Artificial muscle including an electrode pair and artificial muscle assembly including the artificial muscle

Abstract

An artificial muscle comprises: a housing having an electrode region and an expandable fluid region; an electrode pair positioned in the electrode region, the electrode pair comprising a first electrode fixed to a first surface of the housing and a second electrode fixed to a second surface of the housing. The first electrode and the second electrode each have two or more tab portions and two or more bridging portions. Each of the two or more bridging portions interconnects adjacent tab portions, and at least one of the first and second electrodes comprises a central opening positioned between the two or more tab portions and surrounding the expandable fluid region. A dielectric fluid is contained within the housing, and the electrode pair is actuatable between a non-actuated state and an actuated state, such that actuation from the non-actuated state to the actuated state directs the dielectric fluid into the expandable fluid region.

Description

Technical Field

[0001] The present description relates generally to apparatus and methods for focused enlargement on at least one surface of a device, and more particularly to apparatus and methods for directing fluid to enlarge a device using an electrode pair. Background Art

[0002] Current robotics typically relies on rigid components such as servo motors to perform tasks in a structured environment. This rigidity has limitations in many robotic applications, at least in part due to the weight-to-power ratio of servo motors and other rigid robotic devices. The field of soft robotics improves these limitations by using artificial muscles and other soft actuators. Artificial muscles attempt to mimic the versatility, performance, and reliability of biological muscles. Some artificial muscles rely on fluid actuators, but fluid actuators require a supply of pressurized gas or liquid, and fluid transport must be carried out through channels and piping systems, thereby limiting the speed and efficiency of the artificial muscles. Other artificial muscles use heat-activated polymer fibers, but these polymer fibers are difficult to control and have low operating efficiency.

[0003] A specific artificial muscle design is described in a paper by E. Acome, SK Mitchell, TG Morrissey, M B Emmett, C. Benjamin, M. King, M. Radakovitz, and C. Keplinger titled "Hydraulically amplified self-healing electrostatic actuators with muscle-like performance" (Science 05 Jan 2018: Vol. 359, Issue 6371, pp. 61-65). These hydraulically amplified self-healing electrostatic (HASEL) actuators use electrostatic and hydraulic forces to achieve multiple actuation modes. However, HASEL actuator artificial muscles have limited actuator power per unit volume.

[0004] Therefore, there is a need for an improved artificial muscle having increased actuator power per unit volume. Summary of the Invention

[0005] In one embodiment, an artificial muscle comprises: a housing having an electrode region and an expandable fluid region; and an electrode pair positioned in the electrode region of the housing, the electrode pair comprising 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 have 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 comprises a central opening positioned between the two or more tab portions and surrounding the expandable fluid region. A dielectric fluid is contained within the housing and the electrode pair is actuatable between an unactuated state and an actuated state such that actuation from the unactuated state to the actuated state directs the dielectric fluid into the expandable fluid region.

[0006] In another embodiment, an artificial muscle assembly includes: a plurality of artificial muscles, each having a housing having an electrode region and an expandable fluid region; and an electrode pair positioned in the electrode region of the housing, the electrode pair comprising 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 comprise 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 comprises a central opening positioned between the two or more tab portions and surrounding the expandable fluid region. A dielectric fluid is contained within the housing, the plurality of artificial muscles are arranged in a stack such that the expandable fluid region of each artificial muscle is coaxially aligned with one another; and the electrode pair is actuatable between an unactuated state and an actuated state, such that actuation from the unactuated state to the actuated state directs the dielectric fluid into the expandable fluid region.

[0007] In yet another embodiment, a method for actuating an artificial muscle assembly includes generating a voltage using a power source electrically coupled to an electrode pair of an artificial muscle, the artificial muscle having a housing with an electrode region and an expandable fluid region. The electrode pair is positioned in 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 interconnects adjacent tab portions, and 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. A dielectric fluid is contained within the housing. The method further includes applying the voltage to the electrode pair of the artificial muscle, thereby actuating the electrode pair from an unactivated state and an activated state, such that the dielectric fluid is directed into the expandable fluid region of the housing and expands the expandable fluid region.

