WO2014022885A1

WO2014022885A1 - An intraocular device

Info

Publication number: WO2014022885A1
Application number: PCT/AU2013/000871
Authority: WO
Inventors: David Garrett; Owen Burns; Joel VILLALOBOS-VILLA; Kate FOX; Kumar GANESAN; Steven Prawer; Hamish Meffin; Samantha LICHTER
Original assignee: University of Melbourne; National ICT Australia Ltd
Current assignee: University of Melbourne; Data61
Priority date: 2012-08-07
Filing date: 2013-08-07
Publication date: 2014-02-13
Anticipated expiration: 2015-02-07

Description

AN INTRAOCULAR DEVICE

Field of the Invention

The present invention relates to an implantable medical device, such as an intraocular device and relates

particularly, though not exclusively, to a retinal prosthesis.

Background ^'of the Invention

Medical devices that include electronic components are frequently implanted into the human. body. Such medical devices include cochlear implants,' pacemakers, retinal prostheses and other devices. Retinal prostheses for example are positioned within the retina of the eye and need to be protected from ingress of biological fluids.. Such retinal prostheses have an exterior surface that is formed from a biocompatible material. Further, when the retinal prosthesis is positioned₎ within the retina of the eye, stress to the eye tissue should be avoided.

Summary of the Invention

The present invention provides in a first aspect an intraocular device comprising:

a device component comprising a housing having an electrical feedthrough that is fluid impermeable, the device component further comprising an electrode that has a plurality of electrically conductive elements comprisin a diamond material; and a flexible portion arranged to locate the device component at or within biological tissue and to distribute forces between the device component and the biological tissue along at least a portion of the biological tissue..

Throughout this specification the term "diamond material" is used for films or bulk materials of crystalline diamond material, poly-crystalline diamond material, nano- crystalline diamond material and also for diamond-like¹ materials including diamond glassy carbon and diamond-like carbon materials.

In one specific example the intraocular device is a retinal prosthesis. The intraocular device may also comprise first and second attachment elements that are selected such that magnetic forces attract the first and second elements to each other .

,

The first attachment element may be arranged for

positioning such that at least a portion of the device component and a portion of the biological tissue is positioned between the first and second attachment

elements when the intraocular device is localised. In particular, at least a portion of the biological tissue of an eye may in use be positioned between the first and second elements. The first attachment element may be arranged for positioning outside a retina and outside an interior region defined by the retina of the eye, such as within or outside a portion of the sclera of the eye (for example in the suprachoroidal space) . The second attachment element may at- least partially be surrounded by the flexible portion and may be embedded within the flexible portion. The second attachment element may be positioned such that in use at least a portion of the device component is positioned between the first and second attachment elements. Alternatively, the second attachment element may be positioned such that in use., when the intraocular device is localised, the flexible ■ portion and biological tissue is positioned between the first and second attachment elements, but not the device component or a portion thereof.

The flexible portion may at least partially surround the device component and in one example the flexible portion covers the device component in a manner such that only at least a portion of the electrode is exposed.

The flexible portion typically comprises a biocompatible polymeric material. In one specific embodiment the

flexible portion comprises silicone and may at least partially be reinforced. The silicone may be nylon- silicone and may be fibre reinforced (for example using fibres that are formed from a plastics material or a metallic material) .

The flexible portion may have a non-uniform flexibility. The flexible portion typically has a relatively soft surface portion at a contact surface that is arranged such that damage to the biological tissue, such as the retina, is reduced. In one specific embodiment the flexible portion is a layered structure and comprises layers of a flexible material. At least two of the layers may have differing hardnesses. The layered structure may comprise layers that have a hardness ranging from 2 - 80, 4 - 60, 6 - 50, 8 - 40 or 10 - 30 durometer. At least some of these layers of the layered structure may be ordered such that the

hardness of the layers is increasing in a direction through the layered structure and from a contact surface towards the device component.

Alternatively or additionally, the flexible portion may have a contact surface that has a shape that at least approximates an inverse of the shape of the at least a portion of the biological tissue. The contact surface may have a convex or concave shape or any other suitable shape. For example, if the intraocular device is a retinal prosthesis, the contact surface may have a convex shape that is substantially an inverse of the concave shape of a surface of the retina with which the contact surface will be in contact when the intraocular device is positioned at the retina.

