Intraocular physiological sensor

Abstract

SOLUTION: Intraocular physiological sensor implants include a physiological sensor, and a housing comprising a faceplate. The physiological sensor is integrated with the faceplate. The physiological sensor typically comprises an intraocular pressure sensor, such as a capacitive pressure sensor that may further include a flexible diaphragm electrode separated from a counter electrode. The intraocular pressure sensor detects intraocular pressure in order to identify patient conditions such as glaucoma.EFFECT: Appropriate management can be improved using enhanced monitoring.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] <Priority Claim>

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 824,707, entitled "Intraocular Physiological Sensor," filed March 27, 2019, the entire contents of which are hereby incorporated by reference. [Background technology]

[0003] The field of the invention relates generally to implantable physiological sensors. More particularly, embodiments of the invention relate generally to implantable intraocular sensors for measuring physiological characteristics such as intraocular pressure and / or glucose concentration.

[0004] Several diseases, including glaucoma, diabetes, and others, can be treated more effectively if they are diagnosed early and / or monitored effectively. For example, glaucoma is a leading cause of blindness. This disease causes elevated intraocular pressure, which damages the optic nerve inside the eye and can lead to complete loss of vision if left untreated. However, early detection and proper management of elevated intraocular pressure can reduce the risk of blindness. Similarly, diabetes is a serious condition that can be treated more effectively with early detection and proper management of elevated blood glucose levels. For both of these conditions, increased monitoring can be used to improve proper management.

[0005] Accordingly, diagnostic physiological sensors have been developed for implantation within the human body to monitor physiological characteristics such as intraocular pressure and glucose concentration. Such implantable sensors may be used to effectively diagnose and treat certain physiological conditions. Summary of the Invention [Means for solving the problem]

[0006] The present disclosure provides a new physiological sensor for implantation into the intraocular environment and measurement of relevant intraocular characteristics. The new sensor and method of detection disclosed herein advantageously provide continuous monitoring of physiological phenomena, such as intraocular pressure and glucose concentration. The sensor disclosed herein can wirelessly transmit measured data to an external device for further processing and analysis. Similarly, the sensor disclosed herein can be wirelessly charged via an external device for improved ease of use and overall longevity. The sensor can further provide flow through an internal flow path, thus lowering intraocular pressure in the anterior chamber.

[0007] In a first aspect of the present disclosure, which may be combined with any other aspect set forth herein unless otherwise specified, with reference to the disclosure herein and without limiting the scope of the present invention in any way, an intraocular implant comprises a physiological sensor, a housing, and at least one protruding anchor. The housing comprises a faceplate and a cover. The physiological sensor is integral with the faceplate. The at least one protruding anchor is configured to enter the trabecular meshwork. The at least one protruding anchor comprises an internal flow channel.

[0008] In a second aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the physiological sensor includes an intraocular pressure sensor.

[0009] In a third aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the intraocular pressure sensor includes a capacitive pressure sensor.

[0010] In a fourth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, a capacitive pressure sensor includes a flexible diaphragm electrode spaced apart from a counter electrode.

[0011] In a fifth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the faceplate includes a first substrate coupled to a second substrate, the flexible diaphragm electrode includes at least a portion of the first substrate, and the counter electrode includes at least a portion of the second substrate.

[0012] In a sixth aspect of the present disclosure, which may be combined with any other aspect recited in this specification unless otherwise specified, the implant further comprises a first conductive via connected to the flexible diaphragm electrode and extending through the faceplate, a second conductive via connected to the counter electrode, and an electrical interconnect circuit connected to the first conductive via and the second conductive via.

[0013] In a seventh aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the implant further comprises a coil embedded in an inner surface of the faceplate.

[0014] In an eighth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the coil includes conductors provided in channels formed in an inner surface of the faceplate, the channels being laid out to form a plurality of loops.

[0015] In a ninth aspect of the present disclosure, which may be combined with any other aspect recited in this specification unless otherwise specified, the implant further comprises a stress relief cutout formed in the faceplate around the physiological sensor.

[0016] In a tenth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the stress relief cutout includes a channel extending partially through the faceplate.

[0017] In an eleventh aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the faceplate and the physiological sensor are both formed from silicon.

[0018] In a twelfth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the implant further comprises a humidity sensor provided inside the housing.

[0019] In a thirteenth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the humidity sensor includes a capacitor having a plurality of electrodes and a moisture-sensitive dielectric.

[0020] In a fourteenth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the moisture sensitive dielectric comprises a getter material.

[0021] In a fifteenth aspect of the present disclosure, which may be combined with any other aspect recited in this specification unless otherwise specified, the implant further comprises a capacitance-to-digital converter that reads the capacitance of the humidity sensor.

[0022] In a sixteenth aspect of the present disclosure, which may be combined with any other aspect set forth in this specification unless otherwise specified, the physiological sensor includes a capacitance type sensor, and a capacitance-to-digital converter is connected to the physiological sensor to read the capacitance of the physiological sensor.

[0023] In a seventeenth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the physiological sensor includes a glucose sensor.

[0024] In an eighteenth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the housing includes a convex curved surface having a first radius of curvature in a first direction and a second radius of curvature in a second direction perpendicular to the first direction.

[0025] In a nineteenth aspect of the present disclosure, which may be combined with any other aspect set forth in the present specification unless otherwise specified, the first radius of curvature corresponds to the radius of curvature of the iridocorneal angle of a normal human eye in a plane perpendicular to the optical axis of the eye, and the second radius of curvature corresponds to the radius of curvature of the iridocorneal angle in a plane including the optical axis of the eye.

[0026] In a twentieth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the exterior of the housing is coated in a thin film atomic layer deposition (ALD) coating.

[0027] In a twenty-first embodiment of the present disclosure, which may be combined with any other embodiment recited herein unless otherwise specified, a thin film ALD coating covers a surface of a physiological sensor.

[0028] In a twenty-second embodiment of the present disclosure, which may be combined with any other embodiment recited herein unless otherwise specified, the thin film ALD coating further covers a hermetic seal.

[0029] In a twenty-third embodiment of the present disclosure, which may be combined with any other embodiment recited herein unless otherwise specified, the thin film ALD coating comprises a multi-layer stack of at least two different materials.

[0030] In a twenty-fourth aspect of the present disclosure, which may be combined with any other aspect recited herein unless otherwise specified, the physiological sensor is disposed within a recess formed in an outer surface of the faceplate.

[0031] In a twenty-fifth embodiment of the present disclosure, which may be combined with any other embodiment recited herein unless otherwise specified, the housing comprises one or more protrusions or grooves that promote the flow of aqueous humor around the housing.

[0032] In a twenty-sixth embodiment of the present disclosure, which may be combined with any other embodiment recited herein unless otherwise specified, the housing includes at least one retention tab that holds at least one protruding anchor.

[0033] In a twenty-seventh embodiment of the present disclosure, which may be combined with any other embodiment recited in this specification unless otherwise specified, the retention tab includes a through hole, and at least one protruding anchor has an entry head and an elongate body at a first end, extending through the through hole of the retention tab and having an elongate body with a diameter smaller than the diameter of the through hole and an entry head with a diameter larger than the diameter of the through hole, and a second end of the protruding anchor is deformable.

[0034] In a twenty-eighth aspect of the present disclosure, which may be combined with any other aspect recited in the present specification unless otherwise specified, the implant further comprises a controller configured to obtain measurements of physiological characteristics using the physiological sensor.

[0035] In a twenty-ninth aspect of the present disclosure, which may be combined with any other aspect recited in the present specification unless otherwise specified, the implant further comprises a controllable opening and closing device connected between the battery and one or more other electrical components, the controllable opening and closing device being configured to open upon a malfunction.

[0036] In a thirtieth aspect of the present disclosure, which may be combined with any other aspect recited in this specification unless otherwise specified, the implant further comprises a transceiver configured to wirelessly transmit measurement data to an external device.

[0037] In a thirty-first aspect of the present disclosure, which may be combined with any other aspect recited in the present specification unless otherwise specified, the implant further comprises a hermetic seal between the faceplate and the cover, the hermetic seal comprising eutectic solder.

[0038] In a thirty-second aspect of the present disclosure, which may be combined with any other aspect set forth herein unless otherwise specified, a method of monitoring intraocular pressure includes obtaining an intraocular pressure measurement using an intraocular implant, the intraocular implant comprising a physiological sensor, whereby the intraocular pressure is measured using the physiological sensor. The method includes storing the intraocular pressure measurement in a memory of the intraocular implant. The method includes transmitting the intraocular pressure measurement to an external device by a coil embedded in an inner surface of the intraocular implant. The external device wirelessly receives the intraocular pressure measurement by RF transmission from the intraocular implant.

[0039] In a thirty-third aspect of the present disclosure, which may be combined with any other aspect recited in the present specification unless otherwise specified, the method further includes a step of supplying power to a capacitor disposed in the intraocular implant, the step of supplying power including a step of wirelessly transmitting power from an external charging device to a coil embedded in an inner surface of the intraocular implant.

[0040] Additional features and advantages of the disclosed devices, systems and methods are described in and will be apparent from the following detailed description and figures. The features and advantages described herein are not all-inclusive, and many additional features and advantages will be apparent to those skilled in the art, particularly in light of these figures and descriptions. Also, any particular embodiment does not necessarily have all of the advantages listed herein. Furthermore, it should be noted that the language used in this specification has been chosen for ease of reading and explanation, and is not intended to limit the scope of the subject matter of the present invention.

[0041] Various embodiments and features of the devices, systems and methods disclosed herein are described with reference to the following drawings, in which the drawings, associated descriptions and specific implementations are provided to illustrate embodiments of the invention and are not intended to limit the scope of the disclosure. [Brief description of the drawings]

[0042] [Figure 1A] 1 illustrates a schematic diagram of an intraocular physiological sensor implant placed in a human eye. [Figure 1B] 1 illustrates a schematic diagram of an intraocular physiological sensor implant secured by an anchor that is embedded through fibrous network tissue into scleral tissue at the iridocorneal angle. [Figure 2A] 1 illustrates a block diagram of an example embodiment of an intraocular physiological sensor implant. [Figure 2B] 1 illustrates a block diagram of another example embodiment of an intraocular physiological sensor implant. [Figure 3A] 1 illustrates a bottom perspective view of an example embodiment of a housing for an intraocular physiological sensor implant. [Figure 3B] 3B illustrates a top perspective view of an example embodiment of a housing for an intraocular physiological sensor implant shown in FIG. 3A. [Figure 4A] 1 illustrates a top view of another example embodiment of a housing for an intraocular physiological sensor implant. [Figure 4B] 1 illustrates a top perspective view of another example embodiment of a housing for an intraocular physiological sensor implant. [Figure 4C] 1 illustrates a bottom perspective view of another example embodiment of a housing for an intraocular physiological sensor implant. [Figure 4D] 14A-14C illustrate side and top views of another example embodiment of a housing for an intraocular physiological sensor implant. [Figure 4E] 1 illustrates a top perspective view of another example embodiment of a housing and associated anchor for an intraocular physiological sensor implant. [Figure 4F] 1 illustrates a top perspective view of another example embodiment of a housing and associated anchor for an intraocular physiological sensor implant. [Figure 4G] 1 illustrates a top perspective view of another example embodiment of a housing and associated anchor for an intraocular physiological sensor implant. [Figure 4H] 1 illustrates a top perspective view of an example embodiment of an anchor insert. [Figure 4I] 1 illustrates a top perspective view of an example embodiment of an anchor insertion. [Figure 4J] 1 illustrates a top perspective view of an example embodiment of an anchor insertion. [Figure 4K] 1 illustrates a top perspective view of an example embodiment of an anchor insertion. [Figure 4L] 1 illustrates a cross-sectional side view of an example embodiment of an anchor insert. [Figure 4M] 1 illustrates a cross-sectional side view of an example embodiment of an anchor insert. [Figure 4N] 1 illustrates a side and top perspective view of an example embodiment of an anchor with a fluid flow path. [Figure 4O] 1 illustrates a side and top perspective view of an example embodiment of an anchor with a fluid flow path. [Figure 4P] 1 illustrates a side and top perspective view of an example embodiment of an anchor with a fluid flow path. [Figure 4Q] 1 illustrates a side and top perspective view of an example embodiment of an anchor with a fluid flow path. [Figure 4R] 1 illustrates a side and top perspective view of an example embodiment of an anchor with a fluid flow path. [Figure 5A] 1 illustrates a perspective view of an example embodiment of an anchor with clocking features and fluid flow channels. [Figure 5B] 1 illustrates a front view of an example embodiment of an anchor with clocking features and fluid flow channels. [Figure 5C] 1 illustrates a cross-sectional side view of an example embodiment of an anchor with clocking features and fluid flow channels. [Figure 5D] 1 illustrates a perspective view of an intraocular physiological sensor implant having an anchor with clocking features and fluid flow paths. [Figure 5E] 1 illustrates a perspective view of an intraocular physiological sensor implant having an anchor with clocking features and fluid flow paths. [Figure 5F] 1 illustrates a front view of an intraocular physiological sensor implant having an anchor with clocking features and a fluid flow path. [Figure 5G]1 illustrates a perspective view of an intraocular physiological sensor implant having an anchor with clocking features and fluid flow paths. [Figure 5H] 1 illustrates an exploded view of an example embodiment of an intraocular physiological sensor implant. [Figure 5I] 5C illustrates a layer-by-layer perspective view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 5J] 5C illustrates a layer-by-layer perspective view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 5K] 5C illustrates a layer-by-layer perspective view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 5L] 5C illustrates a layer-by-layer perspective view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 6A] 5C illustrates a layer-by-layer top view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 6B] 5C illustrates a layer-by-layer top view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 6C] 5C illustrates a layer-by-layer top view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 6D] 5C illustrates a layer-by-layer top view of an example embodiment of an intraocular physiological sensor implant shown in FIG. 5H. [Figure 7A] 1 illustrates a cross-sectional view of a portion of an example faceplate for a housing of an intraocular physiological sensor implant. [Figure 7B] 1 illustrates a perspective view of an embodiment of an intraocular physiological sensor implant in which the physiological sensor is recessed into the faceplate. [Figure 7C] 7B illustrates a perspective view of a cross section of a portion of an example faceplate for a housing of the intraocular physiological sensor implant shown in FIG. 7A. [Figure 7D] 1 illustrates an example embodiment of how a coil inductor is connected to the electrical interconnect circuit of an intraocular physiological sensor implant. [Figure 7E]1 illustrates an example embodiment of how a coil inductor is connected to the electrical interconnect circuit of an intraocular physiological sensor implant. [Figure 8A] 1 illustrates a top perspective view of an example embodiment of an intraocular physiological sensor implant faceplate with a stress relief cutout between the embedded coil loop and the physiological sensor. [Figure 8B] 8B illustrates a perspective view of a cross section of the faceplate shown in FIG. 8A. [Figure 9A] 1 illustrates an embodiment of a faceplate and circuit board for an intraocular physiological sensor implant. [Figure 9B] 1A-1D illustrate top and perspective views of an example embodiment of a circuit board in an unfolded and folded configuration; [Figure 9C] 1A-1D illustrate top and perspective views of an example embodiment of a circuit board in an unfolded and folded configuration; [Figure 9D] 1 illustrates an example embodiment of how coils can be formed in multiple sections of a circuit board. [Figure 9E] 1 illustrates a top perspective view of stacked circuit boards. [Figure 9F] 1 illustrates a top perspective view of stacked circuit boards. [Figure 9G] 1 illustrates a top perspective view of stacked circuit boards. [Figure 10A] 1 illustrates a top view of an example embodiment of an airtight seal between components that make up the housing of an intraocular physiological sensor implant. [Figure 10B] 1 illustrates a cross-sectional view of an example embodiment of an airtight seal between a faceplate and a top cover of a housing for an intraocular physiological sensor implant. [Figure 10C] A method of hermetic sealing using a gold-tin sealing ring is illustrated. [Figure 10D] A method of hermetic sealing using a gold-tin sealing ring is illustrated. [Figure 11] 1 illustrates an example embodiment of a faceplate and top cover of a housing for an intraocular physiological sensor implant. [Figure 12A] 1 illustrates a graph of atmospheric pressure measured by a barometer worn by a user. [Figure 12B] An enlarged portion of the signal shown in FIG. 12A from time 60 to time 80 is illustrated. [Figure 12C] 1 illustrates a simulation of the effect of a 0.1% timer inaccuracy that causes a time lag between the absolute IOP measurement and the barometric pressure measurement used to calculate the gauge IOP value. [Figure 12D] 1 illustrates a simulation of the effect of a 1% timer inaccuracy that causes a time lag between the absolute IOP measurement and the barometric pressure measurement used to calculate the gauge IOP value. [Figure 13A] 1 illustrates an example method for calculating a gauge IOP value using one or more barometric pressure measurements from an external device and one or more absolute IOP measurements from a sensor implant in a patient's eye. [Figure 13B] An example method for correlating barometric pressure measurements from an external device with absolute IOP measurements from a sensor implant for purposes of determining gauge IOP values ​​is illustrated. [Figure 14A] 1 illustrates a graph showing power usage of an example IOP detection implant when the implant is battery powered and, alternatively, when the implant is powered by a supercapacitor. [Figure 14B] 1 illustrates a graph showing power usage of an example implant for detecting IOP powered by a combination of a battery and a supercapacitor, where the capacity of the supercapacitor is less than the power usage of the implant during charging interaction. [Figure 14C] 1 illustrates a graph showing power usage of an example implant for detecting IOP powered by a combination of a battery and a supercapacitor, where the capacity of the supercapacitor is greater than the power usage of the implant during charging interaction. [Figure 15] 1 illustrates a flow chart illustrating a method for providing operating power to an implant for IOP detection. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] In order to detect or monitor the progression of glaucoma, it is necessary to effectively monitor the intraocular pressure in a patient's eye. Intraocular pressure can be measured non-invasively, for example, using a tonometer. Tonometers have the advantage of being non-invasive, but the disadvantage of being dedicated devices that are generally expensive, not portable, and require skilled operation. Thus, in practice, it is difficult to use a tonometer to effectively monitor intraocular pressure in a patient's eye with a time resolution greater than a measurement every few days or every few weeks. However, because intraocular pressure can change significantly over a relatively short period of time, such relatively spaced intraocular pressure measurements may not provide a sufficient or accurate picture of a patient's risk for glaucoma or progression of glaucoma. Therefore, it would be advantageous to be able to measure intraocular pressure more frequently, or even continuously.

