Patent Application
20230373149
The present disclosure relates to three-dimensional fabrication and shaping of microfluidic products using hydrodynamic focusing producing a microtube products.
Microfluidics devices are typically made of polymers, elastomeric materials, and combinations thereof, such as for example, a cyclo-olefin-copolymer (COC), a polymethylmethacrylate (PMMA), or a polydimethylsiloxane (PDMS) and normally consist of microfluidic channels specifically designed for manipulation, analysis and sorting of micro and nanoscale entities such as biomolecules, cells and particles. Conventional fabrication of microfluidics involves complicated precesses which are expensive and limits microfluidic channel geometry. PCT application PCT/US2017/020443 published as WO 2017/151915 A1 provides several examples of prior art methods of producing microtubes and is incorporated by reference herein in its entirety.
A variety of polymer and elastomeric materials can be used to form microtubes that typically have an inner diameter that can range from about 4 μπι (nanometers) to about 1000 μπι (micrometers) and an outer diameter that is variable and can be controlled depending on needs. The length of the microtubes can be varied depending on the end use. The microtubes can have any desired cross-sectional shape, for example, circular, rectangular, square, triangular, elliptical, star or irregular. Using these polymeric or elastomeric microtubes as basic building blocks, it is now possible to design and produce microfluidic devices providing the versatility to alter the design of the microfluidic devices without the need to redesign and fabricate the whole microfluidic device. Microtubes can be added or removed to make changes to the design of the microfluidic device which can be in two-dimensional (2D) or even 3D in configuration. The ability of the microtubes to be assembled and disassembled enables the fast patterning of microchannels.
Microtubes can be biocompatible, flexible, gas permeable and highly transparent for producing biomedical devices for various applications, e.g., flexible microfluidics, artificial skins, organs-on-chips, blood vessel and capillary network mimicking, opto-microfluidics and 3D bioreactors, among others.
Microtubes have been produced from polymers including a silicone elastomer, an ultraviolet sensitive polymer, a conductive polymer, a thermoplastic polymer, a thermoset polymer, a polyimide, a conductive rubber, or a polyurethane. The silicone elastomer can be, for instance, poly dimethyl siloxane, phenyl-vinyl silicone, methyl-siloxane, fluoro-siloxane or platinum cured silicone rubber. The ultraviolet sensitive polymer can be, for instance, MYpolymer® (a fluorinated resin with acrylate/methacrylate groups produced by MY Polymers Ltd.), styrene-acrylate-containing polymer, polyacrylate polyalkoxy silane, a positive photoresist (e.g., diazonaphthoquinone-based positive photoresist) or a negative photoresist (e.g., epoxy-based negative photoresist).
The microtubes can be used in a biomedical device or even biomedical tissue such as an artificial skin, organ-on-chip, blood vessel mimicking device, capillary network mimicking device, opto-microfluidic device, a 3D bioreactor, drug delivery device, cell stretcher, tissue engineering scaffold, micro-pump or micro-valve.
Commercially available silicone tubing is normally made by extrusion of compounded elastomers mixture, which is easily converted into 3D elastomers using a cross-linking reaction (cure). Different dies and mandrels are used to produce single-lumen tubing of various size and wall thickness (defined by their outside diameter/inside diameter, or OD/ID). Silicone tubing is normally translucent and with an inner diameter larger than 300 μπι, and fails to meet the criteria for micro/cellular scale applications. Silicon is expensive and opaque to visible and ultraviolet light, and so cannot be used with conventional optical methods of detection. Furthermore, the material is not gas permeable and is typically rigid and unsuitable in devices such as valving and actuation with peristaltic pumping is possible.
Polydimethylsiloxane, (“PDMS”), has been used to fabricate microchannels in combination with standard soft-lithography whereby a coating of liquid PDMS is applied on the walls of rectangular microchannels by introducing a pressurized air stream inside the PDMS filled microchannels. Surface tension of the liquid PDMS then forces the coating to take a circular cross-section which is preserved by baking the device under pressure until cured. This method was verified to work on microchannel networks as well as in straight channels and designed diameters can be achieved via proper curing conditions. However, it requires complicated procedures and is hard to fabricate 3D-networked channels.
Another approach to make 3D microfluidic channels is based on 3D printing technology. 3D micro-cavity networks are formed by either printing 3D sacrificial filament templates that are later leached away after prototyping or polymerizing the walls of the channel cavities and subsequent drainage of the uncured photopolymer precursor. The techniques are impaired from the limitation in low printing resolution as the dimension of the “printed” features is limited by the sizes of the nozzle and printing pressure, or by the laser beam diameters, which make it currently a main challenge to produce features smaller than 100 μπι. The rough surface of printed devices also raises a concern for high-resolution imaging in the channels.
Micro/nano-tubes can be formed (e.g., rolled up) from thin solid films of inorganic/organic materials at different positions once these films are released from their substrate. These microtubes have been used as 3D cell culture scaffolds and optofluidic sensor; however, the fabrication and the integration of the microtubes into microfluidic systems require complicated and expensive thermal deposition like Electron Beam deposition and photolithography facilities.
