Artificial muscle including pair of gradient-enhanced electrodes and assembly including artificial muscle

Abstract

An artificial muscle comprising: a housing having an electrode region and an expandable fluid region; an electrode pair including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid housed within the housing; and a reinforcement member positioned between the housing and at least one of the first electrode and the second electrode, the reinforcement member increasing a stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region, wherein 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. A method for actuating an artificial muscle is also provided.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to apparatuses and methods for focused inflation on at least one surface of a device, and more particularly, to apparatuses and methods for directing fluid with an electrode pair to inflate the device. BACKGROUND

[0002] Current robotic technology relies on rigid members such as servo motors to perform tasks, often in structured environments. This rigidity presents limitations in many robotic applications, at least partially caused by 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 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 artificial muscles. Other artificial muscles use heat-activated polymer fibers, but these fibers are difficult to control and operate inefficiently.

[0003] One particular artificial muscle design is described in the paper by E. Acome, S. K. Mitchell, T. G. Morrissey, M. B. Emmett, C. Benjamin, M. King, M. Radakovitz, and C. Keplinger, entitled “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 various actuation modes. The HASEL actuator artificial muscle contains a shell with uniform stiffness that compresses to push fluid into an expandable fluid region when actuated. However, due to the uniform stiffness of the shell, the shell can compress and direct fluid in a direction away from the expandable fluid region.

[0004] Accordingly, there is a need for improved artificial muscles with gradient stiffness such that the artificial muscles are actuated to more efficiently direct fluid into an expandable fluid region. SUMMARY

[0005] In one embodiment, an artificial muscle includes: a housing having an electrode region and an expandable fluid region; an electrode pair including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid housed within the housing; and a reinforcement member positioned between the housing and at least one of the first electrode and the second electrode, the reinforcement member increasing a stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region, wherein 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.

[0006] In another embodiment, an artificial muscle includes: a housing having an electrode region and an expandable fluid region; an electrode pair including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid housed within the housing; and a pair of reinforcement members positioned between the housing and each of the first electrode and the second electrode, the pair of reinforcement members increasing a stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region, wherein 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 causes a distance between the electrode pair proximate the opposite edges of the electrode region to decrease before a distance between the electrode pair proximate the expandable fluid region decreases.

[0007] In yet another embodiment, a method for actuating an artificial muscle includes: providing a voltage using 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, an electrode pair including a first electrode and a second electrode positioned in the electrode region of the housing, a dielectric fluid housed within the housing, and a reinforcement member positioned between the housing and at least one of the first electrode and the second electrode, the reinforcement member increasing a stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region; and actuating the electrode pair 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.

[0008] These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, taken with the drawings, in which: BRIEF DESCRIPTION OF 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 structures have like reference numerals and in which:

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

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

[0012] Figure 3 schematically depicts Figure 1 a cross-sectional view taken along line 3-3 in Figure 2 of an artificial muscle in a non-actuated state according to one or more embodiments shown and described herein;

[0013] Figure 4 schematically depicts Figure 1 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 exploded view of an illustrative artificial muscle according to one or more embodiments shown and described herein;

[0015] Figure 6 schematically depicts Figure 5 a top plan view of an artificial muscle according to one or more embodiments shown and described herein;

[0016] Figure 7 schematically depicts Figure 5 a cross-sectional view taken along line 7-7 in Figure 6 of an artificial muscle in a non-actuated state according to one or more embodiments shown and described herein;

[0017] Figure 8 schematically depicts Figure 5 a cross-sectional view of an artificial muscle in an actuated state according to one or more embodiments shown and described herein; and

[0018] Figure 9 schematically depicts an actuation system for operating an artificial muscle according to one or more embodiments shown and described herein. DETAILED DESCRIPTION

[0019] Embodiments described herein relate to artificial muscles and methods of operating artificial muscles. Artificial muscles described herein are actuatable to selectively raise and lower regions of the artificial muscle to provide a selectively, on-demand inflatable expandable fluid region. The artificial muscle includes a housing and a pair of electrodes. A dielectric fluid is contained within the housing, and the housing includes an electrode region and an expandable fluid region, with the pair of electrodes located in the electrode region. The pair of electrodes includes a first electrode and a second electrode located within the electrode region of the housing. A reinforcing member is located between the housing and at least one of the first and second electrodes. The reinforcing member increases the stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region. A housing having increased stiffness in a direction extending toward the expandable fluid region causes the end of the housing opposite the expandable fluid region to be compressed first and zippered toward the expandable fluid region when the pair of electrodes is actuated. The pair of electrodes 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. This causes the expandable fluid region to expand, thereby on-demand raising a portion of the artificial muscle. Various embodiments of the artificial muscle and operation of the artificial muscle are described in greater detail herein. Wherever possible, the same reference numbers will be used in the various drawings to refer to the same or like parts.

[0020] Referring now to Figures 1-4 , an artificial muscle 100 is shown. As shown in Figure 1 , the artificial muscle 100 includes a housing 102, a pair of electrodes 104 including a first electrode 106 and a second electrode 108, 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. The artificial muscle 100 also includes one or more reinforcing members located between the housing 102 and at least one of the first electrode 106 and the second electrode 108. As shown, a first reinforcing member 113 and a second reinforcing member 115 are located between the housing 102 and the first electrode 106, and a third reinforcing member 117 and a fourth reinforcing member 119 are located between the housing 102 and the second electrode 108.

[0021] In some embodiments, the shell 102 is a single-piece monolithic layer that includes a pair of opposing interior surfaces, such as the first interior surface 114 and the second interior surface 116, and a pair of opposing exterior surfaces, such as the first exterior surface 118 and the second exterior surface 120. In some embodiments, the first interior surface 114 and the second interior surface 116 of the shell 102 are heat sealable. In other embodiments, the shell 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 the first interior surface 114 and the first exterior surface 118, and the second film layer 124 includes the second interior surface 116 and the second exterior surface 120.

[0022] Throughout the following description, reference can be made to the shell 102 including the first film layer 122 and the second film layer 124, as opposed to a single-piece shell. However, it should be understood that 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 an elastomeric material. In some embodiments, the first film layer 122 and the second film layer 124 each include biaxially oriented polypropylene. In embodiments, each of the first film layer 122 and the second film layer 124 has a total thickness of between 1 mil and 5 mils, such as 1.5 mils, 2 mils, 2.5 mils, 3 mils, 3.5 mils, 4 mils, 4.5 mils, or any range having any of these two values as endpoints. Although not shown, each of the first film layer 122 and the second film layer 124 can include a pair of biaxially oriented polypropylene layers. In one exemplary embodiment, each biaxially oriented polypropylene layer can have a thickness of 1.5 mils to provide the first film layer 122 and the second film layer 124 each having a total thickness of 3 mils.

[0023] 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, for example Additionally, 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, as long as one electrode 106, 108 of the artificial muscle 100 is negatively charged, the other electrode 106, 108 can be positively charged.

