Multi-modal multi-direction high-resolution tactile haptics and sensing device using piezoelectric multi-material metamaterial

Abstract

A sensor including one or more piezoelectric cells is disclosed. Each piezoelectric cell of the one or more piezoelectric cells may include a top member, a plurality of piezo electrodes disposed beneath the top member, a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes, a column including one or more vertical struts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes, and wherein the sensor includes a circuit platform electrically connected to the plurality of piezo electrodes of each of the one or more piezoelectric cells.

Description

Attorney Docket No: 00495-0025 (B25-007-PCT)MULTI-MODAL MULTI-DIRECTION HIGH-RESOLUTION TACTILE HAPTICS AND SENSING DEVICE USING PIEZOELECTRIC MULTI-MATERIAL METAMATERIALREFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 687,145, filed August 26, 2024. the entire contents of which are hereby incorporated by reference.FIELD

[0002] The present invention generally relates to the field of haptics and sensing technologies.BACKGROUND OF THE INVENTION

[0003] Tactile haptic technology uses tactile sensations to create a sense of touch for users. This can be done through vibrations, motion, or other forces that are activated by touching actuators. Tactile sensing technology' uses sensing instruments to record tactile input by a user.

[0004] Tactile haptic and sensing technology' is essential to augmented reality7(“AR”), virtual reality7(“VR”), and robotics systems. These systems use tactile haptic and sensing technology to provide feedback to users as well as receive user input. Tactile information ranges in complexity from simple normal stress such as pushing a button to the complex bumpiness of brushing a piece of sandpaper. The more complex the tactile stimulus, generally the more complex the haptic technology7.

[0005] The complexity7in haptic technology arises in part due to the degrees of mechanical freedom (“DoF”) that the haptic devices can operate in. Commonly discussed DoF are the normal force, lateral forces, rotation and torque, and vibration. The normal force operates perpendicular to the surface, allowing for sensations of pressure. Lateral forces, or shear forces, allow7for the simulation of sliding or dragging sensations across the surface. Rotation allow s for a twisting sensation. Vibration can enhance the sensation of textures or impacts. In addition to the DOF, signal and input resolution are both important to convey and receive tactile information. Resolution refers to the fineness or precision with which the system can detect and respond to input variations in each degree of freedom. Human fingers in particular are responsive to very small changes in pressure.

[0006] However, conventional haptic technologies are limited, tending to have either one direction of feedback (normal stress), or very7coarse resolution. These limitations significantly restrict the ability of haptic devices to simulate realistic touch sensation, especially at more14897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) sensitive skin areas like the fingertips. Where conventional haptic technology has multiple DoF, such devices tend to be large. Their size prevents them from receiving and providing high resolution feedback. This obviates their use in highly sensitive areas like the fingertips.

[0007] Additionally, most conventional haptic technologies use digital control signals, which further hinder simulation of a realistic touch sensation. Digital control signals operate in a discrete on / off manner. This means that a haptic device employing digital control is limited to on / off modes, which limits the amount of touch sense recreation. These issues can be overcome by using more complex digital signals to encode different levels of haptic feedback besides the on / off levels. But this requires the use of decoders, which add undesirable bulk to the haptic devices.

[0008] Further, conventional haptic sensor technologies cannot decouple shear and normal forces. This lack of decoupling presents issues in differentiating between detected shear and normal forces.

[0009] Finally, most conventional haptic technologies also do not serve as touch sensors. To create realistic haptic experiences, haptic technologies require touch sensation data, obtained from touch sensors. As these sensors are conventionally separate from the haptic technology, this sensor will be an additional piece of hardware. Furthermore, disparities between the sensor operation and the haptic technology might result in disparities between actual touch sensations and their recreation in haptic technologies.

[0010] What is needed is a haptic technology7that possess multiple DoF, has high resolution, can differentiate between detected shear and normal forces, and / or can also serve as a touch sensor.BRIEF SUMMARY OF THE INVENTION

[0011] In view of the above, it is an object of the present invention to provide a technological solution to address the long felt need and technological challenges faced in the haptic sensor technology field by providing a multi-modal multi-direction high-resolution tactile sensing device using piezoelectric multi-material metamaterial.

[0012] In exemplary embodiments a piezoelectric cell includes: (a) a top member; (b) a plurality of piezo electrodes disposed beneath the top member; (c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; (d) a column including one or more vertical struts, wherein the one or more24897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes.

[0013] In exemplary embodiments, a piezoelectric cell including: (a) a top member; (b) a plurality of piezo electrodes disposed beneath the top member; (c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; (d) a column including one or more vertical struts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes.

[0014] In embodiments, the piezoelectric cell is used to sense a normal deformation and a plurality of shear deformations.

[0015] In embodiments, the piezoelectric cell decouples the normal deformation and the plurality of shear deformations.

[0016] In embodiments, the stiffness ratio between the plurality of lateral members and the column is sufficient to decouple a normal deformation from plurality of shear force deformations.

[0017] In embodiments, when two or more of a normal deformation and a plurality of shear deformations is applied to the piezoelectric cell, the piezoelectric cell outputs a plurality of distinct voltages, wherein each distinct voltage of the plurality of distinct voltages corresponds respectively to one of the normal deformation and the plurality of shear deformations.

[0018] In embodiments, the column is disposed within the plurality of lateral members.

[0019] In embodiments, the column includes four vertical struts.

[0020] In embodiments, the column further includes a plate disposed in between the one or more vertical struts and the top member and / or a plate disposed in between the one or more vertical struts and the respective piezo electrode of the plurality of piezo electrodes.

[0021] In embodiments, the top member, the plurality of lateral members, and the column include the same material.

[0022] In embodiments, the same material includes TMPTA (Millipore Sigma. USA), 1-3 wt.% photoinitiator Irg819, 15 vol% PDD, and a neutral TMPTA resin (without PDD).

[0023] In embodiments, a portion of the top member, the plurality of lateral members, and / or the column is plated with a conductive metal.34897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0024] In embodiments, the conductive metal is plated copper or nickel.

[0025] In embodiments, the plurality of piezo electrodes includes a polymer matrix and dispersed piezoelectric particles.

[0026] In embodiments, the plurality of piezo electrodes include about 40 vol% propylene carbonate and about 60 vol% PEGDA with 1-3 wt.% photoinitiator Irg819.

[0027] In embodiments, the piezoelectric cell is monolithically printed.

[0028] In embodiments, the piezoelectric cell includes four lateral members.

[0029] In embodiments, the piezoelectric cell is part of an array of piezoelectric cells.

[0030] In embodiments, a sensor including one or more piezoelectric cells, wherein each piezoelectric cell includes: (a) a top member; (b) a plurality of piezo electrodes disposed beneath the top member; (c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; (d) a column including one or more vertical stmts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; and wherein the sensor includes a circuit platform electrically connected to the plurality of piezo electrodes of each of the one or more piezoelectric cells.

[0031] In embodiments, the sensor is used to sense a normal deformation and a plurality of shear deformations.

[0032] In embodiments, the sensor decouples the normal deformation and the plurality of shear deformations.

[0033] In embodiments, for each piezoelectric cell, the stiffness ratio between the plurality of lateral members and the column is sufficient to decouple a normal deformation from plurality of shear deformations.

[0034] In embodiments, for each piezoelectric cell, when two or more of a normal deformation and a plurality of shear deformations is applied to the piezoelectric cell, the piezoelectric cell outputs a plurality of distinct voltages, wherein each distinct voltage of the plurality of distinct voltages corresponds respectively to one of the normal deformation and the plurality of shear deformations.

