Device and method for three-dimensional printing of gradient-pore macro-porous gelatin through multi-nozzle array

Abstract

To provide a device and a method for three-dimensional printing of gradient-pore macro-porous gelatin through a multi-nozzle array.SOLUTION: There is provided a device, comprising: a three-dimensional motion control module; a fluorination liquid tank; a flow focusing device; and a mold. In a printing process, the mold is clamped on a sliding block of the three-dimensional motion control module and wholly immersed in the fluorination liquid tank, the fluorination liquid tank has a number of independent bubble nozzles, and the bubble nozzles are connected with flow focusing devices having different sizes so as to generate bubbles with different sizes. According to the device and method for three-dimensional printing of the macro-porous gelatin, printing of the macro-porous gelatin with high internal phase and cross-order-of-magnitude gradient pores can be achieved, and a mold moving speed and a bubble generation frequency and size are coordinated in real time, so that accurate adjustment and control of the internal pores in macro-porous gelatin are executed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of 3D printing of macroporous hydrogels, and more particularly to an apparatus and method for 3D printing gradient pore macroporous gelatin by a multi-nozzle array. [Background technology]

[0002] A macroporous hydrogel material is a composite porous material formed by introducing large pores of the order of microns to submillimeters in addition to the hydrogel polymer porous structure. The pore size of the hydrogel material itself is generally on the order of nanometers to several microns, so these extra pores of the order of microns to submillimeters are generally called macroporous in this field. Conventionally, macroporosity is generally introduced into hydrogels by foaming, pore-forming, freeze-drying, phase separation, and other methods, but these methods often introduce macroporosity whose size and position of bubbles cannot be controlled. In contrast, by combining 3D printing technology with a microflow control template method, the size and position of the macroporosity introduced into the hydrogel can be well controlled.

[0003] There are mainly two methods for controllably 3D printing macroporous hydrogels. One is to introduce oil phase droplets that are incompatible with the hydrogel solution produced by the microflow-controlled template method into the hydrogel solution, harden the hydrogel after the oil phase droplets are introduced, and then remove the oil phase droplets to leave air bubbles in the hydrogel, and adjust and control the size and position of the oil phase droplets to control the size and position of the macropores after the hydrogel is formed. The other is to directly introduce air bubbles produced by the microflow-controlled template method into the hydrogel solution, and leave air bubble holes in the hydrogel after the hydrogel is hardened. Currently, the general method is to deposit and stack hydrogels containing oil phase droplets or air bubbles one layer at a time on a thermal bed to finally produce the desired product, but the pore size adjustment range of such 3D printing methods is often small, and it is difficult to accurately control the size and position of the internal pores of the macroporous hydrogel. Especially when the number of printing layers is large, the size and position of the internal pores of the macroporous hydrogel are likely to be misaligned and collapsed. In addition, such 3D printing methods can only produce macroporous hydrogels with a maximum porosity of about 65%, and as the porosity continues to increase, the hydrogel is difficult to shape during the printing process. Summary of the Invention [Problem to be solved by the invention]

[0004] In response to the shortcomings of the prior art, the present invention provides an apparatus and method for 3D printing gradient pore macroporous gelatin by multi-nozzle array, which can be extended to 3D printing production of other kinds of hydrogels. By depositing the bubbles produced by micro-flow control template method in gelatin solution by the action of buoyancy, matching the size and generation frequency of the bubbles with the mold, the misalignment of the pore position and the collapse of the macroporous gelatin can be largely avoided, and the production of macroporous gelatin with higher porosity can be realized. In addition, the size and generation frequency of some bubbles can be fine-tuned within a certain range in the liquid tank, but the production of macroporous gelatin with a large difference can be realized. [Means for solving the problem]

[0005] The object of the present invention is achieved by the following technical solutions.

