3D printed sensor and cushioning material

Methods, apparatus, systems and articles of manufacture are disclosed relating to 3D-printed structures. An example 3D-printed structure includes a first conductive substrate, a second conductive substrate and a dielectric structure between the first conductive substrate and the second conductive substrate, the dielectric structure including a latticed structure having a first stiffness in a first direction and a second stiffness in a second direction different than the first direction.

FIELD OF THE DISCLOSURE

This disclosure relates generally to sensors, and, more particularly, to a 3D printed sensor and cushioning material.

BACKGROUND

In recent years, 3D printing or additive manufacturing (AM) systems have emerged that execute instructions on a computer to form a specific three-dimensional object indicated by the instructions by iteratively building the three-dimensional object layer-by-layer.

DETAILED DESCRIPTION

FIG. 1is a schematic illustration of an example 3D-printed structure100in accordance with some teachings of this disclosure. The example 3D-printed structure100includes an example first conductive substrate110, an example dielectric structure120, and an example second conductive substrate130. The dielectric structure120, disposed between the first conductive substrate110and the second conductive substrate130, includes a latticed structure having a first stiffness in a first direction and a second stiffness in a second direction different than the first direction.

In some examples, the first conductive substrate110and/or the second conductive substrate130includes conductive carbon nanotube (CNT) filaments (e.g., approximately 10% CNT, etc.), graphene, graphide, nano metallization, silver nano wire and/or copper. For instance, the first conductive substrate110and/or the second conductive substrate130can include an elastomeric polymer composite including CNT filaments. In some examples, the dielectric structure120includes an elastomeric polyurethane (EPU), a thermoplastic polyurethane (TPU), and/or a thermoplastic elastomer (TPE). In some examples, the dielectric structure120includes an aliphatic TPU.

FIG. 1shows example first electrical connectors140built in the first conductive substrate110and example second electrical connectors150built in the second conductive substrate130. The 3D-printed structure100ofFIG. 1is operatively integrated into a circuit, such as an example sensor circuit, via example leads160,170or metallizations connected to the first electrical connectors140and the second electrical connectors150.

FIGS. 2A-2Ddepict views of the example 3D-printed structure100ofFIG. 1.FIG. 2Ais a top view of the example 3D-printed structure100ofFIG. 1showing an example first infill pattern200corresponding to an infill percentage of approximately 10% (+/−1%). The infill pattern relates to the relative hardness (e.g., Shore hardness) and flexibility of the material.FIG. 2Bis a side view of the example 3D-printed structure100ofFIG. 1showing the first conductive substrate110, the dielectric structure120, and the second conductive substrate130.FIG. 2Cis a front view of the example 3D-printed structure100ofFIG. 1showing the first conductive substrate110, the dielectric structure120, and the second conductive substrate130.FIG. 2BandFIG. 2Cshow example patterning corresponding to the first infill pattern200. In other examples, patterning of any of the first conductive substrate110, the dielectric structure120or the second conductive substrate130may differ from any other one or more of the first conductive substrate110, the dielectric structure120or the second conductive substrate130. For instance, the first conductive substrate110, the dielectric structure120and the second conductive substrate130may each have a different infill pattern and/or infill percentage. The example first infill pattern200, having an infill of approximately 10%, corresponds to a Shore hardness of about 44 A.

FIG. 2Dshows an exploded view of a portion ofFIG. 2Bincluding the first conductive substrate110, the dielectric structure120and the second conductive substrate130.FIG. 2Dshows the first conductive substrate110, the dielectric structure120and the second conductive substrate130each include a plurality of layers210that are iteratively applied, layer-by-layer, to form the 3D-printed structure100. In some examples, a layer height of each of the layers to build the first conductive substrate110, the dielectric structure120and/or the second conductive substrate130is between approximately 0.06 mm-0.10 mm. In some examples, a thickness of the first conductive substrate110, the dielectric structure120and/or the second conductive substrate130is between 0.1 mm-1.5 mm.

FIG. 2Eshows a perspective view of an example 3D-printed structure211having an example first conductive substrate212, an example dielectric structure214and an example second conductive substrate216similar to that of corresponding structures in the example 3D-printed structure100ofFIGS. 1-2D. As shown in the enlarged view at the right ofFIG. 2E, the first conductive substrate212of the 3D-printed structure211ofFIG. 2Ehas an example second infill pattern218corresponding to an infill percentage of approximately 80% (+/−2%) and a Shore hardness of 91 A. The dielectric structure214and the second conductive substrate216of the 3D-printed structure211can have an infill pattern and/or percentage similar to, or different from, the first conductive substrate212.

FIG. 2Fshows a perspective view of an example 3D-printed structure220having an example first conductive substrate222, an example dielectric structure224and an example second conductive substrate226similar to that of corresponding structures in the example 3D-printed structure100ofFIGS. 1-2D. As shown in the enlarged view at the right ofFIG. 2F, the first conductive substrate222of the 3D-printed structure220ofFIG. 2Fhas an example second infill pattern228corresponding to an infill percentage of approximately 40% (+/−1%) and a Shore hardness of 77 A. The dielectric structure224and the second conductive substrate226of the 3D-printed structure220can have an infill pattern and/or percentage similar to, or different from, the first conductive substrate222.

FIGS. 3A-3Cdepict the example 3D-printed structure100ofFIGS. 1 and 2A-2D.FIG. 3Ashows the layered structure of the 3D-printed structure100, as shown inFIG. 2D. A portion of the dielectric structure120ofFIG. 3Ais enlarged inFIG. 3Bto show that the dielectric structure120includes an example homogenous structure of a plurality of example unit cells300arranged in an example array to form a lattice structure. A portion of the dielectric structure120ofFIG. 3Bis enlarged inFIG. 3Cto show that an example structure for the unit cells300. The unit cell300includes an example upper portion310, an example middle portion320and an example lower portion330defining an hourglass shape with lateral dimensions of the middle portion320being smaller than lateral dimensions of the lower portion330and the upper portion310. In some examples, the unit cell300includes two oppositely oriented conic sections or truncated cones joined at a position between the apex and the base of the respective cones. The example upper portion310, the example middle portion320and the example lower portion330are shown to be symmetric about a junction335of the example upper portion310and the example lower portion330. In some examples, the unit cell300may be asymmetric with a junction335displaced upwardly or downwardly from the illustrated example ofFIG. 3C.

