Multi-cell digital light processing printer and printing method based on "light field-magnetic field" coupling control

Abstract

Disclosed in the present invention are a multi-cell digital light processing printer and printing method based on "light field-magnetic field" coupling control. According to the present invention, a magnetic field generating device is coupled to a stereolithography device, and a magnetic field is used for controlling material change of microspheres carrying different cells and having different magnetic contents in a container, so that the material change process and the printing process are carried out in parallel, thereby improving the printing efficiency; and a single container is used for contactless material change, so that cross contamination is reduced, and a multi-cell biological structure can be manufactured in a high-precision, high-efficiency and high-cell-viability manner.

Description

Multi-cell digital light processing printer and method for "light field-magnetic field" coupling control Technical Field

[0001] The present invention relates to a light-curing printer in the field of biological 3D printing and digital light processing, and specifically relates to a multi-cell digital light processing printing system and a printing method thereof based on "light field-magnetic field" coupling regulation. Background Art

[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 the manufacture of complex tissues and organs, and a future direction for bio-3D printing. Technologies for this purpose include extrusion printing, inkjet printing, and stereolithography. Stereolithography offers the advantages of high forming accuracy, rapid build speed, and ease of model construction.

[0003] Traditional multi-cell digital light processing printing processes use methods such as manual material refilling, multi-tank refilling, and microfluidic refilling to achieve multi-material printing. However, they are still unable to achieve high-precision 3D shaping of ultra-flexible cell-laden bio-inks and high-efficiency multi-cell printing. The main problems are as follows:

[0004] 1) The material changing and printing processes are serial, and the material changing efficiency is low;

[0005] 2) Changing materials in multiple feed tanks may result in cross contamination and poor biological activity.

[0006] To address the above issues, the material changing process is carried out in parallel with the printing process to improve printing efficiency; at the same time, a contactless single-slot material changing process is used to reduce cross-contamination. External physical field assistance is a more appropriate method. In previous studies on external physical field assistance, magnetic fields and electric fields can only manipulate magnetic particles or polar electrically controlled polymers for printing heterogeneous or reinforced structures. Acoustic fields cannot control particles to move arbitrarily within a plane, and light fields can only manipulate small particles. In comparison, magnetic field assistance is a better choice, but there are still the following problems in realizing multicellular bioprinting:

[0007] 1) Cells cannot be directly magnetically controlled;

[0008] 2) Existing DLP devices cannot be magnetically controlled;

[0009] 3) The material change and printing processes need to be coordinated in parallel.

[0010] Summary of the Invention

[0011] In order to solve the problems existing in the background technology, the present invention mainly proposes a multi-cell digital light processing printing process with "light field-magnetic field" coupling regulation. The cells are prepared in magnetic microspheres, and by introducing magnetic field assistance and utilizing the attraction of the magnetic field to the magnetic particles, the movement of the cell-containing magnetic microspheres is controlled by the magnetic field, so that the cells reach the designated position to complete the printing, and the material changing process and the printing process are realized in parallel, thereby improving the printing efficiency; at the same time, a single material trough is used for contactless material changing to reduce cross contamination; a new biomanufacturing process with "high precision, high efficiency and high cell activity" based on a single material trough is realized, providing a new method for the biomanufacturing of heterogeneous tissues / organs.

[0012] In order to achieve the above object, the present invention includes the following technical solutions:

[0013] 1. A multi-cell digital light processing printer with optical-magnetic field coupling control

[0014] The multi-cell digital light processing printer includes a magnetic field generating device and a light curing device. The magnetic field generating device is used to generate a magnetic field to control the aggregation and dispersion of magnetic microspheres corresponding to different cells, so that the target cells move to the target printing position; the light curing device is used to control the biological ink containing the target cells to solidify and form at the target printing position.

[0015] The magnetic field generating device comprises a power supply and a multi-pole electromagnet. The multi-pole electromagnet is arranged in the light curing device and is connected to the power supply.

[0016] The light curing device includes an optical machine, a stepping motor, a Z-axis screw, a forming platform and a material trough;

[0017] The material trough is movably mounted on the optical machine, a forming platform is provided above the material trough, a magnetic field generating device is provided outside the material trough, the forming platform is connected to the Z-axis screw, the stepper motor is coaxially fixed to the Z-axis screw, the curing end of the forming platform is vertically aligned with the center of the material trough, and the material trough is used to place biological ink; the stepper motor controls the rotation of the Z-axis screw, driving the forming platform to move up and down along the Z-axis screw.