Microfluidic technologies such as rapid sample processing and the precise control of fluids in an assay provide a means to replace traditional experimental approaches in diagnostics and biology research.
Conventional methods for producing microtubes involves a fabrication, testing and redesign period that is long and expensive.
The microtubes of the present invention can be specifically used as elementary building blocks for microfluidic devices. The fabrication procedure involves simple mechanical apparatus and cheap common materials readily available in the lab.
The microtubes of the present invention can be easily assembled into more complex devices. It is expected that the microtubes can help to dramatically cut down the cost and time for the design, fabrication and assembly of the microfluidics systems. Microchannels with circular cross-sectional shapes are currently scarce in the market. The inability to create vascular networks has hindered progress in cardiovascular tissue engineering and organs-on-chip systems. Current micro-channels usually have a rectangular cross-section when fabricated using the conventional fabrication method and the fluid moving inside such channels does not mimic that of the parabolic-flow profile seen in that of circular cross-section tubes such as that of blood vessels. In the low Reynolds number flow, the velocity and shear stress distribution is expected to be more isotropic in a circular tubular channel than a rectangular one with straight steep walls. The cells flowing inside the latter would experience different mechanical stress depending on their relative positions in the cross-section and due to the anisotropic flow field, leading to disparate cellular activities. The microtubes of the present invention can have a range of cross-sectional shapes including circular shapes with inner diameter ranging from about 500 nm to 500 um and can be formed to taper having dimensions engineered for a particular volume at selected points along the tube. Cells in microtube will experience much more similar stress condition of a natural circulatory system than that of cuboid channels. Moreover, the velocity and vorticity fields in a circular microtube have no corner or singular regions due to the uniform circumferential wall effect.
The present invention as the basic building blocks for microfluidic systems, and significantly reduce the cost of fabrication as well as period of manufacture from weeks and days to hours. The present invention provides ease-of-use, cost effectiveness, various cross-sectional shapes, configurability, and ease in assembling complex 2D and 3D microfluidic systems.
Functional microfluidic systems can be made up of microtubes using a pre-designed template with relative ease.
Composite microtubes that can either comprise different materials or are multilayered, core-shell microtubes which can allow coating of these microtubes depending on the needs of the users.
Additional potential applications of the microtubes of the present invention include, but are not limited to, opto-microfluidics devices, organs-on-chips systems, micro-pumps/valves for fluidic controls, controlled drug delivery systems, cell stretchers and tissue engineering scaffolds.
A method for forming extruded microtube devices and products having a hollow portion utilizing a hydrodynamic nozzle, a curable fluid, and a core fluid to form flexible polymer based microtubes having an inner diameter ranging from 500 nanometers to 500 micrometers and also continuous microtubes having a varying inner diameter ranging from about 500 nanometers to 500 micrometers. The outer diameter can be variable and have a cross-sectional shape that is circular, rectangular, square, triangular, elliptical, star, irregular, curved, or formed within a solid block of material.
Hydrodynamic focusing is a scientific concept for creating a flow of an outer “sheath” fluid surrounding a core fluid within a closed tube or channel.
Hydrodynamic focusing is involved in microfluidic applications such as ultra-fast mixers, micro-reactors, and cytometry as a technique for counting, examining and sorting microscopic particles suspended in a stream of fluid, and micro fabrication. Chemical synthesis is faster and small volumes and high area to volume ratios offer an advantage over conventional analysis methods.
Hydrodynamic focusing is described by Navier-Stokes equations for 3-dimensional flow, and various trends and approximations (described below) have been developed to describe the behavior of the fluids. Both the sheath and the core fluid are laminar in flow, and Reynolds numbers between 1-10 are generally preferred to create continuous core flow (Spatiotemporal instability of a confined capillary jet, Herrada M A, Gañãn-Calvo A M, Guillot P. Phys. Rev.E.2008; 78:046312). The diameter of the inner fluid is determined by the ratio of viscosities, flow rates, geometry of the surrounding channel prior to ejection from the channel, and the continuous phase capillary number (for the sheath flow with respect to the core fluid). For a given set of fluids, the result is that by adjusting the flow rate, one can adjust the cross-sectional diameter of the core fluid and alter the output.
Hydrodynamic focusing is dominated by three elements: 1) The ratio of the core viscosity to the sheath viscosity; 2) continuous phase capillary number for the core flow; and 3) the geometry of the structure through which both fluids flow. It is theorized that inertia is an important factor with regards to the transition between jetting, which is continuity of the core diameter, and droplet formation (Spatiotemporal instability of a confined capillary jet, Herrada M A, Gañań-Calvo A M, Guillot P. Phys. Rev. E. 2008; 78:046312 and Stability of a Jet in Confined Pressure-Driven Biphasic Flows at Low Reynolds Numbers, Guillot P, Colin A, Utada A S, Ajdari A. Phys. Rev. Lett. 2007; 99:104502).