[0006] An apparatus for 3D printing gradient pore macroporous gelatin by a multi-nozzle array, comprising a 3D motion control module, a fluoride liquid bath, a flow focusing device and a mold; The fluoride liquid bath and the mold are both fixed to a rectangular frame of the 3D motion control module, the fluoride liquid bath includes a hollow tank with an open top and at least one bubble nozzle fixed in the hollow tank, fluoride liquid is contained in the hollow tank, the 3D motion control module drives the fluoride liquid bath to move in the Z-axis direction, and the 3D motion control module drives the mold to move in the x-axis direction and the y-axis direction, thereby immersing the mold in the fluoride liquid bath during the 3D printing process, and bubbles ejected from the bubble nozzle enter the mold, The flow focusing device and the bubble nozzle are matched and connected one by one, and include a silicone oil injection device, an air injection device, a buffer tank, a three-way valve, a first coarse capillary, a second fine capillary and a third fine capillary. The exterior of the first coarse capillary is sealed and fixedly connected to the air inlet of the three-way valve. The second fine capillary is inserted into the first coarse capillary and its exterior is sealed and fixedly connected to the first coarse capillary. The third fine capillary also has one end inserted into the first coarse capillary and arranged coaxially with the second fine capillary, and the other end communicates with the outlet of the three-way valve. One end of the second fine capillary tube is connected to the air injection device, the gelatin solution inlet of the three-way valve and the outlet of the buffer tank are connected by a gelatin solution transport pipe, the buffer tank is filled with gelatin solution, the inlet of the buffer tank is connected to the outlet of the silicone oil injection device by a silicone oil transport pipe, the outlet of the three-way valve and the bubble nozzle in the fluoride liquid tank are connected by a bubble introduction pipe, and bubbles generated by the flow focusing device enter the mold via the bubble introduction pipe and the bubble nozzle.

[0007] The system further includes a thermal bed, a thermal bed bracket, and a Z-axis ball screw nut device, wherein the thermal bed is fixed to the 3D motion control module by the thermal bed bracket, and the Z-axis ball screw nut device drives the thermal bed bracket to move along the Z-axis direction, and the fluoride liquid tank, buffer tank, and three-way valve are all fixed to the thermal bed, and the thermal bed synchronously heats the liquids in the fluoride liquid tank and buffer tank.

[0008] The belt-shaped groove plate further includes a circular groove and a long belt-shaped groove, which are respectively used for mounting the buffer tank and the three-way valve.

[0009] Furthermore, since the sizes of the No. 1 coarse capillary, the No. 2 fine capillary and the No. 3 fine capillary of each of the flow focusing devices are different, the bubbles generated by each flow focusing device have different sizes and generation frequencies, and are ejected into the mold by the bubble nozzle.

[0010] Furthermore, the fluoride liquid tank is made of a transparent acrylic plate, and the air bubble nozzles are attached vertically to the fluoride liquid tank at equal intervals.

[0011] Additionally, all pipe connections are secured with UV adhesive.

[0012] Furthermore, the buffer tank further includes a silicone oil inlet pipe fixed to its top and a gelatin solution outlet pipe, the silicone oil inlet pipe is shorter than the gelatin solution outlet pipe, the silicone oil inlet pipe communicates with the silicone oil transport pipe, and the gelatin solution outlet pipe communicates with the gelatin solution transport pipe.

[0013] Furthermore, the flow focusing device further includes a gelatin solution inlet tube of a three-way valve and a bubble outlet tube of a three-way valve, one end of the gelatin solution inlet tube of the three-way valve is inserted into the gelatin solution inlet of the three-way valve and the outside is bonded with ultraviolet adhesive, and the other end is connected to the gelatin solution transport tube, one end of the bubble outlet tube of the three-way valve is inserted into the outlet of the three-way valve and the outside is bonded with ultraviolet adhesive, the other end of the No. 3 fine capillary is inserted into the bubble outlet tube of the three-way valve and fixed with ultraviolet adhesive, and the other end of the bubble outlet tube of the three-way valve is connected to the bubble introduction tube.

[0014] Furthermore, the mold is a PDMS mold, the silicone oil injection device includes a silicone oil injection pump and a silicone oil syringe, and the air injection device includes an air injection pump and an air syringe.

