ES2908322T3 - Hot melt electrospinning - Google Patents

Abstract

A system, comprising: a manifold including load sensors attached thereto, the manifold configured to receive an extruded polymer; and an electrospinning melt head assembly positioned above the manifold and configured to extrude the polymer, wherein the electrospinning melt head assembly and/or the manifold are configured to move, the melt head assembly including a syringe assembly and at least one heating element configured to supply heat to the syringe assembly, the syringe assembly comprising: a syringe including a conduit extending from a proximal end, the conduit configured to receive the polymer, and a nozzle configured to allow the polymer to pass through.

Description

DESCRIPTION

Hot melt electrospinning

COUNTRYSIDE

The subject matter described herein relates to electrospinning technology which provides reliable fiber product and improved control.

PRIOR STATE OF THE ART

Electrospinning can include a method of fiber production that uses electrical potential to draw strands of liquid polymer through a gap between a conductive source emitter and a conductive collector, or counter electrode. When a high enough voltage is applied to a liquid droplet, the liquid body can become charged and electrostatic repulsion can counteract the surface tension and the droplet can be stretched away from the emitter. At a critical point, as the droplet spreads from the emitter toward the counter electrode, a torrent of liquid may erupt from the droplet. The geometry of the extended droplet from which the torrent emerges is known as the Taylor cone. If the molecular cohesion of the liquid is high enough, breakage of the flow can be avoided and a charged liquid jet can be formed. During the trip from the emitter to the collector, the torrent can dry up. As the stream dries and/or cools, the mode of current flow can change from ohmic to convective as charge migrates to the surface of the forming fiber. As it travels towards the collector, the stream can be moved through a "churning" process to create small bends in the fiber, which can cause the fiber to thin and lengthen, until it is deposited in the collector. The thinning and elongation as a result of the beating process can lead to the formation of uniform fibers with nanometer-scale diameters.

Electrospinning research has focused on the fabrication of nanofibers. Most of this research involves the use of solution electrospinning and there has been less research on melt electrospinning since this method more generally produces fibers larger than 1 pm. In solution electrospinning, the jet can be thinned by an order of magnitude due to solvent evaporation alone. On the other hand, using high melt viscosity (n ^melt ) and non-conductive molten polymers (typically with electrical conductivity less than 10-10 S/m), the absence of a solvent greatly reduces the surface charge density ( O ^q ) and thus dampens bending instabilities. When the temperature of the electrified jet is below the glass transition temperature ( ^Tg ) of the polymer, rapid solidification of the molten jet further suppresses whipping; since higher perturbation forces are required to overcome the surface tension. The initial region of the electrified molten jet often has considerable volume and movement from the midline is reduced. The suppression of bending instabilities considerably reduces the degree of stretching that the molten electrospinning jet encounters before it solidifies. With the additional lack of thinning from solvent evaporation, melt electrospinning has typically been characterized by fibers of larger diameter than those in solution.

Through careful process design, optimization, and control, sub-micron fibers can be obtained in melt electrospinning. As in melt extrusion systems, this can be achieved by control of extensional viscosity and solidification of the filament through the thermal environment. However, since melt electrospinning is an additional convoluted problem, the effects of electric field and charge transfer must be considered in addition to the effects of heat transfer on conservation of momentum and mass. viscoelastic properties and, in some cases, crystallization in flight. By making further modifications to the material prior to processing, fiber diameters approaching nanoscale magnitudes can be produced using molten polymers: rather than delivering the polymer in solution, including additives to increase the electrical conductivity of the molten polymer is another strategy to increase the charge density in the fusion jet, thus inducing a greater degree of stretching in the jet during flight.

JP 2010 189792 discloses a system comprising a manifold configured to receive an extruded polymer, wherein the manifold is configured to move in X, Y and Z directions and an electrospinning melt head assembly positioned above. from the manifold and configured to extrude the polymer.

SUMMARY

Current subject matter may include an electrospinning melt assembly that monitors and controls the temperature of a polymer, reduces heat fluctuation in a polymer to achieve uniform polymer melting, measures deposited material during an experimental run using charge sensors in the manifold that would allow a user to control the rate of extrusion, and uses a rectified sinusoidal displacement profile during extrusion that can provide smoother linear displacements and therefore better deposited fiber structures. In addition, the current subject matter may include the active measurement and feedback of an electric field between an emitter and a collector of the electrospinning melt assembly from current sensors or from current sensors. charge that can allow the applied voltage to be controlled, thereby allowing the density of an electric field to be maintained.

In one aspect, a system includes a manifold including load sensors attached thereto, the manifold configured to receive an extruded polymer; and an electrospinning melt head assembly positioned above the manifold and configured to extrude the polymer. The electrospinning melt head assembly and manifold are configured to move relative to each other (e.g., the manifold may move and the melt head assembly may be stationary, the melt head assembly may move and the manifold may be stationary). stationary, or both the collector and the fusion head assembly can move). The fusion head assembly includes a syringe assembly and at least one heating element configured to supply heat to the syringe assembly. The syringe assembly includes: a syringe including a conduit extending from a proximal end, the conduit configured to receive the polymer, and a nozzle configured to allow the polymer to pass therethrough.

One or more of the following features may be included in any feasible combination. For example, the syringe assembly may include a plunger sized and shaped to be slidably received within the lumen such that distal movement of the plunger causes extrusion of the polymer. The system may further include a plunger drive system configured to supply a mechanical force to drive the plunger. The system may include an imaging system configured to monitor polymer extrusion; and a probe configured to measure the intensity of an electric field between the nozzle and the collector. The system may further include a control and processing system configured to receive signals from the plunger drive system, imaging system, load sensors, and probe, and to control the position of the electrospinning melt head assembly. , the force applied to the plunger, a collector voltage, and a polymer extrusion rate.

The system may further include a plunger drive system configured to supply a pressure within the syringe. The system may further include a support assembly that retains the electrospinning fusion head assembly.

The extrusion rate can be controlled to follow a ground sinusoidal profile. In some implementations, the extrusion rate is between 0.1 grams/hour and 10 grams/hour. For example, the extrusion rate can be 0.1 gram/hour, 0.2 gram/hour, 0.3 gram/hour, 0.4 gram/hour, 0.5 gram/hour, 0.6 gram/hour. hour, 0.7 grams/hour, 0.8 grams/hour, 0.9 grams/hour, 1.0 grams/hour, 2.0 grams/hour, 3.0 grams/hour, 4.0 grams/hour, 5 .0 grams/hour, 6.0 grams/hour, 7.0 grams/hour, 8.0 grams/hour, 9.0 grams/hour, or 10.0 grams/hour. The collector voltage can be between 0 and 20kV, 1kV, 2kV, 5kV, 10kV, 15kV, 20kV, 25kV, 30kV or 40kV. A voltage source may be included and can provide a maximum collector current of 0.01mA, 0.1mA, 0.18mA, 0.2mA, 0.3mA, 0.6mA, 1.0mA, 10mA or 100mA. The system may include a drive system, which may include a plunger or may have no plunger and operate, for example, using gas. For example, the system may include a drive system including a pump configured to supply pressure within the syringe by means of a gas.

The fusion head assembly and/or manifold may be configured to move in one or more of three directions, eg, x, y, z directions. In some implementations, the manifold and/or fusion head assembly may move in more than x, y, z directions. For example, the manifold and/or fusion head assembly can move in any specified coordinate system, such as polar, spherical, or cylindrical coordinates. Also, in some implementations, the manifold and/or fusion head assembly can move in 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and/or more directions. In some implementations, the x and y directions are 90 degrees apart, and the z direction is 90 degrees apart from a plane formed in the x and y directions. In some implementations, the manifold is moved such that the movement of the fusion head assembly is relative to the manifold. In some implementations, the manifold may include a cylindrical shape and rotate about a central port. In some implementations, the collector may include a flat plate.

The present invention also relates to an electrospinning system including a manifold, an electrospinning melt head assembly, a plunger drive system, an imaging system, and a probe. The collector includes load sensors attached to it. The manifold is configured to receive an extruded polymer. The electrospinning melt head assembly is positioned above the manifold and is configured to extrude the polymer. The electrospinning fusion head assembly is configured to move in the X, Y, and Z directions. The fusion head assembly includes a syringe assembly and at least one heating element configured to supply heat to the syringe assembly. The syringe assembly includes a syringe, a plunger, and a nozzle. The syringe includes a conduit extending from a proximal end. The conduit is configured to receive the polymer. The plunger is sized and shaped to be slidably received within the conduit so that distal movement of the plunger causes extrusion of the polymer. The nozzle is configured to allow the polymer to pass through it. The plunger drive system is configured to supply a mechanical force to drive the plunger. The imaging system is configured to monitor polymer extrusion. The probe is configured to measure the intensity of an electric field between the nozzle and the collector.

