Cluster Rotating Jet Spinning Devices and Methods of Their Use

Abstract

Systems and methods for the focused deposition of micron- or nanometer-sized polymeric fibers and materials for such fibers are described herein. The systems and methods employ one or more gas streams to entrain and deflect fibers produced by a rotary jet spinning system to form a focused fiber stream. Some embodiments enable control of fiber alignment and distribution with relatively high fiber throughput. In one embodiment, the one or more gas stream sources comprise multiple gas stream sources having converging orientations to form a combined gas stream in a first direction.

Description

Technical Field

[0001] (Related Application) This application claims the benefit and priority of U.S. Provisional Application No. 62 / 792,036, filed on Jan. 14, 2019, the entire contents of which are incorporated herein by reference in their entirety.

[0002] (Government Support) The present invention was made with government support under Grant No. DMR-1420570 awarded by the U.S. National Science Foundation. The government has certain rights in the invention.

[0003] (Technical Field) Embodiments of the present disclosure relate to a directional rotary jet spinning system for manipulating the movement of fibers using air flow convergence.

Background Art

[0004] Fibrous structures are used by nature and engineers for many functions, such as fiber reinforcement, filtration, thermal insulation, actuation control, etc. The realization of these functions depends greatly on both the fiber diameter and 3D weaving. Many biological tissues consist of small-diameter fibers (e.g., fibers with diameters on the micron or nanoscale) arranged in complex three-dimensional alignments. For example, muscle fibers that control human movement have diameters of about 10 μm to about 100 μm and are bundled into fiber bundles along the direction of actuation. As another example, collagen fibrils, which are the main components of the extracellular matrix, have diameters of about 10 nm to about 100 nm and are woven into a variety of structures for the different mechanical properties of different tissues. Humans have a history of successfully engineering thick fibrous structures with diameters of about 100 μm or more, but engineering fine fibrous structures with diameters of about 10 μm or less by controlling fiber alignment and weaving using conventional techniques remains an issue. One of the issues is, as shown in FIGS. 1A-1C, the simultaneous realization of fine fiber diameters, complex three-dimensional (3D) structures, and high throughput, as illustrated by a comparison of two main fiber manufacturing techniques: random fiber deposition (random FD) and extrusion 3D printing (extrusion 3DP). For example, in random FD techniques such as melt blowing and electrospinning, the fibers approach the target in randomly arranged groups and can exhibit poor control over fiber alignment and 3D geometry. Neither the spatial distribution inside the group nor the fiber orientation is adjusted. Poor control over the fiber group leads to poor control over deposition. In contrast, extrusion 3DP extrudes fibers through a movable nozzle that precisely controls the location and alignment of the deposition of each part of the fiber. However, extrusion 3DP has a low throughput. Both techniques are capable of producing fibers over a wide range of diameters, but only extrusion 3DP can produce complex 3D structures, while random FD is orders of magnitude more advantageous in throughput for fine fibers. The throughput limit is inherent, and to fill the same volume, the required fiber length increases rapidly as the fiber diameter decreases.Extrusion 3DP requires tracking the fiber length (e.g., length > 100 km for some applications), while fiber deposition does not.

[0005] Accordingly, there is a need in the art for an improved system that enables the generation of complex 3D structures of small diameter fibers (e.g., fibers having a diameter of less than 10 microns) with high throughput. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0006] Some embodiments of the present invention include a rotary jet spinning system configured to manipulate fiber movement through an externally supplied gas (e.g., an air stream) to form a directional flow of fibers. Some embodiments enable control of fiber alignment and have a relatively high throughput.

[0007] Some embodiments provide a system for the focused directional deposition of one or more micron or nanometer scale polymer fibers. The system includes a reservoir configured to hold a material containing a polymer and rotatable about an axis of rotation. The reservoir includes a first end, a second end opposite the first end, and an outer sidewall extending from the first end to the second end, the shape of the reservoir including one or more openings disposed radially inward from the outer sidewall of the reservoir configured to allow gas to move through the reservoir from the first end to the second end, and one or more orifices formed within the outer sidewall, each of the one or more orifices including one or more orifices configured for the radially outward injection of material through the orifice as an injected jet during rotation of the reservoir. The system includes one or more gas flow sources each configured to direct a flow of gas from upstream of the first end of the reservoir through one or more openings of the reservoir to downstream of the second end of the reservoir during rotation of the reservoir, the one or more gas flow sources collectively forming a combined gas flow in a first direction downstream of the second end of the reservoir that captures and deflects one or more injected jets, forming a focused flow of one or more micron or nanometer scale polymer fibers in the first direction, the first direction having an orientation within 5 degrees of the axis of rotation of the reservoir.

[0008] In some embodiments, one or more gas flow sources comprise a plurality of gas flow sources having a converging orientation to form a combined gas flow in a first direction. In some embodiments, the gas flow rate of at least some of the plurality of gas flow sources relative to other of the gas flow sources is controllable to achieve a balanced combined gas flow. In some embodiments, the number and arrangement of the plurality of gas flow sources are configured such that at any single point in time during rotation of the reservoir, the gas flow from all of the plurality of gas flow sources flows through an opening of one or more openings of the reservoir or the gas flow from all of the plurality of gas flow sources is blocked by the reservoir. In some embodiments, the plurality of gas flow sources comprises three gas flow sources.

[0009] In some embodiments, the total gas flow rate from one or more gas flow sources is controllable to vary the distance from the reservoir at which the flow of polymer fibers of micron or nanometer dimensions has its tightest focus.

[0010] In some embodiments, the first direction is within two degrees of the axis of rotation. In some embodiments, the first direction is substantially parallel to the axis of rotation.

[0011] In some embodiments, the converging flow of one or more polymer fibers of micron or nanometer dimensions has a flow width smaller than the diameter of the outer sidewall of the reservoir.

[0012] In some embodiments, the system is disposed upstream of a plurality of gas flow sources and is configured to reduce the influence of the air flow upstream of the plurality of gas flow sources on the focusing of the flow of polymer fibers of micron or nanometer dimensions. In some embodiments, the flow blocking structure is disposed upstream of the rotary reservoir and is configured to at least partially block the air flow from upstream of the rotary reservoir, reducing the influence of the air flow from upstream of the rotary reservoir on the interaction between the air flow resulting from the rotation of the reservoir and the flow of gas through one or more openings. In some embodiments, the flow blocking structure is stationary and does not rotate with the reservoir. In some embodiments, the flow blocking structure enables enhanced control of the vortex structure generated by the gas flow and the rotation of the reservoir, thereby improving the control of the lateral area of the deposition of polymer fibers of micron or nanometer dimensions as the fibers travel towards the target.

[0013] In some embodiments, one or more gas flow sources are configured to enable control of the gas flow rate and to focus the lateral area of the deposition of polymer fibers of micron or nanometer dimensions as the fibers travel towards the target.

[0014] In some embodiments, the system further comprises a target rotation system configured to rotate a three-dimensional target during deposition and deposit fibers on two or more sides of the target.

[0015] In some embodiments, the system is configured to be handheld.

[0016] In some embodiments, the system further comprises a coagulation, precipitation, or cross-linking reservoir configured to hold a bath for the coagulation, precipitation, or cross-linking of the injected polymer material.

[0017] In some embodiments, the system further comprises a heat source for heating the polymer material prior to delivery to the reservoir or while within the reservoir.

[0018] In some embodiments, the system is configured for co-deposition of fibers and further includes a second reservoir configured to hold a second material including a second polymer and rotatable about a second axis of rotation. The second reservoir has a first end, a second end opposite the first end, and an outer sidewall extending from the first end to the second end, the shape of the second reservoir including an outer sidewall having one or more openings disposed radially inward from the outer sidewall of the reservoir configured to allow gas to move from the first end to the second end through the reservoir, and one or more orifices formed within the outer sidewall, each of the one or more orifices including one or more orifices configured for ejection of a second polymeric material radially outward through the orifice as a second ejected jet during rotation of the second reservoir. The system further includes a second plurality of gas flow sources each configured to direct a flow of gas from upstream of the first end of the second reservoir through one or more openings of the second reservoir to downstream of the second end of the second reservoir of the second reservoir during rotation of the second reservoir, the plurality of gas flow sources converging such that the flow from the plurality of gas flow sources collectively forms a second combined gas flow in a second direction downstream of the second end of the second reservoir that entrains and deflects the second ejected jet to form a second focused flow of polymeric fibers of one or more second micron or nanometer dimensions in the second direction, the second direction having an orientation within 5 degrees of the axis of rotation of the second axis of rotation. The first direction and the second direction are directed for deposition on the same collection surface. In some embodiments, the system is configured for simultaneous deposition of one or more fibers of a first polymer and one or more fibers of a second polymer on the same collection surface.

