Method for in-situ photocuring of 3D printing hydrogel on surface of PDMS and application
By doping hydrophobic photoinitiator on the surface of PDMS and performing oxygen plasma treatment, a hydrophilic surface is formed, and a hydrogel coating is formed on the PDMS surface through photocrosslinking, the in-situ photocuring of hydrogel and PDMS is achieved, solving the problem of hydrogel shifting or falling off, and improving design flexibility and production efficiency.
Patent Information
- Application Number
- CN202510266207.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-06-27
AI Technical Summary
The prior art has the problem of hydrogel shifting or falling off when in situ photocuring of 3D printed hydrogel structures on PDMS surface. The traditional combination method limits the design freedom and the singularity of product components, and the process complexity is high, making it difficult to achieve high-precision and large-scale production.
By doping a hydrophobic photoinitiator to the surface of the PDMS, a doped surface layer is formed and oxygen plasma treatment is performed to form a hydrophilic surface. Then, the hydrogel monomer, hydrophilic photoinitiator, and light absorber are mixed with water to form a hydrogel prepolymer, and a hydrogel coating is formed on the PDMS surface by photocrosslinking to achieve in-situ photocuring of the hydrogel and PDMS.
The problem of hydrogel shifting or falling off on the PDMS surface is solved, the design flexibility is improved, the introduction of additional materials is avoided, the singleness of product components is ensured, manual intervention is reduced, and production efficiency and automation level is improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photocuring 3D printing, and particularly to a technique for in-situ photocuring 3D printing of hydrogel materials on the surface of polydimethylsiloxane (PDMS). Background Art
[0002] Polydimethylsiloxane (PDMS) is an elastic polymer with excellent anti-biodegradability, biocompatibility, chemical stability, gas permeability, good mechanical properties, excellent optical transparency, and easy molding and manufacturing. It has been widely used in application scenarios such as micropumps and microvalves, dressings and bandages, microfluidic chips and organ chips, and electrical encapsulation.
[0003] Due to their physical and chemical properties and stimulus responsiveness, hydrogels play a crucial role in various application fields. The three-dimensional polymer network structure of hydrogels is considered a substitute for many materials, such as conductors, sensor sensitive elements, wound dressings, extracellular matrices, and flexible robot components.
[0004] In recent years, the application of hydrogel materials in 3D printing has gradually increased. Its advantage lies in the ability to prepare hydrogel structures with complex geometric shapes and microstructures, while achieving high-precision and high-resolution printing. Also, due to the advantages of high biocompatibility, easy three-dimensional structuring, high water content, adjustable mechanical properties, and easy cell attachment of hydrogels, hydrogel 3D printing has broad application prospects in research fields such as tissue engineering and regenerative medicine, drug delivery, wound care, biochips, and microfluidic devices.
[0005] The technology of 3D printing hydrogels on PDMS can bring new opportunities and challenges to fields such as materials science and biomedicine. By combining the unique properties of both, materials or structures with new functions and characteristics can be prepared, providing strong support for the development of fields such as personalized medicine, biofabrication, and flexible electronics.
[0006] The current mainstream combination strategy, that is, transferring the printed hydrogel structure to the PDMS substrate and then fixing it through traditional means such as structural interlocking and applying adhesives, although achieving the combination of the two to a certain extent, exposes several limitations. These methods limit the structural morphology of hydrogels or PDMS in terms of design freedom, and also affect the simplicity and biocompatibility of the final product composition due to the introduction of additional materials. More critically, these steps highly rely on manual operations, increasing the process complexity, thus limiting their application in high-precision and large-scale production. Therefore, the demand for a more efficient and direct combination method - in-situ photocuring 3D printing of hydrogels on the PDMS surface is becoming increasingly urgent.
[0007] Stereolithography 3D printing technology requires that the printing material has good adhesion to the printing substrate, that is, during the stereolithography 3D printing process, the printing material needs to adhere tightly to the printing platform to ensure the smooth progress of the printing process and the integrity of the final product. However, the rich water content in the hydrogel poses a special challenge to adhesion, and it is almost impossible to combine the water molecules in the hydrogel with other materials. On the other hand, PDMS is permeable to oxygen, which inhibits the free radical polymerization of the hydrogel, resulting in the inability of the hydrogel prepolymer on the PDMS surface to cure. The above problems have hindered the realization of the in-situ stereolithography 3D printing of hydrogels on the PDMS surface. Summary of the Invention
[0008] In view of the deficiencies of the existing technology, the present invention provides a method and application for in-situ stereolithography 3D printing of hydrogels on the PDMS surface.
