Conductive hydrogel preparation method based on photocuring 3D printing technology
By combining DLP 3D printing technology and resistance detection circuit with a conductive hydrogel preparation method using magnesium chloride and sodium chloride, the problems of dispersion and shape preparation of conductive hydrogels have been solved, enabling efficient and sensitive applications of conductive hydrogels.
Patent Information
- Application Number
- CN202410956130.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-17
- Publication Date
- 2026-01-20
AI Technical Summary
Existing methods for preparing conductive hydrogels suffer from problems such as uneven dispersion of conductive materials and difficulty in preparing specific geometries, as well as insufficient sensitivity and stability.
Conductive hydrogels were prepared by photopolymerization 3D printing using DLP 3D printing technology combined with dissolved magnesium chloride and sodium chloride in polyacrylamide hydrogels and a resistance detection circuit. The topology of the hydrogels was also designed.
This invention enables the efficient and simple preparation of conductive hydrogels, improves sensitivity and stability, and allows for the detection of resistance changes, making it suitable for wearable devices and robotics.
Smart Images
Figure CN121362347A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to 3D printing technology and sensor technology, and in particular to a conductive hydrogel preparation method based on light-cured 3D printing technology. BACKGROUND
[0002] Conductive hydrogel combines the excellent characteristics of high elasticity of hydrogel and good conductivity of magnesium and sodium ions, and has wide application prospects in many aspects. Conductive hydrogel is usually mixed with highly water-soluble polymers and carbon-based nanomaterials such as graphene, metal nanowires and conductive ions to make the hydrogel have conductive properties. These conductive hydrogels have been applied in many fields, such as flexible sensors, electrically stimulated drug delivery, etc.
[0003] Although conductive hydrogel has shown excellent application prospects, there are still some problems in its preparation. First, graphite and metal nanowires can be used as conductive materials to prepare conductive hydrogel with excellent conductive properties, but graphite and other materials have strong intermolecular forces, which are difficult to disperse uniformly in the hydrogel, and complex steps are needed for dispersion. Such solid particles also affect the stability of the hydrogel. Using ionic hydrogel as a conductive material can reduce the complex preparation steps and prepare a better conductive hydrogel. Second, the preparation of conductive hydrogel with specific geometric shape is still a great challenge. 3D printing technology can be used to prepare models with customized topological structure and specific functions. The current 3D printing technology with wide application and high precision is based on light-cured printing. Compared with SLA stereolithography technology, DLP 3D printing technology uses face projection printing method, which has faster printing speed. The precision of LCD 3D printer is in the order of hundreds of microns, while the precision of DLP 3D printing using DMD chip projection can reach microns. Using DLP 3D printing technology can realize rapid and high-precision preparation of conductive hydrogel.
[0004] The above-mentioned application prepares a conductive hydrogel based on DLP 3D printing technology, and designs a detection circuit to detect the resistance change generated by the deformation of the conductive hydrogel. In the future, it can be applied in wearable devices and robots through integration and wireless communication technology, and used for detecting motion and motion signals. SUMMARY
[0005] The purpose of the present application is to solve the shortcomings of the existing method in sensitivity and stability, and to develop a 3D printable conductive hydrogel. By dissolving magnesium chloride and sodium chloride in polyacrylamide hydrogel, the hydrogel is conductive. Combined with DLP 3D printing technology, it can simply and efficiently prepare conductive hydrogel with topological structure, and detect the resistance signal by using a resistance detection circuit.
[0006] The present application achieves the above-mentioned purpose by the following scheme: The present application comprises the following contents: Conductive hydrogel preparation steps: Step 1, under the condition of light shielding and ambient temperature of 20-25℃, weigh glycerol, acrylamide, magnesium chloride, sodium chloride, poly(ethylene glycol) diacrylate and photoinitiator, dissolve them in deionized water, and add rhodamine B to mix uniformly to obtain a light-cured printing ink; Step 2, design a three-dimensional digital model of the hydrogel boss structure and import it into the slicing software of a light-cured 3D printer, and set relevant printing parameters; Step 3, use a light-cured 3D printer to print the hydrogel boss structure, take out the hydrogel after printing, wipe the residual printing ink on the surface, and clean it with alcohol, and then perform post-processing by irradiation under 405nm ultraviolet light.
