Hermetic thin-film substrate bonding

Abstract

A sealing structure includes a layer of thin-film sputtered material, such as nitinol, titanium, or similar material. The sealing structure preferably further includes a layer of dissimilar material, such as a non-nitinol and / or non-sputtered material, wherein an intermediary layer of eutectic gold-tin is provided for bonding the layer of thin-film sputtered material to the layer of dissimilar material. Examples of a dissimilar material include ceramic and glass.

Description

Docket No.: ADV-23598WO01 HERMETIC THIN-FILM SUBSTRATE BONDING RELATED APPLICATION(S)

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 625,783, filed on January 26, 2024, the disclosure of which is hereby incorporated by reference. BACKGROUND

[0002] The present disclosure generally relates to the field of material bonding, such as in the context of techniques and processes designed to join different materials, including superelastic materials such as nitinol or other shape memory metals / alloys, in a manner as to provide certain features, such as mechanical integrity, electrical conductivity, and / or hermetic sealing. For some structures / assemblies, successful hermetic bonding can provide / improve suitability for medical implantation, for example. Bonding techniques and materials that involve fusion welding using temperatures greater than the transformation or melting temperature of the material(s) being bonded can cause degradation, damage, and / or other effects with respect to the bonded materials. SUMMARY

[0003] Described herein are methods, systems, and devices that facilitate formation of stable, hermetic seals between ceramic bodies, or other substrates, and nitinol or other superelastic layers, which may be used in pressure-sensing implant devices, for example.

[0004] In some implementations, the present disclosure relates to implantable pressure sensors comprising a sensor body mechanically and / or electrically coupled with a diaphragm structure, which may be formed of thin-film nitinol or similar superelastic material. Such devices can advantageously integrate a nitinol (or similar) thin-film diaphragm formed using physical vapor deposition (PVD) or similar process(es) with a ceramic sensor body or other non-nitinol substrate (e.g., glass, polyimide, FR4, laminate, PTFE, aluminum or other metal, or the like). Such integration can be implemented in accordance with aspects of the present disclosure to preserve the mechanical properties of the nitinol layer(s), such as superelasticity.

[0005] Examples of the present disclosure provide for hermetically joining thin-film nitinol diaphragms / layers to a base substrate (e.g., ceramic) using a relatively low-temperature process to prevent disturbance of the superelasticity and / or other properties of the nitinol. Such process(es) can involve the integration of one or more gold-tin (Au / Sn) layers, which may be applied directly to and / or around a perimeter of a nitinol diaphragm structure, which may serve as a deflectable pressure-sensor diaphragm. The Au / Sn layer(s) can advantageously enable the formation of aDocket No.: ADV-23598WO01 hermetic seal that does not compromise the superelastic properties of the nitinol, and further provides a structural seal and / or electrical interface between the diaphragm and the base / substrate.

[0006] In some implementations, gold-tin layers implemented in connection with examples of the present disclosure comprise an alloy composed of about 80% gold (Au) and about 20% tin (Sn). Such composition can provide a eutectic solid, which possesses a melting point that is advantageously lower than the transition temperature of nitinol, and below the melting points of pure Au and pure Sn. By melting this eutectic alloy, which can occur below the transition temperature of the nitinol thereby preserving the physical characteristics of the nitinol, a robust hermetic seal can be established between the base substrate / ceramic sensor body and the nitinol diaphragm. The produced seal, in addition to being hermetically effective, can also adhere well to both materials being joined.

[0007] Gold-tin (Au / Sn) alloy layers implemented as described herein can advantageously exhibit thermal expansion properties that are intermediate between those of the base ceramic (or other non-nitinol substrate) and the nitinol diaphragm structure. This intermediate thermal expansion characteristic can advantageously mitigates the risk of separation or crack formation in the sensor, which could otherwise arise due to discrepancies in thermal expansion and contraction between the diaphragm and base materials. Therefore, aspects of the present disclosure can promote the long-term integrity and reliability of pressure sensor and / or other devices, which may be particularly beneficial for biomedical implantation applications.

[0008] Some pressure sensors disclosed herein that are configured for implantation include a sensor body and a diaphragm. Hermetically joining PVD Nitinol diaphragm to the ceramic sensor body requires a low-temperature process to avoid disturbing the Nitinol properties. This invention integrates an Au / Sn layer onto the perimeter of the diaphragm allowing for creation of a hermetic seal while maintaining the superelastic properties of Nitinol. An alloy of 80 / 20 Au / Sn forms a eutectic solid having a melting point below the transition temperature of Nitinol. Soldering, or melting, the eutectic alloy allows for a hermatic seal between the ceramic and Nitinol, adhering well to both materials. The Au / Sn alloy has thermal expansion properties intermediate to ceramic and Nitinol thereby avoiding separation and crack formation due to thermal expansion / contraction.

[0009] In some implementations, the present disclosure relates to nitinol-to-substrate bonding / joining techniques in which one or more Au / Sn alloy layers is implemented directly between the base substrate (e.g., ceramic material) and the nitinol diaphragm. In some implementations, one or more intermediate layers, such as titanium, (Ti), nitinol, titanium tungsten (TiW), titanium tungsten gold (TiW / Au), or similar.Docket No.: ADV-23598WO01

[0010] Any of the various systems, devices, apparatuses, etc. in this disclosure can be sterilized (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.) to ensure they are safe for use with patients, and the methods herein can comprise sterilization of the associated system, device, apparatus, etc. (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.).

[0011] Methods and structures disclosed herein for treating a patient also encompass analogous methods and structures performed on or placed on a simulated patient, which is useful, for example, for training; for demonstration; for procedure and / or device development; and the like. The simulated patient can be physical, virtual, or a combination of physical and virtual. A simulation can include a simulation of all or a portion of a patient, for example, an entire body, a portion of a body (e.g., thorax), a system (e.g., cardiovascular system), an organ (e.g., heart), or any combination thereof. Physical elements can be natural, including human or animal cadavers, or portions thereof; synthetic; or any combination of natural and synthetic. Virtual elements can be entirely in silico, or overlaid on one or more of the physical components. Virtual elements can be presented on any combination of screens, headsets, holographically, projected, loudspeakers, headphones, pressure transducers, temperature transducers, or using any combination of suitable technologies.

[0012] For purposes of summarizing the disclosure, certain aspects, advantages and novel features have been described. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular example. Thus, the disclosed examples may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various examples are depicted in the accompanying drawings for illustrative purposes and should in no way be interpreted as limiting the scope of the inventions. In addition, various features of different disclosed examples can be combined to form additional examples, which are part of this disclosure. Throughout the drawings, reference numbers may be reused to indicate correspondence between reference elements.

[0014] Figure 1 illustrates certain human anatomy showing example sensor implant locations in accordance with one or more examples.

[0015] Figure 2 is a block diagram representing a system for wirelessly monitoring one or more physiological parameters associated with a patient in accordance with one or more examples.

[0016] Figures 3A and 3B show cross-sectional side views of a piezoresistive pressure sensor device in accordance with one or more examples.Docket No.: ADV-23598WO01

[0017] Figures 4A and 4B show cross-sectional side views of a capacitive pressure sensor device in accordance with one or more examples.

[0018] Figure 5 is a block diagram showing a thin-film deposition system in accordance with one or more examples.

[0019] Figure 6 shows a side cross-sectional schematic diagram of a sensor device having a capacitive electrode structurally conformal with a thin-film, superelastic diaphragm in accordance with one or more examples.

[0020] Figure 7 shows a side cross-sectional schematic diagram of a sensor device having a pressure-transmitting medium in accordance with one or more examples.

[0021] Figures 8A and 8B show front and back perspective views of a nitinol diaphragm structure structure in accordance with one or more examples.

[0022] Figure 9 shows a base structure for a sensor device in accordance with one or more examples.

[0023] Figures 10A and 10B show perspective and cross-sectional views, respectively, of a sensor device including one or more diaphragm structures physically coupled to a base structure in accordance with one or more examples.

[0024] Figures 11A and 11B show front and back perspective views of a sensor diaphragm structure in accordance with one or more examples.

[0025] Figure 12 shows a base structure for a capacitive sensor device in accordance with one or more examples.

[0026] Figures 13A and 13B show perspective and cross-sectional views, respectively, of a sensor device including one or more diaphragm structures physically coupled to a base structure in accordance with one or more examples.

[0027] Figures 14A and 14B show perspective and cross-sectional views, respectively, of a dual-sided sensor device in accordance with one or more examples.

[0028] Figures 15A and 15B show exploded and assembled / bonded views, respectively, of a material stack-up providing a hermetic seal and / or electrical interface between a thin-film nitinol (or other metal) layer and a dissimilar substrate (e.g., ceramic, glass) using a gold-tin alloy filler in accordance with one or more examples.

[0029] Figures 16A and 16B show exploded and assembled / bonded views, respectively, of a material stack-up capable of producing a hermetic seal between a thin-film nitinol (or other metal) layer and a dissimilar substrate (e.g., ceramic, glass) using a gold-tin alloy filler in accordance with one or more examples.Docket No.: ADV-23598WO01

[0030] Figures 17A and 17B show exploded and assembled / bonded views, respectively, of a material stack-up capable of producing a hermetic seal between a thin-film nitinol (or other metal) layer and a dissimilar substrate (e.g., ceramic, glass) using a gold-tin alloy filler in accordance with one or more examples.

[0031] Figure 18 shows a temperature profile for a process of bonding dissimilar materials using one or more gold-tin layer(s) in accordance with one or more examples.

[0032] Figure 19 shows a force profile for a process of bonding dissimilar materials using one or more gold-tin layer(s) in accordance with one or more examples.

[0033] Figures 20A, 20B, and 20C show schematic, close-up, and side cross-sectional views, respectively, of a wafer having a plurality of diaphragm structures formed thereon in accordance with one or more examples.

[0034] Figures 21A and 21B show exploded and assembled / bonded views of a gold-tin bond including a hard-stop in accordance with one or more examples.

[0035] Figure 22A shows a sensor base structure including coined hard-stop bumps in accordance with one or more examples.

[0036] Figures 22B and 22C show exploded and assembled / bonded views of a gold-tin bond including a hard-stop bump in accordance with one or more examples.

[0037] Figure 23A shows a sensor base structure including a hard-stop extrusion in accordance with one or more examples.

[0038] Figures 23B and 23C show exploded and assembled / bonded views, respectively, of a gold-tin bond including a hard-stop extrusion in accordance with one or more examples.

[0039] Figures 24A and 24B show exploded and assembled / bonded views, respectively, of a gold-tin bond including redundant bonds / seals in accordance with one or more examples.

[0040] Figures 25A and 25B show plan and side cross-sectional views, respectively, of a diaphragm structure having one or more gold-tin seals in accordance with one or more examples.

[0041] Figures 26A and 26B show plan and side cross-sectional views, respectively, of a diaphragm structure having one or more gold-tin seals in accordance with one or more examples.

[0042] Figures 27A and 27B show plan and side cross-sectional views, respectively, of a diaphragm structure having one or more gold-tin seals in accordance with one or more examples.

[0043] Figures 28A and 28B show plan and side cross-sectional views, respectively, of a diaphragm structure having parallel gold-tin seals in accordance with one or more examples.

[0044] Figures 29A and 29B show plan and side cross-sectional views, respectively, of a diaphragm structure having parallel gold-tin seals in accordance with one or more examples.Docket No.: ADV-23598WO01

[0045] Figure 30 shows a plan view of a diaphragm structure having gold-tin seals in a grid pattern in accordance with one or more examples.

[0046] Figures 31A, 31B, and 31C show isolated, exploded, and bonded / assembled views, respectively, of a material stack-up including a plurality of gold-tin bonds in accordance with one or more examples.

[0047] Figure 32 is a graph showing a relationship between gold and tin concentrations in a gold-tin alloy and associated melting points in accordance with one or more examples.

[0048] Figures 33A and 33B show exploded and bonded / assembled views of a structure having gold-tin bond(s) providing electrical connection in accordance with one or more examples.

[0049] Figures 34A and 34B show plan and side views, respectively, of a sensor device with gold-tin electrical contacts in accordance with one or more examples.

[0050] Figure 35 shows a sensor device with gold-tin electrical contacts bonded with an electrical device in accordance with one or more examples.

[0051] Figure 36 is a cutaway view of a human heart and associated vasculature showing certain catheter access paths for sensor device implantation procedures in accordance with one or more examples. DETAILED DESCRIPTION

[0052] The headings provided herein are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.

[0053] Although certain preferred examples are disclosed below, it should be understood that the inventive subject matter extends beyond the specifically disclosed examples to other alternative examples and / or uses and to modifications and equivalents thereof. Thus, the scope of the claims that may arise herefrom is not limited by any of the particular examples described below. For example, in any method or process disclosed herein, the acts or operations of the method or process may be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding certain examples; however, the order of description should not be construed to imply that these operations are order dependent. Additionally, the structures, systems, and / or devices described herein may be embodied as integrated components or as separate components. For purposes of comparing various examples, certain aspects and advantages of these examples are described. Not necessarily all such aspects or advantages are achieved by any particular example. Thus, various examples may be carried out in a manner thatDocket No.: ADV-23598WO01 achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as may also be taught or suggested herein.

[0054] Certain spatially relative terms, such as “outer,” “inner,” “upper,” “lower,” “below,” “above,” “vertical,” “horizontal,” “top,” “bottom,” “distal,” “proximal,” and similar terms, are used herein to describe a spatial relationship of one device / element or anatomical structure to another device / element or anatomical structure. It should be understood that these terms are used herein for ease of description to describe the positional relationship between element(s) / structures(s), as illustrated in the drawings. It should be understood that spatially relative terms are intended to encompass different orientations of the element(s) / structures(s), in use or operation, in addition to the orientations depicted in the drawings. For example, an element / structure described as “above” another element / structure may represent a position that is below or beside such other element / structure with respect to alternate orientations of the subject patient or element / structure, and vice-versa. It should be understood that spatially relative terms, including those listed above, may be understood relative to a respective illustrated orientation of a referenced figure.

[0055] Certain reference numbers are re-used across different figures of the figure set of the present disclosure as a matter of convenience for devices, components, systems, features, and / or modules having features that are similar in one or more respects. However, with respect to any of the examples disclosed herein, re-use of common reference numbers in the drawings does not necessarily indicate that such features, devices, components, or modules are identical or similar. Rather, one having ordinary skill in the art may be informed by context with respect to the degree to which usage of common reference numbers can imply similarity between referenced subject matter. Use of a particular reference number in the context of the description of a particular figure can be understood to relate to the identified device, component, aspect, feature, module, or system in that particular figure, and not necessarily to any devices, components, aspects, features, modules, or systems identified by the same reference number in another figure. Furthermore, aspects of separate figures identified with common reference numbers can be interpreted to share characteristics or to be entirely independent of one another.

[0056] Where an alphanumeric reference identifier is used that comprises a numeric portion and an alphabetic portion (e.g., ‘10a,’ ‘10’ is the numeric portion and ‘a’ is the alphabetic portion), references in the written description to only the numeric portion (e.g., ‘10’) may refer to any feature identified in the figures using such numeric portion (e.g., ‘10a,’ ‘10b,’ ‘10c,’ etc.), even where such features are identified with reference identifiers that concatenate the numeric portion thereof with one or more alphabetic characters (e.g., ‘a,’ ‘b,’ ‘c,’ etc.). That is, a reference in the present written description to a feature ‘10’ may be understood to refer to either an identified feature ‘10a’ in aDocket No.: ADV-23598WO01 particular figure of the present disclosure or to an identifier ‘10’ or ‘10b’ in the same figure or another figure, as an example.

[0057] The present disclosure relates to systems, devices, and methods for hermetically joining thin-film nitinol or other superelastic material to another material / substrate. Such joining / bonding techniques can be sued in connection with the packaging of devices configured for sensing and / or telemetric monitoring of one or more physiological parameters of a patient (e.g., blood pressure). For example, pressure sensing / monitoring and / or other applications can be implemented using implant devices having thin-film pressure sensor diaphragm(s). Such devices can advantageously be packaged for long-term implantation in the cardiac environment, and therefore may have certain biocompatible features associated therewith. The terms “associated” and “associated with” are used herein according to their broad and ordinary meanings. For example, where a first feature, element, component, device, or member is described as being “associated with” a second feature, element, component, device, or member, such description should be understood as indicating that the first feature, element, component, device, or member is physically coupled, attached, or connected to, integrated with, embedded at least partially within, or otherwise physically related to the second feature, element, component, device, or member, whether directly or indirectly.

[0058] The term “thin-film” is used herein according to its broad and ordinary meaning, and may refer to any film, layer, sheet, skin, veneer, coating, covering, plating, enamel, finish, shell, overlay, or other type of membrane having a thickness ranging from a few nanometers (nm) to several micrometers (µm). Thin-film membranes of the present disclosure can be applied to a substrate during fabrication, and can be produced using various deposition techniques, including but not limited to sputtering, electrodeposition, thermal deposition, chemical vapor deposition (CVD), and physical vapor deposition (PVD). Formation of thin-film membranes in accordance with aspects of the present disclosure can involve producing a phase transition of a solid-state source material to gas and reconstituting the gas into a solid state during a deposition process. Thin-film membranes of the present disclosure can comprise any suitable or desirable material, including: metals such as gold, silver, platinum, titanium, nickel, copper, aluminum, and the like, and their alloys; alloys such as nitinol (nickel-titanium) or other superelastic material, NiTiCu (nickel- titanium-copper), AuSn (gold-tin), nickle-cobalt ferrous alloy (e.g., Kovar®, Ni29Co17Fe54), stainless steel, and the like; semiconductors such as silicon, gallium arsenide (GaAs), indium phosphide (InP), cadmium telluride (CdTe), and the like; oxides such as aluminum oxide (Al₂O₃), titanium dioxide (TiO₂), zinc oxide (ZnO), and the like; nitrides such as titanium nitride (TiN), silicon nitride (Si₃N₄), gallium nitride (GaN), and the like; polymers such as polytetrafluoroethyleneDocket No.: ADV-23598WO01 (PTFE), polyimide, polyethylene terephthalate (PET), and the like; and ceramics such as silicon carbide (SiC), aluminum nitride (AlN), and the like. For example, thin-films can have thicknesses as small as 1 nm or as large as 10 µm, 15 µm, 20 µm, or larger, depending on the material properties desired. Membranes as disclosed herein may be formed using any type of sputtering process, including any process where atoms or molecules are ejected from a target material due to the bombardment by energetic particles, such as ions from a plasma, wherein the ejected particles travel through a vacuum or low-pressure gas environment and condense onto a target substrate, forming a thin membrane. “Sputtering,” as used herein, can cover any type of direct current, radio frequency, magnetron, or reactive sputtering, or any other vapor deposition process.

[0059] Examples of devices disclosed herein, such as capacitive pressure sensor devices, can advantageously include diaphragm and / or electrode structures having one or more layers formed of physical vapor deposition and / or other thin-film deposition / formation processes. Such examples can advantageously include superelastic (e.g., nitinol) diaphragm component(s) / layer(s) bonded / joined to a counterpart or corresponding structure / substrate having different material characteristics in a manner as to create a seal suitable for implantation within the human body. In some examples, such bond / joint can further provide an electrical interface between the bonded / joined components.

[0060] As described in detail below, implantable pressure sensors can be used to measure pressure levels in various conduits and chambers of body, such as in the various chambers of the heart. However, due to the accessibility and environmental conditions typically associated with the conduits / chambers of the heart and / or other potential sensor implant locations within a patient, only certain types of sensors and sensor packagings may be suitable for implantation for a given application. Examples of the present disclosure relate to the packaging of pressure sensor implant devices including certain electronics and telemetry features to allow for data and / or power communication wirelessly between the implanted sensor devices and one or more devices or systems external to the patient.