[0018] The multipolar electromagnet is composed of a plurality of monopole electromagnets arranged at intervals along the circumference, and each monopole electromagnet includes an iron core, a metal frame and a coil; one end of the iron core is set to a cone and is recorded as a conical end, and the conical end of the iron core is set on the inner side. In addition to the iron core at the conical end, a metal frame is coaxially sleeved. The metal frame includes at least two circular blocks, and the plurality of circular blocks are coaxially sleeved outside the iron core at intervals in sequence. A coil is wound on the outer circumference of the iron core between two adjacent circular blocks, and the outer diameter of the coil increases from the inner end to the outer end of each monopole electromagnet.

[0019] The multipolar electromagnet includes at least four monopolar electromagnets.

[0020] The metal frame is an aluminum frame.

[0021] The biological ink contains at least one type of cell, and each type of cell is carried in microspheres with corresponding magnetic content.

[0022] 2. A Multi-Cell Digital Light Processing Printing Method Using Light-Magnetic Field Coupling Control

[0023] 1) Microspheres loaded with different cells and different magnetic contents are placed in bio-ink, and then the bio-ink is dripped into a feed tank;

[0024] 2) Determine the target pattern for each printing layer based on the multi-material printing model; before printing, adjust the distance between the multi-pole electromagnet, the optical machine, and the material tank so that the light-curing 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;

[0025] 3) In each printing layer, at each printing position corresponding to the target pattern, the multi-pole electromagnet in the magnetic field generating device is controlled to generate a corresponding target gradient rotating magnetic field. The target gradient rotating magnetic field drives the microspheres containing different magnetic contents and different cells in the material tank to aggregate or disperse, thereby obtaining the target cells at the current printing position. Simultaneously, the forming platform is driven to descend and the optical projection is used to solidify the target cells at the current printing position, realizing parallel material replacement and printing within the layer. After solidification is completed, the process of step 4 is executed.

[0026] 4) Changing the printing position, raising the forming platform, and repeating step 3) to solidify the corresponding target cells at different printing positions within the current printing layer until the current printing layer is completed;

[0027] 5) Repeat 3)-4) to print the remaining printing layers until the target three-dimensional structure is obtained.

[0028] The target cell at the current printing position includes a cell that does not exist at the current printing position.

[0029] In the above 3), the frequency and amplitude of the sinusoidal half-wave current transmitted by the power supply to the multipolar electromagnet are adjusted according to the magnetic content of different microspheres, thereby controlling the rotation frequency and field strength of the gradient rotating magnetic field, and further controlling the aggregation or dispersion of microspheres carrying different cells and different magnetic contents, so that the target cells reach the target printing position.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present 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;

[0032] 2. This invention uses magnetic field assistance to achieve material change in a single material tank. At the same time, the material change process is parallel to the printing process. Compared with traditional multi-material light-curing printing such as multiple material tanks and sequential injection, it reduces cross contamination and improves printing efficiency.

[0033] 3. The present invention uses multiple cell microspheres for printing, which can achieve the simultaneous construction of multi-cellular tissues in a single printing process and arbitrarily distribute cells in three-dimensional space. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic structural diagram of a multi-cell continuous digital light processing printing system regulated by “light field-magnetic field” coupling in the present invention.

[0035] FIG2 is a flow chart of multicellular bioprinting using the printing system proposed in the present invention.

[0036] FIG3 is a schematic diagram of the structure of a multi-pole electromagnet.

[0037] FIG4 is a schematic structural diagram of a multi-pole electromagnet core.

[0038] FIG5 is a schematic structural diagram of a monopole electromagnet.

[0039] In the figure: 101, power supply; 102, multi-pole electromagnet; 201, optical machine; 202, stepper motor; 203, Z-axis lead screw; 204, forming platform; 205, trough; 301, iron core; 302, metal frame; 303, coil. DETAILED DESCRIPTION

[0040] In order to make the purpose, beneficial effects, etc. of the technology and equipment mentioned in the present invention clearer, the equipment and technology of the present invention are further described below in conjunction with embodiments and drawings.

