Near-field electrospinning temperature control spray head for solving local electric field gathering and printing method of near-field electrospinning temperature control spray head

Abstract

The invention discloses a near-field electrospinning temperature control spray head for solving local electric field gathering and a printing method thereof, belongs to the technical field of near-field electrospinning spray heads, and is suitable for a polymer solution or melt near-field electrospinning process. The spray head device comprises a nozzle module, a temperature control module, a feeding barrel and a shell, uniform electric field distribution is formed by optimizing the geometrical shape of a nozzle, jet flow stability is improved, the electric field gathering phenomenon is reduced, and then fiber arrangement precision and interlayer stacking consistency are improved; the temperature of the spinning material is accurately adjusted, and it is ensured that the material is subjected to spinning operation at the optimal temperature. The electrospinning nozzle module can be used as an electrospinning nozzle module to be combined with any three-dimensional motion platform, the requirement for manufacturing high-precision fiber structures is met, the electrospinning nozzle module is particularly suitable for preparing micro-nano fiber structures in biomedicine, flexible electronics and the like, and the problems that in the prior art, jet flow is unstable, and fiber accumulation is uneven are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of near-field electrospinning nozzles, and in particular relates to a near-field electrospinning temperature-controlled nozzle for solving the problem of local electric field concentration and a printing method thereof. Background Art

[0002] Near-field electrospinning (NFES) technology is an efficient preparation method for micro-nano fibers. It can accurately deposit fibers at the micro-nano scale and is widely used in piezoelectric sensors, biomedicine, flexible electronics, micro-optics and other fields. In recent years, with the rapid development of near-field electrospinning technology, its application fields have been continuously broadened. The near-field electrospinning process continuously delivers a certain concentration of polymer solution or melt to a conductive nozzle through air pressure or a syringe pump, and applies a sufficiently large voltage between the nozzle and the collector to form a jet, and finally generates a micro-nano fiber structure.

[0003] However, the local electric field distribution near the end of the existing near-field electrospinning nozzle has a clustering phenomenon, which leads to low precision of fiber deposition and difficulty in forming high-precision three-dimensional structures, preventing the further application of this technology in many fields. Therefore, improving the local electric field distribution near the end of the near-field electrospinning nozzle is expected to achieve more precise control of the jet, improve the precision of near-field electrospinning, achieve higher layers of fiber deposition, expand the application scenarios of this technology, and reduce the defect rate.

[0004] In addition, near-field electrospinning technology often uses polymer solutions or melts as spinning materials, and some materials need to be spun smoothly at a certain temperature, such as gelatin solutions or polycaprolactone melts. This puts higher requirements on the temperature control of the spinning materials during the spinning process. Summary of the invention

[0005] In view of this, in order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a near-field electrospinning temperature-controlled nozzle and a printing method thereof for solving the problem of local electric field concentration. The nozzle is suitable for the near-field electrospinning process of a solution or melt that requires a specific spinning material temperature. By forming a uniformly distributed electric field at the nozzle, the injection area is precisely controlled, the stability of the jet is improved, and the consistency of fiber stacking is improved, thereby achieving a higher number of layers of stacking.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solutions: a near-field electrospinning temperature-controlled nozzle for solving the problem of local electric field concentration, comprising a nozzle module, a temperature control module, a feed barrel and a shell; the nozzle module, the temperature control module and the feed barrel are all installed in the shell, the nozzle module is installed under the feed barrel, and the temperature control module is surrounded by it.

[0007] Furthermore, the nozzle module includes a nozzle fixing and heat preservation device and a replaceable nozzle, the nozzle fixing and heat preservation device is fixed on the heating end shell, and the replaceable nozzle is connected to the feed barrel.

[0008] Furthermore, the nozzle fixing and heat-insulating device is made of a non-conductive material, is filled with heat-insulating material, and is provided with a through hole for the replaceable nozzle to pass through.

