Apparatus and method for 3D printing gradient pore macroporous gelatin with a 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] Macroporous hydrogel materials are composite porous materials formed by introducing large pores on the micron to submillimeter order into the porous structure of hydrogel polymers. Because the pore size of hydrogel materials themselves is generally on the nano to several micron order, these additional micron to submillimeter pores are generally referred to as macroporous in this field. Conventional methods for introducing macroporosity into hydrogels include foaming, pore formation, freeze-drying, and phase separation. However, these methods often result in macroporous structures with uncontrollable bubble size and location. In contrast, the combination of 3D printing technology and microflow-controlled templating allows for precise control of the size and location of macroporous structures introduced into hydrogels.

[0003] There are two main approaches to controllably 3D printing macroporous hydrogels. One is to introduce oil-phase droplets that are incompatible with the hydrogel solution prepared by microflow-controlled templating into the hydrogel solution, cure the hydrogel, and then remove the oil-phase droplets, leaving air bubbles in the hydrogel. The size and position of the oil-phase droplets can be adjusted to control the size and position of the macropores after the hydrogel is formed. The other is to directly introduce air bubbles prepared by microflow-controlled templating into the hydrogel solution, leaving air bubbles in the hydrogel after curing. Currently, the most common method is to deposit hydrogels containing oil-phase droplets or air bubbles layer by layer on a thermal bed to produce the desired final product. However, this 3D printing method often has a narrow pore size adjustment range, making it difficult to accurately control the size and position of the internal pores in the macroporous hydrogel. This can lead to problems such as misalignment and collapse of the internal pores in the macroporous hydrogel, especially when printing a large number of layers. Furthermore, 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 becomes difficult to shape during the printing process. Summary of the Invention [Problem to be solved by the invention]

[0004] To address the shortcomings of the prior art, the present invention provides an apparatus and method for 3D printing gradient pore macroporous gelatin using a multi-nozzle array, which can be applied to the 3D printing production of other types of hydrogels. By depositing bubbles created by microflow-controlled templating in the gelatin solution through the action of buoyancy, the size and generation frequency of the bubbles can be matched with the mold, significantly reducing pore misalignment and macroporous gelatin collapse, resulting in the production of macroporous gelatin with higher porosity. Furthermore, by arranging bubble nozzles in the liquid bath with slightly different bubble sizes and generation frequencies that can be fine-tuned within a certain range, the production of macroporous gelatin with significantly higher porosity can be achieved. [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 it in the Z-axis direction, and the 3D motion control module drives the mold to move it in the x-axis and y-axis directions, 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 connected in a matching manner, 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 connected to 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 is connected to the bubble nozzle in the fluoride liquid tank by a bubble introduction pipe, and the 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 to mount the buffer tank and the three-way valve.

[0009] Furthermore, since the sizes of the No. 1 coarse capillary, No. 2 fine capillary, and No. 3 fine capillary of each flow focusing device 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 bubble nozzles are attached vertically to the fluoride liquid tank at equal intervals.

[0011] Furthermore, 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 pipe of a three-way valve and a bubble outlet pipe of a three-way valve, one end of the gelatin solution inlet pipe 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 is connected to the gelatin solution transport pipe, one end of the bubble outlet pipe 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 No. 3 fine capillary is inserted into the bubble outlet pipe of the three-way valve and fixed with ultraviolet adhesive, and the other end of the bubble outlet pipe of the three-way valve is connected to the bubble introduction pipe.

[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 with a multi-nozzle array, which is realized based on an apparatus for 3D printing gradient pore macroporous gelatin with a multi-nozzle array, 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 change in bubble size and the frequency of bubble generation 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 injection pump parameters are changed to control the liquid flow rate, thereby controlling the frequency and size of bubble generation in real time. When the frequency and size of bubble generation change, the mold movement speed is changed synchronously to adjust and control the position of the target bubble group. [Effects of the Invention]

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

[0017] 1. Compared to conventional 3D printing methods in which a gelatin solution containing oil phase droplets or gas bubbles is deposited layer by layer from bottom to top on a thermal bed, the present invention deposits gas bubbles produced by a microflow-controlled template method layer by layer from top to bottom on a mold filled with a gelatin solution under the action of buoyancy. This, firstly, prevents shape deviation, collapse, and even the inability to mold when the macroporous gelatin has a high porosity, and secondly, allows for more accurate control of the size and location of the pores inside the macroporous gelatin.