[0041] Combined with the specific implementation method and the accompanying drawings, the specific equipment and steps for implementing the method are introduced in detail:

[0042] The multi-cell photocuring printer includes a magnetic field generating device and a photocuring device. The magnetic field generating device 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 photocuring device is used to control the biological ink containing target cells to solidify and form at the target printing position, that is, to solidify the biological ink and print the three-dimensional structure layer by layer, fixing the cells in the three-dimensional structure with a specific distribution.

[0043] As shown in Figure 1, the magnetic field generating device includes a power supply 101 and a multipolar electromagnet 102. The multipolar electromagnet 102 is positioned between the light machine 201 and the forming platform 204 of the light-curing device. The material trough 205 is positioned within the multipolar electromagnet 102, which is connected to the power supply 101. The multipolar electromagnet 102 is used to achieve multi-cell material exchange within a single material trough, concentrating the target cells at the center of the trough.

[0044] The light curing device includes an optical machine 201, a stepping motor 202, a Z-axis screw 203, a forming platform 204 and a material trough 205;

[0045] The trough 205 is movably mounted on the optical machine 201, which projects the pattern upward. A forming platform 204 is positioned above the trough 205. The multipolar electromagnet 102 of the magnetic field generator is positioned outside the trough 205, centered in the xy plane of the multipolar electromagnet 102. The trough 205 is movable up and down along the z-axis. The forming platform 204 is connected to the z-axis screw 203 via a slider. The stepper motor 202 is coaxially fixed to the z-axis screw 203, with the curing end of the forming platform 204 aligned vertically with the center of the trough. The trough 205 is used to hold the bio-ink. Both the optical machine 201 and the stepper motor 202 are connected to corresponding power supplies. The stepper motor 202 controls the rotation of the z-axis screw 203, driving the forming platform 204 up and down along the z-axis screw 203.

[0046] The optical machine 201 projects a pattern upward, solidifying the material in the trough 205. The distance between the trough 205 and the lens of the optical machine 201 can be adjusted using a leveling mechanism to adjust printing accuracy. Maximum accuracy is achieved when the distance between the bottom of the trough 205 and the lens of the optical machine 201 is equal to the focal length f of the optical machine. At this point, the trough 205 lies on the plane of photocuring printing plane P1. The optical machine 201 and the trough 205 can move up and down within a magnetic field to find the magnetic field plane with the best focusing and dispersing effects, designated as the optimal magnetic field plane P2. The photocuring printing plane P1 is aligned with the optimal magnetic field plane P2. The Z-axis screw 203 is secured to the optical platform via a gantry. The build platform 204 is attached to the Z-axis screw via a slider and connected via a right-angle connector, vertically aligned with the center of the trough. This ensures that the build platform 204's movement 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 screw 203, which in turn raises and lowers the build platform 204. The stepper motor and optical machine receive signals from the host computer. After the target cells reach the specified position, the stepper motor controls the rotation of the Z-axis screw, and the forming platform descends to the printing height. After the forming platform is in place, the optical machine projects the pattern to solidify the bio-ink, fixing the target cells in the specified position. After solidification, the forming platform is lifted.

[0047] As shown in FIG3 , FIG4 and FIG5 , the multipolar electromagnet 102 is composed of a plurality of monopolar electromagnets arranged at equal intervals along the circumference. Each monopolar 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 configured as a cone and is denoted as the cone end. The iron core 301 is arranged radially, with the cone end of the iron core 301 positioned inward. The cone ends of the iron core 301 are spaced apart in the plurality of monopole electromagnets. A metal frame 302 is coaxially sleeved around the iron core 301, excluding the cone end. The metal frame 302 comprises at least two circular rings. From the inner end to the outer end of each monopole electromagnet, the plurality of circular rings are coaxially sleeved around the iron core 301 and coaxially fixed thereto. A coil 303 is wound around the outer circumference of the iron core 301 between adjacent circular rings. The outer diameter of the coil 303 increases from the inner end to the outer end of each monopole electromagnet. The iron core with the cone end can better concentrate the magnetic field, generating a larger magnetic field gradient in the center. The metal frame does not affect the magnetic field distribution. The external power supply 101 supplies power to the multi-pole electromagnet 102 to excite the target magnetic field; the specific signal is controlled by the host computer, and the output frequency f of the four-channel half-sine wave current signal is switched in conjunction with the light-curing printing process. HZ and amplitude I0, respectively connected to the multi-pole electromagnet 102 to generate gradient rotating magnetic fields of different frequencies and different magnetic field intensities for aggregation or dispersion of cell microspheres.