[0015] A method for 3D printing gradient pore macroporous gelatin by a multi-nozzle array, which is realized based on an apparatus for 3D printing gradient pore macroporous gelatin by a multi-nozzle array, The method includes steps 1 to 3, In the step 1, before printing, the ranges of gas flow rate and liquid flow rate at which each flow focusing device can stably generate bubbles are debugged and measured, respectively; In step 2, before printing, data on the range of bubble size variation and bubble generation frequency generated by each flow focusing device is collected; In step 3, the change in the injection flow rate of each silicone oil injection pump and the movement path and movement speed of the mold during the printing process are set so that the movement speed of the mold matches the size and generation frequency of the bubbles according to the distribution of the internal macroporosity of the desired product. During the printing process, the parameters of the injection pump are changed to control the liquid flow rate, thereby controlling the generation frequency and size of the bubbles in real time. When the generation frequency and size of the bubbles change, the movement speed of the mold is changed synchronously to adjust and control the position of the target bubble group. Effect of the Invention

[0016] The beneficial effects of the present invention are as follows:

[0017] 1. Compared with the conventional 3D printing method in which a gelatin solution containing oil phase droplets or air bubbles is deposited layer by layer from the bottom up in a thermal bed, the present invention deposits air bubbles produced by a micro-flow controlled template method layer by layer from the top down in a mold filled with gelatin solution under the action of buoyancy, which firstly prevents shape deviation, collapse, and even the inability to mold when the macroporous gelatin has high porosity, and secondly, allows the size and position of the pores inside the macroporous gelatin to be more accurately controlled.

[0018] 2. Compared with conventional single-nozzle 3D printing devices for macroporous gelatin, the present invention not only has the advantage that the pore size of macroporous gelatin can be controlled within a small range by installing a flow focusing device of a slightly different size and connecting it to a bubble nozzle in a fluoride liquid tank, but also that the pore size of macroporous gelatin can be controlled within a larger range, thereby achieving an order of magnitude change. [Brief description of the drawings]

[0019] [Figure 1] 1 is a positive three-axis measurement diagram of the overall structure of a 3D motion control module and a schematic diagram of the positional relationship between the fluoride liquid tank 23, the three-way valve 26, the buffer tank 25, and the band-shaped fixed groove plate 24. FIG. [Diagram 2] FIG. 2 is a schematic diagram showing the structure of a fluoride liquid tank 23 and its internal air bubble nozzle and air bubble introduction tube. [Diagram 3] 1 is a schematic diagram of the structure of a band-shaped fixed groove plate 24. FIG. [Figure 4] 2 is a schematic diagram of the structures of a buffer tank 25 and a three-way valve 26. FIG. [Diagram 5] FIG. 2 is a schematic diagram showing the structural principle of a reverse flow focusing device. [Figure 6] FIG. 1 is a schematic diagram of the connection relationship between four reverse flow focusing devices and a bubble nozzle. [Figure 7] FIG. 1 shows schematic diagrams of the structures of several simple PDMS molds. [Figure 8] 1 is an image of bubbles continuously generated in a bubble nozzle taken by a high-speed camera. [Figure 9] This is a schematic diagram of one of the movement paths of the bubble nozzle relative to the mold when 3D printing a rectangular macroporous glue. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in detail below based on the drawings and preferred embodiments, so that the object and effects of the present invention will become more apparent. It should be understood that the specific embodiments described herein are used only to explain the present invention and are not used to limit the present invention.

[0021] The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array in this embodiment includes a 3D motion control module, a fluoride liquid bath 23, a flow focusing device and a mold 44.