[0044] FIG. 1A is a schematic diagram of an intraocular physiological sensor implant 200 disposed within a human eye 100. For reference, various anatomical features of the eye 100 are numbered in FIG. 1A. For example, FIG. 1A shows the vitreous humor 102, the iris 104, the lens 106, the pupil 108, the anterior chamber 110 (including the aqueous humor that fills the anterior chamber), the cornea 112, the retina 114, and the optic nerve 116. FIG. 1A also illustrates an intraocular physiological sensor implant 200 (not necessarily drawn to scale or shape) disposed within the anterior chamber of the eye. The sensor implant 200 can continuously measure one or more physiological characteristics, such as intraocular pressure within the eye.

[0045] The sensor implant 200 can be positioned in a number of different locations within the eye 100. For example, the sensor implant 200 can be fixedly attached or anchored to any suitable anatomical feature of the eye, including, but not limited to, the sclera or iris, depending on the particular application. The sensor implant 200 can also be fixedly attached or placed relative to or within the physiological aqueous humor outflow pathway. The physiological aqueous humor outflow pathway includes the "normal" pathway, which includes the trabecular meshwork and Schlemm's canal, and the "uveoscleral" pathway, which includes the ciliary body, sclera, and ciliary body / suprachoroidal space. FIG. 1B illustrates the placement of the sensor implant 200 at the iridocorneal angle 119, threaded through the fibrous meshwork tissue 117 and secured by an anchor 201 embedded in the scleral tissue 118. Alternatively, the sensor implant 200 could be attached to some other anatomical feature, such as the sclera, the scleral spine, the vitreous cavity, or even to another intraocular implant, for example an intraocular lens.

[0046] While some embodiments of the sensor implant 200 measure intraocular pressure, some embodiments may additionally or alternatively measure glucose concentration in aqueous humor. In particular, there is a need to measure glucose concentration in the human body as a means of treating or preventing complications from diabetes. Glucose is typically measured from blood or urine samples. Several implantable glucose sensors have been developed that measure glucose from interstitial fluid. However, the body may have a negative immune response to such implants that may degrade the performance of the sensor over time. The eye 100, and in particular the anterior chamber 110 of the eye, is an immunologically privileged site in the body. Thus, an intraocular sensor implant for measuring glucose in the eye may have advantages over other implantable sensors that are designed to measure glucose in non-immunologically privileged parts of the body. Furthermore, although the glucose concentration in the aqueous humor may not be identical to the glucose concentration in the blood, the two may be correlated such that measuring the glucose concentration in the aqueous humor may be predictive of the glucose concentration in the blood.

[0047] In an embodiment, sensor 200 applies a current and measures the initial rate of decomposition of reactive buildup on the glucose sensor. From this measured initial rate of decomposition, sensor 200 implements an algorithm that approximates the glucose level at the time all of the buildup has decomposed. Thus, sensor 200 advantageously avoids the unnecessary power consumption associated with burning off the entire reactive buildup.

[0048] Measuring both intraocular pressure and aqueous humor glucose concentration can be advantageous because glucose concentration measurements can be used to diagnose and / or treat diabetes. However, diabetic patients are also at increased risk of developing glaucoma. Thus, there may be a significant overlap in the patient populations in which measurements of intraocular pressure and glucose concentration would be valuable.

[0049] Furthermore, it should be understood that in various embodiments, the sensors disclosed herein, such as the sensor implant 200, could be implanted and positioned at other locations in the human body other than the eye. For example, the sensor implant 200 could measure pressure in other organs, such as the brain or heart, or other locations, such as the chest cavity, limbs, etc. Similarly, the sensor implant 200 could measure other values, such as glucose concentration, at these other locations. Implantation at other locations can be accomplished with limited, if any, design modifications to the sensor implant 200 disclosed herein. Thus, in certain embodiments, the sensor implant 200 is location agnostic.

[0050] 2A is a block diagram of an example embodiment of an intraocular physiological sensor implant 200. The illustrated embodiment of the sensor implant 200 includes a physiological sensor 210, a controller 220, a battery 230, a measurement memory 240, a transceiver / receiver 250, an inductive coil 260, and an electrical interconnect circuit 270 for communicating power and / or data between various parts of the implant 200. One or more of the illustrated components may be embodied as one or more integrated circuits. Some embodiments of the sensor implant 200 may omit one or more of the components illustrated in FIG. 2A or include additional or alternative components than those specifically illustrated. Each of the components of the sensor implant 200 may be housed in whole or in part in a biocompatible housing 280, which will be described in more detail herein.

[0051] The physiological sensor 210 is a component that performs measurements of one or more physiological characteristics of interest. The physiological sensor 210 can output a signal, e.g., an electrical signal, that quantitatively represents the physiological characteristic being measured. In some embodiments, the physiological sensor 210 can be designed to measure intraocular pressure, intraocular glucose concentration, and / or any other physiological characteristic of interest that can be detected within the eye. The sensor implant 200 may also include multiple instances of the physiological sensor 210. Each instance of the sensor 210 may be used to measure a different physiological characteristic. For example, the sensor implant 200 may include two instances of the physiological sensor 210 to measure intraocular pressure and glucose concentration.

[0052] Measurements obtained using the physiological sensor 210 may be stored in a measurement memory 240, which may be, for example, a solid-state electronic memory device. The measurement memory 240 may be used to internally record measurements from the physiological sensor 210 until they can be retrieved via the transceiver / receiver 250 by an external device communicatively coupled to the sensor implant 200.

[0053] A transceiver / receiver 250, e.g., a two-way radio, can be communicatively coupled to the coil 260 and can be used to wirelessly receive data, e.g., instructions, from an external device and / or to wirelessly transmit data, including physiological measurements from the sensor implant 200, to an external device. The transceiver / receiver 250 can be controlled, e.g., by the controller 220, to transmit measurements on demand, according to a set schedule, and / or at regular or irregular intervals, e.g., daily. In some embodiments, the external device can be a data logger worn by the patient to store the measurements until they can be downloaded by the clinician. In other embodiments, the external device can be a handheld reader device used by the clinician to periodically download the measurement data stored internally by the measurement memory 240. The reader device can then transmit the downloaded measurements via the Internet or some other communication network to a computer for processing and / or analysis by the clinician. The reader device can also provide the downloaded measurements to the patient via a user interface.

[0054] The controller 220 may be used, for example, to perform control operations for other components of the sensor implant 200. In some embodiments, the controller 220 may provide instructions to cause measurements to be taken using the physiological sensor 210. In some embodiments, the controller 220 causes measurements to be taken at regular intervals. For example, measurements may be taken on demand, based on input, for example, from an external device, according to a set schedule, and / or at regular or irregular intervals, for example, at least every hour, at least every 15 minutes, at least every minute, etc., depending on the particular application. In some embodiments, the controller 220 causes measurements to be taken at time intervals that are shorter than typical intervals at which a noticeable change in the physiological characteristic may occur. In this way, trend data regarding the physiological characteristic of interest may be collected to provide a more useful or complete picture of how the physiological characteristic changes as a function of time. In some embodiments, the controller 220 causes measurements to be taken even faster, for example, at a rate of 20 Hz or faster, so that high frequency IOP fluctuations, for example those due to cardiac pulsation, can be identified and recorded. Alternatively, in some embodiments, measurements could be taken less frequently throughout the day to conserve energy, including battery life.

[0055] The controller 220 may also control the writing and reading of measurement data to the measurement memory 240. The controller 220 may also control the transmission and reception of data using the transceiver / receiver 250. Additionally, the controller 220 may control the power settings and / or power electronics of the battery 230.

[0056] The controller 220 may also perform other functions. For example, in some embodiments, the controller 220 may perform data processing operations on measurements collected using the physiological sensor 210. However, in other embodiments, any necessary data processing operations may be performed after the measurements are downloaded by an external device to avoid the power requirements of on-board processing. Additionally, the controller 220 may monitor the collected measurements and output an alarm signal, for example, to an external device via the transceiver / receiver 250, when a monitored physiological characteristic reaches a certain threshold or is otherwise deemed necessary for immediate notification. For example, an alarm signal may be initiated if the sensor implant 200 detects a potentially dangerous hypoglycemic level. The controller 220 may also perform measurement data compression to allow more measurements to be stored in the measurement memory 240. The controller 220 may also perform encryption on data or information transmitted or received by the transceiver / receiver 250. The controller 220 may also issue commands to other components of the sensor implant 200, such as the transceiver / receiver 250, the measurement memory 240, the physiological sensors 210, etc., to shut down or enter a power saving state when not in use.

[0057] In the illustrated embodiment, the sensor implant 200 uses the battery 230 to meet, in whole or in part, the power needs of any or all of the other components of the sensor implant 200. The battery 230 may be repeatedly rechargeable. For example, the sensor implant 200 may use the coil 260 to receive power from an external device by inductive or radio frequency (RF) coupling. This power may be used to recharge the battery 230. In some embodiments, the battery 230 may be a thin-film lithium-ion battery or a lithium-metal battery. The sensor implant 200 may also include power electronics, such as a voltage regulator, a voltage converter, and / or any other electrical components, desired to condition the power output by the battery 230 so that it can be fully used by other electrical components within the sensor implant 200.

[0058] In some embodiments, the battery 230 can be connected to other components of the sensor implant 200 by a switch or other opening and closing component that can be controlled by the controller 220. When the switch is closed, the sensor implant 200 consumes power from the battery 230. When the switch is open, the sensor implant 200 is in an on-demand mode where it can consume power wirelessly transmitted from an external device. The switch can be advantageous in ensuring that battery power is consumed only when instructed by the controller 220. The switch can be designed to be a dead open when the battery 230 is discharged and power to the controller 220 is lost. This ensures that the sensor implant 200 can operate in an on-demand mode if the battery 230 is discharged or inoperable.

[0059] 2B is a block diagram of another example embodiment of an intraocular physiological sensor implant 200. In this embodiment, the sensor implant 200 is an intraocular pressure sensor. The illustrated embodiment of the sensor implant 200 includes a pressure sensor 210, a controller 220, a battery 230, a measurement memory 240, a transceiver / receiver 250, a coil 260, and interconnects 270 for communicating power and / or data between the various components of the implant 200. Each of the components of the sensor implant 200 may be housed in whole or in part within a biocompatible housing 280, as illustrated in FIGS. 3A and 3B.

[0060] Various of the illustrated components may be embodied together on a chip as an application specific integrated circuit (ASIC) 290 (illustrated as a dashed box in FIG. 2B), although some components may also be provided as separate components with electrical connections to the integrated circuit 290, for example.

[0061] There are several different types of intraocular pressure measuring devices for measuring intraocular pressure, any of which may be used as the pressure sensor 210. In some embodiments, the pressure sensor 210 comprises a capacitor whose capacitance changes in response to the pressure of the medium in which the sensor implant 200 is placed. The capacitor may comprise a microelectromechanical system (MEMS). For example, the pressure sensor 210 may comprise a fixed capacitor plate electrode in close proximity to a flexible diaphragm or membrane electrode. The distance between the flexible diaphragm electrode and the fixed plate electrode changes in response to the pressure exerted by the aqueous humor when the sensor implant 200 is implanted in the eye 100. This is detected as a change in the capacitance of the capacitor. In other embodiments, the pressure sensor 210 additionally or alternatively uses other means for measuring pressure, such as a resistive strain gauge, a piezoresistive strain gauge, a piezoelectric strain gauge, an optical measurement, or any other related means for measuring pressure.

[0062] In some embodiments, the pressure sensor 210, when combined with the rest of the sensor implant 200 system, can measure intraocular pressure within the eye 100 from about 0 mmHg to about 50 mmHg gauge pressure with a resolution of about ±0.5 mmHg. In some embodiments, the cavity below the flexible diaphragm is sealed under vacuum and the pressure sensor 210 responds over a range of approximately 500-1000 mmHg absolute pressure with essentially infinite resolution since the output is a variable analog capacitance signal. Atmospheric pressure can be measured independently outside the body and subtracted from the absolute pressure measured by the pressure sensor 210 to obtain the intraocular pressure. In some embodiments, the capacitance varies approximately linearly with intraocular pressure. In some embodiments, the capacitance increases approximately linearly from approximately 1 picofarad (pF) to approximately 4 pF over a range of 500-900 mmHg absolute pressure. In other embodiments, the absolute pressure range is smaller or larger, or the sensitivity of the sensor is higher or lower. In some embodiments, the capacitance varies non-linearly with intraocular pressure.

[0063] The pressure sensor 210 may be electrically connected to a capacitance-to-digital converter 212 that outputs a value indicative of the capacitance of the pressure sensor 210, and therefore the detected pressure. This value may be provided to a controller 220. In some embodiments, the intraocular pressure sensor 210 also includes one or more reference capacitors 214.

[0064] That is, the pressure sensor 210 may include one or more reference capacitors 214, such as a recessed cavity reference MEMS capacitor disposed adjacent to the pressure sensor 210. The reference capacitor 214 may also be connected to the capacitance-to-digital converter 212 and may be used to provide a reference value for calibration and / or temperature compensation. The structure of the reference capacitor 214 is similar to that described above with respect to the pressure sensor 210, except that there is no sensing port. Thus, the faceplate 282 above the reference capacitor 214 prevents the reference capacitor 214 from detectably responding to pressure changes in the anterior chamber of the eye. In this embodiment, a through-silicon via is used to connect to the reference capacitor 214. The capacitive signal generated by the reference capacitor 214 may be used to filter out effects not related to pressure changes, such as intrinsic stress, mechanical stress, temperature changes, etc., thereby improving the accuracy of the system overall. The signal from reference capacitor 214 can be used directly, for example by direct analog subtraction of its capacitance from that of pressure sensor 210 within the operation of an ASIC or digital subtraction of the same, or indirectly by reading its value substantially simultaneously as reading the capacitance of reference capacitor 214 and pressure sensor 210 and using both measurements during downstream data processing / calibration. In this preferred embodiment, reference capacitor 214 has the same dimensions as pressure sensor 210, but may be a different size and shape and still provide similar utility.

[0065] In an embodiment, a temperature sensor is incorporated into the interconnect circuit 270 and can be used for temperature compensation and / or calibration purposes. Another advantage of integrating a temperature sensor with the interconnect circuit 270 in an embodiment is that it compensates for thermal drift as the interconnect circuit, and various components thereon, are subjected to heating and cooling that can result in unpredictable thermal expansion that affects the integrity and reliability of the sensor measurements.

[0066] Pressure measurements from the pressure sensor 210 can be stored in a measurement memory 240. In some embodiments, the measurement memory 240 is a solid-state memory provided as part of the integrated circuit 290. For example, the measurement memory 240 can be an 8 kB static random access memory (SRAM), although other types of memory and / or capacity can be used. In some embodiments, the controller 220 performs data compression on the pressure measurements before storing them in the measurement memory 240. By performing data compression, the measurement memory 240 can hold more measurements. This can allow for more frequent measurements and / or less frequent data download events. In some embodiments, it can be advantageous to use a relatively simple compression technique to conserve computing resources. One example data compression algorithm would be to store the difference between successive measurements rather than the measurements themselves. This technique would allow for fewer bits per measurement used by the measurement memory 240.

[0067] The controller 220 may perform any of the functions described elsewhere herein. For example, in some embodiments, the controller 220 may be programmed to take measurements using the pressure sensor 210 at predefined times, on demand, and / or at regular intervals, for example as determined by the MSTR clock 221. However, each recorded / reported measurement may be calculated from multiple measurements taken using the pressure sensor 210. For example, the controller 220 may be programmed to take multiple measurements, for example three measurements, at relatively short intervals, for example 30 seconds, or even shorter intervals, for example 0.5 seconds. These may then be averaged and recorded / reported as one measurement in the measurement memory 240. This process may then be repeated at longer intervals, for example every hour.

[0068] The sensor implant 200 illustrated in FIG. 2B includes a battery 230 that provides power to components such as the controller 220, the pressure sensor 210, and the transceiver / receiver 250. The battery may have a power rating of approximately 5 μAh or more. Such a power rating is estimated to provide sufficient power for at least approximately seven days between recharges. In some embodiments, the dormant power consumption of the sensor implant 200 is on the order of picowatts or nanowatts, while the active power consumption is on the order of nanowatts or microwatts. However, the size and power rating of the battery 230 could vary from the figures listed above, as could the power consumption of the sensor implant 200.