[0061] Aspects of the present disclosure relate to sensor devices, such as wireless implantable pressure sensor devices and other devices comprising superelastic diaphragm components. In particular, inventive features disclosed herein can be implemented in the context of implantable sensor devices, wherein diaphragm components are joined / bonded to base substrate components using one or more layers of gold-tin (AuSn). For example, examples of the present disclosure can include diaphragm structures that are integrated with eutectic metal layer(s) that produce a hermetic and / or electrical interface. As described in detail herein, hermetically joining thin-film nitinol (e.g., physical-vapor-deposited nitinol) generally requires a relatively low-Docket No.: ADV-23598WO01 temperature process to avoid affecting the material properties (e.g., superelasticity) of the nitinol. Integration of one or more AuSn layers onto the perimeter of a nitinol layer (e.g., diaphragm) as detailed herein can allowing for creation of a hermetic seal while maintaining the superelastic properties of nitinol. With respect to sensor device examples, AuSn-integrated sealings can provide biocompatible sealing and / or encapsulation of internal sensor components, such as capacitive electrodes and other circuitry, as well as other structural components of the device. In some applications, hermetically-sealed electronic packaging can be created using AuSn, such as by using Kovar (nickel-cobalt ferrous alloy) as the material for a metal lid to better match the coefficient of thermal expansion. Nitinol or other super elastic material joined with AuSn in accordance with aspects of the present disclosure provides a novel mechanism for forming hermetic seals for sealing electronics. Furthermore, forming a thin-film nitinol construction for thin-walled pressure transduction for implantable sensors as disclosed herein provides additional novel sensor packaging solutions. In some implementations, titanium (Ti) can be used in addition to, or in place of, nitinol for such applications. Sputtered processes creating a diaphragm (comprising any of the full range of biocompatible low-permeability metals including Ti, stainless steel, nitinol, etc.) for pressure transduction within the body, and joining the diaphragm structure with gold-tin (AuSn) in accordance with the examples presented herein can provide a number of benefits, as outlined in detail below.

[0062] With respect to implantable pressure sensor devices, anatomical considerations can necessitate the use of sensor devices having relatively small form factors. For example, it may be desirable to implant sensor devices, such as pressure sensor devices, using transcatheter procedures, wherein the sensor device is advanced to the target implantation site through one or more venous or arterial blood vessels and / or various tortuous access paths. Examples of the present disclosure advantageously can be implemented in sensor devices having a sufficiently small profile / size to be transported by and / or within a catheter, sheath, or other instrument configured for transcatheter access / use. In addition to sizing constraints associated with implantable sensor devices (e.g., pressure sensor devices), sensor sensitivity and / or dynamic range requirements or desires likewise may drive sensor design. For example, with respect to example pressure sensor devices, deflectable pressure diaphragms associated with such devices may be designed in a manner as to provide sufficient sensitivity to pressure conditions to which the device is exposed.

[0063] When creating diaphragms with thin-film metal layer(s) (e.g., physical vapor deposition nitinol) for use in implantable pressure sensors, it may be necessary to seal the device with a surrounding / perimeter structure. However, wherein nitinol is joined to a dissimilar material, various difficulties can manifest. In particular, joining nitinol to ceramics or other dissimilarDocket No.: ADV-23598WO01 substrates used in implantable pressure sensors can be problematic. For example, because of differing thermal expansion rates, separation and / or cracking of bonds / joints (e.g., welds) between the materials can occur, thereby compromising or destroying the adhesion of the different materials and the integrity of the hermetic seal created by the bond. Use of a low-melting eutectic of AuSn as a solder bonding agent to form a stable, hermetic seal between a ceramic body and nitinol diaphragm in a pressure-sensing implant device is disclosed herein.

[0064] In some examples, gold-tin (AuSn) alloy layer(s) is / are disposed directly between nitinol and non-nitinol (e.g., ceramic) structures of a device stack. Alternatively, one or more intermediate layers, such as titanium (Ti), titanium-tungsten (TiW), and / or TiW-Au, can be implemented between AuSn layer(s) and nitinol and non-nitinol structures. The various AuSn stack- up examples disclosed herein can advantageously provide sufficient biocompatibility to accommodate use with implantable devices. For example, implantable sensor devices, such as nitinol-diaphragm-equipped pressure sensor devices, may need to provide biocompatibility and / or encapsulation characteristics suitable for in vivo implantation. For example, with respect to implantation within certain anatomy, such as within a chamber of a heart, or other fluid-filled anatomical vessel / chamber, such environments can present certain pressure, turbulence, and corrosion conditions, which may be associated with fluid / blood characteristics and / or cardiac cycling. Relative to non-implant environments, the human body represents a relatively harsh environment for electrical implant devices. Examples of the present disclosure provide sensor implant devices that provide extended-duration and / or lifetime hermetic seals / sealing, which can be advantageous and / or critical for for implantable sensor application. For example, such hermetic sealing can prevent components of the environmental blood from degrading or otherwise interfering with the sensor and associated electronics. In addition, hermetic sealing of examples of the present disclosure can help prevent any non-biocompatible components of or associated with the sensor implant device from creating / causing toxic conditions within the body. Physiological Sensor Implant Locations

[0065] Certain examples are disclosed herein in the context of cardiac implant devices. However, although certain principles disclosed herein may be particularly applicable to the anatomy of the heart, it should be understood that sensor implant devices in accordance with the present disclosure may be implanted in, or configured for implantation in, any suitable or desirable anatomy. Furthermore, examples of the present disclosure may be utilized in non-biological environments as well.

[0066] The anatomy of the heart is described below to assist in the understanding of certain inventive concepts disclosed herein. In humans and other vertebrate animals, the heart generallyDocket No.: ADV-23598WO01 comprises a muscular organ having four pumping chambers, wherein the blood flow therein is at least partially controlled by various heart valves, namely, the aortic, mitral (or bicuspid), tricuspid, and pulmonary valves. The valves may be configured to open and close in response to pressure gradients present during various stages of the cardiac cycle (e.g., relaxation and contraction) to control the flow of blood to respective regions of the heart and / or to blood vessels (e.g., pulmonary, aorta, etc.). The contraction of the various heart muscles may be prompted by signals generated by the electrical system of the heart, which is discussed in detail below.

[0067] Figure 1 illustrates an example representation of a heart 1 and associated anatomy having various features relevant to certain examples of the present inventive disclosure. The illustrated anatomy shows example implant locations ‘s’ for sensor devices in accordance with aspects of the present disclosure. Generally, the heart 1 includes four chambers, namely the left atrium 2, the left ventricle 3, the right ventricle 4, and the right atrium 5. In terms of blood flow, blood generally flows from the right ventricle 4 into the pulmonary artery via the pulmonary valve 9, which separates the right ventricle 4 from the pulmonary artery 11 and is configured to open during systole so that blood may be pumped toward the lungs and close during diastole to prevent blood from leaking back into the heart from the pulmonary artery 11.

[0068] The pulmonary artery 11 carries deoxygenated blood from the right side of the heart to the lungs. Blood returns to the left atrium 2 from the lungs via the pulmonary veins 23. The pulmonary artery 11 includes a pulmonary trunk and left 15 and right 13 pulmonary arteries that branch off of the pulmonary trunk, as shown. In addition to the pulmonary valve 9, the heart 1 includes three additional valves for aiding the circulation of blood therein, including the tricuspid valve 8, the aortic valve 7, and the mitral valve 6. The tricuspid valve 8 separates the right atrium 5 from the right ventricle 4. The tricuspid valve 8 generally has three cusps / leaflets and may generally close during ventricular contraction (i.e., systole) and open during ventricular expansion (i.e., diastole). The mitral valve 6 generally has two cusps / leaflets and separates the left atrium 2 from the left ventricle 3. The mitral valve 6 is configured to open during diastole so that blood in the left atrium 2 can flow into the left ventricle 3, and, when functioning properly, closes during systole to prevent blood from leaking back into the left atrium 2. The aortic valve 7 separates the left ventricle 3 from the aorta 12. The aortic valve 7 is configured to open during systole to allow blood leaving the left ventricle 3 to enter the aorta 12, and close during diastole to prevent blood from leaking back into the left ventricle 3.

[0069] The heart valves may generally comprise a relatively dense fibrous ring, referred to herein as the annulus, as well as a plurality of leaflets or cusps attached to the annulus. Generally, the size of the leaflets or cusps may be such that when the heart contracts the resulting increasedDocket No.: ADV-23598WO01 blood pressure produced within the corresponding heart chamber forces the leaflets at least partially open to allow flow from the heart chamber. As the pressure in the heart chamber subsides, the pressure in the subsequent chamber or blood vessel may become dominant and press back against the leaflets. As a result, the leaflets / cusps come in apposition to each other, thereby closing the flow passage. Disfunction of a heart valve and / or associated leaflets (e.g., pulmonary valve disfunction) can result in valve leakage and / or other health complications.

[0070] The atrioventricular (i.e., mitral and tricuspid) heart valves generally are coupled to a collection of chordae tendineae and papillary muscles (not shown) for securing the leaflets of the respective valves to promote and / or facilitate proper coaptation of the valve leaflets and prevent prolapse thereof. The papillary muscles, for example, may generally comprise finger-like projections from the ventricle wall. The valve leaflets are connected to the papillary muscles by the chordae tendineae. A wall of muscle 17, referred to as the septum, separates the left 2 and right 5 atria and the left 3 and right 4 ventricles.

[0071] As referenced above, certain physiological conditions or parameters associated with cardiac anatomy can impact the health of a patient. For example, congestive heart failure is a condition associated with the relatively slow movement of blood through the heart and / or body, which causes the fluid pressure in one or more chambers of the heart to increase. As a result, the heart does not pump sufficient oxygen to meet the body’s needs. The various chambers of the heart may respond to pressure increases by stretching to hold more blood to pump through the body or by becoming relatively stiff and / or thickened. The walls of the heart can eventually weaken and become unable to pump as efficiently. In some cases, the kidneys may respond to cardiac inefficiency by causing the body to retain fluid. Fluid build-up in arms, legs, ankles, feet, lungs, and / or other organs can cause the body to become congested, which is referred to as congestive heart failure. Acute decompensated congestive heart failure is a leading cause of morbidity and mortality, and therefore treatment and / or prevention of congestive heart failure is a significant concern in medical care.

[0072] Various methods for identifying and / or treating congestive heart failure involve the observation of worsening congestive heart failure symptoms and / or changes in body weight. However, such signs may appear relatively late and / or be relatively unreliable. For example, daily bodyweight measurements may vary significantly (e.g., up to 9% or more) and may be unreliable in signaling heart-related complications. Furthermore, treatments guided by monitoring signs, symptoms, weight, and / or other biomarkers have not been shown to substantially improve clinical outcomes. Therefore, direct or indirect measurement / monitoring of pressure and / or other parameter(s) using implant devices can provide better outcomes than purely observation-basedDocket No.: ADV-23598WO01 solutions. For example, without direct or indirect monitoring of cardiac pressure, it can be difficult to infer, determine, or predict the presence or occurrence of congestive heart failure or other pathologies. Treatments or approaches not involving direct or indirect pressure monitoring may involve measuring or observing other present physiological conditions of the patient, such as measuring body weight, thoracic impedance, right heart catheterization, or the like. Cardiac Pressure Monitoring

[0073] Cardiac pressure monitoring in accordance with examples of the present disclosure may provide a proactive intervention mechanism for preventing or treating congestive heart failure. Generally, increases in ventricular filling pressures associated with diastolic and / or systolic heart failure can occur prior to the occurrence of symptoms that lead to hospitalization. For example, cardiac pressure indicators may present weeks prior to hospitalization with respect to some patients. Therefore, pressure monitoring systems in accordance with examples of the present disclosure may advantageously be implemented to reduce instances of hospitalization by guiding the appropriate or desired titration and / or administration of medications before the onset of heart failure.

[0074] Cardiac pressure monitoring, such as left atrial pressure monitoring, can provide a mechanism to guide administration of medication to treat and / or prevent congestive heart failure. Such treatments may advantageously reduce hospital readmissions and morbidity, as well as provide other benefits. An implanted pressure sensor in accordance with examples of the present disclosure may be used to predict heart failure up to two weeks or more before the manifestation of symptoms or markers of heart failure (e.g., dyspnea). When heart failure predictors are recognized using cardiac pressure sensor examples in accordance with the present disclosure, certain prophylactic measures may be implemented, including medication intervention, such as modification to a patient’s medication regimen, which may help prevent or reduce the effects of cardiac dysfunction. Direct pressure measurement in the left atrium can advantageously provide an accurate indicator of pressure buildup that may lead to heart failure or other complications. For example, trends of atrial pressure elevation may be analyzed or used to determine or predict the onset of cardiac dysfunction, wherein drug or other therapy may be augmented to cause reduction in pressure and prevent or reduce further complications.

[0075] Figure 2 is a block diagram representing a system 200 for wirelessly monitoring one or more physiological parameters associated with a patient according to one or more examples. Figure 2 shows an implant device 30 comprising a sensor device 37, which may have associated therewith certain anchoring structure 31. For example, the anchoring structure 31 may be configured to anchor in and / or to one or more biological tissue walls. Although various examples of implantable sensor devices are illustrated and described in the present disclosure without separateDocket No.: ADV-23598WO01 anchoring structure, it should be understood that such omissions are solely for the purpose of clarity and any of the examples disclosed herein may have associated therewith certain anchoring structure for anchoring the device to biological tissue / anatomy at the implantation site.

[0076] The sensor device 37 may be a pressure sensor according to any of the examples disclosed herein. In some examples, the sensor 37 comprises a transducer 32, as well as certain control circuitry 34, which may be embodied in, for example, an application-specific integrated circuit (ASIC) and / or one or more passive devices (e.g., resistors, capacitors, inductors, etc.). The sensor device 37 further includes a diaphragm 33, which is formed of superelastic material and has layered / integrated thereon one or more electrode layers or other electronics that form part of the transducer circuit. The diaphragm 33 may be integrated at least in part with the outer layer(s) of the sensor housing 36. In some examples, the sensor housing 36 includes a radio-frequency-transparent structure that houses at least a portion of the antenna 38.

[0077] The control circuitry 34 of the sensor device 37 may be configured to process signals received from the transducer 32 and / or communicate signals associated therewith wirelessly through biological tissue using the antenna 38. The antenna 38 may comprise one or more coils or loops of conductive material, such as copper wire or the like, or piezoelectric resonator(s), or other wireless signal transmission component(s). In some examples, at least a portion of the transducer 32, control circuitry 34, and / or the antenna 38 are at least partially disposed or contained within the sensor housing / packaging 36 structure, which may comprise any type of material and may advantageously be at least partially hermetically sealed. The housing 36, as well as the diaphragm 33, may be formed at least in part using vapor deposition, as described in greater detail below.

[0078] The term “control circuitry” is used herein according to its broad and ordinary meaning, and may refer to any collection of processors, processing circuitry, processing modules / units, chips, dies (e.g., semiconductor dies including come or more active and / or passive devices and / or connectivity circuitry), microprocessors, micro-controllers, digital signal processors, microcomputers, central processing units, field programmable gate arrays, programmable logic devices, state machines (e.g., hardware state machines), logic circuitry, analog circuitry, digital circuitry, and / or any device that manipulates signals (analog and / or digital) based on hard coding of the circuitry and / or operational instructions. Control circuitry referenced herein may further comprise one or more storage devices, which may be embodied in a single memory device, a plurality of memory devices, and / or embedded circuitry of a device. Such data storage may comprise read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, data storage registers, and / or any device that stores digital information. It should be noted that in examples in which control circuitryDocket No.: ADV-23598WO01 comprises a hardware and / or software state machine, analog circuitry, digital circuitry, and / or logic circuitry, data storage device(s) / register(s) storing any associated operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and / or logic circuitry.

[0079] The housing / packaging 36 may comprise one or more tubes, cans, substrates / boards or other structures comprising glass, epoxy, ceramics, metal, and / or other rigid material(s) in some examples, which may provide mechanical stability and / or protection for the components housed therein. In some examples, the housing / packaging 36 is at least partially flexible. For example, the housing / packaging may comprise polymer or other flexible structure / material, which may advantageously allow for folding, bending, or collapsing of aspects of the sensor 37 to allow for passage thereof through a catheter or other introducing means. However, examples of the present disclosure can advantageously be implemented in such as manner as to provide long term hermetic protection, wherein thin-film, flexible diaphragm(s) for pressure transmission and associated electrical circuitry are integrated into a single part, component, and / or device.

[0080] The transducer 32 may comprise any type of sensor means or mechanism. For example, the transducer 32 may be a force-collector-type pressure sensor. The transducer 32 is shown and described as comprising one or more diaphragms. However, it should be understood that pressure sensor devices disclosed herein may utilize any type of deflectable strain- or deflection- measuring component(s) configured to measure strain or deflection applied over an area / surface thereof, such as one or more pistons, bourdon tubes, bellows, or the like. The transducer 32 may be associated with the housing / packaging 36, such that at least a portion thereof is contained within or attached to the housing / packaging 36. In some examples, the electrode-integrated diaphragm 33 can serve as a component of a piezoresistive MEMS pressure sensor, which may be configured to use bonded or formed conductors to detect strain due to applied pressure, wherein resistance increases as pressure deforms the component / material. That is, the integrated electrode(s) 33 of the transducer 32 may be components of a piezoresistor. In such implementations, the conductor(s) may be applied to a thin-film nitinol diaphragm layer; piezoresistive pressure sensors are described below in connection with Figures 3A and 3B. Alternatively, the diaphragm 33 may be a component of a capacitive pressure sensor, where a capacitive plate / electrode layer is applied to the nitinol diaphragm layer, as described in detail throughout the present disclosure; capacitive pressure sensors are described generally below in connection with Figures 4A and 4B.

[0081] In some examples, the transducer 32 comprises or is a component of an electromagnetic pressure sensor, which may be configured to measure the displacement of a diaphragm by means of changes in capacitance, linear variable displacement transducer (LVDT)Docket No.: ADV-23598WO01 functionality, Hall Effect, or eddy current sensing. In some examples, the transducer 32 comprises or is a component of a piezoelectric strain sensor. For example, such a sensor may determine strain (e.g., pressure) on a sensing mechanism based on the piezoelectric effect in certain materials, such as quartz. In some examples, the transducer 32 comprises or is a component of a strain gauge. In any of such implementations, the relevant sensor electrodes / conductors may be applied to a thin- film nitinol diaphragm component, as described in detail herein.

[0082] The transducer 32 may be integrated with, or comprise, one or more layers of vapor- deposited, biocompatible material, as described in detail below. In some examples, the transducer(s) 32 is / are electrically and / or communicatively coupled to the control circuitry 34, which may comprise one or more application-specific integrated circuit (ASIC) microcontrollers or chips. The control circuitry 34 can further include one or more discrete electronic components, such as tuning capacitors, resistors, diodes, inductors, or the like.

[0083] In the system 200 of Figure 2, the implant device 30 is implanted in a patient 44 for the purpose of monitoring one or more physiological parameters (e.g., left atrial pressure). The patient 44 can have the medical implant device 30 implanted in, for example, his / her heart (not shown), or associated physiology. For example, the implant device 30 can be implanted at least partially within the left atrium of the patient’s heart.

[0084] In certain examples, the monitoring system 200 can comprise at least two subsystems, including the implantable internal subsystem or device 30 that includes the sensor transducer(s) 32, as well as control circuitry 34 comprising one or more microcontroller(s), discrete electronic component(s), and one or more power and / or data transmitter(s) 38 (e.g., antenna coils). The monitoring system 200 can further include an external (e.g., non-implantable) subsystem that includes an external reader 42 (e.g., coil), which may include a wireless transceiver that is electrically and / or communicatively coupled to certain control circuitry 41. In certain examples, both the internal and external subsystems include a corresponding coil antenna for wireless communication and / or power delivery through patient tissue disposed therebetween. The sensor implant device 30 can be any type of implant device. In some examples, the implant device 30 comprises a pressure sensor integrated with another functional implant structure, such as a prosthetic shunt or stent device / structure, valves, clips.

[0085] The implant device 30 can comprise certain anchoring structure 31, as referenced above. For example, the anchor structure 31 can include a percutaneously deliverable shunt device configured to be secured to and / or in a tissue wall. Although certain components are illustrated in Figure 2 as part of the implant device 30, it should be understood that the sensor implant device 30 may only comprise a subset of the illustrated components / modules and can comprise additionalDocket No.: ADV-23598WO01 components / modules not illustrated. The implant device 30 may represent an example of any of the implant devices shown in Figures 8–18, and vice versa.