[0019] Some embodiments provide a method for the formation and deposition of at least one micron or nanometer-sized polymer fiber. The method includes rotating a reservoir that holds a material having a polymer around a rotation axis, ejecting at least one ejection of the material from at least one orifice defined by an outer sidewall of the reservoir, and directing at least one flow of gas through a portion of the reservoir radially inward of the outer sidewall, wherein at least one flow of gas is directed from a first end upstream of the reservoir to a second end downstream of the reservoir during rotation of the reservoir and ejection of at least one ejection of the material, forming at least one micron or nanometer-sized polymer fiber, and at least one flow of gas entrains one micron or nanometer-sized polymer fiber and forms a converging fiber deposition stream of at least one micron or nanometer-sized polymer fiber in a first direction, the first direction having an orientation within 5 degrees of the rotation axis of the reservoir, and collecting the converging fiber deposition stream on a target surface.

[0020] In some embodiments, the first direction is substantially parallel to the rotation axis of the reservoir.

[0021] In some embodiments, at least one flow of gas includes a plurality of flows of gas that converge to form a combined gas flow in the first direction. In some embodiments, the flow rate of at least a portion of the plurality of converging gas flows relative to other of the plurality of converging gas flows is controllable to achieve a balanced combined gas flow. In some embodiments, the total gas flow rate of the plurality of converging gas flows is controllable to vary the distance from the reservoir at which the converging fiber deposition stream of at least one micron or nanometer-sized polymer fiber has the tightest focus. In some embodiments, the plurality of gas flows includes three gas flows.

[0022] In some embodiments, the converging fiber deposition stream has a substantially tangential orientation with respect to the target surface during fiber collection.

[0023] In some embodiments, the method further includes rotating the target surface during fiber collection.

[0024] In some embodiments, the method further includes at least partially blocking the flow of gas from upstream of the reservoir and reducing the influence of the airflow upstream of the plurality of gas flow sources on the focusing of the fiber deposition flow of at least one micron or nanometer-sized polymer fiber.

[0025] In some embodiments, the target surface is linearly moved during deposition of the fiber flow.

[0026] In some embodiments, the material in the reservoir comprises a solvent.

[0027] In some embodiments, the material in the reservoir comprises a polymer melt. In some embodiments, the method further includes heating the reservoir.

[0028] In some embodiments, at least one injected jet contacts the bath prior to being collected on the target. In some embodiments, the bath comprises a crosslinking agent. In some embodiments, at least one injected jet precipitates in the bath to form at least one micron or nanometer-sized polymer fiber. In some embodiments, at least one injected flow solidifies in the bath to form at least one micron or nanometer-sized polymer fiber.

[0029] In some embodiments, at least one micron or nanometer-sized polymer fiber is deposited for reinforcement of a composite material.

[0030] In some embodiments, at least one micron or nanometer-sized polymer fiber is deposited on one or more items of food.

[0031] In some embodiments, the method further includes rotating a second reservoir holding a second material having a second polymer about a second axis of rotation and ejecting at least one injection of the second material from at least one orifice defined by an outer sidewall of the second reservoir. The method is directing at least one second flow of gas through a radially inner portion of the outer sidewall of the second reservoir, wherein the at least one second flow of gas is directed from a first end upstream of the second reservoir to a second end downstream of the second reservoir during rotation of the second reservoir and ejection of at least one injection of the second material, forming at least one micron or nanometer sized polymeric fiber of the second polymer, and the at least one second flow of gas entrains at least one micron or nanometer sized polymeric fiber of the second polymer to form a second focused fiber deposition stream. The method also includes collecting the second focused fiber deposition stream on a target surface. In some embodiments, collection of the first focused fiber deposition stream overlaps in time with collection of the second focused fiber deposition stream.

[0032] Some embodiments provide a method of forming a three-dimensional tissue scaffold that includes performing any of the methods described herein where the target surface is a three-dimensional shape for a tissue scaffold. In some embodiments, the method also includes rotating the target for deposition on two or more sides of the three-dimensional shape.

[0033] The embodiments disclosed herein meet these and other needs by providing systems and methods for flow fiber deposition.

