A biological material droplet ejection device

Abstract

The present invention discloses a biological material droplet ejection device, which includes a fixed part and a detachable non-fixed part. The fixed part includes a housing, an upper limit threaded post, an upper limit piece, a piezoelectric ceramic stack, a lower limit piece and a large spring. The top and bottom of the housing are respectively provided with coaxial upper through holes and lower through holes. The upper through hole is partially threadedly connected to the upper limit threaded post. The upper limit piece, the piezoelectric ceramic stack, the lower limit piece and the large spring are sequentially arranged inside the housing from top to bottom. The non-fixed part includes an annular piece, a cylindrical sleeve, a small spring, a cylindrical sleeve vertical guide and a liquid storage cylinder needle. The lower through hole is partially threadedly connected to the cylindrical sleeve vertical guide. The annular piece and the small spring are arranged inside the large spring. The device is small in size, convenient to disassemble and assemble, can print high-viscosity biological ink, and can flexibly adjust the size and frequency of ejected biological material droplets.

Description

Technical Field

[0001] The invention belongs to the technical field of biomaterial jetting, and in particular relates to a biomaterial droplet jetting device. Background Art

[0002] 3D printing technology has been maturely applied in the field of engineering. This technology is no longer limited to the field of engineering. It has gradually played an important role in leading innovation in the field of bioprinting. At present, biological 3D printing technology is still a novel and interdisciplinary frontier technology to be developed. This technology can accurately regulate biological materials such as cells and active factors. In the study of biological 3D printing, the commonly used technologies are extrusion, laser-assisted, photocuring and inkjet bioprinting technology. Extrusion bioprinting is widely used in bioprinting research due to its simple process and has developed rapidly. This technology does not have particularly strict requirements for biological materials. Biological materials such as cell spheres and microcarriers can be printed by extrusion. However, extrusion bioprinting is more suitable for making larger structures, and its ability to print microstructures is obviously insufficient. The frequency of biological droplets formed by laser-assisted bioprinting technology can reach kilohertz, which far exceeds the printing rate of other technologies. Although laser-assisted bioprinting technology has the advantage of high speed, this technology is very complicated and costly, and the instantaneous high temperature and high pressure generated by the laser act on the biological material, which can easily reduce the activity of the printed biological material. Photocuring bioprinting technology uses the physical property of photosensitive materials that can be cured by light to perform 3D printing. It must use photosensitive materials as printing materials, so there are relatively few types of biomaterials that can be selected. In addition, the ultraviolet light it usually uses also has a very adverse effect on the activity of biomaterials. Inkjet bioprinting technology has high requirements for the solid content and viscosity of the biomaterial ink to be sprayed. The viscosity of the sprayed biomaterial can only be in a relatively low range (usually less than 20mPas). Bioinks with low viscosity are not conducive to the suspension of biomaterials such as cells, so that the biomaterials in the ink cannot be sprayed out evenly with droplets. In order to solve the problems of reduced survival rate of biomaterials such as cells and active factors in biological 3D printing; uneven generation of droplets containing biomaterials such as cells and active factors; high cost; complex process; low viscosity of printable ink; and easy clogging of the nozzle, the present invention proposes an on-demand spraying device for spraying biomaterials such as cells and active factors under the action of water hammer. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention proposes a biomaterial droplet injection device, which has a reasonable design, solves the shortcomings of the prior art and has good effects.

[0004] A biological material droplet ejection device, comprising a fixed part and a detachable non-fixed part. The fixed part includes a housing, an upper limit threaded post, an upper limit sheet, a piezoelectric ceramic stack, a lower limit sheet, and a large spring. The top and bottom of the housing are respectively provided with coaxial upper through holes and lower through holes. The upper through hole is partially threadedly connected to the upper limit threaded post. The upper limit sheet, the piezoelectric ceramic stack, the lower limit sheet, and the large spring are sequentially arranged inside the housing from top to bottom;

[0005] The non-fixed part includes a circular ring sheet, a cylindrical sleeve, a small spring, a vertical guide for the cylindrical sleeve, and a liquid storage cylinder needle. The lower through hole is partially threadedly connected to the vertical guide for the cylindrical sleeve. The circular ring sheet and the small spring are arranged inside the large spring.

[0006] Further, the bottom surface of the large spring is adhered to the inner bottom surface of the housing, and the top of the large spring contacts the bottom surface of the lower limit sheet.

