Patent Publication Number: US-11385480-B2

Title: Alignment features that allow for a liquid filled layered stack to assemble

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/278,394, filed on Sep. 28, 2016, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to ophthalmic devices, and in particular but not exclusively, relates to alignment and separation features on optical elements of stacked lens structures. 
     BACKGROUND INFORMATION 
     Presbyopia may be treated with wearable or implantable lenses that provide accommodation. For example, a lens may provide accommodation through electrical stimulation of liquid crystal material included in the lens. The lenses, either implanted or worn on the surface of the eye similar to a contact lens, may include multiple layers of material to provide the accommodation and associated control. 
     The multiple layers, however, may complicate fabrication of the lens due to the size of the components that form the multiple layers and alignment requirements. For example, an optical axis of the lens may add an alignment constraint to the fabrication of the lens. Misalignment of the optical axis of the multiple layers may result in blurred vision. While many fabrication techniques may be available to provide the desired alignment, additional factors of the lens may not be addressed by such techniques. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Not all instances of an element are necessarily labeled so as not to clutter the drawings where appropriate. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described. 
         FIG. 1A  is a plan view of an ophthalmic device including alignment and separation features in accordance with an embodiment of the disclosure. 
         FIG. 1B  is a perspective view of an ophthalmic device including alignment and separation features in accordance with an embodiment of the disclosure. 
         FIG. 2  is a cross-sectional view of an optical stack including alignment and separation features in accordance with an embodiment of the disclosure. 
         FIG. 3  is an illustrative cross-sectional view of a portion of an ophthalmic device  300  including alignment and separation features in accordance with an embodiment of the disclosure. 
         FIG. 4  is a functional block diagram of an ophthalmic device including alignment and separation features in accordance with an embodiment of the present disclosure 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of a system and apparatus that include alignment and separation features on optical elements of stacked lens structures allowing for the assembly of the stacked lens structures are described herein. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
       FIGS. 1A and 1B  are a plan view and a perspective view, respectively, of an ophthalmic device  100  in accordance with an embodiment of the present disclosure. The ophthalmic device  100  may be an on-eye wearable device, such as a contact lens, or an implantable device, such as an intraocular lens (IOL). In some embodiments, the ophthalmic device  100  may be implemented as a smart contact lens that mounts over a user&#39;s eye or as an IOL that is implanted into the anterior chamber, the posterior chamber, or other locations of the user&#39;s eye. In either or both embodiments, the ophthalmic device  100  may include alignment and separation features that provide for radial alignment between multiple optical elements of the ophthalmic device  100  and further provide separation setting features that determine and set a gap of a desired width between adjacent ones of the multiple optical elements. 
     The ophthalmic device  100  may, in general, be disc-shaped, and may have an anterior side, e.g., an external facing side, and a posterior side, e.g., an eye-ward or corneal side. The ophthalmic device  100  may additionally be dome shaped such that the anterior side is convex and the posterior side is concave. In general, the ophthalmic device  100  may have a radius of curvature around a central axis that may be similar to a radius of curvature of at least a portion of a user&#39;s eye, such as the cornea. In some embodiments, the central axis may also be an optical axis of the ophthalmic device  100 . 
     The illustrated embodiment of the ophthalmic device  100  includes a plurality of optical elements disposed in enclosure  150 . In some embodiments, the plurality of optical elements may be formed into an optical stack having, for example, a posterior optical element, a middle optical element, and an anterior optical element. The plurality of optical elements and at least a portion of the enclosure  150  may be formed with the radius of curvature as discussed above. Each of the plurality of optical elements (discussed in more detail in  FIGS. 2 and 3 ) may have the alignment and separation features formed therein and/or thereon. For example, the alignment and separation features may be grooves and/or ridges that form rings around the optical elements at one or more desired radii. For example, the one or more desired radii may be 4 to 10 mm from a central axis, which may coincide with an optical axis, of the ophthalmic device  100 . In general, the radial location of the alignment and separation features may be influenced by various other aspects of the ophthalmic device  100 , such as a desired area for an optic region, etc. The alignment and separation features may form or define various regions in the ophthalmic device  100 , such as an optic region  102 , a reservoir region  104 , a dam  106 , and a seal region  108 . The ophthalmic device, in some embodiments, may further include an external region  110 . The various regions may include gaps between adjacent optical elements that are formed by the alignment and separation features. Additionally, the alignment and separation features may assist with assembly of the ophthalmic device  100 . 