[0035] In embodiments, for each piezoelectric cell, the column is disposed within the plurality of lateral members.44897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0036] In embodiments, for each piezoelectric cell, the column includes four vertical struts.

[0037] In embodiments, for each piezoelectric cell, the column further includes a plate disposed in between the one or more vertical struts and the top member and / or a plate disposed in between the one or more vertical struts and the respective piezo electrode of the plurality of piezo electrodes.

[0038] In embodiments, for each piezoelectric cell, the top member, the plurality of lateral members, and the column include the same material.

[0039] In embodiments, the same material includes about TMPTA (Millipore Sigma, USA), 1-3 wt.% photoinitiator Irg819, 15 vol% PDD, and a neutral TMPTA resin (without PDD).

[0040] In embodiments, for each piezoelectric cell, a portion of the top member, the plurality of lateral members, and / or the column is plated with conductive metal.

[0041] In embodiments, for each piezoelectric cell, the conductive metal is plated copper or nickel.

[0042] In embodiments, for each piezoelectric cell, the plurality of piezo electrodes includes a polymer matrix and dispersed piezoelectric particles.

[0043] In embodiments, the plurality of piezo electrodes include about 40 vol% propylene carbonate and about 60 vol% PEGDA with 1-3 wt.% photoinitiator Irg819.

[0044] In embodiments, each piezoelectric cell is monolithically printed.

[0045] In embodiments, each piezoelectric cell includes four lateral members.

[0046] In further view of the above, it is an object of the present invention to provide a technological solution to address the long felt need and technological challenges faced in the haptic technology field by providing a multi-modal multi-direction multi-magnitude high- resolution tactile haptics and sensing device using piezoelectric multi -material metamaterial.

[0047] In exemplary embodiments, a piezoelectric cell includes: a) a top face; b) a bottom face; c) a plurality of side faces, connecting the top face and the bottom face; wherein the top face, the bottom face, and each side face of the plurality of side faces includes a material stack layer including: i) a piezoelectric material layer and a structural material layer, wherein: (1) the piezoelectric material layer includes a first portion of the piezoelectric material layer and a second portion of the piezoelectric material layer separated by a gap in the piezoelectric54897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) material layer; (2) the first portion of the piezoelectric material layer and the second portion of the piezoelectric material layer are polarized to enable deformation of the piezoelectric cell; ii) a first electrode layer disposed between the piezoelectric material layer and the non-conducting material layer; and iii) a second electrode layer disposed over the piezoelectric material layer, wherein the second electrode layer includes a first portion of the second electrode layer and a second portion of the second electrode layer separated by a gap in the second electrode layer; and d) a plurality of wires connecting the first electrode layer and the second electrode layer to a controller.

[0048] In embodiments, the piezoelectric cell is capable of deformation normal to at least one pair of opposing faces selected from the group consisting of the top face, the bottom face, and the plurality the side faces.

[0049] In embodiments, the piezoelectric cell is capable of shear deformation along at least one pair of opposing faces selected from the group consisting of the top face, the bottom face, and the plurality the side faces.

[0050] In embodiments, the piezoelectric cell is capable of normal deformation along a first pair of opposing faces and shear deformation along a second pair of opposing faces, each selected from the group consisting of the top face, the bottom face, or the side faces.

[0051] In embodiments, the piezoelectric cell is capable of vibration.

[0052] In embodiments, the controller is capable of sending different waveforms of voltage signals.

[0053] In embodiments, the faces of the piezoelectric cell form a rectangular prism.

[0054] In embodiments, the piezoelectric material layer includes PZT-5H.

[0055] In embodiments, the structural material layer includes a structural ceramic.

[0056] In embodiments, the structural ceramic includes silicon oxy carbide.

[0057] In embodiments, the controller is an analog controller.

[0058] In embodiments, the analog controller includes a power distribution unit, signal amplifier, and power inverter.

[0059] In embodiments, the piezoelectric cell is part of an array of piezoelectric cells.

[0060] In exemplary embodiments, an array includes a plurality of units of piezoelectric cells, wherein each unit includes a top piezoelectric cell and a bottom piezoelectric cell,64897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) wherein the bottom face of the top piezoelectric cell is disposed along the top face of the bottom piezoelectric cell, and wherein the plurality of units of piezoelectric cells are disposed adjacent to each other along their side faces.

[0061] In exemplary embodiments, a haptic device includes one or more piezoelectric cells, wherein each piezoelectric cell includes: a) a top face; b) a bottom face; c) a plurality of side faces, connecting the top face and the bottom face; d) where each face includes a material stack layer including: i) a piezoelectric material layer and a structural material layer, wherein the piezoelectric material layer includes a first portion of the piezoelectric material layer and a second portion of the piezoelectric material layer separated by a gap in the piezoelectric material layer; ii) a first electrode layer between the piezoelectric material layer and the nonconducting material layer; and iii) a second electrode layer disposed over the piezoelectric material layer, wherein the second electrode layer includes a first portion of the second electrode layer and a second portion of the second electrode layer separated by a gap in the second electrode layer; and e) a plurality of wires connecting the first electrode layer and the second electrode layer to a controller.

[0062] In embodiments, the piezoelectric cell is capable of deformation normal to at least one pair of opposing faces selected from the group consisting of the top face, the bottom face, and the plurality the side faces.

[0063] In embodiments, the piezoelectric cell is capable of shear deformation along at least one pair of opposing faces selected from the group consisting of the top face, the bottom face, and the plurality the side faces.

[0064] In embodiments, the piezoelectric cell is capable of normal deformation along a first pair of opposing faces and shear deformation along a second pair of opposing faces, each selected from the group consisting of the top face, the bottom face, or the side faces.

[0065] In embodiments, the piezoelectric cell is capable of vibration.

[0066] In embodiments, the controller is capable of sending different waveforms of voltage signals.

[0067] In embodiments, the faces of the piezoelectric cell form a rectangular prism.

[0068] In embodiments, the piezoelectric material includes PZT-5H.

[0069] In embodiments, the structural material layer includes a structural ceramic.

[0070] In embodiments, the structural ceramic includes silicon oxy carbide.74897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0071] In embodiments, each piezoelectric cell is used as an actuator.

[0072] In embodiments the actuator can actuate in multiple planes of movement.

[0073] In embodiments, each piezoelectric cell is used as a sensor.

[0074] In embodiments, the sensor can sense movement in multiple planes of movement.

[0075] In embodiments, each piezoelectric cell is used as an actuator and a sensor.

[0076] In embodiments, the controller is an analog controller.

[0077] In embodiments, the analog controller includes a power distribution unit, signal amplifier, and power inverter.

[0078] In embodiments, a plurality of piezoelectric cells are arranged in an array. In embodiments, a haptic device, wherein the array includes a plurality of units of piezoelectric cells, wherein each unit includes a top piezoelectric cell and a bottom piezoelectric cell, wherein the bottom face of the top piezoelectric cell is disposed along the top face of the bottom piezoelectric cell, and wherein the plurality of units of piezoelectric cells are disposed adjacent to each other along their side faces.

[0079] In embodiments, the haptic device is attached to a fingertip.

