Functional gels, methods of making and using the same

Abstract

The application provides a functional gel preparation method, comprising the following steps: mixing a functional filler with liquid metal to obtain a mixture; providing a gel substrate, and forming a pre-pattern layer on the surface of the gel substrate by using the mixture as raw material, wherein the pre-pattern layer comprises a sacrificial layer and the functional filler dispersed in the sacrificial layer, and the sacrificial layer comprises the oxide of the liquid metal; providing an etching liquid, and reacting the etching liquid with the sacrificial layer to remove the sacrificial layer, so that the functional filler is deposited on the surface of the gel substrate to form a pattern layer, and a functional gel is obtained. The application also provides a functional gel and application. Since the viscosity of the oxide of the liquid metal is relatively large, the oxide can be stably attached to the surface of the gel substrate, then the sacrificial layer is consumed, and the functional filler is conformally deposited on the surface of the gel substrate, so that a functional gel with stable structure is obtained. The preparation method can overcome the difficulty that the gel substrate cannot be patterned by general semiconductor means.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible electronics, in particular to a functional gel, a preparation method and application thereof. BACKGROUND

[0002] Hydrogel has a three-dimensional network structure, can rapidly swell in a dispersion medium and is not dissolved, and due to the presence of a crosslinked network, the hydrogel can swell and retain a large amount of dispersion medium, and the absorption amount of the dispersion medium is closely related to the crosslinking degree of the hydrogel. Generally, the higher the crosslinking degree of the hydrogel, the lower the dispersion medium retention amount. The aggregate state of the hydrogel is neither completely solid nor completely liquid, the behavior of the solid state is that a certain shape and volume can be maintained under certain conditions and has a certain mechanical strength, and the behavior of the liquid state is that the solute can diffuse or permeate from the hydrogel. Based on the above characteristics of the hydrogel and the unique properties such as flexibility and biocompatibility, the hydrogel is widely researched and applied in many fields such as electrical devices, sensors and biomedicine.

[0003] Traditional semiconductor means is not suitable for patterning preparation on the surface of the hydrogel substrate, because the hydrogel material is not resistant to high temperature, and is easy to lose water and deform and shrink when encountering high temperature, and most semiconductor means needs high temperature treatment, which will cause the surface structure and geometry of the hydrogel material to change, therefore, how to effectively pattern the surface of the hydrogel material without affecting the hydrogel material is a technical problem to be solved at present. SUMMARY

[0004] In view of this, the technical problem to be solved by the present application is to provide a functional gel, a preparation method and application thereof to effectively pattern the surface of the hydrogel substrate without affecting the hydrogel substrate.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of a functional gel is provided, the preparation method comprising the following steps:

[0006] Mixing a functional filler with a liquid metal to obtain a mixture;

[0007] Providing a hydrogel substrate, and forming a pre-pattern layer on the surface of the hydrogel substrate using the mixture as raw material, wherein the pre-pattern layer comprises a sacrificial layer and the functional filler dispersed in the sacrificial layer, and the sacrificial layer comprises an oxide of the liquid metal;

[0008] Providing an etching liquid, and reacting the etching liquid with the sacrificial layer to remove the sacrificial layer, so that the functional filler is deposited on the surface of the hydrogel substrate to form a pattern layer, and a functional gel is obtained.

[0009] In one embodiment, the gel substrate is a three-dimensional network structure with holes, and the gel substrate comprises at least one of a PLA-PEG-PLA-based gel substrate, a PLGA-PEG-PLGA-based gel substrate, a methacrylated-based gelatin substrate, a poly(N-isopropylacrylamide)-based hydrogel substrate, and a polyacrylamide-based gel substrate.

[0010] In one embodiment, the step of mixing the functional filler with the liquid metal is performed in an inert atmosphere.

[0011] In one embodiment, the functional filler comprises at least one of gold particles, silver particles, platinum particles, titanium oxide, tantalum oxide, manganese oxide, tungsten oxide, lead oxide, graphene, and carbon nanotubes; and / or,

[0012] The liquid metal comprises at least one of gallium, a gallium-indium alloy, a gallium-indium-tin alloy, and a gallium-zinc alloy.

[0013] In one embodiment, the mass ratio of the functional filler to the liquid metal is (0.1-10):100.

[0014] In one embodiment, the width of the pre-patterned layer is 10 μm-5 mm; and / or,

[0015] The ratio of the thickness of the pre-patterned layer to the width of the pre-patterned layer is (1-3):4.

[0016] In one embodiment, the step of forming the pre-patterned layer on the surface of the gel substrate comprises:

[0017] The mixture is drawn on the surface of the gel substrate after oxidation treatment, and the mass ratio of the oxide of the liquid metal to the liquid metal after oxidation treatment of the mixture is (1-5):100; or

[0018] The mixture is drawn on the surface of the gel substrate and then subjected to oxidation treatment.

[0019] The drawing comprises at least one of 3D printing, spraying, and spin coating.

[0020] In one embodiment, the oxidation treatment comprises placing the mixture in an oxygen-rich condition for 5 min-10 min; and / or,

[0021] The mixture is placed in a natural condition for 10 min-30 min.

[0022] In one of the embodiments, the oxidizing treatment comprises: placing the mixture under an oxygen-rich condition and heating at a temperature of 60-100℃ for 2-8 minutes; and / or,

[0023] placing the mixture under a natural condition and heating at a temperature of 60-100℃ for 5-20 minutes.

