Artificial muscle including electrode pair and artificial muscle assembly including same

Abstract

To provide an artificial muscle including a housing having an electrode region and an expandable fluid region, and an electrode pair which is positioned within the electrode region, and which has a first electrode fixed to a first surface of the housing and a second electrode fixed to a second surface of the housing.SOLUTION: Each of a first electrode 106 and a second electrode 108 has two or more tab portions 132 and two or more bridge portions 140. Each of two or more bridge portions interconnects an adjacent tab portion, and at least one of the first and second electrodes includes a central opening portion 146, 168 positioned between two or more tab portions and surrounding an expandable fluid region. A dielectric fluid is stored within a housing 102, and the electrode pair is operable between a non-operation state and an operation state such that the dielectric fluid is induced into the expandable fluid region by the operation from the non-operation state to the operation state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present specification relates generally to an apparatus and method for focused expansion on at least one surface of a device, and more particularly to an apparatus and method that uses an electrode pair to direct a fluid for the purpose of expanding the device. [Background technology]

[0002] Current robotics technology relies on rigid components such as servo motors to perform tasks, often in structured environments. This rigidity creates constraints in many robotic applications, caused at least in part by the weight-to-power ratio of servo motors and other rigid robotic devices. The field of soft robotics improves on these constraints by using artificial muscles and other soft actuators. Artificial muscles attempt to mimic the versatility, performance, and reliability of biological muscles. Some artificial muscles employ fluidic actuators, but fluidic actuators require a supply of pressurized gas or liquid, and fluid transport must occur through a system of channels and tubes, limiting the speed and efficiency of the artificial muscles. Other artificial muscles use heat-activated polymer fibers, but these are difficult to control and have low operating efficiency.

[0003] One particular artificial muscle design is described in a paper entitled "Hydraulically amplified self-healing electrostatic actuators with muscle-like performance" by E. Acome, SK Mitchell, TG Morrissey, MBEmmett, C. Benjamin, M. King, M. Radakovitz, and C. Keplinger (Science 05 Jan 2018:Vol. 359, Issue 6371, pp. 61-65). These hydraulically amplified self-healing electrostatic (HASEL) actuators use electrostatic forces and fluid pressure to achieve various actuation modes. However, there is a limit to the actuator output per unit volume of HASEL actuator artificial muscles. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, a need exists for improved artificial muscles that have increased actuator power per unit volume. [Means for solving the problem]

[0005] In one embodiment, an artificial muscle includes a housing having an electrode region and an expansion fluid region, and an electrode pair positioned within the electrode region of the housing, the electrode pair including a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing. The first and second electrodes each have two or more tab portions and two or more bridge portions. Each of the two or more bridge portions interconnect adjacent tab portions, and at least one of the first and second electrodes includes a central opening positioned between the two or more tab portions and surrounding the expansion fluid region. A dielectric fluid is contained within the housing, and the electrode pair is actuable between an unactuated state and an actuated state such that actuation from the unactuated state to the actuated state induces a dielectric fluid into the expansion fluid region.

[0006] In another embodiment, an artificial muscle assembly includes a plurality of artificial muscles, each of which includes a housing having an electrode region and an expansion fluid region, and an electrode pair positioned within the electrode region of the housing, the electrode pair including a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing. The first and second electrodes each include two or more tab portions and two or more bridge portions. Each of the two or more bridge portions interconnects adjacent tab portions, and at least one of the first and second electrodes includes a central opening positioned between the two or more tab portions and surrounding the expansion fluid region. A dielectric fluid is contained within the housing, and the plurality of artificial muscles are arranged in a stack such that the expansion fluid regions of each artificial muscle are coaxially aligned with one another, and the electrode pairs are actuable between an unactuated state and an actuated state such that actuation from the unactuated state to the actuated state induces a dielectric fluid into the expansion fluid region.

[0007] In yet another embodiment, a method of operating an artificial muscle assembly includes generating a voltage with a power source electrically coupled to an electrode pair of the artificial muscle, the artificial muscle having a housing with an electrode region and an expansion fluid region. The electrode pair is positioned within the electrode region of the housing. The electrode pair includes a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing. The first electrode and the second electrode each include two or more tab portions and two or more bridge portions. Each of the two or more bridge portions interconnects adjacent tab portions, and at least one of the first electrode and the second electrode has a central opening positioned between the two or more tab portions and surrounding the expansion fluid region. A dielectric fluid is contained within the housing. The method further includes applying a voltage to the electrode pair of the artificial muscle, thereby actuating the electrode pair from an unactuated state to an actuated state such that a dielectric fluid is induced within the expansion fluid region of the housing and causes the expansion fluid region to expand.

[0008] These and additional features provided by the embodiments described herein will be more fully understood by considering the following detailed description in conjunction with the drawings.