[0034] Other features and advantages of the invention will be apparent from the following detailed description and claims. The present invention provides, for example, the following items. (Item 1) A system for the convergent directional deposition of one or more polymer fibers of micron or nanometer dimensions, the system comprising: A reservoir configured to hold a material containing a polymer and rotatable about a rotation axis, the reservoir comprising: A first end; A second end opposite the first end; An outer sidewall extending from the first end to the second end, the shape of the reservoir including one or more openings disposed radially inward from the outer sidewall of the reservoir, the one or more openings being configured to allow gas to move through the reservoir from the first end to the second end, an outer sidewall; One or more orifices formed within the outer sidewall; Including; Each of the one or more orifices is configured for the radially outward injection of the material through the orifice as an ejected jet during rotation of the reservoir, a reservoir; One or more gas flow sources; Comprising; Each of the one or more gas flow sources is configured to direct the flow of gas from upstream of the first end of the reservoir through the one or more openings of the reservoir from the first end to the second end of the reservoir during rotation of the reservoir, and the one or more gas flow sources collectively form a combined gas flow in a first direction downstream of the second end of the reservoir, the combined gas flow taking in and deflecting the one or more ejected jets to form a convergent flow of the one or more polymer fibers of micron or nanometer dimensions in the first direction, the first direction having an orientation within 5 degrees of the rotation axis of the reservoir, a system. (Item 2) The system according to item 1, wherein the one or more gas flow sources comprise a plurality of gas flow sources having a converging orientation for forming a combined gas flow in the first direction. (Item 3) The system according to item 2, wherein the gas flow rate of at least some of the plurality of gas flow sources relative to other ones of the gas flow sources is controllable to achieve a balanced combined gas flow. (Item 4) The system according to item 1, wherein the total gas flow rate from the one or more gas flow sources is controllable to vary the distance from the reservoir having the tightest focus of the flow of the polymer fibers of micron or nanometer dimensions. (Item 5) (Item 6) The system according to item 2, wherein the number of the plurality of gas flow sources and the arrangement of the plurality of gas flow sources are such that, at any single point in time during the rotation of the reservoir, the gas flow from all of the plurality of gas flow sources flows through an opening among the one or more openings of the reservoir, or the gas flow from all of the plurality of gas flow sources is blocked by the reservoir. (Item 6) (Item 7) The system according to any one of items 2-5, wherein the plurality of gas flow sources comprises three gas flow sources. (Item 7) (Item 8) The system according to any one of items 1-6, wherein the first direction is within two degrees of the axis of the rotation. (Item 8) (Item 8) The system according to any one of items 1-6, wherein the first direction is substantially parallel to the axis of the rotation. (Item 9) (Item 10) The system according to any one of items 1-8, wherein the converging flow of the one or more polymer fibers of micron or nanometer dimensions has a flow width smaller than the diameter of the outer side wall of the reservoir. (Item 10) (Item 11) The system according to any one of items 1-10, further comprising a flow blocking structure disposed upstream of the plurality of gas flow sources, the flow blocking structure being configured to reduce the influence of the air flow upstream of the plurality of gas flow sources on the focusing of the flow of the polymer fibers of micron or nanometer dimensions. (Item 11) (Item 12) The system according to item 10, wherein the flow blocking structure is disposed upstream of the rotating reservoir and at least partially blocks the air flow from upstream of the rotating reservoir, and is configured to reduce the influence of the air flow from upstream of the rotating reservoir on the interaction between the air flow caused by the rotation of the reservoir and the flow of the gas through the one or more openings. (Item 12) (Item 13) The system according to item 10 or item 11, wherein the flow blocking structure is stationary and does not rotate with the reservoir. (Item 13) The flow interruption structure enables enhanced control of the structure of vortices generated by the flow of the gas and the rotation of the reservoir, thereby improving the control of the lateral area of the deposition of the micron- or nanometer-sized polymer fibers as the fibers travel towards the target, according to any one of items 10 - 12 of the system described. (Item 14) The one or more gas flow sources are configured to enable control of the gas flow rate so as to focus the lateral area of the deposition of the micron- or nanometer-sized polymer fibers as the fibers travel towards the target, according to any one of items 1 - 13 of the system described. (Item 15) The system further comprises a target rotation system, the target rotation system is configured to rotate the three-dimensional target during deposition and deposit the fibers on two or more sides of the target, according to any one of items 1 - 14 of the system described. (Item 16) The system is configured to be hand-held, according to any one of items 1 - 15 of the system described. (Item 17) The system further comprises a coagulation, precipitation, or cross-linking reservoir configured to hold a bath for coagulation, precipitation, or cross-linking of the injected polymer material, according to any one of items 1 - 15 of the system described. (Item 18) The system further comprises a heat source for heating the polymer material prior to delivery to the reservoir or while in the reservoir, according to any one of items 1 - 15 of the system described. (Item 19) The system is configured for co-deposition of fibers, and the system is a second reservoir configured to hold a second material containing a second polymer, the second reservoir is rotatable about a second axis of rotation, and the second reservoir has a first end, a second end opposite the first end, and an outer sidewall extending from the first end to the second end, the shape of the second reservoir includes one or more openings disposed radially inward from the outer sidewall of the reservoir, the one or more openings are configured to allow gas to move through the reservoir from the first end to the second end, an outer sidewall, and one or more orifices formed within the outer sidewall and includes Each of the one or more orifices is configured for the radially outward injection of the second polymer material through the orifice as a second ejected jet of the second reservoir, the second reservoir a second plurality of gas flow sources, further comprising, Each of the second plurality of gas flow sources is configured to direct the flow of gas from upstream of the first end of the second reservoir through one or more openings of the second reservoir from the first end to the second end of the second reservoir during rotation of the second reservoir downstream of the second end of the second reservoir, the plurality of gas flow sources having a converging orientation such that the flow from the plurality of gas flow sources collectively forms a second combined gas flow in a second direction downstream of the second end of the second reservoir, the second combined gas flow taking in and deflecting the second ejected jet to form a second converging flow of one or more second micron or nanometer sized polymer fibers in the second direction, the second direction having an orientation within 5 degrees of the axis of rotation of the second axis of rotation, The system according to any one of items 1-18, wherein the first direction and the second direction are directed for deposition on the same collection surface. (Item 20) The system according to item 19, wherein the system is configured for simultaneous deposition of one or more fibers of the first polymer and one or more fibers of the second polymer on the same collection surface. (Item 21) A method for forming and depositing at least one micron or nanometer sized polymer fiber, the method comprising: rotating a reservoir holding a material comprising a polymer about an axis of rotation and ejecting at least one ejection of the material from at least one orifice defined by an outer sidewall of the reservoir; Directing at least one flow of gas through a portion of the reservoir that is radially inward of the outer sidewall, wherein at least one flow of gas is directed from a first end upstream of the reservoir to a second end downstream of the reservoir during rotation of the reservoir and during injection of the at least one injection of the material, forming at least one polymer fiber of micron or nanometer dimension, wherein at least one flow of gas entrains the at least one polymer fiber of micron or nanometer dimension and forms a focused fiber deposition flow of the at least one polymer fiber of micron or nanometer dimension in a first direction, and the first direction has an orientation within 5 degrees of the axis of rotation of the reservoir, and collecting the focused fiber deposition flow on a target surface A method comprising. (Item 22) The method according to item 21, wherein the first direction is substantially parallel to the axis of rotation of the reservoir. (Item 23) The method according to item 21 or item 22, wherein at least one flow of gas comprises a plurality of flows of gas that converge to form a combined gas flow in the first direction. (Item 24) The method according to item 23, wherein the flow rate of at least a portion of the plurality of converging gas flows relative to the other of the plurality of converging gas flows is controllable to achieve a balanced combined gas flow. (Item 25) The method according to item 23 or item 24, wherein the total gas flow rate of the plurality of converging gas flows is controllable to vary the distance from the reservoir at which the focused fiber deposition flow of the at least one polymer fiber of micron or nanometer dimension has the tightest focus. (Item 26) The method according to any one of items 23-25, wherein the plurality of gas flows comprises three gas flows. (Item 27) The method according to any one of items 21-26, wherein the focused fiber deposition flow has a substantially tangential orientation with respect to the target surface during fiber collection. (Item 28) The method according to any one of items 21-26, further comprising rotating the target surface during fiber collection. (Item 29) A method of forming a three-dimensional tissue scaffold comprising performing the method according to any one of items 21-28, wherein the target surface is a three-dimensional shape for the tissue scaffold. (Item 30) The method for forming a three-dimensional tissue scaffold according to item 29, further comprising rotating the target for deposition on two or more sides of the three-dimensional shape. (Item 31) The method according to any one of items 21 - 30, further comprising at least partially blocking the flow of gas from upstream of the reservoir and reducing the influence of the air flow upstream of the plurality of gas flow sources on the focusing of the fiber deposition flow of the at least one micron or nanometer-sized polymer fiber. (Item 32) The method according to any one of items 21 - 31, wherein the target surface is linearly moved during the deposition of the fibers. (Item 33) The method according to any one of items 21 - 32, wherein the material in the reservoir comprises a solvent. (Item 34) The method according to any one of items 21 - 32, wherein the material in the reservoir comprises a polymer melt. (Item 35) The method according to item 34, further comprising heating the reservoir. (Item 36) The method according to any one of items 21 - 32, wherein the at least one injected jet contacts a tank prior to being collected on the target surface. (Item 37) The method according to item 36, wherein the tank comprises a cross-linking agent. (Item 38) The method according to item 36, wherein the at least one injected jet precipitates in the tank to form the at least one micron or nanometer-sized polymer fiber. (Item 39) The method according to item 36, wherein the at least one injected jet solidifies in the tank to form the at least one micron or nanometer-sized polymer fiber. (Item 40) The method according to any one of items 21 - 31, wherein the at least one micron or nanometer-sized polymer fiber is deposited for reinforcement of a composite material. (Item 41) The method according to any one of items 21 - 31, wherein the at least one micron or nanometer-sized polymer fiber is deposited on one or more items of food. (Item 42) Rotating a second reservoir holding a second material comprising a second polymer about a second axis of rotation and ejecting at least one jet of the second material from at least one orifice defined by an outer sidewall of the second reservoir. Directing at least one second flow of gas through a portion of the second reservoir that is radially inward of the outer sidewall, wherein the at least one second flow of gas is directed from a first end upstream of the second reservoir to a second end downstream of the second reservoir during rotation of the second reservoir and during ejection of at least one injection of the second material, forming at least one micron or nanometer-sized polymer fiber of the second polymer, and the at least one second flow of gas entrains at least one micron or nanometer-sized polymer fiber of the second polymer to form a second focused fiber deposition flow; Collecting the second focused fiber deposition flow on a target surface; The method of claim 21, further comprising. (Item 43) The method of claim 42, wherein the collecting of the first focused fiber deposition flow overlaps in time with the collecting of the second focused fiber deposition flow.

Brief Description of the Drawings

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[0036] In the following description, it should be understood that terms such as "upper", "lower", "middle", "outward", "inward", etc. are for convenience only and are not to be construed as limiting terms. Here, the embodiments of the present disclosure illustrated in the accompanying figures and examples will be referred to in detail. In general, it should be understood that referring to the drawings is for the purpose of illustrating specific embodiments of the present disclosure and is not intended to limit it.

[0037] When certain embodiments of the present disclosure are described as comprising, or consisting of, at least one element of a group and combinations thereof, it is to be understood that the embodiments can comprise, or consist of, any one of the elements of the group, individually or in combination with any of the other elements of the group.

[0038] As used herein, the terms “polymer fiber” and “macromolecular fiber” refer to fibers comprising a polymer. The fibers can also include some non-polymer components.

[0039] As used herein, fibers having micron or nanometer dimensions refer to fibers having a diameter of less than about 10 μm.

[0040] These and other aspects of the invention will be better recognized and understood when considered in conjunction with the following description and the accompanying drawings. The following description shows various embodiments of the invention and numerous specific details thereof, given by way of illustration and not limitation. Many substitutions, modifications, additions, or rearrangements can be made within the scope of the invention, and the invention includes all such substitutions, modifications, additions, or rearrangements.

