Patent Description:
Contact lenses that provide refractive vision correction are commonplace. Recently, there has been increased interest in contact lenses that perform functions other than just vision correction. In many of these applications, a contact lens may carry a payload for performing various functions. For example, a contact lens may contain a payload of one or more electrical components, such as projectors, imaging devices (imagers), sensors, coils, batteries, MEMS (micro-electro-mechanical systems), accelerometers and magnetometers, etc. These contact lenses may be referred to as electronic contact lenses.

An electronic contact lens has some structure to support the different electrical components and to provide electrical connections between the different components. However, the form factor of such a structure is significantly limited because it must fit in the contact lens. The contact lens has a limited thickness and volume and it is inherently curved rather than planar. Furthermore, light enters the eye through the center of the contact lens. In order to avoid blocking this incoming light, the structure would have to be located outside the center region of the contact lens. This further limits the possible designs of the supporting structure.

As a result, it can be challenging to provide a support and interconnect structure for electrical components, while still meeting the other requirements of the contact lens.

<CIT> describes thinned, flexible surface regions upon which flexible active components may be utilized to attach flexible active components in space/volume constrained devices, for example, a powered ophthalmic device. Thinned, flexible surface regions foster an avenue for enhanced functionality because various electronic circuits and components can be integrated into polymeric structures.

<CIT> describes methods and apparatus for providing an ophthalmic lens with an energy source capable of powering an electrical component incorporated into the lens.

<CIT> describes an elastic electronic circuit adapted to provide three dimensional elasticity while conforming to the curved or angled structures of a swellable medical device, such as a hydrogel or silicone hydrogel contact lens. The elastic electronic circuit can include a first pattern for flexibility in a first dimension, a second pattern for flexibility in a second dimension, and a third pattern for flexibility in a third dimension. Alternatively, the elastic circuit can include a first pattern for flexibility in a first dimension and a second pattern for flexibility in a second dimension. The resulting three-dimensional elasticity enables the use of electronic circuits on soft contact lenses, where manufacture and use will cause the lenses and circuits to swell and shrink. Furthermore, the electronic circuit will not distort the vision correction of the contact lens or otherwise cause discomfort or other negative side effects.

<CIT> describes antennas and antenna systems that may be designed and configured for incorporation into mechanical devices, including medical devices, such as ophthalmic devices, including contact lenses. These antennas and antenna systems may be utilized to transmit data from the mechanical device to a receiver, to receive data from a transmitter, and/or to inductively charge an electromechanical cell or the like incorporated into the mechanical device.

Embodiments of the disclosure have other advantages and features which will be more readily apparent from the following detailed description and the appended claims, when taken in conjunction with the examples in the accompanying drawings, in which:.

The figures and the following description relate to preferred embodiments by way of illustration only. The invention is set out in the claims.

A contact lens may contain payloads for performing various functions. For example, a contact lens may contain electrical components such as projectors, imaging devices, sensors, coils, batteries, MEMS (micro-electro-mechanical systems), accelerometers and magnetometers, gyroscopes, etc. The electrical components are contained within the limited space of the contact lens and typically must also have electrical connections such as for power, control and data. Furthermore, many electrical components, such as semiconductor devices, are designed to be mounted to a flat surface, while contact lenses are inherently curved.

In one approach, a substrate bent into a non-planar shape is used to carry the electrical components. For example, the substrate may be constructed from a flexible circuit board that is bent into a three-dimensional shape that fits inside an electronic contact lens. The bent circuit board has certain regions which are flat for mounting the electrical components. The bending to create the three-dimensional shape occurs between the flat regions. The components may be mounted to the circuit board, such as by surface mounting or flip-chip mounting of semiconductor devices, before the circuit board is bent into shape.

In one design, the circuit board is bent into the shape of a band with flat facets. Bending between the facets creates a non-planar annular shape (for example, a many-sided frustum) that fits inside the electronic contact lens. The facets themselves remain flat to provide flat surfaces for mounting electrical components.

In another design, the circuit board has a flat annular core portion, with flat tabs that extend radially from the flat annular core. The annular core portion fits inside the contact lens without bending. Bending between the flat tabs and the core portion create a non-planar shape that fits inside the contact lens, while leaving the tabs flat in order to provide flat surfaces for mounting electrical components.