[0009] The embodiments set forth in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, in which like structure is labeled with like reference numerals and in which: [Brief description of the drawings]

[0010] [Figure 1] FIG. 1A generally depicts an exploded view of an illustrative artificial muscle according to one or more embodiments shown and described herein. [Diagram 2] FIG. 2A generally depicts a top view of the artificial muscle of FIG. 1 according to one or more embodiments shown and described herein. [Diagram 3] FIG. 3 is a schematic depiction of a cross-sectional view of the artificial muscle of FIG. 1 taken along line 3-3 in FIG. 2 in an unactuated state, according to one or more embodiments shown and described herein. [Figure 4] FIG. 4 is a schematic depiction of a cross-sectional view of the artificial muscle of FIG. 3 in an actuated state, according to one or more embodiments shown and described herein. [Diagram 5] FIG. 13A illustrates a schematic cross-sectional view of an illustrative artificial muscle in an unactuated state, according to one or more embodiments shown and described herein. [Figure 6] FIG. 6 illustrates a schematic cross-sectional view of the artificial muscle of FIG. 5 in an actuated state, according to one or more embodiments shown and described herein. [Figure 7] FIG. 2 is a schematic depiction of an artificial muscle assembly including a plurality of the artificial muscles of FIG. 1 according to one or more embodiments shown and described herein. [Figure 8]FIG. 2 is a schematic depiction of an actuation system for operating the artificial muscle of FIG. 1 according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Embodiments described herein are directed to artificial muscles and artificial muscle assemblies including a plurality of artificial muscles. The artificial muscles described herein are operable to raise and lower a region of the artificial muscle to provide an expansion fluid region that is selectively and on demand expanded. The artificial muscle includes a housing and an electrode pair. A dielectric fluid is contained within the housing, the housing includes an electrode region and an expansion fluid region, where the electrode pair is positioned within the electrode region. The electrode pair includes a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing. The electrode pair is operable between an unactuated state and an actuated state such that actuation from the unactuated state to the actuated state induces dielectric fluid into the expansion fluid region. This expands the expansion fluid region, lifting a portion of the artificial muscle on demand. Additionally, the first and second electrodes each include two or more tab portions and two or more bridge portions interconnecting adjacent tab portions, and at least one of the first and second electrodes includes a central opening positioned between the tab portions and encircling the expansile fluid region. The tab and bridge portion design of the electrode pairs facilitates a fastener-like actuation action to increase the force per unit volume achievable through actuation of the artificial muscle. Various embodiments of artificial muscles and the operation of artificial muscles are described in more detail herein. Whenever possible, the same reference numbers are used throughout the drawings to refer to the same or similar parts.

[0012] 1 and 2, an artificial muscle 100 is shown. The artificial muscle 100 includes a housing 102, an electrode pair 104 including a first electrode 106 and a second electrode 108 secured to opposing surfaces of the housing 102, a first electrical insulator layer 110 secured to the first electrode 106 and a second electrical insulator layer 112 secured to the second electrode 108. In some embodiments, the housing 102 is a one-piece monolithic layer including a pair of opposing inner surfaces, such as a first inner surface 114 and a second inner surface 116, and a pair of opposing outer surfaces, such as a first outer surface 118 and a second outer surface 120. In some embodiments, the first inner surface 114 and the second inner surface 116 of the housing 102 are heat sealable. In other embodiments, the housing 102 can be a pair of separately manufactured film layers, such as a first film layer 122 and a second film layer 124. Thus, the first film layer 122 includes a first inner surface 114 and a first outer surface 118 , and the second film layer 124 includes a second inner surface 116 and a second outer surface 120 .

[0013] It should be understood that throughout the following description, the housing 102 may be referred to as including primarily a first film layer 122 and a second film layer 124, as opposed to a one-piece housing. Either arrangement is contemplated. In some embodiments, the first film layer 122 and the second film layer 124 generally include the same structure and composition. For example, in some embodiments, the first film layer 122 and the second film layer 124 each include biaxially oriented polypropylene.

[0014] The first electrode 106 and the second electrode 108 are each positioned between the first film layer 122 and the second film layer 124. In some embodiments, the first electrode 106 and the second electrode 108 are each an aluminum coated polyester such as Mylar®. Furthermore, one of the first electrode 106 and the second electrode 108 is a negatively charged electrode and the other of the first electrode 106 and the second electrode 108 is a positively charged electrode. For purposes discussed herein, either electrode 106, 108 may be positively charged as long as the other electrode 106, 108 of the artificial muscle 100 is negatively charged.

[0015] The first electrode 106 has a film-facing surface 126 and an opposing inner surface 128. The first electrode 106 is positioned against the first film layer 122, specifically against the first inner surface 114 of the first film layer 122. Additionally, the first electrode 106 includes a first terminal 130 extending from the first electrode 106 through an edge of the first film layer 122 such that the first terminal 130 can be connected to a power source to activate the first electrode 106. Specifically, the terminal is coupled directly or in series to a power source and controller of the activation system 400 as shown in FIG. 8. Similarly, the second electrode 108 has a film-facing surface 148 and an opposing inner surface 150. The second electrode 108 is positioned against the second film layer 124, specifically against the second inner surface 116 of the second film layer 124. The second electrode 108 includes a second terminal 152 extending from the second electrode 108 through the edge of the second film layer 124 such that the second terminal 152 can be connected to a power source and a controller of the actuation system 400 to activate the second electrode 108.