[0009] To achieve the above objectives, the technical solution of the present invention is as follows:
[0010] A method for in-situ stereolithography 3D printing of hydrogels on the PDMS surface, which includes the following steps:
[0011] (1) Dope a hydrophobic photoinitiator to a certain depth on the surface of the PDMS solid polymer to form a doped surface layer, obtaining a PDMS substrate with a hydrophobic photoinitiator doping;
[0012] (2) Perform oxygen plasma treatment on at least part of the surface of the doped surface layer of the PDMS substrate with a hydrophobic photoinitiator doping to obtain a PDMS substrate with a hydrophilic surface;
[0013] (3) Mix a hydrogel monomer, a hydrophilic photoinitiator, a light absorber, and water to obtain a hydrogel prepolymer;
[0014] (4) Add the hydrogel prepolymer to the hydrophilic surface of the PDMS substrate to form a hydrogel liquid film, and perform photocrosslinking by simultaneously exciting the hydrophobic photoinitiator and the hydrophilic photoinitiator to form a PDMS substrate with a hydrogel coating;
[0015] (5) Transfer the PDMS substrate with a hydrogel coating to the printing platform of a stereolithography 3D printer, and use the hydrogel prepolymer to perform stereolithography 3D printing on the hydrogel coating.
[0016] Optionally, step (1) includes:
[0017] (1.3) Dissolve the hydrophobic photoinitiator in an organic solvent to form an organic solution containing the hydrophobic photoinitiator;
[0018] (1.4) Immerse the PDMS solid polymer in an organic solution containing a hydrophobic photoinitiator. After the organic solution containing the hydrophobic photoinitiator swells the surface of the PDMS solid polymer to a certain depth, take it out and wash it to form the doped surface layer.
[0019] Optionally, the hydrophobic photoinitiator is at least one of benzophenone and trimethylbenzoyl-diphenylphosphine oxide, and the organic solvent is at least one of ethanol and acetone; the mass ratio of the hydrophobic photoinitiator to the organic solvent is (0.03 - 0.2):1.
[0020] Optionally, the time for immersing the PDMS solid polymer in the organic solution containing the hydrophobic photoinitiator is 15 s - 45 min.
[0021] Optionally, in step (2), a patterned masking layer is formed on the surface of the doped surface layer, and then oxygen plasma treatment is carried out to obtain a PDMS substrate with a patterned hydrophilic surface.
[0022] Optionally, the power of the oxygen plasma treatment is 60 - 400 W, the gas flow rate is 50 - 500 ml / min, and the treatment time is 10 - 600 s.
[0023] Optionally, the hydrogel monomer is at least one of acrylamide, polyethylene glycol diacrylate, and methacrylated gelatin, and the hydrophilic photoinitiator is at least one of lithium phenyl-2,4,6-trimethylbenzoylphosphinate and ethyl 2,4,6-trimethylbenzoyl phenylphosphinate.
[0024] Optionally, the absorption wavelengths of the hydrophobic photoinitiator and the hydrophilic photoinitiator have an overlapping band. In step (4), the photocrosslinking is carried out by irradiating the hydrogel liquid film and the doped surface layer with light in the overlapping band.
[0025] Optionally, the thickness of the hydrogel liquid film is 10 μm - 1 mm, the photocrosslinking uses an ultraviolet light source with a power of 3 - 200 W, the distance between the light source and the PDMS substrate is 0.5 - 30 cm, and the crosslinking time is 10 - 200 min.
[0026] A PDMS / hydrogel composite structure, which includes a PDMS substrate and a hydrogel structure, and the hydrogel structure is formed on the PDMS substrate by the method of in-situ photocuring 3D printing of hydrogel on the PDMS surface described above.
[0027] The beneficial effects of the present invention are as follows:
[0028] A hydrophobic photoinitiator is doped into PDMS, and a firm hydrogel coating is formed on the PDMS surface by photocrosslinking, solving the problem of displacement or shedding of the photocured 3D printed hydrogel structure on the PDMS substrate, realizing in-situ photocuring printing of the hydrogel on the PDMS surface, without additional transfer and fixing steps, improving the design flexibility of the traditional process; avoiding the introduction of other adhesives and ensuring the simplicity of the product composition; in-situ printing reduces manual intervention, improves production efficiency and automation level, and opens up a new way for large-scale and high-quality customized manufacturing.
