Multi-cell digital light processing printer and method with light field-magnetic field coupling regulation

Abstract

The application discloses a multi-cell digital light processing printer and method of light field-magnetic field coupling regulation. The application couples a magnetic field generating device with a light curing device, uses a magnetic field to control and replace microspheres with different cells and different magnetic contents in a tank, so that the replacement process is parallel to the printing process, and the printing efficiency is improved; meanwhile, the single-tank non-contact replacement is used, cross contamination is reduced, and multi-cell biological structures can be manufactured with high precision, high efficiency and high cell activity.

Description

Technical Field

[0001] This invention relates to a photopolymerization printer in the field of bio-3D printing and digital light processing, specifically involving a multi-cell digital light processing printing system and its printing method based on "light field-magnetic field" coupling regulation. Background Technology

[0002] DLP (Digital Light Processing) is a printing control method within the field of additive manufacturing. To replicate the biological environment of native tissues and realize their biological functions, multicellular bioprinting is an essential requirement for manufacturing complex tissues and organs and represents the future direction of bio-3D printing. Technologies include extrusion printing, inkjet printing, and photopolymerization printing. Among these, photopolymerization printing offers advantages such as high forming accuracy, fast forming speed, and ease of model construction.

[0003] Traditional multi-cell digital light processing printing processes use methods such as manual material changing, multi-tank material changing, and microfluidic material changing to achieve multi-material printing, but they still cannot achieve high-precision three-dimensional forming and high-efficiency multi-cell printing with ultra-flexible cell-carrying bio-inks. The main problems are as follows:

[0004] 1) The material changing and printing processes are sequential, resulting in low material changing efficiency;

[0005] 2) Multiple material tanks can cause cross-contamination and poor biological activity when changing materials.

[0006] To address the above issues, the material changing process is parallelized with the printing process to improve printing efficiency; simultaneously, non-contact single-slot material changing is used to reduce cross-contamination. Adding an external physical field is a suitable approach. In previous studies using external physical field assistance, magnetic and electric fields could only manipulate magnetic particles or polar electro-controlled polymers for printing heterogeneous or reinforced structures; acoustic fields could not control the arbitrary movement of particles within a plane, and optical fields could only manipulate small particles. In comparison, magnetic field assistance is a better choice, but several challenges remain in achieving multicellular bioprinting:

[0007] 1) Cells cannot be directly magnetized;

[0008] 2) Existing DLP equipment is not magnetically controllable;

[0009] 3) The material changing and printing process needs to be carried out in parallel and in a coordinated manner. Summary of the Invention

[0010] To address the problems existing in the background technology, this invention mainly proposes a multi-cell digital light processing printing process coupled and controlled by an "optical field-magnetic field". Cells are prepared in magnetic microspheres, and with the assistance of a magnetic field, the magnetic attraction of the magnetic field on magnetic particles is utilized to control the movement of the cell-containing magnetic microspheres, allowing the cells to reach the designated position for printing. The material changing process and the printing process are carried out in parallel, improving printing efficiency. At the same time, a single material tank is used for non-contact material changing, reducing cross-contamination. This invention realizes a new biomanufacturing process based on a single material tank that is "high-precision, high-efficiency, and high-cell-activity", providing a new method for the biomanufacturing of heterogeneous tissues / organs.

[0011] To achieve the above objectives, the present invention includes the following technical solutions:

[0012] I. A multi-cell digital light processing printer controlled by "light field-magnetic field" coupling

[0013] The multi-cell digital light processing printer includes a magnetic field generator and a photocuring device. The magnetic field generator is used to generate a magnetic field to control the aggregation and dispersion of magnetic microspheres carrying different cells, so that the target cells move to the target printing position. The photocuring device is used to control the biological ink containing the target cells to solidify and form at the target printing position.

[0014] The magnetic field generating device includes a power supply and a multi-pole electromagnet. The multi-pole electromagnet is installed in the photocuring device and is connected to the power supply.