[0022] Here, as shown in FIG. 1, the 3D motion control module (3D printer) includes a rectangular overall frame consisting of an aluminum profile 1 and a right-angle connecting member 2, with one right-angle connecting member between every two aluminum profiles, and two sets of four y-optical axis brackets 3 are attached to the four corners of the aluminum profile at the top of the rectangular frame, one y-optical axis 4 is attached between each set of y-optical axis brackets, the other two x-optical axis brackets 5 are respectively attached to the two y-optical axes by y-axis linear bearings 6, two x-optical axes 7 are attached between the x-optical axis brackets, and a clamp 10 is attached to the slider 8 and fixed to the x-optical axis by the x-axis linear bearing. Two stepping motor brackets 11 are further mounted on the top of the frame, and the stepping motors that control the x-axis and y-axis movements are mounted on the two brackets, respectively, and are not shown in the drawings. The x-axis and y-axis movements are controlled by connecting the synchronous wheel 17 and the idle wheel with a synchronous belt, and the winding of the synchronous belt is omitted in the drawings. Two sets of four z optical axis brackets 12 are respectively mounted on the center of the aluminum profiles on both sides of the bottom and top of the frame, and the four z optical axes 13, the two ball screws 14, and the stepping motor 15 that controls the z-axis movement are all fixed to the z optical axis brackets, and the z-axis stepping motor and the ball screws are connected by joints 16. The two movable brackets 18 are connected to the z optical axis and the ball screw nut by the z-axis linear bearing 20 and the ball screw nut 21, so that they can move on the z axis. The thermal bed bracket 19 is fixed between the two movable brackets, and the thermal bed 22 is fixed thereon. The fluoride liquid tank 23 is filled with an appropriate amount of fluoride liquid with model number hfe-7500 and placed on the thermal bed, and a removable three-way valve 26 and a buffer tank 25 are attached to a strip-shaped fixed groove plate 24, which is then placed on the thermal bed.

[0023] 2 is a structural schematic diagram of the fluoride liquid tank 23 and the bubble nozzle 27 and bubble introduction tube 28 therein, the fluoride liquid tank being made of a transparent acrylic material, and the bubble nozzle 27 and the bubble introduction tube 28 being glass capillaries having the same inner diameter and appropriately larger than the maximum size of the bubbles to be transported. The bubble introduction tube 28 penetrates the wall of the fluoride liquid tank 23 and is fixed to the wall with an ultraviolet adhesive. The bubble nozzle 27 is fixed vertically to the fluoride liquid tank 23, and the bubble nozzle 27 and the bubble introduction tube 28 are connected by a first Teflon tube 45 of an appropriate size.

[0024] As shown in FIG. 3, which is a structural schematic diagram of a band-shaped fixed groove 24, there is a circular groove and a long groove on which a buffer tank 25 and a three-way valve 26 are mounted.

[0025] As shown in Figure 4, the buffer tank 25 and the three-way valve 26 are structural schematic diagrams, the buffer tank 25 is first filled with gelatin solution, and there is one silicone oil inlet tube 29 and one gelatin solution outlet tube 30 on it, and silicone oil is introduced and gelatin solution is discharged during operation. One inlet of the three-way valve 26 is connected to a thick No. 1 coarse capillary tube 31, and inside the No. 1 coarse capillary tube is a thin No. 2 fine capillary tube 32 for introducing air, another inlet of the three-way valve is connected to a dispenser needle of an appropriate size, and the inlet is attached to the gelatin solution inlet tube 33 of the three-way valve, and similarly, the outlet of the three-way valve is connected to a dispenser needle of an appropriate size, and the outlet is attached to the air bubble outlet tube 34 of the three-way valve, and inside the three-way valve 26 is another No. 3 fine capillary tube 35, which is not shown here but will be described in Figure 5.