[0024] The first electrode 106 has a surface 126 facing the membrane, an opposing inner surface 128, a first end 121, and an opposing second end 123. The first electrode 106 has a length L1 extending between the first end 121 and the second end 123. Additionally, the first electrode 106 includes a first terminal 130 extending from the first end 121 of the first electrode 106 through the edge of the first membrane layer 122, such that the first terminal 130 can be connected to a power source to actuate the first electrode 106. Specifically, as... Figure 9 As shown, the first terminal 130 is directly or in series connected to the controller of the power supply and actuation system 300. Similarly, the second electrode 108 has a membrane-facing surface 148, an opposing inner surface 150, a first end 125, and an opposing second end 127. The second electrode 108 has a length L2 extending between the first end 125 and the second end 127. The second electrode 108 includes a second terminal 152 extending from the first end 125 of the second electrode 108 through the edge of the second membrane layer 124, such that the second terminal 152 can be connected to the controller of the power supply and actuation system 300 to actuate the second electrode 108.

[0025] As described above, the first reinforcing member 113 and the second reinforcing member 115 are disposed between the first film layer 122 and the first electrode 106. As discussed in more detail herein, the first reinforcing member 113 and the second reinforcing member 115 provide gradient stiffness to gradually or incrementally increase the stiffness of the first film layer 122, which causes a zipper-like fastening movement of the first film layer 122 in the direction from the first end 121 of the first electrode 106 toward the second end 123 of the first electrode 106 when the electrode pair 104 is actuated. Specifically, the first reinforcing member 113 has a first end 129 and an opposing second end 131 defining a length L3 therebetween. Additionally, the second reinforcing member 115 has a first end 133 and an opposing second end 135 defining a length L4 therebetween. It should be understood that the length L1 of the first electrode 106 is greater than the length L3 of the first reinforcing member 113. Furthermore, the length L4 of the second reinforcing member 115 is between the length L1 of the first electrode 106 and the length L3 of the first reinforcing member 113. As shown in the figure, the first reinforcing member 113 is positioned between the first film layer 122 and the second reinforcing member 115, and the second reinforcing member 115 is positioned between the first reinforcing member 113 and the first electrode 106. Furthermore, during assembly, the second end 131 of the first reinforcing member 113 and the second end 135 of the second reinforcing member 115 are aligned with the second end 123 of the first electrode 106.

[0026] With respect to the third and fourth stiffening members 117, 119, the third stiffening member 117 has a first end 137 and an opposite second end 139 defining a length L5 therebetween. Additionally, the fourth stiffening member 119 has a first end 141 and an opposite second end 143 defining a length L6 therebetween. It should be appreciated that the length L2 of the second electrode 108 is greater than the length L5 of the third stiffening member 117. Additionally, the length L6 of the fourth stiffening member 119 is between the length L2 of the second electrode 108 and the length L5 of the third stiffening member 117. As discussed in greater detail herein, the third and fourth stiffening members 117, 119 provide a gradient stiffness to gradually or incrementally increase the stiffness of the second film layer 124, which causes a zippering motion of the second film layer 124 in a direction from the first end 125 of the second electrode 108 toward the second end 127 of the second electrode 108 when the electrode pair 104 is actuated. As shown, the third stiffening member 117 is positioned between the second film layer 124 and the fourth stiffening member 119, and the fourth stiffening member 119 is positioned between the third stiffening member 117 and the second electrode 108. Further, when assembled, both the second end 139 of the third stiffening member 117 and the second end 143 of the fourth stiffening member 119 are aligned with the second end 127 of the second electrode 108.

[0027] In example embodiments, the first, second, third, and fourth stiffening members 113, 115, 117, 119 are each a biaxially oriented polypropylene layer having a thickness between 1 and 2 mils, such as 1 mil, 1.5 mils, 2 mils, or any range having either of these two values as endpoints. In some embodiments, only one of both the first and second stiffening members 113, 115 is disposed between the first film layer 122 and the first electrode 106. Further, in some embodiments, the first and second stiffening members 113, 115 can be a single-piece unitary member such that a thickness of the unitary member at its first end is less than a thickness of the unitary member at its opposite second end. The thickness can gradually or incrementally increase along a length direction from the first end toward the second end, such as toward the second end 123 of the first electrode 106. Similarly, in some embodiments, only one of both the third and fourth stiffening members 117, 119 is disposed between the second film layer 124 and the second electrode 108. Further, in some embodiments, the third and fourth stiffening members 117, 119 can be a single-piece unitary member such that a thickness of the unitary member at its first end is less than a thickness of the unitary member at its opposite second end. The thickness can gradually or incrementally increase along a length direction from the first end toward the second end, such as toward the second end 127 of the second electrode 108.

[0028] Still referring to Figure 1 The first electrical insulator layer 110 has a first end 145 and an opposite second end 147. Similarly, the second electrical insulator layer 112 has a first end 149 and an opposite second end 151. When assembled, the first end 145 of the first electrical insulator layer 110 and the first end 149 of the second electrical insulator layer 112 are each aligned with the first end 121 of the first electrode 106 and the first end 125 of the second electrode 108. 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 opposite 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 a polymer tape that is adhered to the inner surface 128 of the first electrode 106 and the inner surface 150 of the second electrode 108, respectively.

[0029] Referring now to Figure 2 A top plan view of the artificial muscle 100 is shown in its assembled form, with the first terminal end 130 of the first electrode 106 and the second terminal end 152 of the second electrode 108 extending beyond the outer periphery of the housing 102 (i.e., the first film layer 122 and the second film layer 124). As shown, the second electrode 108 is stacked on top of the first electrode 106, and thus, only the second film layer 124, the third reinforcing member 117, the fourth reinforcing member 119, and the second electrode 108 are illustrated, as the other members are hidden from this view.

[0030] Referring now to Figure 3 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. Additionally, the first reinforcing member 113 and the second reinforcing member 115 are positioned between the first film layer 122 and the first electrode 106, and the third reinforcing member 117 and the fourth reinforcing member 119 are positioned between the second film layer 124 and the second electrode 108. The first film layer 122 is partially sealed to the second film layer 124 at a region that encloses the first electrical insulator layer 110 and the second electrical insulator layer 112. Specifically, the first film layer 122 is sealed to the second film layer 124 to define a sealed portion 190 that encloses the first electrical insulator layer 110 and the second electrical insulator layer 112. In some embodiments, the first film layer 122 is heat sealed to the second film layer 124. However, the first film layer 122 and the second film layer 124 can be sealed in any suitable manner, such as using an adhesive or the like.

[0031] The first and second electrical insulator layers 110, 112 provide a barrier that prevents a portion of the first film layer 122 from sealing to an opposing portion of the second film 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 adjacent the electrode region 194. Although not shown, the housing 102 can be cut to conform to the geometry of the first and second electrical insulator layers 110, 112 and to reduce the size of the artificial muscle 100, i.e., the size of the sealed portion 190.

[0032] A dielectric fluid 198 is disposed within the unsealed portion 192 and is free to flow between the first and second electrodes 106, 108. As used herein, a "dielectric" fluid is a medium or material that transmits electric force without conduction and thus has a low electrical conductivity. Some non-limiting example dielectric fluids include perfluorocarbons, 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.