[0086] In certain examples, the sensor transducer(s) 32 can be configured to generate electrical signals that can be wirelessly transmitted to a device outside the patient’s body, such as the illustrated local external monitor system 42. The control circuitry 34 may comprise any type of transceiver circuitry configured to transmit an electromagnetic signal, wherein the signal can be radiated by the antenna 38, which may comprise one or more conductive wires, coils, plates, or the like. The control circuitry 34 of the implant device 30 can comprise, for example, one or more chips or dies configured to perform some amount of processing on signals generated and / or transmitted using the device 30. However, due to size, cost, and / or other constraints, the implant device 30 may not include independent processing capability in some examples.

[0087] The wireless signals generated by the implant device 30 can be received by the local external monitor device or subsystem 42, which can include a reader / antenna-interface circuitry module 43 configured to receive the wireless signal transmissions from the implant device 30, which is disposed at least partially within the patient 44. For example, the module 43 may include transceiver device(s) / circuitry.

[0088] The external local monitor 42 can receive the wireless signal transmissions and / or provide wireless power using an external antenna 48, such as a wand device. The reader / antenna- interface circuitry 43 can include radio-frequency (RF) (or other frequency band) front-end circuitry configured to receive and amplify the signals from the implant device 30, wherein such circuitry can include one or more filters (e.g., band-pass filters), amplifiers (e.g., low-noise amplifiers), analog-to-digital converters (ADC) and / or digital control interface circuitry, phase-locked loop (PLL) circuitry, signal mixers, or the like. The reader / antenna-interface circuitry 43 can further be configured to transmit signals over a network 49 to a remote monitor subsystem or device 46. The RF circuitry of the reader / antenna-interface circuitry 43 can further include one or more of digital- to-analog converter (DAC) circuitry, power amplifiers, low-pass filters, antenna switch modules, antennas or the like for treatment / processing of transmitted signals over the network 49 and / or for receiving signals from the implant device 30. In certain examples, the local monitor 42 includes control circuitry 41 for performing processing of the signals received from the implant device 30. The local monitor 42 can be configured to communicate with the network 49 according to a known network protocol, such as Ethernet, Wi-Fi, or the like. In certain examples, the local monitor 42 comprises a smartphone, laptop computer, or other mobile computing device, or any other type of computing device.Docket No.: ADV-23598WO01

[0089] In certain examples, the implant device 30 includes some amount of volatile and / or non-volatile data storage. For example, such data storage can comprise solid-state memory utilizing an array of floating-gate transistors, or the like. The control circuitry 34 may utilize data storage for storing sensed data collected over a period of time, wherein the stored data can be transmitted periodically to the local monitor 42 or another external subsystem. In certain examples, the implant device 30 does not include any data storage. The control circuitry 34 may be configured to facilitate wireless transmission of data generated by the sensor transducer(s) 32, or other data associated therewith. The control circuitry 34 may further be configured to receive input from one or more external subsystems, such as from the local monitor 42, or from a remote monitor 46 over, for example, the network 49. For example, the implant device 30 may be configured to receive signals that at least partially control the operation of the implant device 30, such as by activating / deactivating one or more components or sensors, or otherwise affecting operation or performance of the implant device 30.

[0090] The one or more components of the implant device 30 can be powered by one or more power sources 35 (e.g., battery). Due to size, cost and / or electrical complexity concerns, it may be desirable for the power source 35 to be relatively minimalistic in nature. For example, high- power driving voltages and / or currents in the implant device 30 may adversely affect or interfere with operation of the heart or other body part associated with the implant device. In certain examples, the power source 35 is at least partially passive in nature, such that power can be received from an external source wirelessly by passive circuitry of the implant device 30, such as through the use of short-range, or near-field wireless power transmission, or other electromagnetic coupling mechanism.

[0091] In some examples, the local monitor device 42 can serve as an intermediate communication device between the implant device 30 and the remote monitor 46. The local monitor device 42 can be a dedicated external unit designed to communicate with the implant device 30. For example, the local monitor device 42 can be a wearable communication device, or other device that can be readily disposed in proximity to the patient 44 and implant device 30. The local monitor device 42 can be configured to continuously, periodically, or sporadically interrogate the implant device 30 in order to extract or request sensor-based information therefrom. In certain examples, the local monitor 42 comprises a user interface, wherein a user can utilize the interface to view sensor data, request sensor data, or otherwise interact with the local monitor system 42 and / or implant device 30.

[0092] The system 40 can include a secondary local monitor 47, which can be, for example, a desktop computer or other computing device configured to provide a monitoring station orDocket No.: ADV-23598WO01 interface for viewing and / or interacting with the monitored cardiac pressure data. The local monitor 47, monitoring performed thereby, and / or monitored data can be used / leveraged for troubleshooting. In an example, the local monitor 42 can be a wearable device or other device or system configured to be disposed in close physical proximity to the patient and / or implant device 30, wherein the local monitor 42 is primarily designed to receive / transmit signals to and / or from the implant device 30 and provide such signals to the secondary local monitor 47 for viewing, processing, and / or manipulation thereof. The external local monitor system 42 can be configured to receive and / or process certain metadata from or associated with the implant device 30, such as device ID or the like, which can also be provided over the data coupling from the implant device 30.

[0093] The remote monitor subsystem 46 can be any type of computing device or collection of computing devices configured to receive, process and / or present monitor data received over the network 49 from the local monitor device 42, secondary local monitor 47, and / or implant device 30. For example, the remote monitor subsystem 46 can advantageously be operated and / or controlled by a healthcare entity, such as a hospital, doctor, or other care entity associated with the patient 44. Although certain examples disclosed herein describe communication with the remote monitor subsystem 46 from the implant device indirectly through the local monitor device 42, in certain examples, the implant device 30 can comprise a transmitter capable of communicating over the network 49 with the remote monitor subsystem 46 without the necessity of relaying information through the local monitor device 42.

[0094] In certain examples, the antenna 48 of the external monitor system 42 comprises an external coil antenna that is matched and / or tuned to be inductively paired with the antenna 38 of the internal implant 30. In some examples, the implant device 30 is configured to receive wireless ultrasound power charging and / or data communication between from the external monitor system 42. As referenced above, the local external monitor 42 can comprise a wand or other hand-held reader. In some examples, the antenna 48 comprises a piezoelectric crystal.

[0095] In some examples, a relay transceiver implant device 45 is implanted or otherwise positioned on the patient 44, wherein the device 45 serves as an intermediary between the sensor 30 and the external monitor 42. For example, the device 45 can include one or more antennas configured to receive wireless transmission signals from the sensor 30 and relay the signals (with or without intermediate signal processing) to the external monitor 42. The relay device 45 can be configured to transmit / broadcast signals at a higher power level than the sensor device 30. The relay device 45 can further receive signals from the external monitor 42 and relay such signals to the sensor 30.Docket No.: ADV-23598WO01 Implantable Pressure Sensor Devices with Deflectable Diaphragms

[0096] Pressure sensors that can be used in medical implant applications include sensors utilizing micro-electromechanical system (MEMS) technology. Such devices may combine relatively small mechanical and electrical components on a substrate, such as silicon or other semiconductor substrate, and may incorporate deformable membranes that are used to measure pressure-induced deflection thereof, wherein the degree of deflection of the membrane is indicative of pressure conditions to which the sensor membrane is exposed at the implant location. Examples of the present disclosure improve upon certain MEMS technologies by applying conductor layers and / or other conductor features to deflectable diaphragm stacks formed on a diaphragm substrate comprising thin-film nitinol or similar material. Thin-film diaphragms of sensor devices disclosed herein may be constructed as components of any type of deflection-based sensor device, such as piezoresistive pressure sensors and capacitive pressure sensors. Such sensors advantageously include a flexible diaphragm layer that serves as a deformable membrane that deflects under pressure, wherein integrated conductor features of the diaphragm stack produce a mechanism to measure the displacement of the diaphragm(s). This structure can advantageously provide both transducer structure / functionality and protection from the hostile external environment.

[0097] With respect to resistive (e.g., piezoresistive) pressure sensors, certain conductive sensing elements may be fabricated directly onto the diaphragm of the device (or onto an insulator layer formed on the diaphragm) using sputtering, vapor deposition, or other application process, wherein changes in the electrical resistance of such conductor(s) can be determined to indicate a measure of pressure applied to the diaphragm. Generally, the change in resistance may be proportional to the strain on the conductor(s), wherein the change in resistance of the conductor(s) is related to the change in length of the conductor(s) induced by deflection of the diaphragm on which the conductor(s) are disposed.

[0098] Figure 3A is a side view of a resistive pressure sensor device 320 implemented on a substrate 328 in accordance with one or more examples. Figure 3B is a side view of the piezoresistive pressure sensor 320 of Figure 3A, wherein a diaphragm 325 of the sensor is deflected in accordance with one or more examples. The deflection of the diaphragm 325 may be caused by pressure conditions to which the diaphragm 325 is exposed. The diaphragm 325 may be formed from a substrate material, such as thin-film nitinol, other material, which may be formed using physical vapor deposition or other process. In some examples, the thin diaphragm 325 may be formed by etching the substrate 326 to produce a relatively thin membrane for the diaphragm 325, which may enclose a cavity 329.Docket No.: ADV-23598WO01

[0099] The diaphragm 325 may have one or more conductive traces or elements 322 disposed thereon and / or applied thereto. For example, the conductive elements 322 may comprise traces of metal or other electrical conductor, wherein one or more length portions of the conductor(s) extend over the diaphragm 325, such that deflection of the diaphragm 325 causes one or more portions of the conductor(s) 322 to elongate / lengthen, thereby altering the electrical resistance / impedance thereof. When the diaphragm 325 deflects, as shown in Figure 3B, electrical current and / or voltage through the conductive element(s) 322 may be measured to determine respective resistances / impedances thereof, thereby providing a measurement indicating a degree of deflection of the diaphragm 325; such deflection indicates the environmental pressure experienced by the diaphragm 325.

[0100] Figure 4A is a side view of a capacitive pressure sensor device 420 in accordance with one or more examples. Figure 4B is a side view of the capacitive pressure sensor 420 of Figure 4A, wherein a diaphragm 425 of the sensor is deflected in accordance with one or more examples. For capacitive pressure sensors having electrode-integrated diaphragm structures in accordance with the present disclosure, one or more conductive layers 422 may be deposited / applied on / to the thin- film nitinol diaphragm 425 to produce a capacitive electrode (e.g., anode). A corresponding electrode / plate 421 may be formed on an opposite-facing substrate 428, such that a cavity or other dielectric medium 429 is present between the electrodes / plates 422, 421. In some implementations, the electrode 421 provides a stationary / static electrode, while the diaphragm electrode 422 provides a flexible, dynamically-deflectable membrane electrode 422. With the area of such electrodes 422, 421 being fixed, the capacitance between the electrodes may be proportional to the distance(s) between them.

[0101] As shown in Figure 4B, inward / downward deflection / deformation of the diaphragm 425 may change the spacing between the conductors 421, 422 over at least a portion of the diaphragm 425, thereby changing the capacitance of the capacitor formed between the diaphragm electrode 422 and the base electrode 422. Such change in capacitance may be measured by coupling the sensor device 420 to a tuned circuit, for example, which may have a fundamental frequency that is proportional to the degree of deflection of the diaphragm 425 and electrode 422.

[0102] Any of the various devices shown in Figures 3A / 3B and 4A / 4B can have certain oxide and / or other insulator layers (e.g., high-k dielectric) formed on electrode components to provide increased capacitance, reduced leakage current, improved breakdown voltage, and / or allow for reduced electrode / device size.Docket No.: ADV-23598WO01 Thin-Film Deposition of Superelastic Metal Alloy (e.g., Nitinol) Layer(s)

[0103] Examples of the present disclosure advantageously provide solutions for hermetically and / or electrically bonding to vapor-deposited, thin-film nitinol (or similar) structures (e.g., sensor diaphragm structures). Such thin-film metal alloy structures can advantageously facilitate the design of devices that are relatively small in size, while providing sufficient and / or improved superelasticity, diaphragm sensitivity, and / or sealing characteristics. Furthermore, use of thin-film nitinol diaphragms in connection with examples of the present disclosure can facilitate integration of sensor electrodes with such diaphragm structures / stacks. In some cases, suitable and / or improved biocompatibility characteristics and / or relatively simplified manufacturing processes can be provided through thin-film nitinol layer / diaphragm deposition.

[0104] In some examples, sensor devices disclosed herein include plate structures having formed therein one or more deflectable diaphragms, as well as surrounding mechanical structure, wherein the plate is formed of thin-film vapor deposition. Such integration of the diaphragm(s) with at least some of the additional mechanical structure of a device can reduce the number of manufacturing steps / processes required for device fabrication, and furthermore can provide superior mechanical properties relative to certain non-integrated diaphragm solutions. Furthermore, integration of diaphragm and other mechanical structure of a device can reduce component count and process steps required to produce the resulting sensor packaging. With fewer components and areas requiring hermetic sealing, more robust protective housings can be produced that present a reduced risk of failure / leakage.

[0105] Certain examples of the present disclosure provide alternatives to wrought-metal machining, stamping, grinding, or the like, of sensor diaphragms or other structures in order to provide structures with reduced thicknesses, improved sensitivity, and suitability for conformal deposition / formation thereon. For example, processes for forming thin-file deposited metal alloy layers as described herein can provide the necessary precision and tolerances for micrometer-level layers, which can be difficult or impossible to produce using certain cutting and mechanical processes. In some implementations, physical vapor deposition processing of metal alloy structures as disclosed herein can produce nanometer-level precision and tolerance. Such structures may be advantageously formed using an ionized deposition process, rather than through stamping, welding, or other more complicated and / or inconsistent / error-prone processes.

[0106] Figure 5 is a block diagram showing a thin-film vapor deposition system 700 in accordance with one or more examples. Physical vapor deposition (PVD) and other vacuum deposition processes can be used to produce relatively thin films and coatings. In the system 500, a source material 530 (e.g., metal, nitinol) transitions from a condensed phase to a vapor phase 570Docket No.: ADV-23598WO01 and then back to a thin-film condensed phase 540 applied on / to a target substrate 520. Sputtering or evaporation may be implemented to produce the vaporized / plasma gas 570. The plasma gas 570 is deposited on the substrate 520 to form the layer 540 of the deposited source material. The vacuum chamber 510 may advantageously be devoid of air and particles that could otherwise interfere with the directed deposition onto the substrate 520.

[0107] Transformation from solid 530 to gas 570 can be achieved through the application of energy from an energy source 550. The energy source 550 may be any type of energy, including heat / thermal current, electrical current, and / or voltage potential relative to the potential 560 associated with the substrate 520. Energy may energize the source material 530 to produce the plasma form 570. The electric potential 560 relative to the source material 530 may serve to create a direction of the deposition flow 570 towards the substrate 520. Source material 530 may be positively charged in some cases, whereas the electric potential 560 of the substrate 520 may be negatively charged.

[0108] With respect to the various processes and devices disclosed herein, any type of deposition process may be implemented to produce any of the inventive metal stacks, including or as an alternative to physical vapor deposition. Examples may include cathodic arc deposition, in which a high-power electric arc is discharged at the target (source) material to blast away some into highly ionized vapor to be deposited onto the workpiece. For electron-beam physical vapor deposition implementations, the material to be deposited is heated to a relatively high vapor pressure by electron bombardment in a vacuum and is transported by diffusion to be deposited by condensation onto a relatively cooler workpiece. For evaporative deposition, the material to be deposited may be heated to a relatively high vapor pressure by electrical resistance heating in a vacuum. As another example, close-space sublimation can involve placing the source material and substrate in relatively close proximity to one another and radiatively heated. Pulsed laser deposition may be implemented by ablating the source material into a vapor using a high-power laser. Pulsed electron deposition may be implemented by ablating the source material to generate a plasma under nonequilibrium conditions using a highly energetic pulsed electron beam.

[0109] In some example examples, sputter deposition may be implemented, wherein a glow plasma discharge, which may be localized around the target substrate by a magnet, bombards the source material, thereby sputtering some away as a vapor for subsequent deposition. For sputtering applications, a magnetron may be employed that utilize strong electric and magnetic fields to confine charged plasma particles close to the surface of the sputter target. Other sputtering techniques that can be implemented include ion-beam sputtering, reactive sputtering, ion-assisted deposition, high-power impulse magnetron sputtering, gas flow sputtering, or the like.Docket No.: ADV-23598WO01 Bonded Sensor Encapsulation Variations

[0110] As described above, implantable pressure sensor devices can include a deflectable diaphragm lid comprising thin-film nitinol and / or other superelastic metal alloy bonded to a base substrate (e.g., ceramic, glass, or any other type of inorganic nonmetallic material), wherein the bonding provides a hermetic coupling between the nitinol and nitinol structures and / or an electrical interface. In such examples, deflection of the diaphragm portion(s) of the lid can produce an electrical change in the device that is readable and indicative of pressure conditions external to the device. For example, conductive resistor / strain-gauge trace(s) and / or capacitor electrode(s) can be formed on the diaphragm portion(s), such that deflection of the diaphragm(s) produces changes in electrical characteristics (e.g., capacitance, resistance) of the conductors. Although capacitor plate electrodes are disclosed in some contexts herein, it should be understood that any example disclosed herein is applicable also to resistive or piezoresistive conductor elements integrated with diaphragm stacks. For example, any of the capacitive sensor examples disclosed herein that are described as including flexible nitinol diaphragms with conformal capacitive plates / electrodes associated therewith can alternatively or additionally have resistive or piezoresistive sensor elements integrated / associated with the deflectable nitinol diaphragm.

[0111] Various electronic / conductive layers, components, and / or elements may be added to a diaphragm structure (e.g., stack) including a thin nitinol layer, thereby enabling the integration of passive and / or active electrical elements with relatively thin diaphragm structures. The application of electrical and / or insulative elements, such as conductive layers configured to serve as capacitive plates / electrodes in an electrical circuit, and associated dielectrics, to a nitinol or other thin-film diaphragm can be implemented through chemical or physical vapor deposition, sputtering, masking / etching, photolithography, screen / inkjet printing, electroplating, epitaxy, thermal oxidation, atomic layer deposition, anodization, or the like.

[0112] Figure 6 shows a side cross-sectional schematic diagram of a sensor device 620 having a capacitive electrode 622 structurally conformal with a thin-film (e.g., less than 20 µm in thickness, such as between 5µm–10µm), superelastic diaphragm 625. As with any deflectable diaphragm layer(s) disclosed herein, the diaphragm layer(s) 625 may comprise any type of deposited thin-film, super-elastic metal material(s). Although deflectable diaphragm layers are described in certain contexts herein as comprising nitinol, it should be understood that such diaphragm layers can include any type of deposited (e.g., physical vapor deposition) thin-film (e.g., less than 15 µm), superelastic metal, including alloys such as nitinol (NiTi), NiTiCu, and the like. The utilization of physical vapor deposition of nitinol, titanium, gold, and / or other materials, as described in detail above, provides a basis for producing sensor diaphragm / electrodeDocket No.: ADV-23598WO01 stacks / structures as disclosed herein that produce low-profile sensors suitable for implantation in the human body.

[0113] Transducing pressure inside the human body into capacitance can require relatively high, biocompatible, and stable diaphragm electrodes. To achieve the required compliance for a minimally-invasive implant device, constraining the thickness of a deflectable diaphragm stack / structure to a dimension in the order of microns can produce a suitable product. Furthermore, in order to achieve relatively large capacitance values measurable using either passive or active circuitry, relatively large diaphragm surface area may be necessary or desirable. However, such parameters can conflict with goals of achieving a minimally-invasive implant due to constraints of the lateral dimensions typically associated with such devices. The use of nitinol and similar materials for flexible diaphragm substrates on which capacitive electrodes can be disposed can provide a biocompatible layer that meets the above requirements and allows for production of low- profile, high-elasticity / capacitance sensor elements.

[0114] The device 620 includes an integrated capacitive electrode 622 (or resistive conductor for resistor applications) on a superelastic diaphragm 625. The electrode 622 can be part of a flexible stack-up 627 that serves as a capacitive electrode, without the need for additional transfer of pressure from the diaphragm 625 to a separate sensor element. In the example of Figure 6, as with other examples disclosed herein, the sensor 620 can be considered a dry capacitive sensor due to the absence of pressure-transmitting fluid (see Figure 7), wherein the encapsulation of the sensor 620 (e.g., the outer nitinol shell / layer) itself forms a component of the pressure-transducing element, namely one plate / electrode of the capacitor element. That is, the outer nitinol layer / shell 625 provides both biocompatible / hermetic encapsulation, as well as pressure transmission into sensor electrical signals due to the integration therewith of the capacitive electrode 622.