[0069] In some embodiments, the battery 230 is repeatedly rechargeable by an external device, as discussed elsewhere herein. For example, the battery 230 can be recharged wirelessly by inductive coupling or RF energy from an external device. In other embodiments, the battery 230 can be recharged by solar power or by an infrared laser (in which case the sensor implant 200 can include a suitable photovoltaic cell that converts sunlight or infrared laser light into electrical power), or by a fuel cell powered by glucose present in the aqueous humor.

[0070] The transceiver / receiver 250 and the coil 260 can be used to wirelessly transmit the pressure measurements stored in the measurement memory 240 to an external reader device. The external reader device can be integrated into glasses worn by the patient to download the pressure measurements from the sensor implant 200. The coil 260 can also be used for a dual purpose, for example to wirelessly receive power by inductive coupling to charge the battery 230 while the stored measurements are being downloaded. A wireless charging device can be integrated into the same glasses that includes the external reader device to download data from the sensor implant 200. The coil 260 can transmit measurement data and receive power to repeatedly charge the battery 230, either simultaneously or one at a time (in either order). In some embodiments, the coil 260 includes multiple conductive loops oriented such that their axes are generally aligned with the optical axis of the eye. This orientation allows a relatively large amount of electromagnetic flux to pass through the conductive loops after being transmitted from an external device placed in front of the eye, for example integrated into the frame of the glasses.

[0071] FIG. 3A is a bottom perspective view of an example embodiment of a housing 280 for an intraocular physiological sensor implant 200. In the illustrated embodiment, the housing 280 comprises two portions that combine to form the housing. For example, the housing 280 may comprise a bottom faceplate 282 and a top cover 284. In some embodiments, the faceplate 282 is generally flat, while the top cover 284 is dome-shaped. The faceplate 282 and the cover 284 may both be made of an impermeable, biocompatible material, but are not necessarily made of the same material. The material selected for the housing 280 may be at least partially transmissive, preferably substantially transparent, to radio frequency (RF) electromagnetic radiation, such as ceramic, glass, or silica. An airtight seal may be provided between the faceplate 282 and the cover 284 to prevent aqueous humor or water from seeping into the housing 280 and / or to prevent atoms or molecules of metals or other materials inside the housing 280 from being introduced into the patient's eye.

[0072] In the illustrated embodiment, the physiological sensor 210 is integrated into the faceplate 282. In this example, the physiological sensor 210 is a capacitive intraocular pressure sensor that includes the flexible diaphragm 216 already discussed above. In some embodiments, the flexible diaphragm 216 and the faceplate 282 may be made in whole or in part of the same material, for example, silicon. The faceplate 282 and the flexible diaphragm 216 may be integrally formed from one or more adjacent substrates of a selected material, for example, silicon, as further shown and described herein. This type of design may be advantageous because it may eliminate an airtight seal between the physiological sensor 210 and the faceplate 282 that may be necessary if the physiological sensor and the faceplate were constructed as separate components and then joined together. The absence of the need for such an airtight seal between the physiological sensor 210 and the faceplate 282 is advantageous because there are then fewer locations where aqueous humor can seep into the housing 280, and because an airtight seal around or near the flexible diaphragm 216 could induce mechanical stresses or strains that may affect the performance of the flexible diaphragm.

[0073] 3B is a top perspective view of an example embodiment of a housing 280 for the intraocular physiological sensor implant 200 shown in FIG. 3A. This view shows a top cover 284. Like the faceplate 282, the top cover 284 may be made of a biocompatible material, although the specific material may be different than that used for the faceplate. In some embodiments, the top cover 284 is ceramic or glass. For example, the top cover 284 may be made of injection molded zirconia toughened alumina (ZTA) ceramic, injection molded yttria stabilized zirconia (YSZ), sapphire, or glass. Other materials and manufacturing techniques, such as machining or cutting, may also be used.

[0074] In some embodiments, the sensor implant 200 may be sized and shaped to be placed in the iridocorneal angle of a human eye. The dimensions of the sensor implant 200 may be, for example, 2-6 mm in length, 0.5-2 mm in width, and 0.3-1 mm in height. As illustrated, in some embodiments, the top cover 284 and / or the faceplate 282 may have one or more contoured surfaces or chamfers. For example, one side of the housing 280 may be contoured and have a convex radius of curvature R1 that corresponds to the normal radius of curvature of the iridocorneal angle of the human eye, generally in a plane perpendicular to the optical axis of the eye (in the illustrated xy plane). The radius of curvature R1 may be in the range of 5-7 mm, for example. The same side of the housing 280 may also be contoured and have a convex radius of curvature R2 that corresponds to the normal radius of curvature of the iridocorneal angle of the human eye, generally in the plane of the optical axis of the eye (in the illustrated yz plane). The radius of curvature R2 may be in the range of 0.1 to 0.4 mm, for example.

[0075] The three-dimensional shape of the illustrated embodiment of the housing 280 allows the intraocular physiological sensor implant 200 to be effectively positioned deep into the iridocorneal angle of the patient's eye. This in turn limits external visibility of the sensor implant 200 outside of the eye. In some embodiments, the sensor implant 200 can be provided with a note instructing the surgeon to position the sensor implant in the iridocorneal angle at the top of the patient's eye. This location can take advantage of the fact that the upper eyelid typically extends farther than the lower eyelid, and therefore can more effectively hide the sensor implant 200.

[0076] Compared to a straight sided housing having a similar arrangement in the iridocorneal angle, which leaves a gap between the housing and the curved surface of the iridocorneal angle, the three-dimensional shape of the housing 280 provides additional enclosed volume. This additional enclosed volume within the housing 280 can be used to accommodate additional or larger components and / or to reduce other dimensions of the housing. For example, as discussed further herein, more efficient use of the space provided by the three-dimensional housing 280 can allow for a larger coil 260, which in turn can improve communication and / or power transfer between the sensor implant 200 and an external device, or can allow for a larger battery 230, which can increase the time between charges.

[0077] Because the housing 280 of the sensor implant 200 is designed with at least one three-dimensional surface to fit deeply within the iridocorneal angle, it may have the potential to restrict the outflow of aqueous humor from the portion of the iridocorneal angle where it is located (either through the "normal" outflow pathway, which includes the trabecular meshwork and Schlemm's canal, or the "uveoscleral" outflow pathway, which includes the ciliary body, sclera, and ciliary body / suprachoroidal space). Any reduction in aqueous humor outflow is believed to be insignificant because the portion of the iridocorneal angle occupied by the sensor implant 200 is relatively small. However, in some embodiments, the housing 280 may include one or more flow-enabling features, such as protruding ribs or recessed grooves / channels. Flow-enabling features such as these may create an area of ​​separation between the housing 280 and the iridocorneal angle, thus allowing aqueous humor to exit the anterior chamber via physiological outflow pathways even when the housing of the sensor implant 200 is placed in contact with the surface of the iridocorneal angle.

[0078] In some embodiments, the flow-enabling features can be made from or can include porous materials, such as glass frit, porous plastics such as polypropylene, polyethylene, porous bonded polymeric fibers such as polyethylene, polyester, or other materials that are preferably hydrophilic and can be formed as open-celled porous structures. Such porous materials provide a plurality of fluid-operating capillary or pseudo-capillary structures that allow fluid movement through the bulk structure of the material itself. For example, the porous material can be provided on substantially the entire exterior surface of the housing 280, in ribs or strips on the housing, in grooves / channels formed on the exterior of the housing, etc. In embodiments, these flow-enabling features, such as ribs or grooves in the ceramic, can be formed directly on the housing 280, even if the ceramic itself remains a single monolithic component.

[0079] 4A-4C include top, top and bottom perspective views, respectively, of another example embodiment of a housing 280 for an intraocular physiological sensor implant 200. As shown in these figures, the housing 280 may include one or more anchors 286. The anchors 286 may protrude from a three-dimensional surface of the housing 280 designed to be positioned adjacent to a surface of the iridocorneal angle, for example. The anchors 286 are illustrated as protruding from the top cover 284, but could instead be protruding from the faceplate 282. The embodiment of the housing 280 shown in FIGS. 4A-4C may otherwise be identical to the embodiment described with respect to FIGS. 3A-3B.

[0080] The anchor 286 may include an entry tip designed to enter ocular tissue, such as the sclera, trabecular meshwork, etc., and barbs or other retention features to remain in place in the tissue after insertion. In some embodiments, the anchor 286 may be a drug-eluting anchor similar to that illustrated in FIG. 18 of U.S. Patent Application Publication No. 2015 / 0342875, entitled "Implants with Controlled Drug Delivery and Methods of Using Same," filed May 28, 2015, the contents of which are incorporated herein by reference in their entirety. In some embodiments, the anchor 286 may be a drainage stent to promote outflow of aqueous humor from the eye similar to that illustrated in FIG. 18 of U.S. Patent Application No. 9,554,940, entitled "Systems and Methods for Delivering Multiple Ocular Implants," filed March 14, 2013, the contents of which are incorporated herein by reference in their entirety. Drainage stent anchors are discussed in more detail herein with reference to FIGS. 4N-4R.

[0081] As shown in FIGS. 4A-4C, the width along the length of the housing 280 may be greatest at the center of the housing. However, the housing 280 may taper in width toward the ends of the housing. In some embodiments, the anchors 286 may be located toward the ends of the housing 284, such as outside the central third of the housing. This location of the anchors 286 may reduce the overall width of the sensor implant 200 as compared to alternative embodiments in which the anchors are located in the central portion of the housing 284. This reduced overall width of the sensor implant 200 may make the device easier to insert and manipulate in a patient's eye.

[0082] FIG. 4D illustrates another example embodiment of a housing 480 for an intraocular physiological sensor implant 200. In the embodiment illustrated by FIG. 4D, the housing 480 is placed at the implantation location and then the anchors are pushed through the retention tabs 482 with a blunt tool to penetrate the tissue and secure the implant in place. In particular, the top portion of FIG. 4D shows a side view of the housing 480, while the bottom portion of FIG. 4D shows a top view of the housing. In the illustrated embodiment, the housing 480 includes two retention tabs 482 extending from opposite sides of the housing. Although two retention tabs 482 are illustrated, other embodiments may include more or fewer retention tabs. Each of the retention tabs includes a through hole configured and dimensioned to hold an anchor 486. Each of the anchors 486 includes a penetration head having a penetration tip, an elongated body, and a retention head. The elongate body of each anchor 486 has a diameter smaller than the diameter of the through hole in the corresponding retention tab 482, while the penetration and retention heads of the anchor have diameters larger than the diameter of the through hole. As a result, each anchor 486 can slide freely within the through hole of the corresponding retention tab, but the penetration and retention heads of the anchor hold the anchor as captured within the retention tab. In some embodiments, the length of the elongate body of each anchor 486 is at least the thickness of the corresponding retention tab 482 plus the desired insertion depth of the penetration tip into the ocular tissue.

[0083] Once the surgeon has positioned the housing 480 at the desired location within the patient's eye, he or she applies a longitudinal force to the retention head of each anchor 486 along the axis of its body. The penetration head of the anchor 486 thereby extends the housing 480 into the ocular tissue and holds it in place. Similar retention tabs 482 and captured anchors 486 can be used in other embodiments of the detection implant 200. For example, the housing 280 of the detection implant 200 shown in Figures 3A and 3B could be modified to include retention tabs 482 on both sides of the housing.

[0084] In particular, for example, Figures 4E-4G illustrate housing 280 further comprising a number of retention tabs 482 disposed therein and configured to receive anchors 486. In comparison to Figure 4D, Figures 4E-4G illustrate an embodiment in which the anchors are rigidly secured to the implant prior to implantation in the eye. In other words, a separate "pushing step" of the anchors is not required to secure the implant. Figures 4E, 4F illustrate an embodiment in which the implant is not assembled. Figure 4G illustrates an embodiment in which the implant is assembled.

[0085] In these embodiments, by placing the implant at the implantation location, the anchor penetrates the tissue and secures the implant in place. Referring to FIG. 4E, the holes 482 in the housing 280 for receiving the anchors 486 may be the same size or may be different sizes to accommodate various features. For example, one hole could receive the anchor 486 while another hole could receive a removable dose canister, a permanent flow device, a flow anchor, etc. In an embodiment, the anchor 486 is constructed of titanium or other related material. In a preferred embodiment, the anchor 486 is about 1.5 mm in length and about 0.17 mm in width.

[0086] 4H and 4I illustrate the physical insertion of anchors 486 into retaining tabs 482 of housing 280 for assembly purposes. It should be understood that anchors 486 can be inserted into retaining tabs 482 of housing 280 pre-operatively or alternatively during surgery. Generally, elongated body 488 of each anchor 486 has a diameter smaller than the diameter of the corresponding through hole of retaining tab 482, but the maximum diameter of entry head 490 and retention head 492 of anchor 486 is larger than the diameter of the through hole. As a result, each anchor 486 can slide freely within the corresponding through hole of retaining tab, but entry head 490 and retention head 492 of anchor 486 are held captive in retaining tab 482. In some embodiments, the length of elongate body 488 plus the length of penetration head 490 of each anchor 486 is at least the thickness of the corresponding retention tab 482 plus the desired insertion depth of the penetration tip into ocular tissue. In other embodiments, portions of anchor 486, such as elongate body 488 and retention head 492, include spaces or gaps that allow a user and / or assembler to pinch and reduce the diameter of these components for insertion through retention tab 482. In some embodiments, retention head 492, along with its space or gap, is sized such that it can be detached from retention tab 482 at some time after implantation, if desired.

[0087] In a related embodiment, housing 280 includes alternative or additional features for securing anchor 486. For example, housing 280 may include a figure-eight loop wire instead of a rigid hole. The figure-eight loop wire could be attached to the housing and tightened by the surgeon when implanted to secure anchor 486 to the end of the loop. Alternatively, housing 280 could include both a rigid hole and a figure-eight loop wire for positioning and subsequent securement.

[0088] In another embodiment, the anchors 494 are attached to the housing 280 by alternative means. For example, FIGS. 4J-4M illustrate an anchor 494 without a retaining head 492. In a preferred embodiment, the anchor 494 is about 1.6 mm in length and about 0.2 mm in width. Specifically, the anchor 494 is positioned within the housing by, for example, the retaining tab 482 discussed previously herein. In this particular embodiment, the anchor 494 is threaded through the retaining tab 482 of the housing 280 prior to surgery. Generally, the elongated body of each anchor 494 has a diameter smaller than the diameter of the through hole of the corresponding retaining tab 482, but the maximum diameter of the entry head 496 is larger than the diameter of the through hole. As a result, each anchor 494 is free to slide within the through hole of the corresponding retaining tab 482, but the entry head 496 of the anchor 494 holds the anchor so that it is captured in the retaining tab 482. The anchor 494 further comprises a deformable end 498, which may further comprise a partial recess, deformation or hole. Once the anchor 494 is fully inserted into the through hole of the corresponding retention tab 482, the housing 280 and anchor 494 are fixedly secured to the workpiece. A carbide tip, or other similar machine tool, is then forced into the deformable end 498 of the anchor 494, thereby mechanically deforming the deformable end 498 to obtain a new, larger diameter. In this manner, by deforming the anchor 494 at the deformable end 498, the anchor 494 is permanently secured to the housing 280. Once permanently secured, the anchor 494 and housing 280 may be materialized as described herein.

[0089] In various embodiments, as illustrated by Figures 4N-4R, the anchor, e.g., anchor 486 or anchor 494, may be a drug-eluting anchor and / or have one or more fluid channels to facilitate the outflow of aqueous humor from the eye. For example, the anchor may include one or more inlets, one or more outlets, and one or more fluid paths connecting the inlets and the outlets. In embodiments, when the anchor is threaded through the trabecular meshwork and placed on the sclera, the inlets are in the anterior chamber of the eye and the outlets are in Schlemm's canal, such that the anchor directs fluid from the anterior chamber to Schlemm's canal through the fluid channels. In some embodiments, the fluid channels are open channel channels, e.g., as illustrated by Figures 4N-4P with open channel channels, the inlets, outlets, and fluid channels are one single open passage. In other embodiments, the fluid channels are enclosed passages, e.g., as illustrated by Figures 4Q, 4R.

[0090] In embodiments where the anchor is a drug-eluting anchor, it serves at least two functions: (1) to secure the housing 280 (and the entire sensor implant 200) to ocular tissue; and (2) to provide the eye with sustained drug elution into the anterior chamber to aid in any ocular medical condition requiring continuous medication, such as improving aqueous humor outflow and treating glaucoma. One such stand-alone drug-eluting anchor is described in U.S. Patent Application Publication No. 2015 / 0342875, entitled "Implants with Controlled Drug Delivery Capabilities and Methods of Using Same," which is incorporated herein by reference. Although only discussed as stand-alone drug-eluting implants in U.S. Patent Application Publication No. 2015 / 0342875, it should be understood that the anchor portion of the drug-eluting implant could be used for the additional purpose of securing the intraocular sensors discussed herein or any other desired intraocular implant intended to remain stationary within the anterior chamber (or any other anatomical portion) of the eye to ocular tissue.

