Method for producing low modulus articles

Abstract

A method for manufacturing a three-dimensional (3D) article includes operating a print engine to create a composite structure including the 3D article bonded to a support structure, removing the composite structure from a fluid tank, and peeling an inner surface of a sheath away from an outer surface of the article, the peeling sequentially breaking a plurality of strands. The support structure includes a conformal sheath having an inner surface that conforms to the outer surface of the 3D article, the sheath having a gap between the inner surface of the sheath and the outer surface of the article, and a plurality of strands that span the gap and have opposing ends that are bonded to the inner surface of the sheath and the outer surface of the article to maintain the gap, the gap being filled with a photocurable liquid ink.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 423731, filed November 8, 2022, and U.S. Provisional Patent Application No. 63 / 444151, filed February 8, 2023, the entire contents of which are incorporated herein by reference.

[0002] This disclosure relates to an apparatus and method for producing solid three-dimensional (3D) articles from radiation-curable (photocurable) inks, and more particularly to a method for supporting fragile 3D articles having low modulus of elasticity. [Background technology]

[0003] The use of three-dimensional (3D) printers is rapidly increasing. One class of 3D printers includes stereolithography printers, which have a general principle of operation that involves selectively hardening and curing radiation-curable (photocurable) liquid ink. A typical stereolithography system includes a liquid tank that holds the photocurable ink, a movement mechanism coupled to a support surface, and a controllable light engine. The stereolithography system forms three-dimensional (3D) articles by selectively curing layers of the photocurable ink on the support surface.

[0004] One particular challenge is forming 3D articles from brittle, low-modulus materials such as hydrogels. One potential application is printing artificial tissues or body implants. Damage can occur during the fabrication, post-processing, shipping, and handling of 3D articles. Summary of the Invention

[0005] One aspect of the present disclosure is a method for manufacturing a three-dimensional (3D) article having an outer surface using a print engine having a fluid reservoir, a movable build surface coupled to a movement mechanism, and a light engine. The method includes filling the fluid reservoir with a light-curable liquid ink, positioning the movable build surface within the light-curable ink proximate to the build plane, operating the movement mechanism and the light engine to create a composite structure including the 3D article coupled to a support structure, removing the composite structure from the fluid reservoir, and removing a sheath from the 3D article by peeling an inner surface of the sheath away from the outer surface of the article, where the peeling sequentially breaks the plurality of strands. The support structure includes a conformal sheath having an inner surface that conforms to an outer surface of the 3D article, the sheath having a gap between the inner surface of the sheath and the outer surface of the article; and a plurality of strands that span the gap and have opposing ends, the ends being bonded to the inner surface of the sheath and the outer surface of the article to maintain the gap, and the gap being filled with a photocurable liquid ink.

[0006] This method has advantages for very low modulus and delicate 3D articles, such as those printed from low modulus hydrogel materials. The combination of a conformal sheath and multiple strands effectively supports the 3D article during fabrication and removal from the liquid tank. Peeling the sheath off the article is easy and fast by hand. The low modulus strands do not damage delicate 3D articles when they break.

[0007] In one implementation, the photocurable liquid ink includes water, a photopolymer, and a catalyst. The ink may include more than 30% or more than 40% water by weight. The photocurable liquid ink cures in response to exposure to ultraviolet (UV), violet, and / or blue light.

[0008] In other implementations, the photocurable liquid ink is a hydrogel composition that includes, among other things, water, a natural or synthetic polymer, and a catalyst. Natural polymers for preparing hydrogels can include, among other things, hyaluronic acid, chitosan, heparin, alginic acid, and fibrin.

[0009] In still other implementations, the formed composite structure has an elastic modulus of less than 5 million Pascals (5 MPa), less than 2 million Pascals (2 MPa), less than 1 million Pascals (1 MPa), or in the range of 50,000 to 500,000 Pascals (50 to 500 KPa).

[0010] In further implementations, the gap may have a thickness of less than 2 millimeters (mm) or less than 1 millimeter (mm).