[0009] Furthermore, the replaceable nozzle includes a replaceable nozzle inlet, a replaceable nozzle middle section and a replaceable nozzle end. The replaceable nozzle inlet is located at the upper part and is provided with a thread, which is connected to the feed barrel outlet through the thread; the replaceable nozzle middle section is cylindrical, with an outer diameter a of 310 to 2000 μm and an inner diameter b of 160 to 520 μm, and can print fibers of 0.5 to 100 μm; the replaceable nozzle end is hemispherical or ellipsoidal, and has a cylindrical spinning solution outlet. If it is a hemispherical nozzle end, the radius of the sphere is consistent with the outer diameter a of the nozzle; if it is a hemispherical nozzle end, its equatorial radius should be consistent with the outer diameter a of the nozzle, and the polar radius c should be 0.5 to 1.5 times the outer diameter of the nozzle.

[0010] Furthermore, the feed inlet of the replaceable nozzle is made of insulating material to prevent high voltage electricity from the end of the replaceable nozzle from being conducted to the feed barrel; the material used for the end of the replaceable nozzle is a metal material with good electrical conductivity.

[0011] Furthermore, the temperature control module includes a heat spreader, a heat sink, a heating fin, a cooling fin, a fan, a temperature sensor, an insulation board and a control chip. A fan is installed in front of the heat sink, and a cooling fin and a heat spreader are installed in sequence at the rear. The heat spreader is installed on one side of the feed barrel, and a heating fin is installed on the other side. An insulation board is installed outside the heating fin. The temperature sensor fits tightly against the heat spreader, and its signal line output signal line is connected to the control chip.

[0012] Furthermore, the heat sink has a plurality of heat sink fins for increasing the heat dissipation area, and the fan air outlet faces the heat sink fins of the heat sink.

[0013] Furthermore, a groove is left on the heat sink, the cooling fin is embedded in the groove, and the cooling fin installation side of the heat sink is in close contact with the heat spreader; a groove is left on the insulation board, and the heating fin installation side of the insulation board is in close contact with the heat spreader.

[0014] Furthermore, the wires of the fan, cooling plate, heating plate and temperature sensor are all connected to the control chip, and the control chip is installed on the housing bracket. The control chip realizes closed-loop control of the temperature and adjusts the spinning solution or melt temperature from 5 to 80°C.

[0015] A printing method using a near-field electrospinning temperature-controlled nozzle for solving local electric field concentration specifically comprises the following steps:

[0016] Step 1: Prepare the required spinning solution or melt material, place it in the feed barrel, and install the nozzle on the feed barrel;

[0017] Step 2: Install the feed cylinder in the housing and connect it to the Z axis of the three-dimensional moving platform through the housing bracket of the housing. The distance between the end of the replaceable nozzle and the collector can be adjusted by adjusting the height of the Z axis.

[0018] Step 3: Set the required temperature for spinning material printing through the control chip. If the temperature is too low, control the heating plate to heat the heat spreader, so that the spinning material reaches the required temperature. If the temperature is too high, control the cooling plate and the fan to operate. The cooling plate contacts the heat spreader to cool the side, and transfer the heat to the side in contact with the heat sink base. Finally, use the fan to blow air to dissipate the heat into the air.

[0019] Step 4: After the temperature is reached, high voltage electricity is connected to the end of the replaceable nozzle and both sides of the collector to form an electric field without local electric field concentration, and finally a stable spinning jet is generated. The three-dimensional mobile platform moves according to a predetermined trajectory to realize the printing of a three-dimensional structure;

[0020] Step 5: After printing is completed, stop the input of high voltage electricity and the air supply of the air pump, remove the hose, disassemble the feed barrel and clean it, and then place it in the drying oven for next use.

[0021] Compared with the prior art, the near-field electrospinning temperature-controlled nozzle and printing method thereof for solving the problem of local electric field concentration described in the present invention have the following beneficial effects:

[0022] 1. The nozzle device of the present invention can be installed as an independent nozzle module on any three-dimensional motion platform, and combined with the temperature control module to achieve precise control of the temperature of the spinning material during the spinning process, and ultimately achieve near-field electrospinning of polymer solutions or melts.

[0023] 2. The present invention uses a replaceable nozzle end with a unique shape. Compared with a flat-bottomed or conical nozzle, the ellipsoidal nozzle has a smooth curvature transition, which makes the electric field more evenly distributed on its surface, thereby effectively avoiding the local electric field concentration phenomenon. The uniform electric field distribution reduces jet fluctuations and improves the consistency of fiber arrangement and structure, which is crucial for generating an orderly arranged fiber grid and helps to improve the mechanical properties of the prepared fiber structure, thereby showing better functionality in fields such as tissue engineering.