[0026] As shown in Figure 5, the structural principle of the flow focusing device is a schematic diagram, in which the silicone oil inlet pipe 29 of the buffer tank 25 is a short dispenser needle, which can be inserted into the buffer tank 25, and the silicone oil inlet pipe is connected to the silicone oil syringe 38 through the silicone oil transport pipe 41, whose material is Teflon and whose size matches the silicone oil inlet pipe, and the injection flow rate of the silicone oil syringe 38 is controlled by the silicone oil injection pump 37. The gelatin solution outlet pipe 30 of the buffer tank 25 is a long dispenser needle that extends to the bottom near the buffer tank, and the gelatin solution outlet pipe 30 is connected to the gelatin solution inlet pipe 33 of the three-way valve 26 through the gelatin solution transport pipe 42, whose material is Teflon and whose size matches the gelatin solution outlet, and the gelatin solution inlet pipe 33 of the three-way valve is a dispenser needle that is glued to one hole of the three-way valve by ultraviolet adhesive. A thick glass capillary tube, called the No. 1 coarse capillary tube 31, is attached to another inlet of the three-way valve 26 by ultraviolet adhesive 36, and is called the No. 1 coarse capillary tube 31. The No. 2 fine capillary tube 32 is attached to the inside of the No. 1 coarse capillary tube 31 by ultraviolet adhesive, and the No. 1 coarse capillary tube 31 is connected to an air syringe 40 by an air transport tube 43 made of Teflon, and the injection flow rate of the air syringe 40 is controlled by an air injection pump 39. The air bubble outlet tube 34 of the three-way valve 26 is attached to the outlet of the three-way valve by ultraviolet adhesive, and the No. 3 fine capillary tube 35, which has the same size as the No. 2 fine capillary tube 32, is connected to the inside of the air bubble outlet tube 34 by ultraviolet adhesive. The gelatin solution transported from the gelatin solution inlet flows into the No. 1 coarse capillary 31, and at the opening of the No. 3 fine capillary 35, shears the air transported from the No. 2 fine capillary 32 to generate bubbles. The bubbles are transported together with the gelatin solution through the No. 3 fine capillary 35 into the bubble outlet of the three-way valve.

[0027] As shown in FIG. 6, this is a schematic diagram of the connection relationship between the four flow focusing devices and the bubble nozzle 27, in which the bubble outlet pipe 34 of the flow focusing device is connected to the bubble introduction pipe 28 via a second Teflon tube 46.

[0028] For ease of observation, the mold 44 in this embodiment is a PDMS mold. As shown in FIG. 7, the structure schematic diagram of several simple PDMS molds, each side of the PDMS mold has a square hole, and the clamp 10 can be inserted into the square hole to fix the PDMS mold. The hollow part in the center of the PDMS mold is the area of ​​macroporous gelatin for 3D printing, and is also the overall shape of the final product, that is, the shape of the hollow part of the PDMS mold is determined by the required shape of macroporous gelatin.

[0029] In another aspect, the present embodiment provides a method for 3D printing gradient pore macroporous gelatin by a multi-nozzle array based on the above device, Step 1: before printing, debug and measure the range of gas flow rate and liquid flow rate that each flow focusing device can stably generate bubbles; Step 2, prior to printing, collecting data on the range of bubble size variation and bubble generation frequency generated by each flow focusing device; and setting the change in the injection flow rate of each silicone oil injection pump and the movement path and movement speed of the mold during the printing process so that the movement speed of the mold matches the size and generation frequency of the bubbles according to the distribution of the internal macroporosity of the desired product, and during the printing process, changing the parameters of the injection pump to control the liquid flow rate to control the frequency and size of the bubbles in real time, and when the frequency and size of the bubbles change, synchronously changing the movement speed of the mold to adjust and control the position of the target bubble group.

[0030] Hereinafter, the 3D printing of a rectangular macroporous gelatin is taken as an example to describe the method of using the device for 3D printing gradient pore macroporous gelatin by the multi-nozzle array described in the present invention.

[0031] In S1, before printing, data on the bubble size change range and bubble generation frequency generated by each flow focusing device must be collected. The collection method is to connect the flow focusing device to the bubble nozzle 27, start the silicone oil injection pump 37 and the air injection pump 39 at a certain temperature, that is, the temperature during the subsequent printing process, and use a high-speed camera to photograph the bubbles generated in the bubble nozzle at a certain sampling frequency.

[0032] In S2, the following will be described as an example of how to collect data on the bubble generation status in the bubble head. The manufacturing recipe is a gelatin solution of 12.5% ​​gelatin + 0.2% sodium dodecyl sulfate + 0.04% polyethylene oxide, and silicone oil with a viscosity of 50CS is used. The first coarse capillary 31 is a glass capillary with an inner diameter of 0.5 mm, the second fine capillary 32 and the third fine capillary 35 are glass capillaries with an inner diameter of 0.1 mm, the gelatin solution inlet tube 33 of the three-way valve, the silicone oil inlet tube 29 of the buffer tank, and the gelatin solution outlet tube 30 are 20G dispenser needles, and when the injection flow rate of the air injection pump 39 is 3 mL / h, if the injection flow rate of the silicone oil injection pump 37 changes within the range of 2 mL / h to 4 mL / h, the air bubbles can be stably generated in the flow focusing device. Then, when the air flow rate was 3 mL / h, and the silicone oil flow rate was 2 mL / h, 3 mL / h, and 4 mL / h, respectively, the bubbles generated in the bubble nozzle were photographed at a certain sampling frequency using a high-speed camera, and one of the sampling images is shown in Figure 8. The bubble size data obtained by analysis is shown in Table 1, and the bubble generation frequency data is shown in Table 2.