[0015] The photocuring device includes a photomechanic, a stepper motor, a Z-axis lead screw, a forming platform, and a material tank;

[0016] The material tank is movably mounted on the optical engine. A forming platform is set above the material tank. A magnetic field generating device is set outside the material tank. The forming platform is connected to the Z-axis lead screw. A stepper motor is coaxially fixed to the Z-axis lead screw. The curing end of the forming platform is vertically aligned with the center of the material tank. The material tank is used to hold bio-ink. The stepper motor controls the rotation of the Z-axis lead screw, which drives the forming platform to move up and down along the Z-axis lead screw.

[0017] The multipole electromagnet is composed of multiple single-pole electromagnets arranged at intervals along the circumference. Each single-pole electromagnet includes an iron core, a metal frame, and a coil. One end of the iron core is set into a cone shape and is referred to as the cone end. The cone end of the iron core is located on the inner side. A metal frame is coaxially sleeved on the iron core except for the cone end. The metal frame includes at least two ring blocks. Multiple ring blocks are coaxially sleeved on the iron core at intervals. A coil is wound on the outer circumference of the iron core between two adjacent ring blocks. The outer diameter of the coil increases sequentially from the inner end to the outer end of each single-pole electromagnet.

[0018] The multipole electromagnet contains at least four monopole electromagnets.

[0019] The metal frame is an aluminum frame.

[0020] The bio-ink contains at least one type of cell, each cell being carried in microspheres with a corresponding magnetic content.

[0021] II. A Multi-Cell Digital Light Processing Printing Method with "Light Field-Magnetic Field" Coupling Regulation

[0022] 1) Microspheres carrying different cells and different magnetic contents are prepared in bio-ink, and then the bio-ink is dropped into the material tank;

[0023] 2) Determine the target pattern for each printing layer based on the multi-material printing model; before printing, adjust the distance between the multipole electromagnet, the optical engine and the material tank so that the photocuring printing plane P1 of the material tank coincides with the optimal magnetic field action plane P2 of the material tank in the gradient rotating magnetic field.

[0024] 3) In each printing layer, at each printing position of the corresponding target pattern, a corresponding target gradient rotating magnetic field is generated by controlling the multi-pole electromagnet in the magnetic field generator. The target gradient rotating magnetic field drives the microspheres with different magnetic contents and different cells in the material tank to aggregate or disperse, thereby obtaining the target cells at the current printing position. At the same time, the forming platform is driven to descend and the optomechanical projection is used to solidify the target cells at the current printing position, realizing the parallel processing of material changing and printing within the layer. After solidification is completed, 4) is executed.

[0025] 4) Change the printing position, raise the forming platform, and repeat 3) to solidify the target cells at different printing positions in the current printing layer until the current printing layer is completed;

[0026] 5) Repeat steps 3)-4) to print the remaining printing layers until the target three-dimensional structure is obtained.

[0027] The target cells at the current printing position include cells that are not present at the current printing position.

[0028] In step 3), the frequency and amplitude of the sinusoidal half-wave current transmitted from the power source to the multi-pole electromagnet are adjusted according to the magnetic content in different microspheres, thereby controlling the rotation frequency and field strength of the gradient rotating magnetic field, and thus controlling the aggregation or dispersion of microspheres carrying different cells and different magnetic contents, so that the target cells reach the target printing position.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. This invention uses cell microspheres as printing units, and the printing accuracy (~50μm) is controlled by the size of the microspheres. At the same time, the surface is used as the forming unit. Compared with extrusion and inkjet printing, the forming accuracy is high and the forming speed is fast.

[0031] 2. This invention uses magnetic field assistance to achieve material replacement in a single material tank. At the same time, the material replacement process is parallel to the printing process. Compared with traditional multi-material tank and sequential injection multi-material photopolymerization printing, it reduces cross-contamination and improves printing efficiency.