One or more of the following features may be included in any feasible combination. For example, a control and processing system may be included and may be configured to receive signals from the plunger drive system, imaging system, load sensors, and probe, and to control the position of the imaging head assembly. electrospinning melt, the force applied to the plunger, a collector voltage and a polymer extrusion rate.

A support assembly may be included which retains the electrospinning fusion head assembly.

The present invention also relates to an electrospinning melt head assembly including a syringe assembly including a nozzle, a plunger including at least one sealing member disposed on an outer surface thereof, a first conduit extending from a first opening at a proximal end of the syringe assembly, the passageway having a size and shape necessary to slidably receive the plunger such that the at least one sealing element on the plunger forms a seal with a wall defining the a first conduit, a second opening at a distal end, the second opening being fluidly coupled to the first conduit, the second opening being sized and shaped to resealably receive a portion of the nozzle therein; and at least one heating element configured to supply heat to the syringe assembly.

One or more of the following features may be included in any feasible combination. For example, a heater assembly may be included that retains the at least one heating element, the heater assembly including a second conduit extending from a proximal end thereof, the second conduit sized and shaped to receive the at least one heating element. least a portion of the syringe assembly. The at least one heating element may surround the second conduit. The heating element can be placed within the lower half of the heater assembly. An insulation sleeve may be included. The insulation sleeve may include a third conduit configured to receive the syringe assembly and the at least one heating element.

Power may be applied to a heating element to generate heat for transfer to a polymer. A temperature associated with the polymer is measured. The polymer is melted inside a syringe. A voltage is applied to a collector to generate an electric field across a gap between the collector and a nozzle that is releasably coupled to the syringe. The nozzle is passed over a part of the collector at least once. Force is applied to a proximal end of a plunger that is slidably disposed within the syringe to force the plunger toward the nozzle, thus forcing a portion of the polymer out of the nozzle and into the electrical field so as to create a stream of polymer. extending from the mouthpiece. The polymer stream cools and forms fibers during its journey from the nozzle to the collector.

One or more of the following features may be included in any feasible combination. The size of the gap can be adjusted with each pass of the nozzle over a datum point on the collector. The nozzle can be moved based on a displacement profile to create small bends in the polymer stream. The displacement profile may include a ground sinusoidal profile. Load sensors can be used to determine a rate of polymer extrusion from the die. An imaging system may be used in conjunction with computer vision software to determine a rate of polymer extrusion from the die. Air pressure can create the force at the proximal end of the plunger. The air pressure can be reduced enough to withdraw the plunger from the nozzle to stop, or reduce, the flow of polymer from the nozzle. The intensity of the electric field can be measured. The collector voltage can be adjusted based on the measured intensity of the electric field. The size of the gap between the nozzle and the collector can be adjusted based on the measured intensity of the electric field.

A disclosed system includes a manifold including load sensors attached thereto, the manifold configured to receive an extruded polymer; an electrospinning melt head assembly positioned above the manifold and configured to extrude the polymer, wherein the electrospinning melt head assembly is configured to move in the X, Y, and Z directions, including the melt head assembly fusing a syringe assembly and at least one heating element configured to supply heat to the syringe assembly, the syringe assembly comprising: a syringe including a conduit extending from a proximal end, the conduit being configured to receive the polymer, a nozzle configured to allow polymer to pass therethrough; a plunger drive system configured to supply a pressure within the syringe; an imaging system configured to monitor polymer extrusion; and a probe configured to measure the intensity of an electric field between the nozzle and the collector.

One or more of the following features may be included in any feasible combination. The system may further include a control and processing system configured to receive signals from the plunger drive system, imaging system, load sensors, and probe, and to control the position of the electrospinning melt head assembly. , the pressure supplied to the syringe, a manifold voltage, and a polymer extrusion rate. The system may further include a support assembly that retains the electrospinning fusion head assembly.

An electrospinning fusion head assembly may include a syringe assembly including a nozzle, a first conduit extending from a first opening at a proximal end of the syringe assembly, a a second opening at a distal end, the second opening being fluidly coupled to the first conduit, the second opening being sized and shaped to resealably receive a portion of the nozzle therein; at least one heating element configured to supply heat to the syringe assembly.

One or more of the following features may be included in any feasible combination. For example, the assembly may further include a heater assembly that retains the at least one heating element, the heater assembly including a second conduit extending from a proximal end thereof, the second conduit sized and shaped to receiving the at least a portion of the syringe assembly. The at least one heating element may surround the second conduit. The heating element can be placed within the lower half of the heater assembly. The assembly may further include an insulation sleeve, the insulation sleeve including a third conduit configured to receive the syringe assembly and the at least one heating element.

DESCRIPTION OF THE DRAWINGS

Figure 1 is an exploded view of an exemplary embodiment of an electrospinning fusion head assembly; Figure 2 is an enlarged view of a syringe assembly of the electrospinning fusion head assembly of Figure 1;

Figure 3 is a cross-sectional view of a nozzle of the syringe assembly of Figure 2;

Figure 4 is an enlarged view of a heater assembly of the electrospinning melt assembly shown in Figure 1;

Figure 5 is a perspective view of another embodiment of a heater assembly;

Figure 6 is a side cross-sectional view of the heater assembly of Figure 5;

Figure 7 is a perspective view of the syringe assembly of Figure 2 and the heater assembly of Figure 5; Figure 8 is a bottom perspective view of the syringe assembly of Figure 2 positioned in the heater assembly of Figure 5;

Figure 9 is an exploded perspective view of a support assembly;

Figure 10 is an enlarged perspective view of a top cover and heater assembly support plate of the support assembly of Figure 9;

Figure 11 is a cross-sectional view of the electrospinning fusion head assembly of Figure 1 within the support assembly of Figure 9;

Figure 12 is a diagram of one embodiment of an electrospinning system;

Figure 13 is a diagram of signal communication between a control and processing system and various other components of the electrospinning system of Figure 12;

Figure 14a is a displacement profile;

Figure 14b is another example of a displacement profile;

Figure 15 is a perspective view of a cover of the syringe assembly of Figure 2

Figure 16 is a bottom view of the lid of Figure 15;

Figure 17 is a perspective view of a syringe cap of the electrospinning fusion head assembly of Figure 1;

Figure 18 is a top view of the cap of the syringe of Figure 17;

Figure 19 is a side view of the cap of the syringe of Figure 17;

Figures 20A-F illustrate some aspects of an example implementation of the current subject matter; Y Figure 21 is a table detailing certain technical specifications of an embodiment of an electrospinning system that may be similar to the electrospinning system of Figure 12.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide a comprehensive understanding of the principles of structure, function, manufacture, and use of the systems, devices, and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of this subject matter. Furthermore, in the present description, like-named components of embodiments generally have similar features, and therefore, within a particular embodiment, each feature of each like-named component is not necessarily detailed in its entirety.

Electrospinning can include a method of producing polymer fibers that uses electrical potential to draw strands of liquid polymer through a gap between a conductive source emitter, such as a nozzle, and a conductive collector, or counter electrode. This process can be used to produce scaffolds, on which cells and tissues can be seeded and cultured. One way this process can be improved is by reducing the heat fluctuation in the polymer to achieve uniform polymer melting and thus uniform extrusion. Uniform extrusion can improve control of scaffold properties such as porosity. With greater control of scaffold properties, more repeatable scaffold construction can be achieved and scaffold properties for tissue ingrowth can be optimized. In addition, uniform geometries may provide an ideal match between cell and scaffold sizes, provide the potential for mechanical cues from the uniform geometry, e.g., improved nerve guidance, provide predictable (per model) mechanical characteristics of scaffolds in environments dynamic, eg, the aorta, and provide independence of fiber diameter and pore size in the scaffold. The melt head temperature can be monitored and tracked over time to determine system stability. Monitoring can be done using a heat sensor, such as a PT100 resistance temperature device (RTD), and an analog I/O device to measure and control the process. ("Pt" is the symbol for platinum, "100" for resistance in ohms at 0°C). In addition, tracking can be done using (1) data logging with a computer and a thermocouple and/or RTD and (2) an error term e in a provide-integral-derivative (PID) controller. The error term e can be a difference between a set point and a measured temperature, and can be integrated over the manufacturing time of a frame (minutes to hours). Stability can be affected by (1) an autotune function in the PID controller, but can also be determined by (2) tuning/stability methods such as Ziegler-Nichols tuning. Stability can ensure the emitter reaches and maintains an ideal temperature with minimal overshoot.