[0091] In a preferred embodiment, the anchor comprises some of the features discussed above. For example, the anchor may comprise one or more fluid flow channels and may comprise a mechanically deformable end. In this preferred embodiment, the anchor further comprises a clocking feature. For example, FIGS. 5A-5C illustrate perspective, front and cross-sectional side views of an anchor 500 comprising a clocking feature along with a fluid flow channel and a mechanically deformable end. FIGS. 5D-5G further illustrate additional perspective and front views of an intraocular physiological sensor implant comprising an anchor 500 comprising the clocking features and fluid flow channels discussed herein. In particular, the anchor 500 comprises an elongate body 502, a retaining head 504 and an entry head 506 (previously discussed above). Additionally, the anchor 500 comprises at least one fluid flow channel having an inlet 508 and an outlet 510. In an embodiment, the fluid flow channel between the inlet 508 and the outlet 510 is angled as it passes through the retaining head 504. When anchor 500 is inserted through the trabecular meshwork and placed on the sclera, inlet 508 is in the anterior chamber of the eye and outlet 510 is in Schlemm's canal, such that anchor 500 directs fluid from the anterior chamber through the fluid flow path to Schlemm's canal.

[0092] In this preferred embodiment, anchor 500 further comprises a staking feature 512. For example, staking feature 512 is a deformable end, which may further comprise a partial depression, deformation, or hole. Upon fully inserting anchor 500 into housing 280, staking feature 512 deforms to attach anchor 500 to housing 280 (or housing 480) (as discussed in more detail above with respect to deformable end 498).

[0093] Additionally, in this preferred embodiment, the anchor 500 further includes a clocking feature 514. For example, the clocking feature 514 may be a particular geometric profile on the surface of the retaining head 504 of the anchor 500, such as a bevel, chamfer, fillet, or other rounded edge. The housing 280 may likewise include a similar geometric profile such that the clocking feature 514 on the retaining head 504 matches the housing 280. The clocking feature 514 prevents the anchor 500 from inadvertently twisting after it is inserted into the housing 280. By preventing twisting of the anchor 500, the clocking feature 514 ensures that the inlet 508 and outlet 510 are properly positioned relative to relevant anatomical features in the housing 280 and the intraocular environment, thus ensuring proper flow and drainage across the fluid flow path.

[0094] 5H shows an exploded view of an example embodiment of the intraocular physiological sensor implant 200. It should be understood that certain previously described structures, such as anchors 286, 486, are included that are not illustrated in some of the remaining figures. In the illustrated embodiment, the faceplate 282 includes an electrical interconnect circuit 270 (described in further detail below). Conductive posts 272 and surface mounted capacitors 271 are provided on the electrical interconnect circuit 270. An integrated circuit 290 and a battery 230 are then provided on the faceplate 282 in a stacked configuration. A top cover 284 is then bonded together with the faceplate 282 to form a sealed housing 280.

[0095] 5I-5L are perspective layer-by-layer views of an example embodiment of the intraocular physiological sensor implant 200 shown in FIG. 5H. In FIG. 5I, a complete housing 280 is shown with a faceplate 282 and a top cover 284 joined together to enclose the battery 230, the integrated circuit 290, and other components of the sensor implant 200. In FIG. 5J, the top 284 of the housing 280 is shown removed. In the illustrated embodiment, the battery 230 is provided on top of a stack of electrical components for the sensor implant 200. In some embodiments, the battery 230 is a thin-film rechargeable lithium-ion or lithium-metal battery. The illustrated embodiment of the battery 230 includes electrical contacts on the bottom surface that connect with a battery connection post 272, which in turn is connected to the electrical interconnect circuit 270 via, for example, conductive epoxy. Upon assembly, the battery connection post 272 may be accessed for testing of system integrity and additional battery 230 calibration, such as critical voltage threshold testing. For example, some of the connection posts 272 may be materialized specifically for power purposes and used as cathodes and anodes, while other connection posts 272 may be test or calibration posts. In various embodiments, programming and calibration enabled by one or more of the posts 272 includes marking the device's serial number. It should be understood that the posts 272 also provide a horizontal surface to which a battery may be attached. Having a horizontal surface is advantageous, for example, when probing with a probe card to probe several electrical pads at once and / or to test fixtures.

[0096] In Figure 5K, the battery 230 has been removed to reveal the integrated circuit 290. As previously discussed, the integrated circuit 290 may comprise, for example, the controller 220, the measurement memory 240, the transceiver / receiver 250, the capacitance to digital converter 212, and other associated components. In Figure 5L, the integrated circuit 290 has been removed to reveal the electrical interconnect circuitry 270, embodiments of which are described in more detail below. Figure 5L also shows the coil 260. In the illustrated embodiment, the coil 260 is embedded in the faceplate 282, as described below.

[0097] 6A-6D are top layer views of an example embodiment of the intraocular physiological sensor implant 200 shown in FIG. 5H. FIG. 6A is a top view showing the inner surface of the faceplate 282. As discussed further herein, an airtight seal 288 can be formed around the periphery of the inner surface of the faceplate 282. An electrical interconnect circuit 270 can be formed in or on the inner surface of the faceplate 282. The electrical interconnect circuit 270 can include various conductive pads 274 and traces for making electrical connections between the various electrical components of the sensor implant 200. These conductive pads and traces can be provided on the inner surface of the faceplate 282 above the embedded copper loop of the coil 260. An insulating layer can be provided on the copper coil of the embedded coil 260 to electrically insulate the coil from the electrical interconnect circuit 270. This insulating layer can be, for example, a polymer such as polyimide, parylene, photoresist or other photopatternable polymers including SU-8, BCB, or photopatternable polyimide. The insulating layer may be, for example, an oxide or nitride layer, such as silicon oxide, deposited by physical vapor deposition (PVD). Other insulating layers are possible. In the illustrated embodiment, the electrical interconnect circuit 270 includes two electrical pads 273 that pass through the faceplate 282 and are connected to conductive vias that connect with electrodes of the physiological sensor 210.

[0098] FIG. 6A shows a coil 260, in an exemplary embodiment, made of a conductive loop embedded in the inner surface of the faceplate 282, e.g., copper, silver, gold, platinum, tungsten, low resistivity silicon, silicon doped with an impurity, e.g., boron or phosphorus. In a preferred embodiment, the coil 260 is entirely embedded in the faceplate 282, such that its top surface is flush with the surface of the faceplate 282. In a preferred embodiment, the coil 260 is electrically insulated from the bulk material of the faceplate 282 by a backing oxide, nitride, or other insulating material, e.g., a polymeric material, that is deposited on the silicon before the structure is filled with a conductive material (e.g., copper, silver, or other related material) by sputtering, plating, or other deposition method. This backing material electrically isolates the coil 260 from the faceplate 282. In some embodiments, additional design elements are included with the purpose of improving the electrical isolation of the coil 260 from the faceplate 282. For example, the insulating backing material may be purposely thickened specifically for this reason. For example, a thick insulating layer of oxide several microns may be grown or deposited on the silicon surface of the faceplate 282, or the silicon structure may be converted generally to a silicon dioxide structure by thermal conversion prior to deposition of the coil conductor. As a further approach to minimize parasitic capacitance or eddy current effects in the silicon material near the coil 260, the faceplate 282 may be designed such that in its final configuration there is an air or vacuum gap below and / or above the coil due to selective removal of silicon of the faceplate 282 during the manufacturing process. In some embodiments, the embedded coil 260 does not necessarily make the faceplate 282 thicker than in other embodiments given structural concerns such as stiffness and strength. Thus, by embedding the coil loop in the inner surface of the faceplate 282, the housing 280 can be made smaller since little or no additional space is needed inside the housing for the coil 260 that would be required if the coil were provided as a separate component from the faceplate 282.In an alternative embodiment, the coil 260 and the interconnect circuit 270 are provided as separate components as a flexible circuit, discussed below in connection with Figures 9A-9D. In yet another embodiment, the coil 260 and the interconnect circuit 270 are provided as separate components that are rigid, such as a coil embedded in a thin free-standing piece of silicon, or other rigid material such as glass, or a rigid polymer such as epoxy, BCB, or SU-8. The flexible circuit 900, or any other separate component, may advantageously avoid certain thermal expansion characteristics described in more detail herein. The flexible circuit 900 may advantageously avoid certain thermal expansion characteristics described in more detail herein. For example, one single piece flexible circuit 900 may be advantageous. Additionally or alternatively, by embedding the coil 260 in the faceplate 282, the conductive material making up the coil loop may be thickened, since it does not necessarily occupy additional space beyond that which would already be occupied by the faceplate. The thickness of the conductive material as well as the aspect ratio (thickness to width of the embedded conductive material) can also be greater by embedding the coil in the faceplate 282 than would otherwise be possible using additive processes to fabricate the coil on the faceplate. Increasing the thickness of the conductive material lowers the electrical resistance of the coil 260, which improves its quality factor or efficiency. Additionally, increasing the number of turns improves the inductance of the coil 260, which also improves its efficiency. The ends of the conductors making up the coil 260 can be connected to conductive pads 274 provided as part of the electrical interconnect circuit 270 to connect the coil with other components of the sensor implant 200, particularly the integrated circuit 290.

[0099] 6A also shows a humidity sensor 610 provided on the inner surface of the faceplate 282. The humidity sensor 610 can be used to detect moisture inside the housing 280. This can be useful for the purpose of detecting failure or impending failure of the sensor implant 200 due to damage or failure of the airtight seal or the housing 280, since some of its components, such as the battery 230, can suffer reduced operational life, reduced performance, and even failure if exposed to too much moisture. In the case of a very slow moisture leak inside the housing 280, the humidity sensor 610 can provide a noticeably earlier notification of the leak than would otherwise be possible.

[0100] In some embodiments, the humidity sensor 610 may be a capacitor with spaced apart interdigitated electrodes, such as the interdigitated electrodes 612, 614 shown in FIG. 6A. A moisture-sensitive dielectric may be disposed between, on, or around the electrodes 612, 614. The capacitance of the humidity sensor 610 depends on the dielectric constant of the moisture-sensitive dielectric. Thus, with a material whose dielectric constant changes when exposed to moisture, moisture inside the housing 280 can be detected by detecting the change in capacitance of the humidity sensor 610. In one embodiment, no dielectric is applied over the interdigitated electrodes, but detects the change in the dielectric constant of the air itself inside the implant as the moisture content in the air increases. The number of fingers or tines of the interdigitated interdigitated electrodes 612, 614, as well as the spacing between the fingers or tines, may be adjusted and designed to generate a particular range of capacitance based on the capacitance sensitivity of the integrated circuit. In some embodiments, the humidity sensor 610 includes 10 or 20 or even more fingers or tines on each of its two sides. By increasing the number of fingers or tines, the humidity sensor 610 has increased sensitivity and outputs a capacitance signal high enough to be recorded by the integrated circuit.

[0101] In some embodiments, a getter material may be provided inside the housing 280. Getter materials, e.g., desiccants, may be used to absorb, adsorb, or chemically bind moisture, gases, etc., to keep those contaminants away from sensitive components inside the housing 280 to maintain a suitable operating environment. Such getter materials may be useful even in the absence of a humidity sensor 610, since even moisture-impermeable materials, e.g., ceramics, may allow some moisture to pass through (depending on thickness) when exposed to moisture over extended periods of time, e.g., years or decades. Such getter materials may also be useful to remove, absorb, adsorb, or chemically bind residual gases or moisture trapped within the implant during the sealing operation of the faceplate to the housing. For example, even if the implant assembly and sealing process is performed under a vacuum or in an inert gas environment such as helium, argon, or nitrogen, residual other gases and water vapors may still be inadvertently trapped. Such trapped species may react with the battery if left unchecked, degrading its performance, or may react with integrated circuits, causing their performance to drift over time. Additionally, gases and / or moisture are degassed over time from various components or from the surfaces of various components in the internal implant volume. These components include the faceplate itself, the integrated circuit, the flexible coil circuit, and the conductive epoxy used for the interconnects. However, in embodiments including the humidity sensor 610, a getter material is used as a moisture sensitive dielectric for the humidity sensor, thereby achieving a synergistic effect that allows not only to remove or isolate moisture inside the housing 280, but also to detect such moisture. The getter material may be, for example, a sorbing species suspended in a carrier material that may be applied or deposited on the interdigitated electrodes. For example, sorbing particles, such as those made of metals or metal alloys that react with nitrogen, oxygen, water vapor, etc., or micro- or nano-porous particles that absorb gases or water vapor, such as zeolite minerals, may be suspended in a liquid adhesive applied on the interdigitated electrodes.A getter material may be used as a moisture sensitive dielectric for the humidity sensor 610, but this is not necessary. The getter material may be disposed elsewhere, or throughout the housing 280. The getter may be provided in the housing 280, for example, as a paste or surface coating, or a preformed solid component known as a preform.

[0102] The capacitance of the humidity sensor 610 can be determined using a capacitance-to-digital converter. In some embodiments, the same capacitance-to-digital converter 212 used to read the capacitive pressure sensor 210 is also connected to the humidity sensor 610 and used to read its capacitance. In this manner, the space, cost, and / or complexity of an additional capacitance-to-digital converter can be avoided.

[0103] The capacitance of the humidity sensor 610 could be read periodically by the controller 220 according to a set schedule and / or on demand, for example, whenever an intraocular pressure measurement is downloaded from the sensor implant 200 by an external device, or the capacitance of the humidity sensor 610 could also be read when the battery 230 is recharged by an external device. By tracking the capacitance of the humidity sensor 610 over time, moisture inside the housing 280 can be detected. For example, the controller 220 and / or the external device can determine if the capacitance of the humidity sensor 610 changes over time by an amount that exceeds a threshold. Based on measurements from the humidity sensor 610, a failure or impending failure of the sensor implant 200 can be identified.

[0104] Measurements from the humidity sensor 610 can also be used during manufacturing to ensure the integrity of the hermetic seal 288. During manufacturing, the faceplate 282 and top cover 284 can be sealed together in a dry environment. The humidity sensor 610 can then be used to monitor any extraneous moisture inside the sealed housing. An initial capacitance value can be read from the humidity sensor 610 after the housing 280 is sealed. Subsequent capacitance values ​​can then be read later from the humidity sensor 610 and compared to the initial capacitance value. Optionally, the housing 280 can be exposed to an external high humidity environment, and also optionally increased pressure, to accelerate the ingress of any moisture through a defective hermetic seal 288. A change in capacitance of the humidity sensor 610 above a threshold value can advantageously detect a failure of the hermetic seal 288 before the sensor implant 200 is surgically implanted into the patient's eye.

[0105] 6B is a top view showing an integrated circuit 290 (shown with semi-transparent shading) stacked in place on faceplate 282. As illustrated, a bottom surface of integrated circuit 290 may include a number of electrical contacts, e.g., pads, connectors, etc., for making electrical connections between the integrated circuit and underlying electrical interconnect circuitry 270.

[0106] FIG. 6B shows conductive posts 272 disposed on some of the pads of the electrical interconnect circuit 270. The conductive posts 272 can be used to make connections to components higher in the stack of components inside the housing 280 of the sensor implant 200, such as the battery 230. The battery 230 is connected to the interconnect circuit 270 and the conductive posts 272 with conductive epoxy. The conductive pillars may provide probe locations used to interface with integrated circuits during assembly. FIG. 6B also shows a surface mount capacitor 271 in place. In an embodiment, the surface mount capacitor 271 is configured to absorb frequency spikes, such as those associated with decoupling in response to digital logic switching.

[0107] FIG. 6C is a top view showing the battery 230 stacked in place on the integrated circuit 290. FIG. 6D is the same as FIG. 6C, except that the battery 230 is shown with semi-transparent shading to allow visibility of the electrical connections made underneath the battery on its bottom surface. The conductive post 272a connects to the anode contact of the battery 230, while the conductive post 272b connects to the cathode contact. These connections can be made, for example, using conductive epoxy. It should be understood that the anode contact tracing 272a can be made larger compared to the cathode tracing contact 272b, as can be used to ensure that the backside of the interconnect circuit 270 has a more reliable ground to the system. Additional conductive pillars that do not connect to the battery 230 can be included. For example, these additional conductive pillars can be used when programming the sensor implant 200, such as programming the ASIC during assembly, tuning the voltage of the battery 230 and related components, trimming currents and voltages, etc.

[0108] FIG. 7A is a cross-sectional view of a portion of an example faceplate 282 for the housing 280 of the intraocular physiological sensor implant 200. In some embodiments, the faceplate 282 can comprise a stack of silicon substrates 710, 720, 730, or more stacked substrates. In the illustrated embodiment, the total thickness of the faceplate 282 is 200 μm, but in other embodiments, the thickness of the faceplate can be, for example, 50 μm to 300 μm. Each of the silicon substrates 710, 720, 730 can be a bulk silicon layer or a high conductivity silicon layer that can be formed, for example, by adding suitable dopants to bulk silicon and / or using polycrystalline silicon. In the illustrated embodiment, the bottom substrate 710 is a bulk silicon layer that is 65 μm thick, the middle silicon substrate 720 is a high conductivity silicon layer that is 10 μm thick, and the top substrate 730 is a bulk silicon layer that is 120 μm thick, although other thicknesses can be used.

[0109] The conductive loops forming the coil 260 may be embedded in an upper surface (corresponding to the inner surface of the faceplate 282) of the bulk silicon layer of the top substrate 720. In the illustrated embodiment, the loops of the coil 260 are embedded 25 μm deep in channels formed in the bulk silicon layer of the top substrate 720, with a width of 8 μm and a gap of 4 μm between the loops of the coil 260. However, other depths and associated dimensions may be used.

[0110] As shown, the upper and lower silicon substrates 710, 720 can be stacked together and bonded with the high conductivity silicon layers facing each other. The bulk silicon layer of the lower substrate 710 can be etched away or otherwise removed in the area of ​​the capacitive pressure sensor 210, thereby exposing the high conductivity silicon layer of the lower substrate in that area. In some embodiments, the high conductivity silicon layer can have a thickness of 1 μm to 20 μm. The thicknesses of the two layers can be the same or different thicknesses.