[0011] In still other implementations, the plurality of strands can include at least 25 strands, at least 50 strands, at least 100 strands, or at least 200 strands.

[0012] In other implementations, the strands individually include weakened areas within the gaps, and the strands preferentially break at the weakened areas when the inner surface of the sheath is peeled away from the outer surface of the article.

[0013] In yet other implementations, the 3D article is one of a contact lens, an artificial body tissue structure, and a soft implant.

[0014] In further implementations, the sheath can be left in place during post-processing and / or transportation. Post-processing can include cleaning, curing, coating, or otherwise treating the 3D article after fabrication. The sheath can be left on and removed after transportation to where it will be used. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a three-dimensional (3D) printing system for manufacturing a 3D article. [Figure 2] FIG. 2 is a flow chart illustrating one embodiment of a method for manufacturing a 3D article. [Figure 3] 3 is a simplified cross-sectional side view of a composite structure attached to a support tray, the composite structure including a 3D article and a support structure. [Figure 4] FIG. 4 is a simplified cross-sectional side view of a portion of a first embodiment of a composite structure. [Figure 5] FIG. 5 is a simplified cross-sectional side view of a portion of a second embodiment of a composite structure. [Figure 6] FIG. 6 is a simplified cross-sectional side view of a portion of a third embodiment of a composite structure. [Figure 7] FIG. 7 is a simplified cross-sectional side view of a portion of a fourth embodiment of a composite structure. [Figure 8] FIG. 8 is a side perspective view of a composite structure including a 3D printed article and a support structure, according to one embodiment. [Figure 9] FIG. 9 illustrates top and side perspective views of a composite structure including a 3D printed article and a support structure according to another embodiment. [Figure 10] FIG. 10 is a side view of the 3D printed article and support structure of FIG. [Figure 11] FIG. 11 is a cross-sectional view of the 3D printed article and support structure of FIG. [Figure 12] FIG. 12 is a front perspective view of a support structure according to the embodiment of FIG. 9, including a notch. [Figure 13] 13 is a top and side perspective view of a support structure according to the embodiment of FIG. [Figure 14] FIG. 14 is a perspective view of a composite structure including a 3D printed article and a support structure according to the embodiment of FIG. [Figure 15] FIG. 15 is a schematic diagram of various densities and gap distances of support structures for 3D printing an article, according to one embodiment. [Figure 16] FIG. 16 is a top perspective view of the removal of the 3D printed article from the support structure. DETAILED DESCRIPTION OF THE INVENTION

[0016] Unless the context indicates otherwise, it is specifically contemplated that the various features described herein may be used in any combination. Furthermore, the present disclosure also contemplates that, in some embodiments, any feature or combination of features described herein may be excluded or omitted. By way of example, if the specification states that a composite comprises components A, B, and C (or A, B, and / or C), it is specifically contemplated that any of A, B, or C, or combinations thereof, alone or in any combination, may be omitted and waived.

[0017] Unless expressly indicated otherwise, all specific embodiments, features, and terms are intended to include both the recited embodiment, feature, or term and its biological equivalents.

[0018] All numerical designations, including ranges, for example, pH, temperature, time, concentration, and molecular weight, are approximations that may vary by increments of 1.0 or 0.1, or by increments (+) or (-) of + / - 15%, alternatively 10%, alternatively 5%, alternatively 2%, as appropriate. It is to be understood, although not always explicitly stated, that all numerical designations are preceded by the term "about."

[0019] (definition) As used in describing the invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0020] The terms "substantially" and "about" are used herein to describe and explain small variations. When used in conjunction with an event or circumstance, the term can refer to instances where the event or circumstance occurs exactly, as well as instances where the event or circumstance occurs very nearly. When used in conjunction with a numerical value, the term can refer to a range of variation of ±10% or less of the numerical value, for example, ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.1%, or ±0.05%. When describing a first numerical value as being "substantially" or "about" equal to a second numerical value, the term can refer to the first numerical value being within a range of variation of ±10% or less of the second numerical value, for example, ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.1%, or ±0.05%. When used to describe the selection of any ingredient, range, dosage form, etc. disclosed herein, the terms "acceptable," "effective," or "sufficient" intend that the ingredient, range, dosage form, etc. is suitable for the purpose disclosed.