[0080] Other features and advantages of the present invention will become readily apparent from the following detailed description and the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The above and related objects, features and advantages of the present invention will be more fully understood by reference to the following, detailed description of the preferred, albeit illustrative, embodiment of the present invention when taken in conjunction with the accompanying figures, wherein:

[0082] FIG. 1 is a diagram of a haptic device for use on a fingertip that incorporates an array of piezoelectric cells in accordance with exemplary embodiments of the present invention;

[0083] FIG. 2 is a diagram of a fingertip haptic device being used as a sensor to collect haptic data in accordance with exemplary embodiments of the present invention;

[0084] FIG. 3 is a diagram of a fingertip haptic device being used as an actuator in accordance with exemplary' embodiments of the present invention;84897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0085] FIG. 4 is a diagram of a fingertip haptic device in accordance with exemplary embodiments of the present invention;

[0086] FIG. 5 is a system wiring diagram in accordance with exemplary embodiments of the present invention;

[0087] FIG. 6 is a diagram showing the composition of a piezoelectric cell in accordance with exemplary embodiments of the present invention;

[0088] FIG. 7A is a two-dimensional diagram providing structural details of a piezoelectric cell in accordance with exemplary embodiments of the present invention;

[0089] FIG. 7B is a is a three-dimensional diagram providing structural details of a piezoelectric cell in accordance with exemplary embodiments of the present invention;

[0090] FIG. 8A is a two-dimensional diagram of a piezoelectric cell showing a configuration of piezo electrode polarization orientations in accordance with exemplary embodiments of the present invention;

[0091] FIG. 8B is a three-dimensional diagram of a piezoelectric cell showing a configuration of piezo electrode polarization orientations in accordance with exemplary embodiments of the present invention;

[0092] FIG. 9 is a diagram of a unit of piezoelectric cells undergoing normal and shear deformation in accordance with exemplary embodiments of the present invention;

[0093] FIG. 10A is a two-dimensional wiring schematic configured to actuate and sense changes in normal deformation in accordance with exemplary embodiments of the present invention;

[0094] FIG. 10B is a two-dimensional diagram depicting normal actuation in accordance with exemplary' embodiments of the present invention.

[0095] FIG. 11 A is a three-dimensional wiring schematic configured to actuate and sense changes in normal deformation in accordance with exemplary' embodiments of the present invention;

[0096] FIG. 1 IB is a three-dimensional diagram depicting normal actuation in accordance with exemplary’ embodiments of the present invention;94897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0097] FIG. 12A is two-dimensional wiring schematic configured to actuate and sense changes in shear deformation in accordance with exemplary embodiments of the present invention;

[0098] FIG. 12B is a two-dimensional diagram depicting shear actuation in accordance with exemplar^' embodiments of the present invention;

[0099] FIG. 13A is a three-dimensional wiring schematic configured to actuate and sense changes in shear deformation in accordance with exemplar}' embodiments of the present invention;

[0100] FIG. 13B is a three-dimensional diagram depicting shear actuation in accordance with exemplar}' embodiments of the present invention;

[0101] FIG. 14 is a three-dimensional diagram of an array of an array of piezo electric cells in accordance with exemplary embodiments of the present invention;

[0102] FIGs. 15A-15B are graphs depicting normal and shear force decoupling of a piezoelectric cell in accordance with exemplary embodiments of the present invention;

[0103] FIGs. 16A-16B are three-dimensional diagrams of the movements of various members of a piezoelectric cell in response to normal and shear force in accordance with exemplary embodiments of the present invention; and

[0104] FIGs. 17A-B are graphs depicting the linearity of voltage responses and capacitive response to force applied to piezoelectric cells in accordance with embodiments of the present invention.DETAILED DESCRIPTION OF THE INVENTIONMULTI-MODAL MULTI-DIRECTION HIGH-RESOLUTION TACTILE HAPTICS AND SENSING DEVICE USING PIEZOELECTRIC MULTI-MATERIAL METAMATERIAL

[0105] The present invention generally relates to haptic sensors and actuators.

[0106] This invention achieves high resolution three DoF tactile haptic and sensing technology, allowing for the complex tactile stimulation and data collection required by the AR, VR, and robotics industries. This invention's three DoF are enabled by a piezoelectric multi -material metamaterial design, as shown in FIGs. 3, 9. 11 and 13 Piezoelectric structures, coupled with passive structural materials, can actuate the metamaterial with customizable deformations in the normal and two lateral shear directions. These effects are achieved by104897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) altering electric potentials across the piezoelectric structures via an analog controller. In addition to actuating, the metamaterials can sense changes in pressure and shear due to deformations in the piezo electrodes, which generate changes in voltage. Thus, this invention serves as both a haptic feedback and touch sensing technology.

[0107] Conventional haptic devices either actuate or sense haptic feedback. That means that if a user wants to collect haptic data and then employ it in a haptic device, they need two pieces of equipment. The claimed invention only needs one. Furthermore, differences between conventional sensing and actuating devices may lead to an inaccurate haptic experience. On the other hand, the claimed invention which operates as both a sensor and an actuator, can provide strongly correlated haptic sensing and actuation.

[0108] FIG. 1 is a diagram of a haptic device for use on a fingertip that incorporates an array of piezoelectric cells in accordance with exemplary embodiments of the present invention.

[0109] As shown in FIG. 1, a haptic device (e.g., fingertip haptic device 100) can be attached to a user’s finger (e.g., finger 102). In embodiments, the haptic device may be embedded with an array of piezoelectric cells (e.g., array 116). As shown in FIG. 1. in embodiments, the array of piezoelectric cells may be composed of sub-arrays (e.g., array 104, comprised of four piezoelectric cells).

[0110] In embodiments, the array of piezoelectric cells (e.g., array 104 or array 116) includes a plurality of units of piezoelectric cells (e.g., unit of two stacked piezoelectric cells 114 as part of 104). In embodiments, each unit includes a top piezoelectric cell (e.g., 116) and a bottom piezoelectric cell (e.g., 118). In embodiments, the bottom face of the top piezoelectric cell is disposed along the top face of the bottom piezoelectric cell. In embodiments, the units of piezoelectric cells can comprise a plurality of side faces. In embodiments, the units are disposed adjacent to each other along their respective side faces (e.g., array of four units of two stacked piezoelectric cells 104).

[0111] The array comprised of units of two stacked piezoelectric cells (e.g., unit of two stacked piezoelectric cells 114) has the advantages of structural stability, while still maintaining the high resolution needed for sensitive skin types like the fingertips. Fingertips can sense very small changes in haptic sensations. As such, a common goal for fingertip haptic devices is to be able to construct devices with resolution of 2 millimeters - i.e. the distance between adjacent actuators is 2 mm. Computational testing of the array 104 comprised of units of two stacked114897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) piezoelectric cells, has demonstrated that this array theoretically can be operated at the 2mm scale. This stands in stark contrast to conventional haptic devices.

[0112] Though some haptic devices achieve this spatial resolution, they can only actuate in one dimension. As discussed below, and throughout this application, embodiments of the present invention are configured to actuate in three dimensions, normal, shear x, shear y, and can vibrate, and employ different waveforms of feedback to simulate different textures.

[0113] In embodiments, the array of piezoelectric cells can be arranged in arrays of various geometries, such as non-stacked piezoelectric cells, and stacks of three piezoelectric cells, to give a couple of examples.

[0114] FIG. 2 is a diagram of a fingertip haptic device being used as a sensor to collect haptic data in accordance with exemplary embodiments of the present invention.

[0115] As shown in FIG. 2, a haptic device (e.g., fingertip haptic device 102) may be used as a sensor worn on the fingertip. As the array of embedded piezoelectric cells (e.g., 116) deforms, it can output an array of different voltage readouts (e.g., voltage readouts 202). This occurs because the piezoelectric cells generate an electric charge when deformed, resulting in a measurable change in voltage. In embodiments, these changes in voltage can be recorded in the form of a tactile map (e g., tactile map 204) on computer readable memory (e.g.. a hard drive or memory chip, to give a few examples) In embodiments, the tactile map is stored on a remote server. In embodiments, the tactile map includes values corresponding to the normal force deformations of the array of piezoelectric cells (e.g., 204).