[0024] In one of the embodiments, the step of reacting the etching liquid with the sacrificial layer to remove the sacrificial layer comprises:

[0025] injecting the etching liquid into the gel substrate or immersing a side of the gel substrate away from the pre-patterned layer into the etching liquid so that the etching liquid enters the gel substrate and penetrates to the pre-patterned layer.

[0026] In one of the embodiments, the etching liquid has a pH value of 4.0 or above and 7.0 or below; and / or,

[0027] The etching liquid comprises at least one of a sulfuric acid solution, a hydrochloric acid solution, an acetic acid solution, a hypochlorous acid solution and a sulfurous acid solution.

[0028] In one of the embodiments, the preparation method further comprises: after the etching liquid reacts with the pre-patterned layer, providing a cleaning agent so that the cleaning agent enters the gel substrate to clean the gel substrate.

[0029] According to another aspect of the present application, there is provided a functional gel prepared by any of the above-mentioned methods, which comprises the gel substrate and the pattern layer deposited on the surface of the gel substrate, and the material of the pattern layer is the functional filler.

[0030] According to still another aspect of the present application, there is provided an application of the above-mentioned functional gel in flexible sensors, biomedicine and bionic materials.

[0031] Compared with the prior art, the preparation method of the present application has the following advantages:

[0032] First, this invention disperses functional fillers in liquid metal and forms a pre-patterned layer on the surface of a gel substrate, causing at least partial oxidation of the liquid metal. Due to the high viscosity of the liquid metal oxide and its small contact angle with the gel substrate surface, it exhibits strong wettability and can adhere well and stably to the gel substrate surface. Then, an etchant reacts with the sacrificial layer to slowly consume it, and the resulting liquid metal ion compound can penetrate into the gel substrate. The functional fillers are then conformally deposited on the surface of the gel substrate, resulting in a structurally stable functional gel. This preparation method overcomes the difficulty of patterning gel substrates using conventional semiconductor methods.

[0033] Secondly, the functional gels of the present invention are all prepared at room temperature, the reaction conditions are relatively mild, and they will not affect the surface of the gel substrate. Moreover, the preparation process of the functional gels is simple and fast, and has broad application prospects.

[0034] Furthermore, the functional gel of the present invention combines the functionality of sensing or induction with flexibility, making it particularly suitable for sensing or induction applications that require a certain degree of bending and stretching. It can be widely used in many fields such as flexible sensors, biomedicine, and biomimetic materials. Attached Figure Description

[0035] Figure 1 A schematic diagram illustrating a method for preparing a functional gel according to one embodiment of the present invention;

[0036] Figure 2 for Figure 1 The flowchart shown is for the preparation of the functional gel.

[0037] Figure 3 A flowchart illustrating the preparation process of a functional gel according to another embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the structure of a flexible sensor provided in one embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the structure of a flexible sensor provided in another embodiment of the present invention. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0042] Referring to Figure 1 and Figure 2 , Figure 1 a schematic diagram of a method for preparing a functional gel according to an embodiment of the present application, Figure 2 a flow chart of a method for preparing a functional gel according to an embodiment of the present application. Figure 1 a flow chart of a method for preparing a functional gel according to an embodiment of the present application.

[0043] The method for preparing the functional gel specifically comprises the following steps:

[0044] S1: mixing a functional filler 1 with a liquid metal 2 to obtain a mixture 3;

[0045] S2: providing a gel substrate 4 and forming a pre-pattern layer 5 on the surface of the gel substrate 4 using the mixture 3 as raw material, wherein the pre-pattern layer 5 comprises a sacrificial layer and the functional filler 1 dispersed in the sacrificial layer, and the sacrificial layer comprises an oxide of the liquid metal 2;

[0046] S3: providing an etching liquid, reacting the etching liquid with the sacrificial layer to remove the sacrificial layer, so that the functional filler 1 is deposited on the surface of the gel substrate 4 to form a pattern layer 6, and a functional gel is obtained.

[0047] For a conventional flexible stretchable sensor, a liquid metal 2 is used as a flexible electrode to realize co-forming integration with a flexible substrate, but the liquid metal 2 has fluidity when used as an electrode, which can easily cause instability of electrical signals. The liquid metal 2 has poor electrical signal conduction effect and is not stable and reliable in the process of packaging application.

[0048] When the gel substrate 4 is patterned on the surface by semiconductor means such as physical deposition, chemical deposition, photolithography or etching, the three-dimensional network structure of the gel substrate 4 will be affected due to the high temperature required in the conventional semiconductor preparation process, which can easily cause the gel substrate 4 to lose water and deform, thereby affecting the gel substrate 4.

[0049] The functional filler 1 is dispersed in the liquid metal 2, and a pre-patterned layer 5 is formed on the surface of the gel substrate 4, and the liquid metal 2 is at least partially oxidized, and the oxide of the liquid metal 2 has a large viscosity, a small contact angle with the surface of the gel substrate 4, and a strong wettability, and can be well and stably attached to the surface of the gel substrate 4, then the etching liquid reacts with the sacrificial layer to slowly consume the sacrificial layer, and the generated liquid metal ion compound can enter the inside of the gel substrate 4, and the functional filler 1 is conformally deposited on the surface of the gel substrate 4, so that a functional gel with stable structure is obtained. The preparation method can overcome the difficulty that the gel substrate 4 cannot be patterned by general semiconductor means.

[0050] It is verified that the functional gel provided by the application can realize a bending angle of 90°-120° and a stretching ratio of 10%-15%, and can be well applied in many fields such as flexible sensors, biomedicine and bionic materials.