[0021] Additionally, amounts, ratios, and other numerical values ​​may be presented herein in range format. It should be understood that such range format is used for convenience and brevity and should be flexibly understood to include not only the numerical values ​​explicitly specified as the limits of the range, but also all individual numerical values ​​or subranges subsumed within that range, as if each numerical value and subrange were expressly specified. For example, a ratio range of about 1 to about 200 should be understood to include not only the explicitly recited endpoints of about 1 and about 200, but also individual ratios such as about 2, about 3, and about 4, as well as subranges such as about 10 to about 50 and about 20 to about 100.

[0022] Also, as used herein, "and / or" refers to and includes any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ("or").

[0023] As used herein, "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not occur.

[0024] Preferably, the ink is one that produces a low modulus article. As used herein, the term "low modulus" means less than 5 megapascals (MPa). Even more preferably, the modulus is less than 2 MPa. Preferred inks include soft hydrogel inks.

[0025] FIG. 1 is a schematic diagram of a three-dimensional (3D) printing system 2 for manufacturing a 3D article 4. The 3D printing system 2 includes a fluid reservoir 6, a build tray (e.g., build tray) 8 coupled to a movement mechanism 10, a light engine 12, and a controller 14. In describing the 3D printing system 2, mutually orthogonal axes X, Y, and Z are used. The X and Y axes are generally horizontal transverse axes. The Z axis is generally vertical or generally aligned with a gravity reference. When the term "generally" is used, it indicates that a direction or magnitude is not exact, but within manufacturing tolerances. Thus, generally aligned indicates alignment within manufacturing tolerances.

[0026] The fluid reservoir 6 includes upper and side walls 16 and a transparent sheet 18. In the illustrated embodiment, the transparent sheet 18 is semi-permeable, thereby allowing inhibitors such as oxygen to pass into the fluid reservoir 6 from below. The transparent sheet is a flexible polymer sheet that is generally transparent to ultraviolet (UV), violet, or blue light. The transparent sheet 18 may include one or more polymers, such as polyvinylidene fluoride (PVDF), ethylene chlorotrifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), polyvinylidene fluoride (PVDF), or other materials known in the art. The transparent sheet 18 may include an amorphous thermoplastic fluoropolymer film, such as TEFLON® AF 1600 (a trademark of Chemours, Inc., Wilmington, Delaware) or TEFLON® AF 2400™. Other materials are possible. In an exemplary embodiment, the transparent sheet 18 may have a thickness of approximately 80 microns (1000 microns equals 1 millimeter), although other thicknesses are possible.

[0027] Fluid reservoir 6 contains a photo-curable liquid ink (e.g., ink) 20. Photo-curable liquid ink 20 cures in response to exposure to ultraviolet (UV), violet, and / or blue light. In an exemplary embodiment, ink 20 contains at least a photo-curable liquid and a catalyst. The catalyst enables the ink to cure in response to exposure to radiation. In a further exemplary embodiment, the ink contains a combination of water and a water-miscible photopolymer.

[0028] In another exemplary embodiment, the ink is a hydrogel composition comprising, among other things, water, a natural or synthetic polymer, and a catalyst. The water is typically 30% by weight or more. Natural polymers for preparing hydrogels can include, among other things, hyaluronic acid, chitosan, heparin, alginate, and fibrin. Hydrogel bioinks are known in the art for printing 3D articles, such as soft artificial implants, contact lenses, and artificial tissues, to name a few.

[0029] In the illustrated embodiment, the build tray 8 has a downward-facing bottom surface 22 for supporting the 3D article 4. In other embodiments, the build tray 8 can have an upward-facing surface (embodiment not shown) for supporting the 3D article 4.

