COMPLEX LASER FOLDING AND FABRICATION

Abstract

Provided, among other things, is a method of cutting and folding a planar substrate with a focused laser beam, directed from above the substrate, to form a shape with features in 3-dimensions, the method comprising: (a) executing from above laser cuts to the planar substrate so as to provide one or more a releasable segments; (b) executing from above one or more laser-executed upward folds to bend all or a portion of a releasable segment; and (c) executing from above one or more laser-executed downward folds to bend all or a portion of a releasable segment; wherein the cuts and folds are structured so that precursors to the 3D shape remain attached to the substrate while sufficient cuts and folds are made to form the 3D shape, and wherein the planar substrate is immobile during said steps (a) through (c), or is only moved in the plane of the substrate.

Claims

1. A method of cutting and folding a unpatterned substrate that defines a plane with a focused laser beam, directed from above the substrate, to form a shape with features in 3-dimensions, the method comprising: (a) executing from above laser cuts to the planar substrate so as to provide one or more a releasable segments; and (b) executing one or more folds to form the 3D shape by performing one or more of: (i) from above one or more laser-executed upward folds to bend all or a portion of a releasable segment; and (ii) from above one or more laser-executed downward folds to bend all or a portion of a releasable segment; wherein the cuts and folds are structured so that precursors to the 3D shape remain attached to the substrate while sufficient cuts and folds are made to form the 3D shape; wherein the planar substrate is immobile during said steps (a) through (c), or is only moved in the plane of the substrate; and wherein one or more of the following applies: (1) one or more substrate regions distinct from releasable regions are laser folded such that their edges adjacent to releasable segments are above or below the plane, thereby removing these regions from interfering in the formation of the shape; (2) both (b)(i) and (b)(ii) are executed; or (3) a reflector shape is cut and folded from one or releasable segments to provide a reflector to direct the focused laser beam to cut, etch or fold a portion of one of the releasable segments that would otherwise be inaccessible to the focused laser beam.

2. The method of claim 1, wherein the one or more of the folds comprises an upward or a downward fold in excess of 90.

3. The method of claim 2, wherein the one or more of the folds comprises an upward fold in excess of 90.

4. The method of claim 2, wherein the one or more of the folds comprises a downward fold in excess of 120.

5. The method of claim 1, wherein a reflector shape is cut and folded from one or more releasable segments to provide a reflector to direct the focused laser beam to cut, etch or fold a portion of one of the releasable segments that would otherwise be inaccessible to the focused laser beam.

6. The method of claim 5, further comprising impinging the focused laser beam orthogonal to the plane of the substrate.

7. The method of claim 1, wherein the substrate is conditioned to favor bending along at least one axis.

8. The method of claim 1, wherein the substrate is conditioned to favor bending along at least two axes.

9. The method of claim 1, further comprising providing the substrate to a fabrication zone from a roller.

10. The method of claim 1, further comprising holding the planar substrate immobile during said steps (a) through (c).

11. The method of claim 1, wherein one or more substrate regions distinct from releasable segments are laser folded such that their edges adjacent to releasable segments are above or below the plane, thereby removing these regions from interfering in the formation of the shape.

12. The method of claim 11, wherein one or more said edges are below the plane.

13. The method of claim 1, wherein both steps (b)(i) and (b)(ii) are executed.

14. A method of cutting and folding a unpatterned substrate that defines a plane with a focused laser beam, directed from above the substrate, to form a shape with features in 3-dimensions, the method comprising: (A) providing: a first reel configured for dispensing substrate; a second reel configured for receiving the substrate; a guide element for providing a flat area of substrate between the dispensing and receiving reels; and the laser configured to strike the substrate in the flat area; (B) executing from above laser cuts to the planar substrate so as to provide one or more a releasable segments; and (C) executing one or more folds to form the 3D shape by preforming one or more of: (i) from above one or more laser-executed upward folds to bend all or a portion of a releasable segment; or (ii) from above one or more laser-executed downward folds to bend all or a portion of a releasable segment; wherein the cuts and folds are structured so that precursors to the 3D shape remain attached to the substrate while sufficient cuts and folds are made to form the 3D shape, and wherein the planar substrate is immobile during said steps (B) through (D), or is only moved in the plane of the substrate pursuant to the operation of the reels.