In the example ofFIG. 3C, the unit cell300includes an example base structure340, an example top structure345, and example legs350extending between the base structure340and the top structure345. The legs350extend inwardly by an example bend angle355from a vertical toward the middle portion320or junction335between the base structure340and the top structure345. InFIG. 3C, the bend angle355of the legs350relative to the base structure340is the same as the bend angle355of the legs350relative to the top structure345. In an example asymmetric unit cell300, a bend angle355of the legs350relative to the base structure340can differ from the bend angle355of the legs350relative to the top structure345.

InFIG. 3C, an arrow A1extending from the top structure345represents an example tensile force acting on the top structure345and arrows A2extending from the junctions335of two of the legs350represent example displacement vectors for the legs350responsive to application of the tensile force A1. While four legs350are shown inFIG. 3C, the unit cell300may include a greater number of legs350, or a lesser number of legs350. In some examples, the bend angle355is between approximately 10°-35° from the vertical (e.g., 10°, 14.92°, 15°, 20°, 25°, 30°, 32.25°, etc.).

FIGS. 4A-4Bare schematic illustrations of the example 3D-printed structure in accordance with the example ofFIGS. 1, 2A-2D and 3A-3Cand in accordance with some teachings of this disclosure.FIG. 4Ais a portion of the 3D-printed structure100, showing the first conductive substrate110, or a portion thereof, the dielectric structure120, and the second conductive substrate130, or a portion thereof. The portion of the dielectric structure120illustrated is an array, wherein the unit cell300is replicated along three axes to form an array of unit cells300. In some examples, the unit cells300are vertically staggered, as shown for example inFIG. 3B, so that a lower portion330of one unit cell300is aligned with an upper portion310of adjacent unit cells300.

FIG. 4Bshows that the portion of the 3D-printed structure100represented inFIG. 4Ais incorporated into an example helmet400having an example outer shell410made from aramide polyethylene, polycarbonate, fiberglass and/or Kevlar and an inner liner420, which may include a hard shell of a material similar to the outer shell410and/or an expanded polystyrene, a polypropylene (EPS) foam and/or an insulating layer. The 3D-printed structure100is disposed between the outer shell410and the inner liner420with the first conductive substrate110and the second conductive substrate130connected, via leads or metallizations, to a voltage source.

In some examples, a plurality of addressable 3D-printed structures100are provided in an array. For instance, the helmet400may include two or more (e.g., fore/aft, left/right, etc.), or even tens of, or hundreds of, separately addressable 3D-printed structures100. These 3D-printed structures100may occupy the entire space between the outer shell410and the inner liner420, or only a portion thereon. For instance, a plurality of 3D-printed structures100can be formed interspersed between a shock absorbing material such as, but not limited to, an expanded polystyrene (EPS) foam. The 3D-printed structures100may assume any form factor(s) (e.g., square, rectangle, strip, triangle, etc.) or tiles to occupy a desired geometry and may be continuous or discontinuous in distribution.

The 3D-printed structures100in the array absorb force via compression of the dielectric structure120and serve to identify a location of and an intensity of force, by virtue of a change in capacitance and/or a rate of change in capacitance (e.g., a change in voltage) arising from a strain in one or more dielectric structures120of one or more 3D-printed structures100. The change in capacitance and/or the rate of change in capacitance is correlatable to the force. For instance, application of a compressive force to the 3D-printed structure100, via a strain of the outer shell410of the helmet400, causes a corresponding strain in the dielectric structure120, which decreases a spacing between the first conductive substrate110and the second conductive substrate130and increases a capacitance. Data from the 3D-printed structures100can thus be used to provide a detailed understanding of impact locations and forces on the helmet400. Similarly, one or more 3D-printed structures100can be integrated into medical orthotics (e.g., braces, footwear inserts, etc.), shipping materials, protective cases, sports equipment, and/or footwear.

FIGS. 5A-5Billustrate an example application of an example 3D-printed structure100in an example leg brace500disposed about a user's leg505to be roughly symmetric with respect to the user's knee510. An example first securement member515(e.g., a strap having an adjustment device and/or a closure device, an elastic band, etc.) is disposed above the knee510to serve as an anterior/posterior thigh anchor and an example second securement member520is disposed below the knee510to serve as an anterior/posterior tibial anchor. An example first anterior strap525is attached at a proximal end to the first securement member515and at a distal end to an example lateral securement member535extending between the first securement member515and the second securement member520. An example second anterior strap530is attached at a proximal end to the second securement member520and at a distal end to the example lateral securement member535. The first anterior strap525is shown to include, inFIG. 5B, a 3D-printed structure100constructed to determine tensile forces545across the first anterior strap525during movement of the user. In some examples, the 3D-printed structure100is integrated into a sensor circuit. In some examples, the sensor circuit including the 3D-printed structure100is constructed to store data output by the 3D-printed structure100in a local memory device, to transmit data from the 3D-printed structure100and/or to provide feedback to the user and/or a medical care provider via an output device (e.g., a display device, a speaker, a haptic device, etc.).