[0032] 3. This invention uses various cell microspheres for printing, which can realize the synchronous construction of multi-cell tissues in a single printing process and allow cells to be distributed arbitrarily in three-dimensional space. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the multi-cell continuous digital light processing printing system controlled by "light field-magnetic field" coupling in this invention.

[0034] Figure 2 A flowchart illustrating multicellular bioprinting using the printing system proposed in this invention.

[0035] Figure 3 This is a schematic diagram of a multipole electromagnet.

[0036] Figure 4 This is a schematic diagram of the structure of a multipole electromagnet core.

[0037] Figure 5 This is a schematic diagram of a monopole electromagnet.

[0038] In the diagram: 101, power supply; 102, multi-pole electromagnet; 201, optical engine; 202, stepper motor; 203, Z-axis lead screw; 204, forming platform; 205, material trough; 301, iron core; 302, metal frame; 303, coil. Detailed Implementation

[0039] To make the purpose and beneficial effects of the technology and equipment mentioned in this invention clearer, the equipment and technology of this invention will be further described below in conjunction with embodiments and accompanying drawings.

[0040] The specific equipment and steps for implementing this method are described in detail, along with accompanying diagrams:

[0041] The multi-cell photopolymerization printer includes a magnetic field generator and a photopolymerization unit. The magnetic field generator is used to generate a magnetic field to control the aggregation and dispersion of microspheres carrying different cells and different magnetic contents, so that the target cells move to the target printing position. The photopolymerization unit is used to control the bio-ink containing the target cells to solidify and form at the target printing position, that is, to solidify the bio-ink and print a three-dimensional structure layer by layer, fixing the cells in a specific distribution in the three-dimensional structure.

[0042] like Figure 1As shown, the magnetic field generating device includes a power supply 101 and a multi-pole electromagnet 102. The multi-pole electromagnet 102 is disposed between the photomechanical unit 201 and the forming platform 204 of the photocuring apparatus. The material tank 205 is disposed within the multi-pole electromagnet 102, and the multi-pole electromagnet 102 is connected to the power supply 101. The multi-pole electromagnet 102 is used to achieve multi-cell material exchange within a single material tank, gathering the target cells to the center of the material tank.

[0043] The photopolymerization device includes a photomechanical unit 201, a stepper motor 202, a Z-axis lead screw 203, a forming platform 204, and a material tank 205;

[0044] A material tank 205 is movably mounted on an optical engine 201, which projects patterns upwards. A forming platform 204 is positioned above the material tank 205. A multi-pole electromagnet 102 of a magnetic field generator is located outside the material tank 205, which is centered in the xy-plane where the electromagnet 102 is located. The material tank 205 can move up and down along the z-axis. The forming platform 204 is connected to a Z-axis lead screw 203 via a slider. A stepper motor 202 is coaxially fixed to the Z-axis lead screw 203. The curing end of the forming platform 204 is vertically aligned with the center of the material tank. The material tank 205 is used to hold bio-ink. Both the optical engine 201 and the stepper motor 202 are connected to corresponding power supplies. The stepper motor 202 controls the rotation of the Z-axis lead screw 203, causing the forming platform 204 to move up and down along the Z-axis lead screw 203.

[0045] The optical engine 201 projects a pattern upwards, solidifying the material in the material tank 205. The distance between the material tank 205 and the lens of the optical engine 201 can be adjusted via a leveling mechanism to regulate printing accuracy. The highest accuracy is achieved when the distance between the bottom surface of the material tank 205 and the lens of the optical engine 201 is equal to the optical engine's focal length f; at this point, the plane where the material tank 205 is located is the photopolymerization printing plane P1. The optical engine 201 and the material tank 205 can move up and down in a magnetic field to find the magnetic field plane with the best focusing and dispersing effect, denoted as the optimal magnetic field plane P2. The photopolymerization printing plane P1 is then aligned with the optimal magnetic field plane P2. The Z-axis lead screw 203 is fixed to the optical platform via a gantry frame. The forming platform 204 is connected and fixed to the Z-axis lead screw via a slider and rotated via a right-angle connector, vertically aligned with the center of the material tank to ensure that the movement of the forming platform 204 along the Z-axis during printing does not collide with the magnetic field generator. The entire mechanism is controlled by a host computer, which controls the stepper motor 202 to drive the Z-axis lead screw 203, thereby raising and lowering the forming platform 204. The stepper motor and photoengine receive signals from the host computer. After the target cell reaches the designated position, the stepper motor controls the Z-axis screw to rotate, and the forming platform descends to the printing height. After the forming platform is in place, the photoengine projects the pattern and solidifies the bio-ink, fixing the target cell in the designated position. After solidification, the forming platform is raised.