15. The method of claim 14, further comprising depositing material on an element formed by the laser

16. The method of claim 14, further comprising operating a 3D printer configured to deposit material on an element formed by the laser.

17. A device for laser-implemented manufacture comprising: a first reel configured for dispensing a substrate; a second reel configured for receiving the substrate; a guide element for providing a flat area of substrate between the dispensing and receiving reels; a laser configured to impinge a focused beam onto the substrate in the flat area; and a controller configured to operate the laser to provide cuts, folds away from the laser, and folds towards the laser.

18. The device of claim 17, further comprising operating a means to deposit material on an element formed by the laser.

19. The device of claim 17, further comprising a 3D printer configured to deposit material on an element formed by the laser.

Description

DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only illustrative embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0011] FIG. 1A, FIG. 1B, FIG. 1C, FIG. 1D, and FIG. 1E show the operation of the TGM and BM mechanisms of folding;

[0012] FIG. 2A shows thermal simulations;

[0013] FIGS. 2B and 2C show upward and downward bend angles with the number of laser passes;

[0014] FIG. 2D, FIG. 2E, FIG. 2F and FIG. 2G show images from TGM bending experiments;

[0015] FIG. 2H shows an image from BM bending experiments;

[0016] FIG. 3A, FIG. 3B, FIG. 3C, FIG. 3D and FIG. 3F show manufactures;

[0017] FIGS. 4A and 4B show the workings of a coordinated construct, in this case to provide an etching mirror;

[0018] FIG. 4C, FIG. 4D, FIG. 4E, FIG. 4F and FIG. 4G show stages in an etching manufacture;

[0019] FIG. 5 shows an exemplary supply roll of substrate;

[0020] FIG. 6 shows a reel-to-reel device; and

[0021] FIG. 7 shows another reel-to-reel device.

[0022] To facilitate understanding, identical reference numerals have been used, where possible, to designate comparable elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0023] In laser forming, a laser triggers rapid temperature changes and resulting thermal stresses in a workpiece, causing permanent plastic deformation. The folding here uses two types of laser forming known as the temperature gradient mechanism (TGM) and buckling mechanism (BM), respectively. For TGM-based forming, the laser is scanned rapidly to heat the surface while not allowing time for the heat to spread vertically through the workpiece. The surface expands while the rest of the piece does not, resulting in bending away from the laser, a phenomenon known as counterbending. However, the cooler surroundings act to constrain this expansion, resulting in the buildup of plastic compressive stresses (FIG. 1A). As the region cools, contraction occurs (FIG. 1B) and the shape bends back. The final contraction during cooling is the dominant effect, and therefore the final bending direction for TGM is always toward the laser beam.

[0024] For the buckling mechanism, the laser is scanned more slowly so heat propagates through the thickness of the sheet resulting in a lateral temperature gradient (FIG. 1C). The heated region attempts to expand laterally but is again constrained, resulting in a buildup of compressive stresses. Once these stresses reach a threshold, an instability develops and the heated area buckles (FIG. 1D). As the laser travels across the fold, the buckle propagates across the surface resulting in bending, in the illustrated case away from the laser (FIG. 1E). In the absence of other constraints the laser exposed region is capable of buckling toward or away from the laser based on other factors such as orientation, residual stresses, or an applied force. Using a substrate that has been held in a roll, or otherwise conditioned to favor bending downward, and biasing it flat during the manufacturing process, assures that the BM bend is downward. Conditioning the substrate to bend in two dimensions, such as along axis x and along axis y (which can be orthogonal), increases the axes along which BM bends downwards. Two-dimensional biasing can be done by, for example, supplying the tape for a second roll by cutting a ribbon from a first roll at for example line 14 in the roll 10 (having seam 12) of FIG. 5. The ribbon can then be rolled lengthwise to create the second bias. Biasing the BM fold downwards can be done in a number of ways including prebending prior to clamping flat, applying an air stream, or using gravity to cause buckling downward.

