IMPLANT WITH ELASTOMERIC MEMBRANE AND METHODS OF MANUFACTURING THE SAME.

Abstract

A method for forming an implant is described, which includes providing a preformed liner formed from at least one cured elastomeric layer. The liner includes an outer surface, an inner surface, and a hole for accessing the liner's interior volume. The method further includes expanding the liner to an expanded state, in which the interior volume is greater than the liner's interior volume at the time of liner formation, and forming an interior zone having at least one inner elastomeric layer over at least a portion of the liner's interior surface while the liner is in the expanded state, thereby forming a multi-zone liner.The method also includes reducing the interior volume of the multi-zone coating, thereby contracting at least one interior elastomeric layer of the interior zone and causing texturing of at least one interior elastomeric layer.

Description

IMPLANT WITH ELASTOMERIC MEMBRANE AND METHODS OF MANUFACTURING THE SAME BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates generally to prosthetic implants and methods of manufacturing them, in particular to implants having an elastomeric membrane or coating with textured inner and / or outer surfaces. DESCRIPTION OF THE RELATED TECHNIQUE Many breast implants are commercially available. A single-chamber design is the most common and is available in a variety of fixed volumes to produce a range of sizes and shapes from approximately 80 to 800 cubic centimeters. As used here, a “chamber” refers to the inner portion of a breast implant, which is enclosed by an outer lining or membrane. As those familiar with the terminology know, the inner portion of the implant may also be referred to as a lumen. Implants are typically filled with silicone gel or saline solution. Viscoelastic silicone implant linings may be of similar composition but vary in thickness, texture, and surface treatments. There are also significant differences with respect to the filling materials.Silicone gel implants generally have more natural-looking properties, with less noticeable edges and ripple effects. The viscosity of the silicone gel reduces fluid movement, resulting in these beneficial properties. The silicone gel filling the implant can change over time, becoming firmer, softer, and altering in elasticity, depending on its composition. Historically, a major complication has been gel leakage, leading to capsular contracture and tissue toxicity for the patient. Many gel-filled implants have additional coatings or barrier layers to decrease silicone diffusion into the surrounding tissues. Diffusion can be reduced, but not eliminated. Saline implants have been developed to eliminate - 2 complications related to fluid leakage. Saline solution is biocompatible and can be absorbed without tissue toxicity complications in the event of slow leakage or implant rupture. The low viscosity of saline solution allows for significant fluid movement, resulting in deformation of the fluid-filled liner. This rippling and undulating movement is often visible through the overlying tissue. This is a more significant complication in cases where there is little tissue surrounding the implant. Deformation of the viscoelastic membrane can cause the surrounding tissue to scar and contract, distorting and hardening the implant's sensation. Saline implants are frequently placed deep beneath the pectoral muscle tissue and slightly overfilled to avoid complications. The coatings and texturizing of the implant have been developed to reduce capsular contracture with reasonable success. For example, variable surface treatments can work by allowing tissues to adhere and distributing the forces responsible for contracture. The materials used to form, coat, and fill implants have resulted in a wide variety of available designs. Size and shape alone produce many options. Designs become increasingly complex when considering multiple chambers and variable volume designs. The variability in volume during surgery allows for adjustments to be made for overall size and symmetry. Access ports and valves are used to inflate or deflate the implant. In some cases, the filling tube is left in place for a short period to allow for further adjustment after surgery.This adjustability is a desirable and often necessary feature in the case of tissue expanders. Multi-chamber implants predominantly consist of an inner and an outer chamber filled with silicone, saline, or a combination of both. The combination of chambers allows for greater variability in size and shape characteristics. Currently available models feature a double-membrane, dual-chamber design in which an outer chamber has a fixed volume of gel and an adjustable inner chamber is filled with saline. These implants provide a natural appearance and feel with the added advantage of - 3 temporary adjustability. However, these more complex designs have been found to be less resistant to shear forces in areas where there are junctions between membranes and the valve port. An exemplary implant formed from an elastomeric coating with a textured outer surface is described in U.S. Patent No. 8,506,627 to Van Epps et al. The implant described in patent '627 includes a textured attachment region on an inner face of the coating. The attachment region may have a different texture from other portions of the outer surface of the coating. In some examples, the implant coating is formed on a mandrel. For example, the mandrel may be repeatedly dripped into a flowable silicon elastomer until a membrane of the desired thickness is formed. Portions of the outer surface of the membrane may be subjected to a texturizing process, in which granular solid particles (e.g., salt crystals) are applied to portions of the outer surface of the membrane to form the attachment surface.After the textured surface stabilizes, the granular solid particles can be removed, for example, by immersing the membrane in a fluidized bath (e.g., an aqueous saline bath) to dissolve the particles, resulting in a membrane with a textured surface reminiscent of a plurality of crystalline particles. However, there is a continuing need to develop implants that safely provide a natural feel and appearance when surgically implanted. For example, implants must adhere to and / or interact with the breast or other body tissues in a biocompatible and effective manner. Furthermore, implant designs with improved biocompatibility and / or those that can be manufactured more easily and efficiently are needed. The implants and methods for forming them provided herein are intended to address some or all of these needs. BRIEF DESCRIPTION OF THE INVENTION According to a preferred, non-limiting modality or aspect, an adjustable implant is provided. The adjustable implant comprises an elastomeric membrane enclosed or partially enclosed around a chamber, which is hQfrRrn / Lznz / q / YILI - 4 adapted to expand when filled with a fluid. The membrane comprises: an outer zone formed of at least one outer elastomeric layer, the outer zone comprising an outer surface having at least one textured portion molded thereon; and an inner zone formed of at least one middle elastomeric layer positioned on an inner surface of the outer zone. The implant is configured such that the inner zone is under contraction from a contraction force provided by the outer zone. According to another preferred, non-limiting embodiment or aspect, a method for forming an implant is provided. The method comprises: forming an outer zone of an elastomeric membrane comprising at least one elastomeric layer by casting it in a mold, wherein an inner surface of the mold comprises one or more textured portions, which are molded onto an outer surface of at least one elastomeric layer to form one or more molded textured portions. The method further comprises: expanding the outer zone so as to expand a volume enclosed by the outer zone; forming an inner zone comprising one or more elastomeric layers within the expanded outer zone; retracting the outer and inner zones to a retracted state; and forming a fitable implant from the membrane by enclosing the membrane to form at least one chamber. According to another preferred and non-limiting embodiment or aspect, an implant is provided for volumetrically altering, replacing, expanding, or augmenting tissues. The implant includes an enclosed or partially enclosed elastomeric membrane formed of one or more laminated elastomeric layers. The membrane defines an interior volume. The implant also includes a cohesive gel placed within the interior volume of the elastomeric membrane. The volume of the cohesive gel is greater than the volume enclosed by the elastomeric membrane at the time of curing, thereby causing the elastomeric membrane to exert a contraction force on the cohesive gel. According to another preferred and non-limiting modality or aspect, a method is provided for forming an implant to volumetrically alter, replace, expand, or augment tissues. The method includes: forming an elastomeric membrane that - 5 has one or more laminated elastomeric layers, the membrane encloses or partially encloses an interior volume; expand the elastomeric membrane so that the interior volume enclosed or partially enclosed by the elastomeric membrane expands; fill the elastomeric membrane with a flowable elastomeric material; and cure the elastomeric material to form a cohesive gel. According to another preferred, non-limiting aspect or embodiment, a method is provided for forming an implant for volumetrically altering, replacing, expanding, or augmenting body tissues, comprising an elastomeric membrane that at least partially encloses an inner volume. The method includes forming an outer zone of the elastomeric membrane by casting it in a mold, the outer zone comprising at least one elastomeric layer, wherein the inner surface of the mold comprises one or more textured portions, which are molded onto an outer surface of the outer zone to thereby form one or more textured portions molded onto the outer surface of the outer zone.The method further includes expanding the outer zone to increase the volume enclosed by the outer zone and form an expanded zone of the elastomeric membrane comprising at least one elastomeric layer on an inner surface of the outer zone. The expanded zone at least partially encloses a volume at the time of formation, which is larger than the volume enclosed by the outer zone at the time of its formation. The method further includes forming an adjustable implant from the elastomeric membrane by enclosing the inner volume, wherein the outer surface of the implant comprises one or more molded textured portions. According to another preferred and non-limiting embodiment or aspect, an implant is provided for volumetrically altering, replacing, expanding, or augmenting tissues. The implant includes: a partially enclosed elastomeric membrane formed from a plurality of laminated elastomeric layers. The membrane defines an interior volume. The implant further includes a cohesive gel placed within the interior volume of the elastomeric membrane. The volume of the cohesive gel is greater than the volume enclosed by the elastomeric membrane at the time of curing of the elastomeric membrane, thereby causing the elastomeric membrane to exert a contraction force. - 6 on the cohesive gel. An outer surface of the elastomeric membrane comprises at least one textured portion having a texture pattern different from the other portions of the outer surface of the elastomeric membrane. According to another preferred, non-limiting aspect or embodiment, a method of forming an implant for volumetrically altering, replacing, expanding, or augmenting body tissues includes providing a preformed liner from at least one cured elastomeric layer. The preformed liner includes an outer surface, an inner surface, and an opening for accessing the interior volume of the preformed liner. The method also includes expanding the preformed liner to an expanded state, in which the interior volume is greater than the interior volume of the preformed liner at the time of its formation, and forming an interior zone having at least one inner elastomeric layer over at least a portion of the interior surface of the preformed liner while the liner is in the expanded state, thereby forming a multi-zone liner.The method also includes reducing the internal volume of the multi-zone lining, thereby contracting at least one inner elastomeric layer of the inner zone and causing texturing of at least one inner elastomeric layer, followed by implant formation by enclosing the multi-zone lining to form at least one chamber. According to another preferred, non-limiting aspect or embodiment, a method of forming an implant for volumetrically altering, replacing, expanding, or augmenting body tissues includes providing a preformed liner formed from at least one cured elastomeric layer. The preformed liner includes an outer surface, an inner surface, and an opening for accessing an interior volume of the preformed liner. The method further includes placing the preformed liner on a mandrel to expand the preformed liner to an expanded state in which the interior volume of the preformed liner is greater than the volume of the preformed liner at a time of formation. Although the preformed liner is on the mandrel, an outer zone having at least one outer elastomeric layer is formed over at least one - 7. The method involves placing the multi-zone lining onto a mandrel in an inverted orientation, wherein the outer zone of the multi-zone lining contacts the mandrel and forms an inner zone having at least one inner elastomeric layer over at least a portion of the inner surface of the multi-zone lining, while the multi-zone lining is on the mandrel and in the expanded state. The method further includes reducing the inner volume of the multi-zone lining by removing the multi-zone lining from the mandrel, thereby contracting at least one outer elastomeric layer and at least one inner elastomeric layer.The method further includes causing texturing of at least one outer elastomeric layer and at least one inner elastomeric layer; and forming the implant by enclosing the coating to form at least one chamber. According to another preferred, non-limiting aspect or embodiment, an implant for volumetrically altering, replacing, expanding, or augmenting tissues includes an enclosed or partially enclosed elastomeric coating formed from a plurality of laminated elastomeric layers defining an interior volume; and a cohesive gel placed within the interior volume of the elastomeric coating. The elastomeric coating includes: a preformed coating comprising at least one elastomeric layer having an inner surface and an outer surface; an outer zone having at least one outer elastomeric layer covering at least a portion of the outer surface of the preformed coating; and an inner zone having at least one inner elastomeric layer covering at least a portion of the inner surface of the preformed coating.A volume enclosed by the outer zone and the inner zone at the time of forming the outer zone and the inner zone is greater than a volume of the preformed lining at the time of forming the preformed lining. Additional preferred and non-limiting embodiments or aspects of the present invention will be described below in the following numbered clauses. - 8 Clause 1: A method of forming an implant for volumetrically altering, replacing, expanding or augmenting body tissues comprising an elastomeric membrane that at least partially encloses an inner volume, the method comprising: forming an outer zone of the elastomeric membrane by casting in a mold, the outer zone comprising at least one elastomeric layer, wherein the inner surface of the mold comprises one or more textured portions which are molded onto an outer surface of the outer zone to thereby form one or more textured portions molded onto the outer surface of the outer zone; expanding the outer zone, thereby increasing a volume enclosed by the outer zone;forming an expanded zone of the elastomeric membrane comprising at least one elastomeric layer on an inner surface of the outer zone, the expanded zone at least partially enclosing a volume at the time of formation which is greater than a volume enclosed by the outer zone at the time of formation of the outer zone; and forming an adjustable implant from the elastomeric membrane by enclosing the inner volume, wherein the outer surface of the implant comprises one or more molded textured portions. Clause 2: The method of clause 1, further comprising retracting the elastomeric membrane to a retracted state before forming the implant from the elastomeric membrane, wherein the volume enclosed by the outer zone in the retracted state is greater than the volume enclosed by the outer zone at the time of forming the outer zone, such that the molded textured portions of the implant are expanded compared to one or more textured portions of the inner surface of the mold. Clause 3: The method of clause 1 or clause 2, wherein the expansion of the outer zone comprises expanding a volume enclosed by an outer zone by between 10% and 500% compared to the volume enclosed by the outer zone when it is formed. Clause 4: The method of any of clauses 1 to 3, wherein the inner surface of the mold comprises at least a first molded textured portion having a first texture pattern and at least a second portion - 9 textured molded having a second texture pattern, and wherein the outer surface of the implant comprises a portion having the first texture pattern and a portion having the second texture pattern. Clause 5: The method of clause 4, wherein at least one of the textured portions on the inner surface of the mold is configured to provide an adhesion region to enhance adhesion with surrounding body tissues. Clause 6: The method of clause 4 or clause 5, wherein the inner surface of the mold further comprises one or more substantially flat portions separating the textured portions. Clause 7: The method of any of clauses 1 to 6, wherein the formation of the expanded zone comprises forming a plurality of laminated elastomeric layers of varying hardness. Clause 8: The method of clause 7, wherein an inner layer of the plurality of layers is softer than an outer layer of the plurality of layers. Clause 9: The method of clause 8, wherein the innermost layer of the plurality of layers has a thickness of between approximately Shore 00-10 and approximately Shore A-20, and wherein the outermost layer of the plurality of layers has a hardness of between approximately Shore A-20 and Shore A-40. Clause 10: The method of any of clauses 1 to 9, further comprising pre-stretching at least one elastomeric layer to the outer zone before expansion of the outer zone. Clause 11: The method of any of clauses 1 to 10, wherein the formation of the outer zone comprises introducing a flowable elastomeric material to the inner surface of the mold and curing the material to form at least one elastomeric layer. Clause 12: The method of any of clauses 1 to 