[0051] Specifically, in step S1, the gel substrate 4 has a three-dimensional network structure with holes, and the gel substrate 4 includes at least one of a PLA-PEG-PLA-based gel substrate, a PLGA-PEG-PLGA-based gel substrate, a methacrylated gelatin substrate, a poly(N-isopropylacrylamide)-based hydrogel substrate, and a polyacrylamide-based gel substrate.

[0052] The three-dimensional network structure of the gel substrate 4 helps the etching liquid to penetrate into the gel substrate 4, slowly consume the sacrificial layer on the surface of the gel substrate 4, and help solution replacement in the gel substrate 4.

[0053] In addition, since the traditional semiconductor preparation method is difficult to completely fill or cover the holes on the surface of the gel substrate 4, the functional filler 1 is prone to form a fault or poor contact on the surface of the gel substrate 4, thereby restricting the application of the gel substrate 4 sensor. The functional filler 1 is dispersed in the liquid metal 2 to form a monodisperse solution and drawn on the surface of the gel substrate 4, the liquid metal 2 has good fluidity, can completely fill or cover the holes or gullies on the surface of the gel substrate 4, the viscosity of the oxide of the liquid metal 2 becomes large after oxidation, and the oxide of the liquid metal 2 can be well and stably attached to the surface of the gel substrate 4, which helps to form a pre-patterned layer 5 on the surface of the gel substrate 4.

[0054] Specifically, considering that a functional pattern is formed on the surface of the flexible gel substrate 4, the function of the pattern can be, but is not limited to, sensing, induction or catalysis in the field of flexible application, so as to be applied to the technical field of electrical devices, sensors and biomedicine. It should be pointed out that the pattern described herein refers to a functional structure with a pattern shape formed on the surface of the flexible substrate, including but not limited to one or a combination of structures such as circuit, electrode, capacitor, dot matrix, coil, strain gauge, catalytic product, etc.

[0055] Preferably, the functional filler 1 includes at least one of gold particles, silver particles, platinum particles, titanium oxide, tantalum oxide, manganese oxide, tungsten oxide, lead oxide, graphene, carbon nanotubes, etc. The functional filler 1 is dispersed in the sacrificial layer after the pre-pattern layer 5 is formed on the surface of the gel substrate 4, and is deposited on the surface of the gel substrate 4 after the sacrificial layer is consumed by the etching liquid. There is no reaction between the functional filler 1 and the etching liquid.

[0056] Among them, gold particles, silver particles and platinum particles belong to noble metal particles and can be used for conductive sensing or induction, graphene and carbon nanotubes can also be used for conductive sensing or induction, titanium oxide and tantalum oxide can be used for catalysis, and manganese oxide, tungsten oxide and lead oxide can be used for piezoelectric sensing or induction. It should be pointed out that when the functional filler 1 includes gold particles, the functional gel prepared has higher conductive performance.

[0057] It should be pointed out that the functional filler 1 can be in linear or rod shape with high aspect ratio, or in particle shape with low aspect ratio. When the functional filler 1 is in linear or rod shape, it can be more easily connected and finally shaped when dispersed in the liquid metal 2, and the longer the aspect ratio of the filler, the more stable its performance, the larger the contact area between particles under the same volume, the better the continuity, and the more conducive to building a functional network.

[0058] Preferably, the liquid metal 2 includes at least one of gallium, gallium-indium alloy, gallium-indium-tin alloy, gallium-zinc alloy, etc. The liquid metal 2 as a sacrificial layer capable of adhering to the surface of the flexible gel substrate 4 can better disperse the functional filler 1 and has good fluidity, so as to completely fill or cover the holes or trenches during the drawing process on the surface of the gel substrate 4. In addition, the liquid metal 2 has high viscosity after oxidation so as to adhere and solidify on the surface of the gel substrate 4, and the liquid metal 2 and its oxides can react with the etching liquid to be removed from the surface of the gel substrate 4, thereby realizing the patterning of the functional filler 1 on the surface of the gel substrate 4.

[0059] In order to facilitate the monodispersion of the functional filler 1 in the liquid metal 2, the mass ratio of the functional filler 1 to the liquid metal 2 is (0.1-10):100. Preferably, the mass ratio of the functional filler 1 to the liquid metal 2 is (0.1-1):100, so that the functional filler 1 can be well monodispersed in the liquid metal 2 and form the pre-patterned layer 5 on the surface of the gel substrate 4. It should be noted that the greater the mass fraction of the functional filler 1, the higher the density of the conformal deposition of the functional filler 1 on the surface of the gel substrate 4.

[0060] In order to facilitate the dispersion of the functional filler 1 in the liquid metal 2, preferably, the stirring time of the functional filler 1 in the liquid metal 2 is 5 min-5 h, and the stirring time is related to the mass fraction of the functional filler 1. The greater the mass fraction of the functional filler 1, the longer the required stirring time.

[0061] Preferably, the step of mixing the functional filler 1 and the liquid metal 2 in step S1 is carried out in an inert atmosphere. Specifically, the functional filler 1 can be dispersed in the liquid metal 2 in a glove box to prevent the surface of the liquid metal 2 from being oxidized after being exposed to air, thereby affecting the viscosity of the liquid metal 2 and the dispersion effect of the functional filler 1 in the liquid metal 2. It can be understood that if the functional filler 1 can be quickly and uniformly dispersed in the liquid metal 2, the functional filler 1 can also be mixed in the liquid metal 2 under air conditions. Without affecting the dispersion effect of the liquid metal 2, the mixing conditions of the functional filler 1 and the liquid metal 2 are not limited in the present application.

