

[0012] Preferably, in the step (3), the heating temperature is 75 - 85°C.

[0013] Preferably, the preparation process of the raw materials of the ion storage layer (2) includes the following steps: S1: Dissolve 2.17 M acrylamide monomer powder and 5 M lithium chloride in water to obtain a mixture solution; S2: Add a crosslinking agent N,N'-methylenebisacrylamide and an initiator ammonium persulfate to the solution obtained in the step S1, and then add an accelerator tetramethylethylenediamine; S3: Load the solution of the step S2 into a mold, and carry out heating and curing to obtain a mixed gel of polyacrylamide and lithium chloride.

[0014] Preferably, in the step S2, the addition amount of the crosslinking agent is 0.06% of the mass of the acrylamide monomer, the addition amount of the initiator is 0.16% of the mass of the acrylamide monomer, and the addition amount of the accelerator is 0.25% of the mass of the acrylamide monomer.

[0015] Preferably, in the step S3, the heating and curing temperature is 60°C, and the heating and curing time is 30 min.

[0016] Preferably, the preparation process of the mixture film of Eu 3+ doped WO3 and silver nanowires includes the following steps: Q1: Add Eu2O3 to hot nitric acid, and after the reaction is completed, obtain gel-like Eu(NO3)3; Q2: Dissolve the Eu(NO3)3 obtained in the step Q1 in ethanol, dissolve ammonium metatungstate hydrate in water to obtain a Eu(NO3)3 solution and an ammonium metatungstate hydrate solution, and stir and mix the Eu(NO3)3 solution and the ammonium metatungstate hydrate solution. After the reaction, obtain a transparent Eu 3+ doped WO3 solution, and the amount of substance of the Eu element is 5% - 10% of the amount of substance of WO3. Eu(NO3)3 and ammonium metatungstate hydrate only need to be completely dissolved in ethanol and water respectively. The concentrations of the Eu(NO3)3 solution and the ammonium metatungstate hydrate solution hardly affect the performance of the Eu 3+ doped WO3 and silver nanowire mixture film.

[0017] Q3: Drop the Eu 3+ doped WO3 solution obtained in the step Q2 on a glass plate, and then carry out sintering to obtain Eu 3+ doped WO3 powder.

[0018] Q4: The Eu 3+The doped WO3 powder and silver nanowires are added to isopropyl alcohol and stirred to form a suspension. After that, the suspension is filtered by suction. After suction filtration, the solid substance remains on the filter paper to form a thin film. The thin film is dried to obtain the doped Eu 3+ WO3 and silver nanowire mixture thin film WO3@Eu 3+ / Ag NWs. At this time, the doped Eu 3+ WO3 and silver nanowire mixture thin film is adhered to the filter paper. Therefore, after rolling the doped Eu 3+ WO3 and silver nanowire mixture thin film onto the liquid metal layer 6, the filter paper needs to be peeled off.

[0019] Preferably, in the step Q1, the temperature of the hot nitric acid is 170 - 190 °C.

[0020] Preferably, in the step Q3, the sintering temperature is 450 °C and the sintering time is 5 h.

[0021] Preferably, in the step Q4, the mass of the Eu 3+ doped WO3 powder and silver nanowires is Eu 3+ doped WO3 powder : silver nanowires = 10 : 1, the drying temperature is 60 °C, and the drying time is 2 h.

[0022] When the device of the present invention is under pressure, the substrate and the ion storage layer on the top layer of the device will deform and bend downward, thereby squeezing out the air in the cavity. The ion storage layer contacts the dual-mode electrochromic layer. At this time, Li + in the ion storage layer is embedded into the dual-mode electrochromic layer through interface diffusion. The dual-mode electrochromic layer contains WO3, and the embedding of Li + causes a change in the valence state of W (W 6+ →W 5+ ), and further changes the electronic energy band structure of WO3, resulting in a change in the light absorption characteristics of WO3, so that the dual-mode electrochromic layer produces a color change, realizing pressure visualization. At the same time, In in the indium-based alloy has a relatively low standard potential (E°(In 3+ / In)= -0.34 V), and is preferentially oxidized to release electrons (In → In 3+ + 3e⁻), driving Li + to be embedded into WO3 (Li + + e - + WO3 → LiWO3), thereby realizing the self-driving of the device and responding to pressure without an external power source.