[0024] 3. In addition, the curved surface structure at the end of the ellipsoidal nozzle can effectively guide the electric field lines to concentrate along the injection direction, reduce the lateral leakage of the electric field, and help concentrate the electric field to achieve the purpose of accurately controlling the injection area. Moreover, the concentration of the electric field can increase the field strength at the initial stage of injection, promote the stretching and acceleration of the spinning solution, and obtain finer and more uniform spinning fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a schematic structural diagram of a near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the replaceable nozzle of the present invention;

[0028] Figure 3 This is a schematic diagram of the internal structure of the present invention after removing the outer shell portion;

[0029] Figure 4 This is a schematic diagram of the connection between the heating end housing and the housing bracket of the present invention;

[0030] Among them, the figure markings are: 1-nozzle module, 2-temperature control module, 3-feeding barrel, 4-housing, 11-nozzle fixing and insulation device, 12-replaceable nozzle, 121-replaceable nozzle inlet, 122-replaceable nozzle middle section, 123-replaceable nozzle end, 21-fan, 22-heat sink, 221-heat sink base, 222-heat sink fins, 23-refrigeration fin, 24-heat spreader, 25-heating fin, 26-insulating plate, 261-groove, 262-rectangular channel, 27-temperature sensor, 28-control chip, 3-feeding barrel, 41-heating end housing, 411-feeding barrel interface, 42-fan housing, 421-air inlet, 422-air outlet, 43-housing bracket, 431-quick release structure, 432-integrated wire interface. Specific implementation methods

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0033] Reference Figure 1A near-field electrospinning temperature-controlled nozzle for solving the problem of local electric field concentration includes a nozzle module 1, a temperature control module 2, a feed barrel 3 and a shell 4; the nozzle module 1, the temperature control module 2 and the feed barrel 3 are all installed in the shell 4.

[0034] See also Figure 1 and Figure 2 The nozzle module 1 includes a nozzle fixing and heat preservation device 11 and a replaceable nozzle 12. The nozzle fixing and heat preservation device 11 is made of plastic or other non-conductive materials, filled with heat preservation materials, and provided with a through hole for the replaceable nozzle 12 to pass through. The nozzle fixing and heat preservation device 11 is fixed to the heating end housing 41 by screws, and the replaceable nozzle 12 is connected to the feed barrel 3 by threads, and the replaceable nozzle 12 has threads that can match the discharge port 31 of the feed barrel.

[0035] See also Figure 2 The replaceable nozzle inlet 121 is provided with threads, which can be connected to the feed barrel outlet 31 through the threads to achieve quick assembly and disassembly. The replaceable nozzle inlet 121 is made of insulating material such as plastic to prevent the high voltage electricity at the replaceable nozzle end 123 from being conducted to the feed barrel 3.

[0036] The replaceable nozzle middle section 122 is cylindrical, with an outer diameter a between 310 and 2000 μm and an inner diameter b between 160 and 520 μm. It can print fibers of 0.5 to 100 μm and has threads that can cooperate with the discharge port 31 of the feed barrel.

[0037] The replaceable nozzle end 123 is hemispherical or hemispherical, and has a cylindrical spinning solution outlet. If it is a hemispherical nozzle end, the radius of the sphere should be consistent with the nozzle outer diameter a; if it is a hemispherical nozzle end, its equatorial radius should be consistent with the nozzle outer diameter a, and the polar radius c should be 0.5 to 1.5 times the nozzle outer diameter.

[0038] The present invention uses a replaceable nozzle tip with a unique shape. Compared with a flat-bottom or conical nozzle, the ellipsoidal nozzle has a smooth curvature transition, which makes the electric field more evenly distributed on its surface, thereby effectively avoiding the local electric field concentration phenomenon. The uniform electric field distribution reduces jet fluctuations and improves the consistency of fiber arrangement and structure, which is crucial for generating an orderly arranged fiber grid and helps to improve the mechanical properties of the prepared fiber structure, thereby showing better functionality in fields such as tissue engineering.

[0039] The material used for the replaceable nozzle end 123 is a metal material with good electrical conductivity, and the available materials include but are not limited to stainless steel, copper, etc. A circular opening is left on the nozzle fixing and heat preservation device to connect the positive or negative electrode of the high voltage power supply.