Further details are provided using an eye-mounted display as an example of an electronic contact lens, although it should be understood that other types of electronic contact lenses may also be produced. <FIG> shows a user wearing a display mounted in a scleral contact lens <NUM>. <FIG> also shows an accessory necklace <NUM>, which is discussed with <FIG>. <FIG> shows a cross sectional view of the scleral contact lens <NUM> mounted on the user's eye. Scleral contact lenses are designed to not move around on the wearer's eye. The eye <NUM> includes a cornea <NUM> and a sclera <NUM>. The scleral contact lens <NUM> is supported by the sclera <NUM> and vaults over the cornea <NUM>. A tear fluid layer <NUM> may be formed between the contact lens <NUM> and the cornea <NUM>. Oxygen permeates through the contact lens <NUM> to the cornea <NUM>.

The contact lens <NUM> contains payload(s). For example, the payload(s) may include electronics, including electronics that require a power source such as a battery or a coil that is inductively powered. In the example of <FIG>, the payloads include a small projector that projects images onto the wearer's retina (referred to as a femtoprojector <NUM>), and the corresponding electronics <NUM> to operate the femtoprojector. These are powered by the receiver coil <NUM>, which is positioned around the periphery of the contact lens. The femtoprojector <NUM> may include an LED frontplane with an LED array, an ASIC backplane with electronics that receives the data to drive the LED frontplane, and optics to project light from the LED array onto the retina. The femtoprojector <NUM> preferably fits into a <NUM> by <NUM> by <NUM> volume or even into a <NUM> by <NUM> by <NUM> volume.

The femtoprojector <NUM> is positioned over the cornea since it projects images onto the retina. The electronics <NUM> may be positioned away from the cornea, as shown in <FIG>. For convenience, the contact lens <NUM> is divided into a central zone and a peripheral zone. The central zone overlaps the cornea <NUM>. The area outside the cornea is part of the peripheral zone. In <FIG>, the femtoprojector <NUM> is located within the central zone of the contact lens because it projects images into the user's eye, while the electronics <NUM> and coil <NUM> are located in the peripheral zone. Because people have eyes of different sizes and shapes, for convenience, the central zone may be defined as the <NUM> diameter center area of the contact lens (i.e., within <NUM> radius of the central axis of the contact lens). The diameter of the boundary between the cornea and the sclera is typically <NUM>-<NUM>. Payload components that project light onto the retina typically will be located within the central zone due to the required optical path. Conversely, payload components that do not project light onto the retina or otherwise interact with the retina may be located on the edge of the central zone or outside the central zone so that they do not block light from reaching the retina.

Other examples of powered payloads include sensors, imagers, and eye tracking components such as accelerometers, gyroscopes and magnetometers. Payloads may also include passive devices, such as a coil or antenna for wireless power or data transmission, capacitors for energy storage, and passive optical structures (e.g., absorbing light baffles, beam-splitters, imaging optics). The contact lens <NUM> may also contains multiple femtoprojectors, each of which projects images onto the user's retina. The contact lens <NUM> moves with the user's eye <NUM> as the user's eye rotates in its socket. Because the femtoprojectors are mounted in the contact lens <NUM>, they also move with the user's eye and project to the same region of the retina. Some femtoprojector(s) may always project images to the fovea, and other femtoprojector(s) may always project images to more peripheral regions which have lower resolutions. As a result, different femtoprojectors may have different resolutions. The images from different femtoprojectors may be overlapping, to form a composite image on the wearer's retina.

With respect to the contact lens, terms such as "top", "front", "outer" and "anterior" refer to the direction away from the wearer's eye, while "bottom", "rear" "inner" and "posterior" refer to the direction towards the wearer's eye.

<FIG> is a functional block diagram of an eye-mounted display using the scleral contact lens described above. The display can be divided into a data/control subsystem <NUM> and a power subsystem <NUM>.