[0116] In embodiments, the tactile map corresponds to shear force measurements. In embodiments, the tactile map corresponds to shear force measurements and normal force measurements.

[0117] FIG. 3 is a diagram of a fingertip haptic device being used as an actuator in accordance with exemplary embodiments of the present invention.

[0118] As shown in FIG. 3, a haptic device may be used as an actuator worn on the fingertip (e.g.. fingertip haptic device 102). In embodiments, information (e.g.. such as that contained in a tactile map, such as tactile map 300) may be sent to an array of piezoelectric cells (e.g., array 116) functioning as actuators. In embodiments, the array of piezoelectric cells receives an applied voltage (e.g., 302) corresponding to the information contained in the tactile map. In embodiments, the tactile map may contain tactile information in more than one dimension, such that the applied voltage is configured to cause the array of piezoelectric cells to actuate in124897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) more than one dimension (e.g., piezoelectric cell stack showing different dimensions of movement 304 and array 116 showing different dimensions of movement).

[0119] In embodiments, the tactile map corresponds to information in one dimension. In embodiments, the array may actuate in one dimension.

[0120] FIG. 4 is a diagram of a fingertip haptic device being in accordance with exemplary embodiments of the present invention.

[0121] As shown in FIG. 4, in embodiments, a fingertip haptic device includes an array of piezoelectric cells (e.g., array 408), a power supply (e.g., power supply 402), and a controller (e.g., controller 406). In embodiments, the power supply is located on the same finger as the fingertip haptic device (e.g., power supply 412). In embodiments, the power supply is embedded into the fingertip haptic device using an embedding material. In embodiments, the embedding material (e.g., embedding material 410) is an organic polymer, such as polydimethylsiloxane. In embodiments, the power supply is remote from the fingertip haptic device. In embodiments, the power supply can send voltage supply (e.g., voltage supply 400) to the array of piezoelectric cells (e.g., array 408) through a controller (e.g., controller 406).

[0122] In embodiments, the controller is an analog controller such as a complementary metal oxide semiconductor controller (CMOS), a bipolar CMOS, or a digital signal processor with an analog front end to name a few examples.

[0123] The analog controller allows for high resolution tactile sense recreation and sensing. The analog control can actuate deformations from 0um~200um by applying various voltages. Using the analog controller also allows for use of different electric wave signals to create more complex textures. For example, haptic sensations mimicking the discrete granules of sandpaper could use a square wave to mimic this texture. A smoother sensation like a flowing liquid could use a sine wave. Finally, because the controller actuates and receives input from the metamaterials via changes in voltage, it can send and receive high frequency information.

[0124] FIG. 5 is a system wiring diagram in accordance with exemplary embodiments of the present invention.

[0125] As shown in FIG. 5, in embodiments, an array of piezoelectric cells (e.g., array 500) can be connected to a controller (e.g., controller 402). In embodiments, the controller may be comprised of a power distribution unit (e.g., power distribution unit 502), a, signal amplifier (e.g., signal amplifier 504), and a power inverter (e.g., power inverter 506).134897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0126] In embodiments, each stack (also referred to herein as a “unit”) of piezoelectric cells (e.g., stack 522) in the array of piezoelectric cells (e.g., array 500) is connected to the controller via a plurality of wires (e.g., wires 514, 516, 518, 520). In embodiments, the plurality of wires includes a ground wire, a wi re connecting the controller to piezo electrodes capable of actuating in and sensing deformation in the shear x direction, a wire connecting the controller to piezo electrodes capable of actuating in and sensing deformation in the shear y direction, and a wire connecting the controller to piezo electrodes capable of actuating in and sensing deformation in the normal direction.

[0127] In embodiments, the wires may be combined and / or replaced with additional wires. In embodiments, only ground, one shear, and a normal wire are used. In embodiments, more than two shear wires are used. In embodiments, only one ground and one normal wire are used. In embodiments, the wires connect to a plurality of different numbers of piezoelectric cells, such as one cell, two cells, or three cells, to name a few examples.

[0128] FIG. 6 is a diagram showing the composition of a piezoelectric cell in accordance with exemplary embodiments of the present invention.

[0129] In embodiments, a piezoelectric cell is in the shape of a rectangular prism (e.g., 600). In embodiments, the rectangular prism includes four ribs (e.g. ribs 616, 618, 622, 624). In embodiments the ribs are all located ninety degrees from one another.

[0130] In embodiments, different combinations of ribs and angles are used to form the piezoelectric cell, such as six ribs oriented in sixty7degrees from one another, four ribs oriented in an X pattern, or three ribs located one hundred and twenty degrees from one another, for example.

[0131] As shown in FIG. 6, each rib of the piezoelectric cell includes a material stack layer (e.g.. 602, 604, 606, 608). In embodiments, the material stack layer includes a structural material layer (e g. structural material 602), a piezoelectric layer (e.g., piezoelectric layer 606), and electrodes (e.g., electrodes 604 and 608). In embodiments, layers are organized from outside of the piezoelectric cell toward the inside as: 1) a structural material layer (e.g., structural material 602); 2) a first electrode disposed on the inside of the structural material (e.g., first electrode 604); 3) a piezoelectric material layer (e g., piezoelectric material layer 606); and 4) a second electrode disposed on the inside of the piezoelectric material (e.g., second electrode 608). In embodiments, the piezoelectric material layer and the electrode disposed on the inside of the piezoelectric material layer contain a gap (e.g.. gap 614).144897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0132] In embodiments, layers are organized from inside of the piezoelectric cell toward the outside as: 1) a structural material layer (e.g., structural material 602); 2) a first electrode disposed on the inside of the structural material (e.g., first electrode 604); 3) a piezoelectric material layer (e.g., piezoelectric material layer 606); and 4) a second electrode disposed on the inside of the piezoelectric material (e.g., second electrode 608). In embodiments, the piezoelectric material layer and the electrode disposed on the inside of the piezoelectric material layer contain a gap (e.g., gap 614).

[0133] In embodiments, the outer portion of each rib is a structural material (e.g., structural material 602), such as structural ceramic, or silicon oxy carbide, to give a few examples.

[0134] In embodiments, a rib contains a bump on the outside of the structural material layer(e.g., bump 620). In embodiments, this bump adds structural reinforcement. In embodiments, the bump allows for better joining of piezoelectric cells into an array.

[0135] In embodiments, each rib of the piezoelectric cell is connected to a plurality of wires (e.g., wires 610, 612) that are attached to electrodes (e.g., electrodes 604 and 608). In embodiments, the plurality of wires includes a wire providing voltage (e.g., voltage wire 610) and a wire providing ground (e.g., ground wire 612).

[0136] FIG. 7A is a two-dimensional diagram providing structural details of a piezoelectric cell (e.g.. piezoelectric cell 600), specifically two ribs (e.g., ribs 622 and 618) joined at one hundred eighty degrees from one another (also referred to herein as a “pair of diametrically aligned ribs”) in accordance with exemplary' embodiments of the present invention.

[0137] As shown in FIG. 7A, each pair of diametrically aligned ribs is composed of a plurality7of faces (e.g., the top face 702; the bottom face 710; a first side face 704; and a second side face 712). In embodiments, each face is comprised of two piezoelectric layers (e.g., top face piezo electrodes 700. first side face piezo electrodes 706. bottom face piezo electrodes 708, and second side face piezo electrodes 715) separated by gaps (e g., gaps 614). The gap allows for connecting the different electrodes.