[0008] These and additional features provided by the embodiments described herein will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The embodiments illustrated 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 exemplary illustrative embodiments can be understood when read in conjunction with the following drawings, in which like structures are represented by like reference numerals and in which:

[0010] Figure 1 schematically depicts an exploded view of an example illustrative artificial muscle according to one or more embodiments shown and described herein;

[0011] Figure 2 Schematically depict Figure 1 , a top view of an artificial muscle according to one or more embodiments shown and described herein;

[0012] Figure 3 Schematically depict Figure 1 An artificial muscle in a non-actuated state according to one or more embodiments shown and described herein is moved along Figure 2 A cross-sectional view taken along line 3-3;

[0013] Figure 4 Schematically depict Figure 3 a cross-sectional view of an artificial muscle in an actuated state according to one or more embodiments shown and described herein;

[0014] Figure 5 schematically depicts a cross-sectional view of an example illustrative artificial muscle in a non-actuated state according to one or more embodiments shown and described herein;

[0015] Figure 6 Schematically depict Figure 5 a cross-sectional view of an artificial muscle in an actuated state according to one or more embodiments shown and described herein;

[0016] Figure 7 Schematically depicts an artificial muscle assembly according to one or more embodiments shown and described herein, the artificial muscle assembly comprising Figure 1 multiple artificial muscles; and

[0017] Figure 8 Schematically depicts a method for operating a Figure 1 Actuation system of artificial muscle. DETAILED DESCRIPTION

[0018] Embodiments described herein relate to artificial muscles and artificial muscle assemblies comprising multiple artificial muscles. The artificial muscles described herein are actuatable to selectively raise and lower a region of the artificial muscle to provide selective, on-demand expansion of an expandable fluid region. The artificial muscle comprises a housing and an electrode pair. A dielectric fluid is contained within the housing, and the housing comprises an electrode region and an expandable fluid region, wherein the electrode pair is positioned within the electrode region. The electrode pair comprises 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 actuatable between an unactuated state and an actuated state, such that actuation from the unactuated state to the actuated state directs the dielectric fluid into the expandable fluid region. This causes the expandable fluid region to expand, thereby raising a portion of the artificial muscle on demand. Furthermore, each of the first and second electrodes comprises 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 comprises a central opening positioned between the tab portions and surrounding the expandable fluid region. The design of the tab and bridge portions of the electrode pairs facilitates a zipper-like actuation motion to increase the force per unit volume that can be achieved by actuating the artificial muscle. Various embodiments of artificial muscles and their operation are described in more detail herein. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar components.

[0019] Now refer to Figure 1 and 2 , shows an artificial muscle 100. Artificial muscle 100 includes: a housing 102; an electrode pair 104 affixed to opposing surfaces of housing 102, the electrode pair 104 including a first electrode 106 and a second electrode 108; a first electrical insulator layer 110 affixed to first electrode 106; and a second electrical insulator layer 112 affixed to second electrode 108. In some embodiments, housing 102 is a unitary, monolithic layer comprising a pair of opposing inner surfaces, such as first and second inner surfaces 114 and 116, and a pair of opposing outer surfaces, such as first and second outer surfaces 118 and 120. In some embodiments, first and second inner surfaces 114 and 116 of housing 102 are heat-sealable. In other embodiments, housing 102 may be a pair of separately manufactured film layers, such as first and second film layers 122 and 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 .

[0020] Throughout the following description, reference may be made to the housing 102 comprising the first film layer 122 and the second film layer 124, as opposed to a unitary housing. It should be understood that either arrangement is contemplated. In certain embodiments, the first film layer 122 and the second film layer 124 generally comprise the same structure and composition. For example, in certain embodiments, the first film layer 122 and the second film layer 124 each comprise biaxially oriented polypropylene.

[0021] 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 certain embodiments, the first electrode 106 and the second electrode 108 are each aluminum-coated polyester, for example, In addition, 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 the purposes discussed herein, either the first electrode 106 or the second electrode 108 can be positively charged, as long as the other of the first electrode 106 and the second electrode 108 of the artificial muscle 100 is negatively charged.

[0022] The first electrode 106 has a membrane-facing surface 126 and an opposing inner surface 128. The first electrode 106 is positioned against the first membrane layer 122, specifically the first inner surface 114 of the first membrane layer 122. In addition, the first electrode 106 includes a first terminal 130 that extends from the first electrode 106 beyond the edge of the first membrane layer 122 so that the first terminal 130 can be connected to a power source to actuate the first electrode 106. Specifically, as Figure 8, the terminals are coupled directly or in series to a power source and a controller of the actuation system 400. Similarly, the second electrode 108 has a membrane-facing surface 148 and an opposing inner surface 150. The second electrode 108 is positioned against the second membrane layer 124, specifically the second inner surface 116 of the second membrane layer 124. The second electrode 108 includes a second terminal 152 that extends from the second electrode 108 beyond the edge of the second membrane layer 124 so that the second terminal 152 can be connected to a power source and a controller of the actuation system 400 to actuate the second electrode 108.

