A microbubble-assisted projection-style photocuring 3D printing system and method

Abstract

This invention provides a microbubble-assisted projection-based photopolymerization 3D printing system and method. By incorporating a microbubble generation unit (including coated glass, a laser, a focusing module, and a laser control mechanism) into a traditional projection-based tube-curing 3D printer, the system utilizes the photothermal effect to generate microbubbles and uses these microbubbles for positioning, thus enabling the construction of micro-channel structures in a projection-based photopolymerization 3D printing system. Furthermore, the system leverages microbubble positioning to generate microchannels, and precisely controls the size of the microbubbles by controlling laser power and pulse length, as well as the position of the generated microbubbles by the laser control mechanism. This overcomes the difficulty of printing micro-channel structures and similar micro-structures in existing projection-based photopolymerization 3D printing systems, effectively improving the printing capabilities of projection-based photopolymerization 3D printing technology and expanding its application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a microbubble-assisted projection-type photopolymerization 3D printing system and method. Background Technology

[0002] 3D printing, also known as additive manufacturing, constructs three-dimensional objects by stacking layers. Common 3D printing processes include: fused deposition modeling (FDM), selective laser sintering (SLS), stereolithography, projection photopolymerization, direct metal laser sintering (DLS), layered solid fabrication, polymer jetting, binder jetting, and electron beam fusion.

[0003] Among them, projection-based photopolymer 3D printing technology has been widely used in recent years due to its good precision and high forming efficiency. Like common 3D printing technologies, it also achieves the manufacturing of three-dimensional entities through layer-by-layer stacking. The layer construction is completed using a projection optical engine. During each layer printing, the projection optical engine projects the current printing section of the 3D model onto the photosensitive material at one time. Since the light emitted by the projection optical engine can excite the photosensitive material to solidify, the area of ​​the photosensitive material projected will solidify to a certain depth, thus completing the construction of a single layer. After the construction of a single layer is completed, the deposition platform and the solidified structure are separated by a distance of one layer from the solidified area through related mechanical structure drive, leaving space for the printing of the next layer. This process is repeated until the entire entity is constructed.

[0004] However, due to limitations such as light scattering and free radical diffusion, common projection-based photopolymerization 3D printing systems generally struggle to print microporous structures with precision below 100 micrometers. Constructing such structures with high precision is of considerable significance, holding promising applications in biomedicine, micromechanics, and microelectronics. Therefore, to further expand the printing capabilities and application prospects of projection-based photopolymerization 3D printing technology, it is necessary to address the challenge of constructing microporous structures. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a microbubble-assisted projection-based photopolymerization 3D printing system and method based on projection-based photopolymerization 3D printing technology. This printing system adds a microbubble generating unit to the traditional projection-based photopolymerization 3D printer, consisting of a coated glass at the bottom of the material tank, a laser, a focusing module, and a laser control mechanism. This microbubble generating unit can generate microbubbles at the locations where microchannel structures need to be constructed to occupy space, thereby limiting over-curing from the source and realizing the construction of microchannel-like microstructures.

[0006] A microbubble-assisted projection-type photopolymerization 3D printing system includes a projection optical engine, a deposition platform and a lifting mechanism for controlling its lifting, a material tank and a peeling mechanism for controlling its tilting and peeling from the cured product, and a computer control component for installing a focusing module and controlling the operation of various mechanisms.

[0007] The bottom plate of the material tank is a light-transmitting coated glass with photothermal conversion function;

[0008] The printing system also includes a laser, a focusing module for focusing the light emitted by the laser onto the bottom of the coated glass, and a laser control mechanism for controlling the position of the laser focus.

[0009] The projection engine, deposition platform, lifting mechanism, material tank, peeling mechanism, and computer control components are all important components of a traditional projection-based photopolymerization 3D printer. The projection engine projects the pattern of the current slice to be printed onto the bottom of the material tank and solidifies the printing material between the deposition platform and the bottom of the tank. The projection engine can be a digital light processing engine, an LCD screen, or an engine using other principles. The deposition platform supports the printed structure (cured product). The lifting mechanism controls the rise and fall of the deposition platform to achieve layer-by-layer printing. The material tank supports the printing material; traditionally, the bottom plate of the material tank is made of transparent glass, but this invention uses light-transmitting coated glass with photothermal conversion function. The peeling mechanism controls the tilt of the material tank after curing, peeling the bottom plate of the material tank from the cured product (printed structure) to prepare for the next layer of printing.