[0029] Other features and beneficial effects of the present invention will be described in the subsequent specification, and will be partially obvious from the specification or understood by implementing the present invention. Brief Description of the Drawings
[0030] Figure 1 Process flow chart of the method for in-situ photocuring 3D printing of hydrogel on the PDMS surface in the embodiment;
[0031] Figure 2 Schematic diagram of the principle of constructing a hydrogel coating during the process of the method for in-situ photocuring 3D printing of hydrogel on the PDMS surface in the embodiment;
[0032] Figure 3 Schematic diagram of photocuring 3D printing of a hydrogel structure on the surface with a hydrogel coating during the process of the method for in-situ photocuring 3D printing of hydrogel on the PDMS surface in the embodiment;
[0033] Figure 4 Physical diagram and microscopic morphology diagram of the PDMS / hydrogel composite structure prepared by the method for in-situ photocuring 3D printing of hydrogel on the PDMS surface in Example 1;
[0034] Figure 5 Schematic diagram of the interfacial toughness test of the PDMS / hydrogel composite structure prepared in Examples 1-3 and Comparative Example 1, where a is the schematic diagram of the interfacial toughness test method, b is the physical diagram of the interfacial toughness test in Example 1, c is the relationship diagram between the UV photocrosslinking time and the interfacial toughness, and d is the microscopic morphology diagram of the interface between the hydrogel coating and PDMS after peeling in Example 1;
[0035] Figure 6 Physical diagram of the PDMS / hydrogel composite structure prepared by the method for in-situ photocuring 3D printing of hydrogel on the PDMS surface in Example 4. Detailed Description of the Embodiments
[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings.
[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0038] Reference Figure 1 , a method for in-situ photocuring 3D printing of hydrogels on the surface of PDMS in an embodiment, the substrate of which is a PDMS solid polymer, specifically including:
[0039] I. Forming a PDMS substrate doped with a hydrophobic photoinitiator
[0040] Combined Figure 2 , dissolve the hydrophobic photoinitiator in an organic solvent to form an organic solution containing the hydrophobic photoinitiator, immerse the PDMS solid polymer in the organic solution containing the hydrophobic photoinitiator, wait for the organic solution containing the hydrophobic photoinitiator to swell the surface of the PDMS solid polymer to a certain depth to form a doped surface layer, take it out and wash it to obtain a PDMS substrate doped with a hydrophobic photoinitiator. The hydrophobic photoinitiator is benzophenone, trimethylbenzoyl-diphenylphosphine oxide, etc.; the organic solvent is ethanol, acetone, etc.; the mass ratio of the hydrophobic photoinitiator to the organic solvent is (0.03 - 0.2):1. The time for the PDMS solid polymer to be immersed in the organic solution containing the hydrophobic photoinitiator is 15 s - 45 min, and the thickness of the formed doped surface layer is about 5 - 300 μm. The cleaning agent used for cleaning is at least one of deionized water, ethanol, acetone, nitrogen, and argon.
[0041] II. Forming a PDMS substrate with a hydrophilic surface
[0042] Perform oxygen plasma treatment on at least part of the surface of the doped surface layer of the PDMS substrate to obtain a hydrophilic surface. The power of the oxygen plasma treatment is 60 - 400 W, the gas flow rate is 50 - 500 ml / min, and the treatment time is 10 - 600 s. Further, when a patterned hydrophilic surface needs to be constructed, form a patterned masking layer on the surface of the doped surface layer, and then perform oxygen plasma treatment to obtain a PDMS substrate with a patterned hydrophilic surface, which can realize the selective area setting of the subsequent hydrogel structure.
[0043] III. Forming a PDMS substrate with a hydrogel coating
[0044] Mix the hydrogel monomer, hydrophilic photoinitiator, light absorber, and deionized water to obtain a hydrogel prepolymer. The hydrogel monomer is acrylamide, polyethylene glycol diacrylate, methacrylated gelatin, etc., the hydrophilic photoinitiator is lithium phenyl-2,4,6-trimethylbenzoylphosphinate, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate, etc., and the light absorber is tartrazine, sunset yellow, carmine, etc.