[0016] The first electrode 106 includes two or more tab portions 132 and two or more bridge portions 140. Each bridge portion 140 is positioned between and interconnects adjacent tab portions 132. Each tab portion 132 has a first end 134 that extends radially from a central axis C of the first electrode 106 to an opposite second end 136 of the tab portion 132, where the second end 136 defines a portion of the outer periphery 138 of the first electrode 106. Each bridge portion 140 has a first end 142 that extends radially from the central axis C of the first electrode 106 to an opposite second end 144 of the bridge portion 140 that defines another portion of the outer periphery 138 of the first electrode 106. Extending radially from the central axis C of the first electrode 106, each tab portion 132 has a tab length L1 and each bridge portion 140 has a bridge length L2. Tab length L1 is the distance from first end 134 to second end 132 of tab portion 132, and bridge length L2 is the distance from first end 142 to second end 144 of bridge portion 140. Tab length L1 of each tab portion 132 is longer than bridge length L2 of each bridge portion 140. In some embodiments, bridge length L2 is 20%-50% of tab length L1, such as 30%-40% of tab length L1.

[0017] In some embodiments, the two or more tab portions 132 are arranged in one or more pairs of tab portions 132. Each tab portion pair 132 includes two tab portions 132 disposed diametrically opposite one another. In some embodiments, the first electrode 106 may include only two tab portions 132 positioned on opposite sides or ends of the first electrode 106. As shown in FIGS. 1 and 2, in some embodiments, the first electrode 106 includes four tab portions 132 and four bridge portions 140 interconnecting adjacent tab portions 132. In such embodiments, the four tab portions 132 are arranged as two tab portion pairs 132 diametrically opposite one another. Additionally, as shown, the first terminal 130 extends from and is integrally formed with the second end 136 of one of the tab portions 132.

[0018] Similar to the first electrode 106, the second electrode 108 includes at least a pair of tab portions 154 and two or more bridge portions 162. Each bridge portion 162 is positioned between and interconnects adjacent tab portions 154. Each tab portion 154 has a first end 156 that extends radially from a central axis C of the second electrode 108 to a second end 158 opposite the tab portion 154, where the second end 158 defines a portion of the outer periphery 160 of the second electrode 108. Because the first electrode 106 and the second electrode 108 are coaxial, the central axis C of the first electrode 106 and the second electrode 108 is the same. Each bridge portion 162 has a first end 164 that extends radially from the central axis C of the second electrode to a second end 166 opposite the bridge portion 162 that defines another portion of the outer periphery 160 of the second electrode 108. Extending radially from the central axis C of the second electrode 108, each tab portion 154 has a tab length L3 and each bridge portion 162 has a bridge length L4. The tab length L3 is the distance from the first end 156 to the second end 158 of the tab portion 154, and the bridge length L4 is the distance from the first end 164 to the second end 166 of the bridge portion 162. The tab length L3 is longer than the bridge length L4 of each bridge portion 162. In some embodiments, the bridge length L4 is between 20% and 50% of the tab length L3, such as between 30% and 40% of the tab length L3.

[0019] In some embodiments, the two or more tab portions 154 are arranged in one or more tab portion 154 pairs. Each tab portion pair 154 includes two tab portions 154 disposed diametrically opposite one another. In some embodiments, the second electrode 108 may include only two tab portions 154 located on opposite sides or ends of the first electrode 106. As shown in FIGS. 1 and 2, in some embodiments, the second electrode 108 includes four tab portions 154 and four bridge portions 162 interconnecting adjacent tab portions 154. In such embodiments, the four tab portions 154 are arranged as two tab portion pairs 154 diametrically opposite one another. Additionally, as shown, the second terminal 152 extends from and is integrally formed with the second end 158 of one of the tab portions 154.

[0020] 1-6, at least one of the first electrode 106 and the second electrode 108 has a central opening formed therein between the first end 134 of the tab portion 132 and the first end 142 of the bridge portion 140. In FIGS. 3 and 4, the first electrode 106 has a central opening 146. However, it should be understood that the first electrode 106 need not include the central opening 146 if the central opening is provided within the second electrode 108, as shown in FIGS. 5 and 6. Alternatively, the second electrode 108 need not include a central opening if the central opening 146 is provided within the first electrode 106. Still referring to FIGS. 1-6, the first electrical insulator layer 110 and the second electrical insulator layer 112 generally have a geometry corresponding to the first electrode 106 and the second electrode 108, respectively. Thus, the first and second electrical insulator layers 110, 112 each have tab portions 170, 172 and bridge portions 174, 176 that correspond to similar portions on the first and second electrodes 106, 108. Additionally, the first and second electrical insulator layers 110, 112 each have perimeters 178, 180 that correspond to the perimeter 138 of the first electrode 106 and the perimeter 160 of the second electrode 108 when positioned thereover.