[0010] As a preferred embodiment, the microbubble-assisted projection photopolymerization 3D printing system also includes a frame that serves as equipment support, on which the projection optical engine, deposition platform, lifting mechanism, peeling mechanism, material tank, focusing module and laser control mechanism are all mounted.

[0011] Alternatively, heating devices can be added to the feed tank and deposition platform to accommodate the printing needs of temperature-sensitive printing materials.

[0012] Preferably, the deposition platform can be surface-treated to improve the adhesion strength to the printed structure (cured product); the surface treatment can be sandblasting anodizing or other treatment methods.

[0013] The lifting mechanism and the peeling mechanism together constitute the printing motion device. The deposition platform is slidably mounted on one side of the lifting mechanism and located above the material trough. The lifting mechanism controls the position (height) of the deposition platform, thereby controlling the position of the printed structure. It can lift the printed structure, making room for the next layer of printing, thus enabling the stacking of printed structures to complete the printing process. The output end of the peeling mechanism is vertically upward and connected to the material trough. The other end of the material trough is supported by a material trough bracket, and the material trough and the material trough bracket are rotatably connected. This allows the peeling mechanism to drive the side of the material trough connected to it to descend, tilting the material trough and peeling the printed structure from the material trough, thus meeting the requirements of layer-by-layer printing.

[0014] The projection engine can be located below the material tank, or a reflector can be placed below the material tank to reflect the light pattern transmitted by the projection engine to the bottom of the material tank, thereby reducing the overall height of the printing system.

[0015] The printing material can be a photocurable resin, a photocurable hydrogel, a ceramic material, or other photocurable materials.

[0016] The laser, focusing module, and laser control mechanism together constitute the microbubble generating unit;

[0017] The laser is used to provide energy for the generation of microbubbles, and the light waves it emits are selected so as not to cause the printing material to solidify.

[0018] Alternatively, the laser can be fiber-optic output, meaning the laser is connected to the focusing module via an optical fiber to facilitate the arrangement of the printing system structure.

[0019] The focusing module is mounted on the frame and located below the material tank via a laser control mechanism. It is used to focus the light emitted by the laser to increase the laser energy density and reduce the laser spot size, which facilitates the generation of high-precision and high-efficiency microbubbles.

[0020] The focusing module can use a dedicated focusing lens or a microscope objective. Preferably, the focusing module includes a laser collimator and an objective lens connected in sequence to the laser.

[0021] The coated glass is the core component for microbubble generation. It absorbs light energy focused by the focusing module and converts it into heat energy. Since the coated glass also holds the printing material, it is in direct contact with the material. When it absorbs light energy and converts it into heat, the printing material in contact with it is heated. Due to the high power density of the laser, the heating power density of the coated glass is also high, causing the extremely small volume of printing material to heat up and vaporize instantaneously, thus generating microbubbles. Because the generated microbubbles are very small, they do not suddenly burst due to surface tension and other factors. Instead, they remain stable for a relatively long time and dissolve slowly. This allows the microbubbles to occupy a certain space during the photocuring process, preventing photocuring in the space they occupy. This creates a micropore in each layer of the printed structure. When multiple layers are stacked, the micropores connect to each other, thus creating a microchannel structure.

[0022] The reason why the coated glass can absorb light energy and convert it into heat energy is mainly due to the special coating on its surface. This coating can absorb the light emitted by the laser, while allowing the light emitted by the projection optical engine to pass through to achieve light curing printing.

[0023] Preferably, the coating is a titanium metal film or a gold metal film, or other coatings possessing the aforementioned properties. The coating can be applied by vapor deposition, ion sputtering, or other coating processes.