The flexible portion may also comprise at least one extension that may extend in a wing-like manner from a body portion of the flexible portion. The at least one extension may be arranged to receive a fastener, such as a magnet (for example the above-described second attachment element) or a tack for localising the intraocular device. The flexible portion may comprise an aperture for

receiving a portion of the fastener and may be fibre reinforced. The electrical feedthrough may also comprise an

electrically insulating diamond material. Further, the electrical feedthrough may also comprise an electrically conductive diamond material that may seal and/or penetrate through an aperture of the electrical feedthrough.

Alternatively, the electrically insulating diamond

material may seal the aperture. In one embodiment the device component comprises one or more interfaces between the electrically conductive diamond material and the. electrically insulating diamond material that may provide a hermetic seal. Each electrically conductive element of the electrode typically has a first end and a second end that is

opposite the first end. Each electrically conductive element may be positioned such that the first and second ends of the electrically conductive element are exposed prior to contacting with another medium. In one

embodiment, the electrode is arranged for use as a

stimulating electrode for stimulating biological tissue such as nerve tissue. Each electrically conductive element of the electrode typically is in direct contact with an electrically insulating material and an interface between the

electrically conductive elements and the electrically insulating material typically is hermetically sealed. The electrode may exclusively be formed of a diamond material. The electrically conductive elements of the electrode may form an array. The conductive diamond material may be nitrogen or boron incorporated or doped. In one specific embodiment the . electrically conductive diamond material of the electrode and/or the feedthrough is nano-crystalline diamond

material, such as a nitrogen incorporated or doped nano- crystalline diamond material.

The electrically insulating material of the electrode and/ or the feedthrough may be composed of a poly-crystalline diamond material such as hydrogen-incorporated ultra nano- crystalline diamond.

The present invention provides in a second aspect an intraocular device, such as a retinal prosthesis, the intraocular device comprising:

a device component comprising a housing and an electrode having a plurality of exposed electrically conductive elements; and

a flexible portion surrounding at least partially the device component and having a contact surface for

contacting a biological tissue, the contact surface being shaped such that, when the intraocular device is secured at the biological tissue portion and the flexible portion is positioned at least in part between the device

component and the biological tissue, a shape · and a

flexibility of the flexible portion result in a

distribution of forces between the device component and the biological tissue along at least a portion of the biological tissue. The contact surface of the flexible portion typically has a shape that at least approximates an inverse of the shape of the at least a portion of the biological tissue. The contact surface may have a convex or concave shape or any other suitable shape. For example, if the intraocular device is a retinal prosthesis, the contact surface may have a convex shape that is substantially an inverse of the concave shape of a surface of the retina at which the intraocular device will be positioned when in use.

The intraocular device in accordance with the second aspect of the present invention may also comprise first and second attachment elements that are selected such that magnetic forces attract the first and second elements to each other. The first attachment element may be arranged for positioning such that at least a portion of the device component and a portion of the biological tissue of an eye is positioned between the first and second attachment elements when the intraocular device is localised. The first attachment element may be arranged for positioning outside the retina and outside an interior region defined by the retina, such as within o'r outside a portion of the sclera of the eye (for example in the suprachoroidal space) . The second attachment element_, may at least

partially be surrounded by the flexible portion and may be embedded within the flexible portion. The second

attachment element may be positioned such that in use at least a portion of the device component is positioned between the first and second attachment elements.

Alternatively, the second attachment element may be positioned such that in use, when the intraocular device is localised, the flexible portion and the biological tissue of the eye are positioned between the first and second attachment elements, but not the device component or a portion thereof. The present invention provides in a third aspect an intraocular device, such as 'a retinal prosthesis, the intraocular device comprising:

a device component comprising a housing and an electrode, the electrode having a plurality of exposed electrically conductive elements; and

a flexible portion surrounding at least partially the device component and having a non-uniform flexibility.

The flexible portion of the intraocular device in

accordance with the third aspect of the present invention may be a layered structure and may comprise layers of a flexible material. At least two of the layers may have differing hardnesses. The layered structure may comprise layers that have a hardness ranging from 2 - 80, 4 - 60, 6 - 50, 8 - 40 or 10 - 30. durometer. At least some of the layers of the layered structure may be ordered such that the hardness of these layers is .increasing in a direction through the layered structure and from a contact surface for contacting biological tissue to the device component.