[0023] The beneficial effects of the present invention: 1. In the present invention, a VHB encapsulation layer with a cavity formed therein is provided between the dual-mode electrochromic layer and the ion storage layer. The air contained in the cavity is used to isolate the ion storage layer and the dual-mode electrochromic layer. On the one hand, the amount of materials required for device preparation is reduced. On the other hand, since gas has no physical structure and is hardly affected by device deformation, it will not be damaged due to repeated deformation during long-term use of the device, which helps to reduce the use cost of the device.

[0024] 2. When the ion storage layer contacts the dual-mode electrochromic layer in the present invention, it is driven by a liquid metal layer, so that external power supply is not required for driving, effectively improving the structural compactness of the device and simplifying the device structure. At the same time, as the pressure changes, the contact area between the ion storage layer and the dual-mode electrochromic layer will change, and the color of the dual-mode electrochromic layer will change, thereby visually displaying the pressure change without other dedicated display devices, further simplifying the device structure.

[0025] 3. In the present invention, by doping Eu 3+ , the dual-mode electrochromic layer can be photoexcited to generate light in other wavelength bands with lower energy, thereby providing a backlight effect for the dual-mode electrochromic layer and enhancing the contrast of pressure-induced color changes. Even in a relatively dark environment, the pressure change response can be observed more clearly.

[0026] 4. In the present invention, a denser structure is formed in the LiCl-PAAm gel prepared by a heat-crosslinking method. The PAAm-LiCl gel has excellent electrical conductivity, compressive resistance and flexibility.

[0027] 5. In the present invention, by adding Ag NWs to the dual-mode electrochromic layer, WO3@Eu 3+ are connected together to form an island-bridge structure, which is beneficial to the film formation of the mixture of WO3 and silver nanowires doped with Eu 3+ , and at the same time is beneficial to enhancing the device stability.

[0028] 6. The device of the present invention has a simple structure, high structural compactness, good flexibility for each layer, and good flexibility for the whole device. It does not require external power supply for driving, has low energy consumption during use, is easy to use, and has excellent applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of the device of the present invention; Figure 2 is the stress-strain curve of the LiCl-PAAm gel sample of the present invention; Figure 3 is the transmittance curve of the LiCl-PAAm gel sample of the present invention; Figure 4Fourier infrared spectrogram of the LiCl-PAAm gel sample of the present invention; Figure 5 XRD patterns of the WO3@Eu samples of Examples 1-3 and Comparative Example 1 of the present invention; 3+ of the present invention; Figure 6 Diffuse reflectance spectra comparison diagrams of the dual-mode electrochromic layer before and after color change of Examples 1-3 and Comparative Example 1 of the present invention; Figure 7 Diffuse reflectance spectra comparison of the dual-mode electrochromic layer before and after color change of Examples 1-3 and Comparative Example 1 of the present invention; Figure 8 Photoluminescence spectra of the dual-mode electrochromic layer before and after color change of Examples 1-3 and Comparative Example 1 of the present invention; Figure 9 Raman spectra of the dual-mode electrochromic layer before and after color change of Examples 1-3 and Comparative Example 1 of the present invention; Figure 10 X-ray photoelectron spectroscopy diagrams of the dual-mode electrochromic layer before color change of Examples 1-3 and Comparative Example 1 of the present invention; Figure 11 X-ray photoelectron spectroscopy diagrams of the dual-mode electrochromic layer after color change of Examples 1-3 and Comparative Example 1 of the present invention; Figure 12 X-ray photoelectron spectroscopy diagrams of indium element on the surface of the indium-based alloy used in the examples of the present invention; Figure 13 X-ray photoelectron spectroscopy diagrams of tin element on the surface of the indium-based alloy used in the examples of the present invention; Figure 14 X-ray photoelectron spectroscopy diagrams of bismuth element on the surface of the indium-based alloy used in the examples of the present invention; Figure 15 Tensile-relative resistance curve diagrams of the indium-based alloy used in the examples of the present invention; Figure 16 Diffuse reflectance spectra of the device prepared in Example 1 of the present invention under different pressures; Figure 17 Pressure-reflection mapping curve diagrams of the device prepared in Example 1 of the present invention under 475 nm light illumination; Figure 18 Change mapping diagrams of the reflectivity of the device under different pressures under the condition of 475 nm.