[0033] Table 1. Bubble size data [Table 1]

[0034] Table 2. Bubble generation frequency data [Table 2]

[0035] In S3, following step S2, each reverse-flow focusing device collects size data and generation frequency data of the bubbles generated.

[0036] In S4, before printing starts, the injection flow rate change status of each silicone oil injection pump 37 is set in the injection pump flow rate control software of the upper equipment based on the internal macroporous distribution status of the desired product, and the change status includes the magnitude of the injection flow rate and the time node of the change. The moving path and moving speed of the mold 44 during the printing process are related to the internal macroporous distribution status of the desired product, and further, the moving speed of the mold needs to match the size and generation frequency of the air bubbles. When the nozzle moving path is set as shown in Figure 9, the relationship between the moving speed of the PDMS mold and the size and generation frequency of the air bubbles is further calculated.

[0037] The width of the hollow area inside the PDMS mold is b (mm), the diameter of the air bubble is d (mm), the generation frequency is f (ms / bubble), the time required for the air bubbles to fill the rectangular parallelepiped area in the movement path is t (s), the total path traveled by the PDMS mold in time t is s (mm), the movement distance of the PDMS mold on the long side is x (mm), and the movement speed of the nozzle is F (mm / min), as shown in the following formula:

number

[0038] That is, in the Gcode of the 3D motion control module, the relationship between the moving speed of the PDMS mold and the size and generation frequency of the bubbles is calculated. For example, when the air flow rate and the silicone oil flow rate are both 3 mL / h, the size of the bubbles is 0.397 mm, the generation frequency of the bubbles is 81 ms / piece, and if the width b is 20 mm, the corresponding nozzle moving speed should be calculated to be 302 mm / min.

[0039] In S5, the manufacturing formula is 12.5% ​​gelatin + 0.2% sodium dodecyl sulfate + 0.04% polyethylene oxide gelatin solution, and the x-axis, y-axis, and z-axis of the 3D motion control module are set to zero. The fluoride liquid tank 23 and the strip-shaped fixed groove plate 24 are attached to the thermal bed 22, and an appropriate amount of hfe-7500 fluoride liquid is poured into the fluoride liquid tank. The buffer tank 25, which is filled with gelatin solution in advance, and the three-way valve 26 are attached to the strip-shaped fixed groove plate 24, and each passage is connected with a Teflon tube according to the connection method in the drawing. The heating function of the thermal bed and the temperature control tank is turned on to gradually heat the fluoride liquid and the gelatin solution in the buffer tank to a predetermined temperature, and this step is to control the printing environment and the temperature of the gelatin solution during the 3D printing process.

[0040] In S6, after filling the mold 44 with gelatin solution, the temperature is lowered in a refrigerator at 4°C until the gelatin gels, and then the mold is clamped by the clamp 10, and the x-axis, y-axis, and z-axis positions of the 3D motion control module are adjusted to immerse the mold in the fluoride liquid bath, and the gelled gelatin in the mold prevents the PDMS mold from entering air bubbles during the immersion process. After the mold is immersed in the liquid bath, the gelatin in the mold is gradually heated to the same temperature as the printing environment, and during the waiting process, the silicone oil injection pump 37 and the air injection pump 39 are turned on, and after a while, the air bubble nozzle 27 begins to generate air bubbles and continues to be introduced into the fluoride liquid.