[0024] Preferably, the surface of the coated glass is treated with a hydrophobic coating. This hydrophobic treatment not only facilitates bubble adhesion but also aids in the peeling off of the printed structure. Because the coated glass surface is hydrophobically treated, microbubbles can adhere to it. This hydrophobic treatment can involve adding a coating such as fluorosilane, using a coating of PDMS, or employing other hydrophobic treatment processes.

[0025] The laser control mechanism is used to mount the focusing module and drive its movement to control the position of the laser focus, thereby achieving control over the microbubble generation location. The laser control mechanism can be an XY displacement platform, a laser galvanometer, a spatial light modulator, or other devices for adjusting the laser focus position.

[0026] Preferably, the laser control mechanism employs an XY displacement platform, including a laser X-axis, a laser Y-axis, an XYZ micro-manipulator, and a support rail. The laser Y-axis and support rail are mounted on the frame base plate, the laser X-axis is mounted on the laser Y-axis and support rail, and the XYZ micro-manipulator is mounted on the laser X-axis. The XYZ micro-manipulator is used to install and fix the focusing module and for initial system adjustment, ensuring the initial position of the laser focus is at the specified initial position. The laser X-axis and laser Y-axis are used to control the movement of the laser focus within the XY plane. The laser X-axis and laser Y-axis can be implemented using ball screw linear modules.

[0027] Preferably, the lifting mechanism can be a linear module or other driving device such as a linear motor.

[0028] Preferably, the stripping mechanism can be a linear module, or other drive devices such as a linear motor or a through motor.

[0029] Preferably, limit switches are installed on both the lifting mechanism and the stripping mechanism to enable them to return to zero, facilitating the use of the printing system. The limit switches can be mechanical or photoelectric.

[0030] As a preferred option, the lifting mechanism and the stripping mechanism can each be equipped with a closed-loop control system to further improve their positioning accuracy and repeatability.

[0031] The computer control component is connected to the lifting mechanism, peeling mechanism, projection optical engine, laser, and laser control mechanism to control the corresponding mechanisms during the printing process.

[0032] Preferably, the computer control component includes a host computer, a projection-type photopolymerization control component, and a microbubble generation control component. The host computer is used for human-computer interaction, generating cross-sectional slice images of the pre-printed 3D model at certain intervals along the printing direction and acquiring the position and size information of all microchannel structures in the pre-printed 3D model. It also generates printing control commands and coordinates the operation of all components. The projection-type photopolymerization control component controls the projection optical engine and the printing motion device (including a lifting mechanism and a peeling mechanism) to achieve conventional projection-type photopolymerization 3D printing. It can coordinate the projection optical engine to project the printed slice image with a specified light intensity according to the image data transmitted from the host computer and the printing control commands. It also controls the printing motion device's Z-axis (lifting mechanism) and Y-axis (peeling mechanism) to move to specified coordinates according to the printing control commands to achieve printing. The microbubble generation control component is used to generate microbubbles of a specified size at a specified location. It can control the laser to emit laser pulses of a specified power and length according to the printing control commands given by the host computer and drive the laser control mechanism to position the laser focus at a specified location, thereby achieving the generation of microbubbles of a specified size at a specified location.

[0033] The host computer can be a personal computer equipped with I / O devices such as a monitor, keyboard, and mouse, a Raspberry Pi with a display screen, an industrial control computer with dedicated I / O devices, or other devices. The host computer has software installed, which is responsible for its various tasks. This software has dual-port communication capabilities, enabling bidirectional communication with both the projection-type photopolymerization control component and the microbubble generation control component. The software can read the STL format file of the pre-printed 3D model and display it in a 3D environment, while providing model control functions including rotation, scaling, translation, centering, bottoming, and arraying, facilitating adjustments to relevant parameters by the operator. The software can generate cross-sectional images of the pre-printed 3D model at certain intervals along the printing direction and obtain the position and size information of all micropore structures in the pre-printed 3D model. The software can generate printing control commands; based on information such as layer height and exposure time provided by the operator, it can automatically generate a complete set of printing control commands according to syntax and store them in the host computer's memory. The software can monitor the printer's current operating status, reflecting the current printed layer height and the current projected image, making it easier for operators to understand the current work progress.