[0115] The diaphragm electrode 622 combines with the corresponding electrode 621 to form a capacitor electrically coupled to the electrical circuitry 634 of the sensor 620. The capacitor plates 621, 622 can be electrically coupled to the resonance circuit of the circuitry 634 via certain electrical leads / connectors 624a, 624b, which may be integrated with the structure of the base substrate / structure 605 in any suitable or desirable manner, such as though various traces, vias, or the like. The nitinol diaphragm 625, which may have associated perimeter sidewalls / projections 628, can be physically sealed to a base structure / substrate 605 and a connection / joint 623 to provide a hermetically-sealed volume / space 629 between the capacitor plates 621, 622. The base substrate / structure 605 may comprise ceramic, glass, nitinol, or other metal or material. The volume 629 may comprise a vacuum volume.Docket No.: ADV-23598WO01

[0116] The nitinol layer 625 provides a thin, compliant, superelastic, biocompatible externally-facing shell for the device 620. Furthermore, the thin-film diaphragm 625 provides relatively large deflections and commensurately large variation in capacitance and signal amplitude, while remaining elastic. The conductor layer 622 may advantageously be insulated from the memory-metal structural diaphragm 625, to thereby electrically isolate the nitinol layer 625 from the electrical circuit of the capacitor 622 / 821. That is, the nitinol layer 625 may serve as a substrate for deposition / application of the conductor layer 622, wherein the conductor 622 is electrically isolated from the diaphragm 625 by the insulator layer 626a (e.g., oxide).

[0117] Compared to sensors comprising deflectable capacitive sensor diaphragms formed of layers of glass, use of thin-film nitinol or other superelastic metal as described herein can provide various benefits. For example, when comparing the elasticity of nitinol and glass in the context of a deflectable diaphragm, nitinol can be considered to provide superior superelasticity properties. Generally, nitinol can undergo substantial elastic deformation and revert to its original shape upon stress removal, which can be beneficial for applications demanding considerable degree and number of deflections. Conversely, glass, being a relatively brittle material, generally exhibits relatively low elasticity, such that it does not tolerate extensive strains efficiently and can fracture under high stress. Furthermore, the strength of glass substrates can depend on the surface finish of the glass, wherein flaws or cracks on the surface can act as stress concentrators, which can compromise its structural strength. Conversely, the nitinol diaphragm 625 can advantageously endure high stress and strain without succumbing to permanent deformation, whereas glass, due to its brittle nature, can be prone to catastrophic failure when subject to stress.

[0118] The thin-film nitinol diaphragm 625 provides additional benefits compared to glass diaphragms, including the ability to form shaped surfaces, such as corrugations or extrusions, in the diaphragm layer, which can increase the effective surface area of the diaphragm 625. Furthermore, formation of corrugations, extrusions, and / or other surface-topological features in diaphragm layer(s) of examples of the present disclosure (e.g., the diaphragm layer 625) can increase the linear deflection regime / sensitivity of the diaphragm. Glass, on the other hand, presents certain challenges when it comes to forming shaped surfaces therein due to the structural brittleness / fragility thereof and the lack of available processes to produce surface features precisely in glass surfaces. Nitinol can be tuned mechanically in ways that glass and other diaphragms cannot, and provides greater deflection to produce greater change in capacitance when implemented with conformal electrode layers described herein that cover substantial areas of the nitinol diaphragm. For corrugations in diaphragm layer(s), such three-dimensional features may be formed by depositing thin-film metalDocket No.: ADV-23598WO01 on a surface / mold / mandrel having such surface features. With respect to fractal-like and / or porous surface features, formation of the same may involve masking, electroplating, or the like.

[0119] One or more of the dielectric layers 626a, 626b may comprise high-k dielectric material. The presence of the dielectrics 626, in addition to electrically isolating the plates 622, 621 from the physically proximate substrates 625, 605 to avoid corruption of sensor signals, can serve to protect the electrical circuit associated with the electrodes 621622 from circuit break-down from capacitance between the plates 622 and the substrate(s) 625, 605, which may be at least partially conductive, as in the case of nitinol. Use of high-dielectric materials can impede the creation of a capacitance between the nitinol layer 625 and the electrode layer 622, reducing unwanted stray capacitance that might otherwise negatively impact the circuit.

[0120] The capacitor electrodes 621, 622 are electrically coupled to certain electrical circuitry 634, which may include an antenna configured to facilitate wireless transmission of sensor signals and / or signals derived therefrom. In some implementations, the circuitry 634 comprises active circuit components, including amplifiers or the like configured to convert capacitance of the plates 621, 622 into readable signals. Collectively, the capacitor formed by the plates 621, 622 can be electrically coupled to the antenna in a manner such that changes in the capacitance of the capacitor produces resonance changes in the antenna, wherein such resonance of the antenna can be decoded to determine pressure levels causing the resulting capacitance.

[0121] The bond(s) 623 can advantageously provide an electrical interface through which the conductive line 632 can pass through to the base structure. That is, the bond 623 can serve as both a hermetic seal as well as an electrical interface. The bond 623 may have the form of any bond / joint described herein, and may advantageously include one or more layers of gold-tin (AuSn), which may facilitate bonding / melting at temperatures below the transition temperature of the nitinol layer(s) (e.g., the diaphragm 625). Pressure Sensors Utilizing Pressure-Transmission Media

[0122] Certain pressure sensor solutions can include sensors encapsulated in a diaphragm- integrated shell / housing with a contained transmission fluid disposed between the external flexible diaphragm and an internal capacitive sensor device. Figure 7 shows a side cross-sectional schematic diagram of a sensor device 720 having a pressure-transmitting medium 752 in accordance with one or more examples.

[0123] The pressure-transmitting medium 752 contained within the housing of the device 720 may comprise incompressible fluid, such as oil or gel. Unlike the example of Figure 6, the device 7 includes a separate pressure sensor device / element 710, which includes its own deflectable diaphragm apart from the diaphragm 725 of the housing.Docket No.: ADV-23598WO01

[0124] The area enclosed by the housing 733, which includes the deflectable diaphragm 725, contains the sensor 710 (e.g., MEMS sensor). The pressure-transmission fluid or other medium (e.g., oil, gel, epoxy) 752 is disposed about the sensor element 710, such that external pressure causing inward deflection of the diaphragm 725 is transferred to the pressure sensor 710 for sensing thereof. Pressure conditions external to the enclosure 733 can cause inward deflection of the diaphragm 725 in a manner as to exert pressure on the sensor element surface / diaphragm. The pressure-transmission medium 752 may comprise an incompressible fluid or medium in some examples. Alternatively, the medium 752 may be compressible, wherein deflection of the diaphragm 725 may cause a reduction in volume of the internal chamber of the enclosure 733, thereby compressing the fluid / medium and resulting in increased pressure within the enclosure 733that is translated to the sensor element 710.

[0125] The pressure-transmission medium 752 is sealed within the housing 733 by the bond(s) 723 that seals the diaphragm structure 770 to the base structure 780 and provides the hermetically-sealed housing 733 for the sensor element 710. The diaphragm structure 770 can include the thin-film diaphragm 725, as well as perimeter stack-up(s) 728, which may also comprise nitinol and / or other material(s) / layer(s) for bonding to corresponding structure 738 associated with the base 780. The sensor element 710 can be electrically coupled to certain electrical circuitry 734, which may include an antenna configured to facilitate wireless transmission of sensor signals and / or signals derived therefrom. In some implementations, the circuitry 734 comprises active circuit components, including amplifiers or the like configured to convert capacitance of the plates 621, 622 into readable signals.

[0126] The bond(s) 723 can advantageously provide an electrical interface through which the conductive line 732 can pass through to the base structure. That is, the bond 723 can serve as both a hermetic seal as well as an electrical interface, which may allow for the integration of conductors or other electrical elements with the diaphragm structure 770. The bond 723 may have the form of any bond / joint described herein, and may advantageously include one or more layers of gold-tin (AuSn), which may facilitate bonding / melting at temperatures below the transition temperature of the nitinol layer(s) (e.g., the diaphragm 725). Hermetically Bonding to Nitinol Using Gold-Tin Layer(s)

[0127] Nitinol, a shape-memory alloy composed of approximately equal parts of nickel and titanium, possesses certain beneficial properties due to its crystalline structure and the phase transitions it undergoes. Such properties include superelasticity and the shape-memory effect. However, exposure to high temperatures can have impact nitinol’s distinctive characteristics due to causing changes in the material’s crystalline structure. For example, when nitinol is exposed toDocket No.: ADV-23598WO01 temperatures beyond its austenite finish temperature, it can undergo thermal transformation. Repeated exposure to high temperatures can cause the alloy's crystalline structure to gradually change. Even exposure to relatively low temperatures for long periods of time can cause such changes. Heating nitinol beyond its transformation temperature, such as in connection when melting bonding material for the purpose of bonding to the nitinol material, can lead to loss or reduction in superelasticity, change in transformation temperatures, and / or microstructural changes. Resulting recrystallization and / or grain growth in the material’s microstructure can affect its mechanical properties, such as strength and hardness. Furthermore, nitinol’s shape-memory effect relies on the generation of recovery stress during the phase transition. High-temperature exposure can reduce the alloy’s ability to generate this stress, impacting its shape recovery capabilities.

[0128] Given nitinol’s temperature constraints, traditional joining techniques like welding and brazing can pose challenges when used on nitinol. This is exacerbated when the joint needs to create a hermetic seal. While welding nitinol is possible, it typically requires precise process refinement adapted to the specific designs usually done by subject matter experts. Furthermore, welding can limit the material selection for welding to the nitinol to other metals similar to nitinol.

[0129] Examples of the present disclosure advantageously implement a gold-tin (AuSn) alloy to form a hermetic seal and / or an electrical joint between thin-film (e.g., physical-vapor- deposited) nitinol and a dissimilar material (e.g., ceramic, glass, printed circuit board). Gold-tin can provide a desirable bonding agent due to its relatively low melting temperature, high thermal / electrical conductivity, and resistance to fatigue, corrosion, and creep. The low melting temperature advantage offered by AuSn is advantageous for certain sensor applications disclosed herein as it preserves the unique properties of nitinol while hermetically joining it to dissimilar materials of functional substrates. By avoiding elevated temperatures, the gold-tin alloy can effectively safeguard the integrity of nitinol’s superelasticity and shape-memory characteristics.

[0130] In addition to preserving the mechanical properties of nitinol, the gold-tin hermetic bonding method presented herein offers advantages in facilitating electrical connectivity between nitinol and other circuit elements. Such features can be particularly beneficial in applications where mechanical and electrical integration are important or essential, such as medical implants, sensors, actuators, and various other electronic devices. Gold-tin layer(s), as used in example joining / bonding configurations disclosed herein, can further provide relatively low reactivity, providing resistance to corrosion and degradation when exposed to bodily fluids, promoting an implant's long-term integrity. Furthermore, with both gold and tin being biocompatible materials capable of deposition using physical vapor deposition (PVD) technology or other similar process (e.g., sputtering / e-beam evaporation / electrodeposition), thin-film gold-tin joining layers ofDocket No.: ADV-23598WO01 examples disclosed herein can be deposited using such processes, which can produce stoichiometrically precise alloying of the gold and tin metals without impurities. Finally, certain types of gold-tin joining / bonding features as disclosed herein can be implemented using semiconductor industry standard flip chip bonding processes / machinery. For example, gold-tin features can be flip-chip-bonded by melting the gold-tin form(s) without the use flux or corrosive additives that could ultimately cause biocompatibility concerns for chronically implanted devices.

[0131] Figures 8A and 8B show front and back perspective views of diaphragm lid / structure 870 of a sensor device, the lid / structure comprising nitinol and / or other superelastic material in accordance with one or more examples. Figure 9 shows a base structure 980 for the sensor device in accordance with one or more examples. Figures 10A and 10B show perspective and cross-sectional views, respectively, of the combined sensor device 1000 including the diaphragm lid / structure 870 physically coupled to the base structure 980 in accordance with one or more examples. The description below may be understood with respect to any of Figures 8A, 8B, 9, 10A, and 10B.

[0132] The structure / plate 870 may provide the structure for one side / plate of a pressure sensing capacitor, wherein certain contacts / connections 871 of plate 870 may facilitate electrical connection between electrodes 822 and a paired electrode base structure (see Figure 9), wherein the plate 870 is joined / bonded to counterpart sensor structure using gold-tin (AuSn) alloy layer(s) in a manner as to provide hermetic sealing thereof. References herein to components that are ‘bonded’ to one another may be understood to be joined in any manner, such as welding, adhesive-bonding, or the like. The contacts 871, which may be formed at least in part of AuSn, can interface with the electrode(s) 822 through direct physical contact or a routing connection through trace(s) on the nitinol substrate / layer 821. Although the diaphragm plate 870, as well as certain similar devices / structures disclosed herein, is shown and described as having an oval shape, it should be understood that such devices / structures can have any suitable or desirable shape, such as rectangular, circular, or similar shapes. As with any of the other examples disclosed herein, the active capacitive sensors can occupy the entire surface of the plate 870, or most of the surface, or the capacitive sensors can occupy multiple smaller diaphragm areas 825a, 825b, 825c (collectively or individually ‘825’), as shown in Figures 8A and 8B. As shown, the diaphragm plate 870 and / or associated sensor devices / components can have an oval shape resembling the union of two semicircles on opposite sides of a rectangle (referred to in some contexts as an ‘obround’ shape), providing a shape evoking the likeness of a speed skating rink or an athletics track. In some contexts, the shape of the plate / sensor 870 may be referred to as a “stadium” shape, “disk” shape, or an elongated oval.Docket No.: ADV-23598WO01

[0133] The diaphragm plate 870 includes a sheet / layer of superelastic thin-film nitinol 821, wherein the nitinol may be deflectable in a dimension normal to the surface of the layer(s) 821 in one or more areas, such as at least in the areas 825 corresponding to the capacitor electrodes 822a, 822b, 822c (collectively or individually ‘825’). In terms of processing, the nitinol layer 821, including the diaphragm portion(s) 825 and the area 829 outside of the diaphragms 825, can be deposited on a substrate using physical vapor deposition or other deposition process. The lid structure 870 can include a perimeter sealing flange 872, which is raised above (with respect to the orientation of Figure 8A) the nitinol sheet / layer 821. The perimeter sealing flange 872 can comprise a curb, lip, rim, or similar structure that is configured to be physically joined to a base to provide a spacing between the nitinol layer 821 and the base. The flange 872 can be formed at least in part of nitinol formed / deposited on the layer 821 to produce a raised structure, as shown. In some examples, one or more layers of gold-tin (AuSn) is disposed on or adjacent to the nitinol flange 872 to provide a bonding agent for bonding the lid 870 to the base 980 (see Figure 9). Perimeter bonding / sealing portions of thin-film nitinol diaphragm structures may generally be non-deflectable portions / regions of the nitinol layer, as such portions / regions are bonded to at least partially rigid structures and not free to bow inward in response to pressure changes, unlike the diaphragm portions / regions 822.

[0134] An insulator / oxide layer(s) 826 may be formed or deposited in any suitable or desirable manner on the nitinol 821. For example, the insulator layer(s) 826 may be formed only in the areas of the diaphragms 825. The nitinol layer 821 may have a thickness d1 of approximately 5 µm, or any other value less than 10 µm, for example. Although described as ‘thin-film’ diaphragm layers, it should be understood that flexible diaphragm layers disclosed herein may have a thickness of up to 20µm, or greater in some implementations. The electrode metal 822 may be applied on the oxide layer(s) 826, and likewise may be confined to within the areas of the diaphragm(s) 825. Although three circular diaphragms 825 are shown, it should be understood that diaphragm plates / structures disclosed herein may have any number, configuration, or shape of diaphragms.

[0135] In some implementations, the nitinol layer 821 is materially different in one or more respects in the diaphragm areas 825 compared to the areas 829 outside of the diaphragms. For example, the diaphragm portions 825 may be thinner than the areas 829 outside of the diaphragm. Additionally or alternatively, certain shape or surface features of the diaphragm areas 825 may distinguish the diaphragms from the rest of the nitinol sheet / layer. For example, corrugations, protrusions, indentations, impressions, or other features may define an outer perimeter of the diaphragm areas 825 and / or other areas or features of the diaphragms 825.Docket No.: ADV-23598WO01

[0136] The perimeter flange(s) 872 can have a layer of gold-tin alloy (AuSn) 878 disposed thereon that provides a sealing contact surface 879. Furthermore, the electrical contacts 871 may comprise AuSn. The conductivity of the nitinol layer 821 and side support structures / flanges 871 may be significantly lower than that of the electrode conductor 822 and the AuSn layer(s) 871, 878, which may allow for electrical interfacing through the AuSn forms without electrical shunting through the adjacent nitinol. Use of AuSn at the top (with respect to the orientation of Figure 8A) of the contact flange(s) 872 can advantageously allow for electrical contact onto electrical contacts implemented on / in the vapor-deposited nitinol 821, while also providing a hermetic seal. Furthermore, as nitinol generally cannot withstand high temperatures, AuSn can be suitable for positioning and melting in proximity of the nitinol due to the AuSn being meltable at temperatures below the transition temperature of the nitinol.

[0137] In some implementations, electrical conductor contacts 871, which can comprise AuSn, are applied / formed on the electrode layer(s) 822, such that the forms 871 are in electrical contact / communication therewith. For example, the electrical contacts 871 can be in physical contact with the electrode layer(s) 822. The contacts 871 may provide electrical connections between the capacitor plates 822 and a physically-coupled cathode structure (see Figures 9, 10A, 10B) when the diaphragm plate 870 is joined (e.g., bonded) thereto, thereby incorporating the diaphragm electrode(s) 822 in the associated capacitive resonance circuit of the sensor device. The electrical contacts 871 may have the form of a raised flange, curb, lip, rim, or similar structure, and may generally provide a physical contact surface for electrically interfacing with a counterpart surface 991 (see Figure 9) of a base structure.

[0138] In some implementations, the electrical contacts 991 and / or 871 may comprise electrically-conductive AnSn solder, or the like, or other type of material formed as a flange that projects in a dimension normal to a plane of the plate 870, substrate 980, and / or device 1000. The contacts 871 may be formed in any suitable or desirable way, such as through vapor deposition, sputtering, or other application process.

[0139] In some implementations, perimeter gaps 877 may separate adjacent portions / lengths of the conductors 871, which may generally run along the perimeter of the electrodes 822. The gap(s) 877 may provide a pathway for gas to be removed from the space within the contacts 871 to allow for vacuum sealing of the chamber 1009. In some examples, the contact(s) 871 form a continuous perimeter around the electrode(s) 822 without the presence of circumferential gap(s), which may allow for the implementation of independent and / or isolated capacitors.

[0140] The perimeter-sealing structure 872 may be applied to and / or around the perimeter of the plate 870, such as directly to the thin-film metal (e.g., nitinol) layer 821. The perimeter structureDocket No.: ADV-23598WO01 872 may have the form of a raised flange, curb, lip, rim, or similar structure, and may generally provide a sealing contact surface 879 for sealing against a counterpart surface of the base structure 980. The perimeter structure 872 may project in the direction normal to the surface of the nitinol layer 821 to provide a structure to offset the capacitor electrode(s) 822 from the base 980. For example, the top surface 879, which may comprise gold-tin, may be configured to be bonded to a corresponding surface or feature 992 of the base structure 980 of the sensor device 1000.

[0141] The sensor base 980 can have formed thereon capacitive electrodes 981, which may each be paired with a corresponding one of the capacitive electrodes 822 of the diaphragm plate 870, such that when the plate 870 is coupled with the base 980, a variable capacitance, based at least in part on the deflection state of the diaphragm 825, is present and measurable between the plates 822, 981. The electrode(s) 981, which may have a fixed, non-deflecting attachment / structure, can combine with the deflectable electrode(s) 822 to form one or more variable capacitors having capacitance that varies in accordance with the deflection state of the electrode(s) 822. The static nature of the base electrodes (e.g., cathodes) 981 can be provided by the coupling and / or integration thereof with a rigid, or semi-rigid, substrate structure 901. Any of the electrodes 822, 981 may have an elliptical (e.g., circular) shape, as shown.