[0041] In S7, the injection pump flow control software is started to control the flow rate change of the silicone oil injection pump 37, and the G code of the 3D motion control module is started to perform 3D printing, and it is noted that the mold should still be immersed in the fluoride liquid bath until and when printing is completed. During the printing process, each layer of the 3D printing has many air bubbles and high porosity, so the air bubbles cannot move in the gelatin solution in the mold.

[0042] In S8, the temperature control tank and the thermal bed heating device of the 3D motion control module are stopped, and the gelatin in the PDMS mold is allowed to gel by cooling at room temperature; the cooling process of the gelatin can also be accelerated by replacing the overheated hfe-7500 in the fluoride liquid bath with pre-frozen hfe-7500.

[0043] In S9, the x-axis, y-axis, and z-axis position of the 3D motion control module is adjusted, the mold is removed, and the mold and the gelled gelatin inside it are placed in a freeze dryer for freeze-drying. After freeze-drying, the gelatin will shrink slightly and automatically fall out of the mold.

[0044] It is understood by those skilled in the art that the above description is only a preferred embodiment of the invention, and is not intended to limit the invention, and the invention has been described in detail with reference to the above embodiments, but those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features thereof. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the invention should be included in the protection scope of the invention. [Explanation of symbols]

[0045] In the figure, there are an aluminum molded material 1, a right-angle connecting member 2, a y-axis bracket 3, a y-axis 4, an x-axis bracket 5, a y-axis linear bearing 6, an x-axis 7, a slider 8, an x-axis linear bearing 9, a clamp 10, an x-axis and y-axis stepping motor bracket 11, a z-axis and stepping motor bracket 12, a z-axis 13, a ball screw 14, a stepping motor 15, a joint 16, a synchronous wheel 17, a movable bracket 18, a thermal bed bracket 19, a z-axis linear bearing 20, a ball screw nut 21, a thermal bed 22, and a fluoride liquid tank 23. , strip-shaped fixed groove plate 24, buffer tank 25, three-way valve 26, air bubble nozzle 27, air bubble introduction tube 28, silicone oil inlet tube 29, gelatin solution outlet tube 30, No. 1 coarse capillary tube 31, No. 2 fine capillary tube 32, gelatin solution inlet tube 33, air bubble outlet tube 34, No. 3 fine capillary tube 35, UV adhesive 36, silicone oil injection pump 37, silicone oil syringe 38, air injection pump 39, air syringe 40, silicone oil transport tube 41, gelatin solution transport tube 42, air transport tube 43, mold 44, first Teflon tube 45, second Teflon tube 46.

Claims

1. An apparatus for 3D printing gradient pore macroporous gelatin with a multi-nozzle array, the apparatus including a 3D motion control module, a fluoride liquid bath, a flow focusing device, and a mold; The fluoride liquid tank and the mold are both fixed to a rectangular frame of the 3D motion control module, the fluoride liquid tank includes a hollow tank with an open top and at least one bubble nozzle fixed in the hollow tank, fluoride liquid is contained in the hollow tank, the 3D motion control module drives the fluoride liquid tank to move in the Z-axis direction, and the 3D motion control module drives the mold to move in the x-axis direction and the y-axis direction, thereby immersing the mold in the fluoride liquid tank during the 3D printing process, and bubbles ejected from the bubble nozzle enter the mold, The flow focusing device and the bubble nozzle are matched and connected one by one. The flow focusing device includes a silicone oil injection device, an air injection device, a buffer tank, a three-way valve, a first coarse capillary, a second fine capillary and a third fine capillary. The outer side of the first coarse capillary is sealed and fixedly connected to the air inlet of the three-way valve. The second fine capillary is inserted into the first coarse capillary and its outer side is sealed and fixedly connected to the first coarse capillary. The third fine capillary also has one end inserted into the first coarse capillary and arranged coaxially with the second fine capillary, and the other end communicates with the outlet of the three-way valve. The second fine capillary has one end An apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array, characterized in that the apparatus is connected to the air injection device, the gelatin solution inlet of the three-way valve and the outlet of the buffer tank are connected by a gelatin solution transport pipe, the buffer tank is filled with gelatin solution, the inlet of the buffer tank is connected to the outlet of the silicone oil injection device by a silicone oil transport pipe, the outlet of the three-way valve and the bubble nozzle in the fluoride liquid tank are connected by an air bubble introduction pipe, and bubbles generated by the flow focusing device enter the mold through the air bubble introduction pipe and the bubble nozzle.