FIG. 5Cillustrates an example application of one or more example 3D-printed structures100used in an example circuit550in accordance with the examples ofFIGS. 1-5B. The example circuit550can relate to the example application ofFIGS. 5A-5Bor to any other application using the example 3D-printed structure100and/or an example sensor array555of 3D-printed structures100A,100B . . .100N, where N is any integer, such as, but not limited to, a sensor circuit for a garment, footwear, protective equipment, shock absorbing device(s), orthotic device(s), prosthetic device(s), shipping material, packing material and/or padding. An example processor560receives signals output by the example 3D-printed structure100and/or the example 3D-printed structures (e.g.,100A,100B, . . .100N) of the example sensor array555. In some examples, an example memory565is operatively associated with the example processor560. The example memory565may include, for example, a mapping of the sensor array555and/or other location information for the example 3D-printed structure100and/or the example 3D-printed structures (e.g.,100A,100B, . . .100N) of the example sensor array555. The example memory565may include, for example, a mapping of strain(s) of each 3D-printed structure100along one or more axes relative to applied force(s). The example processor560, the example sensor array555and/or the example 3D-printed structure100are powered by one or more example power source(s)570. The example circuit550can include an interface580such as an Ethernet interface, a universal serial bus (USB), a wireless network interface controller (WINC), a network interface controller (NIC), and/or a PCI express interface. In the example circuit550, one or more input devices585(e.g., a microphone, a keyboard, a keypad, a button, a touchscreen, etc.) are connected to the interface580to permit a user to enter data and/or commands into the processor560and one or more output devices586(e.g., a speaker, a display device, a haptic device, etc.) are connected to the interface580to permit the processor560to communicate information to a user.

FIGS. 6A-6Bare example free body diagrams of a unit cell300of the dielectric structure120of the 3D-printed structure100. InFIG. 6A, a base structure340of the unit cell300is constrained, as indicated by the uniformly distributed circles605, and an axial force610is applied to a top structure345of the unit cell300.FIG. 6Ashows a bend angle380of0.FIG. 6Bshows, in dashed lines, an original state of the unit cell300before application of the axial force610, such as shown inFIG. 6A.FIG. 6Balso shows, in solid lines, a state of the unit cell300after the application of the axial force610. In the example ofFIGS. 6A-6B, the unit cell300is an auxetic structure having a negative Poisson ratio, wherein a positive strain along the axial direction in the direction of the axial force610generates a positive transverse strain625in the unit cell300, increasing the cross-sectional area under the axial strain to outwardly expand the legs350and decrease the bend angle380from θ to θ′.

FIGS. 6C-6Dshow, similar toFIGS. 6A-6B, a free body diagram of an example array of unit cells300of the dielectric structure120of a 3D-printed structure100before application of an axial force (FIG. 6C) and after application of an axial force (FIG. 6D). InFIG. 6C, base structures340of the unit cells300and the second conductive substrate130are constrained, as indicated by the uniformly distributed circles605, and an axial force640is applied to the first conductive substrate110, or another layer attached thereto, to impart an axial force on the array of unit cells300.

FIG. 6Dshows a state of the array of unit cells300after the application of the axial force640. In the example ofFIGS. 6C-6D, as withFIGS. 6A-6B, the unit cells300in the array of unit cells300are auxetic structures that exhibit a positive transverse strain responsive to the positive strain along the axial direction in the direction of the axial force640, and increase in cross-sectional area under the axial strain with outward expansion of the legs350of the respective unit cells300and with a decrease in the bend angles380of the respective unit cells300.

FIG. 7Aillustrates an example plot705of bend angle (in degrees) versus transverse deformation (in meters) for the example unit cell300ofFIGS. 6A-6BandFIG. 7Billustrates an example plot710of bend angle (in degrees) versus axial deformation (in meters) for the example unit cell ofFIGS. 6A-6B. At an example bend angle of 11.97 degrees, the transverse deformation is 7.90E-06 meters with an axial deformation of 4.09E-05 meters. At an example bend angle of 16.59 degrees, the transverse deformation is 1.79E-05 meters with an axial deformation of 7.56E-05 meters. At an example bend angle of 21.00 degrees, the transverse deformation is 3.50E-05 meters with an axial deformation of 8.20E-05 meters. At an example bend angle of 25.16 degrees, the transverse deformation is 6.46E-05 meters with an axial deformation of 1.00E-04 meters. At an example bend angle of 29.06 degrees, the transverse deformation is 8.83E-05 meters with an axial deformation of 1.25E-04 meters. At an example bend angle of 32.68 degrees, the transverse deformation is 1.53E-04 meters with an axial deformation of 1.86E-04 meters. At an example bend angle of 36.03 degrees, not shown inFIGS. 7A-7B, the transverse deformation is 2.36E-04 meters with an axial deformation of 3.11E-04 meters.FIGS. 7A-7Bshow that, as the bend angle increase, the axial displacement increases at a greater rate than the transverse displacement.FIG. 7Cillustrates an example plot715of bend angle versus negative Poisson Ratio for the example unit cell ofFIGS. 6A-6B. For the noted example bend angles of 11.97 degrees, 16.59 degrees, 21.00 degrees, 25.16 degrees, 26.09 degrees, 32.68 degrees and 36.03 degrees the calculated Poisson ratios are, respectively, 0.193, 0.237, 0.427, 0.646, 0.706, 0.823 and 0.759. Accordingly, there is an optimal bend angle720between about 25-32 degrees, at which point the Poisson Ratio of the unit cell300peaks.

FIGS. 7D-7Erespectively show an example first modelling730of axial deformation of an example first dielectric structure120having a first bend angle of 32.25° (FIG. 7D) and an example second modelling735of axial deformation of an example second dielectric structure120having a second bend angle of 14.92° (FIG. 7E) responsive to an applied tensile force. InFIGS. 7D-7E, as inFIGS. 6C-6D, base structures340of the unit cells300and the conductive substrate130are constrained and an axial tensile force is applied to the first conductive substrate110, or another layer attached thereto, to impart an axial tensile force on the array of unit cells300.