In this example, the receive path of the data/control subsystem <NUM> includes an antenna <NUM>, receiver circuitry <NUM>, a data pipeline <NUM>, and a femtoprojector <NUM>. Data from an external source is wirelessly transmitted to the display and received via the antenna <NUM>. The receiver circuitry <NUM> performs the functions for receiving the data, for example demodulation, noise filtering, and amplification. It also converts the received signals to digital form. The pipeline <NUM> processes the digital signals for the femtoprojector <NUM>. These functions may include decoding, and timing. The processing may also depend on other signals generated internally within the contact lens, for example eye tracking sensors <NUM> or ambient light sensing. The femtoprojector <NUM> then projects the corresponding images onto the wearer's retina. In this example, the femtoprojector <NUM> includes a CMOS ASIC backplane <NUM>, LED frontplane <NUM> and optics <NUM>.

The data/control subsystem <NUM> may also include a back channel through transmitter circuitry <NUM> and antenna <NUM>. For example, the contact lens may transmit eye tracking data, control data and/or data about the status of the contact lens.

Power is received wirelessly via a power coil <NUM>. This is coupled to circuitry <NUM> that conditions and distributes the incoming power (e.g., converting from AC to DC if needed). The power subsystem <NUM> may also include energy storage devices, such as batteries <NUM> or capacitors.

In addition to the components shown in <FIG>, the overall system may also include components that are outside the contact lens (i.e., off-lens). For example, head tracking and eye tracking functions may be performed partly or entirely off-lens. The data pipeline may also be performed partially or entirely off-lens. Each of the arrows on the lefthand side of <FIG> also connects to an off-lens component. The power transmitter coil is off-lens, the source of image data and control data for the contact lens display is off-lens, and the receive side of the back channel is off-lens.

There are many ways to implement the different system functions. Some portions of the system may be entirely external to the user, while other portions may be worn by the user in the form of a headpiece or glasses. For example, see <CIT>, "Headgear Providing Inductive Coupling To A Contact Lens," (<NUM>). Components may also be worn on a belt, armband, wrist piece, necklace, or other types of packs. <FIG> shows an example where some functionality is implemented in a necklace <NUM> worn by the user. In this example, the necklace <NUM> includes a wireless transmitter that communicates with the eye-mounted display <NUM>.

<FIG> are cross-sectional views of an electronic contact lens <NUM> containing an electronics assembly with a non-planar substrate. The scleral contact lens <NUM> includes a core <NUM>. The core <NUM> has a base surface <NUM> that mounts to the sclera of the eye. The core <NUM> also contains the payload(s). In this example, the payloads include the femtoprojector <NUM> and electronics <NUM> (and interconnects between them) and coil <NUM> from <FIG>, as well as other components. The femtoprojector <NUM> is positioned in a central zone of the contact lens because it projects images onto the user's retina. The electronics <NUM> and coil <NUM> are positioned in the periphery of the contact lens, so that they do not block light entering the user's eye.

Electrical components are mounted on a non-planar substrate <NUM>, which positions the components and provides electrical connections between the components. The non-planar substrate <NUM> is initially fabricated as a planar substrate and then bent into a three-dimensional shape that fits inside the contact lens. The three-dimensional shape includes flat facets that carry the electrical components. The electrical components may be mounted onto the substrate and tested while the substrate is still flat. For example, the non-planar substrate may be a flexible circuit board, which also contains conductive traces that provide electrical connections between the components. In some designs, the flat facets are arranged in a band. Bending between adjacent facets in the band forms the three-dimensional shape. After bending, the band of facets may have a three-dimensional annular shape. The entire electronics assembly, including substrate and components, may be encapsulated within the core <NUM>. Further description is provided in <FIG>.

<FIG> also show structures that allow oxygenation of the user's cornea. The contact lens <NUM> also includes a gas-permeable outer covering <NUM> and a gas-permeable inner covering <NUM>. Each covering <NUM>, <NUM> forms a corresponding air gap <NUM>, <NUM> between the covering and the core <NUM>. One or more air shaft(s) <NUM> through the core <NUM> connects the two air gaps <NUM>, <NUM>. This provides a path for oxygen to reach the user's cornea. For example, see <CIT>, "Oxygen Permeable Scleral Contact Lenses With Thick Payloads," (<NUM>).