2. The apparatus further includes a thermal bed, a thermal bed bracket, and a Z-axis ball screw nut apparatus; The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array as described in claim 1, characterized in that the thermal bed is fixed to the 3D motion control module by the thermal bed bracket, the Z-axis ball screw nut device drives the thermal bed bracket to move along the Z-axis direction, the fluoride liquid tank, the buffer tank and the three-way valve are all fixed to the thermal bed, and the thermal bed synchronously heats the liquid in the fluoride liquid tank and the buffer tank.

3. The apparatus further includes a grooved strip; The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array as described in claim 2, characterized in that the groove plate has a circular groove and a long groove, which are respectively used to mount the buffer tank and the three-way valve.

4. The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array as described in claim 1, characterized in that the sizes of the first coarse capillary, the second fine capillary and the third fine capillary of each of the flow focusing devices are different, so that the bubbles generated by each flow focusing device have different sizes and generation frequencies, and are ejected into the mold by the bubble nozzle.

5. The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array as described in claim 1, characterized in that the fluoride liquid tank is made of a transparent acrylic plate, and the bubble nozzles are vertically attached to the fluoride liquid tank at equal intervals.

6. The apparatus for 3D printing gradient pore macroporous gelatin with multi-nozzle array as claimed in claim 1, characterized in that all pipe connection points are fixed by ultraviolet adhesive.

7. The apparatus for 3D printing gradient pore macroporous gelatin by multi-nozzle array according to claim 1, characterized in that the buffer tank further includes a silicone oil inlet tube fixed to its top and a gelatin solution outlet tube, the silicone oil inlet tube being shorter than the gelatin solution outlet tube, the silicone oil inlet tube communicating with the silicone oil transport tube, and the gelatin solution outlet tube communicating with the gelatin solution transport tube.

8. 2. The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array according to claim 1, wherein the flow focusing device further comprises a gelatin solution inlet tube of a three-way valve and a bubble outlet tube of a three-way valve, one end of the gelatin solution inlet tube of the three-way valve is inserted into the gelatin solution inlet of the three-way valve and is externally bonded with ultraviolet adhesive, and the other end of the gelatin solution inlet tube is connected to the gelatin solution transport tube, one end of the bubble outlet tube of the three-way valve is inserted into the outlet of the three-way valve and is externally bonded with ultraviolet adhesive, the other end of the third fine capillary tube is inserted into the bubble outlet tube of the three-way valve and fixed with ultraviolet adhesive, and the other end of the bubble outlet tube of the three-way valve is connected to the bubble introduction tube.

9. the mold is a PDMS mold, 2. The apparatus for 3D printing gradient pore macroporous gelatin with a multi-nozzle array as claimed in claim 1 , wherein the silicone oil injection device includes a silicone oil injection pump and a silicone oil syringe, and the air injection device includes an air injection pump and an air syringe.

10. A method for 3D printing gradient pore macroporous gelatin by a multi-nozzle array, said method being carried out on an apparatus for 3D printing gradient pore macroporous gelatin by a multi-nozzle array according to any one of claims 1 to 9, The method includes steps 1 to 3, In step 1, before printing, the ranges of gas flow rate and liquid flow rate at which each flow focusing device can stably generate bubbles are debugged and measured, In step 2, before printing, data on the range of bubble size variation and bubble generation frequency generated by each flow focusing device is collected; In step 3, the change in the injection flow rate of each silicone oil injection pump and the movement path and movement speed of the mold during the printing process are set so that the movement speed of the mold matches the size and generation frequency of the bubbles according to the distribution of the internal macroporosity of the desired product. During the printing process, the parameters of the injection pump are changed to control the liquid flow rate, thereby controlling the generation frequency and size of the bubbles in real time. When the generation frequency and size of the bubbles change, the movement speed of the mold is synchronously changed to adjust and control the position of the target bubble group.

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