[0138] In embodiments, the piezoelectric layers on the plurality7of faces are separate (e.g., the top face piezoelectric layers 700 are separate from side face piezoelectric layers 706). The separateness of the electrodes between faces is important as it allows the different faces to actuate and sense deformation in different ways. This is accomplished in part by taking advantage of different piezoelectric polarizations, as discussed in FIGs. 8A and 8B below.154897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0139] FIG. 7B is a is a three-dimensional diagram providing structural details of how a piezoelectric cell (e.g., piezoelectric cell 600) is constructed from four ribs orientated at ninety degrees from one another. When a piezoelectric cell is constructed from its ribs (e.g., piezoelectric cell 600), it forms a plurality of faces (e.g., the top face 726, the bottom face 720, and aplurality of side faces 716, 718, 722, and 724). In 7B, the dashed lines outline the different faces of the piezoelectric cell, with the longer dashes outline the visible faces in the front of the piezoelectric cell, and the shorter dashes outlining the not visible faces in the back of the piezoelectric cell.

[0140] The faces of the piezoelectric cell are defined by the faces of the ribs that determine the piezoelectric cell (e.g., the top face 726 is defined by the top faces of the four ribs that it contains, and a side face 718 is defined by the one side face of the rib that it contains). In embodiments, the top and bottom face are respectively comprised of the top face and bottom face of two pairs of diametrically aligned ribs of the piezoelectric cell. In embodiments, the side faces are defined by one rib of the piezoelectric cell.

[0141] In embodiments, the piezoelectric cell includes three pairs of diametrically aligned ribs so as to form a hexagonal top and bottom face and six side faces. In embodiments, the piezoelectric cell includes three ribs spaced one hundred and twenty degrees apart to form a triangular top and bottom face and three side faces.

[0142] FIG. 8A is a two-dimensional diagram of a piezoelectric cell showing a configuration of piezo electrode polarization orientations in accordance with exemplary embodiments of the present invention.

[0143] In FIG. 8A, the dashed arrows indicate the polarization of the various piezo electrodes. The differing polarizations allow' the faces of the pair of diametrically aligned ribs to sense and actuate in different directions. In embodiments, if the face of a pair of diametrically aligned ribs is comprised of tw o piezoelectric material layers with the same polarization (e.g., the top face 702 with piezo electrode polarizations 800 facing the same direction), the face of the pair of diametrically aligned ribs will be able to actuate and sense normal deformations. In embodiments, if the face of a pair of diametrically aligned ribs is comprised of two piezoelectric material layers with opposite polarizations (e.g., a side face 704 with piezo electrode polarizations 804 facing in opposite directions), then the face of the pair of diametrically aligned ribs will be able to actuate and sense shear forces. When the ribs are arranged to form a piezoelectric cell, the ability to actuate and sense forces are retained.164897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0144] FIG. 8B is a diagram of a piezoelectric cell showing a configuration of piezo electrode polarization orientations in accordance with exemplary embodiments of the present invention.

[0145] In FIG 8B. the thin dashed lines are to provide guidance to help understand the where the faces of the piezoelectric cell are located. In embodiments, the top face (e.g., top face 726) and the bottom face (e.g., bottom face 720) each include four piezoelectric material layers polarized in the same orientation, pointing into the cell. In embodiments, the side faces (e.g., side faces 716, 718, 722, and 724) each include two piezoelectric material layers polarized in opposite directions, but polarized in the same direction across the pair of diametrically aligned ribs. This configuration enables the top and bottom faces to actuate and sense normal forces, and the side faces to actuate and detect shear forces.

[0146] In embodiments, different combinations of orientations are used, such as only one of the top or bottom faces having orientations allowing it to actuate and sense the normal force, and one or more of the side faces having orientations allowing it to actuate and sense the normal force for example.

[0147] FIG. 9 is a diagram of a unit of piezoelectric cells undergoing normal and shear deformation in accordance with exemplary embodiments of the present invention.

[0148] As shown in FIG. 9, when the piezoelectric cells are organized into an array (e.g., stack arrays 114), the deformations in the normal direction (e g., array 900) and shear directions, (e.g., 902) scale from the single piezoelectric cells to the array.

[0149] FIG. 10A is a two-dimensional wiring schematic configured to actuate and sense changes in normal deformation in accordance with exemplary' embodiments of the present invention.

[0150] As shown in FIG. 10A, the piezoelectric material layers of two opposing faces of pair of diametrically aligned ribs has been connectively wired via a plurality of wires (e.g., wires 1002, 1006, 1008). In embodiments, each of the opposing faces has a corresponding ground wire (e.g., ground wires 1000, 1004). In embodiments, each of the opposing wired faces has its piezoelectric material layers orientated the same way, as indicated by the dashed arrows. As such, when a voltage is applied to this system of opposing faces via a wire (e.g., wire 1006), the piezoelectric material layers will simultaneously deform as demonstrated in 1010 and 1014 in FIG. 10B. These deformations will have the ultimate effect of actuating a force normal to the opposing faces of the diametrically aligned rib as demonstrated by 1012 in FIG. 10B.174897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0151] In embodiments, the wiring configuration depicted in FIG. 10A allows the pair of diametrically aligned ribs to sense normal deformations. In embodiments, the wiring configuration depicted in FIG. 10A allows the pair of diametrically aligned ribs to actuate and sense normal deformations.

[0152] In embodiments, only one of the opposing faces of the diametrically aligned rib has piezo electrodes with the same polarization and a current carrying wire, and ground wire, such that only that one face of the diametrically aligned rib can actuate and sense normal deformation.

[0153] FIG. 11A is a three-dimensional wiring schematic configured to actuate and sense changes in normal deformation in accordance with exemplary embodiments of the present invention.

[0154] As shown in FIG. 11 A, each of the piezoelectric material layers of two opposing faces of a piezoelectric cell (e.g., top face 726 and bottom face 720) are connectedly wired (e.g., wires 1100, 1002, 1102, 1006, and 1008). In embodiments, each of the opposing faces of the piezoelectric cell have one ground wire (e.g., ground wires 1000 and 1004). In embodiments, the opposing faces of the piezoelectric cell have their piezoelectric material layers oriented all facing inwards, like FIG. 9.

[0155] In embodiments, when a voltage is applied to the wired system, the piezoelectric material layers will deform in a curved manner demonstrated in FIG. 11B (e.g., piezoelectric material layer deformations 1112 and 1116). This has the overall effect of exerting an outward force on the pair of opposing faces (e.g., force 1114).

[0156] In embodiments, the wiring configuration depicted in FIG. 11 A allows two pairs of diametrically aligned ribs to sense normal deformations. In embodiments, the wiring configuration depicted in FIG. 11 A allows the pair of diametrically aligned ribs to actuate and sense normal deformations. In embodiments, the wiring configuration in 11 A is extended to allow actuation and sensing of normal force deformation in different numbers of and orientations of ribs such as: three diametrically aligned pairs of ribs separated by sixty degrees, two diametrically aligned ribs orientated to form an X, or three ribs separated by one hundred twenty degrees, to name a few examples.

[0157] FIG. 12A is two-dimensional wiring schematic configured to actuate and sense changes in shear deformation in accordance with exemplary embodiments of the present invention.184897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0158] As shown in FIG. 12A, the piezoelectric material layers of two opposing faces of a pair of diametrically aligned ribs are not connectedly wired like the wiring configuration depicted in FIG. 10 A. Instead, only the piezoelectric material layers on one opposing face are connectedly wired (e.g., wires 1202 and 1208, and 1204 and 1206). Each of the opposing wired faces has a corresponding ground wire (e.g., ground wires 1210 and 1212). Each of the opposing wired of wires faces has its piezoelectric material layers orientated in different directions, as indicated by the dashed arrows.