<FIG> and <FIG> are anterior and posterior perspective views showing the non-planar substrate <NUM> and electrical components of the electronics assembly of <FIG>. The electronics assembly is approximately dome-shaped in order to fit into the contact lens. In the anterior view of <FIG>, the center of the dome-shaped assembly is close to the viewer and the perimeter of the dome is away from the viewer. The surfaces shown in <FIG> face away from the wearer's eye when the contact lens is worn. The posterior view of <FIG> shows a view from inside the dome. The perimeter of the dome is close to the viewer and the center of the dome is away from the viewer. The surfaces shown in <FIG> face towards the wearer's eye.

This particular substrate <NUM> design has a band of twelve flat facets 420A-L. The facets are labelled A-L, where facet 420A is on one end of the band and facet <NUM> is at the opposite end of the band. For clarity, not every facet is labeled in every figure. Two planes intersect in a line, so adjacent facets 420A and 420B meet at an edge region <NUM>, which is bendable. Facets 420B and 420C also meet at a bendable edge region <NUM>, and so on. Facets <NUM> and 420A do not meet. There is a gap <NUM> between facets <NUM> and 420A, as shown in <FIG>.

In this example, the band formed by the twelve facets <NUM> is part of a regular <NUM>-sided frustum. The band of facets is opaque but is positioned such that the band does not substantially block light from entering the eye through the contact lens. In this example, most of the semiconductor devices are mounted on the bottom (posterior surface) of each facet, as shown in <FIG>. The facets <NUM> may be different sizes and/or shapes to accommodate different components. In these figures, positions may be described using a cylindrical coordinate system. "Height" or "z" refers to the direction along the central axis of the contact lens. "Radius" or "r" refers to the radial direction outward from the central axis. Because of the shape of the contact lens, radius and height are not independent. "Azimuth" or "arc" or "θ" is the angular direction in the plane perpendicular to the z-direction.

In the example of <FIG>, the components include three magnetometers <NUM> and four accelerometers 417A-B, which are used for eye tracking. These sensor chips are mounted at specific angles to each other to allow sensing along linearly independent spatial axes. For example, see <CIT>, "Contact Lens-Based Eye Tracking," (<NUM>). The twelve facets form substantially a full annulus so each facet subtends <NUM> / <NUM> = <NUM> degrees of arc. With this layout, four components placed on every third facet are spaced <NUM> degrees apart, and three components placed on every fourth facet are spaced <NUM> degrees apart. The magnetometers <NUM> are mounted on every fourth facet 420D, H and L, so that they are spaced <NUM> degrees apart and they are all approximately the same radial distance from the center of the contact lens.

There are two pairs of accelerometers 417A and 417B. One pair of accelerometers 417A is mounted on diametrically opposing facets 420E and K, in order to increase the distance between them. Similarly, the other pair 417B is mounted on diametrically opposing facets 420C and I. In this configuration, the two pairs of accelerometers are not spaced <NUM> degrees apart, but no two of the accelerometers are mounted on adjacent facets. In an alternative design, the accelerometers may be mounted on every third facet instead of the configuration shown. Radially, the pair 417B is mounted at a larger radius towards the perimeter of the band of facets while the pair 417A is mounted more towards the center of the band, in order to increase the vertical separation between the two pairs. In fact, facets 420E and K are extended towards the center to increase this separation. If additional extension is desired, additional bending may be introduced to conform to the contact lens shape. See the discussion of facet 420I below.

The electronics assembly of <FIG> also includes semiconductor devices <NUM> for the femtoprojector. The optics of the femtoprojector are not shown in <FIG>, but devices <NUM> include the ASIC backplane and LED frontplane for the femtoprojector. For example, see <CIT>, "Advanced Optical Designs for Eye-Mounted Imaging Systems," (<NUM>); <CIT>, "Backplane for Eye-Mounted Display," (<NUM>); and <CIT>, "Ultra-Dense LED Projector Using Thinned Gallium Nitride," (<NUM>). The femtoprojector is located in the center of the contact lens, so the substrate has a narrow bridge <NUM> that extends from the main band of facets <NUM> to the island <NUM> that carries the femtoprojector devices <NUM>. Because the substrate is flexible, the bridge <NUM> may be bent to conform to the contact lens shape. As shown in <FIG>, the island <NUM> has an aperture 424X. The LED frontplane is on one side of the island <NUM> while the femtoprojector optics is on the other side of the island <NUM>. The aperture 424X allows light from the LED frontplane to enter the femtoprojector optics.