[0025] Bending magnitude was measured for each mechanism by clamping 1.5 cm wide strips of metal shim stock into a holder and repeatedly scanning the laser at different travel speeds. The shim stock used was 80 m thick high purity (99.99%) nickel foil. Nickel was chosen as a common engineering material. It also has a thermal conductivity low enough to easily transition between the two bending modes with the travel speeds possible for the laser tool used in the experiments. Nickel has a yield strain of between 0.5% and 1%, and is able to survive tens of percent plastic deformation before breakage. The exemplary laser was a commercial 20 W, 1064 nm wavelength solid state pulsed fiber marking laser (MC Series, Full Spectrum Laser) with measured spot size roughly 80 m for the lens used (model SL-1064-112-163G, effective focal length 163 mm). This wavelength has a 10 smaller spot size than a 10 m CO2 laser and high absorbance into metals, 29% compared with 2% for the higher wavelength CO2. High absorbance reduces needed power for a given thickness, reducing laser cost. For comparison, 500 W lasers of the same wavelength from the same manufacturer (Full Spectrum Laser) exceed $120,000 compared with roughly $10,000 for the 20 W laser here. For bending, the laser was kept at low power (5 W) to minimize material loss; full power (20 W) was used for cutting in later sections. No active cooling was used in these exemplary manufactures, and the primary mechanism of cooling was passive thermal conduction of heat through the nickel sheeting.

[0026] The nickel was obtained and stored in coil form on a 95 mm diameter spool, resulting in a radius of curvature that served as a natural prebend to allow directional control for the buckling mechanism. The characterization in the examples used a given material and thickness. However, the laser forming technique is however general, and has been demonstrated for metal sheeting as thick as 6 mm as well as in microelectromechanical systems (MEMS) structures as thin as a few tens of micrometers. Sub-micrometer levels of positional accuracy have been demonstrated using this technique, and laser forming has also been used commercially for microadjustment of contacts, relays, and drive actuators for hard disk drives. For more information on the effects of individual laser parameters on the bending phenomenon, the reader is encouraged to look for example to S. P. Edwardson, A Study into the 2D and 3D Laser Forming of Metallic Components, (Ph.D. Thesis), University of Liverpool (United Kingdom), 2004, while H. Shen, F. Vollertsen, Modelling of laser formingAn review, Comput. Mater. Sci. 2009, 46, 834 gives an insightful overview of the different analytical and numerical models of laser forming. (These references are incorporated herein by reference in their entirety.)

[0027] Thermal simulations in the numerical solver COMSOL 5.2 were performed to estimate the time scales necessary to transition between TGM and BM modes (FIG. 2A). Such thermal simulations can be used to determine parameters for other substrates and thicknesses. For nickel of the dimensions used here, by about 2 ms the heating has spread vertically through the test piece and begun to spread laterally. Experimentally, travel speeds of 30 mm s1 were found to consistently trigger TGM bending (i.e., to always bend the workpiece upward), while 10 mm s1 was found to consistently trigger BM bending (i.e., to bend upward or downward based on the direction of the prebend in the sheeting before clamping). Travel distances of the laser in 2 ms for the TGM and BM settings are 60 and 20 respectively. With known laser spot size of 80 this corresponds well with the estimated time scale from the simulation.

[0028] Side-view images were taken after individual passes in the experiments and an image processing tool (GIMP 2.8 (GNU Image Manipulation Program, gimp.org) was used to extract the bending angle (FIGS. 2B, 2C) for each mechanism, with estimated measurement accuracy about 1. Individual passes were spaced 15 s apart for cooling. For both mechanisms, the first few passes were found to give bending of roughly 2, with the bend per pass dropping gradually with larger number of passes. This reduction is believed to result from the combined effects of strain hardening, section thickening, absorption variation, and geometrical changes. For the TGM bending (upward, toward the laser), the piece folding eventually blocks the laser, self-limiting the maximum to 90, and the test was ended when the laser was visibly blocked. In embodiments where the laser angle (and possibly height) can be manipulated, greater angles can be achieved. Since the BM folding in this case moves away from the laser, the laser is never blocked and larger angles are possible. With this material, the maximum for BM folding was 110 before bending ceased, possibly due to the metal partially moving out from under the laser path. Again, with a laser that can be manipulated for angle of orientation, it is believed that greater bends can be achieved.