[0021] It should be appreciated that in some embodiments, the first electrical insulator layer 110 and the second electrical insulator layer 112 generally comprise the same structure and composition. Thus, in some embodiments, the first electrical insulator layer 110 and the second electrical insulator layer 112 each comprise an adhesive surface 182, 184 and an opposing non-sealable surface 186, 188, respectively. Thus, in some embodiments, the first electrical insulator layer 110 and the second electrical insulator layer 112 are each polymeric tapes adhered to the inner surface 128 of the first electrode 106 and the inner surface 150 of the second electrode 108, respectively.

[0022] 2-6, the artificial muscle 100 is shown in its assembled configuration with the first terminal 130 of the first electrode 106 and the second terminal 152 of the second electrode 108 extending beyond the periphery of the housing 102, i.e., the first film layer 122 and the second film layer 124. As shown in FIG. 2, the second electrode 108 is stacked on the first electrode 106, and thus the first electrode 106, the first film layer 122 and the second film layer 124 are not shown. The first electrode 106, the second electrode 108, the first electrical insulator layer 110 and the second electrical insulator layer 112 are sandwiched between the first film layer 122 and the second film layer 124 in its assembled configuration. The first film layer 122 is partially sealed to the second film layer 124 in an area surrounding the perimeter 138 of the first electrode 106 and the perimeter 160 of the second electrode 108. In some embodiments, the first film layer 122 is heat sealed to the second film layer 124. Specifically, in some embodiments, the first film layer 122 is sealed to the second film layer 124 to define a sealed portion 190 that surrounds the first electrode 106 and the second electrode 108. The first film layer 122 and the second film layer 124 may be sealed in any suitable manner, for example, with an adhesive, heat sealing, or the like.

[0023] The first electrode 106, the second electrode 108, the first electrical insulator layer 110, and the second electrical insulator layer 112 provide a barrier that prevents the first film layer 122 from sealing to the second film layer 124, forming an unsealed portion 192. The unsealed portion 192 of the housing 102 includes an electrode region 194, within which the electrode pair 104 is provided, and an expandable fluid region 196 that is surrounded by the electrode region 194. The central openings 146, 168 of the first electrode 106 and the second electrode 108 form the expandable fluid region 196 and are arranged to be axially stacked on top of each other. Although not shown, the housing 102 may be cut to fit the geometry of the electrode pair 104 and reduce the size of the artificial muscle 100, i.e., the size of the sealed portion 190.

[0024] A dielectric fluid 198 is provided within the unsealed portion 192 and flows freely between the first electrode 106 and the second electrode 108. As used herein, a "dielectric" fluid is a medium or material that transmits electrical force without conduction and thus has low electrical conductivity. Some non-limiting exemplary dielectric fluids include perfluoroalkanes, transformer oil, and deionized water. It should be appreciated that the dielectric fluid 198 can be injected into the unsealed portion 192 of the artificial muscle 100 using a needle or other suitable injection device.

[0025] 3 and 4, the artificial muscle 100 is actuable between an unactuated state and an actuated state. In the unactuated state shown in FIG. 3, the first electrode 106 and the second electrode 108 are partially spaced apart from one another proximate their central openings 146, 168 and the first ends 134, 156 of the tab portions 132, 154. The second ends 136, 158 of the tab portions 132, 154 remain in a predetermined position relative to one another because the housing 102 is sealed at the perimeter 138 of the first electrode 106 and the perimeter 160 of the second electrode 108. In the actuated state shown in FIG. 4, the first electrode 106 and the second electrode 108 are in contact with one another and oriented parallel to one another to force the dielectric fluid 198 into the expansion fluid region 196. This causes the dielectric fluid 198 to flow through the central openings 146, 168 of the first electrode 106 and second electrode 108 causing the expandable fluid region 196 to expand.

[0026] 3, the artificial muscle 100 is shown in an unactuated state. The electrode pair 104 is provided within an electrode region 194 of an unsealed portion 192 of the housing 102. The central opening 146 of the first electrode 106 and the central opening 168 of the second electrode 108 are coaxially aligned within an expansion fluid region 196. In the unactuated state, the first electrode 106 and the second electrode 108 are partially spaced apart from each other and are not parallel to each other. The first film layer 122 is sealed to the second film layer 124 around the electrode pair 104 such that the second ends 136, 158 of the tab portions 132, 154 are brought into contact with each other. Thus, a dielectric fluid 198 is provided between the first electrode 106 and the second electrode 108, thus isolating the first ends 134, 156 of the tab portions 132, 154 adjacent the expansion fluid region 196. In other words, the distance between the first end 134 of the tab portion 132 of the first electrode 106 and the first end 156 of the tab portion 154 of the second electrode 108 is greater than the distance between the second end 136 of the tab portion 132 of the first electrode 106 and the second end 158 of the tab portion 154 of the second electrode 108. As a result, the electrode pair 104 zips closed toward the expansion fluid region 196 when actuated. In some embodiments, the first electrode 106 and the second electrode 108 may be flexible. Thus, as shown in FIG. 3, the first electrode 106 and the second electrode 108 are convex such that the second ends 136, 158 of the tab portions 132, 154 thereof can remain spaced apart from each other while still being closed to each other and adjacent the central openings 146, 168. In the unactuated state, the expansive fluid region 196 has a first height H1.