[0041] Some embodiments described herein include methods and systems for forming polymer fibers from micron-scale diameters to nanometer-scale diameters by injection of a fiber-forming liquid from a spinning reservoir, which employ a gas (e.g., air) flow to focus and align the fibers produced in the fiber stream for controlled deposition. In some embodiments, the throughput of microfiber production in terms of fiber length per unit time is at least 80 km / min. In some embodiments, the throughput of microfiber production is in the range of 1 m / min to 150 km / min. In some embodiments, the throughput of microfiber production is in the range of 100 m / min to 150 km / min. In some embodiments, the throughput of microfiber production is in the range of 1 km / min to 150 km / min. In some embodiments, the throughput of microfiber production is in the range of 80 km / min to 150 km / min. In some embodiments, the throughput of microfiber production is in the range of 80 km / min to 100 km / min. In some embodiments, the fibers to be deposited conform to various 3D geometries using control of fiber alignment.

[0042] Some conventional high-throughput approaches have attempted to deposit on 3D-shaped targets to achieve 3D fibrous structures; however, the fibers often do not conform to the target shape and often exhibit overhanging fibers. Some conventional approaches have employed rotation of the target to achieve circumferential fiber alignment; however, this method cannot handle more complex alignments (such as helical alignment in the ventricles or 3-layer structures in heart valves with circumferential and longitudinal alignment on different layers) observed in actual tissues.

[0043] In some embodiments, the systems and methods have improved structural controllability with respect to fibers in the micron to nanometer scale diameter as compared to conventional high throughput fiber deposition techniques. Some embodiments of the systems and methods described herein employ flow fiber deposition (flow FD), where the fibers are spatially confined and structured into an aligned fiber flow before being deposited onto a target. A well-structured fiber flow enables a well-structured deposition. Flow FD enables precise control over both conformity and deposition alignment without sacrificing throughput.

[0044] Fibers are formed through an electrospinning process by ejection of one or more jets of a fiber-forming liquid (e.g., a material comprising a polymer, referred to herein as a polymer material) from one or more orifices of a rotating reservoir under centrifugal force, followed by subsequent solidification. The reservoir containing the one or more orifices may be referred to herein as a spinneret. In the embodiments described herein, certain aerodynamics of a gas flow (e.g., an air flow) are employed to confine the generated fiber distribution and align it in the fiber flow. Confining the fiber distribution requires a converging air flow that brings the fibers together as they flow away from the reservoir. Aligning the fibers requires an accelerating air flow that pulls the fibers in a straight line. Additionally, perturbations to the flow near the reservoir (e.g., the spinneret) should be minimized to avoid interfering with fiber formation. In some embodiments, these requirements may be achieved by blowing a gas (e.g., air) from or near the axis of rotation of the reservoir.

[0045] Figure 2A schematically depicts an exemplary rotary jet spinning system 10 that includes a rotary motion generator (e.g., a motor) 11 for rotating a reservoir 12 (referred to herein as a spinneret) that includes an orifice, according to some embodiments. The system employs a gas stream (e.g., an air stream) 30 to converge and align a stream of fibers 15 produced by ejecting a polymer solution 17 from the spinneret 12 before the fibers are deposited on a target 19. In some embodiments, the gas stream can be a gas injection or an air injection located on or near the axis 21 of rotation of the spinneret / reservoir 12 and can direct a flow that is parallel or substantially parallel to the axis 21 of rotation. The gas stream is not a uniform flow across the area of the rotor. In some embodiments, the flow is concentrated in one or more central portions of the rotor that are radially inwardly spaced from the sidewalls of the rotor. In some embodiments, downstream of the rotor, the air stream has a higher speed on or near the axis of rotation of the rotor, which decreases at locations displaced laterally from the axis of rotation.

[0046] Rotary jet spinning produces fibers or a plurality of fibers by centrifugal force and thus generates a fiber mass surrounding the spinneret 12, which moves azimuthally and radially outwardly. As the gas stream (e.g., an air injection) 30 is extruded from one or more central portions of the spinneret, the gas stream 30 draws ambient air into the injection in a phenomenon known as entrainment. The entrainment flow is orders of magnitude slower than the flow inside the injection and has little perturbation to fiber formation. Entrainment converges and accelerates toward the injection, which confines and aligns the fibers within the flow, as shown in the visualization of the fiber flow of Figure 2B produced by overlaying different frames from a video of fiber deposition.

[0047] Additional details of several embodiments of a rotary jet spinning system and method are described below with respect to FIGS. 3A-G. In the embodiments of FIGS. 3A-G, the system employs a plurality of gas streams that are combined to form a combined gas stream for converging and aligning a fiber stream. Further, in accordance with some embodiments, the plurality of gas streams flow through an opening in a reservoir radially inward of one or more orifices before forming the combined flow.

[0048] Referring to FIGS. 3A-G, an embodiment of a rotary jet spinning system 10 includes at least one reservoir 12 configured to rotate about a rotational axis 21. Some systems may also include a rotational motion generator (e.g., a motor) 11 that rotates the reservoir.

[0049] In some embodiments, reservoir 12 has a first end 14, a second end 16 opposite the first end 14, and an outer sidewall 18 extending from the first end 14 to the second end 16. Reservoir 12 is configured and adapted to hold a material (e.g., a polymer material) for forming polymer fibers. Reservoir 12 defines one or more orifices 22 within outer sidewall 18. Reservoir 12 is configured and adapted to radially outwardly inject the polymer material through one or more orifices 22 formed within outer sidewall 18 under pressure caused by the rotation of reservoir 12. Each of the one or more orifices 22 may be configured for the radially outward injection of the polymer material through orifice 22 as an ejected jet 24 during rotation of reservoir 12.

[0050] In some embodiments, the reservoir defines one or more openings 20a, 20b, 20c disposed radially inwardly from an outer sidewall 18 configured to allow gas to move from a first end 14 to a second end 16 past or through the reservoir 12. In some embodiments, the reservoir 12 may define three openings 20a, 20b, 20c disposed radially inwardly from the outer sidewall 18. In other embodiments, the reservoir 12 may define more than three openings disposed radially inwardly from the outer sidewall 18. In some embodiments, the reservoir may define two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, or nineteen openings disposed radially inwardly from the outer sidewall 18. Those skilled in the art will recognize, from the perspective of the present disclosure, that openings of different geometries and different numbers of openings are within the scope of the present invention.

[0051] According to some embodiments, the rotary jet spinning system 10 further includes one or more gas flow sources 28a, 28b, 28c used to form a gas flow (also referred to herein as a gas jet (e.g., an air jet)) to converge and align the fiber stream. In some embodiments, the rotary jet spinning system 10 includes a plurality of gas flow sources 28a, 28b, 28c each configured to direct the flow of gas from upstream of the first end 14 of the reservoir 12, through the openings 20a, 20b, 20c from the first end 14 to the second end 16, downstream of the second end 16 of the reservoir 12. In some embodiments, the plurality of gas flow sources 28a, 28b, 28c have a converging orientation such that the flows from the plurality of gas flow sources collectively form a combined gas flow or gas jet 30 in a first direction downstream of the second end 16 of the reservoir 12. In some embodiments, the first method is substantially parallel to the axis of rotation 21. FIG. 3F includes arrows showing the gas flows 30a, 30b, 30c from the plurality of gas flow sources 28a, 28b, 28c and the combined gas flow 30 aligned with the axis of rotation 21. As shown in FIG. 3F, the gas flows 30a, 30b, 30c directed from the gas flow sources 28a, 28b, 28c converge at a location downstream of the second end 16 of the reservoir 12 to form a combined gas flow 30. In some embodiments, the gas flow sources 28a, 28b, 28c can converge to form a combined gas flow within a range of 2 centimeters to 10 cm downstream of the second end 16 of the reservoir 12. In some embodiments, the flow from the gas flow source can converge more than 10 cm from the second end 16 of the reservoir. The combined gas flow 30 can capture the ejected jet 24 and form a converging stream of polymeric fibers 32 in the first direction having micron or nanometer dimensions. By way of non-limiting example, the plurality of gas flow sources can converge and homogenize at a distance of about 3 centimeters downstream of the second end 16 of the reservoir 12. At such a distance, the air flow rate can be, in some embodiments, from about 10 m / sec to about 30 m / sec.

[0052] In some embodiments, the first direction can be at an angle with respect to the axis of rotation 21. In some embodiments, the first direction can be within 5 degrees of the longitudinal axis A1. In some embodiments, the first direction can be within 3 degrees of the longitudinal axis A1. In some embodiments, the first direction has an angle within the range of zero to 5 with respect to the axis of rotation 21.