[0159] Unlike FIG. 10 A. when the pair of diametrically aligned ribs are normally deformed by receiving a single voltage, in FIG. 12A, the pair of diametrically aligned ribs are shear deformed by receiving two voltages of opposite charge. In embodiments, the two opposite voltages are supplied by current carrying wires (e.g., wires 1212 and 1216). If current carrying wire 1212 supplies a negative voltage, and current carrying wire 1216 supplies a positive voltage, then the piezoelectric cell rib will deform as depicted by 1218 in FIG. 12B. The rib's deformation results from the individual deformations of the piezoelectric material layers of the opposing sides (e.g., 1214 and 1216).

[0160] FIG. 13A is a three-dimensional wiring schematic configured to actuate and sense changes in shear deformation in accordance with exemplary' embodiments of the present invention.

[0161] As shown in FIG. 13A, each of the piezoelectric material layers of two opposing faces of a piezoelectric cell (e.g., faces 718 and 724) are not connectedly wired. They have their own voltage supply wires (e.g. wires 1108 and 1206). In embodiments, each of the opposing faces of the piezoelectric cell has their own ground wire (e.g., wires 1210 and 1208). In embodiments, each of the opposing faces of the piezoelectric cell have their piezoelectric material layers oriented in opposite directions, as demonstrated by the dashed arrows.

[0162] When a voltage is applied to the wired system, such that 1208 delivers a negative voltage and 1306 delivers a positive voltage, the piezoelectric material layers will deform in a curved manner as demonstrated in FIG. 13B (e.g., deformations 1214 and 1216). This has the overall effect of exerting a shear force on the pair of opposing faces (e.g., force 1218).FORCE DECOUPLING SENSOR

[0163] Conventional haptic sensors cannot effectively decouple shear and normal forces. This lack of decoupling presents issues in differentiating between detected shear and normal forces.194897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0164] FIG. 14 is a three-dimensional diagram of an array of piezoelectric cells in accordance with exemplary embodiments of the present invention. In embodiments, the array includes a plurality of piezoelectric cells disposed such that the plurality of lateral members are adjacent. In embodiments, the array is assembled via a pick-and-place machine

[0015] As shown in FIG. 14, in embodiments a piezoelectric cell includes a top member (e.g., member 1401), a plurality7of piezo electrodes disposed beneath the top member (e.g. electrodes 1405), a plurality of lateral members (e.g.. members 1403), each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes, and a column (e.g., column 1407). In embodiments (for example, as shown in FIG. 16), the column includes comprising one or more vertical stmts (e.g., stmts 1501). In embodiments, the one or more vertical stmts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes.

[0166] In embodiments, the plurality7of lateral members may include three members, four members, or five or more members, to give a few examples. In embodiments, each lateral member is connected to the top member and a respective piezo electrode of the plurality of piezo electrodes.

[0167] In embodiments, the plurality of piezo electrodes may include three piezo electrodes, four piezo electrodes, or five or more piezo electrodes, to give a few examples. In embodiments, the plurality of piezo electrodes each correspond to one of the lateral members and the column. In embodiments, one or more piezo electrodes may each correspond to more than one of the lateral members and the column.

[0168] FIGs. 15A-15B are graphs depicting normal and shear force decoupling of a piezoelectric cell in accordance with exemplary embodiments of the present invention.

[0169] In embodiments where the piezoelectric cell has four lateral members, the design can enable the piezo electric cell to detect three forces, for example, shear in X, shear in Y, and normal in Z, as depicted in Figure 14. In embodiments the detection of these forces is decoupled. In embodiments, decoupling is enabled by the piezo electric cell outputting a plurality of distinct voltages, each corresponding respectively to one of the shear in X, shear in Y, and normal in Z. In embodiments, decoupling is enabled by the piezo electric cell outputting a plurality of distinct changes in capacitance, each corresponding respectively to one of the shear in X, shear in Y, and normal in Z. In embodiments, decoupling is enabled by the piezo204897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) electric cell outputting a plurality of distinct voltages and distinct changes in capacitance, each corresponding respectively to one of the shear in X, shear in Y, and normal in Z.

[0170] In embodiments with more or less than four lateral members, the detection of forces is similar to that described above.

[0171] As shown in FIGs. 15A and FIGs. 15B, when a force is applied to the piezoelectric cell in the Z direction (i.e. normal force. FIG. 15B). the plurality of piezo electrodes of the piezoelectric cell output voltages that are distinct from when the same amount of force is applied to the piezoelectric cell in the Y direction (i.e. a shear force, FIG. 15 A). In embodiments, the piezoelectric cell outputs a third distinct voltage when force is applied in the X direction (i.e. a second shear force).

[0172] In embodiments, when the same force is applied in the normal and shear directions to the piezoelectric cell, the piezoelectric cell outputs voltages that differ by any value in the range of a half an order of magnitude to three orders of magnitude. In embodiments, the voltages differ by one order of magnitude. FIGs. 15A-15B show data from an embodiment wherein the voltages differ by one order of magnitude between the Z direction (i.e. normal force, FIG. 15B) and the Y direction (i.e. a shear force, FIG. 15 A).

[0173] In embodiments, when the same force is applied in the normal direction and a first shear direction and a second shear direction to the piezoelectric cell, the piezoelectric cell outputs voltages that differ by a first order of magnitude betw een the normal and first shear direction and a second order of magnitude between the normal and the second order of magnitude. In embodiments, the first and second order or magnitudes are distinctly selected from a range of a half an order of magnitude to three orders of magnitude. In embodiments, the first and second order or magnitudes and respectively one order of magnitude and two order of magnitude.

[0174] FIGs. 16A-16B are three-dimensional diagrams of the movements of various members of a piezoelectric cell in response to normal and shear force in accordance with exemplary embodiments of the present invention.

[0175] FIG. 16A depicts the movements of various members of a piezoelectric cell in accordance with embodiments of the present invention in response to the application of a normal force. In embodiments, when the normal face is applied to a top member (e.g., member 1401), the top member will bend in toward the plurality of piezo electrodes (e g., electrodes 1405), the plurality of the lateral members (e.g., one lateral member 1503 ) will be depressed214897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) dow n tow ard their respective piezo electrodes, and the column included of one or more vertical struts (e.g.. struts 1501) will be depressed down toward it's respective piezo electrode. In embodiments, upon receiving the forces described above from their respective members and column, the piezo electrodes will output a first distinct voltage and / or a first distinct change in capacitance. In embodiments, the first distinct voltage and / or the first distinct change in capacitance will be distinct from a second distinct voltage and / or a second distinct change in capacitance generated by applying a shear force, as discussed below and as shown in FIG. 16B.

[0176] FIG. 16B depicts the movements of various members of a piezoelectric cell in accordance with embodiments of the present invention in response to the application of a first shear force. In embodiments, when the shear face is applied to the piezo electric cell, one of the plurality of lateral members (e.g. 1503) will receive a tensile force, an opposing member of the plurality of lateral members (e.g. 1505) will receive a compressive force, and the one or more vertical struts (e.g. 1501) comprising the column will receive tensile and compressive forces respectively in accordance with their placement within the column. In embodiments, upon receiving the forces described above from their respective members and column, the piezo electrodes will output the second distinct voltage and / or the second distinct change in capacitance, which will be distinct from the first distinct voltage and / or the first distinct change in capacitance output in response to a normal force as shown in FIG. 16A and described in the paragraph above.

[0177] In embodiments, a piezoelectric cell can output a third distinct voltage and / or a third distinct change in capacitance in response to a second shear force. The mechanism by which the third distinct voltage and / or the third distinct change in capacitance are generated are the same as described by FIG. 16B and the accompanying description, but with respect to a different lateral member and opposing lateral member than 1503 and 1505.