FIG. 7Fshows an example plot745of bend angle versus transverse displacement for the example 3D-printed structure100ofFIGS. 7D-7E.FIG. 7Falso shows an example plot750of bend angle versus transverse displacement for an example 3D-printed structure100similar to that ofFIGS. 7D-7E, but with a dielectric structure having a thickness twice that of the dielectric structure120(e.g., a height of 6 unit cells rather than 3 unit cells).FIG. 7Gshows an example plot765of bend angle versus negative Poisson Ratio for the example 3D-printed structure100ofFIGS. 7D-7E.FIG. 7Galso illustrates an example plot770of bend angle versus negative Poisson Ratio for an example 3D-printed structure100similar to that ofFIGS. 7D-7E, but with a dielectric structure having a thickness twice that of the dielectric structure120(e.g., a height of 6 unit cells rather than 3 unit cells).

Behavior of the 3-D structures100is similar to behavior of the individual unit cells300comprising the dielectric structure120of the 3-D structures100with respect to their axial and transverse displacement values. With increasing bend angle the transverse deformation increases slightly slower than the axial deformation. The major difference between the individual unit cells300and the array of unit cells300is that their Poisson Ratios behave differently with decreasing bend angle. For instance, an individual unit cell300has a peak Poisson Ratio at a bend angle of around 30°. However, an array of unit cells300has a Poisson Ratio that consistently rises with decreasing bend angles, as shown inFIG. 7G. Thus, while a greater transverse deformation can occur with larger bend angles, a greater transverse deformation for less axial deformation will occur with lower bend angles.

FIG. 8Ais a schematic illustration of an example first graded dielectric structure800for a 3D-printed structure100. The first graded dielectric structure800was evaluated with respect to transverse deformation, bend angle and Poisson Ratio. The first graded dielectric structure800includes a combination of first unit cells805and second unit cells810, with the first unit cells805further from the central axis812having a first bend angle355lower than a second bend angle814of the second unit cells810closer to the central axis812. Stated differently, the unit cells810closer to the central axis812of the first graded dielectric structure800have a larger bend angle than the unit cells810closer to the edge of the first graded dielectric structure800.

FIG. 8Bis a schematic illustration of an example second graded dielectric structure820for a 3D-printed structure100. The second graded dielectric structure820was also evaluated with respect to transverse deformation, bend angle and Poisson Ratio. The second graded dielectric structure820also includes a combination of first unit cells805and second unit cells810, but the first unit cells805further from the center830of the second graded dielectric structure820have a first bend angle355lower than a second bend angle814of the second unit cells810closer to the center830of the second graded dielectric structure820. Thus, the unit cells810closer to the center830of the second graded dielectric structure820have a larger bend angle than do the unit cells805at the corners of or periphery of the second graded dielectric structure820.

FIGS. 8C-8Drespectively illustrate an example modelling of axial deformation an example first graded dielectric structure820(FIG. 8C) and an example second graded dielectric structure840(FIG. 8D) responsive to an applied tensile force.

In the first graded dielectric structure820ofFIG. 8C, the unit cells of the first graded dielectric structure820include a plurality of first unit cells805and a plurality of second unit cells810arranged as inFIG. 8Awith the unit cells805being distributed further from the center axis of the first graded dielectric structure820and the unit cells810being distributed closer to the center axis of the first graded dielectric structure820. Thus, the bend angle of the unit cells805,810varies from a low of 14.92 degrees for the unit cells805at a periphery of the first graded dielectric structure820to a high of 32.25 degrees for the unit cells810adjacent the center axis. Accordingly, in the example ofFIG. 8C, the bend angle of the unit cells805,810decreases based on a distance from the center axis of the first graded dielectric structure820. While the example ofFIGS. 8A and 8Cdepicts two unit cells805,810, the first graded dielectric structure820can include more than two types of unit cells. For example, the first graded dielectric structure820can include three or more types of unit cells. For instance, a third type of unit cells may be disposed between the unit cells805and the unit cells810and may have a bend angle between about 14.92 degrees and about 32.25 degrees.

In the second graded dielectric structure840ofFIG. 8D, the unit cells of the second graded dielectric structure840include a plurality of first unit cells805and a plurality of second unit cells810arranged as inFIG. 8Bwith the unit cells805being distributed further from the center of the second graded dielectric structure840and the unit cells810being distributed closer to the center of the second graded dielectric structure840. Thus, the bend angle of the unit cells805,810varies from a low of 14.92 degrees for the unit cells805at a periphery of the second graded dielectric structure840to a high of 32.25 degrees for the unit cells810adjacent the center of the second graded dielectric structure840. Accordingly, in the example ofFIG. 8D, the bend angle of the unit cells805,810decreases based on a distance from the center of the second graded dielectric structure840. While the example ofFIGS. 8B and 8Ddepicts two unit cells805,810, the illustrated second graded dielectric structure840can include more than two types of unit cells. For example, the second graded dielectric structure840can include three or more types of unit cells. For instance, a third type of unit cells may be disposed between the unit cells805and the unit cells810and may have a bend angle between about 14.92 degrees and about 32.25 degrees.

FIG. 8Eis an example plot of bend angle versus transverse displacement for example dielectric structures andFIG. 8Fis an example plot of bend angle versus negative Poisson Ratio for example dielectric structures. Modelling was performed to optimize a dielectric structure820,840transverse deformation and Poisson ratio. InFIG. 8E, the horizontal dashed lines850,855represent a performance of the second graded dielectric structure840and the first graded dielectric structure820, respectively. The vertical lines860,865respectively illustrate the bend angle of an equivalent homogeneous dielectric structure. InFIG. 8F, the horizontal dashed lines870,875represent a performance of the second graded dielectric structure840and the first graded dielectric structure820, respectively. The vertical lines880,885respectively illustrate the bend angle of an equivalent homogeneous dielectric structure. By grading the dielectric structures820,840as noted with respect toFIGS. 8A-8D, deformation values of a homogeneous dielectric structure with a bend angle of about 26-27 degrees and a Poisson Ratio of a homogeneous dielectric structure with a bend angle of about 20-22 degrees are realized. Stated differently, graded dielectric structures, such as the first graded dielectric structure820and/or the second graded dielectric structure840, yield superior performance to a homogeneous dielectric structure. Further, the second graded dielectric structure840ofFIG. 8D(e.g., central point structure) outperformed the first graded dielectric structure840ofFIG. 8C(e.g., central axis structure).