11, further comprising filling the interior volume defined by the elastomeric membrane with a flowable elastomeric material and curing the flowable elastomeric material to form a cohesive gel. Clause 13: The method of clause 12, wherein the cohesive gel is - 10 attached to an inner surface of the elastomeric membrane. Clause 14: The method of clause 12, wherein the volume of the cohesive gel when cured is between approximately 5% and 50% larger than a volume enclosed by the outer zone at the time of formation. Clause 15: The method of any of clauses 1 to 14, wherein the mold comprises a volumetrically expandable mold, and wherein an interior volume of the mold is increased to cause the expansion of at least one elastomeric layer of the outer zone. Clause 16: The method of any of clauses 1 to 15, wherein the mold comprises a single-use disposable plastic mold. Clause 17: The method of any of clauses 1 to 16, wherein at least one elastomeric layer of the outer zone has a Shore hardness of approximately Shore A-10 to A-40, and preferably approximately Shore A20 to Shore A-30. Clause 18: The method of any of clauses 1 to 17, wherein the molded textured portion comprises at least one of the following: channels, protrusions, projections, granular or crystalline structures, cross diagonals, waves, or any combination thereof. Clause 19: The method of any of clauses 1 to 18, wherein the molded textured portion comprises molded guide lines to assist in the surgical placement of the implant in relation to the body tissue to be altered, expanded, or augmented. Clause 20: An implant for volumetrically altering, replacing, expanding, or augmenting tissues, comprising: an enclosed or partially enclosed elastomeric membrane formed of a plurality of laminated elastomeric layers, the membrane defining an interior volume; and a cohesive gel placed within the interior volume of the elastomeric membrane, wherein the volume of the cohesive gel is greater than the volume enclosed by the elastomeric membrane at the time of curing of the elastomeric membrane, whereby the elastomeric membrane exerts a contraction force on the cohesive gel, and wherein an outer surface of the membrane - 11 elastomeric comprises at least one textured portion that has a texture pattern different from other portions of the outer surface of the elastomeric membrane. Clause 21: The implant of clause 20, wherein the plurality of laminated elastomeric layers comprises elastomeric layers of variable hardness. Clause 22: The implant of clause 20 or clause 21, wherein an inner layer of the plurality of layers is softer than an outer layer of the plurality of layers. Clause 23: The implant of any of clauses 20 to 22, wherein the innermost layer of the plurality of layers has a hardness of between approximately Shore 00-10 and approximately Shore A-20, and wherein the outermost layer of the plurality of layers has a hardness of between approximately Shore A-20 and Shore A-40. Clause 24: The implant of any of clauses 20 to 23, wherein the volume of the cohesive gel when cured is between approximately 5% and approximately 50% greater than a volume enclosed or partially enclosed by the elastomeric membrane at the time of curing. Clause 25: A method of forming an implant for volumetrically altering, replacing, expanding, or augmenting body tissues, the method comprising: providing a preformed lining, formed from at least one cured elastomeric layer, the preformed lining comprising an outer surface, an inner surface, and an opening for access to an inner volume of the preformed lining; expanding the preformed lining to an expanded state, in which the inner volume is greater than the inner volume of the preformed lining at a time of formation of the preformed lining; forming an inner zone comprising at least one inner elastomeric layer over at least a portion of the inner surface of the preformed lining while the lining is in the expanded state, thereby forming a multi-zone lining;reducing the internal volume of the multi-zone lining, thereby contracting at least one inner elastomeric layer of the inner zone and causing texturing of at least one inner elastomeric layer; and forming the implant by enclosing the multi-zone lining to form at least one chamber. - 12 Clause 26: The method of clause 25, wherein the expansion of the preformed lining to an expanded state comprises inverting the preformed lining and placing the inverted preformed lining on a mandrel, so that the outer surface of the lining is in contact with a surface of the mandrel. Clause 27: The method of clause 26, wherein the volume enclosed by the mandrel surface is greater than the internal volume of the preformed lining at the time of forming the preformed lining. Clause 28: The method of clause 25 or clause 26, wherein reducing the internal volume of the multi-zone lining comprises removing the multi-zone lining from the mandrel and returning the multi-zone lining to a non-inverted orientation. Clause 29: The method of any of clauses 25 to 27, wherein expanding the preformed lining comprises expanding the inside volume of the preformed lining by between 50% and 800% compared to the volume of the preformed lining at the time of forming the preformed lining. Clause 30: The method of any of clauses 25 to 29, wherein the formation of the inner zone comprises, while the preformed lining is in the expanded state, forming a plurality of laminated inner elastomeric layers of varying hardness on the inner surface of the preformed lining. Clause 31: The method of clause 30, wherein the most proximal layer of the plurality of inner elastomeric layers and the most distal layer of the plurality of inner elastomeric layers are firmer than the middle layers of the plurality of inner elastomeric layers. Clause 32: The method of any of clauses 25 to 31, wherein the most proximal layer and the most distal layer of the plurality of inner elastomeric layers are formed by mixing elastomeric materials having a hardness of up to Shore A-20 and wherein the middle layers of the plurality of inner elastomeric layers have a hardness of between approximately Shore 00-10 and Shore A-10. Clause 33: The method of any of clauses 25 to 32, wherein the formation of the implant comprising filling the internal volume of the lining of - 13 multiple zones with a flowable elastomeric material and curing of the flowable elastomeric material to form a cohesive gel. Clause 34: The method of clause 33, wherein the cohesive gel is bonded to the texturizing of at least one inner elastomeric layer. Clause 35: The method of clause 34, wherein a volume of the cohesive gel when cured is between approximately 5% and 50% larger than a volume enclosed by the preformed lining at the time of forming the preformed lining. Clause 36: The method of any of clauses 25 to 35, further comprising forming an outer zone comprising at least one outer elastomeric layer covering at least a portion of the outer surface of the preformed coating, while the preformed coating is in the expanded state and before forming the inner zone. Clause 37: The method of clause 36, further comprising reducing the internal volume of the preformed lining after forming the outer zone, which causes texturing of at least one outer elastomeric layer of the outer zone. Clause 38: The method of clause 37, wherein the texturing of the outer zone is configured to provide an adhesion region to enhance adhesion with surrounding body tissues. Clause 39: The method of any of clauses 36 to 38, wherein the outer zone comprises a plurality of outer elastomeric layers of varying hardness ranging from approximately Shore 00-30 to Shore A-20. Clause 40: The method of any of clauses 36 to 39, wherein forming the outer zone comprises placing the preformed lining on a mandrel, so that the inner surface of the preformed lining is in contact with the surface of the mandrel, and applying at least one outer elastomeric layer to the outer surface of the preformed lining. Clause 41: The method of clause 40, wherein a volume enclosed by the mandrel is greater than the volume of preformed lining, at the time of forming the preformed lining. - 14 Clause 42: A method of forming an implant to volumetrically alter, replace, expand or augment body tissues, the method comprising: providing a preformed lining formed from at least one cured elastomeric layer, the preformed lining comprising an outer surface, an inner surface and an opening for access to an inner volume of the preformed lining; placing the preformed lining on a mandrel to expand the preformed lining to an expanded state in which the inner volume of the preformed lining is greater than a volume of the preformed lining at the time of forming the preformed lining;while the preformed lining is on the mandrel, forming an outer zone comprising at least one outer elastomeric layer on at least a portion of the outer surface of the preformed lining, while the preformed lining is in the expanded state, to form a multi-zone lining; placing the multi-zone lining on a mandrel in an inverted orientation, in which the outer zone of the multi-zone lining makes contact with the mandrel; forming an inner zone comprising at least one inner elastomeric layer on at least a portion of an inner surface of the multi-zone lining, while the multi-zone lining is on the mandrel and in the expanded state;reducing the internal volume of the multi-zone liner by removing the multi-zone liner from the mandrel to bring into contact at least one outer elastomeric layer and at least one inner elastomeric layer, and causing texturing of at least one outer elastomeric layer and at least one inner elastomeric layer; and forming the implant by enclosing the liner to form at least one chamber. Clause 43: An implant for volumetrically altering, replacing, expanding, or augmenting tissues, comprising: an enclosed or partially enclosed elastomeric coating formed from a plurality of laminated elastomeric layers, the elastomeric coating defining an interior volume; and a cohesive gel placed in the interior volume of the elastomeric coating, wherein the elastomeric coating comprises: a preformed coating comprising at least one elastomeric layer, the preformed portion having an inner surface and an outer surface; - 15 an outer zone comprising at least one outer elastomeric layer covering at least a portion of the outer surface of the preformed coating; and an inner zone comprising at least one inner elastomeric layer covering at least a portion of the inner surface of the preformed coating, wherein a volume enclosed by the outer zone and the inner zone at the time of forming the outer zone and the inner zone is greater than a volume of the preformed coating at a time of forming the preformed coating. Clause 44: The implant of clause 43, wherein a volume enclosed by the outer zone and the inner zone of the implant is less than the volume enclosed by the outer zone and the inner zone at the time of formation of the outer zone and the inner zone, so that the preformed coating exerts a contraction force on the inner zone and the outer zone, which causes texturing of the inner zone and the outer zone. These and other features and characteristics of the present invention, as well as the methods of operation and functions of the elements of related structures, the combination of parts, and the economy of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying figures, all of which form a part of this specification, where similar reference numbers designate corresponding parts in the various figures. It should be expressly understood, however, that the figures are for the purpose of illustration and description only and are not intended as defining the limits of the invention. As used in the specification and the claims, the singular forms of “a,” “one,” and “the” include references to the plural forms, unless the context clearly determines otherwise. BRIEF DESCRIPTION OF THE FIGURES Some of the advantages and features of the preferred embodiments of the invention have been summarized above. These embodiments, along with other potential embodiments of the device, will become apparent to those skilled in the art when reference is made to the following figures and the detailed descriptions as they relate to the figures. - 16 Figure 1 is a sagittal view of a female human body through the left breast showing anatomical detail along with the in situ placement of an adjustable implant according to one aspect of the description; Figure 2 is a cross-sectional view of the adjustable implant of Figure 1 inserted into a patient's chest in a reverse orientation; Figure 3 is a cross-sectional view of another modality of an adjustable implant according to one aspect of the description; Figure 4 is a cross-sectional view of another modality of an adjustable implant according to one aspect of the description; Figures 5A to 5C are photographs of textured portions of an outer surface of an implant according to aspects of the description; Figure 6 is a cross-sectional view of a casting mold for forming an elastomeric membrane according to one aspect of the description; Figure 7 is a cross-sectional view of a portion of an elastomeric membrane formed from the mold of Figure 6; Figure 8 is a cross-sectional view of an apparatus for secondary casting to form additional elastomeric layers over the elastomeric membrane portion of Figure 7; Figure 9 is a cross-sectional view of the apparatus in Figure 8 illustrating a processing step for forming an elastomeric membrane from the membrane portion in Figure 7; Figure 10 is another cross-sectional view of the apparatus in Figure 8 illustrating a processing step to form an elastomeric membrane from the membrane portion of Figure 7; Figure 11 is a cross-sectional view of an adjustable implant formed from the elastomeric membrane of Figure 10; Figure 12 is a cross-sectional view of another casting mold for forming an elastomeric membrane according to aspects of the description; Figure 13 is a cross-sectional view of a secondary pouring apparatus for forming additional elastomeric layers on the hQhRQRI Lznz / q / YILI membrane portion - 17 elastomeric of figure 12; Figure 14 is a cross-sectional view of the apparatus in Figure 13 illustrating a processing step for forming an elastomeric membrane from the membrane portion in Figure 12; Figure 15 is a cross-sectional view of another modality of an implant formed from the elastomeric membrane of Figure 14; Figure 16 is a cross-sectional view of a casting mandrel for forming an elastomeric membrane of an adjustable implant according to one aspect of the description; Figure 17 is a cross-sectional view of a portion of an elastomeric membrane formed from the mandrel of Figure 16, during a subsequent processing stage, according to one aspect of the description; Figure 18 is a cross-sectional view of a portion of the elastomeric membrane of Figure 17, during a subsequent processing stage according to one aspect of the description; Figure 19 is an adjustable implant formed from the elastomeric membrane of Figure 18 according to one aspect of the description; Figure 20 is a cross-sectional view of a casting mandrel for forming an elastomeric membrane of an adjustable implant according to one aspect of the description; Figure 21 is a cross-sectional view of a portion of an elastomeric membrane formed from the mandrel of Figure 20, during a subsequent processing stage, according to one aspect of the description; Figure 22 is a cross-sectional view of a portion of the elastomeric membrane of Figure 21 during a subsequent processing stage according to one aspect of the description; Figure 23 is an adjustable implant formed from the elastomeric membrane of Figure 22 according to one aspect of the description; Figure 24 is a cross-sectional view of a casting mandrel for forming an elastomeric membrane of an adjustable implant according to a hQhRQRI Lznz / q / YILI - 18 aspect of the invention; Figure 25 is a cross-sectional view of a portion of an elastomeric membrane formed from the mandrel of Figure 24, during a subsequent processing stage, according to one aspect of the description; Figure 26 is a cross-sectional view of a portion of the elastomeric membrane of Figure 25 during a subsequent processing stage according to one aspect of the description; Figure 27 is an adjustable implant formed from the elastomeric membrane of Figure 26 according to one aspect of the description; Figure 28 is a cross-sectional view of an elastomeric membrane of an adjustable implant according to one aspect of the description; Figure 29 is a cross-sectional view of the elastomeric membrane of Figure 28 in an inverted position according to one aspect of the description; Figure 30 is a cross-sectional view of an adjustable implant formed from the elastomeric membrane of Figure 28 according to one aspect of the description; Figure 31 is a schematic cross-sectional view of another exemplary elastomeric implant according to one aspect of the invention; Figures 32A to 32C are schematic figures illustrating an exemplary process for forming the implant of Figure 31 according to one aspect of the present description; Figures 33A to 33E are schematic drawings illustrating an exemplary process for forming a two-zone implant from a preformed coating, according to one aspect of the present description; Figures 34A to 34D are schematic figures illustrating an exemplary process for forming a three-zone implant from a preformed coating, according to one aspect of the present description; Figures 35A and 35B are schematic figures of the three-zone implant formed by the exemplary process illustrated in Figures 34A to 34D, according to one aspect of the present invention; hQhRQRI Lznz / q / YILI - 19 Figure 36A is a photograph of an inner surface of an implant liner formed according to the process of Figures 33A to 33E or Figures 34A to 34D; and Figure 36B is a photograph of an outer surface of an implant liner formed according to the process of Figures 34A to 34D. DESCRIPTION OF THE INVENTION For the purposes of the description below, the terms “top,” “bottom,” “right,” “left,” “vertical,” “horizontal,” “above,” “below,” “side,” “longitudinal,” and derivatives thereof shall relate to the invention as oriented in the figures. However, it shall be understood that the invention may have variations and alternative step sequences, except where expressly specified otherwise. It shall also be understood that the specific devices and processes illustrated in the accompanying figures and described in the following specification are merely exemplary embodiments of the invention. Therefore, the specific dimensions and other physical characteristics relating to the embodiments described herein shall not be considered limiting. For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, dimensions, physical characteristics, etc., used in the specification and claims shall be understood to be modified, in every instance, by the term "approximately". Unless otherwise indicated, the numerical parameters stated in the following specification and appended claims are approximations that