Related Applications

[0001] This application claims the benefit of the priority of US application No. 61/192190 filed 15 September 2008 and entitled VARIABLE VOLUME GARMENTS, which is hereby incorporated by reference. Technical Field

[0002] The invention relates to variable volume garments. In particular embodiments, variable volume garments may be provided in the form of suits. Background [0003] Protective garments, typically protective suits, are often worn in extreme environments (e.g. in space, underwater or the like), in extreme or potentially extreme circumstances (e.g. when fighting fires, when racing cars, when participating in contact sports or the like) and in a variety of other circumstances. Protective suits may offer a variety of forms of protection. By way of non-limiting example, protective suits may offer insulation against temperature extremes, padding against impact, fire resistance and the like.

[0004] One drawback with some protective suits is that they are difficult to put on and take off. For example, so called "survival suits" used for marine rescue and the like can be tight fitting at least in some areas - e.g. in the cuffs at the neck, wrists and ankles. This tightness can protect the wearer by preventing cold water from entering the suit. While desirable from the perspective of protecting the wearer from cold water, the tightness of the suit can also make it difficult to put the suit on (i.e. to don the suit), particularly in emergencies where time is of the essence. This difficulty in donning the suit can, in some circumstances, defeat the purpose of the suit for use in rescue operations. Protective suits can also be difficult to remove (i.e. to doff).

[0005] For this and other reasons, there is a general desire for garments (e.g. suits) which are relatively easy to put on and/or to take off.

[0006] Some vehicles (e.g. spacecraft, jet airplanes and roller coasters) are capable of being operated in a manner which causes their passengers to experience so-called "g- forces". G-forces, actually a measure of the acceleration experienced by a body, can be experienced by humans in a variety of other circumstances. By way of non-limiting example, humans can experience g-forces upon impact with another body and when skydiving. Extreme accelerations can be difficult for the human body to endure and may contribute to g-induced loss of consciousness (g-LOC). G-LOC is caused by pooling of blood in regions of the body away from the brain, depriving the brain of blood. [0007] So-called anti-g suits have been developed to combat against g-LOC for jet pilots. Such anti-g suits typically incorporate bladders which are filled with gas or liquid when the pilot experiences extreme acceleration. When filled, these bladders apply pressure to the lower parts of the pilot's body, thereby restricting blood flow to the lower extremes of the pilot's body and attempting to maintain blood flow to the brain.

[0008] There is a general desire for garments (e.g. suits) capable of reducing the wearer's susceptibility to g-LOC and/or other issues associated with extreme accelerations.

[0009] hi some applications, it is desirable to influence the flow of blood and/or other materials in the human body. By way of non-limiting example, compression stockings may be used to reduce the chances of post-surgical and/or deep- vein venous thrombosis and/or lymphedema. Compression garments have also been used by athletes, who claim that such garments help prevent muscle vibration and help prevent injuries. [0010] There is a general desire for garments (e.g. suits) capable of influencing the flow of blood and/or other substances in the human body. Brief Description of the Drawings [0011] In drawings which depict non-limiting embodiments of the invention:

Figure 1 is a schematic depiction of a suit according to a particular embodiment of the invention wherein the suit is divided into a plurality of generally tubular sections;

Figures 2A and 2B are cross-sectional views of a dielectric electroactive polymer (EAP) structure in a relaxed state and under the application of an activating voltage; Figure 3 is an exploded isometric view of a generally tubular EAP structure according to a particular embodiment of the invention;

Figures 4A and 4B are cross-sectional views of the Figure 3 tubular EAP along the line 4-4 in a relaxed configuration (Figure 4A) and in an expanded configuration under the application of an activating voltage (Figure

4B);

Figures 5 A and 5B are cross-sectional views of a generally tubular section of a garment in an expanded configuration where the garment is relatively easy to don and to doff (Figure 5A) and in a normal configuration where the garment is relatively tight fitting (Figure 5B);

Figures 5C and 5D are cross-sectional views of a generally tubular section of a garment in an expanded configuration (Figure 5C) and in a contracted configuration (Figure 5D);

Figures 6 A and 6B are cross-sectional views of a pair of generally tubular sections of a garment in a first configuration;

Figure 6C is a cross-sectional view of the Figure 6 A garment section in an expanded configuration;

Figure 6D is a cross-sectional view of the Figure 6B garment section in a contracted configuration; Figure 7 is an exploded isometric view of a non-tubular EAP structure used in a generally tubular section of a garment according to a particular embodiment of the invention;

Figures 8 A and 8B are respectively cross-sectional views of the Figure 7 generally tubular garment section along the line 8-8 with relatively low (Figure 8A) and relatively high (Figure 8B) voltages applied to its EAP structure;

Figure 9 schematically illustrates a suit-type garment incorporating one or more non-tubular EAP structures;

Figure 10 is a cross-sectional view of a layered EAP structure according to a particular embodiment of the invention; - A -

Figures 1 IA is a perspective view of a EAP structure which may be incorporated into a garment according to another embodiment of the invention;

Figure 1 IB is a cross-sectional view of the Figure 1 IA EAP structure along the line HB; Figure 11C is a cross-sectional view of the Figure 1 IA EAP structure along the line HC;

Figures 12A and 12B are cross-sectional views of a garment incorporating the Figure 1 IA EAP structure in a normal configuration where the garment is relatively tight fitting (Figure 12A) and an expanded configuration where the garment is relatively easy to don and to doff (Figure

12B).

Detailed Description

[0012] Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0013] Aspects of the invention provide garments capable of varying in volume to perform particular functions and corresponding methods of using such garments. Figure 1 depicts a suit 10 according to a particular embodiment wherein suit 10 comprises a plurality of generally tubular garment sections. In the illustrated embodiment, suit 10 comprises the following generally tubular garment sections: neck section 12, torso section 14, right and left arm sections 16A, 16B (collectively and individually arm sections 16), right and left arm cuffs 17 A, 17B (collectively and individually arm cuffs 17 or wrist cuffs 17), pelvic section 18, right and left leg sections 2OA, 2OB (collectively and individually leg sections 20) and right and left leg cuffs 21A, 21B (collectively and individually leg cuffs 21 or ankle cuffs 21). [0014] hi the schematic illustration of Figure 1, garment sections (i.e. neck section 12, torso section 14, arm sections 16, arm cuffs 17, pelvic section 18, leg sections 20 and leg cuffs 21) are toroidal in shape to provide bores through which body parts may extend and have annular cross-sections. While garment sections are described herein as being "generally tubular", it will be appreciated that this description represents a convenient description for the purposes of explanation. While generally tubular garment sections provide bores through which body parts may extend, generally tubular garment sections are not limited to cylindrical or toroidal shapes having circular or annular cross-sections and may have a variety of suitable cross-sectional shapes capable of accommodating body parts. In one particular example embodiment, generally tubular garment sections may be elliptically annular in cross-section. Generally tubular garment sections are not limited to having constant cross-sectional shapes and may comprise sections whose cross-sections vary to fit the human body. In one particular embodiment, generally tubular garment sections may have a one- sheeted hyperboloid-type shape where the axial extremities of the generally tubular garment sections have larger cross-sectional dimensions than an axial interior of the garment sections. [0015] Garments according to particular embodiments may comprise any one or more sections of suit 10. By way of non-limiting example, garments according to particular embodiments may comprise leggings which include one or more leg sections 20, pant- like suit bottoms which include leg sections 20, leg cuffs 21 and pelvic section 18 and or shirt-like suit tops which include neck section 12, torso section 14, arm sections 16 and arm cuffs 17.