The viscosity ratio of μd/μc (where μd is the viscosity of the core fluid and μc is the viscosity of the sheath fluid) is useful because as this ratio decreases, the dripping regime increases. There is a transitional regime between droplet formation and jetting (continuous core flow) (Nunes J K, Tsai S S, Wan J, Stone H A. Dripping and jetting in microfluidic multiphase flows applied to particle and fiber synthesis. J Phys D Appl Phys. 2013; 46(11):114002. doi:10.1088/0022-3727/46/11/114002).
The continuous phase capillary number is:
where μc is the viscosity of the sheath fluid, Uc is the velocity of the sheath fluid, and γ is the interfacial energy. There is currently insufficient data to correlate a Cac number to the transition between droplet formatting and jetting (Nunes J K, Tsai S S, Wan J, Stone H A. Dripping and jetting in microfluidic multiphase flows applied to particle and fiber synthesis. J Phys D Appl Phys. 2013; 46(11):114002. doi:10.1088/0022-3727/46/11/114002). As the Cac number increases, the core flow moves to jetting. The Cac can also be increased by lowering the interfacial energy by techniques such as adding surfactants to the fluids, creating partially miscible fluids (Nunes J K, Tsai S S, Wan J, Stone H A. Dripping and jetting in microfluidic multiphase flows applied to particle and fiber synthesis. J Phys D Appl Phys. 2013; 46(11):114002. doi:10.1088/0022-3727/46/11/114002).
For flow within a cylinder, the radius of the core fluid can be estimated as: the radius of the core fluid and R is the channel radius (Jeong W, Kim J, Kim S, Lee S, Mensing G, Beebe D J. Lab Chip. 2004; 4:576-580).
A the experimental level, a filament was created by using a two-component mixture The sheath fluid contained 3% benzoyl peroxide. The polymerizable resin was polyethylene glycol 400 diacrylate. (Book, 3D Printed Microfluidic Devices, edited by Savas Tasoglu, Albert Folch, MDPI AG, 12/21/2018, pg 19). This approach is not at all similar to the present disclosure, but demonstrates the desire to create three-dimensional shapes by using hydrodynamic methods.
The present disclosure provides a method and apparatus for forming extruded shapes having at least a hollow portion using a hydrodynamic nozzle, a curable fluid, and a focusing fluid. The extruded shapes may form a tube or plurality of tubes in a bundle or porous substrate. The ability to form concentric tubes and complex shapes provides a means forming high strength materials controlled release materials, and self-repair materials, etc.
The apparatus comprises a hydrodynamic nozzle, a curing system, a material bed, a control system and optionally a pressure system and a fluid drain system. The method comprises simultaneously introducing a curable sheath fluid and a core fluid from the hydrodynamic nozzle to form a concentric extrusion, depositing at least a portion of the concentric extrusion on the material bed, and causing relative motion between the hydrodynamic nozzle and the material bed to form an extruded shape. The method further comprises curing or partially curing part or all of the external curable fluid. The method may optionally introduce the concentric extrusion to pressure from the pressure system to remove the internal core fluid from the external curable fluid, and may optionally receiving the core fluid into the fluid drain system.
The present invention utilizes a magnetic material or material such as a ferro-fluid as a core fluid which is susceptible to magnetic fields to change the shape of the inner tube diameter. Ferro fluids are composed of very small nanoscale particles (diameter usually 10 nanometers or less) of magnetite, hematite or some other compound containing iron, and a liquid (usually oil) to disperse them evenly within a carrier fluid to contribute to the overall magnetic response of the fluid. The composition of a typical ferro fluid is about 5% magnetic solids, 10% surfactant and 85% carrier, by volume. Particles in Ferro fluids are dispersed in a liquid, often using a surfactant, and thus Ferro fluids are colloidal suspensions. True Ferro fluids are stable. This means that the solid particles do not agglomerate or phase separate even in extremely strong magnetic fields. Common ferro fluid surfactants are soapy surfactants used to coat the nanoparticles including, but are not limited to oleic acid, tetramethylammonium hydroxide, citric acid, soy lecithin, and combinations thereof. These surfactants prevent the nanoparticles from clumping together, so the particles cannot fall out of suspension. The addition of surfactants (or any other foreign particles) decreases the packing density of the ferro particles while in its activated state, thus decreasing the fluid's on-state viscosity, resulting in a “softer” activated fluid. The viscosity of ferrofluid is relatively low between 1-10 centipoise. Alternatively, the present invention uses other fluids with a much higher viscosity that enables longer stable streams than lower viscosity fluids and with a specific gravity greater than that of the sheath fluid including glycerin and food products such as molasses.
Chemicals, light, heat, viscosity, pH, radiation, and exposure to gases such as air can affect curing of some substrates; however, it is advantageous to be able to change the shape of the extruded property by external forces without effecting the chemical structure of the core or sheath materials.