[0030] The movement mechanism 10 is a motorized device for vertically positioning the build tray 8 and outputting an encoder signal indicative of the vertical position of the build tray 8. In an exemplary embodiment, the movement mechanism 10 includes a vertically fixed portion and a vertically moving portion. The vertically moving portion supports the build tray and includes a threaded bearing. The vertically fixed portion includes a motor coupled to a lead screw received in the threaded bearing. When the motor rotates the lead screw, the action on the threaded bearing causes the build tray to translate up or down depending on the direction of rotation of the lead screw. The encoder may be a linear or rotary encoder and outputs a signal by which the controller 14 can determine and monitor the vertical position of the build tray 8 by estimating the position of the underside 22 of the build tray 8.

[0031] Alternative embodiments of the movement mechanism 10 are possible. One alternative embodiment is a rack-and-pinion system. In such a system, the build tray 8 is coupled to a vertical gear (rack) with vertically oriented gear teeth. A motor is coupled to a round pinion gear that engages the vertically oriented gear teeth. As the motor rotates, the build tray 8 is translated up and down. Yet another alternative is based on a belt and pulley system. A belt is coupled to the build tray 8, and a motorized gear engages and translates the belt, thereby vertically translating the build tray 8. With any of these mechanisms, the motor can be indirectly coupled via a reduction gear train, improving precision and movement force. Various movement mechanism 10 designs for 3D printing are known.

[0032] Light engine 12 is configured to project or transmit pixelated radiation upward through transparent sheet 18. In one embodiment, light engine 12 is a stationary projector based on a radiation source, a spatial light modulator, and projection optics. Such light engines are known in the art for digital projectors that transmit visible or ultraviolet light to selectively cure resins for stereolithography. In a second embodiment, the light engine can include a scanning light bar having a linear array of light emitting diodes. In a third embodiment, the light engine can include a laser and scanning optics. The scanning optics can include a galvanometer mirror for scanning a laser beam onto transparent sheet 18. Such light engines are all known in the field of stereolithography.

[0033] The controller 14 is coupled to the movement mechanism 10, the light engine 12, and other portions of the 3D printing system 2. The controller 14 includes a processor 24 coupled to an information storage device 26. The processor 24, which may alternatively be referred to as a CPU (Central Processing Unit), is an electronic circuit that executes software instructions. The information storage device 26 is a non-transitory storage device that stores the software instructions. When executed by the processor 24, the software instructions control and monitor portions of the 3D printing system 2.

[0034] To fabricate article 4, controller 14 performs the following steps: (A) operates movement mechanism 10 to position underside 22 of build tray (or future 3D article 4) on build plane 28 directly above transparency sheet 18; (B) operates light engine 12 to selectively illuminate build plane 28 to selectively harden and cure the layer of ink 20 on underside 22 of build tray or 3D article 4; (C) repeats steps A and B to complete fabrication of 3D article 4. Notably, support structures are also fabricated to provide support for 3D article 4 to build tray 8. As will be seen below, steps A-C are only a subset of the steps for manufacturing article 4, the subject of FIG. 2 .

[0035] 2 is a flow chart illustrating one embodiment of a method 30 for manufacturing a 3D article 4. According to 32, a 3D printing system 2 is provided that includes a fluid reservoir 6, a movement mechanism 10, and a light engine 12. According to 34, the fluid reservoir 6 is filled with a light-curable liquid ink 20. In an exemplary embodiment, the ink 20 is a light-curable hydrogel composition that includes water, a natural polymer, a synthetic polymer, and a catalyst. According to 36, a support tray 8 is loaded onto the movement mechanism 10.

[0036] According to 38, the controller 14 operates the 3D printing system to fabricate a composite structure 50 according to steps A-C discussed above. The composite structure 50 is shown attached to a support tray 8 in FIG. 3. In the illustrated embodiment, the composite structure 50 includes a 3D article 4 and a support structure 52 that surrounds and supports the 3D article 4. The support structure 52 includes three types of components, including a conformal sheath (e.g., sheath) 54, connecting strands 56, and support posts 58.