[0007] Further, first grooves are respectively provided on the top surface of the lower limit sheet and the bottom surface of the upper limit sheet, so that the top and bottom ends of the piezoelectric ceramic stack are respectively embedded in the two first grooves;

[0008] The top surface of the upper limit sheet is provided with an arc-shaped concave surface, and the bottom end of the upper limit threaded post is provided with a hemispherical protrusion, and the hemispherical protrusion contacts the arc-shaped concave surface;

[0009] The bottom surface of the lower limit sheet is provided with a second groove, and a part of the circular ring sheet is embedded in the second groove.

[0010] Further, the vertical guide for the cylindrical sleeve is a four-layer circumferential stepped structure with diameters increasing sequentially from top to bottom. The first stepped structure at the top is located inside the small spring. One end of the small spring abuts against the circular ring sheet, and the other end abuts against the horizontal table surface of the second stepped structure. A part of the third stepped structure and the fourth stepped structure is threadedly connected to the lower through hole.

[0011] Further, vertical through holes are provided in the upper limit threaded post, the upper limit sheet, the piezoelectric ceramic stack, the lower limit sheet, and the vertical guide for the cylindrical sleeve. Each vertical through hole, the large spring, the small spring, and the circular ring sheet are coaxial with the upper through hole and the lower through hole. The two ends of the upper limit threaded post and the vertical guide for the cylindrical sleeve respectively extend out of the upper through hole and the lower through hole.

[0012] Further, the cylindrical sleeve is sequentially passed through the vertical through holes of the circular ring sheet, the small spring, and the vertical guide for the cylindrical sleeve, and is adhesively fixed to the inner wall of the circular ring sheet. The bottom end of the cylindrical sleeve extends out of the vertical guide for the cylindrical sleeve;

[0013] The liquid storage cylinder needle is sequentially passed through the vertical through holes of the upper limit screw column, the upper limit piece, the piezoelectric ceramic, the lower limit piece and the cylindrical sleeve, and the end of the liquid storage cylinder needle is adhesively fixed to the inside of the end of the cylindrical sleeve. The bottom end of the liquid storage cylinder needle extends out of the cylindrical sleeve, and its top end extends out of the upper limit screw column.

[0014] Further, by rotating the upper limit screw column downward, the large spring is in a compressed state, so that the entire fixed part is closely fitted together and a certain pre-tightening force is formed.

[0015] By rotating the vertical guide of the cylindrical sleeve upward, the non-fixed part makes the small spring in a compressed state, so that the entire non-fixed part is closely fitted together and a certain pre-tightening force is formed.

[0016] Further, the housing, the upper limit piece, the lower limit piece, the circular ring piece, the cylindrical sleeve and the vertical guide of the cylindrical sleeve are made of hard materials that are not easily deformed, and the liquid storage cylinder needle is made of a material that does not damage the biological material ink. The biological material ink is continuously injected through the top opening of the liquid storage cylinder needle, and a small hole is opened at the bottom end of the liquid storage cylinder needle as a nozzle for spraying the biological material ink.

[0017] Further, when the signal generator and the power amplifier are connected to the piezoelectric ceramic stack, the biological material ink is injected into the liquid storage cylinder needle. The signal generator and the power amplifier drive the piezoelectric ceramic stack to expand and contract, and then drive the cylindrical sleeve to move up and down quickly. The liquid storage cylinder needle will also move up and down quickly following the cylindrical sleeve. Among them, the large spring and the small spring remain in a compressed state after being assembled, providing a certain pre-tightening force for the fixed part and the non-fixed part of the device.

[0018] By replacing the liquid storage cylinder needle with different nozzle diameters, the ejection liquid diameter of the biological material can be greatly adjusted; by adjusting the amplitude and frequency of the signal generator, the amplitude of the up and down movement of the liquid storage cylinder needle and the time required for one cycle of the up and down movement are changed, which is equivalent to changing the ejection force and movement speed of the liquid storage cylinder needle of the device, and then adapting to biological material inks with different viscosities, and realizing fine adjustment of the diameter of the biological material droplets ejected by the same nozzle diameter.

