Sealing thin film substrate bonding

Abstract

The sealing structure comprises a layer of thin-film sputtered material such as nitinol, titanium, or a similar material. The sealing structure preferably further comprises a layer of heterogeneous material such as a non-nitinol and / or non-sputtered material, wherein an intermediate layer of process gold-tin is provided to bond the layer of thin-film sputtered material to the layer of heterogeneous material. Examples of heterogeneous materials include ceramics and glass.

Description

Technology Field

[0001] Related applications

[0002] This application claims the benefit of U.S. provisional patent application serial number 63 / 625,783 filed January 26, 2024, the disclosures of said document are incorporated herein by reference. Background Technology

[0003] The present disclosure generally relates to the field of material joining, 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 that provides specific features, e.g., mechanical integrity, electrical conductivity, and / or hermetic sealing. For some structures / assemblies, successful hermetic joining can provide / improve fit, for example, for medical implants. Joining techniques and materials involving fusion welding using temperatures higher than the transformation or melting temperature of the material(s) being joined may cause degradation, damage, and / or other effects on the joined materials.

[0004] For example, a method, system, and apparatus for facilitating the formation of a stable hermetic seal between a ceramic body or other substrate and a nitinol or other superelastic layer that can be used in a pressure-sensing implant device are described herein.

[0005] In some embodiments, the present disclosure relates to an implantable pressure sensor comprising a sensor body mechanically and / or electrically coupled to a diaphragm structure, which may be formed from a thin film nitinol or a similar superelastic material. Such a device may advantageously integrate a nitinol (or similar) thin film diaphragm formed using physical vapor deposition (PVD) or similar process(s) with a ceramic sensor body or other non-nitinol substrate (e.g., glass, polyimide, FR4, laminate, PTFE, aluminum, or other metal, etc.). Such integration may be implemented according to an aspect of the present disclosure to preserve the mechanical properties, such as superelasticity, of the nitinol layer(s).

[0006] Embodiments of the present disclosure provide a method for hermetically bonding a thin film nitinol diaphragm / layer to a base substrate (e.g., ceramic) using a relatively low-temperature process to prevent disturbance of the superelasticity and / or other properties of nitinol. Such process(s) may include the incorporation of one or more gold-tin (Au / Sn) layers, which may be applied directly to and / or around the periphery of a nitinol diaphragm structure capable of functioning as a deflected pressure sensor diaphragm. Through the Au / Sn layer(s), an hermetic seal may be formed that additionally provides a structural seal and / or electrical interface between the diaphragm and the base / substrate without impairing the superelasticity of nitinol.

[0007] In some embodiments, the gold-tin layer implemented in relation to the embodiments of the present disclosure comprises an alloy consisting of about 80% gold (Au) and about 20% tin (Sn). This composition can advantageously provide a eutectic solid having a melting point lower than the transition temperature of nitinol and lower than the melting points of pure Au and pure Sn. By preserving the physical properties of nitinol through the melting of this eutectic alloy, which may occur below the transition temperature of nitinol, a robust hermetic seal can be established between the base substrate / ceramic sensor body and the nitinol diaphragm. The manufactured seal is not only hermetically effective but may also adhere well to both materials being bonded.

[0008] The gold-tin (Au / Sn) alloy layer implemented as described herein may advantageously exhibit intermediate thermal expansion characteristics between the thermal expansion characteristics of the base ceramic (or other non-nitinol substrate) and the thermal expansion characteristics of the nitinol diaphragm structure. These intermediate thermal expansion characteristics may advantageously mitigate the risk of separation or crack formation in the sensor that could otherwise occur due to a mismatch in thermal expansion and contraction between the diaphragm and the base material. Accordingly, the aspects of the present disclosure can improve the long-term integrity and reliability of pressure sensors and / or other devices, which may be particularly beneficial for biomedical implant applications.

[0009] Some pressure sensors disclosed herein configured for implantation include a sensor body and a diaphragm. To hermetly bond a PVD nitinol diaphragm to a ceramic sensor body, a low-temperature process is required to prevent deformation of the nitinol properties. The present invention enables the creation of a hermetic seal while maintaining the superelastic properties of nitinol by incorporating an Au / Sn layer on the periphery of the diaphragm. An 80 / 20 Au / Sn alloy forms a eutectic solid having a melting point below the transition temperature of nitinol. Soldering or melting of the eutectic alloy forms a hermetic seal between the ceramic and nitinol, which adheres well to both materials. The Au / Sn alloy has intermediate thermal expansion properties for the ceramic and nitinol, thereby preventing separation and crack formation due to thermal expansion / contraction.

[0010] In some embodiments, the present disclosure relates to a nitinol-to-substrate bonding / bonding technique in which one or more Au / Sn alloy layers are directly implemented between a base substrate (e.g., a ceramic material) and a nitinol diaphragm. In some embodiments, one or more intermediate layers are titanium (Ti), nitinol, titanium tungsten (TiW), titanium tungsten gold (TiW / Au), or similar.

[0011] Any various systems, devices, instruments, etc. in the present disclosure may be sterilized (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.) to ensure safety of use for patients, and the method of the present invention may include sterilization of associated systems, devices, instruments, etc. (e.g., using heat, radiation, ethylene oxide, hydrogen peroxide, etc.).

[0012] The methods and structures disclosed herein for treating a patient also include similar methods and structures performed on or deployed on a simulated patient that are useful, for example, for education, demonstration, procedure and / or device development, etc. The simulated patient may be physical, virtual, or a combination of physical and virtual. The simulation may include a simulation of all or part of a patient, for example, the whole body, a part of the body (e.g., the chest), a system (e.g., the cardiovascular system), an organ (e.g., the heart), or any combination thereof. The physical element may be natural, synthetic, or any combination of natural and synthetic, comprising a human or animal cadaver or part thereof. The virtual element may be entirely in silico or may be overlaid on one or more of the physical components. The virtual element may be presented on any combination of screens, headsets, holography, projection, loudspeakers, headphones, pressure transducers, and temperature transducers, or may be presented using any combination of suitable technologies.

[0013] For the purpose of summarizing the present disclosure, specific aspects, advantages, and novel features have been described. It should be understood that not all of these advantages may be achieved according to any specific embodiment. Accordingly, the disclosed embodiments may be performed in a manner that achieves or optimizes one advantage or a group of advantages as taught herein, without necessarily achieving other advantages that may be taught or suggested herein. Brief explanation of the drawing

[0014] Various embodiments are depicted in the accompanying drawings for exemplary purposes and should not be construed as limiting the scope of the invention. Additionally, various features of different disclosed embodiments may be combined to form additional embodiments that are part of the present disclosure. Throughout the drawings, reference numbers may be reused to indicate correspondences between reference elements. FIG. 1 illustrates a predetermined human anatomical structure, presenting an example of a sensor implantation location according to one or more embodiments. FIG. 2 is a block diagram illustrating a system for wirelessly monitoring one or more physiological parameters associated with a patient according to one or more embodiments. FIGS. 3a and 3b illustrate side cross-sectional views of a piezoresistive pressure sensor device according to one or more embodiments. FIGS. 4a and 4b illustrate side cross-sectional views of a capacitive pressure sensor device according to one or more embodiments. FIG. 5 is a block diagram showing a thin film deposition system according to one or more embodiments. FIG. 6 illustrates a schematic cross-sectional view of a sensor device having a thin film superelastic diaphragm and a structurally conformal capacitive electrode according to one or more embodiments. FIG. 7 illustrates a schematic side cross-sectional view of a sensor device having a pressure transmission medium according to one or more embodiments. FIGS. 8A and FIGS. 8B illustrate front and rear perspective views of a nitinol diaphragm structure according to one or more embodiments. FIG. 9 illustrates a base structure for a sensor device according to one or more embodiments. FIGS. 10a and FIGS. 10b respectively illustrate a schematic diagram and a cross-sectional view of a sensor device comprising one or more diaphragm structures physically coupled to a base structure according to one or more embodiments. FIGS. 11a and FIGS. 11b illustrate front and rear perspective views of a sensor diaphragm structure according to one or more embodiments. FIG. 12 illustrates a base structure for a capacitive sensor device according to one or more embodiments. FIGS. 13a and FIGS. 13b respectively illustrate a schematic diagram and a cross-sectional view of a sensor device comprising one or more diaphragm structures physically coupled to a base structure according to one or more embodiments. FIGS. 14a and FIGS. 14b respectively illustrate a perspective view and a side cross-sectional view of a double-sided sensor device according to one or more embodiments. FIGS. 15a and FIGS. 15b respectively illustrate an exploded view and an assembled / bonded view of a material stack structure that provides a hermetic seal and / or electrical interface between a thin film nitinol (or other metal) layer and a heterogeneous substrate (e.g., ceramic, glass) using a gold-tin alloy filler according to one or more embodiments. FIGS. 16a and FIGS. 16b respectively illustrate an exploded view and an assembly / bonding view of a material stack structure capable of providing a hermetic seal between a thin film nitinol (or other metal) layer and a heterogeneous substrate (e.g., ceramic, glass) using a gold-tin alloy filler according to one or more embodiments. FIGS. 17a and FIGS. 17b respectively illustrate an exploded view and an assembly / bonding view of a material stack structure capable of providing a hermetic seal between a thin film nitinol (or other metal) layer and a heterogeneous substrate (e.g., ceramic, glass) using a gold-tin alloy filler according to one or more embodiments. FIG. 18 illustrates a temperature profile for a process of bonding different materials using one or more gold-tin layer(s) according to one or more embodiments. FIG. 19 illustrates a force profile for a process of joining different materials using one or more gold-tin layer(s) according to one or more embodiments. FIGS. 20a, FIGS. 20b, and FIGS. 20c each illustrate a schematic view, an enlarged view, and a side cross-sectional view of a wafer having a plurality of diaphragm structures formed thereon according to one or more embodiments. FIGS. 21a and FIGS. 21b illustrate an exploded view and an assembled / bonded view of a gold-tin joint including a hard-stop according to one or more embodiments. FIG. 22a illustrates a sensor base structure comprising a coined hard-stop bump according to one or more embodiments. FIGS. 22b and FIGS. 22c illustrate an exploded view and an assembled / bonded view of a gold-tin joint including a hard-stop bump according to one or more embodiments. FIG. 23a illustrates a sensor base structure including a hard-stop extrusion portion according to one or more embodiments. FIGS. 23b and FIGS. 23c respectively illustrate an exploded view and an assembled / bonded view of a gold-tin joint including a hard-stop extrusion according to one or more embodiments. FIGS. 24a and FIGS. 24b respectively illustrate an exploded view and an assembled / bonded view of a gold-tin joint including an overlapping joint / seal portion according to one or more embodiments. FIGS. 25a and FIGS. 25b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure having one or more gold-tin seals according to one or more embodiments. FIGS. 26a and FIGS. 26b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure having one or more gold-tin seals according to one or more embodiments. FIGS. 27a and FIGS. 27b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure having one or more gold-tin seals according to one or more embodiments. FIGS. 28a and FIGS. 28b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure having parallel gold-tin seals according to one or more embodiments. FIGS. 29a and FIGS. 29b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure having parallel gold-tin seals according to one or more embodiments. FIG. 30 illustrates a plan view of a diaphragm structure having a gold-tin seal of a grid pattern according to one or more embodiments. FIGS. 31a, FIGS. 31b, and FIGS. 31c illustrate a separated, exploded, and joined / assembled view of a material stack structure comprising a plurality of gold-tin joints according to one or more embodiments. FIG. 32 is a graph showing the relationship between the gold and tin concentrations and the related melting point in a gold-tin alloy according to one or more embodiments. FIGS. 33a and FIGS. 33b illustrate an exploded view and a joining / assembly view of a structure having gold-tin joint(s) providing electrical connections according to one or more embodiments. FIGS. 34a and FIGS. 34b respectively illustrate a plan view and a side view of a sensor device having a gold-tin electrical contact according to one or more embodiments. FIG. 35 illustrates a sensor device having a gold-tin electrical contact joined to an electric device according to one or more embodiments. FIG. 36 is a cross-sectional view of the human heart and associated vascular system showing a predetermined catheter access path for a sensor device implantation procedure according to one or more embodiments. Specific details for implementing the invention

[0015] The title provided herein is for convenience only and does not necessarily affect the scope or meaning of the claimed invention.

[0016] Although certain preferred embodiments are disclosed below, it should be understood that the claims of the present invention extend beyond the embodiments specifically disclosed herein to other alternatives and / or uses and variations and equivalents thereof. Accordingly, the scope of claims that may arise herein is not limited by any of the certain embodiments described below. For example, in any method or process disclosed herein, the actions or operations of said method or process may be performed in any appropriate order and are not necessarily limited to any specific disclosed order. Various operations may be described in a number of individual operations in a manner that consequently aids in understanding the certain embodiments, but the order of such description should not be interpreted as implying that such operations are order-dependent. Furthermore, the structures, systems, and / or devices described herein may be implemented as integrated components or as separate components. For the purpose of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not all of these aspects or advantages are necessarily achieved by any given embodiment. Accordingly, various embodiments do not necessarily achieve other aspects or advantages that may be taught or proposed herein, and may be performed in a manner that achieves or optimizes one advantage or group of advantages as taught herein.

