Printer jetting mechanism and printer employing printer jetting mechanism

Abstract

To provide a three-dimensional printer for improving the quality of three-dimensional objects.SOLUTION: A three-dimensional printer is provided which comprises: an ejector device 101 comprising a passageway for allowing a print material to flow from a first end 106A to a second end 106B, where surfaces of a first electrode 110 and a second electrode 112 are exposed into the passageway; a current pulse generating system in electrical connection with the first electrode and the second electrode of a plurality of ejector conduits 106; a magnetic field source sufficiently proximate to the second end of the plurality of ejector conduits so as to generate a flux region disposed within an ejector nozzle 108 of the plurality of ejector conduits during operation of the 3D printer; and a positioning system for controlling the relative position of the ejector device 101 with respect to a print substrate 102 in a manner that allows the print substrate to receive the print material jettable from the ejector nozzle of the ejector conduits during operation of the 3D printer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to printer ejection mechanisms that can be used in printers used for additive manufacturing, which are referred to herein as three-dimensional ("3D") printers. This disclosure also relates to 3D printers that include printer ejection mechanisms. [Background technology]

[0002] Additive manufacturing, also referred to herein as three-dimensional ("3D") printing of conductive printing materials such as metals, is a known manufacturing technique. For example, three-dimensional printers for constructing 3D objects from molten aluminum and other metals are known in the art.

[0003] One such 3D printer is disclosed in U.S. Patent No. 9,616,494. The 3D printer operates by using DC pulses applied by an electromagnetic coil to eject molten aluminum droplets in response. A platen, which is the target of the droplets, translates to connect and accumulate the droplets, enabling the creation of a three-dimensional object. However, the molten aluminum droplets ejected from this 3D printer have a diameter of approximately 0.5 mm or more. This enables the production of metal parts with high capacity throughput. However, the relatively large droplet size can result in an undesirable degree of porosity in the 3D objects printed thereby, as well as uneven build surfaces, unwelded droplets, and morphological variations during production. All of these can lead to degradation of physical properties such as insufficient tensile strength, as well as problems with the appearance of the final object, and / or the inability to print objects with very fine details.

[0004] Therefore, methods and systems for improving the quality of three-dimensional objects produced from three-dimensional printers, such as liquid metal printers, would represent a step forward in this field. [Overview of the Initiative]

[0005] One embodiment of the present disclosure relates to a three-dimensional ("3D") printer. The 3D printer comprises an ejector device including a substrate and a plurality of ejector conduits on the substrate, the ejector conduits arranged in an array. Each ejector conduit includes a first end positioned to receive print material, a second end including an ejector nozzle, the ejector nozzle including a first electrode and a second electrode, and a passage for allowing print material to flow from the first end to the second end, with at least one surface of the first electrode exposed in the passage and at least one surface of the second electrode exposed in the passage. A current pulse generation system is electrically connected to the first and second electrodes of the plurality of ejector conduits. A magnetic field source is positioned sufficiently close to the second ends of the plurality of ejector conduits to generate flux regions located within the ejector nozzles of the plurality of ejector conduits during operation of the 3D printer. The 3D printer further includes a positioning system for controlling the relative position of the ejector device to the print substrate in a manner that allows the print substrate to receive printable material from ejector nozzles of multiple ejector conduits during the operation of the 3D printer.

[0006] Another embodiment of the present disclosure relates to a printer ejection mechanism. The printer ejection mechanism comprises an ejector device including a substrate and an ejector conduit on the substrate, the ejector conduit including a first end positioned to receive printing material and a second end including an ejector nozzle, the ejector nozzle including a first electrode and a second electrode and a passage for allowing the printing material to flow from the first end to the second end, the passage having at least one surface of the first electrode exposed in the passage and at least one surface of the second electrode exposed in the passage. The printer ejection mechanism further comprises a current pulse generation system electrically connected to the first and second electrodes of the ejector conduit and a magnetic field source sufficiently close to the second end of the ejector conduit to generate a flux region positioned within the ejector nozzle during operation of the 3D printer.

[0007] Another embodiment of the present disclosure relates to an ejector device. The ejector device comprises a substrate and an ejector conduit on the substrate. The ejector conduit includes a first end configured to receive printing material and a second end including an ejector nozzle, the ejector nozzle including a first electrode and a second electrode, and a passage for allowing the printing material to flow from the first end to the second end. At least one surface of the first electrode is exposed in the passage and at least one surface of the second electrode is exposed in the passage.

[0008] Please understand that the general explanation above and the detailed explanation below are for illustrative and explanatory purposes only and do not limit this instruction as requested. [Brief explanation of the drawing]

[0009] The accompanying drawings incorporated herein and constituting part of this specification illustrate embodiments of this teaching and, together with the description, serve to illustrate the principles of this teaching. [Figure 1] A schematic perspective view of a printer jetting mechanism according to one embodiment of the present disclosure is shown. [Figure 2] A schematic top view of an array of ejector conduits for a printer ejection mechanism according to one embodiment of the present disclosure is shown. [Figure 3] A schematic side view of an array of ejector conduits according to one embodiment of the present disclosure is shown. [Figure 4A] A schematic top view of an ejector conduit including multiple electrode pairs on a rail is shown. In one embodiment of the present disclosure, a current pulse generation system is shown electrically connected to the first electrode pair as part of the ejector nozzle. [Figure 4B] Figure 4A shows a schematic side view of an ejector conduit illustrating the relationship between the ejector conduit and the magnetic field source 130 according to one embodiment of the present disclosure. [Figure 5] This diagram shows a schematic side view of a printer jetting mechanism according to one embodiment of the present disclosure, in which the magnetic field source is a flux circuit including a magnet and a flux guide. [Figure 6] Shows a schematic side view of a printer ejection mechanism according to an embodiment of the present disclosure. [Figure 7] Shows a schematic perspective view of a printer ejection mechanism in which the magnetic field source is a flux circuit including a magnet and a flux guide according to an embodiment of the present disclosure. [Figure 8] Shows a schematic side view of an ejector duct array used in the printer ejection mechanism of FIG. 7 according to an embodiment of the present disclosure. [Figure 9] Shows a schematic side view of an ejector nozzle array according to an embodiment of the present disclosure. [Figure 10] Shows a schematic side view of an ejector nozzle array according to an embodiment of the present disclosure. [Figure 11] Shows an array of ejector ducts including a closed channel configuration according to an embodiment of the present disclosure. [Figure 12] Shows a schematic top view of an ejector duct for mixing printing materials according to an embodiment of the present disclosure. [Figure 13A] Shows a schematic top view of an electrode configuration for an ejector duct for mixing printing materials according to an embodiment of the present disclosure. [Figure 13B] Shows a schematic top view of an electrode configuration for an ejector duct for mixing printing materials according to an embodiment of the present disclosure. [Figure 13C] Shows a schematic side view of the ejector duct of FIG. 13B according to an embodiment of the present disclosure. [Figure 14] Shows a schematic top view of an ejector duct for mixing printing materials according to an embodiment of the present disclosure. [Figure 15] Shows a schematic top view of an ejector duct for mixing printing materials according to an embodiment of the present disclosure. [Figure 16A] An example of a schematic diagram of an ejector duct is shown. Also shown is a current pulse generation system that can be used to generate a current pulse across an electrode positioned within an ejector nozzle of the ejector duct according to an embodiment of the present disclosure. [Figure 16B]An example of a schematic diagram of an ejector nozzle is shown. Also shown is a current pulse generation system that can be used to generate current pulses across electrodes positioned within the ejector nozzle, according to one embodiment of the present disclosure. [Figure 17] A schematic cross-sectional side view of an ejector nozzle having a closed channel configuration including a vent, according to one embodiment of the present disclosure, is shown. [Figure 18A] A schematic cross-sectional view of an ejector nozzle including multiple vents according to one embodiment of the present disclosure is shown. [Figure 18B] Figure 18A shows a schematic cross-sectional view of an ejector nozzle according to one embodiment of the present disclosure. [Figure 19] This is a block diagram of a 3D printer according to one embodiment of the present disclosure. [Figure 20] This diagram shows a schematic side view of a printer ejection mechanism, according to one embodiment of the present disclosure, which includes a plurality of ejector conduits for simultaneously ejecting droplets to print a 3D object onto a printing substrate. [Figure 21] This is a flowchart of a method for ejecting printing material from a printer ejection mechanism according to one embodiment of the present disclosure. [Figure 22] This is a schematic perspective view of a 3D printer according to one embodiment of the present disclosure. [Figure 23A] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 23B] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 23C] This shows a cross-sectional side view of an array of ejector conduits according to one embodiment of the present disclosure. [Figure 24A] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 24B] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 24C] This shows a cross-sectional side view of an array of ejector conduits according to one embodiment of the present disclosure. [Figure 25A] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 25B] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 25C] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 25D] This shows a cross-sectional side view of a partially fabricated array of ejector conduits according to one embodiment of the present disclosure. [Figure 25E] This shows a cross-sectional side view of an array of ejector conduits according to one embodiment of the present disclosure. [Figure 26] An enlarged view of the side wall 143b in Figure 9, according to one embodiment of the present disclosure, is shown.

[0010] Please note that some details in these figures have been simplified, and strict structural accuracy, detail, and scale are not maintained; they are drawn to facilitate understanding of the embodiments. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of this teaching will be referred to in detail, and these embodiments are shown in the accompanying drawings. In the drawings, similar reference numerals are used throughout to designate the same elements. The following description will refer to the accompanying drawings, which form part of it and illustrate specific exemplary embodiments that can put this teaching into practice. Therefore, the following description is merely illustrative.

[0012] This disclosure covers printer ejection mechanisms including ejector devices, and 3D printers using printer ejection mechanisms. In one embodiment, any of the ejector devices described herein may be a microelectromechanical system ("MEMS"). As used herein, the terms "microelectromechanical system" or "MEMS" are defined as a device that 1) has at least one moving part or uses a non-moving part to move a fluid (e.g., liquid) through the device, and 2) can be manufactured using MEMS manufacturing techniques. MEMS manufacturing techniques include semiconductor and printed circuit board manufacturing techniques, such as film deposition, patterning (e.g., photolithography), and etching techniques.

[0013] A method using a jetting mechanism for ejecting printing material is also disclosed. The printer jetting mechanism is designed to use an electric current and a magnetic field to provide a force for ejecting the printing material, as will be described in more detail herein.

[0014] The spraying mechanisms and printing methods disclosed herein may offer one or more of the following advantages: the ability to selectively spray a wide range of metals and other conductive materials; the ability to spray a selectable droplet volume; the ability to spray small droplet sizes that enable printing of fine and / or selectable feature sizes; the ability to mix different printing materials during the spraying process; and the ability to print at relatively high throughput.

[0015] Figure 1 shows an example of a printer ejection mechanism 100 according to one embodiment of the present disclosure. The printer ejection mechanism 100 includes an ejector device 101 comprising a substrate 102 and an ejector conduit 106 on the substrate 102. As used herein, the term “on” is broadly defined to include both direct and indirect physical contact, and therefore includes, for example, situations in which an intervening layer may be formed between the ejector conduit and the substrate. As used herein, all examples of the term “on” may be optionally replaced with “directly on” unless the specification explicitly states that direct physical contact is not possible.

[0016] Any suitable substrate 102 may be used as part of the ejector device of this disclosure. Exemplary substrates include at least one material selected from insulating materials and semiconductor materials. Examples of insulating materials include polymers (e.g., epoxy or polyimide), ceramics (e.g., alumina), and glass, as well as combinations thereof such as glass polymer composites and glass ceramics. Examples of commercially available glass polymer composites include glass-epoxy laminates such as G-10, G-11, FR-4, FR-5, and FR-6, all of which are available from Corning, headquartered in Corning, New York. An example of a commercially available glass ceramic is MACOR®, also available from Corning. Examples of semiconductor materials include Group IV semiconductors (e.g., silicon, germanium, SiC, or SiGe), Group III-V materials (e.g., GaAs, GaN, GaInAs), or any other suitable semiconductor material. The substrate may be a single layer or multiple layers. In one embodiment, the surface of the substrate 102 on which the passage 106C is formed is smooth (for example, the substrate is made of a fiber-free material such as fiber-free polyimide or other fiber-free polymer, rather than a fiber-containing material such as FR4). In one embodiment, the substrate 102 has an electrically insulating surface (for example, a multilayer substrate including an electrically insulating surface layer, or the entire substrate 102 is an electrically insulating material).

[0017] An ejector device 101 comprising only a single ejector conduit 106 is shown in Figure 1, but multiple ejector conduits 106 can be arranged in an array 107 on a substrate 102 to form an ejector device 101, as indicated by the dotted line extending laterally from the single ejector conduit in Figure 1 and as shown in the top view of Figure 2. Referring to Figure 1, each ejector conduit 106 includes a first end 106A positioned to receive the printing material 104 from the feeder mechanism 113. The second end 106B includes an ejector nozzle 108. Figure 2 shows a top view of three ejector conduits 106 arranged in an array 107. The passage 106C defined by the inner surface of each ejector conduit 106 allows the printing material 104 to pass through the ejector conduit 106 from the first end 106A to the second end 106B. Figure 1 also shows part of the feeder mechanism 113 for advancing the printing material 104 (Figure 3) to be printed. The exemplary printing material 104 includes molten metal or other materials, as will be discussed in more detail below.

[0018] The ejector nozzle 108 includes at least one pair of electrodes, including a first electrode 110 and a second electrode 112, which are used to supply current to the printing material 104. Additional electrodes can be optionally used, as will be discussed in more detail herein. At least one surface of the first electrode 110 is exposed into the passage 106C, and at least one surface of the second electrode 112 is exposed into the passage 106C.

[0019] The current pulse generation system 114 shown in Figure 4A is electrically connected to at least one electrode pair of each ejector nozzle 108 of a plurality of ejector conduits 106. The current pulse generation system 114 can generate pulses of current that flow through the conductive printing material 104, mainly between the first electrode 110 and the second electrode 112, when the conductive printing material 104 is positioned within the ejector nozzle 108, thereby generating an electromagnetic force, such as a Lorentz force, on the printing material 104 to drive ejection, as will be discussed in more detail herein. By changing the current pulse characteristics, such as amplitude, pulse length, and / or pulse shape, the current pulse generation system can enable, for example, variable droplet volume and variable ejection rate of the printing material, allowing both the desired droplet volume and ejection rate to be selected for each droplet during printing.

[0020] As shown in Figures 1 and 5, the magnetic field source 130 is located close to the second end of the multiple ejector conduits 106, i.e., the ejector nozzle 108. Positioning the magnetic field source 130 close to the ejector nozzle allows for the provision of a flux region 133 (indicated by flux lines in Figures 1 and 5) within the ejector nozzle 108 between the ends of the magnetic field source 130, thereby enabling certain advantages that are more favorable than positioning the flux region further upstream. For example, the advantage is that the electromagnetic force acts on a reduced mass (e.g., only the mass of the printing material 104 within the current pulse transmission region between electrodes 110, 112 and the exit of the ejector nozzle 108), thereby enabling a higher peak ejection rate of the printing material 104 for a given current. On the other hand, if the electromagnetic force generating magnetic field source 130 and electrodes 110, 112 were located further upstream in the ejector conduit 106, the same current pulse would accelerate longer columns of the printing material 104 to a lower peak velocity. For the purposes of this disclosure, the term “flux region” or “magnetic flux region” means any region within the passage of the ejector conduit 106 that has a greater magnetic flux density due to the proximity of the magnetic field source 130 than would be in the absence of the magnetic field source 130, and the magnetic flux density is measured in air at room temperature (22°C) (e.g., in an empty passage).