[0034] The projection-type light curing control component can be a microcontroller or other devices. The projection-type light curing control component is equipped with software that supports bidirectional communication with the host computer and the projection optical engine simultaneously. It also carries a print control command interpreter to interpret print control commands, drive the corresponding ports, and execute the corresponding commands.

[0035] The microbubble generation control component can be a microcontroller, a PLC, or other devices. The microbubble generation control component is equipped with software that supports bidirectional communication with the host computer, the laser, and the laser control mechanism. It also carries a printing control instruction interpreter to interpret printing control instructions, drive the corresponding ports, and execute the corresponding commands.

[0036] A microbubble-assisted projection-based photopolymerization 3D printing method includes the following steps:

[0037] (1) The computer control component slices the microchannel structure model to be printed and generates printing code;

[0038] (2) The computer control component controls the laser and laser control mechanism to emit laser pulses of set power and length to a set position at the bottom of the material tank according to the printing code, and causes the printing material to generate micro bubbles at the corresponding position;

[0039] (3) The lifting mechanism controls the deposition platform to descend to the set height, and then the projection optical engine works to project the corresponding slice layer image onto the printing material to solidify it;

[0040] (4) The computer control component controls the laser to cause the microbubbles to expand secondaryly;

[0041] (5) The peeling mechanism controls the tilting of the material tank to peel it off from the cured product. At the same time, the lifting component controls the deposition platform to rise. Then the peeling mechanism controls the material tank to reset, completing the single-layer printing.

[0042] (6) Repeat steps (1) to (5) until the printing of the entire microporous structure model is completed.

[0043] Preferably, in step (3), the descent height of the deposition platform is such that the distance between the deposition platform or the solidified product and the bottom of the material tank (i.e., the thickness of a single slice layer) is less than the radius of the microbubbles generated in step (2), so as to ensure the integrity of the micropore structure after the printed slice layers are stacked.

[0044] In step (2) above, the size of the generated microbubbles is determined by the laser emission power and the length of the laser pulse; in step (4), the same power and laser pulse length as in step (2) are used to make the microbubbles expand a second time at the same position, the purpose of which is to remove the film that may be generated at the top of the micropore during solidification.

[0045] As a preferred embodiment, a microbubble-assisted projection-based photopolymerization 3D printing method includes the following steps:

[0046] S1. The microchannel structure pre-printed 3D model is sliced, the position and size of the microchannel structure are obtained, and the printing control code is generated through the host computer.

[0047] S2. The microbubble generation control component controls the laser and the laser control mechanism to input laser pulses of specified power and length to a specified position at the bottom of the material tank according to the position and size of the microchannels to be printed, so that the printing material generates microbubbles of a specified size at the corresponding position.

[0048] S3. The projection-type photopolymerization control component controls the printing Z-axis (lifting mechanism) to drive the deposition platform down, so that the deposition platform or the printed structure is separated from the coated glass by the height of the corresponding slice layer (the height of the slice layer is less than the radius of the microbubble generated in step S2).

[0049] S4. The projection-type photocuring control component controls the projection optical engine to start exposure, projecting the specified slice image onto the printing material (bottom of the material tank), so that the material of one layer height is cured;

[0050] S5. The microbubble generation control component controls the laser and the laser control mechanism again to input a laser pulse of specified power and length to a specified position to make the microbubble expand secondary, so as to ensure the printing quality of the microchannel structure.

[0051] S6. The printing motion control component controls the printing Y-axis (peeling component) to tilt the material tank so that it peels off the printed structure. At the same time, the printing Z-axis (lifting mechanism) drives the deposition platform to rise to a higher position. Then the printing Y-axis drives the material tank back to its original position to complete the printing of a single-layer structure.

[0052] S7. Repeat steps S2 to S6 until the entire microporous structure model is printed.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] The microbubble-assisted projection-based photopolymerization 3D printing system of the present invention, by setting up a microbubble generating unit on the basis of a traditional projection-based tube-based curing 3D printer, utilizes the photothermal effect to generate microbubbles and uses microbubbles for occupancy, thereby realizing a projection-based photopolymerization 3D printing system capable of constructing micro-channel structures. This overcomes the difficulty of existing projection-based photopolymerization 3D printing systems in printing micro-channel structures and other micro-structures, effectively improving the printing capability of projection-based photopolymerization 3D printing technology and expanding the application scenarios of projection-based photopolymerization 3D printing technology.