[0017] Specific spatially relative terms and similar terms, such as "external," "internal," "superior," "lower," "below," "above," "vertical," "horizontal," "top," "bottom," "distal," and "proximal," are used herein to describe the spatial relationship that one device / element or anatomical structure has with respect to another device / element or anatomical structure. It should be understood that these terms are used herein for ease of description regarding the positional relationship between element(s) / structure(s) as illustrated in the drawings. It should be understood that spatially relative terms are intended to include different orientations of the element(s) / structure(s) during use or operation, in addition to the orientations illustrated in the drawings. For example, another element / structure may indicate a position below or next to that other element / structure with respect to an alternative orientation of the target patient or element / structure, and vice versa. It should be understood that spatially relative terms including the foregoing can be understood relative to each illustrated orientation of the referenced drawing.

[0018] Specific reference numbers are reused across different drawings of the set of drawings of the present disclosure for convenience regarding devices, components, systems, features, and / or modules having similar features in one or more embodiments. However, with respect to any embodiment disclosed herein, the reuse of common reference numbers in drawings does not necessarily indicate that such features, devices, components, or modules are identical or similar. Rather, those skilled in the art may recognize from the context the extent to which the use of common reference numbers may imply similarity between the referenced objects. In the descriptive context of a particular drawing, the use of a specific reference number may be understood to relate to the device, component, embodiment, feature, module, or system identified in that particular drawing, and this does not necessarily relate to any device, component, embodiment, feature, module, or system identified by the same reference number in other drawings. Furthermore, embodiments in separate drawings identified by a common reference number may be interpreted as sharing such characteristics or being entirely independent of one another.

[0019] Where an alphanumeric reference identifier including a numeric part and an alphabet part is used (e.g., in '10a', '10' is the numeric part and 'a' is the alphabet part), a reference to only the numeric part (e.g., '10') in the detailed description of the invention may refer to any feature identified in drawings using such numeric part (e.g., '10a', '10b', '10c', etc.), and this applies even when such feature is identified as a reference identifier that associates the numeric part with one or more alphabet characters (e.g., 'a', 'b', 'c', etc.). That is, a reference to feature '10' in the detailed description of the invention may be understood as referring, for example, to feature '10a' identified in a specific drawing of the present disclosure, or to the identifier '10' or '10b' in the same drawing or another drawing.

[0020] The present disclosure relates to systems, devices, and methods for hermetically bonding thin film nitinol or other superelastic materials to other materials / substrates. Such bonding / bonding techniques may be used in connection with the packaging of devices configured for the sensing and / or remote monitoring of one or more physiological parameters (e.g., blood pressure) of a patient. For example, pressure sensing / monitoring and / or other applications may be implemented using an implant device having thin film pressure sensor diaphragms. Since such a device may be advantageously packaged for organ implantation in a cardiac environment, it may have certain biocompatible features associated therewith. The terms "associated" and "associated with" are used herein in their broad and ordinary senses. 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 to indicate that the first feature, element, component, device, or member is physically coupled, attached, connected, integrated, at least partially embedded, or otherwise physically related to the second feature, element, component, device, or member, either directly or indirectly.

[0021] The term “thin film” is used herein in its broad and common sense and may refer to any film, layer, sheet, skin, veneer, coating, covering, plating, enamel, finish, shell, overlay, or other type of film having a thickness in the range of several nanometers (nm) to several micrometers (μm). The thin film membrane of the present disclosure may be applied to a substrate during manufacturing and may be produced using various deposition techniques, including but not limited to sputtering, electrodeposition, thermal deposition, chemical vapor deposition (CVD), and physical vapor deposition (PVD). The formation of the thin film membrane according to an aspect of the present disclosure may include the step of phase transitioning a solid source material to a gas and the step of reconstituting the gas into a solid state during the deposition process. The thin film membrane of the present disclosure may comprise any suitable or preferred material including: metals such as gold, silver, platinum, titanium, nickel, copper, aluminum, etc., and alloys thereof; Nitinol (nickel-titanium) or other superelastic materials, NiTiCu (nickel-titanium-copper), AuSn (gold-tin), nickel-cobalt-iron alloy (e.g., Kovar ®Alloys such as Ni29Co17Fe54), stainless steel, etc.; semiconductors such as silicon, gallium arsenide (GaAs), indium phosphide (InP), cadmium telluride (CdTe), etc.; oxides such as aluminum oxide (Al2O3), titanium dioxide (TiO2), zinc oxide (ZnO), etc.; nitrides such as titanium nitride (TiN), silicon nitride (Si3N4), gallium nitride (GaN), etc.; polymers such as polytetrafluoroethylene (PTFE), polyimide, polyethylene terephthalate (PET), etc.; and ceramics such as silicon carbide (SiC), aluminum nitride (AlN), etc. For example, depending on the desired material properties, the thin film can be as thin as 1 nm or have a large thickness of 10 μm, 15 μm, 20 μm or more. The membrane disclosed herein may be formed using any type of sputtering process comprising any process in which atoms or molecules are emitted from a target material due to collision with particles having energy such as ions from a plasma, and the emitted particles travel through a vacuum or low-pressure gas environment and condense on a target substrate to form a thin membrane. As used herein, "sputtering" may include any type of direct current, radio frequency, magnetron or reactive sputtering, or any other vapor deposition process.

[0022] Embodiments of the apparatus disclosed herein, such as a capacitive pressure sensor apparatus, may advantageously comprise a diaphragm and / or electrode structure having one or more layers formed by physical vapor deposition and / or other thin film deposition / forming processes. Such embodiments may advantageously comprise superelastic (e.g., nitinol) diaphragm component(s) / layer(s) bonded / coupled to a counterpart or corresponding structure / substrate having different material properties in a manner that creates a seal suitable for implantation in the human body. In some embodiments, such bonding / coupled may further provide an electrical interface between said bonded / coupled components.

[0023] As described in detail below, implantable pressure sensors can be used to measure pressure levels within various conduits and ventricles of the body, such as within various ventricles of the heart. However, generally, due to accessibility and environmental conditions associated with the conduits / ventrics of the heart and / or other potential sensor implantation sites within the patient, only certain types of sensors and sensor packaging may be suitable for implantation for a given application. Embodiments of the present disclosure relate to packaging of a pressure sensor implantable device comprising certain electronic and telemetry features that enable data and / or power to be wirelessly communicated between the implanted sensor device and one or more devices or systems outside the patient.

[0024] Aspects of the present disclosure relate to sensor devices, e.g., wireless implantable pressure sensor devices, and other devices comprising superelastic diaphragm components. In particular, the features of the invention disclosed herein may be implemented in the context of an implantable sensor device, wherein the diaphragm component is bonded / bonded to a base substrate component using one or more gold-tin (AuSn) layers. For example, embodiments of the present disclosure may include a diaphragm structure integrated with eutectic metal layer(s) that create a hermetic and / or electrical interface. As described in detail herein, hermetic bonding of thin film nitinol (e.g., physically vapor deposited nitinol) generally requires a relatively low-temperature process so as not to affect the material properties (e.g., superelasticity) of the nitinol. As described in detail herein, integration of one or more AuSn layers on the periphery of a nitinol layer (e.g., diaphragm) can create a hermetic seal while maintaining the superelastic properties of the nitinol. In relation to the sensor device embodiments, the AuSn-integrated seal may provide biocompatible sealing and / or encapsulation of internal sensor components, such as capacitive electrodes and other circuits, as well as other structural components of the device. In some applications, hermetic sealed electronic packaging may be produced using AuSn, for example, by using Kovar (nickel-cobalt-iron alloy) as a material for the metal lid for better matching of the coefficient of thermal expansion. Nitinol or other superelastic materials combined with AuSn according to aspects of the present disclosure provide a novel mechanism for forming hermetic seals for sealed electronic devices. Additionally, the formation of thin-walled nitinol structures for thin-walled pressure conversion for implantable sensors as disclosed herein provides additional novel sensor packaging solutions. In some embodiments, titanium (Ti) may be used in addition to, or instead of, nitinol for these applications.A process using sputtering to create a diaphragm for pressure conversion within the body (including any one of the entire range of biocompatible low-permeability metals including Ti, stainless steel, nitinol, etc.) according to an embodiment presented herein and to combine said diaphragm structure with gold-tin (AuSn) can provide a number of advantages as described in detail below.

[0025] With respect to implantable pressure sensor devices, anatomical considerations may necessitate the use of sensor devices having a relatively small shape factor. For example, it may be desirable to implant a sensor device, such as a pressure sensor device, using a transcatheter procedure, wherein the sensor device is advanced to a target implantation site through one or more venous or arterial vessels and / or various tortuous access paths. Embodiments of the present disclosure may advantageously be implemented as sensor devices having a profile / size sufficiently small to be carried by and / or through a catheter, a sheath, or other apparatus configured for transcatheter access / use. In addition to size constraints associated with the implantable sensor device (e.g., a pressure sensor device), requirements for sensor sensitivity and / or dynamic range may likewise determine the sensor design. For example, with respect to the pressure sensor device of the embodiment, the deflection pressure diaphragm associated with such a device may be designed in such a way that it provides sufficient sensitivity to the pressure conditions to which the device is exposed.

[0026] When creating a diaphragm having thin metal layer(s) (e.g., physically vapor-deposited nitinol) for use in an implantable pressure sensor, it may be necessary to seal the device using a periphery / periphery structure. However, various difficulties may arise when nitinol is bonded to different materials. In particular, bonding nitinol to ceramics or other different substrates used in implantable pressure sensors can be difficult. For example, due to different rates of thermal expansion, separation and / or cracking may occur at the joints / bonds (e.g., welds) between the materials, thereby compromising or destroying the integrity of the hermetic seal created through the adhesion of the different materials and the bonding thereof. The use of a low-fusion eutectic of AuSn as a soldering bonder to form a stable hermetic seal between a ceramic body and a nitinol diaphragm in a pressure-sensing implant is disclosed herein.

[0027] In some embodiments, gold-tin (AuSn) alloy layer(s) are placed directly between the nitinol and non-nitinol (e.g., ceramic) structures of the device stack. Alternatively, one or more intermediate layers, such as titanium (Ti), titanium-tungsten (TiW), and / or TiW-Au, may be implemented between the AuSn layer(s) and the nitinol and non-nitinol structures. The various AuSn stack structure embodiments disclosed herein may advantageously provide biocompatibility sufficient for use in implantable devices. For example, implantable sensor devices, such as pressure sensor devices equipped with nitinol diaphragms, may require providing biocompatibility and / or encapsulation properties suitable for in vivo implantation. For example, in relation to implantation within certain anatomical structures, such as the ventricles of the heart or other fluid-filled anatomical vessels / ventrics, these environments may provide certain pressure, turbulence, and corrosive conditions that may be associated with fluid / blood properties and / or cardiac circulation. Compared to non-implantable environments, the human body constitutes a relatively harsh environment for electrical implantable devices. Embodiments of the present disclosure provide a sensor implantable device that provides a hermetic seal / sealing for a long period and / or for a lifetime, which may be advantageous or / or critical in implantable sensor applications. For example, such hermetic sealing can prevent the degradation of components of surrounding blood or otherwise prevent interference with the sensor and associated electronic devices. Additionally, the hermetic sealing of the embodiments of the present disclosure may help prevent any non-biocompatible component of the sensor implantable device or any non-biocompatible component associated with the sensor implantable device from creating / causing toxic conditions in the body.

[0028] Physiological sensor implantation site

[0029] Certain embodiments in the context of a heart implant device are disclosed herein. However, while certain principles disclosed herein may be applied particularly to the anatomical structure of the heart, it should be understood that a sensor implant device according to the present disclosure may be implanted or configured to be implanted in any suitable or desirable anatomical structure. Furthermore, embodiments of the present disclosure may also be used in non-biological environments.

[0030] The anatomical structure of the heart is described below to aid in understanding the specific inventive concepts disclosed herein. In humans and other vertebrates, the heart generally comprises a muscular organ having four pumping chambers, and blood flow within it is at least partially controlled by various heart valves, namely the aortic valve, the mitral valve (or bicuspid valve), the tricuspid valve, and the pulmonary valve. The valves may be configured to open and close in response to pressure gradients present during various phases of the cardiac cycle (e.g., relaxation and contraction) to control blood flow to each region of the heart and / or to blood vessels (e.g., pulmonary artery, aorta, etc.). Contraction of the various heart muscles may be triggered by signals generated by the heart's electrical system, which is discussed in detail below.

[0031] FIG. 1 illustrates an example of a heart (1) and associated anatomical structures having various features related to a specific embodiment of the disclosure of the present invention. The illustrated anatomical structures illustrate an exemplary implantation site, 's', for a sensor device according to an aspect of the present disclosure. Generally, the heart (1) comprises four ventricles, 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) to the pulmonary artery through the pulmonary artery valve (9), and the pulmonary artery valve is configured to separate the right ventricle (4) from the pulmonary artery (11) and to be open during systole so that blood is pumped toward the lungs and to be closed during diastole so that blood can be prevented from leaking back from the pulmonary artery (11) to the heart.