     The enclosure  150  may be formed from a material amenable to being worn on a user&#39;s eye, or implantable into a user&#39;s eye, and may further be an optically transmissive material (e.g., transparent, clear, etc.) that seals the internal components and protects the eye. Enclosure  150  may have concave and convex surfaces similar to a contact lens, have generally flat surfaces, or otherwise in various embodiments. In a contact lens embodiment, enclosure  150  may be implemented as a hydrogel or other permeable polymer material that permits oxygen to reach the eye, or non-permeable materials (e.g., glass, plastic, silicon) may also be used. In an IOL embodiment, enclosure  150  may be implemented as a silicon enclosure, or other hermetically sealable materials. Of course, other optically transmissive and biocompatible materials may be used. 
     The optic region  102  may be an optically active area that provides adjustable optical power using a liquid crystal material, for example. The optic region  102  may encompass a central diameter and may include an optical axis of the ophthalmic device  100 . In some embodiments, the optic region  102  may be around 5 mm in diameter and may be centered on the optical axis. The liquid crystal material may be disposed in gaps formed between adjacent ones of the plurality of optical elements. For example, transparent or semi-transparent electrodes (not shown) of the ophthalmic device  100  may be energized by one or more power sources controlled by control electronics  152  to change an orientation of the liquid crystals of the liquid crystal material with respect to one or more optical elements of the plurality of optical elements. The change in orientation of the liquid crystal material may cause a change in optical power of the ophthalmic device  100 , which may provide accommodation to a user. 
     The reservoir region  104  may be radially outside of and adjacent to the optic region  102 . Alignment and separation features of each of the plurality of optical elements may be arranged to form the reservoir region  104 . The reservoir region  104  may be formed by gaps between adjacent ones of the optical elements, which may be smaller than, equal to, or greater than the gaps associated with the optic region  102 . The reservoir region  104  may hold excess liquid crystal material outside of the optic region  102 , which may be included in the ophthalmic device  100  during assembly, for example. 
     The dam  106  may prevent liquid crystal from escaping out of the reservoir region  104 , and may prevent sealant material disposed in the seal region from breaching the reservoir region in a radially inward direction. The dam  106  may also determine gap widths between the optical elements in the optic region  102  and the reservoir region  104 . The dam  106  may be formed by interlocking the alignment and separation features of the optical elements. For example, a sidewall, e.g., flat area, of a ridge formed in one optical element may contact, e.g., rest upon, a sidewall of a groove formed in an opposing optical element. Alternatively or additionally, the dam  106  may be formed by mating curves of similar or different radii of curvature, or mating, e.g., nesting, v-shaped features. In some embodiments, the alignment and separation features formed on each optical element may be slightly offset from associated features in the opposing elements so that the dam  106  is formed. 
     The seal region  108  may be formed radially outward of the dam  106 . The seal region  108  may be formed by large gaps between adjacent ones of the optical elements and that may allow a sealant to be formed therein to seal in the liquid crystal material. Example sealants may include a gasket or a curable adhesive, to name a couple. The seal region  108  may be formed, for example, due to the alignment and separation features and further due to a thickness of the optical elements reducing in the seal region  108 . 
     In some embodiments, the external region  110  may be radially outside of the seal region  108 . The external region  110  may include edges of the optical elements, control circuitry substrates, such as control electronics  152 , and where an anterior portion and a posterior portion of the enclosure  150  intersect and seal. In some embodiments, one or more substrates for supporting electrical components and connections to conductors may be included in the external region  110 . For example, a disc-shaped substrate may be included outside of the seal region  108  that supports the control electronics  152  and connections. 
     The various regions of the ophthalmic device  100  may, in general, include gaps between adjacent ones of the plurality of optical elements that are formed by the associated alignment and separation features of the optical elements. The alignment and separation features, to be discussed in more detail below, may assist with setting widths of the gaps and that further assist with radial alignment of the optical elements to obtain concentricity between the optical elements. 
       FIG. 2  is a cross-sectional view of an optical stack  246  including alignment and separation features in accordance with an embodiment of the present disclosure. The optical stack  246  may be an example of an optical stack included in the ophthalmic device  100 . The illustrated embodiment of the optical stack  246  includes optical elements  212 ,  214 , and  216  having alignment and separation features  242  formed in or on surfaces thereof. The alignment and separation features  242  may define an optic region  202 , a reservoir region  204 , a dam  206 , and a seal region  208  of the optical stack  246 . The various regions may relate to operational related aspects and/or assembly related aspects of the ophthalmic device  200 . 
     In general, the combination of the optical elements  212 - 216  may form a lens that may either be worn on a user&#39;s eye or implanted into a user&#39;s eye. At least one of the optical elements  212 - 216  in conjunction with a liquid crystal material included in gaps between the optical elements  212 - 216  may provide a dynamic optic capable of providing accommodation to the user. 