[0016] hi some embodiments, any one or more of the generally tubular sections of suit 10 may be subdivided into other portions (not explicitly shown in Figure 1). For example, arm sections 16 may be subdivided into upper and lower arm portions and leg sections 20 may be subdivided into upper and lower leg portions. Similarly, torso section 14 and/or pelvic section 18 may be subdivided to provide waist cuffs - e.g. at the lower extremity of torso section 14 and/or at the upper extremity of pelvic section 18. Such subdivided portions may or may not be generally tubular in shape and may have cross-sections which vary to fit the human body. [0017] Garments (e.g. suit 10 and/or various sections of suit 10) according to particular embodiments are capable of varying in volume (e.g. in the space they enclose) by expanding and contracting to achieve particular objectives. Garments according to particular embodiments provide variable volume for one or more of tubular neck section 12, torso section 14, arm sections 16, arm cuffs 17, pelvic section 18, leg sections 20, leg cuffs 21 and/or sub-divided portions of these sections. In some embodiments, such variable volume section(s) and/or sub-divided portions of section(s) may be individually controllable - i.e. such that particular section(s) and/or sub-divided portion(s) of section(s) can be expanded in volume while other section(s) and/or sub-divided portion(s) of section(s) can be caused to contract. [0018] In particular embodiments, the volume expansion and contraction of a particular section of suit 10 may be implemented principally by corresponding expansion and contraction of the section in generally radial directions - e.g. in directions oriented generally orthogonal to the longitudinal axis of the generally tubular section. Similarly, for a sub-divided portion of a section(s) which is generally tubular in shape, the volume expansion and contraction may be implemented by corresponding expansion or contraction of the portion in generally radial directions. Such radially oriented expansion and/or contraction is not limited to strictly radial directions in the Euclidean geometric sense and may correspond with expansion and/or contraction of the area bounded by the cross-sectional perimeter of the generally tubular section or portion. [0019] Garments according to particular embodiments of the invention incorporate dielectric electroactive polymers (dielectric EAPs). Dielectric EAPs may comprise polymers whose shape is modified under the influence of an applied voltage. Dielectric EAPs may include, without limitation, structures currently referred to in the art as dielectric elastomers, piezoelectric elastomers, eletrostrictive polymers and liquid crystal elastomers. Dielectric EAPs may include any subset of these structures. [0020] The general operation of a dielectric EAP structure 50 is shown in Figures 2A and 2B (collectively, Figure 2). In the illustrated embodiment, dielectric EAP structure 50 comprises a dielectric elastomer. As shown in Figure 2, EAP structure 50 comprises a pair of relatively conductive layers 52 A, 52B (collectively, conductors 52) located on either side of a relatively non-conductive dielectric material 54. [0021] Dielectric material 54 may comprise a suitable polymer elastomer and/or a suitable acrylic elastomer, although other suitable materials could be used to provide dielectric material 54. Conductors 52 may comprise compliant material(s) and may provide compliant electrodes. Conductors 52 may be formed by doping or otherwise combining dielectric material 54 with suitable additive materials (e.g. carbon particles, silver particles, gold particles or the like) to render the doped layers conductive. In other embodiments, conductors 52 may be provided by coating suitably conductive material onto polymer-based dielectric 54. The conductive material used to provide compliant conductors 52 may be fabricated by adding micro-particles to suitable elastomeric materials. In one particular embodiment, compliant electrodes 52 may be formed by implanting gold ions (or other suitable particles) into Polydimethylsiloxane (or other suitable base materials) as described by Niklaus et al. in "Microstructure of 5 KeV Gold implanted Polydimethylsiloxane", Scripta Materialia 59 (2008) 893-896 which is hereby incorporated herein by reference. [0022] Structure 50 is electrically connected to a voltage source V via a switch 56. hi the configuration of Figure 2 A, switch 56 is connected between nodes 58 and 60 and voltage source V is decoupled from conductors 52. Li the configuration of Figure 2B, switch 56 is connected between nodes 58 and 62, such that the voltage V appears between conductors 52 which together act as a capacitor to produce an electric field in dielectric material 54. [0023] In the Figure 2B configuration, conductors 52 acquire opposing electric charge and are consequently attracted toward one another. As may be seen by comparing Figures 2A and 2B, this attractive force compresses dielectric material 54 in the z direction. In the Figure 2A configuration, structure 50 has a z dimension shown as Z ₁ and transverse (x, y) dimensions X ₁ , Y ₁ (only X ₁ being visible in the Figure 2 A cross- section). In Figure 2B, when the voltage V is applied to structure 50 and conductors 52 are attracted to one another in the z direction, the z dimension of dielectric material 54 shrinks to the reduced thickness Z ₂ . Since the volume of dielectric material 54 remains approximately constant under the Coulombic pressures caused by the applied voltage (at least at the pressures of interest), dielectric material 54 expands in at least one of the transverse (x, y) dimensions if the system is not constrained. This expansion is shown schematically in Figures 2 A and 2B by the increase in the x dimension width of dielectric material 54 from the initial width X ₁ (Figure 2A) to the increased width X ₂ (Figure 2B).