The intraocular device may also comprise first and second attachment elements that are selected such that magnetic forces attract the first and second elements to each other. The first and second attachment elements may be arranged for positioning such_. that at least a portion of the device component and a portion of the biological tissue is positioned between the first and second elements when the intraocular device is localised.

The present invention provides in a fourth aspect a method of fabricating an intraocular device, the method

comprising the steps of:

providing a device component;

providing a mould having a shape that at least approximates that of a portion of the biological tissue; and

forming a flexible portion in the mould such that a contact surface of the flexible portion has a shape that at least approximates that of an inverse of the portion of the biological tissue, comprising embedding at least a portion of the device component within the flexible portion.

The formed flexible portion may have a non-uniform

flexibility.

The present invention provides in a fifth aspect a method of fabricating an intraocular device, the method

comprising the steps of:

providing a device component; and

forming a flexible portion such that the flexible portion has a non-uniform hardness, comprising embedding at least a portion of the device component within the flexible portion. The method in accordance with the fifth aspect of the present invention typically comprises the step of

providing a mould having a shape that at least approximates that of a portion of the biological tissue. The step of forming the flexible portion may comprise forming the flexible portion in the mould such that a contact surface of the flexible material has a shape that at least approximates that of an inverse of the at least a portion of the biological tissue. ^■

The following introduces features that the method in accordance with either the fourth. or the fifth aspect of the present invention may have.

The intraocular device may be a retinal implant. The formed flexible portion typically is arranged to locate the device component at or within biological tissue and distribute forces between the device component and the biological tissue along the at least a portion of the biological tissue.

The flexible portion typically has a relatively soft surface portion at a contact surface that is arranged such that damage to the biological tissue, such as the retina, is reduced.

The flexible portion may for example comprise silicone. The step of forming the flexible portion may comprise forming a layered structure that comprises layers of a flexible material. At least two of the layers may have differing hardnesses. The layered structure may comprise layers that have a hardness ranging from 2 - 80, 4 - 60, 6 - 50, 8 - 40 or 10 - 30 durometer. At least some of these layers of the layered structure may be ordered such that the hardness of the layers is increasing in a direction through the layered structure and from a contact surface towards the device component.

In one specific example the intraocular device is a retinal prosthesis.

The invention will be more fully understood from the following description of specific embodiments of the invention^' The description is provided with reference to the accompanying drawings.

Brief Description of the. Drawings

Figure 1 is a schematic perspective view of an intraocular device in accordance with a first embodiment of the present invention;

Figure 2 is a schematic cross-sectional representation ,of the intraocular device of Figure 1;

Figure 3 shows a flow diagram illustrating method steps for fabricating an intraocular device within biological tissue in accordance with embodiments of the invention; Figure 4 is a schematic cross-sectional representation of an intraocular device in accordance with a second

embodiment of the present invention;

Figure 5 is an optical image of an intraocular device in accordance with a further embodiment of the present invention; Figure 6 is an optical image of the a stimulating

electrode of the^' intraocular device shown in Figure 4; and

Figures 7 and 8 are schematic cross-sectional

representations of an electrical feedthrough in accordance with an embodiment of the present invention.

Detailed Description of Specific Embodiments

Embodiments of the present invention relate to an

intraocular device such as a retinal prosthesis comprising a device component that includes a housing with an

electrical feedthrough and an electrode. The electrode and the housing form a capsule such that a seal is provided between the electronic components of the device and surrounding tissue when the intraocular device is

implanted in a patient. The device component is at least partially embedded in a flexible material. ¹

Embodiments of the present invention have applications in the field of retinal prostheses for treatment of

particular retinal diseases and for this purpose a retinal prosthesis may be implanted into the retina of a patient. The retinal prosthesis comprises a stimulating electrode array that stimulates neurons in an inner cell layer of the retina which is still intact. Thus, at least some degree of sight can be restored.

Referring initially to Figures 1 and 2, there is shown an implantable intraocular device 100 comprising a device component 102 and a flexible portion 104. The device component 102 has a housing that comprises an electrical feedthrough and an electrode that has a plurality of electrically conductive elements (not shown) .

The electrically conducting elements and electrically insulating elements such as the housing of the device component 102 are composed of diamond material having different electrical properties. The housing has an exterior portion that is embedded in the flexible portion 104.