[0055] The microbubble-assisted projection-based photopolymerization 3D printing system of this invention utilizes microbubbles to create microchannels. By precisely controlling the size of the microbubbles through laser power and pulse length, and by precisely controlling the position of the microbubbles through a laser control mechanism, this system enables a relatively low-precision projection-based photopolymerization 3D printing system to possess the ability to construct microstructures to a certain extent, effectively reducing equipment costs. This microbubble-assisted projection-based photopolymerization 3D printing system of the present invention can adapt to printing on various materials, including photopolymerizable resins and photopolymerizable hydrogels, and has broad application prospects. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the structure from another angle according to an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram illustrating the principle of printing microporous structures according to an embodiment of the present invention;

[0059] Figure 4 This is a photograph of a single-layer structure printed in an application example of the present invention;

[0060] Figure 5 In the figures, (a) is a microscopic image of a microchannel structure printed using the printing system in the embodiments of the present invention; and (b) is a microscopic image of a microchannel structure printed using a conventional printer.

[0061] In the diagram: 1-Frame, 2-Deposition platform, 3-Feed tank, 4-Coated glass, 5-Printing Z-axis, 6-Feed tank support, 7-Projection optical engine, 8-Mounting rail, 9-Laser, 10-Objective lens, 11-Printing Y-axis, 12-Y-axis support, 13-Laser collimator, 14-Laser X-axis, 15-Laser Y-axis, 16-Fiber optic cable, 17-XYZ micro-handle, 18-Reflector, 19-Support rail. Detailed Implementation

[0062] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0063] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "up," "down," and similar expressions used herein are for illustrative purposes only and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0065] A microbubble-assisted projection-based photopolymerization 3D printing system, such as Figure 1 and 2 As shown, it includes: a frame 1 and a projection optical engine 7, a deposition platform 2, a material tank 3, a printing Z-axis (lifting mechanism) 5, a printing Y-axis (peeling mechanism) 11, a laser 9, a focusing module, a laser control mechanism, and a computer control component mounted on the frame. The bottom plate of the material tank 3 is a light-transmitting coated glass 4 with photothermal conversion function.

[0066] The frame 1 includes a top plate and a bottom plate. The deposition platform 2 is mounted on the top plate of the frame via the printing Z-axis 5. The deposition platform 2 can be slidably mounted on one side of the printing Z-axis 5 via a connecting arm. The printing Z-axis 5 is used to control the up and down movement of the deposition platform 2 above the material tank 3, thereby controlling the position of the deposition platform 2 and the printed structure. It can lift the printed structure, leaving space for the next layer of printing, thus achieving the stacking of printed structures to finally complete the printing. One side of the material tank 3 is mounted on the top plate of the frame via the material tank bracket 6, and the other side is mounted on the top plate of the frame via the Y-axis bracket 12 and the printing Y-axis 11. One side of the material tank 3 is rotatably connected to the material tank bracket 6. The Y-axis bracket 12 is used to mount the printing Y-axis 11. The output end of the printing Y-axis 11 is vertically upward and connected to one side of the material tank 3, used to drive the connected side of the material tank 3 to descend, causing the material tank 3 to tilt, thereby peeling the printed structure from the material tank 3.

[0067] The projection optical engine 7 is located below one side of the material tank 3 and is mounted on the top plate of the frame via the mounting rail 8; a reflector 18 is also provided below the material tank 3, which is used to reflect the light emitted from the projection optical engine 7 to the bottom of the material tank 3 to achieve the curing of the printing material.

[0068] The projection optical engine 7 is used to project the pattern to be printed onto the printing material and to solidify the material. In this embodiment, the projection optical engine 7 is an optical engine using digital light processing technology, and the wavelength of the light it emits is 405nm.