[0053] As described above, in some embodiments, the rotary jet spinning system 10 can include a gas flow system including one or more gas flow sources (e.g., nozzles) 28a, 28b, 28c. The one or more gas flow sources 28a, 28b, 28c can be supplied with gas flow independently, or all of them can receive gas flow from a common supply source before it is divided among the one or more gas flow sources 28, 28b, 28c. In some embodiments, the one or more gas flow sources can be part of a single gas flow unit or fixture 26, as illustrated in FIGS. 3A, 3D, and 3G.

[0054] During operation, the gas flow or gas jet 30, which can be a combined gas flow, entrains and deflects the ejected flow to form a converging flow of polymer fibers in the micron or nanometer dimension in the first direction. The gas flow through the axis of rotation or a reservoir near it does not interfere with fiber formation. FIGS. 4A and 4B show a turbulent flow model simulation of the flow field around the spinneret 12 with an applied central air jet 30 from the central portion of the spinneret or reservoir. Even with a substantial air jet, the presence of the central air jet causes little perturbation in the flow field in the fiber formation region 41, either axially (FIG. 4A) or radially (FIG. 4B), and thus does not interfere with fiber formation. In contrast, when the reservoir is exposed to a uniform external air flow parallel to the axis of rotation instead of an external air flow from outside through the central portion of the reservoir, the uniform external air flow interferes with fiber formation in the fiber formation region 41 and can cause fiber entanglement.

[0055] In some embodiments, the reservoir 12 can begin to rotate without a gas flow (e.g., an air flow) being applied. The gas flow (e.g., an air flow) can be gradually increased until a focus of the flow of polymer fibers of micron or nanometer dimensions is achieved. FIG. 2B illustrates a converging flow of fibers and shows the narrow width W 最小 of the narrowest flow. In some embodiments, the narrow width of the fiber flow can be located at a distance of 3 cm to 7 cm from the orifice of the reservoir as measured along the axis of rotation. If the flow rate is too low, the fibers may not be able to align or may not be able to align properly. A higher flow rate will allow for alignment and collection of the fibers at a greater distance from the reservoir 12. Collection of the fibers at a greater distance from the reservoir 12 can be beneficial to ensure drying of the fibers and / or to allow the fibers to be distributed over a larger area / to be deposited over a larger target, however, as the distance from the reservoir increases, the fiber flow will spread, the fibers will decelerate and may warp. In some embodiments, the fibers are deposited on the surface of the collector or target at a distance of 2 cm to 20 cm from the orifice as measured along the axis of rotation. In some embodiments, the fibers are deposited on the surface of the collector or target at a distance of 3 cm to 20 cm from the orifice as measured along the axis of rotation. In some embodiments, the fibers are deposited on the surface of the collector or target at a distance of 4 cm to 20 cm from the orifice as measured along the axis of rotation. In some embodiments, the fibers are deposited on the surface of the collector in the range of 3 cm to 50 cm from the orifice as measured along the axis of rotation.

[0056] In some embodiments, the arrangement of the plurality of gas flow sources may be configured such that at any single point in time during rotation of the reservoir, the gas flow from all of the gas flow sources flows through the openings of the reservoir, or the gas flow from all of the gas flow sources is blocked by the reservoir. In this manner, the combined gas flow will not be deflected from the intended direction by having only a portion of the gas flow blocked at a given time, resulting in an unbalanced combined gas flow. For example, the gas flow source arrangement and reservoir in the system of FIGS. 3A-F are configured such that at any point in time, the gas flow from all three gas flow sources 28a, 28b, 28c either flows through the openings 20a, 20b, 20c of the reservoir 12, or the gas flow from all three gas flow sources 28a, 28b, 28c is substantially blocked by the portion of the reservoir 12 between the openings 20a, 20b, 20c. In other embodiments, a sufficient number of gas flows may be present such that the combined flow may be balanced even when a portion of the gas flow is blocked. For example, with respect to an embodiment with six gas flows symmetrically arranged around the axis of rotation and three openings in a reservoir symmetrically arranged around the axis of rotation, at a given point in the rotation of the reservoir, all of the other gas flows will be blocked, but the combined gas flow may still be balanced.

[0057] In some embodiments, the gas flow sources 28a, 28b, 28c may be controllable to achieve a balanced combined gas flow. For example, the flow rate through the gas flow source may be adjustable, or the direction or orientation of the flow from the gas flow source may be adjustable. In some embodiments, the gas flow sources 28a, 28b, 28c may be controllable to vary the distance from the reservoir 12 having the tightest focus (also referred to herein as the narrow portion of the flow) of the flow of the polymer fibers 32 of micron or nanometer dimensions, or the distance from the orifice (see FIG. 2B). In some embodiments, the distance along the first direction between the orifice and the narrow portion of the flow may range from about 3 cm to about 7 cm. In other embodiments, the distance may be shorter or longer than this range. In some embodiments, the gas flow rate may be adjustable. In some embodiments, during fiber formation and deposition, the gas pressure may be within the range of about 0.1 MPa to about 0.5 MPa.

[0058] In some embodiments, the rotary jet spinning system 10 may include a flow blocking device 34 positioned upstream of the first end 12 of the reservoir 12 (see FIGS. 3A, 3B, and 3E). The flow blocking device 34 provides additional control of the vortex generated by the gas flow and the rotation of the reservoir 12, thereby improving the control of the side area of the deposition of the polymer fibers of micron or nanometer dimensions as the fibers travel towards the target.

[0059] In some embodiments, the flow blocking device 34, which may also be referred to herein as a flow conditioner, can be used to achieve a longer collection distance by preventing stronger airflows from overly perturbing fiber formation near the reservoir 12. As described above, the flow blocking device 34 can be positioned upstream of the first end 14 of the reservoir 12. In some embodiments, the flow blocking device 34 can be positioned at a distance of about 2 cm to about 10 cm upstream of the first end 14 of the reservoir 12. In some embodiments, the flow blocking device is positioned about 5 cm upstream of the first end 14 of the reservoir. In some embodiments, the flow blocking device 34 is stationary and does not rotate. In other embodiments, the flow blocking device 34 can be configured to rotate with or separate from the reservoir. The flow blocking device 34 has a diameter equal to or greater than that of the reservoir 12 according to some embodiments. For example, in some embodiments, the flow blocking device 34 has a diameter in the range of about 1 to about 5 times the diameter of the reservoir 12. In other embodiments, the flow blocking device can have a larger diameter. The diameter of the flow blocking device 34 can be selected based in part on the location of the flow blocking device 34 relative to the reservoir 12. For example, a larger flow blocking device 34 installed further from the reservoir 12 can have a similar effect as a smaller flow blocking device 34 installed closer to the reservoir 12. In some embodiments, the flow blocking device may not be required for deposition on the collector relatively close to the reservoir, but the flow blocking device can be required for collection at distances further from the reservoir (e.g., at distances greater than 20 cm from the reservoir, at distances greater than 30 cm from the reservoir, or at distances greater than 50 cm from the reservoir).

[0060] Figure 5A schematically depicts the streamlines of the gas flow around the system and the influence of the flow interruption device 34 on the gas flow. The gas flow is governed by the radial and azimuthal gas flows caused by the rotation of the reservoir and the externally applied gas through the central portion of the reservoir. Within the circulation region, vortices are generated due to the competition between the centripetal flow from the rapidly rotating reservoir and the entrainment flow of the air jet blown from the center of the reservoir. The external flow in the drive region also captures the gas flow from upstream of the reservoir and the flow interruption device across the circulation region, which flows within the following region. The flow interruption device 34 can modify (e.g., interrupt) at least a portion of the air flow from upstream of the reservoir and affect the size and shape of the vortices within the circulation region.

[0061] Figure 5B schematically depicts the polymer jet 24 (the polymer jet 24 is subject to the centrifugal force resulting from the ejection from the reservoir in the absence of an external air flow) under the influence of the flow in the centrifugal region, and the resulting fiber 15 (the fiber 15 is captured by the external air flow 30 and is under tension) in the tension region. In this schematic diagram, the one or more gas flow sources used to generate the external air flow 30 are not shown for simplicity.

[0062] Figure 5C schematically depicts an axial view of the reservoir and illustrates the various forces acting on the ejected jet of polymer material from the reservoir during the fiber formation process.

