Application of anisotropic material in printing flexible capacitive sensor

Abstract

The disclosed embodiments include a flexible member having a flexible capacitive sensing region and at least one motion limiter located in at least a portion of the flexible capacitive sensing region, the at least one motion limiter preventing deflection in a limited axial direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 379,979, filed on October 18, 2022, entitled “Anisotropic Materials Applications In Printed Flexible Capacitive Sensors,” under 35 U.S.C. 119, the contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure generally relates to compliant sensor systems and methods for sensors that can bend, flex, stretch, twist, etc. to measure force, strain, stress, etc. More specifically, the present disclosure relates to compliant sensor systems and methods for sensors configured to have anisotropic movement behavior. Background Art

[0003] Flexible sensors are known. For example, U.S. Patent Nos. 8,941,392, 9,222,764, 9,476,692, 9,612,102, 9,874,431, 10,551,917, 10,823,546, 10,959,644, and U.S. Patent Application Publication No. 2022 / 0034692 disclose flexible sensors, the contents of which are incorporated herein by reference. However, there may be a need for making clear and directional measurements or comparisons using flexible sensors. Existing flexible sensors typically exhibit an isotropic response to a given range of deflections or strains and typically provide a magnitude, but not a direction, for a given measurement.

[0004] Theoretically, if the dimension of the undesired axial direction (i.e., the direction in which measurement is undesirable) is reduced to an infinitesimal value, the integrated strain recorded by the sensor should primarily be from the desired axial direction (i.e., the direction in which measurement is desired). In practice, this approach does not work due to, among other reasons, the high resistivity of the sensor's conductive layer. Current systems and methods also suffer from other drawbacks, inconveniences, inefficiencies, and problems. Summary of the Invention

[0005] Thus, the disclosed embodiments address the aforementioned shortcomings, inconveniences, inefficiencies, and problems with current systems and methods.The disclosed systems and methods also have other advantages and efficiencies.

[0006] As used herein, "flexible," "extensible," "compliant," "deformable," etc. are used somewhat interchangeably and all mean that there is a certain amount of flexing, stretching, compression, torsion, bending, etc., for the described embodiment.

[0007] As used herein, the terms "undesired axial direction," "restricted axial direction," "unmeasured axial direction," etc., refer to directions in which it is undesirable for a sensor to measure or read. Similarly, the terms "desired axial direction," "unrestricted axial direction," "measured axial direction," etc., refer to directions in which it is desirable for a sensor to measure or read.

[0008] It should be understood that the terms "vertical," "horizontal," "lateral," "upper," "lower," "top," "bottom," "left," "right," "inner," "outer," and the like, as used herein, may refer to the relative orientations or positions of features of related devices and / or components as shown in the accompanying drawings. For example, "upper" or "topmost" may refer to a feature that is positioned closer to the top of the page than another feature. However, these terms should be broadly interpreted to include devices and / or components having other orientations, such as reverse or oblique orientations, where top / bottom, above / below, over / below, up / down, and left / right may be interchanged based on orientation.

[0009] The disclosed exemplary embodiment includes a compliance sensor having an inextensible fiber parallel to an unmeasured axis. The fiber physically resists the force induced by a deformation source until the fiber breaks. In this way, the signal from the constrained, unmeasured axis is filtered out, leaving only the measurement from the unconstrained axis. Other embodiments exist. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic cross-sectional view of a laminate used to form a compliant sensor system according to disclosed embodiments.

[0011] Figure 2 A multi-region angular displacement sensor according to the disclosed embodiments.

[0012] Figure 3 is an illustrative example of a deformable isotropic printed flexible capacitive sensor system according to the disclosed embodiments.

[0013] Figure 4 is an illustrative example of a deformable anisotropic printed flexible capacitive sensor system according to the disclosed embodiments.

[0014] Figure 5is a schematic diagram of an anisotropic sensor system with motion limiters in the signal traces according to the disclosed embodiments.

[0015] Figure 7 is a schematic diagram of an anisotropic sensor system embedded in an adhesive according to disclosed embodiments.

[0016] Figure 6A and Figure 6B is a schematic diagram of an anisotropic sensor system according to a disclosed embodiment.

[0017] While specific embodiments are shown by way of example in the drawings and will be described in detail herein, the present invention is susceptible to various modifications and alternative forms. However, it should be understood that the present invention is not limited to the specific embodiments disclosed. Rather, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the claims. DETAILED DESCRIPTION

[0018] Figure 1 2 is a schematic cross-sectional view of a laminate 200 forming a compliant sensor system. As shown, dielectric layer 12 is positioned between top electrode layer 2 and signal electrode layer 16. Furthermore, peripheral electrode 140 is schematically shown electrically connecting top electrode layer 2 and signal electrode layer 16. Other configurations are also possible.

[0019] In some embodiments, the top electrode layer 2 may include an elastomeric layer (e.g., silicone) in which conductive particles (e.g., nanoparticles such as carbon black, nickel nanowires, silver nanoparticles, graphene microplatelets, graphene oxide, etc.) are incorporated. Figure 2 Although shown as a continuous layer, the top electrode layer 2 can also be "hatched" or otherwise discontinuous. The top electrode layer 2 can also include a printed circuit board (PCB) interface and a plurality of conductive trace pads for connecting to the PCB, sensor traces, or other electronic devices to operate and control the sensor system.