[0021] The magnetic field source 130 is configured to provide a magnetic field substantially perpendicular to the flow of current through the conductive printing material 104 during the operation of the ejector nozzle 108, thereby generating an electromagnetic force, such as a Lorentz force, on the conductive printing material 104 within the ejector nozzle 108. The path of the current through the printing material 104 is determined by the arrangement of electrodes along the ejector conduit (e.g., any of the electrodes 110, 112 or other electrode pairs described herein). The magnetic field source 130 may include any suitable type of magnet 132 that can provide the desired magnetic field, such as a permanent magnet or an electromagnet.

[0022] Figure 6 shows an example where the magnetic field source 130 may be one or more magnets 132, which may be permanent magnets or other types of magnets (e.g., electromagnets) including a north pole 132a and a south pole 132b, respectively, positioned in close proximity to opposing sides of the ejector conduit 106. The north pole 132a and south pole 132b shown in Figure 6 may come from the same magnet or from two different magnets.

[0023] In another embodiment, as shown in Figure 5, the magnetic field source 130 is a flux circuit including a magnet 132 and a flux guide 134 for providing a magnetic flux density B. In one example, a first portion of the flux guide 134a is attached to the north pole 132a of the magnet 132 (Figure 5). A second portion of the flux guide 134b is attached to the south pole 132b of the magnet 132. The north pole 132a and south pole 132b may be, for example, two ends of the same magnet or two ends of two different magnets. The opposing ends of the portions of the flux guide 134a and 134b are positioned in close proximity to the ejector nozzle 108 and conduct or induce magnetic flux to immerse the ejector nozzle 108 in the desired magnetic field. The magnet 132 may be any magnetic field generating device such as a permanent magnet or an electromagnet.

[0024] For the purposes of this disclosure, the term “flux guide” can be understood as any member or other device capable of restricting the path of magnetic flux and guiding the magnetic flux to a target volume. In one embodiment, the flux guide 134 is a member comprising any suitable material for guiding the magnetic flux. As an example, the flux guide is a member comprising a material that is shaped to carry magnetic flux from a magnetic field generating device to a desired target volume and has one or both high permeability and high magnetic saturation at the operating temperature near the ejector nozzle 108. As an example, the material may have a desired magnetic saturation (e.g., about 0.1 to about 2 Tesla, such as about 0.5 to about 2 Tesla) at a desired operating temperature, such as any of the operating temperatures described herein. Examples of such materials include nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys, where the alloys may include combinations of nickel, cobalt, and / or iron, as well as other materials such as silicon (e.g., silicon iron and silicon steel). Any other type of magnetic flux guide may also be used.

[0025] When a current i (represented as a dot in Figure 5, flowing towards the back or front of the page), whose current flow is substantially perpendicular (e.g., perpendicular or within 10% of perpendicular) to the averaged direction of the magnetic field in the flux region 133 (the averaged direction shown as the magnetic flux density B), is pulsed through the conductive printing material 104 between electrodes 110, 112 in the ejector nozzle 108, a Lorentz force is generated on the conductive printing material 104 through which the current flows. For illustrative purposes, the averaged direction of the current i, shown as a dot in Figure 5, is towards the back of the page. Those skilled in the art will understand that the force realized with respect to the liquid in the ejector conduit can be calculated as the integral of i(xyz) × B(xyz) over the volume of the liquid where i and B intersect, where x, y, and z represent Cartesian coordinates describing that volume. As used herein, the term “averaged direction” means the approximate average direction of the current and the approximate average direction of the magnetic flux over the entire volume of liquid printing material in the region where i and B intersect within the ejector conduit. Those skilled in the art will understand how to determine the averaged direction of the magnetic flux density and current.

[0026] Generally speaking, the Lorentz force is proportional to the cross product of the current i and the magnetic flux density B. Therefore, as the magnetic flux density of the magnetic field increases in the region of the ejector nozzle 108 through which the current is pulsed, the Lorentz force increases on the printing material 104 given a constant current pulse amplitude. Thus, providing a higher magnetic flux density can allow for a smaller current pulse amplitude while still providing the desired ejection force for the printing material 104. In this specification, the Lorentz force is described as an example of an electromagnetic force that can be used to drive ejection, and it should be understood that any other suitable electromagnetic force can be used to drive ejection.

[0027] The magnetic flux density achieved in the current pulse region of the ejector nozzle 108 depends on the magnetic field strength of the magnetic field source 130, the proximity of the magnetic field source 130 to the current pulse region, the shape of either flux guide, and the properties of the medium through which the magnetic field extends (e.g., the type of conductive printing material 104). In one embodiment, the magnetic field source 130 is positioned relatively close to the current pulse region of the ejector nozzle 108 to provide a desired magnetic flux density. This can be achieved by positioning either the magnet 132 or the flux guide 134 of the magnetic field source 130 sufficiently close to the nozzle 108 to provide a desired magnetic flux density of about 0.1 to 2 Tesla, for example. An exemplary distance X between the magnetic field source 130 and the longitudinal axis l in the passage 106C of the ejector nozzle 108. mn (Figure 4B) includes a range of approximately 0.1 mm to 10 mm, such as approximately 0.5 mm to 5 mm or approximately 1 mm to 2 mm, X mn This is the nearest distance between 1) the longitudinal axis l of the passage 106C of the ejector nozzle 108 and 2) a magnetic field source 130 such as a magnet 132 if there is no magnetic flux guide, or a flux guide 134 if the magnetic field source 130 is a flux circuit.

[0028] The ejector nozzle 108 may operate at temperatures above the melting point of the conductive printing material being ejected. These temperatures often exceed 400°C. Such high temperatures can result in a decrease in magnetic strength and / or complete loss of magnetism for many magnetic materials. An advantage of using a flux circuit including a magnet 132 and a flux guide 134 as the magnetic field source 130 is that the magnet 132 can be kept at a distance from the ejector nozzle, thereby making it easier to keep the magnet at a lower operating temperature compared to temperatures close to the ejector nozzle 108.

[0029] If necessary, a cooling system 142 (Figure 5) for cooling the magnetic field source 130 may also be used to cool the magnet 132 (and optionally the flux guide 134) used either alone or together with the flux guide 134, for the purpose of maintaining the magnet 132 (and optionally the flux guide 134) within a desired operating temperature to avoid a decrease in magnetic field strength. Any suitable cooling system 142 may be used to cool the magnetic material, such as a forced fluid cooling system in which a cooling gas and / or coolant is circulated by a mechanical system 142d including, for example, a fan, blower, compressor, pump, radiator, or other heat exchanger, or any combination thereof. Examples of such systems include refrigeration systems, forced air systems, and systems for cooling the magnet by circulating water (e.g., a radiator and a heat conduction path from the magnetic material to the water or other fluid cooled by the radiator). In one example, the cooling system 142 may include a feedback loop 142a that includes one or more temperature sensors 142b (e.g., thermocouples) positioned close to the magnet and / or flux guide to determine the temperature of the magnet / flux guide, and a controller 142c (e.g., a manual controller or an automatic controller with a computer processor) for increasing or decreasing the cooling output of the cooling system's mechanical system 142d (e.g., a fan, blower, compressor, pump, radiator, or other heat exchanger or combination thereof) to maintain a desired temperature. Any other suitable cooling system 142 may be used to cool the magnet 132 and / or flux guide 134. In addition to, or instead of, the cooling system 142, the magnet and / or flux guide may be thermally isolated from heat from the ejector conduit by any suitable insulator. Figure 6 shows an example of a suitable insulator 139 that may include, for example, one or both of a thermal insulating material or a vacuum chamber positioned between the ejector conduit and the magnet and / or flux guide.For example, the insulator 139 may optionally include a thin vacuum gap represented by the space shown in the insulator 139, the vacuum gap being located between the outer chamber wall or layer and the magnetic field source 130, and the outer chamber wall or layer being represented by the outer line of the insulator 139.

[0030] An example of a flux circuit including magnets 132 and flux guide 134 is shown in Figure 7. The flux guide 134 is configured as a closed flux loop in all places except for a gap 136 in which the ejector nozzles 108 of array 107 (Figure 8) are positioned to allow the ejector material 104 to be ejected. The ejector nozzles 108 are positioned within the width dimension W of the ejector housing 120 so as to fit within the gap 136. H Shorter width dimension W E It is positioned within the extended portion 107a of the array 107, thereby reducing the distance between the flux guide 134 and the pulsed region in the ejector nozzle 108. This can allow for an increase in magnetic flux density in the pulsed region, which has the advantage of allowing the current to be reduced while providing the desired ejection force to the printing material, as discussed herein. For example, W E It can be in the range of approximately 0.2 mm to approximately 10 mm, or approximately 0.5 mm to approximately 2 mm, W H This can range from approximately 0.5 mm to approximately 100 mm, or from approximately 1 mm to approximately 10 mm. Another example is W E is, W H The size may range from approximately 70% to 1%, or from approximately 50% to 10%. The through conduit 138 can provide a flow of printing material 104 to the array 107 as part of the feeder mechanism.

[0031] In one embodiment, the magnetic field source 130 is not integrated with the array 107. For example, the magnetic field source 130 can be positioned proximate to the array without being incorporated within the array of ejector conduits themselves. In one embodiment, the magnetic field source 130 is positioned on the opposing side surfaces of the ejector nozzle 108, as shown, for example, in FIGS. 1 and 7, and is parallel to the length of the array of nozzles. This arrangement allows for a more dense packing of the ejector nozzles in a given row of the array since at least the magnetic field source 130 is not positioned between the ejector conduits 106 of any given row.

[0032] Referring to FIG. 4A, the ejector nozzle 108 has an inner width d that is the length of the shortest straight line between opposing electrodes 110 and 112, as shown in FIG. 4A. i has. d i If there are two or more possible values for d (e.g., if the value of d i varies along the length of the ejector nozzle 108), then d i is the smallest of the possible d i values for the ejector nozzle 108. Exemplary values for d i include, for example, from about 10 micrometers to about 1000 micrometers, from about 20 micrometers to about 500 micrometers, from about 50 micrometers to about 200 micrometers, or about 100 micrometers. In one embodiment, d i is in the range of from about 10 micrometers to less than 100 micrometers, from about 10 micrometers to about 90, 80, 70, or 50 micrometers, or from about 10 micrometers to about 25 micrometers. The length L E (FIG. 4B) (or, in the case of FIG. 16B, when multiple electrode pairs are used, the combined length of the multiple electrode pairs) can be any suitable length, such as, for example, from about 1 to about 10 times the inner width d i (e.g., diameter). The length L EExamples of preferred values ​​include approximately 10 micrometers to approximately 500 micrometers, approximately 10 micrometers to approximately 1000 micrometers, approximately 10 micrometers to approximately 5000 micrometers, or approximately 15 micrometers to approximately 100 micrometers (e.g., 90, 80, 70 micrometers or less). In one embodiment, electrodes 110 and 112 are positioned entirely within the ejector nozzle 108 and / or at the tip of the ejector nozzle 108 (e.g., the outermost position).

[0033] The ejector nozzle 108 is the outermost part of the ejector conduit 106 and has a length L that is, for example, in the range of approximately 1 to approximately 10 times the inner width di (e.g., diameter) of the ejector nozzle 108. n (Figure 8) n For example, is in the range of approximately 1 to 5 times di, approximately 1 to 3 times di, approximately 1 to 2 times di, or approximately equal to di. In one embodiment, the length L of the electrode is E The length L of the ejector nozzle is... n It is almost equal to.

[0034] Referring again to Figures 1 and 5, sufficient current is supplied to electrodes 110 and 112 to provide the desired momentum for ejecting or spraying at least a portion of the printing material 104 from the ejector nozzle 108. The amplitude and length of the current pulses can be determined by those skilled in the art.

[0035] In one embodiment, one or more of the multiple ejector conduits 106 each include a third electrode 144 and a fourth electrode 145, as shown, for example, in Figure 1. At least one surface of the third electrode 144 is exposed into the passage 106C, and at least one surface of the fourth electrode 145 is exposed into the passage 106C. In this specification, the third electrode 144 and the fourth electrode 145 may be collectively referred to as the second electrode pair.

[0036] Having multiple electrode pairs in a given path offers several advantages. One advantage is the ability to supply current in parallel through multiple leads. Supplying current to multiple electrode pairs through multiple leads can be beneficial when the series resistance of the leads exhibits a significant voltage drop (and thus requires a high-voltage current source), or when the available lead cross-section results in undesirable power dissipation. Power dissipation is proportional to the square of the current (I 2 ) is proportional to, and therefore having N electrode pairs means that the dissipation in each pair is N compared to using a single electrode pair for the same total current. 2 This potentially reduces the force. More interestingly, if the current per electrode is limited, providing the ability to select a different number of electrode pairs for each droplet of printing material being discharged can allow for the selective application of higher forces.

[0037] In one embodiment, one or more of the ejector conduits 106 each include a fifth electrode 146 and a sixth electrode 147, as shown, for example, in the rightmost ejector conduit 106 of Figure 2. At least one surface of the fifth electrode 146 is exposed into the passage 106C, and at least one surface of the sixth electrode 147 is exposed into the passage 106C. In this specification, the fifth electrode 146 and the sixth electrode 147 are collectively referred to as the third electrode pair.

[0038] The electrode pair may be configured to form a rail portion which can be used to guide molten printing material through the ejector conduit 106 by providing a side wall of the passage 106C and / or a surface which can be wettable along the length of the passage 106C, as described herein, such as by wicking the printing material. The rail may extend along the entire length of the passage 106C, or substantially the entire length. In one embodiment, referring to Figures 1 and 2, a first rail 148 and a second rail 149 are positioned close to the passage 106C such that at least a portion of the passage 106C is located between the first rail 148 and the second rail 149. The first rail 148 includes a first electrode 110 and optionally one or both of a third electrode 144 and a fifth electrode 146 (shown in Figure 2). The second rail 149 includes a second electrode 112 and optionally one or both of a fourth electrode 145 and a sixth electrode 147.

[0039] The portions of rails 148 and 149 include insulating material. For example, insulating portions 148a and 149a of rails 148 and 149 may be positioned between electrodes and may include insulating material for electrically insulating the electrodes from other electrodes in the rail. In addition, portions 148b and 149b of rails 148 and 149 may include either insulating material or a floating metal layer (e.g., an electrically isolated metal layer that does not form electrodes).

[0040] The materials of rails 148 and 149 can be selected to provide good capillary flow of the printing material 104. For example, metal electrodes and floating metal layers are more readily wicked with molten metal printing material than if the rail material were non-metallic. In other words, during the printing operation, the printing material 104 has a contact angle with the metal parts of rails 148 and 149 that is generally smaller than the contact angle of the printing material with the non-metallic parts. Therefore, using metal electrodes and floating metal layers as the materials for rails 148 and 149 allows the printing material to be wicked along the passage 106C by capillary force and thus flow more easily through the passage 106C.

[0041] When non-metallic (e.g., insulators or semiconductors) materials are used, the non-metallic material can be optionally selected to have a desired effect on the flow of the printing material through the passage. Almost all electrical insulating materials have a molten metal contact angle greater than 100 degrees, but the value depends, among other things, on the printing material, temperature, atmosphere, and surface roughness. For example, the aluminum wetting angle on alumina varies from about 140 degrees at 750°C to about 90 degrees at 1000°C. Semiconductor materials such as silicon or germanium generally have a contact angle with the molten metal printing material that lies between the contact angles of solid metals and insulators. Lower contact angles can make the flow through passage 106C easier, while higher contact angles hinder the flow. Contact angles greater than 90° hinder the flow of the printing material through passage 106C, while contact angles less than 90° increase the flow of the printing material.