[0033] The artificial muscle 100 is actuatable between an unactuated state and an actuated state. In the unactuated state, as shown in FIG. 1, Figure 3 the first and second electrodes 106, 108 are partially spaced apart from one another near the second ends 123, 127 of the first and second electrodes 106, 108, respectively. Because the housing 102 is sealed, the first and second ends 121, 125 of the first and second electrodes 106, 108, respectively, are held in place relative to one another. In the actuated state, as shown in FIG. 2, Figure 4As shown in FIG. 1, the first electrode 106 and the second electrode 108 are in contact with each other and oriented parallel to each other to force the dielectric fluid 198 into the expandable fluid region 196. This causes the dielectric fluid 198 to flow into the expandable fluid region 196 and inflate the expandable fluid region 196. In particular, it should be appreciated that the first stiffening member 113 and the second stiffening member 115 make the first membrane layer 122 increasingly rigid within the electrode region 194 in a direction toward the expandable fluid region 196. Similarly, the third stiffening member 117 and the fourth stiffening member 119 make the second membrane layer 124 increasingly rigid within the electrode region 194 in a direction toward the expandable fluid region 196. Thus, during actuation of the electrode pair 104, the least rigid portions of the first membrane layer 122 and the second membrane layer 124 (i.e., those portions without any of the stiffening members 113, 115, 117, 119) are first drawn toward each other by actuation of the electrode pair 104. Subsequently, adjacent portions of the first membrane layer 122 and the second membrane layer 124 having a rigidity greater than the least rigid portions (i.e., those portions containing only the second stiffening member 115 or the fourth stiffening member 119 therebetween) are drawn toward each other. Finally, the remaining portions of the first membrane layer 122 and the second membrane layer 124 having the greatest rigidity (i.e., those portions containing each of the stiffening members 113, 115, 117, 119 therebetween) are drawn toward each other, as shown in FIG. 1. Figure 4 It should be appreciated that the increasing rigidity of the first membrane layer 122 and the second membrane layer 124 in a direction toward the expandable fluid region 196 facilitates a "zipper-like" closing of the electrodes from the first end 121 of the first electrode 106 and the first end 125 of the second electrode 108 toward the second end 123 of the first electrode 106 and the second end 127 of the second electrode 108.

[0034] Referring again to FIG. 1, Figure 3The diagram illustrates an artificial muscle 100 in a non-actuated state. An electrode pair 104 is disposed within the electrode region 194 of the unsealed portion 192 of the housing 102. 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. Because the first membrane layer 122 is hermetically connected to the second membrane layer 124, the first end 121 of the first electrode 106 and the first end 125 of the second electrode 108 are in contact with each other. Therefore, a dielectric fluid 198 is disposed between the first electrode 106 and the second electrode 108, thereby approaching the expandable fluid region 196 to separate the second end 123 of the first electrode 106 and the second end 127 of the second electrode 108. In other words, the distance between the second end 123 of the first electrode 106 and the second end 127 of the second electrode 108 is greater than the distance between the first end 121 of the first electrode 106 and the first end 125 of the second electrode 108. In some embodiments, the first electrode 106 and the second electrode 108 may be flexible. In the non-actuated state, the expandable fluid region 196 has a height H1.

[0035] When actuated, such as Figure 4 As shown, the first electrode 106 and the second electrode 108 are zipped together from the first end 121 of the first electrode 106 and the first end 125 of the second electrode 108, thereby pushing the dielectric fluid 198 into the expandable fluid region 196. As shown, when 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 expandable fluid region 196 to cause the expandable fluid region 196 to expand. Thus, the first film layer 122 and the second film layer 124 expand in opposite directions. In the actuated state, the expandable fluid region 196 has a height H2, which is greater than the height H1 of the expandable fluid region 196 when in the non-actuated state. Although not shown, it should be noted that the electrode pair 104 can be partially actuated to a position between the non-actuated and actuated states. This allows for partial expansion of the expandable fluid region 196 and, if necessary, adjustment.

[0036] To move the first electrode 106 and the second electrode 108 toward one another, a voltage is applied by a power source. In some embodiments, a voltage of up to 10 kV can be provided from 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 expandable fluid region 196. The pressure from the dielectric fluid 198 within the expandable fluid region 196 deforms the first membrane layer 122 and the first electrical insulator layer 110 and deforms the second membrane layer 124 and the second electrical insulator layer 112 in opposite second axial directions. Once the voltage is stopped from being supplied to the first electrode 106 and the second electrode 108, the first electrode 106 and the second electrode 108 return to their initial non-parallel positions in the non-actuated state.

[0037] Also, 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, when a larger 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 appreciated that the size of the expandable fluid region 196 is defined by the length of the first electrical insulator layer 110 and the second electrical insulator layer 112 and the difference between the length LI of the first electrode 106 and the length L2 of the second electrode 108. Thus, the degree of displacement within the expandable fluid region 196 can alternatively or additionally be controlled by increasing or decreasing the length of the first electrical insulator layer 110 and the second electrical insulator layer 112.

[0038] Referring now to Figures 5-8 , an artificial muscle 200 is shown. As Figure 5 shown, the artificial muscle 200 is generally similar to the artificial muscle 100 discussed herein, except that the various layers have a generally plus sign shape geometry. Thus, the artificial muscle 200 includes a housing 202, an electrode pair 204 including a first electrode 206 and a second electrode 208, a first electrical insulator layer 210 fixed to the first electrode 206, and a second electrical insulator layer 212 fixed to the second electrode 208. The artificial muscle 200 also includes one or more reinforcement members positioned between the housing 202 and at least one of the first electrode 206 and the second electrode 208. As shown, a first reinforcement member 213 and a second reinforcement member 215 are positioned between the housing 202 and the first electrode 206, and a third reinforcement member 217 and a fourth reinforcement member 219 are positioned between the housing 202 and the second electrode 208.

[0039] In some embodiments, the housing 202 is a single-piece monolithic layer that includes a pair of opposing inner surfaces, such as a first inner surface 214 and a second inner surface 216, and a pair of opposing outer surfaces, such as a first outer surface 218 and a second outer surface 220. In some embodiments, the first inner surface 214 and the second inner surface 216 of the housing 202 are heat sealable. In other embodiments, the housing 202 can be a pair of separately manufactured film layers, such as a first film layer 222 and a second film layer 224. Thus, the first film layer 222 includes the first inner surface 214 and the first outer surface 218, and the second film layer 224 includes the second inner surface 216 and the second outer surface 220.

[0040] Throughout the following description, reference can be made to the housing 202 including the first film layer 222 and the second film layer 224, as opposed to a single-piece housing. It should be understood that either arrangement is contemplated. In some embodiments, the first film layer 222 and the second film layer 224 generally include the same structure and composition. For example, in some embodiments, the first film layer 222 and the second film layer 224 each include biaxially oriented polypropylene. In embodiments, each of the first film layer 222 and the second film layer 232 has a total thickness of 3 mils. Although not shown, each of the first film layer 222 and the second film layer 232 can include a pair of biaxially oriented polypropylene layers. In embodiments, each biaxially oriented polypropylene layer has a thickness of between 1 mil and 2 mils, such as 1 mil, 1.5 mils, 2 mils, or any range having either of these two values as endpoints. In embodiments, each biaxially oriented polypropylene layer has a thickness of 1.5 mils to provide the first film layer 222 and the second film layer 232 each having a total thickness of 3 mils.

