Patent Publication Number: US-2021178678-A1

Title: Bioprinting platform, method for using the same and 3d bioprinter

Description:
The present application is a continuation application of U.S. patent application No. U.S. 15/964,214, filed Apr. 27, 2018, which claims priority to Chinese Patent Application No. CN 201810048700.6, filed Jan. 18, 2018, both of which are herein incorporated by reference in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     The present application relates to the technical field of 3D bioprinting, and especially relates to a bioprinting platform, a method for using the same and a 3D bioprinter. 
     BACKGROUND 
     In the prior art, common artificial blood vessels are made from polymer fibers (e.g., nylon, dacron), silk, or ePTFE. In the case of vascular transplantation, intact artificial blood vessels may be used to replace lesioned or damaged blood vessels. Although the replacement of lesioned or damaged blood vessels with such artificial blood vessels has attained great clinical achievement, it is still confronted with difficult problems, including recurrence of thrombus and appearance of restenosis of a lumen after transplantation for a long time. The root of these problems lies in the lack of a complete endothelial cell layer on the inner surface of such artificial blood vessels. 
     In addition, since the artificial blood vessels can hardly deform in a radial direction, the prior art cannot externally compress the artificial blood vessels so that the bio-block is completely evenly, intactly, and flatly attached on the inner wall of the artificial blood vessels. 
     SUMMARY 
     In order to overcome the above technical defects, the technical problem solved by the present application is to provide a bioprinting platform, a method for using the same and a 3D bioprinter, aiming at improving the biological reliability of the lumen tissue. 
     In order to solve the above technical problem, the present application provides a bioprinting platform includes a platform base, a rotary part on the platform base and a butt-jointed part movable relative to the rotary part, the rotary part includes a rotary rod for placing the bio-block and the medical adhesive to form a biological construct, and the butt-jointed part includes a hollow rod having an outer wall for placing the lumen tissue. 
     Further, the outer wall of the rotary rod is covered with an elastic film. 
     Further, an interior of the rotary rod is hollow, and the outer wall of the rotary rod is provided with a vent communicating with the interior, for exhausting air inside the rotary rod to balloon the elastic film. 
     Further, the interior of the rotary rod is provided with a heating unit. 
     Further, the heating unit includes a heating section and a spacing section that are spacedly arranged, wherein the heating section has a surface wound with a resistance wire, and the heating section has a diameter that is less than that of the spacing section. 
     Further, a temperature detecting unit is provided at one end of the heating unit proximate to the butt-jointed part, for detecting the temperature of the heating unit. 
     Further, the bioprinting platform includes a gripping mechanism for gripping the lumen tissue to make it disengaged from the hollow rod and socketed to the biological construct. 
     Further, the gripping mechanism includes a first gripping block and a second gripping block which are movable relatively. 
     Further, the gripping mechanism includes a retaining unit for acting on a tail end of the lumen tissue so that it is disengaged from the hollow rod. 
     Further, the retaining unit is cooperatively provided with a retaining ring acting on the tail end of the lumen tissue. 
     Further, the gripping mechanism includes a limiting block provided at the bottom of the first gripping block and the second gripping block, for limiting relative movement of the first gripping block and the second gripping block, so that the first gripping block and the second gripping block are both tangent to the outer wall of the lumen tissue. 
     Further, the gripping mechanism includes a support platform provided at the bottom of the first gripping block and the second gripping block, for supporting the lumen tissue. 
     Further, the platform base includes an optical probe movable inside the rotary rod, for detecting the flatness of the inner wall of the biological construct, wherein the rotary rod is made of a transparent material. 
     Further, the optical probe is movably disposed within the rotary rod or the hollow rod. 
     Further, the optical probe is fixedly disposed within the hollow rod. 
     Further, platform base further includes a reservoir provided below the rotary rod, for bearing a bioprinting construct disengaged and falling from the gripping mechanism. 
     The present application further provides a 3D bioprinter, which includes the aforementioned platform base. 
     The present invention further correspondingly provides a method of printing lumen tissue construct using the aforementioned platform base, which includes a mantling step: cladding a layer of elastic film on the outer wall of the rotary rod before printing the biological construct. 