[0046] like Figure 3 , Figure 4 and Figure 5As shown, the multipole electromagnet 102 is composed of multiple monopole electromagnets arranged at equal intervals along the circumference. Each monopole electromagnet includes an iron core 301, a metal frame 302, and a coil 303. In this embodiment, the metal frame 302 is an aluminum frame. One end of the iron core 301 is set as a cone and is referred to as the cone end. The iron core 301 is arranged radially, and the cone end of the iron core 301 is located on the inner side. The cone ends of the iron core 301 in the multiple monopole electromagnets are arranged at intervals. Except for the iron core 301 at the cone end, the metal frame 302 is coaxially sleeved. The metal frame 302 includes at least two annular blocks. From the inner end to the outer end of each monopole electromagnet, multiple annular blocks are sequentially and coaxially sleeved on the outside of the iron core 301 and coaxially fixed to the iron core 301. A coil 303 is wound on the outer circumference of the iron core 301 between two adjacent annular blocks. From the inner end to the outer end of each monopole electromagnet, the outer diameter of the coil 303 increases sequentially. The iron core with tapered ends can better concentrate the magnetic field, generating a larger magnetic field gradient in the central part, while the metal frame does not affect the magnetic field distribution. An external power supply 101 supplies power to the multi-pole electromagnet 102, exciting the target magnetic field; the specific signal is controlled by a host computer, which switches the output frequency f of the four-channel sinusoidal half-wave current signal in conjunction with the photopolymerization printing process. HZ With amplitude I0, connecting to a multipole electromagnet 102 can generate gradient rotating magnetic fields of different frequencies and magnetic field intensities for the aggregation or dispersion of cell microspheres.

[0047] The multipole electromagnet 102 contains at least four monopole electromagnets.

[0048] In practice, the multi-pole electromagnet 102 uses a four-pole electromagnet. The coil in each monopole electromagnet can carry a maximum current of 10A and has an average resistance of 2.3Ω. When the maximum current is applied to any one of the electromagnets, the center of the multi-pole electromagnet 102 can generate a magnetic field with a maximum field strength of 150mT and a gradient of 27.5mT / m.

[0049] Bio-inks contain at least one type of cell, each type of cell is carried in microspheres with a corresponding magnetic content. Generally, the magnetic content of microspheres of different cell types is different, and microspheres may not contain cells.

[0050] A multi-cell photopolymerization printing method with "light field-magnetic field" coupling regulation includes the following steps:

[0051] 1) Cell microspheres with different magnetic contents are prepared in bio-ink, and then the bio-ink is dropped into the material tank 205;

[0052] 2) The target pattern for each printing layer is determined based on the multi-material printing model. The target pattern for each printing layer is projected onto the material tank 205 via the optomechanical system 201. In practice, the required multi-material printing model is designed using 3D software on a computer, and structural parameter files describing the model are generated for each material. Slice patterns and printing codes are generated using photopolymerization printing software. Before printing, the distance between the multipole electromagnet 102, the optomechanical system 201, and the material tank 205 is adjusted so that the photopolymerization printing plane P1 of the material tank 205 coincides with the optimal magnetic field action plane P2 of the material tank 205 in the gradient rotating magnetic field. The photopolymerization printing plane is obtained by the focal length f of the optomechanical lens. The optimal magnetic field action plane is obtained through magnetic microsphere dispersion and aggregation experiments, and the magnetic field height H with the shortest aggregation and dispersion time of the magnetic microspheres is selected as the optimal magnetic field action plane.