[0023] 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 adjacent tab portions 132, thereby interconnecting the adjacent tab portions 132. Each tab portion 132 has a first end 134 that extends radially relative to the central axis C of the first electrode 106 to an opposite second end 136 of the tab portion 132, wherein 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 relative to the central axis C of the first electrode 106 to an opposite second end 144 of the bridge portion 140, thereby defining another portion of the outer periphery 138 of the first electrode 106. Each tab portion 132 has a tab length L1, and each bridge portion 140 has a bridge length L2 that extends in a radial direction relative to the central axis C of the first electrode 106. Tab length L1 is the distance from first end 134 to second end 136 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 certain embodiments, bridge length L2 is 20% to 50% of tab length L1, such as 30% to 40% of tab length L1.

[0024] In some embodiments, two or more tab portions 132 are arranged in a pair or more of tab portions 132. Each tab portion 132 includes two tab portions 132 arranged diametrically opposite each other. 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. In some embodiments, as Figure 1 and 2As shown in FIG, the first electrode 106 includes four tab portions 132 and four bridge portions 140 that interconnect adjacent tab portions 132. In this embodiment, the four tab portions 132 are arranged as two pairs of tab portions 132 that are diametrically opposed to each other. In addition, as shown in the figure, the first terminal 130 extends from the second end 136 of one of the tab portions 132 and is formed integrally with the second end 136.

[0025] Similar to the first electrode 106, the second electrode 108 includes at least one pair of tab portions 154 and two or more bridge portions 162. Each bridge portion 162 is positioned between adjacent tab portions 154, thereby interconnecting the adjacent tab portions 154. Each tab portion 154 has a first end 156 that extends radially relative to the central axis C of the second electrode 108 to an opposite second end 158 of the tab portion 154, wherein the second end 158 defines a portion of the outer periphery 160 of the second electrode 108. Because the first and second electrodes 106, 108 are coaxial with each other, the central axis C of the first and second electrodes 106, 108 are the same. Each bridge portion 162 has a first end 164 that extends radially relative to the central axis C of the second electrode to an opposite second end 166 of the bridge portion 162, thereby defining another portion of the outer periphery 160 of the second electrode 108. Each tab portion 154 has a tab length L3, and each bridge portion 162 has a bridge length L4 extending in a radial direction relative to the central axis C of the second electrode 108. Tab length L3 is the distance from the first end 156 to the second end 158 of the tab portion 154, and bridge length L4 is the distance from the first end 164 to the second end 166 of the bridge portion 162. Tab length L3 is longer than bridge length L4 of each bridge portion 162. In some embodiments, bridge length L4 is 20% to 50% of tab length L3, such as 30% to 40% of tab length L3.

[0026] In some embodiments, two or more tab portions 154 are arranged in a pair or more of tab portions 154. Each tab portion 154 includes two tab portions 154 arranged diametrically opposite each other. In some embodiments, the second electrode 108 may include only two tab portions 154 positioned on opposite sides or ends of the first electrode 106. In some embodiments, as Figure 1 and 2As shown in FIG, the second electrode 108 includes four tab portions 154 and four bridge portions 162 that interconnect adjacent tab portions 154. In this embodiment, the four tab portions 154 are arranged as two pairs of tab portions 154 that are diametrically opposed to each other. In addition, as shown in the figure, the second terminal 152 extends from the second end 158 of one of the tab portions 154 and is formed integrally with the second end 158.

[0027] Now refer to Figure 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. Figure 3 and 4 In the embodiment, the first electrode 106 has a central opening 146. However, it should be understood that when a central opening is provided in the second electrode 108, the first electrode 106 does not need to include the central opening 146. Figure 5 and 6 Alternatively, when the central opening 146 is provided in the first electrode 106, the second electrode 108 does not need to include a central opening. Still referring to Figure 1-6 , the first and second electrical insulator layers 110, 112 have geometries corresponding to the first and second electrodes 106, 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. Further, the first and second electrical insulator layers 110, 112 each have an outer perimeter 178, 180 that, when positioned over the outer perimeter 138, 160 of the first and second electrodes 106, 108, respectively, correspond to the outer perimeter 138, 160 of the first and second electrodes 106, 108, respectively.