[0041] The first electrode 206 and the second electrode 208 are each positioned between the first film layer 222 and the second film layer 224. In some embodiments, the first electrode 206 and the second electrode 208 are each an aluminum-coated polyester, such as Additionally, one of the first electrode 206 and the second electrode 208 is a negatively charged electrode, and the other of the first electrode 206 and the second electrode 208 is a positively charged electrode. For the purposes discussed herein, as long as one electrode 206, 208 of the artificial muscle 200 is negatively charged, the other electrode 206, 208 can be positively charged.

[0042] The first electrode 206 has a film-facing surface 226 and an opposing inner surface 228. Additionally, the first electrode 206 includes a first terminal 230 that extends from the first electrode 206 beyond an edge of the first film layer 222, such that the first terminal 230 can be connected to a power source to actuate the first electrode 206. In particular, as shown in FIG. 1, the first terminal 230 extends beyond the edge of the first film layer 222 to a location outside of the housing 202. In some embodiments, the first terminal 230 is a tab that extends from the first electrode 206. In other embodiments, the first terminal 230 is a wire that extends from the first electrode 206. Figure 9The terminals are directly or serially coupled to a power source and a controller of the actuation system 300, as shown. Similarly, the second electrode 208 has a membrane-facing surface 248 and an opposite inner surface 250. The second electrode 208 includes a second terminal 252 extending from the second electrode 208 beyond an edge of the second membrane layer 224, such that the second terminal 252 can be connected to the power source and the controller of the actuation system 300 to actuate the second electrode 208.

[0043] The first electrode 206 includes two or more tab portions 232 and two or more bridge portions 240. Each bridge portion 240 is positioned between adjacent tab portions 232, thereby interconnecting the adjacent tab portions 232. Each tab portion 232 has a first end 234 extending radially with respect to a central axis C of the first electrode 206 to an opposite second end 236 of the tab portion 232, where the second end 236 defines a portion of an outer periphery 238 of the first electrode 206. Each bridge portion 240 has a first end 242 extending radially with respect to the central axis C of the first electrode 206 to an opposite second end 244 of the bridge portion 240, which defines another portion of the outer periphery 238 of the first electrode 206. Each tab portion 232 has a tab length Al, and each bridge portion 240 has a bridge length A2 extending in a radial direction with respect to the central axis C of the first electrode 206. The tab length Al defines a distance from the first end 234 to the second end 236 of the tab portion 232, and the bridge length A2 defines a distance from the first end 242 to the second end 244 of the bridge portion 240. The tab length Al of each tab portion 232 is longer than the bridge length A2 of each bridge portion 240. In some embodiments, the bridge length A2 is 20% to 50% of the tab length Al, such as 30% to 40% of the tab length Al.

[0044] In some embodiments, the two or more tab portions 232 are arranged in one or more pairs of tab portions 232. Each pair of tab portions 232 includes two tab portions 232 arranged diametrically opposite each other. In some embodiments, the first electrode 206 can include only two tab portions 232 positioned on opposite sides or ends of the first electrode 206. In some embodiments, as shown in FIG. 2, the first electrode 206 includes four tab portions 232 arranged in two pairs of tab portions 232 diametrically opposite each other. Figure 5 As shown in FIG. 1, the first electrode 206 includes four tab portions 232 and four bridge portions 240 interconnecting adjacent tab portions 232. In this embodiment, the four tab portions 232 are arranged in two pairs of tab portions 232 diametrically opposite each other. Further, as shown, the first terminal 230 extends from and is integral with the second end 236 of one of the tab portions 232.

[0045] Similar to the first electrode 206, the second electrode 208 includes at least one pair of tab portions 254 and two or more bridge portions 262. Each bridge portion 262 is positioned between adjacent tab portions 254, thereby interconnecting the adjacent tab portions 254. Each tab portion 254 has a first end 256 extending radially with respect to a central axis C of the second electrode 208 to an opposite second end 258 of the tab portion 254, where the second end 258 defines a portion of an outer periphery 260 of the second electrode 208. Since the first electrode 206 and the second electrode 108 are coaxial with each other, the central axis C of the first electrode 106 and the central axis C of the second electrode 108 are the same. Each bridge portion 262 has a first end 264 extending radially with respect to the central axis C of the second electrode 208 to an opposite second end 266 of the bridge portion 262, where the opposite second end 266 of the bridge portion 262 defines another portion of the outer periphery 260 of the second electrode 208. Each tab portion 254 has a tab length A3, and each bridge portion 262 has a bridge length A4 extending in a radial direction with respect to the central axis C of the second electrode 208. The tab length A3 defines a distance from the first end 256 to the second end 258 of the tab portion 254, and the bridge length A4 defines a distance from the first end 264 to the second end 266 of the bridge portion 262. The tab length A3 is longer than the bridge length A4 of each bridge portion 262. In some embodiments, the bridge length A4 is 20% to 50% of the tab length A3, such as 30% to 40% of the tab length A3.

[0046] In some embodiments, two or more tab portions 254 are arranged in one or more pairs of tab portions 254. Each pair of tab portions 254 includes two tab portions 254 arranged diametrically opposite each other. In some embodiments, the second electrode 208 can include only two tab portions 254 positioned on opposite sides or ends of the second electrode 208. In some embodiments, as shown in FIG. 2, the second electrode 208 includes four tab portions 254 arranged in two pairs of tab portions 254 diametrically opposite each other. Figure 5 In some embodiments, the second electrode 208 includes four tab portions 254 and four bridge portions 262 interconnecting adjacent tab portions 254, as shown in FIG. 2. In this embodiment, the four tab portions 254 are arranged in two pairs of tab portions 254 diametrically opposite each other. In addition, as shown, the second terminal 252 extends from and is integrally formed with the second end 258 of one of the tab portions 254.

[0047] Still referring to FIG. 2, the second electrode 208 includes a first end 270 and a second end 272. The first end 270 of the second electrode 208 is positioned on a first side 274 of the second electrode 208, and the second end 272 of the second electrode 208 is positioned on a second side 276 of the second electrode 208 opposite the first side 274. The first end 270 of the second electrode 208 is positioned on a first end 278 of the second electrode 208, and the second end 272 of the second electrode 208 is positioned on a second end 280 of the second electrode 208 opposite the first end 278. The first end 270 of the second electrode 208 is positioned on a first end 282 of the second electrode 208, and the second end 272 of the second electrode 208 is positioned on a second end 284 of the second electrode 208 opposite the first end 282. The first end 270 of the second electrode 208 is positioned on a first end 286 of the second electrode 208, and the second end 272 of the second electrode 208 is positioned on a second end 288 of the second electrode 208 opposite the first end 286. Figure 5At least one of the first electrode 206 and the second electrode 208 has a central opening formed therein between the first end 234 of the tab portion 232 and the first end 242 of the bridge portion 240. As shown, the first electrode 206 has a central opening 246. However, it should be appreciated that the first electrode 206 need not necessarily include the central opening 246 when the central opening 268 is provided in the second electrode 208. Alternatively, the second electrode 208 need not necessarily include the central opening 268 when the central opening 246 is provided in the first electrode 206.