[0069] The deposition platform 2 is used to support the printed structure. Its surface has been sandblasted and anodized to improve the adhesion strength with the printed structure. At the same time, the deposition platform 2 is equipped with heating equipment to meet the printing needs of some temperature-sensitive printing materials.

[0070] The material tank 3 is used to hold the printing material. The material tank 3 is also equipped with a heating device to meet the printing needs of some temperature-sensitive printing materials.

[0071] The Z-axis of printing uses a ball screw linear module, and the Y-axis of printing uses a through motor. Both the Z-axis and the Y-axis are equipped with limit switches to enable the Z-axis and the Y-axis to return to zero, which facilitates the use of the printing system. The limit switches are photoelectric limit switches.

[0072] Laser 9 is used to provide energy for the generation of microbubbles. The wavelength of the light emitted is 465nm, which will not cause the printing material to solidify. At the same time, laser 9 uses optical fiber 16 for light emission to facilitate the arrangement of the printing system. That is, laser 9 is connected to the focusing module through optical fiber.

[0073] The focusing module is mounted on the base plate of the frame via a laser control mechanism and is located on one side of the reflector 18 below the material tank 3. It includes a laser collimator 13 and an objective lens 10 connected in sequence to the laser. It is used to focus the light emitted by the laser 9 to improve the laser energy density and reduce the laser spot size, so as to facilitate the generation of high-precision and high-efficiency microbubbles. The objective lens 10 is a metallographic flat apochromatic ultra-long working distance objective lens.

[0074] The coated glass 4 is the core component for microbubble generation. It absorbs the light energy focused by the focusing module and converts it into heat energy. Since the coated glass 4 also serves to hold the printing material, it is in direct contact with the material. When it absorbs light energy and converts it into heat energy, the printing material in contact with it is heated. Due to the high power density of the laser, the heating power density of the coated glass 4 is also high, causing the extremely small volume of printing material to heat up and vaporize instantaneously, thus generating microbubbles. Because the generated microbubbles are very small, they do not suddenly burst due to surface tension and other factors. Instead, they remain stable for a long time and dissolve slowly. This allows the microbubbles to occupy a certain space during the photocuring process, preventing photocuring in the space occupied by the microbubbles. This creates a micropore in each printed layer. When layers are stacked, the micropores connect with each other, thus creating a microchannel structure.

[0075] The reason why the coated glass 4 can absorb light energy and convert it into heat energy is mainly due to the special coating on its surface. The coating can absorb the light emitted by the laser 9, while allowing the light emitted by the projection optical engine 7 to pass through to achieve light curing printing. The coating is made of titanium metal film and is processed using a vapor deposition process.

[0076] The hydrophobic treatment of the coated glass 4 not only enables bubble adhesion but also facilitates the peeling of the printed structure. This hydrophobic treatment is achieved by vapor-depositing a layer of fluorosilane onto the coated glass surface. Because of the hydrophobic treatment, microbubbles can adhere to the surface of the coated glass 4.

[0077] The laser control mechanism employs an XY displacement platform, including a laser X-axis 14, a laser Y-axis 15, an XYZ micro-manipulation stage 17, and a support rail 19, used to control the position of the laser focus, thereby controlling the microbubble generation position. The laser Y-axis 15 and the support rail 19 are mounted on the frame base plate, the laser X-axis 14 is mounted on the laser Y-axis 15 and the support rail 19, and the XYZ micro-manipulation stage 17 is mounted on the laser X-axis 14. The XYZ micro-manipulation stage 17 is used to install and fix the focusing module (objective lens 10, laser collimator 13) and to perform initial system adjustments, ensuring the initial position of the laser focus is at the specified initial position. The laser X-axis 14 and laser Y-axis 15 are used to control the movement of the laser focus in the XY plane, and both the laser X-axis 14 and laser Y-axis 15 use ball screw linear modules.