[0029] Experiments were also performed toward a complete (180) fold with each mechanism. Patterns were first cut using repeated passes by the laser at full power (20 W) and high speed (100 mm s1), followed by laser induced bending. Although bending upward in the TGM mode blocks the laser, and therefore is limited to 90, it is possible to make twofold in close proximity to make a V (FIGS. 2D-G), which can be folded almost into contact. The spacing shown is 400 m; this distance sets the minimum spacing between the raised plates seen in the experiments. Unlike folds upward from TGM, downward bends do not block the laser, allowing complete 180 folds. FIG. 2H shows folding downward to almost flat on the underside (FIG. 2K). Since scanning repeatedly in the buckling mode along a single fold does not reach 180 as discussed previously, the complete fold here was obtained through a set of three folds 200 m apart. It is believed that a complete fold can be achieved with two closely spaced folds.

[0030] One of the advantages of using a commercial marking laser is the ease of rapidly prototyping a variety of self-assembled parts (FIGS. 3A to 3F). All pieces were cut and folded without manual handling. In FIG. 3A, a raised ARL logo was cut and folded. This demonstrates marking (etching a pattern on the surface at low power) and cutting at high power followed by a single TGM upward fold. Video S1, included with the Supporting Information at the aforementioned Advanced Materials Technologies article website, shows the part as it goes through each stage.

[0031] The same technique can be used for creating more complex parts such as cubes (FIG. 3B), which require a total of six upward folds. One of the main challenges for a completely enclosed structure is the need to avoid blocking the laser beam during folding. This was done by designing the order and position of the folds such that the final fold was exposed until the end of the process. This final fold, at the bottom of the cube, consisted of two 45 folds, 400 m apart, similar to the V-fold depicted in FIG. 2F. By doing this final fold at an angle, the cube folds almost closed before the laser is blocked. There is also evident discoloration due to nickel oxidation at higher temperatures. This effect is not fundamental to the technique, and can be minimized by increasing the time delay between individual passes of the laser (to allow more time for cooling) or by plumbing in an inert atmosphere.

[0032] FIG. 3C shows a part made through a combination of upward and downward folds (temperature gradient and buckling folds, respectively). The paper airplane analog consists of six folds, with each individual wing folded using an initial upward fold (the tip) followed by a downward fold (the wing) and a final upward fold to create the plane body. In observing the folding process (Video S2, included with the Supporting Information at the aforementioned Advanced Materials Technologies article website), one of the challenges in folding parts back and forth across the plane of the original sheet becomes quickly evident. At several points one of the wings becomes pinned by the edges of the outline, requiring a few cycles for the part to break through. For parts of this size scale, this is only a minor issue mostly resulting in a delay in assembly.

[0033] For smaller parts, however, building the force to break free is more difficult, requiring an alternative solution. One method investigated was to move the surrounding outline out of the way, allowing the assembled part to freely cross the exposed region. FIG. 3D shows a two-turn coil made using this approach; a large neighboring region is folded up out of plane, allowing the narrow nickel line to pass through the resulting hole in the sheet. The coil consists of eight distinct upward folds in addition to the fold moving the surroundings up. Nearly continuous bending is also possible using a series of tightly spaced folds, each a few degrees, to approximate a curved structure such as an arc or cylinder. See e.g., M. Nunobiki, K. Okuda, K. Hourai, H. Shizuka, Bending of Pure Titanium Sheet to Curved Surface Shape by Laser Forming Technique, Adv. Mater. Res. 2010, 126, 388-393, herein incorporated by reference in its entirety. FIG. 3E shows a nearly complete cylinder consisting of two arcs bending upward to come together at a center fold. As with the cube, upward bending is limited by the eventual blocking of the laser; no such restriction is present for downward bending, allowing arcs greater than 180 using buckling (FIG. 3F).

[0034] The ability to precisely control angle and position using the marking laser also opens up the possibility of interaction between multiple parts, again without manual intervention. For demonstration, one specific challenge was attempted: testing whether it is possible to mark the underside of the metal sheet without flipping it over by hand. More specifically, a simple system was designed to fold a nickel flap up out of plane, move the surface originally on the underside in front of an optical reflector, use reflected laser light to pattern the surface, and then move the part away in preparation for further assembly.