Another way the electrospinning process can be improved is by measuring the deposited material during an experimental run using charge sensors on the manifold to allow the user to control the rate of extrusion. For example, a single load cell capable of measuring micro Newton forces as a function of time f(t) can be used. The load cell can be placed between the mobile platform and a counter electrode. The load cell can have enough dynamic range to take the weight of the platform and still measure small forces. A load cell signal can be low-pass filtered to derive a signal that changes slowly with increasing force due to a mass of deposited material. Said signal can also be used to modulate the rate of material deposition. Any rapid change in f(t) may indicate erroneous or non-uniform deposition and may indicate an alarm state in the software. Furthermore, the use of a ground sinusoidal displacement profile during extrusion can provide smoother linear displacements and thus better deposited fiber structures. As another example, active measurement and feedback of the electric field between the emitter and the collector from current or charge sensors can allow the applied voltage to be controlled, allowing the electric field density to be maintained.

In some implementations, the feedback to increase the separation distance with each step can be monitored and controlled and combined with any control of the electric field to ensure consistency of the process scenario with each step.

Figure 1 shows an exploded view of an exemplary embodiment of an electrospinning fusion head assembly 100. The fusion head assembly 100 may include a syringe assembly 110, a heater assembly 140, a high-pressure insulation sleeve temperature 170 and a syringe cap 190. The syringe assembly 110 is operable to retain and controllably deposit a polymer onto a substrate. Syringe assembly 110 may be received within heater assembly 140, which may be operable to heat the polymer to a desired temperature, and heater assembly 140 may be inserted into insulation sleeve 170. over a proximal end of syringe assembly 110 and heater assembly 140 to provide a layer of thermal insulation while allowing access to the syringe assembly 110 and heater assembly 140. The specific components of electrospinning melt head assembly 100 will be discussed in greater detail below.

Figure 2 shows an enlarged view of the syringe assembly 110 of Figure 1. The syringe assembly 110 may include a syringe 112, a plunger 114, a cap 116, and a nozzle 118. As shown in Figures 1 through 2, syringe 112 may have a substantially cylindrical geometry and may include a first opening 120a at a proximal end 112a, a second opening (not shown) at a distal end 112b, and a passageway 120 extending therebetween, where the passageway may extend along a central axis a 2. Conduit 120 extending from proximal end 112a to distal end 112b can receive a polymer to be heated and extruded, deposited, or spun onto a substrate. Opening 120a at the proximal end may receive plunger 114, which may have at least one or more sealing elements 113 such as, for example, O-rings, which may form a seal with a wall of passageway 120 of syringe 112. In some embodiments, the plunger may have two sealing elements 113. In some embodiments, the plunger may be made of stainless steel. The plunger is translatable proximally and distally within lumen 120 of syringe 112 to control polymer extrusion. In practice, there are several ways to control the position of plunger 114. For example, the position of plunger 114 can be altered by applying positive air pressure to a proximal end 114a of plunger 114. Alternatively, a rod can be attached to the opening 115 at the proximal end 114a of the plunger and force can be applied to the plunger 114 by means of the rod. Adjusting the position of plunger 114 using air pressure can be beneficial as it can simplify construction and reduce costs. Air or some other suitable gas pressure may be applied directly to the molten polymer to extrude it through the die. The method of operation is discussed below in greater detail.

Cap 116 may function to couple nozzle 118 to syringe 112 and to provide access to syringe lumen 112 through distal end 112b. In the illustrated example, cap 116 has a substantially cylindrical body and includes a cylindrical mating feature 122 that extends in a proximal direction. The coupling feature 122 may allow the cap 116 to be releasably attached to the syringe 112 via the second opening at the distal end 112b of the syringe 112. The cap 116 may be attached to the syringe 112 in a variety of ways. . For example, the mating feature 122 may have threads that may mate with threads on the second opening of the syringe 112. Alternatively, the mating feature 122 and the second opening may be mated by, for example, a friction fit. . In some embodiments, mating feature 122 may include seals 124 disposed on an outer surface thereof. Mating feature 122 may be received within the second opening of syringe 112, and gaskets 124 may form a seal between mating feature 122 and conduit 120 of syringe 112. In some embodiments, gaskets may include gaskets O-rings that can be made from FFKM perfluoroelastomers. In addition, the mating feature 122 may have a curved face 117 which may form part of a distal end 114b of the plunger.

As shown in Figures 1-2, syringe 112 and cap 116 may include bores 126a, 126b, and bores 126c, 126d, all of which may be threaded, and temperature measurement channels 128a, 128b. Perforations 126a, 126b may allow syringe 112 to engage cap 116. Figures 15-16 show enlarged views of cap 116. As shown in Figures 2, 15, and 16, perforations 126b, 126d may be larger than the perforations 126a, 126c. This helps ensure that cap 116 and syringe 112 are properly aligned during assembly. Perforations 126a may align with perforations 126b, and perforation 126c may align with perforation 126d, and syringe 112 may be attached to cap 116 by means of coupling elements, such as, for example, screws or bolts, which may extend through the perforations 126a, 126b, 126c, 126d. Temperature measurement channels 128a, 128b can receive a temperature measurement sensor, such as, for example, a thermocouple, PT100 RTD, and the like that can extend through syringe 112 and into cap 116 to monitor the temperature of the cap 116 as close to the nozzle 118 as possible. Although not illustrated, the syringe 112 and cap 116 can include multiple temperature measurement channels that can receive temperature measurement sensors. Including more than one channel may allow multiple temperatures to be taken at various positions along the length of the syringe 112 and cap 116. In an exemplary embodiment, the syringe 112 and cap 116 may be made of stainless steel. Stainless steel can provide a good combination of corrosion resistance, thermal conductivity, and machinability. However, syringe 112 and cap 116 may be made of any corrosion resistant material, such as titanium, nickel, or any other material suitable for the purpose described. In some embodiments, cap 116 may be integral with syringe 112.

As shown in Figure 3, the nozzle 118 may include a central passageway 130 that extends through a proximal coupling portion 131 and a distal extrusion portion 132. The central passageway 130 may have a first portion 135 with a first diameter, and a second part 137 having a second diameter. The first portion 135 may extend from an inlet 130a at a proximal end 118a of the proximal coupling portion, and the second portion 137 may lead to an outlet 130b at a distal end 118b of the extrusion distal portion 132. The distal portion of Spray 132 may include an inwardly tapering inner surface 132a, which may create a transition zone that may couple the first portion 135 of conduit 130 to the second portion 137 of conduit 130. The inwardly tapering inner surface 132a may result in the outlet 130b of the nozzle 118 having a smaller diameter than the inlet 130a of the nozzle 118. In some embodiments, A coating of a conductive material may cover part of the extrusion portion 132 of the nozzle 118. The coating may act as a high voltage electrode when connected to a suitable high voltage source.

In some implementations, a high voltage source may be included that applies a voltage between 0 and 20 kV. In some implementations, the voltage source can provide a voltage of 1 kV, 2 kV, 5 kV, 10 kV, 15 kV, 20 kV, 25 kV, 30 kV, 40 kV, or more. The power supply can provide a voltage resolution of 10 V, for example. In some implementations, the voltage source can provide a maximum current of 0.18mA. In some implementations, the voltage source may provide a maximum current of 0.01 mA, 0.1 mA, 0.2 mA, 0.3 mA, 0.6 mA, 1.0 mA, 10 mA, 100 mA, or plus.

In the illustrated embodiment, the proximal mating portion 131 of the nipple 118 may include threads that may mate with threads in an opening 119 (shown in FIG. 16) in the cap 116. In an exemplary embodiment, the nipple 118 may be made of a material that has a coefficient of thermal expansion that is greater than that of cap 116. For example, if cap 116 is made of a stainless steel, nozzle 118 may be made of brass. Therefore, when the fusion head assembly 100 is heated, the nozzle 118 can expand more than the cap 116, which can help form a seal between the threads on the coupling portion 131 of the nozzle and the threads on the nozzle. the opening in the lid 116.