[0078] The computer control component includes a host computer, a projection-type photopolymerization control unit, and a microbubble generation control unit. The host computer is used for human-computer interaction, generating cross-sectional slice images of the pre-printed 3D model at certain intervals along the printing direction and acquiring the position and size information of all microchannel structures in the pre-printed 3D model. It also generates printing control commands and coordinates the operation of all components. The projection-type photopolymerization control unit controls the projection optical engine 7 and the printing motion device (printing Z-axis 5 and printing Y-axis 11) to achieve conventional projection-type photopolymerization 3D printing. It can coordinate the projection optical engine 7 to project the printed slice images with a specified light intensity according to the image data and printing control commands transmitted from the host computer, and control the printer's Z-axis and Y-axis to move to specified coordinates according to the printing control commands to achieve printing. The microbubble generation control unit is used to generate microbubbles of a specified size at a specified location. It can control the laser 9 to emit laser pulses of a specified power and length according to the printing control commands given by the host computer, and drive the laser control mechanism to position the laser focus at a specified location, thereby achieving the generation of microbubbles of a specified size at a specified location.

[0079] The host computer is a personal computer equipped with I / O devices such as a monitor, keyboard, and mouse. The host computer has software installed to handle its various tasks. This software features dual-port communication, enabling simultaneous bidirectional communication with the projection-type photopolymerization control unit and the microbubble generation control unit. The software can read STL format files of pre-printed 3D models and display them in a 3D environment, while providing model control functions including rotation, scaling, translation, centering, bottoming, and arraying, facilitating operator adjustments to relevant parameters. The software can generate cross-sectional images of the pre-printed 3D model at regular intervals along the printing direction and acquire the positional and dimensional information of all micropore structures within the model. The software can generate printing control commands; based on operator-provided information such as layer height and exposure time, it automatically generates a complete set of printing control commands and stores them in the host computer's memory. The software can monitor the printer's current operating status, displaying the current layer height and projected image, allowing operators to understand the current progress.

[0080] The projection-type light curing control component uses a single-chip microcomputer, which is low in cost and small in size and can be installed on a rack. It has internal software that supports bidirectional communication with the host computer and the projection optical engine 7. It also carries a print control command interpreter to interpret print control commands, drive the corresponding ports, and execute the corresponding commands.

[0081] The microbubble generation control component also uses a microcontroller, which is low in cost and small in size and can be installed on a rack. It contains software that supports bidirectional communication with the host computer, laser and laser control mechanism, and carries a printing control command interpreter to interpret printing control commands and drive the corresponding ports to execute corresponding commands.

[0082] The printing method of the above-mentioned microbubble-assisted projection photopolymerization 3D printing system includes the following steps:

[0083] S1. The microchannel structure pre-printed 3D model is sliced, the position and size of the microchannel structure are obtained, and the printing control code is generated through the host computer.

[0084] S2. The microbubble generation control component controls the laser and laser control mechanism to input laser pulses of specified power and length to a specified position at the bottom of the material tank according to the position and size of the microchannels to be printed, so that the printing material generates microbubbles of a specified size at the corresponding position.

[0085] S3. The projection-type photopolymerization control component controls the printing Z-axis (lifting mechanism) to drive the deposition platform to descend, so that the deposition platform or the printed structure is separated from the coated glass by the height of the corresponding slice layer, and the height of the slice layer is less than the radius of the microbubble generated in step S2.

[0086] S4. The projection-type light curing control component controls the projection optical engine to start exposure, projecting the specified slice image onto the printing material, causing the material of one layer height to cure.

[0087] S5. The microbubble generation control component controls the laser and laser control mechanism to input laser pulses of specified power and length to the specified position to make the microbubbles expand a second time, ensuring the printing quality of the microchannel structure;

[0088] S6. The printing motion control unit controls the printing Y-axis (peeling mechanism) to tilt the material tank so that the printed structure is peeled off. At the same time, the printing Z-axis drives the deposition platform to rise to a higher position. Then the printing Y-axis drives the material tank back to its original position to complete the printing of a single-layer structure.

[0089] S7. Repeat steps S2 to S6 until the entire microporous structure model is printed.