[0035] FIG. 4A shows a simplified diagram of the workings of the marking laser. From a fixed source, the laser is reflected from mechanically positioned mirror, then through an F-theta lens, a lens incorporating designed distortion to maintain focus at a constant distance (163 mm from the lens for this laser) along a flat plane according to a simple positioning algorithm. Metal positioned above the plane of focus will not be hit by a focused laser, but rather by more dispersed light. If one folds a plate out of plane and then shine onto its surface, the laser will be too dispersed to cut, instead heating slightly and reflecting most of the light. Given the long distance from the lens (163 mm) and the small size of the target region (a nearly square region roughly 45 mm on a side, placed near the center of the marking laser cutting area), the beam can be considered almost normal to the cutting plane. Since the marking laser is designed to focus a known distance (the focal length F) from the lens, maintaining the same travel distance for the reflected light should similarly focus the laser. For a reflector at 45, this distance will occur along a vertical plane at the reflector base (where the vertical distance F plus the lateral distance sum to F, as in FIG. 4B).

[0036] FIGS. 4C to 4F shows marking using this technique. First, a reflector was cut and folded out of plane to 45 (FIG. 4C). A nearby region was cut and then folded vertical using one fold, followed by a second fold to rotate it sideways to align along the reflector base (FIG. 4D). These folds were designed to match the first stages of a cube similar to that in FIG. 3B. Note the face now positioned in front of the reflector was originally on the underside of the sheeting. The letters ARL were then scanned on the reflector (and reflected onto the side of the cube) for marking (FIG. 4E), done in a series of single loops at high speed (500 mm s1) and high power (20 W), to both compensate for the loss in energy in the reflection and minimize thermal deformation of the reflector. Finally, the part was folded 45 upward, allowing the possibility of further assembly (FIG. 4F). A close up of the final marked surface is shown in FIG. 4G.

[0037] These experiments demonstrate using a tabletop marking laser to create complicated 3D structures out of thin metal sheets. Starting with blank, unpatterned sheeting, laser cutting, and forming is used to cut and assemble parts containing both upward and downward folds without manual handling. Laser forming is also used to precisely align two components, demonstrating the positioning of an optical reflector to guide the laser and pattern a portion of the sheeting originally inaccessible on the underside. At this price point, these processes will enhance the small scale metal fabrication capabilities for a wide range of researchers, educators, and small businesses.

[0038] Substrate Materials

[0039] Any number of materials and material thicknesses can be used in this methodology, as guided for example by thermal modeling. Different lasers, laser powers or spot sizes can be selected based on the material and the thickness, as guided for example by thermal modeling. It is believed that thicknesses as high a 1 cm or above can be folded. In embodiments, the substrate is 5 mm or less in thickness, or 2 mm or less, or 1 nm or less, or 500 microns (m) or less.

[0040] Exemplary materials include nickel, nickel.titanium, copper, various steel alloys including stainless steel, titanium, aluminum, iron/aluminum alloy, copper alloys like brass and bronze, and the like. Exemplary materials further include crystalline materials such as silicon, borosilicate glass, alumina (Al.sub.2O.sub.3) ceramic, and the like.

[0041] Fold Angles

[0042] In embodiments of the invention, high fold angles are achieved with closely spaced lines of laser heating. For example, TGM folds in excess of 90 using a vertically aligned laser can be achieved with two or more such lines (and two releasable segments). Or, BM folds of in excess of 120 can be achieved. All folding of metal tend to have an element of curvature. Those of skill in metal working will recognize when the material is bent at an angle substantially between two planes, and when there is a more sustained curvature. This same knowledge is applicable to non-metallic substrates.

[0043] Laser Control

[0044] The invention can provide great flexibility with a laser oriented orthogonal to the plane of the substrate. The laser can be operated in multiple locations in 3D space, and with multiple orientations utilizing for example computer numerical control (CNC) mechanisms.

[0045] Reel-to-Reel Machines, Incorporated Deposition

[0046] For any kind of meaningful production, however, there is a significant disadvantage of having to manually place and clamp in metal sheeting for production. This manual transfer of substrates, what is known as batch or sheet processing, is however standard in most self-folding manufacturing, and is a major reason why it has remained primarily in the laboratory.