[0032] The pulmonary artery (11) carries deoxygenated blood from the right side of the heart to the lungs. The blood returns from the lungs to the left atrium (2) via the pulmonary vein (23). As illustrated, the pulmonary artery (11) includes the pulmonary trunk and the left (15) and right (13) pulmonary arteries branching out from the pulmonary trunk. In addition to the pulmonary valve (9), the heart (1) includes three additional valves to assist in the circulation of blood within, 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 leaflets and can be closed during ventricular contraction (i.e., systole) and opened during ventricular expansion (i.e., diastole). The mitral valve (6) generally has two leaflets and separates the left atrium (2) from the left ventricle (3). The mitral valve (6) is configured to open during diastole to allow blood from the left atrium (2) to flow into the left ventricle (3), and, if functioning properly, to close 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 to close during diastole to prevent blood from leaking back into the left ventricle (3).

[0033] Heart valves generally comprise a relatively dense fibrous ring, referred herein as the annulus, as well as multiple leaflets or leaflets attached to the annulus. Generally, the leaflets or leaflets may be sized such that the resulting increased blood pressure occurring within the corresponding heart ventricle when the heart contracts causes the leaflets to open at least partially, allowing flow from the heart ventricle. When intracardiac pressure drops, subsequent ventricular or intravascular pressure rises, which can compress the leaflets again. As a result, the leaflets / leaflets adhere to each other, thereby closing the passage of flow. Dysfunction of the heart valve and / or associated leaflets (e.g., pulmonary valve dysfunction) can lead to valve leakage and / or other health complications.

[0034] The atrioventricular (i.e., mitral and tricuspid) heart valves are generally coupled to an assembly of chordae tendineae and papillary muscles (not shown) to secure the leaflets of each valve in order to promote and / or facilitate proper fusion of the valve leaflets and to prevent dislocation of the valve leaflets. The papillary muscles may include, for example, finger-like protrusions from the ventricular wall. The valve leaflets are connected to the papillary muscles by chordae tendineae. A muscular wall (17), called the septum, separates the left (2) and right (5) atria and the left (3) and right (4) ventricles.

[0035] As mentioned above, specific physiological conditions or parameters associated with cardiac anatomical structures can affect a patient's health. For example, congestive heart failure is a condition associated with the relatively slow flow of blood through the heart and / or body, which increases fluid pressure in one or more ventricles of the heart. As a result, the heart becomes unable to pump enough oxygen to meet the body's needs. The various ventricles of the heart may respond to this increased pressure by stretching, becoming relatively stiff, or hypertrophying to retain more blood for pumping throughout the body. The heart walls may eventually weaken and become unable to pump efficiently. In some cases, the kidneys may counteract cardiac inefficiency by allowing the body to retain fluid. Fluid accumulation in the arms, legs, ankles, feet, lungs, and / or other organs can cause congestion in the body, which is known as congestive heart failure. Acute decompensated congestive heart failure is a major cause of morbidity and mortality; therefore, the treatment and / or prevention of congestive heart failure is a significant concern in medical care.

[0036] Various methods for identifying and / or treating congestive heart failure involve observing the worsening of symptoms and / or changes in body weight. However, these signs may appear relatively late and / or may be relatively unreliable. For example, daily body weight measurements can be significantly variable (e.g., up to 9% or more) and may not be reliable in indicating signs of cardiac complications. Furthermore, treatments derived from monitoring signs, symptoms, body 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 implantable devices may provide better results than purely observation-based 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 that do not involve direct or indirect pressure monitoring may include measuring or observing other current physiological conditions of the patient, such as body weight, chest impedance, and right heart catheter insertion.

[0037] Cardiac pressure monitoring

[0038] Cardiac pressure monitoring according to embodiments of the present disclosure may provide a proactive intervention mechanism for preventing or treating congestive heart failure. Generally, an increase in ventricular filling pressure associated with diastolic and / or systolic heart failure may occur prior to the onset of symptoms leading to hospitalization. For example, cardiac pressure indicators may be provided for some patients for several weeks prior to hospitalization. Accordingly, a pressure monitoring system according to embodiments of the present disclosure may be advantageously implemented to reduce hospitalization cases by guiding appropriate or desired titration and / or administration of medication prior to the onset of heart failure.

[0039] Cardiac pressure monitoring, such as left atrial pressure monitoring, can provide a mechanism to guide the administration of medications to treat and / or prevent congestive heart failure. Such treatment may advantageously reduce hospital readmissions and morbidity, as well as provide other benefits. An implanted pressure sensor according to an embodiment of the present disclosure may be used to predict heart failure up to two weeks or longer prior to the onset of symptoms or markers of heart failure (e.g., dyspnea). If a heart failure predictor is identified using an embodiment of the cardiac pressure sensor according to the present disclosure, certain preventive measures, including pharmacological interventions such as modifications to the patient's medication regimen, may be implemented, which may help prevent or reduce the effects of cardiac dysfunction. Direct pressure measurement in the left atrium may advantageously provide an accurate indicator of pressure accumulation that may cause heart failure or other complications. For example, the trend of atrial pressure elevation may be analyzed or used to determine or predict the onset of cardiac dysfunction, whereby medication or other therapies may be intensified to reduce pressure and prevent or reduce additional complications.

[0040] FIG. 2 is a block diagram illustrating a system (200) for wirelessly monitoring one or more physiological parameters associated with a patient according to one or more embodiments. FIG. 2 illustrates an implantable device (30) comprising a sensor device (37) which may have a predetermined fixation structure (31) associated therewith. For example, the fixation structure (31) may be configured to be fixed inside and / or to the tissue wall of one or more organisms. Although various embodiments of the implantable sensor device are illustrated and described in this disclosure without a separate fixation structure, such omission is for clarity purposes only, and it should be understood that any example disclosed herein may have a predetermined fixation structure associated therewith to fix the device to the tissue / anatomical structure of the organism at the implantation site.

[0041] The sensor device (37) may be a pressure sensor according to any embodiment disclosed herein. In some embodiments, the sensor (37) includes a converter (32) as well as a predetermined control circuit (34), which may be implemented, for example, in 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), the diaphragm being formed of a superelastic material and having one or more electrode layers or other electronic devices forming part of the converter circuit layered / integrated thereon. The diaphragm (33) may be at least partially integrated with the outer layer(s) of the sensor housing (36). In some embodiments, the sensor housing (36) includes a radio frequency transparent structure that accommodates at least part of the antenna (38).

[0042] The control circuit (34) of the sensor device (37) may be configured to process a signal received from the transducer (32) and / or to wirelessly transmit the associated signal through biological tissue using an antenna (38). The antenna (38) may include one or more coils or loops of a conductive material such as copper wire, or piezoelectric resonators, or other wireless signal transmission components. In some embodiments, at least a portion of the transducer (32), the control circuit (34), and / or the antenna (38) may be at least partially disposed in or included within a sensor housing / packaging (36) structure which may include any type of material and, advantageously, may be at least partially hermetic-sealed. The housing (36) as well as the diaphragm (33) may be at least partially formed using vapor deposition, as described in more detail below.

[0043] The term “control circuit” is used herein in its broad and common sense and may refer to any assembly of any device that manipulates a signal (analog and / or digital) based on a logic circuit, an analog circuit, a digital signal processor, a microcomputer, a central processing unit, a field programmable gate array, a programmable logic unit, a state machine (e.g., a hardware state machine), a logic circuit, an analog circuit, a digital circuit, and / or any assembly of any device that manipulates a signal (analog and / or digital) based on the hard coding and / or operating instructions of the circuit. The control circuit referenced herein may further include one or more storage devices that may be implemented as a single memory device, multiple memory devices, and / or embedded circuits of the device. Such data storage devices may include 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 an embodiment in which the control circuit includes a hardware and / or software state machine, an analog circuit, a digital circuit, and / or a logic circuit, the data storage device(s) / register(s) storing any associated operation instruction may be embedded inside or outside the circuit including the state machine, the analog circuit, the digital circuit, and / or the logic circuit.

[0044] In some embodiments, the housing / packaging (36) may comprise one or more tubes, cans, substrates / boards, or other structures comprising glass, epoxy, ceramic, metal, and / or other rigid material(s), which may provide mechanical stability and / or protection for the components housed therein. In some embodiments, the housing / packaging (36) is at least partially flexible. For example, the housing / packaging may comprise a polymer or other flexible structure / material that can advantageously allow folding, bending, or collapse of an embodiment of the sensor (37) to pass through a catheter or other introduction means. However, embodiments of the present disclosure may be implemented in a manner that advantageously provides long-term hermetic protection, and the thin-film flexible diaphragm(s) for pressure conversion and the associated electrical circuitry are integrated into a single part, component, and / or device.

[0045] The transducer (32) may include any type of sensor means or mechanism. For example, the transducer (32) may be a force-collector-type pressure sensor. The transducer (32) is illustrated and described as including one or more diaphragms. However, it should be understood that the pressure sensor device disclosed herein may utilize any type of deflection strain- or deflection-measuring component(s) configured to measure strain or deflection applied across its area / surface, such as one or more pistons, Bourdon tubes, bellows, etc. The transducer (32) may be associated with a housing / packaging (36) such that at least a portion thereof is contained within or attached to the housing / packaging (36). In some embodiments, the electrode-integrated diaphragm (33) may function as a component of a piezoresistive MEMS pressure sensor, which may be configured to use a conductor coupled or formed to detect strain caused by applied pressure, wherein the resistance increases as the pressure deforms the component / material. That is, the integrated electrode(s) (33) of the transducer (32) may be a component of a piezoresistor. In this embodiment, the conductor(s) may be applied to a thin film nitinol diaphragm layer. A piezoresistor pressure sensor is described below in relation to FIGS. 3a and 3b. Alternatively, the diaphragm (33) may be a component of a capacitive pressure sensor, wherein the capacitive plate / electrode layer is applied to a nitinol diaphragm layer as described in detail throughout this disclosure. A capacitive pressure sensor is generally described below in relation to FIGS. 4a and 4b.

[0046] In some embodiments, the transducer (32) is or includes a component of an electromagnetic pressure sensor that may be configured to measure the displacement of the diaphragm by capacitance change, linear variable displacement transducer (LVDT) function, Hall effect, or eddy current detection. In some embodiments, the transducer (32) is or includes a component of a piezoelectric strain sensor. For example, such a sensor may determine a strain (e.g., pressure) for a sensing mechanism based on the piezoelectric effect in a specific material such as quartz. In some embodiments, the transducer (32) is or includes a component of a strain gauge. In any of these embodiments, the associated sensor electrode / conductor may be applied to a thin film nitinol diaphragm component as described in detail herein.

[0047] As described in detail below, the transducer (32) may be integrated with or include one or more layers of vapor-deposited biocompatible material. In some embodiments, the transducer(s) (32) are electrically and / or telecommunicationally coupled to a control circuit (34), which may include one or more application-specific integrated circuit (ASIC) microcontrollers or chips. The control circuit (34) may further include one or more individual electronic components, such as tuning capacitors, resistors, diodes, inductors, etc.

[0048] In the system (200) of FIG. 2, an 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) may have a medical implant device (30) implanted in, for example, the heart (not shown) or an associated physiological location. For example, the implant device (30) may be implanted at least partially within the left atrium of the patient's heart.

[0049] In a given embodiment, the monitoring system (200) may include at least two subsystems, including an implantable internal subsystem or device (30) comprising a control circuit (34) comprising one or more microcontroller(s), individual electronic component(s), and one or more power and / or data transmitter(s) (38) (e.g., antenna coils), as well as sensor transducers (32). The monitoring system (200) may further include an external (e.g., non-implantable) subsystem comprising an external reader (42) (e.g., coils) which may include a wireless transceiver electrically and / or communicationally coupled to a given control circuit (41). In a given embodiment, both the internal and external subsystems include corresponding coil antennas for wireless communication and / or power transmission through patient tissue placed between them. The sensor implant device (30) may be any type of implant device. In some embodiments, the implant device (30) includes a pressure sensor integrated with other functional implant structures, such as an artificial shunt or stent device / structure, a valve, or a clip.

[0050] The implant device (30) may include a predetermined fixing structure (31) as described above. For example, the fixing structure (31) may include a transdermal shunt device configured to be fixed to a tissue wall and / or inside a tissue wall. Although a predetermined component is shown in FIG. 2 as part of the implant device (30), it should be understood that the sensor implant device (30) may include only a subset of the illustrated components / modules and may include additional components / modules not illustrated. The implant device (30) may be presented as an embodiment of any implant device shown in FIG. 8 through FIG. 18, or vice versa.

[0051] In a given embodiment, the sensor transducer(s) (32) may be configured to generate an electrical signal that can be wirelessly transmitted to a device outside the patient's body, such as the illustrated local external monitor system (42). The control circuit (34) may include any type of transceiver circuit configured to transmit an electromagnetic signal, and the signal may be emitted by an antenna (38), which may include one or more conductive wires, coils, plates, etc. The control circuit (34) of the implantable device (30) may include, for example, one or more chips or dies configured to perform a certain amount of processing on the signal generated and / or transmitted using the device (30). However, due to size, cost and / or other constraints, the implantable device (30) may not include independent processing capabilities in some embodiments.

[0052] A wireless signal generated by the implant device (30) may be received by a local external monitor device or subsystem (42), which may include a reader / antenna-interface circuit module (43) configured to receive wireless signal transmissions from the implant device (30) that is at least partially placed within the patient (44). For example, the module (43) may include transceiver device(s) / circuits.