[0042] Therefore, both metallic and non-metallic materials can be selected based on their contact angle with the printing material under operating conditions to help regulate the pressure required to control the metallic flow in the passage 106C. Using metallic and other materials with relatively low contact angles (e.g., 90° or less) in the rails can reduce or eliminate the need to use external forces, such as pressure applied by a pump or hydrostatic pressure, to provide the desired flow rate of the printing material 104 through the passage 106C, compared to embodiments using materials such as insulating materials with contact angles greater than 90° to most of the rails 148, 149 (e.g., sections 148b, 149b). Insulating materials, such as those for insulating sections 148a, 149a, can be selected to obstruct the flow of the printing material 104 for any desired reason, such as to reduce or prevent undesirable or uncontrolled flow through the flow channel due to the capillary effect. Any of the optional electrode pairs used in the devices of this disclosure other than electrodes 110 and 112 (e.g., optional electrodes 144, 145 and 146, 147, and the second, third, fourth and fifth electrodes described with respect to Figure 12) may be replaced as necessary with a floating metal layer or a nonmetallic material (e.g., an insulating material or semiconductor material, such as any of the semiconductor or insulating materials described herein).

[0043] In one embodiment, as shown in Figure 3, the printing material 104 is contained substantially between or only between rails 148 and 149. Due to the printing material 104's ability to wet the sidewalls of rails 148 and 149, the printing material 104 may be optionally suspended between rails 148 and 149 and above the bottom of passage 106C, as indicated by a gap 612, the gap 612 may be filled with a gas, such as a reducing gas including air, hydrogen and nitrogen, or an inert gas such as nitrogen or argon. In such embodiments, the bottom of passage 106C may include a non-metallic material (e.g., a semiconductor material or an insulating material), such as a material that is not wettable or a material with low wettability with molten metal printing material, in order to reduce contact of the printing material with the bottom of the passage and thereby improve the suspension of the printing material between rails 148 and 149. For example, the material between rails 148 and 149 can be selected to be a nonmetal (e.g., an insulating or semiconductor material) having a contact angle with the printing material greater than 90°, such as 100° to 180°. The specific contact angle achieved depends, among other things, on the type of printing material being printed, as described herein. The embodiment shown in Figure 3 can enable a more defined printing material volume, or a more controlled volume between electrodes, and / or smaller droplet volumes, than when the printing material flow is not limited to the space between electrodes. Furthermore, since the contact of the printing material 104 is mostly with or only with rails 148 and 149, and rails 148 and 149 can, in embodiments, mostly include metal surfaces that can be wetted by molten metal printing material, this design can bring less drag on the printing material 104 as the printing material flows through the passage 106C than when the printing material flow is not limited to the space between electrodes.

[0044] Figure 9 shows an embodiment in which the sidewall layer 143 includes an insulating material positioned adjacent to the first rail 148 and the second rail 149. The insulating material may include any electrical insulating material described herein. The sidewall layer 143 is patterned to form a first sidewall 143a and a second sidewall 143b. The distance between the first sidewall 143a and the second sidewall 143b defines the width of the passage 106C through which the printing material flows. In one embodiment, the sidewall layer 143 is used to form a boundary and thereby retain the printing material 104 (e.g., molten metal) in the passage 106C. The material of the sidewall layer 143 (Figure 9), which can provide a good boundary-forming function for the molten metal printing material, is selected to be fire-resistant and electrically insulating.

[0045] Any suitable insulating material can be used for the sidewall layer 143. Examples of insulating materials include metal oxides such as aluminum oxide, magnesium oxide, and silicon oxide (e.g., silicon dioxide), metal oxynitrides such as silicon oxynitride or aluminum oxynitride, metal nitrides such as aluminum nitride, silicon nitride, or boron nitride, metal carbides such as silicon carbide, and polymers such as epoxy or polyimide, as well as any combination of these materials. It should be noted that the terms “metal oxide,” “metal nitride,” “metal oxynitride,” and “metal carbide” may include silicon and other semiconductor materials such as germanium as the metallic portion of the compound. However, semiconductors such as silicon and germanium are generally considered nonmetals for the purposes of this disclosure, as described herein, unless otherwise explicitly stated.

[0046] The insulating sidewall material can be optionally selected to provide capillary effect, a confinement effect for the printing material flow, or a balance between the two. An insulating material with improved capillary effect allows for a reduction in impedance to the flow of the printing material in the passage 106C at relatively low contact angles (e.g., approximately 145° to approximately 80°, closer to or smaller than 90°). On the other hand, an insulating material with improved confinement allows for improved confinement for boundary formation of the printing material between insulating sidewalls, which can be beneficial in reducing or preventing overflow of the printing material from the sidewall boundary in open channel configurations. The improved confinement effect is due to relatively larger contact angles (e.g., approximately 145° to approximately 180°, closer to 180°), although some degree of confinement is provided at contact angles greater than 90°. The contact angle of the insulating material depends, among other things, on the specific printing material.

[0047] For any insulating material, the contact angle of the molten metal printing material on the insulating material can also be reduced by electrowetting. The concept of electrowetting is generally well known. Electrowetting occurs when a voltage is applied to an electrode beneath the insulating layer, inducing charge accumulation in the molten metal printing material adjacent to the insulating material. For example, referring to Figures 4A and 4B, in an embodiment where electrode pairs 146, 147 are replaced by insulating material as rail portions (e.g., portions 148b, 149b in Figure 1), an optional electrode 190 (indicated by dashed lines) connected to a voltage source (not shown) can come into contact with the insulating material which is portions 148b, 149b. It is desirable for the charge to diffuse, and this diffuses by increasing the wettable area, thereby lowering the contact angle between the insulating layer (e.g., portions 148b, 149b) and the molten metal printing material. The lower contact angle between the molten metal and the insulating layer aids in the capillary filling of the passage. As described herein, controlled pressure heads can also be optionally used to induce filling of passages with molten metal, either in combination with low-contact-angle materials (e.g., metal electrodes, floating metal layers, and / or insulating materials used with electrowetting as described herein) or to allow the use of higher-contact-angle materials in the passages.

[0048] In one embodiment, as shown in Figure 9, rails 148, 149 include electrodes 110, 112 and optional electrodes 144-147 (Figure 2), and have a width greater than their thickness. Relatively wide and thin electrodes allow for an increased surface area for wicking the printing material with a wettable electrode material, while still maintaining relatively low series resistance. The sidewall layer 143 is formed to have sidewalls positioned so that the upper surfaces of rails 148, 149 are exposed, for example, as shown in Figures 9 and 10. This allows the printing material 104 to flow over the portion of rails 148, 149 positioned between sidewalls 143a and 143b, as well as between rails 148, 149.

[0049] The shapes of the electrodes, other parts of the rails and / or sidewalls in the various embodiments described herein can be used to control whether the flow of the printing material is maintained within the desired boundaries of the passage. For example, sharp edges can potentially prevent overflow of the printing material onto the upper surface of any electrode or sidewall in any of the passages described herein, while rounded edges allow the printing material to flow more easily over the edge. As an example, the sharp edges of the sidewalls 143a, 143b of the device shown in Figures 9 and 10, and the sharp edges of the electrodes and other parts of the rails 148, 149 in the device in Figures 2 and 3, can help prevent undesirable overflow. Referring to the cross-sectional view in Figure 26, preferably sharp edges have a mean radius of curvature R that is small enough to provide the desired impedance of the flow over the edge. E It can have at each point along the edge. The mean radius of curvature takes into account the curve of the edge in any given cross section that is not perfectly circular. A person skilled in the art will be able to determine the mean radius of curvature. R E The desired value of R depends, among other things, on the type of printing material and the type of material used for the sidewalls. E Suitable values ​​include those smaller than approximately 50 micrometers, such as approximately 1 micrometer to approximately 50 micrometers, or approximately 5 micrometers to approximately 50 micrometers. If overflow is desired, a rounded edge with a large radius of curvature can be preferably used.

[0050] In other embodiments, the entire upper surface of the electrode may be coated with a non-wetting or less wettable material compared to the wettability of the electrode in order to prevent the flow of printing material out of the passage. For example, a sidewall layer 143 comprising any or a combination of insulating materials described herein may cover all or part of the upper surface of either of the electrode pairs, as shown in Figures 9 and 25E. Alternatively, the entire upper surface of the electrode pair may be left as an exposed metal surface, as shown, for example, in Figures 3 and 10.

[0051] Figure 10 shows an embodiment in which the sidewall layer 143 is positioned in close proximity to the first electrode 110 and the second electrode 112. The sidewall layer 143 is patterned to form the first sidewall 143a and the second sidewall 143b. The distance between the first sidewall 143a and the second sidewall 143b defines the width of the passage 106C. The electrodes 110 and 112 are embedded in trenches within the substrate 102 such that the printing material flows over the electrodes but substantially not between them. The sidewall layer 143 may include any suitable insulating material, including any or a combination of insulating materials described herein. The insulating material can be optionally selected to have a desired contact angle with the printing material to provide a confinement effect and / or capillary effect, as discussed herein.

[0052] In one embodiment, electrodes 110, 112 and optional electrodes 144-147 have a width less than or equal to their thickness, as shown in Figure 10. Optional electrodes 144-147 may have a similar configuration as shown in the top view of Figure 2, but can be embedded in trenches within the substrate, as shown for electrodes 110 and 112 in Figure 10. The increased thickness allows for narrower electrodes that conserve material resources in the substrate while still providing the desired low resistance, thereby reducing series resistance while enabling a higher linear density of the ejector conduit. Alternatively, electrodes 110, 112 and optional electrodes 144-147 have a width greater than their thickness.

[0053] In the embodiment of Figure 10, electrodes 110, 112 and electrodes 144-147 can optionally form embedded rails 148 and 149. Rails 148 and 149 in Figure 10 do not provide sidewalls for the passage 106C, but can guide molten printing material through the ejector conduit 106 by wicking the printing material by providing a surface that can be wetted along the length of the passage. The rails extend along the entire length of the passage, or substantially the entire length, and may include electrodes 110, 112, and either i) one or more pairs of the optionally selected electrodes 144-147, or ii) a floating metal layer or other non-metallic material in place of the optionally selected electrodes. Any of the metals described herein for use as electrodes or floating metal layers may be used as described herein. Any of the non-metallic materials described herein (e.g., semiconductor materials or insulating materials), including any of the insulating materials described herein for use as a sidewall layer 143, may also be used in portions of the rails.

[0054] Electrodes 110, 112, and 144-147 are shown as being formed on the same substrate layer. However, those skilled in the art will readily understand that some or all of electrodes 110, 112, and 144-147 may be formed on different non-conductive layers (e.g., semiconductor or insulating) sublayers of the multilayer stack and routed to the surface of the passage 106C via vias formed in the insulating layer to provide electrical contact with the printing material 104 during printing.

[0055] The electrically isolated metals used in electrodes 110, 112, 144, 145, 146, 147, and in rail portions (e.g., floating metal layers in rail portions 148b, 149b) may include any conductive material suitable for providing electrical contact to the printing material 104 while withstanding the ejector nozzle temperature during printing. Examples of suitable conductive materials include metals with a higher melting temperature than the printing material 104, including refractory metals, aluminum, aluminum alloys (e.g., 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series such as 6061 and 6063, and 7000 series aluminum alloys), magnesium, magnesium alloys, iron, iron alloys (e.g., steel), copper, copper alloys (e.g., zinc), nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Suitable alloys of the above metals may include mixtures of any desired metals, such as mixtures of two or more of the above elemental metals, including elemental refractory metals, for example, mixtures of two or more of aluminum, magnesium, iron, copper, nickel, titanium, tungsten, or other elemental refractory metals such as palladium and silver. As used herein, the terms “refractory metal” or “refractory metals” are defined to include both elemental refractory metals and their alloys, such as alloys of two or more of the refractory metals listed herein, or alloys of one or more refractory metals with other metals such as iron, nickel, copper, and silver, including niobium, molybdenum, tantalum, tungsten, rhenium, titanium, vanadium, chromium, zirconium, hafnium, ruthenium, rhodium, osmium, iridium, and alloys of any of these metals. Suitable refractory metal alloys are known in the art.

[0056] The electrodes and any electrically isolated conductive rail portions 148b, 149b may be corrosion-resistant. For example, the electrodes and / or portions 148b, 149b may be optionally coated with a passivation layer containing a noble metal such as palladium to resist corrosion by the molten printing material. In one example, any of the electrodes and / or other portions 148b, 149b taught herein may contain tungsten (e.g., elemental tungsten or tungsten alloy), other refractory metals, copper, or other metals taught herein as suitable for electrodes, and may be coated with a passivation layer containing a noble metal such as palladium. An example of a passivation layer 405 is shown in Figure 23A. The use of noble metals as corrosion-resistant coatings on electrodes is generally well known.

[0057] In one embodiment, an ejector device is envisioned for mixing two or more different printing materials during 3D printing. Figure 12 shows an example of an ejector device 300 configured to mix and eject printing material 104. Multiple ejector devices 300 can be arranged in an array on a substrate 102, as described herein for other ejector devices. The ejector device 300 includes a substrate 102 comprising a semiconductor or electrically insulating surface 102a and an ejector conduit 306 comprising a plurality of passages 306C, 306E, and 306F. The first passage 306C fluidly connects the first end 306A of the ejector conduit to a conduit junction 306D. The first end 306A is configured to receive the first printing material 104A (e.g., Figure 14). The second passage 306E fluidly connects the second end 306B of the ejector conduit 306D to the conduit junction 306D. The second end 306B is configured to receive the second printing material 104B. The third passage 306F fluidly connects the conduit junction 306D to the third end 306g, which includes an ejector nozzle 108. The ejector nozzle 108 includes a first electrode 110 and a second electrode 112. At least one surface of the first electrode 110 and at least one surface of the second electrode 112 are exposed within the third passage 306F.

[0058] Referring to Figure 12, the ejector conduit 306 includes a third electrode 308 and a fourth electrode 310. At least one surface of the third electrode 308 and at least one surface of the fourth electrode 310 are exposed within the first passage 306C. Together, the third electrode 308 and the fourth electrode 310 form a second electrode pair configured to control the flow of the first printing material 104A from the first passage 306C to the third passage 306F. The ejector conduit 306 further includes a fifth electrode 312 and a sixth electrode 314. At least one surface of the fifth electrode 312 and at least one surface of the sixth electrode 314 are exposed within the second passage 306E. Together, the fifth electrode 312 and the sixth electrode 314 form a third electrode pair configured to control the flow of the second printing material 104B from the second passage 306E to the third passage 306F. The magnetic flux region extends to a first reloading region 170A between the exposed third electrode 308 and the exposed fourth electrode 310 in the first passage 306C, and to a second reloading region 170B between the exposed fifth electrode 312 and the exposed sixth electrode 314 in the second passage 306E. In this configuration, electromagnetic forces such as the Lorentz force can be generated by passing current pulses through the printed material between the electrode pairs, as described herein.

[0059] In one embodiment, the ejector conduit 306 may include a fourth electrode pair, including electrodes 316, 310 positioned between the second electrode pair 308, 310 and the first end 306A of the first passage 306C. The fourth electrode pair is configured to control the flow of a portion of the first printing material 104A upstream of the second electrode pair 308, 310. The ejector conduit 306 may also include a fifth electrode pair, including electrodes 320, 314 positioned between the third electrode pair 312, 314 and the second end 306B of the second passage 306E. The fifth electrode pair is configured to control the flow of a portion of the second printing material 104B upstream of the third electrode pair 312, 314. The magnetic flux region extends to the region between the fourth electrode pair and the region between the fifth electrode pair, thereby enabling the generation of a Lorentz force to control the printing material flow.

[0060] In one embodiment, the second and fourth electrode pairs share a common electrode 310, and the third and fifth electrode pairs share a common electrode 314. In one embodiment, the shared electrodes are held to ground using embedded electrodes (not shown). Alternatively, those skilled in the art can easily determine an electrode configuration in which the fourth electrode pair does not use a common electrode with the second electrode pair, and the fifth electrode pair does not use a common electrode with the third electrode pair.