The intraocular device 100 also comprises a first

attachment element (not shown) and a second attachment element 106 for locating the intraocular device 100 within biological tissue. The attachment elements are attracted to each other by virtue of magnetic forces. A suitable exemplary arrangement of the first and second attachment elements is for example described in patent application No. 2012905040 which is incorporated herein by reference in its entirety.

In this particular embodiment, the first and second attachment elements 106 are magnets that attract each other. The second attachment element 106 is embedded within the flexible portion 104 and located adjacent to the device component 102.. The magnets are positioned such that the device component 102, a portion of the flexible portion 104 and a portion of biological tissue are located between the magnets. In this way, the intraocular device 100 can be positioned and fixated within the biological tissue when the intraocular device 100 is implanted into a patient . However, a person skilled in the art will appreciate that the attachment elements may be positioned such that a portion of the flexible portion 102 and a portion of biological tissue are located between the attachment elements, but not the device component .102.

As shown in Figures 1 and 2, the flexible portion 104 surrounds the device component 102 in a manner such that only a portion of the electrode is exposed.

..

The flexibility of the flexible portion 104 enables some deformation of the intraocular device 100 such that the intraocular device 100 can follow a motion of the

biological tissue when the intraocular device 100 is implanted into a patient.

The flexible portion 102 is composed of a silicone material.. Silicone has the advantage of being a

biocompatible material which is crucial when the

intraocular device 100 is implanted into a patient. A person skilled in the art will appreciate that other suitable materials are envisaged, such as other

biocompatible polymeric materials. The flexible portion 104 illustrated with reference to Figure 2 has a non-uniform flexibility which in this embodiment is realised by having a layered structure of a plurality of silicone layers. Specifically, the flexible portion 104 has a first silicone layer 108 and a second silicone layer 110 that are located near a contact surface 112 that is arranged for contacting biological tissue when the intraocular device 100 is implanted into a patient. The first silicone layer 108 has a hardness that is larger than the hardness of the second silicone layer 110. For example, the first silicone layer 108 may have a hardness of 30 durometer and the second silicone layer 110 may have a hardness of 10 durometer. As such, the hardne&s of the layered structure of the flexible portion 10,4 decreases towards the contact surface 112. In this way, a relatively soft contact surface can be provided that aims to reduce damage to the biological tissue. Simultaneously, a relatively rigid but flexible structure can be provided that surrounds the device component 102 and consequently provides stability of the intraocular device 100.

However, a person skilled in the art will appreciate that the flexible portion 104 may comprise more than two layers of any suitable hardness. Suitable ranges for hardness may include 2-80 durometer.-

The flexible portion 104 is arranged to locate the device component 102 at or within biological tissue and to distribute forces between the device component 102 and the biological tissue along at least a portion of the

biological tissue when the intraocular device 100 is implanted into a patient.

In this particular embodiment, the flexible portion 104 has an overall shape that is substantially flat and that encompasses the device component 102. Specifically, the flexible portion 104 has extensions on opposite lateral sides of the device component 102. In this way, the forces that work between the device component 102 and the

biological tissue are distributed to a larger area that is defined by the . shape of the flexible portion 104 including the extensions. In other words, forces are distributed from a relatively small area that is defined by the shape of the housing of the device component to a relatively large area that is defined by the shape of the flexible portion 104. It should be appreciated that there is no requirement that the flexible portion has a shape that distributes the forces along a substantially rectangular area. Other suitable shapes are envisaged. Further and as shown in Figure 2, the flexible portion 104 is shaped such that the contact surface 112 approximates an inverse of the shape of the biological tissue when the intraocular device is implanted into the biological tissue. For example, in case of a retinal prosthesis, the retinal prosthesis is implanted into the retina of an eye such that the electrode of the prosthesis can stimulate an inner cell layer of the retina. The inner cell layer of the retina has a substantially concave shape, consequently the contact surface 112 of the flexible portion 104 has a substantially convex shape.

A person skilled in the art will appreciate that other suitable shapes are envisaged.

The flexible portion 104 of the intraocular device 100 shown in Figures 1 and 2 also comprises a fin 114 that simplifies handling of the intraocular device 100 when the device 100 is implanted into the biological tissue such as the retina of a patient.

Further, the flexible^' portion 104 has a cylindrical projection 116 that may encompass wires that connect the device component with an external device (not shown) .

