3D printed wear-resistant packaging layer for flexible sensors and its preparation method and application

Abstract

The present invention discloses a 3D-printed wear-resistant encapsulation layer for flexible sensors, as well as a preparation method and application thereof. The preparation comprises the following steps: ultrasonically dispersing Fe3O4@SiO2 two-dimensional nanochains in alcohol, which is then added to Sylgard 184-A to obtain a mother liquor; irradiating Sylgard 184-A, Sylgard 184-B, a copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane, and a photoinitiator with ultraviolet light to obtain a base liquid; mixing the mother liquid and the base liquid to form ink; and 3D-printing the ink to obtain a wear-resistant encapsulation layer; the wear-resistant encapsulation layer comprises at least two layers, the outermost layer of which is oriented using a rotating magnetic field. The encapsulation layer has an extremely low coefficient of friction and wear rate and can be used in flexible electronic devices and wearable flexible sensors.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printed flexible sensors, and in particular to a 3D printed wear-resistant packaging layer for a flexible sensor, a preparation method thereof, and an application thereof. Background Art

[0002] Driven by advances in information science, materials science, wireless communications, and computer science, flexible electronics are rapidly developing toward stretchability, integration, multifunctionality, and intelligence. Flexible sensors have reached a critical juncture, with a wide variety of new devices emerging for diverse applications. However, deficiencies remain in material selection, surface design, and fabrication processes. Beyond addressing the wide strain range and high sensitivity of sensors, challenges encountered in practical use also need to be overcome. For example, wear caused by friction during daily wear needs to be addressed urgently. Summary of the Invention

[0003] In order to overcome the problems in the prior art, the purpose of the present invention is to provide a 3D printed wear-resistant packaging layer for flexible sensors, a preparation method and an application. The flexible packaging layer prepared by this method can reduce the friction coefficient and wear rate, effectively protect the sensing layer of the sensor, and extend the service life of the sensor.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for preparing a 3D-printed wear-resistant packaging layer that can be used for a flexible sensor comprises the following steps:

[0006] The Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in alcohol, then added to Sylgard184-A, stirred evenly, and dried to obtain a mother solution;

[0007] Sylgard 184-A, Sylgard 184-B, a copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane, and a photoinitiator are stirred uniformly and then irradiated with ultraviolet light to obtain a base liquid;

[0008] Mixing the mother liquid and the base liquid to form ink;

[0009] The ink is 3D printed to obtain a wear-resistant packaging layer; the wear-resistant packaging layer includes at least two layers, and the outermost layer is oriented by a rotating magnetic field.

[0010] Furthermore, the photoinitiator is ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0011] Furthermore, the mass ratio of the mother liquid to the base liquid is 1.25-2.25 g:0.01-0.2 g.

[0012] Furthermore, when preparing the mother solution, the mass ratio of Fe3O4@SiO2 two-dimensional nanochains to Sylgard184-A is 2-3 mg:2-3 g.

[0013] Furthermore, when preparing the base liquid, the mass ratio of Sylgard 184-A, Sylgard 184-B, the copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane and the photoinitiator is 2-3g: 0.2-0.3g: 0.5-0.7g: 0.03-0.05g.

[0014] Furthermore, the conditions of ultraviolet irradiation are: 365nm ultraviolet irradiation for 5s.

[0015] Furthermore, the outermost layer is oriented using a rotating magnetic field, including the following steps: rotating the magnetic field for 1-5 minutes, fixing the direction of the magnetic field for 2-10 minutes, and curing after ultraviolet irradiation for 2-10 seconds.

[0016] Furthermore, the curing conditions are: temperature of 120-160° C. and time of 5-8 hours.

[0017] The 3D printed wear-resistant packaging layer for flexible sensors prepared according to the method includes at least two layers, the outermost layer is a vertical layer, and all other layers are horizontal layers.