[0024] The direction of expansion of dielectric material 54 under the influence of voltage V can be controlled by imposing suitable constraints - e.g. structures that will not move or deform (or at least be relatively immobile or rigid) under the range of forces created by voltage V and the attraction of conductors 52 toward one another. For example, in the illustrated embodiment of Figures 2 A and 2B, constraining structures (not shown) may be provided to prevent expansion of dielectric material in the y direction (i.e. into and out of the page in the Figure 2 view). With such constraining structures, the shape change of dielectric material 54 can be constrained to compression in the z direction (from Z ₁ (Figure 2A) to Z ₂ (Figure 2B)) and corresponding expansion in the x direction (from X ₁ (Figure 2A) to X ₂ (Figure 2B)). [0025] Dielectric EAP structure 50 may be used as an actuator by harnessing the deformation of dielectric material 54 and causing it to perform work (e.g. by interacting with some other object). It will be appreciated that when dielectric EAP structure 50 is used as an actuator, there is a general trade-off which relates to the Young's modulus characteristic of dielectric material 54. When dielectric material 54 is relatively stiff, it will be resistant to the compressive forces of conductors 52 attracted to one another by the application of voltage V. Consequently, for a given voltage V, the magnitude of the deformation of dielectric material 54 will be correspondingly low. When dielectric material 54 is relatively soft, it will be easily compressed by the attraction of conductors 52 to one another, but will have a correspondingly reduced capacity to perform work on another object. [0026] Some techniques for fabricating dielectric EAP structure are described by Pelrine et al. in "High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%", Science, Vol. 287, No. 5454, 4 February 2000, pp. 836-839, which is hereby incorporated herein by reference. Particular embodiments of the invention may incorporate any such techniques or any suitable portions thereof. [0027] Dielectric EAPs of the type shown in Figures 2 A and 2B differ from so-called ionic EAPs. Ionic EAPs generally comprise a pair of electrodes on either side of an ionically conductive electrolyte-containing region. Ionic EAPs also permit shape changes under the influence of electrical stimulation. However, ionic EAPs change shape because of the movement of ions within the electrolyte region and, consequently, require continuous energy input to maintain the EAP structure in a given shape. [0028] As discussed above, suit 10 and garments fabricated from one or more sections of suit 10 comprise one or more generally tubular sections (e.g. neck section 12, torso section 14, arm sections 16, arm cuffs 17, pelvic section 18, leg sections 20 and leg cuffs 21). Figure 3 shows a partially exploded view of generally tubular shaped dielectric EAP structure 80 which may be incorporated into a section of a garment according to a particular embodiment of the invention. While EAP structure 80 is described as "generally tubular", it will be appreciated that this description represents a convenient description for the purposes of explanation. In general, EAP structure 80 may have any of the shapes described above for the generally tubular garment sections. EAP structure 80 comprises conductor layers 82A, 82B (collectively, conductors 82) which, in the illustrated embodiment, are fabricated to provide generally annular shaped cross-sections and which are located on the interior and exterior of dielectric material 84 which may also be fabricated to provide a generally annular shaped cross-section. In the Figure 3 view, only conductor 82A is visible and conductor 82B is located in bore 86 of dielectric material 84. In the illustrated embodiment, generally tubular shaped EAP structure 80 also comprises constraint structures 88A, 88B (together, constraint structures 88) which limit the deformation of structure 80 in the axial directions shown by double-headed arrow 90. Constraint structures 88 may be located at the axial extremities of EAP structure 80 in regions not covered by conductor layers 82. [0029] hi one particular embodiment, tubular EAP structure 80 may be fabricated by starting with a generally flat piece of elastomeric material (e.g. silicone and/or acrylic- based elastomeric material) which will form dielectric material 84 and coating (e.g. by painting, smearing, spraying or the like) a relatively conductive material onto the generally planar sides of the elastomeric material to provide conductors 82. In one exemplary embodiment, the relatively conductive material may be provided by silicone (or other base material), diluted by a suitable solvent and blended with carbon powder comprising carbon micro-particles. In one particular embodiment, such silicone may include TC-5005 silicone AfB-C available from BJB Enterprises Inc., U.S.A. and the carbon microparticles may comprise CAF 4 available from Rhodorsil, France and/or Vulcan XC 72R available from Carbocrom, Italy, hi another particular embodiment, the relatively conductive material may be provided by ion bombardment of suitable base materials, as described in Niklaus et al. in "Microstructure of 5 KeV Gold implanted Polydimethylsiloxane", Scripta Materialia 59 (2008) 893-896. Other materials and/or techniques may also be used to provide and/or to fabricate EAP structures capable of providing the characteristics described herein. [0030] Next, the generally flat structure may be cut to size (if required) and bent to provide a generally tubular shape. The edges of the flat structure may be attached to one another using any suitable technique. In one exemplary embodiment, the edges of the flat structure are bonded together with silicone. Other techniques could be used to attach the edges of the flat structure to form a tube. By way of non-limiting example, such techniques may include stapling the edges together, sewing the edges together, applying another form of adhesive and/or the like.

[0031] hi other embodiments, it may be desirable to fabricate EAP structure 80 using other techniques. Examples of suitable techniques include extrusion, injection molding and blow molding. [0032] Constraint structures 88 may be fabricated from suitable materials, such as plastic or relatively hard polymer, for example. Other suitable materials could also be used. Constraint structures 88 may be designed such that they achieve a compromise between being sufficiently flexible to maintain comfort and to facilitate activity of the wearer, but also function to constrain axial deformation of tubular shaped EAP structure 80 as described herein. Constraint structures 88 are not limited to the shape shown in the illustrated view and may be provided with other suitable shapes. Constraint structures 88 may be coupled to the rest of tubular EAP structure 80 using any suitable technique. In one exemplary embodiment, constraint structures 88 are coupled to the rest of EAP structure 80 by silicone bonding. Other suitable fastening techniques could be used for this purpose, such as, by way of non-limiting example, staples, rivets, another form of fastener, another form of adhesive and/or the like. [0033] Charge may be carried to conductors 82 using wires. Wires may make direct electrical contact with conductors 82 or may be plugged into suitable electronic connectors (not shown) which may in turn be electrically connected to conductors 82. Non-limiting examples of techniques for electrically connecting to conductors 82 include integrating electrical contacts and/or electrical connectors for wires into conductors 82 during the fabrication thereof, soldering electrical contacts onto conductors 82 and/or bonding electrical contacts onto conductors 82 using silicone or other suitable adhesives. [0034] Figures 4 A and 4B respectively show schematic cross-sectional views of the Figure 3 EAP structure 80 (along the line 4-4) in the absence of an applied voltage and under the influence of an applied voltage V. In the Figure 4 A configuration, switch 92 is connected between nodes 94 and 96. Consequently, any potential difference between conductors 82A, 82B is dissipated across resistor R and structure 80 adopts a first shape shown in Figure 4A. [0035] When switch 92 is connected between nodes 94 and 98 (as shown in Figure 4B), the voltage V is asserted between conductors 82 A and 82B. This potential difference creates an electric field in dielectric material 84 and causes conductors 82A, 82B to be attracted toward one another in generally radial directions shown by double-headed arrow 99. The force of attraction of conductors 82 A, 82B toward one another causes a corresponding deformation of dielectric material 84. However, constraint structures 88A, 88B restrict the ability of dielectric material 84 to expand in axial direction 90 (i.e. into or out of the page in the views of Figures 4 A, 4B - see Figure 3). Consequently, dielectric material 84 is forced to expand in generally radial direction 99 such that the circumference of structure 80 (i.e. the distance around its perimeter) increases.

[0036] In particular embodiments, generally tubular dielectric EAP structures similar to structure 80 may be incorporated into one or more sections (e.g. neck section 12, torso section 14, arm sections 16, arm cuffs 17, pelvic section 18, leg sections 20 and/or leg cuffs 21) or one or more portions of one or more sections of a garment. Garments according to some embodiments of the invention comprise a flexible base material capable of being deformed (e.g. stretched or compressed) by the operation of EAP structures. In some embodiments, such garments may be relatively tight fitting to the body of the individual.

[0037] One or more generally tubular EAP structures may be connected to or otherwise located adjacent to corresponding portions of a garment. In some embodiments, generally tubular EAP structures may be fabricated using fibers which are directly woven or otherwise integrated with or formed into the material of the garment. In other embodiments, one or more generally tubular EAP structures may be mechanically connected to the material used to provide the garment (e.g. by stitching, adhesive or other suitable mechanical connection). One or more generally tubular EAP structures may be connected to or otherwise located adjacent to an interior or an exterior of the garment or may be connected or otherwise located between layers of the garment. In some embodiments, generally tubular EAP structures may be fabricated from materials that have suitable characteristics such that the EAP structures themselves can make up the fabric of the garment or a portion of the garment.