     The optical stack  246  may be formed from the optical elements  212 - 216 . Optical elements  212  and  216  may be on opposing sides of optical element  214 , such that optical element  214  is sandwiched between optical elements  212  and  216 . In some embodiments, optical element  212  may be on an anterior side of the ophthalmic device  200 , while the optical element  216  may be on a posterior side. In such an embodiment, the optical element  212  may be external facing, whereas the optical element  216  may be eye-ward or corneal facing. While these designations may be adopted for use in discussion of the present disclosure, they are by no means limiting, and the opposite designations may be adopted instead. The optical stack  246  may be encased in an enclosure  150 . In general, the optical stack  246  may provide the optically active elements of the ophthalmic device, at least within an optic region  202 . 
     Optical element  212  may be a planar substrate formed into disc. In some embodiments, the planar substrate may be dome-shaped such that a convex side is posterior facing and a concave side faces the optical element  214 . Optical element  212  may include one or more features around the disc-shaped planar substrate, which may be formed on the anterior side of the optical element  212 . The one or more features may be disposed at a desired radius from a central axis of the optical element  212 , and in some embodiments, the one or more features may extend from a first radius to a second radius. These features, such as the groove  226  and the ridge  228 , may be physical features cut or molded into the material of the optical element  212 . The groove  226  and the ridge  228  may be part of the alignment and separation features  242  that are associated with the optical element  212 . While only a single groove and a single ridge are shown, the alignment and separation features may include multiple grooves and ridges. Optical element  212  may be formed from a polymer, and may be a rigid, gas permeable polymer in some embodiments. The optical element  212  may or may not have optical power, such as a static optical power. 
     Optical element  214  may be a planar substrate also formed into a disc. Similar to optical element  212 , optical element  214  may be dome-shaped with a convex side facing optical element  212  and a concave side facing optical element  216 . In the optic region  202 , the optical element  214  may have a diffraction lens structure formed on one or both sides, which, in combination with liquid crystal material  244 , may provide a dynamic optic. Additionally, optical element  214  may include one or more physical features at a desired radius, which may at least partially align with the radius the physical features of optical element  212  are located. In some embodiments, the one or more physical features may be formed on both surfaces of the planar substrate, e.g., a posterior surface and an anterior surface. For example, the one or more physical features may include a ride  230  and a groove  232  formed on a posterior side, and a groove  234  and a ridge  236  formed on an anterior side of the optical element  214 . The grooves  232 ,  234  and ridges  230 ,  236  may combined form alignment and separation features  242  associated with the optical element  214 . In some embodiments, the apex of the ridge  230  and the base of the groove  234  may align. The groove  232  and the ridge  236  may similarly align. These features of the optical element  214  may appear as a zig zag when viewed from the side, as shown in  FIG. 2 . The grooves and ridges  232 ,  234  and ridges  230 ,  236  may combined to form kinks or buckles in the optical element  214  that when viewed from above may appear as topographical rings around the optical element  214 , which may be disposed at one or more desired radii from a central axis of the optical element  214 . While optical element  214  is shown to include two ridges and two grooves, e.g. a posterior kink and an anterior kink, there may be multiple kinks in the optical element  214  to form associated alignment and separation features  242 . Similar to the optical element  212 , the grooves  232 ,  234  and ridges  230 ,  236  may be cut into or molded into a polymer material, such as a rigid, gas permeable polymer, used to form the optical element  214 . 
     Optical element  216  may be a planar substrate formed into disc similar to the optical element  212 . In some embodiments, the planar substrate may be dome-shaped such that a convex side faces optical element  214  and a concave side is eye-ward facing. Optical element  216  may include one or more features disposed at a desired radius of the disc-shaped planar substrate, which may be formed on the posterior side of the optical element  216 . In some embodiments, the desired radius may at least partially align with the radius the one or more features of the optical element  214  on the posterior side are disposed. These features, such as the ridge  238  and the groove  240 , may be physical features cut or molded into the material forming the optical element  216 . The groove  240  and the ridge  238  may be part of the alignment and separation features  242  that are associated with the optical element  216 . While only a single a single instance of the alignment and separation features is shown, multiple instances of the alignment and separation features may be included in the optical stack  246 . Optical element  216  may be formed from a polymer, and may be a rigid, gas permeable polymer in some embodiments. The optical element  216  may or may not have optical power, such as a static optical power. 
     Gaps between the optical elements  212 - 216  may be filled with the liquid crystal material  244  in at least the optic region  202  and the reservoir region  204 . For example, gaps  218 ,  220 ,  222  and  224  may be filled with the liquid crystal material  244 . The liquid crystal material may, in combination with at least the optical element  314 , provide a dynamic optic to the ophthalmic device  200  by changing an orientation of the liquid crystals within the liquid crystal material  244 . 