[0111] The high conductivity silicon layer can be used as the two electrodes 216, 217 for the capacitive pressure sensor 210. In the illustrated embodiment, the high conductivity silicon layer of the lower substrate 710 is used as the flexible diaphragm electrode 216, while the high conductivity silicon layer of the upper substrate 720 is used as the counter electrode 217 for the capacitive pressure sensor 210. Although the two electrodes 216, 217 are seen to be in contact with each other in FIG. 7A, there is a gap between them at least in the area of ​​the pressure sensor 210. The gap between the two electrodes 216, 217 can be, for example, 0.05 μm to 2 μm. This gap can be formed by etching away or otherwise removing a portion of the thickness of the high conductivity silicon layer used as the counter electrode 217 in the area above the flexible diaphragm electrode 216. The gap can also be formed by removing a portion of the thickness of the flexible diaphragm electrode 216 in a similar manner. The gap between flexible diaphragm electrode 216 and counter electrode 217 may be vacuum sealed, or the gap may be filled with air or another gas to a desired pressure.

[0112] An isolation trench 218 may be formed around the counter electrode 217 to electrically isolate it from the flexible diaphragm electrode 216. Conductive vias may be formed through the bulk silicon layer of the top substrate 720 to electrically connect the electrodes 216, 217 of the capacitive pressure sensor 210 to the conductive pads 273 of the electrical interconnect circuit 270.

[0113] In an embodiment, the faceplate 282 includes an additional capacitive sensor that includes a second set of gaps between the two electrodes 216, 217 in the same manner as the capacitive pressure sensor 210. The additional capacitive sensor is further connected to another pair of conductive vias 219 and a pair of conductive pads 273 that can be used to connect the additional capacitive sensor to the integrated circuit 290 in the same manner as the capacitive pressure sensor 210. However, unlike the capacitive pressure sensor 210 that includes an opening in the underlying substrate 710 to allow pressure to act on the flexible diaphragm electrode 216 and deform in response to pressure changes, the additional capacitive sensor does not include an opening in the underlying substrate 710. Rather, the underlying substrate 710 is continuous across the sensor location, preventing the electrode 216 (of the additional capacitive sensor) from moving in response to changes in external pressure.

[0114] The additional capacitive sensor does not respond to external pressure changes, but can be used to detect strains in the faceplate 282, such as those caused by bond stresses that arise during attachment of the faceplate 282 to the housing 284 creating the sealed housing 280, stresses caused by coefficient of thermal expansion (CTE) mismatch between the faceplate 282 and the housing 284, or other stresses acting on the faceplate 282 that may be the result of temperature changes. Such stresses can cause strains in the faceplate 282 that can affect the output of the capacitive pressure sensor 210 and cause errors in its pressure measurements. Providing an additional capacitive sensor allows the strains in the faceplate 282 to be measured, and this information can be used to compensate or correct the output of the capacitive pressure sensor 210 to obtain more accurate pressure measurements. In certain embodiments, the additional capacitive sensor can be used as a temperature sensor by measuring and attributing the above effects to changes in temperature. When used in this manner, its output can be calibrated.

[0115] FIG. 7B illustrates an embodiment of an intraocular physiological sensor implant 200 in which the physiological sensor 210 is embedded in the faceplate 282. As discussed above with respect to FIG. 7A, the bulk silicon layer of the underlying substrate 710 can be removed in the area of ​​the capacitive pressure sensor 210, thereby exposing the high conductivity silicon layer of the underlying substrate that is used as the flexible diaphragm electrode 216. As shown in FIG. 7B, this results in the capacitive pressure sensor 210 being embedded from the outer surface of the faceplate 282 (i.e., the bottom surface of the bulk silicon layer of the underlying substrate 710). The recess in the faceplate 282 has sidewalls whose height corresponds to the thickness of the removed bulk silicon layer of the underlying substrate 710. Because the flexible diaphragm electrode 216 can be delicate, its placement in this recess in the faceplate 282 provides a measure of protection against damage when handling or manipulating the implant prior to and during surgical implantation.

[0116] While the placement of the embedded flexible diaphragm electrode 216 may be advantageous for its protective properties, it may also cause some complications that will affect the ability of the capacitive pressure sensor 210 to operate within the eye. For example, the recess in the faceplate 282 may have a tendency to trap an air pocket adjacent to the flexible diaphragm electrode 216 when the sensor implant 200 is inserted into a patient's eye. Although the air pocket may at least partially transfer pressure from the aqueous humor to the flexible diaphragm electrode 216, it is also possible that an air pocket filling or partially filling the recess in the faceplate 282 may adversely affect the accuracy of the IOP measurement due to forces generated by surface tension at the interface of the air pocket with the aqueous humor and / or the flexible diaphragm electrode 216, or due to other effects such as affecting the parasitic capacitance acting on the capacitive pressure sensor 210.

[0117] This potential challenge may be at least partially ameliorated by providing a hydrophilic coating on the inside of the recess. For example, the perimeter of the recess in the faceplate 282 may be coated with a hydrophilic material. Similarly, the flexible diaphragm electrode 216 disposed inside the recess may be similarly coated with a hydrophilic material. The presence of a hydrophilic material in the recess may facilitate wetting of the recess by aqueous humor. Examples of suitable hydrophilic materials include various oxides, including silicon oxide, titanium oxide, and tantalum oxide, various nitrides, including silicon nitride, titanium nitride, and tantalum nitride, various carbides, including silicon carbide, titanium carbide, or other related materials. Such materials may be deposited as thin layers using physical vapor deposition (PVD) techniques, such as atomic layer deposition (ALD), sputtering or evaporation, or chemical vapor deposition (CVD), among others. Other materials may be applied as thin films that create hydrophilic surfaces, including biomaterials, such as heparin, poly-L-lysine, or other materials. Alternatively and / or additionally, the hydrophilicity of the recess and / or the hydrophilic surface of the peripheral wall of the flexible diaphragm 216 may be increased by increasing the surface roughness using various means such as dry or wet chemical etching or physical etching such as ion bombardment. Such roughening may occur before, after, or instead of coating with a hydrophilic material. More generally, a coating may be provided to reduce leakage, reduce wear, and increase durability of the physiological sensor 210.

[0118] In some embodiments, the recess in the faceplate 282 in which the flexible diaphragm electrode 216 is disposed can be filled with a non-compressible, pressure-transmitting gel or other substance prior to insertion into the eye. The gel may displace air from the recess. Additionally, once the sensing implant 200 is surgically implanted, the gel may act as a pressure-transmitting medium that can allow aqueous humor in the eye to exert pressure on the capacitive pressure sensor 210 (disposed within the recess in the faceplate 282). Examples of suitable materials for the non-compressible, pressure-transmitting gel include silicone gel, fluorosilicone gel, or other related materials.

[0119] 7C is a perspective view of a cross section of a portion of an example faceplate 282 for the housing 280 of the intraocular physiological sensor implant 200 shown in FIG. 7A. The perspective view of FIG. 7C again shows the flexible diaphragm electrode 216 and the counter electrode 217 of the capacitive pressure sensor 210. This perspective view also shows an isolation trench 218 formed around the counter electrode 217 to electrically isolate it from the flexible diaphragm electrode 216. Additionally, the view in FIG. 7C shows a conductive via formed through the bulk silicon layer of the top substrate 720 to electrically connect the counter electrode 217 of the capacitive pressure sensor 210 to one of the conductive pads 273 (see FIG. 6A) of the electrical interconnect circuit 270. Although not shown in the illustrated cross section, a second conductive via can be formed through the bulk silicon layer of the top substrate 720 to electrically connect the flexible diaphragm electrode 216 to the other conductive pad 273. Alternatively, the substrate, such as the top substrate 720, may be any other metal or silica for forming vias. These conductive vias are used to route capacitive signals from the capacitive pressure sensor 210 to other components of the sensor implant 200.

[0120] 7D and 7E illustrate an example embodiment of how the coil 260 is electrically connected to the electrical interconnect circuit 270 of the intraocular physiological sensor implant 200. As previously discussed, the coil 260 may be formed of a conductive material 262 embedded in a channel formed in the top of the bulk silicon layer of the top substrate 720. The channel may be a single continuous channel that spirals around the periphery of the faceplate 282 to form a spiral of loops. Once the conductive material 262 is deposited in the channel, an insulating layer 722 may be formed over the embedded conductive material 262. The insulating layer may be, for example, an oxide layer or a polymer layer. Holes may be left in the insulating layer 722 on each end of the coil 260. A conductive pad 274 (see FIG. 6A), which is part of the electrical interconnect circuit 270, may then be connected to each end of the coil 260 through the insulating layer 722.

[0121] 8A is a top perspective view of an example embodiment of an intraocular physiological sensor implant faceplate 282 including a stress relief cutout 810 between the loop of the embedded coil 260 and the physiological sensor 210. In addition to the stress relief cutout 810, FIG. 8A shows the embedded loop of the coil 260 and the conductive vias 219 from the two electrodes 216, 217 of the capacitive pressure sensor 210 through the bulk silicon layer of the top substrate 720.

[0122] In embodiments in which the coil 260 is embedded in the surface of the faceplate 282, the embedded coil may affect the mechanical properties of the capacitive pressure sensor 210 in which it is integrated. For example, the conductive material from which the coil 260 is fabricated, such as copper, is unlikely to have the same thermal expansion coefficient as the material from which the faceplate 282 and the capacitive pressure sensor 210 are fabricated, such as silicon. Thus, if the temperature of the sensor implant 200 changes after the coil material is deposited in the faceplate 282 (e.g., when the sensor implant is raised to body temperature after being surgically implanted in a patient's eye), the different thermal expansion coefficients of the two materials may cause mechanical stresses and strains in the faceplate. These mechanical stresses and strains have the potential to change the behavior of the flexible diaphragm of the capacitive pressure sensor 210. This, in turn, may reduce the accuracy of intraocular pressure measurements obtained using the capacitive pressure sensor 210.

[0123] Temperature induced mechanical stresses and strains in the faceplate 282 may be reduced by depositing the coil material in the faceplate in a manufacturing environment where the temperature is held at or near normal human body temperature. The faceplate 282 may also include stress relief cutouts 810 that mitigate the effects of any mechanical stresses and strains induced by the loops of the embedded coil 260, either by temperature or by other means. The stress relief cutouts 810 may surround the capacitive pressure sensor 210 and may be located between the loops of the coil 260 and the capacitive pressure sensor 210.

[0124] FIG. 8B is a perspective view of a cross section of faceplate 282 through stress relief cut 810. FIG. 8B shows bottom substrate 710 and top substrate 720 of faceplate 282. A loop of coil 260 is shown embedded in the bulk silicon layer of top substrate 720. FIG. 8B also shows flexible diaphragm electrode 216 and counter electrode 217 of capacitive pressure sensor 210. A first conductive via 219a passes through top substrate 720 from counter electrode 217, while a second conductive via 219b passes through top substrate 720 from the highly conductive silicon layer of substrates 710, 720 that is an extension of or adjacent counter electrode 217 and flexible diaphragm electrode 216, respectively.

[0125] In the illustrated embodiment, the stress relief cutout 810 is a channel through the bulk silicon layer of the top substrate 720 of the faceplate 282. In the illustrated embodiment, the channel completely surrounds the mechanically active portion of the flexible diaphragm electrode 216 of the capacitive pressure sensor 210, while the loop of the coil 260 completely surrounds the stress relief cutout 810. Thus, the stress relief cutout 810 is disposed between the loop of the coil 260 and the mechanically active portion of the flexible diaphragm electrode 216. The stress relief cutout 810 helps to mechanically isolate the mechanically active portion of the flexible diaphragm electrode 216 from the remainder of the faceplate 282. Thus, the resulting mechanical stress from the embedded loop of the coil 216, whether induced by temperature changes or by other means, has a reduced effect on the mechanical properties of the flexible diaphragm electrode 216.

[0126] Although the stress relief cuts 810 are shown through the entire thickness of the bulk silicon layer of the top substrate 720, in other embodiments the stress relief cuts may only partially through the bulk silicon layer of the top substrate 720. Alternatively, the stress relief cuts 810 may pass completely through the top substrate 720 and partially through the bottom substrate 710. The stress relief cuts 810 are illustrated as circular or oval loops, although other shapes for the stress relief cuts 810 are possible. Additionally, in some embodiments there may be multiple separate stress relief cuts 810 at various angular locations around the flexible diaphragm electrode 216. Some or all of these stress relief cuts may not completely surround the capacitive pressure sensor 210.

[0127] FIG. 9A illustrates an embodiment of a faceplate 282 and a circuit board 900 for an intraocular physiological sensor implant 200. The coil 260 and / or electrical interconnect circuitry 270 may be embedded or formed on the inner surface of the faceplate 282 as shown in FIGS. 5H-6D, although this need not be the case in all embodiments. For example, as shown in FIG. 9A, the coil 260 and / or electrical interconnect circuitry 270 may be formed as one or more components that are separate from the faceplate 282. In the illustrated embodiment, the coil 260 and electrical interconnect circuitry 270 are provided on a circuit board 900. The circuit board 900 includes two electrical pads 273 that connect to the electrodes 216, 217 of the capacitive pressure sensor 210 with conductive vias 219 when the circuit board is placed over the faceplate 282. In general, the circuit board 900 may be constructed from silicon, from a polymer such as polyimide, or from other materials such as glass or other polymers. The circuit board 900 may be several layers that are stacked together during manufacture to create a multi-layer coil, for example, multiple pieces each having one or more turns of a coil that can be stacked together. For example, three layers each having two coils may be stacked to create a six-layer coil. The top layer will have circuit traces on its top side. When multiple pieces are stacked, interconnects between each layer are necessary.

[0128] 9B and 9C show top and perspective views of example embodiments of circuit boards similar to circuit board 900 in unfolded and folded configurations. For example, FIG. 9B illustrates a foldable circuit board 902. The illustrated embodiment of circuit board 902 has a surface area preferably larger than the surface of faceplate 282 on which the circuit board is designed to be placed. The larger surface area of ​​circuit board 902 provides additional area for coil 260 than would be available in a non-folded design. For example, a configuration equivalent to a four-layer coil can be constructed by folding two two-layer coil sections 905 of circuit board 902 onto each other. Such a configuration would be useful, for example, to overcome manufacturing limitations that make it impossible or cost prohibitive to realize a four-layer monolith coil. Circuit board 902 also includes a number of flexible connection regions 910 that allow various sections 905 of circuit board 902 to be folded to fit into a footprint provided by faceplate 282. In some embodiments, the sections 905 of the circuit board 902 that are connected by the linking regions 910 are also flexible such that the entire circuit board is flexible. However, in other embodiments, the sections 905 that are connected by the linking regions 910 may be rigid or relatively rigid. For example, FIG. 9B illustrates a foldable circuit board 902 that includes three sections 905 with two flexible linking regions 910. Similarly, for example, FIG. 9C illustrates a foldable circuit board 904 that includes two sections 905 with one flexible linking region 910. It should be understood that more (or fewer) sections and / or flexible linking regions are contemplated herein.

[0129] 9D illustrates an example embodiment of how coil 260 may be formed on multiple sections 905 of a circuit board, such as the circuit board 902 illustrated in FIG. 9B. In some embodiments, coil 260 is a conductive trace formed on a single section 905 of circuit board 902. The conductive traces making up coil 260 may be made by patterning a conductive material on selected sections 905 of circuit board 902. The conductive material may be patterned on one or more layers of circuit board 902. The width and height of the conductive traces may be specified to reduce the electrical resistance of coil 260 to an acceptable amount.

[0130] The conductive traces can be laid out on the sections 905 of the circuit board 902 to form multiple loops as a spiral loop. By increasing the number of loops, the inductance of the coil 260 can be increased, which can also increase the sensitivity of the coil. However, the space available on a given section 905 of the circuit board 902 can limit the number of loops that can be formed. If the manufacturing process used to deposit the conductive material is constrained in terms of the height of the conductive traces that can be formed, thereby exacerbating the lack of space to form the coil loops, the conductive traces need to be wide so that the electrical resistance of the traces is low enough. However, this space constraint can be overcome by patterning the conductive traces on multiple separate sections 905 of the circuit board 902 such that the coil loops formed on the separate sections 905 align with each other when the circuit board is in a folded configuration. The coil loops formed on the separate sections 905 of the circuit board 902 can also be positioned such that when the circuit board is in a folded configuration, currents passing through the conductive traces induce constructive rather than destructive magnetic fields in the coil loops patterned on the separate sections of the circuit board.

[0131] 9D shows a portion of a first section 905a and a portion of a second section 905b of the circuit board 902. The two sections 905a, 905b are joined by a coupling region 910. A conductive trace forming the coil 260 is formed on both sections 905a, 905b of the circuit board 902 as well as the coupling region 910. A first end 264a of the conductive trace is shown in the first section 905a of the circuit board 902. The conductive trace spirals radially outward from the first end 264a in a counterclockwise direction around the first section 905a of the circuit board 902 to form a first set of coil loops 260a. A second end 264b of the conductive trace is shown in the second section 905b of the circuit board 902. The conductive traces spiral radially inward from the coupling region 910 to the second end 264b in a clockwise direction around the second section 905b of the circuit board 902 to form a second set of coil loops 260b. Thus, the rotational direction in which current flows when following the path from the first end 264a to the second end 264b is opposite in the two sections 905a, 905b. The height and width of the conductive traces may be similar in both the first section 905a and the second section 905b of the circuit board 902.