[0178] In embodiments, a piezoelectric cell can output a plurality of distinct voltages and / or distinct changes in capacitance in response to a combination of ferees from the group selected from a normal force, and a plurality of shear forces. For example, the piezoelectric cell can output a plurality of distinct voltages and a plurality of distinct changes in capacitance for each of the normal force, a first shear force, a second shear force, the normal force and the first shear force, and the normal face and the normal force and the second shear force.

[0179] In embodiments, a piezoelectric cell can output a plurality of distinct voltages and a plurality of distinct changes in capacitance based on the ratios of stiffness between the top224897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) member, the plurality of lateral members, and the column. When the ratios of stiffness are used to decouple the forces applied to the piezoelectric cell, this is called passive decoupling, as opposed to active force decoupling using additional sensors, actuators or control system to actively modify system behavior. Passive decoupling represents an advantage of the present invention as it: requires no power to operate, making it useful for wearables or low7energy system; is simple and reliable with fewer moving parts; it generates an instantaneous response governed by inherent mechanical properties; and is low cost.

[0180] In embodiments, a piezoelectric cell includes a plate (e.g.. plate 1507) between the column of one or more struts and the respective piezo electrode.

[0181] FIGs. 17A-B are graphs depicting the linearity of voltage responses and capacitive response to force applied to piezoelectric cells in accordance with embodiments of the present invention.

[0182] As FIGs. 17A and 17B demonstrate, in embodiments, when forces are applied to a piezo electric cell the cell responds with a linear output of voltage and / or linear output of change in capacitance. The linear output of voltage is useful for sensing fast applications of force. The linear output of change in capacitance is useful for sensing slow or static applications of force.

[0183] In embodiments, a sensor according to embodiments of the present invention can be manufactured by any suitable 3D printing process.

[0184] In embodiments, the sensor is fabricated in two parts, the piezoelectric cells, and the circuit platform. In embodiments, a layer of silver paste is sprayed onto one or more of the top member, the plurality of lateral members, and the column and dried before printing the piezoelectric elements. In embodiments, the circuit platform is printed separately using both the neutral TMPTA resin and the negatively charged resin, ensuring electrical insulation and plating compatibility. In embodiments, after printing, the two parts are assembled using a pick- and-place machine for precise alignment.

[0185] In embodiments, the sensor undergoes a 10-minute UV post-curing to eliminate unreacted polymer residues and enhance mechanical stability. In embodiments, electroless plating is performed to deposit conductive metal (Cu or Ni) onto the onto one or more of the top member, the plurality of lateral members, and the column and the circuit platform. The negatively charged regions selectively attract palladium (Pd) cations, which are reduced to234897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) palladium. Palladium acts as a catalyst for subsequent metal deposition, forming conductive pathways.

[0186] In embodiments, the sensor is polarized by applying a high DC electric field. In embodiments, the electric field is 5 V / pm. This high voltage DC field aligns the dipoles within the piezoelectric elements.

[0187] In exemplary embodiments, a piezoelectric cell including: (a) a top member; (b) a plurality of piezo electrodes disposed beneath the top member; (c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; (d) a column including one or more vertical struts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes.

[0188] In embodiments, the piezoelectric cell is used to sense a normal deformation and a plurality of shear deformations.

[0189] In embodiments, the piezoelectric cell decouples the normal deformation and the plurality of shear deformations.

[0190] In embodiments, the stiffness ratio between the plurality of lateral members and the column is sufficient to decouple a normal deformation from plurality of shear force deformations.

[0191] In embodiments, when two or more of a normal deformation and a plurality of shear deformations is applied to the piezoelectric cell, the piezoelectric cell outputs a plurality of distinct voltages, wherein each distinct voltage of the plurality of distinct voltages corresponds respectively to one of the normal deformation and the plurality of shear deformations.

[0192] In embodiments, the column is disposed w ithin the plurality of lateral members.

[0193] In embodiments, the column includes four vertical struts.

[0194] In embodiments, the column further includes a plate disposed in between the one or more vertical struts and the top member and / or a plate disposed in between the one or more vertical struts and the respective piezo electrode of the plurality of piezo electrodes.

[0195] In embodiments, the top member, the plurality of lateral members, and the column include the same material.244897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0196] In embodiments, the same material includes TMPTA (Millipore Sigma, USA), 1-3 wt.% photoinitiator Irg819, 15 vol% PDD, and a neutral TMPTA resin (without PDD).

[0197] In embodiments, a portion of the top member, the plurality of lateral members, and / or the column is plated with a conductive metal.

[0198] In embodiments, the conductive metal is plated copper or nickel.

[0199] In embodiments, the plurality of piezo electrodes includes a polymer matrix and dispersed piezoelectric particles.

[0200] In embodiments, the plurality of piezo electrodes include about 40 vol% propylene carbonate and about 60 vol% PEGDA with 1-3 wt.% photoinitiator Irg819.

[0201] In embodiments, the piezoelectric cell is monolithically printed.

[0202] In embodiments, the piezoelectric cell includes four lateral members.

[0203] In embodiments, the piezoelectric cell is part of an array of piezoelectric cells.

[0204] In embodiments, a sensor including one or more piezoelectric cells, wherein each piezoelectric cell includes: (a) a top member; (b) a plurality of piezo electrodes disposed beneath the top member; (c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; (d) a column including one or more vertical stmts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes: and wherein the sensor includes a circuit platform electrically connected to the plurality of piezo electrodes of each of the one or more piezoelectric cells.

[0205] In embodiments, the sensor is used to sense a normal deformation and a plurality of shear deformations.

[0206] In embodiments, the sensor decouples the normal deformation and the plurality of shear deformations.

[0207] In embodiments, for each piezoelectric cell, the stiffness ratio between the plurality of lateral members and the column is sufficient to decouple a normal deformation from plurality7of shear deformations.

[0208] In embodiments, for each piezoelectric cell, when two or more of a normal deformation and a plurality of shear deformations is applied to the piezoelectric cell, the piezoelectric cell outputs a plurality of distinct voltages, wherein each distinct voltage of the254897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) plurality of distinct voltages corresponds respectively to one of the normal deformation and the plurality of shear deformations.

[0209] In embodiments, for each piezoelectric cell, the column is disposed within the plurality of lateral members.

[0210] In embodiments, for each piezoelectric cell, the column includes four vertical struts.

[0211] In embodiments, for each piezoelectric cell, the column further includes a plate disposed in between the one or more vertical struts and the top member and / or a plate disposed in between the one or more vertical struts and the respective piezo electrode of the plurality of piezo electrodes.

[0212] In embodiments, for each piezoelectric cell, the top member, the plurality of lateral members, and the column include the same material.

[0213] In embodiments, the same material includes about TMPTA (Millipore Sigma, USA), 1-3 wt.% photoinitiator Irg819, 15 vol% PDD, and a neutral TMPTA resin (without PDD).

[0214] In embodiments, for each piezoelectric cell, a portion of the top member, the plurality of lateral members, and / or the column is plated with conductive metal.

[0215] In embodiments, for each piezoelectric cell, the conductive metal is plated copper or nickel.

[0216] In embodiments, for each piezoelectric cell, the plurality of piezo electrodes includes a polymer matrix and dispersed piezoelectric particles.

[0217] In embodiments, the plurality of piezo electrodes include about 40 vol% propylene carbonate and about 60 vol% PEGDA with 1-3 wt.% photoinitiator Irg819.

[0218] In embodiments, each piezoelectric cell is monolithically printed.