[0028] It should be understood that, in some embodiments, first electrical insulator layer 110 and second electrical insulator layer 112 generally comprise the same structure and composition. Thus, in some embodiments, first electrical insulator layer 110 and second electrical insulator layer 112 each comprise adhesive surfaces 182, 184, respectively, and opposing non-sealable surfaces 186, 188. Thus, in some embodiments, first electrical insulator layer 110 and second electrical insulator layer 112 are each polymeric strips adhered to inner surface 128 of first electrode 106 and inner surface 150 of second electrode 108, respectively.

[0029] Now refer to Figure 2-6, shows the artificial muscle 100 in an assembled form, wherein the first terminal 130 of the first electrode 106 and the second terminal 152 of the second electrode 108 extend beyond the outer periphery of the housing 102, i.e., the first membrane layer 122 and the second membrane layer 124. Figure 2 , the second electrode 108 is stacked on top of the first electrode 106, and therefore, the first electrode 106, the first film layer 122, and the second film layer 124 are not shown. In its assembled form, 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. The first film layer 122 is partially sealed to the second film layer 124 at an area surrounding the outer periphery 138 of the first electrode 106 and the outer periphery 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 surrounding the first electrode 106 and the second electrode 108. The first film layer 122 and the second film layer 124 can be sealed in any suitable manner, such as using an adhesive, heat sealing, or the like.

[0030] 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 membrane layer 122 from sealing to the second membrane layer 124, thereby forming an unsealed portion 192. The unsealed portion 192 of the housing 102 includes an electrode region 194 in which the electrode pair 104 is disposed and an expandable fluid region 196 surrounded by the electrode region 194. The central openings 146, 168 of the first and second electrodes 106, 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 can be cut to conform to the geometry of the electrode pair 104 and to reduce the size of the artificial muscle 100, that is, the size of the sealed portion 190.

[0031] 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 conducting and, as such, has low electrical conductivity. Some non-limiting exemplary dielectric fluids include perfluorocarbons, transformer oil, and deionized water. It should be understood 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.

[0032] Now refer to Figure 3 and 4 , the artificial muscle 100 can be actuated between a non-actuated state and an actuated state. In the non-actuated state, as Figure 3 As shown in FIG, the first electrode 106 and the second electrode 108 are partially spaced apart from each other near their central openings 146, 168 and the first ends 134, 156 of the tab portions 132, 154. Because the housing 102 is sealed at the outer periphery 138, 160 of the first electrode 106 and the outer periphery 160 of the second electrode 108, the second ends 136, 158 of the tab portions 132, 154 are held in position relative to each other. In the actuated state, as shown Figure 4 , first and second electrodes 106, 108 are in contact and oriented parallel to each other to force dielectric fluid 198 into expandable fluid region 196. This causes dielectric fluid 198 to flow through central openings 146, 168 of first and second electrodes 106, 108 and expand expandable fluid region 196.

[0033] Now refer to Figure 3 , shows the artificial muscle 100 in a non-actuated state. The electrode pair 104 is disposed 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 the expandable fluid region 196. In the non-actuated state, the first electrode 106 and the second electrode 108 are partially spaced apart from each other and are not parallel to each other. Because the first membrane layer 122 is sealed to the second membrane layer 124 around the electrode pair 104, the second ends 136, 158 of the tab portions 132, 154 contact each other. Thus, a dielectric fluid 198 is provided between the first electrode 106 and the second electrode 108, thereby separating the first ends 134, 156 of the tab portions 132, 154 proximate to the expandable 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. This allows the electrode pair 104 to zip toward the expandable fluid region 196 when actuated. In some embodiments, the first electrode 106 and the second electrode 108 can be flexible. Thus, as Figure 3 , first and second electrodes 106, 108 are convexly shaped such that second ends 136, 158 of their tab portions 132, 154 can remain proximate to each other but spaced apart proximate central openings 146, 168. In the unactuated state, expandable fluid region 196 has a first height H1.