This example also includes an outward-facing imager, which is mounted on an extension tab <NUM>. For example, see <CIT>, "Eye-Mounted Device Including a Femtocamera and Femtoprojector," (<NUM>). Semiconductor device <NUM> is the electronics for the imager, such as detector array and processing. If the imager were mounted directly on the existing facet 420I, it would be tilted too far off-axis and may also be blocked by the user's eyelids if positioned too far to the periphery. As a result, facet 420I is shortened (its inner edge is offset relative to the other facets), and a flat extension tab <NUM> extends radially from the facet 420I. Bending at edge region <NUM> allows tab <NUM> to be tilted at a different angle than the main facets <NUM>, so that the imager's field of view is more on-axis. The imager optics are on one side of the substrate <NUM> while the electronics <NUM> are on the other, with aperture 429X between the two.

The electronics assembly in this example also includes a processor <NUM> and RF filter <NUM>. The substrate also includes flat extension tabs <NUM> to carry the coil <NUM>. These tabs <NUM> extend radially from the main facets <NUM> with a bend in between. The holes allow casting resin to flow through the flexible circuit board and around the coil wires.

<FIG> shows the electronics assembly after folding into shape. <FIG> is a posterior view of the electronics assembly before folding. The substrate <NUM> is a flexible, flat circuit board. The circuit board may have conductive traces on only one side. Alternatively, it may have a non-conductive core, with conductive traces on both sides of the core and vias between the two sides of the core. It may also be a multi-layer board. The approximate boundaries of regions that will remain flat after bending are shown by the dashed lines.

The substrate is initially fabricated flat. Components may be placed on the substrate, bonded to it, and electrically tested while the assembly is flat. Semiconductor devices may be mounted on the flat facets using conventional techniques, such as surface mounting or flip-chip mounting. Anisotropic conductive paste (ACP) may also be used to attach semiconductor devices to the substrate. Components may be mounted to either side of the facets or to both sides. Alternatively, the facet may contain a cutout with the component positioned in the cutout. In this way, the total thickness is just the thickness of the component, rather than the thickness of the component plus the thickness of the substrate. In one approach, these components are flip-chip bonded along one edge and the remaining edges are glued with ACP to stabilize the position of the component in the cutout.

<FIG> and <FIG> are anterior and posterior perspective views showing the electronics assembly of <FIG>, with a coil and overmolding. Here, compared to <FIG>, the femtoprojector optics <NUM> and imager optics <NUM> have been mounted onto the substrate. The coil <NUM> has also been mounted onto the substrate.

As more clearly seen in <FIG>, overmolding 610A-L is also added to the facets. After the components are mounted on the flat substrate of <FIG>, the facets <NUM> are overmolded with a polymer. The polymer may be designed to have specific stiffness, dimensional stability, adhesion, and/or moisture sealing properties. The overmolding adds stiffness to the flat facets carrying the electrical components. The electronics assembly is then folded into a conical shape to fit inside the contact lens.

The polymer overmolding <NUM> ensures that each facet remains flat and isolated from the surrounding environment. All bonds from chips to the bus are on flat sections and they are protected from mechanical stress. This overmolding <NUM> encapsulates the electrical components mounted on the facets <NUM>. It protects the components. It also adds stiffness to the flat facets, to further prevent unwanted bending of the flat facets, particularly in locations where electrical components are mounted. Other types of stiffeners may also be used. <FIG> also shows an antenna <NUM>. Alternatively, the antenna may be implemented as a conductive pattern on the circuit board.

The outward-facing (anterior) surfaces of the electronics assembly may be colored to match the coloring and markings of a person's eye, thereby making the contact lens appear more natural when worn.