[0037] The 3D article 4 has an outwardly facing outer surface 60. The conformal sheath 54 generally "follows" or is conformal to the outer surface 60. The conformal sheath 54 has an inner surface 62 in facing relationship to the outer surface 60, with a fluid-filled gap 64 therebetween. The fluid-filled gap 64 is filled with the photocurable liquid ink 20.

[0038] A plurality of connecting strands 56 couple the outer surface 60 to the inner surface 62. The connecting strands 56 act to maintain a gap 64 between the outer surface 60 and the inner surface 62. The connecting strands control and maintain the size of the gap 64 measured perpendicular to the surfaces 60 and 62. In a first exemplary embodiment, the size of the gap 64 is less than 2 millimeters. In a second exemplary embodiment, the size of the gap 64 is less than 1 millimeter. The connecting strands 56 individually have a thickness measured parallel to the outer surface 60 and the inner surface 62 of less than 2 millimeters or less than 1 millimeter.

[0039] The support posts 58 couple the conformal sheath 54 to the underside 22 of the build tray 8. The thickness or design of the support posts 58 is selected to ensure a stable coupling of the sheath 54 to the build tray 8.

[0040] The composite structure 50 is generally a very low modulus material, such as a hydrogel. Typically, the modulus is less than 5 megapascals, less than 2 megapascals, or less than 1 megapascal. Note that 1 million pascals equals 1 megapascal, which equals 1 MPa.

[0041] 2, according to step 40, the support tray 8 and composite structure 50 are removed from the fluid tank 6. According to 42, the composite structure 50 is separated from the build tray 8.

[0042] According to 44, the sheath 54 is peeled away from the 3D article 4. As the sheath 54 is peeled away from the article 4, the connecting strands 56 spanning the gap 64 are broken. Compared to conventional support methods, this removal of the support structure 52 can be performed quickly, easily, and essentially without damaging the article 4.

[0043] In some embodiments, post-processing and / or transportation can occur between steps 42 and 44. Post-processing can include one or more of cleaning, washing, surface treatment, surface coating, UV curing, and heat curing, to name a few. If transportation (via logistics services including one or more of land, air, rail, and ocean) is performed before step 44, support structure 52 can form part of the packaging to avoid damage during transportation.

[0044] 4 shows a first embodiment of a portion of a composite structure 50 having a first embodiment of connector strands 56. The connector strands 56 individually have pointed or small cross-sectional area tips 66 for bonding to the exterior surface 60 of the 3D article 4. In this design, the tips have a small cross-sectional area that requires very little force to remove them from the exterior surface 60. Furthermore, at the same time, the connector strands 56 provide the function of maintaining a fluid gap 64.

[0045] 5 shows a second embodiment of a portion of a composite structure 50 having a second embodiment of connector strands 56. The connector strands 56 individually have weakened areas or side notches 68. During the peel process, the connector strands 56 tend to break along the side notches 68.

[0046] 6 shows a third embodiment of a portion of a composite structure 50 having a third embodiment of connector strands 56. The connector strands 56 individually have weakened areas or annular notches 70. During the peel process, the connector strands 56 tend to break along the annular notches 70.

[0047] Figure 7 shows a fourth embodiment of a portion of a composite structure 50 having a fourth embodiment of connecting strands 56. The strands have a converging or narrowing geometry from surfaces 60 and 62 to weakened areas 72. Other designs of connecting strands 56 are possible, and it is even possible to combine two or more of the examples shown in Figures 4-7.

[0048] 8-16, a support structure 52 and 3D printed article 4 according to another embodiment are shown. According to this embodiment, the build tray 8 is flat and mimics the contours of the 3D printed object 4.

[0049] According to this embodiment, the support pillars 58 are of a gyroid design (e.g., infinitely connected) and extend vertically upward from the build tray 8, with gaps 64. The support pillars 58 are connected horizontally such that each support pillar 58 is connected to an adjacent support pillar 58. The gaps 64 between the support pillars 58 may be diamond-shaped or may have various other shapes.