[0132] In the illustrated embodiment, the central portion 260c of the conductive trace is disposed in the coupling region 910 of the circuit board 902. In some embodiments, the central portion 260c of the conductive trace can be formed with a height that is less than the height of the conductive trace outside of the coupling region 910 to improve the flexibility of the conductive trace in the coupling region of the circuit board 902. If the width of the conductive trace remained constant, this reduction in height would result in an increase in the electrical resistivity of the central portion 260c of the conductive trace. To avoid or reduce this increase in electrical resistivity, the central portion 260c of the conductive trace may be formed with a width that is greater than the width of the conductive trace outside of the coupling region 910, as illustrated in FIG.

[0133] The current propagating from the first end 264a of the coil 260 through the conductive trace will proceed counterclockwise through the first set of coil loops 260a that spiral around the first section 905a of the circuit board 902. The current will then pass through the central portion 260c of the conductive trace and across the coupling region 910 to the second section 905b of the circuit board 902. In the second section 905b of the circuit board 902, the current will propagate clockwise through the second set of coil loops 260b toward the second end 264b of the conductive trace. In other words, due to the illustrated conductive trace layout, the direction of current propagation through the second set of coil loops 260b is opposite to its direction of propagation through the first set of coil loops 260a when the circuit board 902 is in an unfolded configuration. Both sets of coil loops 260a, 260b spiral radially outward in the same direction, e.g., counterclockwise, from their respective ends 264a, 264b of the conductive traces, but current through the conductive traces propagates from the corresponding end 264a through one set of coil loops 260a to the central portion 260c, and from the central portion 260c through the second set of coil loops 260b toward the corresponding end 264b.

[0134] 9D, when the circuit board 902 is in an unfolded configuration, a current propagating from the first end 264a of the conductive traces through the first set of coil loops 260a will induce a magnetic field (taking into account conventional current flow and the right-hand rule) that is directed out of the page. In contrast, the same current propagating through the second set of coil loops 260b toward the second end 264b of the conductive traces will induce a magnetic field that is directed into the page. However, when the circuit board 902 is folded at the coupling region 910 to place the first and second sections 264a, 264b in a configuration in which they are stacked directly one on top of the other, the magnetic fields induced by this current in the first set of coil loops 260a and the second set of coil loops 260b will align in a manner that is consistent with one another. Thus, when the circuit board 902 is in the folded configuration, the magnetic fields induced by the currents passing through the first set of coil loops 260a and the second set of coil loops 260b are constructive rather than destructive.

[0135] The technique exemplified by the coil configuration shown in FIG. 9D can be used to increase the sensitivity of the coil 260 by allowing a greater number of loops than can be formed in an individual section 905 of the circuit board 902.

[0136] As an alternative to the folded circuit board 902, 904 illustrated above by Figures 9B, 9C, the circuit board 900 may alternatively be stacked. In particular, Figures 9E-9G illustrate top perspective views of a stacked circuit board with an upper level, a middle level, and a lower level in an exploded configuration (Figure 9E) and a stacked configuration (Figure 9F). Each of the upper level, middle level, and lower level are bonded together at individual pads 912 as illustrated by Figure 9G. In an embodiment, these individual pads 912 are connected to each other by conductive epoxy beads.

[0137] 10A is a top view of an example embodiment of an airtight seal 288 between components that make up the housing 280 of the intraocular physiological sensor implant 200. As previously discussed, the housing 280 may consist of a bottom faceplate 282 and a top cover 284. The airtight seal 288 may be provided at mating surfaces around the periphery of these housing parts.

[0138] In some embodiments, the hermetic seal 288 is formed by welding, soldering, or brazing the faceplate 282 and top cover 284 together at their mating surfaces. This can be accomplished, for example, by providing one or more layers of soldering material at the mating surfaces and melting the soldering material using a heat source. The solder material can be a metal with a low melting point, such as tin or indium, or a metal with a higher melting point, such as gold or aluminum. Alternatively, the solder can be a mixture or alloy of two or more metals that have a lower melting point than either of the individual metals in their pure form, such as gold-tin solder, indium-tin solder, indium-silver solder, tin-silver-copper solder, or other related materials. The solder can be a eutectic system in which the ratio of two or more metals in its composition is such that the melting point of the solder has a local melting point minimum compared to the ratio of the surrounding metals in the system, such as gold-tin at an 80-20 percent weight ratio. In some embodiments, the soldering material may be provided on the faceplate 282 or top cover 284, or both components so as to be integral therewith, or may be provided as a separate preform component that is placed between the two pieces during assembly, or may be applied as a paste to the sealing location during assembly.

[0139] It may be advantageous to use a localized heat source to melt the soldering material to avoid thermal damage to the internal components of the sensor implant 200 when sealing the housing 280. In some embodiments, a reactive nanoscale multi-layer stack can be used as the localized heat source in a process called reactive bonding. In some embodiments, a laser welding or laser assisted diffusion process is used to bond an unmetallized glass housing directly to an unmetallized silicon faceplate. Additionally, a laser process can be used with a solder or other metallized interlayer between the silicon faceplate and the housing.

[0140] 10B is a cross-sectional view of an example embodiment of a hermetic seal 288 between the faceplate 282 and the top cover 284 of the housing 280 for the intraocular physiological sensor implant 200. The hermetic seal 288 can comprise, for example, an upper and / or lower layer of soldering material 1014. The upper layer of soldering material 1014 can be applied or bonded to a mating surface of the top cover 284, while the lower layer of soldering material 1014 can be applied or bonded to a mating surface of the faceplate 282. A reactive nanoscale multilayer stack can be formed adjacent to the upper layer of soldering material 1014 on either the top cover 284 or the faceplate 282 such that a nanoscale reactive multilayer stack (RMS) is provided between the layers of soldering material 1014 when the two housing components are joined. Alternatively, the RMS may be provided directly on either the top cover 284 or the faceplate 282 without the soldering material. Alternatively, the RMS and / or soldering material 1014 may be provided as separate preform components that are placed between the top cover 284 and the faceplate 282 during assembly. The reactive nanoscale multilayer stack may comprise alternating layers of a first material 1010, e.g., aluminum, and a second material 1012, e.g., nickel. Numerous other RMS systems are possible with various metal combinations such as Ti / Al, Pd / Al, Zr / Si, Pd / Sn / Pd / Al, or other related metal combinations. The number of layers may range from a few to several dozen to hundreds, with each layer being on the order of a few nanometers thick. When energy, e.g., from a laser, is applied to the reactive nanoscale multilayer stack, a self-propagating, exothermic chemical reaction ensues. This chemical reaction results in intermixing between the alternating layers of the first material 1010 and the second material 1012. The heat generated by the reaction causes the solder material to melt and bond to the reacted nanoscale multi-layer stack to form a localized metallurgical bond. The reaction propagates forward through the reactive nanoscale multi-layer stack until it is across the entire perimeter of the housing 280.By materializing a reactive nanoscale multi-layer stack, the heat generated is localized and of very short duration, thus avoiding unwanted temperature exposure to the battery or other temperature sensitive components, and also reduces bond stresses due to CTE mismatch between the top cover 284 and faceplate 282 since only the immediately adjacent material around the bond is heated during the bonding process.

[0141] Because the battery 230 is temperature sensitive, as well as due to intrinsic stresses caused by the CTE mismatch between the top cover 284 and the faceplate 282, preferred bonding techniques include low temperature bonding and / or localized heating to avoid excessive heat exposure to the internal components of the sensor 280 and / or intrinsic stresses in final assembly. One preferred embodiment that allows for low temperature bonding includes metallization at the periphery of the top cover 284 with gold, or gold and tin, or another metal, and metallization at the faceplate 282 with gold, or gold and tin, or another metal as well. By way of example, gold and tin are beneficial due to their low creep and high stiffness. In various alternative embodiments, soldering is accomplished using a method of localized heat delivery, for example, using a hot air gun or thermal conduction fuser to rapidly provide heat to melt the layers and perform an airtight seal between the top cover 284 and the faceplate 282 without using high concentrations of electricity or heat to damage the internal components. In another embodiment, as illustrated by Figs. 10C, 10D, a current is passed through the resistive material to generate enough heat to melt the layer. For example, a current may be passed through the seal itself, which causes the seal to act as an intrinsic resistive heater and melt the solder. Contacts are made at each end of the seal ring and a voltage is applied to pass current through the seal on both sides. Special care can be taken in locating the current entry and exit locations to the seal ring to ensure that the current paths on each side of the seal ring are resistively symmetric so that heating is uniform on both sides. The seal material heats up and the solder melts. In a particular example, AuSn solder is deposited on the faceplate and / or housing, and Au is deposited on both components, e.g., the housing and the faceplate, whereby Au acts as a barrier on either side of the AuSn solder. Additional metal layers, e.g., Ti, Ta, Pt, W, or others, can be included as additional barrier layers. Current can flow through either component, for example through the connecting gold pads illustrated in FIG. 10D.In these various embodiments, providing localized heat limits the total heat in the system, thus avoiding the risks associated with using global heating methods to damage sensitive components such as the battery 230. It should be understood that other localized low temperature couplings can achieve this goal.

[0142] FIG. 11 illustrates an example embodiment of the faceplate 282 and top cover 284 of the housing 280 for the intraocular physiological sensor implant 200. In the illustrated embodiment, the top cover 284 includes a protruding lip 289 adjacent the airtight seal 288. The faceplate 282 can also include a protruding lip 289. The protruding lip of the faceplate 282 can be adjacent the airtight seal 288 or somewhere else, such as near its bottom surface as illustrated. In some embodiments, the protruding lip 289 extends outwardly at least 5 μm. The protruding lip 289 can be advantageous because it can help protect the airtight seal 289 from being damaged by tweezers or other tools when handling the housing 280 of the sensor implant 200 prior to or during surgical implantation. For example, when using tweezers to grasp the side of the housing 280, the tweezers contact the lip 289 rather than the airtight seal 288. In an embodiment, the bottom of the faceplate 282 includes chamfered or rounded edges that may advantageously lower the risk of injury sometimes associated with sharper edge features. This is unique because Si is brittle and often difficult to manufacture with rounded features such as chamfers.

[0143] In some embodiments, after the faceplate 282 and top cover 284 are sealed together, a thin film coating can be applied to the entire housing 280 of the intraocular physiological sensor implant 200. The thin film can be, for example, titanium dioxide. The thin film coating can be applied using atomic layer deposition (ALD) techniques. For example, alternatively, the housing 280 can be exposed to various gas phase precursor species. In embodiments, the thin film ALD coating includes a multi-layer stack of various materials. For example, the various layers in the multi-layer stack could include titanium oxide, titanium dioxide, aluminum oxide, aluminum dioxide, hafnium oxide, or any of other related oxides. In embodiments, the multi-layer stack includes up to 50 layers. However, it should be understood that more layers, fewer layers, and different materials are contemplated by the ALD coatings disclosed herein. Each of the separate precursor species can react with the surface of the housing 280 in a self-limiting manner such that the reaction terminates when all reactive sites on the surface are filled. The reaction of each precursor species can deposit a monolayer on the surface of the housing 280. By sequentially exposing the housing 280 to different precursor chemical genus, the complete crystalline structure can be built up layer by layer.

[0144] The thin film ALD coating can be a conformal layer of titanium dioxide crystals without pinholes. Such an ALD coating can provide several advantages. It can act as an additional hermetic seal to help prevent aqueous humor from entering the housing 280. By covering any exposed edges of the hermetic seal 288, the ALD coating can help prevent aqueous humor from reacting with metals from the metal seal and dissolving or reacting with them to create corrosion, as well as preventing the metals in the hermetic seal from leaching into the patient's eye.

[0145] Additionally, the ALD coating can protect the housing 280 from dissolving in aqueous humor over time if the material used to make the housing is water soluble in any way. As already discussed, some embodiments of the faceplate 282 and flexible diaphragm 216 of the capacitive pressure sensor 210 are formed of silicon. This can be advantageous since there are many known manufacturing processes for creating microscopic structures from silicon. However, uncoated silicon dissolves in the body at a rate, e.g., 1-2 microns per decade, that can result in appreciable thickness loss over the life of the sensor implant 200. In some embodiments, the flexible diaphragm 216 may only be approximately 5 μm thick at the time of manufacture. Thus, dissolution of the flexible diaphragm 216 will result in long-term thickness loss of the flexible diaphragm 216 that can significantly alter its mechanical performance. This makes it necessary to periodically recalibrate the capacitive pressure sensor 210. However, an ALD coating on flexible diaphragm 216 could dramatically slow down the rate of dissolution or prevent dissolution altogether, thereby helping to avoid the need for periodic recalibration of capacitive pressure sensor 210. The ALD coating itself can be applied in a low stress manner, so that its presence does not significantly affect the mechanical performance of flexible diaphragm 216.

[0146] The ALD coating may be relatively soft and therefore prone to damage during surgical implantation of the sensor implant 200. Thus, the protective lip 289 shown in Figure 11 may advantageously protect the coating over the airtight seal 288. Additionally, the fact that the flexible diaphragm 216 is disposed within a recess in the faceplate 282 (as discussed with respect to Figure 7B) may advantageously protect the coating over the flexible diaphragm.

[0147] <Wearable devices and data acquisition> In a preferred embodiment, the sensor implant 200 autonomously records all data measured by the physiological sensor 210 and stores this data in the measurement memory 240. The data may be recorded and stored at regular intervals, for example every 15 minutes, to optimize power consumption from the battery 230. The recorded data is stored in the measurement memory 240, but the recorded data is occasionally transmitted to an external reader for subsequent processing and analysis. For example, as described above, the transceiver / receiver 250 and coil 260 may wirelessly transmit the pressure measurements stored in the measurement memory 240 to an external reader, such as glasses worn by the patient. The glasses may advantageously ensure that an external reader for receiving the pressure measurements, for example an antenna and / or coil on the glasses, is located close to the sensor implant 200. In an embodiment, the glasses communicate with the sensor implant 200 by inductive coupling.

[0148] Furthermore, once the pressure measurements are received at the glasses, the glasses may then communicate these pressure measurements to an additional external reader, such as a wearable watch. In various embodiments, the glasses communicate with the wearable watch by Bluetooth, WiFi, Zigbee, or other related wireless communication. In addition to receiving the pressure measurements from the sensor implant 200 and other data such as battery voltage, temperature measurements, etc. by the glasses, the wearable watch may communicate with the sensor implant 200 directly or with other physiological sensors and / or obtain physiological measurements directly. The wearable watch may measure physiological parameters of the patient, such as heart rate, blood pressure, pulse oxygen saturation measurements, etc. The wearable watch may further measure environmental factors such as air pressure, temperature, etc. The wearable watch may associate these environmental factors with a particular pressure measurement for sensor calibration purposes or to identify data outliers. The additional external reading device disclosed herein is in one embodiment a wearable wristwatch, but it should be understood that other devices, e.g. bracelets, any other wearable electronic device, cell phone, tablet, e-reader, laptop, etc. are envisioned to communicate directly with the glasses or sensor implant 200. In alternative embodiments, a handheld reading device could also be used for communication instead of the glasses. Typically, the glasses (or handheld reading device) communicate directly with the implant via an inductive link, and the wearable device, e.g. a wristband, communicates with the glasses via Bluetooth. However, from the patient's perspective, the wristband appears to be communicating directly with the implant. Thus, all patient interaction is through the wristband, which may include a screen, UI capabilities, etc. This configuration is advantageous since it only requires Bluetooth capabilities on the wristband. For example, the wristband does not require high power radio frequency communication, coils, etc. These features are provided with the glasses.

[0149] Besides data transmission, the glasses are further configured to charge the physiological sensor 200. For example, the coil 260 may receive wireless power from the glasses by inductive coupling to charge the battery 230 while the stored measurements are downloaded to the glasses. A wireless charging device may be integrated into the glasses. The coil 260 may transmit measurement data and receive power to repeatedly charge the battery 230 simultaneously or one after the other (in either order). In some embodiments, the coil 260 comprises a number of conductive loops oriented with their axes generally aligned with the optical axis of the eye. This orientation may allow a relatively larger amount of electromagnetic flux to pass through the conductive loops after being transmitted from the glasses.

[0150] Ideally, charging the physiological sensor 200 takes roughly 30 minutes and is performed once a week. In various embodiments, the glasses are configured to perform additional functions beyond charging and data transmission. For example, the glasses could include a fundus camera that takes pictures of the patient's optic nerve, for example along the edge of the glasses or as a clip-on or snap-in module that can be temporarily attached to the glasses when charging. These pictures, taken at regular intervals, such as when the physiological sensor 200 is charged weekly, are useful for clinicians to identify visual field reduction. Because glaucoma affects the optic nerve and it is this particular area of ​​the retina, and not the entire retina, that is most important in monitoring the progression of glaucoma, it is possible to achieve a fundus image suitable for this purpose without necessarily enlarging the pupil of the eye. Alternatively or additionally, the glasses could include a light that can perform a peripheral vision test for the patient, either along the edge of the glasses or as a clip-on or snap-in module that can be temporarily attached to the glasses. A peripheral vision test typically involves a series of flashes of light that are placed at different locations in the patient's visual field. This test could be done with glasses that have integrated LEDs in various locations, or fiber optic pipes that create many configurations of points of light that the patient can see but that are delivered from LEDs located elsewhere in the frame of the glasses. Similar to fundus imaging, peripheral vision testing performed at regular intervals, such as at weekly charging times, is useful to clinicians to identify the rate of peripheral vision decline. Fundus imaging and peripheral vision testing are performed on an infrequent basis for glaucoma patients, and thus the described home testing system would provide medical professionals with orders of magnitude more data than is currently provided. This is particularly important for visual field tests that, like IOP measurements, exhibit an extreme amount of variability, or noise, in typical patient data. The collection of more data, especially much more than is provided by current standards of care, followed by averaging and trend analysis, is an effective strategy to improve reliability in the analysis of data sets that inherently have a large degree of variability.