[0048] The multi-pole electromagnet 102 includes at least four monopole electromagnets.

[0049] In a specific embodiment, the multipolar electromagnet 102 is a quadrupole electromagnet. Each monopole coil can carry a maximum current of 10A and an average resistance of 2.3Ω. When the maximum current is applied to any one of the poles, the center of the multipolar electromagnet 102 can generate a magnetic field with a maximum field strength of 150mT and a gradient of 27.5mT / m.

[0050] The bio-ink contains at least one type of cell, and each cell is carried in a microsphere with a corresponding magnetic content. Generally, the magnetic content of microspheres of different types of cells is different, and the microspheres may not contain cells.

[0051] A multi-cell photocuring printing method using light field-magnetic field coupling control, the method comprising the following steps:

[0052] 1) placing cell microspheres carrying different magnetic contents in bio-ink, and then dripping the bio-ink into the trough 205;

[0053] 2) Determine the target pattern for each printing layer based on the multi-material printing model. Each target pattern is projected onto the trough 205 via the optical machine 201. Specifically, the required multi-material printing model is designed on a computer using 3D software, and a file describing the model structure parameter is generated for each material. The slicing pattern and printing code are generated using the photocuring printing software. Before printing, the distance between the multi-pole electromagnet 102, the optical machine 201, and the trough 205 is adjusted so that the photocuring printing plane P1 of the trough 205 coincides with the optimal magnetic field action plane P2 of the trough 205 in the gradient rotating magnetic field. The photocuring printing plane is determined by the focal length f of the optical machine lens. The optimal magnetic field action plane is determined through magnetic microsphere dispersion and aggregation experiments. The magnetic field height H that minimizes the aggregation and dispersion time of the magnetic microspheres is selected as the optimal magnetic field action plane.

[0054] 3) In each printing layer, at each printing position corresponding to the target pattern, the multi-pole electromagnet 102 in the magnetic field generating device 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 containing different magnetic contents and different cells in the material trough 205 to aggregate or disperse, thereby obtaining the target cells at the current printing position. Simultaneously, the forming platform 204 is driven to descend, and the optical machine 201 is projected to solidify the target cells at the current printing position, achieving parallel material replacement and printing within the layer. After solidification is completed, execute 4);

[0055] The target cells at the current printing position include the case where no cells exist at the current printing position, that is, only bio-ink exists.

[0056] 4) Changing the printing position, raising the forming platform 204, and repeating step 3) to solidify the corresponding target cells at different printing positions within the current printing layer until the current printing layer is completed;

[0057] 5) Repeat 3)-4) to print the remaining printing layers until the target three-dimensional structure is obtained.

[0058] The present invention performs layer-by-layer material printing and exposure forming, so that the aggregated cells are fixed in their corresponding positions in sequence, and multi-cellular high-precision three-dimensional artificial tissue is constructed through single-tank multi-cell digital light processing printing to form the required printing model.

[0059] 3), according to the magnetic content of different cell microspheres, the host computer adjusts the frequency and amplitude of the sinusoidal half-wave current transmitted by the power supply 101 to the multipolar electromagnet 102, thereby controlling the rotation frequency and field strength of the gradient rotating magnetic field, and further controlling the aggregation or dispersion of cell microspheres carrying different magnetic contents, so that the target cells reach the target printing position.

[0060] Specifically, the magnetic field used in the present invention is controlled by a power supply and needs to match the magnetic responsiveness of magnetically controlled microspheres carrying different cells, thereby manipulating the spatial position distribution of the cell-carrying magnetically controlled microspheres to achieve the separation and high-precision positioning of multiple cells.