[0018] The invention relates to an application of a 3D printed wear-resistant packaging layer for flexible sensors prepared according to the method in flexible electronic devices and wearable flexible sensors.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention uses polydimethylsiloxane (PDMS) as the main matrix material, a copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane (M-PDMS), and a photoinitiator as a rheology modifier to make it printable. Fe3O4@SiO2 two-dimensional nanochains are used as a mechanical performance enhancing phase to control the arrangement of the nanochains, so that the tribological properties and other mechanical properties of the matrix material are improved. The materials used are non-toxic, have good biocompatibility, will not produce an immune rejection reaction with the skin, and can be used for the packaging layer of wearable devices. The tribological test results of the printed multi-layer angled packaging layer show that: due to the existence of the texture of the angled surface, the friction coefficient is effectively reduced. At the same time, the arrangement of the nanochains between different layers forms a structure similar to the outer layer of the abalone shell, achieving a low wear rate (relative to PDMS, a reduction of 95.36%). The preparation process of the present invention is simple, the cost is low, the preparation process is safe, and the raw materials are non-toxic and harmless with good biocompatibility. The flexible packaging layer prepared by the present invention has strong mechanical properties and excellent tribological properties, which can better protect the flexible sensor packaging layer.

[0021] Furthermore, the mass ratio of Fe3O4@SiO2 two-dimensional nanochains to Sylgard184-A is 2-3 mg:2-3 g, and the magnetic field can be effectively driven, so that the chains can be arranged on demand in the main matrix.

[0022] Furthermore, since polydimethylsiloxane (PDMS) itself does not have the property of shear thinning, it is necessary to add a rheology modifier, a copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane (M-PDMS), and when preparing the base liquid, the mass ratio of Sylgard184-A, Sylgard184-B, the copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane and the photoinitiator is 2-3g: 0.2-0.3g: 0.5-0.7g: 0.03-0.05g.

[0023] Furthermore, during the printing process, a 365nm wavelength light source is required to preliminarily cure the printed sample to give it a good three-dimensional shape.

[0024] The wear-resistant encapsulation layer prepared by the present invention can be integrated with other flexible conductive layers for printing, which is simple and efficient. After the encapsulation layer and the sensing layer are integrated to prepare a wearable device, the service life of the flexible sensor can be effectively improved. Compared with the polydimethylsiloxane (PDMS) encapsulation layer currently commonly used in the field of flexible electronic devices, the friction coefficient of the encapsulation layer of the present invention is reduced by 27.70%, and the wear rate is reduced by 95.36%. Therefore, the flexible layer obtained by this preparation method has good application scenarios in real life, such as friction and scratches during fitness activities, which can be better protected by the flexible layer of this method to protect the sensing layer of the flexible electronic device in motion. At the same time, it can also achieve large-scale low-cost preparation and further promote it. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] in,

[0027] Figure 1 The following are photos of the encapsulation layer prepared in the embodiment of the present invention; wherein (a) is a schematic diagram of the angled wear-resistant layer, and (b) is a physical picture of the printed angled wear-resistant layer;

[0028] Figure 2 Schematic diagram of the tribological testing method used in an embodiment of the present invention;

[0029] Figure 3 Figure 1 shows the magnetically assisted printing device used in the embodiments of the present invention, and the arrangement of nanochains between different layers of the printed encapsulation layer. (a) shows the rotating magnetic field device used for magnetically assisted printing, (b) shows a field emission electron microscope micrograph of a horizontally aligned layer, (c) shows a field emission electron microscope micrograph of a horizontally aligned layer, (d) shows a field emission electron microscope micrograph of a vertically aligned layer, and (e) shows a field emission electron microscope micrograph of a vertically aligned layer.

[0030] Figure 4 Figure 1 is the mechanical properties of the angled multilayer wear-resistant encapsulation layer prepared in the embodiment of the present invention; wherein, (a) is a comparison of the elastic modulus and Shore hardness of the angled wear-resistant encapsulation layer and PDMS, (b) is a curve showing the change in elastic modulus of PDMS at different cycle numbers, (c) is a curve showing the change in elastic modulus of the angled wear-resistant encapsulation layer at different cycle numbers, (d) is a curve showing the change in hysteresis dissipation energy of PDMS at different cycle numbers, and (e) is a curve showing the change in hysteresis dissipation energy of the angled wear-resistant encapsulation layer at different cycle numbers;