     The optic region  202  may be an optically active region of the ophthalmic device  200  and may include liquid crystal material  244  disposed between the optical elements  212 - 216  within gaps  218  and  220 . The gap  218  being a space between optical elements  212  and  214  that may be filled with the liquid crystal material  244 , and the gap  220  being a space between optical elements  214  and  216  that may also be filled with the liquid crystal material. The optic region  202  may be circular shaped and may be centered on an optical axis of the optical stack  246 . The optic region  202 , in some embodiments, may provide a dynamic optic to a user that provides accommodation by changing an orientation of the liquid crystal material, for example. 
     The reservoir region  204  may be a region that holds excess liquid crystal material. The reservoir region  204  may be formed by the gaps between adjacent ones of the optical elements  212 - 216  that are radially outside of the optic region  202 . For example, the reservoir region  204  may be formed by the portion of the gap  222  that is between the optic region  202  and the dam  206 . The portion of the gap  224  that is similarly situated would also form a part of the reservoir region  204 . In general, the reservoir region  204  may begin on or before the separation and alignment features  242  are located, and the change between the optic region  202  and the reservoir region  204  may be gradual. In general, the reservoir region  204  may be radially outside of and may encircle the optic region  202 . As such, the reservoir region  204  may be annular-shaped and disposed on a perimeter of the optical stack  246 . 
     The dam  206  may be an area where the optical elements  212 - 216  contact or interlock, and may be formed to prevent the liquid crystal material  244  from leaking out of the reservoir region  204  and ultimately the optic region  202 . The dam  206  may be formed by flat surfaces, e.g., sidewalls, of some of the grooves and ridges that form the alignment and separation features  242 . The dam  206  may be arranged radially outward from and may encircle the reservoir region  204 . In general, the dam  208  may be circumferential around a perimeter of the optical stack  246 . 
     The seal region  208  may be a region for including a sealant, for example, to seal in the liquid crystal material  244 . The seal region  208  may be formed by gaps between adjacent ones of the optical elements  212 - 216 , such as gaps  226  and  228 . In some embodiments, the seal region  208  may extend to an edge of the optical elements  212 - 216 . The seal region  208  may also be annular-shaped and encircle the dam  206 . 
     The alignment and separation features  242  associated with each optical element may, when the optical elements are formed into the optical stack  246 , assist with radial alignment of the optical elements  212 - 216 , and may cause the gaps  218 - 228  to be formed. The alignment and separation features  242  may additionally define the optic region  202 , reservoir region  204 , dam  206 , and seal region  208 . More specifically, the relative lateral positioning and size of the alignment and separation features  242  associated with each of the optical elements  212 - 216  may assist with setting widths of the various gaps and assist with radial alignment of the optical elements  212 - 216  to obtain concentricity. 
     The structures that form the alignment and separation features  242  may be formed in or on the optical elements  212 - 216 , and may include various angles in relation to at least one surface of the optical elements  212 - 216 . For example, the ridge  320  may extend up at an angle from an anterior surface of the optical element  214 . In some embodiments, the angle may be less than 50°. In some embodiments, the angle the ridges and grooves make with posterior and/or anterior surfaces of the optical elements may affect various other features of the optical stack  246 , such as electrical coatings formed on such surfaces for example. 
     The dam  206  may be formed upon stacking of the optical elements  212 - 216 . The dam  206  may be formed in areas of the separation and alignment features  242  make contact. For example, the dam  206  may be formed where flat sidewalls of the ridges  228  and  236  rest of flat sidewalls of corresponding grooves  232  and  240 . The resting of the optical elements  212 - 216  at those locations may provide intimate contact between adjacent ones of the optical elements  212 - 216 . Additionally, the ridges and grooves that form the dam  208  may be offset from one another so that the ridges and grooves do not completely nest into one another. The amount of offset in combination with the heights/depths of the ridges and grooves may determine the widths of the various gaps  218 - 228 . For example, the contact between optical elements  212  and  214  that occurs between ridge  228  and groove  232  may determine the width of gaps  218 ,  222 , and  226 . The contact point between ridge  228  and groove  232  may be affected by their relative amount of offset and their relative height/depth. For example, the ridges and grooves of the optical elements  212 - 216  may be around 30 to 90 microns in height/depth. It should also be noted that the width of gap  226 , which may be larger than gaps  218  and  222 , may also be formed by a change in thickness of the optical elements  212 - 216  in the seal region  208 . 