[0053] The external local monitor (42) may receive wireless signal transmissions and / or provide wireless power using an external antenna (48), such as a wand device. The reader / antenna-interface circuit (43) may include a radio frequency (RF) (or other frequency band) front-end circuit configured to receive and amplify a signal from the implantable device (30), wherein the circuit may include one or more filters (e.g., band-pass filters), amplifiers (e.g., low-noise amplifiers), analog-to-digital converters (ADCs) and / or digital control interface circuits, phase-locked loop (PLL) circuits, or signal mixers, etc. The reader / antenna-interface circuit (43) may be further configured to transmit a signal to a remote monitor subsystem or device (46) via a network (49). The RF circuit of the reader / antenna-interface circuit (43) may further include one or more of a digital-to-analog converter (DAC) circuit, a power amplifier, a low-pass filter, an antenna switch module, an antenna, etc., for processing / processing a signal transmitted through the network (49) and / or receiving a signal from the implantable device (30). In a given embodiment, the local monitor (42) includes a control circuit (41) for performing processing of a signal received from the implantable device (30). The local monitor (42) may be configured to communicate with the network (49) according to a known network protocol such as Ethernet or Wi-Fi. In a given embodiment, the local monitor (42) includes a smartphone, a laptop computer, or other mobile computing device, or any other type of computing device.

[0054] In a given embodiment, the implantable device (30) includes a certain amount of volatile and / or non-volatile data storage devices. For example, such data storage devices may include solid-state memory utilizing an array of floating-gate transistors, etc. The control circuit (34) may utilize data storage for storing detected data collected over a given period, and the stored data may be periodically transmitted to a local monitor (42) or other external subsystems. In a given embodiment, the implantable device (30) does not include any data storage. The control circuit (34) may be configured to facilitate wireless transmission of data generated by the sensor transducers (32) or other associated data. The control circuit (34) may be further configured to receive input from one or more external subsystems, such as a local monitor (42) or a remote monitor (46), across a network (49), for example. For example, the implantable device (30) may be configured to receive a signal that controls the operation of the implantable device (30) at least partially, for example, by activating / deactivating one or more components or sensors, or otherwise by affecting the operation or performance of the implantable device (30).

[0055] One or more components of the implant device (30) may be powered by one or more power sources (35) (e.g., batteries). Due to concerns regarding size, cost, and / or electrical complexity, it may be desirable for the power sources (35) to be essentially minimized. For example, high power driving voltage and / or current within the implant device (30) may adversely affect or interfere with the operation of the heart or other body parts associated with the implant device. In a given embodiment, the power sources (35) are essentially at least partially passive, so that power can be received wirelessly from an external source by the passive circuit of the implant device (30), such as through short-range or near-range wireless power transmission or the use of other electromagnetic coupling mechanisms.

[0056] In some embodiments, the local monitor device (42) may function as an intermediate communication device between the implantable device (30) and the remote monitor (46). The local monitor device (42) may be a dedicated external unit designed to communicate with the implantable device (30). For example, the local monitor device (42) may be a wearable communication device, or another device that can be easily placed in close proximity to the patient (44) and / or the implantable device (30). The local monitor device (42) may be configured to call the implantable device (30) continuously, periodically, or sporadically to extract or request sensor-based information. In some embodiments, the local monitor (42) includes a user interface, and the user may use the interface to view sensor data, request sensor data, or otherwise interact with the local monitor system (42) and / or the implantable device (30).

[0057] The system (40) may include an auxiliary local monitor (47), which may be, for example, a desktop computer or other computing device configured to provide a monitoring station or interface for viewing and / or interacting with monitored cardiac pressure data. The local monitor (47) on which monitoring is performed and / or the monitored data may be used / utilized for troubleshooting. In one embodiment, the local monitor (42) may be a wearable device or other device or system configured to be placed in physical proximity to the patient and / or implant device (30), wherein the local monitor (42) is primarily designed to receive / transmit signals transmitted and / or received by the implant device (30) and to provide these signals to the auxiliary local monitor (47) for viewing, processing, and / or manipulating. The external local monitor system (42) may be configured to receive and / or process specific metadata from or associated with the implant device (30), such as a device ID, which may be provided through data coupling from the implant device (30).

[0058] The remote monitor subsystem (46) may be any type of computing device or set of computing devices configured to receive, process, and / or present monitor data received via the network (49) from the local monitor device (42), the auxiliary local monitor (47), and / or the implantable device (30). For example, the remote monitor subsystem (46) may advantageously be operated and / or controlled by a medical entity, such as a hospital, a doctor, or other treatment entity associated with the patient (44). While some embodiments disclosed herein describe communication with the remote monitor subsystem (46) indirectly from the implantable device via the local monitor device (42), in some embodiments, the implantable device (30) may include a transmitter capable of communicating with the remote monitor subsystem (46) via the network (49) without the need to transmit information via the local monitor device (42).

[0059] In some embodiments, the antenna (48) of the external monitor system (42) includes an external coil antenna that is matched and / or adjusted to inductively pair with the antenna (38) of the internal implant (30). In some embodiments, the implant device (30) is configured to receive wireless ultrasonic power charging and / or data communication from the external monitor system (42). As previously described, the local external monitor (42) may include a wand or other portable reader. In some embodiments, the antenna (48) includes a piezoelectric crystal.

[0060] In some embodiments, a relay transceiver implant device (45) is implanted or otherwise placed in a patient (44), wherein the device (45) acts as an intermediary between a sensor (30) and an external monitor (42). For example, the device (45) may include one or more antennas configured to receive a wireless transmission signal from the sensor (30) and relay the signal to the external monitor (42) (with or without intermediate signal processing). The relay device (45) may be configured to transmit / relay a signal at a higher power level than the sensor device (30). The relay device (45) may also receive a signal from the external monitor (42) and relay the signal to the sensor (30).

[0061] Implantable pressure sensor device with a deflection diaphragm

[0062] Pressure sensors that can be used in medical implant applications include sensors utilizing microelectromechanical systems (MEMS) technology. Such devices may combine relatively small mechanical and electrical components on a substrate, such as silicon or other semiconductor substrates, and may include a deformable membrane used to measure deflection induced by pressure, wherein the degree of deflection of the membrane indicates the pressure conditions to which the sensor membrane is exposed at the implantation site. Embodiments of the present disclosure improve certain MEMS technology by applying a conductive layer and / or other conductive features to a deflection diaphragm stack formed on a diaphragm substrate comprising thin film nitinol or a similar material. The thin film diaphragm of the sensor device disclosed herein may be configured as a component of any type of deflection-based sensor device, such as a piezoresistive pressure sensor and a capacitive pressure sensor. Such sensors advantageously include a flexible diaphragm layer that functions as a deformable membrane deflected under pressure, and the integrated conductive features of the diaphragm stack create a mechanism for measuring the displacement of the diaphragm(s). This structure can advantageously provide both the converter structure / function and protection from the hostile external environment.

[0063] In relation to a resistive (e.g., piezoresistive) pressure sensor, a certain conductive sensing element may be manufactured directly on the diaphragm of the device (or on an insulating layer formed on the diaphragm) using sputtering, vapor deposition, or other coating processes, and a change in the electrical resistance of such conductor(s) may be determined to indicate a measurement of pressure applied to the diaphragm. Generally, the change in resistance may be proportional to the deformation on the conductor(s), where the change in resistance of the conductor(s) is related to the change in length of the conductor(s) caused by the deflection of the diaphragm on which the conductor(s) are placed.

[0064] FIG. 3a is a side view of a resistive pressure sensor device (320) implemented on a substrate (328) according to one or more embodiments. FIG. 3b is a side view of the piezoresistive pressure sensor (320) of FIG. 3a, wherein the diaphragm (325) of the sensor is deflected according to one or more embodiments. 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, or other materials, which can be formed using physical vapor deposition or other processes. In some embodiments, the thin diaphragm (325) may be formed by etching the substrate (326) to create a relatively thin membrane for the diaphragm (325) that can surround the cavity (329).

[0065] The diaphragm (325) may have one or more conductive traces or elements (322) placed thereon or / or applied thereon. For example, the conductive elements (322) may include traces of metal or other electrical conductors, and as one or more length portions of the conductor(s) extend over the diaphragm (325), the deflection of the diaphragm (325) causes one or more portions of the conductor(s) (322) to be elongated, thereby changing its electrical resistance / impedance. As illustrated in FIG. 3b, when the diaphragm (325) is deflected, the current and / or voltage through the conductive elements(s) (322) can be measured to determine their respective resistance / impedances, thereby providing a measurement indicating the degree of deflection of the diaphragm (325). This deflection represents the environmental pressure experienced by the diaphragm (325).

[0066] FIG. 4a is a side view of a capacitive pressure sensor device (420) according to one or more embodiments. FIG. 4b is a side view of the capacitive pressure sensor (420) of FIG. 4a, wherein the diaphragm (425) of the sensor is deflected according to one or more embodiments. In the case of a capacitive pressure sensor having an electrode-integrated diaphragm structure according to the present disclosure, one or more conductive layers (422) may be deposited / coated on / on a thin film nitinol diaphragm (425) to form a capacitive electrode (e.g., an anode). A corresponding electrode / plate (421) may be formed on a counter substrate (428) such that a cavity or other dielectric medium (429) exists between the electrode / plate (422, 421). In some embodiments, the electrode (421) provides a stationary / static electrode, whereas the diaphragm electrode (422) provides a flexible membrane electrode (422) of dynamic deflection. When the area of ​​these electrodes (422, 421) is fixed, the capacitance between the electrodes can be proportional to the distance(s) between them.

[0067] As illustrated in FIG. 4b, the inward / downward deflection / deformation of the diaphragm (425) can change the spacing between the conductors (421, 422) above at least part of the diaphragm (425), thereby changing the capacitance of the capacitor formed between the diaphragm electrode (422) and the base electrode (422). This change in capacitance can be measured by coupling the sensor device (420) to a tuning circuit, for example, the tuning circuit may have a fundamental frequency proportional to the degree of deflection of the diaphragm (425) and the electrode (422).

[0068] Various arbitrary devices illustrated in FIGS. 3a / 3b and FIGS. 4a / 4b may have a certain oxide and / or other insulating layer (e.g., a high dielectric constant) formed on an electrode component to provide increased capacitance, reduced leakage current, and improved breakdown voltage, or enable a reduction in electrode / device size.

[0069] Thin film deposition of superelastic metal alloy (e.g., nitinol) layer(s)

[0070] Embodiments of the present disclosure advantageously provide solutions for hermetic bonding and / or electrical 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 relatively small devices while providing sufficient and / or improved superelasticity, diaphragm sensitivity, and / or sealing properties. Additionally, using thin film nitinol diaphragms in connection with the embodiments of the present disclosure can facilitate the integration of such diaphragm structures / stacks with sensor electrodes. In some cases, suitable and / or improved biocompatibility properties and / or a relatively simplified manufacturing process may be provided through the deposition of thin film nitinol layers / diaphragms.

[0071] In some embodiments, the sensor device disclosed herein comprises one or more deflection diaphragms as well as a plate structure in which a peripheral mechanical structure is formed internally, said plate being formed by thin film vapor deposition. This integration of the diaphragm(s) with at least some of the additional mechanical structures of the device can reduce the number of manufacturing steps / processes required for manufacturing the device and can also provide superior mechanical properties compared to certain non-integrated diaphragm solutions. Additionally, the integration of the diaphragm with other mechanical structures of the device can reduce the number of components and process steps required to produce the resulting sensor packaging. Because there are fewer components and areas requiring hermetic sealing, a more robust protective housing can be created that reduces the risk of failure / leakage.

[0072] Certain embodiments of the present disclosure provide alternatives to metal plastic deformation, stamping, grinding, etc., of sensor diaphragms or other structures to provide structures having reduced thickness, improved responsiveness, and suitability for conformal deposition / forming on the structure. For example, the process for forming a thin-film deposited metal alloy layer described herein can provide the precision and tolerance required for a micrometer-level layer, which may be difficult or impossible to produce using certain cutting and mechanical processes. In some embodiments, the physical vapor deposition process of a metal alloy structure as disclosed herein can produce nanometer-level precision and tolerance. Such structures may advantageously be formed using an ionization deposition process rather than stamping, welding, or other more complex and / or inconsistent / error-prone processes.

[0073] FIG. 5 is a block diagram illustrating a thin film vapor deposition system (700) according to one or more embodiments. Physical vapor deposition (PVD) and other vacuum deposition processes may be used to produce relatively thin films and coatings. In the system (500), a source material (530) (e.g., metal, nitinol) is transferred from a condensed phase to a vapor phase (570), and then transferred again to a thin film condensed phase (540) applied on / on a target substrate (520). A vaporized / plasma gas (570) may be generated by performing sputtering or evaporation. The plasma gas (570) is deposited on the substrate (520) to form a layer (540) of the deposited source material. Advantageously, the vacuum chamber (510) may not contain air and particles that could otherwise interfere with directional deposition onto the substrate (520).

[0074] Transformation from solid (530) to gas (570) can be achieved by applying energy from an energy source (550). The energy source (550) may be any type of energy including heat / thermocurrent, electric current, and / or voltage potential for a potential (560) associated with the substrate (520). The energy can supply energy to the source material (530) to create a plasma form (570). The potential (560) for the source material (530) may function to form the direction of the deposition flow (570) toward the substrate (520). The source material (530) may be positively charged in some cases, while the potential (560) of the substrate (520) may be negatively charged.