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

[0019] [Figure 1] 1 is a diagram showing a three-axis measurement diagram of the overall structure of the 3D motion control module and a schematic diagram showing the positional relationship between the fluoride liquid tank 23, the three-way valve 26, the buffer tank 25, and the belt-shaped fixed groove plate 24. [Figure 2] FIG. 2 is a structural schematic diagram of a fluoride liquid tank 23 and its internal bubble nozzle and bubble introduction pipe. [Figure 3] FIG. 2 is a structural schematic diagram of a band-shaped fixed groove plate 24. [Figure 4] 2 is a structural schematic diagram of a buffer tank 25 and a three-way valve 26. FIG. [Figure 5] 1 is a schematic diagram illustrating 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] Schematic diagrams of the structure of several simple PDMS molds. [Figure 8] This is an image of bubbles continuously generated in the 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 INVENTION

[0020] The present invention will be described in detail below based on the drawings and preferred embodiments, and the objects 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 reservoir 23, a flow focusing device, and a mold 44.

[0022] Here, as shown in Figure 1, the 3D motion control module (3D printer) includes a rectangular parallelepiped overall frame made of aluminum profiles 1 and right-angle connecting members 2, with one right-angle connecting member between each pair of aluminum profiles. Two sets of four y-optical axis brackets 3 are attached to the four corners of the aluminum profiles at the top of the rectangular parallelepiped frame, with one y-optical axis 4 attached between each set of y-optical axis brackets, and two other x-optical axis brackets 5 are attached to the two y-optical axes respectively by y-axis linear bearings 6, and two x-optical axes 7 are attached between the x-optical axis brackets, with clamps 10 attached to sliders 8 and fixed to the x-optical axes by x-axis linear bearings. Two stepper motor brackets 11 are further attached to the top of the frame. The stepper motors that control the x- and y-axis movement are attached to the two brackets, respectively (not shown in the drawings). The x- and y-axis movement is controlled by connecting the synchronous wheel 17 to the idle wheel via a synchronous belt (the winding of the synchronous belt is omitted in the drawings). Two sets of four z-optical axis brackets 12 are attached to the centers of the aluminum profiles on both sides of the bottom and top of the frame, respectively. The four z-optical axes 13, two ball screws 14, and the stepper motor 15 that controls the z-axis movement are all fixed to the z-optical axis brackets. The z-axis stepper motor and ball screw are connected by a joint 16. The two movable brackets 18 are connected to the z-optical axis and ball screw nut by z-axis linear bearings 20 and ball screw nuts 21, allowing movement along the z axis. A thermal bed bracket 19 is fixed between the two movable brackets, and a thermal bed 22 is fixed on top of it. 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 buffer tank 25 are attached to a strip-shaped fixed groove plate 24 and 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 is made of transparent acrylic material, and the bubble nozzle 27 and bubble introduction tube 28 are glass capillaries with the same inner diameter but 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 ultraviolet adhesive. The bubble nozzle 27 is fixed vertically to the fluoride liquid tank 23, and the bubble nozzle 27 and bubble introduction tube 28 are connected by a first Teflon tube 45 of appropriate size.

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

[0025] 4 shows a schematic diagram of the structure of a buffer tank 25 and a three-way valve 26. The buffer tank 25 is initially filled with gelatin solution, and has a silicone oil inlet pipe 29 and a gelatin solution outlet pipe 30 above it, through which 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, which has a thin No. 2 fine capillary tube 32 inside it for introducing air. Another inlet of the three-way valve is connected to an appropriate-sized dispenser needle, to which a gelatin solution inlet pipe 33 of the three-way valve is attached. Similarly, the outlet of the three-way valve is connected to an appropriate-sized dispenser needle, to which a bubble outlet pipe 34 of the three-way valve is attached. Inside the three-way valve 26 is another No. 3 fine capillary tube 35, which is not shown here but will be described in FIG. 5.