[0090] The principle of the microbubble and the entire microchannel process in step S2 above is as follows: Figure 3 As shown in the diagram, the deposition platform (shown as the printing deposition platform in the figure) is initially positioned high to allow space for microbubble generation. A laser pulse is then input to generate the microbubbles. The deposition platform then descends to the designated photocuring position, creating a printing layer height gap between the cured structure and the coated glass. A projection engine then performs projection exposure. Due to the presence of the microbubbles, the space they occupy cannot undergo photocuring, resulting in a micropore structure extending along the printing layer height after exposure. Finally, another laser pulse is input to cause the microbubbles to expand again, cleaning some of the film at the top of the micropores and further improving the quality of the micropores. This process is repeated, and by stacking micropore structures layer by layer, microchannels can be printed.

[0091] Application examples

[0092] 1. Using the microbubble-assisted projection-based photopolymerization 3D printing system and method described in the above embodiments, with 15% concentration PEGDA hydrogel printing ink as the printing material, a laser power of 563mW per pulse and a laser pulse length of 400ms, a microporous structure product is printed. The printed single-layer structure photograph is shown below. Figure 4 As shown, the microbubble size is only tens of micrometers, and the presence of microbubbles prevents the photocuring reaction from proceeding, thus forming micropores with a size of only tens of micrometers. This proves that the microbubble-assisted projection photocuring 3D printing system and method provided by the present invention can achieve the printing of microchannel structures with a size of less than one hundred micrometers.

[0093] 2. Using the same printing parameters and materials, the same microporous structure product was printed using both the microbubble-assisted projection-based photopolymerization 3D printing system and method described in the above embodiments and the traditional projection-based photopolymerization 3D printing system and method. The microscopic images of the micropores in the printed products are shown below. Figure 5 As shown. Comparison Figure 5 In (a) and (b), it can be seen that the micropore structure printed by the microbubble-assisted projection photopolymerization 3D printing system and method provided by the present invention is clear, complete and unobstructed; while the micropore structure printed by the traditional projection photopolymerization 3D printing system and method is basically difficult to observe traces, and the micropore structure is completely blocked.

[0094] In summary, this invention utilizes the photothermal effect to generate microbubbles and uses these microbubbles for occupancy, thereby realizing a projection-based photopolymerization 3D printing system capable of constructing microporous structures. This overcomes the difficulty of printing microporous structures in existing projection-based photopolymerization 3D printing systems, effectively improves the printing capability of projection-based photopolymerization 3D printing technology, and expands the application scenarios of projection-based photopolymerization 3D printing technology.

[0095] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

[0096] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0097] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A microbubble-assisted projection-type photopolymerization 3D printing system, comprising a projection optical engine, a deposition platform and a lifting mechanism for controlling its lifting, a material tank and a peeling mechanism for controlling its tilting and peeling from the cured product, and a computer control component for controlling the operation of each mechanism; characterized in that The bottom plate of the material tank is a light-transmitting coated glass with photothermal conversion function; The printing system also includes a laser, a focusing module for focusing the light emitted by the laser onto the bottom of the coated glass, and a laser control mechanism for mounting the focusing module and controlling the position of the laser focus.

2. The microbubble-assisted projection-style photocuring 3D printing system according to claim 1, wherein, The coating is a titanium metal film or a gold metal film.

3. The microbubble-assisted projection-type photopolymerization 3D printing system according to claim 1, characterized in that, The surface of the coated glass is hydrophobically treated.

4. A microbubble-assisted projection-based photopolymerization 3D printing method, characterized in that, The microbubble-assisted projection photopolymerization 3D printing system as described in any one of claims 1 to 3 includes the following steps: (1) The computer control component slices the microchannel structure model to be printed and generates printing code; (2) The computer control component controls the laser and laser control mechanism to emit laser pulses of set power and length to a set position at the bottom of the material tank according to the printing code, and causes the printing material to generate micro bubbles at the corresponding position; (3) The lifting mechanism controls the deposition platform to descend to the set height, and then the projection optical engine works to project the corresponding slice layer image onto the printing material to solidify it; (4) The computer control component controls the laser to cause the microbubbles to expand secondary; (5) The peeling mechanism controls the tilt of the material tank to peel it off from the cured product. At the same time, the lifting component controls the deposition platform to rise. Then the peeling mechanism controls the material tank to reset, completing the printing of a single layer. (6) Repeat steps (1) to (5) until the entire microchannel structure model is printed.

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