     The widths of the gaps  218  and  220  in the optic region  202  may be determined by the dam  208 , and may also be affected by the diffraction lens formed on the optical element  214 . For example, the width of gaps  218  and  220  may be from 6 to 14 microns when including the diffraction lens aspect. If the diffraction lens aspect is ignored, the width of gaps  218  and  220  may be 2 to 10 microns. The widths of gaps  222  and  224  that form the reservoir region  204  may, for example, be 4 to 20 microns, and the width of gaps  226  and  228  that form the seal region  208  may be from 20 to 100 microns. In some embodiments, the width of gaps  222  and  224  may be, for example, 8 to 12 microns. 
     Radial alignment of the optical elements  212 - 216  may be assisted by the nesting of the grooves and ridges in the reservoir region  204 , and further assisted by the width of the gap in the reservoir region  204 . The grooves  226  and  232  and the ridges  230  and  238  may provide guides for aligning the optical axis of the optical elements  212 - 216 , which may be nested as shown to provide coarse alignment. Additionally, the gap widths of the reservoir area may induce capillary forces to wick in excess liquid crystal material  244  from the optic region  202 , for example. The capillary forces may further cause the gap widths on both sides of the nested grooves/ridges to equilibrate, which may provide more fine radial alignment of the optical elements  212 - 216 . 
     The seal region  208  may have gap widths that provide space for inclusion of sealant material  248 , such as a gasket or adhesive. For example, a liquid sealant material may wick into the gaps  226  and  228 . In some embodiments, the liquid sealant material may be a curable adhesive that may be flash cured after wicking. 
     The optical stack  246  may be formed through various assembly steps. For example, a controlled volume of liquid crystal material  244  may be dispensed in the anterior side of the optical element  212 , followed by the placement of the optical element  214  onto the volume of the liquid crystal material  244 . The alignment and separations features  242  of the optical elements  212  and  214  may form the gap  218  and  222 , and further radially align the two optical elements. Liquid crystal material  244  that may be in excess of a volume of the optic region  202  may be pulled into the reservoir region due to capillary forces. The capillary forces may cause the liquid crystal material  244  to equilibrate around the features in the reservoir region  204 , which may provide finer alignment between the optical elements. A sealant material  248  may then be wicked into the seal region  208  between the optical elements  212  and  214 . The sealant material  248  may then be treated to cause it to remain within the seal region  208 . 
     The above steps may be performed again to add the optical element  216  to the optical stack  246 . Alternatively, the three optical elements  212 - 216  may be assembled with the liquid crystal material  244  before sealant material  248  is applied and treated. 
       FIG. 3  is an illustrative cross-sectional view of a portion of an ophthalmic device  300  including alignment and separation features in accordance with an embodiment of the present disclosure. The ophthalmic device  300  may be an example of the ophthalmic device  100 . The ophthalmic device  300  may include same or similar features as the ophthalmic device  200 , for example, which may not be fully discussed in detail for sake of brevity. The illustrated embodiment of the ophthalmic device  300  includes optical elements  312 ,  314 , and  316  that have separation and alignment features  342  formed therein and/or thereon. The separation and alignment features  342  may define an optic region  302 , a reservoir region  304 , a dam  306 , and a seal region  308 . The ophthalmic device  300  may be worn on an eye or implanted into an eye to provide accommodation, for example. 
     The optical elements  312 - 316  may form an optical stack, such as the optical stack  246 , and which may be encased in enclosure  350 . Enclosure  350  may provide a protective enclosure to the optical elements  312 - 316 , including various other components of the ophthalmic device  300 . Additionally, the enclosure  350  may be formed from a biocompatible material amenable to be worn on an eye or implanted into an eye. For example, encasement  350  may be fabricated of a common material (e.g., PolyMethylMethAcrylate or PMMA) or other optically transmissive materials. 
     Additionally, enclosure  350  may have a size and shape that mounts over the cornea of an eye. In the illustrated embodiment, enclosure  350  includes an external side, e.g., posterior side, having a convex shape and an eye-ward side, e.g., anterior side, having a concave shape. Of course, ophthalmic device  300  may assume other shapes and geometries including a piggyback configuration that attaches to a surface of an eye-mountable carrier substrate having an overall shape that resembles a conventional contact lens. 
     Optical element  312  may be hemispherical-shaped and may provide a top substrate of the optical stack. Further, the optical element  312  may be disposed between optical element  314  and enclosure  350 . The optical element  312  may include a groove and a ridge to form associated alignment and separation features. For example, a shallow u-shaped groove may extend into the optical element  312  and a v-shaped ridge may extend out of the optical element  312 . The optical element  312  may be formed from optically transmissive material, such as a transparent polymer. In some embodiments, the optical element  312  may be formed from a rigid, gas permeable polymer. Additionally, optical element  312  may provide optical power to the ophthalmic device  300  in some embodiments, and, in other embodiments, may not provide any optical power. 