[0061] 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 are determined through magnetic microsphere dispersion and aggregation experiments, and the frequency f of the sinusoidal half-wave current output by the required power supply is determined accordingly. HZ Specifically, magnetic microspheres of a single magnetic content were placed in a bio-ink feed tank. Based on the current parameters obtained from simulation, the frequency and amplitude of the sinusoidal half-wave current were adjusted from 1-100Hz and 0-10A, respectively. The movement trend and speed of the magnetic microspheres were observed, and the parameter ranges and times for microsphere aggregation and dispersion at each magnetic content were recorded. Similarly, the parameter ranges and times for aggregation and dispersion of magnetic microspheres with different magnetic contents were measured. When two microspheres were mixed, the current parameter that could disperse the two microspheres step by step with the shortest dispersion time was selected as the corresponding control current.

[0062] In addition, different cells are prepared into magnetically controlled microspheres with different magnetic responsiveness. Different cells are controlled separately by the different speeds of the response of different magnetic responsive microspheres to the magnetic field, thereby achieving the manipulation of different cells. Among them, the magnetic responsiveness is controlled by the amount of magnetic particles added. The magnetic susceptibility of different magnetic responsive microspheres χ m and the magnetic field force F mag Relationship:

[0063] Where m is the magnetic moment of the magnetic particle, is the magnetic induction intensity, μ0 is the vacuum magnetic permeability, V is the volume of magnetic particles, χ m is the magnetic susceptibility of the particle, and H is the magnetic field strength.

[0064] Applying the gradient rotating magnetic field measured in the above experiment to the material, the aggregation and dispersion of magnetic microspheres can be achieved by switching the magnetic field rotation frequency and magnetic field intensity distribution. m Larger microspheres will aggregate and disperse faster, while microspheres with smaller magnetic susceptibility will aggregate and disperse slower, so different cell-carrying magnetic microspheres can be distinguished.

[0065] At the same time, the microspheres are also affected by drag in the flow field. Since the liquid moves in laminar flow relative to the spheres, the drag force F on the particles is D It can be described by Stokes' law: F D =3πμd p v

[0066] Where μ is the dynamic viscosity of the fluid, d pis the microsphere diameter, and v is the velocity of the microsphere relative to the fluid.

[0067] In the actual printing process, the "light field-magnetic field" collaborative printing process is planned as follows: the magnetic field controls the target microspheres to reach the specified position, the forming platform moves at the same time to reach the printing height, and the optical machine projection solidifies; the forming platform is lifted, the magnetic field switches to change the material, and the above process is repeated until printing is completed.

[0068] Among them, the magnetic field switching time interval is accurately calculated and controlled by the dispersion time, aggregation time, forming platform descent time, and optical machine exposure time of the magnetic microspheres in the current material tank. The optical machine 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 biological ink and the spatial positioning of the cell microspheres are completed synchronously.

[0069] 2 , the present invention utilizes the above system to perform multi-cell digital light processing printing with “light field-magnetic field” coupling control. The process is as follows and can be divided into three stages:

[0070] The first stage is pretreatment. Taking GelMA bio-ink as an example, two magnetic microspheres containing different cells are added to a 5% GelMA solution, mixed evenly, and then added to tank 205. Microsphere A contains cell A and has a magnetic content of 10%, while microsphere B contains cell B and has a magnetic content of 1%. The current parameter I required for microsphere A to disperse the magnetic field has also been measured. Adisperse 、f Adisperse , the required dispersion time T 1A , B The current parameter I required for the microsphere to disperse the magnetic field Bdisperse 、f Bdisperse , the required dispersion time T 1B ; A microsphere aggregation magnetic field required current parameter I Aaggregate , fAaggregate, required aggregation time T 2A , B The current parameter I required for the microspheres to gather in the magnetic field Baggregate , fBaggregate, required aggregation time T 2B ; Time T3 required for the forming platform 204 to descend.

[0071] 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.

[0072] The first step is to print AB cells simultaneously. When the AB microspheres are initially evenly dispersed in the solution, the forming platform 204 descends to a single layer height, while the optical machine 201 projects and prints AB cells simultaneously. After completion, the Z-axis screw 203 controls the forming platform 204 to rise.

[0073] The second step is B cell printing. Magnetic field effect (specifically, high-frequency magnetic field makes the magnetic microspheres disperse, and low-frequency magnetic field makes the magnetic microspheres aggregate): The host computer controls the power supply 101 to sequentially pass a sinusoidal half-wave current with a phase difference of 90° to the four poles of the multipolar electromagnet 102. The current parameter is I Adisperse 、f Adisperse , generating a high-frequency, low-intensity gradient rotating magnetic field to control the magnetic microspheres containing A cells with a larger magnetic content to disperse faster to the surroundings, leaving only the microspheres containing B cells in the trough 205; Printing: The forming platform 204 is at (T 1A -T3) starts to descend, and when the target cells are moved, it just descends to the height of one layer. At this time, the optical machine 201 projects and prints B cells. After completion, the Z-axis screw rod 203 controls the forming platform 204 to lift.