The present invention to use process manipulation to provide a process whereby fluid streams are acted upon using externally applied forces including but not limited to magnetic, acoustic, heat, light, mechanical vibration, and mechanically induced deflection to produce defined features and shaping of the internal walls of the microtubes and cavities in the cured solids.
It is an object of the present invention to cure the tubes in free space outside of the channel versus conventional technology to cure the tubes or fibers inside of a channel.
It is an object of the present invention to rely on gravity to taper and focus the internal stream to create a cylinder that is unbounded by a physical surface.
It is an object of the present invention for the gravity focusing effect to be applicable when the outer fluid necks down to a smaller diameter, whereby the present invention having a core fluid results in the fluid diameter necking down as well.
It is an object of the present invention to cure the polymer after it exits the microfluidic channel as opposed to conventional processes which cure the polymer before it exits the microfluidic channel.
It is an object of the present invention to focus the core material into very small diameters generating micron and/or submicron tubes structures, (as small as 200 nm have been achieved).
It is another object of the present invention to make tubes with core materials of larger diameters of at least up to 2 mm, limited only by the nozzle design.
It is another object of the present invention to make tapered core diameters.
It is another object of the present invention to form a microtube whereby the resulting inner diameter of the tube has a superior surface as compared to polished, drawn, traditional micro machined, injection molding, extruding and other methods (1-5 nm Ra which is a mirror finish) because the process essentially molds the sheath fluid around a core fluid and the core fluid has a very smooth surface roughness (molded parts take on the surface roughness of the molds used to make them).
It is another object of the present invention to form microsized core diameters tubes whereby the tubes can be further processed into microfluidic chips (2D networks of channels) and microfluidic bricks (3D networks of channels) by molding the tubes into a larger matrix of the UV curable material.
It is an object to product a microtube having a selected wall dimension, bore, and curvature.
It is an object of the present invention to produce a microfluidic product including precision nozzles, microfluidic chip component, capillary and sampling devices and components, precision instrumentation components (viscosity devices), textiles (hollow and solid acrylate fibers), and toys and home and office goods.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to about 100:1.
It is an object of the present invention to form a tapered microtube with inner surface roughness about 2 to 5 nm.
It is an object of the present invention for form a tapered microtube with inner surface roughness about 6 to 20 nm.
It is an object of the present invention to form variations of the tapered microtube wherein the polymer selected is relevant to fabrication method and selected from the group comprising an ultraviolet reactive setting polymer, a chemically reactive setting polymer, a thermoplastic polymer, and a thermoset polymer.
It is an object of the present invention to form variations of the tapered microtube formed from a polymer which is transparent, translucent, or opaque.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube comprises a taper geometry wherein the tapered microtube inner diameter surface is continuously increasing from the small end to the large end with the change of diameter from small to large end generally following a parabolic curve with continuously changing curvature radius, up to a maximum infinite radius at either or both ends.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube comprises a taper geometry is smoothly decreasing then increasing again in a single section or a multiplicity of sections, while the overall primary taper shape increases in inner diameter from smaller at one end to larger at the other end.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube comprises a taper geometry having a tapered microtube inner diameter axis is that is coaxial with outer diameter axis.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube comprises a taper geometry having a tapered microtube inner diameter axis is that is not coaxial with outer diameter axis.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube comprises a taper geometry having a tapered microtube inner diameter axis is coaxial with the outer diameter axis in some sections and not coaxial with the outer diameter in other sections.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube overall length is from about 5 mm to about 1 m.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube outer diameter is from about 10 um to about 20 mm.
It is an object of the present invention to form variations of the tapered microtube for use in biotechnology applications.
It is an object of the present invention to form extruded microtube products having a hollow portion utilizing a hydrodynamic nozzle, a curable fluid, and a core fluid to form a flexible polymer based microtube(s) having an inner diameter ranging from about 500 nm to 500 um and in particular a continuous microtube having a varying inner diameter ranging from about 500 nm to 500 um. The outer diameter can be variable and have a cross-sectional shape that is circular, rectangular, square, triangular, elliptical, star, or irregular or block of material having a plurality of microtubes therein of a selected diameter and/or curvature.