[0219] In embodiments, each piezoelectric cell includes four lateral members.GENERAL

[0220] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary7skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary264897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0221] In the discussion unless otherwise stated, adjectives such as "‘substantially" and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment of the invention, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended. In embodiments, about means within a standard deviation using measurements generally acceptable in the art. In embodiments, about means a range extending to + / - 10% of the specified value. In embodiments, about includes the specified value. Unless otherwise indicated, the word “or” in the specification and claims is considered to be the inclusive “or” rather than the exclusive or, and indicates at least one of and any combination of items it conjoins.

[0222] It should be understood that the terms “a” and “an” as used above and elsewhere herein refer to “one or more” of the enumerated components. It will be clear to one of ordinary skill in the art that the use of the singular includes the plural unless specifically stated otherwise. Therefore, the terms “a,” “an” and “at least one” are used interchangeably in this application.

[0223] For purposes of better understanding the present teachings and in no way limiting the scope of the teachings, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary7depending upon the desired properties sought to be obtained. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0224] In the description and claims of the present application, each of the verbs, “comprise,” “include” and “have” and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb. Other terms as used herein are meant to be defined by their well-known meanings in the art.

[0225] For the foregoing embodiments, each embodiment disclosed herein is contemplated as being applicable to each of the other disclosed embodiments.274897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)

[0226] As used herein, all headings are simply for organization and are not intended to limit the disclosure in any manner. The content of any individual section may be equally applicable to all sections. All combinations of the various elements disclosed herein are within the scope of the invention.

[0227] Additional objects, advantages, and novel features of the present invention will become apparent to one ordinarily skilled in the art upon examination of the following examples, which are not intended to be limiting. Additionally, each of the various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below finds experimental support in the following examples.

[0228] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.284897-0584-9405v.2

Claims

Attorney Docket No: 00495-0025 (B25-007-PCT)CLAIMSWhat is claimed is:

1. A piezoelectric cell comprising: a) a top member; b) a plurality of piezo electrodes disposed beneath the top member; c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; d) a column comprising one or more vertical struts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes.

2. The piezoelectric cell of claim 1 , wherein the piezoelectric cell is used to sense a normal deformation and a plurality of shear deformations.

3. The piezoelectric cell of claim 2, wherein the piezoelectric cell decouples the normal deformation and the plurality of shear deformations.

4. The piezoelectric cell of claim 3, wherein the stiffness ratio between the plurality of lateral members and the column is sufficient to decouple a normal deformation from plurality of shear force deformations.

5. The piezoelectric cell of any one of claims 1-4, wherein when two or more of a normal deformation and a plurality of shear deformations is applied to the piezoelectric cell, the piezoelectric cell outputs a plurality of distinct voltages, wherein each distinct voltage of the plurality of distinct voltages corresponds respectively to one of the normal deformation and the plurality of shear deformations.

6. The piezoelectric cell of any one of claims 1-5, wherein the column is disposed within the plurality of lateral members.

7. The piezoelectric cell of any one of claims 1-6, wherein the column comprises four vertical struts.

8. The piezoelectric cell of any one of claims 1-7, wherein the column further comprises a plate disposed in between the one or more vertical struts and the top member and / or294897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) a plate disposed in between the one or more vertical struts and the respective piezo electrode of the plurality of piezo electrodes.

9. The piezoelectric cell of any one of claims 1-8, wherein the top member, the plurality of lateral members, and the column comprise the same material.

10. The piezoelectric cell of claim 9, wherein the same material comprises TMPTA (Millipore Sigma, USA), 1-3 wt.% photoinitiator Irg819, 15 vol% PDD, and a neutral TMPTA resin (without PDD).

11. The piezoelectric cell of any one of claims 1-10, wherein a portion of the top member, the plurality of lateral members, and / or the column is plated with a conductive metal.

12. The piezoelectric cell of claim 11, wherein the conductive metal is plated copper or nickel.

13. The piezoelectric cell of any one of claims 1-12, wherein the plurality7of piezo electrodes comprises a polymer matrix and dispersed piezoelectric particles.

14. The piezoelectric cell of claim 13, wherein the plurality of piezo electrodes comprise about 40 vol% propylene carbonate and about 60 vol% PEGDA with 1-3 wt.% photoinitiator Irg819.

15. The piezoelectric cell of any one of claims 1-14, wherein the piezoelectric cell is monolithically printed.

16. The piezoelectric cell of any one of claims 1-15. wherein the piezoelectric cell comprises four lateral members.

17. The piezoelectric cell of any one of claims 1-16, wherein the piezoelectric cell is part of an array of piezoelectric cells.

18. A sensor comprising one or more piezoelectric cells, wherein each piezoelectric cell comprises: a) a top member; b) a plurality of piezo electrodes disposed beneath the top member; c) a plurality of lateral members each connected to the top member and a respective piezo electrode of the plurality7of piezo electrodes;304897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT) d) a column comprising one or more vertical struts, wherein the one or more vertical struts are connected to the top member and a respective piezo electrode of the plurality of piezo electrodes; and wherein the sensor comprises a circuit platform electrically connected to the plurality of piezo electrodes of each of the one or more piezoelectric cells.

19. The sensor of claim 18, wherein the sensor is used to sense a normal deformation and a plurality of shear deformations.

20. The sensor of claim 19, wherein the sensor decouples the normal deformation and the plurality of shear deformations.

21. The sensor of claim 20, wherein, for each piezoelectric cell, the stiffness ratio between the plurality of lateral members and the column is sufficient to decouple a normal deformation from plurality of shear deformations.

22. The sensor of any one of claims 19-21, wherein, for each piezoelectric cell, when two or more of a normal deformation and a plurality of shear deformations is applied to the piezoelectric cell, the piezoelectric cell outputs a plurality of distinct voltages, wherein each distinct voltage of the plurality of distinct voltages corresponds respectively to one of the normal deformation and the plurality of shear deformations.

23. The sensor of any one of claims 18-22. wherein, for each piezoelectric cell, the column is disposed within the plurality of lateral members.

24. The sensor of any one of claims 18-23, wherein, for each piezoelectric cell, the column comprises four vertical struts.

25. The sensor of any one of claims 18-24, wherein, for each piezoelectric cell, the column further comprises a plate disposed in between the one or more vertical struts and the top member and / or a plate disposed in between the one or more vertical struts and the respective piezo electrode of the plurality of piezo electrodes.

26. The sensor of any one of claims 18-25, wherein, for each piezoelectric cell, the top member, the plurality of lateral members, and the column comprise the same material.314897-0584-9405v.2Attorney Docket No: 00495-0025 (B25-007-PCT)27. The sensor of claim 26, wherein the same material comprises about TMPTA (Millipore Sigma, USA), 1-3 wt.% photoinitiator Irg819, 15 vol% PDD, and a neutral TMPTA resin (without PDD).

28. The sensor of any one of claims 18-27, wherein, for each piezoelectric cell, a portion of the top member, the plurality of lateral members, and / or the column is plated with conductive metal.

29. The sensor of claim 28, wherein, for each piezoelectric cell, the conductive metal is plated copper or nickel.

30. The sensor of any one of claims 18-29, wherein, for each piezoelectric cell, the plurality of piezo electrodes comprises a polymer matrix and dispersed piezoelectric particles.

31. The sensor of claim 30, wherein the plurality of piezo electrodes comprise about 40 vol% propylene carbonate and about 60 vol% PEGDA with 1-3 wt.% photoinitiator Irg819.

32. The sensor of any one of claims 18-31. wherein each piezoelectric cell is monolithically printed.

33. The sensor of any one of claims 18-32, wherein, each piezoelectric cell comprises four lateral members.324897-0584-9405v.2

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