In the embodiment shown in Figures 1 and 2, the device, component 102 of the intraocular device 100 comprises electrically conductive and insulating elements that are formed from materials that have substantially the same lattice constants and crystallographic structures. In this example these materials are diamond materials.

The diamond materials of the intraocular devices in accordance with embodiments of the present invention are provided in the form of thin films_, that are formed by thin film growth techniques such as CVD. Electrically

insulating diamond layers may for example comprise poly- crystalline diamond material such as hydrogen-incorporated ultra nano-crystalline diamond. Electrically conductive diamond layers may for example comprise nitrogen- incorporated diamond such as nitrogen-incorporated ultra nano-crystalline diamond. It is to be appreciated by a person skilled in the art that the present invention is not limited to these explicit types of diamond material and any diamond material (or diamond like carbon

material) , having suitable properties may be used.

Referring now to Figure 3, an intraocular device 200 in accordance with a second specific embodiment of the present invention is described. The intraocular device 200 is arranged for implanting into the retina of a patient and for stimulating an inner, cell layer of the retina.

Figure 3 is a schematic cross-sectional representation of the intraocular device 200. The intraocular device 200 comprises an electrode 201 that has a plurality of

electrically conducting elements 202 and electrically insulating material 204 surrounding portions of the electrically conducting elements 202. The electrically conducting elements 202 of the electrode 201 form an array.

The electrically conducting elements 202 and the

electrically insulating elements 204 are composed of diamond material having different electrical properties.

In this particular embodiment, the electrically conducting elements 202 are composed of nitrogen incorporated ultra nano-crystalline diamond material having sp² and sp³ carbon bonds and the electrically insulating elements 204 are composed of polycrystalline diamond material having primarily sp³ carbon bonds.

The intraocular device 200 further comprises feedthroughs 205 (only one feedthough is shown in Figure 3) for

electrically connecting an electronic chip 208 to a power supply and further electronic components positioned at a remote location. The feedthroughs are provided in the form of the feedthrough as described below with reference to Figure 6.

The intraocular device 200 comprises a housing 206 that is also composed of a diamond material. The housing 206 has an exterior portion embedded in a flexible biocompatible material, such as silicone, that is in this embodiment fibre reinforced. The intraocular device 200 comprises a .layer 210 of the silicone material and projections 212 and 214 that are also formed from silicone and in this

embodiment provided in the forms of "wings". The ^'< projections 212, and 214 have reinforced apertures 216 and 218 for receiving titanium tacks (not shown) . The

electrode 201 forms a lid of the housing and a stimulating face of the electrode 201 is exposed.

. The electronic chip 208 is arranged to control stimulating signals or receiving signals. Electrical wires (not shown) establish electrical communication between the chip 208 with an external device (not shown) . The electrical wires are coupled to the feedthroughs 205 and are directed within the silicon material around the apertures 216 or 218 to exit the intraocular device 200 at the projections 212 or 214.

Such an implantable array provides a mechanically robust, ^■ biocompatible and hermetic . seal that is capable of

stimulating nerve tissue in the retina. Figure 4 is an optical image of components of an

intraocular device 250 in accordance with a further variation. The intraocular device 250 comprises an

electrode array 251 and a housing 256 that is also

composed of a diamond material. The housing 256 has an exterior portion that is embedded in silicone. The

intraocular device 250 comprises a layer 260 of the

. silicone and projections 262 and 264 that comprise fibre reinforced silicone. In this embodiment the projections 262 and 264 are provided in the forms of "wings". The projections 262 and 264 have reinforced apertures 266 and 268 for receiving titanium tacks (not shown) . The

electrode 201 forms a lid of the housing 256 and a

stimulating face of the electrode 201 is exposed.

Electrical wires 269 establish electrical communication between the electrode array 251 and an external device (not shown) . The electrical wires 269 are directed within the silicon material around the apertures 266 or 268 to exit the intraocular device 250 at the projections 262 or 264.

Figure 5 is an optical image of the electrode array 251 that is also shown in Figure 4.