It is an object of the present invention to form variations of the tapered microtube wherein the microtube is made reusable by flushing with water or water-surfactant mixture heated up to a temperature of 100° C. or flushing with common solvents or organic compounds.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to about 100:1, forming a tapered microtube with inner surface roughness about 2 to 5 nm and having an inner surface roughness about 6 to 20 nm.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to about 100:1, forming a tapered microtube with inner surface roughness about 2 to 5 nm and having an inner surface roughness about 6 to 20 nm, wherein said microtube(s) are embedded in a polymer of a particular size, shape, thickness or form suitable for use with another device.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to about 100:1, forming a tapered microtube with inner surface roughness about 2 to 5 nm and having an inner surface roughness about 6 to 20 nm, further including means for cooperative permanent or temporary engagement with other devices providing a fluid tight connection.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to 25 about 100:1, forming a tapered microtube with inner surface roughness about 2 to 5 nm and having an inner surface roughness about 6 to 20 nm, further including means for cooperative permanent or temporary engagement with other biotechnology microfluidic devices selected from the group comprising a micro nozzle, a micro-nozzle with in-nozzle mixing effect, a micro flow restrictor, a micro aspiration tip, a micro dispenses tip, a reagent, a microsample delivery path, a cell aligner, a cell, protein or particle sorter.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to about 100:1, forming a tapered microtube with inner surface roughness about 2 to 5 nm and having an inner surface roughness about 6 to 20 nm, wherein the tapered microtube is a component of a precision instrument.
It is an object of the present invention to form a tapered microtube comprising a polymer, with internal circular cross section, the tapered microtube having an inner diameter that is smaller at one end increasing to larger at the other end, with the smaller end inner diameter measuring about 500 nm to about 500 um, the larger end inner diameter measuring about 50 um to about 10 mm, the larger end to smaller end inner diameter ratio about 5:1 to about 100:1, forming a tapered microtube with inner surface roughness about 2 to 5 nm and having an inner surface roughness about 6 to 20 nm, wherein the tapered microtube is a component of a precision instrument and incorporates at least one of the following components such as a micro nozzle, a micro nozzle with in-nozzle mixing effect, a micro flow restrictor, a micro aspiration tip, a micro dispense tip, and a micro cooling fluid, heating fluid, or lubrication fluid delivery path.
It is another object of the present invention to incorporate tapered microtubes in microfluidic chips utilizing a tapered flow channel and/or a tapered flow channel which may provide residence time and/or reservoir necessary to supply microchip capillary capabilities for passive or zero dead volume fluid applications, whereby the chip includes integrated tubing that connects directly to board providing low volume automated flows.
It is another object of the present invention to incorporate tapered microtubes in microfluidic chips utilizing a tapered flow channel and/or a tapered flow channel which may provide residence time and/or reservoir necessary to supply microchip capillary capabilities for passive or zero dead volume fluid applications, whereby the chip includes integrated circuitry and tubing that connects directly to the process components and is attachable to conventional circuit boards.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
It is to be understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but these are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present disclosure. It is to be understood that the present disclosure is not limited in its application to microfluidic applications set forth in the following description. The present disclosure is capable of other embodiments and of being used in various applications.
Reference to documents made in the specification is intended to result in such patents or literature cited are expressly incorporated herein by reference, including any patents or other literature references cited within such documents as if fully set forth in this specification.
It is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Further, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
Any extruded shape, even if extruded onto a planar surface, is considered “three-dimensional” since the extrusion has a thickness, and additional process disclosed herein may cause a varying thickness.
The term “sheath fluid” is interchangeable with “focusing fluid”.
By controlling the core fluid and sheath fluid volume flow rates, the dimensions of the extrusions can be altered without the application of physical changes to the apparatus.
There is also shows a material bed 140 for receiving the extrusion 50. Extrusion 50 is normally flexible prior to curing. Material bed 140 provides a surface for forming 2-dimensional (2D) and three-dimensional (3D) shapes. A material bed axis 145 provides three-degrees of freedom for forming shapes from extrusion 50. These include x-, y-, and z-translation. Having two separate axes (115 and 145) enables greater flexibility in forming shapes from extrusion 50. We therefore describe motion as “relative motion” since both axes 115 and 145 may contribute. A control system 200 provides control to all electrical systems of the machine system 100, which will be described in detail with reference to
An extruded shape that is at least partially cured in situ may be created in free space, wherein a shape may be extruded to make contact with the material bed 140 but then be moved away from the material bed 140 (in a y-direction), translated in an x- or z-direction in free space, then again making contact with the material bed 140.
For certain core fluids or certain shapes, the core fluid 15 used in the production of a concentric extrusion 50 requires removal. In some scenarios, the final shape may be cured, trimmed if needed, and any core fluid 15 may be removed using manual methods. In other scenarios, however, auto-removal of the core fluid 15 may be preferred.
Fluid removal system 160 is comprised of at least one fluid port 170 that is exposed to the top surface (as shown) of the material bed 140. A pressure system 180 enables positive or negative pressure to be applied. If more than one fluid port 170 is included, valves 190 enable pressure (positive or negative) to be applied only to the fluid port 170 that is in fluidic communication with the extrusion 50. By closing valves that are in fluid communication with any open fluid ports 170, pressure can be more efficiently directed to the extrusion 50. For some extrusions 50 that are extremely flexible, it may be preferred to at least partially cure the extrusion 50 prior to removing the core fluid 15 to avoid inflating (if positive pressure is used) or collapsing (if negative pressure is used) the extrusion 50.