may vary based on the desired properties sought to be obtained by the present invention. Although the numerical ranges and parameters that define the broad scope of the invention are approximations, the numerical values ​​stated in the specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors that necessarily result from the standard deviation found in its measurements of hQhRQRI Lznz / q / YILI - 20 respective tests. Furthermore, any numerical interval mentioned in this document is intended to include all sub-intervals within it. For example, an interval from “1 to 10” is understood to include any and all sub-intervals between it that include the minimum value mentioned of 1 and the maximum value mentioned of 10; that is, all sub-intervals that begin with a minimum value equal to or greater than 1 and end with a maximum value equal to or less than 10, and all sub-intervals between them, for example, 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1. With reference to the figures, in general, the present description relates to an implant 12, 112, 210 that includes an elastomeric membrane enclosed or partially enclosed within a cavity or internal volume. The membrane may be prestretched before filling. For example, prestretching may involve expanding the cavity volume substantially beyond both the membrane volume when cured and the volume of the finished implant. In some examples, a 500 cc membrane may be expanded to 15 liters (e.g., a 3000% expansion). Prestretching modifies the membrane's stretch and resilience, which may be desirable in some applications. Following prestretching, the cavity may be filled with a fluid, such as a biocompatible water-soluble gel, silicone gel, or saline solution. Ideally, the membrane is under significant contraction or compression.However, the forces that contract the membrane must be balanced by other forces acting on the membrane to produce a stable implant.12,112,210 Due to the nature of its design, the elastomeric membrane produces a different sensation than other exemplary implant membranes. In some examples, at least a portion of the membrane may completely close the cavity. In other examples, the membrane may define an opening or orifice filled by a plug (e.g., a cured elastomeric material) to enclose the cavity. The implant 12, 112, 210 described herein can be used for various breast reconstruction and augmentation procedures, but is not limited to these procedures. For illustrative and descriptive purposes, the breast implants are - 21 can be used as examples of procedures in which a described implant will be used. Variations of the invention can be used for tissue volume replacement and as a tissue expansion device, to form tissues in post-traumatic surgery or in pre-planned or pre-annual surgery to prepare tissue wings. In this way, these implants 12, 112, 210 can be used as a permanent prosthesis or a temporary device, as indicated. The manufacturing methods described herein can be used to produce implants with suitable shapes and / or material properties for specific patient shapes or procedures at an affordable cost. In this way, the implants 12, 112, 210 described herein can be used in planned, highly invasive surgeries, such as the removal of a large tumor. For example, an implant can be pre-fabricated to replace the desired volume and shape of the removed tissues.In this way, the implant can be used to be slowly expanded or contracted over time to achieve the desired shape and allow the tissues to conform slowly, safely, and predictably. In some preferred, non-limiting embodiments or aspects, one or more layers or zones 18, 20, 118, 120 of the elastomeric membrane are continuous or substantially continuous and, preferably, self-sealing. Continuous elastomeric layers or zones are included that increase the structural integrity of the implant liner, so that the implant can be filled at higher pressures and / or substantially expanded beyond its natural volume without risk of rupture. Thus, in one preferred, non-limiting embodiment or aspect, the continuous, self-sealing nature of the membrane allows for adjustability (e.g., adjustment of implant volume by filling or removing fluid) without the need for special ports and filling valves. In preferred and non-limiting additional modalities or aspects, an outer surface of the elastomeric membrane is textured, for example, to enhance adhesion to and / or interaction with breast tissue. For example, channels, ridges, or other features of a textured surface may be selected or provided to permit or enhance ingrowth or adhesion of breast tissue to the outer surface of the hQhRQRI Lznz / q / YILI - 22 Implant. In some examples, the textured or rough regions of an implant 12, 112, 210 can create an attachment surface to adhere surface areas of the implant to breast tissue. In some examples, the texturing features are imparted to the outer surface of the implant during the formation of the outer layers of the implant, for example, by casting in a mold. In particular, texture features etched or otherwise produced on an inner surface of the mold are imparted to the outer surface of the implant. The texture may be a repeating pattern across the entire outer surface of the implant. In other examples, different portions of the implant surface have different texture patterns to impart different interactions with body tissue to different areas of the membrane.For example, posterior portions of implants 12, 112, and 210 may include corrugated attachment surfaces for enhanced adhesion to the chest wall. In other examples, anterior portions of the membrane may include a more substantial degree of texture (e.g., higher ridges and deeper grooves) to allow muscle tissue to grow to the implant surface. In other examples, designs may be provided on the outer surface of the implant to aid in implant placement. For example, guide lines for implant orientation may be molded onto the implant surface. In other preferred and non-limiting embodiments, an implant 12, 112, 210 formed from an elastomeric membrane or lining is filled with a cohesive gel 212. A cohesive gel material 212 refers to a substantially shape-stable material, which retains its shape when cured. In contrast, flowable materials such as saline solution are not shape-stable. The cohesive gel 212 is generally a biocompatible material, such as silicone, which can be injected or poured into an implant lining or mold in a flowable state and can be cured to produce a shape-stable structure. In some preferred and non-limiting embodiments or aspects, the cohesive gel 212 is enclosed within an elastomeric lining formed from a plurality of silicone layers. The elastomeric membrane or lining may be under contraction such that the elastomeric lining exerts a contraction force. - 23 on interior portions of the implant, including the cohesive gel. For example, the outer lining layers may cure to enclose a smaller volume than the volume enclosed by the finished implant. In that case, the outer lining layers exert a contraction force on the inner lining layers and on the cured cohesive gel material. The contraction force of the outer layers is balanced against outward-directed forces from the inner layers and / or the cohesive gel. The balance of contraction and outward-extending forces contributes to the mechanical properties and feel of the implant. For example, the inner membrane layers and / or the cohesive gel material may press against the outer layers, thereby providing a level of resilience and softness that gives the implant a more natural feel.Previously, manufacturers have attempted to improve the softness and feel of implants by making the lining as thin as possible, so that the feel of the cohesive gel portion of the implant is more noticeable than the feel of the lining. To achieve such a thin lining, stronger silicone materials are used for each layer. However, conventional implants made from thin but strong silicone linings are susceptible to rippling. In the implant described herein, the membrane contracts against the cohesive gel, which reduces rippling. Furthermore, the balance of forces produced between the cohesive gel and the contracting lining means that a thicker lining can be used while still achieving the desired softness and natural feel.Using a thicker membrane or lining further reduces ripple effects. Exemplary implant With reference to Figure 1, a cross-sectional view of a 12 implant placed within the left female human breast is illustrated. The 12 implant, according to a preferred, non-limiting modality, is in a submuscular anatomical position, under the pectoralis major muscle. Alternatively, the 12 implant may be placed submuscularly or in a subglandular position. Variations on these placements exist, but these two placement categories are the most common. - 24 common in practice. The cross-sectional view in Figure 1 provides basic anatomical landmarks for clarity. The implant 12 is positioned posteriorly against the chest wall tissues and underlying ribs 6. Anteriorly, the implant 12 can be positioned under the pectoral muscle tissue 5 with the larger muscle cover enveloping the superior anterior aspects of the implant 12. Anterior to the muscle tissue 5 are intact subcutaneous fat 4 and mammary glands 2. The nipple 3 is the structure most anterior to the implant 12. As shown in Figure 1, the implant 12 can be oriented so that a plug 23 sealing the implant cavity is positioned adjacent to the nipple 3. In other examples, as shown in Figure 2, the implant can be positioned with the plug adjacent to the chest wall and underlying ribs 6. Elastomeric membrane With reference to Figures 1 to 4, according to non-limiting aspects or modalities, the implant 12 generally includes an elastomeric membrane, also referred to as a lining, formed from multiple laminated elastomeric layers. In some preferred, non-limiting aspects and examples, the membrane or lining has a thickness of approximately 0.75 mm to 5.0 mm, preferably approximately 1.0 mm to 3.0 mm, and most preferably 1.8 mm to 2.5 mm. However, linings with a thickness greater than 5.0 mm may be used for particular applications. In some examples, the thickness of the membrane may vary around the circumference of the implant 12. For example, portions of the membrane intended to be placed near an opening 24 and / or plug 23 may be made thicker than other portions of the membrane.In other examples, portions of the membrane intended to be placed close to harder anatomical structures can be made thicker to reduce the possibility of leakage and / or improve implant safety. In general, the membrane includes at least several high-performance silicone elastomeric layers for improved liner integrity. Various elastomers are used to provide the membrane with self-sealing properties. Although the membrane may include numerous layers, the layers can be classified as follows: - 25 In general, in two or more zones or regions that have similar material properties and / or shrinkage rates, specifically, an outer zone 18 and an expanded or middle zone 19. In the case of a two-zone implant 12, only the outer zone 18 and the expanded or middle zone 19 are provided. As shown in Figures 1, 2, and 4, a three-zone implant 12 may include the outer zone 18, the expanded or middle zone 19, and an inner zone 20. Figure 3 shows a two-zone implant 12. In some non-limiting aspects or configurations, the multiple layers of the elastomeric membrane are classified into zones based on the volume enclosed by the respective layers at the time of curing. For example, as described in more detail herein, the volume enclosed by the outer zone 18 layers at the time of curing may be smaller than the volume enclosed by the expanded or middle zone 19 layers at the time of curing, causing the outer zone 18 layers to exert a contraction force against the middle zone 19 layers. For example, a volume enclosed by the outer zone 18 at the time of curing may expand from approximately 10% to approximately 500% or more before forming the expanded or middle zone 19.In some modalities, the degree of expansion of the outer zone 18 is selected so that the completed implant 12 naturally returns to a size slightly larger than the size of the outer zone 18 when it was originally formed. For example, the completed membrane 214 may naturally conform to enclose an inner volume that is between approximately 10% and approximately 40% larger than the volume enclosed by the outer zone 18 at the time of its formation. In order to impart this contraction force, at least some of the outer zone 18 layers must be durable, essentially waterproof, exhibit stable memory characteristics, and still remain highly elastic. For example, the outer zone 18 layers may have a Shore hardness of approximately Shore A-10 to A-40, and preferably approximately Shore A-20 to Shore A-30. In some instances, the respective zone 18 and 20 layers may be formed in different enclosed volumes. For example, the cured outer zone 18 may expand into - 26 increments, and during each expansion, some layers of the mid-zone 19 can be formed. In this way, the layers of the expanded or mid-zone 19 can be subjected to variable contraction forces based, in part, on the volume enclosed by each layer of the respective mid-zone 19 when it forms and / or cures. However, in any case, it is desirable that in the completed implant 12, the expansion and contraction forces provided by the membrane layers are balanced, resulting in a stable implant. The balance of expansion and contraction forces gives the completed implant lining desirable properties, including, for example, rebound and a natural feel. In some preferred, non-limiting embodiments or aspects, an outer surface of an outermost layer of outer zone 18 includes one or more textured portions. For example, the textured portions may include a pattern of ridges and projections to enhance implant adhesion. In some embodiments or aspects, the pattern may resemble granular or crystalline structures on the implant surface. In other preferred, non-limiting embodiments or aspects, an outer surface of an outermost layer of outer zone 18 includes a cross-diagonal design pattern formed from interconnecting lines or waves extending across at least a portion of the implant surface. In other embodiments or aspects, the textured pattern may include a plurality of projections extending from the outer surface 18a of implant 12.For example, these projections can be separated or evenly spaced across a portion of the outer surface. Photographic images show exemplary textured portions of an implant 12 and are presented in Figures 5A to 5C. For example, a portion of an implant 12 that includes a textured portion 12b has a molded or crystalline granular structure and is shown in Figures 5A and 5B. An implant 12 that has a textured portion 12B that has a molded or crystalline granular structure and is surrounded by a flat portion or surface 12c is shown in Figure 5C. With reference again to Figures 1 to 4, in some preferred and non-limiting modalities or aspects, the expanded or middle zone 19 includes multiple layers of softer elastomeric material applied and / or laminated to the outer zone layers hQhRQRI Lznz / q / YILI 18. The layers of the middle zone 19 can be formed by combining silicone materials with different hardnesses to obtain the desired properties. Ideally, the change in the composition of the layers occurs gradually, so that the transition between adjacent layers is not too abrupt. Adjacent layers with similar properties adhere better than layers with different properties. For example, the layers of the expanded or middle zone 19 near the outer and inner zones 18, 20 can be formed to have a hardness similar to the outer and inner zones 18, 20. Moving toward the middle of the middle zone 19, the layers can be made to be gradually softer by increasing the proportion of soft silicone material in the silicone mixture. The overall thickness of the middle zone 19 can be greater than that of the outer zone 18.Paite or the entirety of the middle zone 19 layers may be in a tacky, yet cured, state, which remains soft and elastic. For example, the tacky, soft layers of the expanded or middle zone 19 may have a durometer of approximately Shore 00-10 to Shore 00-40. These flexible characteristics allow these layers to be placed in a state of compression. Specifically, as described in detail herein, during the formation of the elastomeric membrane, the cured outer zone 18 is expanded to allow a larger volumetric shape to be established. Once the middle zone 19 cures over the expanded outer zone 18, both the outer zone 18 and the middle zone 19 shrink to a volume and shape that more closely resembles their original cured form. However, the outer zone 18 generally does not fully shrink back to its original state.However, the outer zone 18 still provides substantial contraction over the softer middle zone 19 by causing the layers of the middle zone 19 to adapt to a smaller volume. In some preferred and non-limiting modalities or aspects, the outer zone 18 and / or the expanded or middle zone 19 may include a combination of soft and hard layers. For example, the soft and hard layers may be laminated alternately on top of each other, thus proportioning a zone 19, 20 that includes both soft and hard properties. For an elastomeric membrane that has only two zones, as hQhRQRI Lznz / q / YILI - 28 shows, for example in Figure 3, that at least one innermost layer 19a of the middle zone 19 must be harder than the other layers of the middle zone 19, in order to enclose and provide a shrinkage force for the soft, sticky layers of the middle zone 19. However, unlike a three-zone membrane in which the inner zone 20 cures after the membrane 12 shrinks, the innermost layer 19a of the middle zone 19 forms while the membrane is in an expanded state. For example, the innermost, harder layer 19a can form on the inner surface of the middle zone 19 just before the membrane shrinks. The innermost layer 19a can have a composition similar to the harder, stiffer layers of the outer zone 18. In some preferred, non-limiting modalities or aspects, the membrane may define an opening 24 to allow access to the interior of the implant 12 during formation and filling. For example, a plug 23 may be inserted and cured in the opening 24 to seal the implant's internal volume. In some instances, the plug 23 functions as a self-sealing injection port that can be used to pre-fill the membrane-enclosed implant 12 to a desired volume prior to implantation. This plug 23 may have a variety of shapes and configurations, such as a one-way valve, a hinge valve, a spring valve, and the like. Furthermore, the plug 23 may include one or more orifices or channels through which specified fluids can be injected into various areas of the implant 12. In other preferred and non-limiting embodiments or aspects, the plug 23 is formed by folding a small portion of the elastomeric layers of the membrane over the opening 24 to seal it. For example, as shown in Figures 16 to 18, the formed membrane may include a neck