[0040] See also Figure 3 The temperature control module 2 includes a heat spreader 24, a heat sink 22, a heating fin 25, a cooling fin 23, a fan 21, a temperature sensor 27, a heat shield 26 and a control chip 28. The feeding barrel 3 is surrounded by the heat spreader 24 in the temperature control module 2, and the heat spreader 24 is tightly connected to the cooling fin 23 and the heating fin 25 at the front and rear sides thereof.

[0041] A groove is provided on the heat dissipation base 221 on the heat sink 22 for mounting the cooling fin 23, and a rectangular channel with a width of 1 mm is connected to the groove for the wire of the cooling fin 23 to pass through. The heat sink 22 is fixed to the housing 4 by screws, and the side where the cooling fin 23 is mounted is in close contact with the heat spreader 24.

[0042] The heat insulation board 26 has a groove 261, in which the heating sheet 25 is inserted, and two 1 mm wide rectangular channels are left for the wires of the heating sheet 25 to pass through. The heat insulation board 26 is fixed to the heating end housing 41 by screw connection, and the side where the heating sheet 25 is installed is in close contact with the heat spreader 24.

[0043] The heat sink 22 has a plurality of heat sink fins 222 for increasing the heat dissipation area, the fan 21 air outlet faces the heat sink fins 222 of the heat sink 22, and the housing air inlet 421 is meshed. The cooling end housing 42 on both sides of the heat sink fins 222 is provided with air outlets to facilitate the outflow of hot air.

[0044] The fan 21 is mounted on the cooling end housing 42 by screw connection, with its air inlet 211 facing the housing air inlet, and its air outlet facing the heat sink fins 222 on the heat sink 22 .

[0045] A cylindrical through hole is provided in the middle of the heat plate 24 for installing the feed cylinder 3. The feed cylinder 3 can be taken out from the top of the housing 4 to achieve the replacement of the spinning material, and a circular gas path interface is provided above the feed cylinder 3 to adjust the feeding speed of the spinning material by controlling the gas pressure.

[0046] The temperature sensor 27 is closely attached to the heat spreader 24, and its signal line output signal line is connected to the control chip 28. The control chip 28 is installed in the housing bracket 43 and fixed by screws.

[0047] The cooling plate 23 is in direct contact with the heat spreader 24 to realize the cooling function. The heat spreader 24 is made of a material with good thermal conductivity. A through hole is provided in the middle of the heat spreader 24, and the feed barrel 3 can be installed to make the overall temperature distribution of the feed barrel 3 more uniform. The other side of the heat spreader 24 is in close contact with the heating plate 25.

[0048] The wires of the fan 21, cooling plate 23, heating plate 25 and temperature sensor 27 are all connected to the control chip 28, and the control chip 28 is installed on the housing bracket 43. The control chip 28 realizes closed-loop control of the temperature, and can adjust the spinning solution or melt temperature from 5 to 80°C.

[0049] See also Figure 1 , Figure 3 The feeding cylinder 3 is provided with a cylindrical interface, which can be connected to an air pump through a hose to achieve control of the near-field electrospinning feeding speed.

[0050] See also Figure 1 and Figure 4 The housing 4 is divided into three parts: a heating end housing 41, a fan end housing 42 and a housing bracket 43. The heating end housing 41 is connected to the fan housing 42 by spring buckles and screws. The housing bracket 43 is connected to the heating end housing 41 by a quick-release structure 431. The wire is connected to the control chip 28 in the housing bracket 43 through an integrated interface 432.

[0051] The overall material of the housing 4 is engineering plastics, etc., which can not only prevent the conduction of high voltage electricity in near-field electrospinning, but also can be made by 3D printing, which is simple and convenient. An interface 411 for installing and replacing the feed barrel 3 is provided above the heating end housing 41, and a quick-release structure that can be connected to the housing bracket 43 is provided on the rear side. The fan end housing 42 is provided with an air inlet 421 and an air outlet 422.

[0052] The printing method of a near-field electrospinning temperature-controlled nozzle for solving the problem of local electric field concentration comprises the following steps:

[0053] 1) Prepare the required spinning solution or melt material, such as gelatin solution or polycaprolactone melt, and place it in the feed barrel 3, and install the nozzle 12 of the present invention on the feed barrel 3.