[0075] In relation to the various processes and apparatus disclosed herein, any type of deposition process including or as an alternative to physical vapor deposition may be implemented to manufacture any one of the metal stacks of the present invention. Examples may include cathode arc deposition, wherein a high-power electric arc is emitted from a target (source) material and a portion thereof is ejected into a highly ionized vapor to be deposited on a workpiece. In the case of electron beam physical vapor deposition implementations, the material to be deposited is heated to a relatively high vapor pressure by electron collision in a vacuum, transported by diffusion, and condensed and deposited on a relatively cooler workpiece. In the case of evaporation deposition, the material to be deposited may be heated to a relatively high vapor pressure by electric resistance heating in a vacuum. As another embodiment, close-space sublimation may include the step of placing the source material and the substrate in relatively close proximity to each other and radiating them. Pulsed laser deposition may be implemented by using a high-power laser to ablate the source material into the vapor. Pulsed electron deposition can be implemented by ablating the source material to generate plasma under non-equilibrium conditions using a high-energy pulsed electron beam.

[0076] In some exemplary embodiments, sputtering deposition may be implemented in which a glow plasma discharge, localized around a target substrate via a magnet, bombards the source material and sputters a portion of it into a vapor state for subsequent deposition. For sputtering coating, a magnetron utilizing strong electric and magnetic fields to confine charged plasma particles close to the surface of the sputtering target may be used. Other sputtering techniques that can be implemented include ion beam sputtering, reactive sputtering, ion-assisted deposition, high-power impulse magnetron sputtering, gas flow sputtering, etc.

[0077] Bonded sensor encapsulation variant

[0078] As described above, the implantable pressure sensor device may comprise a deflection diaphragm cover comprising a thin film of nitinol and / or another superelastic metal alloy bonded to a base substrate (e.g., ceramic, glass, or any other type of inorganic nonmetallic material), wherein the bond provides a hermetic coupling between the nitinol and the nitinol structure and / or electrical interface. In such embodiments, the deflection of the diaphragm portion(s) of the cover may generate an electrical change that is readable within the device and indicates pressure conditions outside the device. For example, conductive resistor / strain gauge trace(s) and / or capacitor electrode(s) may be formed on the diaphragm portion(s) so that the deflection of the diaphragm(s) generates a change in the electrical properties (e.g., capacitance, resistance) of the conductor. While capacitor plate electrodes are disclosed in some contexts of this invention, it should be understood that any embodiment disclosed herein is also applicable to resistive or piezoresistive conductor elements integrated with the diaphragm stack. For example, any embodiment of the capacitive sensor disclosed herein described as comprising a flexible nitinol diaphragm and an associated conformal capacitive plate / electrode may alternatively or additionally have a resistive or piezoresistive sensor element integrated / associated with a deflectional nitinol diaphragm.

[0079] Various electronic / conductive layers, components, and / or elements may be added to a diaphragm structure (e.g., a stack) comprising a thin nitinol layer, thereby enabling the integration of passive and / or active electrical elements with a relatively thin diaphragm structure. Applying electrical and / or insulating elements, such as a conductive layer configured to function as a capacitive plate / electrode in an electrical circuit, and associated dielectrics to a nitinol or other thin-film diaphragm can be achieved through chemical or physical vapor deposition, sputtering, masking / etching, photolithography, screen / inkjet printing, electroplating, epitaxy, thermal oxidation, atomic layer deposition, anodizing, etc.

[0080] FIG. 6 illustrates a schematic side cross-sectional view of a sensor device (620) having a thin film (e.g., less than 20 μm, e.g., 5 μm to 10 μm thick), a superelastic diaphragm (625), and a structurally conformal capacitive electrode (622). As with any deflection diaphragm layer(s) disclosed herein, the diaphragm layer(s) (625) may comprise any type of deposited thin film, superelastic metal material(s). Although the deflection diaphragm layer is described as comprising nitinol in a specific context of the present invention, it should be understood that such diaphragm layer may comprise any type of deposited (e.g., physical vapor deposition) thin film (e.g., less than 15 μm), superelastic metal, including nitinol (NiTi), an alloy such as NiTiCu, etc. As described in detail above, the use of physical vapor deposition of nitinol, titanium, gold, and / or other materials provides a basis for producing the sensor diaphragm / electrode stack / structure disclosed herein, which produces a low-profile sensor suitable for human implantation.

[0081] Converting internal human body pressure into capacitance may require relatively high, biocompatible, and stable diaphragm electrodes. To achieve the compliance required for minimally invasive implantable devices, suitable products can be produced by constraining the thickness of the deflection diaphragm stack / structure to micron-level dimensions. Additionally, to achieve relatively large measurable capacitance values ​​using passive or active circuitry, a relatively large diaphragm surface area may be required or desirable. However, these parameters may conflict with the goal of achieving minimally invasive implants due to lateral dimensional constraints generally associated with such devices. By using nitinol and similar materials for a flexible diaphragm substrate upon which a capacitive electrode can be placed, it is possible to provide a biocompatible layer that satisfies these requirements and enables the creation of a low-profile, high-elasticity / capacitive sensor element.

[0082] The device (620) comprises an integrated capacitive electrode (622) (or a resistive conductor in the case of a resistor application) on a superelastic diaphragm (625). The electrode (622) may be part of a flexible stack structure (627) that functions as a capacitive electrode without additional transmission of pressure from the diaphragm (625) to a separate sensor element. In the embodiment of FIG. 6, as with other embodiments disclosed herein, the sensor (620) may be considered a dry capacitive sensor because it does not contain a pressure-transmitting fluid (see FIG. 7), and the encapsulation of the sensor (620) itself (e.g., an outer nitinol shell / layer) forms a component of the pressure-transmitting element, namely one plate / electrode of the capacitor element. That is, the outer nitinol layer / shell (625) provides both biocompatible / seal encapsulation and pressure transmission to the sensor electrical signal due to integration with the capacitive electrode (622).

[0083] The diaphragm electrode (622) is combined with the corresponding electrode (621) to form a capacitor electrically coupled to the electrical circuit portion (634) of the sensor (620). The capacitor plates (621, 622) may be electrically coupled to the resonant circuit of the circuit portion (634) through a predetermined electrical lead / connector (624a, 624b) which can be integrated with the structure of the base substrate / structure (605) in any suitable or desirable manner, such as various traces, vias, etc. A nitinol diaphragm (625) which may have an associated peripheral sidewall / protrusion (628) may be physically sealed to the base structure / substrate (605) and the connection / coupling portion (623) to provide a hermetic sealed volume / space (629) between the capacitor plates (621, 622). The base substrate / structure (605) may include ceramic, glass, nitinol, or other metal or material. The volume (629) may include a vacuum volume.

[0084] The nitinol layer (625) provides a thin, conformal, superelastic, and biocompatible outer opposing shell for the device (620). Additionally, the thin film diaphragm (625) maintains elasticity while providing a relatively large deflection and a corresponding large change in capacitance and signal amplitude. The conductor layer (622) is advantageously insulated from the shape memory metal structure diaphragm (625) to electrically isolate the nitinol layer (625) from the electrical circuit of the capacitor (622 / 821). That is, the nitinol layer (625) can function as a substrate for the deposition / coating of the conductor layer (622), and the conductor (622) is electrically isolated from the diaphragm (625) by the insulating layer (626a) (e.g., oxide).

[0085] Compared to sensors comprising a deflection capacitive sensor diaphragm formed from a glass layer, the use of thin-film nitinol or other superelastic metals as described herein can provide various advantages. For example, when comparing the elasticity of nitinol and glass in the context of a deflection diaphragm, nitinol can be considered to provide superior superelastic properties. Generally, nitinol can return to its original shape after undergoing substantial elastic deformation upon stress relief, which can be beneficial for applications requiring significant degrees and frequency of deflection. Conversely, glass, being a relatively brittle material, generally exhibits relatively low elasticity, cannot efficiently withstand extensive deformation, and may fracture under high stress. Furthermore, the strength of the glass substrate may vary depending on the surface finish of the glass, and defects or cracks on the surface can act as sources of stress concentration, which can impair structural strength. In contrast, the nitinol diaphragm (625) can withstand high stress and deformation without being permanently deformed, whereas glass can be fatally broken when subjected to stress due to its brittle nature.

[0086] The thin-film nitinol diaphragm (625) provides additional advantages, including the ability to form shaped surfaces, such as corrugated or extruded portions, in the diaphragm layer, which can increase the effective surface area of ​​the diaphragm (625) compared to a glass diaphragm. Additionally, the formation of corrugated, extruded, and / or other surface-topological features in the diaphragm layer(s) of the embodiments of the present disclosure (e.g., diaphragm layer (625)) can increase the linear region / responsiveness of the diaphragm. Meanwhile, glass presents certain technical difficulties regarding the formation of shaped surfaces therein due to its structural brittleness / fragility and the lack of available processes for precisely creating surface features on the glass surface. Nitinol can be mechanically tuned in a manner not possible with glass and other diaphragms, and when implemented with the conformal electrode layer described herein covering a substantial area of ​​the nitinol diaphragm, it provides greater deflection, thereby producing a greater change in capacitance. In the case of the corrugated portion within the diaphragm layer(s), such three-dimensional features may be formed by depositing a thin film metal on a surface / mold / mandrel having the corresponding surface features. With respect to fractal-like and / or porous surface features, their formation may include masking, electroplating, etc.

[0087] One or more of the dielectric layers (626a, 626b) may comprise a high dielectric constant dielectric material. In addition to electrically isolating the plate (622, 621) from a physically adjacent substrate (625, 605) to avoid distortion of the sensor signal, the presence of the dielectric (626) may function to protect the electrical circuit associated with the electrode (621, 622) from circuit breakdown from the capacitance between the substrate (622) and the substrate(s) (625, 605), which may be at least partially conductive as in the case of nitinol. The use of a high dielectric material may hinder the generation of capacitance between the nitinol layer (625) and the electrode layer (622), thereby reducing unwanted stray capacitance, which otherwise could have a negative effect on the circuit.

[0088] The capacitor electrodes (621, 622) are electrically coupled to a predetermined electrical circuit (634), which may include an antenna configured to facilitate the wireless transmission of a sensor signal and / or a signal derived therefrom. In some embodiments, the circuit (634) includes active circuit components, such as an amplifier configured to convert the capacitance of the plates (621, 622) into a readable signal. Taken together, the capacitor formed by the plates (621, 622) may be electrically coupled to the antenna in such a way that a change in the capacitance of the capacitor generates a change in the resonance of the antenna, and the resonance of the antenna may be decoded to determine a pressure level that generates the resulting capacitance.

[0089] The joint(s) (623) can advantageously provide an electrical interface through which a conductive line (632) can pass into the base structure. That is, the joint(s) (623) can function as an electrical interface as well as an airtight seal. The joint(s) (623) may have any joint / bond shape described herein and may advantageously comprise one or more layers of gold-tin (AuSn) that facilitate bonding / melting at a temperature below the transition temperature of the nitinol layer(s) (e.g., diaphragm (625)).

[0090] Pressure sensor utilizing a pressure transmission medium

[0091] A given pressure sensor solution may include a sensor encapsulated within a diaphragm-integrated shell / housing with a receiving fluid disposed between an external flexible diaphragm and an internal capacitive sensor device. FIG. 7 illustrates a schematic side cross-sectional view of a sensor device (720) having a pressure receiving medium (752) according to one or more embodiments.

[0092] The pressure transmission medium (752) contained within the housing of the device (720) may include an incompressible fluid such as oil or gel. Unlike the embodiment of FIG. 6, the device (7) includes a separate pressure sensor device / element (710) that includes a self-deflecting diaphragm separate from the diaphragm (725) of the housing.

[0093] An area enclosed by a housing (733), which includes a deflection diaphragm (725), includes a sensor (710) (e.g., a MEMS sensor). A pressure-transmitting fluid or other medium (e.g., oil, gel, epoxy) (752) is placed around the sensor element (710) so that external pressure causing inward deflection of the diaphragm (725) is transmitted to a pressure sensor (710) to detect it. Pressure conditions outside the enclosure (733) can cause inward deflection of the diaphragm (725) by applying pressure to the surface of the sensor element / diaphragm. In some embodiments, the pressure-transmitting medium (752) may include an incompressible fluid or medium. Alternatively, the medium (752) may be compressible, and the deflection of the diaphragm (725) may cause a reduction in the volume of the inner chamber of the enclosure (733), thereby compressing the fluid / medium and causing an increase in pressure within the enclosure (733) that is converted into a sensor element (710).

[0094] The pressure transfer medium (752) is sealed within the housing (733) through a junction(s) (723) that seal the diaphragm structure (770) to the base structure (780) and provide a hermetic sealed housing (733) for the sensor element (710). The diaphragm structure (770) may include a thin film diaphragm (725) as well as peripheral stack structure(s) (728), which may include nitinol and / or other material(s) / layer(s) for bonding to the corresponding structure (738) associated with the base (780). The sensor element (710) is electrically coupled to a predetermined electrical circuit (734), which may include an antenna configured to facilitate the wireless transmission of the sensor signal and / or a signal derived therefrom. In some embodiments, the circuit section (734) includes active circuit components, such as an amplifier configured to convert the capacitance of the plates (621, 622) into a readable signal.