[0061] The electrode pair may be configured to form a rail, which can be used to guide molten printing material through the ejector conduit 106 by wicking the printing material, for example, by forming the sidewall of the passage 106C and / or by providing a surface that can be wetted along the length of the passage. The rail extends along the entire length of the passage, or substantially the entire length. In one embodiment, the first rail 148A and the second rail 149A for the first and third passages 306C, 306F include a first electrode pair (110, 112) and optionally one or both of a second electrode pair (308, 310) and a fourth electrode pair (316, 310), and the first rail 148B and the second rail 149B for the second and third passages 306E, 306F include a first electrode pair (110, 112) and optionally one or both of a third electrode pair (312, 314) and a fifth electrode pair (320, 314). The portions of rails 148 and 149 may include insulating material. For example, insulating rail portions 148A-a and 148B-a may be positioned between electrodes as shown in Figure 12 and may include insulating material to electrically insulate the electrodes from other electrodes in the rail. In addition, any or all of the electrodes 308, 310, 312, 314, 316, and 360 constituting rails 148A, 149A, 148B, and 149B may include insulating material or floating metal layers (e.g., electrically isolated metal layers that do not form electrodes), as discussed herein with respect to the rails of Figures 1 and 2. Any insulating and conductive material discussed herein for use as a part of a rail, including any metallic and non-metallic material for the floating metal layers, electrodes, and insulating portions of the rail, can also be used for the rails of the device in Figure 12.

[0062] Figures 13A and 13B show top views of another ejector device 300 for mixing different printing materials according to one embodiment of the present disclosure. The ejector device 300 includes a substrate 102, such as one of the substrates 102 described herein. As shown in Figure 13A, the electrode configuration includes a first electrode pair 110, 112 and optionally second, third, fourth, and fifth electrode pairs, as described above for Figure 12. As shown in the end view of Figure 13C, the electrodes can be formed to have a width greater than their height, but any desired width-to-height ratio can be used. As shown in Figures 13B and 13C, a sidewall layer 143 containing an insulating material, such as one of the insulating materials described herein, is positioned on the electrodes to form the boundaries of passages 306C, 306E, and 306F, similar to the electrode and sidewall configuration of the device in Figure 9. The ejector device 300, which includes multiple passages for mixing the printing material, as in Figures 12 and 13, can also be fabricated using any of the other electrode and sidewall configurations discussed herein, such as the configurations generally shown in Figures 3 and 10.

[0063] The ejector devices in Figures 12 and 13 illustrate means for controlling alloy composition. Referring to Figure 14, two or more sources of different printing materials (e.g., printing materials 104A, 104B) are aligned with a confluence channel (e.g., a first passage 306C and a second passage 306E) and supplied to the confluence channel. During operation, the ejector device 300 is maintained at a temperature at which all printing material components melt. For example, Al and Mg are both liquid above approximately 670°C, as are various alloys of Al. Any other combination of printing materials that melt at a suitable operating temperature can be used. Although only two passages 306C, 306E are illustrated, the ejector conduit can include three, four, or more passages. The printing materials from each of the two or more passages merge into a third passage 306F, where they mix with each other to form the mixed printing material 104C.

[0064] The third passage 306F may include a linear mixing region 330, as shown in Figures 13B and 14, which show that the adjacent surfaces of electrodes 110, 112 (e.g., opposing adjacent sidewalls) and / or the sidewalls 143a and 143b of the sidewall layer 143 in the ejector nozzle 108 provide a generally linear passage 306F. Alternatively, the third passage 306F may include a non-linear mixing region 330, where the adjacent surfaces of electrodes 110, 112 (e.g., opposing adjacent sidewalls) and / or the sidewalls 143a and 143b of the sidewall layer 143 in the ejector nozzle 108 provide a generally non-linear, i.e., curved, passage 306F. For example, the mixing region 330 of passage 306F may include a meandering configuration, as shown in Figure 15. The mixing region 330 is located upstream of, or as part of, the ejector nozzle 108. By controlling the flow of printing materials 104A and 104B into the mixing region 330 (for example, by using pulse length and / or amplitude control of current pulses to an optional second and third electrode pair and / or an optional fourth and fifth electrode pair), the ratio of printing materials 104A and 104B in the resulting mixed printing material 104C can be modified as needed for each ejected droplet, as will be discussed in more detail below.

[0065] The ejector conduits 106, 306 as described herein can function as open channels having at least one side open to the atmosphere along the length of the passage. In alternative embodiments, any of the ejector conduits described herein may include closed channels that are enclosed on all sides along the length of the passage (e.g., passage 106C in Figure 2 or passages 306C, 306E, and 306F in Figure 12) but remain open at a first end 106A and a second end 106B to allow receiving and ejecting the printing material 104. One such closed channel array is shown in Figure 11, which shows two open channel arrays as shown in Figure 3, where the passage 106C of each array 107 faces the other array 107 and is mounted to form a closed channel. An optional interposer layer 250 is sandwiched between the two arrays 107. The interposer layer 250 may include any suitable insulating material that can withstand the operating temperature of the device, such as silicon oxide (e.g., silicon dioxide) or ceramic. An ejector device including a closed channel can be formed using any of the open-channel ejector devices described herein in a manner similar to that described for the device in Figure 11.

[0066] In yet another embodiment, a closed channel device can be formed by covering one of the open channel array structures herein with a plate comprising, for example, ceramic, glass, or other insulating material. For example, a single array 107 can be covered with an interposer layer 250 as shown in Figure 11 without mounting a second array 107.

[0067] Furthermore, although closed-channel devices are described as arrays, closed-channel devices containing a single ejector conduit can also be fabricated by forming a single open-channel ejector conduit on a substrate and then covering it with a plate, as described above. Similarly, two separate ejector devices, each containing a single open-channel ejector conduit on a substrate, can be mounted such that the passages 106C of each ejector conduit face each other, thereby forming two closed channels. As described above for the device in Figure 11, an optional interposer layer 250 can be sandwiched between the two ejector channels.

[0068] The current pulse generation system 114, also referred to herein as a current pulse generation circuit, has the ability to generate current pulses of sufficient amplitude to provide a desired electromagnetic force (e.g., Lorentz force) induced momentum of the printing material 104 in a relatively short period of time (e.g., a single current pulse). The current pulse generates sufficient momentum of the printing material resulting from the generated electromagnetic force, causing, for example, the separation and ejection of the printing material 104 from the ejector nozzle 108 during the operation of the 3D printer. Any type of current pulse generation circuit can be used that can provide a desired pulse with sufficient amperage to eject the printing material. Suitable current pulse generation circuits are well known in the art, and any desired current pulse generation system can be used. The current pulse generation system is electrically connected to one or more of the electrode pairs in the ejector device described herein (e.g., all electrode pairs), such as the first electrode 110 and the second electrode 112 of the ejector nozzle, as shown in Figures 4A, 16A, and 16B. In one embodiment, the current pulse generation system 114 includes a current source electrically connected to the ejector nozzle 108 (e.g., a current source connected to the first electrode 110 and a current sink electrically connected to the second electrode 112 of the ejector nozzle). In another embodiment, the current pulse generation system 114 includes a voltage source electrically connected to the ejector nozzle 108 (e.g., to apply a desired voltage between the first electrode 110 and the second electrode 112 of the nozzle). Examples of suitable current and voltage sources are well known in the art.

[0069] Referring to Figure 4A, the circuit of the current pulse generation system 114 may include a power supply 114a and a switch 114b, which are operated by a pulse control device 114c, such as a pulse generator, waveform generator, or other device capable of generating a desired current pulse. Although shown separately, the switch 114b may optionally be part of the pulse control device 114c. The pulse control device 114c may be programmable to provide computer control of the current pulse generation system. The power supply 114a may be any power supply, such as a DC power supply or a switching power supply, capable of supplying a desired current. The switch 114b may be any switch that can provide a desired current pulse in combination with the pulse control device 114c. Examples include high-current switches, including FET or MEMS switches. As will be understood by those skilled in the art, other circuit components such as amplifiers and resistors may optionally be included. As described herein, the current pulse generation system 114 may be electrically connected to the printing material in the ejector nozzle 108 using electrodes 110 and 112.

[0070] Figure 16A shows an example of a current pulse generation circuit that can potentially be used to provide relatively high current pulses over a short period of time with a low duty cycle. The current pulse generation system 114 in Figure 16A charges one or more capacitors using a power supply 114a, which is a DC power supply such as a switching power supply, and multiple FETs (e.g., GaAs FETs or other FETs) 114b that act as switches. As described herein, the current pulse generation system 114 in Figure 16A is electrically connected to the printing material in the ejector nozzle 108 using electrodes 110 and 112. The charged capacitors can be discharged to provide a desired current pulse 118 across the printing material. A typical circuit design can use a DC voltage source, a high-power operational amplifier with a current feedback resistor, and / or a high-speed, low-series impedance switch such as a GaAs nMOS transistor. Such circuits are generally well known. High-speed bipolar switching can similarly be applied using, for example, a high-current H-bridge. Any other suitable current pulse generation circuit that can provide a suitable current pulse can be used.

[0071] In one embodiment, the current pulse generation system 114 includes a programmable pulse control device. Pulse control system 160 (Figure 16A) is an example of a programmable pulse control device including a pulse controller 162 and a computing system 164. The pulse controller 162 may be a microcontroller including a CPU 167 and memory 172 that interfaces with circuit components of the current pulse generation system 114 (e.g., current switches, power supplies and / or other components) to generate current pulses having desired pulse characteristics when current pulses flow between a first electrode 110 and a second electrode 112. The pulse controller 162 can be driven by the computing system 164, which can execute computer executable instructions embedded in a non-temporary computer-readable medium (e.g., memory 166 of the computing system 164). The computing system 164 may be integrated as part of the pulse controller 162 itself (for example, a CPU and memory integrated with the pulse controller 162 can be used, such as a CPU 167 and memory 172), or it may be a separate computer system interfaced with the pulse controller 162, for example, including memory 166 and CPU 168 (as shown in Figure 16A). Computer executable instructions embedded in the non-temporary computer-readable medium of the computing system 164 can, among other things, instruct the CPU 168 of the computing system 164 to determine at least one desired pulse characteristic, such as pulse length, amplitude, and / or pulse shape, for ejecting the printing material 104 as described herein. The computing system 164 can determine at least one desired pulse characteristic in any preferred way, such as by using a mathematical algorithm to calculate the pulse characteristics that provide the desired ejection characteristics of the printing material 104, for example, taking into account the type of printing material, the pulse history of the ejector, and / or feedback from the printer ejection mechanism. Such feedback may include, for example, real-time magnetic flux fluctuations, nozzle temperature, print material temperature, and / or other data.Additional computer-executable instructions embedded in non-temporary computer-readable media (e.g., memory 166 or 172) of either or both of the computing system 164 and the pulse controller 162 are executed by the CPU of the pulse control system 160 (e.g., CPU 168 and / or CPU 167) to send instructions or electrical signals to the voltage or current source of the current pulse generation system to cause a current to flow between the first electrode 110 and the second electrode 112. The resulting current includes a current pulse 118 having at least one pulse characteristic. By controlling the current pulses crossing the first electrode 110 and the second electrode 112, the ejection of the printing material 104 can be controlled, including droplet volume, the rate of ejected printing material, and the ejection rate (e.g., number of ejections per second). Optionally, controlling the current pulses crossing one or more of the second, third, fourth, and fifth electrode pairs in the ejector device of this disclosure can be used to control the flow of printing material in the ejector conduit, as will be described in more detail herein.

[0072] As described above, when determining the desired pulse characteristics, the calculation system 164 can optionally compensate for, for example, the effects of temperature changes at the nozzle 108 caused by changes in the duty cycle on the conductivity, thermal expansion, magnetic flux, or other temperature-dependent properties of the printing material 104 or the system (e.g., the effect of temperature on the magnet or flux guide). For example, in some cases the duty cycle may be high, and pulses may follow one after the other immediately. This can potentially cause a localized increase in temperature of the ejector nozzle 108, the ejector conduit 106 adjacent to the ejector nozzle, and / or the printing material 104 contained therein, compared to conditions with lower duty cycles. Such temperature changes can affect the ejection of the printing material. By considering these effects when determining the pulse characteristics, the calculation system 164 of the current pulse generation system can control and / or improve the ejection characteristics of the printer ejection mechanism 100.

[0073] Figure 16B shows a current pulse generation circuit similar to the current pulse generation circuit in Figure 16A, except that the current pulse generation circuit in Figure 16B can be used with an ejector nozzle 108 that includes two or more electrode pairs 110a and 112a, 110b and 112b, and 110c and 112c. Although three pairs of electrodes are shown, any number of electrode pairs can be used, such as 1 to 10 electrode pairs or 2 to 5 electrode pairs. Such a design may potentially allow for improved control and / or higher current density across the printing material compared to the single electrode pair design in Figure 16A. For example, multiple electrodes per nozzle can enable variable volume droplet ejection, and the droplet volume of each ejection can be varied by sending current pulses to a desired number of electrode pairs. Therefore, smaller droplets can be ejected by pulsing a current through a single electrode pair 110a, 112a, while larger droplets can be ejected by pulsing a current through two electrode pairs 110a, 112a and 110b, 112b, or three or more electrode pairs. A pulse control system 160, such as the one shown in Figure 16A, can also be used to control the current pulse generation circuit in Figure 16B. Any of the devices of this disclosure may use multiple electrode pairs within the ejector nozzle 108 as described herein.

[0074] The feeder mechanism 113 may be any suitable mechanical system, pressure-driven system, or other system capable of supplying the printing material 104 to the ejector conduit 106. The feeder mechanism may include one or more pumps, actuators, or combinations thereof that can function as movers 113a (Figure 22) for moving the printing material 104. Examples of suitable actuators include electric motors, piezoelectric motors, inchworm actuators, hydraulic actuators, and pneumatic actuators, which are generally well known.

[0075] Electromagnetic force drives (e.g., Lorentz force drives) can also be used as suitable actuators for controlling the flow of printing material 104 upstream of a plurality of ejector conduits 106 and / or for controlling the flow of printing material 104 from the reservoir 140 into the ejector conduits 106. Such electromagnetic force drives can apply an electromagnetic force to the printing material by using a magnetic field across one or more electrode pairs used to control a current through a liquid metal, similar to how electromagnetic force is used to control the flow of printing material 104 in the passage 106c using electrode pairs (e.g., 144 and 145, 146 and 147 in Figure 2). For example, portions 148b and 149b of rails 148 and 149 in Figure 1 can optionally be configured to function as such electrode pairs for controlling the flow of printing material 104 from the reservoir 140.

[0076] The type of feeder mechanism 113 used depends on the type of printing material 104 used. For example, the printing material 104 comprises multiple filaments, and the feeder mechanism 113 is a mechanism for advancing the multiple filaments. For the purposes of this disclosure, the terms “filament” or “filaments” are defined to include both solid filaments (e.g., wires such as 104 in Figure 22) and liquid filaments such as liquid-filled capillaries or other liquid-filled conduits. Examples of feeder mechanisms for solid filaments include spool feeders and inchworm actuators, which are well known in the art. As will be understood by those skilled in the art, other feeder devices for moving solid printing material 104 in the form of solid filaments, dry powder, or other solid forms into an ejector conduit 106 by a wheel or in other ways may also be used as part of the feeder mechanism 113 or a feeder mechanism.

[0077] In the embodiment, the feeder mechanism 113 may be any suitable mechanism for supplying liquid printing material into the ejector conduit 106 and optionally advancing the liquid printing material to the ejector nozzle 108. Examples of suitable feeder mechanisms for liquid printing material include mechanisms that advance the liquid from a reservoir or other source of printing material (e.g., molten metal) and thereby use sufficient capillary force and / or overpressure to stably refill the ejector nozzle 108 after discharge (for example, the feeder mechanism may be designed to automatically refill the ejector nozzle after discharge). The feeder mechanism may include, for example, a pump that can be filled with printing material to provide a hydrostatic head (e.g., by maintaining a specific level of filling of printing material in the reservoir), or a feeder conduit and / or reservoir configuration, or other devices or combinations of such devices for applying overpressure. Such feeder mechanisms are well known in the art. Those skilled in the art will be able to easily determine a suitable feeder mechanism.