[0030] In the figure, 1 - substrate, 2 - ion storage layer, 3 - VHB encapsulation layer, 4 - cavity, 5 - dual-mode electrochromic layer, 6 - liquid metal layer. Detailed implementation manners

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0032] In the embodiments and comparative examples of the present invention, chemical reagents not specifically described were all used for experiments with commercially available analytical pure reagents.

[0033] Example 1 In this example, a flexible self-driven opto-electric coupling pressure visualization device was prepared by the following method: (1) 2.17 M acrylamide monomer powder and 5 M aluminum chloride were dissolved in water to obtain a mixture solution.

[0034] (2) A cross-linking agent N,N'-methylenebisacrylamide and an initiator ammonium persulfate were added to the solution, and then a promoter tetramethylethylenediamine was added. The addition amount of the cross-linking agent was 0.06% of the mass of the acrylamide monomer, the addition amount of the initiator was 0.16% of the mass of the acrylamide monomer, and the addition amount of the promoter was 0.25% of the mass of the acrylamide monomer; (3) The solution of step (2) was loaded into a mold and heated and cured at 60 °C for 30 min to obtain a mixed gel of polyacrylamide and lithium chloride.

[0035] (4) Eu2O3 was added to hot nitric acid at 180 °C, and a gel-like Eu(NO3)3 was obtained by reaction. Since Eu(NO3)3 is gel-like, it is convenient to take out Eu(NO3)3.

[0036] (5) The Eu(NO3)3 obtained in step (4) was dissolved in ethanol, ammonium metatungstate hydrate was dissolved in water, and the Eu(NO3)3 solution and ammonium metatungstate hydrate solution were stirred and mixed (after mixing, the amount of substance of Eu element in the liquid was 7.5% of the amount of substance of WO3). After reaction, a transparent Eu 3+ doped WO3 solution was obtained.

[0037] (6) The Eu 3+ doped WO3 solution obtained in step (5) was dropped on a glass plate and then sintered at 450 °C for 5 h to obtain Eu 3+ doped WO3 powder.

[0038] (7) The Eu 3+ doped WO3 powder and silver nanowires were added to isopropanol according to a mass ratio of 10:1 and stirred and mixed to obtain a suspension. Then, the suspension was filtered by suction. After suction filtration, the solid substance remained on the filter paper to form a thin film, which was dried at 60 °C for 2 h to obtain a thin film of a mixture of Eu 3+ doped WO3 and silver nanowires.

[0039] (8) The mixed gel of polyacrylamide and lithium chloride was adhered to a substrate 1 by physical adhesion to form an ion storage layer 2.

[0040] (9) Bond the VHB encapsulation layer 3 and the ion storage layer 2 by physical pasting.

[0041] (10) At 80 °C, roll the liquid metal onto the substrate 1 to form the liquid metal layer 6. Then, while maintaining the heating state, roll the mixture film of Eu-doped WO3 and silver nanowires onto the liquid metal layer 6 to form the dual-mode electrochromic layer 5. 3+ onto the liquid metal layer 6 to form a dual-mode electrochromic layer 5.