[0048] As discussed above, the first stiffening member 213 and the second stiffening member 215 are disposed between the first membrane layer 222 and the first electrode 206. As discussed in greater detail herein, the first stiffening member 213 and the second stiffening member 215 provide a gradient stiffness to gradually or incrementally increase the stiffness of the first membrane layer 222. As shown, the first stiffening member 213 is positioned between the first membrane layer 222 and the second stiffening member 215, and the second stiffening member 215 is positioned between the first stiffening member 213 and the first electrode 206.

[0049] The first stiffening member 213 and the second stiffening member 215 each have a geometry that generally corresponds to the first electrode 206. Thus, the first stiffening member 213 includes tab portions 221 defining an outer periphery 225 and bridge portions 223 extending between adjacent tab portions 221. Similarly, the second stiffening member 215 includes tab portions 227 defining an outer periphery 231 and bridge portions 229 extending between adjacent tab portions 227. However, the first stiffening member 213 and the second stiffening member 215 are smaller in size than the first electrode 206. Specifically, the second stiffening member 215 is smaller in size than the first electrode 206, and the first stiffening member 213 is smaller in size than the second stiffening member 215. In embodiments where the first electrode 206 has the central opening 246, the first stiffening member 213 has a central opening 233 and the second stiffening member 215 has a central opening 235, each of which is coaxial with the central opening 246 of the first electrode 206.

[0050] With respect to the third stiffening member 217 and the fourth stiffening member 219, as discussed above, the third stiffening member 217 and the fourth stiffening member 219 are disposed between the second membrane layer 224 and the second electrode 208. As discussed in greater detail herein, the third stiffening member 217 and the fourth stiffening member 219 provide a gradient stiffness to gradually or incrementally increase the stiffness of the second membrane layer 224. As shown, the third stiffening member 217 is positioned between the second membrane layer 224 and the fourth stiffening member 219, and the fourth stiffening member 219 is positioned between the third stiffening member 217 and the second electrode 208.

[0051] The third and fourth reinforcing members 217, 219 each have a geometry that generally corresponds to the second electrode 208. Thus, the third reinforcing member 217 includes tab portions 237 that define an outer perimeter 241 and bridge portions 239 that extend between adjacent tab portions 237. Similarly, the fourth reinforcing member 219 includes tab portions 243 that define an outer perimeter 247 and bridge portions 245 that extend between adjacent tab portions 243. However, the third and fourth reinforcing members 217, 219 are smaller in size than the second electrode 208. Specifically, the fourth reinforcing member 219 is smaller in size than the second electrode 208, and the third reinforcing member 217 is smaller in size than the fourth reinforcing member 219. In embodiments in which the second electrode 208 has a central opening 268, the third reinforcing member 217 has a central opening 249 and the fourth reinforcing member 219 has a central opening 251, which are coaxial with the central opening 268 of the second electrode 208.

[0052] In embodiments, the first, second, third, and fourth reinforcing members 213, 215, 217, 219 are each a biaxially oriented polypropylene layer having a thickness of between 1 and 2 mils, such as 1 mil, 1.5 mil, 2 mil, or any range having either of these two values as endpoints. In embodiments, only one of the first and second reinforcing members 213, 215 is disposed between the first film layer 222 and the first electrode 206. Further, in embodiments, the first and second reinforcing members 213, 215 can be a single-piece unitary member such that the thickness of the unitary member at an end opposite the central opening is less than the thickness of the unitary member at the central opening. The thickness can gradually increase or incrementally increase along a length direction from the opposite end toward the central opening. Similarly, in embodiments, only one of the third and fourth reinforcing members 217, 219 is disposed between the second film layer 224 and the second electrode 208. Further, in embodiments, the third and fourth reinforcing members 217, 219 can be a single-piece unitary member such that the thickness of the unitary member at an end opposite the central opening is less than the thickness of the unitary member at the central opening. The thickness can gradually increase or incrementally increase along a length direction from the opposite end toward the central opening.

[0053] Still referring to Figure 5The first and second electric insulator layers 210, 212 have geometrical shapes that generally correspond to the first and second electrodes 206, 208, respectively. Thus, the first and second electric insulator layers 210, 212 each have tab portions 270, 272 and bridge portions 274, 276 that correspond to respective portions of the first and second electrodes 206, 208. Further, the first and second electric insulator layers 210, 212 each have outer perimeters 278, 280 that correspond to the outer perimeters 238, 260 of the first and second electrodes 206, 208, respectively, when positioned on the first and second electrodes 206, 208.

[0054] It should be appreciated that, in some embodiments, the first and second electric insulator layers 210, 212 generally comprise the same structure and composition. Thus, in some embodiments, the first and second electric insulator layers 210, 212 each comprise an adhesive surface 282, 284 and an opposing non-sealable surface 286, 288, respectively. Thus, in some embodiments, the first and second electric insulator layers 210, 212 are each a polymer tape that is adhered to the inner surface 228 of the first electrode 206 and the inner surface 250 of the second electrode 208, respectively.

[0055] Reference is now made to Figure 6 A top plan view of the artificial muscle 200 is shown in an assembled form of the artificial muscle 200, with the first terminal 230 of the first electrode 206 and the second terminal 252 of the second electrode 208 extending beyond the outer perimeters of the housing 202 (i.e., the first and second film layers 222, 224). As shown, the second electrode 208 is stacked on top of the first electrode 206, and thus, only the second film layer 224, the third reinforcing member 217, the fourth reinforcing member 219, and the second electrode 208 are illustrated, as the other members are hidden from this view.

[0056] Reference is now made to Figure 7In its assembled form, the first electrode 206, the second electrode 208, the first electrical insulator layer 210, and the second electrical insulator layer 212 are sandwiched between the first film layer 222 and the second film layer 224. Additionally, the first reinforcement member 213 and the second reinforcement member 215 are positioned between the first film layer 222 and the first electrode 206, and the third reinforcement member 217 and the fourth reinforcement member 219 are positioned between the second film layer 224 and the second electrode 208. The first film layer 222 is partially sealed to the second film layer 224 at areas that encompass the outer perimeters 238, 260 of the first electrode 206 and the second electrode 208. Specifically, in some embodiments, the first film layer 222 is sealed to the second film layer 224 to define a sealed portion 290 that encompasses the first electrode 206 and the second electrode 208. In some embodiments, the first film layer 222 is heat sealed to the second film layer 224. However, the first film layer 222 and the second film layer 224 can be sealed in any suitable manner, such as using an adhesive or the like.

[0057] The first electrical insulator layer 210 and the second electrical insulator layer 212 provide a barrier that prevents a portion of the first film layer 222 from sealing to an opposing portion of the second film layer 224, thereby forming an unsealed portion 292. The unsealed portion 292 of the housing 202 contains an electrode region 294 in which the electrode pair 204 is disposed, and an expandable fluid region 296 that is encompassed by the electrode region 294. The central openings 246, 268 of the first electrode 206 and the second electrode 208, and the central openings of the reinforcement members define the expandable fluid region 296 and are arranged to axially stack on top of one another. Although not shown, the housing 202 can be cut to conform to the geometry of the first electrical insulator layer 210 and the second electrical insulator layer 212, and to reduce the size of the artificial muscle 200, i.e., the size of the sealed portion 290.