In operation, the leading end of the extrusion 50 is placed in fluid communication with a fluid port 170 prior to shape formation. Curing or partial curing may occur during extrusion. Once the extrusion 50 is completed and has been severed from the hydrodynamic nozzle assembly 110, pressure may be applied using the pressure system 130. It is preferred that the severed end of the extrusion 50 be at least partially opened during application of pressure.
In
The control system 200 is supplied power by a power supply 280. The control system 200 may include a communication interface or module 220 coupled to a shape processing module 230. The shape processing module 230 may be communicatively coupled to an extrusion module 240, a positioning module, 250, a curing module 260, a pressure module 270, and a ferro module 275.
The shape source 210 may be any type of device capable of transmitting data related to a shape file to be formed by machine system 100 in cooperation with the shape processing module 230. The shape source 210 may include a general-purpose computing device, e.g., a desktop computing device, a laptop computing device, a mobile computing device, a personal digital assistant, a cellular phone, etc. or it may be a removable storage device, e.g., a flash memory data storage device, designed to store data such as shape data. If, for example, the shape source 210 is a removable storage device, e.g., a universal serial bus (USB) storage device, the communication interface 220 may include a port, e.g., a USB port, to engage and communicatively receive the storage device. In another embodiment, the communication interface 220 may include a wireless transceiver to allow for the wireless communication of shape data 215 between the shape source 210 and the control system 200. Alternatively, the communication interface 220 may facilitate creation of an infrared (IR) communication link, a radio-frequency (RF) communication link or any other known or contemplated communication system, method or medium.
The communication interface 220 may be configured to communicate with the shape source 210 through one or more wired and/or wireless networks. The networks may include, for example, a personal area network (PAN), a local area network (LAN), a wireless local area network (WLAN), a wide area network (WAN), etc. The networks may be established in accordance with any number of standards and/or specifications such as, for example, IEEE 802.11x (where x indicates a, b, g and n, etc.), 802.16, 802.15.4, Bluetooth, Global System for Mobile Communications (GSM), code-division multiple access (CDMA), Ethernet, etc.
The shape processing module 230 may receive the shape data 215 from the communication interface 220 and process the received shape data 215 to create a shape job 225 for use within the machine system 100. Alternatively, the processing of the shape data 215 may be performed by the shape source 210 or other device or module and the resulting shape job 225 may be communicated to the communication interface 220. The processed shape data 215 and/or shape job 225 may, in turn, be provided to the shape processing module 230. The shape processing module 230 can cache or store the processed shape data 215 or may communicate the shape data 215 in real-time for shape job 225 creation.
The shape processing module 230 sends the shape job 225 to the extrusion module 240, positioning module 250, curing module 260, and optionally the pressure module 270 if using a pressure system 180 with the material bed 140, and optionally the ferro module 275 if ferro fluid is used as the core fluid 15. The extrusion module 240 controls the extrusion parameters based on material properties of the sheath fluid 25 and core fluid 15, and desired shape outcome. The extrusion module 240 is configured to cooperate with positioning module 250, which includes positioning data for the nozzle axis 115 and material bed axis 145. Alternately, if the mandrel 150 is used instead of the material bed 140, the positioning module 250 includes positioning data for the nozzle axis 115 and mandrel axis 155. Position sensors 290 provide feedback for closed-loop location information. Sample position sensors 290 include optical encoders (not shown) that may be linear or rotary strips having scale markings that are detected by optical sensors. An analog or digital signal may provide position feedback based on the number of scale markings detected by the optical sensors. Pressure module 270 receives information from the shape processing module 230 whether core fluid 25 will be removed by pressure or not. If core fluid 25 is to be removed, the magnitude and direction of pressure (such as low vacuum pressure or moderate positive pressure) will be determined based on the anticipated properties of the extrusion 50 at the time pressure is to be applied. The pressure module 270 will also control any valves 190 if multiple fluid ports are available for use. If there is only one fluid port, there is no need for valves 190.
As shown in
Temperature controlled first sheath conduit 30 and second core conduit 40 deliver the sheath fluid 25 and core fluid 15 respectively from sheath fluid supply 125 and core fluid 130 to the hydrodynamic nozzle assembly 110. Viscosity of the fluids is lowered by heating and increased by cooling.
The funnel contains the sheath fluid 25 with a nozzle on the inside that delivers the core fluid 15. Both fluids then exit the nozzle of the funnel together coaxially and both fluids are reduced in diameter due to the gravity focusing effect. Permanent magnet used when one uses a ferro fluid as the core fluid is greater when use do change the shape of the inner tube diameter. UV curing light with 405 nm wavelength can be used to cure the falling sheath fluid 25 in one preferred embodiment. A material bed such as a substrate mounted onto a movable drive (xyz stage motion) to catch the cured stream and/or to allow build up and a different channel to create patterns.
By controlling the core fluid 15 and sheath fluid 25 volume flow rates, the dimensions of the extrusions can be altered without the application of physical changes to the apparatus.