[0042] (11) After the liquid metal layer 6 in step (3) cools down, bond the dual-mode electrochromic layer 5 and the VHB encapsulation layer 3 by physical pasting. Since the substrate 1, the ion storage layer 2 and the VHB sub-packaging layer 3 have been bonded before, and the substrate 1 and the liquid metal layer 6, the dual-mode electrochromic layer 5 have also been combined. After bonding the dual-mode electrochromic layer 5 and the VHB sub-packaging layer 3, a pressure visualization device is formed.

[0043] In this embodiment, the thickness of the substrate 1 is 200 μm, the thickness of the ion storage layer 2 is 1 mm, the thickness of the VHB encapsulation layer 3 is 2 mm, the thickness of the dual-mode electrochromic layer 5 is 20 μm, and the thickness of the liquid metal layer 6 is 50 μm.

[0044] Example 2 This embodiment uses the same method as in Example 1 to prepare the pressure visualization device, except that: in this embodiment, the amount of substance of Eu element in the liquid is 5% of the amount of substance of WO3.

[0045] The performance of the device prepared in this embodiment is similar to that of Example 1.

[0046] Example 3 This embodiment uses the same method as in Example 1 to prepare the pressure visualization device, except that: in this embodiment, the amount of substance of Eu element in the liquid is 10% of the amount of substance of WO3.

[0047] The performance of the device prepared in this embodiment is similar to that of Example 1.

[0048] Example 4 This embodiment prepares a flexible self-powered opto-electric coupled pressure visualization device by the following method: (1) Dissolve 2.17 M acrylamide monomer powder and 5 M aluminum chloride in water to obtain a mixture solution.

[0049] (2) Add crosslinking agent N,N'-methylenebisacrylamide and initiator ammonium persulfate to the solution, and then add accelerator tetramethylethylenediamine. The addition amount of the crosslinking agent is 0.06% of the mass of acrylamide monomer, the addition amount of the initiator is 0.16% of the mass of acrylamide monomer, and the addition amount of the accelerator is 0.25% of the mass of acrylamide monomer; (3) Load the solution in step S2 into a mold and heat and cure it at 60 °C for 30 min to obtain a mixed gel of polyacrylamide and lithium chloride.

[0050] (4) Add Eu2O3 to hot nitric acid at 170 °C and react to obtain gel-like Eu(NO3)3. Since Eu(NO3)3 is gel-like, it is convenient to take out Eu(NO3)3.

[0051] (5) Dissolve the Eu(NO3)3 obtained in step (4) in ethanol, dissolve ammonium metatungstate hydrate in water, and stir and mix the Eu(NO3)3 solution and ammonium metatungstate hydrate solution (after mixing, the amount of substance of Eu element in the liquid is 7.5% of the amount of substance of WO3). After reaction, a transparent Eu 3+ -doped WO3 solution is obtained.

[0052] (6) Drop the Eu 3+ -doped WO3 solution obtained in step (5) on a glass plate and then sinter it at 450 °C for 5 h to obtain Eu 3+ -doped WO3 powder.

[0053] (7) Add the Eu 3+ -doped WO3 powder and silver nanowires to isopropanol in a mass ratio of 10:1 and stir and mix to obtain a suspension. Then, perform suction filtration on the suspension. After suction filtration, the solid substance remains on the filter paper to form a thin film, and dry it at 60 °C for 2 h to obtain a thin film of a mixture of Eu 3+ -doped WO3 and silver nanowires.

[0054] (8) Bond the mixed gel of polyacrylamide and lithium chloride to the substrate 1 by physical adhesion to form the ion storage layer 2.

[0055] (9) Bond the VHB encapsulation layer 3 to the ion storage layer 2 by physical pasting.

[0056] (10) At 75 °C, roll the liquid metal onto the substrate 1 to form the liquid metal layer 6. Then, while maintaining the heating state, roll the thin film of the mixture of Eu 3+ -doped WO3 and silver nanowires onto the liquid metal layer 6 to form the dual-mode electrochromic layer 5.