[0058] A dielectric fluid 298, such as the dielectric fluid 198, is disposed within the unsealed portion 292 and is free to flow between the first electrode 206 and the second electrode 208. Similar to the artificial muscle 100 discussed herein, the artificial muscle 200 is actuatable between a non-actuated state and an actuated state. In the non-actuated state, as shown in FIG. 2A, the first electrode 206 and the second electrode 208 are partially spaced apart from one another at their central openings 246, 268 and near the first ends 234, 256 of the tab portions 232, 254. Due to the sealing of the housing 202 at the outer perimeters 238, 260 of the first electrode 206 and the second electrode 208, the second ends 236, 258 of the tab portions 232, 254 are held in place relative to one another. In the actuated state, as shown in FIG. 2B, the first electrode 206 and the second electrode 208 are in contact with one another at their central openings 246, 268 and near the second ends 236, 258 of the tab portions 232, 254. Figure 7 Figure 8 ​As shown in FIG. 3, the first electrode 206 and the second electrode 208 are in contact with each other and oriented parallel to each other to force the dielectric fluid 298 into the expandable fluid region 296. This causes the dielectric fluid 298 to flow through the central openings 246, 268 of the first electrode 206 and the second electrode 208 and inflate the expandable fluid region 296. In particular, it should be appreciated that the first stiffening member 213 and the second stiffening member 215 make the first membrane layer 222 increasingly rigid within the electrode region 294 in a direction toward the expandable fluid region 296. Similarly, the third stiffening member 217 and the fourth stiffening member 219 make the second membrane layer 224 increasingly rigid within the electrode region 294 in a direction toward the expandable fluid region 296. Thus, during actuation of the electrode pair 204, the least rigid portions of the first membrane layer 222 and the second membrane layer 224 (i.e., those portions without any of the stiffening members 213, 215, 217, 219) are first drawn toward each other by actuation of the electrode pair 204. Subsequently, adjacent portions of the first membrane layer 222 and the second membrane layer 224 having a greater rigidity than the least rigid portions (i.e., those portions containing only the second stiffening member 215 or the fourth stiffening member 219 therebetween) are drawn toward each other. Finally, the remaining portions of the first membrane layer 222 and the second membrane layer 224 having the greatest rigidity (i.e., those portions containing each of the stiffening members 213, 215, 217, 219 therebetween) are drawn toward each other, as shown in FIG. 3. Figure 8 It should be appreciated that the increasing rigidity of the first membrane layer 222 and the second membrane layer 224 in a direction toward the expandable fluid region 296 facilitates a "zipper-like" unzipping of the electrodes from the second ends 236, 258 of the tab portions 232, 254 of the first electrode 206 and the second electrode 208 toward the first ends 234, 256 of the tab portions 232, 254 of the first electrode 206 and the second electrode 208.

[0059] Reference is now made to Figure 7The diagram illustrates an artificial muscle 200 in a non-actuated state. An electrode pair 204 is disposed within the electrode region 294 of the unsealed portion 292 of the housing 202. The central opening 246 of the first electrode 206 and the central opening 268 of the second electrode 208 are coaxially aligned within the expandable fluid region 296. In the non-actuated state, the first electrode 206 and the second electrode 208 are partially spaced apart from each other and are not parallel. Because the first membrane layer 222 seals the electrode pair 204 to the second membrane layer 224, the second ends 236 and 258 of the tab portions 232 and 254 are in contact with each other. Therefore, a dielectric fluid 298 is disposed between the first electrode 206 and the second electrode 208, thereby approaching the expandable fluid region 196 and separating the first ends 234 and 256 of the tab portions 232 and 254. In other words, the distance between the first end 234 of the contact portion 232 of the first electrode 206 and the first end 256 of the contact portion 254 of the second electrode 208 is greater than the distance between the second end 236 of the contact portion 232 of the first electrode 206 and the second end 258 of the contact portion 254 of the second electrode 208. In some embodiments, the first electrode 206 and the second electrode 208 can be flexible. Therefore, as... Figure 7 As shown, the first electrode 206 and the second electrode 208 are convex so that the second ends 236 and 258 of their contact portions 232 and 254 can remain close to each other, but are spaced apart from each other near the central openings 246 and 268. In the non-actuated state, the expandable fluid region 296 has a height B1.

[0060] When actuated, such as Figure 8 As shown, the first electrode 206 and the second electrode 208 are zipped together from the second ends 236 and 258 of their tab portions 232 and 254, thereby pushing the dielectric fluid 298 into the expandable fluid region 296. As shown, in the actuated state, the first electrode 206 and the second electrode 208 are parallel to each other. In the actuated state, the dielectric fluid 298 flows into the expandable fluid region 296, causing the expandable fluid region 296 to expand. Thus, the first film layer 222 and the second film layer 224 expand in opposite directions. In the actuated state, the expandable fluid region 296 has a height B2, which is greater than the height B1 of the expandable fluid region 296 in the non-actuated state. Although not shown, it should be noted that the electrode pair 204 can be partially actuated to a position between the non-actuated and actuated states. This allows for partial expansion of the expandable fluid region 296 and, if necessary, adjustment.

[0061] To move the first and second electrodes 206, 208 toward one another, a voltage is applied by a power source. In some embodiments, a voltage of up to 10 kV can be provided from the power source to create a supply electric field through the dielectric fluid 298. The resulting attractive force between the first and second electrodes 206, 208 pushes the dielectric fluid 298 into the expandable fluid region 296. The pressure from the dielectric fluid 298 within the expandable fluid region 296 deforms the first membrane layer 222 and the first electrical insulator layer 210 along the central axis C of the first electrode 206 in a first axial direction, and deforms the second membrane layer 224 and the second electrical insulator layer 212 along the central axis C of the second electrode 208 in an opposite second axial direction. Once the voltage is stopped from being supplied to the first and second electrodes 206, 208, the first and second electrodes 206, 208 return to their initial non-parallel positions in the unactuated state.

[0062] It should be appreciated that the current embodiments disclosed herein, specifically the tab portions 232, 254 having interconnected bridge portions 274, 276, provide a number of improvements over actuators, such as HASEL actuators, that do not include tab portions 232, 254. Embodiments of the artificial muscle 200 that include two pairs of tab portions 232, 254 on each of the first and second electrodes 206, 208, respectively, reduce the overall mass and thickness of the artificial muscle 200, reduce the amount of voltage required during actuation, and the present solution reduces the overall volume of the artificial muscle 200 without reducing the size of the resulting force after actuation compared to known HASEL actuators that include annular electrodes having a uniform, radially extending width. More specifically, the tab portions 232, 254 of the artificial muscle 200 provide a zip-tape wave front that produces increased actuation power by providing localized and uniform hydraulic actuation of the artificial muscle 200 compared to HASEL actuators that include annular electrodes. Specifically, one pair of tab portions 232, 254 provides twice the amount of actuator power per unit volume compared to annular HASEL actuators, and two pairs of tab portions 232, 254 provide four times the amount of actuator power per unit volume. The bridge portions 274, 276 that interconnect the tab portions 232, 254 also limit buckling of the tab portions 232, 254 by maintaining a distance between adjacent tab portions 232, 254 during actuation. Because the bridge portions 274, 276 are integrally formed with the tab portions 232, 254, the bridge portions 274, 276 also prevent leakage between the tab portions 232, 254 by eliminating attachment locations that increase the risk of rupture.