[0034] When activated, Figure 4As shown in FIG, the first and second electrodes 106, 108 are zip-connected from the second ends 144, 158 of their tab portions 132, 154 toward each other, thereby pushing dielectric fluid 198 into the expandable fluid region 196. As shown, when in the actuated state, the first and second electrodes 106, 108 are parallel to each other. In the actuated state, dielectric fluid 198 flows into the expandable fluid region 196, causing it to expand. Thus, the first and second membrane layers 122, 124 expand in opposite directions. In the actuated state, the expandable fluid region 196 has a second height H2 that is greater than the first height H1 of the expandable fluid region 196 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 and actuated states. This allows for partial expansion of the expandable fluid region 196 and allows for adjustments if necessary.

[0035] To move the first electrode 106 and the second electrode 108 toward each other, a voltage is applied by a power supply. In certain embodiments, a voltage of up to 10 kV can be supplied from the power supply 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 expandable fluid region 196. The pressure from the dielectric fluid 198 within the expandable fluid region 196 causes the first membrane 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 causes the second membrane 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 is removed from the first and second electrodes 106, 108, the first and second electrodes 106, 108 return to their original, non-parallel positions in the unactuated state.

[0036] It should be appreciated that the embodiments of the present invention disclosed herein, and in particular the tab portions 132, 154 having interconnected bridge portions 174, 176, provide numerous improvements over actuators (such as HASEL actuators) that do not include tab portions 132, 154. Compared to known HASEL actuators that include donut-shaped electrodes having uniform radially extending widths, embodiments of the artificial muscle 100 that include two tab portions 132, 154 on each of the first electrode 106 and the second electrode 108, respectively, reduce the overall mass and thickness of the artificial muscle 100, reduce the amount of voltage required during actuation, and reduce the overall volume of the artificial muscle 100 without reducing the magnitude of the resultant force after actuation. More specifically, the tab portions 132, 154 of the artificial muscle 100 provide a zippered front portion that increases actuation power by providing localized and uniform hydraulic actuation to the artificial muscle 100, compared to HASEL actuators containing donut-shaped electrodes. Specifically, compared to a donut-shaped HASEL actuator, one pair of tab portions 132, 154 provides twice the amount of actuator power per unit volume, while two pairs of tab portions 132, 154 provide four times the amount of actuator power per unit volume. The bridge portions 174, 176 interconnecting the tab portions 132, 154 also limit buckling of the tab portions 132, 154 by maintaining the distance between adjacent tab portions 132, 154 during actuation. Because the bridge portions 174 , 176 are integrally formed with the tab portions 132 , 154 , the bridge portions 174 , 176 also prevent leakage between the tab portions 132 , 154 by eliminating attachment locations that provide an increased risk of rupture.

[0037] In operation, when the artificial muscle 100 is actuated, the expansion of the expandable fluid region 196 produces a flow of 100 psi per cubic centimeter (cm 3 ) actuator volume of 3 Newton-millimeter (N.mm) or greater, such as 4 N.mm per cubic centimeter or greater, 5 N.mm per cubic centimeter or greater, 6 N.mm per cubic centimeter or greater, 7 N.mm per cubic centimeter or greater, 8 N.mm per cubic centimeter or greater, or the like. In one example, when the artificial muscle 100 is actuated by a voltage of 9.5 kilovolts (kV), the artificial muscle 100 provides a net force of 5 N. In another example, when the artificial muscle 100 is actuated by a voltage of 10 kV, the artificial muscle 100 provides a strain of 440% under a load of 500 grams.

[0038] Furthermore, the size of the first and second electrodes 106, 108 is proportional to the amount of displacement of the dielectric fluid 198. Thus, when a greater displacement within the expandable fluid region 196 is desired, the size of the electrode pair 104 is increased relative to the size of the expandable fluid region 196. It should be understood that the size of the expandable fluid region 196 is defined by the central openings 146, 168 in the first and second electrodes 106, 108. Thus, the degree of displacement within the expandable fluid region 196 can alternatively or additionally be controlled by increasing or decreasing the size of the central openings 146, 168.