[0027] As shown in FIG. 4, when activated, the first electrode 106 and the second electrode 108 close toward each other from the second ends 144, 158 of their tab portions 132, 154 in a fastener-like manner, thereby forcing the dielectric fluid 198 into the expansion fluid region 196. As shown, in the actuated state, the first electrode 106 and the second electrode 108 are parallel to each other. In the actuated state, the dielectric fluid 198 flows into the expansion fluid region 196, causing it to expand. Thus, the first film layer 122 and the second film layer 124 expand in opposite directions. In the actuated state, the expansion fluid region 196 has a second height H2, which is greater than the first height H1 of the expansion fluid region 196 when in the unactuated state. Although not shown, it should be noted that the electrode pair 104 can be partially actuated to a position between the unactuated state and the actuated state. This allows for local expansion and adjustment of the expansile fluid region 196 when needed.

[0028] A voltage is applied by the power source to move the first electrode 106 and the second electrode 108 toward each other. In some embodiments, a voltage of up to 10 kV can be provided by the power source to induce an electric field through the dielectric fluid 198. The resulting attractive force between the first electrode 106 and the second electrode 108 pushes the dielectric fluid 198 into the expansion fluid region 196. Pressure from the dielectric fluid 198 within the expansion fluid region 196 causes the first film layer 122 and the first electrical insulator layer 110 to deform in a first axial direction along the central axis C of the first electrode 106 and the second film layer 124 and the second electrical insulator layer 112 to deform in an opposite second axial direction along the central axis C of the second electrode 108. Once the voltage supplied to the first electrode 106 and the second electrode 108 is interrupted, the first electrode 106 and the second electrode 108 return to their initial non-parallel position in the unactuated state.

[0029] It should be appreciated that the embodiments disclosed herein, specifically the tab portions 132, 154 with the interconnecting bridge portions 174, 176, provide many improvements over actuators such as HASEL actuators that do not include the tab portions 132, 154. An embodiment of an artificial muscle 100 that includes two tab portion pairs 132, 154, respectively, on each of the first electrode 106 and the second electrode 108, reduces the overall mass and thickness of the artificial muscle 100, reduces the amount of voltage required during actuation, and reduces the total volume of the artificial muscle 100 without reducing the amount of resulting force after actuation, compared to known HASEL actuators that include toroidal shaped electrodes with uniform radially extending widths. More specifically, the tab portions 132, 154 of the artificial muscle 100 provide a fastener-like front surface that results in increased actuation output by providing localized, uniform hydraulic actuation of the artificial muscle 100, compared to HASEL actuators that include toroidal shaped electrodes. Specifically, one tab portion pair 132, 154 provides twice the actuator force per unit volume compared to a toroidal HASEL actuator, while two tab portion pairs 132, 154 provide four times the actuator force per unit volume. Bridge portions 174, 176 interconnecting tab portions 132, 154 similarly limit buckling of tab portions 132, 154 by maintaining the distance between adjacent tab portions during actuation. Because bridge portions 174, 176 are integrally formed with tab portions 132, 154, bridge portions 174, 176 also prevent leakage between tab portions 132, 154 by eliminating attachment points that increase the risk of fracture.

[0030] In operation, when the artificial muscle 100 is actuated, the expansion of the expansive fluid region 196 expands to approximately one cubic centimeter (cm) of actuator volume. 3 ) or more than 3 Newton-millimeters (N·mm) per unit force, e.g. 4N·mm / cm 3 More than 5N mm / cm 3 More than 6N mm / cm 3 More than 7N mm / cm 3 More than 8N mm / cm 3In one embodiment, when the artificial muscle 100 is actuated with a voltage of 9.5 kilovolts (kV), the artificial muscle 100 provides a resultant force of 5 N. In another embodiment, when the artificial muscle 100 is actuated with a voltage of 10 kV, the artificial muscle 100 provides a 440% strain under a load of 500 grams.

[0031] Additionally, the size of the first electrode 106 and the second electrode 108 is proportional to the amount of displacement of the dielectric fluid 198. Thus, if a greater displacement is desired within the expansion fluid region 196, the size of the electrode pair 104 is increased in relation to the size of the expansion fluid region 196. It should be appreciated that the size of the expansion fluid region 196 is defined by the central openings 146, 168 in the first electrode 106 and the second electrode 108. Thus, the degree of displacement within the expansion fluid region 196 may alternatively or additionally be controlled by increasing or decreasing the size of the central openings 146, 168.