[0019] The beneficial technical effects brought by the present invention:

[0020] 1. It is convenient to use a cylindrical needle with different nozzle holes for printing. Different diameters of biomaterial droplets can be ejected by replacing the liquid storage cylindrical needle with different nozzle diameters. This method can greatly adjust the diameter of the ejected droplets of biomaterials. Moreover, according to different inks and printing requirements, cylindrical needles with different nozzle hole sizes can be used. Large-hole needles are for efficient printing, and small-hole needles are for high-precision printing. The overall structure of the present invention is divided into a fixed part that is not disassembled after assembly and a non-fixed part that can be conveniently disassembled. The non-fixed part is for facilitating the replacement of the liquid storage cylindrical needle to achieve the convenient replacement of the biomaterial in the liquid storage cylindrical needle.

[0021] 2. The device can flexibly adjust the size and frequency of the ejected biomaterial droplets. The present invention utilizes the water hammer principle for ejecting biomaterial droplets. A signal generator and a power amplifier are used to drive the device, thereby enabling the liquid storage cylindrical needle to move up and down rapidly, driving a part of the biomaterial inside the needle to form droplets through the nozzle at the bottom of the needle. By adjusting the waveform parameters in the signal generator, the rate, amplitude of the up and down movement of the nozzle of the device, and the printing ejection frequency can be precisely controlled. This method can quickly achieve fine adjustment of the size of biomaterial droplets without replacing the liquid storage cylindrical needle.

[0022] 3. The ejection pressure is moderate and will not have an adverse impact on the activity of biomaterials. This device utilizes the inertial force of the biomaterial ink itself to generate the pulsed pressure required for ejection. The pressure amplitude is much smaller than that generated by laser ejection, and the ejection process has less impact on the activity of biomaterials.

[0023] 4. The device has low cost, non-blocking nozzles, and can print high-viscosity materials. The overall size of the device is small, with few components. The motion drive is direct drive, avoiding problems such as insensitive response caused by the cooperation and transmission of too many components. Moreover, it has low cost and non-blocking nozzles. By adjusting the amplitude and frequency parameters of the signal generator, the action force and time of the liquid storage cylindrical needle can be changed, thereby adapting to biomaterial inks with different viscosities. Description of the Drawings

[0024] Figure 1 is a perspective view of the biomaterial droplet ejection device in the present invention;

[0025] Figure 2 is a front view of the biomaterial droplet ejection device in the present invention;

[0026] Figure 3 is a cross-sectional view of the biomaterial droplet ejection device in the present invention;

[0027] Figure 4 is a schematic diagram of the fixed part in the present invention;

[0028] where (a) is a cross-sectional view of the fixed part; (b) is a perspective view of the fixed part;

[0029] Figure 5 Cross-sectional view of the non-fixed part of the present invention;

[0030] Wherein, 1 - upper limit threaded post; 2 - housing; 3 - upper limit piece; 4 - piezoelectric ceramic stack; 5 - lower limit piece; 6 - circular ring piece; 7 - large spring; 8 - small spring; 9 - cylindrical sleeve vertical guide; 10 - cylindrical sleeve; 11 - liquid storage cylinder needle; Detailed implementation manners

[0031] The following further describes the detailed implementation manners of the present invention in conjunction with specific embodiments:

[0032] A biological material droplet ejection device, as Figures 1-5 shown, includes a fixed part and a detachable non-fixed part. The fixed part includes a housing 2, an upper limit threaded post 1, an upper limit piece 3, a piezoelectric ceramic stack, a lower limit piece 5, and a large spring 7. The top and bottom of the housing are respectively provided with coaxial upper and lower through holes. The upper through hole is threadedly connected to the middle part of the upper limit threaded post 1. Both ends of the upper limit threaded post 1 extend out of the upper through hole. The upper limit piece 3, the piezoelectric ceramic stack, the lower limit piece 5, and the large spring 7 are sequentially arranged inside the housing 2 from top to bottom;

[0033] The non-fixed part includes a circular ring piece 6, a cylindrical sleeve 10, a small spring 8, a cylindrical sleeve vertical guide 9, and a liquid storage cylinder needle 11. The lower through hole is threadedly connected to a part of the cylindrical sleeve vertical guide 9. Both ends of the cylindrical sleeve vertical guide 9 extend out of the lower through hole. The circular ring piece 6 and the small spring 8 are arranged inside the large spring 7 from top to bottom.

[0034] The bottom surface of the large spring 7 is adhered to the inner bottom surface of the housing 2 by epoxy resin, and the top of the large spring 7 contacts the bottom surface of the lower limit piece 5.