[0057] After the liquid metal layer 6 in step (3) is cooled, the dual-mode electrochromic layer 5 and the VHB encapsulation layer 3 are bonded by physical pasting.

[0058] In this embodiment, the thickness of the substrate 1 is 300 μm, the thickness of the ion storage layer 2 is 2 mm, the thickness of the VHB encapsulation layer 3 is 3 mm, the thickness of the dual-mode electrochromic layer 5 is 40 μm, and the thickness of the liquid metal layer 6 is 100 μm.

[0059] The performance of the device prepared in this embodiment is similar to that of Example 1.

[0060] Example 5 In this embodiment, a flexible self-powered light-electricity coupled pressure visualization device is prepared by the following method: (1) 2.17 M acrylamide monomer powder and 5 M aluminum chloride are dissolved in water to obtain a mixture solution.

[0061] (2) A cross-linking agent N,N'-methylenebisacrylamide and an initiator ammonium persulfate are added to the solution, and then an accelerator tetramethylethylenediamine is added. The addition amount of the cross-linking agent is 0.06% of the mass of the acrylamide monomer, the addition amount of the initiator is 0.16% of the mass of the acrylamide monomer, and the addition amount of the accelerator is 0.25% of the mass of the acrylamide monomer; (3) The solution of step S2 is loaded into a mold and heated and cured at 60 °C for 30 min to obtain a mixed gel of polyacrylamide and lithium chloride.

[0062] (4) Eu2O3 is added to hot nitric acid at 190 °C, and a gel-like Eu(NO3)3 is obtained. Since Eu(NO3)3 is gel-like, it is convenient to take out Eu(NO3)3.

[0063] (5) The Eu(NO3)3 obtained in step (4) is dissolved in ethanol, ammonium metatungstate hydrate is dissolved in water, and the Eu(NO3)3 solution and the ammonium metatungstate hydrate solution are stirred and mixed (after mixing, the amount of substance of Eu element in the liquid is 7.5% of the amount of substance of WO3), and after the reaction, a transparent Eu 3+ doped WO3 solution is obtained.

[0064] (6) The Eu 3+ doped WO3 solution obtained in step (5) is dropped on a glass plate and then sintered at 450 °C for 5 h to obtain Eu 3+ doped WO3 powder.

[0065] (7) The Eu 3+The doped WO3 powder and silver nanowires are added to isopropanol according to a mass ratio of 10:1 and stirred and mixed to obtain a suspension. After that, the suspension is filtered by suction. After suction filtration, the solid substance remains on the filter paper to form a thin film, which is dried at 60 °C for 2 h to obtain Eu-doped 3+ WO3 and silver nanowire mixture thin film.

[0066] (8) The mixed gel of polyacrylamide and lithium chloride is bonded to the substrate 1 by physical adhesion to form the ion storage layer 2.

[0067] (9) The VHB encapsulation layer 3 is bonded to the ion storage layer 2 by physical pasting.

[0068] (10) At 85 °C, the liquid metal is rolled onto the substrate 1 to form the liquid metal layer 6. After that, while maintaining the heating state, the Eu-doped 3+ WO3 and silver nanowire mixture thin film is rolled onto the liquid metal layer 6 to form the dual-mode electrochromic layer 5.

[0069] (11) After the liquid metal layer 6 in the step (3) is cooled, the dual-mode electrochromic layer 5 is bonded to the VHB encapsulation layer 3 by physical pasting.

[0070] In this embodiment, the thickness of the substrate 1 is 250 μm, the thickness of the ion storage layer 2 is 1.5 mm, the thickness of the VHB encapsulation layer 3 is 2.5 mm, the thickness of the dual-mode electrochromic layer 5 is 30 μm, and the thickness of the liquid metal layer 6 is 70 μm.

[0071] The performance of the device prepared in this embodiment is similar to that of Example 1.