[0032] As shown in Figures 5 and 6, another embodiment of an artificial muscle 200 is illustrated. The artificial muscle 200 is substantially similar to the artificial muscle 100. Thus, like structures are labeled with like reference numbers. However, as shown, the first electrode 106 does not include a central opening. Thus, only the second electrode 108 includes a central opening 168 therein. As shown in Figure 5, the artificial muscle 200 is in an unactuated state, the first electrode 106 is planar, and the second electrode 108 is convex relative to the first electrode 106. In the unactuated state, the expansion fluid region 196 has a first height H3. In the actuated state, shown in Figure 6, the expansion fluid region 196 has a second height H4 that is greater than the first height H3. It should be appreciated that by providing the central opening 168 only in the second electrode 108 as opposed to in both the first electrode 106 and the second electrode 108, a full deformation can be created on one side of the artificial muscle 200. Furthermore, because the total deformation occurs on only one side of the artificial muscle 200, the second height H4 of the expansion fluid region 196 of the artificial muscle 200 extends farther from the longitudinal axis perpendicular to the central axis C of the artificial muscle 200 than the second height H2 of the expansion fluid region 196 of the artificial muscle 100, all other dimensions, orientation, and volume of the dielectric fluid being the same.

[0033] 7, an artificial muscle assembly 300 is shown that includes multiple artificial muscles, such as artificial muscle 100. However, multiple artificial muscles 200 can be arranged in a stacked arrangement as well. Each artificial muscle 100 can be structurally identical and arranged in a stack such that the expansion fluid region 196 of each artificial muscle 100 overlaps with the expansion fluid region 196 of an adjacent artificial muscle 100. The terminals 130, 152 of each artificial muscle 100 are electrically connected to each other such that the artificial muscles 100 can be simultaneously actuated between an unactuated state and an actuated state. By arranging the artificial muscles 100 in a stacked configuration, the total deformation of the artificial muscle assembly 300 is the sum of the deformations within the expansion fluid region 196 of each artificial muscle 100. Thus, the degree of deformation resulting from the artificial muscle assembly 300 is greater than would be provided by the artificial muscles 100 alone.

[0034] 8, an actuation system 400 can be provided for operating an artificial muscle or artificial muscle assembly, such as artificial muscle 100, 200 or artificial muscle assembly 300, between an unactuated state and an actuated state. Thus, the actuation system 400 can include a controller 402, a manipulation device 404, a power source 406, and a communication path 408. Various components of the actuation system 400 will now be described.

[0035] The controller 402 includes a non-transitory electronic memory 412 and a processor 410, with the various components communicatively coupled. In some embodiments, the processor 410 and the non-transitory electronic memory 412 and / or other components are contained within a single device. In other embodiments, the processor 410 and the non-transitory electronic memory 412 and / or other components may be distributed among multiple communicatively coupled devices. The controller 402 includes a non-transitory electronic memory 412 that stores a machine-readable instruction set. The processor 410 executes the machine-readable instructions stored in the non-transitory electronic memory 412. The non-transitory electronic memory 412 may include RAM, ROM, flash memory, a hard drive, or any device capable of storing machine-readable instructions such that the processor 410 can access the machine-readable instructions. Thus, the operating system 400 described herein may be implemented as a hardware element pre-programmed in any conventional computer programming language, or as a combination of hardware and software components. The non-transitory electronic memory 412 may be implemented as one memory module or multiple memory modules.

[0036] In some embodiments, the non-transitory electronic memory 412 includes instructions for carrying out the functions of the actuation system 400. The instructions may include instructions for operating the artificial muscles 100, 200 or the artificial muscle assembly 300 based on user commands.

[0037] The processor 410 may be any device capable of executing machine-readable instructions. For example, the processor 410 may be an integrated circuit, a microchip, a computer, or any other computing device. The non-transitory electronic memory 412 and the processor 410 are coupled to a communication path 408 that provides signal interconnectivity between various components and / or modules of the operating system 400. Thus, the communication path 408 may communicatively couple any number of processors to each other and may enable the modules coupled to the communication path 408 to operate within a distributed computing environment. Specifically, each of the modules may operate as a node that can transmit and / or receive data. As used herein, the term "communicatively coupled" means that the coupled components have the ability to exchange data signals with each other, e.g., electrical signals over a conductive medium, electromagnetic signals over air, and optical signals over optical waveguides.

[0038] As depicted generally in Figure 8, a communication path 408 communicatively couples a processor 410 and non-transitory electronic memory 412 of the controller 402 with a number of other components of the actuation system 400. For example, the actuation system 400 depicted in Figure 8 includes a processor 410 and non-transitory electronic memory 412 communicatively coupled to a manipulation device 404 and a power source 406.

[0039] The manipulation device 404 allows a user to control the operation of the artificial muscle 100, 200 or the artificial muscle assembly 300. In some embodiments, the manipulation device 404 can be a switch, a toggle, a button, or any combination of control mechanisms to provide manipulation by a user. As a non-limiting example, a user can actuate the artificial muscle 100, 200 or the artificial muscle assembly 300 to an activated state by actuating a control mechanism of the manipulation device 404 to a first position. While in the first position, the artificial muscle 100, 200 or the artificial muscle assembly 300 remains in the activated state. A user can switch the artificial muscle 100, 200 or the artificial muscle assembly 300 to an inactivated state by actuating a control mechanism of the manipulation device 404 out of the first position to a second position.