[0035] The top surface of the lower limit piece 5 and the bottom surface of the upper limit piece 3 are respectively provided with first grooves, so that the top and bottom ends of the piezoelectric ceramic stack are respectively embedded in the two first grooves;

[0036] The top surface of the upper limit piece 3 is provided with an arc-shaped concave surface. The center position of the bottom end of the upper limit threaded post is provided with a hemispherical protrusion. The bottom of the hemispherical protrusion contacts the arc-shaped concave surface, and the cross-sectional area of the upper limit threaded post is smaller than the cross-sectional area of the upper limit piece. Therefore, the edge of the bottom end of the upper limit threaded post can contact the arc-shaped concave surface;

[0037] The bottom surface of the lower limit piece 5 is provided with a second groove, and a part of the circular ring piece 6 is embedded in the second groove;

[0038] The cylindrical sleeve vertical guide 9 is a four-layer circumferential stepped structure with diameters increasing sequentially from top to bottom. From top to bottom, it includes the first stepped structure, the second stepped structure, the third stepped structure, and the fourth stepped structure. The first stepped structure and the second stepped structure are located inside the large spring 7. Since the small spring 8 is located inside the large spring 7, the first stepped structure is located inside the small spring 8. One end of the small spring 8 abuts against the circular ring piece 6, and the other end abuts against the horizontal tabletop of the second stepped structure. Part of the third stepped structure and the fourth stepped structure has external threads and is threadedly connected to the lower through hole. The remaining part of the fourth stepped structure extends out of the lower through hole.

[0039] Both sides of the upper limit piece 3 and the lower limit piece 5 are very close to the inner wall of the housing 2 and maintain a certain gap to ensure that when the upper limit threaded post 1 is rotated downward to tightly fit the entire fixed part together, the components will not be deflected, and the components are kept on the central axis of the entire device. Coupled with the cooperation of the grooves provided in the centers of the respective limit pieces, the through holes in the centers of the respective components are on the central axis of the entire device. Finally, the cylindrical sleeve 10 is sequentially inserted into the vertical through holes of the circular ring piece 6, the small spring 8, and the cylindrical sleeve vertical guide 9, and is fixedly bonded to the inner wall of the circular ring piece 6 through epoxy resin. The bottom end of the cylindrical sleeve 10 extends out of the cylindrical sleeve vertical guide 9;

[0040] Vertical through holes are provided in the upper limit threaded post 1, the upper limit piece 3, the piezoelectric ceramic stack 4, the lower limit piece 5, and the cylindrical sleeve vertical guide 9. Each vertical through hole, the large spring 7, the small spring 8, and the circular ring piece 6 are coaxial with the upper through hole and the lower through hole.

[0041] The liquid storage cylinder needle 11 is sequentially inserted into the vertical through holes of the upper limit screw post, the upper limit piece 3, the piezoelectric ceramic, the lower limit piece 5, and the cylindrical sleeve 10. The end of the liquid storage cylinder needle is fixedly bonded to the inside of the bottom end of the cylindrical sleeve using strong glue. The bottom end of the liquid storage cylinder needle extends out of the cylindrical sleeve 10, and its top end extends out of the upper limit threaded post 1.

[0042] By rotating the upper limit threaded post downward, the large spring 7 is in a compressed state, so that the entire fixed part is tightly fitted together and a certain pre-tightening force is formed;

[0043] By rotating the cylindrical sleeve vertical guide 9 upward, the non-fixed part makes the small spring 8 in a compressed state, so that the entire non-fixed part is tightly fitted together and a certain pre-tightening force is formed.

[0044] Among them, the housing 2, the upper limit piece 3, the lower limit piece 5, the circular ring piece 6, the cylindrical sleeve 10, and the cylindrical sleeve vertical guide 9 are made of hard materials that are not prone to deformation. The liquid storage cylinder needle 11 is made of a material that does not damage the biological material ink, and a small hole is opened at the bottom end of the liquid storage cylinder needle 11 as the spray hole for spraying the biological material ink. The biological material ink is continuously injected through the top opening of the liquid storage cylinder needle 11.

[0045] When it is necessary to replace the liquid storage cylinder needle 11 with different nozzle diameters to eject biomaterial droplets of different diameters, simply rotate the cylindrical sleeve vertical guide 9 downward to remove the non-fixed part connected to the liquid storage cylinder needle 11 together. After replacing the liquid storage cylinder needle 11 with the required aperture diameter, rotate the cylindrical sleeve vertical guide 9 upward to install the non-fixed part together, which is convenient and fast.