[0045] Combine Figure 2 , and drop an appropriate amount of the hydrogel prepolymer onto the hydrophilic surface of the PDMS substrate to form a hydrogel liquid film, and the thickness of the hydrogel liquid film is 10 μm to 1 mm. Form a PDMS substrate with a hydrogel coating by simultaneously exciting the hydrophobic photoinitiator and the hydrophilic photoinitiator for photocrosslinking. Specifically, the absorption wavelengths of the hydrophobic photoinitiator and the hydrophilic photoinitiator have an overlapping band, and the photocrosslinking uses light in the overlapping band to irradiate the hydrogel liquid film and the doped surface layer. Excited by the photoinitiator, polymerization occurs simultaneously between the hydrogel monomers and between the hydrogel and the PDMS polymer network free radicals, so that chemical bond connections are formed between the hydrogel network and the PDMS network. For example, the photocrosslinking uses an ultraviolet light source with a wavelength of 285 nm to 405 nm, a power of 3 to 200 W, the distance between the light source and the PDMS substrate is 0.5 to 30 cm, and the crosslinking time is 10 to 200 min.
[0046] IV. Form a PDMS substrate with a hydrogel 3D printing structure
[0047] Combine Figure 3 , transfer the PDMS substrate with a hydrogel coating to the printing platform of a photocuring 3D printer, and perform photocuring 3D printing on the hydrogel coating using the hydrogel prepolymer, and layer-by-layer print with patterned ultraviolet light to form a preset 3D hydrogel structure.
[0048] It should be noted that for the hydrogel prepolymer used for 3D printing and the hydrogel prepolymer used to form the hydrogel coating, the specific material selection and proportion of each component can be the same or different, and there is no limitation on this. Preferably, in the hydrogel prepolymer for forming the hydrogel coating, the mass fraction of the hydrogel monomer is 10 to 80 wt%, the mass fraction of the photoinitiator is 0.1 to 5 wt%, the mass fraction of the light absorber is 0.05 to 5 wt%, and the balance is deionized water. The hydrogel prepolymer for 3D printing can be set according to actual needs.
[0049] Example 1
[0050] Prepare a hydrogel scaffold structure on a PDMS film by the method of in-situ photocuring 3D printing of hydrogel on the PDMS surface in Example 1, including the following steps:
[0051] (1) Dissolve the hydrophobic photoinitiator benzophenone in the organic solvent ethanol at a weight ratio of 0.2:1 to form an organic solution containing the hydrophobic photoinitiator.
[0052] (2) At room temperature, use a PDMS film with a size of 20 mm × 10 mm × 300 μm as the PDMS substrate, immerse it in the ethanol solution containing benzophenone, take out the PDMS film after soaking for 20 minutes, wash it successively with a small amount of ethanol and deionized water, and purge the residual deionized water with nitrogen to obtain a PDMS film doped with a hydrophobic photoinitiator.
[0053] (3) Treat the entire surface of the PDMS film doped with the hydrophobic photoinitiator under the conditions of 300 W power, 300 ml / min gas flow rate, and 60 s treatment time with oxygen plasma to obtain a PDMS film with a hydrophilic surface.
[0054] (4) Mix the hydrogel monomer, hydrophilic photoinitiator, light absorber, and deionized water to obtain a hydrogel prepolymer; the hydrogel monomer is acrylamide, the hydrophilic photoinitiator is lithium phenyl 2,4,6-trimethylbenzoylphosphinate, and the light absorber is tartrazine; the mass fraction of the hydrogel monomer is 20 wt%, the mass fraction of the photoinitiator is 0.4 wt%, the mass fraction of the light absorber is 0.16 wt%, and the rest is deionized water.
[0055] (5) Drop an appropriate amount of the hydrogel prepolymer onto the PDMS surface to form a hydrogel liquid film with a thickness of about 100 μm, and use a UV lamp with a wavelength of 365 nm and a power of 60 W to irradiate the hydrogel prepolymer and PDMS at a distance of 2 cm from the PDMS surface. Stop irradiation after 55 minutes to form a PDMS film with a hydrogel coating.
[0056] (6) Bond the PDMS film with the hydrogel coating flat to the printing platform of the stereolithography 3D printer using double-sided tape, and perform stereolithography 3D printing with the hydrogel prepolymer. The material used for stereolithography 3D printing is the same as the hydrogel prepolymer in step (4). The parameters of the stereolithography 3D printing process are: the light source wavelength is 365 - 405 nm, the single-layer exposure time is 0.1 - 10 s, where the first-layer exposure time is 10 - 45 s, the single-layer slice layer thickness is 10 - 50 μm, and the light power of the light source is 10 - 120 mW / cm 2 . Finally, obtain the structure as Figure 4 shown.
[0057] Example 2
[0058] The difference between Example 2 and Example 1 is that in step (5), the UV irradiation time is 20 minutes. The rest refers to Example 1.