[0050] 8-16 further includes a conformal sheath 54. The sheath 54 is disposed on top of the support posts 58. For example, the sheath 54 is disposed at the distal end of the support posts 58 relative to the build tray 8.

[0051] The plurality of connecting strands 56 further includes a plurality of touch points 80. The touch points 80 extend through the sheath 54. The touch points 80 are removably coupled to the 3D-printed object 4. Placing the sheath 54 as close as possible to the 3D-printed object 4 while maintaining a gap during printing provides additional support. Pre-cured ink between the 3D-printed article 4 and the sheath 54 provides Stefan adhesion, which helps hold the 3D-printed article 4 in place. The sheath 54 does not need to completely encase the 3D-printed article 4, and thin cuts can be provided in the support posts 58 to facilitate removal, if desired.

[0052] As shown in Figures 10-12, after the printing process is completed, the 3D printed object 4 is removed from the support structure 52. The 3D printed object 4 is pulled away from the support structure 52 at an angle in a lift direction 90. During the removal process, the touch points 80 between the 3D printed object 4 and the support structure 52 are broken.

[0053] 11, a cross-sectional view of the embodiment of the support structure 52 and 3D printed object 4 of FIG. 9 is shown. As shown in FIG. 11, the 3D printed object 202 is coupled to the support structure 52 by small touchpoints 80. The embodiment of the support structure 52 and 3D printed object 4, 202 further includes a space 100. The space 100 is defined by the sheath 54 and a proximal side of the 3D printed object 4.

[0054] The distance between touch points 80 may vary. For example, the 3D printed structure 4 may include a body 102 and a flange 104. The body 102 may be elongated and thick, while the flange 104 may be thin and delicate. For example, the flange 104 may have more touch points 80 than the body 102. Furthermore, the flange 104 may be joined with more touch points 80 that are closer together. Alternatively, the body 102 may have fewer touch points 80 that are spread farther apart. The flange 104 may require more touch points 80 because it is a more delicate structure that may lack its own structural support before curing.

[0055] 13-14, front and back perspective views of the support structure 52 and the 3D-printed object 4 are shown, respectively. The support structure 52 may further include a plurality of slits 110. According to this embodiment, the support structure 52 surrounds the 3D-printed object 4. For example, the support structure 52 may support a portion of the 3D-printed object 4 from below and above the 3D-printed object 4. For example, this may be advantageous for supporting a 3D-printed object 4 having a hollow interior cavity.

[0056] According to this embodiment, the support structure 52200 includes an arch portion 112 that defines an interior cavity 114 for the 3D printed object 4. A plurality of slits 110 are positioned on the arch portion 112. For example, the plurality of slits 110 may be break points for the support structure 52 during removal of the 3D object 4. For example, when removing the 3D printed object 4, the plurality of slits 110 may completely break the support structure 52 when a user peels the 3D printed object 4 from the support structure 52.

[0057] 15 is a schematic diagram illustrating differences in gap size and density of touch points 80. The differences in gap size and density of touch points 80 can vary based on the shape of the object being printed. Additionally, varying the gap size and density of touch points 80 can facilitate removal of the 3D printed object 4 while still supporting the 3D printed object 4 during printing.

[0058] 16 , a perspective view is shown of a user 200 removing the 3D printed object 4 from the support structure 52. As shown in FIG. 16 , the user 200 can use a finger (e.g., a thumb) to separate the 3D printed object 4 from the support structure 52. For example, the user 200 can press the finger between the support structure 52 and the 3D printed object 4, and then peel the 3D printed object 4 away from the support structure 52, breaking the touch point 80.

[0059] The particular embodiments and applications thereof described above are for illustrative purposes only and do not exclude modifications and variations encompassed by the scope of the following claims.

[0060] These examples are provided for illustrative purposes only and are not intended to limit the scope of the claims provided herein.