[0046] The biomaterial droplets ejected by the present invention are generated by the water hammer effect between the biomaterial ink and the liquid storage cylinder needle. After the signal generator and the power amplifier are connected to the piezoelectric ceramic stack 4, inject the biomaterial ink into the liquid storage cylinder needle 11, and drive the piezoelectric ceramic stack 4 to expand and contract through the signal generator and the power amplifier, thereby driving the cylindrical sleeve 10 to move up and down quickly. Since the liquid storage cylinder needle is fixedly connected to the cylindrical sleeve 10, the liquid storage cylinder needle will also move up and down quickly following the cylindrical sleeve 10; among them, the large spring 7 and the small spring 8 remain in a compressed state after being assembled, providing a certain pre-tightening force for the fixed part and the non-fixed part of the device.

[0047] Greatly adjust the ejection liquid diameter of the biomaterial by replacing the liquid storage cylinder needle with different nozzle diameters; by adjusting the amplitude and frequency of the signal generator, change the amplitude of the up and down movement of the liquid storage cylinder needle and the time required for one cycle of the up and down movement, which is equivalent to changing the ejection force and movement speed of the liquid storage cylinder needle of the device, thereby adapting to biomaterial inks with different viscosities and realizing fine adjustment of the diameter of the biomaterial droplets ejected with the same nozzle diameter.

[0048] Example 1: Use a 50-micron nozzle to eject and print sodium alginate with a viscosity of 1%

[0049] Inject the biomaterial ink into the liquid storage cylinder needle 11 with a 50-micron nozzle to fill the entire inner cavity of the needle with the biomaterial. A bottom plate is placed at the lower end of the device, and the bottom end of the liquid storage cylinder needle 11 is about 1 mm away from the top surface of the bottom plate. Use the signal generator and the power amplifier to drive the device to make the liquid storage cylinder needle 11 move up and down quickly. In this example, the voltage amplitude is 20 V, and the single up and down movement time is within 500 microseconds. After continuous triggering for many times, uniform 70-micron biomaterial droplets are obtained, and the diameter difference is less than 4 microns.

[0050] Example 2: Use a 150-micron nozzle to eject and print sodium alginate with a viscosity of 1%

[0051] Inject the biomaterial ink into the liquid storage cylinder needle 11 with a 150-micron nozzle, filling the entire inner cavity of the needle with the biomaterial. Place a bottom plate at the lower end of the device, with the bottom end of the liquid storage cylinder needle 11 about 1 mm away from the top surface of the bottom plate. Use a signal generator and a power amplifier drive device to move the liquid storage cylinder needle 11 up and down rapidly. In this embodiment, the voltage amplitude is 30 V, and the single up-and-down movement time is within 200 microseconds. After continuous triggering for multiple times, uniform 210-micron biomaterial droplets are obtained, with a diameter difference of less than 10 microns.

[0052] Example 3: Prepare a bioink for jet printing

[0053] HEK293H cells for cell printing are routinely stored in DMEM supplemented with 10% FCS, 200 mM L-533 glutamine, and 100 U / ml penicillin / streptomycin at a temperature of 37 °C and 5% CO2. When preparing the bioink, the HEK293H cells are trypsinized with 0.05% trypsin-EDTA at 37 °C for 3 minutes and then collected by centrifugation at 1500 rpm for 5 minutes. The cell pellet is dissolved in Ca 2+ -ion-free DMEM, and the cell number is evaluated by counting. The final concentration of the bioink is 40 mM CaCl2, 40 IOWA Units / ml thrombin, and 6x10 6 cells / ml DMEM. The printing is carried out in air. The results show that the printing conditions are mild, the cell viability is high, or it is suitable for viscous liquids containing biological cells. The cell viability measured directly after printing is higher than 93%.