[0007] The conductive hydrogel preparation method of the light-cured 3D printing technology in Step 1 is as follows: First, place deionized water in a beaker, add glycerol, place the beaker on a magnetic stirrer, and stir for 5-10 minutes. After the glycerol is completely dissolved in the deionized water, weigh the acrylamide powder and add it to the beaker, and continue stirring for 30-60 minutes. After the acrylamide is completely dissolved, add magnesium chloride and sodium chloride and continue stirring for 10-15 minutes. After the magnesium chloride and sodium chloride are completely dissolved, add poly(ethylene glycol) diacrylate, photoinitiator and rhodamine B, and continue stirring for 10-15 minutes. After all the ingredients are completely dissolved and uniformly mixed, the printing ink is a light red transparent liquid. The light-cured printing ink preparation is completed.
[0008] The poly(ethylene glycol) diacrylate in Step 1 has a molecular weight of 200-600 daltons, and the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide.
[0009] The slicing software in Step 2 is set to single-layer printing with a layer thickness of 0.03-0.05mm, a single-layer printing time of 4.5-13s, a bottom layer number of 4-6 layers, a bottom layer printing time of 6-20s, a lifting speed of 60-80mm / min, and a return speed of 150-170mm / min.
[0010] In the preparation process of the light-cured printing ink, the mass ratio of each material to deionized water is as follows: glycerol 0.1-0.8g / mL, acrylamide 0.6-0.8g / mL, magnesium chloride 0.3-0.6g / mL, sodium chloride 0.05-0.1g / mL, poly(ethylene glycol) diacrylate 0.002-0.007g / mL, photoinitiator 0.002-0.01g / mL, and rhodamine B 0-0.001g / mL.
[0011] The resistance detection circuit is used to collect the data of the conductive hydrogel and display the resistance data in real time, and finally store the resistance data. BRIEF DESCRIPTION OF DRAWINGS
[0012] Figure 1 Fig. 1 is a three-dimensional model diagram of the conductive hydrogel with a boss structure according to Embodiment 1, 2 or 3; Figure 2 Fig. 3 is an enlarged diagram of the conductive hydrogel with a boss structure according to Embodiment 3; Figure 3 Fig. 4 is a diagram of the conductive hydrogel with a rectangular block structure according to Embodiment 3 without stretching; Figure 4 Fig. 5 is a diagram of the conductive hydrogel with a rectangular block structure according to Embodiment 3 with stretching; Figure 5 Fig. 6 is a diagram of the corresponding resistance change of the conductive hydrogel with a rectangular block structure according to Embodiment 3 with stretching; Figure 6 Fig. 7 is a diagram of the bending experiment curve of the conductive hydrogel with a rectangular block structure according to Embodiment 3; DETAILED DESCRIPTION
[0013] The preparation method in the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. The described embodiments are only some of the embodiments in the present application, not all the embodiments. Other embodiments obtained by those skilled in the art on the basis of the embodiments in the present application without creative labor are within the scope of protection of the present application.