[0062] Further, the gel substrate 4 in step S2 includes but is not limited to a hydrogel substrate, and can also be an alcohol gel substrate, a silicon gel substrate, a carbon gel substrate, a metal gel substrate, an inorganic non-metal oxide gel substrate, etc. It can be understood that without affecting the effect of the present application, the gel substrate 4 can include but is not limited to at least one of a PLA-PEG-PLA (poly lactic acid-polyethylene glycol-poly lactic acid) based gel substrate, a PLGA-PEG-PLGA (poly lactic acid-glycolic acid copolymer-polyethylene glycol-poly lactic acid-glycolic acid copolymer) based gel substrate, a methacrylated based gelatin substrate, a poly(N-isopropyl acrylamide) based hydrogel substrate, a polyacrylamide based gel substrate, etc., and the present application is not limited thereto. Since the gel substrate 4 has a three-dimensional network structure, the dispersion medium is dispersed in the three-dimensional network structure, and the inside and surface of the gel substrate 4 have pore and wrinkle structures to facilitate the penetration and replacement of the solution. It should be noted that if functional pattern drawing is required on the surface of the gel substrate 4, the pore and wrinkle structures need to be completely filled.

[0063] Further, the method of forming the pre-patterned layer 5 on the surface of the gel substrate 4 in step S2 includes, but is not limited to, at least one of 3D printing, spraying, spin coating and the like, which has a lower temperature and less impact on the surface structure of the gel substrate 4. Among them, 3D printing can be freely edited and has high precision, and can achieve a patterned precision control of 20 microns, so it is preferred to realize the patterned drawing of the surface of the gel substrate 4 by 3D printing. It should be noted that the functional filler 1 can be physically attached to the surface of the gel substrate 4 and fixed on the surface of the gel substrate 4 by relying on the physical adhesion of the liquid metal oxide itself.

[0064] Further, the width of the pre-patterned layer 5 is 10 μm-5 mm. It should be noted that the pre-patterned layer 5 formed is a layer with poor flowability and has certain viscosity, which can be relatively fixed on the surface of the gel substrate 4, and the wider the pre-patterned layer 5, the more conducive to the patterned drawing on the surface of the gel substrate 4, and the more stable the pre-patterned layer 5 obtained. The pre-patterned layer 5 can be better patterned on the surface of the gel substrate 4 within the width range, and if the drawing width of the pre-patterned layer 5 is too small, it is not conducive to its attachment to the surface of the gel substrate 4.

[0065] Preferably, the ratio of the thickness of the pre-patterned layer 5 to the width of the pre-patterned layer 5 is (1-3):4.

[0066] Preferably, the ratio of the thickness of the pre-patterned layer 5 to the width of the pre-patterned layer 5 is 1:2.

[0067] Further, the step of forming the pre-patterned layer 5 on the surface of the gel substrate 4 in step S2 further includes: drawing the mixture on the surface of the gel substrate 4 after the oxidation treatment, and the mass ratio of the liquid metal oxide to the liquid metal after the oxidation treatment of the mixture is (1-5):100. If the oxidation ratio of the liquid metal is too small, the wettability cannot be improved well, and if the oxidation ratio of the liquid metal is too large, the viscosity will be too large and not conducive to printing, spraying or spin coating and the like; or

[0068] The mixture is drawn on the surface of the gel substrate 4 and then subjected to oxidation treatment, so that only the surface of the liquid metal in contact with oxygen is subjected to oxidation reaction after drawing.

[0069] In one embodiment, the oxidation treatment includes:

[0070] placing the mixture in an oxygen-rich condition for 5-10 minutes; and / or,

[0071] placing the mixture in a natural condition for 10-30 minutes.

[0072] In another embodiment, the oxidation treatment comprises:

[0073] placing the mixture under an oxygen-rich condition and heating at a temperature of 60-100°C for 2-8 minutes; and / or,

[0074] placing the mixture under a natural condition and heating at a temperature of 60-100°C for 5-20 minutes.

[0075] It should be noted that the liquid metal 2 itself has a small viscosity, a large contact angle with the surface of the gel substrate 4, and a weak wettability, which facilitates transfer and patterned drawing; and the oxidation of the liquid metal 2 at least partially occurs by being placed under an oxygen-rich condition, being placed under a natural condition, and being heated. After the oxidation of the liquid metal 2, the oxide thereof has a large viscosity, a small contact angle with the surface of the gel substrate 4, and a strong wettability, which facilitates adhesion to the surface of the gel substrate 4. In addition, the oxide of the liquid metal 2 has a thin thickness and a high strength, and combines the electronic properties of the oxide and the high surface activity of the nanomaterial.

[0076] Further, the step of reacting the etching liquid with the sacrificial layer to remove the sacrificial layer in step S3 comprises:

[0077] injecting the etching liquid into the gel substrate 4 or immersing one side of the gel substrate 4 away from the pre-patterned layer 5 in the etching liquid, so that the etching liquid enters the gel substrate 4 and penetrates to the pre-patterned layer 5.

[0078] Specifically, the etching of the sacrificial layer is performed by immersion, and the ionized compounds of the etching liquid and the liquid metal 2 freely diffuse in the three-dimensional network structure of the gel substrate 4, which is a relatively slow process. By injection, a pressure difference or a concentration difference is formed on both sides of the gel substrate 4, which allows the etching liquid and the ionized compounds of the liquid metal 2 to quickly penetrate and replace, which is a relatively fast process.