Referring to now to Figure 6, an electrical feedthrough of an intraocular device 300 in accordance with an embodiment of the present invention is now described. The shown intraocular device 300 has an electrical feedthrough assembly 302. The intraocular device 300 comprises, electronic components 303 that are electrically coupled to exterior components (not shown) via the feedthrough assembly 302. The intraocular device 300 is arranged for housing the electronic components 303 and is arranged for implantation into the human body. Again, the intraocular device 300 comprises a stimulating electrode and the above described flexible portion that is arranged to distribute forces between the device component such as the housing and biological tissue. The feedthrough 302 assembly comprises a wall portion 304 and an aperture 310 extending entirely through the wall portion 304. An electrically conductive wire 3.06 extends through the aperture 310.

A surface of the wall portion 304 and a portion of the electrically conductive wire 306 are coated by a layer of an electrically insulating diamond, material 308 that penetrates into the aperture 310 and seals the aperture 310. The diamond material 308 encapsulates a portion of the wire 306, which preserves its metallic behaviour and low resistivity. The coverage of the diamond material 308 extends over the exterior surface of the wall portion. The aperture 310 is at least partially filled with the diamond material 308 whereby the wire 306 is irremovably

encapsulated by diamond material 308 within the aperture 310. The interface between the wire 306 and the diamond material 308 is fluid impermeable. The diamond material 308 comprises a poly-crystalline material such as hydrogen-incorporated ultra nano- crystalline diamond. The electrically conductive wire 306 is in this embodiment formed from platinum, but may alternatively also comprise another suitable metallic material, such as gold.

Referring to now Figure 7, an electrical feedthrough 404 of an intraocular device 400 in accordance with an

embodiment of the present invention is now described. The intraocular device 400 comprises a wall portion 402 that has an aperture 404. The aperture 404 is filled with an electrically conductive material, which in this embodiment is an electrically conductive diamond material 406. The electrically .conductive diamond material_. 406 seals the aperture 404 such that the aperture 404 is fluid and gas impermeable.

The intraocular device 400 comprises a stimulating

electrode, housing portions and the above-described flexible portion comprising silicone material that

distributes forces between the device component such as the stimulating electrode and the housing portion, and biological tissue. For locating the intraocular device 400 at or -within biological tissue, the device may further comprise above described attachment elements such as magnets or wings that extend from the flexible portion for receiving tacks (not shown in Figure 7).

The electrically conductive diamond material 406 is flush with an exterior surface of the wall portion 402, but may alternatively extend further. For example, if a mask or masking agent (not illustrated) is used to selectively deposit electrically conductive diamond material 406, the electrically conductive diamond material 406 is likely to extend to the vertical dimension of the mask or masking agent .

As mentioned above,, a CVD system, such as a microwave plasma CVD system, is used to manufacture components of the intraocular device.

Referring now to Figure 8, there^' is shown a flow chart for illustrating method step for fabricating an intraocular device in accordance with an embodiment of the invention. In a first step 502/ a device component such as device component 102 is provided. The device component may comprise a housing, an electrode, a feedthrough and other suitable elements. Further, a mould is provided (step 504) that has a shape which approximates the shape of a portion of biological tissue. For example, in the case of a retinal prosthesis, the retinal prosthesis is implanted into the retina of an eye and the shape of a cell layer of the retina is substantially concave. As such, the mould also has a portion that has a substantially concave shape.

In a next step 506, a flexible portion such as the

structured layer composed of silicone as described with reference to Figures 1 and 2, is formed in the mould. The step is conducted such that a contact surface of the flexible portion has a shape that approximates an inverse shape of the portion of biological tissue. For the above described example, the shape the contact surface would be substantially convex.

The provided device component is embedded into the

flexible portion after or during the flexible portion is formed. The step of forming the flexible portion may be performed so that the flexible portion has a non-uniform flexibility .

An alternative method for fabricating an intraocular device will be described in the following.

In a first step, a device component is provided.

Subsequently, a flexible portion is formed such that the formed flexible portion has a non-uniform hardness. The step of forming the flexible portion further comprises embedding the provided device component within the flexible portion.

The above described method steps may be performed such that the formed flexible portion is arranged to located the intraocular device at or within biological tissue and to distribute forces between the device component and the biological tissue along at least a portion of the

biological tissue.

The step of forming the flexible portion may comprise forming a layered structure that comprises layers of flexible material. The flexible material may have

properties such that hardness of the flexible material differs between at least two of the layers. For example and with reference to Figures 1 and 2, the step of forming the flexible portion may be, conducted such that in a first step a layer of relatively soft material is formed in the mould. In a next step, a layer of a material is formed which is harder than the first layer. In further steps, layers may be added with increased hardness such that the hardness increases from the contact surface towards .the opposite surface of the intraocular device.