portion extending from the opening 24, which must be removed to form the completed implant. The neck portion is frequently trimmed after the elastomeric membrane has cured. In some examples, portions of the neck portion may be folded over the opening 24 to form the plug 23 instead of being trimmed from the implant. In other embodiments or aspects, the plug 23 is a flat patch or piece of elastomeric material that is mounted to the implant 12 over the opening 24 using, for example, adhesive or flowable elastomeric material. The flowable elastomeric material can be cured to secure the patch to hQhRQRI Lznz / q / YILI - 29 the elastomeric membrane. In other forms or aspects, the plug 23 can be formed by pouring a small amount of flowable silicone into the opening 24. The flowable material can be cured to form a suitable seal for the implant. After the membrane layers are cured, in some preferred and non-limiting modalities or aspects, the implant's internal chamber or volume 12 can be filled with biocompatible filling materials such as saline or saline with biocompatible thickening agents so that, in the event of leakage, the saline is naturally absorbed. The thickening agents can be designed to provide additional sealing capacity from within the implant. Methylcellulose has a high molecular weight and can be added to saline to give it gel-like properties. Aqueous carboxymethylcellulose has demonstrated biocompatibility and is used in some cosmetic filling agents. Polyethylene glycol (PEG) and saline could also be a suitable combination with thickening characteristics. The high molecular weight of PEG and other similar thickening agents will reduce the risk of leakage from the membrane.Previously, breast implant membranes were generally made as thin as possible to achieve a softer feel. However, thinner membranes carry a higher risk of perforation, capsular contracture, and gel or fluid leakage. The membranes described herein are generally thicker than currently available membranes, resulting in a safer design. For example, the preferred membrane is approximately 1.8 mm to 3.0 mm thick and can be as thick as 5.0 mm. The contraction properties of the present implant are selected to provide the desired natural material feel and softness, even when using a thicker membrane. Exemplary three-zone implant With reference to Figure 4, an implant 12 comprising a three-zone lining is illustrated. An implant 12 having a membrane formed in a three-zone configuration facilitates the self-sealing ability of the implant 12. The implant 12 is generally similar in size and shape to other exemplary implants described herein. For example, the implant 12 generally includes a membrane - 30 A continuous or substantially continuous elastomeric membrane having a total thickness of approximately 0.75 mm to 5.0 mm, preferably approximately 1.0 mm to 3.0 mm, and most preferably approximately 1.8 mm to 2.5 mm. The membrane encloses a volume or chamber of approximately 80 cc to 800 cc. The membrane includes an outer zone 18 formed from a thicker silicone material of approximately Shore A-10 to Shore A-40, and preferably approximately Shore A-20 to Shore A-30. The elastomeric layers of the outer zone 18 enclose and apply substantial compression to the softer, sticky but cured layers of the middle zone 19. As described in relation to other exemplary implants, the layers of the middle zone may have a durometer of approximately Shore A-10 to Shore A-40. The membrane further comprises an inner zone 20 formed from one or more elastomeric layers that are strong and highly resistant to permeability. The layers of the inner zone 20 remain elastomeric and have significant stretchability and return to their original shape. These inner zone 20 layers are cured and set to a desired volume and shape, encapsulating the inner volume or chamber of the implant 12. As described herein, the inner zone 20 layers form when the membrane is in a retracted state. Consequently, the inner zone 20 layers exert a contraction force on the middle zone 20 layers, contributing to substantial compression on the middle zone 20. Therefore, the inner zone 20 contributes to the desirable properties of the implant 12 by increasing compression on the middle zone 19. In a three-zone implant, the middle zone 19 includes multiple layers of softer elastomeric material to envelop the layers of the inner zone 18 in a significantly expanded state. The middle zone 19 may be thicker than either the inner zone 18 or the outer zone 20. During membrane formation, the inner zone 18 expands to allow for the establishment of a larger volumetric shape. Once the middle zone 19 is cured, the inner zone 18 and the middle zone 19 retract to a volume and shape representative of the inner zone 18 in its original cured form. In this way, the softer middle zone 19 is in significant contraction as it is forced to conform to a smaller volume. The layers of the outer zone 20 then form to - 31 wrap the layers of the middle zone 19. The outer zone 20 has similar or identical properties to the layers of the inner zone 18, which are elastomeric, although tough and resistant. The resulting membrane includes a middle zone 19 that is thicker and composed of a softer, shrinkable elastomeric membrane. The middle zone 19 is sandwiched between the inner zone 18 and the outer zone 20, which are made of stronger, more stable elastomeric compounds. In some designs or aspects, the membrane may have varying thicknesses in different areas of the implant 12. Furthermore, as described above, the layering of the middle zone 19 may vary gradually so that adjacent membrane layers have similar mechanical properties. The three-zone configuration facilitates the membrane's self-sealing capability. However, the membrane's design and configuration are not limited to the three-zone configuration. Other elastomeric layer arrangements can also be used to provide the membrane's self-sealing capability. Furthermore, as will be appreciated by those with regular skill in the field, manipulating these zone layers and their configurations will yield additional advantages of this invention. For example, multiple shrinkage layers will increase the membrane's integrity and self-sealing potential. The thicknesses of the shrinkage layers are also directly related to the membrane's integrity. Therefore, a balance between the optimal number of layers and layer thicknesses can be established for particular applications. In some preferred and non-limiting modalities or aspects, the implant 12 formed from a three-zone membrane can be punctured with a non-core needle to access one or more chambers enclosed by the membrane. Non-core needles are used to puncture the membrane without removing any of the silicone materials that make up the membrane layers. The geometry of a non-core needle spreads and expands the silicone at the entry site. When the needle retracts from the membrane, the silicone self-seals at the penetration site. The silicone must be under contraction forces for self-sealing. This contraction is achieved by holding the silicone membrane under mechanical compression from hQhRQRI Lznz / q / YILI - 32 other elastomeric layers. The self-sealing properties of the membrane produce an implant lining that exhibits different properties from existing implants. Compression of the mid-zone 19 changes how inflation forces manifest in terms of the overall feel of the implant 12. More specifically, the implant 12 can be varied in design to produce a more natural feel with less of an inflated or balloon-like characteristic. Furthermore, the membrane properties introduce a favorable variable that can be incorporated into various single- or multi-chamber designs. For example, it is possible to alter the membrane characteristics to produce a saline-filled implant with more silicon-like characteristics. Implant formation method Having described in general terms the structure of different types of elastomeric membranes and implants, we will now describe in detail the manufacturing methods for these implants. As anyone familiar with this field will appreciate, the manufacturing possibilities for these implants are extensive with respect to both methods and materials. Reverse emptying method In some preferred and non-limiting modalities or aspects, the membrane is formed in a mold in reverse order (e.g., a reverse-casting method) from an outer layer to an inner layer. The methods described herein also include varying the volume enclosed by the respective layers to thereby impart a substantial contraction force, particularly to the middle layer 19 of the implant 12. With reference to Figures 6 to 11, a method of forming implant 12 by casting in a mold is illustrated. Various casting methods can be used, ranging from simple manual techniques to mechanical centrifugal casting. The layers of the respective zones 18, 19, and 20 are cast and cured in reverse order, starting with the outer zone 18 layers. As shown in Figure 6, a mold 17 is used to produce the viscoelastic outer zone 18 layers, which are desirable to be highly durable, essentially impermeable, and exhibit stable memory characteristics. - 33 still remain highly elastic. In some preferred and non-limiting embodiments or aspects, mold 17 is formed from a transparent material to allow visual inspection during the casting process. Mold 17 may be a flexible structure that can expand and contract to form layers and / or zones having different enclosed volumes. For example, mold 17 may be formed from various flexible and stretchable plastics. In other embodiments or aspects, mold 17 may be formed from a rigid, non-expandable material, such as glass, having a constant volume and used only for forming the outer zone 18 layers. In that case, other zones (for example, the middle zone 19 and / or the inner zone 20) may be formed once the cured outer zone 18 layers are removed from mold 17.For example, as described herein, the cured outer zone 18 can be inserted into an expandable bladder 17a during the formation of the middle and / or inner zones 19, 20. In other examples, the cured outer zone 18 can be sufficiently rigid so that the middle and / or inner zones 19, 20 can be formed in the cured outer zone 18 without using a mold or bladder to support the cured outer zone 18. In some examples, mold 17 can be disposable and configured for single use. For instance, molds made from plastics can be inexpensive to manufacture and can be discarded after a single use. Advantageously, implants formed from a disposable mold can be highly customized for specific applications. For example, the implant's volume and shape can be customized for individual patients. Furthermore, the texturing on the inner surface of the mold can be specifically tailored for particular uses. As shown in Figure 6, a flowable material, such as liquid silicone, is introduced into the interior of mold 17. The flowable material can be dispersed across the inner surface of mold 17 by centrifugation and / or inversion of mold 17 until the entire surface is covered. Desirably, the flowable material flows into the textured protrusions and channels on the inner surface of mold 12 so that the outer surface of the outer zone 18 conforms to the texture of the inner surface of mold 17. Once the flowable material has been uniformly dispersed, it can be allowed to stabilize and cure. - 34 In some examples, the flowable material cures at room temperature. In other examples, the mold 17 and the flowable material contained within it can be heated to cure the flowable material and thus form an elastomeric layer. Additional layers of the outer zone 18 can be laminated to the inner surface of the outermost layer 18a, thus forming a thicker outer zone 18. The outer zone 18 can be completed once the collected layers reach a desired thickness. The purpose of this initial stage is to produce a complete shape of the viscoelastic layers of the outer zone 18, as shown in Figure 6. An illustration of a cured outer zone 18 removed from the mold 17 is shown in Figure 7. As shown in Figure 8, an apparatus 33, such as a vacuum evacuation chamber, is used to expand and retract the cured outer zone 18 and / or the mold 17 for the removal of the remaining layers. The outer body of the apparatus 33 is rigid, with an evacuation valve 34 and an internal bladder 17a. The purpose of this apparatus 33 is to expand and retract the layers of the outer zone 18 and / or the mold 17 throughout the remainder of the lamination process. The bladder 17a has a base shape that reflects the final shape of the preferred, non-limiting modality of the implant illustrated, for example, in Figures 1 to 4. The bladder 17a has elastic properties and strong shape memory. In some examples, the bladder 17a may include perforations to allow communication between the mold cavity and the evacuation chamber 35 created by the outer body of the apparatus 33. With continued reference to Figure 8, the pre-formed viscoelastic outer zone 18 layers are placed inside the bladder 17a. In some examples, the outer zone 18 layers may remain in the mold 17, and both the zone 18 and the mold 17 may be inserted into the bladder 17a. In other examples, the outer zone 18 layers may be removed from the mold 17 and inserted into the bladder 17a. The cured outer zone 18 may be inserted directly into the evacuation chamber 35 without a support mold 17 or bladder 17a. Once the chamber 35 is inserted, the bladder 17a may be retracted to conform to the shape of the cured outer zone 18. Light vacuum pressure may be required to hold the outer zone 18 layers and / or the mold 17 in place. The bladder 17a and outer zone layers 18 are sealed around a collar of the apparatus body hQhRQRI Lznz / q / YILI 33. Vacuum pressure is maintained by using an evacuation valve. 34. In certain embodiments, the contact surface between the bladder 17c and the viscoelastic layers of the outer zone 18 may require lubrication to equalize and match conforming shapes. Once positioned and retained, the apparatus 33 is configured to expand the bladder 17a together with the viscoelastic layers of the outer zone 18 to a desired size and shape. As shown in Figure 9, the bladder complex 17a and the pre-formed outer zone layers 18 are expanded and held in an expanded shape by closing the evacuation valve 34 to seal the evacuation chamber 35. For example, if the outer zone layers 18 have a cured diameter of 7 cm and an enclosed volume of 180 cm³, in the expanded shape, the outer zone 18 may have a diameter of approximately 15 cm and an enclosed volume of approximately 1770 cm³. Once the desired amount has been expanded, the expanded mold cavity is ready for laminating the middle zone layers 19. In some examples, as described herein, one or more of the middle zone layers 19 are required to achieve a tacky, yet cured, state that remains soft and elastic. In particular, the middle zone layers 19 desirably have flexible characteristics that allow the layers to be placed in a compressed state.The layers of the middle zone 19 are emptied in one or more layers by manual or mechanical processes, similar to the layers of the outer zone 18 previously emptied. In some preferred and non-limiting embodiments or aspects, the implant 12 can be formed as a two-zone implant comprising only elastomeric layers of the outer zone 18 and the middle zone 19. In that case, at least the innermost layer 19a of the middle zone 19 is a harder layer similar to the layers of the outer zone 18. In order to deposit the innermost hard layer 19a of the middle zone 19, after forming the soft, sticky layers of the middle zone 19 as described above, the innermost layer 19a is formed by introducing a harder elastomeric material into the inner cavity of the mold 17a, dispersing the elastomeric material over the surface of the membrane, and curing the material to form the innermost hard layer 19a. After the emptying of the middle zone layers 19 is completed, the hQhRQRI Lznz / q / YILI - 36 layers are subjected to compression by opening the evacuation valve 34 to place the cured outer zone 18 and the middle zone 19 in a retracted state. The retraction process can be performed in a fully or partially cured state to allow manipulation of the desired characteristics of the membrane complex. This allows the bladder 17a to return to its original shape memory with the laminated outer zone 18 layers and the middle zone 19 layers. It should be noted that although the bladder 17a can return to its original shape, the outer zone 18 layers generally do not fully react to their original cured shape and position but instead assume a slightly expanded configuration compared to the original cured state.For example, for a liner in which the outer zone 18 has a cured diameter of approximately 7 cm and an enclosed volume when cured of approximately 180 cm³, the final or retracted diameter of the outer zone 18 may be approximately 9 cm, and it has an enclosed volume of approximately 382 cm³. Consequently, the textured outer surface of the outer zone 18, formed from the contact between the outer zone 18 and the inner surface of the mold 17, is not an identical representation of the texturing and / or protrusions and channels on the inner surface of the mold 17. Instead, the texturing of the outer surface of the implant 12 takes on a slightly expanded configuration. The texturing of the inner surface of the mold 17 can be selected with the degree of expansion of the formed implant 12 in mind. The formed elastomeric membrane can be removed from the mold 17 and restretched before filling to modify the implant's resilience and elasticity. In some modalities or aspects, prestretching includes stretching the membrane by expanding the volume enclosed by the membrane by a substantial amount. Some implants 12 formed by the processes described herein can expand up to 3000% without rupture (e.g., a 500 cc implant expands to 15 1). In other examples, membrane prestretching may include portions of the membrane stretching to increase the flexibility of selected portions of the implant. Additionally, in some cases, prestretching may include performing multiple inflations and / or adjusting the duration of each inflation or the ambient temperature during membrane inflation. In other examples, the amount of stretching or percentage of inflation may be hQhRQRI Lznz / q / YILI - 37. Adjustment. In some modalities or aspects, especially for thicker elastomeric membranes, the membrane can be warmed or heated before stretching or tensioning. In one example, external pressure (e.g., compression) can be applied to portions of the membrane as it is inflated to impart variable prestretch. For example, if the two posts of implant 12 are pushed forcefully toward each other, the equatorial portion of implant 12 will expand more, resulting in a softer and more flexible portion of the membrane after the prestretching process is complete. Following pre-stretching, in some preferred and non-limiting aspects or modalities, the interior volume or cavity of the membrane is cleaned by appropriate means. After cleaning, the membrane can be