[0014] The preparation method of the conductive hydrogel of a photocuring 3D printing technology comprises the following steps: selecting poly(ethylene glycol) diacrylate as a crosslinking agent, acrylamide as a monomer, and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (light initiator 819) as a light initiator to form a photocrosslinking system hydrogel. Using poly(ethylene glycol) diacrylate as a crosslinking agent can adjust the crosslinking density and the mechanical properties of the hydrogel system; sequentially introducing glycerol, magnesium chloride, sodium chloride and rhodamine B into the printing ink to improve the water retention of the hydrogel, obtain the conductive ability, and have better printing precision and printing speed. The hydrogel is observed by a microscope, and the real-time image and data are used to evaluate the conductive performance of the hydrogel. Specifically, the method comprises the following steps: Step 1: Preparation of printing ink Take the appropriate amount of deionized water and glycerol solution, add beaker, beaker on the magnetic stirrer for stirring, stirring time is 5~10 minutes, until the glycerol completely dissolved in deionized water; weigh acrylamide powder, add beaker, heated with magnetic stirrer for 3~5 minutes, stop heating, continue stirring for 30~60 minutes, until the acrylamide in the solution is completely dissolved, acrylamide powder purity ≥ 99%; add magnesium chloride and sodium chloride powder to the beaker, continue stirring for 10~15 minutes, after the magnesium chloride and sodium chloride powder is completely dissolved, drop poly(ethylene glycol)diacrylate, add photoinitiator and rhodamine B, continue stirring for 10~15 minutes, complete the preparation of printing ink, the prepared printing ink is stored in the dark, wherein the purity of magnesium chloride and sodium chloride is ≥98%.
[0015] Step 2: 3D printing model preparation The computer software is used for printing model structure design, and the rectangular block and boss structure are designed. The printing parameter setting is completed by the light curing 3D printer slicing software. The printing ink is added to the printer hopper, and 3D printing is carried out. After printing, alcohol is used for cleaning, and post-processing is carried out under 405 nm ultraviolet lamp, to complete the preparation of high-precision, microstructure conductive hydrogel.
[0016] Step 3: mechanical property and conductivity test After testing, the tensile rate of the conductive hydrogel can reach 500%, and the resistivity can reach 75kΩ / cm. The hydrogel is attached to the finger joint, the finger joint is bent, and the resistance signal of the conductive hydrogel is detected by the detection circuit. The image is shown as Figure 6 .
[0017] In step 2, the printing parameter setting of the conductive hydrogel is shown in the following table Printing parameters Single layer thickness (mm) Single layer exposure time (s) Number of base layers Base layer exposure time (s) Lift speed (mm / min) Return speed (mm / min) Parameter range 0.03-0.05 4.5-13 4-6 6-20 60-80 150-170 Example 1 (1) Preparation of printing ink First, 6g of acrylamide is added to 10ml of deionized water and heated and stirred for 30 minutes. 4g of magnesium chloride and 1g of sodium chloride are added and continue to stir for 15 minutes. Finally, 0.02g of poly(ethylene glycol)diacrylate, 0.02g of photoinitiator 819, are added and stirred for 15 minutes to complete the preparation of printing ink.
[0018] (2) Preparation of 3D printed conductive hydrogel The rectangular block and prism structure are designed by Solidworks software. The rectangular block is 10mm×5mm×2mm, the boss structure has a base size of 10mm×10mm×0.3mm, the top boss size is 0.15mm×0.15mm on the top surface, the bottom surface is 0.4mm×0.4mm, and the boss height is 0.5mm. The model is as followsFigure 1 As shown, the boss model was exported as an STL file, imported into the slicing software for printing parameter settings, and then exported as a CBT file. The file was imported into the printer using a USB flash drive. The prepared printing ink was poured into the printer's ink tank for 3D printing. After printing, the model was cleaned with alcohol and post-processed under a 405nm UV lamp to complete the preparation of a high-precision conductive hydrogel with microstructures. The printing parameters of the conductive hydrogel are shown in the table below. Printing parameters Single layer thickness (mm) Single layer exposure time (s) Number of base layers Base layer exposure time (s) Lift speed (mm / min) Return speed (mm / min) Parameter range 0.04 13 4 20 60 150 The conductive hydrogel obtained above has an ultimate tensile strength of 500%. The conductive hydrogel loses water, shrinks and deforms, and loses its elasticity within 8 hours.