[0031] Figure 5 Figure 2 is a friction coefficient curve of the angled multilayer wear-resistant encapsulation layer and PDMS prepared in an embodiment of the present invention under different experimental conditions; wherein (a) is the friction coefficient curve of PDMS under different experimental conditions, and (b) is the friction coefficient curve of the angled wear-resistant encapsulation layer under different experimental conditions;

[0032] Figure 6 The wear volume and wear rate of the angled multilayer wear-resistant encapsulation layer prepared in the embodiment of the present invention, as well as its morphology after wear; wherein, (a) comparison of the wear volume and wear rate of the angled wear-resistant encapsulation layer and PDMS, (b) surface electron microscope micrograph of PDMS before wear, (c) surface electron microscope micrograph of the angled wear-resistant encapsulation layer before wear, (d) surface electron microscope micrograph of PDMS after wear, (e) surface electron microscope micrograph of the angled wear-resistant encapsulation layer after wear, (f) surface electron microscope micrograph of the grinding ball after wear with PDMS, (g) surface electron microscope micrograph of the grinding ball after wear with the angled wear-resistant encapsulation layer. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in a variety of different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0034] The present invention is not limited to the following examples, which are merely provided to illustrate the present invention.

[0035] The present invention provides a method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor, comprising the following steps:

[0036] Step 1: Preparation of Fe3O4@SiO2 two-dimensional nanochains:

[0037] Fe3O4 nanoparticles were synthesized by a hydrothermal method and further self-assembled into Fe3O4@SiO2 two-dimensional nanochains through a magnetic field.

[0038] First, FeCl₃·6H₂O (1 g), C₆H₅Na₃Oₐ·2H₂O (2.4 g), CH₄N₂O (0.8 g), and PAAS (0.6 g) were dissolved sequentially in 80 mL of deionized water and magnetically stirred for 4 h until completely dissolved. The mixed solution was transferred to a Teflon-lined stainless steel autoclave and heated at 200°C for 12 h. The resulting black product was centrifuged (9000 rpm) for 15 min and washed alternately with alcohol and water. After standing in a vacuum oven at 60°C for 4 h, Fe₃O₄ particles were obtained. Fe₃O₄ (25.8 mg) was dispersed in 3 mL of deionized water and sonicated (200 W) for 20 min. The dispersed Fe₃O₄ was first transferred to a mixture of ethanol and NH₄OH, then sonicated (200 W) for 20 min (maintaining the water bath at 30°C). The mixture was quickly transferred to a three-necked flask, TEOS (170 μL) was added, and mechanical stirring was performed for 15 min. The prepared mixture was poured into a 25mL beaker and subjected to a pair of magnets placed above and below (in a perpendicular magnetic field) for 1-8 hours. Subsequently, the mixture was centrifuged, washed alternately with ethanol and deionized water, and dried at 60°C to obtain Fe₃O₄@SiO₂ two-dimensional nanochains composed of Fe₃O₄ coated with silica. The Fe₃O₄@SiO₂ chains were 60.2±10.7μm long and 0.2μm in diameter.

[0039] Step 2: Prepare the ink for printing:

[0040] 2-3 mg of Fe₃O₄@SiO₂ 2D nanochains were ultrasonically dispersed in 1 mL of ethanol. Then, 2-3 g of Sylgard 184-A (PDMS consists of two components, Sylgard 184-A and Sylgard 184-B) were added and mechanically stirred for 4 hours. The resulting solution was then transferred to a vacuum drying oven and heated at 80°C for 90 minutes to eliminate the alcohol, yielding the ink. This ink, referred to as the mother liquor, was stored in a refrigerator until ready for use.

[0041] Then, 2-3 g of Sylgard 184-A, 0.2-0.3 g of Sylgard 184-B, 0.5-0.7 g of a copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane (M-PDMS), and 0.03-0.05 g of ethyl 2,4,6-trimethylbenzoylphenylphosphonate (photoinitiator, TPO-L) were weighed respectively, mixed, and magnetically stirred for 30-40 minutes. Then, the viscosity was enhanced by irradiation with 365 nm ultraviolet light for 2-10 seconds to obtain a mixture, which was called a base liquid.

[0042] Mix 1.25-2.25g of the mother liquid with 0.1-0.2g of the base liquid to form a printable ink.