[0063] In operation, when the artificial muscle 200 is actuated by providing a voltage, the expansion of the expandable fluid region 296 produces a force of up to 10 N / cm 3a force of 3 Newton-millimeters (N.mm) or more per volume of actuator, such as 4 N.mm or more per cubic centimeter of actuator volume, 5 N.mm or more per cubic centimeter of actuator volume, 6 N.mm or more per cubic centimeter of actuator volume, 7 N.mm or more per cubic centimeter of actuator volume, 8 N.mm or more per cubic centimeter of actuator volume, or the like. Providing a voltage can include generating a voltage, for example, in embodiments where the power source is a battery; converting a voltage, for example, in embodiments where the power source is a power adapter; or any other known or yet to be developed technique for preparing a voltage for application. In one example, artificial muscle 200 provides a resultant force of 5 N when actuated by a voltage of 9.5 kilovolts (kV). In another embodiment, artificial muscle 200 provides a strain of 440% under a load of 500 grams when actuated by a voltage of 10 kV.

[0064] Further, the size of first electrode 206 and second electrode 208 is proportional to the amount of displacement of dielectric fluid 298. Thus, when a greater displacement within expandable fluid region 296 is desired, the size of electrode pair 204 is increased relative to the size of expandable fluid region 296. It will be appreciated that the size of expandable fluid region 296 is defined by the center openings 246, 268 in first electrode 206 and second electrode 208. Thus, the degree of displacement within expandable fluid region 296 can alternatively or additionally be controlled by increasing or decreasing the size of center openings 246, 268.

[0065] Reference is now made to Figure 9 An actuation system 300 can be provided for operating an artificial muscle, such as artificial muscle 100, 200, between a non-actuated state and an actuated state. Thus, actuation system 300 can include a controller 302, an operating device 304, a power source 306, and a communication path 308. The various components of actuation system 300 will now be described.

[0066] The controller 302 includes a processor 310 and a non-transitory electronic memory 312 communicatively coupled to various components. In some embodiments, the processor 310 and the non-transitory electronic memory 312 and / or other components are included within a single device. In other embodiments, the processor 310 and the non-transitory electronic memory 312 and / or other components can be distributed among multiple devices communicatively coupled. The controller 302 includes a non-transitory electronic memory 312 that stores a set of machine-readable instructions. The processor 310 executes the machine-readable instructions stored in the non-transitory electronic memory 312. The non-transitory electronic memory 312 can include RAM, ROM, flash memory, a hard disk drive, or any device capable of storing machine-readable instructions so that the machine-readable instructions can be accessed by the processor 310. Thus, the actuation system 300 described herein can be implemented in any conventional computer programming language as pre-programmed hardware elements or a combination of hardware and software components. The non-transitory electronic memory 312 can be implemented as one memory module or multiple memory modules.

[0067] In some embodiments, the non-transitory electronic memory 312 includes instructions for performing the functions of the actuation system 300. The instructions can include instructions for operating the artificial muscle 100, 200 based on user commands.

[0068] The processor 310 can be any device capable of executing machine-readable instructions. For example, the processor 310 can be an integrated circuit, a microchip, a computer, or any other computing device. The non-transitory electronic memory 312 and the processor 310 are coupled to a communication pathway 308 that provides signal interconnectivity between various components and / or modules of the actuation system 300. Thus, the communication pathway 308 can communicatively couple any number of processors to one another and allow modules coupled to the communication pathway 308 to operate in a distributed computing environment. Specifically, each of the modules 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, such as, for example, electrical signals via an electrically conductive medium, electromagnetic signals via air, optical signals via an optical waveguide, and the like.

[0069] As schematically depicted in Figure 9 , the communication pathway 308 communicatively couples the processor 310 and the non-transitory electronic memory 312 of the controller 302 with various other components of the actuation system 300. For example, as depicted in Figure 9 , the actuation system 300 includes the processor 310 and the non-transitory electronic memory 312 communicatively coupled with the operating device 304 and the power source 306.

[0070] The operating device 304 allows a user to control the operation of the artificial muscle 100, 200. In some embodiments, the operating device 304 can be a switch, a toggle, a button, or any combination of controls used to provide user operation. As a non-limiting example, a user can actuate the artificial muscle 100, 200 into an actuated state by actuating a control of the operating device 304 to a first position. When in the first position, the artificial muscle 100, 200 will remain in the actuated state. The user can switch the artificial muscle 100, 200 into a non-actuated state by operating the control of the operating device 304 away from the first position and into a second position.

[0071] The operating device 304 is coupled to the communication path 308 such that the communication path 308 communicatively couples the operating device 304 to other modules of the actuation system 300. The operating device 304 can provide a user interface for receiving user instructions regarding a particular operational configuration of the artificial muscle 100, 200. Additionally, the user instructions can include instructions to operate the artificial muscle 100, 200 only under certain conditions.

[0072] The power source 306 (e.g., a battery) provides power to the artificial muscle 100, 200. In some embodiments, the power source 306 is a rechargeable direct current power source. It should be appreciated that the power source 306 can be a single power source or battery for providing power to the artificial muscle 100, 200. A power adapter (not shown) can be provided and electrically coupled via a wiring harness or the like for providing power to the artificial muscle 100, 200 by means of the power source 306. In effect, the power source 306 is a device that can receive power at one level (e.g., a first voltage, power level, or current) and output power at a second level (e.g., a second voltage, power level, or current).

[0073] In some embodiments, the actuation system 300 also includes a display device 314. The display device 314 is coupled to the communication path 308 such that the communication path 308 communicatively couples the display device 314 to other modules of the actuation system 300. The display device 314 can output notifications in response to an actuation state of the artificial muscle 100, 200 or a change in the actuation state of the artificial muscle 100, 200. Also, the display device 314 can be a touch screen that detects the presence and location of a tactile input on or adjacent to a surface of the display device 314 in addition to providing optical information. Thus, the display device 314 can include the operating device 304 and receive mechanical inputs directly on the optical outputs provided by the display device 314.

[0074] In some embodiments, the actuation system 300 includes network interface hardware 316 for communicatively coupling the actuation system 300 to a portable device 318 via a network 320. The portable device 318 can include, but is not limited to, a smart phone, a tablet computer, a personal media player, or any other electronic device that includes wireless communication functionality. It should be appreciated that when provided, the portable device 318 can be used to provide user commands to the controller 302 in place of the operating device 304. In this way, a user can be able to control or set programs for controlling the artificial muscle 100, 200 without utilizing controls of the operating device 304. Thus, the artificial muscle 100, 200 can be remotely controlled via the portable device 318 wirelessly communicating with the controller 302 over the network 320.