     Further, the method further includes a ballooning step: ventilating into the elastic film to balloon the elastic film so that the biological construct is attached to the inner wall of the lumen tissue, after the lumen tissue is sleeved outside the biological construct. 
     Therefore, based on the aforementioned technical solution, the bioprinting platform of the present application cooperates with a nozzle assembly to print the biological construct on the inner surface of the lumen tissue by the bioprinting platform, thus avoid such problems as recurrence of thrombus and restenosis of a lumen after the lumen tissue has been transplanted for a long time, thereby improving the biological reliability of the lumen tissue. The method of printing lumen tissue construct and the 3D bioprinter provided by the present application also correspondingly have the advantageous technical effects described above. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
       The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application as well as the descriptions thereof, which are merely used for explaining the present application, and do not constitute improper definitions on the present application. In the drawings: 
         FIG. 1  illustrates an overall structure of the device for printing lumen tissue construct according to an embodiment of the present application; 
         FIG. 2  illustrates an overall structure of a sprayhead assembly of the device according to an embodiment of the present application; 
         FIG. 3  illustrates an interior structure of a sprayhead assembly of the device according to an embodiment of the present application; 
         FIG. 4  illustrates a sectional structure of a screw pump of the device according to an embodiment of the present application; 
         FIG. 5  illustrates a sectional structure of a bio-block nozzle of the device according to an embodiment of the present application; 
         FIG. 6  is a locally enlarged schematic view of a circled portion in  FIG. 5 ; 
         FIG. 7  illustrates an overall structure of a bioprinting platform of the device according to an embodiment of the present application; 
         FIG. 8  illustrates a local structure of a bioprinting platform of the device according to an embodiment of the present application; 
         FIG. 9  illustrates the structure of a rotary rod of the device according to an embodiment of the present application; 
         FIG. 10  illustrates the structure of a heating unit of the device according to an embodiment of the present application; 
         FIG. 11  illustrates the structure of a heating unit disposed inside the rotary rod of the device according to an embodiment of the present application; 
         FIG. 12  illustrates an interior structure of a rotary part of the device according to an embodiment of the present application; 
         FIG. 13  illustrates the structure of a first embodiment of a gripping mechanism of the device according to the present application; 
         FIG. 14  illustrates the structure of a first embodiment of a gripping mechanism of the device according to the present application in another angle of view; 
         FIG. 15  illustrates the structure of a second embodiment of a gripping mechanism of the device according to the present application; 
         FIG. 16  illustrates the structure of a second embodiment of a gripping mechanism when gripping the lumen tissue of the device according to the present application. 
     
    
    
     Various reference signs respectively represent: 
       1 . sprayhead assembly;  11 . medical adhesive sprayhead;  111 . medical adhesive container;  112 . medical adhesive nozzle;  113 . medical adhesive piston;  12 . bio-block sprayhead;  121 . screw pump;  1211 . spiral stator;  1212 . spiral rotor;  1213 . inlet connecting piece;  122 . bio-block nozzle;  123 . thermal insulation shell;  124 . bio-block piston;  125 . bio-block container;  126 . semiconductor cooling plate;  127 . connecting tube;  128 . bio-block inlet;  129 . thermal insulation sleeve;  2 . bioprinting platform;  21 . rotary part;  211 . rotary rod;  212 . heating unit;  2121 . heating section;  2122 . connecting groove;  2123 . spacing section;  213 . temperature detecting unit;  214 . sealing ring;  22 . gripping mechanism;  221 ,  221 ′. first gripping block;  222 ,  222 ′. second gripping block;  223 ,  223 ′. retaining unit;  224 . support platform;  225 . limiting block;  23 . butt-jointed part;  231 . hollow rod;  232 . displacement mechanism. 
     DETAILED DESCRIPTION 
     Next, the technical solution of the present application is further described in detail by means of the drawings and embodiments. 
     The specific embodiments of the present application are further described in order to facilitate understanding of the concept of the present application, the technical problem to be solved, the technical features constituting the technical solution and the technical effect produced therefrom. It is necessary to explain that, the explanations for such embodiments do not constitute definitions on the present application. In addition, the technical features involved in the embodiments of the present application described below may be combined with each other as long as they do not constitute a conflict therebetween. 