[0079] Preferably, the pH value of the etching liquid is greater than or equal to 4.0 and less than 7.0.

[0080] Further preferably, the etching liquid comprises at least one of a sulfuric acid solution, a hydrochloric acid solution, an acetic acid solution, a hypochlorous acid solution, a sulfurous acid solution, and the like.

[0081] The top surface of the gel substrate 4 provided with the pre-patterned layer 5 is the bottom surface of the gel substrate 4. In this embodiment, the bottom surface of the gel substrate 4 is immersed in the etching solution or the etching solution is injected into the gel substrate 4. The etching solution gradually penetrates into the top surface of the gel substrate 4 through the network structure in the gel substrate 4. The sacrificial layer on the top surface of the gel substrate 4 slowly reacts with the etching solution in the gel substrate 4 and is gradually consumed to form a liquid metal ion compound. The liquid metal ion compound slowly flows into the three-dimensional network structure in the gel substrate 4. Thus, the surface of the gel substrate 4 provided with the pre-patterned layer 5 is not affected and impacted. This is helpful for the slow conformal deposition of the functional filler 1 on the surface of the gel substrate 4.

[0082] It should be noted that the etching solution of the present application only reacts with and dissolves the sacrificial layer, i.e., the mixed layer of the liquid metal 2 and the oxide thereof or the oxide layer of the liquid metal 2, and does not react with the functional filler 1 on the surface of the gel substrate 4.

[0083] Further, please refer to Figure 3 , Figure 3 The preparation flowchart of the functional gel provided by another embodiment of the present application can be seen. The preparation method of the functional gel further includes:

[0084] S4: The preparation method further includes: after the etching solution reacts with the pre-patterned layer 5, a cleaning agent is provided, and the cleaning agent enters the gel substrate 4 to clean the gel substrate 4. The pH value of the cleaning agent is 7.0-14.0.

[0085] The cleaning agent is used to neutralize or dilute the etching solution and the liquid metal ion compound in the gel substrate 4. Thus, by changing the pH value and the ratio of the components in the gel substrate 4, the liquid metal ion compound in the gel substrate 4 can be gradually discharged. Similarly, the cleaning agent can enter the gel substrate 4 by invasion or injection. The entering method of the cleaning agent is the same as that of the etching solution, which is not described herein.

[0086] Further, in order to facilitate the accurate regulation of the cleaning process of the prepared functional gel, step S4 further includes:

[0087] The gel substrate 4 is cleaned by a microfluidic system, which in this embodiment uses micro-pipes (with a size of ten to several hundred microns) to process or manipulate micro-fluids. The gel substrate 4 has a liquid circulation inside, and a cleaning agent is introduced into the micro-pipes of the microfluidic system, so that the cleaning agent enters the inside of the gel substrate 4. The pH value of the liquid circulating out of the other end of the gel substrate 4 is monitored. When the pH values of the liquid flowing into and out of the gel substrate 4 are consistent, it is considered that the etching liquid and the liquid metal ion compound inside the gel substrate 4 are basically removed; and / or,

[0088] The cleaning agent is provided to the microfluidic system by an electrochemical workstation, and the pH value of the solution flowing out of the outlet end of the gel substrate 4 is monitored by the electrochemical workstation. In this embodiment, the electrochemical workstation is connected to the microfluidic system and continuously provides a cleaning agent with a stable ratio and controllable pH value to the gel substrate 4, while monitoring the pH value, ion concentration and other parameters of the solution flowing out of the outlet end of the gel substrate 4. The above precise control means is relatively common, and the present application does not make further limitations and elaborations thereon.

[0089] One of the embodiments of the present application also includes a functional gel prepared by the above preparation method, which includes the gel substrate 4 and the pattern layer 6 deposited on the surface of the gel substrate 4, and the material of the pattern layer 6 is the functional filler 1.

[0090] Preferably, the functional filler 1 includes at least one of gold particles, silver particles, platinum particles, titanium oxide, tantalum oxide, manganese oxide, tungsten oxide, lead oxide, graphene, carbon nanotubes, etc.; and the gel substrate 4 includes at least one of a PLA-PEG-PLA-based gel substrate 4, a PLGA-PEG-PLGA-based gel substrate, a methacrylated-based gelatin substrate, a poly(N-isopropylacrylamide)-based hydrogel substrate, a polyacrylamide-based gel substrate, etc. How to select the functional filler 1 and the gel substrate 4 has been described above, and will not be elaborated here.

[0091] Further, please refer to Figure 4 and Figure 5 The present application also provides application examples of the above functional gel, Figure 4 a flexible sensor provided by one of the embodiments of the present application, Figure 5 a flexible sensor provided by another embodiment of the present application, which includes the above functional gel and an electrical element 7 encapsulated on the surface of the functional gel.

[0092] In a preferred embodiment, an electrical element can be laid on the surface of the gel substrate 4, and the electrical element 7 is encapsulated by an elastomer, and the electrical element 7 is connected to the pattern layer 6 and constitutes an electrical circuit.

[0093] Specifically, an elastomer is laid on the surface of the gel substrate 4, and then the electrical element 7 such as a connector, an electrical signal converter, etc. is laid on the elastomer, and finally a layer of elastomer is covered on the electrical element 7 to complete the encapsulation of the device, so that the electrical element 7 can be protected from the gel substrate 4 system. The electrical element 7 can be a connector, an electrical signal converter, or other.