[0043] Step 3: Printing angled wear-resistant multi-layer flexible layers:

[0044] The angled, wear-resistant, multilayer flexible layer consists of five layers. During the printing process for layers 1, 2, 3, and 4, no magnetic field was applied, the printing nozzle was 400 μm, and the printing speed was 10 mm / s. The shear force of the extrusion flow field was used to align the Fe3O4@SiO2 nanochains horizontally. After the fourth layer was printed, UV irradiation was applied for 5 seconds. Subsequently, printing was paused, and a magnetic field was positioned perpendicular to the top of the flexible layer (field strength 500 Oe), and printing continued. After the fifth layer was printed, a rotating magnetic field was used for orientation. The specific conditions were: a rotating magnetic field for 1-5 minutes, followed by a fixed magnetic field direction for 2-10 minutes. After UV irradiation for 2-10 seconds, the flexible layer was placed in a vacuum drying oven at 120-160°C for 5-8 hours. During the printing process, the printing path was adjusted to 60°, ultimately producing an encapsulation layer with a multilayer nanochain arrangement and a 60° surface texture.

[0045] Applications of the multi-layer 3D-printed flexible layer with low friction and low wear rate produced by the above method include adhering the flexible layer to the surface of flexible electronic devices to better protect the electronic devices, or printing it together with the sensing layer to form a complete wearable flexible sensor. Specifically, the prepared flexible layer can be integrated with a mixture of liquid metal and polydimethylsiloxane, for example, and then cured to obtain a flexible sensor with a low-friction and high-wear-resistant surface.

[0046] The multi-layer 3D-printed flexible layer with low friction and low wear rate prepared by the present invention has an extremely low friction coefficient and wear rate. The wear-resistant flexible layer has excellent mechanical properties.

[0047] Example 1

[0048] The first step is to prepare Fe3O4@SiO2 two-dimensional nanochains:

[0049] First, FeCl3·6H2O (1 g), C6H5Na3O7·2H2O (2.4 g), CH4N2O (0.8 g), and PAAS (0.6 g) were dissolved sequentially in 80 mL of deionized water and magnetically stirred for 4 h until completely dissolved. The mixture was placed in a reactor and heated at 200°C for 12 h. The resulting black product was centrifuged and washed, then placed in a vacuum oven at 60°C for 4 h to yield Fe3O4 particles. Fe3O4 (25.8 mg) was dispersed in 3 mL of deionized water and sonicated (200 W) for 20 min. The dispersed Fe3O4 was first transferred to a mixture of ethanol and NH4OH, then sonicated (200 W) for 20 min (maintaining the water bath at 30°C). The mixture was quickly transferred to a three-necked flask, TEOS (170 μL) was added, and mechanical stirring was performed for 15 min. The prepared mixture was poured into a 25 mL beaker and a pair of magnets were placed above and below the beaker (perpendicular to the magnetic field) for 8 hours. Subsequently, the Fe3O4@SiO2 nanochains were centrifuged, washed alternately with ethanol and deionized water, and dried at 60°C.

[0050] The second step is to prepare printable ink:

[0051] 2.5 mg of Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 2.5 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This mixture was heated at 80°C under vacuum for 90 minutes (mother solution). Next, 2.5 g of Sylgard 184-A, 0.25 g of Sylgard 184-B, 0.685 g of M-PDMS, and 0.0415 g of TPO-L were weighed separately. After mixing, the mixture was magnetically stirred for 30 minutes and then irradiated with 365 nm UV light for 5 seconds to increase viscosity (base solution). 1.75 g of the mother solution and 0.175 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0052] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0053] The first four layers were printed with a 400μm nozzle and a printing speed of 10mm / s without applying a magnetic field. After printing was complete, the flexible layer was exposed to UV light for 5 seconds. Subsequently, printing was paused, and a magnetic field (field strength 500Oe) was positioned perpendicular to the flexible layer, and printing continued. After the fifth layer was printed, the magnetic field was rotated for 2 minutes, then fixed in a fixed direction for 5 minutes. After 5 seconds of UV exposure, the flexible layer was cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, the flexible layer was removed to yield a wear-resistant, textured surface.

[0054] The wear-resistant flexible layer prepared in this embodiment is as follows Figure 1 As shown in (a) and (b), the structure is simple and easy to prepare.