[0038] Particular embodiments of the invention provide garments for which it is desired that the garment (or at least some section(s) or portion(s) of the garment) fit relatively tightly to the body of the wearer. By way of non-limiting example, such garments may include wetsuits, dry suits, survival suits for emergency applications or the like, where a relatively tight fit is desirable to protect and/or comfort the wearer against cold water which may leak between the suit and the wearer's body. One or more generally tubular sections (e.g. neck section 12, torso section 14, arm sections 16, arm cuffs 17, pelvic section 18, leg sections 20 and/or leg cuffs 21) of such garments may comprise one or more corresponding generally tubular EAP structures. Suitable voltages may be applied to one or more of such generally tubular EAP structures causing their circumferences to increase and making it easier for a person to don the garment (i.e. to put the garment on). Once the garment is on, the voltage may be removed in whole or in part from the EAP structure(s), such that the garment shrinks down to fit tightly to the wearer's body. In particular embodiments, suitable EAP structures may be provided at one or more of arm cuffs 17, leg cuffs 21 and neck section 12 of garments to prevent the ingress of cold water when voltage is removed. Suitable voltage may additionally or alternatively be applied again to expand the circumferences of generally tubular EAP structures, making it easier to doff the garment (i.e. to take the garment off).

[0039] Figures 5 A and 5B show cross-sectional views of a generally tubular section 100 of a garment 10OA which incorporates a generally tubular EAP structure 100B. Tubular section 100 of garment IOOA may comprise an arm cuff, for example. In the illustrated embodiment, generally tubular EAP structure IOOB is located between exterior garment layer 116A and interior garment layer 116B and may be connected to one or both of garment layers 116A, 116B (e.g. by stitching or other mechanical connection). In particular embodiments, one or both of garment layers 116 A, 116B may be resiliently stretchable and/or otherwise deformable. In particular embodiments, one or both of garment layers 116 A, 116B may comprise neoprene. In other embodiments, garment IOOA can comprise different numbers of garment layers and EAP structure IOOB may be located interior to, exterior to or between such garment layers, hi some embodiments, generally tubular EAP structure IOOB may be fabricated from materials that have suitable characteristics such that EAP structure IOOB itself can make up the fabric of garment IOOA or a portion thereof. [0040] Figure 5 A shows the configuration of section 100 of garment IOOA when garment IOOA is being donned and/or doffed, hi the Figure 5 A configuration, switch 106 is connected between nodes 108, 110 such that the voltage V is applied between conductive layers 102 A, 102B of EAP structure IOOB. The application of voltage V causes conductive layers 102A,102B to be attracted toward one another in generally radial directions 99, compressing (e.g. squishing) dielectric material 104 and causing an increase in the circumference of EAP structure IOOB. Figure 5 A shows a portion 114 of the wearer's body. It can be seen that in the configuration of Figure 5 A, body portion 114 fits easily within the bore 118 of generally tubular section 100 of garment IOOA, making it relatively easy to don and/or doff garment IOOA. [0041] Figure 5B shows the configuration of generally tubular section 100 of garment IOOA after it has been donned by the wearer, hi the Figure 5B configuration, switch 106 is connected between nodes 108, 112 such that voltage V is removed from conductive layers 102 A, 102B of EAP structure IOOB. When voltage V is removed, the attraction between conductive layers 102 A, 102B decreases, resulting in an increase in the thickness of dielectric material 104 in radial directions 99 and a corresponding decrease in the circumference of EAP structure 10OB. It can be seen that in the configuration of Figure 5B, bore 118 of generally tubular section 100 of garment 100 A fits relatively tightly against body portion 114.

[0042] hi particular embodiments, voltages may be selectively applied to generally tubular EAP structures in a suitable order. For example, in a garment comprising neck section 14, arm sections 16 and torso section 18, when donning the garment it may be desirable to apply voltages first to arm sections 16 and then to subsequently apply voltages to neck section 14 and torso section 18. This will allow an increase in the volume of arm sections 16 first (e.g. for inserting arms into the garment) and then a subsequent increase in volume of neck section 14 and torso section 18 (e.g. for pulling the garment over the head and onto the wearer's torso). Similarly, when removing the garment it may be desirable to apply voltages first to neck section 14 and torso section 18 and then to subsequently apply voltages to arm sections 16. Such controlled application of voltages may be implemented by a suitably configured controller and/or user interface unit (not explicitly shown), hi one such embodiment, a user interface unit may comprise a switch or other suitable user-configurable input corresponding to each controllable section of the garment wherein one configuration of the switch applies a voltage to a corresponding EAP and the other configuration of the switch removes the applied voltage. Those skilled in the art will appreciate that there are a variety of ways to effect a suitable controller and/or user interface unit for selective application of voltages. [0043] Particular embodiments of the invention provide adjustable-fit garments wherein the size of the garment or one or more sections of the garment or one or more portions of sections of the garment may be adjusted by applying a suitable voltage level to generally tubular EAPs incorporated into the garment. For example, for individuals with a large chest it may be desirable to increase the size of torso section 18 of the garment by imparting a suitable voltage on a corresponding generally tubular EAP incorporated into torso section 18. It will be appreciated that larger voltages applied between the conductive layers of generally tubular EAP structures correspond to larger increases in the circumference of the generally tubular EAP structures. [0044] Figures 5C and 5D show cross-sectional views of generally tubular section 100 of garment IOOA which incorporates generally tubular EAP structure IOOB configured for adjustable-fit operation. Tubular section 100 of garment IOOA may comprise a chest section, for example. Section 100 of garment IOOA and EAP structure IOOB are substantially similar to that of Figures 5 A and 5B, except that EAP structure IOOB is connected to a variable voltage source. In the configuration of Figure 5C, conductive layers 102 A, 102B of EAP structure IOOB are connected to a relatively high voltage level V ₁ , causing the circumference of EAP structure IOOB to be relatively large and resulting in a corresponding loose fit of section 100 of garment IOOA relative to body part 114. In the configuration of Figure 5D, conductive layers 102A, 102B of EAP structure IOOB are connected to a relatively low voltage level V ₂ , causing the circumference of EAP structure IOOB to be relatively small and resulting in a corresponding tight fit of section 100 of garment IOOA relative to body part 114.

[0045] In particular embodiments, variation of the voltage levels may be controlled by a suitably configured controller and/or user interface unit. For example, a user interface unit may comprise a suitable user-configurable input corresponding to each controllable section of the garment wherein a configuration of the user-configurable input applies a corresponding voltage to a corresponding EAP structure. Non-limiting examples of suitable user inputs include dials, sliders or the like. Such user-inputs may provide a number of discrete levels or may be continuously variable. Those skilled in the art will appreciate that there are a variety of ways to effect a suitable controller and/or user interface unit. [0046] Other aspects of the invention provide garments comprising generally tubular EAP structures similar to generally tubular EAP structure 80 (Figures 3, 4 A, 4B) wherein one or more sections of the garment or one or more portions of such sections expand and contract to influence the flow of blood and/or other materials (e.g. fluid materials) in the human body. Such garments may be used, for example, to counteract the adverse effects of extreme acceleration (g-forces), for medical applications (e.g. prevention of venous thrombosis), for athletic applications, for comfort of the wearer and/or for rehabilitation applications.