     In an illustrative embodiment of the device for printing lumen tissue construct of the present application, as shown in  FIG. 1 , the device comprises a sprayhead assembly  1  and a bioprinting platform  2 , the sprayhead assembly  1  prints a biological construct on an inner surface of a lumen tissue by the bioprinting platform  2 . 
     In the illustrative embodiment, the device provides the sprayhead assembly  1  and the bioprinting platform  2 , and the sprayhead assembly  1  prints the biological construct on the inner surface of the lumen tissue by the bioprinting platform  2 , thus avoid such problems as recurrence of thrombus and restenosis of a lumen after the lumen tissue has been transplanted for a long time, thereby improving the biological reliability of the lumen tissue. Among them, the lumen tissue is especially an artificial blood vessel, such as a commercial blood vessel of Gore, and the occurrence of thrombus after an artificial blood vessel has been transplanted for a long time may be avoided by printing the biological construct on the inner surface of the artificial blood vessel. 
     In an improved embodiment of the device for printing lumen tissue construct of the present application, as shown in  FIGS. 2 and 3 , the sprayhead assembly  1  includes a medical adhesive sprayhead  11 , which consist of a medical adhesive container  111  and a medical adhesive nozzle  112 , wherein the medical adhesive container  111  is used for containing a medical adhesive, the medical adhesive nozzle  112  is directly connected with the medical adhesive container  111 , a top of the medical adhesive container  111  is connected with an air pump through an air path, in which a vacuum generator is provided for generating a negative pressure for the medical adhesive container  111  in a non-printing state. Since the medical adhesive presents an excellent fluidity, in a non-printing state, the medical adhesive may also drip slowly due to the effect of gravity. Thus, a vacuum generator is added in the air path, where certain negative pressure is present in a non-printing state, and the negative pressure counteracts with the gravity so that the medical adhesive no longer drips freely. Specifically or further, as shown in  FIG. 3 , a top of the medical adhesive container  111  is provided with a medical adhesive piston  113  which is connected with the air pump through an air path. The air pump is pressurized to extrude the medical adhesive from an ink bladder, and the vacuum generator is located between the air pump and the medical adhesive piston  113 . 
     In an improved embodiment of the device for printing lumen tissue construct of the present application, as shown in  FIGS. 2 to 4 , the sprayhead assembly  1  includes a bio-block sprayhead  12  which consist of a screw pump  121 , a bio-block nozzle  122 , and a bio-block container  125 . The bio-block container  125  is used for containing bio-ink (bio-block). The outlet at the bottom of the bio-block container  125  communicates with the bio-block inlet  128  of the screw pump  121  through the connecting tube  127  and the inlet connecting piece  1213 . The top of the bio-block container  125  is provided with a bio-block piston  124  which is connected with the air pump through an air path. The air pump is pressurized to extrude the bio-ink from the bio-block container  125  into the screw pump  121 . The screw pump  121  includes a spiral stator  1211  and a spiral rotor  1212  for extruding a bio-block entering the screw pump  121  to the bio-block nozzle  122 , wherein the spiral stator  1211  is made of a silicone material. 
     Due to the physical properties of the bio-block, when it is very small at the outlet of the bio-block container  125 , the bio-block cannot be extruded and may form an accumulation at the outlet. Even if the pressure is increased, the bio-block cannot be extruded even if it is crushed. Likewise, even if such means as angular design is performed at the outlet of the bio-block container  125 , the bio-block still cannot be extruded. However, the printing requirement defines that the bio-block cannot be extruded in large quantities, and only a few amount can be extruded at a time. Therefore, the bio-blocks can only be conveyed from the bio-block container  125  to the screw pump  121  and extruded by the screw pump  121 . As the outlet of the screw pump  121  itself is very large, and the amount of the bio-blocks extruded each time is still greater than the operational requirement, a bio-block nozzle  122  is provided at the outlet of the screw pump  121 . 