[0040] The manipulation device 404 is coupled to a communication path 408 such that the communication path 408 communicatively couples the manipulation device 404 to other modules of the actuation system 400. The manipulation device 404 can provide a user interface for receiving user instructions regarding a particular operational configuration of the artificial muscles 100, 200 or the artificial muscle assembly 300. Additionally, the user instructions can include instructions to operate the artificial muscles 100, 200 or the artificial muscle assembly 300 only under certain conditions.

[0041] The power source 406 (e.g., a battery) provides power to the artificial muscles 100, 200 or the artificial muscle assembly 300. In some embodiments, the power source 406 is a rechargeable DC power source. It should be understood that the power source 406 can be a single power source or a battery for providing power to the artificial muscles 100, 200 or the artificial muscle assembly 300. To provide power to the artificial muscles 100, 200 or the artificial muscle assembly 300 via the power source 406, a power adapter (not shown) can be included and electrically coupled via a wiring harness or the like.

[0042] In some embodiments, the actuation system 400 also includes a display device 414. The display device 414 is coupled to the communication path 408 such that the communication path 408 communicatively couples the display device 414 to other modules of the actuation system 400. The display device 414 may output notifications in response to indications of a state of actuation of the artificial muscles 100, 200 or the artificial muscle assembly 300 or a change in a state of actuation of the artificial muscles 100, 200 or the artificial muscle assembly 300. Furthermore, in addition to providing optical information, the display device 414 may be a touch screen that detects the presence and location of tactile input on or adjacent to a surface of the display device 414. Thus, the display device 414 may include the manipulation device 404 and receive mechanical input directly at the time the display device 414 provides an optical output.

[0043] In some embodiments, the actuation system 400 includes network interface hardware 416 that communicatively couples the actuation system 400 to a mobile device 418 via a network 420. The mobile device 418 may include, without limitation, a smart phone, a tablet, a personal media player, or any other electronic device that includes wireless communication functionality. It should be appreciated that if a mobile device 418 is provided, it may serve to provide user commands to the controller 402 instead of the manipulation device 404. In this manner, a user may be able to control or program to control the artificial muscle 100, 200 or artificial muscle assembly 300 without utilizing the control mechanisms of the manipulation device 404. Thus, the artificial muscle 100, 200 or artificial muscle assembly 300 can be remotely controlled via the mobile device 418 that wirelessly communicates with the controller 402 over the network 420.

[0044] From the above, it should be appreciated that artificial muscles are defined herein for expanding or deforming the surface of an object by selectively activating the artificial muscles to raise and lower regions thereof, thereby providing a low-profile expansion member that can be operated on demand.

[0045] The terms "substantially" and "about" may be used herein to express the inherent degree of uncertainty that may result from any quantitative comparison, value, measurement or other expression. These terms are also used herein to express the degree to which a quantitative expression may vary from the stated basis without resulting in a change in the basic functionality of the subject matter at issue.

[0046] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be used in combination. It is therefore intended that the appended claims cover all such changes and modifications that fall within the scope of the claimed subject matter.

Claims

1. a housing containing an electrode region and an expandable fluid region; an electrode pair positioned within the electrode region of the housing, the electrode pair including a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing; the first electrode and the second electrode each include two or more tab portions and two or more bridge portions; each of the two or more bridge portions interconnecting adjacent tab portions; at least one of the first electrode and the second electrode includes a central opening positioned between the two or more tab portions and surrounding the expandable fluid region. An electrode pair; a dielectric fluid contained within the housing; An artificial muscle comprising: the electrode pair is actuable between the unactuated state and the actuated state such that actuation from the unactuated state to the actuated state induces the dielectric fluid into the expansion fluid region.

2. 2. The artificial muscle of claim 1 , wherein the housing includes a first film layer and a second film layer partially sealed to one another to define a sealed portion of the housing, the housing further includes an unsealed portion surrounded by the sealed portion, the electrode region and the expansion fluid region of the housing being disposed within the unsealed portion.

3. The artificial muscle of claim 2, wherein the first film layer and the second film layer are each a biaxially oriented polypropylene film.

4. 2. The artificial muscle of claim 1, further comprising: a first electrical insulator layer secured to an inner surface of the first electrode opposite the first surface of the housing; and a second electrical insulator layer secured to an inner surface of the second electrode opposite the second surface of the housing, the first electrical insulator layer and the second electrical insulator layer each including an adhesive surface and an opposing non-sealable surface.

5. 10. The artificial muscle of claim 1 , wherein the first electrode and the second electrode are each an aluminum-coated polyester electrode.