[0019] Conductive hydrogel was applied to the finger joints, and the resistance signal of the conductive hydrogel was detected under different degrees of finger bending. Example 2
[0020] (1) Printing ink preparation First, add 15g of acrylamide to 15ml of deionized water and heat and stir for 30 minutes. Then add 5g of magnesium chloride and 1g of sodium chloride and continue stirring for 15 minutes. Finally, add 0.05g of polyethylene glycol diacrylate, 0.08g of photoinitiator 819, and 0.01g of rhodamine B and stir for 15 minutes to complete the preparation of the printing ink.
[0021] (2) Preparation of 3D printed conductive hydrogels Design a rectangular block and prism structure using Solidworks software. The rectangular block measures 10mm × 5mm × 2mm. The base of the boss structure measures 10mm × 10mm × 0.3mm, the top boss measures 0.15mm × 0.15mm for the top surface, 0.4mm × 0.4mm for the bottom surface, and the boss height is 0.5mm. The model is shown below. Figure 1 As shown, the boss model was exported as an STL file, imported into the slicing software for printing parameter settings, and then exported as a CBT file. The file was imported into the printer using a USB flash drive. The prepared printing ink was poured into the printer's ink tank for 3D printing. After printing, the model was cleaned with alcohol and post-processed under a 405nm UV lamp. This completed the preparation of a high-precision conductive hydrogel with microstructures. The printing parameters for the conductive hydrogel are shown in the table below. Printing parameters Single layer thickness (mm) Single layer exposure time (s) Number of base layers Base layer exposure time (s) Lift speed (mm / min) Return speed (mm / min) Parameter range 0.03 6 6 8 80 170 The conductive hydrogel obtained above has an ultimate tensile strength of 400%. The conductive hydrogel loses water, shrinks and deforms, and loses its elasticity within 8 hours.
[0022] Repeat the resistance signal detection operation in Example 1. Example 3
[0023] (1) Printing ink preparation First, add 8 ml of glycerol to 10 ml of deionized water and stir for 10 minutes. Weigh 20 g of acrylamide and add it to the solution. Heat and stir for 5 minutes, then stop heating and continue stirring for 1 hour. Add 4 g of magnesium chloride and 1 g of sodium chloride and continue stirring for 15 minutes. Finally, add 0.07 g of poly(ethylene glycol) diacrylate, 0.1 g of photoinitiator 819, and 0.01 g of rhodamine B and stir for 15 minutes to complete the preparation of the printing ink.
[0024] (2) Preparation of 3D printed conductive hydrogels Design a rectangular block and prism structure using Solidworks software. The rectangular block measures 10mm × 5mm × 2mm. The base of the boss structure measures 10mm × 10mm × 0.3mm, the top boss measures 0.15mm × 0.15mm for the top surface, 0.4mm × 0.4mm for the bottom surface, and the boss height is 0.5mm. The model is shown below. Figure 1 The protrusion model was exported as an STL file, imported into the CHITUBOX slicing software for printing parameter settings, and then exported as a CBT file. The file was then imported into the printer using a USB flash drive. The printing ink prepared in step 1 was poured into the printer's ink tank for 3D printing. After printing, the print was cleaned with alcohol and post-processed under a 405nm UV lamp to complete the preparation of a high-precision conductive hydrogel with microstructures. The printing parameters for the conductive hydrogel are shown in the table below. Printing parameters Single layer thickness (mm) Single layer exposure time (s) Number of base layers Base layer exposure time (s) Lift speed (mm / min) Return speed (mm / min) Parameter range 0.03 5.5 4 6 80 170 The conductive hydrogel structure obtained above is as follows Figure 2 As shown, the ultimate tensile strength of the conductive hydrogel is 350%. Figure 3 , 4 As shown, the conductive hydrogel remains elastic within 24 hours, with shrinkage and deformation of less than 5%.
[0025] Repeat the resistance signal detection operation in Example 1.