[0094] The elastomer includes, but is not limited to, at least one of PDMS (polydimethylsiloxane) silicone and vulcanized silicone rubber, etc. It should be noted that the encapsulation described in the present embodiment can be directly laying the elastomer on the gel substrate 4, or coating the PDMS solution or the vulcanized silicone solution and curing. Since this encapsulation method is relatively conventional, the present application does not limit and elaborate on it.

[0095] In the following, in order to better understand the present application, preferred embodiments and comparative examples are listed. However, the following examples are only used to illustrate the present application, and are not limited to or by them.

[0096] Example 1:

[0097] (1) 100 parts by weight of liquid metal EGaIn (gallium-indium eutectic) was placed in a glove box, the glove box was filled with inert gas Ar, 0.1 parts by weight of gold microparticles were dispersed in the liquid metal EGaIn to form a mixture, and the stirring was continued for 1 hour in the inert gas atmosphere to achieve monodispersion of the gold microparticles in the liquid metal EGaIn, and the diameter of the gold microparticles was about 20 μm;

[0098] (2) A methacrylated gelatin substrate was provided, and the above mixture was used as a 3D printing slurry, and the mixture was drawn on the top surface of the methacrylated gelatin substrate through a 3D printer nozzle;

[0099] (3) The liquid metal EGaIn on the surface of the gel substrate was subjected to oxidation treatment, and was placed in natural conditions (in air) and heated at a temperature of 60°C for 20 min, so that the liquid metal EGaIn on the surface of the gel substrate in contact with the air was subjected to oxidation reaction and generated a corresponding oxide layer;

[0100] (4) The bottom surface of the gel substrate was immersed in a dilute hydrochloric acid solution for 0.5 hours, so that the dilute hydrochloric acid solution slowly consumed the liquid metal EGaIn and its oxide to generate a liquid metal ion compound which was dissolved into the gel substrate, and the pH value of the dilute hydrochloric acid solution was 6.0;

[0101] (5) The bottom surface of the gel substrate was immersed in deionized water for 0.5 hours to dilute the dilute hydrochloric acid solution and the liquid metal ion compound in the gel substrate;

[0102] (6) Repeat steps (4) and (5) three times until the pH of the liquid flowing into and out of the gel substrate remains consistent, ensuring that the dilute hydrochloric acid solution and liquid metal ion compound inside the gel substrate are removed, leaving the gold microparticle conformal deposition on the surface of the gel substrate.

[0103] Example 2:

[0104] (1) Put 100 parts by weight of liquid metal GaInSn into a glove box, fill the glove box with inert gas Ar, disperse 0.5 parts by weight of graphene sheets in the liquid metal GaInSn to form a mixture, and continue stirring in the inert gas atmosphere for 2 hours to achieve monodispersion of the graphene sheets in the liquid metal GaInSn;

[0105] (2) Place the mixture in an oxygen-rich condition and heat at a temperature of 60°C for 2 min to cause the liquid metal GaInSn to undergo an oxidation reaction, and the mass ratio of the oxide of the liquid metal GaInSn to the liquid metal GaInSn is 2:100;

[0106] (3) Provide a polyacrylamide-based gel substrate, and use the mixture as a 3D printing slurry, and draw the mixture on the top surface of the polyacrylamide-based gel substrate through the 3D printer nozzle;

[0107] (4) Immerse the bottom surface of the gel substrate in a dilute sulfuric acid solution for 1 hour to slowly consume the liquid metal GaInSn and its oxide in the dilute sulfuric acid solution, and the liquid metal ion compound generated by the reaction flows into the inside of the gel substrate, and the pH value of the dilute sulfuric acid solution is 5.5;

[0108] (5) Immerse the bottom surface of the gel substrate in deionized water for 1 hour to dilute the dilute sulfuric acid solution and the liquid metal ion compound in the gel substrate;

[0109] (6) Repeat steps (4) and (5) three times until the pH of the liquid flowing into and out of the gel substrate remains consistent, ensuring that the dilute sulfuric acid solution and liquid metal ion compound inside the gel substrate are removed, and the graphene sheet is conformal deposited on the surface of the gel substrate.

[0110] Example 3:

[0111] (1) Put 100 parts by weight of liquid metal gallium-indium alloy into a glove box, fill the glove box with inert gas Ar, disperse 5 parts by weight of platinum nanoparticles in the liquid metal gallium-indium alloy to form a mixture, and continue stirring in the inert gas atmosphere for 4 hours to achieve monodispersion of the platinum nanoparticles in the liquid metal gallium-indium alloy, and the diameter of the gold microparticles is approximately 10 nm;

[0112] (2) The mixture is placed in an oxygen-rich condition and heated at a temperature of 100°C for 8 min to cause the gallium-indium alloy to undergo an oxidation reaction, and the mass ratio of the oxide of the gallium-indium alloy to the gallium-indium alloy is 5:100;

[0113] (3) A poly(N-isopropyl acrylamide) based hydrogel substrate is provided, and the mixture is spin-coated on the top surface of the poly(N-isopropyl acrylamide) based hydrogel substrate;

[0114] (4) The bottom surface of the hydrogel substrate is immersed in a dilute acetic acid solution for 1 hour to cause the dilute acetic acid solution to slowly consume the liquid metal gallium-indium alloy and its oxide, and the generated liquid metal ionic compound is dissolved into the inside of the hydrogel substrate, and the pH value of the dilute acetic acid solution is 4.0;

[0115] (5) The hydrogel substrate is washed by deionized water through a microfluidic system for 1 hour to dilute the dilute acetic acid and the liquid metal ionic compound in the hydrogel substrate;

[0116] (6) Steps (4) and (5) are repeated three times until the pH of the liquid flowing into and out of the hydrogel substrate remains consistent, so as to ensure that the dilute acetic acid solution and the liquid metal ionic compound in the inside of the hydrogel substrate are removed, leaving the platinum nanoparticles conformally deposited on the surface of the hydrogel substrate.