     Optical element  314  may also be hemispherical-shaped and may include a diffraction lens on one or two surfaces within an optic region  302 . For example, a diffraction lens may be formed on an external facing side (in the +Y direction) and/or on an eye-ward side (in the −Y direction). The optical element  314  may include grooves and ridges on both sides, such as the external facing side and the eye-ward side, that form associated alignment and separation features  342 . For example, the optical element  314  has an upward bend followed by a downward bend that together form a serpentine-like shape in the optical element  314 . The serpentine-like shape may form the alignment and separation features associated with the optical element  314 . The serpentine-like shape in the optical element  314  may form grooves and ridges on both sides of the optical element  314 . The optical element  314  may be formed from similar materials as the optical element  312  is formed. 
     Optical element  316  may also be hemispherical-shaped and may provide a bottom substrate of the optical stack. Further, the optical element  316  may be disposed between optical element  314  and enclosure  350  on the eye-ward side of the ophthalmic device  300 . The optical element  316  may include a groove and a ridge to form associated alignment and separation features  342 . For example, a shallow v-shaped ridge may extend up from the optical element  316 , which is adjacent to a v-shaped ridge that also extends out of the optical element  316 . In between the two v-shaped ridges a groove may be formed. The optical element  316  may be formed from similar materials as the other two optical elements are formed. Additionally, optical element  312  may provide optical power to the ophthalmic device  300  in some embodiments, and, in other embodiments, may not provide any optical power. 
     The separation and alignment features  342  include the ridges and grooves formed on or in each of the three optical elements. The relative location and interaction between the separation and alignment features  342  of each of the three optical elements may result in the formation of the various regions of the ophthalmic device  300 , such as the optic region  302 , reservoir region  304 , dam  306 , and seal region  308 . For example, the flat areas of the grooves and ridges that make contact to form the dam  306  may also determine gap widths of the optic region  302  and the reservoir region  304 . While a gap width of the seal region  308  may be additionally influenced by the dam  306 , one or more of the optical elements  312 - 316  may become thinner in the seal region  308 , which may also determine the gap width of the seal region  308 . 
     The optic region  302  may be the optically active area of the ophthalmic device  300  and may be located over the cornea of a user&#39;s eye. The optic region  302  may include gaps between the optical elements that are filled with a liquid crystal material, for example. The liquid crystal material may be electrically stimulated to change orientations so that a change in optical power is provided by the ophthalmic device  300 . The gaps may have a width of 2 to 10 microns, which may be determined by the alignment and separation features  342  of the optical elements  312 - 316  that form the dam  306 . 
     The reservoir region  304  may be formed from the gaps between the adjacent optical elements that are between the optic region  302  and the dam  306 . The gaps between the optical elements in the reservoir region  304  may have widths that are similar to, larger than, or smaller than the gap widths between the optical elements in the optic region  302 . For example, the gap widths in the reservoir region  304  may be 4 to 20 microns. 
     The features of the optical elements that occur in the reservoir region  304  provide radial alignment between the optical elements so that concentricity of optical axes of the optical elements may be achieved. Nesting of the grooves and ridges that occur in the reservoir region may provide the radial alignment. Additionally, the gap widths in the reservoir region  304  may be on an order that capillary forces are induced in the reservoir region by the interaction of the optical elements and the liquid crystal material. The capillary forces may cause the gap width on both sides of the nested grooves/ridges may equilibrate that may cause concentricity to be achieved. Additionally, the capillary forces may assist with assembly of the ophthalmic device  100  by causing the optical elements to self-align. 
     The features of the optical elements that form the dam  306  may be laterally offset from mirror-like features on the adjacent optical elements. Offsetting the ridges/grooves that form the dam  306  may cause a flat surface, e.g., sidewall, of the ridges/grooves to contact one another. For example, the ridge extending down from the optical element  312  may be offset from the opposing groove of the optical element  314  so that the dam  306  is formed where sidewalls of those two features contact. The amount of offset and a height/depth of the ridges/grooves may set the gap widths in at least the optic region  302  and the reservoir region  304 . 
     The seal region  308  may be formed radially outward of the dam  306 , and may have gap widths that are larger than the gap widths of the optic region  302  and the reservoir region  304 . For example, the gap widths that form the seal region  308  may be 30 to 100 microns. While the gap widths of the seal region  308  may be larger than the other discussed gap widths, the gap widths of the seal region may be small enough to induce wicking of a liquid sealant material into the seal region  308 . 