[0095] The joint(s) (723) can advantageously provide an electrical interface through which a conductive line (732) can pass into the base structure. That is, the joint(s) (723) can function as an electrical interface as well as an airtight seal, thereby enabling the integration of the diaphragm structure (770) with a conductor or other electrical element. The joint(s) (723) may have any joint / bond shape described herein and may advantageously include one or more layers of gold-tin (AuSn) that facilitate bonding / melting at a temperature below the transition temperature of the nitinol layer(s) (e.g., diaphragm (725)).

[0096] Tight bonding to nitinol using gold-tin layer(s)

[0097] Nitinol, a shape memory alloy composed of roughly equal proportions of nickel and titanium, possesses certain beneficial properties derived from its crystal structure and the phase transitions it undergoes. These properties include superelasticity and shape memory effects. However, exposure to high temperatures can affect Nitinol's unique properties because it causes changes in the material's crystalline structure. For example, if Nitinol is exposed to temperatures exceeding its austenite termination temperature, it may undergo a thermal transformation. Repeated exposure to high temperatures can gradually alter the alloy's crystalline structure. Even prolonged exposure to relatively low temperatures can induce such changes. In the context of melting bonding materials for the purpose of bonding to Nitinol, heating Nitinol beyond its transformation temperature can result in a loss or reduction of superelasticity, a change in the transformation temperature, and / or changes in the microstructure. The occurrence of recrystallization and / or grain growth in the material's microstructure can affect mechanical properties such as strength and hardness. Furthermore, the shape memory effect of Nitinol depends on the generation of recovery stress during phase transitions. High-temperature exposure can affect this shape recovery ability by reducing the alloy's ability to generate such stress.

[0098] Given the temperature constraints of Nitinol, traditional joining techniques such as welding and soldering can present difficulties when applied to it. This becomes even more severe when the joint must create a hermetic seal. While welding Nitinol is possible, it generally requires precise process modifications tailored to the specific design, performed by experts. Furthermore, welding can limit the choice of materials for welding Nitinol to other metals similar to it.

[0099] Embodiments of the present disclosure advantageously implement a gold-tin (AuSn) alloy to form a hermetic seal and / or electrical bond between a thin film (e.g., physically vapor-deposited) of nitinol and a different material (e.g., ceramic, glass, printed circuit board). Gold-tin can provide a desirable binder through its relatively low melting temperature, high thermal / electrical conductivity, and resistance to fatigue, corrosion, and creep. The advantage of the low melting temperature provided by AuSn is advantageous for the specific sensor applications disclosed herein in that it hermeticly binds nitinol to a different material of the functional substrate while preserving the intrinsic properties of nitinol. By avoiding the need for high temperatures, the gold-tin alloy can effectively protect the integrity of the superelasticity and shape memory properties of nitinol.

[0100] In addition to preserving the mechanical properties of nitinol, the gold-tin hermetic bonding method presented herein offers the advantage of facilitating electrical connection between nitinol and other circuit elements. This feature may be particularly beneficial in applications where mechanical and electrical integration is important or essential, such as medical implants, sensors, actuators, and various other electronic devices. The gold-tin layer(s) used in the exemplary bonding / bonding configurations disclosed herein may additionally provide relatively low reactivity and provide resistance to corrosion and degradation when exposed to body fluids, thereby improving the long-term integrity of the implant. Furthermore, since both gold and tin are biocompatible materials that can be deposited using physical vapor deposition (PVD) techniques or other similar processes (e.g., sputtering / e-beam evaporation / electrodeposition), the thin film gold-tin bonding layer of the embodiments disclosed herein can be deposited using these processes, which can produce a stoichiometrically accurate alloy of gold and tin metals without impurities. Finally, specific types of gold-tin bonding / bonding features as disclosed herein may be implemented using semiconductor industry standard flip-chip bonding processes / machines. For example, gold-tin features may be flip-chip bonded by melting gold-tin form(s) without using flux or corrosive additives that could ultimately raise biocompatibility concerns for chronically implanted devices.

[0101] FIGS. 8a and 8b illustrate front and rear perspective views of a diaphragm lid / structure (870) of a sensor device, wherein the lid / structure comprises nitinol and / or other superelastic material according to one or more embodiments. FIG. 9 illustrates a base structure (980) for a sensor device according to one or more embodiments. FIGS. 10a and 10b illustrate a perspective view and a side cross-sectional view, respectively, of a combined sensor device (1000) comprising a diaphragm lid / structure (870) physically coupled to a base structure (980) according to one or more embodiments. The following description may be understood as relating to any one of FIGS. 8a, 8b, FIG. 9, FIG. 10a, and 10b.

[0102] The structure / plate (870) may provide a structure for one side / plate of a pressure sensing capacitor, and a predetermined contact / connection (871) of the plate (870) may facilitate an electrical connection between the electrode (822) and the electrode base structure pair (see FIG. 9), and the plate (870) is bonded / joined to the corresponding sensor structure using gold-tin (AuSn) alloy layer(s) in such a way that it provides a hermetic seal. In the same invention, components that are 'bonded' to each other may be understood as being joined in any manner, such as welding, adhesive bonding, etc. The contact (871), which may be formed of at least a portion of AuSn, may be connected to the electrode(s) (822) through direct physical contact or routing connection via trace(s) on the nitinol substrate / layer (821). Although the diaphragm plate (870) as well as certain similar devices / structures disclosed herein are illustrated and described as having an elliptical shape, it should be understood that such devices / structures may have any suitable or desirable shape, such as a rectangular, circular, or similar shape. As with any of the other embodiments disclosed herein, as illustrated in FIGS. 8a and 8b, the active capacitive sensor may occupy the entire surface or most of the surface of the plate (870), or the capacitive sensor may occupy a number of smaller diaphragm areas (825a, 825b, 825c) (collectively or individually '825'). As illustrated, the diaphragm plate (870) and / or associated sensor device / component may have an elliptical shape (referred to as 'oblong shape' in some contexts) similar to two semicircles joined on opposite sides of a rectangle, which provides a shape reminiscent of a speed skating rink or athletic track. In some contexts, the shape of the plate / sensor (870) may be referred to as a "stadium" shape, a "disk" shape, or an elongated ellipse.

[0103] The diaphragm plate (870) comprises a sheet / layer (821) of superelastic thin film nitinol, wherein the nitinol may be deflected in a direction perpendicular to the surface of the layer(s) (821) in one or more regions, for example, in regions (825) (collectively or individually '825') corresponding to at least the capacitor electrodes (822a, 822b, 822c). From a process perspective, the nitinol layer (821), comprising the diaphragm portion(s) (825) and the region (829) outside the diaphragm (825), may be deposited on a substrate using physical vapor deposition or other deposition processes. The lid structure (870) may include a peripheral sealing flange (872) raised over the nitinol sheet / layer (821) (based on the orientation of FIG. 8a). The peripheral sealing flange (872) may include a stepped portion, lip portion, rim portion, or similar structural portion configured to be physically bonded to the base to provide a gap between the nitinol layer (821) and the base. As illustrated, the flange (872) may be formed from at least a portion of the nitinol formed / deposited on the layer (821) to create a raised structure. In some embodiments, one or more gold-tin (AuSn) layers are disposed on or adjacent to the nitinol flange (872) to provide a bonding agent for bonding the lid (870) to the base (980) (see FIG. 9). The peripheral bonding / sealing portion of the thin-film nitinol diaphragm structure may generally be a non-flat portion / region of the nitinol layer, as this portion / region is at least partially bonded to a rigid structure and, unlike the diaphragm portion / region (822), does not freely bend inward in response to pressure changes.

[0104] Insulator / oxide layer(s) (826) may be formed or deposited on the nitinol (821) in any suitable or preferred manner. For example, the insulator layer(s) (826) may be formed only in the region of the diaphragm (825). The nitinol layer (821) may have a thickness of, for example, about 5 μm or any other value of less than 10 μm ( d 1 It may have a ‘thin film’ diaphragm layer, but it should be understood that the flexible diaphragm layer disclosed herein may have a thickness of up to 20 μm or more in some embodiments. The electrode metal (822) may be applied on the oxide layer(s) (826) and likewise confined within the area of ​​the diaphragm(s) (825). Although three circular diaphragms (825) are shown, it should be understood that the diaphragm plate / structure disclosed herein may have any number, any configuration, or any shape of diaphragms.

[0105] In some embodiments, the diaphragm region (825) of the nitinol layer (821) is substantially different in one or more aspects compared to the region outside the diaphragm (829). For example, the diaphragm portion (825) may be thinner than the region outside the diaphragm (829). Additionally or alternatively, certain shape or surface features of the diaphragm region (825) may distinguish the diaphragm from the rest of the nitinol sheet / layer. For example, a corrugated portion, a protrusion, an indentation, an embossed portion, or other features may define the outer periphery of the diaphragm region (825) and / or other regions or features of the diaphragm (825).

[0106] A layer (878) of a gold-tin alloy (AuSn) providing a sealing contact surface (879) may be disposed on the periphery flange(s) (872). Additionally, the electrical contact (871) may comprise AuSn. The conductivity of the nitinol layer (821) and the lateral support structure / flange (871) may be significantly lower than the conductivity of the electrode conductor (822) and the AuSn layer(s) (871, 878), thereby allowing an electrical interface through the AuSn form to be formed without electrical shunting through the adjacent nitinol. Using AuSn on the upper part of the contact flange(s) (872) (based on the orientation of FIG. 8a) is advantageous in that it allows electrical contact with the electrical contact implemented on / within the vapor-deposited nitinol (821), while also providing a hermetic seal. Additionally, considering that nitinol generally cannot withstand high temperatures, AuSn may be suitable for placement and melting in close proximity to nitinol because it can melt at temperatures below the transition temperature of nitinol.

[0107] In some embodiments, an electrical conductor contact (871) that may include AuSn is applied / formed on the electrode layer(s) (822) and is electrically in contact / communicated with the formed body (871). For example, the electrical contact (871) may be physically in contact with the electrode layer(s) (822). The contact (871) may provide an electrical connection between the capacitor plate (822) and the physically coupled cathode structure (see FIG. 9, 10a, 10b) when the diaphragm plate (870) is coupled (e.g., bonded) to it, thereby integrating the diaphragm electrode(s) (822) into the associated capacitive resonant circuit of the sensor device. The electrical contact portion (871) may have the form of a raised flange, a stepped portion, a lip portion, a rim portion, or a similar structural portion, and may generally provide a physical contact surface for electrically connecting with a corresponding surface (991) of the base structure (see FIG. 9).

[0108] In some embodiments, the electrical contact portion (991 and / or 871) may comprise electrically conductive AnSn solder, or other types of material formed as a flange protruding in a direction perpendicular to the plane of the plate (870), substrate (980), and / or device (1000). The contact portion (871) may be formed in any suitable or preferred manner through vapor deposition, sputtering, or other coating processes.

[0109] In some embodiments, the peripheral gap (877) may separate adjacent portions / lengths of the conductor (871), which may generally extend along the periphery of the electrode (822). The gap(s) (877) may provide a path for gas from the chamber (1009) to be removed from the space within the contact(s) (871), thereby enabling vacuum sealing. In some embodiments, the contact(s) (871) form a continuous periphery around the electrode(s) (822) without the presence of circumferential gap(s), thereby enabling independent and / or separated capacitors.

[0110] A peripheral-sealing structure (872) may be applied to a thin film metal (e.g., nitinol) layer (821) on the periphery and / or around the plate (870), for example, directly. The peripheral structure (872) may have the form of a raised flange, a step, a lip, a rim, or a similar structure and may generally provide a sealing contact surface (879) for sealing to a corresponding surface of the base structure (980). The peripheral structure (872) may provide a structure that protrudes in a direction perpendicular to the surface of the nitinol layer (821) to offset the capacitor electrode(s) (822) from the base (980). For example, a top surface (879), which may include 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).

[0111] The sensor base (980) may have a capacitive electrode (981) formed thereon, which may be paired with a corresponding one of the capacitive electrodes (822) of the diaphragm plate (870), so that when the plate (870) is coupled to the base (980), a variable capacitance based at least partially on the deflection state of the diaphragm (825) may exist between the plates (822, 981) and be measured. The electrode(s) (981), which may have a fixed non-deflection attachment / structure, may be combined with the deflection electrode(s) (822) to form one or more variable capacitors having a capacitance that varies according to the deflection state of the electrode(s) (822). The static properties of the base electrode (e.g., cathode) (981) may be provided by coupling and / or integration with a rigid or semi-rigid substrate structure (901). One of the electrodes (822, 981) may have an elliptical (e.g., circular) shape as illustrated.

[0112] The base (980) may additionally include a predetermined electrical contact (991) configured to contact / bond to a corresponding electrical contact (871) of the diaphragm plate (870). That is, the contact (991) of the base (980) may be electrically separated from the capacitor plate (981), but may be electrically coupled to the electrode (822) through the contact (871) which can be bonded together at the coupling interface (1007) as shown in FIG. 10 when the diaphragm plate (870) is bonded to the base structure (980). The contact (991) may be configured in such a way that it does not make direct contact with the capacitor plate (981) through various electrical interconnections, but both the capacitor plate (981) and the electrical contact (991) may ultimately be connected in the same capacitive residence circuit to allow the capacitance between the plates (822, 981) to be measured. The static / fixed capacitor electrode (981) may be axially aligned with and / or centrally positioned with the dynamic capacitor electrode (822) when the pieces (870, 980) are joined / coupled together. The electrical contact portion (991) may have the form of a raised flange, a stepped portion, a lip portion, a rim portion, or a similar structural portion, and may generally provide a contact surface for electrically connecting with the corresponding surface (871) of the diaphragm plate (870).