[0142] The base 980 may further comprise certain electrical contacts 991 configured to contact / bond to the corresponding electrical contacts 871 of the diaphragm plate 870. That is, the contacts 991 of the base 980 may be electrically isolated from the capacitor plates 981, but electrically coupled to the electrodes 822 via the contacts 871, which may be bonded together at coupling interfaces 1007, as shown in Figure 10, when the diaphragm plate 870 is bonded to the base structure 980. While the contacts 991 may be configured in such a way that they do not directly contact the capacitor plates 981, through various electrical interconnections, both the capacitor plates 981 and electrical contacts 991 can ultimately be connected in the same capacitive residence circuit to allow for the measurement of capacitance between the plates 822, 981. The static / fixed capacitor electrodes 981 may be axially aligned and / or centered with the dynamic capacitor electrodes 822 when the pieces 870, 980 are bonded / coupled together. The electrical contacts 991 may have the form of a raised flange, curb, lip, rim, or similar structure, and may generally provide a contact surface for electrically interfacing with a counterpart surface 871 of the diaphragm plate 870.

[0143] An area of physical contact and sealing between the diaphragm plate 870 and the base plate 980 may be via perimeter projections 992. The dimensions of the electrical contact flanges 991, 872 may be designed and set to known distances to offset the capacitive electrodes 822 and 981 a desired distance. For example, the opposing flange contacts 991 and 871 can be inDocket No.: ADV-23598WO01 physical contact to create both the electrical connection between the plates 870, 980, as well as defining the precision of the offset of the electrodes 981, 822. The contact flanges 992,1372 can provide the perimeter seal for the hermetic sealing of the device 1000. The perimeter structure 992 of the base 980 may advantageously span the entire perimeter of the base substrate 901, such that, when brought into tight bonding contact with the perimeter structured 872 of the diaphragm plate 870, the connection interface between such perimeter structures can provide a hermetic seal protecting the internal cavity 1009 from the external environment. The internal cavity 1009 can be filled with air or other inert gas, or may be vacuum sealed. In examples in which the cavity 1009 comprises a vacuum, the sensor can provide an absolute pressure sensor. Alternatively, some examples include the presence of a gas in the 1009 cavity / volume, which may be used as a relative pressure sensor implementation. Furthermore, the cavity 1009 can provide a venting path to a large volume. Such larger venting volume can advantageously reduce the air compression resistance, while allowing for the cathode and anode to be placed very close to each other with minimal / little volume between the electrodes.

[0144] The substrate 901 of the base structure 980 (e.g., cathode structure) can comprise ceramic, glass, or any other suitable material, whether rigid or flexible. For example, the substrate 901 can comprise and / or have associated therewith a printed circuit board and / or a dedicated integrated circuit that contains certain circuitry configured to handle the capacitance signal of the capacitor(s) 1095. The base substrate 901 may include certain electrical connections configured to facilitate proper electrical coupling of the respective capacitor plates 822, 981. For example, certain vias or other connections may connect through at least a portion of the thickness of the substrate 901.

[0145] In some implementations, the deflection of the diaphragms 825 are independently measured to provide separate sensor signals, providing additional levels of sensitivity. For example, the different capacitors 1095 may be tuned to have different mmHg / fF curves (or curves based on other units, such as change in electrode displacement (Δz) per mmHg, allowing for accounting for (e.g., zeroing-out of) tissue growth that may accumulate disproportionately on one capacitor diaphragm 825 versus another. In the example of Figures 8–10, the three capacitors 1095 can work in unison to serve as a single capacitor sensor, or they can be separated by certain electrical contacts / connections to make three separate capacitors. The capacitor electrodes 822 and / or the capacitor electrodes 981 may comprise gold in some examples.

[0146] The joint / bond 1005 between the lid structure 870 and the base structure 980 can be implemented using one or more layers of gold-tin (AuSn) and / or gold (Au) to produce a relatively hard / good joint / bond that provides both a hermetic seal and an electrical interface between theDocket No.: ADV-23598WO01 nitinol material of the lid 870 and the non-nitinol material of the base 980. As interfacing with nitinol (e.g., thin-film nitinol) and similar materials is generally challenging due to the molecular structure and temperature response, use of the eutectic metal alloy AuSn can allow for effective bonding while protecting the molecular integrity of the substrate. Example AuSn joining / bonding techniques of the present disclosure can be particularly useful for sensor application, where a sensing mechanism is implemented that involves transduction and / or electrical coupling between nitinol and non-nitinol components, as the AuSn joint / bond can provide biocompatibility and electrical pathways between components.

[0147] Generally, when nitinol is exposed to high temperatures, or even to lower temperatures for protracted periods, the material can be rendered an amorphous material rather than remaining superelastic. Gold-tin alloy (AuSn) can advantageously become eutectic in certain compositions, such that the alloy melts at a relatively low temperature (e.g., as low as 280° C), thereby allowing for melting thereof to form joint / bonds at temperatures that do not disturb the nitinol’s crystal structure. Therefore, the AuSn-nitinol bonding as described in detail below can be useful for bonding to nitinol structures as in the bond 1005 described above with respect to Figures 8–10, as with other examples disclosed herein, to create a hermetic and electrical joint with nitinol structures.

[0148] Figures 11A and 11B show front and back perspective views of a sensor lid / diaphragm structure 1170 in accordance with one or more examples. The lid / structure 1170 may be used in an alternative sensor design in which the capacitor electrodes are not deposited conformally onto the nitinol layer(s), but rather the lid 1170 contains one or more internal sensor device chambers having disposed therein one or more sensor devices and pressure-transmission media (e.g., oil, gel) configured to transfer deflection of the nitinol diaphragm(s) to the internal sensor device(s); examples relating to such pressure-transmission-fluid sensor devices are described in detail above.

[0149] The lid 1170 includes a thin-film nitinol layer covering the diaphragm areas. And some examples, the lid structure 1170 can include built-up NiTi material 1164 around the diaphragms 1125, where in the raised can structure 1164 and provide at least part of a cylindrical or other -shaped volume / space, wherein such space may be filled with pressure-transmission fluid when the lid structure 1170 is assembled with a base structure to form a sensor device. In some implementations, no raised extra-diaphragm structure is formed around the diaphragm (as) 1125. For example, any cylinder or other volume / space in which pressure of transmission fluid is disposed may be associated with the base structure 1280 exclusively.Docket No.: ADV-23598WO01

[0150] The lid structure 1170 can include a perimeter sealing flange 1172, which is raised above (with respect to the orientation of Figure 11A) the nitinol sheet / layer 1121 and / or the thicker nitinol structure (if implemented) 1164 around the diaphragm(s) 1125a, 1125b, 1125c. The perimeter sealing flange 1172 can comprise a curb, lip, rim, or similar structure, as described above in connection with other example(s), that is configured to be physically joined to a base to provide a spacing between the nitinol layer(s) 1121, 1164 and the base. The flange 1172 can be formed at least in part of nitinol formed / deposited on the layer 1121 to produce a raised structure, as shown. In some implementations, the perimeter flange 872 is flush with the raised form(s) 1164 around the diaphragm. For example, the lid may include the thin-film diaphragm layer(s) 1121 and raised outer structure 1164, with no additional raised nitinol structure. Rather, the bonding agent (e.g., AuSn) may be applied to such integrated structure 1164, such as in the form of a preform structure placed against the structure 1164 / 1172.

[0151] In some examples, one or more layers of gold-tin (AuSn) is disposed on or adjacent to the nitinol flange 1172 to provide a bonding agent for bonding the lid 870 to the base 980 (see Figure 9). The AuSn layer(s) may be deposited using sputtering, vapor deposition, or other process(es), or may be a solid pre-form structure having, e.g., a stadium shape as shown, or other shape, which is physically placed against the nitinol structure, with or without intermediate oxide disposed between the two materials.

[0152] Figure 12 shows a base structure 1280 for a capacitive sensor device 1300 in accordance with one or more examples. Figures 13A and 13B show perspective and cross-sectional views, respectively, of the sensor device 1300 including the diaphragm lid / structure 1170 physically coupled to the base structure 1280.

[0153] The sensor base 1280 can have one or more cylinders or other volumes / spaces 1209 in which sensor devices 1210 may be placed / disposed, such that when the lid 1170 is coupled with the base 1280, a fluid medium 1252 (e.g., an incompressible fluid, such as oil or gel) can be placed in the can spaces 1209 around the sensors 1210. In such configuration, pressure conditions / readings associated with the sensor device(s) 1210 can be affected by and indicative of the deflection state of the respective diaphragm 1125. The cans 1209 can have raised flanges 1391 thereabout, which may seal against corresponding structure of the lid 1170 to provide a fluid-tight chamber for pressure sensing. Although a secondary seal 1391 is shown, it should be appreciated that the device 1300 may not include such seal(s), but rather the outer hermetic seal 1305 may serve to contain the pressure transmission fluid medium. For example, the cavity 1309 may not be present in some examples.Docket No.: ADV-23598WO01

[0154] An area of physical contact and sealing between the diaphragm plate 1170 and the base plate 1280 may be via perimeter projections 1392. When the base contact 1392 is brought into tight bonding contact with the diaphragm plate 1170, the connection interface 1305 can provide a hermetic seal protecting the internal structure / components from the external environment.

[0155] The substrate 1201 of the base structure 1280 can comprise ceramic, glass, or any other suitable material, whether rigid or flexible. For example, the substrate 1201 can comprise and / or have associated therewith a printed circuit board and / or a dedicated integrated circuit that contains certain circuitry configured to handle the capacitance signal of the capacitor(s). The joint / bond 1305 between the lid structure 1170 and the base structure 1280 can be implemented using one or more layers 1178 of gold-tin (AuSn) and / or gold (Au) to produce a relatively hard / good joint / bond that provides a hermetic seal, and possibly an electrical interface as well, between the nitinol material of the lid 1170 and the non-nitinol material of the base 1280.

[0156] While Figures 10B and 13B show diaphragm lid structures and sensors implemented on one side of a base substrate, it should be understood that any of the sensor and bonding features disclosed herein may be implemented in sensor devices having dual-sided sensor features. Figures 14A and 14B show perspective and cross-sectional views, respectively, of a dual-sided sensor device 1400 in accordance with one or more examples. The various illustrated and referenced features of Figures 14A and 14B can be understood with reference to the description of Figures 8A, 8B, 9, 10A, and 10B above. Although the dual-sided sensor device 1400 is shown as a sensor device having conformal capacitive electrodes formed on the nitinol diaphragms, it should be understood that dual-sided sensor devices can be implemented in connection with pressure- transmission-fluid can / chamber embodiments as well.

[0157] Figures 15A and 15B show exploded and assembled / bonded views, respectively, of a material stack-up bond / joint 150 capable of producing a hermetic seal between a thin-film nitinol (or other metal) layer 152 and a dissimilar substrate (e.g., ceramic, glass) using a gold-tin alloy filler in accordance with one or more examples. The bond / joint 150 can be used to bond nitinol (or other similar superelastic material) to dissimilar (e.g., non-nitinol) substrate(s) of any example disclosed herein. Various examples of present disclosure are described in the context of gold-tin bonds to nitinol. However, it should be understood that examples of gold-tin bonds disclosed herein can be implemented to bond to any sputtered material, and references to nitinol layers / substrates herein can be understood to refer to implementations using other sputtered materials. Such materials can comprise any thin-film metal, such as titanium, tantalum, or the like. Example sputtered materials can be deposited using vapor deposition, electrodeposition, thermal deposition, or any process wherein a solid substrate is converted to a gaseous form and re-solidified and applied on a substrate.Docket No.: ADV-23598WO01 Additionally, alloys other than nitinol may be bonded to using gold-tin bonding, such as kovar (nickel-cobalt ferrous alloy), which can provide desirable hermetic sealing. Such bonded-to layers / substrates can be associated / integrated with thin-walled pressure transduction structures.

[0158] 2) Ti is a reasonable alternative material (biocompatible) with some advantages and disadvantages. If we can claim the broader sputtered process creating a diaphragm (full range of biocompatible low-permeability metals including Ti, stainless steel, Nitinol) for pressure transduction within the body (both transmission fluid and dry-cap configurations), and joined with AuSn then we will cover what we are intending to protect

[0159] The stack-up 150 includes a nitinol layer / form 152 (or similar superelastic material) bonded to a non-nitinol material 158 (e.g., ceramic, glass, PCB) using one or more layers 155 of eutectic gold-tin (AuSn) alloy or other eutectic metal. In some examples, the AuSn layer(s) 155 can comprise about (e.g., within 5%) 80% gold (Au) and 20% tin by weight. Such composition can provide a eutectic alloy, wherein the material melts or solidifies at a single temperature, like a pure metal, rather than over a range of temperatures like many alloys. The eutectic temperature for the AuSn layer 155 may advantageously be relatively low, such as around 280°C (536°F), which is significantly lower than the melting points of pure gold (1064°C or 1947°F). The AuSn layer, which may be a preform layer, can have a thickness of about 25 µm, or other thickness.

[0160] The intermediary gold-tin (AuSn) layer(s) 155 is interposed between the nitinol 151 and base 159 structures and can provide desirable thermal and electrical conductivity features, wettability, and resistance to corrosion for use in chronic implant devices. Furthermore, AuSn as composed in examples disclosed herein can be bonded using heating / soldering techniques, where the high thermal conductivity of the material helps dissipate heat and the high electrical conductivity can promote reliable electrical connections. The relatively low eutectic point of the AuSn 155 can also minimize thermal stresses during bonding / soldering, which can be protect sensitive sensor components as well as avoid molecular deformation of the adjacent nitinol 152.

[0161] The bond line of a sensor implant housing, as described above, can have layering similar to that shown in Figure 15B, which shows the layers combined together to produce a hermetic and / or electrically-conductive seal. In some examples, the layer(s) 155 of gold-tin (AuSn) are deposited (e.g., vapor-deposited or placed as a preform structure) on the thin-film nitinol 152 and / or base substrate 158, with or without intermediary seed layer(s) 154, 156 of gold and / or other metal. The intermediary gold 154, 156 can be included to enhance the bonding, compatibility, and / or functionality between the nitinol 152 and the glass / ceramic (or other substrate) 158, which may not directly adhere or interact well enough with each other for the purposes of the bonded device.Docket No.: ADV-23598WO01

[0162] The gold-tin (AuSn) layer 155 hermetically joins the nitinol 151 and ceramic / glass 159 stacks, each of which may have a seed layer 154, 156, such as a gold seed layer. The gold layer(s) 154, 156 can have a thickness of less than 1 µm. The gold seed layer 156 can be lithographically patterned / sputtered onto the substrate 158. In some implementations, the AuSn layer(s) 155 can be applied to the substrate 158 without the intermediary gold layer 156. Glass and / or ceramic structures and materials disclosed herein are described as such to provide example implementations, and it should be understood that any such referenced structures / materials may comprise any type(s) of nonmetallic (e.g., inorganic) material(s), such as woven glass fiber fabric, epoxy resin binder, plastic, polymer, or even metallic structures such as stainless steel.

[0163] The seed layer materials 153, 157 to the gold layer 156 can be selected based on the material it is applied to. For example, the seed layer 153 can be titanium for suitability for interfacing with the nitinol layer 150. For the seed layer 157, the material may be nickel or titanium for suitability in interfacing with ceramic or similar materials. The layers 157 and 156 may collectively be considered a seed layer for the substrate 158, and the layers 153 and 154 can collectively be considered the seed layer for the thin-film nitinol 152.

[0164] The thin-film nitinol 152, which may be formed using physical vapor deposition (PVD) or similar process, can be metallized with the gold layer 154, with acceptable adhesion between layers, which can provide a desirable interface for applying the gold-tin intermediary layer(s) 155 between the nitinol 152 and the non-nitinol substrate 158. For example, the PVD nitinol 152 can be metallized conformally with pure gold using sputtering techniques or other processes. The seed layers 153, 157 can provide a necessary intermediary for application of the gold layers 154, 156, respectively.

[0165] The gold (Au) layer(s) 154, 156 can advantageously promote adhesion due to the ability of gold to adhere well to nitinol, glass, ceramic, and other substrates, while also forming a good bond with the AuSn alloy. Furthermore, the gold layer(s) 154, 156 can provide a desirable barrier layer to prevent interactions between the nitinol 152, the glass / ceramic 158, and the AuSn 155 that might be undesirable, such as diffusion or chemical reactions that could weaken the bond or alter the properties of the materials. In addition, as gold is a good conductor of electricity and heat, the gold layer(s) a54, 156 can advantageously impart these properties to the overall structure 150. The gold layer(s) 154, 156 can also serve to prepare the nitinol 152 and ceramic / glass 158 surfaces for better deposition of the AuSn layer 155, ensuring a more uniform and consistent layer. Although described as gold, other metals may be used for the layer(s) 154, 156, such as nickel, palladium, titanium, titanium alloy, aluminum, platinum, or the like. In some implementations, the nitinol stack 151 comprises approximately 1–3 μm thickness of nitinol with a sputtered titanium-Docket No.: ADV-23598WO01 tungsten (TiW) barrier metal 153, with the AuSn layer 155 bonded thereto. The interim TiW (or other material described herein) barrier can advantageously allow the AuSn to stay molten for a period of time for attachment to the base gold layer 154.

[0166] The intermediary seed layers 153, 157 can comprise any suitable or desirable gold, or gold-tin, intermediary interface, such as titanium, chrome, nickel, copper alloy, silver, platinum alloy, palladium alloy, titanium alloy, or the like. In some examples, the layer(s) 153, 157 comprise oxide. The layer(s) 153, 157 can improve the adhesion of the gold layers to the nitinol 152 and / or glass / ceramic 158, and / or can modify the surface properties of the glass / ceramic (such as its electrical properties) in a desirable manner. The layers 153, 157 can comprise any suitable or desirable oxide, such as titanium or chrome. In some implementations, the layer 153 can comprise titanium dioxide, which forms naturally on nitinol surfaces, and can be enhanced through various treatments. Other options include silicon dioxide, which can provide an insulating layer and / or desirably modify surface properties for improved adhesion or functionalization, niobium pentoxide, and other oxides. The substrate seed layer 157 can comprise silicon dioxide, titanium dioxide, aluminum oxide, aluminum oxide, zirconium dioxide, yttrium oxide, or other similar oxide.

[0167] In some implementations, the gold-tin (AuSn) layer 155 is introduced to the stack-up 150 as a preform structure that is interposed / placed between the gold-seeded layers. For example, the preform can comprise a layer of AuSn cut to a specific track, which may have a thickness of less than 100 µm, such as approximately 50 µm or less, or as low as 25 µm or less. The preform 155 can be sandwiched between the two layers 151, 159. In some implementations, the AuSn preform 155 is stamped / machined off a sheet, or laser cut or die cut. In some implementations, the gold-tin (AuSn) layer 155 is grown on the thin-film nitinol 155. AuSn ‘preforms,’ as described herein, can comprise a piece of material that has been pre-shaped or formed into a specific configuration, such as a circumscribing track, prior to undergoing reflowing. Such preforms can be shaped into a specific form that is similar to the final desired shape of the AuSn seal / bond. The use of AuSn preforms can help to reduce the amount of processing or machining needed to achieve the final shape and size of the hermetic and / or electrical seal. It also helps in ensuring consistency and uniformity in the manufacturing process. AuSn preforms as described herein may be made using various techniques, such as casting, extrusion, powder metallurgy, or the like.

[0168] The bonded stack-up 150, as shown in Figure 15B, may be formed using standard semiconductor packaging tools, such as flip-chip bonding, to precisely align and apply controlled force and heat to create a hermetic seal. With certain applications, creating biocompatible interfaces may require an additive or flux that can potentially render the device harmful for the body. Conversely, utilizing gold-tin (AuSn) alloy for bonding as disclosed herein can allow for bondingDocket No.: ADV-23598WO01 without the need for flux or other chemicals to create the bond. Rather, in examples of the present disclosure, the bonding process may involve presenting an inert gas during the bond, which is sufficient to create a hermetic seal. The present disclosure provides various combinations of using AuSn for medical implants. The combination of Figures 15A and 15B, as with other examples presented herein, can allow for low-temperature mechanical joining of nitinol onto dissimilar materials, like glass and ceramic.