     As shown in  FIG. 4 , the spiral stator  1211  cannot rotate, the spiral rotor  1212  rotates relative to the spiral stator  1211 , and the groove on the spiral rotor  1212  forms a chamber in which only a few amount of bio-blocks can be loaded within each chamber. The bio-blocks are conveyed out to the bio-block nozzle  122  along with rotation of the spiral rotor  1212 . Due to the physical properties of the current bio-ink materials, the printing needs to be performed at a low temperature (4° C.). The screw stators of the existing screw pumps are made of a rubber material, which may rapidly age at a low temperature, so that black powder appears during the printing. The present application makes a modification by making the spiral stator  1211  of silicone, thus avoiding the appearance of black powder during the printing. 
     In order to avoid the phenomenon of “hanging droplets” (Due to high viscosity of the bio-ink, the bio-block after being extruded may not drip directly, but hang at the nozzle outlet. When a following bio-block is extruded, a previous bio-block that does not drip is piled up with the following to become a large droplet hanging at the outlet of the nozzle which may drip when the gravity of such large droplet is greater than the frictional force) appearing at a front end outlet (a circled portion in  FIG. 5 ) of the bio-block nozzle  122  when printing the bio-block. In an improved embodiment, on one hand, as shown in  FIGS. 5 and 6 , a printing outlet end of the bio-block nozzle  122  has a chamfer, which has a chamfered surface defining an included angle of 10° to 30° with a center line of a printing outlet of the bio-block nozzle  122 . Even further, the included angle is 20°, such design can effectively avoid the phenomenon of “hanging droplets”. On the other end, an outer surface at the printing outlet end of the bio-block nozzle  122  has a roughness Ra≤0.4. The outer surface of the bio-block nozzle  122  may be plated/polished so as to increase the surface smoothness, and such design can be able to better avoid the phenomenon of “hanging droplets”. 
     Since the currently used bio-ink may tend to coagulate in the case of a temperature greater than 4° C., it is very necessary to maintain the bio-block sprayhead at an ambient temperature of 4° C. In some improved embodiments, as shown in  FIG. 3 , the bio-block sprayhead  12  also includes a semiconductor cooling plate  126  located behind the screw pump  121  and the bio-block container  125 , which can cool the bio-block sprayhead  12  by heat transfer. Further, as shown in  FIG. 3 , the bio-block nozzle  122  is externally provided with a thermal insulation sleeve  129 . There is certain gap between the thermal insulation sleeve  129  and an exterior of the bio-block nozzle  122 , in which an air thermal insulation layer can be formed. Further, as shown in  FIG. 2 , the screw pump  121  and the bio-block container  125  are externally sleeved with a thermal insulation shell  123  including a box cover and thermal insulation cotton covered on the outer surface of the box cover. The thermal insulation cotton can further improve the thermal insulation effect, and reduce the heat exchange between the sprayhead and the environment. The box cover is provided with a transparent window for observing the containing condition of the bio-ink in the bio-block container  125 . 
     In some improved embodiments, the device further comprises a displacement assembly for moving the sprayhead assembly  1 , and an entirety of the sprayhead assembly  1  (the bio-block sprayhead  12  and the medical adhesive sprayhead  11 ) may be displaced in a vertical direction and a horizontal direction, and the medical adhesive sprayhead  11  may be lifted independently. When the sprayhead assembly  1  is in the initial state, the horizontal position at the outlet of the bio-block sprayhead  12  is below the horizontal position at the outlet of the medical adhesive sprayhead  11 . After the displacement assembly lowers the sprayhead assembly  1  to certain height during the printing, the bio-block sprayhead  12  extrudes the bio-block, and wholly ascends a segment after the printing of the lumen tissue is accomplished, then the medical adhesive sprayhead  11  descends independently, to print the medical adhesive. 
     In an improved embodiment of the device for printing lumen tissue construct of the present application, as shown in  FIGS. 7 and 8 , the bioprinting platform  2  includes a platform base, a rotary part  21  and a butt-jointed part  23  movable relative to the rotary part  21 , wherein the rotary part  21  includes a rotary rod  211  for placing the bio-block and the medical adhesive to form a biological construct, and the butt-jointed part  23  includes a displacement mechanism  232  and a hollow rod  231  having an outer wall for placing the lumen tissue and having an inner cavity for containing the rotary rod  211  with the biological construct. 