In order to provide heat to the polymer within syringe 112, syringe assembly 110 may be inserted into heater assembly 140. Figure 4 shows an enlarged view of heater assembly 140 shown in Figure 1. heater 140 may include heating elements 154, a heating member 142, or body, which may be in the form of, for example, a cylindrical sleeve, as well as a heater cover 144 and mounting flange 146. The heating member 142, heater cap 144 and mounting flange 146 may all have substantially cylindrical geometries. Mounting flange 146 may include sleeve mating holes 146a, heater mating holes 146b, bracket mating holes 146c, and a center hole 146d. Sleeve mating perforations 146a may be aligned with mating perforations 143a on a proximal end 142a of heating member 142, and may allow mounting flange 146 to be attached to heating member 142 using a coupling element, such as such as a screw or bolt. Bracket mating perforations 146c may function to allow heater assembly 140 to be mated to a support frame, discussed in greater detail below.

As shown in Figure 4, heating member 142 may have a substantially cylindrical geometry and may include a first opening 148a at proximal end 142a, a second opening (not shown) at distal end 142b, and a conduit 148 extending understand each other. Heating member 142 may include mating perforations 143a as well as heater perforations 143b at proximal end 142a. As described above, mating perforations 143a in heating member 142 may align with mating perforations 146a in mounting flange 146, and may allow heating member 142 and mounting flange 146 to be mated using coupling elements, such as screws or bolts. Heater perforations 143b may extend along the length of heating member 142 and may be aligned with heater perforations 146b of mounting flange 146 at proximal end 142a of heating member 142 and with heater perforations 145b. of cap 144 at distal end 142b of heating member 142.

Heater cap 144 may include heater perforations 145b as well as mating perforations 145a. Heater cap 144 may have a recessed area 150 extending distally from opening 150a in proximal end 144a, and may also include a bore 152 extending through distal end 144b of cap 144. Central bore 146d , conduit 148, recessed area 150, and bore 152 may share a central axis A3 and may be aligned so that syringe assembly 110 can be received within heater assembly 140. receive and seat a distal portion of syringe assembly 110, and bore 152 may allow nozzle 118 to extend through distal end 144b of heater cap 144.

Heating elements 154, such as, for example, cartridge heaters, may be used to provide heat to syringe assembly 112. In some embodiments, heating elements 154 may be 200W cartridge heaters. of heating can generate more than 200 W of heat or less than 200 W of heat. Heating elements 154 may be inserted through heater perforations 146b and 143b and may extend into heater perforations 145b in heater cover 144. Heating elements 154 may heat mounting flange 146, heating member 142 and heater cap 144, which may in turn heat syringe assembly 110 and polymer that may be within syringe 112. In some embodiments, heating elements 154 may heat heater assembly 140 to a temperature of about 250°C.

Heating member 142, mounting flange 146, and cover 144 may be made of any material suitable for the purpose described. However, in an exemplary embodiment, heating member 142, mounting flange 146, and cover 144 may be made of aluminum. Aluminum has a thermal conductivity relatively high, which can result in a more even temperature distribution since the heat from the heating elements 154 can be conducted well through all parts of the heater assembly 140.

Syringe assembly 110 and heater assembly 140 may be insulated using, for example, insulation sleeve 170, to minimize heat loss and improve temperature control. Referring again to Figure 1, isolation sleeve 170 may include a conduit 172 that may extend between an opening 172a at a proximal end 170a of isolation sleeve 170 and an opening (not shown) at a distal end 170b of the sleeve. of insulation 170. Syringe assembly 110 and heater assembly 140 may be inserted into conduit 172 of insulation sleeve 170. Insulation sleeve 170 may be made of any insulating material that can withstand the maximum temperature of the heating elements. 154. In some embodiments, the insulation sleeve may be made of calcium silicate. Insulation sleeve 170 and heating elements 154 may form a concentrated zone of heating. This concentrated zone of heating concentrates the heat in a volume of the syringe where, in operation, the polymer is loaded.

In order to provide insulation at the proximal end of the syringe 112, the syringe cap 190 may be positioned over the proximal end 112a of the syringe and/or the mounting flange 146. The syringe cap 190 has a substantially cylindrical geometry and may include a series of perforation holes 192 that may extend from a proximal end 190a of syringe cap 190 to a distal end 190b of syringe cap 190. In some embodiments, a portion of cap 190 may extend toward the interior of lumen 120 of syringe 112 so as to form a seal with the wall defining lumen 120. In some embodiments, syringe cap 190 may be made of, for example, DuroBest® 280 (agk), polyether ether ketone (PEEK) or IGLIDUR® (IGUS INC., East Providence R.I. 02914). Figures 17 through 19 show various views of syringe cover 190. Drill holes 192 may provide access to syringe assembly 110 and/or heater assembly 140. For example, at least one drill hole 196 may provide access. access to temperature measurement channel 128a, so that a temperature sensor 129 can be inserted into temperature measurement channels 128a, 128b. In some embodiments, temperature sensor 129 may be a 4mm PT100 temperature sensor, or a K-type thermocouple. In some embodiments, syringe cap 190 may include mating holes 195a, 195c, which may be aligned with the perforations 126a, 126c of the syringe 112 and may allow the syringe cover 190 to be attached to the syringe 112 using coupling elements, such as, for example, screws or bolts. Syringe cap 190 may also include mounting holes 197, which are discussed below. A hose coupling can be attached to an air inlet port 193 so that gas pressure can be applied to the plunger to force polymer liquid from the nozzle. Alternatively, a rod may extend from entry port 193 and engage opening 115 in proximal end 114a of the plunger. The rod may then apply mechanical force to the plunger to move it proximally and/or distally within lumen 120 of syringe 112. In some implementations, gas may be applied directly to the molten polymer. In some implementations, a solenoid valve may be used to control gas pressure, including applying positive and negative pressure to the plunger. This approach can provide improved control of the extrusion process.

In some embodiments, a heater assembly may have a single body configuration rather than having multiple components, such as those described with respect to heater assembly 140. The heater assembly may also have heating elements integrated into it. Figures 5-6 show an example of an embodiment of a heater assembly 240 that has a single body configuration and can have one or more heating elements 254 integrated. Temperature sensors can also be integrated in a single body configuration. Figure 5 shows a perspective view of heater assembly 240, and Figure 6 shows a side cross-sectional view of heater assembly 240. Heater assembly 240 may have a body 242 that may have substantially cylindrical geometry, and may include a central conduit 248 that extends from an opening 248a in a proximal end 240a of heater assembly 240, toward a distal end 240b of heater assembly 240. Proximal end 240a of heater assembly 240 may include a flange 246 that can extend radially outward. Flange 246 may have bracket mating perforations 246c which may function in a similar manner to bracket mating perforations 146c. The distal end 240b of the heater assembly may have a bore 252 that may receive a nozzle, such as a nozzle 118 of the syringe assembly 110. In the illustrated embodiment, the central passageway 248 and bore 252 may share a central axis A4.

Heater assembly 240 may also include a port 260 having a radial conduit 262 that may extend from one end 260a of port 260 to central conduit 248. Port 260 may allow cables to enter and exit conduit 248. For example , temperature sensor leads 129 that can monitor temperature of a syringe assembly, such as syringe assembly 110, may be passed through conduit 262 of port 260.

In the illustrated example, instead of inserting heating elements into heater assembly perforations, as described with respect to heater assembly 140, heating elements 254 may be integrated into a concentrated heated zone 256 of body 242 of heater assembly 240. In some embodiments, the zone 256 may be confined to a lower half, or distal half, of heater assembly 240. Heating elements 254 may be one or more resistive heaters that may surround, or wrap around, conduit 248 within body 242 of heater assembly. 240. The heating elements 254 may be powered from a power source via a cable 257 that may extend outside the body 242 of the heater assembly 240. The use of a heater assembly configuration that includes heating elements that wrap to conduit 248 may provide more uniform heat transfer to syringe assembly 110, which may result in the polymer having a more uniform temperature distribution. Such a configuration can increase the accuracy of a control system that can be used to monitor and maintain the temperature of syringe assembly 110 and/or the polymer within syringe 112. By creating a more uniform temperature profile, measurements of temperature sensors may be less sensitive to the exact position of the temperature sensor 129, which may result in greater accuracy and precision of the temperature measurement. In some embodiments, conduit 262 of port 260 does not extend into conduit 248. In that case, conduit 262 may be used to pass cables that may be attached to heating elements 254 or temperature sensors within the walls of the assembly. of heater. For example, cable 257 may extend from heating elements 254, to conduit 262, and out of heater assembly 240, instead of extending out of body 242 of heater assembly 240.

Figures 7 and 8 show how syringe assembly 110 may be received within heater assembly 240. Figure 7 shows syringe assembly 110 aligned with opening 248a in proximal end 240a of the heater assembly. Figure 8 shows syringe assembly 110 positioned within conduit 248 of the heater assembly.