[0055] The method of testing the tribological performance in this embodiment is as follows: Figure 2 As shown, the multi-layer 3D printed flexible layer with low friction and low wear rate effects prepared by the present invention is placed on a UMT-2 friction and wear testing machine. The upper sample uses a GCr15 steel ball with a diameter of 9.5 mm, the speed is 1 Hz, and the loads are 1 N, 5 N, and 10 N to test its performance under different working conditions.

[0056] The rotating magnetic field used in this embodiment is as follows Figure 3 In (a), when orientation is required, the rotating mechanism is powered to rotate the magnetic field. When orientation is completed, the rotation stops. Under the action of the extrusion flow field of the nozzle, the nanochains are arranged horizontally as shown in Figure 3 (b) and Figure 3 As shown in (c), after the magnetic field rotates and orients, the nanochains are vertically aligned, as shown in Figure 3 (d) and Figure 3 This confirms the success of the hierarchical ordered arrangement as shown in (e).

[0057] The mechanical properties of the wear-resistant flexible layer prepared in this embodiment are as follows: Figure 4 As shown in Figures (a)-(e), the tensile fracture results reveal an increase in the elastic modulus of the wear-resistant flexible layer, along with a slight improvement in Shore hardness. Cyclic tensile testing at maximum strain reveals a significant decrease in the elastic modulus of the wear-resistant flexible layer. However, the hysteresis dissipation energy of the flexible layer is low, quickly reaching a plateau. This demonstrates low internal friction dissipation within the flexible layer and a strong bond between the nanochains and the substrate.

[0058] The friction performance of the wear-resistant flexible layer prepared in this embodiment under different loads is as follows: Figure 5 As shown in (a) and (b), the angled wear-resistant encapsulation layer exhibits a lower friction coefficient than polydimethylsiloxane under various load conditions. When rubbing at a 60° angle to the surface texture, the friction coefficient is reduced by 27.70% and the wear rate is reduced by 95.36% compared to polydimethylsiloxane. This demonstrates that the flexible layer prepared by the present invention exhibits superior tribological properties under various scratching environments, achieving lower friction.

[0059] The wear performance of the flexible layer with wear resistance prepared in this embodiment under a load of 10N is as follows: Figure 6 As shown in (a)-(g), Figure 6 In (a), it can be seen that the wear volume and wear rate of the angled wear-resistant encapsulation layer are much lower than those of polydimethylsiloxane. It has been reduced by 95.36%. Figure 6In (e), the angled wear-resistant encapsulation layer exhibits no surface furrows or wear debris after wear. The presence of the nanochains effectively enhances the substrate's wear resistance and acts as a pinning mechanism. In contrast, the polydimethylsiloxane surface exhibits furrows, indicating significant material transfer to the grinding ball surface, indicating adhesive wear. This demonstrates the excellent tribological properties of the present invention in friction experiments, making it suitable for use as a flexible sensor encapsulation layer to protect electronic devices.

[0060] Example 2

[0061] The first step is to prepare Fe3O4@SiO2 two-dimensional nanochains:

[0062] First, FeCl3·6H2O (1 g), C6H5Na3O7·2H2O (2.4 g), CH4N2O (0.8 g), and PAAS (0.6 g) were dissolved sequentially in 80 mL of deionized water and magnetically stirred for 4 h until completely dissolved. The mixture was placed in a reactor and heated at 200°C for 12 h. The resulting black product was centrifuged and washed, then placed in a vacuum oven at 60°C for 4 h to yield Fe3O4 particles. Fe3O4 (25.8 mg) was dispersed in 3 mL of deionized water and sonicated (200 W) for 20 min. The dispersed Fe3O4 was first transferred to a mixture of ethanol and NH4OH, then sonicated (200 W) for 20 min (maintaining the water bath at 30°C). The mixture was quickly transferred to a three-necked flask, TEOS (170 μL) was added, and mechanical stirring was performed for 15 min. The prepared mixture was poured into a 25 mL beaker and a pair of magnets were placed above and below the beaker (perpendicular to the magnetic field) for 1 hour. Subsequently, the Fe3O4@SiO2 nanochains were centrifuged, washed alternately with ethanol and deionized water, and dried at 60°C.