[0074] The third step is to print without cells. Magnetic field switching: The host computer controls the power supply 101 to sequentially pass a sinusoidal half-wave current with a phase difference of 90° to the four poles of the multipolar electromagnet 102, and the current parameter is switched to I Bdisperse 、f Bdisperse Magnetic field effect: The multipolar electromagnet 102 generates a high-frequency, high-intensity gradient rotating magnetic field to control the dispersion of magnetic microspheres containing B cells, and the trough does not contain microspheres; Printing: The forming platform 204 is (T 1B -T3) and starts to descend, and when it descends to a height of one layer, the time machine 201 projects and performs cell-free printing. After completion, the Z-axis screw rod 203 controls the forming platform 204 to lift.

[0075] Step 4: Cell A printing. Magnetic field switching: The host computer controls the power supply 101 to sequentially pass a sinusoidal half-wave current with a phase difference of 90° to the four poles of the multipolar electromagnet 102. The current parameter is switched to I Aaggregate , fAaggregate; Magnetic field effect: The multipolar electromagnet generates a low-frequency, low-intensity gradient rotating magnetic field to control the magnetic microspheres containing A cells with a larger magnetic content to gather faster toward the center, while the magnetic microspheres containing B cells remain around the trough 205; Printing: The forming platform 204 is (T 2A -T3) and starts to descend, and when it descends to a height of one layer, the time machine 201 projects and performs A cell printing. After completion, the Z-axis screw rod 203 controls the forming platform 204 to lift.

[0076] At this point, one layer of structure printing is completed.

[0077] Step 5: Gather cells and print AB cells simultaneously. Magnetic field switching: The host computer controls the power supply 101 to sequentially pass a sine half-wave current with a phase difference of 90° to the four poles of the multipolar electromagnet 102. The current parameter is switched to I Baggregate, fBaggregate; Magnetic field effect: The multipolar electromagnet 102 generates a low-frequency, high-intensity gradient rotating magnetic field to control the B cell magnetic microspheres to gather at the center of the trough 205; Printing: The forming platform 204 is (T 2B -T3) and starts to descend, descending to the height of the second floor, and the optical machine 201 projects and prints AB cells simultaneously. After completion, the Z-axis screw rod 203 controls the forming platform 204 to lift.

[0078] Repeat steps 2 to 5 to complete three-dimensional multicellular bioprinting.

[0079] The third stage is post-processing. The forming platform 204 is removed from the Z-axis screw 203, and the formed structure is removed with a scraper and placed in a PBS solution for storage to remove the dye that serves as a light absorber. The structure can then be placed on a glass slide to absorb moisture for observation.

[0080] The above description is only a specific example of the present invention and does not constitute any limitation to the present invention.

[0081] When cell C is added to the solution, three types of cells can be printed simultaneously in a non-contact single-tank system.

[0082] The present invention couples magnetic fields with light fields to perform multicellular photocuring bioprinting, and plans the material changing process and the printing process in parallel, so that multicellular bioprinting can achieve non-contact parallel material changing in a single material tank, improving printing efficiency and avoiding cross-contamination. At the same time, using cell microspheres as printing units can achieve arbitrary arrangement of multiple cells in three-dimensional space, and manufacture multicellular biological structures with "high precision, high efficiency and high cell activity".

Claims

1. A multi-cell digital light processing printer with "light field-magnetic field" coupling control, characterized in that: It includes a magnetic field generating device and a light curing device. The magnetic field generating device is used to generate a magnetic field to control the aggregation and dispersion of magnetic microspheres corresponding to different cells, so that the target cells move to the target printing position; the light curing device is used to control the biological ink containing the target cells to solidify and form at the target printing position.

2. A multi-cell digital light processing printer with "light field-magnetic field" coupling control according to claim 1, characterized in that: The magnetic field generating device comprises a power source (101) and a multi-pole electromagnet (102); the multi-pole electromagnet (102) is arranged in the light curing device, and the multi-pole electromagnet (102) is connected to the power source (101).