[0047] Particular embodiments of this aspect of the invention are provided in the form of full body suits similar to suit 10 (Figure 1), although this is not necessary and other embodiments may be provided in the form of garments comprising any one or more generally tubular sections similar to any one or more of the generally tubular sections of suit 10. This description uses the term positive pressure to refer to pressures greater than that of the outward pressure exerted by a wearer's body and the term negative pressure to refer to pressures less than that of the outward pressure exerted by a wearer's body, hi accordance with these terms, the application of positive pressure by a garment to a wearer's body corresponds with net forces that will tend to compress the body and the application of negative pressure by a garment to the wearer's body corresponds with net forces which will allow the body to expand. [0048] In some circumstances, it may be desirable to increase the flow of blood and/or other materials (e.g. other bodily substances) to certain portions of the body and/or to limit the flow of blood and/or other materials to other portions of the body. For example, so-called positive g-forces (+Gz) experienced by astronauts, pilots and the like may cause an increase in blood flow to lower portions of the body (e.g. the legs) and may deprive upper portions of the body (e.g. the head and torso) from receiving sufficient blood flow, hi some circumstances it is desirable to counteract the effects of +Gz forces - e.g. by effecting conditions which, in the absence of other factors, would tend to increase blood flow to upper portions of the body and/or decrease blood flow to lower portions of the body. Similarly, it may be desirable to counteract the effects of so-called negative g-forces (-Gz) - e.g. by effecting condition which, in the absence of other factors, would tend to increase blood flow to lower portions of the body and/or decrease blood flow to upper portions of the body. [0049] Some embodiments of the invention provide garments are controllable to apply positive pressure to one or more first portions of the body and/or negative pressure to one or more second portions of the body. Such garments may compress the first body portions, thereby tending to decrease the flow of blood to such first body portions and/or such garments may allow the second body portions to expand, thereby tending to increase the flow of blood and/or other materials to such second body portions.

[0050] Figures 6A, 6B respectively depict cross-sectional views of a pair of generally tubular sections 200, 220 of a garment 201 which respectively incorporate generally tubular EAP structure 203 and generally tubular EAP structure 223. By way of non- limiting example used for the purposes of explanation, generally tubular section 200 and EAP structure 203 (Figure 6A) may be part of a chest section 14 of garment 201 and generally tubular section 220 and EAP structure 223 (Figure 6B) may be part of a leg section 20 of garment 201 - i.e. body part 214 located in section 200 (Figure 6A) may be the wearer's chest and body part 234 located in section 220 (Figure 6B) may be one of the wearer's legs. As explained in more detail below, in the illustrated view of Figures 6A and 6B ₅ sections 200, 220 are in an intermediate configuration from which sections 200, 220 may be either expanded or contracted by varying the applied voltages. Contracting sections 200, 220 may correspondingly compress body parts 214, 234 and expanding sections 200, 220 may correspondingly allow body parts 214, 234 to expand.

[0051] In the illustrated embodiment, generally tubular EAP structure 203, 223 of Figures 6 A, 6B are respectively located between exterior garment layers 216A, 236 A and interior garment layers 216B, 236B and may be connected to one or both of garment layers 216 A, 236 A, 216B, 236B (e.g. by stitching or other mechanical connection), hi particular embodiments, one or both of garment layers 216A, 236 A, 216B, 236B may be resiliently stretchable and/or otherwise deformable. hi other embodiments, sections 200, 220 of garment 201 can comprise different numbers of garment layers and EAP structures 203, 223 may be located interior to, exterior to or between such garment layers. In some embodiments, generally tubular EAP structures203, 223 may be fabricated from materials that have suitable characteristics such that the EAP structures 203, 223 themselves can make up the fabric of garment 201 or a portion thereof. [0052] hi the illustrated views of Figures 6 A and 6B, an intermediate voltage V _{1 A} is applied to conductive layers 202 A, 202B of EAP structure 203 and an intermediate voltage V _{1 B} is applied to conductive layers 222A, 222B of EAP structure 223. Voltages V _{1 A} , V _{1 B} may be selected to provide desired levels of compression of dielectric materials 204, 224, corresponding circumferences of EAP structures 203, 223 and corresponding levels of fit for sections 200, 220 of garment 201 on body parts 214, 234. In the illustrated embodiment, the pressure caused by the application of intermediate voltages V _{1 A} , V _{1 B} on body parts 214, 234 may be neutral or slightly positive. In other embodiments, different pressure levels can be used for the intermediate voltage configurations of Figures 6 A, 6B.

[0053] In one exemplary circumstance, it is desired to decrease the pressure applied by section 200 of garment 201 to body part 214 (Figure 6A) and to increase the pressure applied by section 220 of garment 201 to body part 234 (Figure 6B). For example, where body part 214 is a chest and body part 234 is a leg, such a circumstance may be desirable to counteract the effects of +Gz forces. Such +Gz forces would tend increase blood flow to lower body portions (e.g. legs) and decrease blood flow to upper body portions (e.g. the chest and head), hi particular embodiments, counteracting such +Gz forces can involve applying negative pressure to body part 214 (e.g. the chest) and positive pressure to body part 234 (e.g. the leg), which may in turn tend to increase blood flow to the upper parts of the body and to decrease blood flow to the lower parts of the body. [0054] This circumstance is illustrated in Figures 6C and 6D. Figure 6C depicts a cross-sectional view of section 200 of garment 201 when corresponding EAP structure 203 is expanded to apply negative pressure to body part 214. Figure 6D shows a cross-sectional view of section 220 of garment 201 when corresponding EAP structure 223 is shrunken to apply positive pressure to body part 224. [0055] hi the illustrated embodiment of Figure 6C, expanding EAP structure 203 to apply negative pressure to body part 214 comprises applying a voltage V _{2 A} between conductive layers 202 A, 202B of EAP structure 203, where V _{2 A} >V _{t A} . Since V _{2 A} >V _{j A} , the application of V _{2 A} to conductive layers 202 A, 202B (as shown in Figure 6C) causes conductive layers 202A, 202B to be further attracted to one another (relative to the configuration of Figure 6A), thereby deforming dielectric material 204 and causing the circumference of EAP structure 203 to increase. The increase in circumference of generally tubular EAP structure 203 causes body part 214 to experience negative pressure. Under the influence of negative pressure, body part 214 may expand, as can be seen by comparing Figures 6A and 6C. [0056] In the illustrated embodiment of Figure 6D, shrinking EAP structure 223 to apply positive pressure to body part 234 comprises applying a voltage V _{2 B} between conductive layers 222 A, 222B of EAP structure 223, where V _{2 B} <V _{j B} . Since V _{2 B} <Vi _B , the application of V _{2 B} to conductive layers 222 A, 222B (as shown in Figure 6D) reduces the attractive force between conductive layers 222A, 222B (relative to the configuration of Figure 6B), thereby allowing dielectric material 224 to expand and causing the circumference of EAP structure 223 to contract. The contraction of the circumference of generally tubular EAP structure 223 exerts positive pressure on body part 234. Under the influence of positive pressure, body part 234 shrinks, as can be seen by comparing Figures 6B and 6D. [0057] Thus, the application of voltages V _{2 A} >V _{1 A} to EAP structure 203 (Figure 6C) and V _{2 B} <V, _B to EAP structure 223 (Figure 6D) achieves the desired effect of applying negative pressure to body part 214 (e.g. the chest) and positive pressure to body part 234 (e.g. the leg), which may in turn allow circumferential expansion of body part 214, circumferential contraction of body part 234 and a corresponding increase blood flow to certain parts of the body and decrease blood flow to other parts of the body, hi the case where body part 214 is the wearer's chest and body part 234 is one of the wearer's legs, such expansion and contraction of garment 201 may be used to counteract +Gz forces. V _{2 B} may be zero volts which may be effected, for example, by connecting switch 226 between nodes 228 and 232 of Figure 6D. [0058] It will be appreciated by those skilled in the art that the invention also encompasses applying a positive pressure to body part 214 (relative to the configuration of Figure 6A) by applying a third voltage V _{3 A} (where V _{3 A} <V _{j A} ) to EAP structure 203 and/or applying a negative pressure to body part 234 (relative to the configuration of Figure 6B) by applying a third voltage V _{3 B} (where V _{3 B} >V _{j B} ) to EAP structure 223. This may cause circumferential contraction of body part 214 and circumferential expansion of body part 234. Where body part 214 is a chest and body part 234 is a leg, such a scenario (negative pressure on body part 234 and positive pressure on body part 214) may be useful to counteract -Gz force. Furthermore, the invention also encompasses applying only positive pressure to one or more body parts (i.e. pressure above the intermediate pressures in the condition of Figures 6 A, 6B) or applying only negative pressure to one or more body part (i.e. pressure below the intermediate pressures in the condition of Figures 6A, 6B) and to thereby influence the flow of blood or other materials within the body of the wearer.