     After the biological construct is manufactured on the rotary rod  211 , the hollow rod  231  is displaced toward a direction of the rotary part  21  driven by the displacement mechanism  232 . The rotary rod  211  together with the biological construct enter the inner cavity of the hollow rod  231 , and the lumen tissue sleeved outside the hollow rod  231  is displaced to the outside of the biological construct along with the hollow rod  231 . Further, the surface of the hollow rod  231  is plated with a Teflon layer, which is capable of avoiding that the medical adhesive contacts and reacts with the metal surface. The hollow rod  231  is further displaced in an opposite direction driven by the displacement mechanism  232 , and the lumen tissue is removed from the hollow rod  231 , and then sleeved on the outer surface of the biological construct, so that the assembly is accomplished to obtain an artificial tissue precursor. Further, the outer wall of the rotary rod  211  is covered with an elastic film. During the printing of the biological construct, the elastic film presents a natural state and clads on the surface of the rotary rod  211 . The bio-block makes up a biological construct on the surface of the elastic film, thus favorable for removing the biological construct. Further, as shown in  FIG. 9 , an interior of the rotary rod  211  is hollow, and the outer wall of the rotary rod  211  is provided with a vent communicating with the interior, for exhausting air inside the rotary rod  211  to balloon the elastic film. During the assembly of the biological construct and the lumen tissue, the rotary rod  211  is internally ventilated so that air expands outwards from the air outlet to balloon the elastic film (conceivably like a balloon is blown up). The biological construct on the surface of the elastic film is displaced outwards along with the expansion of the elastic film, and finally in contact with the inner wall of the lumen tissue and then adhered onto the inner wall of the lumen tissue, to obtain an artificial tissue precursor. It is demonstrated in practice that, the embodiment is easy to operate and implement, and presents a high implementability. Specifically or further, as shown in  FIG. 12 , a sealing ring  214  is provided inside the rotary part  21 . The rotary rod  211  is detachably connected with the sealing ring  214 , and the sealing ring  214  is used for sealing the inner cavity of the rotary rod  211 , so that the process of balloon the elastic film is more controllable. 
     As an improvement to the above embodiment, as shown in  FIGS. 10 and 11 , the interior of the rotary rod  211  is further provided with a heating unit  212 . The heating unit  212  can accelerate the coagulation rate of the bio-ink and shorten the preparation time of the bio-construct. The heating unit  212  needs to maintain the surface temperature of the rotary rod at 37° C.-38° C. Further, as shown in  FIG. 11 , a temperature detecting unit  213  is provided at one end of the heating unit  212  proximate to the butt-jointed part  23 , for detecting the temperature of the heating unit  212 , so as to maintain the surface temperature of the rotary rod in real time. 
     In a specific or improved embodiment, as shown in  FIGS. 10 and 11 , the heating unit  212  includes a heating section  2121  and a spacing section  2123  that are spacedly arranged, wherein a connecting groove  2122  is opened in the surface of the spacing section  2123 , and the surface of the heating section  2121  is wounded with a resistance wire, the surface of the spacing section  2123  is not wounded with a resistance wire, the resistance wire between adjacent heating sections  2121  passes through the connecting groove  2122 , and the diameter of the heating section  2121  is less than that of the spacing section  2123 . The heating unit  212  is in clearance fit with the rotary rod  211 , and the outer wall of the spacing section  2123  is in contact with the inner wall of the rotary rod  211 . The purpose of providing the spacing section is to protect the resistance wire when the heating unit  212  is inserted into the rotary rod  211 , so as to avoid that the resistance wire is damaged during the assembly. 
     As to how to remove the lumen tissue from the hollow rod  231 , in an improved embodiment, as shown in  FIG. 7 , the bioprinting platform  2  further includes a gripping mechanism  22  for gripping the lumen tissue to make it disengaged from the hollow rod  231  and socketed to the biological construct when the hollow rod  231  is displaced in an opposite direction. The embodiment is easy to implement and has a high reliability. 