Regardless of which heater assembly is used, the fusion head assembly 100 may be supported within a support assembly. The support assembly 300, shown in the figure. 9, may include top and bottom covers 302, 304, side covers 305, 306, top and bottom frames 308, 309, and heater assembly support plate 310.

Bottom cover 304 may be generally in the shape of a square or rectangular plate. In some embodiments, bottom cover 304 may be made of polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), and/or other electrically insulating and thermally resistant material. Lower cover 304 may have a recessed area 312 extending distally from an opening 312a on a proximal surface 304a, and may also include a perforation 352 extending from the recessed area 312 to a distal surface 304b of the cover 304. Lower cover 304 may also have mating perforations 314a that may extend distally from proximal surface 304a of lower cover 304. The recessed area 312 may be sized and shaped to receive a distal portion of isolation sleeve 170. Perforation 352 it may be generally aligned with bore 252 of heater assembly 240 so that it may receive nozzle 118 of syringe assembly 110.

As illustrated in Figure 9, support assembly 300 may include upper and lower frames 308, 309, or structural ribs. In some embodiments, the upper and lower frames 308, 309 may be made of aluminum. Support frames 308, 309 may be generally square or rectangular in shape and may have perimeter dimensions and may be approximately the same as bottom cover 304. Support frames 308, 309 may have ducts 316, 318 extending from the proximal surfaces 308a, 309a to the distal surface 308b, 309b of the frames. In the illustrated example, the ducts 316, 318 are generally square in shape. However, the passageways 316, 318 may have any suitable geometry to receive and retain the fusion head assembly 100. In addition to the passageways 316, 318 for receiving the fusion head assembly 100, the support frames 308, 309 may having first sets of mating holes 320a, 321a, second sets of mating holes 320b, 321b, and third sets of mating holes 320c, 321c.

In the illustrated example, side covers 305, 306 include mating holes 319b. Mating holes 319b may be aligned with mating holes 320b, 321b in support frames 308, 309 to allow side covers 305, 306 to be attached to support frames 308, 309 using, for example, a screw. , a bolt or a pin. As shown in Figure 9, support plate 306 may also include larger mating holes 319c, as well as conduit 322. In some embodiments, conduit 322 may be used to feed power cables to cartridge heaters 154, or to the heating elements 254, from an external power supply. These cables can be managed through the use of conduit and labeling. The cables may further include input filters to improve the electromagnetic compatibility (EMC) characteristics of the system and/or prevent electrical leakage. Perforations 320c, 321c may be aligned with perforations 319c in side cover 306, and may allow fusion head assembly 100 and support assembly 300 to be attached to a mounting assembly (not shown) using coupling elements. such as, for example, screws, bolts, or other separation mechanisms, such as standoff posts, rods, or an adapter plate. In some embodiments, the side covers 305, 306 may be made of aluminum and may be powder coated white. Although side cover 305 is illustrated as a three-sided bent aluminum piece, each side of side cover 305 may be an individual piece similar to side cover 306.

Figure 10 shows an enlarged view of the top cover 302 and support plate 310 of the heater assembly. In some embodiments, the top cover 302 may be made of aluminum and may be white powder coated, and the heater support plate 310 may be made of polyether ether ketone (PEEK). The heater assembly support plate 310 may also have a generally square or rectangular shape and may have perimeter dimensions that may be approximately equal to those of the bottom cover 304. The support plate 310 may have a recessed area 324 extending distally from an opening 324a in a proximal surface 310a, and may also include a perforation 326 extending from the recessed area 324 to a distal surface 310b of the support plate 310. The support plate 310 may also include mating perforations 328a. , and first and second sets of mating holes 330a, 332a countersunk. In addition, the recessed area may include mounting holes 325 in the syringe cap 190. Mounting holes 325 in the cap may align with mounting holes 197 in the syringe cap, which may allow the cap to be removed from the syringe cap. syringe 190 is attached to heater assembly support plate 310 using fasteners, such as screws, bolts, or other fasteners suitable for the purpose described.

Top cover 302 may be generally square or rectangular in shape, and may include mating perforations 334a that may align with mating perforations 328a in backing plate 310, and a center perforation 336 that may align with opening 324a. on support plate 310.

Support assembly 300 may be assembled from the various components using coupling elements, such as, for example, screws, bolts, and/or pins. Distal end 170b of isolation sleeve 170 may be positioned in recessed area 312 of bottom cover 304.

Distal surface 318a of lower support frame 309 may be positioned on proximal surface 304a of lower cover 304 such that mating perforations 320a align with mating perforations 314a. Coupling elements can be inserted into coupling holes 314a, 320a to couple bottom support frame 309 to bottom cover 304.

Heater assembly 240 may be inserted into conduit 172 of insulation sleeve 170 such that perforation 252 of heater assembly 240 aligns with perforation 352 of bottom cover 304. Although not shown, insulation sleeve 170 may have a radial bore to allow port 260 of heater assembly 240 to pass through. Electrospinning fusion head assembly 100 and support assembly 300 may be assembled as follows.

Syringe assembly 110 can be inserted into heater assembly 240. A polymer that can be used for electrospinning can be inserted into conduit 120 of syringe 112. The polymer can be in the form of beads.

The upper support frame 308 can be attached to the side covers 305, 306 using coupling elements that can extend through some of the coupling holes 319b in the side covers 305, 306 and in the coupling holes 320b in the frame of Top support.

The upper support frame 308, with the side covers 305, 306 releasably attached thereto, can be positioned over the insulation sleeve 170 so that the rest of the mating holes 319b align with the mating holes 321b on the bottom support frame 309.

Larger mating holes 319c in side cover 306 can be releasably attached to third sets of mating holes 320c, 321c in top and bottom frames 308, 309.

Heater support plate 310 may be positioned over insulation sleeve 170, heater assembly 240, and syringe assembly 110. Heater support plate 310 may be releasably attached to proximal end 240a of heater assembly 240 by coupling elements insertable into countersunk coupling holes 330a in heater assembly 240 and coupling holes 246c in proximal end 240a of heater assembly 240. Heater support plate 310 can also be attached to support frame bracket 308 by means of coupling elements that can be inserted into countersunk coupling holes 332a and coupling holes 320a in the upper bracket 308.

Distal end 190b of syringe cap 190 may be positioned in recessed area 324 of heater support plate 310. Although not illustrated, syringe cap 190 may have sealing elements extending around its perimeter. that can form a seal with the recessed area 324.

Top cover 302 may be attached to heater support plate 310 by coupling elements insertable into coupling holes 334a in top cover 302 and coupling holes 328a in support plate 310.

If a multi-component heater assembly is used, such as heater assembly 140, it can be assembled as described above and can be incorporated into melt head assembly 100 in the same manner as heater assembly 240. Figure 11 shows a cross-sectional view of the electrospinning melter head assembly 100, shown in Figure 1, within the support assembly 300 illustrated in Figure 9. As shown in Figure 11, a portion 190c of the cap 190 may extend into the lumen 120 of the syringe 112 so as to form a seal with the wall defining the lumen 120.

Figure 12 shows a diagram of one embodiment of an electrospinning system 400. The electrospinning system 400 may include the electrospinning melt head assembly 100, which includes the support assembly 300, a manifold assembly 402, a imaging system 404, plunger drive system 406, probe 408, and control and processing system 410. Fusion head assembly 100 may be assembled and mated with support assembly 300 as described above and may be mounted on a mounting assembly (not shown) that allows the fusion head assembly to move along the X, Y, and Z axes.

As described above, plunger 114 of syringe assembly 110 can be actuated by applying air pressure to proximal surface 114a, or by using a rigid mechanical connector, such as a rod. Plunger drive system 406 may supply air or other mechanical force to the plunger to create proximal or distal displacement to expel polymer liquid or to draw it back into syringe 112. In some implementations, plunger drive system 406 may include a bomb. Plunger drive system 406 may send and receive signals to and from control and processing system 410 to control the position of plunger 114, thereby controlling the flow of polymer from nozzle 118. In some embodiments, the plunger 114, so that the applied air pressure directly expels polymer liquid or draws it back into syringe 112. The gas that is supplied into syringe 112 is not limited to air, but can also include any inert gas, such as, for example, nitrogen or argon. In some implementations, omitting the plunger 114 may be advantageous in some implementations since in implementations using a plunger, molten polymer may be extruded through the die even if no driving force is applied. Due to the tight fit between the piston and the melt chamber walls, any expanded air in the system during the heating phase can force the molten polymer through the nozzle, since it may not be released.