[0026] In summary, the present invention provides a method for preparing conductive hydrogels using photopolymerization 3D printing technology. Through the above embodiments, it can be seen that by using poly(ethylene glycol) diacrylate as a crosslinking agent, glycerol as a humectant, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide as a photoinitiator, rhodamine B as a photoinhibitor, and magnesium chloride and sodium chloride as conductive fillers, and adjusting the ratio of acrylamide and various materials as well as the printer's printing parameters, conductive hydrogels can be prepared using DLP 3D printing. Furthermore, the resistance change generated during the deformation of the conductive hydrogel can be detected.
[0027] Figure 2The image shown is a magnified view of the details of the hydrogel 3D printed in Example 3 of this invention, demonstrating that this method can produce complex three-dimensional structures.
[0028] Figure 5 The bar chart shows the resistance change during stretching of the rectangular conductive hydrogel prepared in Example 3, collected using a multimeter.
[0029] Figure 6 In Example 3, a rectangular conductive hydrogel was prepared, encapsulated with VHB tape, and then attached to a finger. When the finger is bent, a corresponding resistance change is generated. The detection circuit can detect the finger bending signal by the change in resistance signal during the bending process.
[0030] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can make improvements and modifications to the above embodiments without departing from the spirit and scope of the present invention. Therefore, any modifications that may be made to certain parts by those skilled in the art embody the principles of the present invention and fall within the protection scope of the present invention.
Claims
1. A method for preparing conductive hydrogels based on photopolymerization 3D printing technology, comprising: Step 1: Under light-protected conditions and an ambient temperature of 20°C to 25°C, weigh out glycerol, acrylamide, magnesium chloride, sodium chloride, poly(ethylene glycol) diacrylate and photoinitiator, dissolve them in deionized water, and add Rhodamine B to mix evenly to obtain photocurable printing ink. Step 2: Design a 3D digital model of the hydrogel boss structure, import it into the slicing software of the photopolymer 3D printer, and set the relevant printing parameters; Step 3: Print the hydrogel boss structure using a photopolymer 3D printer. After printing, remove the hydrogel, wipe off any residual printing ink on the surface, clean it with alcohol, and finally perform a post-treatment by irradiation under 405nm ultraviolet light.
2. The method according to claim 1, wherein the specific preparation process of the photocurable printing ink in step 1 is as follows: First, deionized water is placed in a beaker, glycerol is added, the beaker is placed on a magnetic stirrer and stirred for 5-10 minutes. After the glycerol is completely dissolved in the deionized water, acrylamide powder is weighed and added to the beaker and stirred for 30-60 minutes. After the acrylamide is completely dissolved, magnesium chloride and sodium chloride are added and stirred for 10-15 minutes. After the magnesium chloride and sodium chloride are completely dissolved, poly(ethylene glycol) diacrylate, photoinitiator and rhodamine B are added and stirred for 10-15 minutes. After all the components are completely dissolved and uniformly mixed, the printing ink is a light red transparent liquid, and the photocurable printing ink is prepared.
3. The method according to claim 1, wherein the poly(ethylene glycol) diacrylate in step 1 has a molecular weight of 200-600 Daltons, and the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator 819).
4. The method according to claim 1, wherein the slicing software parameters in step 2 are set as follows: single-layer printing thickness is 0.03~0.05mm, single-layer printing time is 4.5~13s, number of bottom layers is 4~6, bottom layer printing time is 6~20s, lifting speed is 60~80mm / min, and return speed is 150~170mm / min.
5. According to the specific preparation process of the photocurable printing ink in claim 2, the mass ratio of each material to the solvent deionized water is as follows: glycerol 0.1-0.8 g / mL, acrylamide 0.6-0.8 g / mL, magnesium chloride 0.3-0.6 g / mL, sodium chloride 0.05-0.1 g / mL, poly(ethylene glycol) diacrylate 0.002-0.007 g / mL, photoinitiator 0.002-0.01 g / mL, and rhodamine B 0.001 g / mL.