enclosed by trimming the excess membrane formed along the collar of the appliance 33 and by inverting a remaining flange around the orifice or opening 24 of the membrane in an inward direction, toward the middle of the posterior surface of the implant 12 to form the plug 23. The plug 23 is then cured to seal the implant 12, thereby forming a completed two-zone implant. Exemplary completed two-zone implants are illustrated, for example, in Figures 3 and 11. In some preferred and non-limiting modalities or aspects, plug 23 is formed from viscoelastic material similar to the mid-zone 19. Plug 23 functions as a self-sealing injection port that can be used to prefill the implant's inner volume or chamber 25 to a desired volume prior to implantation. Biocompatible thickening agents can also be prefilled prior to implant sealing. The implant 12 is filled or partially filled with a fluid, for example, saline solution, prior to implantation in the patient. With reference to Figures 12 to 15, a process for forming a three-zone implant 12 is illustrated. The process is generally similar to the process for fabricating the two-zone implant described in relation to Figures 6 to 11. In particular, as shown in Figure 12, the elastomeric material is introduced into the mold 17 and cured to form an outer zone 18. The texturing can be transferred from the inner surface of the mold 17 to the outer surface of the implant in the manner shown in Figure 12. - 38 mentioned herein. In some embodiments or aspects, after curing, the outer zone 18 is removed from the mold 17 and placed in the bladder 17a. In other examples, the mold 17 and the cured outer zone 18 are inserted into the bladder 17a together. As shown in Figure 13, the outer zone 18 and / or the mold 17 are expanded and retained in an expanded shape by closing the evacuation valve 34 to seal the evacuation chamber 35. As in the examples described above, the expanded mold cavity is ready for laminating the layers of the middle zone 19. In some examples, one or more of the layers of the middle zone 19 are required to achieve a tacky but cured state, which remains soft and elastic. These layers of the middle zone 19 may have flexible characteristics that allow the layers to be placed in a compressed state.The layers of the middle zone 19 are emptied in one or more layers by manual or mechanical processes, similar to the layers of the outer zone 18 previously emptied. After the middle zone 19 cures, the lining, which includes the outer zone 18 layers and the middle zone 19 layers, is retracted as described above. Once zones 18 and 19 are retracted, as shown in Figure 14, the appliance is configured for its final molded state. Specifically, the outer zone 18 and middle zone 19 are retracted to a shape representative of the final implant shape 12. Adequate vacuum pressure is maintained in the evacuation chamber 35 to stabilize the shape for molding. Once the membrane is stabilized in a desired shape, one or more viscoelastic layers of the inner zone 20 are emptied in a manner similar to the previously emptied layers.For example, the flowable viscoelastic material for forming inner zone 20 layers can be introduced to the inner surface of the membrane or lining either manually (e.g., by pouring a flowable elastomeric material into the mold) or using a mechanical or automated device to introduce this flowable material. In some preferred and non-limiting embodiments or aspects, the inner zone 20 layers are very durable, essentially waterproof, exhibit stable memory characteristics, and yet remain highly elastic. In some preferred and non-limiting embodiments or aspects, the membrane can be sealed by a plug 23 as described above in relation to the two-zone elastomeric membrane. In other examples, the membrane can be sealed by hQhRQRI Lznz / q / YILI - 39 One or more layers of the inner zone 18, as shown in Figure 15. For example, the outer zone 18 and middle zone 19 layers may define an opening 24 to allow the casting of additional layers into the hollow space or chamber. The innermost layer of the inner zone 20 may be formed as a continuous layer extending into the opening 24 to seal the membrane. Once the layers of the inner zone 20 are in place, the inner zone 20 may be cured to produce the completed implant 12. Once the layers of the inner zone 20 are cured, the three-zone membrane is complete and ready for removal. The vacuum is released, and the laminated implant liner is pulled through the collar of the appliance neck 33. In some preferred, non-limiting embodiments or aspects, the implant 12 can be filled into the mold 17. For example, before enclosing the inner zone 20, biocompatible gel can be introduced into the implant cavity 12 or the hollow space. Biocompatible thickening agents can also be pre-filled before sealing the implant 12. The implant 12 is filled or partially filled with a fluid, such as saline solution, before implantation in a patient. Once the fluid is introduced, the cavity can be sealed in any of the ways described herein. For example, the plug 23 can be cured into the opening 24, or a portion of the inner zone 20 can be formed to enclose the opening 24. The filled implant 12 can be removed from the mold 17 by breaking the mold 17 in half. In other examples, the mold 17 can be a reusable two-piece mold.In that case, the filled implant 12 can be removed from the mold 17 by separating the pieces of the mold 17 and removing the filled implant 12 from it. In other preferred and non-limiting embodiments or aspects, the mold 17 may be formed from a degradable or dissolvable material. In that case, after the inner zone layers 20 are cured and / or after the completed implant 12 is filled, the mold 17 may be dissolved to release the implant 12 from it. In some embodiments or aspects, dissolving the mold 17 may involve placing the mold 17 and the formed implant 12 in a bath of a fluid capable of dissolving the mold 17. For example, the mold 17 may be formed from collagen. In that case, the collagen mold 17 may be dissolved by immersion in a solution of acetic acid or another fluid. - 40 suitable. In other examples, as described in relation to the two-zone modalities, the formed implant 12 can be removed from the mold 17 before filling. After the implant 12 is removed, it can be filled to a desired quantity for a particular patient and / or use. In that case, the unfilled implant can be removed through a small opening in the orifice without breaking the mold. The mold can then be reused to form additional implant devices. Further steps for removing the implant from the mold, filling the collapsed implant with a biocompatible gel or liquid, and preparing the formed implant for patient treatment will be evident to those typically skilled in the field. Drip emptying method In other preferred and non-limiting aspects of a manufacturing process, drip casting can be used to form an elastomeric membrane. Drip casting around a mandrel is a more conventional method for forming the primary shell of a breast implant. Figures 16 to 27 show different processes for forming viscoelastic membranes around mandrels. With reference to Figures 16 to 27, methods for forming an elastomeric membrane by drop casting around a mandrel 117 are presented herein. Generally, the inner zone 118 layers are formed on the mandrel 117. The mandrel 117 is subsequently exhausted, collapsed, or removed from the formed layers. There are many potential materials that can be used to form the mandrel 117. Plaster plaster is a good example; however, various plastics can also be used. A plastic mandrel can be mechanically collapsed, softened with solvents, or heated to aid its removal without damaging the silicone castings. Gelatinous substances are another option that can provide sufficient stability to expand a membrane and form a mandrel that can be agitated and removed. Agar or agar-agar is one such form of a polysaccharide that can be molded into firm, stable shapes.The possibilities for casting are extensive and different techniques can be used for various applications in this invention. In a preferred and non-limiting modality or aspect of a process of - 41. In manufacturing, after the formed membrane is removed from the mandrel 117, an expansion medium 122 is used to expand the formed layers during subsequent stages of the pouring process. This medium 122 is necessary to retain the previously poured membrane in a desired expanded state, as well as to support a membrane volume in a contracted state. The expansion medium 122 has many possible material selections and techniques of use. Gases and fluids under pressure are the simplest media that can be used. Agar and other materials that can be poured and emptied to a fixed volume and shape can also be used. Agar has a low melting point, which allows it to be liquefied for removal or poured again, as required. Spheres are another option that produces fixed volumes of variable shapes.The advantages and disadvantages of the various means of expansion will become evident based on the requirements of the particular manufacturing state. A preferred, non-limiting manufacturing method using drip casting around a mandrel 117 is shown in Figures 16 to 19. Figure 16 is a cross-sectional view of the drip casting mandrel 117. The mandrel 117 is formed from a material that will be destroyed after the inner zone 118 layers are cast. Thus, the mandrel 117 can be described as an exhausted drip casting mandrel. The mandrel 117 can be cast in plaster plaster. Plaster plaster is a viable option since it can be cast very thinly and can be easily removed by mechanical means and / or dissolved with sodium bicarbonate and water. Multiple elastomeric layers are drip-cast onto the mandrel 117 to form the inner zone 118 of the membrane. The viscoelastic layers of the inner zone 118 are very durable, essentially waterproof, have stable memory characteristics and still remain very elastic. In Figure 17, the mandrel 117 has been exhausted, and the inner zone lining 118 has been filled with expansion medium 122 through a filling tube 121 to expand the lining to a desired volume. The expansion medium 122 is required to be a stable medium that can be altered in volume. The filling tube 121 has three functions: it inflates the inner lining 118, allows the expansion medium 122 to pass through it, and fills the expanded volume. Once hQhRQRI Lznz / q / YILI - 42 obtains the desired shape, the filling tube 121 becomes a support handle which causes the drip-pour mandrel to apply the viscoelastic layers of the middle zone 119. The layers of the middle zone 119 are applied directly onto the inner zone 118. The layers of the middle zone 119 are in a sticky but cured state, which remains soft and elastic. These flexible characteristics allow these layers to be placed in a state of compression. Figure 18 illustrates the third drip-emptying stage. In this stage, a portion of the expansion medium 122 has been removed to return the membrane to a volume and shape representative of the original mandrel 117. The filling tube 121 is used to create a vacuum that retracts the inner zone layers and the middle zone layers 119 to conform to them. The outer zone layers 120 are drip-emptied to enclose the middle zone 119 and inner zone 118 layers. The three-zone lining is complete when the outer zone 120 layers cure. These viscoelastic outer zone 120 layers must be highly durable, essentially impermeable, exhibit stable memory characteristics, and still remain highly elastic. The outer zone 120 layers are essentially the same as, or similar to, the viscoelastic layers of the inner zone 118. Figure 19 illustrates a non-limiting and preferred embodiment of implant 110 formed from a three-zone membrane in its completed state. To produce implant 110, the expansion medium 122 is removed, producing a hollow liner. The liner is cleaned, and the excess membrane, formed along the filling tube 121, is removed by trimming. The permanent flange around the orifice remaining in the middle of the posterior face of the implant is inverted inward, and a plug 123 is cured to seal implant 112. The plug 123 is formed from a viscoelastic material, similar to the material forming the middle zone 119. The plug 123 functions as a self-sealing injection orifice that can be used to prefill a main chamber 125 of the implant 112, enclosed by the membrane, to a desired volume prior to implantation.This plug 123 can take on a variety of shapes and configurations, such as a one-way valve, a chamela valve, a flexible valve, and the like. Furthermore, the plug 123 can include one or more orifices or conduits through the hQhRQRI Lznz / q / YILI. - 43 which insert specified fluids into the various areas of the implant 112. Biocompatible thickening agents can also be prefilled before sealing the implant 112. The implant 112 is filled or partially filled with a fluid, such as saline solution, before implantation in a patient. In another preferred, non-limiting embodiment, mandrel 117 is an expandable structure that can be used to form layers of the inner zone 118, the expanded or middle zone 119, and optionally, the outer zone 120. For example, an expandable mandrel 117 can be an inflatable balloon formed from a flexible rubbery material. Desirably, at least one outer surface of the expandable mandrel 117 is not formed from silicone to prevent portions of the implant membrane from adhering to the mandrel 117 during curing. The volume of the expandable mandrel 117 or balloon can be increased by inflating the mandrel 117 with a fluid (e.g., air or saline solution) to adjust the mandrel's volume. For example, the anterior zone 118 layers can be formed around the mandrel 117 in the manner described above.After the inner zone 118 layers have cured, the mandrel 117 can be expanded by introducing fluid into its interior. Once the mandrel 117 has expanded, the expanded or middle zone 119 layers can be formed around the expanded inner zone 118 as described above. After the middle zone 119 layers have cured, the mandrel 117 can be collapsed by removing fluid from its interior, thereby reducing its volume to that enclosed by the inner zone 118 layers at the time of curing. Once the mandrel 117 is collapsed, the outer zone 120 layers can be formed over the middle zone 120 in the manner described above, for example, by pouring liquid silicone over the middle zone 119 layers. After the outer zone 120 is in place, the outer zone 119 layers can be cured.After curing of the outer zone 120, the mandrel 117 can be collapsed or deflated and removed from the mandrel 117 by, for example, sliding the collapsed or deflated mandrel through the opening of the formed elastomeric membrane. With reference to Figures 20 to 23, the steps for forming another preferred and non-limiting modality of an implant by drip emptying are illustrated. Figure hQhRQRI Lznz / q / YILI Figure 4420 is a cross-sectional view of a double-chamber drip-cast mandrel 117 used to form the inner zone 118 of the implant 112. The mandrel 117 is formed into a desired shape from a material that will be destroyed after the layers of the inner zone 118 are cast into shape. The mandrel 117 can be described as an exhaustion drip-cast mandrel. The mandrel 117 can be cast in plaster plaster. The plaster plaster can be cast very thin and can be easily removed by mechanical means and / or dissolved with sodium bicarbonate and water. Multiple elastomeric layers are formed on the mandrel 117 to form the inner zone 118. The viscoelastic layers of zone 118 can be durable, essentially impermeable, exhibit stable memory characteristics, and still remain highly elastic. In Figure 21, the double-chamber mandrel 117 has been exhausted, and both chambers of the inner zone liner 118 have been filled with the expansion medium 122 to expand the liner and retain it at a desired volume. The filling tube 121 has three functions. It inflates the inner liner, allowing the expansion medium 122 to fill the expanded volume. Once the desired shape is achieved, the filling tube 121 becomes a support handle, creating a drip-pour mandrel for applying viscoelastic layers of the middle zone 119. The middle zone 119 layers are formed directly onto the inner zone 118 and cured. As in the previously described modalities or aspects, the expanded or middle zone 119 layers are tacky, but in their cured state, they remain soft and elastic.Furthermore, in some modalities or aspects, the flexible layers of the expanded or middle zone 119 are capable of being placed in a state of compression. Figure 22 illustrates the third drip-emptying stage. In this stage, a portion of the expansion medium 122 is removed to return the membrane to a volume and shape representative of the original mandrel 117. The filling tube 121 is used to create a vacuum to retract the inner zone layers 118 and compress the middle zone layers 119 to conform to it. The outer zone layers 120 are drip-emptied to enclose the middle zone 119 and inner zone 118 layers. The three-zone membrane is completed when the outer zone 120 layers cure. These viscoelastic outer zone 120 layers must be highly durable, essentially impermeable, and exhibit hQhRQRI Lznz / q / YILI - 45 stable memory characteristics while still remaining highly elastic. In this way, they are essentially the same as or similar to the viscoelastic layers of the inner zone 118. Figure 23 illustrates a preferred, non-limiting embodiment of implant 112 in a completed state, formed from the elastomeric membrane shown in Figures 21 and 22. To form implant 112, the expansion medium 122 is removed, producing a hollow liner. The liner is cleaned by appropriate means. After cleaning, a smaller inner chamber 127 of the membrane is folded into an outer chamber 126, thereby forming an implant in which the outer chamber 126 encloses the inner chamber 127. In this way, the membrane of the inner chamber 127 is inverted into its final position. In addition, a portion of the continuous membrane formed along the filling tube 121 becomes the membrane termination. Since this portion of the membrane extends from the posterior face of implant 112, the excess is removed by trimming. Subsequently, a plug 123 is inserted and cured to seal implant 112.Plug 123 is formed from viscoelastic material similar to the middle zone 119. In some embodiments, plug 123 functions as a self-sealing injection port that can be used to prefill the outer chamber 126 and inner chamber 127 of the implant to a desired volume prior to implantation. Biocompatible thickening agents can also be prefilled before sealing the implant. In this final configuration, the implant 112 has a continuous viscoelastic membrane forming two independent, self-sealing chambers. The implant 112 is filled or partially filled with a fluid, such as saline solution, prior to implantation in a patient. With reference to Figures 24 to 27, a preferred, non-limiting embodiment of an adjustable implant 113 is illustrated. Figure 24 is a cross-sectional view of a three-chamber drip-cast mandrel 117 used for the initial formation of the implant 113, according to a