An example manner of implementing a 3D build manager900is illustrated inFIG. 9. One or more of the elements, processes and/or devices illustrated inFIG. 9may be combined, divided, re-arranged, omitted, eliminated and/or implemented in any other way. The example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9may be implemented by hardware, software, firmware and/or any combination of hardware, software and/or firmware. Thus, for example, any of the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9could be implemented by one or more analog or digital circuit(s), logic circuits, programmable processor(s), application specific integrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)). When reading any of the apparatus or system claims of this patent to cover a purely software and/or firmware implementation, at least one of the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9is/are hereby expressly defined to include a non-transitory computer readable storage device or storage disk such as a memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-ray disk, etc. including the software and/or firmware. Further still, the example 3D build manager900ofFIG. 9may include one or more elements, processes and/or devices in addition to, or instead of, those illustrated inFIG. 9, and/or may include more than one of any or all of the illustrated elements, processes and devices.

The example 3D build manager900is to control a build of the 3D printed structure100, using a 3D printer or other additive manufacturing device, using the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9. The build material application manager910is to control dispensing of one or more build materials, such as one or more of the build materials used to form the first conductive substrate110, the dielectric structure120and/or the second conductive substrate130of the 3D printed structure, onto the build platform. The build platform manager920is to control a position of a 3D printer build platform relative to a build material applicator via one or more motors and/or actuators.

The memory930includes build data940which is used by the 3D build manager900to build the 3D printed structure100. The build data940may include instructions in a 3D printing file format including all model, material and property information necessary to form the 3D printed structure100using a 3D printer.

Example flowcharts representative of example machine readable instructions for implementing the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9are shown inFIGS. 10-11. In these examples, the machine readable instructions comprise a program for execution by a processor such as the processor1212shown in the example processor platform1200discussed below in connection withFIG. 12. The program may be embodied in software stored on a non-transitory computer readable storage medium such as a CD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), a Blu-ray disk, or a memory associated with the processor1212, but the entire program and/or parts thereof could alternatively be executed by a device other than the processor1212and/or embodied in firmware or dedicated hardware. Further, although the example program is described with reference to the flowcharts illustrated inFIG. 10, many other methods of implementing the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9to make the 3D-printed structures100ofFIGS. 1-8Dmay alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally or alternatively, any or all of the blocks may be implemented by one or more hardware circuits (e.g., discrete and/or integrated analog and/or digital circuitry, a Field Programmable Gate Array (FPGA), an Application Specific Integrated circuit (ASIC), a comparator, an operational-amplifier (op-amp), a logic circuit, etc.) structured to perform the corresponding operation without executing software or firmware.

As mentioned above, the example programs ofFIGS. 10-11may be implemented using coded instructions (e.g., computer and/or machine readable instructions) stored on a non-transitory computer and/or machine readable medium such as a hard disk drive, a flash memory, a read-only memory, a compact disk, a digital versatile disk, a cache, a random-access memory and/or any other storage device or storage disk in which information is stored for any duration (e.g., for extended time periods, permanently, for brief instances, for temporarily buffering, and/or for caching of the information). As used herein, the term non-transitory computer readable medium is expressly defined to include any type of computer readable storage device and/or storage disk and to exclude propagating signals and to exclude transmission media. “Including” and “comprising” (and all forms and tenses thereof) are used herein to be open ended terms. Thus, whenever a claim lists anything following any form of “include” or “comprise” (e.g., comprises, includes, comprising, including, etc.), it is to be understood that additional elements, terms, etc. may be present without falling outside the scope of the corresponding claim. As used herein, when the phrase “at least” is used as the transition term in a preamble of a claim, it is open-ended in the same manner as the term “comprising” and “including” are open ended.

The example program1000ofFIG. 10begins at block1005by building a first conductive substrate110via a 3D printer or other additive manufacturing device and the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9. As shown by way of example inFIG. 2D, the building of the first conductive substrate110can include sequentially building a plurality of layers210, layer-by-layer, to form the first conductive substrate110.

The example program1000ofFIG. 10then proceeds to block1110and the building of a dielectric structure120including a latticed structure, such as is represented by way of example inFIGS. 3A-4C, on the first conductive substrate110via a 3D printer or other additive manufacturing device, the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9. As shown by way of example inFIG. 2D, the building of the dielectric structure120can include sequentially building a plurality of layers210, layer-by-layer, to form the dielectric structure120.

The example program1000ofFIG. 10then proceeds to block1030and the building of a second conductive substrate130on the dielectric substrate120, such as is represented by way of example inFIG. 2D, via the 3D printer or other additive manufacturing device, the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9. As shown by way of example inFIG. 2D, the building of the second conductive substrate130can include sequentially building a plurality of layers210, layer-by-layer, to form the second conductive substrate130.

The example program1100ofFIG. 11begins at block1105by positioning a build platform of the 3D printer or other additive manufacturing device, via the example 3D build manager900and/or the example build platform manager920, for initiation of a building operation for the example 3D-printed structure100. Control then passes to block1110.

At block1110, the example 3D build manager900and/or the example build material application manager910deposit a layer of a 3D build material (e.g., a conductive material) to build the first conductive substrate110. Control then passes to block1115, where the example 3D build manager900determines, using the example memory930and/or the example build data940, whether a next layer of the 3D build material is to be applied to build the first conductive substrate110. If the outcome of block1115is in the affirmative (block1115=“YES”), then the example 3D build manager900and/or the example build platform manager920increment a position of the build platform for application of a next layer of the 3D build material for the first conductive substrate110in block1120and control passes back to block1110. The process of depositing a layer of 3D build material to build the first conductive substrate110, determination as to whether an additional layer of build material is to be applied to build the first conductive substrate110, and incrementing of a position of the build platform for application of a next layer of the 3D build material for the first conductive substrate110continues until the outcome of block1115is negative (block1115=“NO”), at which point control passes to block1125. At block1125, the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940deposit a layer of a 3D build material (e.g., a dielectric material) for the example dielectric structure120.