<FIG> show one example. Other variations will be apparent. For example, each facet may be the same size and shape as all the others, or some of the facets may have sizes and shapes different from the others, or all the facets may be different sizes and shapes. The inner and outer edges of each facet may be different distances from the center of the contact lens. The electrical components may be mounted on the anterior side of the facets, on the posterior side or on both sides.

The tilt angles of the facets and their sizes may be adjusted to accommodate components of different sizes within the confines of the contact lens. Facets may be arranged to lie at specific angles with respect to each other after the substrate is folded into its three-dimensional shape or with respect to the contact lens. For example, in one design, three facets, spaced apart by <NUM> degrees in azimuth, lie in mutually perpendicular orientations when the substrate is folded to its final shape. This type of configuration is useful for eye tracking.

The facets may be based on non-regular frustums. Alternatively, they may be based on multiple frustums. For example, the facets may alternate between two different tilt angles. The odd facets may be based on a frustum with steeper sides and the even facets based on a frustum with less steep sides. Adjacent facets still meet at edge regions, but the edges may be skewed relative to the central axis of the contact lens, and odd and even facets may have different shapes. Different components may have different requirements on their position within the contact lens or their tilt angle relative to the contact lens central axis. The facets may be designed to meet these requirements. Components may also have different sizes and shapes. Some facets may be larger to accommodate larger components.

The band of facets may also have different designs. It does not have to cover a full <NUM> degrees of arc. It may form substantially less than a full annulus. In <FIG>, facets 420A-B do not carry any electrical components other than the coil. They may be omitted if the coil <NUM> is supported some other way. There may be multiple bands. The band may be narrower or wider or less uniform in width. Different facets may also have different widths.

<FIG> and <FIG> are anterior and posterior perspective views showing another electronics assembly. In this example, the non-planar substrate <NUM> includes a band of twelve flat facets 720A-L. Many of these facets carry batteries <NUM>, as shown in <FIG>. Extension tabs <NUM> extend towards the center of the contact lens. These extension tabs <NUM> carry many of the electrical components that were carried by the main facets in <FIG>. The electrical components labeled with 4xx numbers in <FIG> are the same as in <FIG>. Compared to <FIG>, the design in <FIG> has a larger center opening, which may allow for better peripheral vision.

<FIG> is a posterior perspective view showing the electronics assembly of <FIG>, with overmolding. The femtoprojector optics <NUM> and imager optics <NUM> have been added. The semiconductor devices have been overmolded <NUM>.

<FIG> is an anterior perspective view showing yet another electronics assembly. <FIG> is a partial cross-sectional view of the electronics assembly. In this design, the non-planar substrate <NUM> has a flat annular core portion <NUM>. Flat tabs <NUM> extend radially from the annular core <NUM>, and electrical components are mounted on these tabs <NUM>. In one approach, the tabs <NUM> and core <NUM> meet at bendable edge regions. Thus, the overall substrate <NUM> may be fabricated flat, including conductive traces that provide electrical connections to the electrical components. Components may be placed on the substrate, bonded to it, and electrically tested while the assembly is flat. Optics and overmolding may be added. The entire assembly may then be folded into a three-dimensional shape to fit in a contact lens.

This example shows may of the same components as the previous examples. It includes femtoprojector electronics <NUM> and optics <NUM>, and imager electronics <NUM> and optics <NUM>. It also includes magnetometers <NUM> and accelerometers <NUM>, processor <NUM> and RF filter <NUM>. Additional tabs (not shown) may be used to carry a coil or batteries.

In alternate approaches, the tabs <NUM> may be separates pieces from the core <NUM> and later attached to the core <NUM>.

Claim 1:
A non-planar substrate (<NUM>) comprising a flexible circuit board bent into a three-dimensional shape that fits inside an electronic contact lens (<NUM>) designed to be worn on a human eye, the three-dimensional shape including a band of flat facets configured to carry electrical components, wherein the band contains twelve facets (420A-L) that form substantially a full annulus, and the electrical components comprise a first pair of accelerometers (417A) mounted on opposing facets and a second pair of accelerometers (417B) also mounted on opposing facets, wherein no two of the accelerometers are mounted on adjacent facets.