[0151] As mentioned above, data may be recorded at regular intervals and stored in the measurement memory 240. However, if the battery 230 runs out of power or fails, the physiological sensor 200 may transition to an on-demand mode. In the on-demand mode, the physiological sensor 200 stops recording measurements at intervals. However, the sensor 200 may be powered up at any time, for example by the glasses charging described above, thereby recording and transmitting live pressure measurements in an on-demand manner. In particular, for example, a user may power up the physiological sensor 200 via the glasses, which then receive live pressure measurements directly from the physiological sensor 200. The live pressure measurements are then communicated from the glasses to a wearable watch as disclosed above.

[0152] <Pressure Calibration> FIG. 12A is a graph 1200 of atmospheric pressure measured by a barometer worn by a user. Signal 1202 shows the variation in atmospheric pressure over a period of approximately 140 hours. FIG. 12B shows an enlarged portion 1204 of signal 1202 from time 60 to time 80. During this period, signal 1202 shows that atmospheric pressure typically changed relatively slowly over time, most likely due to normal changes in weather conditions. An example of this type of relatively slow weather-induced variation over time is shown by signal 1202 from time 69 to time 73. However, signal 1202 also shows that there were sudden, relatively large amounts of change that also occurred. Examples of these types of sudden, large changes in measured atmospheric pressure are seen in signal 1202 at approximately time 63 (i.e., between 62-63 on the graph), time 68 (i.e., between 67-68 on the graph), time 75 (i.e., between 74-75 on the graph), and time 77 (i.e., between 76-77 on the graph). These sudden, large changes in atmospheric pressure may have been the result of changes in altitude experienced by the user while he or she was driving uphill or downhill, traveling between different floors of a building, etc.

[0153] Because relatively large changes in atmospheric pressure such as these can occur in a relatively short period of time, care should be taken when correlating atmospheric pressure measurements with absolute IOP measurements to calculate a gauge IOP value. If the external and internal pressure measurements are too far apart in time from one another, the gauge IOP value derived from these two measurements can be significantly affected by one of these sudden, large changes in atmospheric pressure, thus reducing the accuracy of the gauge IOP value.

[0154] This difficulty in correlating the internal absolute IOP measurements with the external atmospheric pressure measurements may be exacerbated if there is some amount of drift over time in the accuracy of the respective time keeping devices used by the external pressure measurement device and the implanted pressure measurement device. For example, as shown in FIG. 2B, an IOP sensor implant may include a time keeping device, e.g., a timer or clock, used to indicate the time when pressure measurements should be taken. Design constraints may favor or require the use of relatively simple timer or clock circuits. For example, cost, power consumption and / or circuit size constraints may favor or require the use of less advanced timers and / or clocks, e.g., those that do not include a piezoelectric resonator in the implantable sensor device. These timers and / or clocks may be less accurate than more advanced versions that require, for example, more circuit elements, a larger amount of space and / or more power in the implantable sensor device. As a result, the accuracy of the time keeping of timers and / or clocks used in implantable devices of the type described herein may drift over time. Additionally, these time keeping devices may be more susceptible to temperature fluctuations.

[0155] For example, a timekeeping drift of only 0.1% can result in relatively large errors over a period of days, weeks, or months. As a result, even if the respective timekeeping elements used by the two devices indicate that the two measurements were taken simultaneously, there can be a time lag between the atmospheric pressure measurement taken by the external device and the internal absolute IOP measurement taken by the implant in the patient's eye. And, of course, significant changes in either atmospheric pressure or absolute IOP could occur during that time lag, resulting in an inaccurate calculation of the gauge IOP value.

[0156] 12C and 12D are graphs 1210, 1220 illustrating examples of inaccurate gauge IOP calculations that can result from time misalignment between absolute IOP and barometric pressure measurements, respectively. FIG. 12C illustrates the effect of a simulated 0.1% timer inaccuracy, while FIG. 12D illustrates the effect of a simulated 1% timer inaccuracy. In both graphs 1210, 1220, the plotted gauge IOP values ​​were calculated by subtracting barometric pressure values ​​from absolute IOP values ​​at regular intervals, e.g., every hour. In these simulated examples, the absolute IOP and barometric pressure signals were designed to result in a constant gauge IOP signal of 16 mmHg. That is, both the absolute IOP and barometric pressure signals were time-varying in the same manner as shown in FIGS. 12A and 12B, but the difference between these signals (gauge IOP) was designed to be constant. If the gauge IOP values ​​had been calculated using perfectly time-synchronized absolute IOP and barometric pressure values, the plotted gauge IOP values ​​would have remained constant at 16 mmHg. However, in these simulations, time wander was introduced between the respective absolute IOP values ​​used to calculate the barometric and gauge IOP values. As shown in graphs 1210, 1220, within just a few days, the simulated timer inaccuracies resulted in a loss of synchronization between the respective absolute IOP and barometric pressure values, which in turn caused large, erroneous changes in the gauge IOP calculations. Figures 13A and 13B illustrate an example method for avoiding these types of inaccuracies.

[0157] 13A illustrates an example method 1300a for calculating a gauge IOP value using one or more barometric pressure measurements from an external device and one or more absolute IOP measurements from a sensor implant in a patient's eye. The method begins at block 1310a, where specified times and / or intervals are set for taking absolute IOP measurements using a sensor implant in the patient's eye and barometric pressure measurements using an external device. For example, both the external device and the implanted sensor device can be set (e.g., using built-in software, firmware, and / or hardware) to take measurements at or about times T1, T2, T3, ..., etc. These times can be measured independently by the external device and the sensor implant, for example, using their respective built-in time keeping devices.

[0158] As already discussed, even if the time keeping devices used by the external device and the sensor implant are initially synchronized, they may lead or lag each other due to time keeping wander and thus become out of sync. As a result, the sensor implant may actually take absolute IOP measurements at times T1±Δ1, T2±Δ2, T3±Δ3, etc. Similarly, the external device may actually take barometric pressure measurements at times T1±δ1, T2±δ2, T3±δ3, etc., where Δ n and δ n Additionally or alternatively, both the external device and the sensor implant can be set to take measurements at or about the times of the intervals I1, I2, I3, .... However, again, there can be an unknown offset between the instants in time at which the external barometric pressure measurements and the absolute IOP measurements are actually taken.

[0159] In block 1320a, the sensor implant acquires absolute IOP measurements in the patient's eye at specified times / intervals (e.g., T1, I1). The measurements are stored in an internal memory or transmitted to an external reading device. At least partially simultaneously, in block 1330a, the external device acquires multiple measurements during a window of time that may extend before and / or after the specified times / intervals (e.g., T1, I1). The length of the atmospheric pressure measurement window may be determined based on, for example, the time-keeping wander present in the sensor implant timing device and / or the time-keeping device used by the external device to measure the atmospheric pressure. The amount of time-keeping wander may identify a window of uncertainty around each specified measurement time during which measurements may be made. In some embodiments, the atmospheric pressure measurement window may be set to be at least as large as this time-keeping uncertainty window. For example, in some embodiments, the external device acquires multiple measurements during a 20-minute window of time centered on the specified times / intervals. These atmospheric pressure measurement windows are indicated in FIG. 12B by the horizontal bars 1206 centered on each hour on the hour. The number of barometric pressure measurements taken during each barometric pressure measurement window can be selected based on, for example, the length of the time window, the desired sampling rate, available memory, or other selection means. During the time window, barometric pressure measurements can be taken, for example, every second, every 10 seconds, every minute, or other time frequency.

[0160] At block 1340a, measurements taken during the barometric pressure measurement time window may be analyzed to determine the amount of variation present in the measurements. For example, the barometric pressure measurements may be analyzed to determine if the deviation between the barometric pressure measurements during the window around the specified measurement time / interval falls within a selected range (e.g., deviation ≦10 mmHg, ≦5 mmHg, ≦1 mmHg, ≦10%, ≦1%). Calculation of the variation in the barometric pressure signal may be performed according to any suitable mathematical technique, including one or more difference calculations, variance or standard deviation calculations, or other related techniques. This analysis may be performed, for example, by an external measurement device. Alternatively, the analysis may be performed by a separate processing device to which the barometric pressure measurements are uploaded. In FIG. 12B, the unshaded bars 1206a are examples where the amount of variation in measurements taken during the barometric pressure measurement window was within a selected tolerance range, while the shaded bars 1206b are examples where the amount of variation was found to be outside the selected tolerance range.

[0161] In block 1350a, if the variation in the barometric pressure measurements taken during the time window is acceptable, one or more of the barometric pressure measurements during the window may be accepted and used with the absolute IOP measurements taken with the sensor implant at the specified time / interval to calculate a gauge IOP value. For example, the barometric pressure measurement whose time is closest to the specified time / interval may be selected for use in calculating the gauge IOP value. Or, an average of all measurements during the barometric pressure measurement window may be used. Or, a representative barometric pressure value may be calculated or selected in some manner from all measurements in the barometric pressure measurement window. However, in these embodiments, a barometric pressure measurement is only accepted for calculating a gauge IOP value if the barometric pressure data is relatively stable (within defined limits that may be set based on the application or desired accuracy) over the course of the barometric pressure measurement window. In this manner, the gauge IOP value is calculated only for times when it is relatively certain that the calculated value will not be significantly adversely affected by the barometric pressure variations experienced by the user during the barometric pressure measurement window. Alternatively, the gauge IOP value could be calculated in all cases and then stored and / or presented to the user only if it meets the above criteria. Alternatively, a suspect gauge IOP value (e.g., calculated using data taken during a period when barometric pressure fluctuations exceeded some set threshold) may be presented to the user with a flag or notification that it is a suspect value. The calculation of the gauge IOP value by block 1350a may be performed, for example, by an external device to which both barometric pressure and IOP measurements are uploaded.

[0162] FIG. 13B illustrates an example method 1300b for correlating barometric pressure measurements from an external device with absolute IOP measurements from a sensor implant for purposes of determining a gauge IOP value. The method 1300b begins at block 1310b, where an external device or system used to obtain barometric pressure measurements initiates a synchronization operation by wirelessly transmitting synchronization information to a sensor implant in the patient's eye. The synchronization information may be a value, such as a timestamp or a unique correlation ID number, associated with a particular time (e.g., the current time the synchronization signal is transmitted) indicated by a timekeeping device used by the external device to determine when to obtain barometric pressure measurements. In some embodiments, the synchronization information may be wirelessly transmitted at a different frequency than that used to wirelessly power the implant and / or download data from the implant. The synchronization information may be stored by the external device in association with the time of the synchronization operation indicated by its internal clock or timer. The synchronization information may be stored along with the barometric pressure measurements, which may also be stored in association with the time of acquisition indicated by an internal clock or timer.

[0163] In some embodiments, the synchronization information is transmitted at predetermined times and / or intervals by the external device. In some cases, the user may be prompted to interact with the external device to initiate the synchronization operation. In some embodiments, the external device used to obtain the barometric pressure measurements may be an item designed to be worn on the wrist, such as a watch. The external device may output an alarm or other prompt to remind the user to perform the synchronization operation. The synchronization operation may require the user to bring the external device closer to his or her eye so that the sensor implant can more easily receive the synchronization information. In some embodiments, the external device may transmit the synchronization information using a transmission power that is high enough so that the user does not need to bring the external device closer to his or her eye. In such embodiments, the external device may be located on the patient's body, for example on the user's wrist or around the user's neck, or even close to the user, such as in the same room, so that the user does not need to bring the external device very close to his or her eye.

[0164] At block 1320b, the sensor implant receives the synchronization information and associates it with a current time as indicated by an internal time keeping device (e.g., a clock or timer). The sensor implant may then store the synchronization information with the associated time of the synchronization operation. The synchronization information may be stored along with the absolute IOP measurement, which is also stored in association with the time it was taken as indicated by the sensor implant's internal time keeping device.

[0165] Next, in block 1330b, the sensor implant obtains absolute IOP measurements in the patient's eye at the designated measurement times / intervals. At least partially simultaneously, in block 1340b, the external device obtains one or more barometric pressure measurements at and / or about the designated measurement times (e.g., as discussed with respect to FIG. 13A).

[0166] After the absolute IOP and barometric pressure measurements are obtained, both can be uploaded to a processing device along with the synchronization information stored by each of the two devices. The processing device can then correlate one or more absolute IOP measurements with one or more barometric pressure measurements based on the synchronization information in block 1350b. As previously described, the synchronization information received from the barometric pressure measurement device is associated with the time indicated by its time management device when the synchronization operation was performed. Similarly, the synchronization information received from the sensor implant is associated with the time indicated by its time management device when the synchronization operation was performed. Thus, the synchronization information can be used to identify one or more barometric pressure measurements taken at the same or approximately the same time (e.g., within minutes or, more preferably, within seconds of each other) as the absolute IOP measurement from the sensor implant. The processing device can then calculate a gauge IOP value in block 1360b using the correlated absolute IOP and barometric pressure measurements. In other embodiments, the implant need not necessarily include a time management device, but may instead rely on receiving a wireless signal from an external device to initiate an IOP measurement. The external device could take an atmospheric pressure measurement at or near the time of transmitting this wireless signal (eg, within 1 second, or within 10 seconds, or within 60 seconds).

[0167] In some embodiments, absolute IOP measurements can be correlated with each simultaneous barometric pressure measurement by using signal processing techniques, such as pattern correlation. For example, a signal consisting of absolute IOP measurements taken over time and a signal consisting of barometric pressure measurements taken during at least partially overlapping time periods can be analyzed according to known signal processing techniques (e.g., autocorrelation, feature extraction algorithms, or other processing techniques) to identify signal features, such as peaks, patterns, etc. Once matching features are identified in both signals, the time of one of the signals can be shifted relative to the other (e.g., by the time offset between the matching features) to correlate the simultaneously taken absolute IOP measurements with the barometric pressure measurements. These simultaneous measurements can then be used to calculate a gauge IOP value. This method could be applied in addition to other synchronization methods (e.g., those discussed with respect to Figures 13A and 13B).

[0168] In some embodiments, an external device, such as one used to measure atmospheric pressure, can issue a control signal to the IOP detection implant that causes the implant to obtain an absolute IOP measurement. The external device can obtain the atmospheric pressure measurement substantially simultaneously with the control signal so that the absolute IOP measurement and the atmospheric pressure measurement are obtained sufficiently simultaneously to avoid substantial errors in the calculation of the gauge IOP value. In some such embodiments, the external device can prompt the user to initiate the absolute IOP measurement and the atmospheric pressure measurement at a designated time. For example, the external device may provide an indication, such as an alarm, that reminds the user to begin the measurement at the designated time. To begin the measurement, the user may, for example, activate a button, switch, or other feature on the external device. This action may 1) initiate the atmospheric pressure measurement and 2) initiate a control signal from the external device to the implanted IOP detection implant. As just discussed, this control signal may be used to cause the IOP detection implant to obtain an absolute IOP measurement. In such an embodiment, the control signal may include or consist of a unique correlation ID number, or other unique identification characteristic as previously described herein, that allows for proper correlation of measurements between the IOP detection implant and the external device even if the control signal is not properly received by the IOP detection implant. The external device may be provided in the kit with information indicating that the user should bring the external device closer to his or her eye when performing this operation to improve communication of the control signal to the IOP detection implant.

[0169] In some embodiments, the IOP detection implant may include a low-power clock (which may be relatively inaccurate) to initiate a ready state in which the implant can receive a signal from an external device. For example, the low-power clock may cause the implant to enter this ready state during a time window in which it is expected to receive a signal from the external device, such as those described herein (e.g., synchronization signals, control signals, etc.). This period may be, for example, a 1-minute, 5-minute, 10-minute, 30-minute, or 60-minute window around the time a signal is expected from the external device. This approach may be beneficial because it may allow the use of wireless signals rather than signals sent by inductive coupling. Wireless signals travel farther but may lack the power required to wake the implant from a dormant state. To use wireless signals, the IOP detection implant typically needs to have a radio circuit that is powered on and ready to receive a signal. It may be advantageous to use a low-power clock to shut down the radio circuit except for the ready period in which a signal is expected from the external device. In some embodiments, the low-power clock may be synchronized to a precise time by the external device at various intervals (e.g., during charging or data download interactions).

[0170] <Power supply> The various IOP detection implants described herein can include one or more power sources that provide operating power for various components of the IOP detection implant. In some embodiments, the IOP detection implant can include two separate power sources of different types. The first power source can be, for example, a battery, and the second power source can be, for example, a capacitor or a supercapacitor. These separate power sources can collectively provide operating power for the IOP detection implant.