[0078] When the metal-coated rails 148, 149 are used as described herein, the capillary force provided thereby can potentially deliver a desired flow of printing material through the passage to the ejector nozzle without the assistance of excess pressure from an additional feeder mechanism. Furthermore, to drive or obstruct the flow of printing material in the passage of the ejector conduit, an electromagnetic force provided by an additional electrode pair, as described herein, can be used instead of hydrostatic pressure or capillary force.

[0079] In one embodiment, the feeder mechanism 113 can supply printing material to each ejector conduit 106 at different supply rates. For example, the feeder mechanism 113 for advancing multiple filaments includes a separate mechanism for progressively advancing each of the multiple filaments at a separately controllable supply rate. Thus, in one embodiment, the supply rate can satisfy the replenishment of printing material 104 to the ejector nozzles before the next ejection, as the ejection rate at each ejector is increased or decreased as needed for printing.

[0080] Referring to Figures 7 and 8, any array 107 of the ejector devices described herein may be supported within the ejector housing 120. In one embodiment, the ejector devices may be a separate structure from the housing material and may be mounted in the ejector housing 120 in any preferred manner. The ejector housing 120 includes any preferred material that can withstand the injection process temperature and provide the desired support for the ejector conduit 106. Examples of preferred housing materials include metals such as aluminum, copper, brass, and steel, refractory metals, ceramics, other refractory materials, polymers that can withstand the process temperature (e.g., polymers with melting points of 150°C to 650°C or higher, such as 200°C to 300°C), and combinations thereof such as metal-coated ceramics and ceramic-coated metals. An example of a composite housing material is copper clad with a ceramic such as mullite, where copper and mullite have similar coefficients of thermal expansion. The specific material used may depend on the printing material to be ejected. For the purposes of this disclosure, the terms “refractory material” and “refractory materials” are broadly defined as any material having a melting point of 1000°C or higher at 1 atmosphere. For example, refractory materials may have melting points in the range of 1000°C to 4000°C, such as about 1200°C to 4000°C, or about 1400°C to 3500°C, or about 1700°C to 3500°C, or about 2000°C to 3500°C.

[0081] In one embodiment, the printer ejection mechanism 100 includes a heater mechanism 126 for heating at least a portion of the ejector conduits 106 and optionally an ejector housing 120 surrounding the ejector conduits 106 during the operation of the three-dimensional printer, as shown, for example, in Figures 1, 5, 8, 10, and 11. In this embodiment, the heater mechanism 126 can maintain the temperature of the reservoir 140 and the passage 106C of the ejector conduits 106 above the melting temperature of the printing material 104. The reservoir 140 is fluidly connected to a plurality of ejector conduits 106. In one example, the heater mechanism 126 can provide sufficient thermal energy to bring the printing material 104 to a temperature above its melting temperature and to maintain the printing material 104 above its melting temperature while the printing material 104 is held in the reservoir 140 and flowed from the reservoir 140 through the ejector conduits 106 to the nozzle 108.

[0082] The heater mechanism 126 may include, for example, any preferred type of resistance heater, induction heater, radiant heater, or any combination thereof. For example, the heater mechanism 126 includes a heating element positioned in close proximity to the reservoir 140 or conduit 106. The heating element may, for example, be in the form of a resistance heating coil or an induction coil. As an example, a preferred resistance heater mechanism includes an ohmic meandering trace embedded in the substrate, housing, or a layer surrounding the passage 106C and / or the printing material reservoir 140 (e.g., a sidewall layer 143 or any other insulating layer). As used herein, the term “ohmic meandering trace” refers to a resistance heating element having a non-linear path along the longitudinal axis (e.g., a zigzag path, a wound path, or a wire suitable for resistance heating having a differently curved path). The heater mechanism 126 is separate from the current pulse generation system 114 and / or electrodes 110, 112 and electrodes 144-147.

[0083] In one embodiment, the array of ejector conduits 106 includes M columns of ejector conduits arranged on the X-axis and N rows of ejector conduits arranged on the Y-axis, where M is an integer in the range of, for example, about 2 to about 1000, and N is an integer in the range of 1 to 2. For example, in the array of Figure 2, M is 3 and N is 1, but in the array of Figure 11, M is 8 and N is 2. In other examples, M is an integer in the range of about 5 to 1000, 50 to 1000, 100 to 900, 250 to 750, or 500 to 1000.

[0084] In one embodiment, the rows of ejector conduits 106 are arranged linearly, and the ejector conduits 106 in each row are staggered relative to the ejector conduits of adjacent rows to facilitate closer mounting, as shown, for example, in Figure 11. Multiple arrays may be stacked or otherwise combined to expand the number of rows or columns in the system as needed.

[0085] The ejector device design and MEMS fabrication techniques that can be used to fabricate the ejector devices of this disclosure enable increased nozzle density compared to most non-MEM fabrication techniques. For example, in the case of a single-row array of ejector conduits, such as shown in Figure 2, the nozzle density can exceed approximately 5 nozzles / inch, such as approximately 10 nozzles / inch to approximately 1500 nozzles / inch, or approximately 50 nozzles / inch to approximately 1000 nozzles / inch, or approximately 100 nozzles / inch to approximately 500 nozzles / inch. The number of nozzles per inch can effectively double in a two-row array of ejector conduits, such as shown in Figure 11. The actual nozzle density depends on several factors, including, among others, the desired nozzle size and the complexity of the ejector conduits in the array. Lower nozzle densities can be used if necessary, but the relatively high nozzle densities provided by this technique can enable shorter 3D printing times and / or smaller droplet sizes than when arrays with lower nozzle densities are used.

[0086] Droplet formation during the ejection of the printing material can occur by any suitable mechanism inside or outside the ejector nozzle 108. In one embodiment, separation of the printing material for droplet formation can occur by necking off of the printing material inside the ejector conduit 106, such as inside the nozzle 108. In embodiments where a closed ejector conduit is used, such as shown in Figure 11, the ejector conduit 106 may optionally include one or more vents 135, such as shown in Figure 17. The vents 135 can be located inside or directly above the ejector nozzle 108, such as in or near the ejector nozzle 108, where necking off of the printing material 104 being ejected from the remaining printing material 104 inside the ejector conduit 106 occurs during droplet formation. The vent 135 allows air or other ambient gas to flow into the ejector conduit 106 and / or into the ejector nozzle 108 (as indicated by arrow 137) when the printing material 104 is ejected from the ejector nozzle 108. This can allow the ejected printing material 104 to be more easily separated from the remaining printing material 104 in the ejector conduit 106 and / or to be more easily ejected from the ejector nozzle 108. One or more vents 135 can be configured in any way that allows ambient gas to flow into the ejector nozzle when the printing material 104 is ejected. Figures 18A and 18B show another example in which the vent 135 takes the form of a groove on the inner surface of the ejector nozzle 108. Any other suitable vent configuration may be used. In one embodiment, such as those shown in Figures 17, 18A, and 18B, the vent 135 is small enough that the surface tension of the liquid printing material 104 prevents a considerable amount of printing material from flowing out of the ejector conduit into the vent 135, but is large enough to allow ambient gas to flow through the groove into the ejector nozzle 108. For example, the width and / or length of the vent 130 in Figure 17, or the diameter in the case of a circular vent (not shown), or the groove width in Figure 18 can be 10 times or more smaller than the inner diameter of the ejector nozzle so as to reduce or eliminate the penetration of liquid printing material.The vents can be formed by any suitable means, such as etching techniques or laser ablation, which are well known in the art.

[0087] This disclosure is not intended to be limited to any particular droplet formation and / or separation mode. For example, droplets may neck off and separate in a separation zone within the ejector conduit 106, but it is also possible for droplets to neck off and separate outside the ejector conduit 106, with the unseparated printing material 104 subsequently retracting into the ejector conduit 106. Thus, modes of droplet ejection may include electromagnetically driven "extrusion" of molten printing material 104 from the ejector nozzle 108 into free space, followed by de-acceleration / retraction of the extruded printing material 104 when the current pulse ends and the printing material 104 contracts. Other modes of droplet ejection and / or separation can also be realized.

[0088] The printer ejection mechanism 100 described herein can be used in any type of printer suitable for ejecting printing material. The printer ejection mechanism 100 may be manufactured and sold separately for use in a printer, or alternatively, it may be manufactured together as part of a printer or as part of a larger printer component. In one embodiment, the printer is a three-dimensional ("3D") printer that can be used to print 3D objects. A block diagram of an exemplary 3D printer 150 is shown in Figure 19. The 3D printer 150 may include any of the printer ejection mechanisms 100 described herein. In one embodiment, the printer ejection mechanism 100 may include an ejector device 101, which includes an array of ejector conduits or any other ejector device described herein, as well as a current pulse generation system 114 and a magnetic field source 130. In addition, the 3D printer may include a positioning system 152 for controlling the relative position of the ejector device 101 with respect to a printing substrate 154. The phrase "controlling the relative position of the ejector device with respect to the printing substrate" means that either the ejector device or the printing substrate 154, or both, can be moved to change the relative position of the ejector device with respect to the printing substrate. While the ejector device is described herein as being moved relative to the printing substrate, it should be understood that i) the current pulse generation system and ii) all or part of the magnetic field source can also be moved relative to the printing substrate using the positioning system 152. The relative position of the ejector device with respect to the printing substrate 154 is modified during printing so that the printing substrate 154 is positioned to receive printable material 104 from multiple ejector conduits, thereby forming a 3D object. The positioning system 152 may include either or both of the printing substrate handling mechanism 156 for positioning the printing substrate 154 and the array positioning mechanism 158 for positioning the ejector device and, optionally, parts of the current pulse generation system 114 or electrical connections thereto, or other parts of the printer ejection mechanism 100. The printing substrate 154 may include any substrate on which it is desirable to print three-dimensional objects.Examples of the printed substrate 154 include a build plate that is part of the 3D printer 150, or other temporary substrates from which the 3D object can be removed after printing. In another example, the printed substrate 154 may be intended to be permanently attached to the three-dimensional object after printing, for example, if the printed substrate 154 is a printed circuit board with circuit parts printed on it.

[0089] The printing substrate handling mechanism 156 may be any mechanism suitable for positioning the printing substrate 154 to receive printable material from the ejector device during the operation of the 3D printer 150. In one embodiment, the printing substrate handling mechanism 156 has the ability to position the printing substrate 154, such as a build plate or other substrate, by moving the printing substrate 154 in directions along the x, y, and / or z axes to a desired target position for the ejected printable material. The array positioning mechanism 158 may be any mechanism suitable for moving the ejector device in directions along one or more of the x, y, and / or z axes to a desired target position for the ejected printable material 104. A positioning system 152 including either or both of the printing substrate handling mechanism 156 and the array positioning mechanism 158 may include one or more actuators 180 (Figure 22) that can function as movers for positioning the printing substrate 154 and the ejector device relative to each other, for example, using a system including a track 182. Examples of suitable actuators include electric motors, piezoelectric motors, hydraulic actuators, and pneumatic actuators. Figure 22 shows an example of such a positioning system 152, which includes an actuator-equipped (e.g., motor-equipped) XY stage 184 for supporting a printing substrate 154, and a vertical track system 186 on which one or more actuators 180 can be used to move all or part 100a of the printer ejection mechanism 100 to enable vertical positioning. Part 100a of the printer ejection mechanism 100 may include any of the components of the printer ejection mechanism 100 described herein, mounted on the vertical track system 186 for vertical positioning, including an ejector device, all or part of a current pulse generation system, and all or part of a magnetic field source. The feeder mechanism 113 can be positioned so as not to be directly mounted on the vertical track system 186 (as shown in Figure 22), or in other embodiments, it can be directly mounted on the vertical track system 186.In another embodiment, the positioning system 152 includes an actuator-equipped (e.g., motor-equipped) XYZ stage for supporting and positioning the printing substrate 154 in three dimensions, and the position of part 100a of the printer ejection mechanism 100 (e.g., the print head) is fixed. Generally, it is easier to fix the print head together with the feeder and support elements attached to it and move only the printing substrate 154 in 3D. However, any means for relative motion can be used.

[0090] As described above, the positioning system 152 may include one or both of the print substrate handling mechanism 156 and the array positioning mechanism 158. For example, the print substrate handling mechanism 156 can be used to move the print substrate 154 along both the x and y axes, and the array positioning mechanism 158 can be used to move the ejector device and optionally the entire printer ejection mechanism 100 or any part thereof along the z axis, thereby enabling the print substrate 154 and the ejector device to be positioned three-dimensionally relative to each other during 3D printer operation. For example, for the purposes of this consideration, the x and z axes are as shown for the printing operation in Figure 20, the y axis (not shown) is in the direction toward the back of the paper, the x and y axes are parallel to the top surface of the print substrate 154, and the z axis is perpendicular to the top surface of the print substrate 154.

[0091] In one embodiment, the printing substrate 154 is a build plate, and optionally, a heater mechanism 155 is used, which is positioned within or near the build plate, or, in the case of a radiant heating lamp or laser, is positioned to allow the build plate to collide with radiant energy, such as a resistance heating element, an induction heating coil, a radiant heating lamp or laser, or a combination of two or more thereof. The heater mechanism 155 can provide sufficient thermal energy to heat the build plate and / or the 3D object printed thereon to a desired deposition temperature. Suitable build plates, including build plates having a heater mechanism, are well known in the art.

[0092] One embodiment of the present disclosure relates to a method for ejecting printing material from a printer ejection mechanism. As shown in Figure 21-220, the method includes supplying conductive printing material 104 to an ejector device which includes a plurality of ejector conduits 106 on a substrate 102 (Figures 1 and 2). The ejector conduits 106 include a first end 106A configured to receive the printing material and a second end 106B which includes an ejector nozzle 108. In one embodiment, the ejector nozzle 108 may have an inner width (e.g., diameter) in the range of, for example, about 10 micrometers to about 1000 micrometers, or any other ejector nozzle width disclosed herein. In the method described herein, the ejector nozzle 108 includes electrodes 110, 112 for supplying current in the form of electrical pulses through the printing material, as will be discussed in more detail herein.

[0093] As shown in Figure 21, 222, the printing material 104 is advanced in one or more (e.g., all) of the ejector conduits 106 of the array 107 until the printing material 104 is positioned within the ejector nozzle 108. For example, the printing material 104 may be advanced to at least partially fill the ejector nozzle 108 (e.g., completely or substantially fill it).

[0094] In one embodiment, the printing material 104 is supplied as a solid or liquid and then advanced to the ejector nozzle 108 as a liquid phase. For example, the printing material 104 can be supplied to the reservoir 140 or to a plurality of ejector conduits 106 in the form of one or more solid or liquid filaments. If the printing material 104 is supplied as a solid, the printing material is heated to molten state using, for example, a heater mechanism 126 as described herein, before it is flowed through the ejector conduit to the ejector nozzle. In one example, molten state can occur in the reservoir 140 before or just as the printing material enters the reservoir 140. Once molten state occurs, the liquid, i.e., molten printing material 104 is maintained above its molten temperature and advanced by flowing the printing material to the ejector nozzle 108.

[0095] The desired supply rate of the printing material may differ for each ejector nozzle 108. This supply rate may depend on the rate at which the printing material is ejected from the ejector nozzles 108, and this ejection rate may depend on the number of ejections per unit time from each nozzle and the droplet size per ejection.