As polymer is ejected from nozzle 118, it may deposit on a manifold 412 of manifold assembly 402. Manifold assembly 402 may include manifold 412, a base 414, and one or more load sensors 416 that may be used to determine the amount of polymer that has been deposited on the manifold 412. By measuring the amount of polymer that has been deposited on the manifold, a rate of polymer extrusion from the nozzle 118 can be determined. In some embodiments, the nozzle 118 can be connected to mains and high voltage power may be supplied to collector 412 such that an electric field is created between collector 412 and nozzle 118. In some embodiments, collector 412 may have a conductive coating that may allow it to function as an electrode. In other embodiments, collector 412 may be conductive.

In addition to, as an alternative to, using load sensors 416 to measure the amount of polymer deposited on manifold 412, imaging system 404 may be used in conjunction with machine vision software to determine a polymer extrusion rate and to perform tracking the amount of extruded polymer. Imaging system 404 may have a field of view (FOV) that includes nozzle 118 and collector 412.

As the polymer strands are deposited on collector 412, in an area sometimes referred to as the boundary, and the polymer framework increases in height, the electric field generated between nozzle 118 and collector 412 may change and/or weaken due to the insulating properties of the polymer. Probe 408 may measure the electric field between nozzle 118 and collector 412. Probe 408 may be, for example, a field mill or electric field meter (EFM). Alternatively, or additionally, probe 408 may measure the charge of collector 412 and/or the polymer on the collector. Information about the electric field between nozzle 118 and collector 412 can be used to adjust the power supplied to, or voltage from, collector 412, thereby allowing an electric field density to be maintained. Information about the electric field can also be used to adjust the position of the electrospinning fusion head assembly 100 in the Z direction with each pass, thereby altering the electric field. In some embodiments, collector 412 may have a stippled and/or pointed surface, which may allow for a more uniform electric field density during polymer deposition. In some embodiments, the dots and/or spikes may extend between about 1mm and 2mm, or less than 10mm, from the commutator surface. The dots and/or spikes may be arranged in an array and may have a variable pitch. The collector zones 412 may also have points and/or spikes that may be arranged in patterns with varying density. In other words, certain areas of collector 412 may have points and/or spikes that may be more closely packed than they are in other areas of collector 412.

The electrospinning process occurs over a short gap distance between collector 412 and nozzle 118. In a similar way to the electric field, as the frame increases in height with each step, the gap between collector 412 and nozzle 118 can also be increased to maintain a constant deposition distance between nozzle 118 and the previously deposited polymer fiber.

The position of the nozzle 118 can be monitored and feedback can be used to increase the separation distance with each step. Nozzle 118 can be monitored and controlled and combined with any electrical field control to ensure consistency of process displacement with each passage of nozzle 118 over a given point on manifold 412.

Figure 13 shows a signal communication diagram between the control and processing system 410 and various other components of the electrospinning system 400. As shown in Figure 13, the control and processing system 410 may include a signal processing module. images 422, an electric field module 424, a load module 426, a plunger module 428, a heater module 430 and a collector module 432.

Heater module 430 may send and receive signals to and from temperature sensor 129 and heating elements 254. In operation, a desired polymer temperature may be selected by control and processing system 410. The selected temperature may correspond to an initial power that can be provided to the heating elements from a power source. The temperature of nozzle 118 can be measured using temperature sensor 129 in temperature measurement channels 128a, 128b of syringe assembly 110. Temperature sensor 129 can send temperature signals to heater module 430, which can analyze the signals, calculate the temperature, determine an appropriate action for the heating elements 254, and send a heating signal corresponding to that of the heating elements 254. The behavior of the system can be coordinated in hardware and software developed to indicate the multiple signals conditions (for example, temperature, platen location, and material deposition rate) and perform calculations on inputs to produce outputs (for example, heater coil power, plunger displacement, electric field potential). In some embodiments, a resistance temperature detector (RTD), such as a PT100 RTD, can be used to measure the temperature of the nozzle 118. In that case, the heater module 430 can measure the resistance through the temperature sensor. temperature 129 and correlate that resistance with a temperature value. In other embodiments, a thermocouple, for example, a type K thermocouple, may be used to measure the temperature of nozzle 118. A polymer melt temperature may be measured empirically prior to loading the polymer into syringe 112. For example, phase change experiments by heating and melting the polymer and measuring the temperature of the polymer throughout the heating and melting process. In some embodiments, the heating signal may come from a heater module power source. The heater module 430 may include a proportional integral derivative (PID) controller and may use PID control with an autotune function to control the power delivered to the heating elements 254. The input may be the temperature signal from the sensor. temperature 129 and the output can be the heating signal. The autotune function can determine a thermal response of the over time and can calculate a system parameter to properly drive the system. As described above, temperature sensor 129 may be an RTD, a thermocouple, or both. If more than one temperature sensor 129 is implemented, one sensor can be used as a reference for the PID controller and another sensor can be used to monitor the melt temperature of the polymer. The use of a type K thermocouple can be more dynamic than that of the PT100 temperature sensor. This can reduce or prevent overshoot of the polymer as the heater reaches a desired set point more quickly and thus can be close to a steady state by the time sufficient conduction occurs. This may include a gradual heating process compared to some embodiments. In addition, the use of separate temperature monitoring and control probes can allow fine tuning of the melting setpoint temperature, combating natural losses. In some implementations, the PID controller reference temperature can be built into the heating head in such a way that it cannot be removed, reducing the chance of overheating the system to the point of irreversible damage.

Once the temperature sensor outputs a signal corresponding to the desired polymer temperature, the melt head assembly 100 may be left unheated for a period of time to ensure that it has reached thermal equilibrium. Polymer that is not in direct contact with syringe 112 will melt due to the thermal conductivity of the loaded polymer. The time required to melt all of the polymer will depend on the mass of the polymer and its thermal conductivity.

PID temperature may also include dual relay control on heater power lines, temperature lockouts, and internal alarms/lockouts to enhance user safety and/or device performance.

When the system has reached thermal equilibrium, the polymer can be extruded through die 118. High voltage power can be supplied to collector 412 from collector module 432. Collector module 432 can also monitor the voltage at the collector. 412 and a position of the nozzle 118 in the X, Y, and Z directions. The plunger module 428 can also send a drive signal to the plunger drive system 406. The plunger drive system 406 can receive the drive signal and may provide air pressure to the space between proximal end 114a of plunger 114 and distal end 190b of syringe cap 190 to urge plunger 114 distally within lumen 120 of syringe 112 to force polymer liquid from the nozzle 118. Alternatively, if the plunger is actuated by a rod, the plunger drive 406 can apply a force to the rod to displace the plunger. If the air pressure directly drives the polymer melt without any plunger, the plunger drive system 406 can receive the drive signal and can provide air pressure to the space between the proximal end of the polymer melt and the distal end 190b of the cap. of the syringe 190 to force liquid polymer from the nozzle. The rate of this natural extrusion can depend on the viscosity of the molten polymer. Low viscosity molten polymers can be extruded very quickly, while high viscosity polymers can be extruded very slowly.

At a critical point, as the polymer droplet extends from the nozzle 118 toward the manifold, a torrent of polymer liquid may erupt from the droplet. During the run from nozzle 118 to manifold 412, the stream may dry up. As the stream dries or cools, the mode of current flow can change from ohmic to convective as charge migrates to the surface of the forming fiber. While traveling toward manifold 412, manifold module 432 may send a motion signal to the mounting assembly (not shown) holding fusion head assembly 100 to move fusion head assembly 100 in the X-Y plane to create small bends in the fiber, which can cause the fiber to become thinner and longer, until it settles on the collector. In some implementations, the mounting assembly retains the manifold 412 to move the manifold in the X-Y plane to bend small bends in the fiber, which can cause the fiber to elongate and then settle on the manifold 412. The thinning and Elongation as a result of X-Y movement can lead to the formation of uniform fibers with nanometer-scale diameters. The X-Y movement of the fusion head assembly 100 and/or manifold 412 can be achieved by an XYZ drive system which can be implemented with various drive mechanisms such as a ball and screw drive system or a linear positioner. . When the linear positioner is used, linear interpolation can be facilitated to maintain a constant speed during curve operations, whereby there is no acceleration or deceleration during curves and therefore grids with round features can be deposited. In addition, the constant linear speed can prevent crimped melt electrospun fibers.