[0053] 3) In each printing layer, at each printing position of the corresponding target pattern, the multi-pole electromagnet 102 in the magnetic field generator is controlled by changing the power signal to generate a corresponding target gradient rotating magnetic field. The target gradient rotating magnetic field drives the microspheres with different magnetic contents and different cells in the material tank 205 to aggregate or disperse, thereby obtaining the target cells at the current printing position. At the same time, the forming platform 204 is driven to descend and the optomechanical system 201 projects onto the target cells at the current printing position to solidify them, thereby realizing parallel material exchange and printing within the layer. After solidification is completed, 4) is executed.

[0054] The target cells at the current printing position include cells that are not present at the current printing position, i.e., only bio-ink.

[0055] 4) Change the printing position, raise the forming platform 204, and repeat 3) to solidify the target cells at different printing positions in the current printing layer until the current printing layer is completed.

[0056] 5) Repeat steps 3)-4) to print the remaining printing layers until the target three-dimensional structure is obtained.

[0057] This invention uses a layer-by-layer material printing and exposure molding method to fix the aggregated cells in their respective positions sequentially. Through single-cell multi-cell digital light processing printing, a high-precision three-dimensional artificial tissue is constructed, forming the desired printed model.

[0058] In step 3), based on the magnetic content in different cell microspheres, the host computer adjusts the frequency and amplitude of the sinusoidal half-wave current transmitted from the power supply 101 to the multi-pole electromagnet 102, thereby controlling the rotation frequency and field strength of the gradient rotating magnetic field, and thus controlling the aggregation or dispersion of cell microspheres with different magnetic contents, so that the target cells reach the target printing position.

[0059] Specifically, the magnetic field used in this invention is controlled by a power source and needs to be matched with the magnetic responsiveness of the magnetically controlled microspheres carrying different cells, thereby manipulating the spatial distribution of the cell-carrying magnetically controlled microspheres to achieve the separation and high-precision positioning of various cells.

[0060] The rotation frequency and field strength distribution of the gradient magnetic field required for the aggregation and dispersion of cell microspheres with different magnetic contents were determined through magnetic microsphere dispersion and aggregation experiments, thereby determining the frequency f of the sinusoidal half-wave current required by the power supply output. HZ The amplitude I0 is also considered. Specifically, magnetic microspheres with a single magnetic content are added to a material tank in bio-ink. Based on the simulated current parameters, the frequency and amplitude of the sinusoidal half-wave current are adjusted from 1-100Hz and 0-10A. The movement trend and velocity of the magnetic microspheres are observed, and the range and time of aggregation and dispersion parameters of the microspheres under this magnetic content are recorded. Similarly, the range and time of aggregation and dispersion parameters of magnetic microspheres with different magnetic contents are measured. When two types of microspheres are mixed, the current parameter that can disperse the two types of microspheres in steps with the shortest dispersion time is selected as the corresponding control current.

[0061] Furthermore, in the microsphere preparation process, different cells are incorporated into magnetically controlled microspheres with varying magnetic responsiveness. By controlling the different response times of these microspheres to a magnetic field, different cells can be individually manipulated. The magnetic responsiveness is controlled by the amount of magnetic particles added, and the magnetic susceptibility (χ) of different magnetically responsive microspheres is also considered. m With the magnetic force F mag Relationship:

[0062]

[0063] Where m is the magnetic moment of the magnetic particle. χ is the magnetic flux density, μ0 is the free permeability, V is the volume of the magnetic particle, and χ is the magnetic flux density. m Let H be the magnetic susceptibility of the particle, and H be the magnetic field strength.