[0096] The printing material 104 may be any conductive material. In one example, the printing material includes at least one metal. This at least one metal can be selected from, for example, tin, tin alloys, lead, lead alloys (e.g., solder containing one or both of tin and lead), aluminum, aluminum alloys (e.g., aluminum alloys of the 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series such as 6061 and 6063, and 7000 series), magnesium, magnesium alloys, iron, iron alloys (e.g., steel), copper, copper alloys (e.g., zinc), nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Preferred alloys of the above metals may include mixtures of any desired metals, such as mixtures of two or more of the above elemental metal printing materials (e.g., mixtures of two or more of aluminum, magnesium, iron, copper, nickel, titanium, and silver). In one embodiment, the printing material 104 has a metal content of more than 90% by weight, such as about 95% to 100% by weight, or 98% to 100% by weight, or 99% to 100% by weight, or 99.5% to 100% by weight, or 99.8% to 100% by weight, or 99.9% to 100% by weight.

[0097] For example, printing material 104 is approximately 1 × 10 at 20°C. -6 Ohm * m or approximately 1 x 10 -7 Ohm * m~approx.x1×10 -8 Ohm * m etc, 1 x 10 at 2℃ -5 Ohm * It has a resistivity of less than m (for example, it is conductive at room temperature (20°C)). In one example, the printing material 104 has a resistivity of about 1 × 10⁻¹⁶ while in solid form, liquid form, or both solid and liquid forms, and while at a temperature within 300°C from its melting point. -6 Ohm * m~approx.x1×10 -8 Ohm * m, etc., 1 x 10 -5 Ohm *It has a resistivity of less than m. The printing material can have any desired melting temperature. For example, the printing material has melting temperatures in the ranges of about 50°C to about 3000°C, about 100°C to about 2000°C, about 150°C to about 1600°C, about 500°C to about 1200°C, and about 600°C to about 1000°C.

[0098] As shown in Figure 21, 224, a magnetic field is provided within the ejector nozzle 108, thereby forming a flux region 133 (e.g., Figure 4B) within the printing material 104 placed within the ejector nozzle of one or more ejector conduits. This can be achieved, for example, by immersing at least a portion of the ejector nozzle 108 in a magnetic field supplied by a magnetic field source 130, as described herein. In one embodiment, the ejector nozzle 108 remains continuously immersed in the magnetic field throughout the operation of the printer ejection mechanism 100. In another embodiment, the magnetic field is periodically turned on and off as needed, for example, by connecting and disconnecting the flux guide 134 to a magnet 132 using a switch (not shown), or by using an electromagnet as the magnet 132 in combination with the flux guide 134 and switching the electromagnet on and off. In this case, the magnetic field is controlled to turn on when a current is pulsed between electrodes 110, 112 to provide an electromagnetic force.

[0099] As shown in Figure 21, 226, the method involves passing an electric current through a flux region 133 in an ejector nozzle 108 of one or more ejector conduits, thereby ejecting at least a portion of the printing material 104 from the ejector nozzle 108 onto, for example, a printing substrate 102. Passing the electric current may include transmitting an electric current pulse between a first electrode 110 and a second electrode 112 using a current pulse generation system 114, such as one of the current pulse generation systems described herein.

[0100] When the current i is pulsed through the conductive printing material 4 between electrodes 110 and 112 in the ejector nozzle 108 in a direction substantially perpendicular to the direction of the magnetic field B, a Lorentz force is generated on the conductive printing material 104 through which the current flows. Generally speaking, the Lorentz force, and thus the ejection force, i.e., momentum, of the printing material ejected from the ejector nozzle 108, is proportional to the cross product of the current i and the magnetic flux density B in the flux region.

[0101] The amount of current (e.g., pulse amplitude) and length of the current pulse used to achieve the desired momentum of the ejected printing material depend on factors such as the type of printing material, the magnetic flux density in the flux area, and the amount of printing material being ejected, and can be easily determined by those skilled in the art. In addition to providing momentum for ejection, shorter current pulse lengths can also potentially enable faster ejection rates (e.g., an increase in the number of printing material ejected per second from the same ejector nozzle).

[0102] In embodiments where electrodes 110 and 112 are used to separate droplets from the remaining printing material 104 within the ejector conduit 106, the direction of the current between electrodes 110 and 112 can be reversed immediately after the discharge current has pulsed through the conductive printing material 104 to forcibly discharge a portion of the liquid printing material 104 from the ejector nozzle 108. Reversing the direction of the current reverses the Lorentz force on the portion of the printing material 104 remaining in the nozzle 108, thereby pulling a portion of the column of liquid printing material back into the printing nozzle 108. This can help increase the force at the necking-off point of the liquid printing material where the droplet is formed, so that the droplet is more easily separated from the remaining column of printing material. In an alternative embodiment, the current flow is stopped immediately after the current pulse has passed through the conductive printing material 104 to push the liquid out of the ejector nozzle 108. In this embodiment, the initial pulse of current is sufficient to provide the desired droplet formation and discharge of the printing material 104 without reversing the direction of the current flow between electrodes 110 and 112.

[0103] While the discharge of the printing material 104 is achieved using a single pulse of current, it may also be useful to achieve discharge using two or more pulses of current from the same or multiple electrode pairs. For example, the desired discharge of the printing material can be achieved using two, three, or more high-speed pulses, in contrast to a single, longer pulse. In general, any desired pulse waveform can be selectively selected to optimize fluid flow and discharge.

[0104] The droplet size can be individually selected on demand. In one embodiment, the droplet size can be varied by changing the current pulse energy of each pulse (e.g., by changing the pulse length and / or amplitude of the current pulse). In another embodiment, multiple addressable electrode pairs (similar to those shown in Figure 16B, where each electrode is driven independently) can be used to vary the droplet volume. Thus, during operation, the current generation system can be used to send electrical pulses between a first number of electrode pairs in the ejector nozzle 108 (e.g., one or more of the electrode pairs 110a and 112a, 110b and 112b, and 110c and 112c in Figure 16B) to eject a first droplet volume, and then to send electrical pulses between a second number of electrode pairs to eject a second droplet volume different from the first droplet volume, where the first number of electrode pairs are different from the second number of electrode pairs. Therefore, in this process, the droplet size of the printing material discharged in the first discharge will be different from the droplet size of the printing material discharged in the second discharge.

[0105] The droplet size per ejection can be selected based on a variety of factors, including the desired size of the details in the object being printed, specific properties of the printing material (e.g., heat transfer and thermal expansion properties), the characteristics of the current pulse supplied to the printing material, and the nozzle size. While droplets can generally have a diameter as small as the inner diameter of the ejector nozzle 108, they can potentially have significantly larger diameters if longer lengths of printing material (e.g., liquid filament) are ejected during a single ejection. In one embodiment, the length of printing material ejected in a single ejection (e.g., using a single pulse) is approximately 1 to 10 times the inner width (e.g., diameter) of the printing nozzle 108 each time the printing material is ejected.

[0106] In one embodiment, the ejector conduit 106 further includes a second electrode pair (e.g., electrodes 144, 145 in Figure 4A) positioned upstream of the ejector nozzle. The flux region 133 extends to the printing material 104 located in a reloading region 170 of the passage adjacent to the second electrode pair, so as to enable the generation of an electromagnetic force, such as a Lorentz force, between the electrodes of the second electrode pair for controlling the flow of the printing material. In one embodiment, advancing the printing material 104 in the passage 106C involves passing a current through the second electrode pair, thereby separating the reloaded portion of the printing material 104 located in the reloading region 170 from the rest of the printing material 104 positioned upstream of the second electrode pair, and further flowing the reloaded portion of the printing material into the ejector nozzle. In this way, a desired amount of printing material for ejection can be delivered to the ejector nozzle 108.

[0107] In one embodiment, the ejector conduit 106 further includes a third electrode pair (electrodes 146, 147 in Figures 2 and 4A) positioned upstream of the second electrode pair (electrodes 144, 145). The flux region 133 extends to the printing material 104 positioned close to the third electrode pair, allowing for the generation of an electromagnetic force (e.g., a Lorentz force) between the electrodes of the second electrode pair to control the flow of the printing material. In one embodiment, when the second electrode pair is used to reload the ejector nozzle 108 as described above, advancing the printing material 104 may include passing a current through the third electrode pair (146, 147) to thereby move the printing material positioned upstream of the second electrode pair (144, 145) into the reloading region 170. This may occur simultaneously with, or after, the second electrode pair (144, 145) pushing the reloading portion of the printing material out of the reloading area 170 to refill the nozzle 108.

[0108] In one embodiment, advancing the printing material may include passing an electric current through a third electrode pair (146, 147) to cause the portion of the printing material 104 located upstream of the second electrode pair (144, 145) to either i) stop flowing or ii) flow away from the reloading region 170 (Figure 4A). This may occur simultaneously with the second electrode pair (144, 145) generating an electromagnetic force (e.g., a Lorentz force) to push the printing material in the reloading region into the ejector nozzle 108. By using the second electrode pair to push the material into the nozzle 108 while the third electrode pair (146, 147) stops or reverses the flow of printing material upstream of the reloading region 170, the reloaded portion of the printing material can be separated from the rest of the upstream portion of the printing material. Furthermore, by controlling the current pulse amplitude and / or current pulse length for the second and third electrode pairs, a measured volume of the printing material can be separated as a reload portion and transported to the first electrode pair (110, 112) in the ejector nozzle 108. There, the printing material can be accelerated to a desired speed and ejected on demand.

[0109] After the ejection of the printing material 104, additional printing material 104 can be advanced to refill the ejector nozzle or nozzle 108, and then a current pulse is repeated to eject the additional printing material. i) Refill the nozzle 108 by advancing the printing material (for example, by generating a Lorentz force using an additional electrode pair and / or by flowing the printing material using hydrostatic pressure or other means), ii) Dispell the printing material by providing a current pulse to electrodes 110, 112 in the ejector nozzle 108. This process can be repeated any number of times as needed for each of the ejector nozzles 108 in the array until printing is complete, thereby forming a 2D or 3D object. During printing, the ejection of the printing material 104 can occur from only a single ejector nozzle 108 in the array at a time, from two or more ejector nozzles 108 simultaneously, and / or from all of the ejector nozzles 108 in the array simultaneously, as needed to achieve a particular printing process.

[0110] In one embodiment, discharging at least a portion of the printing material involves flowing a sheath gas near the ejector nozzle, the sheath gas comprising one or both an inert gas and a reducing gas. An example of using a sheath gas is shown by arrow 210 in Figures 1 and 20. The sheath gas flow can be achieved in any preferred manner, for example, by flowing the sheath gas through a sheath gas vent 212 located within or near the printer ejection mechanism 100, such as within the array 107 and / or ejector housing 120. In one embodiment, the sheath gas is maintained at a desired temperature to avoid cooling the printing material before deposition. For example, the sheath gas temperature may be above the melting point of the printing material. In this way, the printing material can be kept in a molten state until deposition on the substrate occurs, if necessary. In one embodiment, the sheath gas can move at approximately the same speed and in approximately the same direction as the droplets when the droplets are discharged.

[0111] The magnetic field can be provided by any suitable source, including any of the magnetic field sources described herein. In one embodiment, the magnetic field source includes a permanent magnet. This method may include cooling the permanent magnet to bring its temperature below the Curie temperature or within the proposed operating temperature range in order to avoid a large decrease in magnetic field strength. For example, the magnet may be cooled to maintain a temperature below 200°C, such as a temperature in the range of about 0°C to about 160°C. Cooling of the magnet may occur for the magnet 132 used with or without the flux guide 134, as described herein. Any suitable cooling technique can be used, such as circulating a cooling fluid in close proximity to the magnet (e.g., by flowing the cooling fluid through a conduit (not shown) positioned to cool the space surrounding the magnet, or by flowing the cooling fluid across the surface of the magnet, or by flowing a coolant through the inside of the magnet or the flux guide). The cooling fluid can be circulated using any suitable mechanical system, such as a pump, fan, blower and / or compressor, to cool the magnet. In one embodiment, instead of cooling the magnet, or in addition to cooling it, the flux guide can be cooled to a desired operating temperature range. Any of the techniques and / or cooling systems enumerated herein for cooling the magnet can be used to cool the flux guide.

[0112] Next, a method for mixing separate printing materials and discharging the mixed printing materials to form, for example, a metal alloy will be described. This method uses an ejector device 300 including an ejector conduit 306, as shown in Figures 12 to 15 and as described herein. As described for other ejector devices herein, in the case of an array, multiple ejector conduits can be used. In one embodiment, the method includes supplying a conductive first printing material 104A (Figure 14) to a first passage 306C (Figure 12) which fluidly connects a first end 306A of the ejector conduit 306 to a conduit junction 306D. The first end is configured to receive the first printing material from a feeder mechanism, such as from a reservoir 140 (Figure 1), for example. The method further includes supplying a conductive second printing material 104B (Figure 14) to a second passage 306E that fluidly connects the second end 306B of the ejector conduit 306 to the conduit junction 306D. The second end 306B is configured to receive the second printing material 104B.

[0113] The first printing material 104A and the second printing material 104B flow into a conduit junction 306D where the flows merge and mixing occurs, and using current pulses from each, a desired amount of each material is pushed into the common receiving conduit junction 306D. A first amount of the first printing material 104A and a second amount of the second printing material 104B are mixed to provide a third mixed printing material 104C. Then, an electromagnetic force (e.g., a Lorentz force) is generated to discharge droplets of the mixed printing material 104C from the ejector nozzle 108 onto, for example, the printing substrate. The process of flowing, mixing, and generating electromagnetic forces is repeated to discharge additional droplets of printing material and form a three-dimensional object on the printing substrate.

[0114] Unlike other ejector nozzles as described herein, the ejector nozzle 108 includes a first electrode 110 and a second electrode 112 that form a first electrode pair. Generating an electromagnetic force includes providing a flux region 133 (as shown by the dotted line in Figure 14, for example) and passing a current pulse between the first electrode 110 and the second electrode 112 within the flux region 133.

[0115] In one embodiment, the ejector conduit 106 further includes a second electrode pair (e.g., electrodes 308 and 310) located in the first passage 306C and a third electrode pair (e.g., electrodes 312 and 314) located in the second passage 306E. The flux region 133 may extend to the printing material 104 located in the first reloading region 170A (Figure 12) of the first passage 306C, adjacent to the second electrode pair, and to the second reloading region 170B of the second passage 306E, adjacent to the third electrode pair. The first amount of the first printing material 104A flowing through the conduit junction 306D can be controlled by passing a current having a first current pulse through the second electrode pair. Similarly, the second amount of the second printing material 104B flowing through the conduit junction 306D can be controlled by passing a current having a second current pulse through a third electrode pair.

[0116] In one embodiment, controlling a first amount of the first printing material 104A further includes separating a first amount of the first printing material 104A, located in the first passage 306C, from the rest of the printing material located upstream of the second electrode pair (308, 310). Similarly, controlling a second amount of the second printing material 104B includes separating a second amount of the second printing material 104B, located in the second passage 306E, from the rest of the second printing material 104B located upstream of the third electrode pair (312, 314). The separation of the first and second amounts of the printing materials 104A and 104B can occur before mixing the printing materials.

[0117] In one embodiment, the ejector conduit 106 further includes a fourth electrode pair (e.g., electrodes 310, 316) positioned upstream of a second electrode pair (e.g., electrodes 308, 310). A fifth electrode pair (e.g., electrodes 314, 320) is positioned upstream of a third electrode pair (e.g., electrodes 312, 314). The flux region 133 extends to the printing material 104 positioned adjacent to the fourth and fifth electrode pairs, as shown, for example, in Figure 14.

[0118] The fourth electrode pair (310, 316) and the fifth electrode pair (314, 320) can be used to control the flow of portions of the printing material in passages 306C and 306E, respectively. For example, to independently control the flow of the printing material from the feeder mechanism 113 (e.g., reservoir 140) to the second electrode pair (308, 310) and / or the third electrode pair (312, 314), and / or to independently control the amount of printing material 104A, 104B and / or to separate the reloading portions when used in combination with the second electrode pair (308, 310) and the third electrode pair (312, 314), as described herein for the second electrode pair (144, 145) and the third electrode pair (146, 147) in Figure 4A. For example, the method involves passing a current having a third current pulse through a fourth electrode pair (310, 316) for any of the following purposes: i) to flow printing material into the reloading area 170A; ii) to stop the flow of printing material; or iii) to flow the printing material away from the reloading area 170A while the reloading portion is separated from the first printing material 104A remaining upstream of the reloading portion, thereby controlling the flow of the portion of the first printing material located upstream of the second electrode pair (308, 310). This may include, i) flowing the printing material into the reloading area 170B, ii) stopping the flow of the printing material, or iii) flowing the printing material away from the reloading area 170B while the reloading portion is separated from the second printing material 104B remaining upstream of the reloading portion, thereby controlling the flow of the second printing material positioned upstream of the third electrode pair (312, 314).