The heated filling hose for the sheath fluid and the core fluid and the holder for the outer funnel. Heating the hose controls the viscosity of the fluids. The higher the viscosity the longer the manufactured tube body. The lower the viscosity, the less bubbles are produced in the tube body. The holder for the outer funnel is adjustable in the x and y directions so as to make sure the inner nozzle is perfectly centered in the outer funnel nozzle so that the core stream is centered in the sheath steam such that the inner and outer diameters of the manufactured tube are concentric as shown in
The pressurized pot delivering sheath fluid to the funnel, and showing the temperature control system for the sheath and core fluids to control the viscosity, and the insulation covering the heating element and the delivery hose for the core/sheath fluids as shown in
The hydrodynamic nozzle assembly 110 has a core fluid steam 15 introduced into a clear outer sheath fluid stream 25 wherein the inner blue core fluid 15 is surrounded by the clear liquid sheath fluid 25. The diameter of the sheath fluid 25 is the same as the nozzle at the nozzle exit 108 and quickly necks down to about 1/10 of that within a short distance and both the core fluid 15 and coaxial sheath fluid 25 continue to taper only slightly thereafter and the using this gravity focusing effect and curing the UV curable sheath fluid, hollow tubes with inner diameters as small as 200 nm have been created.
The following examples describe preferred embodiments of the intention. Other embodiments within the scope of the claims herein will be apparent to one skilled in the art from consideration of the specification or practice of the invention as disclosed herein. It is intended that the specification, together with the examples, be considered exemplary only, with the scope and spirit of the intention being indicated by the claims which follow the examples. The present disclosure will be more readily appreciated with reference to the example which follows.
An extruded shape in the form of an “S” is desired which is shown in
The sheath fluid 25 is capable of being partially cured using typical curing wavelengths. The curing system 120 is a 35-watt UV LED light ring attached to the hydrodynamic nozzle assembly 110. The material bed 140 includes a top surface of transparent glass. Below the material bed 140 is a 35-watt UV LED array.
The extruded shape was drawn and converted to a vector file, which is the shape data 215. The shape data 215 was received by the communication interface 220 and sent to the shape processing module 230 for processing into a shape job 225. The shape job 225 was sent to the extrusion module 240, the positioning module 250, and the curing module 260.
The machine system 100 was then activated, the hydrodynamic nozzle assembly 110 was preheated to 100° F. (37.8° C.), and sheath fluid 25 and core fluid 15 were introduced to the hydrodynamic nozzle assembly 110 via first conduit 30 and second conduit 40, respectively. The hydrodynamic nozzle assembly 110 moved to a close proximity (within 25 mm) to the material bed 140, which is planar. Extrusion from the hydrodynamic nozzle assembly 110 was activated, and the nozzle axis 115 and material bed axis cooperated to produce relative motion between the hydrodynamic nozzle assembly 110 and the material bed 140 that resulted in an “S” shape being extruded onto the material bed 140. After extrusion, the hydrodynamic nozzle assembly 110 was moved to a central position above the shape, and the curing system 120 was activated. Both the UV LED light ring and the UV LED array were activated simultaneously for 12 seconds (10 seconds minimum and a safety margin of 2 seconds). After 12 seconds, the curing system 120 was deactivated, and the hydrodynamic nozzle assembly 110 and the material bed 140 were returned to a home position, enabling the user to manually remove the shape for trimming and removal of the core fluid 25.
The sheath fluid 25 used was a polyacrylate. The core fluid was water. The inner diameter of the sheath fluid was 0.03 mm (30 microns). A random three-dimensional shape was created as shown in
The sheath fluid 25 used was a dipentaerythritol pentaacrylate. The core fluid was an electro rheological fluid EMG 700 from Ferrotec USA Corporation, located in Santa Clara, California. The inner diameter of the sheath fluid was 0.03 mm (30 microns). A random three-dimensional shape was created according to aspects of the present disclosure. See
This method uses co-flow of two immiscible fluids that exit a nozzle, chute, ledge, beaker edge or the like (all termed “nozzle”), simultaneously, and one totally encased by the other, but not necessarily at the same flow rates. The motive force for the co-flowing fluids from the “nozzle” may be gravity, centrifugal force or any other body force generation method. The outer fluid is termed the sheath fluid and the inner fluid is termed the core fluid. A distinguishing characteristic of the flow from the “nozzle” is that the diameter or width of sheath fluid is reduced as it exits the “nozzle”. The core fluid, likewise, is reduced in width or diameter. This reduction in width or diameter is commonly termed “focusing”, and the motive force is a body force, like gravity, it is further termed “gravity focusing”. Gravity focusing is distinguished from the commonly used method of hydrodynamic focusing in that, hydrodynamic focusing generates co-flow from a nozzle into a constrained channel, whereas gravity focusing generates co-flow from a nozzle into unconstrained free space. A further distinguishing factor is that hydrodynamic focusing relies on surface forces (like applied pressure) to force the sheath and core fluids through converging nozzles to provide focusing, whereas gravity focusing relies upon the body force of gravity, the initial geometry of the nozzle, the sheath and core viscosities and the surface tension between the nozzle and sheath fluid at the exit to provide focusing.