[0054] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A biological material droplet ejection device, characterized in that, It includes a fixed part and a non-fixed part that is conveniently detachable. The fixed part includes a housing, an upper limit threaded post, an upper limit piece, a piezoelectric ceramic stack, a lower limit piece, and a large spring. Coaxial upper and lower through holes are respectively provided at the top and bottom of the housing. The upper through hole is partially threadedly connected to the upper limit threaded post. The upper limit piece, the piezoelectric ceramic stack, the lower limit piece, and the large spring are sequentially arranged inside the housing from top to bottom; The non-fixed part includes a circular ring piece, a cylindrical sleeve, a small spring, a vertical guide for the cylindrical sleeve, and a liquid storage cylinder needle. The lower through hole is partially threadedly connected to the vertical guide of the cylindrical sleeve. The circular ring piece and the small spring are arranged inside the large spring; The cylindrical sleeve is sequentially passed through the vertical through holes of the circular ring piece, the small spring, and the vertical guide of the cylindrical sleeve, and is adhesively fixed to the inner wall of the circular ring piece. The bottom end of the cylindrical sleeve extends out of the vertical guide of the cylindrical sleeve; The liquid storage cylinder needle is sequentially passed through the vertical through holes of the upper limit spiral post, the upper limit piece, the piezoelectric ceramic, the lower limit piece, and the cylindrical sleeve, and the end of the liquid storage cylinder needle is adhesively fixed to the inside of the end of the cylindrical sleeve. The bottom end of the liquid storage cylinder needle extends out of the cylindrical sleeve, and its top end extends out of the upper limit threaded post; The housing, the upper limit piece, the lower limit piece, the circular ring piece, the cylindrical sleeve, and the vertical guide of the cylindrical sleeve are made of hard materials that are not easily deformed. The liquid storage cylinder needle is made of a material that does not damage the biological material ink. The biological material ink is continuously injected through the top opening of the liquid storage cylinder needle. Small holes are provided at the bottom end of the liquid storage cylinder needle as spray holes for spraying the biological material ink; When the signal generator and the power amplifier are connected to the piezoelectric ceramic stack, biological material ink is injected into the liquid storage cylinder needle. The piezoelectric ceramic stack is driven by the signal generator and the power amplifier to perform expansion and contraction actions, thereby driving the cylindrical sleeve to perform rapid up and down movements. The liquid storage cylinder needle will also perform rapid up and down movements following the cylindrical sleeve. Among them, the large spring and the small spring remain in a compressed state after being assembled, providing a certain pre-tightening force for the fixed part and the non-fixed part of the device; By replacing the liquid storage cylinder needles with different nozzle diameters, the ejection liquid diameter of the biological material is greatly adjusted. By adjusting the amplitude and frequency of the signal generator, the amplitude of the up and down movement of the liquid storage cylinder needle and the time required for one cycle of the up and down movement are changed, which is equivalent to changing the ejection force and movement speed of the liquid storage cylinder needle of the device, thereby adapting to biological material inks with different viscosities and realizing fine adjustment of the diameter of the biological material droplets ejected by the same nozzle diameter.

2. The bio-material droplet ejection device according to claim 1, characterized in that, The bottom surface of the large spring is adhered to the inner bottom surface of the housing, and the top of the large spring contacts the bottom surface of the lower limit piece.

3. The bio-material droplet ejection device according to claim 2, wherein First grooves are respectively provided on the top surface of the lower limit piece and the bottom surface of the upper limit piece, so that the top and bottom ends of the piezoelectric ceramic stack are respectively embedded in the two first grooves; An arc-shaped concave surface is provided on the top surface of the upper limit piece, and a hemispherical protrusion is provided at the bottom end of the upper limit threaded post. The hemispherical protrusion contacts the arc-shaped concave surface; A second groove is provided on the bottom surface of the lower limit piece, and a part of the circular ring piece is embedded in the second groove.

4. The bio-material droplet ejection device according to claim 3, wherein The vertical guide of the cylindrical sleeve is a four-layer circumferential step structure with diameters increasing sequentially from top to bottom. The first step structure at the top is located inside the small spring. One end of the small spring abuts against the circular ring plate, and the other end abuts against the horizontal tabletop of the second step structure. Part of the third step structure and the fourth step structure are threadedly connected to the lower through hole.

5. The bio-material droplet ejecting device according to claim 4, wherein Vertical through holes are provided in the upper limit threaded post, upper limit plate, piezoelectric ceramic stack, lower limit plate, and the vertical guide of the cylindrical sleeve. Each vertical through hole, large spring, small spring, and circular ring plate are coaxial with the upper through hole and the lower through hole. The two ends of the upper limit threaded post and the vertical guide of the cylindrical sleeve respectively extend out of the upper through hole and the lower through hole.

6. The bio-material droplet ejection device according to claim 5, wherein, By rotating the upper limit threaded post downward, the large spring is in a compressed state, so that the entire fixed part is closely fitted together and a certain pre-tightening force is formed. By rotating the vertical guide of the cylindrical sleeve upward, the non-fixed part makes the small spring in a compressed state, so that the entire non-fixed part is closely fitted together and a certain pre-tightening force is formed.

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