In the following, method steps for fabricating the

stimulating electrode are , described . In a first step a silicon substrate is provided. The substrate is

subsequently immersed in a nano-diamond slurry in

ultrasonic bath to form a seeding layer. The substrate is held upright in the solution and in an ultrasonic bath to ensure even diamond dispersion. Subsequently, the

substrate is dried.

A first gas mixture of methane (CH₄, 2%) and hydrogen _. (H₂, 98%) is used to form the electrically insulating material. In this particular example, a polycrystalline diamond layer of approximately 10-100μπι is grown using a H2/CH4 (750 seem / 15 seem) gas mixture at a pressure of 80 Torr and a temperature of approximately 900 - 1100°C.

The seeded substrate is placed in a microwave plasma chamber. of a microwave plasma CVD system (2,45 GHz / 6kW ^' continuous wave, microwave power: 1-3 kW) and is then exposed to the hydrogen-methane plasma. A layer of approximately 50-100 μιτι of the polycrystalline diamond layer is required for a mechanically stable and relatively robust 10x10 mm diamond slap.

In a further step, portions of the polycrystalline diamond layer are removed using a laser radiation or etching such as reactive ion etching or wet etching. Resulting voids provide a basis for forming the electrically conducting elements. Additionally, also portions of the silicon wafer may be removed using the laser radiation or etching. In this particular example, the size of the portions that are removed from the silicon wafer determines the form and height of the electrically conducting elements.

Formation of the electrically conductive diamond · material includes an initial seeding step. Using a second gas mixture of Argon (Ar, 70-80%), methane (CH₄, 1-5 %) and Nitrogen (N₂, 5-20 %) , a layer of the electrically reconducting diamond material is then formed. In this particular example, a gas mixture Ar/N2/CH4

(79sccm/20sccm/lsccm) is used at a pressure of 80-120 Torr and a temperature of 900°C. In this particular example, a layer of approximately 10-100 m of nitrogen incorporated ultra nano-crystalline diamond is grown using the

abovementioned gas mixture.

In a further step, portions of the ultra nano-crystalline diamond layer are removed by etching or laser radiation such that a plurality of isolated electrically conducting elements is provided within the polycrystalline diamond layer. .The substrate is then removed by etching such that an array of implantable electrodes is provided.

The following will describe a method of fabricating a feedthrough in accordance with embodiments of the present invention, such as the feedthrough that is schematically illustrated in Figure 3. Initially a housing of the device component is provided. The housing has in this embodiment wall portions that are formed from a diamond material and the^' above-described electrode forms a lid portion of the housing. An aperture is formed through a wall portion of a housing of an intraocular device. The wall portion is masked by placing a substrate having the same aperture over the wall portion. The wall portion and the substrate are seeded by physically dipping both in a nano-diamond . solution comprising 4-6nm diamond nano-crystals suspended within methanol^' solution.

The seeded wall portion and substrate are placed within a CVD chamber. The chemical vapour deposition is operated- under a flow of methane, nitrogen and argon to deposit an electrically conductive diamond material. In this

embodiment, the electrically conductive diamond is

nitrogen-incorporated ultra-nanocrystalline diamond .

including 1-2% methane, 5-25% nitrogen and 74-94% argon. A sample stage on which the wall portion and the substrate are positions stage is heated to 800-900 °C during

chemical vapour deposition. _, After the CVD the substrate is removed from alignment with the wall portion. The aperture of .the wall portion is filled with electrically conductive diamond material and the electrically conductive diamond irremovably seals the aperture. The electrically conductive diamond seals the aperture such that the contact regions between the

substrate and the diamond are fluid and gas impermeable. Electrically conductive diamond layers may be formed in the described manner to contact the electrically

conductive material that fills the aperture. An

electrically insulating material is finally deposited to establish electrical insulation of the electrically conductive material.

For further details of the fabrication of the above- described electrode and electrical feedthrough reference is being made to the applicant's co-pending PCT

international application PCT/AU2012/000609, which is herewith incorporated by cross-reference.