     Specifically or further, as shown in  FIGS. 13-16 , the gripping mechanism  22  includes a first gripping block  221 ,  221 ′ and a second gripping block  222 ,  222 ′ which are movable relatively. As shown in  FIGS. 13 and 14 , the relative movement of the first gripping block  221  and the second gripping block  222  may be preferably realized by providing a guide rail. As shown in  FIGS. 15 and 16 , the relative movement of the first gripping block  221 ′ and the second gripping block  222 ′ may also be preferably realized by providing a leadscrew nut mechanism. Even further, as shown in  FIG. 14 , the gripping mechanism  22  further includes a limiting block  225  provided at the bottom of the first gripping block  221  and the second gripping block  222 , for limiting relative movement of the first gripping block  221  and the second gripping block  222 , so that the first gripping block  221  and the second gripping block  222  are both tangent to the outer wall of the lumen tissue, and it is possible to produce certain limiting effect for the lumen tissue during assembling the artificial tissue precursor. 
     In order to ensure that the lumen tissue is removed from the hollow rod  231  as much as possible, in one further embodiment, as shown in  FIGS. 13 to 16 , the gripping mechanism  22  further includes a retaining unit  223 ,  223 ′ for acting on a tail end of the lumen tissue so that it is disengaged from the hollow rod  231  to prevent the lumen tissue from following the hollow rod  231  when the hollow rod  231  is displaced in an opposite direction. The retaining units  223 ,  223 ′ may be disposed at a tail end of the first gripping blocks  221 ,  221 ′ and/or the second gripping blocks  222 ,  222 ′, and may also be directly disposed on the gripping mechanism independent of the first gripping block and the second gripping block. Even further, the retaining unit  223  is cooperatively provided with a retaining ring acting on the tail end of the lumen tissue, so that the lumen tissue is more easily disengaged from the hollow rod  231 . Still further, as shown in  FIG. 14 , the gripping mechanism  22  further includes a support platform  224  provided at the bottom of the first gripping block  221  and the second gripping block  222 , for supporting the lumen tissue. In the process of the lumen tissue socketing the biological construct, the support platform  224  is exactly tangent to the outer wall at the bottom of the lumen tissue, for providing an upward force for the lumen tissue and avoiding the sinking of the lumen tissue. 
     In an improved embodiment of device for printing the lumen tissue construct of the present application, the device further comprises a reservoir provided below the rotary rod  211 , for bearing a bioprinting construct disengaged and falling from the gripping mechanism  22 . After the printing assembly is completed, the bioprinting construct is gripped by the gripping mechanism  22 , and an entirety of the rotary rod  211  is withdrawn towards an opposite direction. The bioprinting construct is located immediately above the reservoir, and is supported by the gripping mechanism  22 . At this time, the gripping mechanism  22  withdraws the gripping force, so that the bioprinting construct falls vertically into the reservoir. This design can avoid the introduction of new contamination in the transfer operation process implemented manually or by robotic arm after the completion of printing, or the damage caused for printing the inner wall of a blood vessel due to inappropriate operation in the operational process, and facilitate the packaging of a finished product. 
     The present application correspondingly provides a method for printing lumen tissue construct using the aforementioned bioprinting platform, which comprises a mantling step: cladding a layer of elastic film on the outer wall of the rotary rod  211  before printing the biological construct. During the printing of the biological construct, the elastic film presents a natural state, and clads on the surface of the rotary rod  211 . The bio-block makes up a biological construct on the surface of the elastic film, thus favorable for removing the biological construct. Further, the printing method of the lumen tissue construct printing device further comprises a film ballooning step: ventilating into the elastic film to balloon the elastic film so that the biological construct is attached to the inner wall of the lumen tissue, after the lumen tissue is sleeved outside the biological construct. The biological construct on the surface of the elastic film is displaced outwards along with the expansion of the elastic film, and finally in contact with the inner wall of the lumen tissue and adhered onto the inner wall of the lumen tissue, so that the biological construct is completely evenly, intactly, and flatly attached on the inner wall of the lumen tissue, such as to obtain an artificial tissue precursor. It is demonstrated in practice that, the embodiment is easy to operate and implement, and presents a high implementability. 