preferred, non-limiting embodiment of the invention. The mandrel 117 is formed into a desired shape from a material that will be destroyed after the inner zone layers 118 are cast into shape. The mandrel 117 can be described as an exhaustion drip-cast mandrel 117. In some embodiments, the mandrel 117 can be cast in a drip-casting manner. - 46 Plaster plaster. The plaster plaster can be poured very thinly and can be easily removed by mechanical means and / or dissolved with sodium bicarbonate and water. Multiple elastomeric layers are poured by dripping into mandrel 117 to form the inner zone 118. The viscoelastic layers of the inner zone 118 must be very durable, essentially impermeable, exhibit stable memory characteristics, and still remain highly elastic. In Figure 25, the three-chamber mandrel 117 is exhausted, and the inner zone liner chamber 18 is filled with the expansion medium 122 to expand the liner and retain it at a desired volume. The filling tube 121 requires a retaining clip 124 to seal the neck to the outer chamber 126 and also to pull the two smaller chambers (collectively, the inner chamber 127) away from the outer chamber 126. The filling tube 121 has three functions. It inflates the inner zone liner 118 of the outer chamber 126, allowing the expansion medium 122 to pass through it and fill the expanded volume. Once the desired shape is achieved, the filling tube 121 becomes a support handle, creating a drip-empty mandrel. The viscoelastic layers of the media zone 119 are applied directly to portions of the inner zone 118.In a preferred, non-limiting embodiment, the viscoelastic layer of the middle zone 1179 is poured only by dripping onto the outer chamber 126. The layers of the middle zone 119 are required to achieve a sticky but cured state which remains soft and elastic. These flexible characteristics mean that the layers of the middle zone 119 can be placed in a compressed state. Figure 26 illustrates the third drip-emptying stage. In this stage, a portion of the expansion medium 122 is removed to return the outer chamber 126 to a volume and shape representative of the original mandrel 117. The expansion medium 122 is also added to the inner chambers 127 to fill them to a volume and shape representative of the original mandrel 117. The filling tube 121 is used to create a vacuum pressure, thereby retracting the entire structure and compressing the middle zone layers 119 to conform to it. The outer zone layers 120 are drip-emptied to enclose the middle zone layers 119 and the hQhRQRI Lznz / q / YILI - 47 Inner zone 118. The three-layer lining is complete when the outer zone 120 layers are cured. These viscoelastic outer zone 120 layers must be highly durable, essentially waterproof, exhibit stable memory characteristics, and still remain highly elastic. They are essentially the same as, or similar to, the viscoelastic layers of inner zone 118. The final three-chamber lining consists of an outer chamber lining 126, which has the self-sealing properties of all three layers. The two smaller chambers (collectively, inner chambers 127) comprise only the inner zone 118 and outer zone 120 layers. Figure 27 illustrates another preferred, non-limiting embodiment of an implant 113 formed from the membrane layers of Figures 25 and 26 in their completed state. To produce the completed implant 113, the expansion medium 122 is removed, creating a hollow liner. The liner is cleaned using appropriate methods. The two smaller chambers (collectively, inner chambers 127) are folded into the outer chamber 126. In this way, the membrane of the inner chamber 127 has an inverted outer appearance and a non-inverted inner appearance at its end portion. A continuous portion of the membrane along the filling tube 121 forms the membrane ends. A port for accessing the outer chamber 126 of the membrane is positioned at the membrane ends. Excess material is trimmed from this portion of the membrane. A plug 123 is inserted and cured to seal the implant 113 at the port.As in previous embodiments, plug 123 can be formed from viscoelastic material similar to the mid-zone 119. Plug 123 functions as a self-sealing injection port that can be used to prefill the outer chamber 126 and inner chamber 127 of implant 113 to a desired volume prior to implantation. Biocompatible thickening agents can also be prefilled prior to sealing the implant. Note that inner chamber 127 can be perforated to allow fluid communication between all chambers. In this embodiment, the internal structures of implant 113, specifically inner chamber 127, provide deflection features to slow the fluid movement of the liquid used to fill the chambers. Implant 113 is filled or partially filled with a fluid, such as saline solution, prior to implantation in a patient. hQhRPRI Lznz / q / YILI - 48 With reference to Figures 28 to 30, steps for forming an adjustable implant 114 according to another preferred, non-limiting embodiment or aspect of the invention are illustrated. Figure 28 shows a completed liner formed by drip casting around a mandrel, comprising inner zone layers 118, middle layers 119, and outer zone layers 120. In Figure 28, the expansion medium 1122 is removed, producing a hollow liner. The liner is cleaned after the expansion medium 122 is removed. The liner is inflated sufficiently to maintain its shape, and a temporary plug 130 is placed near a hole in the liner. Viscoelastic curls 129 form and cure over the chambers of the liner. Figure 29 shows the next stage of formation, in which the entire membrane is inverted so that the curls 129 extend into the inner chamber 127. The final configuration of the implant 114 with curls 129 is illustrated in Figure 30. The smaller inner chamber 127 with curls 129 is folded into the outer chamber 126. The inner chamber 127 does not invert into its final position. The curls 129 expand into the outer chamber 126, providing stability to the final shape and deflection characteristics to stop fluid movement in the outer chamber 126. The membrane of the outer chamber 126 remains inverted in its final position. A portion of the continuous membrane formed along the filling tube 121 forms the membrane termination. As this portion of the membrane extends from the back of the implant 113, the excess membrane material is trimmed.As in the previously described modalities, a plug 123 is inserted and cured to seal the implant 114. For example, the plug 123 can be formed from viscoelastic material similar to the mid-zone 119. The plug 123 functions as a self-sealing injection port that can be used to prefill the outer chamber 126 and inner chamber 127 of the implant 114 to a desired volume prior to implantation. Biocompatible thickening agents can also be prefilled prior to sealing the implant. This final configuration of the implant 114 has a continuous viscoelastic membrane forming two independent, self-sealing chambers, specifically an outer chamber 126 and an inner chamber 127. The implant 114 is filled or partially filled with a fluid, such as saline solution, prior to implantation in a patient. hQhRQRI Lznz / q / YILI - 49 Filling of exemplary implant with a cohesive sel In another preferred, non-limiting embodiment of the invention, with reference to Figure 31, an implant 210 includes a cohesive gel 212 enclosed in an elastomeric coating or membrane 214. The gel can be inserted into the membrane or coating in a flowable state and can be cured to impart cohesive properties to the implant 210. An example of a cohesive gel 212 that can be used with the implant 210 is a crosslinked dimethylsilicone gel. The membrane 214 can be any of the membranes shown herein, including, for example, an intrinsically compressible membrane (e.g., the two-zone or three-zone membrane described herein), a non-intrinsically compressible membrane, and / or a pre-stretched membrane.Ideally, the elastomeric lining or membrane 214 exerts a contraction force on the cohesive gel 212, which is balanced by outward forces from the gel 212 to form a stable implant structure. As in the previously described examples, the lining or membrane 214 is formed from a plurality of laminated layers of an elastomeric material, such as silicone. One or more of the layers may be continuous layers that completely enclose the gel 212. In a preferred, non-limiting example, the elastomeric lining or membrane 214 is a single-zone membrane without intrinsic compression. The lining or membrane 214 can have a thickness of between approximately 0.75 mm and 5.0 mm, preferably between 1.0 mm and 3.0 mm, and most preferably between 1.8 mm and 2.5 mm. However, linings with a thickness greater than 5.0 mm may be used for specific applications. The layers of the elastomeric lining or membrane 214 can have a Shore hardness of approximately Shore 00-10 to Shore A-40. In a single-zone membrane without intrinsic compression, all layers of the liner or membrane 214 are formed around a single mandrel (e.g., for drip casting) or in a single mold (e.g., using the reverse casting method). Thus, unlike the previously described modalities, the membrane 214 may not exhibit intrinsic compression. For example, the layers or zones hQfrRrn / Lznz / q / YILI The outer or inner surfaces of membrane 214 may not exert contractile forces on the middle layers or zones of membrane 214, as occurs with other membranes and coverings mentioned herein. Instead, the elastomeric membrane 214 is configured to exert a contractile force on the gel 212. As a result, the volume enclosed by the elastomeric membrane 214 when cured is smaller than the volume of the gel 212. The volume enclosed by the membrane 214 when cured is also smaller than the volume of the finished implant 210, so that in a finished state, the elastomeric membrane 214 exerts the contractile force on the gel 212. For example, the volume enclosed by the lining or membrane 214 when cured may be approximately 50% to 95%, and preferably approximately 80%, of the volume of the finished implant 210.In order to obtain this balanced compression, the volume of the elastomeric lining or membrane 214, when formed, can be expanded by approximately 5% to approximately 50% and preferably approximately 20% before supplying the gel 214 to the inside of the implant 210. In some examples, the coating or membrane 214 is formed from single layers of uniform hardness. In other preferred, non-limiting embodiments or aspects, the membrane 214 can be formed from multiple layers of varying hardness. For example, the layers can decrease in hardness from the outermost layers toward an inner surface 216 of the membrane 214. In that case, the innermost layers of the membrane 214 will be soft. The softer layers have properties that are more similar to those of the cohesive gel 212. Silicon materials bond better with layers that have similar properties (e.g., hardness), so a membrane 214 with softer inner layers bonds more securely with the cohesive gel 212. Accordingly, the membrane 214 can be designed so that the layers undergo a slow transition to a soft state similar to that of the gel 212 to ensure superior bonding.In some instances, the innermost layers of the 214 membrane may include layers with some gel-like properties. In some examples, the outermost layers of the membrane may have a hardness of approximately Shore A-20 to Shore A-40. The innermost layers of the membrane may have a hardness of approximately Shore A-00 to Shore A-20. hQhRQRI Lznz / q / YILI - 51 In some examples, gel 212 is a cohesive gel that has a stable shape or substantially stable shape properties. For example, gel 212 may be a silicone gel that can be cured by applying heat to the filled implant 210. Exemplary gel materials that can be used to fill a cohesive gel implant are described, for example, in U.S. Patent No. 4,455,691, entitled “Silicone gel filled prosthesis,” and in U.S. Patent No. 8,858,630, entitled “Variable cohesive gel form-stable breast implant,” each of which is incorporated herein by reference in its entirety. Other soft polymer materials can also be used for gel 212, including, for example, polyesters, polyacrylamides, and others. The exemplary materials are described in US Patent No. 5,941,909 entitled “Filling material for soft tissue implant prostheses and implants made therewith”, which is incorporated by reference in its entirety. An exemplary method for forming a gel-filled elastomeric implant 210, including a single-zone membrane 214 without intrinsic compression, is shown in Figures 32A to 32E. Figures 32A to 32C show steps for producing a single-zone elastomeric lining or membrane 214 by the reverse pouring method described herein. In other examples, the single-zone lining or membrane may be formed by drip pouring onto a mandrel, as described above. As shown in Figure 32A, a mold 218 is provided. Mold 218 can be similar in shape to the molds described above in connection with reverse casting processing for the multi-zone membrane. In some examples, mold 218 can define an internal cavity that has the same shape as the finished implant, but is smaller. For example, the cavity volume of mold 218 can be between 50% and 95%, and preferably approximately 80%, of the finished implant volume. When mold 218 has the same shape as the finished implant, the membrane expands equally and uniformly to conform to the shape of the finished implant. In other examples, mold 218 can have a different shape than the finished implant. For example, mold 218 can define a hQhRQRI Lznz / q / YILI - 52 simple round shape or other shape capable of expanding to the shape of the finished implant. In some examples, the shape of mold 218 can be selected so that, when expanded, the membrane produces varying contraction forces against the soft gel. For example, the upper and lower portions of the membrane can be configured to exert increased contraction forces on the gel, so that the equatorial portions of the finished implant protrude or exhibit increased resilience. Mold 218 may include a textured inner surface 220 to produce a textured implant. Mold 218 may be a flexible, disposable, single-use product. In other examples, multi-use molds formed from more rigid materials may also be used within the scope of this description. As shown in Figure 32B, a flowable elastomeric material, such as silicone, is injected or poured into mold 218 to form an outer layer of the lining or membrane 214. For example, the elastomeric material may be poured into mold 218 through a narrow opening 222. The elastomeric material may be dispersed onto the textured surface 220 of mold 218 by oscillating or rotating the mold 218. The deposited elastomeric material dries or becomes stable. The process may then be repeated multiple times to deposit multiple layers onto the inner surface of the mold.As described herein, the hardness of the layers can be modified to produce a membrane 214 of varying hardness. For example, the inner layers of membrane 214 can be softer than the outer layers. Once the multiple layers of elastomeric material are deposited onto the inner surface 220 of the mold 218, the elastomeric material can be cured or partially cured to form the single-zone lining or membrane 214. As previously described, the process of depositing and curing the elastomeric material can be carried out multiple times to produce a laminated, multi-layered lining. In some examples, the cured lining or membrane 214 remains open, as shown in Figure 32B, so that the implant can be filled by pouring gel through the opening. In other examples, the lining or membrane 214 can be closed to form a continuous membrane.A continuous membrane can be more durable and less susceptible to leaks compared to hQhRQRI Lznz / q / YILI. - 53 membranes that have an opening covered by a patch or plug. As shown in Figure 32C, after being cured or partially cured, the single-zone lining or membrane 214 is removed from the mold. In other cases, the lining or membrane 214 can be formed by drip casting onto a mandrel as described above. As shown in Figure 32D, the liner or membrane 214 expands into a first finished shape. For example, as shown in Figure 32D, the membrane 214 can be placed in a vacuum chamber mold 224 that has a rigid, pre-set shape defining a cavity with the desired implant shape. The vacuum chamber mold 224 is actuated, causing the liner or membrane 214 to expand to an enlarged volume and take the shape of the mold cavity. For example, a valve 226 can be opened, and a pump can be coupled to evacuate air from the mold 224, creating negative pressure within the mold. In other preferred and non-limiting embodiments or aspects, the membrane 214 can be expanded by pressurizing the internal cavity or volume of the membrane 214 instead of by applying a vacuum force. For example, an opening 228 in the membrane 214 can be connected to a pump or device for inflating the membrane 214. As the membrane 214 is inflated, it can be pressed against a mold, thereby causing the membrane 214 to conform to the shape of the mold. In some preferred and non-limiting embodiments or aspects, the expansion of the lining or membrane 214 involves expanding an internal volume of the lining or membrane 214 by approximately 5% to approximately 50% before filling the lining or membrane 214 with the cohesive gel 212. In one preferred embodiment, the lining or membrane 214 is expanded by approximately 20% before filling the membrane 214 with the cohesive gel 212.It is noted that for modalities that include the cohesive gel 212, the degree of expansion of the lining or membrane 214 is generally less than that required to form a multi-zone membrane with intrinsic compression and shown and described in relation to Figures 6 to 15. Furthermore, in some modalities, the degree of expansion of the lining or membrane 214 is selected so that once the vacuum force is removed, the formed implant 210 returns to a size which hQhRQRI Lznz / q / YILI. - 54 is slightly larger than membrane 214 when it is formed. For example, in its completed state, membrane 214 can enclose a volume which is preferably between approximately 10% and 40% larger than the volume enclosed by membrane 214 when it was originally formed. As shown in Figure 32E, while the vacuum pump remains active and the liner or membrane 214 remains in its expanded state, the liner or membrane 214 is filled with a filling material, such as a flowable cohesive gel 212. For example, the flowable gel can be poured through the opening 228. After the membrane 214 is filled to a desired volume, the opening 228 can be closed or covered, for example, by folding overlapping portions of the liner or membrane 214 against each other to enclose the gel 212. In other examples, an elastomeric plug can be placed in the opening 228 to seal the gel 212. If membrane 214 is a continuous, enclosed membrane, the implant can be filled by injection. For example, an injection needle can be inserted through membrane 214. A second needle for evacuating air from membrane 214 can be inserted through another portion of membrane 214. Once the needles are in place, a fluid, such as a flowable cohesive gel, can be injected into the