[0169] Figures 16A and 16B show exploded and assembled / bonded views, respectively, of another configuration of a material stack-up 160 capable of producing a hermetic seal between a thin-film nitinol (or other metal) layer 162 and a dissimilar substrate 168 (e.g., ceramic, glass) using a gold-tin alloy filler 165 in accordance with one or more examples. The bond-line stack-up 160 of Figures 16A and 16B is similar to the configuration of Figures 15A and 15B, except that the thin- film nitinol 162 has gold-tin (AuSn) 164 applied thereto without an intermediary gold layer. The AuSn (e.g., Au80Sn20) 164 can be sputtered directly onto the nitinol 152.

[0170] In some examples, an additional preform AuSn layer 165 may be interposed / disposed between the AuSn-seeded nitinol stack 161 and the non-nitinol substrate stack 169. Although shown as including a gold seed layer 166, it should be understood that in any of the disclosed examples, a ceramic, glass, or similar substrate can be seeded with AuSn 164 in the manner as the nitinol stack 161. The AuSn seed layer 164 can be directly sputtered onto the thin film nitinol 162 in a conformal manner, or can be applied in any other suitable manner. The AuSn seed layer 164 and may include an intermediary layer 163 interposed between the AuSn layer 164 and the nitinol layer 162. The base structure 168 can be seeded with gold 166 formed on an intermediary layer 167, such as titanium, chromium, nickel, etc.

[0171] Figures 17A and 17B show exploded and assembled / bonded views, respectively, of another material stack-up 170 capable of producing a hermetic seal between a thin-film nitinol (or other metal) layer 172 and a dissimilar substrate 178 (e.g., ceramic, glass) using a gold-tin alloy filler 175 in accordance with one or more examples. In the example configuration 170, a relatively thicker layer gold-tin (AuSn) 175 (e.g., stoichiometrically-precise Au80Sn20) is sputtered directly onto the thin-film nitinol 172 (possibly with intermediary seed layer 173). For example, the AuSn layer 175 may be greater than 20 μm in thickness.

[0172] The substrate 178 may be seeded with gold 176 or similar metal, which may be formed on an intermediary layer 177, such as chromium, titanium, nickel, etc. The seeded base substrate 179 may be bonded to the nitinol stack 171 by reflowing / melting of the AuSn layer 175.

[0173] By implementing the thicker AuSn layer 175, it may not be necessary or desirable to include an additional AuSn preform layer (e.g., like preform layers 155, 165, described above inDocket No.: ADV-23598WO01 connection with Figures 15A / 15B and 16A / 16B, respectively). That is, the use of an AuSn preform structure can be dispensed with altogether in favor of a sputtered thicker layer of the AuSn 175 directly applied onto the thin film 172. Such a configuration can be preferable as reducing the number of components of the bond-line stack 170 and providing relatively more pristine material composition due to the controlled sputtering application.

[0174] Any of the bond-line stacks disclosed above in connection with Figures 15–17, or anywhere else in the present disclosure, can include gold-tin (AuSn) layer(s) used to bond nitinol and non-nitinol structures together by heating and / or applying pressure force to the AuSn layer(s) and / or other components according to a suitable temperature and force profile. Figure 18 shows a temperature profile for a process of bonding dissimilar materials, such as nitinol bonding / joining to non-nitinol material such as ceramic, glass, or printed circuit board, using one or more AuSn layer(s) in accordance with some examples.

[0175] Figure 18 shows a process by which a AuSn bond line may be heated from a baseline (BL) temperature in a gradual ramped-up fashion to a melting temperature 181 of the AuSn (e.g., approximately 280°C / 536°F)) for a period of time sufficient to cause the AuSn to adhere to the nitinol and non-nitinol structures, after which the temperature may be ramped back down to the baseline temperature. Figure 19 shows a force profile for a process of bonding dissimilar materials using one or more gold-tin layer(s) in accordance with one or more examples. As demonstrated in Figure 19, around the time of heating initiation for AuSn bonding, the structures to be bonded together may be pressed into a pressure contact to promote adhesion to the AuSn, thereby facilitating the bond between the materials. The bonding force 191 may be held for a period of time t that spans the time during which the AuSn (and / or other component(s)) is subjected to the heating temperature 181 (see Figure 18). The holding force may be implemented for a period of time before maximum heating and for a period of time after maximum heating, as shown. That is, the bonded components may be forced together during at least a portion of the temperature ramp-up and / or ramp-down.

[0176] Figures 20A, 20B, and 20C show schematic, close-up, and side cross-sectional views, respectively, of a wafer 2000 having a plurality of structures 2070 with gold-tin bonding surfaces 2075 formed thereon in accordance with one or more examples. The wafer 2000 may have formed thereon a plurality of molds / substrates for deposition of thin-film nitinol structures, such as sensor device lid structure, such that a single wafer may be utilized to produce a relatively large number of diaphragm plates / stacks for pressure sensor devices in accordance with aspects of the present disclosure. The reference ‘2070’ in the description below may refer to an individual shapedDocket No.: ADV-23598WO01 substrates of the wafer 2000 onto which thin-film nitinol layer(s) is / are deposited, or may refer to the thin-film nitinol layer / plate-structure deposited onto the substrate.

[0177] The wafer 2000 includes a plurality of diaphragm structures / shapes 2070, wherein each of the shapes 2070 may comprise or be used to produce a separate sensor diaphragm plate. Each of the illustrated plates 2070 may serve as a substrate / mandrel / mold onto which a thin-film diaphragm layer of nitinol metal alloy or similar material may be deposited to form thin-film diaphragm plates comprising, for example, less than 10 µm thickness (e.g., 4–6 µm; around 5 µm) of nitinol or other superelastic material. The layer(s) of nitinol may have a uniform thickness in both the diaphragm areas 2025, as well as the surrounding perimeter structure 2029.

[0178] The forms / plates 2070 may be configured with spacing 2001 around one or more portions of the perimeter 2029 of the respective diaphragm plate forms 2070, which may facilitate deposition of the nitinol and / or other layers of the diaphragm plates in relatively precise areas and / or shapes, and / or may facilitate singulation of the individual diaphragm plates 2070 after formation thereof to mechanically separate the individual plates from the wafer structure 2000. Physical connectors 2002 may be used to connect the diaphragm plate substrates 2070 to the outer structure 2005 of the wafer 2000, which can serve as a sprue / tab structure that anchors the singular substrates 2003 to the outer coupon / structure 2005. The inside portions 2003 (e.g., the substrates 2070 for the nitinol deposition) of the structure 2000 may be detachable from the wafer 2000, or the deposited layers of material (e.g., nitinol, insulator, electrode) may be removed from the substrate without detachment of the substrate 2003.

[0179] The wafer 2000 may be formed of any suitable or desirable material, such as silicone, stainless steel, titanium, nickel, alumina, sapphire, glass, ceramic, or the like. Once the nitinol base diaphragm layer 2025 has been deposited on the plate structures 2003, additional layering may be applied to the diaphragm plates using masking and / or other suitable process. Thin- film nitinol (e.g., 5 µm) diaphragm layer 2025 may be deposited on the substrate 2003, and further perimeter flange structure 2029 may be formed / built-up in the perimeter areas and / or other areas of the substrate 2003, using vapor deposition or other process. Gold-tin (AuSn) 2075 can be applied (e.g., through direct sputtering) onto the perimeter 2029 of the nitinol structure 2070. The total thickness of the nitinol structures 2070 in the area of the perimeter 2029, together with the AuSn bonding layer 2075, can advantageously be between 3–6 µm.

[0180] Figures 21A and 21B show exploded and assembled / bonded views, respectively, of a gold-tin bond stack-up 210 including a nitinol stack 211 bonded to a base substrate stack 219, which includes a hard-stop form 201 in accordance with one or more examples. The hard-stop 201 can be used to provide a deterministic bond line gap distance / height d1between a thin-film nitinolDocket No.: ADV-23598WO01 layer / structure 211 and a base structure 219 comprising dissimilar material(s). As shown, the hard- stop 201 may be positioned laterally outside of at least a portion of the gold-tin bond 215 (i.e., positioned between the gold-tin 215 and the exterior of the device comprising the stack-up 210). As with other examples disclosed herein, the thin-film nitinol structure 211 may be gold-seeded with a layer of gold 214 (or similar metal) and / or an intermediary seed layer 213 (e.g., titanium, chromium, platinum, nickel, etc.). Likewise, the base substrate 219, which may comprise a layer 218 of ceramic, glass, or the like, and may be gold-seeded with a layer of gold 216 (or similar metal) and / or an intermediary seed layer 217 (e.g., chromium, titanium, silicon dioxide, tungsten, etc.). The gold seed layer(s) can be lithographically patterned onto the respective materials, or applied in another manner. Hard-stop forms disclosed herein can comprise metal and / or be formed using metal fabrication processes. However, it should be understood that any hard-stop disclosed herein can comprise non-metal forms, such non-mental forms / substrates extruded from ceramic, glass, or other rigid material.

[0181] The hard-stop 201, which can help make the bond between the nitinol 211 and non- nitinol 219 structures more repeatable / reliable, can be formed and / or configured in various ways. For example, the use of hard-stop form(s) can provide an alignment mechanism that can facilitate repeatable placement of gold-tin preforms. The hard-stop 201 can comprise gold or similar metal, and may extruded or formed in some other manner to provide the set distance d1 between the two layers. As described throughout the present disclosure, when forming the gold-tin (AuSn) bond between the structures 211, 219, the AuSn layer 215 (e.g., preform structure) may be melted like a solder. That is, as the AuSn 215 becomes eutectic, it becomes molten, thereby assuming a liquid form of AuSn that does not hold a rigid layer thickness as force is applied thereto, but rather may flow outward to some degree as it is compressed / pressed in the vertical dimension (with respect to the orientation of Figures 21A and 21B). In order to prevent the thickness of the AuSn layer 215 from decreasing below the dimension d1, the hard-stop 201 prevents the structures 211, 219 from coming closer together than is permitted by the interfering thickness dimension d1 of the hard-stop 201, thereby allowing for the ability to set the separation distance to a very specific dimension / height d1 as the AuSn layer 215 is compressed.

[0182] Physical vapor deposition processes provide various tools to create extrusions, such as the hard-stop extrusion 201. For example, the extrusion 201 can be sputtered / vapor-deposited, electroplated, patterned, or applied using electron beam depostion, focused ion beam milling or deposition, laser microfabrication, or the like.

[0183] Figure 22A shows a sensor base structure 229 including coined hard-stop bumps 203 in accordance with one or more examples. Figures 22B and 22C show exploded andDocket No.: ADV-23598WO01 assembled / bonded views of a device 220 including a gold-tin bond 225 between nitinol 221 and non-nitinol 228 structures, wherein the gap d2 between the bonded structures is set / determined by the hard-stop bumps 203. The hard-stops 203 can be implemented as coined gold bumps to provide the precise distance d2between the mated components, wherein direct reflow using AuSn 225 as a eutectic solder can be implemented to bond the structures together. In some examples, the bumps 203 are gold-studded bumps that are ultrasonically placed onto the ceramic (or glass, PCB, etc.) substrate 228. Such processes can implement standard semiconductor packaging techniques using a gold ball wirebonder machine. For example, rather than extracting the thin gold cable after placing the first ball joint, as done in some wirebonded integrated circuit chip application, the cable can be immediately cleaved, leaving behind the hard-stop extrusion form. To flatten this extrusion, the ball joints can be ‘coined.’ Since gold is generally ductile, this can be done by pressing down on the ball joints, flattening the extrusion and transforming the ball joint into a more cylindrical form. The base structure 229 may include a recess 202 with a bottom layer 204 configured to provide a volume for placement of a sensor device, wherein the volume 202 can be filled with pressure-transmitting fluid, as described in detail herein.

[0184] The hard-stops 203 may be formed by masking and electroplating, or alternatively, by using gold studs with a similar construction to microchip wirebonds. In some implementations, the hard-stop bumps 203 are not extruded, but rather cleaved wire that is flattened to create coin- shaped forms. That is, rather than forming a full wirebond, the gold wire can be cleaved, leaving behind the bump, wherein the joint is implemented using an ultrasonic mechanism to produce a solid metal-to-metal joint. The bumps 203 can be coined down to less than 20 μm in thickness (e.g., 10–20 μm). The bumps 203 may be coined by physically pushing on them since the gold material of which they are comprised is malleable. The coining may be performed using a machine configured to implement ultrasonic pulses while extruding a gold wire to create a metal-to-metal joint.

[0185] The gold hard-stop bumps 203 are advantageously not eutectic, and have a melting point higher than that of the gold-tin 225, such that during the re-flow process for melting the gold- tin (AuSn) bonding agent 225 to produce a hermetic seal, the bumps 203 remain solid and hold the dimension d2. That is, during the heating process for melting the AuSn layer 225, due to its eutectic nature, the AuSn is the only layer / material that melts.

[0186] Figure 23A shows a sensor base structure 239 including a hard-stop extrusion 206 in accordance with one or more examples. Figures 23B and 23C show exploded and assembled / bonded views, respectively, of a gold-tin (AuSn) bond including the hard-stop extrusion 206. The hard-stop extrusion 206 can have the form of a continuous flange that circumscribes the middle area of the structure 239 on an inner radius of the AuSn bond track 235. The base structureDocket No.: ADV-23598WO01 239 may include a recess 205 with a bottom layer 207 configured to provide a volume for placement of a sensor device, wherein the volume 205 can be filled with pressure-transmitting fluid, as described in detail herein.

[0187] The hard-stop 206 can comprise an electrodeposited gold (Au) extrusion, which may be formed in a continuous eutectic flow containment flange / lip that provides the hard-stop dimension d3. For example, the gold seed layer of the base structure 238 can be patterned to form a track rather than a continuous plane. In some implementations, the ceramic (or other material) substrate 238 may be patterned to produce the flange 206, with or without a gold layer thereon. For example, a hard-stop flange may be formed in the ceramic or glass substrate 238 and a thin layer of gold can be applied over the flange. The hard-stop flange 206 may advantageously prevent the molten gold-tin (AuSn) layer 235 (e.g., preform structure) from flowing into the inner sensor space 205.

[0188] When melted, the AuSn layer 235 may push outward as it is compressed / flattened to the thickness of the dimension d3 and push outward away from the flange 206 and fill-in on the edges of the bonded assembly. The hard-stop 206 can be dimensioned such that there is not a substantial volume of the AuSn that pushes outward when the lid 231 and base 238 are joined.

[0189] Figures 24A and 24B show exploded and assembled / bonded views, respectively, of a gold-tin (AuSn)bond stack-up 240 including redundant bonds / seals 302a, 302b in accordance with one or more examples. The structure 240 comprises a nitinol stack 241 including a nitinol thin-film substrate 242 having multiple tracks 245 of AuSn bonding form, which may have an intermediary seed layer 243 having any quitable material as described herein. The nitinol stack 241 is bonded to a non-nitinol substrate stack 249 comprising a non-nitinol substrate 248 seeded with gold 246, and optionally an intermediate layer 247.

[0190] The bond line of the stack 240 includes multiple segments 245a, 245b of gold-tin (AuSn) to form multiple bond-line seals. For example, the AuSn 245a, 245b can be patterned in a manner as to produce the laterally-spaced AuSn forms 245a, 245b, which may be at least partially thermally and / or electrically isolated from one another in some implementations. Physical vapor deposition or other process(es) may be leveraged to form the segmented AuSn bonding forms. For example, lithography can be implemented for such purpose, which can enable the ability to pattern arbitrary patterns. The spaces 301 between the AuSn forms can be air-filled, vacuum-filled, or filled with another material selected to provide desirable insulation or other properties. By implementing redundant AuSn seals, the failure or ineffectiveness of one of the AuSn seals may not cause a failure of the hermetic seal of the stack 240, as the remaining seal(s) may advantageously be independently sufficient to provide a hermetic seal. Therefore, redundant AuSn seals as disclosedDocket No.: ADV-23598WO01 herein can provide a fail-safe mechanism for implant devices and other applications. Furthermore, the use of redundant seals can provide improved structural and / or electrical properties for implant bond lines. Some of the following examples provide variations of redundant AuSn seals according to aspects of the present disclosure.

[0191] The separate bond tracks 302a, 302b can be patterned as continuous tracks, wherein one or both of the tracks provides a hermetic and / or electrical interface / seal. Redundant bonds as disclosed herein can address potential issues relating to mismatches in the coefficient of thermal expansion between the bonded materials. The additional bonds can provide thermal strain accommodation and bond failure contingency. For example, the redundant tracks / bonds 302a / 302b can provide mechanical benefits for hermetic sealing, such as protection against a compromised bond propagating cracks / imperfections thereof throughout the seal. For example, a flaw in the bond 302a may be limited to that bond due to the space separation 301 preventing structural defects from affecting the adjacent bond 302b. Furthermore, as thermal expansion is a volumetric process, the relatively less volume of the segmented bonds can result in less volume expansion differential.

[0192] Figures 25A and 25B show plan and side cross-sectional views, respectively, of a diaphragm structure 250 having one or more gold-tin (AuSn) seals 255 disposed on a nitinol bond- line structure in accordance with one or more examples. In the example of Figures 25A and 25B, the AuSn seal 255 provides a track seal around the perimeter 259 of the structure 250, wherein the perimeter 259 comprises nitinol built-up around the outside of the structure 250 to provide a hermetic seal that surrounds the internal diaphragms 252. Although shown as having perimeter build-up / projections 259, it should be understood that in some implementations, the nitinol areas 252, 259 are of uniform thickness, such that the perimeter 259 and diaphragm 252 surfaces of the nitinol layer are flush. The diaphragm structure 250 may be bonded to a corresponding base structure (not shown in Figures 25A and 25B for visual clarity) in accordance with any example disclosed herein.

[0193] Figures 26A and 26B show plan and side cross-sectional views, respectively, of a diaphragm structure 260 having one or more gold-tin (AuSn) seals 265 disposed on a nitinol bond- line structure in accordance with one or more examples. In the example of Figures 26A and 26B, the AuSn seal 265 provides a track seal around the perimeter 269 of the structure 260, wherein the perimeter 269 comprises nitinol built-up around the outside of the structure 260 to provide a hermetic seal that surrounds the internal diaphragms 262. The structure 250 further includes inner nitinol build-up 267 around rows of diaphragms 262, which may have an elliptical shape / boundary, as shown. Although shown as having perimeter and inner build-up / projections 269, 267, it should be understood that in some implementations, the nitinol areas 262, 267, 269 are of uniformDocket No.: ADV-23598WO01 thickness, such that the perimeter 269 and inner 267 nitinol and the nitinol diaphragm 262 surfaces of the nitinol layer are flush. The diaphragm structure 260 may be bonded to a corresponding base structure (not shown in Figures 26A and 26B for visual clarity) in accordance with any example disclosed herein.

[0194] Figures 27A and 27B show plan and side cross-sectional views, respectively, of a diaphragm structure 270 having one or more gold-tin (AuSn) seals 275 disposed on a nitinol bond- line structure in accordance with one or more examples. In the example of Figures 27A and 27B, the AuSn seal 275 provides a track seal around the perimeter 279 of the structure 270, wherein the perimeter 279 comprises nitinol built-up around the outside of the structure 270 to provide a hermetic seal that surrounds the internal diaphragm area 272. Compared to the examples of Figures 25A / 25B and 26A / 26B, the diaphragm structure 270 does not include a plurality of elliptical thin- film diaphragms, but rather a single diaphragm 272 in the space surrounded by the perimeter seal 275 / 279. Although shown as having a perimeter build-up / projection 279, it should be understood that in some implementations, the nitinol areas 272, 279 are of uniform thickness, such that the perimeter 279 and the nitinol diaphragm 272 surfaces of the nitinol layer are flush. The diaphragm structure 270 may be bonded to a corresponding base structure (not shown in Figures 27A and 27B for visual clarity) in accordance with any example disclosed herein.