The flow of material for a gravity focusing system is characterized by the jet shape and depends on the dynamic viscosity of the Newtonian fluid typically forming a concave jet, flow velocity at the nozzle resulting in a straight, vertical shape, falling height forming a vertical jet, and the flow of material application onto a moving substrate whereby the flow of material forms a convex shape.
This method further relies on the sheath fluid being comprised of a fast curing, liquid plastic that can be cured by different means but preferentially using ultra-violet light, and the core fluid being non-curable, but immiscible with the sheath fluid, so as the core and sheath fluid remain co-flowing and do not mix as the co-flowing jet travels away from the nozzle exit. The fast curing UV lights are positioned some distance below the nozzle exit and some distance away from the co-flowing sheath and core fluids. The exact distances depend upon the tubular geometry desired. As the co-flowing fluid stream passes between the UV lights they are activated such that the sheath fluid is cured into a solid plastic material. That material is then removed either as a discrete part or spooled onto a mandrel in a continuous fashion, depending upon the tube design objectives. The core fluid may remain inside the tube, may be cleaned out of the tube or replaced by another material inside the tube depending upon the design and use intent.
This method has advantages over other tube making methods in that it can be used to focus the core material into very small diameters (as small as 200 nm have been achieved). It can be used to make tubes with core materials of larger diameters, limited only by the nozzle design. Microtubes at least up to 2 mm have been achieved and the tubes can be made with tapered core diameters. Furthermore a plurality of microtubes can be bundled for higher flow rate and/or surface area or flow rate. The resulting inner diameter of the tube has a superior surface as compared to polished, drawn, traditional micro machined, injection molding, extruding and other methods (1-5 nm Ra which is a mirror finish) because the process essentially molds the sheath fluid around a core fluid and the core fluid has a very smooth surface roughness (molded parts take on the surface roughness of the molds used to make them). Upon forming microsized core diameters, the tubes can be further processed into microfluidic chips (2D networks of channels) and microfluidic bricks (3D networks of channels) by molding the tubes into a larger matrix of the UV curable material.
A 100 mL beaker with approximately 25 mL of highly viscous, UV curable sheath material and 5 mL of significantly less viscous core material was used where the core material specific gravity is greater than that of the sheath material such that it remains inside the sheath material as a ball of material (doesn't float to the top and spread out). The beaker was simply tilted by hand such that the sheath material began to flow over the edge of the spout and the flow of the sheath material began to draw from the ball of the core material until a small stream of the core material formed on the inside of the sheath material, both materials co-flowing over the edge of the beaker. Due to the high viscosity and surface tension of the sheath material, a significantly tapered flow was seen from the exit of the beaker to the free stream. A hand-held radiation device, such as a UV light, was used to cure the sheath material just prior to it collecting onto a substrate such as a material bed, resulting in solid diameters of plastic tubing with micro sized inner diameters.
The plastic tubing was then cast into a larger chip of UV cured material and the inner channels were accessed by drilling and then gluing connectors in place. In this manner a microfluidic flow chip of 3D nature was created.
A funnel nozzle or an L-shaped chute can be utilized as the nozzle. The sheath fluid is maintained in the funnel or chute using a syringe pump or a pressurized pot with a hose. The core fluid is injected into the sheath fluid using a syringe pump with a syringe and a dispense tip or syringe needle depending upon the design intent. As the fluids exit the nozzle, UV curing lamps under automatic control are actuated to cure the material. The material either collects onto a substrate plate or is captured in free space and removed as a discrete tubular section. A mandrel is not yet implemented but can be used to collect the tubular section in a continuous fashion to create very long tubes of several feet in length and the length is only limited by the length of the mandrel.
As illustrated in
Gravity fed extrusion of SR399 and ferro fluid, is cured as it takes shape as shown in
Fluids streams are acted upon using other process manipulations, as well as externally applied forces (including, but not limited to, magnetic, acoustic, mechanical vibration, and mechanically induces deflection) to produce defined features and shaping of the cavities in the cured solid.
The experimental embodiment described in the examples is flexible and the apparatus is altered to provide various product configurations, including at least one or more of the following steps of:
It is contemplated and will be clear to those skilled in the art that modifications and/or changes may be made to the embodiments of the disclosure. Accordingly, the foregoing description and the accompanying drawings are intended to be illustrative of the example embodiments only and not limiting thereto, in which the true spirit and scope of the present disclosure is determined by reference to the appended claims.
The present application claims priority from U.S. application Ser. No. 17/960,120 filed on Oct. 4, 2022 and claims priority from U.S. Provisional Patent Application 63/331,253, filed Apr. 14, 2022, both of which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63331253 | Apr 2022 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17960120 | Oct 2022 | US |
| Child | 18135109 | US |