[0064] By applying the gradient rotating magnetic field measured in the above experiment to the material, and by switching the magnetic field rotation frequency and magnetic field intensity distribution, the aggregation and dispersion of magnetic microspheres can be achieved. Among these, the magnetic susceptibility χ... m Larger microspheres aggregate and disperse more quickly, while microspheres with lower magnetic susceptibility aggregate and disperse more slowly, thus distinguishing different cell-carrying magnetic microspheres.

[0065] Meanwhile, the microspheres are also subjected to drag force in the flow field. Due to the laminar flow of the liquid relative to the spheres, the drag force F on the particles is... D This can be described using Stokes' Law:

[0066] F D =3πμd p v

[0067] Where μ is the hydrodynamic viscosity, d p Let be the diameter of the microsphere, and v be the relative velocity of the microsphere to the fluid.

[0068] In the actual printing process, the "light field-magnetic field" collaborative printing process is planned as follows: the magnetic field controls the target microsphere to reach the designated position, the forming platform moves to the printing height at the same time, and the photomechanical projection is solidified; the forming platform is raised, the magnetic field switches to change the material, and the above process is repeated until the printing is completed.

[0069] The magnetic field switching time interval is precisely calculated and controlled by the dispersion time, aggregation time, forming platform descent time, and photomechanical exposure time of the magnetic microspheres in the current material tank. The photomechanical projection time interval is also calculated by the above parameters and the exposure time is controlled by the material properties, so that the curing of the bio-ink and the spatial positioning of the cell microspheres are completed synchronously.

[0070] Reference Figure 2 This invention utilizes the aforementioned system to perform multi-cell digital light processing printing with "light field-magnetic field" coupling control. The process can be divided into three stages:

[0071] The first stage is pretreatment. Taking GelMA bio-ink as an example, two types of magnetic microspheres containing different cells were added to a 5% GelMA solution and mixed thoroughly before being added to a feed tank 205. Microsphere A contains cell A with a magnetic content of 10%, while microsphere B contains cell B with a magnetic content of 1%. The required current parameter I for dispersing the magnetic field of microsphere A was also measured. Adisperse f Adisperse Required dispersion time T 1A The current parameter I required for the dispersion magnetic field of microsphere B Bdisperse f Bdisperse Required dispersion time T 1B The current parameter I required for the magnetic field to focus on microspheres. Aaggregate f Aaggregate Required aggregation time T 2A The current parameter I required for the magnetic field to gather B microspheres Baggregate f Baggregate Required aggregation time T 2B The time required for the forming platform 204 to descend is T3.

[0072] The second stage is printing. Each layer of printing can be divided into four steps: A-cell printing, B-cell printing, simultaneous A and B-cell printing, and cell-free printing. Each step can be categorized into three main actions: magnetic field application, printing, and magnetic field switching.

[0073] The first step is the simultaneous printing of AB cells. When the AB microspheres are initially uniformly dispersed in the solution, the forming platform 204 descends to a single layer height, and at the same time, the optomechanical system 201 projects and prints the AB cells simultaneously. After completion, the Z-axis lead screw 203 controls the forming platform 204 to rise.

[0074] The second step is B-cell printing. The magnetic field effect (specifically, a high-frequency magnetic field disperses the magnetic microspheres, while a low-frequency magnetic field aggregates them): The host computer controls the power supply 101 to sequentially supply sinusoidal half-wave currents with a 90° phase difference to the four poles of the multi-pole electromagnet 102, with the current parameter I... Adisperse f Adisperse A high-frequency, low-intensity gradient rotating magnetic field is generated to control the magnetic microspheres containing A cells with a higher magnetic content to disperse more quickly in all directions, leaving only the microspheres containing B cells in the material tank 205; Printing: The forming platform 204 is in (T 1A The descent begins at time -T3. Once the target cell has moved properly, it descends to the height of one layer. At this point, the optical engine 201 projects and prints B cells. After completion, the Z-axis lead screw 203 controls the forming platform 204 to rise.