implant. As the filling material enters the implant, the air is evacuated through the second needle. Once membrane 214 is sealed, the flowable gel 212 can be cured, causing it to transition to a stable, cohesive state. For example, gel 212 can be cured by applying heat to both gel 212 and membrane 214. In some applications, the curing temperature for the cohesive gel is between approximately 110°C and 170°C. In other applications, curing can be initiated using other common techniques, such as applying electromagnetic radiation, UV radiation, or adding a curing agent to the flowable gel material. Curing gel 212 also effectively bonds it to the inner layers of membrane 214. As described herein, in some applications, the inner layers of membrane 214 may have soft, gel-like properties to enhance the bond between gel 212 and membrane 214. hQhRQRI Lznz / q / YILI - 55 The finished implant 210 generally has the shape of the vacuum chamber mold 224. In addition, since the lining or membrane 214 expands while being filled with the cohesive gel 212, the lining or membrane 214 exerts the contraction force against the gel 212. Once cured, the shape-stable cohesive structure of the gel 212 counteracts the contraction force, thus contributing to the resilience and smoothness of the finished implant. Exemplary implants formed from preformed coatings With reference to Figures 33A to 35B, according to another preferred, non-limiting embodiment of the invention, a multi-zone implant, such as a two-zone implant 310 or a three-zone implant 410, can be formed from a preformed elastomeric coating 312, 412, such as a preformed elastomeric lining 312, 412 used in the production of conventional commercially available implants. In these embodiments, the preformed coating 312, 412 is used in place of the outer zone of previous embodiments to provide support or structure for the implant. These preformed coatings 312, 412 are generally formed around a mandrel and comprise multiple laminated layers of an elastomeric material, such as silicone. The preformed coating 312, 412 generally has a thickness of less than 1.5 mm, or preferably a thickness of approximately 0.25 mm to 1.0 mm.The layers of the elastomeric lining or membrane can have a Shore hardness of approximately Shore A-20 to Shore A-40. The preformed lining can enclose an internal volume of approximately 80 cc to 800 cc. The 312, 412 preformed liner generally includes only a single zone of elastomeric layers, meaning that all the layers of the 312, 412 liner are formed around the same mandrel or in the same mold. When the 312, 412 preformed liner is formed, the volume of the mandrel or mold used to form the preformed liner does not change as the layers are formed and cured, as occurs in other implant liner forming methods described herein. Instead, the elastomeric layers are applied one on top of the other in the mandrel or mold and allow the liner to cure into its shape. - 56 preformed single-zone liners, which can be used to form the implant described herein, are commercially available from manufacturers including, for example: Mentor Worldwide LLC of Invine, Texas; Allergan PCL of Madison, NJ; Sientra, Inc. of Santa Barbara, CO; and Polytech Health & Aesthetics GmbH of Dieburg, Germany. Method of forming a two-zone implant from a preformed coating In some preferred and non-limiting aspects or modalities, a method of forming an implant 310 for volumetrically altering, replacing, expanding, or augmenting body tissues from the preformed liner 312 includes providing the preformed liner 312. In its finished form, the liner 312 includes a two-zone elastomeric membrane having an inner surface 330 and an outer surface 336. As shown in Figure 33A, the preformed liner 312 has an inner surface 314 that partially encloses an inner volume 316, an outer surface 318, and an opening 320 for accessing the inner volume. The opening 320 typically has a diameter of approximately 2.5 cm to 4.5 cm, although many different-sized openings may be used within the scope of this description.The preformed lining 312 can be formed from at least one cured elastomeric layer or from a plurality of laminated elastomeric layers. As shown in Figure 33B, the method includes inverting the preformed lining 312 and expanding the interior volume 316 of the inverted preformed lining 312 to an expanded volume, in which the interior volume of the lining 312 is larger than the volume of the preformed lining 312 at the time of lining 312 formation. For example, expanding the lining 312 can include expanding the interior volume of the lining by between 50% and 800%, preferably approximately 500%, compared to the volume of the lining 312 at the time of lining 312 formation. As in the examples described above, a volume of the elastomeric lining 312 can be expanded using a mandrel or mold.For example, the inverted lining 312 can be placed on a mandrel 322 so that the outer surface 318 of the preformed lining 312 makes contact with the mandrel 322, to place the lining 312 in an expanded state. - 57 After the preformed lining 312 is placed onto the mandrel 322, as shown in Figure 33C, an inner zone 324, which includes at least one inner elastomeric layer, forms on the inner surface 314 of the lining 312 while the lining 312 is in the expanded state. For example, one or more layers of the elastomeric material, such as silicone, can be formed on top of each other to form the inner zone 324. Generally, the elastomeric layers are formed either by spraying or applying the silicone material to a surface and allowing the applied layers to cure. In some examples, the elastomeric layers of the inner zone 324 are softer than the layers of the preformed lining 312.For example, the layers of inner zone 324 can have a Shore hardness of approximately Shore 00-100 to approximately Shore A-20 and, for example, can be formed by combining Shore 00-10 and Shore A-20 materials to form inner zone 324. Inner zone 324 can have a thickness of approximately 0.2 mm to approximately 3.5 mm. In that case, the completed two-zone elastomeric membrane has a total thickness of approximately 0.7 mm to approximately 4.5 mm. In some examples, the elastomeric layers of inner zone 324 are substantially similar in material composition. In other examples, the material properties of the different layers may vary to produce an inner zone 324 with varying hardness and / or elasticity. For example, a more proximal layer 326 of inner zone 324 (e.g., a layer of inner zone 324 closer to the preformed liner 312) and the more distal layers 328 (e.g., layers farther from the preformed liner 312, which form an inner surface 330 of implant 310) may be formed from stiffer materials, such that they form a combination of a Shore 00-10 and Shore A-20 material assembly. In some examples, stiffer layers may comprise approximately 10% to 20% of the total volume of inner zone 324.The inner layers of inner zone 324 can be combined (for example, a combination of Shore A-10 elastomer and Shore 00-10 elastomer), becoming progressively softer towards the middle of inner zone 324. Layers near the middle of the inner zone can be soft. For example, middle layers near the middle of inner zone 324 can have a hardness of hQhRQRI Lznz / q / YILI. - 58 Shore 00-10. In general, the combination of softer layers of the 324 interior zone can constitute approximately 80% to 90% of the total volume of the 324 interior zone. As shown in Figure 33D, after the layers of inner zone 324 cure, the lining 312 (which can be referred to as a multi-zone lining, since it includes both the preformed lining 312 and the inner zone 324) is removed from the mandrel 322 and inverted back to its original orientation. Once removed from the mandrel 322, the lining 312 naturally shrinks to a smaller volume, closer to the volume of the preformed lining 312 when it was originally formed (as shown in Figure 33A). In this retracted position, the preformed lining 312 exerts a contraction force on one or more elastomeric layers of the inner zone 324. Since the layers of the inner zone 324 are formed when the preformed lining 312 is in the expanded state, the contraction of the inner zone 324 compresses the layers of the inner zone 324.This compression causes the layers of the inner zone 324 to fold, creating a textured or textured region that has protrusions, grooves, and indentations on the inner surface 330 of the implant 310. Figure 33A shows an expanded view of the liner 312 that includes the texture on the inner surface 330 of the implant 310. After the liner 312 is inverted and retracted to approximately its original volume, a completed implant can be formed. In order to form the completed implant, as shown in Figure 33D, the liner 312 is enclosed to form at least one chamber, in a manner similar to the previous modalities. For example, a piece of elastomeric material, such as a plug or patch 332, can be vulcanized to the outer surface 336 and / or, preferably, to the inner surface 330 of the liner 312 to cover the opening 320 and completely enclose the inner volume 316 of the implant 310. In some examples, the formation of the implant 310 can also include filling the implant 310 with a fluid, such as saline solution or a cohesive gel 334.When a cohesive gel 334 is used as a filling material, in an uncured state, the gel 334 may be fluid enough to flow into the protrusions, grooves, and clefts on the textured inner surface 330 of the implant 310. As the gel 334 cures, it adheres to. - 59 the textured inner surface 330, which creates a more stable boundary zone between the gel 334 and the inner zone layers 324 compared to if the texturing were not present. Specifically, since the textured inner surface 330 has a larger surface area than a flat surface enclosing a similar volume, the cohesive gel 334 is better able to adhere to the inner surface 330 compared to if the texturing were not present. As a result of the stable boundary zone, the mechanical properties of the liner 312 and the implant 310 are improved. For example, as a result of the adhesion between the gel 334 and the textured inner surface 330, the likelihood of delamination of the gel 334 and the inner surface 330 of the liner 312 is reduced. Consequently, the formed implant 310 is better able to maintain its shape, giving the completed implant 310 a more natural appearance and feel.Delamination of the lining 312 and gel 334 can also occur when there is a substantial difference in material properties between the inner surface 330 of the lining and the gel 334. Therefore, it is desirable that the more distal layers 328 of the inner zone 324 be more similar in hardness to the cohesive gel 334 compared to the layers of the preformed portion of the lining 312. Method of forming a three-zone implant from a preformed liner. According to another preferred, non-limiting aspect or embodiment of the present description, the steps for forming the three-zone implant 410 from a preformed liner 412, which includes an elastomeric membrane having a textured inner surface 430 and a textured outer surface 436, are shown in Figures 34A to 34D. In order to form the implant 410, as in the preceding example, a commercially available preformed liner 412 is provided, as shown in Figure 34A, and transformed to an expanded state, as shown in Figure 34B. For example, the preformed liner 412 can be placed on a mandrel 422 such that an inner surface 414 of the liner 412 makes contact with the mandrel 422.With the coating 412 in the expanded state, as shown in Figure 34C, an outer zone 440 including at least one outer elastomeric layer is formed over at least a portion of an outer surface 418 of the preformed coating 412. For example, as in previous embodiments, a plurality of layers of. Sixty elastomeric materials can be deposited onto the surface 418 of the lining 412 and laminated to form the outer zone 440 of the elastomeric layers. In general, the outer zone 440 layers are harder than the inner zone 324 layers (shown in Figures 33A to 33E). For example, the outer zone 440 layers can have a hardness from Shore 00-30 to Shore A-20. The outer zone 440 can have a thickness from approximately 0.1 mm to approximately 1.0 mm. In that case, a three-zone implant lining 410 can have a total thickness from approximately 0.8 mm to 5.0 mm. In some examples, the outer zone 440 layers are formed from materials having different material properties.For example, a more proximal layer 442 (for example, a layer closed to the preformed lining 412) and a more distal layer 444 (for example, the layer furthest from the preformed lining 412) can be formed from firmer materials, while the layers in the middle part of the outer zone 440 can be softer. After the outer zone 440 layers cure, the liner 442 (which can be referred to as a multi-zone liner, since it includes the preformed liner 412 and an outer zone 440) can be removed from the mandrel 422 or mold and inverted so that the inner surface 430 of the implant 410 faces outward. The liner 412 is then expanded again either by using a mold or by placing the liner onto a mandrel 422 in the inverted orientation, so that the outer surface 436 of the implant 410 contacts the mandrel 422. Once the liner 412 is mounted onto the mandrel 422 in its inverted orientation, as shown in Figure 34D, an inner zone 424, which includes at least one inner elastomeric layer, can be formed by applying elastomeric layers to the liner 412.The mandrel 422 used to form the inner zone 424 has a volume that is larger than the volume enclosed by the preformed lining 412 at the time of forming the lining 412. In some examples, the mandrel 422 used to form the inner zone 424 is the same as the mandrel 422 used to form the outer zone 440. In other examples, the mandrels 422 used to form the inner zone 424 and the outer zone 440 may be of different volumes to vary the compression or shrinkage forces applied to zones 424 and 440 by the preformed lining 412. (Similar to hQhRQRI Lznz / q / YILI.) - 61 that in the preceding example, the inner zone 424 may include a plurality of elastomeric layers having the same or varying hardness. Generally, the inner zone 424 is softer than the outer zone 440 of the preformed lining 412. For example, the layers in the inner zone 424 may have a hardness from approximately Shore 00-10 to approximately Shore A-20. After the inner zone 424 is formed, the liner 412 (which is a multi-zone liner with three distinct zones) is removed from the mandrel 422 and inverted back into its original position, as shown in Figure 34A. Removing the liner 412 from the mandrel 422 allows the liner 412 to shrink to a volume closer to the volume of the preformed liner 412 when it was formed. In this orientation, the preformed liner 412 exerts a shrinkage force on the outer zone 440 layers and compresses the inner zone 424 layers, thereby causing the liner 412 to assume a volume smaller than that of the mandrel 422.The retraction of the outer zone 440 layers and the compression of the inner zone 424 layers cause the inner zone 424 and outer zone 440 layers to fold over each other, thereby producing textured regions on the inner surface 430 and outer surface 436 of the implant 410. Figure 35B shows a detailed cross-sectional view of the lining 412, including the textured inner and outer surfaces 430, 436. Once the lining 412 is completed, the implant 410 is formed by enclosing the lining 412 to form at least one chamber. For example, as in the previous examples, the opening 420 of the lining 412 can be enclosed by bonding and / or vulcanizing a piece of elastomeric material, such as a plug or patch 432, to the outer surface 436 and / or, preferably, to the inner surface of the lining, to form a secure seal covering the opening. As in the previous examples, the implant chamber can be filled with a liquid, such as saline solution, or with a cohesive gel which, when cured, adheres to the textured inner surface 430 of the inner zone 424. As previously described, the adhesion between the lining 412 and the cohesive gel 43 is increased as a result of the increased surface area of ​​the textured inner surface 430 compared to hQhRQRI Lznz / q / YILI - 62 with a flat surface that encloses the same volume. The completed three-zone implant 410 is shown in Figures 35A and 35B. The implant 410 includes the enclosed or partially enclosed elastomeric liner 412 and the cohesive gel 434 positioned inside the elastomeric liner 412. As in the previous examples, the cohesive gel 434 adheres to the textured inner surface 430 of the liner 412 to provide a stable boundary zone between the liner 412 and the gel 434, thereby reducing the possibility of delamination. The elastomeric liner 412 includes the preformed portion of the liner 412 comprising at least one elastomeric layer. The elastomeric liner 412 also includes the outer zone 440 and the inner zone 424.As described above, in the completed implant 410, the outer zone 440 and inner zone 424 layers are forced to conform to a reduced volume, which is smaller than the volume enclosed by the inner zone 424 and / or outer zone 440 when cured. As a result of the shrinkage of the outer zone 440 and the compression of the inner zone 424, the inner surface 430 and outer surface 436 of the implant liner 412 are textured. The textured surfaces 430 and 436 are shown, for example, in Figure 35B and in the photographs in Figures 36A and 36B. The cohesive gel 434 is configured to adhere to the textured surface 430 of the inner zone 424 to form a stable boundary zone between the cohesive gel 434 and the inner zone 424.Similarly, the textured outer surface 436 provides increased adhesion between the 410 implant and biological tissues, such as breast tissue, which can improve surgical outcomes. For example, as a result of the textured outer surface 436, the 410 implant can be more securely anchored within the biological tissue. Surfaces with varying degrees of texturing, such as different fold sizes or crevice depths, can be formed using materials of different hardness and / or rely on varying degrees of layer shrinkage and compression. While many different distributions are possible, generally, the smoother inner zone 434 will have larger folds to provide additional surface area to promote adhesion between the gel hQhRQRI Lznz / q / YILI - 63 cohesive 434 and the inner surface 430 of the lining 412. Figure 36A shows a photograph of an exemplary inner surface 430 that includes large folds. Generally, the textured surface 436 of the outer zone 440 has a more granular appearance with a larger number of smaller folds. Figure 36B shows a photograph of an exemplary outer surface 436. Although the invention has been described in detail for illustrative purposes based on what are currently considered the most practical and preferred embodiments, it should be understood that this detail is solely for that purpose and that the invention is not limited to the described embodiments but, on the contrary, is intended to encompass equivalent modifications and arrangements. For example, it should be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