[0061] While particular embodiments have been illustrated and described, it will be understood by those skilled in the art that changes and modifications can be made without departing from the scope of the invention in its broader aspects as defined in the following claims.

[0062] The embodiments illustratively described herein may suitably be practiced in the absence of any element(s), limitation(ies) not specifically disclosed herein. Thus, for example, terms such as "comprising," "including," and "containing" are intended to be read expansively and without limitation. Furthermore, the terms and expressions used herein are used as terms of description and not of limitation, and the use of such terms and expressions is not intended to exclude the described and illustrated features or equivalents thereof, recognizing that various modifications are possible within the scope of the claims. Furthermore, the phrase "consisting essentially of" should be understood to include the specifically described elements and additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase "consisting of" excludes any elements not specified.

[0063] The present disclosure should not be limited in terms of the specific embodiments described in this application. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent methods and compositions within the scope of the present disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the language of the appended claims, along with the full scope of equivalents to which the appended claims are entitled. It is to be understood that the present disclosure is not limited to particular methods, reagents, compounds, or compositions, as these may, of course, vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0064] Furthermore, when features or aspects of the present disclosure are described in terms of a Markush group, one skilled in the art will understand that the present disclosure is also described with respect to any individual member of that Markush group or any subgroup of members thereof.

[0065] As will be understood by those skilled in the art, for any and all purposes, particularly with respect to providing a written description, all ranges disclosed herein encompass any and all possible subranges and combinations of subranges, including the endpoints. It will be readily recognized that any numerical range is sufficient to describe and allow for equal ranges divided into at least two, three, four, five, ten, etc. equal parts. As a non-limiting example, each range described herein can be readily divided into a lower third, middle third, upper third, etc. Furthermore, as will be understood by those skilled in the art, the terms "up to," "at least," "greater than," "less than," and the like, refer to ranges that are inclusive of the recited numerical values ​​themselves and that can be divided into subranges as described above. Finally, as will be understood by those skilled in the art, a numerical range encompasses each of its constituent numerical values ​​individually.

[0066] All publications, patent applications, issued patents, and other documents referenced herein are incorporated by reference as if each such publication, patent application, issued patent, or other document were individually and expressly incorporated herein in its entirety. Definitions contained in texts incorporated by reference are excluded to the extent they conflict with definitions in this disclosure.

[0067] Other embodiments are set forth in the following claims.

Claims

1. 1. A method for manufacturing a three-dimensional (3D) article having an exterior surface using a print engine having a fluid reservoir, a movable build surface coupled to a movement mechanism, and a light engine, the method comprising: filling the fluid reservoir with a photocurable liquid ink; positioning the movable build surface proximate to a build plane within the photocurable ink; operating the movement mechanism and the light engine to create a composite structure comprising the 3D article coupled to a support structure, the support structure comprising: a conformal sheath having an inner surface that conforms to the outer surface of the 3D article, the sheath having a gap between the inner surface of the sheath and the outer surface of the article; and operating the movement mechanism and the light engine, the plurality of strands comprising a plurality of strands that span the gap and have opposing ends, the ends being bonded to the inner surface of the sheath and the outer surface of the article to maintain the gap, the gap being filled with the photocurable liquid ink; removing the composite structure from the fluid tank; removing the sheath from the 3D article, the sheath comprising peeling the inner surface of the sheath away from the outer surface of the article, the peeling sequentially breaking the plurality of strands.

2. The method of claim 1 , wherein the photocurable liquid ink is a hydrogel bioink comprising water, a photopolymer, and a catalyst.

3. The method of claim 1 , wherein operating the light engine comprises curing the light curable liquid ink layer by layer.

4. The method of claim 1 , wherein the photocurable liquid ink is at least 30% water by weight.

5. The method of claim 1 , wherein the formed composite structure has a modulus of elasticity of less than 5 million Pascals (5 MPa).

6. The method of claim 1 , wherein the formed composite structure has a modulus of elasticity of less than 2 million Pascals (2 MPa).

7. The method of claim 1 , wherein the formed composite structure has a modulus of elasticity of less than 1 million Pascals (1 MPa).