[0063] Figures 6A - 6C and 7A - 7C illustrate the effect of the flow interruption device according to some embodiments. By way of non - limiting example, FIGS. 6A - 6C correspond to the generation of fibers by the rotary jet spinning system 10 for flow fiber deposition without the flow interruption device 34. In contrast, FIGS. 7A - 7C correspond to the generation of fibers by the rotary jet spinning system 10 for flow fiber deposition including the flow interruption device 34 here. The background - subtracted image during fiber deposition in FIG. 7A shows less turbulence downstream of the reservoir 12 due to the use of the flow interruption device 34 compared to the background - subtracted image in FIG. 6A where the flow interruption device was not employed. In some embodiments, the flow interruption device 34 provides additional control of the gas flow and the vortices generated by the rotation of the reservoir 12, thereby improving the control of the lateral area of the polymer fiber deposition as the fibers travel towards the target. The fibers extend further before being focused into the flow using the flow interruption device shown in FIG. 7B. The flow interruption device 34 suppresses the drag region and leads to a better fiber morphology. The SEM images in FIGS. 6C and 7C compare the resulting fiber morphologies. The images illustrate a more uniform fiber diameter and reduced fiber curling for the fibers generated using the flow interruption device. The samples were collected 20 cm downstream from the reservoir.

[0064] Some embodiments of the system are described herein as including a flow interruption device, but the systems and methods described herein do not necessarily require, incorporate, or employ a flow interruption device or flow regulator upstream of the reservoir. In some embodiments, fiber morphology, distribution, and fiber alignment in the deposition may be acceptable without the use of a flow interruption device. As noted above, in some embodiments, whether a flow interruption device is required or employed may be determined at least in part by the distance between the reservoir and the surface on which the fibers are collected.

[0065] Some embodiments are described herein as having multiple gas streams that converge into a single gas stream that entrains fibers and converges and focuses the gas flow, but in other embodiments, a single gas stream directed along the axis of rotation of the reservoir may be employed.

[0066] With respect to some of the systems and methods described herein, after the central gas stream converges the fiber stream until it reaches the narrow section, the fiber stream then spreads in proportion to the distance from the reservoir as would be predicted for a turbulent jet spread. FIG. 8A is a wide-field image formed from multiple overlaid images of the fiber stream, showing this spread r of the fiber stream with distance x from the reservoir. stream is illustrated. FIG. 8B is a plot of the thickness profile for collection at different distances from the reservoir. The thickness profile shows self-similar scaling at r stream ~0.1x, which is similar to the self-similar scaling of the velocity profile for the turbulent spread of an injection stream. Thus, downstream of the narrow section of the flow, the flow width increases in proportion to the distance of the collection target surface from the reservoir.

[0067] In some embodiments, a system for rotary jet spinning using fluid fiber deposition is configured for conformal deposition onto 3D features. Containment of the fiber stream is important for conformal deposition onto 3D features. From a length scale perspective, as schematically illustrated in FIG. 9A, containment is characterized by the fiber stream width w, and the target 3D feature for deposition is characterized by the local radius of curvature ρ. Since the fiber stream is generated from a random fiber population and is constantly perturbed by turbulent fluctuations, the fiber trajectories undulate within the stream. As schematically depicted in FIG. 9B, when the fiber stream width is much less than the curvature of the target surface, w << ρ, the target surface is effectively flat with respect to the fiber stream, and deposition conforms to the target surface. When the fiber stream width is comparable to or less than the curvature of the target surface, w ~ ρ or w >> ρ, the curvature has a significant effect on deposition. When the target surface is convex, the fibers wrap around the target and still result in conformal deposition. However, as illustrated in FIG. 9C, when the surface is concave, the fibers cross the concave portion and result in non-conformal deposition. In practice, the width of the fiber stream is determined by the width of the central gas stream, which may correspond to the spinneret diameter and increases linearly with the collection distance. The effect of the stream width compared to the feature size of the target was illustrated by deposition onto two targets, namely a 50 cm tall female mannequin and a 15 cm tall Buddha face replicated from a 5th century statue from Qingzhou, China, using a fixed stream width of about 6 cm. For larger feature sizes where the stream width was approximately the same size as the feature size on the target, the deposition conformed well to the body features of the female mannequin (see FIG. 9D). For relatively smaller feature sizes where the stream width was larger than the feature size on the target, the deposition hardly resolved any of the facial features on the Buddha face (see FIG. 9E). After embossing, the details of the facial features on the Buddha face are revealed (see FIG. 9F). The scale bar on FIGS. 9D - 9F is about 6 cm.

[0068] Theoretically, the spinning settings can be scaled down to achieve a smaller flow width for finer feature resolution. In practice, a smaller flow width typically requires a trade-off between throughput and fiber quality. Since turbulent fluctuations constantly perturb the fibers in the fiber stream, the chance of the fibers colliding and bunching increases as the fiber density inside the stream increases. As a result, maintaining the same throughput while decreasing the flow width leads to poorer fiber quality because this requires a higher fiber density. Alternatively, keeping the fiber density the same for a smaller flow leads to lower throughput. For targets such as a mask where fine features only appear as shallow undulations on coarser features, high-throughput deposition that captures large-scale features and continues with embossing can be employed (see FIG. 9F).

[0069] In some embodiments, the alignment of fibers in the fiber stream enables the system and method to control the alignment of deposition by varying the deposition angle. When the fiber stream impacts the target surface in a tangential direction, as depicted schematically in the upper image of FIG. 10A, the flow field of the air jet is hardly perturbed by the target, and the fibers fall onto the target surface as they vary in the flow, preserving their alignment in the flow. The scanning electron microscope photograph (lower left) and the corresponding Fourier transform (lower right) image of FIG. 10A of the fibers deposited using this deposition angle confirm the fiber alignment in the flow. When the flow impacts the target surface in a perpendicular direction, as depicted in the upper image of FIG. 10C, the air jet hits the target and forms a divergent decelerating flow field, opposite to the converging accelerating field used to form the flow. As a result, the fibers are distorted and spread into random groups, resulting in a random deposition with little or no alignment, as shown by the scanning electron microscope photograph (lower left) and the corresponding Fourier transform (lower right) image of FIG. 10C of the fibers deposited using this deposition angle. Using an intermediate angle of incidence leads to a partially aligned deposition as shown in FIG. 10B. In the SEM images, the scale bar is 20 μm. Various alignment patterns are possible in some embodiments by moving the target relative to the flow. For example, collection on a rotating disk produces a fiber sheet with rotational alignment through the thickness as illustrated by FIG. 9D. Collection on a rotating cylinder produces a helical alignment as illustrated by FIGS. 10E and 10F. In some embodiments, a combination of deposition angle control and target rotation control can be employed to create more complex fiber alignment patterns.

[0070] In some embodiments, the rotary jet spinning system may also include a second reservoir configured to hold a second polymer material that may be different from the first polymer material. In some embodiments, the rotary jet spinning system may also include one or more second gas flow sources, and the second reservoir and the one or more second gas flow sources are configured such that the gas flow through the reservoir forms a gas flow downstream of the reservoir along a second direction that may be substantially parallel to the axis of rotation of the second reservoir or at an angle to the axis of rotation of the second reservoir. The gas flow may entrain and deflect the fibers to form a second fiber stream in the second direction. In some embodiments, the first reservoir and the second reservoir are oriented such that they can both deposit fibers on the same target surface simultaneously. All of the features and aspects described herein with respect to reservoir 12 are also applicable to the second reservoir, and all of the features and aspects described herein with respect to one or more gas flow sources are also applicable to the one or more second gas flow sources.

[0071] In some embodiments, the polymer material is a polymer solution, and the polymer fibers are formed by evaporation of the solvent from the polymer solution. In some embodiments, the polymer material is a polymer melt, and the polymer fibers are formed by solidification due at least in part to cooling. Additional details regarding the rotary spinning system, such as the reservoir, spinning speed, orifice diameter, polymers, polymer solutions, and other polymer materials such as polymer melts, can be found in U.S. Patent No. 2013 / 0312638, which is incorporated herein by reference in its entirety.

[0072] In some embodiments, the rotary jet spinning system 10b for melt deposition may employ a polymeric material that requires crosslinking, precipitation, or coagulation for fiber formation. In some such embodiments, a rotating target 102 that is at least partially immersed within a precipitation, coagulation, or crosslinking bath 104 may be exposed to the flow of the polymeric material (see FIG. 11A). Additional details regarding precipitation, coagulation, or crosslinking baths, and wet rotary jet spinning systems and methods, may be found in U.S. Patent Publication No. 2015 / 0354094, the entire contents of which are incorporated herein by reference.