[0113] The physical contact and sealing area between the diaphragm plate (870) and the base plate (980) can be formed through the peripheral protrusion (992). The dimensions of the electrical contact flanges (991, 872) can be designed and set to a known distance to separate the capacitive electrodes (822 and 981) by a desired distance. For example, the opposing flange contacts (991 and 871) can physically contact each other to create an electrical connection between the plates (870, 980) as well as define the precision of the offset of the electrodes (981, 822). The contact flanges (992, 1372) can provide a peripheral seal for hermetic sealing of the device (1000). The peripheral structure (992) of the base (980) may advantageously extend across the entire periphery of the base substrate (901) and, accordingly, when in close contact with the structured periphery (872) of the diaphragm plate (870), the connection interface between the peripheral structures may provide a hermetic seal that protects the internal cavity (1009) from the external environment. The internal cavity (1009) may be filled with air or other inert gas, or vacuum sealed. In an embodiment where the cavity (1009) contains a vacuum, the sensor may provide an absolute pressure sensor. Alternatively, some embodiments may include a gas present within the cavity (1009) / volume that can be used as a relative pressure sensor embodiment. Additionally, the cavity (1009) may provide a ventilation path with a large volume. Such a larger ventilation volume may advantageously reduce air compression resistance, while allowing the cathode and anode to be placed very close to each other with a minimum / small volume between the electrodes.

[0114] The substrate (901) of the base structure (980) (e.g., cathode structure) may comprise ceramic, glass, or any other suitable material, regardless of whether it is rigid or flexible. For example, the substrate (901) may comprise a printed circuit board and / or a dedicated integrated circuit comprising a predetermined circuit portion configured to handle the capacitance signal of the capacitor(s) (1095), and / or may be associated therewith. The base substrate (901) may comprise a predetermined electrical connection portion configured to facilitate proper electrical coupling of each capacitor plate (822, 981). For example, a specific via or other connection portion may be connected through at least a portion of the thickness of the substrate (901).

[0115] In some embodiments, the deflection of the diaphragm (825) is measured independently to provide a separate sensor signal, thereby providing an additional level of sensitivity. For example, different capacitors (1095) have different mmHg / F curves (or electrode displacement change amount per mmHg). Δz It can be adjusted (e.g., zero point adjustment) to have a curve based on other units such as ), thereby explaining tissue growth that may accumulate unevenly on one capacitor diaphragm (825) compared to other capacitor diaphragms. In the embodiments of FIGS. 8–10, the three capacitors (1095) may operate as a single capacitor sensor or may be separated by a predetermined electrical contact / connection to create three separate capacitors. In some embodiments, the capacitor electrode (822) and / or capacitor electrode (981) may contain gold.

[0116] The bonding / joining (1005) between the lid structure (870) and the base structure (980) may be implemented using one or more gold-tin (AuSn) layers and / or gold (Au) layers so as to create a relatively hard / good bonding / joining that provides both a hermetic seal and an electrical interface between the nitinol material of the lid (870) and the non-nitinol material of the base (980). Since bonding with materials similar to nitinol (e.g., thin film nitinol) is generally difficult due to molecular structure and temperature response, the use of the eutectic metal alloy AuSn allows for effective bonding while protecting the molecular integrity of the substrate. Because the AuSn bonding / joining can provide biocompatible and electrical pathways between the components, the exemplary AuSn bonding / joining technique of the present disclosure may be particularly useful for sensor applications in which a sensing mechanism involving conversion and / or electrical coupling between nitinol and non-nitinol components is implemented.

[0117] Generally, when nitinol is exposed to high temperatures, or even to lower temperatures for extended periods, the material may not remain superelastic and may transform into an amorphous material. A gold-tin alloy (AuSn) can advantageously be eutecticed at a specific composition, and thus the alloy can be melted at a relatively low temperature (e.g., as low as 280°C), so that the melting can form a bond / joint at a temperature that does not disturb the crystal structure of nitinol. Thus, an AuSn-nitinol bond as described in detail below may be useful for bonding to a nitinol structure, such as the bond (1005) described above in relation to FIGS. 8–10, to create a closed and electrically bonded nitinol structure.

[0118] FIGS. 11a and 11b illustrate front and rear perspective views of a sensor lid / diaphragm structure (1170) according to one or more embodiments. The lid / structure (1170) may be used in an alternative sensor design comprising one or more internal sensor device chambers in which a pressure transfer medium (e.g., oil, gel) is disposed therein, wherein capacitor electrodes are not conformally deposited on the nitinol layer(s), but rather the lid (1170) is configured to transmit deflection of one or more sensor devices and nitinol diaphragms to the internal sensor device(s) (an embodiment related to such a pressure transfer fluid sensor device is described in detail above).

[0119] The lid (1170) includes a thin film nitinol layer covering the diaphragm area. In some embodiments, the lid structure (1170) may include a built-up NiTi material (1164) around the diaphragm (1125), wherein the raised can structure (1164) provides at least a portion of a volume / space of a cylindrical or other shape, and this space may be filled with a pressure-transmitting fluid when the lid structure (1170) is assembled with a base structure to form a sensor device. In some embodiments, a raised diaphragm outer structure is not formed around the diaphragm(s) (1125). For example, any cylindrical or other shaped volume / space where the pressure of the pressure-transmitting fluid is placed may be exclusively associated with the base structure (1280).

[0120] The lid structure (1170) may include a peripheral sealing flange (1172) that rises over a nitinol sheet / layer (1121) and / or (if implemented) a thicker nitinol structure (1164) around the diaphragm(s) (1125a, 1125b, 1125c) (based on the orientation of FIG. 11a). The peripheral sealing flange (1172) may include a step, lip, rim, or similar structure as described above in relation to other embodiments, which is physically bonded to the base and configured to provide a gap between the nitinol layer(s) (1121, 1164) and the base. As illustrated, the flange (1172) may be formed of at least a portion of the nitinol formed / deposited on the layer (1121) to create a raised structure. In some embodiments, the peripheral flange (872) is coplanar with the raised forming(s) (1164) around the diaphragm. For example, the lid may comprise a thin film diaphragm layer(s) (1121) and a raised outer forming (1164) without an additional raised nitinol forming. Rather, a binder (e.g., AuSn) may be applied to this integrated forming (1164), such as the shape of the preform forming placed against the forming (1164 / 1172).

[0121] In some embodiments, one or more gold-tin (AuSn) layers are disposed on or adjacent to the nitinol flange (1172) to provide a binder for bonding the lid (870) to the base (980) (see FIG. 9). The AuSn layers may be deposited using sputtering, vapor deposition, or other process(s), or may be solid preform structures physically disposed on the nitinol structure, having a stadium shape as illustrated, or other shapes, regardless of whether an intermediate oxide is interposed between the two materials.

[0122] FIG. 12 illustrates a base structure (1280) for a capacitive sensor device (1300) according to one or more embodiments. FIG. 13a and FIG. 13b illustrate a schematic view and a side cross-sectional view, respectively, of a sensor device (1300) comprising a diaphragm lid / structure (1170) physically coupled to the base structure (1280).

[0123] The sensor base (1280) may have one or more cylinders or other volumes / spaces (1209) into which the sensor device (1210) can be placed / separated, and accordingly, when the lid (1170) is coupled to the base (1280), a fluid medium (1252) (e.g., an incompressible fluid such as oil or gel) may be placed within the can space (1209) around the sensor (1210). In this configuration, the pressure condition / reading associated with the sensor device(s) (1210) may be affected by the deflection state of each diaphragm (1125) and may indicate a deflection state. The can (1209) may have a raised flange (1391) around it, which may be sealed to the corresponding structure of the lid (1170) to provide a fluid-tight chamber for pressure sensing. Although a secondary seal (1391) is illustrated, it should be understood that the device (1300) may not include such seal(s), and rather, an external hermetic seal (1305) may serve to accommodate the pressure-transmitting fluid medium. For example, the cavity (1309) may not be present in some embodiments.

[0124] The area of ​​physical contact and sealing between the diaphragm plate (1170) and the base plate (1280) can be achieved through the peripheral protrusion (1392). When the base contact portion (1392) comes into close contact with the diaphragm plate (1170), the connection interface (1305) can provide a hermetic seal that protects the internal structure / component from the external environment.

[0125] The substrate (1201) of the base structure (1280) may comprise ceramic, glass, or any other suitable material, regardless of whether it is rigid or flexible. For example, the substrate (1201) may comprise a printed circuit board and / or a dedicated integrated circuit comprising a predetermined circuit portion configured to handle the capacitance signal of the capacitor(s) and / or may be associated therewith. The joint / bond (1305) between the lid structure (1170) and the base structure (1280) may be implemented using one or more gold-tin (AuSn) layers and / or gold (Au) layers (1178) so as to create a relatively rigid / good joint / bond that provides a hermetic seal between the nitinol material of the lid (1170) and the non-nitinol material of the base (1280), and possibly also an electrical interface.

[0126] FIGS. 10b and 13b illustrate a diaphragm lid structure and a sensor implemented on one side of a base substrate, but it should be understood that any of the sensor and bonding features disclosed herein may also be implemented in a sensor device having a double-sided sensor feature. FIGS. 14a and 14b respectively illustrate a perspective view and a side cross-sectional view of a double-sided sensor device (1400) according to one or more embodiments. Various features illustrated and referenced in FIGS. 14a and 14b may be understood by referring to the descriptions in FIGS. 8a, 8b, 9, 10a, and 10b above. Although the double-sided sensor device (1400) is illustrated as a sensor device having an conformal capacitive electrode formed on a nitinol diaphragm, it should be understood that the double-sided sensor device may also be implemented in connection with a pressure-transmitting-fluid can / chamber embodiment.

[0127] FIGS. 15a and FIGS. 15b respectively illustrate an exploded view and an assembled / bonded view of a material stack structure bonding / bonding (150) that can provide a hermetic seal between a thin film nitinol (or other metal) layer (152) and a heterogeneous substrate (e.g., ceramic, glass) using a gold-tin alloy filler according to one or more embodiments. The bonding / bonding (150) may be used to bond nitinol (or other similar superelastic material) to a heterogeneous (e.g., non-nitinol) substrate(s) of any embodiment disclosed herein. Various embodiments of the present disclosure are described in the context of gold-tin bonding to nitinol. However, it should be understood that embodiments of gold-tin bonding disclosed herein may be implemented for bonding to any sputtered material, and references to the nitinol layer / substrate herein may be understood as referring to embodiments using other sputtered materials. Such materials may include any thin film metal such as titanium, tantalum, etc. Exemplary sputtered materials may be deposited using vapor deposition, electrodeposition, thermal deposition, or any process in which a solid substrate is converted into a gaseous form and re-solidified to be applied onto a substrate. Additionally, alloys other than Nitinol, such as Kovar (nickel-cobalt-iron alloy), may be used in gold-tin bonding to provide a desirable hermetic seal. Such bonded layers / substrates may be associated with / integrated with thin-wall pressure-transforming structures.

[0128] 2) Ti is a reasonable alternative material (biocompatible) with some advantages and disadvantages. If a broader sputtering process can be claimed to produce diaphragms (a full range of biocompatible low-permeability metals including Ti, stainless steel, and nitinol) for pressure conversion in the body (applicable to both transfer fluid and dry cap configurations) and to combine them with AuSn, this will cover the scope intended to be protected by this invention.

[0129] The stack structure (150) comprises a nitinol layer / form (152) (or a similar superelastic material) bonded to a non-nitinol material (158) (e.g., ceramic, glass, PCB) using one or more layers (155) of a eutectic gold-tin (AuSn) alloy or other eutectic metal. In some embodiments, the AuSn layer(s) (155) may comprise about 80 wt% gold (Au) and 20 wt% tin (e.g., with a margin of error of about 5 wt%). Such compositions may provide a eutectic alloy, which melts or solidifies at a single temperature similar to a pure metal, without spanning a temperature range like many alloys. The eutectic temperature for the AuSn layer (155) can advantageously be relatively low, for example, about 280°C (536°F), which is significantly lower than the melting point of pure gold (1064°C or 1947°F). The AuSn layer, which may be a preform layer, may have a thickness of about 25 μm or other thicknesses.

[0130] Intermediate gold-tin (AuSn) layer(s) (155) are interposed between the nitinol (151) and base (159) structures and can provide desirable thermal and electrical conductivity features, wettability, and corrosion resistance for use in chronic implant devices. Additionally, AuSn as configured in the embodiments disclosed herein can be joined using heat / soldering techniques, and the high thermal conductivity of the material helps with heat dissipation, while the high electrical conductivity can facilitate reliable electrical connections. The relatively low eutectic point of AuSn (155) can also minimize thermal stress during joining / soldering, which can not only protect sensitive sensor components but also prevent molecular deformation of the adjacent nitinol (152).

[0131] As described above, the bonding line of the sensor implant housing may have a layer similar to the layer shown in FIG. 15b, which illustrates layers combined together to create an airtight and / or electrically conductive seal. In some embodiments, a layer(s) (155) of gold-tin (AuSn) is deposited on a thin film nitinol (152) and / or a base substrate (158), with or without intermediate seed layer(s) (154, 156) of gold and / or other metals (e.g., vapor deposition or placement as a preform structure). Intermediate gold (154, 156) may be included to improve the bondability, compatibility, and / or functionality between the nitinol (152) and the glass / ceramic (or other substrate) (158), which may not be directly bonded to or sufficiently interact with each other for the purposes of the bonded device.