[0075] From the foregoing, it should be appreciated that an artificial muscle is defined herein having a pair of electrodes and one or more reinforcing members for providing increased stiffness of the artificial muscle toward an expandable fluid region at an opposing end of the pair of electrodes or a central portion of the pair of electrodes. This ensures that the artificial muscle is zipped inward to direct dielectric fluid into the expandable fluid region on demand.

[0076] It should be noted that the terms "substantially" and "approximately" can be used herein to represent the degree by which any quantitative comparison, value, measurement, or other representation can inherently vary. These terms are also used herein to represent the degree to which a quantitative representation can vary from a recited reference without causing a change in the basic function of the subject matter at issue.

[0077] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made therein without departing from the scope of the claimed subject matter. Furthermore, although various aspects of the claimed subject matter have been described herein, such aspects need not be used in combination. Accordingly, it is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

Claims

1. An artificial muscle comprising: a housing having an electrode region and an expandable fluid region; a pair of electrodes including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid contained within the housing; and a pair of reinforcement members positioned between the housing and at least one of the first electrode and the second electrode, a first reinforcement member of the pair of reinforcement members having a first length, a second reinforcement member of the pair of reinforcement members having a second length greater than the first length, the first reinforcement member positioned between the housing and the second reinforcement member, wherein the pair of reinforcement members increase a stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region, wherein the pair of electrodes 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. A pair of reinforcement members is disposed between the housing and each of the first electrode and the second electrode.

2. Artificial muscle according to claim 1, wherein, The housing is a flexible housing comprising an elastomeric material.

3. The artificial muscle according to claim 1, wherein, The housing comprises a biaxially oriented polypropylene layer.

4. The artificial muscle according to claim 3, wherein The housing comprises a pair of biaxially oriented polypropylene layers.

5. The artificial muscle of claim 4, wherein, Each reinforcement member comprises a biaxially oriented polypropylene layer.

6. The artificial muscle of claim 1, wherein, 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 interconnecting adjacent tab portions, and at least one of the first electrode and the second electrode comprises a center opening positioned between the two or more tab portions and encircling the expandable fluid region.

7. The artificial muscle of claim 1, wherein, 8. An artificial muscle comprising: a housing having an electrode region and an expandable fluid region; a pair of electrodes including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid contained within the housing; and a pair of reinforcement members positioned between the housing and each of the first electrode and the second electrode, the pair of reinforcement members increasing a stiffness of the housing in a direction from opposite edges of the electrode region toward the expandable fluid region, wherein a first reinforcement member of the pair of reinforcement members has a first length, a second reinforcement member of the pair of reinforcement members has a second length greater than the first length, and the first reinforcement member is positioned between the housing and the second reinforcement member; wherein the pair of electrodes is actuatable between a non-actuated state and an actuated state such that actuation from the non-actuated state to the actuated state causes a distance between the pair of electrodes proximate the opposite edges of the electrode region to decrease before a distance between the pair of electrodes proximate the expandable fluid region decreases. The housing comprises a pair of biaxially oriented polypropylene layers. Each reinforcement member comprises a biaxially oriented polypropylene layer.

9. The artificial muscle according to claim 8, wherein, ​ 10. The artificial muscle of claim 8, wherein, ​ 11. The artificial muscle of claim 8, wherein, 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, and at least one of the first electrode and the second electrode includes a center opening positioned between the two or more tab portions and encircling the expandable fluid region.

12. The artificial muscle of claim 11, wherein, Each of the two or more bridge portions of the at least one of the pair of reinforcing members interconnects adjacent tab portions of the at least one of the pair of reinforcing members, and at least one of the pair of reinforcing members includes a center opening positioned between the two or more tab portions and encircling the expandable fluid region.

13. A method for actuating an artificial muscle, the method comprising: providing a voltage using a power source electrically coupled to a pair of electrodes of an artificial muscle, the artificial muscle comprising: a housing having an electrode region and an expandable fluid region; the pair of electrodes including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid housed within the housing; and a pair of reinforcing members positioned between the housing and at least one of the first electrode and the second electrode, a first reinforcing member of the pair of reinforcing members having a first length, a second reinforcing member of the pair of reinforcing members having a second length greater than the first length, the first reinforcing member positioned between the housing and the second reinforcing member, the pair of reinforcing members increasing a stiffness of the housing in a direction from opposing edges of the electrode region toward the expandable fluid region, and applying the voltage to the pair of electrodes of the artificial muscle, thereby actuating the pair of electrodes from a non-actuated state to an actuated state to cause the dielectric fluid to be directed into the expandable fluid region of the housing and expand the expandable fluid region.

14. The method of claim 13, wherein, The housing 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 housing, the housing further including an unsealed portion surrounded by the sealed portion, wherein the electrode region and the expandable fluid region of the housing are disposed in the unsealed portion.

15. The method of claim 13, wherein, A pair of reinforcing members is disposed between the housing and each of the first electrode and the second electrode.

16. The method of claim 15, wherein, The housing and the pair of reinforcing members each include a biaxially oriented polypropylene layer.

17. The method of claim 13, wherein, Expanding the expandable fluid region generates a force per cubic millimeter of actuator volume greater than 4 N.mm. 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, and at least one of the first electrode and the second electrode includes a center opening positioned between the two or more tab portions and encircling the expandable fluid region. Each of the two or more bridge portions of the at least one of the pair of reinforcing members interconnects adjacent tab portions of the at least one of the pair of reinforcing members, and at least one of the pair of reinforcing members includes a center opening positioned between the two or more tab portions and encircling the expandable fluid region.

13. A method for actuating an artificial muscle, the method comprising: providing a voltage using a power source electrically coupled to a pair of electrodes of an artificial muscle, the artificial muscle comprising: a housing having an electrode region and an expandable fluid region; the pair of electrodes including a first electrode and a second electrode positioned in the electrode region of the housing; a dielectric fluid housed within the housing; and a pair of reinforcing members positioned between the housing and at least one of the first electrode and the second electrode, a first reinforcing member of the pair of reinforcing members having a first length, a second reinforcing member of the pair of reinforcing members having a second length greater than the first length, the first reinforcing member positioned between the housing and the second reinforcing member, the pair of reinforcing members increasing a stiffness of the housing in a direction from opposing edges of the electrode region toward the expandable fluid region, and applying the voltage to the pair of electrodes of the artificial muscle, thereby actuating the pair of electrodes from a non-actuated state to an actuated state to cause the dielectric fluid to be directed into the expandable fluid region of the housing and expand the expandable fluid region. The housing 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 housing, the housing further including an unsealed portion surrounded by the sealed portion, wherein the electrode region and the expandable fluid region of the housing are disposed in the unsealed portion. A pair of reinforcing members is disposed between the housing and each of the first electrode and the second electrode. The housing and the pair of reinforcing members each include a biaxially oriented polypropylene layer. Expanding the expandable fluid region generates a force per cubic millimeter of actuator volume greater than 4 N.mm.

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