[0073] In some embodiments, the polymeric material may include a polymer melt, and the system 10b may include a heater 204 (e.g., a syringe heater) for heating the polymeric material prior to delivery to a reservoir (see FIG. 11B). The system 10b may additionally or alternatively include a reservoir heater 204 for heating the polymeric material while the polymeric material is within the reservoir. As depicted in FIG. 11B, the reservoir heater may be, in some embodiments, an infrared spot heater.

[0074] In some embodiments, the rotary jet spinning system 10c for melt fiber deposition may be configured as a hand-held device, as depicted in FIG. 11C.

[0075] In some embodiments, the system 10d may include a plurality of rotary jet spinning systems for fiber deposition that can deposit fibers onto a target being linearly transported, such as on a conveyor belt 302, as shown in FIG. 11D. In some embodiments, the system or the plurality of rotary jet spinning systems may be adapted for use in a production line.

[0076] In some embodiments, the system is configured for the deposition of fibers having an average diameter of less than 10 μm. In some embodiments, the system is configured for the deposition of fibers having an average diameter of less than 5 μm. In some embodiments, the system is configured for the deposition of fibers having an average diameter of less than 3 μm. In some embodiments, the system is configured for the deposition of fibers having an average diameter of less than 2 μm.

[0077] Embodiments include a method of depositing fibers of micron or nanometer dimensions on a surface of a target. Some embodiments of the method are described herein with respect to system 10 depicted in FIGS. 3A - 3G for illustrative purposes only; however, one of ordinary skill in the art will recognize from the perspective of the present disclosure that other systems may also be employed with the methods described herein. In some embodiments, the method includes rotating a reservoir 12 having an outer sidewall 18 and at least one orifice 22 about a rotation axis 21 and ejecting an injection 24 of a polymer material from the at least one orifice 22, which solidifies to form polymer fibers 15. During rotation of the reservoir 12 and ejection of the polymer material injection 24 for forming polymer fibers, at least one flow of gas, e.g., flow 30a, flow 30b, flow 30c, or flow 30, is directed from the upstream end 14 of the reservoir to the downstream end 16 of the reservoir through a radially inner portion of the reservoir from the outer sidewall 18 of the reservoir, and at least one flow of gas 30 is used to entrain the polymer fibers 24 to form a focused fiber deposition stream. The focused fiber deposition stream is collected on the target surface to form a polymeric fiber material. In some embodiments, the focused fiber deposition stream flows in a first direction that is substantially parallel to the rotation axis of the reservoir. In some embodiments, the orientation of the first direction is within 20 degrees, within 10 degrees, or within 5 degrees of the rotation axis of the reservoir. In some embodiments, at least one flow of gas is a plurality of flows of gas 30a, 30b, 30c that converge and combine to form a combined gas flow 30 in the first direction (see FIG. 3F). In some embodiments, the reservoir includes at least one opening 20a, 20b, 20c radially inner of the sidewall that allows at least one flow of gas to flow through the reservoir.

[0078] In some embodiments, the deposited fibers have an average diameter of less than 10 μm. In some embodiments, the deposited fibers have an average diameter of less than 5 μm. In some embodiments, the deposited fibers have an average diameter of less than 3 μm. In some embodiments, the deposited fibers have an average diameter of less than 2 μm.

[0079] The systems and methods described herein can be employed for many different uses and purposes. For example, by way of non-limiting list, the systems and methods can be employed for the generation of composite materials, for tissue engineering design (e.g., for cell or tissue scaffolds), or for clothing design. Some embodiments are particularly suitable for the formation of structures having complex three-dimensional shapes and / or complex fiber alignments. The ability to control both the 3D shape and alignment of fiber deposition can affect various fields involving structured fibrous materials such as fashion design, composite materials, and tissue engineering design.

[0080] (Example - Engineered Ventricle) A tissue scaffold for an engineered ventricle was generated to demonstrate the capabilities of some embodiments described herein. The ventricle is one of two heart chambers involved in blood pumping. The ventricle is made from a layer of highly aligned cardiomyocytes that wrap in a helical pattern. The helical angle rotates from 45° to -45° through the thickness of the ventricle wall. The complex helical arrangement of cardiomyocytes is supported by a fibrous extracellular matrix (ECM), which consists primarily of hierarchical collagen fibers whose diameters range from tens of nanometers to several microns. Reconstructing this fibrous ECM is considered an important challenge in cardiac tissue engineering. Conventional efforts to reconstruct the fibrous ECM of the ventricle have included a number of efforts, including tissue decellularization, random fiber deposition, and 3D printing. However, these efforts are still limited by a trade-off between fine fibers, complex structures, and high processing capabilities.

[0081] A 4-step spinning procedure was employed to replicate a simplified three-layer helical biventricular model as depicted schematically in Fig. 12A. The fiber diameter was selected to be on the order of several microns, similar to the diameter of the subendocardial fibers in the cardiac ECM. In step 1, the fiber stream was deposited onto a rotating mandrel shaped like the left ventricle, with the mandrel at an angle of 45 degrees to the deposition stream. In step 2, the fiber stream was deposited onto a rotating left ventricle mandrel that was perpendicular to the fiber stream. In step 3, the fibers were deposited onto a rotating mandrel shaped like the right ventricle, with the right ventricle mandrel at an angle of 45 degrees to the deposition stream. In step 4, the left ventricle mandrel and the right ventricle mandrel were positioned together to form a combined mandrel, and the fibers were deposited at an angle of -45 degrees to the fiber stream across the rotating combined mandrel and across the previously deposited layers of fibers.

[0082] The realization of these design features was verified by direct measurement or by micro-CT imaging. Fig. 12B is an image of the combined mandrel with the previously deposited fiber layer, and Fig. 12C is an image of the combined mandrel after deposition of the fiber layer at an angle of -45 degrees to the fiber stream.

[0083] Fig. 12C is a micro-CT image of a section of the resulting deposited fiber structure. Fig. 12D is a micro-CT image of the septal region between the two ventricles showing various helical angles. Fig. 12E is a detail of the image of the septal region, similarly showing various helical angles.

[0084] Throughout this specification and the claims, approximating language, as used herein, may be applied to modify any quantitative or qualitative expression that can vary within a tolerance without resulting in a change in the basic function to which it is related. Accordingly, values modified by terms such as "about" or by a numerical range are not limited to the precise values specified, but may include values different from those specified. In at least some instances, approximating language may correspond to the precision of the instrument for measuring the value.

[0085] Although the present disclosure has been described in detail in connection with only a limited number of aspects and embodiments, it should be understood that the present disclosure is not limited to such aspects. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements that do not appear in the foregoing description but are within the scope of the claims. Additionally, although various embodiments of the present disclosure have been described, it should be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be regarded as limited by the foregoing description, but is limited only by the scope of the appended claims.

Claims

1. A system for the focused directional deposition of one or more polymer fibers of micron or nanometer dimensions, said system comprising: A reservoir configured to hold a material containing a polymer, said reservoir being rotatable about a rotation axis, Said reservoir comprising: A first end, A second end opposite said first end, An outer sidewall extending from said first end to said second end, said reservoir having a shape including one or more openings disposed radially inwardly from said outer sidewall of said reservoir, said one or more openings being configured to allow gas to move through said reservoir from said first end to said second end, an outer sidewall; One or more orifices formed within said outer sidewall, each of said one or more orifices being configured for the radially outward injection of said material through said orifice as an injected jet during rotation of said reservoir, one or more orifices; A reservoir including; A plurality of gas flow sources, each of said plurality of gas flow sources being configured, during rotation of said reservoir, to direct gas flow from upstream of said first end of said reservoir through said one or more openings of said reservoir from said first end of said reservoir to downstream of said second end of said reservoir, said plurality of gas flow sources collectively forming a combined gas flow in a first direction downstream of said second end of said reservoir, said combined gas flow capturing and deflecting said one or more injected jets to form a focused flow of one or more polymer fibers of micron or nanometer dimensions in said first direction, said first direction having an orientation within 5 degrees of the rotation axis of said reservoir, said plurality of gas flow sources having an orientation converging to form said combined gas flow in said first direction, a plurality of gas flow sources; A system comprising.

2. The system of claim 1, wherein the gas flow rate of at least some of said plurality of gas flow sources relative to other gas flow sources of said plurality of gas flow sources is controllable to direct said combined gas flow in said first direction.

3. The system according to claim 1, wherein the total gas flow rate from the plurality of gas flow sources is controllable to vary the distance from the reservoir where the width of the flow of the micron or nanometer-sized polymer fibers is the narrowest.