6. 2. The artificial muscle of claim 1 , wherein the first electrode and the second electrode each include two pairs of tab portions and two pairs of bridge portions, each bridge portion interconnecting an adjacent pair of tab portions, and each tab portion diametrically opposed to an opposing tab portion.

7. 2. The artificial muscle of claim 1 , wherein the two or more tab portions each have a tab length and the two or more bridge portions each have a bridge length extending radially from the central opening, the bridge lengths being between 20% and 50% of the tab lengths.

8. 2. The artificial muscle of claim 1 , wherein the first electrode and the second electrode each include a central opening positioned between the two or more tab portions and surrounding the expansive fluid region, the central openings being coaxially aligned with one another.

9. when the electrode pair is in the unactuated state, the first electrode and the second electrode are not parallel to one another; when the electrode pair is in the actuated state, the first electrode and the second electrode are parallel to one another, such that the first electrode and the second electrode are configured to close in a fastener-like manner toward the central opening and toward one another when actuated from the unactuated state to the actuated state. The artificial muscle according to claim 1.

10. An artificial muscle assembly having a plurality of artificial muscles, Each artificial muscle is a housing containing an electrode region and an expandable fluid region; an electrode pair positioned within the electrode region of the housing, the electrode pair including a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing; the first electrode and the second electrode each include two or more tab portions and two or more bridge portions; each of the two or more bridge portions interconnecting adjacent tab portions; at least one of the first electrode and the second electrode includes a central opening positioned between the two or more tab portions and surrounding the expandable fluid region. An electrode pair; a dielectric fluid contained within the housing; Including, the plurality of artificial muscles are arranged in a stack such that the expansive fluid regions of each artificial muscle are coaxially aligned with one another; the electrode pair is actuable between an unactuated state and an actuated state such that actuation from the unactuated state to the actuated state induces the dielectric fluid into the expansion fluid region. Artificial muscle assembly.

11. 11. The artificial muscle assembly of claim 10, wherein the plurality of artificial muscles are electrically coupled to one another and configured to simultaneously operate between an unactuated state and an actuated state.

12. a first layer of electrical insulation secured to an inner surface of the first electrode opposite the first surface of the housing, and a second layer of electrical insulation secured to an inner surface of the second electrode opposite the second surface of the housing; 11. The artificial muscle assembly of claim 10, wherein the first electrical insulator layer and the second electrical insulator layer each include an adhesive surface and an opposing non-sealable surface.

13. 11. The artificial muscle of claim 10, wherein the first electrode and the second electrode each include two pairs of tab portions and two pairs of bridge portions, each bridge portion interconnecting adjacent pairs of tab portions, and each tab portion diametrically opposed to an opposing tab portion.

14. 11. The artificial muscle of claim 10, wherein the first electrode and the second electrode each include a central opening positioned between the two or more tab portions and surrounding the expansive fluid region, the central openings being coaxially aligned with one another.

15. when the electrode pair is in the unactuated state, the first electrode and the second electrode are not parallel to one another; when the electrode pair is in the actuated state, the first electrode and the second electrode are parallel to one another, such that the first electrode and the second electrode are configured to close in a fastener-like manner toward the central opening and toward one another when actuated from the unactuated state to the actuated state. The artificial muscle according to claim 10.

16. 1. A method of actuating an artificial muscle assembly, comprising: generating a voltage with a power source electrically coupled to an electrode pair of an artificial muscle, the artificial muscle including a housing having an electrode region and an expandable fluid region; the electrode pair is positioned within the electrode region of the housing; the electrode pair includes a first electrode secured to a first surface of the housing and a second electrode secured to an opposing second surface of the housing; the first electrode and the second electrode each include two or more tab portions and two or more bridge portions; each of the two or more bridge portions interconnecting adjacent tab portions; at least one of the first electrode and the second electrode includes a central opening positioned between the two or more tab portions and surrounding the expansion fluid region; A dielectric fluid is contained within the housing. And, actuating the electrode pair from an unactuated state to an actuated state such that the voltage is applied to the electrode pair of the artificial muscle, thereby inducing the dielectric fluid into the expansion fluid region of the housing and expanding the expansion fluid region; A method comprising:

17. 17. The method of claim 16, wherein the housing comprises a first film layer and a second film layer, the first film layer and the second film layer being partially heat sealed to one another to define a sealed portion of the housing, the housing further comprising an unsealed portion surrounded by the sealed portion, the electrode region and the expandable fluid region of the housing being disposed within the unsealed portion.

18. 17. The method of claim 16, wherein a controller is communicatively coupled to the electrode pair, the controller inducing a voltage from the power source across the first electrode and the second electrode to actuate the artificial muscle from the unactuated state to the actuated state.

19. 17. The method of claim 16, wherein the artificial muscle is one of a plurality of artificial muscles arranged in a stack such that the expansive fluid domains of each artificial muscle are coaxially aligned with one another.

20. By expanding the expansion fluid region, the actuator volume can be increased by 1 cm 3 17. The method of claim 16, wherein a force of greater than 4 N.mm per

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