     The various regions and the associated gaps may assist in the relative positioning of the optical elements  312 - 316  during assembly of the optical stack. For example, alignment and separation features  342  may assist with radial alignment of the optical elements  312 - 316  to obtain concentricity, and the dam  306  and the seal region  308  may reduce or eliminate the leakage of liquid crystal material out of the optic and reservoir regions  302 ,  304 , respectively. 
       FIG. 4  is a functional block diagram of an ophthalmic device  400  including alignment and separation features in accordance with an embodiment of the present disclosure. Ophthalmic device  400  may be an on-eye device, such as a contact lens or a smart contact lens, or an implantable device, such as an intraocular lens. In the depicted embodiment, ophthalmic device  400  includes an enclosure material  410  formed to be either contact-mounted to a corneal surface of an eye or implanted into an eye. A substrate  415  is embedded within or surrounded by enclosure material  410  to provide a mounting surface for a power supply  420 , a controller  425 , an antenna  440 , and various interconnects  445  and  450 . The substrate  415  and the associated electronics may be one implementation of the control electronics  152 . The illustrated embodiment of power supply  420  includes an energy harvesting antenna  455 , charging circuitry  460 , and a battery  465 . The illustrated embodiment of controller  425  includes control logic  470 , accommodation logic  475 , and communication logic  480 . As shown, accommodation actuator  430  is disposed in the enclosure material  410 . 
     Power supply  420  supplies operating voltages to the controller  425  and/or the accommodation actuator  430 . Antenna  440  is operated by the controller  425  to communicate information to and/or from ophthalmic device  400 . In the illustrated embodiment, antenna  440 , controller  425 , and power supply  420  are disposed on/in substrate  415 , while accommodation actuator  430  is disposed in enclosure material  410  (not in/on substrate  415 ). However, in other embodiments, the various pieces of circuitry and devices contained in ophthalmic device  400  may be disposed in/on substrate  415  or in enclosure material  410 , depending on the specific design of ophthalmic device  400 . For example, in one embodiment, accommodation actuator  430  may be disposed on a transparent substrate. 
     Substrate  415  includes one or more surfaces suitable for mounting controller  425 , power supply  420 , and antenna  440 . Substrate  415  can be employed both as a mounting platform for chip-based circuitry (e.g., by flip-chip mounting) and/or as a platform for patterning conductive materials (e.g., gold, platinum, palladium, titanium, copper, aluminum, silver, metals, other conductive materials, combinations of these, etc.) to create electrodes, interconnects, antennae, etc. In some embodiments, substantially transparent conductive materials (e.g., indium tin oxide or silver nanowire mesh) can be patterned on substrate  415  to form circuitry, electrodes, etc. For example, antenna  440  can be formed by depositing a pattern of gold or another conductive material on substrate  415 . Similarly, interconnects  445  and  450  can be formed by depositing suitable patterns of conductive materials on substrate  415 . A combination of resists, masks, and deposition techniques can be employed to pattern materials on substrate  415 . Substrate  415  can be a relatively rigid material, such as polyethylene terephthalate (“PET”) or another material sufficient to structurally support the circuitry and/or electronics within enclosure material  410 . Ophthalmic device  400  can alternatively be arranged with a group of unconnected substrates rather than a single substrate  415 . For example, controller  425  and power supply  420  can be mounted to one substrate  415 , while antenna  440  is mounted to another substrate  415  and the two can be electrically connected via interconnects. Substrate  415  may also be a continuous piece of semiconductor, housing all or some of the aforementioned pieces of device architecture as integrated circuitry. 
     Substrate  415  can be shaped as a flattened ring with a radial width dimension sufficient to provide a mounting platform for the embedded electronic components. Substrate  415  can have a thickness sufficiently small to allow substrate f 15  to be embedded in enclosure material f 10  without adversely influencing the profile of ophthalmic device  400 . Substrate  415  can have a thickness sufficiently large to provide structural stability suitable for supporting the electronics mounted thereon. For example, substrate  415  can be shaped as a ring with a diameter of about 10 millimeters, a radial width of about 1 millimeter (e.g., an outer radius 1 millimeter larger than an inner radius), and a thickness of about 50 micrometers. Substrate  415  can optionally be aligned with the curvature of the eye-mounting surface of ophthalmic device  400  (e.g., convex surface). For example, substrate  415  can be shaped along the surface of an imaginary cone between two circular segments that define an inner radius and an outer radius. In such an example, the surface of substrate  415  along the surface of the imaginary cone defines an inclined surface that is approximately aligned with the curvature of the eye mounting surface at that radius. 