[0047] In the printing industry, it is common to use continuous feedstock transferred through a series of processing steps as it transfers between two rolls of flexible material, what is known as roll-to-roll (or reel-to-reel) processing. This technique removes the need for substrate transfer. In this disclosure, the use of a roll-to-roll type process for laser-implemented fabrication. Substrate sheeting is transferred from one roll to a fixed height using a guide that defines a manufacturing position. The substrate located in the manufacturing position can be subjected to laser-implemented fabrication. After the manufacture, the residual substrate can be transferred to a second roll and another blank region of substrate moved into the manufacturing position.

[0048] FIG. 6 illustrates an exemplary reel-to-reel device 20. Reel 22 supplies substrate 24 to manufacturing position 28. Guide 26 keeps the substrate flat in the manufacturing position. The guide can have a through slot through which the substrate arrives, and slot to both sides. The guide can be of a lubricious polymer such as polytetrafluoroethylene or the line. In embodiments, there is a through slot through which the substrate leaves the manufacturing position. The substrate is taken up by second reel 30. In the illustration, there is a reel guide 32. Motor 34 pulls the substrate through the manufacturing zone. The motor can be for example various DC or AC motors, such as a brushless DC motor, a high resolution stepper motor, a high resolution servo motor, or the like.

[0049] In the manufacturing process the flexible foils are transferred between the two rollers through the guide, which sets the height. In the manufacturing zone the laser (above, not shown) is used to cut and fold 3D components.

[0050] A roll-to-roll laser cutter configured for rapidly creating 3D parts is an important new innovation allowing self-folding origami to be done at a large scale.

[0051] FIG. 7 shows schematically another reel-to-reel device 120. The numbering matches the numbering in FIG. 6, but advanced by 100. The new elements are a second manufacturing guide 136, a second manufacturing zone 138, material deposition device 142 (such as a 3D printer head), and a laser 140. The manufacturing guides can be such that enough of the top surface of the substrate 124 is unobstructed when the substrate moves from the first manufacturing zone 128 to the second 138. In embodiments, there is a second motor so that the substrate can be moved between the two manufacturing zones as different elements of the fabrication are effected. With such a device incorporating deposition of additional elements (such as 3D printing), additional elements can be associated by deposition with the construct of the laser-implemented fabrication. A material deposition device can for example add material by welding, gluing or adhering, using a physical attachment device such as a bolt, rivet, or the like, 3D printing, or other deposition/attachment means. Robotic elements and controls can be incorporated in to the material deposition device.

[0052] Misc.

[0053] Reference to downward folds means folds away from the laser, and upward folds are towards the laser. Recitations of above and below are relative to setting the frame of reference with the laser being above the substrate. It will be recognized that the apparatus can be set in different orientations such with the substrate being horizontal, or the laser being inverted, yet the relative orientation of the laser is still above the substrate. Thus, downward, above, and below are relative designations with respect to the laser, and not literal designations.

[0054] All ranges recited herein include ranges therebetween, and can be inclusive or exclusive of the endpoints. Optional included ranges are from integer values therebetween (or inclusive of one original endpoint), at the order of magnitude recited or the next smaller order of magnitude. For example, if the lower range value is 0.2, optional included endpoints can be 0.3, 0.4, . . . 1.1, 1.2, and the like, as well as 1, 2, 3 and the like; if the higher range is 8, optional included endpoints can be 7, 6, and the like, as well as 7.9, 7.8, and the like. One-sided boundaries, such as 3 or more, similarly include consistent boundaries (or ranges) starting at integer values at the recited order of magnitude or one lower. For example, 3 or more includes 4 or more, or 3.1 or more. If there are two ranges mentioned, such as about 1 to 10 and about 2 to 5, those of skill will recognize that the implied ranges of 1 to 5 and 2 to 10 are within the invention.

[0055] Where a sentence states that its subject is found in embodiments, or in certain embodiments, or in the like, it is applicable to any embodiment in which the subject matter can be logically applied.

[0056] This invention described herein is of a laser-driven manufacturing method and related machines. Although some embodiments have been discussed above, other implementations and applications are also within the scope of the following claims. Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the following claims. More specifically, those of skill will recognize that any embodiment described herein that those of skill would recognize could advantageously have a sub-feature of another embodiment, is described as having that sub-feature

[0057] Publications and references, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference in their entirety in the entire portion cited as if each individual publication or reference were specifically and individually indicated to be incorporated by reference herein as being fully set forth. Any patent application to which this application claims priority is also incorporated by reference herein in the manner described above for publications and references.