[0119] A first current pulse flowing through a second electrode pair (e.g., 308, 310) may have a first pulse amplitude and a first pulse length. A second current pulse flowing through a third electrode pair (e.g., 312, 314) may have a second pulse amplitude and a second pulse length. A third current pulse flowing through a fourth electrode pair (e.g., 310, 316) may have a third pulse amplitude and a third pulse length. A fourth current pulse flowing through a fifth electrode pair (e.g., 314, 320) may have a fourth pulse amplitude and a fourth pulse length. The amplitudes of the first, second, third, and fourth pulses, and the lengths of the first, second, third, and fourth pulses, can be independently selected to be the same as or different from the pulse amplitudes and lengths transmitted to other electrode pairs (for example, the amplitude and / or length of the first current pulse may be the same as or different from the amplitude and / or length of the second, third, and / or fourth current pulses). By selecting the amplitude and pulse length of the current pulses for the second, third, fourth, and fifth electrode pairs, the amounts of each printing material 104A and 104B separated as reloaded portions in the reloading regions 170A and 170B can be independently controlled. In this way, different amounts of each printing material 104A and 104B can be mixed and discharged to obtain an alloy containing printing materials in any desired ratio. Furthermore, alloy structures with gradient metal concentrations and / or various different alloy concentrations can be printed. If necessary, it may also be possible to discharge droplets containing only the first printing material 104A or only the second printing material 104B. Thus, the first droplet of discharged material may be printing material 104A, printing material 104B, or a mixture of printing materials 104A and 104B, and the second droplet discharged from the same ejector conduit 306 may be printing material 104A, printing material 104B, or a mixture of printing materials 104A and 104B, and the concentrations of printing materials 104A and 104B in the first droplet may differ from those in the second droplet.

[0120] The printing materials 104A and 104B can each be independently selected from any of the printing materials taught herein, as long as both printing materials melt at the desired operating temperature. In one embodiment, the first printing material is a first metal and the second printing material is a second metal, and the first and second metals are different. As an example, both the first and second metals can be independently selected from tin, tin alloys, lead, lead alloys (e.g., solder containing one or both of tin and lead), aluminum, aluminum alloys (e.g., aluminum alloys of the 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series such as 6061 and 6063, and 7000 series), magnesium, magnesium alloys, iron, iron alloys (e.g., steel), copper, copper alloys (e.g., zinc), nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. The resulting mixed printing material 104C (Figure 14) (sometimes referred to as the third printing material in this specification) is an alloy of the first and second metals.

[0121] In any of the methods of this disclosure, the printer ejection mechanism can operate at an ejector nozzle temperature that is approximately the melting temperature of the printing material 104 or higher. For example, the nozzle temperature may be in the range of about 50°C to about 3000°C, and for many metals, it will be above about 500°C, such as about 500°C to about 2000°C, about 600°C to about 1500°C, or about 600°C to about 1000°C. For printing material 104 including refractory materials, the nozzle temperature may be in the range of about 1000°C to about 3000°C, such as about 1200°C to about 3000°C, or about 1400°C to about 2500°C, or about 1700°C to about 2500°C, or about 2000°C to about 2500°C.

[0122] In any of the methods of this disclosure, the printing material 104 is ejected from the ejector nozzle 108 as a liquid in the form of droplets. The droplets can optionally have a relatively small droplet size, which can enable printing of fine details. For example, the droplet diameter may be in the range of about 0.001 mm to about 0.2 mm, about 0.005 mm to about 0.1 mm, or about 0.01 mm to about 0.05 mm. Droplets with larger diameters, such as droplets of about 0.5 mm, about 1 mm, or about 2 mm or more, can also be potentially formed as needed. In one embodiment, the droplet diameter is 100 micrometers (0.1 mm) or less, such as 90 micrometers, 80 micrometers, or 70 micrometers or less.

[0123] The method of the present disclosure can be used to deposit printing material 104 simultaneously or separately from any number of ejector conduits 106, as desired. The method can also allow the deposit of small amounts of material from any one ejector nozzle 108, while still providing a relatively high overall deposition rate due to the potentially large number of ejector conduits 106 in the array and the potentially high ejection rates from each ejector conduit 106.

[0124] The printer ejection mechanisms for ejecting printing materials described herein can be used in a variety of printing methods. For example, any of the printer ejection mechanisms described herein can be used in a three-dimensional printing method in which printing material 104 (Figure 1) is ejected from ejector nozzles 108 and deposited onto a printing substrate 154 (Figures 19 and 20), such as a build plate. Either or both of the printing substrate 154 and the array 107 of ejector nozzles 108 can move relative to each other in any preferred manner in three dimensions (e.g., along the x, y, and z axes) during printing, thereby forming a 3D object. As is well known in the art, 3D printing involves printing multiple droplets or layers of material, each droplet or layer can be stacked on top of each other until a desired thickness of the 3D object is achieved. Figure 20 shows an example of a printer ejection mechanism 100 including multiple ejector conduits 106 that simultaneously eject droplets 200 to print a 3D object 202 on a printing substrate 154. Numerous layers 204 of droplets 200 can be deposited one after another in units of one layer or droplet until the 3D object 202 is completed. As will be readily understood by those skilled in the art, the droplets and / or layers can be stacked in any desired order, for example, such that the first base layer 204 may or may not be completed before the subsequent layers begin, and there may or may not be a recognizable layer pattern in relation to the order of material deposition. Rather, the droplets, layers, and / or parts of layers can be stacked in any desired order to complete the 3D object.

[0125] Embodiments of this disclosure relate to a method for fabricating an ejector device including one or more ejector conduits, such as an array of ejector conduits, as described herein. The method includes providing a substrate, such as one of the substrates described herein. One of the ejector conduits as described herein is formed on the substrate. This may include forming one or more (e.g., multiple) electrode pairs on the substrate, each of which electrode pairs includes a first electrode and a second electrode. One or more (e.g., multiple) open passages are formed for flowing printing material. Each open passage has a first end for receiving the printing material and a second end for discharging the printing material. As described herein, the first and second electrodes of at least one electrode pair are exposed within the second end of an open passage to form an ejector nozzle.

[0126] Figures 23A to 23C illustrate a method for forming an ejector device according to one embodiment of the present disclosure. In one embodiment, the ejector device is a MEMS. Referring to Figure 23A, a substrate 402 is provided. The substrate may include any of the substrate materials described herein. In one embodiment, the substrate includes an insulating material. Multiple electrode pairs 404 are formed, for example, by blanket depositing a conductive layer on the substrate and patterning the conductive layer to form patterned conductive layers 403 for a first electrode 404A and a second electrode 404B for each of the multiple electrode pairs 404. The conductive layer may be patterned using any suitable photolithography technique. Alternatively, the electrode pairs 404 may be selectively deposited on the substrate into a desired electrode pattern. The patterned conductive layer includes a first metal, such as aluminum, an aluminum alloy, copper, a copper alloy, or any other metal taught herein for use as an electrode.

[0127] Optionally, the first electrode 404A and the second electrode 404B may further include a passivation layer 405. The passivation layer 405 may include a second corrosion-resistant metal that is different from the first metal and resistant to chemical reactions with the sprayed printing material (e.g., molten metal). The passivation layer 405 can be formed by any preferred method, such as electroplating or other deposition techniques. For example, the passivation layer can be provided by electroplating iron onto the electrode pair. Such a passivation layer may be optionally applied to any of the electrodes described herein (e.g., electrodes 110, 112, 144, 145, 146, 147, 504A, 504B, 604A, 604B, and other electrodes).

[0128] In one embodiment, the first electrode 404A and the second electrode 404B each have a width W1 and a height H1, where the width is greater than the height. Alternatively, the height may be greater than the width. W1 and H1 include all conductive layers of the electrodes, including the passivation layer 405 if one is formed thereon.

[0129] Referring to Figure 23B, a first side wall 406A is formed on the first electrode 404A, and a second side wall 406B is formed on the second electrode 404B, forming a plurality of passages 106C. The first electrode 404A and the second electrode 404B are raised above the base material 402 so as to also form the side wall portions of the passages 106C.

[0130] In one embodiment, forming the side walls 406A and 406B of a plurality of open passages 106C involves depositing a side wall layer 406 on a plurality of electrode pairs. The side wall layer 406 can be blanket-deposited and then patterned by photolithography techniques to form a plurality of channels within the side wall layer 406, the channels including a first side wall 406A adjacent to a first electrode 404A and a second side wall 406B adjacent to a second electrode 404B. The distance between the first side wall 406A and the second side wall 406B determines the width of the open passage. Using known techniques, a heater mechanism 126 can be optionally embedded in the side wall layer 406 and / or the substrate 402. Any of the heater mechanisms 126 disclosed herein may be used. For example, the sidewall layer 406 can be deposited as two thinner, stacked insulating layers, and a conductive heating element can be formed between the stacked insulating layers, thereby embedding the conductive heating element in the sidewall layer 406. The conductive heating element can be formed using any suitable technique, such as well-known deposition techniques, photolithography techniques, and etching techniques.

[0131] In one embodiment, the ejector conduits shown in Figures 23A-23C can be fabricated using printed circuit board ("PCB") manufacturing technology. PCB technology is a scalable and relatively inexpensive approach to manufacturing such arrays. For example, the substrate 402 may include a flexible insulating substrate, such as a polyimide or other fiber-free PCB substrate. The patterned conductive layer 403 for electrodes 404A, 404B includes a metal that can be deposited at a relatively low temperature suitable for a PCB substrate, such as copper or aluminum. The passivation layer 405 is optionally applied, for example, by electroplating copper or aluminum with a flash of iron or another metal that does not chemically interact with the ejected printing material at the operating temperature, or is resistant to chemical interaction with the ejected printing material at the operating temperature. The sidewall layer 406 for fabricating the sidewalls 406A, 406B may be, for example, a deposited and photolithographically patterned solder mask. The flexible substrate 402 can be laminated onto a carrier substrate 408, such as a substrate containing a fiber-reinforced material (e.g., FR4), at any point during the manufacturing process.

[0132] In one embodiment, the relatively broad and thin electrodes 404A and 404B shown in Figures 23A and 23C support molten metal confined by the insulating sidewalls 406A and 406B of the sidewall layer 406. The sidewall layer 406 may include any suitable insulating material, including any of the insulating materials described herein or a combination of insulating materials, such as any of the insulating materials described herein, as described above, relative to the sidewall layer 143. The insulating material can be optionally selected to have a desired contact angle with the printing material to provide a confinement effect and / or capillary effect, as discussed herein. If necessary, some or all of the electrodes 404A and 404B may be routed through sublayers in a multilayer PCB stack (not shown), as is generally known in the art.

[0133] Another example of a method for fabricating the ejector device of this disclosure is shown in Figures 24A to 24C. In one embodiment, the ejector device is a MEMS. This method involves etching a plurality of trenches 500 in a substrate 502. The substrate 502 may include any suitable substrate material described herein, such as semiconductors (e.g., compound semiconductors or group IV semiconductors such as silicon), insulating materials such as glass and ceramics, or combinations thereof. If the printing material 104 has a low melting point, such as below 300°C, it is also possible to use a lower temperature substrate such as a polymer substrate (e.g., FR4 or polyimide). In one embodiment, the substrate includes an embedded insulating layer, such as an embedded insulating layer 608 of a silicon-on-insulator ("SOI") substrate, as shown in Figure 25A.

[0134] The trench 500 can be formed by any preferred method. An exemplary method involves patterning the substrate using photolithography, and then etching the substrate using, for example, dry reactive ion etching ("DRIE") or wet etching techniques. When an SOI substate is used, the embedded insulating layer can optionally function as an etching stop, which can either form the bottom of the trench or be removed.

[0135] Trench 500 is filled with a conductive material to form electrodes 504A and 504B for each of a plurality of electrode pairs 504. The conductive material includes a metal, such as one of the metals described herein used as electrodes. In one embodiment, electrodes 504A and 504B each have a width W2 and a height H2, where the width is less than the height. Narrower and thicker electrodes can allow for a higher linear density of the ejector. The metal can be deposited in the trench using any preferred technique. Examples include filling the trench with copper using a damascene process including electroplating, or depositing a metal layer by chemical vapor deposition ("CVD") followed by chemical mechanical planarization ("CMP").

[0136] Referring to Figure 24C, a first sidewall 506A is formed adjacent to the first electrode 504A, and a second sidewall 506B is formed adjacent to the second electrode 504B, forming a plurality of passages. In one embodiment, forming the first sidewalls 506A and the second sidewalls 506B of a plurality of open passages involves depositing a sidewall layer 506 on a plurality of electrode pairs 504. The sidewall layer can be blanket-deposited and then patterned by photolithography techniques to form a plurality of channels within the sidewall layer 506, the channels including a first sidewall 506A adjacent to the first electrode 504A and a second sidewall 506B adjacent to the second electrode 504B. The distance between the first sidewall 506A and the second sidewall 506B of the channel determines the width of the open passage 106C. A heater mechanism, such as any of the heater mechanisms taught herein, can be embedded in an insulating sidewall layer including sidewalls 506A, 506B or in a substrate 502, similar to the one described herein for the ejector device in Figure 23C.

[0137] The insulating material for the sidewall layer is selected to be fire-resistant and electrically insulating. The sidewall layer 506 may include any suitable insulating material, including any of the insulating materials described herein or a combination of insulating materials, such as any of the materials described above for the sidewall layer 143. The insulating material can be optionally selected to have a desired contact angle with the printing material so as to provide a confinement effect and / or capillary effect, as discussed herein.

[0138] Figures 25A to 25E illustrate yet another method for forming the ejector device of the present disclosure. In one embodiment, the ejector device is a MEMS. As shown in Figures 25A to 25C, a trench 600 is formed within a substrate 602. The trench is filled with metal to form a plurality of electrode pairs, including a first electrode 604A and a second electrode 604B. The substrate 602, the method for forming the trench 600 and the method for forming the electrode pairs 604 may be the same as described above with respect to Figures 24A and 24B, except that the electrodes are configured to hold the printing material within a metal rail rather than metal resting on a rail. This can be achieved, for example, by forming the trench 600 to have a relatively high aspect ratio, such as an aspect ratio in the range of about 1 / 1 to about 30 / 1, about 2 / 1 to about 25 / 1, or about 10 / 1 to about 20 / 1. The high aspect ratio trench 600 allows the subsequently formed electrode pair 604 to form relatively high sidewalls 604C while still enabling low electrode series resistance.

[0139] In one example, a trench 600 is formed using a silicon-on-insulator substrate having a thickness of an upper Si layer 603 corresponding to a desired depth of the trench. Exemplary thicknesses range from about 10 micrometers to about 1000 micrometers, about 25 micrometers to about 500 micrometers, or about 50 micrometers. The trench can have sidewalls with a desired relatively high aspect ratio by patterning, for example, using photolithography techniques and then etching using DRIE. Etching can be stopped at a buried oxide layer 608. Electrodes 604A, 604B can then be formed in the trench by, for example, electroplating of a metal, followed by chemomechanical planarization (CMP). Such patterning, etching, electroplating, and CMP methods can also be optionally used in a dual damascene process to form vias for multilayer electrode configurations (not shown). Multilayer metallized structures are generally well known and can be readily used by those skilled in the art to form the electrodes of this disclosure.