     In the illustrated embodiment, power supply  420  includes a battery  465  to power the various embedded electronics, including controller  425 . Battery  465  may be inductively charged by charging circuitry  460  and energy harvesting antenna  455 . In one embodiment, antenna  440  and energy harvesting antenna  455  are independent antennae, which serve their respective functions of energy harvesting and communications. In another embodiment, energy harvesting antenna  455  and antenna  440  are the same physical antenna that are time shared for their respective functions of inductive charging and wireless communications with reader  405 . Additionally or alternatively, power supply  420  may include a solar cell (“photovoltaic cell”) to capture energy from incoming ultraviolet, visible, and/or infrared radiation. Furthermore, an inertial power scavenging system can be included to capture energy from ambient vibrations. 
     Charging circuitry  460  may include a rectifier/regulator to condition the captured energy for charging battery  465  or directly power controller  425  without battery  465 . Charging circuitry  460  may also include one or more energy storage devices to mitigate high frequency variations in energy harvesting antenna  455 . For example, one or more energy storage devices (e.g., a capacitor, an inductor, etc.) can be connected to function as a low-pass filter. 
     Controller  425  contains logic to choreograph the operation of the other embedded components. Control logic  470  controls the general operation of ophthalmic device  400 , including providing a logical user interface, power control functionality, etc. Accommodation logic  475  includes logic for receiving signals from sensors monitoring the orientation of the eye, determining the current gaze direction or focal distance of the user, and manipulating accommodation actuator  430  (focal distance of the contact lens) in response to these physical cues. The auto-accommodation can be implemented in real-time based upon feedback from gaze tracking, or permit the user to select specific accommodation regimes (e.g., near-field accommodation for reading, far-field accommodation for regular activities, etc.). Communication logic  480  provides communication protocols for wireless communication with reader  405  via antenna  440 . In one embodiment, communication logic  480  provides backscatter communication via antenna  440  when in the presence of an electromagnetic field  471  output from reader  405 . In one embodiment, communication logic  480  operates as a smart wireless radio-frequency identification (“RFID”) tag that modulates the impedance of antenna  440  for backscatter wireless communications. The various logic modules of controller  425  may be implemented in software/firmware executed on a general purpose microprocessor, in hardware (e.g., application specific integrated circuit), or a combination of both. 
     Ophthalmic device  400  may include various other embedded electronics and logic modules. For example, a light source or pixel array may be included to provide visible feedback to the user. An accelerometer or gyroscope may be included to provide positional, rotational, directional or acceleration feedback information to controller  425 . 
     The illustrated embodiment also includes reader  405  with a processor  482 , an antenna  484 , and memory  486 . Memory  486  in reader  405  includes data storage  488  and program instructions  490 . As shown reader  405  may be disposed outside of ophthalmic device  400 , but may be placed in its proximity to charge ophthalmic device  400 , send instructions to ophthalmic device  400 , and/or extract data from ophthalmic device  400 . In one embodiment, reader  405  may resemble a conventional contact lens holder that the user places ophthalmic device  400  in at night to charge, extract data, clean the lens, etc. 
     External reader  405  includes an antenna  484  (or group of more than one antennae) to send and receive wireless signals  471  to and from ophthalmic device  400 . External reader  405  also includes a computing system with a processor  482  in communication with a memory  486 . Memory  486  is a non-transitory computer-readable medium that can include, without limitation, magnetic disks, optical disks, organic memory, and/or any other volatile (e.g., RAM) or non-volatile (e.g., ROM) storage system readable by the processor  182 . Memory  486  can include a data storage  488  to store indications of data, such as data logs (e.g., user logs), program settings (e.g., to adjust behavior of ophthalmic device  400  and/or external reader  405 ), etc. Memory  486  can also include program instructions  490  for execution by processor  482  to cause the external reader  405  to perform processes specified by the instructions  490 . For example, program instructions  490  can cause external reader  405  to provide a user interface that allows for retrieving information communicated from ophthalmic device  400  or allows transmitting information to ophthalmic device  400  to program or otherwise select operational modes of ophthalmic device  400 . External reader  105  can also include one or more hardware components for operating antenna  484  to send and receive wireless signals  471  to and from ophthalmic device  400 . 
     External reader  405  can be a smart phone, digital assistant, or other portable computing device with wireless connectivity sufficient to provide the wireless communication link  471 . External reader  405  can also be implemented as an antenna module that can be plugged into a portable computing device, such as in an embodiment where the communication link  471  operates at carrier frequencies not commonly employed in portable computing devices. In some instances, external reader  405  is a special-purpose device configured to be worn relatively near a wearer&#39;s eye to allow the wireless communication link  471  to operate with a low power budget. For example, the external reader  405  can be integrated in a piece of jewelry such as a necklace, earing, etc. or integrated in an article of clothing worn near the head, such as a hat, headband, etc. 
     The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. 
     These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.