[0026] 5 shows a schematic diagram of the structural principle of a flow focusing device. The silicone oil inlet pipe 29 of the buffer tank 25 is a short dispenser needle inserted into the buffer tank 25. The silicone oil inlet pipe is connected to a silicone oil syringe 38 via a silicone oil transport pipe 41 made of Teflon and matching the size of the silicone oil inlet pipe. The injection flow rate of the silicone oil syringe 38 is controlled by a silicone oil injection pump 37. The gelatin solution outlet pipe 30 of the buffer tank 25 is a long dispenser needle extending to the bottom near the buffer tank. The gelatin solution outlet pipe 30 is connected to a gelatin solution inlet pipe 33 of the three-way valve 26 via a gelatin solution transport pipe 42 made of Teflon and matching the size of the gelatin solution outlet. The gelatin solution inlet pipe 33 of the three-way valve is a dispenser needle attached to one of the three-way valve's holes with UV adhesive. A thick glass capillary tube, called No. 1 coarse capillary tube 31, is glued to another inlet of the three-way valve 26 with ultraviolet adhesive 36. The No. 1 coarse capillary tube 31 has a No. 2 fine capillary tube 32 glued to its interior with ultraviolet adhesive. 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 bubble outlet tube 34 of the three-way valve 26 is glued to the outlet of the three-way valve with ultraviolet adhesive. The No. 3 fine capillary tube 35, which is the same size as the No. 2 fine capillary tube 32, is connected to the interior of the bubble outlet tube 34 with 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 then 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 Figure 6, this is a schematic diagram of the connection relationship between the four flow focusing devices and the bubble nozzle 27, and 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 Figure 7, the structure of several simple PDMS molds is a schematic diagram. Each side of the PDMS mold has a square hole, and a 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 for the macroporous gelatin used for 3D printing, and also determines 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 the 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: collecting data on the range of bubble size variation and bubble generation frequency generated by each flow focusing device before printing; and (3) setting the injection flow rate changes 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 injection pump parameters to control the liquid flow rate to control the bubble generation frequency and size in real time, and when the bubble generation frequency and size change, synchronously changing the mold movement speed to adjust and control the position of the target bubble group.

[0030] Hereinafter, the 3D printing of rectangular macroporous gelatin will be 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 step S1, before printing, data on the range of change in bubble size and bubble generation frequency generated by each flow focusing device must be collected. The collection method involves connecting the flow focusing device to the bubble nozzle 27, starting the silicone oil injection pump 37 and the air injection pump 39 at a certain temperature, which is the temperature during the subsequent printing process, and using a high-speed camera to photograph the bubbles generated in the bubble nozzle at a certain sampling frequency.

[0032] In S2, we will explain how to collect data on the bubble generation status in the bubble head as an example. The manufacturing recipe is a gelatin solution of 12.5% ​​gelatin, 0.2% sodium dodecyl sulfate, and 0.04% polyethylene oxide, using silicone oil with a viscosity of 50CS. 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, and the three-way valve's gelatin solution inlet tube 33, the buffer tank's silicone oil inlet tube 29, and the gelatin solution outlet tube 30 are 20G dispenser needles. 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 varies within the range of 2 mL / h to 4 mL / h, stable bubble generation can be achieved 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, the bubbles generated in the bubble nozzle were photographed at a fixed sampling frequency using a high-speed camera. One of the sampled 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 step S4, before printing begins, the injection pump flow control software of the upper equipment sets the injection flow rate of each silicone oil injection pump 37 based on the internal macroporous distribution of the desired product. This change includes the injection flow rate magnitude and time node of the change. The movement path and movement speed of the mold 44 during the printing process are related to the internal macroporous distribution of the desired product. Furthermore, the mold movement speed must match the size and frequency of air bubbles. After setting the nozzle movement path as shown in Figure 9, the relationship between the PDMS mold movement speed and the size and frequency of air bubbles is further calculated.

[0037] The width of the hollow area inside the PDMS mold is b (mm), the diameter of the bubbles is d (mm), the generation frequency is f (ms / bubble), the time required for the bubbles to fill the rectangular parallelepiped area in the movement path is t (s), the total distance traveled by the PDMS mold within 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), which is shown in the following equation:

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 bubbles is calculated. For example, if the air flow rate and silicone oil flow rate are both 3 mL / h, the bubble size is 0.397 mm, the bubble generation frequency 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 step S5, the manufacturing formula is a gelatin solution of 12.5% ​​gelatin, 0.2% sodium dodecyl sulfate, and 0.04% polyethylene oxide. The x, y, and z axes of the 3D motion control module are set to zero. The fluoride solution tank 23 and the fixed groove strip 24 are attached to the thermal bed 22, and an appropriate amount of HFE-7500 fluoride solution is poured into the fluoride solution tank. A buffer tank 25 filled with gelatin solution and a three-way valve 26 are attached to the fixed groove strip 24, and Teflon tubing is used to connect the various passages according to the connection method shown in the drawing. The heating functions of the thermal bed and temperature control tank are turned on, gradually heating the fluoride solution and the gelatin solution in the buffer tank to the desired temperature. This step controls the temperature of the gelatin solution during the printing environment and the 3D printing process.