4. The number and arrangement of the plurality of gas flow sources are such that, at any single point in time during the rotation of the reservoir, the gas flow from all of the plurality of gas flow sources flows through one of the one or more openings of the reservoir, or the gas flow from all of the plurality of gas flow sources is blocked by the reservoir. The system according to claim 1.

5. The system according to any one of claims 1 to 4, wherein the plurality of gas flow sources comprises three gas flow sources.

6. The system according to any one of claims 1 to 4, wherein the first direction is within two degrees of the axis of rotation.

7. The system according to any one of claims 1 to 4, wherein the first direction is substantially parallel to the axis of rotation.

8. The converging flow of the one or more micron or nanometer-sized polymer fibers has a flow constriction smaller than the diameter of the outer sidewall of the reservoir. The system according to any one of claims 1 to 4.

9. The system further comprises a flow blocking structure disposed upstream of the plurality of gas flow sources, and the flow blocking structure is configured to reduce the influence of the air flow upstream of the plurality of gas flow sources on the focusing of the flow of the micron or nanometer-sized polymer fibers. The system according to any one of claims 1 to 4.

10. The flow blocking structure is disposed upstream of the rotating reservoir, and the flow blocking structure at least partially blocks the air flow from upstream of the rotating reservoir and reduces the influence of the air flow from upstream of the rotating reservoir on the interaction between the air flow caused by the rotation of the reservoir and the gas flow through the one or more openings. The system according to claim 9.

11. The flow blocking structure is stationary and does not rotate with the reservoir. The system according to claim 9 or claim 10.

12. The system further comprises a target rotation system, wherein the target rotation system is configured to deposit the one or more polymer fibers of micron or nanometer dimensions on two or more sides of the target by rotating a three-dimensional target during deposition. The system according to any one of claims 1 to 4.

13. The system is configured to be handheld. The system according to any one of claims 1 to 4.

14. The system further comprises a coagulation, precipitation, or cross-linking reservoir configured to hold a bath for coagulation, precipitation, or cross-linking of the injected polymer material. The system according to any one of claims 1 to 4.

15. The system further comprises a heat source for heating the polymer material prior to delivery to the reservoir or while within the reservoir. The system according to any one of claims 1 to 4.

16. The system is configured for co-deposition of fibers, and the system is a second reservoir configured to hold a second material containing a second polymer, wherein the second reservoir is rotatable about a second axis of rotation, and the second reservoir has a first end, a second end opposite the first end, and an outer sidewall extending from the first end to the second end, wherein the shape of the second reservoir includes one or more openings disposed radially inward from the outer sidewall of the reservoir, and the one or more openings are configured to allow gas to move through the reservoir from the first end to the second end. The outer sidewall, and one or more orifices formed within the outer sidewall, each of the one or more orifices being configured for ejection of the second polymer material radially outward through the orifice as a second ejected jet during rotation of the second reservoir. One or more orifices and a second reservoir. A second plurality of gas flow sources, each of the second plurality of gas flow sources being configured to direct gas flow from upstream of the first end of the second reservoir to downstream of the second end of the second reservoir through the one or more openings of the second reservoir from the first end of the second reservoir during rotation of the second reservoir, the second plurality of gas flow sources being such that the flow from the second plurality of gas flow sources collectively forms a second combined gas flow in a second direction downstream of the second end of the second reservoir, the second combined gas flow capturing and deflecting the second ejected jet to form a second focused flow of one or more second polymer fibers of micron or nanometer dimensions in the second direction, the second direction having a converging orientation such that it is within 5 degrees of the axis of rotation of the second axis of rotation, a second plurality of gas flow sources and further comprising The system according to any one of claims 1 to 4, wherein the first direction and the second direction are directed for deposition on the same collection surface. **Claim 17** The system according to claim 16, wherein the system is configured for simultaneous deposition of one or more fibers of a first polymer and one or more fibers of a second polymer on the same collection surface. **Claim 18** A method for forming and depositing at least one polymer fiber of micron or nanometer dimensions, the method comprising rotating a reservoir holding a material comprising a polymer about an axis of rotation to eject at least one injection of material from at least one orifice defined by an outer sidewall of the reservoir and Directing a plurality of gas flows through a part of the reservoir that is radially inward of the outer sidewall, each of the plurality of gas flows being directed by a corresponding one of a plurality of gas flow sources, the plurality of gas flows being directed from a first end upstream of the reservoir to a second end downstream of the reservoir during rotation of the reservoir and during injection of the at least one injection of the material, thereby forming at least one polymer fiber having a micron or nanometer dimension, the plurality of gas flows capturing and converging the at least one polymer fiber having a micron or nanometer dimension to form a combined gas flow in the first direction, forming a converging fiber deposition flow of the at least one polymer fiber having a micron or nanometer dimension in the first direction, the first direction having an orientation within 5 degrees of the axis of rotation of the reservoir, and collecting the converging fiber deposition flow on a target surface A method comprising: **Claim 19** The method according to claim 18, wherein the first direction is substantially parallel to the axis of rotation of the reservoir. **Claim 20** The method according to claim 18, wherein the flow rate of at least some of the plurality of gas flows relative to other gas flows of the plurality of gas flows is controllable to direct the combined gas flow in the first direction. **Claim 21** The method according to any one of claims 18 to 20, wherein the total gas flow rate of the plurality of gas flows is controllable to vary the distance from the reservoir at which the narrowest width of the converging fiber deposition flow of the at least one polymer fiber having a micron or nanometer dimension is located. **Claim 22** The method according to claim 18, wherein the plurality of gas flows comprises three gas flows. **Claim 23** The method according to claim 18, wherein the converging fiber deposition flow has a substantially tangential orientation with respect to the target surface during fiber collection. **Claim 24** The method according to claim 18, further comprising rotating the target surface during fiber collection. **Claim 25** A method of forming a three-dimensional tissue scaffold, comprising performing the method according to any one of claims 18 to 20, wherein the target surface has a three-dimensional shape for the tissue scaffold. **Claim 26** The method according to claim 25, further comprising rotating the target for deposition on two or more sides of the three-dimensional shape. **Claim 27** The method according to any one of claims 18 to 20, further comprising reducing the influence of the upstream air flow of the plurality of gas flows on the focusing of the fiber deposition flow of the at least one micron or nanometer-sized polymer fiber by at least partially blocking the gas flow from upstream of the reservoir. **Claim 28** The method according to any one of claims 18 to 20, wherein the material in the reservoir comprises a solvent. **Claim 29** The method according to any one of claims 18 to 20, wherein the material in the reservoir comprises a polymer melt. **Claim 30** The method according to claim 29, further comprising heating the reservoir. **Claim 31** The method according to any one of claims 18 to 20, wherein the at least one injected jet is at least partially immersed in the tank prior to being collected on the target surface. **Claim 32** The method according to claim 31, wherein the tank comprises a cross-linking agent. **Claim 33** The method according to claim 31, wherein the at least one injected jet precipitates in the tank to form the at least one micron or nanometer-sized polymer fiber. **Claim 34** The method according to claim 31, wherein the at least one injected jet solidifies in the tank to form the at least one micron or nanometer-sized polymer fiber. **Claim 35** The method according to any one of claims 18 to 20, wherein the at least one micron or nanometer-sized polymer fiber is deposited for reinforcement of a composite material. **Claim 36** The method according to any one of claims 18 to 20, wherein the at least one micron or nanometer-sized polymer fiber is deposited on one or more items of food. **Claim 37** The method comprises ejecting at least one injection of a second material held in a second reservoir containing a second polymer through at least one orifice defined by an outer sidewall of the second reservoir by rotating the second reservoir about a second axis of rotation; Directing at least one second gas flow through a part of the second reservoir that is radially inward of the outer sidewall, wherein the at least one second gas flow is directed from a first end upstream of the second reservoir to a second end downstream of the second reservoir during rotation of the second reservoir and during injection of at least one injection of the second material, forming at least one micron or nanometer sized polymer fiber of the second polymer, and the at least one second gas flow entrains at least one micron or nanometer sized polymer fiber of the second polymer to form a second focused fiber deposition flow; Collecting the second focused fiber deposition flow on a target surface; The method according to claims 18 - 20, further comprising. **Claim 38** The method according to claim 37, wherein collection of the first focused fiber deposition flow temporally overlaps with collection of the second focused fiber deposition flow.

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