[0059] In some embodiments, garment sections may be designed to maintain air-tight contact between the skin of the wearer and the interior surface of the garment such that the skin of the wearer is actually pulled outwardly upon the application of negative pressure. As an illustrative, but non-limiting example, consider the case of section 200 of garment 201 which encompasses generally tubular EAP structure 203. The voltage V _{1 A} applied in the intermediate state (Figure 6A) may be selected such that contact is maintained between the interior surface 216B of section 200 and the skin of body part 214 and that there is substantially no (or very little) air between interior surface 216B and the skin of body part 214. [0060] Circumferential bands or cuffs (not explicitly shown) may be located at or near the axial ends (e.g. the top and bottom) of section 200 and EAP structure 203. Such circumferential bands may comprise elastomeric material that maintains positive pressures on body part 214 and prevents or at least mitigates the flow of air into the space between from the interior surface 216B of section 200 and the skin of body part 214. Such circumferential bands or cuffs may additionally or alternatively comprise straps (e.g. velcro straps or straps comprising suitable fasteners) to facilitate tightening the circumferential bands to provide positive pressure, hi some embodiments, such circumferential bands or cuffs can themselves comprise EAP structures similar to those disclosed in the remainder of this description with suitably shortened axial dimensions. In other embodiments, circumferential bands or cuffs are not expressly required and the garment or section(s) of the garment may otherwise be at least substantially air-tight. For example, the garment itself or section(s) of the garment may be substantially air-tight because the garment comprises a relatively tight fitting deformable material that maintains contact with the body (e.g. the neoprene of a wetsuit, stretchable rayon or spandex or the like) and also, if required or desired, an air-tight layer (e.g. rubber, silicone or the like). [0061] Since no air can get into the region between the interior surface 216B of section 200 and the skin of body part 214, increasing the voltage from V _{1 A} (Figure 6A) to V _{2 A} (Figure 6C) and the associated negative pressure are then accompanied by the creation of a vacuum between the interior surface 216B of section 200 and the skin of body part 214. This vacuum acts to pull the skin of body part 214 radially outwardly (see arrow 99 of Figure 6C) to maintain contact between the interior surface 216B of section 200 and the skin of body part 214. In particular embodiments, a suitable gel, liquid and/or adhesive may be applied between the interior surface 216B of section 200 and the skin of body part 214. Such gel, liquid and/or adhesive may improve the air-tightness of the contact between interior surface 216B of section 200 and the skin of body part 214 and/or may otherwise help to maintain contact therebetween to pull the skin of body part 214 outwardly during application of negative pressure. In embodiments comprising liquid, gel or adhesive between the garment and the wearer's skin, circumferential positive pressure bands may not be required.

[0062] hi particular embodiments, a user interface unit may comprise a suitable user- configurable input (e.g. a dial, knob, slider or the like) corresponding to each controllable section of the garment wherein a configuration of the user-configurable input applies a corresponding voltage to a corresponding EAP structure. Such a user- input may provide a number of discrete levels or may be continuously variable. Those skilled in the art will appreciate that there are a variety of ways to effect a suitable user interface unit.

[0063] In other embodiments, the application of voltages to the various controllable sections of the garment is controlled automatically by a controller which receives information from one or more sensors (e.g. acceleration information from sensors such as accelerometers, gyroscopes or the like) and makes decisions as to what voltages to apply to the various EAP structures of the suit.

[0064] Aspects of the invention provide methods for operating the garments and/or tubular EAP structures described herein. By way of non-limiting example, aspects of the invention provide methods for donning and/or doffing garments which involve expanding a volume of at least a portion of the garment prior to donning and/or doffing the garment. Expanding the volume of the garment may involve application of voltages to one or more generally tubular EAP structures. After donning the garment (or at least an expanded portion of the garment), the voltage may be removed from the EAP (or reduced) to allow the garment to shrink again. Another example method comprises adjusting the fit of a garment or one or more sections of a garment or one or more portions of sections of a garment by applying suitable voltage level(s) to one or more corresponding generally tubular EAPs incorporated into the garment. Another example method comprises influencing the flow of blood or other materials in the human body by expanding one or more sections (or portions of section) of the garment and/or contracting one or more other sections (or portions of sections) of the garment. [0065] In the embodiments described above, garments are provided with generally tubular EAP structures capable of expanding and/or contracting to effect particular objectives. In other embodiments, generally tubular sections (or portions of generally tubular sections) of garments may be provided with one or more EAP structures of other shapes which effect expansion and/or contraction of the circumference of the generally tubular garment section.

[0066] Figures 7, 8 A and 8B depict various views of an exemplary embodiment of a generally tubular section 280 of a garment 280A incorporating an EAP structure 281. Some detail is omitted from the schematic illustrations of Figures 7, 8 A and 8B for brevity and clarity. As shown in Figures 7, 8 A and 8B, EAP structure 281 occupies only a portion of the circumference of generally tubular section 280. hi the illustrated embodiment, EAP structure 281 has a curved shape which may conform to the body section (not shown) located within generally tubular section 280. EAP structure 281 may have a different shape that occupies only a portion of the circumference of section 280. For example, where section 280 is a torso section (see torso section 14 of Figure 1), EAP structure may be generally rectangular to conform with a portion of the wearer's chest or back.

[0067] EAP structure 281 comprises conductive electrodes 282A, 282B (together, conductors 282) which may be similar to any of the other conductors described herein and a dielectric material 284 which may be similar to any of the dielectric materials described herein. As shown in Figure 7, EAP structure 281 comprises axial constraints 288A, 288B (together, constraints 288) which constrain the expansion of EAP structure 281 in axial direction 90. hi the illustrated embodiment, axial constraints 288 are similar to the axial constraints of other embodiments described herein. However, this is not necessary, as it is generally unnecessary to constrain section 280 of garment 280A outside of the region of EAP structure 281.