[0020] In some embodiments, the dielectric layer 12 may include an elastomeric material (eg, silicone) and may incorporate some conductive material therein as desired based on the desired amount of dielectric constant, etc. Figure 1 The figures are not drawn strictly to scale, but in some embodiments, the dielectric layer 12 is sized slightly smaller than the top electrode layer 2 so that the peripheral edge of the top electrode layer 2 is not covered by the dielectric layer 12 and allows electrical contact with the peripheral electrode 140 described below.

[0021] In some embodiments, the signal electrode layer 16 may comprise an elastomeric material (e.g., silicone) having therein a conductive material (e.g., nanoparticles such as carbon black, nickel nanowires, silver nanoparticles, graphene microplatelets, graphene oxide, etc.) confined to the sensor regions, traces, and peripheral electrodes 140. Figure 3 The signal electrode layer 16 may be distributed throughout the signal electrode layer 16 (see, e.g., Figure 3 ). The sensor area 20 may include an area of ​​conductive material. The sensor area 20 is connected to the traces 22 printed on the signal electrode layer 16 (in Figure 3 The top electrode layer 2 is electrically connected to the signal electrode layer 16 (labeled "signal trace line" in the figure and used interchangeably with "trace(s)" herein). As shown, embodiments of the signal electrode layer 16 may include a peripheral electrode 140 electrically connected to the top electrode layer 2, thereby providing electrical isolation for the sensor system as a whole. Other configurations are also possible.

[0022] Figure 2 FIG. 8 is a multi-region angular displacement sensor 800 according to the disclosed embodiment. As shown in the figure, Figure 1 The sensor systems 200 disclosed in FIG. 8 and FIG. 9 are connected together to form an angular displacement sensor 800. For example, by connecting sensor system 200A to a second sensor system 200B via an elastomeric connector 802, an angular displacement sensor 800 (single region, multi-region, etc.) can be implemented. Further disclosure regarding the construction, operation, and implementation of such displacement sensor systems 800 can be found in U.S. Patent No. 10,551,917, entitled “Compliant Multi-Region Angular Displacement And Strain Sensors,” the disclosure of which is incorporated herein by reference in its entirety.

[0023] As will be understood by one of ordinary skill in the art having the benefit of this disclosure, angular displacement sensor 800 can be extended to any number of areas as desired as shown by the addition of elastomeric connector 802 and sensor system 200N. Other configurations are also possible.

[0024] Figure 3FIG2 is an illustrative embodiment of a deformable, isotropic printed flexible capacitive sensor system 300 according to the disclosed embodiments. As shown, at least one sensing region 20 can be included in the elastic material, and the sensing region 20 is provided with one or more signal traces 22 for electronic communication with other system circuits and components. Other configurations are also possible.

[0025] Figure 4 FIG2 is an illustrative embodiment of a deformable anisotropic printed flexible capacitive sensor system 400 according to the disclosed embodiments. As shown, the anisotropic sensor system 400 includes a motion limiter 24 in the sensing region 20 that limits or otherwise prevents deflection or extension along a restricted axis. In some embodiments, the motion limiter 24 may include carbon fiber, poly (p-phenylene terephthalamide) (e.g., ) fiber, woven fiber, glass fiber, inextensible film, epoxy resin, etc. In addition, the motion limiter 24 can be conductive or non-conductive as needed.

[0026] like Figure 4 As schematically shown, the anisotropic sensor system 400 is capable of making flexure or extension measurements in a "vertical" (top to bottom on the page) direction and restricting flexure or extension measurements in a "horizontal" (left to right on the page) direction. Typically, the motion limiters 24 can be printed, attached, or otherwise included in the sensor 400 in a manner parallel to the preferred restriction direction to enable flexure or extension measurements in a direction perpendicular to the arrangement of the motion limiters 24. Of course, as will be understood by those of ordinary skill in the art having the benefit of this disclosure, measurements in any direction may be achieved by appropriately including or excluding the motion limiters 24. For example, referring to Figure 4 A "diagonal" pattern of motion limiters 24 would enable flexure or extension measurements to be taken in a 45-degree (or other angled) direction (e.g., lower left corner to upper right corner on a page). Furthermore, motion limiters 24 could be arranged in more than one axial direction (e.g., a cross-hatched pattern) to simultaneously prevent flexure or extension measurements in more than one direction. Other embodiments are also possible.

[0027] The spacing of the motion limiters 24 can also be varied as desired. For example, the spacing can be determined by the smallest expected deformable object size. Generally, the contact area between the deformable object and the sensing area 20 should be greater than the spacing of the motion limiters 24 to ensure contact with at least one limiter 24. Other embodiments are also possible.