[0039] like Figure 5 and 6 As shown in FIG, another embodiment of an artificial muscle 200 is shown. The artificial muscle 200 is substantially similar to the artificial muscle 100. As such, like structures are denoted by like reference numerals. However, as shown, the first electrode 106 does not include a central opening. Therefore, only the second electrode 108 includes a central opening 168 formed therein. Figure 5 As shown in FIG, the artificial muscle 200 is in a non-actuated state, wherein the first electrode 106 is flat and the second electrode 108 is convex relative to the first electrode 106. In the non-actuated state, the expandable fluid region 196 has a first height H3. In the actuated state, as shown in FIG. Figure 6 , the expandable fluid region 196 has a second height H4 that is greater than the first height H3. It should be understood that by providing the central opening 168 only in the second electrode 108, as opposed to providing a central opening in both the first electrode 106 and the second electrode 108, the total deformation can be generated on one side of the artificial muscle 200. In addition, because the total deformation is generated on only one side of the artificial muscle 200, when all other dimensions, orientations, and volumes of dielectric fluid are the same, the second height H4 of the expandable fluid region 196 of the artificial muscle 200 extends further from the longitudinal axis perpendicular to the central axis C of the artificial muscle 200 than the second height H2 of the expandable fluid region 196 of the artificial muscle 100.

[0040] Now refer to Figure 7, an artificial muscle assembly 300 is shown that includes multiple artificial muscles, such as artificial muscle 100. However, it should be understood that multiple artificial muscles 200 can be similarly arranged in a stacked configuration. Each artificial muscle 100 can be structurally identical and arranged in a stack such that the expandable fluid region 196 of each artificial muscle 100 overlaps the expandable fluid region 196 of an adjacent artificial muscle 100. The terminals 130, 152 of each artificial muscle 100 are electrically connected to each other so that the artificial muscles 100 can be simultaneously actuated between an inactive 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 expandable fluid region 196 of each artificial muscle 100. Thus, the degree of deformation caused by the artificial muscle assembly 300 is greater than the degree of deformation provided by the artificial muscles 100 individually.

[0041] Now refer to Figure 8 , an actuation system 400 may be provided for operating an artificial muscle or artificial muscle assembly, such as artificial muscles 100, 200, or artificial muscle assembly 300, between a non-actuated state and an actuated state. Thus, the actuation system 400 may include a controller 402, an operating device 404, a power source 406, and a communication path 408. The various components of the actuation system 400 will now be described.

[0042] Controller 402 includes a processor 410 and non-transitory electronic memory 412 communicatively coupled to various components. In some embodiments, processor 410, non-transitory electronic memory 412, and / or other components are contained within a single device. In other embodiments, processor 410, non-transitory electronic memory 412, and / or other components may be distributed across multiple communicatively coupled devices. Controller 402 includes non-transitory electronic memory 412 storing a set of machine-readable instructions. Processor 410 executes the machine-readable instructions stored in non-transitory electronic memory 412. Non-transitory electronic memory 412 may include RAM, ROM, flash memory, a hard drive, or any device capable of storing machine-readable instructions so that the machine-readable instructions are accessible to processor 410. Thus, the actuation system 400 described herein may be implemented as pre-programmed hardware elements or as a combination of hardware and software components in any conventional computer programming language. Non-transitory electronic memory 412 may be implemented as one memory module or multiple memory modules.

[0043] In some embodiments, non-transitory electronic storage 412 includes instructions for performing functions of actuation system 400. For example, the instructions may include instructions for operating artificial muscles 100, 200 or artificial muscle assembly 300 based on user commands.

[0044] The processor 410 can be any device capable of executing machine-readable instructions. For example, the processor 410 can 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 the various components and / or modules of the actuation system 400. Thus, the communication path 408 can communicatively couple any number of processors to one another and allow the modules coupled to the communication path 408 to operate in a distributed computing environment. Specifically, each module can operate as a node that can send and / or receive data. As used herein, the term "communicatively coupled" means that the coupled components are capable of exchanging data signals with one another, for example, exchanging electrical signals via a conductive medium, exchanging electromagnetic signals via air, exchanging optical signals via optical waveguides, and the like.

[0045] As in Figure 8 As schematically depicted in FIG, communication path 408 communicatively couples processor 410 and non-transitory electronic memory 412 of controller 402 with various other components of actuation system 400. For example, Figure 8 The actuation system 400 depicted in FIG. 4 includes a processor 410 and non-transitory electronic memory 412 communicatively coupled with an operating device 404 and a power source 406 .

[0046] The operating device 404 allows the user to control the operation of the artificial muscle 100, 200 or the artificial muscle assembly 300. In some embodiments, the operating device 404 can be a switch, a trigger, a button, or any combination of controls to provide user operation. As a non-limiting example, the user can actuate the artificial muscle 100, 200 or the artificial muscle assembly 300 to an actuated state by actuating the control of the operating device 404 to a first position. When in the first position, the artificial muscle 100, 200 or the artificial muscle assembly 300 will remain in the actuated state. The user can switch the artificial muscle 100, 200 or the artificial muscle assembly 300 to a non-actuated state by operating the control of the operating device 404 from the first position to a second position.