[0068] While not explicitly shown in Figures 7, 8 A and 8B, EAP structure 281 may be connected at its edges to the non-EAP material 283 garment 280A. Such connection may be provided by stitching, by suitable mechanical fasteners, by bonding using silicone or other suitable adhesive or the like. EAP structure 281 may additionally or alternatively be connected or integrated onto or between layers of garment 280A using any of the techniques described herein. In some embodiments, EAP structure 281 may be fabricated from materials that have suitable characteristics such that EAP structure 281 itself can be the fabric of the garment or a portion of the garment. [0069] Figure 8A is a cross-sectional view of section 280 with EAP structure in a relatively relaxed state (i.e. with a relatively low applied voltage between conductors 282A, 282B). Figure 8B is a cross-sectional view of section 280 with EAP structure in a relatively compressed state (i.e. with a relatively high applied voltage between conductors 282A, 282B). It can be seen by comparing Figure 8A and 8B, that the increased Coulombic attraction between conductors 282A, 282B caused by the increased voltage in Figure 8B compresses dielectric material 284 as conductors 282A, 282B move toward one another. When coupled with the axial constraint provided by constraints 288, the compression of dielectric material 284 causes the dimension of dielectric material 284 to increase in the directions generally aligned with a circumference of section 200. As such, the overall circumference of section 200 increases with the application of greater voltage to conductors 282A, 282B. [0070] It will be appreciated that any of the garments and applications described above for generally tubular EAP structures may be accomplished in whole or in part by EAP structures similar to EAP structure 281 that have non-tubular shapes occupying less than the circumference of the corresponding garment section. Further, sections of garments may comprise a plurality of EAP structures similar to EAP structure 281 that have non-tubular shapes occupying less than the circumference of the corresponding garment section. Such pluralities of EAP structures may be arranged at spaced apart locations around the circumference of the generally tubular garment section or along the axial dimension of the generally tubular garment section. Such pluralities of EAP structures may be interleaved with one another.

[0071] Figure 9 depicts a garment 300 according to another particular embodiment. Garment 300 comprises a suit 301 covering the wearer's arms, legs, torso, neck and pelvis. In the illustrated embodiment, garment 300 comprises a pair of EAP structures 302A, 302B which have a non-tubular shape. EAP structures 302A, 302B may be similar to EAP structure 281. EAP structures 302 A, 302B are located in arm sections, leg section, torso section, neck section and pelvis section of suit 301. When EAP structures 302A, 302B expand (i.e. by application of a larger voltage), the arm sections, leg section, torso section, neck section and pelvis section of suit 301 expand and when EAP structures 302 A, 302B contract (i.e. by application of a smaller voltage), the arm sections, leg section, torso section, neck section and pelvis section of suit 301 also contract.

[0072] Figures 1 IA, 1 IB and 11C depict various views of an EAP structure 400 which may be incorporated into a garment according to another embodiment of the invention. Unlike some of the other EAP structures described above, EAP structure 400 does not include constraint structures. EAP structure 400 of the illustrated embodiment has a toroid or donut-like shape. The toroid shape of EAP structure 400 provides a central bore 410 aligned with central toroidal axis 402. In the illustrated embodiment, the toroid shape of EAP structure 400 may be envisioned as revolving an elliptical annulus about central axis 402. In other embodiments, toroidal shapes may be provided by revolving other plane annular shapes (e.g. circular annuli, or irregularly shaped annuli) about central axis 402.

[0073] EAP structure 400 comprises an external conductive layer 404A and an internal conductive layer 404B (collectively, conductive layers 404), which are respectively located on the external surface and the internal surface of dielectric material 406. hi the illustrated embodiment, conductive layers 404 and dielectric material 406 all have toroidal shapes similar to those of EAP structure 400 itself (i.e. formed by revolving elliptical annuli about central axis 402). hi other embodiments, conductive layers 404 and dielectric material 406 may have other toroidal shapes (i.e. formed by revolving other plane annular shapes about central axis 402). In other embodiments, conductive layers 404 and dielectric material 406 may have toroidal shapes that are different from one another. As shown best in Figure 1 IB, EAP structure 400 also comprises a bore 408 on an interior of internal conductive layer 404B.

[0074] Figures 12A and 12B show cross-sectional views of a garment section 420 incorporating EAP structure 400 of Figures l lA-HC in a normal configuration where garment section 420 is relatively tight fitting on body part 422 (Figure 12A) and an expanded configuration where garment section 420is relatively loose fitting on body part 422 and relatively easy to don and to doff (Figure 12B). For clarity, non-EAP garment layers of garment section 420 (to which EAP structure may be connected by any of the means described herein) are not shown in Figures 12A and 12B. While EAP structure 400 may be connected to garment layers, this is not necessary and EAP structure 400 alone may provide garment section 420.

[0075] As shown in Figures 12A and 12B, body part 422 extends through bore 410 of EAP structure 400 in general alignment with axis 402. Figure 12B shows the expanded configuration of garment section 420 - for example, in a configuration which may make it easier to don and doff the garment, hi the Figure 12B configuration, switch 106 is connected between nodes 108, 110 such that the voltage V is applied between conductive layers 404 A, 404B of EAP structure 400. The application of voltage V causes conductive layers 404A, 404B to be attracted to one another, compressing dielectric material 406. When dielectric material 406 of structure 400 is compressed in this manner, the conservation of its volume causes the circumference/perimeter of the toroid shape of EAP structure 400 to increase together with an increase in the size of bore 410, thereby loosening the fit of garment section 420 around body part 422. This increase in the size of bore 410 makes it relatively easy to don and doff the garment incorporating garment section 420. [0076] Figure 12B shows the contracted configuration of garment section 420 - for example, in a configuration which may be used after the garment is donned by the wearer or when the garment is being stored, hi the Figure 12A configuration, switch 106 is connected between nodes 108, 112 such that voltage V is removed from conductive layers 404A, 404B of EAP structure 400. When voltage V is removed, the attraction between conductive layers 404A, 404B decreases, resulting in an increase in the thickness of dielectric material 406 and corresponding decreases in the circumference/perimeter of EAP structure 400 and the size of bore 410. It can be seen that in the configuration of Figure 12 A, bore 410 of garment section 420 fits relatively tightly against body portion 422.

[0077] EAP structure 400 may be fabricated using techniques similar to those described above for EAP structure 80 (Figure 3) - e.g. by bending one or more generally planar pieces of elastomeric material and bonding suitable edges of the elastomeric piece(s) to one another. In one particular embodiment, a single flat piece of material can be shaped to form a toroidal cylinder (similar to that of EAP structure 80) using the techniques described above. Then the axial extremities of the toroidal cylinder may be cut at suitable angles and the cylinder may be bent into a circle until the extremities contact one another. When the extremities are in contact with one another, these edges may be bonded to one another in a manner similar to that described above. In other embodiments, EAP structure 400 may be fabricated using suitable injection molding or blow molding techniques or using prototyping technologies, such as stereolithography, three-dimensional printing, or the like. [0078] Electrical contact may be provided to external conductive surface 404A using techniques similar to those described above for EAP structure 80. To provide electrical contact to internal conductive surface 404B, a small hole/conduit may be provided through external conductive surface 404A and dielectric material 406 and wire may be extended through this hole. Such a hole/conduit may be substantially smaller than the size of structure 80, so as to minimize the impact on performance. [0079] Referring to garment 10 of Figure 1, EAP structure 400 is particularly well suited to be incorporated into arm cuffs 17, leg cuffs 21 and neck section 12 of garment 10. However, EAP structure 400 may generally be incorporated into other garment sections (e.g. arm sections 16, torso section 14, pelvic section 18, leg sections 20) or portions thereof. Like the other EAP structures described herein, it is not necessary that EAP structure 400 be used in on/off modes. More particularly, the voltage applied to EAP structure 400 may be varied (e.g. by a suitably configured controller and/or user interface) to provide bore 410 with various cross-sectional sizes. Such variable applied voltage may be used to provide adjustable-fit garment sections similar to those described in Figures 5C and 5D above.