[0075] Step 3, without cell printing. Magnetic field switching: The host computer controls the power supply 101 to sequentially supply sinusoidal half-wave currents with a 90° phase difference to the four poles of the multi-pole electromagnet 102, and its current parameter is switched to I. Bdisperse f Bdisperse Magnetic field effect: Multi-pole electromagnet 102 generates a high-frequency, high-intensity gradient rotating magnetic field to control the dispersion of B-cell-containing magnetic microspheres; the material tank does not contain microspheres; Printing: The forming platform 204 is in (T 1B At time -T3), the machine begins to descend. Once it reaches a height of one layer, the time machine 201 projects the image for cell-free printing. After completion, the Z-axis lead screw 203 controls the forming platform 204 to rise.

[0076] Step 4, A-cell printing. Magnetic field switching: The host computer controls the power supply 101 to sequentially supply sinusoidal half-wave currents with a 90° phase difference to the four poles of the multi-pole electromagnet 102, and the current parameter is switched to I. Aaggregate f Aaggregate ; Magnetic field effect: A low-frequency, low-intensity gradient rotating magnetic field generated by a multipole electromagnet controls the magnetic microspheres containing A cells with higher magnetic content to gather towards the center more quickly, while the magnetic microspheres containing B cells remain around the material tank 205; Printing: The forming platform 204 is in (T 2A At time -T3), the machine begins to descend. Once it reaches a height of one layer, the time machine 201 projects the A-cell for printing. After completion, the Z-axis lead screw 203 controls the forming platform 204 to rise.

[0077] At this point, the printing of one layer of the structure is complete.

[0078] Step 5: Cell aggregation; A and B cells are printed simultaneously. Magnetic field switching: The host computer controls the power supply 101 to sequentially supply sinusoidal half-wave currents with a 90° phase difference to the four poles of the multi-pole electromagnet 102, and the current parameter is switched to I. Baggregate f Baggregate ; Magnetic field effect: Multipole electromagnet 102 generates a low-frequency, high-intensity gradient rotating magnetic field to control the aggregation of B-cell magnetic microspheres to the center of the material tank 205; Printing: The forming platform 204 is in (T 2B At time -T3), the machine begins to descend to the second-layer height. The optical engine 201 projects and prints AB cells simultaneously. After completion, the Z-axis lead screw 203 controls the forming platform 204 to rise.

[0079] Repeat steps two through five above to complete the three-dimensional multicellular bioprinting.

[0080] The third stage is post-processing. The forming platform 204 is removed from the Z-axis lead screw 203, and the formed structure is removed with a scraper and placed in PBS solution for preservation. The dye used as a light absorber is removed by soaking. It can then be placed on a glass slide to absorb moisture for observation.

[0081] The above description is merely a specific example of the present invention and does not constitute any limitation on the present invention.

[0082] When cell C is added to the solution, three types of non-contact single-cell printing can be completed simultaneously.

[0083] This invention couples magnetic fields with light fields for multi-cell photopolymerization bioprinting, and plans the material changing process and printing process in parallel. This enables non-contact parallel material changing in a single material tank, improving printing efficiency and avoiding cross-contamination. At the same time, it uses cell microspheres as printing units, which can realize the arbitrary arrangement of various cells in three-dimensional space, and manufacture multi-cell biological structures with "high precision, high efficiency and high cell activity".