[0140] Following the formation of electrodes 604A and 604B, the silicon portion of the substrate 602 between the electrode pairs is removed by any preferred process, as shown in Figure 25D, to form an open passage 106C. The removal process may include patterning the substrate using photolithography techniques to expose only the silicon region to be removed from the substrate 602, followed by an etching process, such as a DRIE or wet etching process, to remove the silicon region. The embedded insulating layer 608 may optionally function as an etching stop during this etching process. Optionally, a sidewall layer 143 is deposited before the removal of the silicon portion between the electrodes. The sidewall layer 143 may include any preferred insulating material, such as any of the insulating materials described herein or a combination of insulating materials. The sidewall layer 143 may be patterned using the same or a different process as used to remove the silicon region.

[0141] Optionally, portions of the embedded insulating layer 608 can also be removed to form a gap 612 as part of the passage 106C, as shown in Figure 25E. This embedded oxide can optionally be slightly etched beneath electrodes 604A and 604B, so that the electrodes protrude slightly from the underlying oxide layer, as shown in Figure 25E. Portions of the embedded insulating layer 608 can be removed using any suitable etching process, such as selective oxide etching (e.g., buffer oxide etching), as is well known in the art. Optionally, removing the embedded insulating layer 608 from the bottom of the trench 600 can better allow the liquid metal to be suspended between electrodes 604A and 604B, and between the other portions of rails 148 and 149.

[0142] The ejector conduits disclosed herein can be manufactured and used as open channel structures. For example, ejector conduits 106 manufactured by the processes shown in Figures 23A–23C, 24A–24C, and 25A–25E, as described herein, can be used to manufacture an open channel device having at least one side open to the atmosphere along the length of the passage. Alternatively, the ejector conduit can include a closed channel by mounting two open channel structures facing each other (for example, as shown in Figure 11), as will be discussed in more detail below. Mounting can be achieved by any preferred technique, such as bonding, tightening, or fastening them together using any type of fasteners. In yet another embodiment, a closed channel device can be formed by covering a single open channel array structure with a plate containing, for example, ceramic, glass, or other insulating material. For example, the bottom array 107 can be covered with an interposer layer 250 as shown in Figure 11, without using the top array 107. The term “closed channel” refers to a passage 106C that is enclosed on all sides along its length but remains open at, for example, a first end 106A and a second end 106B, to allow for the receipt and discharge of printing material 104. Figure 11 shows an example of such a closed channel configuration.

[0143] In one embodiment, a method for forming a closed channel array of ejector conduits includes forming a first array 107 of ejector conduits including a first plurality of open passages 106C, and forming a second array 107 of ejector conduits including a second plurality of open passages 106C. The first and second arrays can be formed by any of the methods described herein for fabricating such arrays. Examples of such arrays 107 having open ejector conduits are shown in the ejector conduits of Figures 3, 9, and 10, and Figures 12 and 13. The method further includes attaching the first array 107 of ejector conduits to the second array 107 of ejector conduits, thereby surrounding the first plurality of open passages to form a surrounded first passage 106C-1 (Figure 11), and surrounding the second plurality of open passages to form a surrounded second passage 106C-2. As also shown in Figure 11, the first and second arrays of ejector conduits are oriented to face each other, so that the first enclosed passage 106C-1 is adjacent to the second enclosed passage 106C-2. This method optionally includes including an interposer layer 250 between the first array 107 of ejector conduits and the second array 107 of ejector conduits.

[0144] In one embodiment, the array mounting may include the use of removable fasteners 252 that allow the first array of ejector conduits to be easily removed from the second array of ejector conduits after the mounting process has been performed. Examples of removable fasteners include screws or clamps, which may be optionally used with alignment pins or other lithographically complementary patterned features that allow the first and second arrays to be aligned as needed when fastened together, with or without the interposer layer 250. This configuration achieves the advantages of 3D capillary behavior, including the ability to pressurize the printed material in the conduits for potentially improved flow. At the same time, this configuration allows for the advantages of an open channel architecture, such as easy cleaning, when the closed array configuration is disassembled into a first open array and a second open array. Alternatively, if the advantages of an open channel architecture are not desired, such a 3D configuration can be manufactured as a monolithic structure, for example, by permanently joining the first array to the second array.

[0145] Any method described herein, such as any method for fabricating either an open-channel ejector conduit or a closed-channel ejector conduit, can be used to fabricate any of the ejector conduits described herein. For example, these methods can be used to fabricate any of the ejector conduits 106 described herein having a single electrode pair, as well as ejector conduits having 2 to 5 electrode pairs, including ejector conduits used for mixing two or more printing materials.

[0146] While the ejector devices of this disclosure have generally been described as comprising an array of ejector conduits, it is intended that any of the ejector devices described herein may include a single ejector conduit or a plurality of ejector conduits. Furthermore, any of the methods for manufacturing an ejector device described herein can be applied to manufacture an ejector device comprising either a single ejector conduit or a plurality of ejector conduits on a substrate. Similarly, an ejector device comprising only a single ejector conduit may be used in any of the printers or printer ejection mechanisms described herein, and / or in any of the methods for printing or ejecting printing materials described herein.

[0147] The following embodiments are illustrative and do not limit, nor imply, the scope of the present invention as described in the claims.

[0148] Theoretical Examples Example 1: Molten Metal Ejection Using Lorentz Force: Molten metal (e.g., molten aluminum) is supplied into a refractory tube (e.g., fused silica). The refractory tube includes two tungsten electrodes positioned at its ends. The electrodes are connected to a current source and positioned within the tube to conduct current through the molten metal adjacent to the ends of the tube. A permanent magnet cooled within its operating temperature range is positioned adjacent to the ends of the refractory tube to provide a magnetic flux region near the ends of the tube. The strength of the magnetic field provided by the magnet in this flux region is approximately 0.8 Tesla. At least a portion of the molten metal is positioned adjacent to the ends of the silica tube (e.g., so that the meniscus of the molten metal is positioned at the ends of the silica tube). A single current pulse is passed through a 0.0001-meter end portion of the silica tube within the magnetic flux region using the current source, thereby applying a Lorentz force to the molten metal. The free meniscus of the molten metal is accelerated axially within the tube. As shown in Table 1, the acceleration of the molten metal inside the tube is equivalent to an energy that exceeds the energy required to separate the droplets of molten metal from the liquid and expel those droplets from the tube; therefore, the droplets of molten metal are ejected from the tube.

[0149] [Table 1]

[0150] While the numerical ranges and parameters described in this disclosure are approximations, the numerical values ​​described in specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors that inevitably arise from the standard deviation observed in each test measurement. Furthermore, all ranges disclosed herein should be understood to encompass any and all subranges contained therein.

[0151] While this teaching is presented in relation to one or more implementations, modifications and / or alterations can be made to the exemplary embodiments without departing from the spirit and scope of the attached claims. In addition, certain features of this teaching may be disclosed in relation to only one of several implementations, but such features may be combined with one or more other features of other implementations as desired and advantageous for any given function or particular function. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” and “with,” or their variations thereof, are used in any of the modes for carrying out the invention and in the claims, such terms are intended to be comprehensive in the same manner as the term “comprising.” Furthermore, the term “about” in the discussion and claims herein indicates that the enumerated values ​​may be modified to some extent, provided that the modifications do not result in process or structural incompatibility to the implementations shown. Finally, “exemplary” indicates that the descriptions are used as examples, not that they are ideal.

[0152] It will be understood that variations of those disclosed above, as well as other features and functions, or substitutes thereof, may be combined into many other different systems or applications. Various currently unforeseen or unprecedented substitutes, modifications, variations, or improvements may subsequently be made by those skilled in the art, and these are also intended to be covered by the following claims.

Claims

1. 1. A three-dimensional ("3D") printer comprising:

1. An ejector device comprising a substrate and a plurality of ejector conduits on the substrate, the ejector conduits being arranged in an array, each ejector conduit comprising: a first end positioned to receive a printing material; a second end including an ejector nozzle, the ejector nozzle including a first electrode and a second electrode; an ejector device including: a passage for allowing the printing material to flow from the first end to the second end, wherein at least one surface of the first electrode is exposed within the passage and at least one surface of the second electrode is exposed within the passage; a current pulse generating system electrically connected to the first electrode and the second electrode of each of the plurality of ejector conduits; a magnetic field source proximate the second end of each of the plurality of ejector conduits to generate a flux field disposed within the ejector nozzle of each of the plurality of ejector conduits during operation of the three-dimensional printer; a positioning system for controlling a relative position of the ejector device with respect to a printing substrate in a manner that enables the printing substrate to receive jettable printing material from the ejector nozzle of each of the plurality of ejector conduits during operation of the three dimensional printer.

2. 2. The three dimensional printer of claim 1, wherein one or more of the plurality of ejector conduits each include a third electrode and a fourth electrode, at least one surface of the third electrode is exposed within the passageway, at least one surface of the fourth electrode is exposed within the passageway, and the third electrode and the fourth electrode are a second electrode pair.

3. 3. The three dimensional printer of claim 2, wherein one or more of the plurality of ejector conduits each include a fifth electrode and a sixth electrode, at least one surface of the fifth electrode is exposed within the passageway, at least one surface of the sixth electrode is exposed within the passageway, and the fifth electrode and the sixth electrode are a third electrode pair.

4. 4. The three dimensional printer of claim 3, further comprising a first rail and a second rail, the first rail and the second rail being disposed proximate to the passageway, with at least a portion of the passageway being positioned between the first rail and the second rail, the first rail including the first electrode and optionally one or both of the third electrode and the fifth electrode, and the second rail including the second electrode and optionally one or both of the fourth electrode and the sixth electrode.

5. 5. The three dimensional printer of claim 4, wherein at least a first portion of the first rail and at least a first portion of the second rail comprise at least one metal selected from copper, copper alloys, platinum, platinum alloys, aluminum, aluminum alloys, palladium, palladium alloys, iron, iron alloys, nickel, nickel alloys, silver, silver alloys, magnesium, magnesium alloys, titanium, titanium alloys, and refractory metals.

6. 5. The three dimensional printer of claim 4, further comprising a sidewall layer disposed proximate to the first rail and the second rail, the sidewall layer being patterned to form a first sidewall and a second sidewall, the distance between the first sidewall and the second sidewall defining a width of the passage.

7. 7. The three dimensional printer of claim 6, wherein the sidewall layer comprises a material selected from a metal oxide, a metal oxynitride, a metal nitride, a metal carbide, a polymer, and combinations thereof.

8. The three-dimensional printer of claim 1 , wherein the substrate comprises at least one material selected from an insulating material and a semiconducting material.

9. The three dimensional printer of claim 1 , wherein the passageway is an open channel having at least one side open to the atmosphere along the length of the passageway.

10. The three dimensional printer of claim 1 , wherein the passageway is a closed channel that is surrounded on all sides along the length of the passageway.

11. 10. The three dimensional printer of claim 1, further comprising: a heating mechanism for melting a solid printing material into a liquid printing material; and a reservoir for holding the liquid printing material, the reservoir in fluid communication with the plurality of ejector conduits.

12. The three dimensional printer of claim 1 , wherein the magnetic field source is configured to provide a magnetic field substantially perpendicular to a direction of current flow through the printing material.

13. 2. The three dimensional printer of claim 1, wherein the magnetic field source is a flux circuit including a magnet and a flux guide attached to the magnet, the flux guide being positioned proximate to the ejector nozzle for each of the plurality of ejector conduits.

14. The three-dimensional printer of claim 1 , wherein the magnetic field source comprises a permanent magnet.

15. The three-dimensional printer of claim 1 , further comprising a cooling system for cooling the magnetic field source.

16. 10. The three dimensional printer of claim 1, wherein the current pulse generating system includes at least one controller disposed in circuit with a power supply, at least one current switch, and the controller provides variable control of one or more characteristics selected from current amplitude and pulse length.

17. 10. The three dimensional printer of claim 1, wherein the ejector nozzle has an inside width ranging from about 10 micrometers to about 1000 micrometers.

18. 2. The three dimensional printer of claim 1, wherein the array has M columns of ejector conduits arranged on an X axis and N rows of ejector conduits arranged on a Y axis, where M is an integer between 3 and 1000, and N is an integer between 1 and 2.

19. The three-dimensional printer of claim 1 , wherein the ejector device is a micro-electromechanical system ("MEMS").

20. 1. A printer jetting mechanism comprising:

1. An ejector device comprising a substrate and an ejector conduit on the substrate, the ejector conduit comprising: a first end positioned to receive a printing material; a second end including an ejector nozzle, the ejector nozzle including a first electrode, a second electrode, a third electrode, and a fourth electrode, the first electrode and the second electrode being a first electrode pair, and the third electrode and the fourth electrode being a second electrode pair; an ejector device including: a passage for allowing the printing material to flow from the first end to the second end, wherein at least one surface of the first electrode is exposed within the passage, at least one surface of the second electrode is exposed within the passage, at least one surface of the third electrode is exposed within the passage, and at least one surface of the fourth electrode is exposed within the passage; a current pulse generating system electrically connected to the first electrode and the second electrode of the ejector conduit; a magnetic field source proximate the second end of the ejector conduit to generate a flux field disposed within the ejector nozzle during operation of the three dimensional printer.

21. 21. The printer ejection mechanism of claim 20, wherein the ejector conduit includes a fifth electrode and a sixth electrode, at least one surface of the fifth electrode is exposed within the passage, at least one surface of the sixth electrode is exposed within the passage, and the fifth electrode and the sixth electrode are a third electrode pair.

22. 22. The printer ejection mechanism of claim 21, further comprising a first rail and a second rail, the first rail and the second rail being disposed proximate to the passage, at least a portion of the passage being positioned between the first rail and the second rail, the first rail including the first electrode and optionally one or both of the third electrode and the fifth electrode, and the second rail including the second electrode and optionally one or both of the fourth electrode and the sixth electrode.

23. 23. The printer jetting mechanism of claim 22, further comprising a sidewall layer disposed proximate to the first rail and the second rail, the sidewall layer being patterned to form a first sidewall and a second sidewall, the distance between the first sidewall and the second sidewall defining a width of the passage.

24. 21. A printer jetting mechanism as claimed in claim 20, wherein the passage is an open channel having at least one side open to the atmosphere along the length of the passage.

25. 21. A printer jetting mechanism as claimed in claim 20, wherein the passage is a closed channel that is enclosed on all sides along the length of the passage.

26. 21. The printer jetting mechanism of claim 20, wherein the ejector device includes one or more additional ejector conduits on the substrate such that a plurality of ejector conduits are disposed on the substrate, the plurality of ejector conduits being arranged in an array.

27. 21. The printer ejection mechanism of claim 20, wherein the ejector device is a micro-electromechanical system ("MEMS").

28. 21. A three-dimensional printer comprising the printer jetting mechanism of claim 20.

29. 1. An ejector device, comprising: A substrate; an ejector conduit on the substrate, the ejector conduit comprising: a first end configured to receive a printing material; a second end including an ejector nozzle, the ejector nozzle including a first electrode, a second electrode, a third electrode, and a fourth electrode; an ejector conduit including a passage for allowing the printing material to flow from the first end to the second end, wherein at least one surface of the first electrode is exposed within the passage, at least one surface of the second electrode is exposed within the passage, at least one surface of the third electrode is exposed within the passage, and at least one surface of the fourth electrode is exposed within the passage.

30. 30. The ejector device of claim 29, wherein the ejector conduit includes a fifth electrode and a sixth electrode, at least one surface of the fifth electrode is exposed in the passage, at least one surface of the sixth electrode is exposed in the passage, and the fifth electrode and the sixth electrode are a third electrode pair.

31. 31. The ejector device of claim 30, wherein the passage is an open channel having at least one side open to the atmosphere along the length of the passage.

32. 31. The ejector device of claim 30, wherein the ejector device is a microelectromechanical system ("MEMS").

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