[0047] The operating device 404 is coupled to the communication path 408 such that the communication path 408 communicatively couples the operating device 404 to the other modules of the actuation system 400. The operating device 404 may provide a user interface for receiving user instructions regarding specific operating configurations of the artificial muscle 100, 200, or the artificial muscle assembly 300. In addition, the user instructions may include instructions to operate the artificial muscle 100, 200, or the artificial muscle assembly 300 only under certain conditions.

[0048] A power source 406 (e.g., a battery) provides power to the artificial muscle 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 battery for powering the artificial muscle 100, 200, or the artificial muscle assembly 300. A power adapter (not shown) can be provided and electrically coupled via a wiring harness or the like to power the artificial muscle 100, 200, or the artificial muscle assembly 300 using the power source 406.

[0049] In some embodiments, the actuation system 400 further includes a display device 414. The display device 414 is coupled to the communication path 408 so that the communication path 408 communicatively couples the display device 414 to the other modules of the actuation system 400. The display device 414 can output a notification or indication of a change in the actuation state of the artificial muscle 100, 200, or the artificial muscle assembly 300 in response to the actuation state of the artificial muscle 100, 200, or the artificial muscle assembly 300. Furthermore, the display device 414 can be a touch screen that, in addition to providing optical information, detects the presence and location of tactile input on a surface of the display device 414 or on a surface adjacent to the display device 414. Thus, the display device 414 can include the operating device 404 and receive mechanical input directly on the optical output provided by the display device 414.

[0050] In some embodiments, the actuation system 400 includes network interface hardware 416 for communicatively coupling the actuation system 400 to a portable device 418 via a network 420. The portable device 418 may include, but is not limited to, a smartphone, a tablet computer, a personal media player, or any other electrical device that includes wireless communication capabilities. It should be understood that when a portable device 418 is provided, the portable device 418 can be used to provide user commands to the controller 402 rather than the operating device 404. In this way, the user may be able to control or set the program for controlling the artificial muscle 100, 200, or the artificial muscle assembly 300 without utilizing the controller of the operating device 404. Thus, the artificial muscle 100, 200, or the artificial muscle assembly 300 can be remotely controlled via the portable device 418 that wirelessly communicates with the controller 402 via the network 420.

[0051] From the above it will be appreciated that what is defined herein is an artificial muscle that can be used to inflate or deform the surface of an object by selectively actuating the artificial muscle to raise or lower an area thereof. This provides a low profile inflatable member that can be manipulated as required.

[0052] It should be noted that the terms "substantially" and "approximately" may be used herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0053] While specific embodiments have been illustrated and described herein, it will be appreciated that various other changes and modifications may be made without departing from the scope of the claimed subject matter. Furthermore, while various aspects of the claimed subject matter have been described herein, these aspects need not be used in combination. It is therefore intended that the appended claims cover all such changes and modifications within the scope of the claimed subject matter.

Claims

1. An artificial muscle comprising: a housing comprising an electrode region and an expandable fluid region; an electrode pair positioned in an electrode region of the housing, the electrode pair comprising a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing, wherein: The first electrode and the second electrode each include two or more tab portions and two or more bridge portions, wherein: Each of the two or more bridging portions interconnects adjacent tab portions; and 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; and a dielectric fluid contained within the housing; The electrode pair is switchable between a non-actuated state and an actuated state, such that switching from the non-actuated state to the actuated state directs the dielectric fluid into the expandable fluid region.

2. The artificial muscle according to claim 1, wherein The shell includes a first membrane layer and a second membrane layer partially sealed to each other to define a sealed portion of the shell, and the shell further includes an unsealed portion surrounded by the sealed portion, wherein the electrode area and the expandable fluid area of the shell are arranged in the unsealed portion.

3. The artificial muscle according to claim 2, characterized in that The first film layer and the second film layer are each biaxially oriented polypropylene films.

4. The artificial muscle according to claim 1 , further comprising a first electrical insulator layer fixed to an inner surface of the first electrode opposite to the first surface of the housing, and a second electrical insulator layer fixed to an inner surface of the second electrode opposite to the second surface of the housing, wherein the first electrical insulator layer and the second electrical insulator layer each include an adhesive surface and an opposing non-sealable surface.