[0054] 2) The feed barrel 3 is installed in the housing 4 and connected to the Z axis of the three-dimensional moving platform through the housing bracket 43 of the housing 4. The distance between the nozzle end and the collector can be adjusted by adjusting the height of the Z axis.

[0055] 3) The required temperature for spinning material printing is set by controlling chip 28. If the temperature is too low, the heating plate 25 is controlled to heat the heat spreader, so that the spinning material reaches the required temperature. If the temperature is too high, the cooling plate 23 and the fan 21 are controlled to operate. The cooling plate 23 cools the contact side with the heat spreader 24, and conducts the heat to the contact side with the heat sink base 222. Finally, the fan 21 is used to blow air so that the heat is dissipated into the air.

[0056] 4) After the temperature is reached, a certain amount of high voltage electricity is connected to the nozzle end 123 and both sides of the collector to form an electric field without local electric field concentration, and finally a stable spinning jet is generated. The three-dimensional mobile platform moves according to a predetermined trajectory to realize the printing of a three-dimensional structure.

[0057] 5) After printing is completed, stop the input of high voltage electricity and the air supply of the air pump, remove the hose, disassemble the feed cylinder 3 and clean it, and then place it in the drying oven for next use.

[0058] Embodiment 1:

[0059] Near-field electrospinning is performed using polycaprolactone melt. First, a certain amount of polycaprolactone solid is placed in the feed barrel 3, and the feed barrel 3 is installed in the housing 4. To ensure that the polycaprolactone is always kept in a molten state, the temperature of the feed barrel 3 is set to 75°C. The heating plate 25, the cooling plate 23 and the fan 21 are powered by the control chip 28 to achieve precise temperature control. The operating voltage is set to 0.5-3kV, the distance between the nozzle and the collector is 0.5-3mm, the air pressure is 1-3MPa, and the collector movement speed is 10-50mm / s. A replaceable nozzle 12 with a hemispherical nozzle end is installed for near-field electrospinning, which ultimately reduces the fluctuation of the spinning jet. Combined with the movement of the collector in a certain direction, precise control of the jet area is achieved.

[0060] Embodiment 2:

[0061] Using gelatin solution for near-field electrospinning, first use water as solvent and gelatin as solute to prepare a gelatin solution with a concentration range of 10 to 30wt%. When preparing the gelatin solution, it is necessary to heat the water to 40 to 50°C, then slowly add the gelatin powder and stir evenly until it is completely dissolved. Gelatin is easy to solidify at a lower temperature, and continuous heating is required to maintain the temperature to prevent the solution from solidifying while ensuring the uniformity of the solution. After that, the prepared gelatin solution is placed in the feed barrel, and the temperature control module 2 is used to accurately control the temperature of the feed barrel 3 to 40°C. Set the various process parameters, set the motion trajectory of the mobile platform, use the replaceable nozzle 12 described in the present invention, and perform near-field electrospinning, and finally obtain a spinning fiber with a finer diameter and more uniform arrangement, and the arrangement is more neat. When performing multi-layer printing, the consistency of the multi-layer fiber stacking is higher, and printing with a higher number of layers can be achieved.

[0062] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration, characterized in that: The invention comprises a nozzle module (1), a temperature control module (2), a feed barrel (3) and a shell (4); the nozzle module (1), the temperature control module (2) and the feed barrel (3) are all installed in the shell (4); the nozzle module (1) is installed under the feed barrel (3) and is surrounded by the temperature control module (2).

2. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 1, characterized in that: The nozzle module (1) comprises a nozzle fixing and heat preservation device (11) and a replaceable nozzle (12); the nozzle fixing and heat preservation device (11) is fixed on the heating end shell (41); and the replaceable nozzle (12) is connected to the feed barrel (3).

3. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 2, characterized in that: The nozzle fixing and heat-insulating device (11) is made of a non-conductive material, is filled with heat-insulating material, and is provided with a through hole for the replaceable nozzle (12) to pass through.

4. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 2, characterized in that: The replaceable nozzle (12) comprises a replaceable nozzle feed inlet (121), a replaceable nozzle middle section (122) and a replaceable nozzle end (123); the replaceable nozzle feed inlet (121) is located at the upper part and is provided with a thread, and is connected to the feed barrel discharge port (31) through the thread; the replaceable nozzle middle section (122) is cylindrical, and its outer diameter a is 310 to 2000 μm, and its inner diameter b is 160 to 520 μm, and it can print fibers of 0.5 to 100 μm; the replaceable nozzle end (123) is hemispherical or ellipsoidal, and has a cylindrical spinning solution outlet. If it is a hemispherical nozzle end, the radius of the sphere is consistent with the nozzle outer diameter a; if it is a hemispherical nozzle end, its equatorial radius should be consistent with the nozzle outer diameter a, and the polar radius c should be 0.5 to 1.5 times the nozzle outer diameter.

5. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 4, characterized in that: The replaceable nozzle inlet (121) is made of insulating material to prevent high voltage electricity from the replaceable nozzle end (123) from being transmitted to the feed barrel (3); the replaceable nozzle end (123) is made of a metal material with good electrical conductivity.

6. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 1, characterized in that: The temperature control module (2) comprises a heat spreader (24), a heat sink (22), a heating fin (25), a cooling fin (23), a fan (21), a temperature sensor (27), a heat insulation board (26) and a control chip (28); the fan (21) is installed in front of the heat sink (22), and the cooling fin (23) and the heat spreader (24) are installed in sequence at the rear; the heat spreader (24) is installed on one side of the feed barrel (3), and the heating fin (25) is installed on the other side; a heat insulation board (26) is installed outside the heating fin (25); the temperature sensor (27) is tightly fitted with the heat spreader (24), and its signal line output signal line is connected to the control chip (28).

7. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 6, characterized in that: The heat sink (22) has a plurality of heat sink fins (222) for increasing the heat dissipation area, and the air outlet of the fan (21) faces the heat sink fins (222) of the heat sink (22).

8. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 6, characterized in that: A groove is left on the heat sink (22), and the cooling fin (23) is embedded in the groove. The side of the heat sink (22) on which the cooling fin (23) is installed is in close contact with the heat spreader (24); a groove is left on the heat insulation board (26), and the side of the heat insulation board (26) on which the heating fin (25) is installed is in close contact with the heat spreader (24).

9. The near-field electrospinning temperature control nozzle for solving the problem of local electric field concentration according to claim 6, characterized in that: The wires of the fan (21), the cooling plate (23), the heating plate (25) and the temperature sensor (27) are all connected to the control chip (28). The control chip (28) is mounted on the housing bracket (43). The closed-loop control of the temperature is achieved through the control chip (28), so that the temperature of the spinning solution or melt can be adjusted from 5 to 80°C.

10. A printing method using the near-field electrospinning temperature-controlled nozzle for solving the problem of local electric field concentration according to any one of claims 1 to 9, characterized in that: The specific steps include: Step 1: Prepare the required spinning solution or melt material, place it in a feed barrel (3), and install the nozzle (12) on the feed barrel (3); Step 2: Install the feed barrel (3) in the housing (4) and connect it to the Z axis of the three-dimensional moving platform through the housing bracket (43) of the housing (4). By adjusting the height of the Z axis, the distance between the replaceable nozzle end (123) and the collector can be adjusted; Step 3: The temperature required for printing the spinning material is set by the control chip (28). If the temperature is too low, the heating plate (25) is controlled to heat the heat spreader (24), so that the spinning material reaches the required temperature. If the temperature is too high, the cooling plate (23) and the fan (21) are controlled to operate. The contact side of the cooling plate (23) and the heat spreader (24) is cooled, and the heat is transferred to the contact side of the heat sink base 222. Finally, the fan (21) is used to blow air so that the heat is dissipated into the air. Step 4: After the temperature is reached, high voltage electricity is connected to the end of the replaceable nozzle (123) and both sides of the collector to form an electric field without local electric field concentration, and finally a stable spinning jet is generated, and the three-dimensional mobile platform moves according to a predetermined trajectory to realize the printing of a three-dimensional structure; Step 5: After printing is completed, stop the input of high voltage electricity and the air supply of the air pump, remove the hose, disassemble the feed cylinder (3) and clean it, and then place it in a drying oven for next use.

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