[0040] In step S6, the mold 44 is filled with gelatin solution and cooled in a refrigerator at 4°C until the gelatin gels. The mold is then clamped in the clamp 10, and the x-, y-, and z-axis positions of the 3D motion control module are adjusted to immerse the mold in a fluoride bath. The gelled gelatin prevents air bubbles from entering the PDMS mold during immersion. After immersion, the gelatin in the mold is allowed to gradually heat up to the same temperature as the printing environment. During this time, the silicone oil injection pump 37 and air injection pump 39 are turned on. After a while, the air bubble nozzle 27 begins to generate air bubbles, which are then continuously introduced into the fluoride bath.

[0041] In step S7, the injection pump flow control software is launched to control the flow rate of the silicone oil injection pump 37, and the G-code of the 3D motion control module is launched to perform 3D printing. Note that the mold should remain immersed in the fluoride liquid bath until and after printing is complete. During the printing process, each layer of the 3D print contains many air bubbles and has high porosity, preventing the air bubbles from moving through the gelatin solution inside 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 cool at room temperature until it gels. 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-, y-, and z-axis positions of the 3D motion control module are 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 shrinks slightly and automatically falls off the mold.

[0044] Those skilled in the art will understand that the above description is only a preferred embodiment of the invention and is not intended to limit the invention, and although the invention has been described in detail with reference to the above embodiments, 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, and any modifications, equivalent substitutions, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention. [Explanation of symbols]

[0045] In the figure, there is an aluminum profile 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 bath 23. , a strip-shaped fixed groove plate 24, a buffer tank 25, a three-way valve 26, an air bubble nozzle 27, an air bubble introduction pipe 28, a silicone oil inlet pipe 29, a gelatin solution outlet pipe 30, a No. 1 coarse capillary tube 31, a No. 2 fine capillary tube 32, a gelatin solution inlet pipe 33, an air bubble outlet pipe 34, a No. 3 fine capillary tube 35, an ultraviolet adhesive 36, a silicone oil injection pump 37, a silicone oil syringe 38, an air injection pump 39, an air syringe 40, a silicone oil transport pipe 41, a gelatin solution transport pipe 42, an air transport pipe 43, a mold 44, a first Teflon tube 45, and a 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 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 it in the Z-axis direction, and the 3D motion control module drives the mold to move it in the x-axis and y-axis directions, 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 connected in a matching manner. 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 surface 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 surface 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 connected to the outlet of the three-way valve. The second fine capillary has one end an air injection device connected to the air injection device, the gelatin solution inlet of the three-way valve connected to the outlet of the buffer tank by a gelatin solution transport pipe, the buffer tank filled with gelatin solution, the inlet of the buffer tank connected to the outlet of the silicone oil injection device by a silicone oil transport pipe, the outlet of the three-way valve connected to the bubble nozzle in the fluoride liquid tank by a bubble introduction pipe, and bubbles generated by the flow focusing device enter the mold through the 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, buffer tank, and three-way valve are all fixed to the thermal bed, and the thermal bed synchronously heats the liquid in the fluoride liquid tank and buffer tank.

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

4. 2. The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array according to claim 1, wherein 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 onto the mold by the bubble nozzle.

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

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

7. 2. The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array according to claim 1, wherein the buffer tank further includes a silicone oil inlet pipe fixed to the top thereof and a gelatin solution outlet pipe, the silicone oil inlet pipe being shorter than the gelatin solution outlet pipe, the silicone oil inlet pipe communicating with the silicone oil transport pipe, and the gelatin solution outlet pipe communicating with the gelatin solution transport pipe.

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 pipe of a three-way valve and a bubble outlet pipe of a three-way valve, one end of the gelatin solution inlet pipe of the three-way valve being inserted into the gelatin solution inlet of the three-way valve and externally bonded with ultraviolet adhesive, and the other end being connected to the gelatin solution transport pipe, one end of the bubble outlet pipe of the three-way valve being inserted into the outlet of the three-way valve and externally bonded with ultraviolet adhesive, the other end of the third fine capillary being inserted into the bubble outlet pipe of the three-way valve and fixed with ultraviolet adhesive, and the other end of the bubble outlet pipe of the three-way valve being connected to the bubble introduction pipe.

9. the mold is a PDMS mold; 2. The apparatus for 3D printing gradient pore macroporous gelatin using a multi-nozzle array according to 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 change in bubble size and the frequency of bubble generation 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 according to the distribution of the internal macroporosity of the desired product, so that the movement speed of the mold matches the size and generation frequency of the bubbles. During the printing process, the injection pump parameters are changed to control the liquid flow rate, thereby controlling the frequency and size of the bubbles in real time. When the 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.

Images