Claims

1. A multi-cell digital light processing printing method with "light field-magnetic field" coupling control, characterized in that, The printing method employs a multi-cell digital light processing printer controlled by "light field-magnetic field" coupling. The printer includes a magnetic field generator and a photocuring device. The magnetic field generator generates a magnetic field to control the aggregation and dispersion of magnetic microspheres carrying different cells, causing the target cells to move to the target printing position. The photocuring device controls the curing of bio-ink containing the target cells at the target printing position. The method includes the following steps: 1) Microspheres carrying different cells and different magnetic contents are placed in bio-ink, and then the bio-ink is dropped into the material tank (205); 2) Determine the target pattern of each printing layer according to the multi-material printing model; adjust the distance between the multipole electromagnet (102), the optical engine (201) and the material tank (205) so that the photocuring printing plane P1 of the material tank (205) coincides with the optimal magnetic field action plane P2 of the material tank (205) in the gradient rotating magnetic field; 3) In each printing layer, at each printing position of the corresponding target pattern, a corresponding target gradient rotating magnetic field is generated by controlling the multipole electromagnet (102) in the magnetic field generator. The target gradient rotating magnetic field drives the microspheres with different magnetic contents and different cells in the material tank (205) to aggregate or disperse, thereby obtaining the target cells at the current printing position. At the same time, the forming platform (204) is driven to descend and the optomechanical system (201) is projected to solidify the target cells at the current printing position, thereby realizing parallel material exchange and printing within the layer. After solidification is completed, 4) is executed. 4) Change the printing position, raise the forming platform (204), and repeat 3) to solidify the target cells corresponding to different printing positions in the current printing layer until the current printing layer is completed; 5) Repeat steps 3)-4) to print the remaining printing layers until the target three-dimensional structure is obtained.

2. The multi-cell digital light processing printing method according to claim 1, characterized in that, The target cells at the current printing position include cells that are not present at the current printing position.

3. The multi-cell digital light processing printing method according to claim 1, characterized in that, In step 3), the frequency and amplitude of the sinusoidal half-wave current transmitted from the power source (101) to the multipole electromagnet (102) are adjusted according to the magnetic content in different microspheres, thereby controlling the rotation frequency and field strength of the gradient rotating magnetic field, and thus controlling the aggregation or dispersion of microspheres carrying different cells and different magnetic contents, so that the target cells reach the target printing position.

4. The multi-cell digital light processing printing method according to claim 1, characterized in that, The magnetic field generating device includes a power supply (101) and a multipole electromagnet (102). The multipole electromagnet (102) is installed in the photocuring device and is connected to the power supply (101).

5. The multi-cell digital light processing printing method according to claim 1, characterized in that, The photocuring device includes a photomechanic (201), a stepper motor (202), a Z-axis lead screw (203), a forming platform (204), and a material tank (205). The material tank (205) is movably mounted on the optical engine (201). A forming platform (204) is set above the material tank (205). A magnetic field generating device is set outside the material tank (205). The forming platform (204) is connected to the Z-axis lead screw (203). The stepper motor (202) is coaxially fixed to the Z-axis lead screw (203). The curing end of the forming platform (204) is vertically aligned with the center of the material tank. The material tank (205) is used to hold bio-ink. The stepper motor (202) controls the Z-axis lead screw (203) to rotate, driving the forming platform (204) to move up and down along the Z-axis lead screw (203).

6. The multi-cell digital light processing printing method according to claim 1, characterized in that, The multipole electromagnet (102) is composed of multiple single-pole electromagnets arranged at intervals along the circumference. Each single-pole electromagnet includes an iron core (301), a metal frame (302), and a coil (303). One end of the iron core (301) is set as a cone and is referred to as the cone end. The cone end of the iron core (301) is located on the inner side. The metal frame (302) is coaxially sleeved outside the iron core (301) except for the cone end. The metal frame (302) includes at least two ring blocks. Multiple ring blocks are coaxially sleeved outside the iron core (301) at intervals. A coil (303) is wound on the outer circumference of the iron core (301) between two adjacent ring blocks. The outer diameter of the coil (303) increases sequentially from the inner end to the outer end of each single-pole electromagnet.

7. The multi-cell digital light processing printing method according to claim 1, characterized in that, The multipole electromagnet (102) contains at least four monopole electromagnets.

8. The multi-cell digital light processing printing method according to claim 6, characterized in that, The metal frame (302) is an aluminum frame.

9. The multi-cell digital light processing printing method according to claim 1, characterized in that, The bio-ink contains at least one type of cell, each cell being carried in microspheres with a corresponding magnetic content.

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