Control then passes to block1130and the example 3D build manager900determines, using the example memory930and/or the example build data940, if a next layer of the 3D build material for the dielectric structure120is to be deposited to build the dielectric structure120. If the outcome of block1130is in the affirmative (block1130=“YES”), then the example 3D build manager900and/or the example build platform manager920increment a position of the build platform for application of a next layer of the 3D build material for the dielectric structure120in block1135and control passes back to block1125. This process of depositing a layer of 3D build material for the dielectric structure120to build the dielectric structure120(block1125), determination as to whether additional layers of build material are required to be applied to build the dielectric structure120(block1130), and incrementing of a position of the build platform for application of a next layer of the 3D build material for the dielectric structure120(block1135) continues until the outcome of block1130is negative (block1130=“NO”).

At block1140, the example 3D build manager900and/or the example build material application manager910deposit a layer of a 3D build material (e.g., a conductive material) to build the second conductive substrate130. Control then passes to block1145, where the example 3D build manager900determines, using the example memory930and/or the example build data940, whether a next layer of the 3D build material is to be applied to build the second conductive substrate130. If the outcome of block1145is in the affirmative (block1145=“YES”), then the example 3D build manager900and/or the example build platform manager920increment a position of the build platform for application of a next layer of the 3D build material for the second conductive substrate130in block1150and control passes back to block1110. The process of depositing a layer of 3D build material to build the second conductive substrate130(block1140), determination as to whether an additional layer of build material is to be applied to build the second conductive substrate130(block1145), and incrementing of a position of the build platform for application of a next layer of the 3D build material for the second conductive substrate130(block1150) continues until the outcome of block1145is negative (block1145=“NO”), at which point the 3D-printed product100is completed and the process of building the 3D-printed product100ends.

FIG. 12is a block diagram of an example processor platform1200capable of executing the instructions ofFIGS. 10-11to implement the example 3D build manager900ofFIG. 9to produce the example 3D-printed products100ofFIGS. 1-8F. The processor platform1200can be, for example, a server, a personal computer, a mobile device (e.g., a cell phone, a smart phone, a tablet such as an iPad™), a personal digital assistant (PDA), an Internet appliance, or any other type of computing device.

The processor platform1200of the illustrated example includes a processor1212. The processor1212of the illustrated example is hardware. For example, the processor1212can be implemented by one or more integrated circuits, logic circuits, microprocessors or controllers from any desired family or manufacturer. The hardware processor may be a semiconductor based (e.g., silicon based) device. In this example, the processor implements the example 3D build manager900, the example build material application manager910, the example build platform manager920, the example memory930and/or the example build data940ofFIG. 9.

The processor1212of the illustrated example includes a local memory1213(e.g., a cache). The processor1212of the illustrated example is in communication with a main memory including a volatile memory1214and a non-volatile memory1216via a bus1218. The volatile memory1214may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/or any other type of random access memory device. The non-volatile memory1216may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory1214,1216is controlled by a memory controller.

The processor platform1200of the illustrated example also includes an interface circuit1220. The interface circuit1220may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices1222are connected to the interface circuit1220. The input device(s)1222permit(s) a user to enter data and/or commands into the processor1212. The input device(s) can be implemented by, for example, an audio sensor, a microphone, a camera (still or video), a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, isopoint and/or a voice recognition system.

The processor platform1200of the illustrated example also includes one or more mass storage devices1228for storing software and/or data. Examples of such mass storage devices1228include floppy disk drives, hard drive disks, compact disk drives, Blu-ray disk drives, RAID systems, and digital versatile disk (DVD) drives.

The coded instructions1232ofFIGS. 10-11may be stored in the mass storage device1228, in the volatile memory1214, in the non-volatile memory1216, and/or on a removable tangible computer readable storage medium such as a CD or DVD.

From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that yield an example 3D-printed structure100having an example dielectric structure120(e.g., an auxetic structure, a lattice structure, etc.) functioning as an energy absorbing material and functioning to deliver, in combination with the example first conductive substrate110and the example second conductive substrate130, information relative to, for example, a locus and an intensity of an impact. These example 3D-printed structures100can be purposed as a compression sensor, a bend sensor and/or a tensile sensor. In some examples, a product (e.g., a garment, footwear, protective equipment, shock absorbing device, orthotic device, prosthetic device, shipping material, packing material, padding, etc.) can include any combination of one or more types of the example 3D-printed structures100(e.g., one or more compression sensors, one or more bend sensors and/or one or more tensile sensors).

Example 1 is a 3D-printed structure including a first conductive substrate, a second conductive substrate and a dielectric structure between the first conductive substrate and the second conductive substrate, the dielectric structure including a latticed structure having a first stiffness in a first direction and a second stiffness in a second direction different than the first direction.

Example 2 includes the 3D-printed structure of example 1, wherein the latticed structure includes a plurality of first unit cells having a first structure.

Example 3 includes the 3D-printed structure as defined in any of Examples 1-2, wherein the latticed structure includes a plurality of second unit cells having a second structure different than the first structure.

Example 4 includes the 3D-printed structure as defined in any of Examples 1-3, wherein at least one of the first structure or the second structure is an auxetic structure having a negative Poisson ratio.

Example 5 includes the 3D-printed structure as defined in any of Examples 1-4, wherein the first structure and the second structure are auxetic structures, each having a negative Poisson ratio.