[0063] The second step is to prepare printable ink:

[0064] 2.5 mg of Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 2.5 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This mixture was heated at 80°C under vacuum for 90 minutes (mother solution). Next, 2.5 g of Sylgard 184-A, 0.25 g of Sylgard 184-B, 0.685 g of M-PDMS, and 0.0415 g of TPO-L were weighed separately. After mixing, the mixture was magnetically stirred for 30 minutes and then irradiated with 365 nm UV light for 5 seconds to increase viscosity (base solution). 1.75 g of the mother solution and 0.175 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0065] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0066] The first two layers were printed with a 400μm nozzle and a printing speed of 10mm / s without applying a magnetic field. After printing was complete, the flexible layer was exposed to UV light for 5 seconds. Subsequently, printing was paused, and a magnetic field (field strength 500Oe) was positioned perpendicular to the flexible layer, and printing continued. After the third layer was printed, the magnetic field was rotated for 2 minutes, then fixed in a fixed direction for 5 minutes. After 5 seconds of UV exposure, the flexible layer was cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, the flexible layer was removed to yield a wear-resistant, textured surface.

[0067] Example 3

[0068] The first step is to prepare Fe3O4@SiO2 two-dimensional nanochains:

[0069] First, FeCl3·6H2O (1 g), C6H5Na3O7·2H2O (2.4 g), CH4N2O (0.8 g), and PAAS (0.6 g) were dissolved sequentially in 80 mL of deionized water and magnetically stirred for 4 h until completely dissolved. The mixture was placed in a reactor and heated at 200°C for 12 h. The resulting black product was centrifuged and washed, then placed in a vacuum oven at 60°C for 4 h to yield Fe3O4 particles. Fe3O4 (25.8 mg) was dispersed in 3 mL of deionized water and sonicated (200 W) for 20 min. The dispersed Fe3O4 was first transferred to a mixture of ethanol and NH4OH, then sonicated (200 W) for 20 min (maintaining the water bath at 30°C). The mixture was quickly transferred to a three-necked flask, TEOS (170 μL) was added, and mechanical stirring was performed for 15 min. The prepared mixture was poured into a 25 mL beaker and a pair of magnets were placed above and below the beaker (perpendicular to the magnetic field) for 5 hours. Subsequently, the Fe3O4@SiO2 nanochains were centrifuged, washed alternately with ethanol and deionized water, and dried at 60°C.

[0070] The second step is to prepare printable ink:

[0071] 2.5 mg of Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 2.5 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This mixture was heated at 80°C under vacuum for 90 minutes (mother solution). Next, 2.5 g of Sylgard 184-A, 0.25 g of Sylgard 184-B, 0.685 g of M-PDMS, and 0.0415 g of TPO-L were weighed separately. After mixing, the mixture was magnetically stirred for 30 minutes and then irradiated with 365 nm UV light for 5 seconds to increase viscosity (base solution). 1.75 g of the mother solution and 0.175 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0072] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0073] The print nozzle was 400 μm, the print speed was 10 mm / s, and the first three layers were printed without applying a magnetic field. After printing, the flexible layer was exposed to UV light for 5 seconds. Subsequently, printing was paused, and a magnetic field (field strength 500 Oe) was positioned perpendicular to the flexible layer, and printing continued. After the fourth layer was printed, the magnetic field was rotated for 2 minutes, then fixed in the same direction for 5 minutes. After 5 seconds of UV light exposure, the flexible layer was cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, the flexible layer was removed to obtain a wear-resistant, textured surface.

[0074] Example 4

[0075] The first step is to prepare Fe3O4@SiO2 two-dimensional nanochains:

[0076] First, FeCl3·6H2O (1 g), C6H5Na3O7·2H2O (2.4 g), CH4N2O (0.8 g), and PAAS (0.6 g) were dissolved sequentially in 80 mL of deionized water and magnetically stirred for 4 h until completely dissolved. The mixture was placed in a reactor and heated at 200°C for 12 h. The resulting black product was centrifuged and washed, then placed in a vacuum oven at 60°C for 4 h to yield Fe3O4 particles. Fe3O4 (25.8 mg) was dispersed in 3 mL of deionized water and sonicated (200 W) for 20 min. The dispersed Fe3O4 was first transferred to a mixture of ethanol and NH4OH, then sonicated (200 W) for 20 min (maintaining the water bath at 30°C). The mixture was quickly transferred to a three-necked flask, TEOS (170 μL) was added, and mechanical stirring was performed for 15 min. The prepared mixture was poured into a 25 mL beaker and a pair of magnets were placed above and below the beaker (perpendicular to the magnetic field) for 8 hours. Subsequently, the Fe3O4@SiO2 nanochains were centrifuged, washed alternately with ethanol and deionized water, and dried at 60°C.

[0077] The second step is to prepare printable ink:

[0078] 2.5 mg of Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 2.5 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This mixture was heated at 80°C under vacuum for 90 minutes (mother solution). Next, 2.5 g of Sylgard 184-A, 0.25 g of Sylgard 184-B, 0.685 g of M-PDMS, and 0.0415 g of TPO-L were weighed separately. After mixing, the mixture was magnetically stirred for 30 minutes and then irradiated with 365 nm UV light for 5 seconds to increase viscosity (base solution). 1.75 g of the mother solution and 0.175 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0079] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0080] The print nozzle is 400μm, the print speed is 10mm / s, and a single layer is printed without applying a magnetic field. After printing is complete, the flexible layer is exposed to UV light for 5 seconds. Subsequently, printing is paused, and a magnetic field (field strength 500Oe) is positioned perpendicular to the flexible layer, and printing continues. After the second layer is printed, the magnetic field is rotated for 2 minutes, then fixed in the same direction for 5 minutes. After 5 seconds of UV exposure, the flexible layer is cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, it is removed to obtain a wear-resistant flexible layer with a surface texture.

[0081] Example 5

[0082] The first step is the same as in Example 1;

[0083] The second step is to prepare printable ink:

[0084] 2 mg of Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 3 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This solution was heated at 80°C under vacuum for 90 minutes (mother solution). 2.7 g of Sylgard 184-A, 0.3 g of Sylgard 184-B, 0.5 g of M-PDMS, and 0.05 g of TPO-L were then weighed separately. After mixing, the solution was magnetically stirred for 40 minutes and then irradiated with 365 nm UV light for 7 seconds to increase viscosity (base solution). 1.25 g of the mother solution and 0.1 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0085] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0086] The print nozzle is 400μm, the print speed is 10mm / s, and a single layer is printed without applying a magnetic field. After printing is complete, the flexible layer is exposed to UV light for 5 seconds. Subsequently, printing is paused, and a magnetic field (field strength 500Oe) is positioned perpendicular to the flexible layer, and printing continues. After the second layer is printed, the magnetic field is rotated for 2 minutes, then fixed in the same direction for 5 minutes. After 5 seconds of UV exposure, the flexible layer is cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, it is removed to obtain a wear-resistant flexible layer with a surface texture.

[0087] Example 6

[0088] The first step is the same as in Example 1;

[0089] The second step is to prepare printable ink:

[0090] 2.3 mg of Fe₃O₄@SiO₂ two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 2 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This solution was heated at 80°C under vacuum for 90 minutes (mother solution). Next, 2 g of Sylgard 184-A, 0.2 g of Sylgard 184-B, 0.6 g of M-PDMS, and 0.03 g of TPO-L were weighed separately. After mixing, the mixture was magnetically stirred for 35 minutes and then irradiated with 365 nm UV light for 10 seconds to increase viscosity (base solution). 2 g of the mother solution and 0.2 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0091] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0092] The print nozzle is 400μm, the print speed is 10mm / s, and a single layer is printed without applying a magnetic field. After printing is complete, the flexible layer is exposed to UV light for 5 seconds. Subsequently, printing is paused, and a magnetic field (field strength 500Oe) is positioned perpendicular to the flexible layer, and printing continues. After the second layer is printed, the magnetic field is rotated for 2 minutes, then fixed in the same direction for 5 minutes. After 5 seconds of UV exposure, the flexible layer is cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, it is removed to obtain a wear-resistant flexible layer with a surface texture.