[0117] Example 4:

[0118] (1) 100 parts by weight of a liquid metal gallium-zinc alloy is placed in a glove box, inert gas Ar is filled in the glove box, 10 parts by weight of silver nanoparticles are dispersed in the liquid metal gallium-zinc alloy to form a mixture, and the mixture is continuously stirred in an inert gas atmosphere for 5 hours to achieve monodispersion of the silver nanoparticles in the liquid metal gallium-zinc alloy;

[0119] (2) A PLA-PEG-PLA based hydrogel substrate is provided, and the mixture is sprayed on the top surface of the PLA-PEG-PLA based hydrogel substrate;

[0120] (3) The liquid metal gallium-zinc alloy on the surface of the hydrogel substrate is subjected to an oxidation treatment, and is placed in a natural condition (in air) for 30 min to cause the gallium-zinc alloy on the surface of the hydrogel substrate in contact with the air to undergo an oxidation reaction and generate a corresponding oxide layer;

[0121] (4) The bottom surface of the hydrogel substrate is immersed in a dilute hypochlorous acid solution for 0.5 hours to cause the dilute hypochlorous acid solution to slowly consume the liquid metal gallium-zinc alloy and its oxide, and the reaction generated liquid metal ionic compound flows into the inside of the hydrogel substrate, and the pH value of the dilute hypochlorous acid solution is 5.0;

[0122] (5) The gel substrate is cleaned by an electrochemical workstation with a dilute potassium hydroxide solution with a pH value of 7.5, and soaked for 0.5 hours to dilute the dilute hypochlorous acid and liquid metal ion compound in the gel substrate;

[0123] (6) Steps (4) and (5) are repeated three times until the pH of the liquid flowing in and out of the gel substrate remains consistent, so as to ensure that the dilute hypochlorous acid solution and liquid metal ion compound in the gel substrate are removed, and silver nanoparticles are conformally deposited on the surface of the gel substrate.

[0124] Example 5:

[0125] This example is basically the same as Example 1, except that in step (1), 0.1 parts by weight of carbon nanotube particles are dispersed in the liquid metal EGaIn to form a mixture.

[0126] Example 6:

[0127] (1) 100 parts by weight of liquid metal gallium is placed in a glove box filled with inert gas Ar, 1 part by weight of titanium dioxide nanoparticles is dispersed in the liquid metal gallium to form a mixture, and the mixture is continuously stirred for 5 hours in an inert gas atmosphere to achieve monodispersion of the titanium dioxide nanoparticles in the liquid metal gallium;

[0128] (2) A PLGA-PEG-PLGA-based gel substrate is provided, and the above mixture is used as a 3D printing slurry, and the mixture is drawn on the top surface of the PLGA-PEG-PLGA-based gel substrate through the nozzle of a 3D printer;

[0129] (3) The liquid metal gallium on the surface of the gel substrate is oxidized by placing it in natural conditions for 10 min, so that the liquid metal gallium on the surface of the gel substrate in contact with the air is oxidized to form a corresponding oxide layer;

[0130] (4) The bottom surface of the gel substrate is immersed in a dilute sulfurous acid solution for 0.5 hours to slowly consume the liquid metal gallium and its oxides, and the liquid metal ion compound generated by the reaction flows into the gel substrate, and the pH value of the dilute sulfurous acid solution is 6.5;

[0131] (5) The gel substrate is cleaned by a microfluidic system with a dilute sodium hydroxide solution with a pH value of 8.0, and soaked for 0.5 hours to dilute the dilute sulfurous acid and liquid metal ion compound in the gel substrate;

[0132] (6) Repeat steps (4) and (5) three times until the pH of the liquid flowing into and out of the gel substrate remains consistent, ensuring that the dilute sulfurous acid solution and liquid metal ion compound inside the gel substrate are removed, and achieving conformal deposition of titanium dioxide nanoparticles on the surface of the gel substrate.

[0133] Example 7:

[0134] This example is basically the same as Example 6, except that in step (1), 0.1 parts by weight of tantalum oxide particles are dispersed in the liquid metal EGaIn to form a mixture.

[0135] Example 8:

[0136] This example is basically the same as Example 1, except that in step (1), 0.1 parts by weight of manganese oxide particles are dispersed in the liquid metal EGaIn to form a mixture.

[0137] Example 9:

[0138] This example is basically the same as Example 1, except that in step (1), 0.1 parts by weight of tungsten oxide particles are dispersed in the liquid metal EGaIn to form a mixture.

[0139] Example 10:

[0140] This example is basically the same as Example 1, except that in step (1), 0.1 parts by weight of lead oxide particles are dispersed in the liquid metal EGaIn to form a mixture.

[0141] Please continue to refer to Figure 4 The functional gel prepared in Example 1 and Example 2 is respectively electrically connected with the electrical element laid on the gel substrate 4, and the electrical element is encapsulated by PDMS flexible material to prepare a flexible sensor. The flexible sensor is attached to the knee, and during the knee movement, the stretching action will affect the capacitance of the flexible sensor, thereby enabling the measurement of the knee movement condition.