[0080] Garments incorporating multiple EAP structures 400 may be controlled by controllers/user interfaces or the like which may control the individual EAP structures in a manner similar to the EAP structures described herein. Like the other EAP structures described herein, EAP structure 400 may be incorporated into garments and controlled to apply positive and negative pressures to various parts of the wearer's body to influence the flow of blood and/or other materials within the body of the wearer. [0081] As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example:

• This description makes use of words and phrases such as generally tubular, generally radial, circumference, circumferential and the like. Such words and phrases are used for convenience and brevity and are not meant to imply that

EAP structures and garments incorporating such EAP structures are limited to EAP structures having circular or annular cross-sections. Generally tubular EAP structures according to particular aspects of the invention may have any suitable constant or varying cross-sections for accommodating the body of a wearer.

• hi some embodiments, garments may comprise layered EAP structures. Figure 10 schematically illustrates an EAP structure 310 with such a layered formation. In the illustrated embodiment, EAP structure 310 comprises four layered individual EAP structures 314, 316, 318, 320, but may comprise a different number, hi the illustrated embodiment, adjacent individual EAP structures 314, 316, 318, 320 share electrodes, but that is not necessary. Individual EAP structure 314 comprises electrodes 326, 328 and dielectric 336, individual EAP structure 316 comprises electrodes 328, 330 and dielectric 338, individual EAP structure 318 comprises electrodes 330, 332 and dielectric 340 and individual EAP structure 320 comprises electrodes 332,

334 and dielectric 342. Alternating electrodes 326, 330, 334 are tied to ground and, in the illustrated embodiment, the other set of alternating electrodes 328, 332 are tied to a positive voltage source V. The voltage source V may be varied. In some embodiments, each of the second set of electrodes 328, 332 may have a different applied voltage. Because of the manner that they operate in parallel, layered EAP structures similar to layered EAP structure 310 may achieve similar pressures to individual EAP structures with lower applied voltages to each individual EAP structure. Layered EAP structures may be used in the place of any of the other EAP structures described herein.

• The sections of suit 10 shown in Figure 1 represent a non-limiting set of sections. Garments according to various embodiments of the invention could be provided with other sections, such as gloves, boots and/or hoods which are not shown in suit 10 of Figure 1. Garments according to other embodiments may subdivide any of the Figure 1 garment sections into subdivided garment portions.

• Garments are described herein for application to the human body, but such garments may be adjusted for application to some animals.

• The drawings accompanying this description show the application of discrete voltage levels which may be used to expand and/or contract one or more sections (or portions of sections) of a garment. The use of discrete voltage levels is not necessary. Voltages applied to EAP structures may be controlled by analog inputs or by digital inputs having imperceptibly small quantization intervals to provide a smoothly varying variety of levels to suit a given purpose.

• The description above sets out a number of non-limiting uses for variable volume garments according to particular aspects of the invention. There are a wide variety of other uses in addition to those described in detail above. Such other uses may include, without limitation: restricting blood flow to hemorrhages using contraction, assistance with breathing by rhythmic contraction and expansion and other blood volume regulation applications.

• Garments according to various aspects of the invention may comprise other smart materials capable of changing shape under the influence of an external stimulus. Such smart materials may be shaped into generally tubular structures similar to those described above for generally tubular dielectric EAP structures. By way of non-limiting example, such smart materials may comprise: piezoelectric materials and/or shape memory alloys similar to those disclosed in Donald J. Leo, Engineering Analysis of Smart Material Systems: Analysis, Design, and Control - Technology & Engineering - 2007, magnetorheological materials and/or electrically and/or magnetically activated fluid materials similar to those disclosed in James A. Jacobs, Thomas F. Kilduff, Engineering Materials Technology: Structures, Processing, Properties, and Selection, Prentice Hall, 2001, liquid metal materials similar to those disclosed in T. Iida et al., The Physical Properties of Liquid Metals (Oxford Univ. Press, Oxford, 1987), hybrid artificial muscles similar to those disclosed in Adam W. Feinberg, Alex Feigel, Sergey S. Shevkoplyas, Sean Sheehy, George M. Whitesides, and Kevin Kit Parker, Muscular Thin Films or Building Actuators and Powering Devices, Science, 7 September 2007, 317: 1366-1370 and other forms of electroactive polymers (EAPs), such as polyelectrolyte gels, ion polymer metal composites (IPMC), conducting polymers, carbon nanotubes, piezoelectric polymers, electrostrictive polymers and dielectric elastomers similar to those disclosed in Y. Bar-Cohen (Book Editor and author/co-author of 5 chapters), Electroactive Polymer (EAP) Actuators as Artificial Muscles - Reality, Potential and Challenges, ISBN 0-8194-4054-X, SPIE Press, Vol. PM98, (March 2001). All of these references are hereby incorporated herein by reference. Some embodiments described above provide garment sections incorporating features (e.g. circumferential bands or cuffs) to make them air-tight such that the application of negative pressure actually pulls the wearer's skin outwardly and maintains contact between the interior surface of the garment and the wearer's skin. In some embodiments, an entire suit (or several sections of a suit) may be made air-tight to achieve this effect over any sections of the suit which are actuated to provide negative pressure. For example, a garment comprising a pair of trousers may be made air-tight by having suitable ankle cuffs and an appropriate waist cuff, an upper body garment may be made airtight by having suitable wrist cuffs, neck cuff and waist cuff and a full body garment may be SUBSTITUTE_SHEET (RULE _^ 26) able ankle, wrist and neck cuffs. Such garments may also employ liquids, gels or adhesives which may improve the air-tight aspect of the suit and/or assist with maintaining contact between the skin and the inside surface of the garment to pull the wearer's skin outwardly during application of negative pressure. In some embodiments, circumferential bands or cuffs may be provided at or near the edges of particular sections to make such sections air-tight so that the application of negative pressure pulls the wearer's skin outwardly and maintains contact between the interior surface of the section and the wearer's skin. For example, where the section is arm section, circumferential bands or cuffs may be located at or near the wrist and at or near the armpit. In some embodiments, circumferential bands may be provided within particular sections to sub-divide the section into air-tight portions. For example, in the aforementioned arm section, one or more additional circumferential bands may be provide around the elbow to facilitate independent air-tight portions above and below the elbow.

• Garments according to the embodiments described herein may generally be fabricated to have any suitable thickness. Particular embodiments provide garments which have thicknesses in a range of 0.5mm- 15mm. Accordingly, the invention should be interpreted in accordance with the following claims.