3. According to the multi-cell digital light processing printer with "light field-magnetic field" coupling control as claimed in claim 1, it is characterized in that: The light curing device comprises an optical machine (201), a stepping motor (202), a Z-axis screw rod (203), a forming platform (204) and a material trough (205); The material trough (205) is movably mounted on the optical machine (201); a forming platform (204) is arranged above the material trough (205); a magnetic field generating device is arranged outside the material trough (205); the forming platform (204) is connected to a Z-axis screw rod (203); a stepping motor (202) is coaxially fixedly connected to the Z-axis screw rod (203); a solidifying end of the forming platform (204) is vertically aligned with the center of the material trough; the material trough (205) is used to place biological ink; the stepping motor (202) controls the rotation of the Z-axis screw rod (203) to drive the forming platform (204) to move up and down along the Z-axis screw rod (203).

4. A multi-cell digital light processing printer with "light field-magnetic field" coupling control according to claim 2, characterized in that: The multipolar electromagnet (102) is composed of a plurality of monopolar electromagnets arranged at intervals along a circumference, and each monopolar electromagnet comprises an iron core (301), a metal frame (302) and a coil (303); one end of the iron core (301) is arranged in a conical shape and is recorded as a conical end, and the conical end of the iron core (301) is arranged on the inner side, and a metal frame (302) is coaxially sleeved outside the iron core (301) except for the conical end, and the metal frame (302) comprises at least two circular ring blocks, and the plurality of circular ring blocks are coaxially sleeved outside the iron core (301) at intervals in sequence, and a coil (303) is wound outside the outer circumference of the iron core (301) between two adjacent circular ring blocks, and the outer diameter of the coil (303) increases in sequence from the inner end to the outer end of each monopolar electromagnet.

5. According to claim 2, a multi-cell digital light processing printer with "light field-magnetic field" coupling control is characterized in that: The multi-pole electromagnet (102) includes at least four monopole electromagnets.

6. A multi-cell digital light processing printer with "light field-magnetic field" coupling control according to claim 5, characterized in that: The metal frame (302) is an aluminum frame.

7. A multi-cell digital light processing printer with "light field-magnetic field" coupling control according to claim 3, characterized in that: The biological ink contains at least one type of cell, and each type of cell is carried in microspheres with corresponding magnetic content.

8. A multi-cell digital light processing printing method with "light field-magnetic field" coupling regulation, characterized in that: The printing method adopts the multi-cell digital light processing printer controlled by the "light field-magnetic field" coupling control according to any one of claims 1 to 7, and the method comprises the following steps: 1) placing microspheres carrying different cells and different magnetic contents in biological ink, and then dripping the biological ink into a material tank (205); 2) determining the target pattern of each printing layer according to the multi-material printing model; adjusting the distance between the multi-pole electromagnet (102), the optical machine (201) and the material tank (205) so that the light-curing 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 corresponding to the target pattern, the multi-pole electromagnet (102) in the magnetic field generating device is controlled to generate a corresponding target gradient rotating magnetic field, and the target gradient rotating magnetic field drives the microspheres containing 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 optical machine (201) is projected to solidify the target cells at the current printing position, thereby realizing the parallelization of material replacement and printing within the layer, and after the solidification is completed, 4) is executed; 4) changing the printing position, raising the forming platform (204), and repeating 3) to solidify the corresponding target cells at different printing positions in the current printing layer until the current printing layer is completed; 5) Repeat 3)-4) to print the remaining printing layers until the target three-dimensional structure is obtained.

9. The multi-cell digital light processing printing method of "light field-magnetic field" coupling control according to claim 1 is characterized in that: The target cell at the current printing position includes a cell not existing at the current printing position.

10. The multi-cell digital light processing printing method of "light field-magnetic field" coupling control according to claim 1 is characterized in that: In the above 3), the frequency and amplitude of the sinusoidal half-wave current transmitted by the power supply (101) to the multipolar electromagnet (102) are adjusted according to the magnetic content of different microspheres, thereby controlling the rotation frequency and field strength of the gradient rotating magnetic field, and further controlling the aggregation or dispersion of microspheres carrying different cells and different magnetic contents, so that the target cells reach the target printing position.

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