[0072] Comparative Example 1 In this embodiment, the pressure visualization device is prepared by the same method as in Example 1, except that: in this embodiment, the amount of substance of Eu element in the liquid is 2.5% of the amount of substance of WO3.

[0073] Through Figure 8 It can be seen that due to too little Eu 3+ , the luminescence performance of the dual-mode electrochromic layer 5 in the device of Comparative Example 1 can hardly be manifested. When the Eu 3+ doping is too much (exceeding 10%), its luminescence performance will instead weaken. Therefore, within the doping amount range of Eu in the present invention 3+ , relatively good luminescence performance can be obtained.

[0074] As Figure 1 shown, Figure 1 in, if for Figure 1Pressure is applied to the substrate 1 at the top layer. Since the substrate 1 and the ion storage layer 2 are flexible, the substrate 1 and the ion storage layer 2 will bend downward under the pressure, so that the ion storage layer 2 moves downward, squeezing out the air in the cavity 4 and contacting the dual-mode electrochromic layer 5. After the ion storage layer 2 contacts the dual-mode electrochromic layer 5, Li in the ion storage layer 2 + can diffuse into the dual-mode electrochromic layer 5 through the interface. As Li + diffuses and embeds into the dual-mode electrochromic layer 5, combined with the self-driving effect of the liquid metal layer 6, the dual-mode electrochromic layer 5 will produce a color change to reflect the pressure. If the applied pressure is increased, the deformation of the ion storage layer 2 will increase, and its contact area with the dual-mode electrochromic layer 5 will increase, and more Li + diffuses into the dual-mode electrochromic layer 5 through the interface, and the color of the dual-mode electrochromic layer 5 changes further. Thus, the change in pressure can be reflected by the color change of the dual-mode electrochromic layer 5.

[0075] Through Figure 2 It can be seen that the LiCl-PAAm gel prepared by the present invention can withstand a maximum tensile strain of 900%, and has excellent mechanical properties.

[0076] Through Figure 3 It can be seen that the LiCl-PAAm gel prepared by the present invention can maintain a light transmittance of about 90% in the visible light band, and will not block the color change effect of the dual-mode electrochromic layer 5, and the color change effect of the device can be better displayed. At the same time, the substrate 1 is made of PET material and also has transparency.

[0077] Through Figure 4 It can be seen that 3360 nm corresponds to the vibration of the O-H bond, and 1650 nm corresponds to the vibration mode of the C=C bond, indicating that the LiCl-PAAm gel of the present invention is successfully prepared.

[0078] The above results fully prove that the LiCl-PAAm gel prepared by the present invention has excellent mechanical properties, optical properties and flexibility, which is helpful for its practical application and development as a wearable flexible device.

[0079] Through Figure 5 It can be seen that Eu within the doping amount range of the present invention 3+ has little influence on the crystal form of WO3, and cubic WO3 can be obtained in all cases. Thus, it can be proved that the Eu doping amount of the present invention 3+ is reasonable and will not have a negative impact on the actual use of the device of the present invention due to Eu 3+ doping.

[0080] Through Figure 6 It can be seen that before and after color change, WO3@Eu within the doping amount range of the present invention3+ has a relatively close diffuse reflectance, further indicating that Eu within the doping amount range of the present invention 3+ doping has almost no negative impact on the electrochromic performance of WO3.

[0081] Through Figure 7 It can be seen that the maximum contrast before and after the color change of the device in Example 1 of the present invention is 2.7%, indicating that Eu within the doping amount range of the present invention 3+ has basically no negative impact on the electrochromic effect of the device.