[0195] Figures 28A and 28B show plan and side cross-sectional views, respectively, of a diaphragm structure 280 having redundant, parallel gold-tin (AuSn) seals 285 in accordance with one or more examples. The diaphragm structure 280 may be bonded to a corresponding base structure (not shown in Figures 28A and 28B for visual clarity) in accordance with any example disclosed herein.

[0196] In the example of Figures 28A and 28B, the AuSn seal 285 provides parallel track seals 285 around the perimeter of the structure 280, wherein the perimeter comprises nitinol tracks 289 built-up around the outside of the structure 280, with AuSn 285 formed thereon to provide a hermetic seal that surrounds the internal diaphragm area 282. The redundant seals 289 / 285 can be implemented in any example disclosed herein, such as in any of the perimeter seals of the examples of Figures 25A / 25B, 26A / 26B, or 27A / 27B described above. Furthermore, although two parallel seals are shown, it should be understood that redundant seals in accordance with examples of the present disclosure can have any number of parallel, and / or non-parallel, seals. Although shown as having perimeter build-up / projections 289, it should be understood that in some implementations, the nitinol areas 282, 289 are of uniform thickness, such that the perimeter areas / tracks 289 and the nitinol diaphragm 282 surfaces of the nitinol layer are flush. In such implementations, the AuSn may simply be applied on a uniform nitinol layers in the seal track patterns shown.Docket No.: ADV-23598WO01

[0197] The parallel tracks 285a / 289a, 285b / 289b may have a common width, or one of the tracks may be wider than another. The parallel tracks 285 may provide lateral space 286 between the adjacent tracks, which, when the diaphragm structure 280 is assembled in as sensor device or other sealed assembly, may be air-filled, vacuum-filled, or filled with a material suitable for providing insulation and / or structural support for the parallel tracks. The use of multiple redundant tracks, separated by lateral spacing between tracks, can increase flexibility in the area of the seal. The bond projections 299 / 295, and counterpart bonding surfaces / structures of the base to which the plate 290 may be bonded are subjected to thermal expansion mismatches. Therefore, the laterally non-continuous redundant tracks, as opposed to the solid tracks of Figures 25–27, can help alleviate the mismatches.

[0198] Figures 29A and 29B show plan and side cross-sectional views, respectively, of a diaphragm structure 290 having parallel gold-tin (AuSn) seals 295 in accordance with one or more examples. The diaphragm structure 290 may be hermetically bonded to a corresponding base structure (not shown in Figures 29A and 29B for visual clarity) using the AuSn seals 295 in accordance with any example disclosed herein.

[0199] In the example of Figures 29A and 29B, the AuSn seal 295 provides three parallel track seals 295a, 295b, 295c around the perimeter of the structure 290, wherein the perimeter comprises nitinol tracks 299 built-up around the outside of the structure 290, with AuSn 295 formed / applied thereon to provide a hermetic seal that surrounds the internal diaphragm area 292. The redundant seals 299 / 295 can be implemented in any example disclosed herein, such as in any of the perimeter seals of the examples of Figures 25A / 25B, 26A / 26B, or 27A / 27B described above. Furthermore, although three parallel seals are shown, it should be understood that redundant seals in accordance with examples of the present disclosure can have any number of parallel, and / or non- parallel, seals. Although shown as having perimeter build-up / projection 299, it should be understood that in some implementations, the nitinol areas 292, 299 are of uniform thickness, such that the perimeter areas / tracks 299 and the nitinol diaphragm 292 surfaces of the nitinol layer are flush. In such implementations, the AuSn may simply be applied on a uniform nitinol layers in the seal track patterns shown.

[0200] The parallel tracks 295a / 299a, 295b / 299b, 295c / 299c may have a common width, or one of the tracks may be wider than another. For example, in the illustrated example, the middle track 299b / 295b is wider than the inner 299c / 295c and outer 299a / 295a tracks; any combination of relative track widths may be implemented in connection with examples of the present disclosure, including implementations in which an outermost track is wider than one or more inner tracks, and / or where an innermost track is wider than one or more outer tracks. The parallel tracks 299 mayDocket No.: ADV-23598WO01 provide lateral space 296 between the adjacent tracks, which, when the diaphragm structure 290 is assembled in as sensor device or other sealed assembly, may be air-filled, vacuum-filled, or filled with a material suitable for providing insulation and / or structural support for the parallel tracks.

[0201] Figure 30 shows a plan view of a diaphragm structure 300 having gold-tin seals 394, 395 in a grid pattern in accordance with one or more examples. The seals can include a plurality of parallel tracks 395, which may run along a perimeter of the structure 300, as well as a plurality of tracks 394 that are perpendicular to the perimeter track(s), such that the tracks 395 and the tracks 394 cross paths. Such grid pattern may produce cells 393 enclosed by the seal tracks 394, 395, which may be air-filled, vacuum-filled, or filled with a material suitable for providing insulation and / or structural support for the parallel tracks. Although the tracks 394, 395 are shown as having a generally-perpendicular arrangement, examples may include tracks having any suitable or desirable relative angles.

[0202] Figures 31A, 31B, and 31C show isolated, exploded, and bonded / assembled views, respectively, of a material stack-up 325 including a plurality of gold-tin (AuSn) bonds 314, 324 in accordance with one or more examples. Processes disclosed herein can be implemented to produce, after implementing a first AuSn bond through melting of a AuSn layer, one or more subsequent AuSn bonds without disturbing / reworking previous bond(s). Such processes can allow for assembly of multiple thin-film nitinol components 311, 321 onto a single substrate 317. Double-sided AuSn bonding as shown in Figures 31A–31C may be used in application such as the double-sided diaphragm sensor 1400 shown in Figures 14A and 14B, which includes AuSn bonds on both sides of a base substrate 1401.

[0203] Figure 31A shows a material stack-up bond / joint 310 with a hermetic seal previously implemented between a thin-film nitinol (or other metal) layer 311 and a first side 308 of a dissimilar substrate 317 (e.g., ceramic, glass) using a gold-tin alloy filler 314, which may be similar to any of the gold-tin-bonded structures disclosed herein. In some examples, the AuSn layer(s) 314 can comprise about (e.g., within 5%) 80% gold (Au) and 20% tin by weight. Such composition can provide a eutectic alloy, wherein the material melts or solidifies at a single temperature, like a pure metal, rather than over a range of temperatures like many alloys. The eutectic temperature for the AuSn layer 314 may advantageously be relatively low, such as around 280°C (536°F), which is significantly lower than the melting points of pure gold (1064°C or 1947°F).

[0204] The gold-tin (AuSn) layer 314 hermetically joins the nitinol 311 and ceramic / glass 317 stacks, each of which may have seed layer 312 / 313, 315 / 316, such as gold seed layers as described above. The seed layer materials 312, 316 to the respective gold layers 313, 315 can comprise titanium, nickel, chromium, or other material described herein. The gold (Au) layer(s)Docket No.: ADV-23598WO01 313, 315 can advantageously provide a barrier and / or promote adhesion, as described above. The bonded stack-up 310 may be formed using standard semiconductor packaging tools, such as flip- chip bonding, to precisely align and apply controlled force and heat to create a hermetic seal.

[0205] In addition to the gold seeding and gold-tin (AuSn) bonding implemented on the top side 308 (with respect to the orientation of Figure 31A) of the base substrate 317, the substrate 317 may be further prepared for bonding on another side 309 (e.g., bottom side with respect to the orientation of Figure 31A) of the substrate 317, wherein such further bonding may be implemented after the AuSn bond 314 has been completed. Therefore, as shown in Figure 31A, the bottom side 309 of the ceramic or glass (or other material) substrate 317 may be seeded, such as with a gold or other metal layer 319 and / or intermediary metal / oxide layer 318 (e.g., titanium).

[0206] With the gold-tin (AuSn) bond 314 having been previously implemented, the stack- up 310 may subsequently be bonded to another thin-film nitinol structure 320, as shown in Figures 31B and 31C. That is, the second side 309 of the substrate 317 may be bonded to the nitinol layer 321 via a AuSn layer 324, which may be joined to the nitinol 321 via a seed layer comprising gold, AuSn, titanium, and / or other suitable material. The subsequent bonding of the nitinol layer / stack 320 to the substrate 317 without disturbing the previously-implemented bond 314 may be facilitated by the ability of the AuSn alloy 314 to significantly increase its melting temperature after being reflowed onto the gold seed layer(s) 313, 315 through eutectic alloying. For example, during reflowing of the AuSn layer 314, heat can cause the atoms of gold and tin of the AuSn layer 314 to diffuse and mix at the interface between the gold seed layer(s) and the deposited AuSn alloy, leading to a shift in its melting characteristics, thereby increasing the melting point of the AuSn bond 314 due to stoichiometric changes.

[0207] Figure 32 is a graph showing a relationship between gold and tin content by weight in a gold-tin (AuSn) alloy and associated melting points in accordance with one or more examples. As shown in the graph, with a negligible concentration of tin (Sn), gold (Au) melts at around 1000° C, whereas as Sn is added to the alloy, the melting temperature tends to fall drastically up until a local minimum 303 melting temperature of about 280° C at a ration of 80% Au to 20% Sn, beyond which, the melting temperature rises back up by some amount before tapering back down moving towards higher Sn concentrations. As higher Au concentrations can provide better electrical conductivity characteristics, the lower melting point 303 associated with the local minimum on the Au-heavy side of the spectrum may be preferable to alloys with higher Sn concentrations. Therefore, Au80Sn20, and nearby concentrations, which places the melting point at or near the local minimum 303, may be beneficial for applications disclosed herein to allow for reflowing below the transformation temperature of nitinol.Docket No.: ADV-23598WO01

[0208] With reference back to Figure 31A, the diffusion of the AuSn molecules from reflowing of the AuSn layer 314 can advantageously result in a higher concentration of gold (Au) and less tin (Sn) in the bond layer 314 through out-diffusion of Sn into the Au seed layer(s) 313, 315 and / or diffusion of Au from the Au seed layer(s) 313, 315 into the AuSn layer 314, such that the melting point of the layer 314 moves back up the melting curve shown in Figure 32 to a higher melting temperature (e.g., higher than 320° C, such as about 350° C). Therefore, with the melting temperature of the previous bond 314 having increased, the subsequent reflowing of the AuSn bond / layer 324 may be implemented at the lower melting temperature (at or around 280° C) without melting / disturbing the layer 314 with the higher Au concentration. The diffusion of Au into the AuSn layer 314 may be dependent on the thickness of the Au layer(s) 313, 315. Therefore, the melting temperature of the AuSn layer 314 can be controlled at least in part by implementing particular thickness(es) for the Au layer(s) 313, 315. By raising the melting temperature of the AuSn layer 314 above the 280 you raise it above 280° C minimum, subsequent heating of the layer 314 will not reach a eutectic melting temperature that would disturb the bond, which is an important aspect for hermetic sealing. Therefore, the diffusion of the adjacent Au into the AuSn can provide a valuable benefit for bonding of hermetic devices.

[0209] Figures 33A and 33B show exploded and bonded / assembled views of a structure 330 having gold-tin bond(s) 401, 402 providing hermetic sealing and electrical connection between a nitinol substrate 332 and a non-nitinol substrate 348, wherein the substrates 332, 348 have integrated with conductive pathways, passive electronics, and / or active electronics that are electrically connected across the bonds 402 in accordance with one or more examples. As described herein, in addition to forming a hermetic seal, gold-tin (AuSn; e.g., Au80Sn20) can provide the capability of electrically connecting functional thin-film nitinol 332 onto a passive (e.g., a printed circuit board (PCB), flex cable, or micro-electro-mechanical system (MEMS) substrate) or an active (e.g., application-specific integrated circuit (ASIC), microprocessor, field-programmable gate array (FPGA), system-on-chip (SOC), microcontroller, radio-frequency identification (RFID) chip, active MEMS, optoelectronic device) substrate 348.

[0210] Figure 33A shows a thin-film nitinol substrate 332, which may have a passive capacitive electrode 482, or other passive or active electrical element(s), formed thereon. For example, the electrode 482 may comprise a layer of gold (Au) or other conductor applied to the nitinol 332 through physical vapor deposition or other process, as described in detail above. An intermediate layer 373 of high-k dielectric, such as titanium oxide or other suitable oxide, may be interposed between the gold layer 482 and the nitinol 332. Furthermore, gold-tin (AuSn) form(s) 471 may be applied onto the electrode 482 to provide electrical contacts to the elected 482. TheDocket No.: ADV-23598WO01 nitinol substrate 332 may further have AuSn bumps / tracks 335 outside of the area of the electrode 482 to provide a hermetic bond for the device / structure 330, wherein the bond tracks 335 can be configured to provide a hermetic seal around the electrode 482, such that the assembled device 330 may be suitable for implantation and chronic maintenance within a human body, for example. The hermetic bond forms 335 may be seeded by a seed material 333, such as titanium or other suitable metal / oxide.

[0211] The base substrate 348 may comprise any suitable material in / on which electrical elements may be integrated. In some implementations, the base substrate 348 includes bond projections / tracks 346, which may be bonded to the opposite-facing AuSn bonds 335 to form the hermetic seals 401. The substrate 348 may further include an electrode or other passive or active circuitry 481. The electrode 481 may serve as a counter electrode to the capacitive electrode 482 associated with the nitinol substrate 332, which may be implemented on a seed layer 373. Therefore, when combined as shown in Figure 33B, the electrodes 482, 481 may operate as plates of a capacitor, which may be utilized in a pressure-sensing application or other application. Examples of such sensor devices are described in detail above.

[0212] The base substrate 348 may further include electrical contacts 491, which may comprise gold or other conductor metal, wherein such contacts 491 are configured to bond to the AuSn electrical contacts 471 associated with the nitinol substrate 332. The assembled configuration shown in Figure 33B shows the formed electrical internal bonds 402 and hermetic perimeter bonds 401, which may connect any number / types of transducers integrated directly onto the thin-film nitinol substrate 332 to the electronics / circuit associated with the corresponding active or passive substrate 348. Intermediary seed layers 247, 377 may be implemented for the AuSn layers 347, 491, respectively.

[0213] In some implementations, the same bond may be formed on the inside 402 and outside 401 of the device 330 in terms of material composition and / or arrangement. The diagram of Figure 33B represents the electrical connection / bond by resistor icon. Generally, the AuSn bond 402 may provide low enough electrical resistance to accommodate use in sensor applications and other applications as described herein.

[0214] The bond forms 335 may be implemented as flip-chip bumps / forms to allow for flip- chip combination as demonstrated by the diagrams of Figures 33A and 33B. Therefore, according to aspects of the present disclosure, sensor electronics integrated onto a thin-film nitinol substrate (e.g., multiple capacitive electrodes, multiple piezoresistors), such electronics can be connected to individual AuSn bond forms, wherein joints to such bond forms can be created using traditional flip-chip bonding technologies to bond the nitinol to a flex cable or other substrate.Docket No.: ADV-23598WO01

[0215] Figures 34A and 34B show plan and side views, respectively, of a nitinol sensor structure / device 351 with gold-tin (AuSn) electrical contacts 354 in accordance with one or more examples. Figure 35 shows the nitinol sensor structure / device 351 with the gold-tin electrical contacts 354 bonded with corresponding electrical contacts 366 of an electrical device / substrate 368 in accordance with one or more examples.

[0216] As shown, AuSn solder bumps 354 can be patterned directly onto thin-film nitinol substrate 352 to interface between any number / types of sensors / transducers 353 on the nitinol 352 forming an electrical connection. Electrical connection between the AuSn contacts 354 and the respective sensor elements 353 may be made via conductive traces 355 formed on the nitinol 352. Analogous to solder bumps used for flip chip bonding, AuSn bond forms 354 can serve a similar purpose. In the illustrated configuration, a plurality of AuSn bond pads 354 connect to one or more nodes of the sensor(s) 353, which may be passive or active electrical elements implemented on the nitinol 352. For example, is some implementations, the sensor(s) 352 can comprise a plurality (e.g., nine) of gold, platinum, or other microelectrode(s) used to capture electrocardiogram (ECG) signals, or other type of electrode(s). Each microelectrode can be electrically connected to a corresponding AuSn solder bump 354 and wired out onto a base / substrate 368.

[0217] The substrate 368 can be a flex cable or other passive (e.g., a printed circuit board (PCB), flex cable, or micro-electro-mechanical system (MEMS) substrate) or active (e.g., application-specific integrated circuit (ASIC), microprocessor, field-programmable gate array (FPGA), system-on-chip (SOC), microcontroller, radio-frequency identification (RFID) chip, active MEMS, optoelectronic device) substrate. The substrate 368 can have contact pads 366, which may comprise gold or other conductor seeded to the substrate 368, wherein the pads 366 align with the AuSn pads 354 in a flip-chip arrangement. Due to the low melting temperature of the AuSn bonding pads 354, the nitinol structure configuration 351 provides the ability to join multiple nitinol components onto the same substrate 368 without adversely disturbing previous joints.

[0218] When implemented as gold-tin (AuSn) solder bumps, the contact pads 354 may not include gold seeding for the AuSn bumps, as implementing the AuSn contacts as multiples of preform AuSn may be challenging. Rather, the AuSn pads 354 may advantageously be sputtered directly onto the nitinol 352. The contacts 366 on the substrate 368 may provide a gold seed layer for the AuSn bonds. The illustrated layers 356 may comprise a nickel titanium mix of some configuration, or other layer used to create adhesion, such as a metal between 5–100 nm in thickness.

[0219] The AuSn contact bumps 354 may have any suitable height, such as a height above about 15–20 µm, which may be sufficient to achieve a solid bond and withstand the relevantDocket No.: ADV-23598WO01 planarity tolerance. The AuSn bumps 354 may not provide a hermetic seal due to the non- encompassing form / configuration thereof. Therefore, the combined device 350 may be implemented with a perimeter seal, which may or may not comprise AuSn as described in detail herein. Vascular / Cardiac Access for Sensor Implantation

[0220] Packaged sensor implant devices in accordance with one or more examples of the present disclosure may be advanced to the relevant target chamber or vessel of the heart and / or vasculature using any suitable or desirable procedure. Figure 36 is a cutaway view of a human heart 1 and associated vasculature showing certain catheter 111 access paths for implantation procedures for implanting a sensor device 370, which may be similar in one or more respect to any of the examples disclosed herein, in accordance with one or more examples. Specifically, access to various chambers / vessels of the heart can be made using a delivery system 111 via the right atrium 5 and / or inferior vena cava 16, such as through a transfemoral or other transcatheter procedure. Such access is shown by reference 111a. Reference 111b shows access to the right atrium 5 via the superior vena cava. In some implementations, access to the left atrium 2 or ventricle may be made using transseptal access, which may be made through the inferior vena cava 16 or superior vena cava 19, as respectively shown, and from the right atrium 5, through the septal wall 18 and into the left atrium 2. For transaortic access, a delivery catheter 111c may be passed through the descending aorta 27, aortic arch 12, ascending aorta, and aortic valve 7, and into the left atrium 2 through the mitral valve 6. For transapical access, a delivery catheter 111d may make access directly through the apex 39 of the heart 1 into the left ventricle 3, and into the left atrium 2 through the mitral valve 6. Other access paths are also possible beyond those shown in Figure 36. The various transcatheter delivery systems and paths shown may involve transporting a sensor implant device 1900 within a shaft / lumen of such instrumentation and deploying the device 1900 from the delivery system at the target anatomical site. Additional Description of Examples

[0221] Provided below is a list of examples, each of which may include aspects of any of the other examples disclosed herein. Furthermore, aspects of any example described above may be implemented in any of the numbered examples provided below.

[0222] Example 1: A sealing structure comprising a layer of nitinol, a layer of non-nitinol material, and an intermediary layer of eutectic gold-tin configured to bond the layer of nitinol to the layer of non-nitinol.Docket No.: ADV-23598WO01

[0223] Example 2: The sealing structure of any example herein, in particular example 1, wherein the non-nitinol material is ceramic or glass.

[0224] Example 3: The sealing structure of any example herein, in particular example 2, further comprising a gold seed layer interposed between the layer of eutectic gold-tin and the layer of non-nitinol material.

[0225] Example 4: The sealing structure of any example herein, in particular example 3, wherein the gold seed layer comprises a layer of gold and a layer interposed between the layer of non-nitinol material and the layer of gold comprising at least one of chromium, titanium, tungsten, or palladium.