Claims

1. A method for forming an implant for volumetrically altering, replacing, expanding, or augmenting body tissues, characterized in that it comprises: providing a preformed lining formed from at least one cured elastomeric layer, the preformed lining comprising an outer surface, an inner surface, and a perforation for accessing the interior volume of the preformed lining; expanding the preformed lining to an expanded state, in which the interior volume is greater than the interior volume of the preformed lining at the time of forming the preformed lining; forming an interior zone comprising at least one inner elastomeric layer over at least a portion of the interior surface of the preformed lining while the lining is in the expanded state, thereby forming a multi-zone lining;reducing the internal volume of the multi-zone lining, thereby contracting at least one inner elastomeric layer of the inner zone and causing texturing of at least one inner elastomeric layer; and forming the implant by enclosing the multi-zone lining to form at least one chamber.

2. The method according to claim 1, characterized in that the expansion of the preformed coating to the expanded state comprises inverting the preformed coating and placing the inverted preformed coating on a mandrel so that the outer surface of the coating makes contact with a surface of the mandrel.

3. The method according to claim 2, characterized in that the volume enclosed by the mandrel surface is greater than the internal volume of the preformed liner at the time of forming the preformed liner. hQhRQRI Lznz / q / YILI 4. The method according to claim 2, characterized in that reducing the internal volume of the multi-zone lining comprises removing the multi-zone lining from the mandrel and returning the multi-zone lining to a non-inverted orientation.

5. The method according to claim 1, characterized in that expanding the preformed lining comprises expanding the internal volume of the preformed lining by between 50% and 800% compared to the volume of the preformed lining at the time of forming the preformed lining.

6. The method according to claim 1, characterized in that the formation of the inner zone comprises, while the preformed coating is in the expanded state, forming a plurality of laminated inner elastomeric layers of varying hardness on the inner surface of the preformed coating.

7. The method according to claim 6, characterized in that a more proximal layer of the plurality of inner elastomeric layers and a more distal layer of the plurality of inner elastomeric layers are firmer than the middle layers of the plurality of laminated inner elastomeric layers.

8. The method according to claim 7, characterized in that the most proximal layer and the most distal layer of the plurality of inner elastomeric layers are formed by combining elastomeric materials having a hardness of up to Shore A-20, and wherein the middle layers of the plurality of inner elastomeric layers have a hardness of between approximately Shore 00-10 and Shore A-10.

9. The method according to claim 1, characterized in that the formation of the implant comprises filling the interior volume of the multi-zone lining with a flowable elastomeric material and curing the flowable elastomeric material to form a cohesive gel.

10. The method according to claim 9, characterized in that the cohesive gel is bonded to the texturizing of at least one inner elastomeric layer.

11. The method according to claim 10, characterized in that the volume of the cohesive gel when cured is between approximately 5% and 50% greater than the volume enclosed by the preformed coating at the time of forming the preformed coating. hQhRQRI Lznz / q / YILI 12. The method according to claim 1, characterized in that it further comprises forming an outer zone comprising at least one outer elastomeric layer covering at least a portion of the outer surface of the preformed coating while the preformed coating is in the expanded state and before forming the inner zone.

13. The method according to claim 12, characterized in that it further comprises reducing the internal volume of the preformed coating after forming the outer zone, which causes texturing of at least one outer elastomeric layer of the outer zone.

14. The method according to claim 13, characterized in that the texturing of the outer area is configured to provide an adhesion region to enhance adhesion with surrounding body tissues.

15. The method according to claim 12, characterized in that the outer zone comprises a plurality of outer elastomeric layers of varying hardness ranging from approximately Shore 00-30 to Shore A-20.

16. The method according to claim 12, characterized in that the formation of the outer zone comprises placing the preformed coating on a mandrel, so that the inner surface of the preformed coating is in contact with the surface of the mandrel, and applying at least one outer elastomeric layer to the outer surface of the preformed coating.

17. The method according to claim 16, characterized in that a volume enclosed by the mandrel is greater than the volume of the preformed lining, at the time of formation of the preformed lining.

18. A method for forming an implant for volumetrically altering, replacing, expanding, or augmenting body tissues, characterized in that it comprises: providing a preformed lining formed from at least one cured elastomeric layer, the preformed lining comprising an outer surface, an inner surface, and an orifice for accessing an inner volume of the preformed lining; placing the preformed lining onto a mandrel to expand the preformed lining to an expanded state in which the inner volume of the preformed lining is greater than the volume of the preformed lining at the time of forming the preformed lining;although the preformed lining is on the mandrel, the formation of an outer zone comprises at least one outer elastomeric layer on at least a portion of the outer surface of the preformed lining, while the preformed lining is in the expanded state, to form a multi-zone lining; placing the multi-zone lining on the mandrel in an inverted orientation, in which the outer zone of the multi-zone lining makes contact with the mandrel; forming an inner zone comprising at least one inner elastomeric layer on at least a portion of the inner surface of the multi-zone lining, while the multi-zone lining is on the mandrel and in the expanded state;reducing the internal volume of the multi-zone liner by removing the multi-zone liner from the mandrel to thereby contract the at least one outer elastomeric layer and the at least one inner elastomeric layer, and causing texturing of at least one outer elastomeric layer and the at least one inner elastomeric layer; and forming the implant by enclosing the liner to form at least one chamber.

19. An implant for volumetrically altering, replacing, expanding, or augmenting tissues, characterized in that it comprises: an enclosed or partially enclosed elastomeric coating formed from a plurality of laminated elastomeric layers, the elastomeric coating defining an interior volume; and a cohesive gel placed in the interior volume of the elastomeric coating, wherein the elastomeric coating comprises: a preformed coating comprising at least one elastomeric layer, the preformed coating having an inner surface and an outer surface; an outer zone comprising at least one outer elastomeric layer covering at least a portion of the outer surface of the preformed coating; and an inner zone comprising at least one inner elastomeric layer covering at least a portion of the inner surface of the preformed coating;where a volume enclosed by the outer zone and the inner zone at the time of forming the outer zone and the inner zone is greater than a volume of the preformed lining at the time of forming the preformed lining.; 20. The implant according to claim 19, characterized in that the volume enclosed by the outer and inner zones of the implant is less than the volume enclosed by the outer and inner zones at the time of forming the outer and inner zones, so that the preformed coating exerts a contraction force on the inner and outer zones, which causes texturing of the inner and outer zones.