Example 6 includes the 3D-printed structure as defined in any of Examples 1-5, wherein at least one of the first conductive substrate, the second conductive substrate or the dielectric structure include an infill density between approximately 10%-80%.

Example 7 includes the 3D-printed structure as defined in any of Examples 1-6, wherein the first structure and the second structure each include a lower portion, a middle portion and an upper portion, the first and second structures defining respective hourglass shapes with lateral dimensions of the middle portion being smaller than lateral dimensions of the lower portion and the upper portion.

Example 8 includes the 3D-printed structure as defined in any of Examples 1-7, wherein the first structure includes a base structure, a top structure, and a plurality of legs extending between the base structure and the top structure, the plurality of legs extending inwardly by a first bend angle from a vertical toward a middle portion between the base structure and the top structure.

Example 9 includes the 3D-printed structure as defined in any of Examples 1-8, wherein the second structure includes a base structure, a top structure, and a plurality of legs extending between the base structure and the top structure, the plurality of legs extending inwardly by a second bend angle from a vertical toward a middle portion between the base structure and the top structure.

Example 10 includes the 3D-printed structure as defined in any of Examples 1-9, wherein the first bend angle is between approximately 10°-35° and wherein the second bend angle is between approximately 10°-35°, with the second bend angle being different than the first bend angle.

Example 11 includes the 3D-printed structure as defined in any of Examples 1-10, wherein a thickness of the dielectric structure is between approximately 0.1 mm-1.5 mm.

Example 12 includes the 3D-printed structure as defined in any of Examples 1-11, wherein a layer height to build at least one of the first conductive substrate, the second conductive substrate, or the dielectric structure is between approximately 0.06 mm-0.10 mm.

Example 13 includes the 3D-printed structure as defined in any of Examples 1-12, wherein at least one of the first conductive substrate or the second conductive substrate includes carbon nanotube filaments, graphene, graphide, nano metallization or silver nano wire.

Example 14 includes the 3D-printed structure as defined in any of Examples 1-13, wherein the dielectric structure includes an elastomeric polyurethane (EPU), a thermoplastic polyurethane (TPU), and/or a thermoplastic elastomer (TPE).

Example 15 includes the 3D-printed structure as defined in any of Examples 1-14, further including a first electrical connector built in the first conductive substrate and a second electrical connector built in the second conductive substrate.

Example 16 includes the 3D-printed structure as defined in any of Examples 1-15, wherein the first direction is normal to at least one of the first conductive substrate or the second conductive substrate.

Example 17 includes the 3D-printed structure as defined in any of Examples 1-16, wherein the first conductive substrate has a first infill density and the second conductive substrate has a second infill density different than the first infill density.

Example 18 is a sensor circuit including a sensor having a first conductive substrate having a first electrical connector, a second conductive substrate having a second electrical connector, and a dielectric structure between the first conductive substrate and the second conductive substrate, the dielectric structure including a latticed structure having a first stiffness in a first direction and a second stiffness in a second direction different than the first direction, and a processor, operatively connected to the sensor via the first electrical connector and the second electrical connector, to determine for a first strain of the dielectric structure along the first direction, at least one of a location of the first strain, a magnitude of the first strain, a first strain rate, or a first strain rate acceleration.

Example 19 includes the sensor circuit as defined in Example 18, wherein the sensor includes at least one of a compression sensor, a flex sensor, or a stretch-strain sensor.

Example 20 includes the sensor circuit as defined in any of Examples 18-19, wherein at least one of the first conductive substrate, the second conductive substrate or the dielectric structure include an infill density between approximately 10%-80%.

Example 21 includes the sensor circuit as defined in any of Examples 18-20, wherein at least one of the first conductive substrate, the second conductive substrate or the dielectric structure include an infill density between approximately 10%-80%.

Example 22 includes the sensor circuit as defined in any of Examples 18-21, wherein the latticed structure includes a plurality of second unit cells having a second structure different than the first structure.

Example 23 includes the sensor circuit as defined in any of Examples 18-22, wherein at least one of the first structure or the second structure is an auxetic structure having a negative Poisson ratio.

Example 24 includes the sensor circuit as defined in any of Examples 18-23, wherein the negative Poisson ratio is between approximately 0.0 to approximately 0.50.

Example 25 includes the sensor circuit as defined in any of Examples 18-24, wherein the first structure and the second structure include a respective lower portion, a respective middle portion and a respective upper portion to define an hourglass shape with lateral dimensions of the respective middle portion being smaller than lateral dimensions of the respective lower portion and the respective upper portion.

Example 26 includes the sensor circuit as defined in any of Examples 18-25, wherein the first structure includes a base structure, a top structure, and a plurality of legs extending between the base structure and the top structure, the plurality of legs extending inwardly by a first bend angle from a vertical toward a middle portion between the base structure and the top structure.

Example 27 includes the sensor circuit as defined in any of Examples 18-26, wherein the second structure includes a base structure, a top structure, and a plurality of legs extending between the base structure and the top structure, the plurality of legs extending inwardly by a second bend angle from a vertical toward a middle portion between the base structure and the top structure.

Example 28 includes the sensor circuit as defined in any of Examples 18-27, wherein the first bend angle is between approximately 10°-35° and wherein the second bend angle is between approximately 10°-35°, with the second bend angle being different than the first bend angle.

Example 29 includes the sensor circuit as defined in any of Examples 18-28, wherein a thickness of the dielectric structure is between approximately 0.1 mm-1.5 mm.

Example 30 includes the sensor circuit as defined in any of Examples 18-29, wherein a layer height to build at least one of the first conductive substrate, the second conductive substrate, or the dielectric structure is between approximately 0.06 mm-0.10 mm.

Example 31 includes the sensor circuit as defined in any of Examples 18-30, wherein at least one of the first conductive substrate or the second conductive substrate includes carbon nanotube (CNT) filaments including approximately 10% CNT, graphene, graphide, nano metallization or silver nano wire.