[0226] Example 5: The sealing structure of any example herein, in particular example 1, further comprising a gold-tin seed layer interposed between the layer of eutectic gold-tin and the layer of nitinol.

[0227] Example 6: The sealing structure of any example herein, in particular example 1, wherein the layer of eutectic gold-tin, prior to reflowing, is 80% gold and 20% tin by weight.

[0228] Example 7: The sealing structure of any example herein, in particular example 6, wherein the layer of eutectic gold-tin is configured to be reflowed and increase in gold content by weight from a layer of gold interposed between the layer of eutectic gold-tin and the layer of nitinol or the layer of non-nitinol material, thereby increasing a melting point of the layer of gold-tin.

[0229] Example 8: The sealing structure of any example herein, in particular example 1, wherein the layer of eutectic gold-tin is sputtered onto the layer of nitinol.

[0230] Example 9: The sealing structure of any example herein, in particular example 1, wherein the layer of nitinol is a thin-film layer formed using physical vapor deposition.

[0231] Example 10: The sealing structure of any example herein, in particular example 9, further comprising a layer of sputtered gold applied to the layer of nitinol, the layer of sputtered gold being interposed between the layer of nitinol and the layer of eutectic gold-tin.

[0232] Example 11: The sealing structure of any example herein, in particular example 1, wherein the layer of eutectic gold-tin is a preform structure.

[0233] Example 12: The sealing structure of any example herein, in particular example 1, further comprising a hard-stop form interposed between the layer of nitinol and the layer of non- nitinol material, the metal hard-stop form having a melting point that is higher than a melting point of the layer of eutectic gold-tin.

[0234] Example 13: The sealing structure of any example herein, in particular example 12, wherein the hard-stop form has a track form.Docket No.: ADV-23598WO01

[0235] Example 14: The sealing structure of any example herein, in particular example 12, wherein the hard-stop form has a bump form.

[0236] Example 15: The sealing structure of any example herein, in particular example 12, wherein the hard-stop form is configured to laterally block the layer of eutectic gold-tin from flowing past the metal hard-stop form when the layer of eutectic gold-tin is melted.

[0237] Example 16: The sealing structure of any example herein, in particular example 1, wherein the layer of nitinol and the layer of eutectic gold-tin are bonded to a first side of the layer of non-nitinol material, and a second nitinol layer is bonded to a second side of the layer of non-nitinol material via a second layer of gold-tin.

[0238] Example 17: The sealing structure of any example herein, in particular example 1, wherein the layer of eutectic gold-tin provides an electrical pathway electrically coupling a first conductor on the layer of nitinol to a second conductor on the layer of non-nitinol material.

[0239] Example 18: An implantable sensor device comprising a vapor-deposited nitinol layer comprising one or more deflectable diaphragms, a non-nitinol base substrate, and one or more gold-tin forms bonded between the nitinol layer and the base substrate, the one or more gold-tin forms providing a hermetic seal between the nitinol layer and the base substrate.

[0240] Example 19: The implantable sensor device of any example herein, in particular example 18, further comprising a first capacitive electrode conformally formed on one of the one or more deflectable diaphragms of the nitinol layer, and a second capacitive electrode coupled to the base substrate, the second capacitive electrode and the first capacitive electrode forming a variable capacitor.

[0241] Example 20: The implantable sensor device of any example herein, in particular example 19, further comprising one more gold-tin electrical contacts providing an electrical connection between the first capacitive electrode and an electrical element associated with the base substrate.

[0242] Example 21: The implantable sensor device of any example herein, in particular example 18, further comprising one or more gold contacts formed on the base substrate and configured to bond to the one or more gold-tin forms.

[0243] Example 22: The implantable sensor device of any example herein, in particular example 18, further comprising one or more gold-tin electrical contacts each electrically coupled to a respective one of one or more sensor elements implemented on the nitinol layer.

[0244] Example 23: The implantable sensor device of any example herein, in particular example 22, further comprising one or more electrical contacts implemented on the base substrate and arranged to bond to the one or more gold-tin electrical contacts in a flip-chip connection.Docket No.: ADV-23598WO01

[0245] Example 24: The implantable sensor device of any example herein, in particular example 22, wherein the one or more gold-tin electrical contacts are arranged in a track around a perimeter of the nitinol layer.

[0246] Example 25: An implantable sensor device comprising a vapor-deposited nitinol layer comprising one or more deflectable diaphragms, a non-nitinol base substrate, and a hermetic seal formed between the nitinol layer and the base substrate, the hermetic seal formed as a track around a perimeter of the nitinol layer that comprises eutectic gold-tin.

[0247] Example 26: The implantable sensor device of any example herein, in particular example 25, wherein the track comprises one or more tracks of nitinol having gold-tin formed thereon.

[0248] Example 27: The implantable sensor device of any example herein, in particular example 26, wherein the one or more tracks of nitinol comprises a plurality of redundant parallel tracks.

[0249] Example 28: The implantable sensor device of any example herein, in particular example 27, wherein the plurality of parallel tracks consists of two parallel tracks that run along the perimeter of the nitinol layer.

[0250] Example 29: The implantable sensor device of any example herein, in particular example 27, wherein the plurality of parallel tracks consists of three parallel tracks that run along the perimeter of the nitinol layer.

[0251] Example 30: The implantable sensor device of any example herein, in particular example 29, wherein a central one of the three parallel tracks has a width that is greater tha a width of an inner track and an outer track of the three parallel tracks.

[0252] Example 31: The implantable sensor device of any example herein, in particular example 25, further comprising a metal hard-stop structure disposed on an inner radius of the track that sets a spacing dimension between the nitinol layer and the base substrate.

[0253] Example 32: A method of bonding a nitinol structure to a non-nitinol structure. The method comprises providing a first thin-film nitinol structure, providing a non-nitinol base structure, disposing a first eutectic gold-tin form between the first nitinol structure and a first side of the base structure, and reflowing the first gold-tin form to bond the first nitinol structure to the first side of the base structure.

[0254] Example 33: The method of any example herein, in particular example 32, wherein, prior to said reflowing, the first gold-tin form is a solid preform structure.Docket No.: ADV-23598WO01

[0255] Example 34: The method of any example herein, in particular example 32, further comprising, prior to said reflowing the first gold-tin form, forming a seed layer on the first side of the base structure.

[0256] Example 35: The method of any example herein, in particular example 34, wherein the seed layer comprises a layer of gold.

[0257] Example 36: The method of any example herein, in particular example 35, further comprising, during said reflowing the first gold-tin form, increasing a melting point of the first gold-tin form by diffusing gold from the seed layer into the first gold-tin form.

[0258] Example 37: The method of any example herein, in particular example 36, further comprising, after reflowing the first gold-tin form, reflowing a second gold-tin form on a second side of the base structure to bond a second thin-film nitinol structure to the second side of the base structure.

[0259] Example 38: The method of any example herein, in particular example 37, wherein, when the second gold-tin form is reflowed, the second gold-tin form is not melted due to the second gold-tin form having a melting point that is lower than the melting point of the first gold-tin form.

[0260] Example 39: The method of any example herein, in particular example 32, further comprising pressing the nitinol structure against the base structure while reflowing the gold-tin form to facilitate the bonding.

[0261] Example 40: The method of any example herein, in particular example 32, further comprising pressing the nitinol structure against the base structure to compress the gold-tin form between the nitinol structure and the base structure.

[0262] Example 41: The method of any example herein, in particular example 40, wherein said compressing of the gold-tin form is limited by a non-nitinol hard-stop form disposed between the nitinol structure and the base structure.

[0263] Example 42: The method of any example herein, in particular example 32, further comprising passing an electrical signal from a first electrical element on the first nitinol structure to a second electrical element on the base structure through the bond.

[0264] Example 43: The method of any example herein, in particular example 32, wherein said reflowing of the first gold-tin form is implemented with the first nitinol structure and the base structure in a flip-chip arrangement.

[0265] Example 44: A sealing structure comprising a first substrate comprising a layer of sputtered material, a second substrate comprising a layer of non-sputtered material, and an intermediary layer of eutectic gold-tin configured to bond the first substrate and the second substrate.Docket No.: ADV-23598WO01

[0266] Example 45: The sealing structure of any example herein, in particular example 44, wherein the sputtered material is nitinol.

[0267] Example 46: The sealing structure of any example herein, in particular example 44, wherein the sputtered material is titanium.

[0268] Methods and structures disclosed herein for treating a patient also encompass analogous methods and structures performed on or placed on a simulated patient, which is useful, for example, for training; for demonstration; for procedure and / or device development; and the like. The simulated patient can be physical, virtual, or a combination of physical and virtual. A simulation can include a simulation of all or a portion of a patient, for example, an entire body, a portion of a body (e.g., thorax), a system (e.g., cardiovascular system), an organ (e.g., heart), or any combination thereof. Physical elements can be natural, including human or animal cadavers, or portions thereof; synthetic; or any combination of natural and synthetic. Virtual elements can be entirely in silica, or overlaid on one or more of the physical components. Virtual elements can be presented on any combination of screens, headsets, holographically, projected, loud speakers, headphones, pressure transducers, temperature transducers, or using any combination of suitable technologies.

[0269] Any of the various systems, devices, apparatuses, etc. in this disclosure can be sterilized (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.) to ensure they are safe for use with patients, and the methods herein can comprise sterilization of the associated system, device, apparatus, etc. (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.).

[0270] Depending on the example, certain acts, events, or functions of any of the processes or algorithms described herein can be performed in a different sequence, may be added, merged, or left out altogether. Thus, in certain examples, not all described acts or events are necessary for the practice of the processes.

[0271] Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is intended in its ordinary sense and is generally intended to convey that certain examples include, while other examples do not include, certain features, elements and / or steps. Thus, such conditional language is not generally intended to imply that features, elements and / or steps are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and / or steps are included or are to be performed in any particular example. The terms “comprising,” “including,” “having,” and the like are synonymous, are used in their ordinary sense, and are used inclusively, in an open-ended fashion, and do not exclude additional elements,Docket No.: ADV-23598WO01 features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is understood with the context as used in general to convey that an item, term, element, etc. may be either X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain examples require at least one of X, at least one of Y and at least one of Z to each be present.

[0272] It should be appreciated that in the above description of examples, various features are sometimes grouped together in a single example, Figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than are expressly recited in that claim. Moreover, any components, features, or steps illustrated and / or described in a particular example herein can be applied to or used with any other example(s). Further, no component, feature, step, or group of components, features, or steps are necessary or indispensable for each example. Thus, it is intended that the scope of the inventions herein disclosed and claimed below should not be limited by the particular examples described above, but should be determined only by a fair reading of the claims that follow.

[0273] It should be understood that certain ordinal terms (e.g., “first” or “second”) may be provided for ease of reference and do not necessarily imply physical characteristics or ordering. Therefore, as used herein, an ordinal term (e.g., “first,” “second,” “third,” etc.) used to modify an element, such as a structure, a component, an operation, etc., does not necessarily indicate priority or order of the element with respect to any other element, but rather may generally distinguish the element from another element having a similar or identical name (but for use of the ordinal term). In addition, as used herein, indefinite articles (“a” and “an”) may indicate “one or more” rather than “one.” Further, an operation performed “based on” a condition or event may also be performed based on one or more other conditions or events not explicitly recited.

[0274] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example examples belong. It be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and not be interpreted in an idealized or overly formal sense unless expressly so defined herein.Docket No.: ADV-23598WO01

[0275] The spatially relative terms “outer,” “inner,” “upper,” “lower,” “below,” “above,” “vertical,” “horizontal,” and similar terms, may be used herein for ease of description to describe the relations between one element or component and another element or component as illustrated in the drawings. It be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, in the case where a device shown in the drawing is turned over, the device positioned “below” or “beneath” another device may be placed “above” another device. Accordingly, the illustrative term “below” may include both the lower and upper positions. The device may also be oriented in the other direction, and thus the spatially relative terms may be interpreted differently depending on the orientations.

[0276] Unless otherwise expressly stated, comparative and / or quantitative terms, such as “less,” “more,” “greater,” and the like, are intended to encompass the concepts of equality. For example, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.”

Claims

Docket No.: ADV-23598WO01 WHAT IS CLAIMED IS:

1. An implantable sensor device comprising: a sealing structure including: a layer of nitinol; a layer of non-nitinol material; and an intermediary layer of eutectic gold-tin configured to bond the layer of nitinol to the layer of non-nitinol.

2. The implantable sensor device of claim 1, wherein: the non-nitinol material is ceramic or glass; and the sealing structure further comprises a gold seed layer interposed between the layer of eutectic gold-tin and the layer of non-nitinol material.

3. The implantable sensor device of claim 2, wherein the gold seed layer comprises a layer of gold and a layer interposed between the layer of non-nitinol material and the layer of gold comprising at least one of chromium, titanium, tungsten, or palladium.

4. The implantable sensor device of any of claims 1–3, further comprising a gold-tin seed layer interposed between the layer of eutectic gold-tin and the layer of nitinol.

5. The implantable sensor device of any of claims 1–3, wherein: the layer of eutectic gold-tin, prior to reflowing, is 80% gold and 20% tin by weight; and the layer of eutectic gold-tin is configured to be reflowed and increase in gold content by weight from a layer of gold interposed between the layer of eutectic gold-tin and the layer of nitinol or the layer of non-nitinol material, thereby increasing a melting point of the layer of gold-tin.

6. The implantable sensor device of any of claims 1–3, wherein the layer of eutectic gold-tin is sputtered onto the layer of nitinol.

7. The implantable sensor device of any of claims 1–3, wherein: the layer of nitinol is a thin-film layer formed using physical vapor deposition; and the sealing structure further comprises a layer of sputtered gold applied to the layer of nitinol, the layer of sputtered gold being interposed between the layer of nitinol and the layer of eutectic gold-tin.Docket No.: ADV-23598WO01 8. The implantable sensor device of any of claims 1–3, wherein the layer of eutectic gold-tin is a preform structure.

9. The implantable sensor device of any of claims 1–3, further comprising a metal hard- stop form interposed between the layer of nitinol and the layer of non-nitinol material, wherein: the metal hard-stop form has a melting point that is higher than a melting point of the layer of eutectic gold-tin; and the metal hard-stop form is configured to laterally block the layer of eutectic gold-tin from flowing past the metal hard-stop form when the layer of eutectic gold-tin is melted.

10. The implantable sensor device of any of claims 1–3, wherein: the layer of nitinol and the layer of eutectic gold-tin are bonded to a first side of the layer of non-nitinol material; and a second nitinol layer is bonded to a second side of the layer of non-nitinol material via a second layer of gold-tin.

11. The implantable sensor device of any of claims 1–3, wherein the layer of eutectic gold-tin provides an electrical pathway electrically coupling a first conductor on the layer of nitinol to a second conductor on the layer of non-nitinol material.

12. An implantable sensor device comprising: a vapor-deposited nitinol layer comprising one or more deflectable diaphragms; a non-nitinol base substrate; and one or more gold-tin forms bonded between the nitinol layer and the base substrate, the one or more gold-tin forms providing a hermetic seal between the nitinol layer and the base substrate.

13. The implantable sensor device of claim 12, further comprising: a first capacitive electrode conformally formed on one of the one or more deflectable diaphragms of the nitinol layer; and a second capacitive electrode coupled to the base substrate, the second capacitive electrode and the first capacitive electrode forming a variable capacitor.

14. The implantable sensor device of claim 13, further comprising one more gold-tin electrical contacts providing an electrical connection between the first capacitive electrode and an electrical element associated with the base substrate.Docket No.: ADV-23598WO01 15. The implantable sensor device of any of claims 12–14, further comprising one or more gold contacts formed on the base substrate and configured to bond to the one or more gold-tin forms.

16. The implantable sensor device of any of claims 12–14, further comprising: one or more gold-tin electrical contacts each electrically coupled to a respective one of one or more sensor elements implemented on the nitinol layer; and one or more electrical contacts implemented on the base substrate and arranged to bond to the one or more gold-tin electrical contacts in a flip-chip connection.

17. The implantable sensor device of any of claims 12–14, further comprising one or more gold-tin electrical contacts each electrically coupled to a respective one of one or more sensor elements implemented on the nitinol layer, wherein the one or more gold-tin electrical contacts are arranged in a track around a perimeter of the nitinol layer.

18. An implantable sensor device comprising: a vapor-deposited nitinol layer comprising one or more deflectable diaphragms; a non-nitinol base substrate; and a hermetic seal formed between the nitinol layer and the base substrate, the hermetic seal formed as a track around a perimeter of the nitinol layer that comprises eutectic gold- tin.

19. The implantable sensor device of claim 18, wherein: the track comprises one or more tracks of nitinol having gold-tin formed thereon; and the one or more tracks of nitinol comprises a two or more redundant parallel tracks that run along the perimeter of the nitinol layer.

20. The implantable sensor device of claim 18 or claim 19, further comprising a metal hard-stop structure disposed on an inner radius of the track that sets a spacing dimension between the nitinol layer and the base substrate.

21. A method of bonding a nitinol structure to a non-nitinol structure, the method comprising: providing a first thin-film nitinol structure; providing a non-nitinol base structure;Docket No.: ADV-23598WO01 disposing a first eutectic gold-tin form between the first nitinol structure and a first side of the base structure; and reflowing the first gold-tin form to bond the first nitinol structure to the first side of the base structure.

22. The method of claim 21, further comprising: prior to said reflowing the first gold-tin form, forming a seed layer of gold on the first side of the base structure; during said reflowing the first gold-tin form, increasing a melting point of the first gold-tin form by diffusing gold from the seed layer into the first gold-tin form; and after reflowing the first gold-tin form, reflowing a second gold-tin form on a second side of the base structure to bond a second thin-film nitinol structure to the second side of the base structure; wherein, when the second gold-tin form is reflowed, the second gold-tin form is not melted due to the second gold-tin form having a melting point that is lower than the melting point of the first gold-tin form.

23. An implantable sensor device for measuring blood pressure, comprising: a first substrate comprising a layer of sputtered nitinol or titanium; a second substrate comprising a layer of non-sputtered material; and an intermediary layer of eutectic gold-tin configured to bond the first substrate and the second substrate.

24. The implantable sensor device of claim 23, further comprising an anchoring structure for securing the sensor device to a blood vessel.

25. The implantable sensor device of claim 24, wherein the anchoring structure is shaped for anchoring within a pulmonary artery.

26. An implantable sensor device comprising: an inorganic nonmetal casing; a vapor-deposited thin-film nitinol diaphragm layer including: a deflectable portion configured to deflect in response to changes in pressure conditions external to the implantable sensor device; and a non-deflectable perimeter portion;Docket No.: ADV-23598WO01 a layer of eutectic gold-tin (AuSn) that bonds the inorganic nonmetal casing to the perimeter portion of the thin-film nitinol diaphragm layer, the layer of eutectic AuSn having a melting point that is below a transition temperature of the thin-film nitinol diaphragm layer; and a capacitive sensor element disposed within a chamber hermetically sealed at least in part by the layer of eutectic AuSn and enclosed on at least one side by the deflectable portion of the thin-film nitinol diaphragm layer.

27. The implantable sensor device of claim 26, further comprising: a first seed layer comprising titanium applied directly on the perimeter portion of the thin-film nitinol diaphragm layer; a first layer of gold disposed between the first seed layer and the layer of eutectic AuSn; a second seed layer comprising titanium applied directly on the inorganic nonmetal casing; and a second layer of gold disposed between the second seed layer and the layer of eutectic AuSn.

28. The implantable sensor device of claim 26, further comprising: a first seed layer comprising titanium applied directly on the perimeter portion of the thin-film nitinol diaphragm layer, the layer of eutectic AuSn being disposed directly on the first seed layer; a second seed layer comprising titanium applied directly on the inorganic nonmetal casing; and a layer of gold disposed between the second seed layer and the layer of eutectic AuSn.

29. The implantable sensor device of any of claims 26–28, further comprising a gold hard-stop form disposed laterally outside of at least a portion of the layer of eutectic AuSn.

30. The implantable sensor device of any of claims 26–28, wherein the chamber is filled with incompressible fluid configured to transfer pressure on the deflectable portion of the thin-film nitinol diaphragm layer to the capacitive sensor element.

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