[0093] Example 7

[0094] The first step is the same as in Example 1;

[0095] The second step is to prepare printable ink:

[0096] 3 mg of Fe₃O₄@SiO₂ two-dimensional nanochains were ultrasonically dispersed in 1 mL of ethanol and then added to 2.5 g of Sylgard 184-A with continuous mechanical stirring for 4 hours. This mixture was heated at 80°C under vacuum for 90 minutes (mother solution). Next, 3 g of Sylgard 184-A, 0.22 g of Sylgard 184-B, 0.7 g of M-PDMS, and 0.04 g of TPO-L were weighed separately. After mixing, the mixture was magnetically stirred for 32 minutes and then irradiated with 365 nm UV light for 2 seconds to increase viscosity (base solution). 2.25 g of the mother solution and 0.15 g of Sylgard 184-B were mixed with the base solution to form a printable ink.

[0097] The third step is to prepare an angled wear-resistant multi-layer flexible layer:

[0098] The print nozzle is 400μm, the print speed is 10mm / s, and a single layer is printed without applying a magnetic field. After printing is complete, the flexible layer is exposed to UV light for 5 seconds. Subsequently, printing is paused, and a magnetic field (field strength 500Oe) is positioned perpendicular to the flexible layer, and printing continues. After the second layer is printed, the magnetic field is rotated for 2 minutes, then fixed in the same direction for 5 minutes. After 5 seconds of UV exposure, the flexible layer is cured in a 160°C vacuum drying oven for 7 hours. Once fully cured, it is removed to obtain a wear-resistant flexible layer with a surface texture.

[0099] The present invention is not limited to the tribological results measured in the embodiments of the present invention. The present invention also has great application prospects in the fields of smart windows, stretchable electronics, etc.

[0100] The above description is merely a description of the preferred embodiment of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiment, and variations in the specific structure are permitted. Any variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor, characterized in that: The following steps are involved: The Fe3O4@SiO2 two-dimensional nanochains were ultrasonically dispersed in alcohol, then added to Sylgard184-A, stirred evenly, and dried to obtain a mother solution; Sylgard 184-A, Sylgard 184-B, a copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane, and a photoinitiator are stirred uniformly and then irradiated with ultraviolet light to obtain a base liquid; Mixing the mother liquid and the base liquid to form ink; The ink is 3D printed to obtain a wear-resistant encapsulation layer; the wear-resistant encapsulation layer includes at least two layers, and the outermost layer is oriented by a rotating magnetic field; When preparing the mother solution, the mass ratio of Fe3O4@SiO2 two-dimensional nanochains to Sylgard184-A is 2-3 mg: 2-3 g; When preparing the base liquid, the mass ratio of Sylgard 184-A, Sylgard 184-B, the copolymer of methylacetoxypropylmethylsiloxane and dimethylsiloxane and the photoinitiator is 2-3g: 0.2-0.3g: 0.5-0.7g: 0.03-0.05g.

2. The method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor according to claim 1, wherein: The photoinitiator was ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

3. The method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor according to claim 1, wherein: The mass ratio of mother liquor to base liquid is 1.25-2.25g:0.01-0.2g.

4. The method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor according to claim 1, wherein: The conditions of ultraviolet irradiation are: 365nm ultraviolet irradiation for 5s.

5. The method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor according to claim 1, wherein: The outermost layer is oriented using a rotating magnetic field, including the following steps: rotating the magnetic field for 1-5 minutes, fixing the direction of the magnetic field for 2-10 minutes, and curing after ultraviolet irradiation for 2-10 seconds.

6. The method for preparing a 3D printed wear-resistant packaging layer for a flexible sensor according to claim 5, characterized in that: The curing conditions are: temperature 120-160°C, time 5-8h.

7. A 3D printed wear-resistant packaging layer for a flexible sensor prepared according to the method of any one of claims 1 to 6, characterized in that: It consists of at least two layers, the outermost layer is a vertical layer and all other layers are horizontal layers.

8. Use of a 3D printed wear-resistant packaging layer for flexible sensors prepared according to the method according to any one of claims 1 to 6 in flexible electronic devices.

9. Application of a 3D printed wear-resistant packaging layer for flexible sensors prepared according to the method according to any one of claims 1 to 6 in wearable flexible sensors.

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