[0059] Example 3
[0060] The difference between Example 3 and Example 1 is that in step (5), the ultraviolet light irradiation time is 35 min. For the rest, refer to Example 1.
[0061] Comparative Example 1
[0062] The difference between Example 3 and Example 1 is that steps (1-3) in Example 1 are not carried out. For the rest, refer to Example 1.
[0063] The interfacial toughness of the PDMS / hydrogel composite structures obtained in Examples 1-3 and Comparative Example 1 was tested. Using the 90° peel test method, the PDMS film was irreversibly bonded to a rigid quartz glass sheet through plasma treatment. Referring to Example 1, a hydrogel layer was constructed on the PDMS surface. A tough PET backing was adhered to the outer surface of the hydrogel with ethyl cyanoacrylate glue, and a tensile machine was used to measure the peeling force of the hydrogel peeling off the PDMS. From Figure 5 As can be seen from c and d, compared with the composite structure without photo-crosslinking, the stable peeling force of Examples 1-3 is significantly greater than that of Comparative Example 1, and the peeling fracture surface occurs inside the hydrogel rather than at the hydrogel / PDMS interface, indicating that a covalent connection is formed between the hydrogel polymer network and the PDMS polymer network, significantly improving the adhesion between the hydrogel and the PDMS printing substrate, and the interfacial strength between the two is increased to be higher than the tensile strength of the hydrogel network.
[0064] Example 4
[0065] A method for in-situ photocuring 3D printing of hydrogels on the surface of polydimethylsiloxane to prepare an array of inverted convex structures of hydrogels on a PDMS film, comprising the following steps:
[0066] (1) Dissolve the hydrophobic photoinitiator benzophenone in the organic solvent acetone according to a weight ratio of (0.03-0.2):1 to form an organic solution containing the hydrophobic photoinitiator.
[0067] (2) At room temperature, use a PDMS film with a size of 20 mm×10 mm×300 μm as the PDMS substrate, immerse it in the acetone solution containing benzophenone, take out the PDMS film after soaking for 10 minutes, wash it successively with a small amount of acetone and deionized water, and blow the residual deionized water with nitrogen to obtain a PDMS film doped with a hydrophobic photoinitiator.
[0068] (3) Attach a patterned and hollowed 3M tape to the surface of the PDMS film doped with a hydrophobic photoinitiator, and perform oxygen plasma treatment under the conditions of a power of 300 W, a gas flow rate of 300 ml / min, and a treatment time of 90 s to obtain a PDMS film with a patterned hydrophilic surface.
[0069] (4) Mix the hydrogel monomer, hydrophilic photoinitiator, light absorber, and deionized water to obtain a hydrogel prepolymer; the hydrogel monomer is acrylamide, the hydrophilic photoinitiator is lithium phenyl 2,4,6-trimethylbenzoylphosphinate, and the light absorber is tartrazine; the mass fraction of the hydrogel monomer is 20 wt%, the mass fraction of the photoinitiator is 0.4 wt%, the mass fraction of the light absorber is 0.16 wt%, and the rest is deionized water;
[0070] (5) Drop an appropriate amount of the hydrogel prepolymer obtained in step (4) onto the hydrophilic surface of PDMS to form a hydrogel liquid film with a thickness of about 50 - 300 μm, and horizontally place a glass slide 100 μm above the prepolymer to ensure the flatness of the upper surface of the hydrogel prepolymer. Then, irradiate the hydrogel prepolymer and PDMS with a 365 nm wavelength and 60 W power ultraviolet lamp at a distance of 2 cm from the PDMS surface. Stop irradiation after 35 minutes to form a PDMS film with a patterned hydrogel coating;
[0071] (6) Use double-sided tape to flatly bond the PDMS film with the patterned hydrogel coating to the printing platform of a stereolithography 3D printer, and perform stereolithography 3D printing using the hydrogel prepolymer; it should be ensured that the position of the patterned hydrogel coating is aligned with the first-layer pattern of the printed structure or the hydrogel coating area is larger than the first-layer pattern of the printed structure to ensure that the first-layer structure can polymerize with the hydrogel coating during the printing process; in the hydrogel prepolymer of this step, the hydrogel monomer is polyethylene glycol diacrylate, the hydrophilic photoinitiator is lithium phenyl 2,4,6-trimethylbenzoylphosphinate, and the light absorber is tartrazine; the mass fraction of the hydrogel monomer is 80 wt%, the mass fraction of the photoinitiator is 0.4 wt%, the mass fraction of the light absorber is 0.3 wt%, and the balance is deionized water; the parameters of the stereolithography 3D printing process are: the light source wavelength is 365 - 405 nm, the single-layer exposure time is 0.1 - 10 s, where the first-layer exposure time is 20 - 40 s, the single-layer slice layer thickness is 10 - 50 μm, and the light power of the light source is 10 - 120 mW / cm 2 . The finally obtained PDMS / hydrogel composite structure is as Figure 6 shown, including a PDMS substrate and an array of inverted convex hydrogel structures formed on the PDMS substrate.