8. The method of claim 1, wherein the formed composite structure has a modulus of elasticity in the range of 50,000 to 500,000 Pascals (50 to 500 KPa).

9. The method of claim 1 , wherein the article is one of a contact lens, an artificial body tissue structure, and a soft implant.

10. The method of claim 1 , wherein the gap has a thickness of less than 2 millimeters (mm).

11. The method of claim 1 , wherein the gap has a thickness of less than 1 millimeter (mm).

12. The method of claim 1 , wherein the plurality of strands comprises at least 25 strands.

13. The method of claim 1 , wherein the plurality of strands comprises at least 50 strands.

14. The method of claim 1 , wherein the plurality of strands comprises at least 100 strands.

15. The method of claim 1 , wherein the plurality of strands individually have a thickness of less than 1 millimeter.

16. 2. The method of claim 1, wherein the plurality of strands each include a weakened portion within the gap, and the plurality of strands preferentially break at the weakened portion when the inner surface of the sheath is peeled away from the outer surface of the article.

17. 10. The method of claim 1, wherein the method further comprises post-processing the composite structure prior to removing the sheath from the 3D article, wherein post-processing comprises one or more of cleaning, curing, coating, and treating the 3D article.

18. 1. A method for manufacturing a three-dimensional (3D) article having an exterior surface using a print engine having a fluid reservoir, a movable build surface coupled to a movement mechanism, and a light engine, the method comprising: filling the fluid reservoir with a photocurable liquid ink; positioning the movable build surface proximate to a build plane within the photocurable ink; operating the movement mechanism and the light engine to create a composite structure comprising the 3D article coupled to a support structure, the support structure comprising: a conformal sheath having an inner surface that conforms to the outer surface of the 3D article, with a gap of less than 2 millimeters between the inner surface of the sheath and the outer surface of the article; and operating the movement mechanism and the light engine, the plurality of strands comprising at least 25 strands that span the gap and have opposing ends, the ends being bonded to the inner surface of the sheath and the outer surface of the article to maintain the gap, and the gap being filled with the photocurable liquid ink; removing the composite structure from the fluid tank; peeling the inner surface of the sheath away from the outer surface of the article, the peeling sequentially breaking the plurality of strands.

19. 1. A method for manufacturing a three-dimensional (3D) article having an exterior surface using a print engine having a fluid reservoir, a movable build surface coupled to a movement mechanism, and a light engine, the method comprising: filling the fluid reservoir with a photocurable liquid ink; positioning the movable build surface proximate to a build plane within the photocurable ink; operating the movement mechanism and the light engine to create a composite structure comprising the 3D article coupled to a support structure, wherein the 3D article and the support structure have an elastic modulus of less than 5 million Pascals, and the support structure comprises: a conformal sheath having an inner surface that conforms to the outer surface of the 3D article, with a gap of less than 2 millimeters between the inner surface of the sheath and the outer surface of the article; and operating the movement mechanism and the light engine, the plurality of strands comprising at least 25 strands that span the gap and have opposing ends, the ends being bonded to the inner surface of the sheath and the outer surface of the article to maintain the gap, and the gap being filled with the photocurable liquid ink; removing the composite structure from the fluid tank; peeling the inner surface of the sheath away from the outer surface of the article, the peeling sequentially breaking the plurality of strands.

20. The method of claim 19 , wherein the support structure comprises a plurality of support columns.

21. 21. The method of claim 20, wherein the plurality of support pillars are gyroid-like structures.

22. 20. The method of claim 19, wherein the support structure further comprises a plurality of slits, the plurality of slits weakening the support structure during removal of the 3D printed article such that the support structure breaks.

23. 20. The method of claim 19, wherein the support structure further comprises a plurality of connecting strands, the plurality of connecting strands comprising a plurality of touch points.

24. 23. The method of claim 22, wherein a size and density of the plurality of touch points is adjusted based on a composition of the photocurable ink and the 3D article being printed.

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