[0142] Please continue to refer to Figure 5 The functional gel prepared in Example 3 and Example 4 is respectively electrically connected with the electrical element 7 laid on the gel substrate 4, and the electrical element 7 is encapsulated by vulcanized silicone rubber to prepare a flexible sensor. The flexible sensor is attached to the forehead, and as the temperature changes, the resistance of the flexible sensor will also change, thereby enabling the measurement of the forehead temperature.

[0143] In addition, the functional gel prepared in Example 5 can be used as a capacitive sensor and energized to detect the capacitive signal on the flexible object.

[0144] The functional gel prepared in Example 6 and Example 7 can also be wrapped around an ultraviolet lamp, and a volatile compound is introduced, and the functional gel can decompose the volatile compound into small molecules to remove the volatile compound.

[0145] The functional gel prepared in Example 8 to Example 10 is also connected with a sensor and a piezoelectric sensor is prepared to detect a piezoelectric signal on a flexible object.

[0146] The functional gel prepared in the above examples has good sensing or sensing function and good flexibility, and thus has wide application in the fields of flexible sensors, biomedicine, bionic materials and the like.

[0147] The technical features of the above-described examples can be combined in any manner, and for the sake of brevity, all possible combinations of the technical features in the above examples are not described, but as long as the combination of the technical features does not exist, it should be considered as the scope of the description.

[0148] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a functional gel, characterized in that, The preparation method includes the following steps: A mixture is obtained by mixing a functional filler with a liquid metal, wherein the functional filler includes at least one of gold particles, silver particles, platinum particles, titanium oxide, tantalum oxide, manganese oxide, tungsten oxide, lead oxide, graphene, and carbon nanotubes, and the liquid metal includes at least one of gallium, gallium-indium alloy, gallium-indium-tin alloy, and gallium-zinc alloy. A gel substrate is provided, and a pre-patterned layer is formed on the surface of the gel substrate using the mixture as a raw material, wherein the pre-patterned layer includes a sacrificial layer and the functional filler dispersed in the sacrificial layer, and the sacrificial layer includes an oxide of the liquid metal; An etchant is provided, which reacts with the sacrificial layer to remove the sacrificial layer, thereby depositing the functional filler on the surface of the gel substrate to form a patterned layer, thus obtaining a functional gel. The step of forming the pre-patterned layer on the surface of the gel substrate includes: The mixture is then oxidized and drawn onto the surface of the gel substrate; or The mixture is drawn onto the surface of the gel substrate and then subjected to oxidation.

2. The method for preparing the functional gel according to claim 1, characterized in that, The gel substrate is a three-dimensional network structure with pores, and the gel substrate includes at least one of PLA-PEG-PLA-based gel substrate, PLGA-PEG-PLGA-based gel substrate, methacrylic anhydride-based gelatin substrate, poly(N-isopropylacrylamide)-based hydrogel substrate, and polyacrylamide-based gel substrate.

3. The method for preparing the functional gel according to claim 1, characterized in that, The step of mixing the functional filler with the liquid metal is carried out in an inert atmosphere.

4. The method for preparing the functional gel according to claim 1, characterized in that, The mass ratio of the functional filler to the liquid metal is (0.1~10):

100.

5. The method for preparing the functional gel according to claim 1, characterized in that, The width of the pre-formed pattern layer is 10μm~5mm; and / or, The ratio of the thickness of the pre-formed pattern layer to the width of the pre-formed pattern layer is (1~3):

4.

6. The method for preparing the functional gel according to claim 1, characterized in that, After the mixture is oxidized, the mass ratio of the oxide of the liquid metal to the liquid metal is (1~5):

100.

7. The method for preparing the functional gel according to claim 1, characterized in that, The drawing process includes at least one of 3D printing, spraying, and spin coating.

8. The method for preparing the functional gel according to claim 1, characterized in that, The oxidation treatment includes: placing the mixture under oxygen-rich conditions for 5 to 10 minutes; and / or, Place the mixture under natural conditions for 10 to 30 minutes.

9. The method for preparing the functional gel according to claim 1, characterized in that, The oxidation treatment includes: placing the mixture under oxygen-rich conditions and heating it at a temperature of 60°C to 100°C for 2 to 8 minutes; and / or, The mixture was placed under natural conditions and heated at a temperature of 60°C to 100°C for 5 to 20 minutes.

10. The method for preparing the functional gel according to claim 1, characterized in that, The step of removing the sacrificial layer by reacting the etchant with the sacrificial layer includes: The etching solution is injected into the gel substrate or the side of the gel substrate away from the pre-patterned layer is immersed in the etching solution, so that the etching solution enters the gel substrate and penetrates into the pre-patterned layer.

11. The method for preparing the functional gel according to claim 10, characterized in that, The pH value of the etching solution is greater than or equal to 4.0 and less than 7.0; and / or, The etching solution includes at least one of sulfuric acid solution, hydrochloric acid solution, acetic acid solution, hypochlorous acid solution, and sulfurous acid solution.

12. The method for preparing the functional gel according to claim 1, characterized in that, The preparation method further includes: after the etching solution reacts with the pre-patterned layer, providing a cleaning agent to allow the cleaning agent to enter the gel substrate for cleaning the gel substrate.

13. A functional gel, characterized in that, The functional gel is prepared by the method according to any one of claims 1 to 12, the functional gel comprising the gel substrate and the patterned layer deposited on the surface of the gel substrate, wherein the material of the patterned layer is the functional filler.

14. The application of the functional gel as described in claim 13 in flexible sensors, biomedicine, and biomimetic materials.

Images