[0082] Through Figure 8 It can be seen that when the doping concentration of Eu 3+ is 7.5%, its luminous intensity is the highest, and the main peak of the luminescence is 615 nm, corresponding to Eu 3+ 's characteristic peak, which indicates that Eu 3+ has been successfully doped into WO3, and at the same time, the best doping amount of the luminescence effect Eu 3+ is 7.5%. At the same time, through Figure 8 it can also be seen that there are luminescence peaks at 592 nm, 615 nm, 653 nm, and 701 nm, corresponding to the energy level transitions of 5D0-7F1, 5D0-7F2, 5D0-7F3, and 5D0-7F4 of Eu 3+ , proving that the dual-mode electrochromic layer 5 in the device of the present invention has luminescence performance.

[0083] Through Figure 9 it can be seen that compared with before the color change, the intensity of the W-O vibration in WO3 after the color change decreases, and the peak shift and intensity decrease caused by the color development are attributed to the increase in the number of W 5+ . Combining Figure 10 and 11 in, the XPS signals of 37.38 eV and 35.28 eV come from W 6+ , and before the color change, weak XPS signals of 36.08 eV and 33.88 eV of the W 5+ element were observed. The XPS signals of 36.08 eV and 33.88 eV of W 5+ increase significantly in WO3 after the color change, indicating that during the electrochromic process of WO3, the polaron transitions from W 6+ to W 5+ .

[0084] Through Figures 12 - 14It can be seen that the valence states of the oxides of In and Sn elements are observed on the surface, while the Bi element exists only in the elemental state, indicating that both In and Sn elements can undergo spontaneous oxidation reactions under general conditions. Since the standard electrode potential of In is lower than that of Sn, In reacts first and is considered to act as a self-driven power source, demonstrating that the device of the present invention using an indium-based alloy as the liquid metal layer can effectively achieve the self-driven effect.

[0085] It can be seen that in the present invention, the ion storage layer and the dual-mode electrochromic layer are arranged in an upper and lower two-layer structure. At the same time, a part of the bottom surface of the ion storage layer is embedded in the surface of the dual-mode electrochromic layer, making the structure of the device more stable. Figure 15

[0086] It can be seen that within a certain range of deformation, the resistance change of the indium-based alloy always remains within a relatively small range, indicating that the deformation of the device of the present invention will not have a negative impact on the performance. Figure 16

[0087] It can be seen that at the same wavelength, the diffuse reflection change amplitudes of the device under different pressures are different. Among them, at the wavelength of 475 nm, the diffuse reflection change amplitude is the largest, indicating that under the wavelength condition of 475 nm, the contrast of the dual-mode electrochromic layer 5 of the device of the present invention is the most obvious and the pressure visualization effect is the best. Figure 17

[0088] It can be seen that the diffuse reflectance of the device under different pressures decreases as the pressure increases, indicating that the device of the present invention can achieve the effect of pressure visualization. Figure 18

[0089] In summary, the device of the present invention can effectively improve the structural compactness of the device, simplify the device structure, realize the visualization of pressure changes without adding self-driven power, have low energy consumption, be easy to use, and have excellent applicability.

[0090] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.​​​​

Claims

1. A flexible self-driven optical-electric coupled pressure visualization device, characterized in that: The device comprises a substrate (1), an ion storage layer (2), a VHB encapsulation layer (3), a dual-mode electrochromic layer (5), and a liquid metal layer (6); the ion storage layer (2), the VHB encapsulation layer (3), the dual-mode electrochromic layer (5), and the liquid metal layer (6) are arranged in sequence from top to bottom between the substrate (1); the VHB encapsulation layer (3) is in a ring structure; a cavity (4) is provided in the middle of the VHB encapsulation layer (3); the thickness of the substrate (1) is 200-300 μm; the thickness of the ion storage layer (2) is 1-2 mm; the thickness of the VHB encapsulation layer (3) is 2-3 mm; the thickness of the dual-mode electrochromic layer (5) is 20-40 μm; and the thickness of the liquid metal layer (6) is 50-100 μm; The substrate (1) is made of polyethylene terephthalate, the ion storage layer (2) is made of a mixed gel of polyacrylamide and lithium chloride, and the dual-mode electrochromic layer (5) is made of Eu doped 3+ The liquid metal layer (6) is a mixture of WO3 and silver nanowires, and the raw material of the liquid metal layer is indium-based alloy.