Example 32 includes the sensor circuit as defined in any of Examples 18-31, wherein the dielectric structure includes an elastomeric polyurethane (EPU), a thermoplastic polyurethane (TPU), and/or a thermoplastic elastomer (TPE).

Example 33 includes the sensor circuit as defined in any of Examples 18-32, wherein, for a second strain of the dielectric structure along the second direction, the processor is to determine at least one of a location of the second strain, a magnitude of the second strain, a second strain rate, or a second strain rate acceleration.

Example 34 includes the sensor circuit as defined in any of Examples 18-33, wherein the first conductive substrate has a first infill density and the second conductive substrate has a second infill density different than the first infill density.

Example 35 is a wearable device including a securement means to secure the wearable device to a wearer and a sensor means to sense forces applied to the wearable device, the sensor means including a first conductive substrate having a first electrical connector, a second conductive substrate having a second electrical connector, and a dielectric structure between the first conductive substrate and the second conductive substrate, the dielectric structure including a latticed structure having a first stiffness in a first direction and a second stiffness in a second direction different than the first direction, the sensor means being configured to output at least one of a first strain of the dielectric structure along the first direction, a location of the first strain, a magnitude of the first strain, a first strain rate, or a first strain rate acceleration.

Example 36 includes the wearable device as defined in Example 35, further including a processor, operatively connected to the sensor means, via the first electrical connector and the second electrical connector, wherein the wearable device includes an orthotic device, a brace, footwear, sports equipment, or a helmet.

Example 37 is a method of building a sensor with a 3D printer including building a first conductive substrate, building a dielectric structure including a latticed structure on the first conductive substrate, and building a second conductive substrate on the dielectric structure.

Example 38 includes the method of building the sensor as defined in Example 37, wherein the latticed structure includes a plurality of first unit cells having a first structure.

Example 39 includes the method of building the sensor as defined in any of Examples 37-38, wherein the first structure includes a first lower portion, a first middle portion and a first upper portion, defining a first hourglass shape with lateral dimensions of the first middle portion smaller than lateral dimensions of the first lower portion and the first upper portion.

Example 40 includes the method of building the sensor as defined in any of Examples 37-39, wherein the first structure includes a first base structure, a first top structure, and a plurality of first legs extending between the first base structure and the first top structure, the plurality of first legs extending inwardly by a first bend angle from a vertical toward a first middle portion between the first base structure and the first top structure.

Example 41 includes the method of building the sensor as defined in any of Examples 37-40, wherein the latticed structure includes a plurality of second unit cells having a second structure different than the first structure.

Example 42 includes the method of building the sensor as defined in any of Examples 37-41, wherein the second structure includes a second lower portion, a second middle portion and a second upper portion, defining a second hourglass shape with lateral dimensions of the second middle portion smaller than lateral dimensions of the second lower portion and the second upper portion.

Example 43 includes the method of building the sensor as defined in any of Examples 37-42, wherein the second structure includes a second base structure, a second top structure, and a plurality of second legs extending between the second base structure and the second top structure, the plurality of second legs extending inwardly by a second bend angle from a vertical toward a second middle portion between the second base structure and the second top structure.

Example 44 includes the method of building the sensor as defined in any of Examples 37-43, wherein the first bend angle is between approximately 10°-35° and wherein the second bend angle is between approximately 10°-35°, with the second bend angle being different than the first bend angle.

Example 45 includes the method of building the sensor as defined in any of Examples 37-44, wherein at least one of the first structure or the second structure is an auxetic structure having a negative Poisson ratio.

Example 46 includes the method of building the sensor as defined in any of Examples 37-45, wherein the negative Poisson ratio is between approximately 0.0 to approximately 0.50.

Example 47 includes the method of building the sensor as defined in any of Examples 37-46, wherein the building of the dielectric structure includes building the dielectric structure to a thickness between approximately 0.1 mm-1.5 mm.

Example 48 includes the method of building the sensor as defined in any of Examples 37-47, wherein the building of at least one of the first conductive substrate, the second conductive substrate, or the dielectric structure includes building a plurality of layers having a height between approximately 0.06 mm-0.10 mm.

Example 49 includes the method of building the sensor as defined in any of Examples 37-48, further including building a first electrical connector in the first conductive substrate and building a second electrical connector in the second conductive substrate.

Example 50 includes the method of building the sensor as defined in any of Examples 37-49, further including using a nozzle having a diameter of between approximately 0.8 mm-1.0 mm to deposit one or more layers of at least one of the first conductive substrate, the dielectric structure or the second conductive substrate.

Example 51 includes the method of building the sensor as defined in any of Examples 37-50, wherein at least one of the first conductive substrate, the second conductive substrate or the dielectric structure include an infill density between approximately 10%-80%.

Example 52 is a 3D-printed structure including a first conductive means, a second conductive means and a dielectric means between the first conductive means and the second conductive means, the dielectric means including a latticed structure having a plurality of auxetic cells.

Example 53 includes the 3D-printed structure as defined in Example 52, wherein the latticed structure includes a plurality of first auxetic cells having a first structure and a plurality of second auxetic cells having a second structure different than the first structure.

Example 54 includes the method of building the sensor as defined in any of Examples 52-53, wherein the dielectric means has a first stiffness in a first direction and has a second stiffness in a second direction different than the first direction, and wherein at least one of the first conductive means, the second conductive means or the dielectric means includes an infill density between approximately 10%-80%.

Example 55 is a non-transitory machine readable medium comprising executable instructions that, when executed, cause at least one processor to at least build a first conductive substrate, build a dielectric structure including a latticed structure having a plurality of auxetic cells on the first conductive substrate and build a second conductive substrate on the dielectric structure.

Example 56 includes the non-transitory machine readable medium as defined in Example 55, further including executable instructions that, when executed, cause the at least one processor to build at least one of the first conductive substrate, the second conductive substrate or the dielectric structure with an infill density between approximately 10%-80%.