Although the invention has been described with reference to particular examples,¹ it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

The Claims:

1. An intraocular device comprising:

a device component comprising a housing having an electrical feedthrough that is fluid impermeable, the device component further comprising an electrode that has a plurality of electrically conductive elements comprising a diamond material; and

a flexible portion arranged to locate the device component at or within biological tissue and to distribute forces between the device component and the biological tissue along at least a portion of the biological tissue.

2. The intraocular, device of claim 1 being a retinal prosthesis. v

3.. The intraocular device of claim 1 or 2 comprising first and second attachment elements that are selected such that magnetic forces attract the first and second elements to each other.

4. The intraocular device of any one of the preceding claims wherein the flexible portion at least partially surrounds the device component.

5. The intraocular device of claim 4 wherein the

flexible portion covers the device component in a manner such that only a portion of the electrode is exposed.

6. The intraocular device of any one of ^' the preceding claims wherein the flexible portion has a non-uniform flexibility .

7. The intraocular device of any one of the preceding claims wherein the flexible portion is a layered structure and comprises, layers of a flexible material.

8. The intraocular device of claim 7 wherein at least two of the layers have differing hardnesses.

9. The intraocular device of claim 7 or 8 werein the layered structure comprises layers that have a hardness ranging from 2 - 80, or 4 - 60, or 6 - 50, or 8 - 40 or 10 - 30 durometer.

10. ^' The intraocular device of any one of claims 7 to 9 wherein at least some of the layers of .the layered

structure are ordered such that the hardness of the layers is increasing in a direction through the layered structure and from a contact surface towards the device component.

11. The intraocular device of any one of the preceding claims wherein the flexible portion has a contact surface that has a shape that at least approximates an inverse of the shape of the at least a portion of the biological tissue.

12. The intraocular device of claim 11 wherein the contact surface has a convex shape.

13. The intraocular device of any one of the preceding claims' wherein the flexible portion comprises at least one extension from a body portion of the flexibl.e portion, the at least one extension being arranged to. receive a

fastener.

14. An intraocular device comprising:

component and the biological tissue, a shape and a

flexibility of the flexible portion result in a

distribution . of forces between the device component and the biological tissue along at least a portion of the biological tissue.

15. The intraocular device of claim 14 wherein the contact surface of the flexible portion has a shape that at least approximates an inverse of the shape of the at least a portion of the biological tissue.

16. The intraocular device of claim 15 wherein the contact surface has a convex shape.

17. The intraocular device of any one of claims 14 to 16 comprising first and second attachment elements that are selected such that magnetic forces attract the first and second elements to each other.

18. An intraocular device, such as a retinal prosthesis, the intraocular device comprising:

a flexible portion surrounding, at least partially the device component and having a non-uniform flexibility.

19. The intraocular device of claim 19 wherein the flexible portion is a layered structure comprising layers of a flexible material.

20. The intraocular device of claim 18 or 19 comprising first and second attachment elements that are selected such that magnetic forces attract the first and second elements to each other.

21. A method of fabricating an intraocular device

arranged for implanting at or within biological tissue, the method comprising the steps of:

providing a device component;

forming a flexible portion in the mould such that a contact surface of the flexible portion has a shape that at least approximates that of an inverse of the portion of the biological tissue, comprising embedding at least a portion of the ^' device component within the flexible portion .

22. The method of claim 21 wherein the step of forming is conducted such that the formed flexible portion has a nonuniform flexibility.

23. A method of fabricating an intraocular device

arranged for implanting at or within a biological tissue, the method comprising the steps of:.

providing a device component; and

forming a flexible portion such that the flexible portion has a non-uniform hardness, comprising embedding at least a portion of the device component within the flexible portion.

24. The method of claim 23 comprising a step of providing a mould having a shape that at least approximates that of a portion of the biological tissue.

25. The method of claim 23 or 24 wherein the step of forming the flexible portion comprises forming the

flexible portion in the mould such that a contact surface of the flexible material has a shape that at least

approximates that of an inverse of the at least a portion of the biological tissue.

26. The method of any one of claims 21 to 25 wherein the step of forming the flexible portion comprises forming a layered structure that comprises layers of a flexible material .

27. The method of claim 26 wherein the step of forming the flexible portion is conducted such that at least some of the layers of the layered structure are ordered such that the hardness of the . layers is increasing in a

direction through the layered structure and from a, contact surface for contacting biological tissue towards the device component.