[0072] The PDMS / hydrogel composite structure prepared by the present invention can be applied to, for example, flexible sensors, bioengineering cell scaffolds, microfluidic chips, etc., and has broad application prospects.
[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for in-situ photocuring 3D printing of hydrogel on PDMS surface, characterized in that: The following steps are involved: (1) doping a hydrophobic photoinitiator to a certain depth on the surface of the PDMS solid polymer to form a doped surface layer, thereby obtaining a PDMS substrate doped with the hydrophobic photoinitiator; (2) treating at least a portion of the doped surface layer of the PDMS substrate doped with a hydrophobic photoinitiator with oxygen plasma to obtain a PDMS substrate with a hydrophilic surface; (3) mixing a hydrogel monomer, a hydrophilic photoinitiator, a light absorber and water to obtain a hydrogel prepolymer; (4) adding a hydrogel prepolymer to the hydrophilic surface of the PDMS substrate to form a hydrogel liquid film, and simultaneously exciting a hydrophobic photoinitiator and a hydrophilic photoinitiator to perform photocrosslinking to form a PDMS substrate with a hydrogel coating; (5) The PDMS substrate with the hydrogel coating is transferred to the printing platform of a light-curing 3D printer, and a hydrogel prepolymer is used to perform light-curing 3D printing on the hydrogel coating.
2. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 1, characterized in that: Step (1) comprises: (1.1) dissolving a hydrophobic photoinitiator in an organic solvent to form an organic solution containing the hydrophobic photoinitiator; (1.2) Immersing the PDMS solid polymer in an organic solution containing a hydrophobic photoinitiator, and taking out and cleaning it after the organic solution containing the hydrophobic photoinitiator swells the surface of the PDMS solid polymer to a certain depth, thereby forming the doped surface layer.
3. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 2, characterized in that: The hydrophobic photoinitiator is at least one of benzophenone and trimethylbenzoyl-diphenylphosphine oxide, and the organic solvent is at least one of ethanol and acetone; the mass ratio of the hydrophobic photoinitiator to the organic solvent is (0.03-0.2):
1.
4. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 2, characterized in that: The PDMS solid polymer is immersed in the organic solution containing the hydrophobic photoinitiator for a period of 15 s to 45 min.
5. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 1, characterized in that: In step (2), a patterned shielding layer is formed on the surface of the doped surface layer, and then oxygen plasma treatment is performed to obtain a PDMS substrate with a patterned hydrophilic surface.
6. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 1, characterized in that: The power of the oxygen plasma treatment is 60-400W, the gas flow rate is 50-500ml / min, and the treatment time is 10-600s.
7. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 1, characterized in that: The hydrogel monomer is at least one of acrylamide, polyethylene glycol diacrylate, and methacrylated gelatin, and the hydrophilic photoinitiator is at least one of phenyl-2,4,6-trimethylbenzoylphosphonic acid lithium and 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester.
8. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 1, characterized in that: The absorption wavelengths of the hydrophobic photoinitiator and the hydrophilic photoinitiator have overlapping wavelength bands. In step (4), the photo-crosslinking uses light in the overlapping wavelength band to irradiate the hydrogel liquid film and the doped surface layer.
9. The method for in-situ photocuring 3D printing hydrogel on PDMS surface according to claim 1, characterized in that: The thickness of the hydrogel liquid film is 10 μm to 1 mm. The photo-crosslinking adopts an ultraviolet light source with a power of 3 to 200 W. The light source is 0.5 to 30 cm away from the PDMS substrate. The crosslinking time is 10 to 200 min.
10. A PDMS / hydrogel composite structure, characterized in that: The invention comprises a PDMS substrate and a hydrogel structure, wherein the hydrogel structure is formed on the PDMS substrate by the method for in-situ photocuring 3D printing hydrogel on the PDMS surface according to any one of claims 1 to 9.