In some embodiments, G-code can be used to create polymer scaffolds with a certain porosity and density. In other embodiments, position table logic may be used to command the movement of the fusion head assembly 100. A displacement profile of linear steps of movement may be important in creating fine, straight fibers. Straight fiber extrusion and deposition can depend on the velocity profile of the linear motion steps. If the speed is not properly matched to the extrusion speed (the electrospinning speed), ie the extrusion speed is too fast or too slow, the deposited fibers may be curly instead of straight. A displacement profile 500 can be seen in Figure 14a. The displacement profile 500 shows that each pass has a first part 502 showing linear acceleration, a second part 504 showing constant velocity, and a third part 506 showing constant linear deceleration at the end of the pass. This travel profile 500 is abrupt in nature given the short and fast nature of the travel. Instead of using the displacement profile 500 shown in Figure 14a, a displacement profile 600 using a sine-ground profile 602, as shown in Figure 14b, can provide smoother linear displacements and therefore fibers. better deposited.

Referring again to Figure 13, as the polymer fibers are deposited in collector 412, imaging system 404 can monitor the rate and volume of polymer extrusion from nozzle 118. The imaging system Image processing module 404 can send image signals to image processing module 422. Image processing module 422 can send rate signals to collector module 432 and plunger module 428. Collector module 432 and plunger module 428 can receive the rate signals and can send signals to manifold 412 and plunger drive system 406 to adjust the voltage of manifold 412 and the pressure applied to plunger 114, respectively. By adjusting the voltage at collector 412, the density of an electric field can be maintained.

Load sensors 416 can measure the weight pressure of polymer fibers in manifold 412 and can send corresponding signals to load module 426. Load module 426 can receive the signals, determine how much polymer is in manifold 412. as well as extrusion rate, and can send corresponding load signals to manifold module 432 and plunger module 428. For example, the mass of polymer in manifold 412 may be determined by load sensors 416 and the charge modulus 426. A volume of polymer can be determined using a known density, molar mass, and/or molecular weight of the polymer, along with the mass measured in manifold 412. A rate of polymer extrusion can be controlled by determining a change in mass /volume of polymer in collector 412 and dividing by the time between measurements. Load signals can be analog and can be converted to digital by load module 426. Collector module 432 and plunger module 428 can send signals to nozzle 118 and plunger drive system 406 to adjust the charging voltage. nozzle 118 and extrusion rate, respectively.

Probe 408 can measure the electric field strength between nozzle 118 and collector 412 and can send field signals to electric field module 424. The field signals can correspond to the electric field strength between nozzle 118 and collector. 412, and/or the electrical charge of the collector 412. In some embodiments, the electric field module 424 may include a microammeter or other electrical charge/current detector. Therefore, the collector 412 can send electric charge signals to the electric field module 424. The signals of electric charge can correspond to the electric charge of the collector 412. The electric field module 424 can receive the field signals and the electric charge signals of the probe 408 and the collector 412, respectively, and can send a signal to the collector module 432. The collector module 432 can receive the signal and can adjust the voltage of the collector 412 or adjust the position of the fusion head assembly 100 in the Z axis, thus adjusting the distance between the nozzle 118 and the collector 412. The module manifold 432 can also send a signal to plunger module 428, which can send a signal to plunger drive system 406 to adjust the rate of extrusion.

The polymer extrusion rate can also be reduced or stopped at any point during the extrusion process. For example, if the polymer extrusion rate is determined to be too high, or if extrusion is complete, the plunger module 428 may send a signal to the plunger drive system 406 indicating that the plunger 114 should retract. Plunger drive system 406 can create a vacuum pressure behind plunger 114 to draw it proximally into lumen 120 of syringe 112, thus drawing liquid polymer from nozzle 118. In other words, air pressure applied to the end Proximal portion of plunger 114 may be reduced enough to draw the plunger proximally within conduit 120 to stop or reduce the flow of polymer from nozzle 118.

In the embodiment of electrospinning system 400 described above, nozzle 118 is grounded while a voltage is applied to collector 412. However, in some embodiments, a voltage can be applied to nozzle 118 and collector 412 can be grounded. or provide another voltage. Such a configuration can generate an electrical field between nozzle 118 and manifold 412 that can facilitate polymer extrusion.

In some embodiments, the electrical, fluidic, and temperature subsystems may be integrated into a single enclosure. The subsystems may further include a security circuit to enhance user security. In addition, the electrical, fluidic, and temperature subsystems can be controlled by closed-loop control using, for example, a programmable logic controller (PLC) over an Ethernet IP protocol. Using a PLC can reduce manufacturing assembly time and allow the user to store operating parameters in memory for reproducible development. Also, by using a PLC, the system can be configured to operate when all operating parameters are within an acceptable range. The PLC may also include safety features to prevent heater overheating, control the high voltage module, and monitor system pressure. In addition, the system's PLC can have a human-machine interface (HMI) to provide stand-alone operation without the need for a PC to interact with an operator regarding operating parameters such as pressure, temperature, speed, and number of cycles, to provide to the operator feedback, errors, current program, temperatures, speeds, pressure values and voltage values.

Figures 20A-F illustrate some aspects of an exemplary implementation of the subject matter. Fusion electrospinning can be considered as an alternative polymer processing technology that can allow the fabrication of three-dimensional frameworks. Some implementations may be solvent-free and allow the use of polymers that do not dissolve easily. Some implementations may allow advances in the field of tissue engineering, where solvent retention and toxicity may be a concern. Some implementations of the current subject matter may include a melt electrospinning instrument capable of melting polymers with melting points up to 250 degrees Celsius. Some implementations can enable fusion electrospinning writing (MEW) by using an x-y stage as the pickup platform. Figure 20A illustrates the interaction between process and operating parameters for MEW, including polymer, collector, voltage, software, distance, heating element, travel speed, and flow rate. Figure 20B illustrates a schematic diagram of an MEW instrument. Figure 20C illustrates a table of polymer, molecular weight and melting temperature. Polymers include polycaprolactone (PCL), polydioxanone (PDS), polylactic-coglycolic acid (PLGA), thermoplastic polyurethane (TPU), and polystyrene (PS). Figures 20D-F illustrate generated frameworks constructed using an example MEW system, illustrating the morphology, resolution, and versatility of different structures and materials.

Figure 21 shows a table detailing certain technical specifications of an embodiment of an electrospinning system that may be similar to electrospinning system 400.

In some implementations, the control system conditions and buffers the signal for a robust industrial scheme (0-10 Volts). Data acquisition hardware is used and values are provided to a software module, which drives the outputs through an analog output (for example, 12-bit pulse width modulation). Alarms, limits, maximum, minimum and average values can be calculated.

In some implementations, the fusion head assembly can move in more than x, y, z directions. For example, the fusion head assembly can move in any specified coordinate system, such as polar, spherical, or cylindrical coordinates. Furthermore, the fusion head assembly can move in 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and/or more directions. In some implementations, the x and y directions are 90 degrees apart, and the z direction is 90 degrees apart from a plane formed in the x and y directions. In some implementations, the manifold is moved such that the movement of the fusion head assembly is relative to the manifold. In some implementations, the manifold can also be cylindrical and rotate around its own central axis.

Other embodiments are within the scope and spirit of the disclosed subject matter.

The techniques described herein may be implemented using one or more modules. As used herein, the term "module" refers to computer software, firmware, hardware, and/or various combinations thereof. However, at a minimum, Modules should not be construed as software that is not implemented in hardware, firmware, or recorded on a writable storage medium readable by a non-transient processor (ie, Modules are not software per se). In fact, "module" should always be interpreted to include at least some non-transient physical hardware, such as a part of a processor or a computer. Two different modules can share the same physical hardware (for example, two different modules can use the same processor and the same network interface). The modules described herein can be combined, integrated, separated and/or duplicated to support various applications. Furthermore, a function described herein as being performed in a particular module may be performed in one or more modules and/or by one or more devices instead of, or in addition to, the function performed in the particular module. Furthermore, the modules can be implemented on multiple devices and/or other components local or remote from each other. Furthermore, modules can be moved from one device and added to another device, and/or can be included in both devices.

One or more aspects or features of the subject matter described herein may be embodied in digital electronic circuits, integrated circuits, specially designed application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), hardware, firmware , software and/or combinations thereof. These various aspects or features may include implementation in one or more computer programs that are executable and/or interpretable in a programmable system that includes at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from , and to transmit data and instructions to, a storage system, at least one input device and at least one output device. The programmable system or computer system may include clients and servers. A client and a server are generally remote from each other and typically interact through a communications network. The client and server relationship arises by virtue of the computer programs running on the respective computers and having a client-server relationship with each other.