5. The artificial muscle according to claim 1, characterized in that The first electrode and the second electrode are each an aluminum-coated polyester electrode.

6. The artificial muscle according to claim 1, characterized in that The first electrode and the second electrode each include two pairs of tab portions and two pairs of bridge portions, each bridge portion adjacently interconnecting a pair of adjacent tab portions, each tab portion diametrically opposing an opposing tab portion.

7. The artificial muscle according to claim 1, characterized in that 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 length being 20% to 50% of the tab length.

8. The artificial muscle according to claim 1, wherein Each 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, the central openings being coaxially aligned with one another.

9. The artificial muscle according to claim 1, wherein: When the electrode pair is in the non-actuated state, the first electrode and the second electrode are non-parallel to each other; as well as When the electrode pair is in the actuated state, the first electrode and the second electrode are parallel to each other such that the first electrode and the second electrode are configured to zip toward each other and toward the central opening when switched from the non-actuated state to the actuated state.

10. An artificial muscle assembly comprising: Multiple artificial muscles, each artificial muscle includes: a housing comprising an electrode region and an expandable fluid region; an electrode pair positioned in an electrode region of the housing, the electrode pair comprising a first electrode secured to a first surface of the housing and a second electrode secured to a second surface of the housing, wherein: The first electrode and the second electrode each include two or more tab portions and two or more bridge portions, wherein: Each of the two or more bridging portions interconnects adjacent tab portions; and 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; and a dielectric fluid contained within the housing; wherein the plurality of artificial muscles are arranged in a stack such that the expandable fluid regions of each artificial muscle are coaxially aligned with one another; and The electrode pair is switchable between a non-actuated state and an actuated state, such that switching from the non-actuated state to the actuated state directs the dielectric fluid into the expandable fluid region.

11. The artificial muscle assembly according to claim 10, characterized in that The plurality of artificial muscles are electrically coupled to each other and are configured to simultaneously switch between the non-actuated state and the actuated state.

12. The artificial muscle assembly of claim 10, further comprising: a first electrical insulator layer fixed to an inner surface of the first electrode opposite the first surface of the housing and a second electrical insulator layer fixed to an inner surface of the second electrode opposite the second surface of the housing, Wherein, the first electrical insulator layer and the second electrical insulator layer each comprise an adhesive surface and an opposing non-sealable surface.

13. The artificial muscle assembly according to 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 a pair of adjacent tab portions, each tab portion diametrically opposed to an opposing tab portion.

14. The artificial muscle assembly according to claim 10, wherein: Each of the first electrode and the second electrode includes the central opening positioned between the two or more tab portions and surrounding the expandable fluid region, the central openings being coaxially aligned with each other.

15. The artificial muscle assembly according to claim 10, characterized in that: When the electrode pair is in the non-actuated state, the first electrode and the second electrode are non-parallel to each other; as well as When the electrode pair is in the actuated state, the first electrode and the second electrode are parallel to each other such that the first electrode and the second electrode are configured to zip toward each other and toward the central opening when switched from the non-actuated state to the actuated state.

16. A method for actuating an artificial muscle assembly, the method comprising: generating a voltage using a power source electrically coupled to a pair of electrodes of an artificial muscle comprising a housing having an electrode region and an expandable fluid region, wherein: The electrode pair is positioned in an 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, wherein: Each of the two or more bridging portions interconnects adjacent tab portions; and 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; and a dielectric fluid contained within the housing, and The voltage is applied to the electrode pair of the artificial muscle, thereby switching the electrode pair from a non-actuated state to an actuated state, causing the dielectric fluid to be introduced into the expandable fluid region of the housing and expand the expandable fluid region.

17. The method according to claim 16, characterized in that The shell includes a first film layer and a second film layer, and the first film layer and the second film layer are partially heat-sealed to each other to define a sealed portion of the shell, and the shell further includes an unsealed portion surrounded by the sealed portion, wherein the electrode area and the expandable fluid area of the shell are arranged in the unsealed portion.

18. The method according to claim 16, characterized in that A controller is communicatively coupled to the electrode pair, and the controller directs a voltage from the power supply across the first electrode and the second electrode to switch the artificial muscle from the non-actuated state to the actuated state.

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

20. The method according to claim 16, wherein Expanding the expandable fluid region generates a force greater than 4 N·mm per cubic centimeter of actuator volume.

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