     Next, the construction process of the artificial tissue precursor of the lumen tissue construct printing device of the present application is explained by exemplifying the embodiments shown in  FIGS. 1 to 14  as follows: 
     The bio-ink constructs a biological construct on the surface of the elastic film by means of the bio-block sprayhead  12 , and then a medical adhesive layer for adhering the bio-block and the lumen tissue is uniformly extruded on the surface of the biological construct by means of the medical adhesive sprayhead  11 . 
     After the biological construct is made, the hollow rod  231  moves toward the rotary rod  211  until the hollow rod  231  is completely sleeved outside the rotary rod  211 . At this time, the lumen tissue is completely outside the biological construct, and the hollow rod  231  moves towards a direction away from the rotary rod  211 , then the gripping mechanism  22  prevents the lumen tissue from following the movement of the hollow rod  231 . Finally, the hollow rod  231  is completely separated from the rotary rod  211 , but the lumen tissue remains outside the biological construct. Limited by the mechanical structure, there is inevitably a gap between the lumen tissue and the biological construct at this time, then an upward force is provided to the lumen tissue by means of the support platform  224 , so as to avoid uneven attachment between the biological construct and the artificial blood vessel resulting from a downward movement due to the effect of gravity. Then, the rotary rod  211  is internally ventilated to balloon the elastic film, so that the biological construct is completely attached onto the inner wall of the lumen tissue. The heating unit  212  heats to accelerate the coagulation of the bio-ink, to finally obtain an artificial tissue precursor, which is removed from the rotary rod  211 . 
     Since the printed artificial tissue precursor needs to detect the flatness of its inner wall, in an improved embodiment of the device for printing lumen tissue construct of the present application, the device may further comprise an optical probe movable inside the rotary rod  211 , for detecting the flatness of the inner wall of the biological construct, wherein the rotary rod  211  is made of a transparent material. There is a high implementability to design the optical probe in such a form as to be movable inside the rotary rod  211 , and to move the optical probe and photograph the internal wall of the biological construct by an image acquisition software before the artificial tissue precursor is removed from the rotary rod  211 , so as to judge whether the printed bio-block coating is intact, smooth and flat or not, and the embodiment adequately utilize the hollow structure inside the rotary rod  211  to improve the structural utilization rate, which presents a high implementability. 
     For how to effectuate that the optical probe is movable inside the rotary rod  211 , in some improved embodiments, the optical probe is fixedly disposed in the hollow rod  231 . For example, the hollow rod  231  is designed in a double-layer embedded structure, in which the first layer is used for embedding an artificial blood vessel, and the front end of the second layer is provided with an optical probe. The rotary rod  211  may also be a double-layer structure, in which ventilation is performed within the sandwich for ballooning the elastic film. The elastic film only covers the surface of the rotary rod  211  but does not cover the front end, such as to enable the optical probe to extend into the rotary rod  211 . In the assembly process, the lumen tissue is sleeved on the surface of the biological construct, and the optical probe also moves along with the hollow rod  231  to the furthest end of the biological construct. When the lumen tissue is removed, the optical probe also moves along with the hollow rod  231  to the foremost end of the artificial precursor tissue, so as to accomplish the flatness detection in the assembly process. Certainly, in other improved embodiments, the optical probe is movably disposed in the hollow rod  231 , that is, the optical probe moves independently with respect to the hollow rod  231 , and the flatness detection can also be accomplished. In some other modified embodiments, the optical probe is movably disposed in the rotary rod  211 , and the optical probe moves from one end to the other within the rotary rod  211  to accomplish the flatness detection. 
     The present application further provides a 3D bioprinter, which comprises the aforementioned device for printing lumen tissue construct. As the device of the present application can improve the biological reliability of the lumen tissue, correspondingly, the 3D bioprinter of the present application also has the advantageous technical effects described above, and thus will no longer be repeated here. 
     The above-combined embodiments make detailed explanations for the embodiments of the present application, but the present application is not limited to the embodiments described. For a person skilled in the art, multiple changes, modifications, equivalent replacements, and variations made to such embodiments still fall within the protection scope of the present application without departing from the principles and substantive spirit of the present application.