[0028] Figure 5Figure 5 is a schematic diagram of an anisotropic sensor system 500 having motion limiters 24 in signal traces 22, according to disclosed embodiments. In some embodiments, it may be desirable to anisotropically limit signal traces 22 in a deformable, flexible sensor, particularly to mitigate undesirable effects on the signal generated as a byproduct of deformation of the signal traces 22. As shown, one or more signal traces 22 can be in electrical contact with the sensing area 20. As shown in exploded portion "A," motion limiters 24 can be included to limit deformation unidirectionally (from top to bottom on the page) and in the vertical direction (from left to right on the page). In some embodiments, as shown in exploded portion "B," bidirectional restriction may be desirable, with motion limiters 24A provided in one direction (from left to right on the page) and motion limiters 24B provided in a second direction (from top to bottom on the page), thereby simultaneously limiting flexure or extension in both directions. In multi-directional restriction embodiments, motion limiters 24 can be provided in a single layer, multiple layers, a braided layer, and so on. Other configurations and embodiments are also possible.

[0029] Figure 6A and Figure 6B FIG is a schematic diagram of anisotropic sensor systems 600A and 600B according to the disclosed embodiments. As schematically shown, the motion limiter 24 can be placed in any layer of the sensor system. For example, Figure 6A As shown, the motion limiter 24 can be placed in a conductive layer (e.g., signal layer 16), or, as shown in FIG. Figure 6B As shown, the motion limiter 24 may be placed in a non-conductive layer (eg, dielectric layer 12 ).

[0030] Typically, the motion limiter 24 can be conductive and directly connected to a specified electrode layer (e.g., top electrode 2, signal electrode 16, etc.). If the conductivity of the motion limiter 24 is higher than that of the electrode, this will have the additional advantage of increasing the conductivity of the electrode. Alternatively, with respect to the conductive motion limiter 24, the signal layer 16 can be replaced with a conductive motion limiter 24. Alternatively, the motion limiter 24 can be connected to a conductive layer. When included in the signal trace 22, if the resistivity of the motion limiter 24 is lower than the resistivity of the electrode layer, the conductor loss of the signal trace 22 will be lower. Other advantages and embodiments exist.

[0031] Figure 7 is a schematic diagram of an anisotropic sensor system 700 embedded in an adhesive 704 according to the disclosed embodiments. For example, a sensor having an anisotropic motion limiter 24 ( Figure 7Anisotropic elements (e.g., carrier layer 706) (not shown) can be embedded in an adhesive (e.g., layer 704) that is used to bond all or some portions of sensor system 700 to a target substrate (e.g., the inside of a tire, etc.). In some embodiments, a backing layer 702 can also be provided, in particular to protect the outer adhesive layer 704. Other configurations and embodiments are also possible.

[0032] Although various embodiments have been shown and described, the present disclosure is not limited thereto, but should be construed to include all changes and modifications that are obvious to those skilled in the art.

Claims

1. A flexible sensor comprising: Flexible capacitive sensing area; as well as At least one motion limiter is located in at least a portion of the flexible capacitive sensing area and prevents deflection along a restricted axial direction.

2. The flexible sensor according to claim 1, wherein The motion limiter further includes at least one of carbon fiber, poly(p-phenylene terephthalamide) fiber, woven fiber, glass fiber, inextensible film, or epoxy resin.

3. The flexible sensor according to claim 1, further comprising: One or more signal traces in electronic communication with the flexible capacitive sensing area.

4. The flexible sensor according to claim 3, further comprising: At least one motion limiter is positioned in at least a portion of the one or more signal traces and prevents deflection along a restricted axis.

5. The flexible sensor according to claim 3, further comprising: At least two motion limiters, located in at least a portion of the one or more signal traces, prevent flexure along two limited axial directions.

6. A flexible sensor comprising: Flexible capacitive sensing area; one or more signal traces in electronic communication with the flexible capacitive sensing area; as well as At least one motion limiter is positioned in at least a portion of the one or more signal traces and prevents deflection along a restricted axial direction. 7 . The flexible sensor according to claim 6 , wherein the motion limiter further comprises at least one of carbon fiber, poly(p-phenylene terephthalamide) fiber, woven fiber, glass fiber, an inextensible film, or epoxy resin.

8. The flexible sensor according to claim 6, further comprising: At least two motion limiters are positioned in at least a portion of the one or more signal traces and prevent deflection along two restricted axial directions.

9. An anisotropic flexible sensor, comprising: an elastomer signal electrode layer; an elastomer top electrode layer; an elastomeric dielectric layer positioned between the signal electrode layer and the top electrode layer; as well as At least one motion limiter that prevents deflection along a restricted axial direction.

10. The anisotropic flexible sensor according to claim 9, wherein: The at least one motion limiter is at least partially located in the dielectric layer.

11. The anisotropic flexible sensor according to claim 9, wherein: The at least one motion limiter is at least partially located in at least one of the signal electrode layer or the top electrode layer.

12. The anisotropic flexible sensor according to claim 9, wherein: The motion limiter further includes at least one of carbon fiber, poly(p-phenylene terephthalamide) fiber, woven fiber, glass fiber, inextensible film, or epoxy resin.

13. The anisotropic flexible sensor according to claim 9, further comprising: At least one adhesive layer for attaching the anisotropic flexible sensor to a target substrate.

Images