These computer programs, which may also be referred to as programs, software, software applications, applications, components, or code, include machine instructions for a programmable processor and may be implemented in a high-level procedural language, scripting language, or scripting language. object-oriented programming, a functional programming language, a logic programming language, and/or assembly/machine language. As used herein, the term "machine-readable medium" refers to any computer program product, apparatus, and/or device, such as magnetic disks, optical disks, memory, and programmable logic devices (PLDs), used for providing machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term "machine readable signal" refers to any signal used to provide machine instructions and/or data to a programmable processor. The machine-readable medium may store such machine instructions in a non-transient manner, such as in the manner that a non-transient solid-state memory or magnetic hard disk or any equivalent storage medium would. The machine-readable medium may alternatively or additionally store such machine instructions in a transient manner, such as in the manner of a processor cache or other random access memory associated with one or more physical processor cores.

To provide interaction with a user, one or more aspects or features of the subject matter described herein may be implemented on a computer having a display device, such as a cathode ray tube (CRT) or a screen. liquid crystal (LCD) or light-emitting diode (LED) monitor to display information to the user, and a keyboard and pointing device, such as a mouse or trackball, by which the user can provide information to the computer. Other types of devices may also be used to enable interaction with a user. For example, the feedback provided to the user can be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and user input may be received in any form, including, but not limited to, acoustic, voice, or tactile input. Other possible input devices include, but are not limited to, touch screens or other touch-sensitive devices, such as single or multi-point resistive or capacitive touch panels, voice recognition hardware and software, optical scanners, optical pointers, digital images and associated interpretation software, and the like.

In the descriptions above and in the claims, phrases such as "at least one of" or "one or more of" may appear followed by a joint list of elements or features. The term "and/or" may also appear in a list of two or more elements or characteristics. Unless otherwise explicitly or implicitly contradicted by the context in which it is used, such phrase is intended to mean: any of the listed items or features individually or any of the listed items or features in combination with any of the others listed items or features. For example, the phrases "at least one of A and B";"one or more of A and B"; and "A and/or B" are each intended to mean: "A alone, B alone, or A and B together." Also a similar interpretation is intended for lists that include three or more elements. For example, the phrases "at least one of A, B, and C";"one or more of A, B, and C" and "A, B, and/or C" mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together." Furthermore, the use of the term "based on", above and in the claims, is intended to mean "based at least in part on", so that a feature or element not mentioned is also permitted.

The subject matter described herein can be incorporated into systems, apparatus, methods and/or articles depending on the configuration desired. The implementations set forth in the description above do not represent all implementations consistent with the subject matter described herein. Instead, they are merely a few examples consistent with aspects related to the described subject matter. Although some variations have been described in detail above, other modifications or additions are possible. In particular, other features and/or variations may be provided in addition to those set forth herein. For example, the implementations described above may be directed to various combinations and sub-combinations of the features described and/or combinations and sub-combinations of additional features described above. Furthermore, the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or the sequential order, to achieve the desired results. Other implementations may be within the scope of the following claims.

Claims (15)

1. A system, comprising: a manifold including load sensors attached thereto, the manifold configured to receive an extruded polymer; Y an electrospinning melt head assembly positioned above the manifold and configured to extrude the polymer, wherein the electrospinning melt head assembly and/or the manifold are configured to move, the melt head assembly including an assembly syringe assembly and at least one heating element configured to supply heat to the syringe assembly, the syringe assembly comprising: a syringe including a conduit extending from a proximal end, the conduit configured to receive the polymer, and a nozzle configured to allow the polymer to pass therethrough. 2. The system according to claim 1, wherein the syringe assembly further comprises: a plunger sized and shaped to be slidably received within the conduit such that distal movement of the plunger causes extrusion of the polymer; wherein the system further comprises a plunger drive system configured to supply a mechanical force to drive the plunger. 3. The system according to claim 2, further comprising: an imaging system configured to monitor polymer extrusion; Y a probe configured to measure the intensity of an electric field between the nozzle and the collector. 4. The system according to claim 3, further comprising a control and processing system configured to receive signals from the plunger drive system, the imaging system, the load sensors and the probe, and to control the position of the electrospinning melt head assembly, the force applied to the plunger, a collector voltage, and a rate of polymer extrusion. 5. The system according to claim 4, wherein the extrusion rate is controlled to follow a ground sinusoidal profile, or the extrusion rate is between 0.1 grams/hour and 10 grams/hour, such as 0.1 grams/hour, 0.2 grams/hour, 0 .3 grams/hour, 0.4 grams/hour, 0.5 grams/hour, 0.6 grams/hour, 0.7 grams/hour, 0.8 grams/hour, 0.9 grams/hour, 1, 0 grams/hour, 2.0 grams/hour, 3.0 grams/hour, 4.0 grams/hour, 5.0 grams/hour, 6.0 grams/hour, 7.0 grams/hour, 8.0 grams/hour, 9.0 grams/hour or 10.0 grams/hour. 6. The system according to claim 4, wherein the collector voltage is between 0 and 20 kV, 1 kV, 2 kV, 5 kV, 10 kV, 15 kV, 20 kV, 25 kV, 30 kV or 40 kV, or the system further comprises a voltage source that provides a maximum current to collector 0.01 mA, 0.1 mA, 0.18 mA, 0.2 mA, 0.3 mA, 0.6 mA, 1.0 mA, 10 mA or 100 mA. 7. The system according to any one of the preceding claims, further comprising: a drive system including a pump configured to supply a pressure within the syringe by means of a gas, or a support assembly that retains the electrospinning fusion head assembly or the manifold. The system according to any one of the preceding claims, wherein the syringe assembly includes, a plunger including at least one sealing element disposed on an outer surface thereof, a first conduit extending from a first opening at a proximal end of the syringe assembly, the passageway having a size and shape necessary to slidably receive the plunger such that the at least one sealing element on the plunger forms a seal with a wall defining the first passageway, and a second opening at a distal end, the second opening being fluidly coupled to the first conduit, the second opening being sized and shaped to resealably receive the nozzle portion therein. The system of claim 8, further comprising a heater assembly retaining the at least one heating element, the heater assembly having a second conduit extending from a proximal end thereof, the second conduit having a size and shape necessary to receive the at least a part of the syringe assembly. 10. The system according to claim 9, (a) wherein the at least one heating element surrounds the second conduit; I (b) wherein the heating element is positioned within a lower half of the heater assembly; and/or (c) the system further comprising an insulation sleeve, the insulation sleeve having a third conduit configured to receive the syringe assembly and the at least one heating element. 11. A method comprising: applying power to a heating element of the system of any one of the preceding claims to generate heat for transfer to the polymer and to melt the polymer within the syringe; measuring a temperature associated with the polymer; applying a voltage to the collector to generate an electric field across a gap between the collector and the nozzle that is releasably coupled to the syringe; moving the nozzle and/or the manifold to pass the nozzle over a portion of the manifold at least once; Y apply force to a proximal end of a plunger that is slidably disposed on the syringe to force the plunger toward the nozzle, thereby forcing a portion of the polymer out of the nozzle and into the electric field so as to create a stream of polymer that is extends from the nozzle, where the polymer stream cools and forms fibers on the way from the nozzle to the manifold. 12. The method according to claim 11, (i) the method further comprising adjusting the size of the gap with each pass of the nozzle over a given point on the collector; I (ii) the method further comprising moving the nozzle and/or manifold based on a displacement profile to create small bends in the polymer flow, preferably wherein the displacement profile includes a ground sinusoidal profile; I (iii) the method further comprising using load sensors to determine a rate of polymer extrusion from the die; I (iv) the method further comprising using an imaging system in conjunction with computer vision software to determine a rate of polymer extrusion from the die; I (v) wherein the air pressure creates the force at the proximal end of the plunger; I (vi) the method further comprising reducing the air pressure enough to withdraw the plunger from the nozzle to stop, or reduce, the flow of polymer from the nozzle; I (vii) the method further comprising measuring an electric field strength, preferably wherein the method further comprises adjusting the collector voltage and/or a gap size between the nozzle and the collector as a function of the measured electric field strength. 13. The system according to any one of claims 1 to 10, wherein the electrospinning melt head assembly and/or collector is configured to move in at least one of X, Y and Z directions. 14. The system according to claim 13, further comprising a control and processing system configured to receive signals from a drive system, an imaging system, load sensors and a probe, and to control the position of the electrospinning melt head assembly, the pressure supplied to the syringe, a manifold voltage, and a polymer extrusion rate. 15. The system of claim 13, further including a support assembly that retains the electrospinning melt head assembly or manifold.