2. The method for preparing a flexible self-driven optical-electric coupled pressure visualization device according to claim 1, characterized in that: The preparation method comprises the following steps: (1) bonding a mixed gel of polyacrylamide and lithium chloride to a substrate (1) by physical bonding to form an ion storage layer (2); (2) bonding the VHB encapsulation layer (3) to the ion storage layer (2) by physical bonding; (3) By hot rolling, in a heated state, the liquid metal is rolled onto the substrate (1) to form a liquid metal layer (6), and then, the Eu-doped 3+ A mixture film of WO3 and silver nanowires is rolled onto the liquid metal layer (6) to form a dual-mode electrochromic layer (5); (4) After the liquid metal layer (6) in step (3) is cooled, the dual-mode electrochromic layer (5) is bonded to the VHB encapsulation layer (3) by physical bonding.

3. The preparation method according to claim 2, characterized in that: In the step (3), the heating temperature is 75-85°C.

4. The preparation method according to claim 2, characterized in that: The raw material preparation process of the ion storage layer (2) comprises the following steps: S1: dissolving 2.17 M acrylamide monomer powder and 5 M lithium chloride in water to obtain a mixture solution; S2: adding a crosslinking agent N,N'-methylenebisacrylamide and an initiator ammonium persulfate to the solution obtained in step S1, and then adding an accelerator tetramethylethylenediamine; S3: The solution of step S2 is placed into a mold and heated and cured to obtain a mixed gel of polyacrylamide and lithium chloride.

5. The preparation method according to claim 4, characterized in that: In the step S2, the amount of the cross-linking agent added is 0.06% of the mass of the acrylamide monomer, the amount of the initiator added is 0.16% of the mass of the acrylamide monomer, and the amount of the accelerator added is 0.25% of the mass of the acrylamide monomer.

6. The preparation method according to claim 4, characterized in that: In the step S3, the heating curing temperature is 60° C. and the heating curing time is 30 min.

7. The preparation method according to claim 2, characterized in that: The doped Eu 3+ The preparation process of the WO3 and silver nanowire mixture thin film includes the following steps: Q1: Add Eu2O3 to hot nitric acid, and after the reaction is completed, gelatinous Eu(NO3)3 is obtained; Q2: Dissolve the Eu(NO3)3 obtained in step Q1 in ethanol, dissolve ammonium metatungstate hydrate in water to obtain Eu(NO3)3 solution and ammonium metatungstate hydrate solution, and stir and mix the Eu(NO3)3 solution and ammonium metatungstate hydrate solution. After the reaction, a transparent Eu 3+ Doped WO3 solution, the Eu 3+ In the doped WO3 solution, the amount of Eu element is 5%-10% of the amount of WO3; Q3: The Eu obtained in step Q2 3+ The doped WO3 solution is dropped onto a glass plate and then sintered to obtain Eu 3+ Doped WO3 powder. Q4: The Eu obtained in step Q3 3+ The doped WO3 powder and silver nanowires were added to isopropanol and stirred to obtain a suspension, and then the suspension was filtered. After the filtration, the solid matter remained on the filter paper to form a thin film, and the thin film was dried to obtain the doped Eu 3+ WO3 and silver nanowire mixture thin film.

8. The preparation method according to claim 7, characterized in that: In step Q1, the temperature of hot nitric acid is 170-190°C.

9. The preparation method according to claim 7, characterized in that: In step Q3, the sintering temperature is 450° C. and the sintering time is 5 hours.

10. The preparation method according to claim 7, characterized in that: In step Q4, Eu 3+ The mass ratio of doped WO3 powder and silver nanowires is Eu 3+ Doped WO3 powder: silver nanowire = 10:1, drying temperature is 60°C, and drying time is 2h.

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