[0171] Although batteries can hold much larger amounts of energy than capacitors, capacitors offer the advantage of being able to be recharged very quickly, e.g., within a matter of seconds. This property is particularly advantageous for supercapacitors, which have a relatively large energy storage capacity compared to other types of capacitors. Supercapacitors can store energy per unit volume or mass that is one to two orders of magnitude more than, e.g., electrolytic capacitors. Unlike the solid-state dielectrics used by other capacitors, supercapacitors may also use, e.g., electrostatic double-layer capacitance and / or electrochemical pseudocapacitance to store energy. Some energy storage devices may have a combination of physical, chemical, or behavioral properties that make their classification as batteries, capacitors, or supercapacitors somewhat ambiguous. In some embodiments, supercapacitors may be considered to have a storage capacity per unit volume or mass that is one to two orders of magnitude less than batteries, as well as the ability to be fully charged in a relatively short time, e.g., within 1 to 10 seconds, by applying an appropriate voltage.

[0172] The IOP detection implant may include a circuit with separate physical connections to the battery and the supercapacitor, e.g., a pair of pads for each power source. The circuit may also include a third, separate pair of pads for an induction coil. When an external induction field is present, the circuit may generate a source current that causes both the supercapacitor and the battery to be energized and charge both. The voltage may remain energized while the external induction field is present (the supercapacitor charges to its voltage relatively quickly, while the battery continues to draw current for a longer period of time). The supercapacitor and the battery may be connected in parallel to the same charging circuit and have the same charging voltage. This configuration may be advantageous since it does not require a complex charging circuit. However, in other embodiments, there could be two different charging circuits, one that charges the supercapacitor and another that charges the battery (possibly at different voltages and / or currents).

[0173] For discharging, in some embodiments, the supercapacitor and the battery are not connected in parallel. Instead, the IOP detection implant may receive power from the supercapacitor until it runs out of charge, and then the implant may switch to using the battery. Alternatively, the supercapacitor may be used to charge the battery (while the battery powers the implant). This approach may result in energy loss when charging the battery, but may be an advantageous approach, for example, if the self-discharge rate of the supercapacitor is high.

[0174] 14A is a graph 1400a showing the power usage of an exemplary IOP detection implant when the implant is powered by a battery (i.e., signal 1402) and separately when the implant is powered by a supercapacitor (i.e., signal 1404). Signal 1402 illustrates a first case in which the IOP detection implant is powered only by a battery. In this example, the IOP detection implant is assumed to use 1 nAh of electrical energy per hour and the battery is assumed to have a usable storage capacity of 1 μAh. As shown by signal 1402, the plotted remaining power capacity starts at 1 μAh and decreases linearly at a rate of 1 nAh per hour until all of the energy stored in the battery is exhausted after approximately 41 days.

[0175] Meanwhile, signal 1404 illustrates a second case where the IOP detection implant is powered only by a supercapacitor. When the IOP detection implant is at least partially powered by a supercapacitor, the IOP detection implant may be part of a system designed to prompt the patient with the IOP detection implant to perform charging interactions or to perform more frequent charging interactions. In such an embodiment, an external charging device may be provided to wirelessly charge the IOP detection implant. Wireless power transmission from the external device to the IOP detection implant may be performed using electromagnetic energy, such as radio frequency (RF) energy, infrared (IR) energy, and the like. The electromagnetic energy may be transmitted, for example, by inductive coupling, propagating waves, and the like. The external charging device may include, for example, a charging power source, a transmitter, and a coil or inductive coupling element. The IOP detection implant may similarly include a coil or inductive coupling element to receive power from the external charging device.

[0176] Additionally, the external charging device may also include an output device, such as a speaker, a display, a tactile transducer, or other related components. The output device may be used by the external charging device to prompt the patient to perform a charging interaction with the IOP detection implant. Such prompts may be provided at regular intervals, such as daily, every 12 hours, weekly, etc. Alternatively, the prompts may be provided at irregular intervals based on some criteria, such as when the supercapacitor has a predetermined percentage of remaining power capacity. The prompts may take the form of an audible cue, such as an alarm. In other embodiments, the prompts may be a visible cue, such as a particular symbol or sentence on a display. In yet other embodiments, the prompts may be in some other form, such as a tactile cue.

[0177] The charging interaction prompt may be simultaneous with the timer synchronization prompt and / or the data download prompt. In such an embodiment, the use of a supercapacitor power source may have a synergistic effect since the user may already be required to perform regular timer synchronization interactions due to drift in the IOP detection implant's built-in timekeeping as discussed herein, and / or data download due to storage capacity limitations, for example, using inductive coupling. These interactions may also be utilized to charge the supercapacitor. Thus, it may be possible to eliminate or reduce the frequency and associated inconvenience of battery recharging, which may otherwise require 30-45 minutes of wearing a special charging device.

[0178] The charging interaction itself may take a variety of forms. For example, the patient may be asked to operate a control on the external charging device, such as a button, switch, or other relevant feature. Operating the control may cause the external charging device to initiate a wireless transfer of power from the external charging device to the IOP sensing implant. The control may also initiate synchronization of a timekeeping device, downloading of data from the IOP sensing implant, etc., as discussed elsewhere herein.

[0179] In some embodiments, the external charging device may include or be accompanied by instructions informing the user that he or she should bring the external charging device close to his or her eye as part of the charging interaction. Increasing physical proximity between the external power charging device and the IOP detection implant generally improves power transfer to the implant. In some embodiments, the external charging device may provide repeated or constant prompts until it detects that the user has performed the charging interaction. Because the power source is a supercapacitor, the charging interaction takes only a few seconds or less, making it practical to perform frequent charging interactions.

[0180] In some embodiments, the external charging device may be set to provide a charging prompt during an interval of time during which the predicted energy usage of the IOP detection implant is less than the storage capacity of the supercapacitor. For example, in the case illustrated by signal 1404, the IOP detection implant is expected to use 1 nAh of electrical energy per hour, and the supercapacitor is expected to have an available storage capacity of 0.2 μAh. Thus, the supercapacitor can provide enough energy to power the IOP detection implant for several days. As long as the external charging device prompts the user to perform a charging interaction with the IOP detection implant (and assumes that the user actually performs the prompted charging interaction) at intervals shorter than this predicted operating time, the IOP detection implant can operate continuously. For example, signal 1404 indicates that a charging interaction is prompted (and generally performed) every day. However, even if the patient ignores the charging interaction prompts for a few days at a time (indicated by larger teeth in the sawtooth signal waveform 1404), the IOP sensing implant can still operate continuously because the supercapacitor can store enough energy at one time to power the device for a few days. The expected energy usage of the IOP sensing implant can be determined in a variety of ways, including experimentally during typical usage scenarios, or analytically relative to the rated power usage of the various components of the sensing implant.

[0181] FIG. 14B is a graph 1400b showing the power usage of an exemplary IOP detection implant powered by a combination of a battery and a supercapacitor, where the capacity of the supercapacitor is less than the power usage of the implant during the charge interaction time. In the example illustrated by signal 1408, the IOP detection implant consumes 1 nAh of power per hour, but the battery has a storage capacity of 0.5 μAh and the supercapacitor has a storage capacity of 0.02 μAh. As just described with respect to FIG. 14A, the IOP detection implant may be part of a system with an external charging device that occasionally prompts the patient to perform a charge interaction to charge the supercapacitor. (As described above, the charge interaction prompt may be used or be simultaneous as a timer synchronization prompt and / or a data download prompt.) In the example illustrated by signal 1408, the external charging device outputs a charge interaction prompt every day, and thus the supercapacitor is recharged every day as long as the patient follows the prompt. This is evident from the 0.02 μAh sawtooth pattern evident in signal 1408 where the supercapacitor is charged and then the remaining capacity drops until it is recharged once more. The 0.02 μAh storage capacity in this example of the supercapacitor is slightly less than the 0.024 μAh energy usage expected during the daily charge interaction time by the IOP detection implant.

[0182] For comparison purposes, FIG. 14B also includes signal 1406 illustrating the case where an IOP detection implant is powered only by a battery with a storage capacity of 1 μAh (twice the storage capacity of the battery represented by signal 1408). As shown by signal 1406, this battery capacity is sufficient to power the IOP detection implant for approximately 41 days. However, despite the fact that the battery corresponding to signal 1406 has twice the capacity of the battery corresponding to signal 1408, the IOP detection implant corresponding to signal 1408 can operate approximately three times longer than the IOP detection implant corresponding to signal 1406. This is due to the presence of a supercapacitor in combination with regular or daily charging interaction. This example illustrates the synergistic effect that can be realized by using a relatively small capacity supercapacitor together with a battery to provide operating power to an IOP detection implant.

[0183] 14C is a graph 1400c showing the power usage of an exemplary IOP detection implant powered by a battery and supercapacitor combination, where the capacity of the supercapacitor is greater than the power usage of the implant during the charge interaction time. In the example illustrated by signal 1412, the IOP detection implant once again consumes 1 nAh of power per hour, but the battery has a storage capacity of only 0.3 μAh and the supercapacitor has a storage capacity of 0.1 μAh. Once again, the IOP detection implant may be part of a system with an external charging device that occasionally prompts the patient to perform a charge interaction to charge the supercapacitor. In the example illustrated by signal 1412, the external charging device outputs a charge interaction prompt every day, so that the supercapacitor is generally recharged daily, although it is acceptable for these charge interactions to be skipped occasionally.

[0184] For comparison purposes, FIG. 14C also includes signal 1410 illustrating the case where the IOP detection implant is powered only by a battery with a storage capacity of 1 μAh (more than three times the storage capacity of the battery represented by signal 1412). As shown by signal 1410, this battery capacity is sufficient to power the IOP detection implant for approximately 41 days. In contrast, the IOP detection implant corresponding to signal 1412 can operate for a much longer period because the supercapacitor can provide all of the necessary operating power for the entire period between scheduled charging interaction prompts. As long as the patient follows these prompts and performs the charging interaction, no battery power is needed. However, if the patient is unable to follow one or more of the charging interaction prompts, the battery is available to provide backup power.

[0185] FIG. 15 is a flow chart illustrating a method 1500 for providing operating power to an IOP detection implant. The method 1500 starts at block 1510, where a battery and a supercapacitor are provided within the IOP detection implant to provide operating power for the implant. At block 1520, an external charging device is provided. At block 1530, the external charging device is configured to prompt the patient to initiate a charging interaction between the external charging device and the IOP detection implant. Finally, at block 1540, the external charging device wirelessly transmits power, for example, to the supercapacitor within the IOP detection implant when the charging interaction is initiated. As previously discussed, the charging interaction can be prompted by the external charging device, for example, at regular intervals or based on the satisfaction of some criteria.

[0186] Various embodiments of implantable physiological sensors and related methods have been described herein with various features. Not all embodiments are illustrated with all features, but it should be understood that the features described herein can be freely combined with the various embodiments described and illustrated. The various physiological sensors described herein can have any of the features, characteristics, elements, etc. disclosed in connection with the sensor devices described in the following U.S. patent documents: U.S. Pat. No. 6,981,958; U.S. Pat. No. 7,678,065; U.S. Patent Application Publication No. 2010 / 0056979; and U.S. Patent Application Publication No. 2010 / 0106073, each of which is incorporated herein by reference in its entirety. Furthermore, the various physiological sensors described herein can be used in any of the methods or applications described, for example, in the above patent documents.

[0187] The various exemplary devices, logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be embodied as electronic hardware, such as, for example, analog and / or digital circuitry, computer software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, the various exemplary components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is embodied as hardware or software depends on the particular application and design constraints imposed on the overall system. The described functionality may be embodied in various ways for each particular application, and such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0188] Some of the various example logic blocks, modules and circuits described in connection with the embodiments disclosed herein may be embodied or implemented using general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

[0189] The embodiments have been described in conjunction with the accompanying drawings. However, it should be understood that the figures are not necessarily drawn to scale. Distances, angles and other dimensions are merely exemplary and do not necessarily bear precise relationship to the actual dimensions and layout of the illustrated devices. Moreover, the above embodiments have been described with a level of detail that will enable one skilled in the art to make and use the devices, systems and methods described herein. A wide variety of variations are possible. Components, elements and / or steps can be changed, added, deleted or rearranged. Although certain embodiments have been explicitly described, other embodiments will be apparent to those skilled in the art based on this disclosure. The scope of the particular inventions disclosed herein is indicated by the appended claims, rather than by the above description. All changes that come within the meaning and range of equivalence of the claims are embraced within their scope.

Claims

1. A physiological sensor; a housing comprising a faceplate and a cover, the physiological sensor being integrated with the faceplate; at least one protruding anchor configured to penetrate the trabecular meshwork; 1. An intraocular implant comprising: the at least one protruding anchor includes an internal channel. Intraocular implants.

2. The intraocular implant of claim 1 , wherein the physiological sensor comprises an intraocular pressure sensor.

3. The intraocular implant of claim 2 , wherein the intraocular pressure sensor comprises a capacitive pressure sensor.

4. The intraocular implant of claim 3 , wherein the capacitive pressure sensor includes a flexible diaphragm electrode spaced from a counter electrode.

5. the faceplate includes a first substrate coupled to a second substrate; the flexible diaphragm electrode includes at least a portion of the first substrate, and the counter electrode includes at least a portion of the second substrate; The intraocular implant of claim 4.

6. a first conductive via connected to the flexible diaphragm electrode and extending through the faceplate; a second conductive via connected to the counter electrode; an electrical interconnect circuit connected to the first conductive via and the second conductive via; The intraocular implant of claim 5 further comprising:

7. The intraocular implant of claim 1 , further comprising a coil embedded in an inner surface of the faceplate.

8. The intraocular implant of claim 7 , wherein the coil includes conductors provided in channels formed in the inner surface of the faceplate, the channels being laid out to form a plurality of loops.

9. The intraocular implant of claim 1 , further comprising a stress relief cutout formed in the faceplate around the physiological sensor.

10. The intraocular implant of claim 9 , wherein the stress relief cutout comprises a channel extending partially through the faceplate.

11. The intraocular implant of claim 1 , wherein the faceplate and the physiological sensor are both formed from silicon.

12. The intraocular implant of claim 1 , further comprising a humidity sensor provided within the housing.

13. The intraocular implant of claim 12 , wherein the humidity sensor includes a capacitor having a plurality of electrodes and a moisture sensitive dielectric.

14. The intraocular implant of claim 13 , wherein the moisture sensitive dielectric comprises a getter material.

15. 14. The intraocular implant of claim 13, further comprising a capacitance-to-digital converter that reads the capacitance of the humidity sensor.

16. the physiological sensor includes a capacitive sensor; a capacitance-to-digital converter coupled to the physiological sensor for reading the capacitance of the physiological sensor; The intraocular implant of claim 1 .

17. The intraocular implant of claim 1 , wherein the physiological sensor comprises a glucose sensor.

18. The intraocular implant of claim 1 , wherein the housing includes a convex curved surface having a first radius of curvature in a first direction and a second radius of curvature in a second direction perpendicular to the first direction.

19. 20. The intraocular implant of claim 18, wherein the first radius of curvature corresponds to a radius of curvature of the iridocorneal angle of a normal human eye in a plane perpendicular to an optical axis of the eye, and the second radius of curvature corresponds to a radius of curvature of the iridocorneal angle of the eye in a plane including the optical axis of the eye.

20. The intraocular implant of claim 1 , wherein the exterior of the housing is coated in a thin film atomic layer deposition (ALD) coating.

21. The intraocular implant of claim 20 , wherein the thin film ALD coating covers a surface of the physiological sensor.

22. 22. The intraocular implant of claim 21, wherein the thin film ALD coating further covers a hermetic seal.

23. 21. The intraocular implant of claim 20, wherein the thin film ALD coating comprises a multi-layer stack of at least two different materials.

24. The intraocular implant of claim 1 , wherein the physiological sensor is disposed within a recess formed in an outer surface of the faceplate.

25. The intraocular implant of claim 1 , wherein the housing includes one or more protrusions or grooves that facilitate the flow of aqueous humor around the housing.

26. The intraocular implant of claim 1 , wherein the housing includes at least one retention tab that retains the at least one protruding anchor.

27. the retention tab includes a through hole; the at least one protruding anchor comprises an elongated body and a penetration head at a first end, the elongated body extending through the through hole of the retention tab and having a diameter smaller than a diameter of the through hole, and a penetration head having a diameter larger than a diameter of the through hole, and a second end of the protruding anchor is deformable.

27. The intraocular implant of claim 26.

28. The intraocular implant of claim 1 , further comprising a controller configured to obtain measurements of physiological characteristics with the physiological sensor.

29. 10. The intraocular implant of claim 1, further comprising a controllable opening and closing device connected between the battery and one or more other electrical components, the controllable opening and closing device configured to open upon a malfunction.

30. The intraocular implant of claim 1 , further comprising a transceiver configured to wirelessly transmit measurement data to an external device.

31. The intraocular implant of claim 1 , further comprising a hermetic seal between the faceplate and the cover, the hermetic seal comprising a eutectic solder.

32. obtaining an intraocular pressure measurement using an intraocular implant, the intraocular implant comprising a physiological sensor whereby intraocular pressure is measured using the physiological sensor; storing the intraocular pressure measurement in a memory of the intraocular implant; transmitting the intraocular pressure measurement to an external device by the coil embedded in an inner surface of the intraocular implant; 1. A method for monitoring intraocular pressure comprising: The external device wirelessly receives the intraocular pressure measurements via RF transmissions from the intraocular implant.

33. Providing power to a capacitor disposed in the intraocular implant.

33. The method of claim 32, further comprising: The method, wherein the step of providing power includes wirelessly transmitting power from the external charging device to a coil embedded in an inner surface of the intraocular implant.

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