[0132] A gold-tin (AuSn) layer (155) hermetically bonds 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) may have a thickness of less than 1 μm. The gold seed layer (156) may be lithographically patterned / sputtered onto a substrate (158). In some embodiments, the AuSn layer(s) (155) may be applied to the substrate (158) without an intermediate gold layer (156). It should be understood that the glass and / or ceramic structures and materials disclosed herein are described as such to provide exemplary embodiments, and that any of these mentioned structures / materials may include any type(s) of non-metallic (e.g., inorganic) material(s), such as woven glass fiber fabrics, epoxy resin binders, plastics, polymers, or even metallic structures such as stainless steel.

[0133] The seed layer material (153, 157) for the gold layer (156) may be selected based on the applied material. For example, the seed layer (153) may be titanium suitable for forming an interface with the nitinol layer (150). For the seed layer (157), the material may be nickel or titanium, considering its suitability for forming an interface with ceramic or similar materials. Layers (157 and 156) may be collectively considered as seed layers for the substrate (158), and layers (153 and 154) may be collectively considered as seed layers for the thin film nitinol (152).

[0134] A thin film nitinol (152), which can be formed using physical vapor deposition (PVD) or a similar process, can be metallized with a gold layer (154) having acceptable adhesion between the layers, which can provide a desirable interface for applying gold-tin intermediate layer(s) (155) between the nitinol (152) and a non-nitinol substrate (158). For example, the PVD nitinol (152) can be conformally metallized with pure gold using sputtering technology or other processes. Seed layers (153, 157) can each provide an intermediate layer necessary for applying the gold layer (154, 156).

[0135] The gold (Au) layer(s) (154, 156) can advantageously form a good bond with the AuSn alloy while facilitating adhesion through the ability of gold to adhere well to nitinol, glass, ceramic, and other substrates. Additionally, the gold layer(s) (154, 156) can provide a desirable barrier layer to prevent undesirable interactions between nitinol (152), glass / ceramic (158), and AuSn (155), such as diffusion or chemical reactions, which could weaken the bond or alter the properties of the material. Furthermore, since gold is an excellent conductor of electricity and heat, the gold layer(s) (a54, 156) can advantageously impart these properties to the entire structure (150). The gold layer(s) (154, 156) can also serve to prepare the AuSn layer (155) to be deposited more effectively on the surface of the nitinol (152) and ceramic / glass (158), thereby ensuring a more uniform and consistent layer. Although described as using gold, other metals such as nickel, palladium, titanium, titanium alloy, aluminum, platinum, etc., may be used for the layer(s) (154, 156). In some embodiments, the nitinol stack (151) comprises nitinol about 1 to 3 μm thick having a sputtered titanium-tungsten (TiW) barrier metal (153), and the AuSn layer (155) is bonded thereto. The intermediate TiW (or other material described herein) barrier advantageously allows the AuSn to remain in a molten state for a certain period of time to be attached to the base gold layer (154).

[0136] The intermediate seed layer (153, 157) may comprise any suitable or desirable gold, or gold-tin, intermediate interface, such as titanium, chromium, nickel, copper alloy, silver, platinum alloy, palladium alloy, titanium alloy, etc. In some embodiments, the layer(s) (153, 157) comprises an oxide. The layer(s) (153, 157) may improve the adhesion of the gold layer to the nitinol (152) and / or glass / ceramic (158), and / or modify the surface properties (e.g., electrical properties) of the glass / ceramic in a desirable way. The layer (153, 157) may comprise any suitable or desirable oxide, such as an oxide of titanium or chromium. In some embodiments, the layer (153) may comprise titanium dioxide naturally formed on the surface of the nitinol, which may be modified through various treatments. Other options include silicon dioxide, niobium pentoxide, and other oxides that can provide an insulating layer and / or can preferably modify surface properties for improved adhesion or functionalization. The substrate seed layer (157) may include silicon dioxide, titanium dioxide, aluminum oxide, aluminum oxide, zirconium dioxide, yttrium oxide, or other similar oxides.

[0137] In some embodiments, a gold-tin (AuSn) layer (155) is introduced into the stack structure (150) as a preform structure interposed / placed between gold-seed layers. For example, the preform may comprise an AuSn layer cut for a specific track, which may have a thickness of less than 100 μm, e.g., about 50 μm or less, or 25 μm or less. The preform (155) may be sandwiched between two layers (151, 159). In some embodiments, the AuSn preform (155) is stamped / machined from a sheet, laser cut, or die cut. In some embodiments, the gold-tin (AuSn) layer (155) is grown on a thin film nitinol (155). An AuSn 'preform' as described herein may comprise a piece of material that is pre-shaped or formed into a specific configuration, such as a track surrounding the outer periphery, before undergoing reflow. These preforms can be shaped into specific forms similar to the final desired shape of the AuSn seal / joint. The use of AuSn preforms can help reduce the amount of machining or processing required to achieve the final shape and size of the hermetic and / or electrical seal. Additionally, it helps ensure consistency and uniformity in the manufacturing process. AuSn preforms as described herein can be manufactured using various techniques such as casting, extrusion, and powder metallurgy.

[0138] As illustrated in FIG. 15b, the bonded stack structure (150) can be formed using standard semiconductor packaging tools, such as flip-chip bonding, to accurately align and apply controlled force and heat, thereby creating a hermetic seal. In certain applications, creating a biocompatible interface may require additives or fluxes that could potentially cause harm to the body. In contrast, the use of a gold-tin (AuSn) alloy for bonding as disclosed herein enables bonding that does not require fluxes or other chemicals to create the bond. Rather, in the embodiments of the present disclosure, the bonding process may include a step of providing an inert gas during bonding, which alone is sufficient to create a hermetic seal. The present disclosure provides various combinations of using AuSn for medical implants. The combination of FIG. 15a and 15b, as with other embodiments presented herein, can allow low-temperature mechanical bonding of nitinol on heterogeneous materials such as glass and ceramic.

[0139] FIGS. 16a and FIGS. 16b respectively illustrate an exploded view and an assembled / bonded view of another configuration of a material stack structure (160) that can provide a hermetic seal between a thin film nitinol (or other metal) layer (162) and a heterogeneous substrate (168) (e.g., ceramic, glass) using a gold-tin alloy filler (165) according to one or more embodiments. The bonded stack structure (160) of FIGS. 16a and FIGS. 16b is similar to the configuration of FIGS. 15a and 15b, except that the thin film nitinol (162) has gold-tin (AuSn) (164) applied without an intermediate gold layer. AuSn (e.g., Au80Sn20) (164) can be sputtered directly onto the nitinol (152).

[0140] In some embodiments, an additional preform AuSn layer (165) may be interposed / placed between the AuSn-seed nitinol stack (161) and the non-nitinol substrate stack (169). Although illustrated as including a gold seed layer (166), it should be understood that in any of the embodiments disclosed herein, a ceramic, glass, or similar substrate may be seeded to AuSn (164) in the same manner as the nitinol stack (161). The AuSn seed layer (164) may be sputtered directly onto the thin film nitinol (162) in an conformal manner or applied in any other suitable manner. The AuSn seed layer (164) may include an intermediate 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 intermediate layer (167) such as titanium, chrome, nickel, etc.

[0141] FIGS. 17a and FIGS. 17b respectively illustrate an exploded view and an assembled / bonded view of another material stack structure (170) that can provide a hermetic seal between a thin film nitinol (or other metal) layer (172) and a heterogeneous substrate (178) (e.g., ceramic, glass) using a gold-tin alloy filler (175) according to one or more embodiments. In an exemplary configuration (170), a relatively thick layer of gold-tin (AuSn) (175) (e.g., stoichiometrically accurate Au80Sn20) is sputtered directly onto a thin film nitinol (172) (including an intermediate seed layer (173) if possible). For example, the thickness of the AuSn layer (175) may be greater than 20 μm.

[0142] The substrate (178) can be seeded with gold (176) or a similar metal, such as chrome, titanium, nickel, etc., which can be formed on the intermediate layer (177). The seeded base substrate (179) can be bonded to the nitinol stack (171) by reflow / melting of the AuSn layer (175).

[0143] By implementing a thicker AuSn layer (175), it may not be necessary or desirable to include additional AuSn preform layers (such as the preform layers (155, 165) described above in relation to FIG. 15a / 15b and FIG. 16a / 16b, respectively). That is, the use of AuSn preform structures may be completely excluded, and a thicker sputtered layer of AuSn (175) applied directly onto the thin film (172) may replace them. This configuration may be desirable because it reduces the number of components of the bonding line stack (170) and provides a relatively cleaner material composition through controlled sputtering application.

[0144] In relation to FIGS. 15–17, or any of the aforementioned bonding line stacks disclosed elsewhere in this disclosure, may include gold-tin (AuSn) layer(s) used to bond nitinol and non-nitinol structures together by applying heat and / or force to the AuSn layer(s) and / or other components according to an appropriate temperature and force profile. FIG. 18 illustrates a temperature profile for a nitinol bonding / bonding process for heterogeneous materials, such as ceramics, glass, or printed circuit boards, using one or more AuSn layer(s), for example, according to some embodiments.

[0145] FIG. 18 illustrates a process in which an AuSn bonding line is heated from a baseline (BL) temperature through a gradual heating method to the melting temperature (181) of AuSn (e.g., about 280°C / 536°F), maintained for a sufficient time to bond the AuSn to the nitinol and non-nitinol structures, and then the temperature can be lowered back to the baseline temperature. FIG. 19 illustrates a force profile for a process of bonding different materials using one or more gold-tin layer(s) according to one or more embodiments. As shown in FIG. 19, at the time of initiation of heating for AuSn bonding, the structures to be bonded together may be pressed with pressure contact to promote attachment to the AuSn, thereby facilitating bonding between the materials. The bonding force (191) is a time over which the AuSn (and / or other component(s)) is under the heating temperature (181). t It can be maintained for a period of time (see Fig. 18). As illustrated, the holding force can be applied during the period before maximum heating and during the period after maximum heating. That is, the bonded components can be pressurized against each other for at least some period of the temperature rise and / or fall phases.

[0146] FIGS. 20a, 20b, and 20c each illustrate a schematic, enlarged, and side cross-sectional view of a wafer (2000) having a plurality of structures (2070) having a gold-tin bonding surface (2075) formed thereon, according to one or more embodiments. The wafer (2000) may have a plurality of molds / substrates formed thereon for the deposition of thin film nitinol structures, such as sensor device lid structures, so that a single wafer may be utilized to produce a relatively large number of diaphragm plates / stacks for a pressure sensor device according to an embodiment of the present disclosure. In the description below, the reference numeral '2070' may refer to an individually shaped substrate of the wafer (2000) upon which thin film nitinol layer(s) are deposited, or may refer to a thin film nitinol layer / plate structure deposited on the substrate.

[0147] The wafer (2000) comprises a plurality of diaphragm structures / shapes (2070), each shape (2070) may comprise a separate sensor diaphragm plate or may be used to create one. Each illustrated plate (2070) may function as a substrate / mandrel / mold, and a thin film diaphragm layer of a nitinol metal alloy or similar material may be deposited thereon to form a thin film diaphragm plate comprising nitinol or other superelastic material with a thickness of, for example, less than 10 μm (e.g., 4 to 6 μm; about 5 μm). The layer(s) of nitinol may have a uniform thickness in both the diaphragm region (2025) and the surrounding structure (2029).

[0148] The forming body / plate (2070) may be configured to have a gap (2001) around one or more parts of the periphery (2029) of each diaphragm plate forming body (2070), which may facilitate the deposition of nitinol and / or other layers of the diaphragm plate in a relatively precise area and / or shape, and / or facilitate the singulation of the individual diaphragm plate (2070) after a forming step of mechanically separating the individual plate from the wafer structure (2000). A physical connector (2002) may be used to connect the diaphragm plate substrate (2070) to an external structure (2005) of the wafer (2000) which may act as a sprue / tap structure anchoring the individual substrate (2003) to the external coupon / structure (2005). The internal portion (2003) of the structure (2000) (e.g., the substrate (2070) for nitinol deposition) can be detached from the wafer (2000), or the deposited layer of the material (e.g., nitinol, insulator, electrode) can be removed from the substrate without detaching the substrate (2003).

[0149] The wafer (2000) may be formed from any suitable or desirable material such as silicon, stainless steel, titanium, nickel, alumina, sapphire, glass, ceramic, etc. Once the nitinol base diaphragm layer (2025) is deposited on the plate structure (2003), additional layers may be applied to the diaphragm plate using masking and / or other suitable processes. A thin film nitinol (e.g., 5 μm) diaphragm layer (2025) may be deposited on the substrate (2003), and an additional peripheral flange structure (2029) may be formed / built-up on the peripheral area and / or other area of ​​the substrate (2003) using vapor deposition or other processes. Gold-tin (AuSn) (2075) may be applied to the peripheral area (2029) of the nitinol structure (2070) (e.g., via direct sputtering). The total thickness of the nitinol structure (2070) in the peripheral region (2029) together with the AuSn bonding layer (2075) can advantageously be 3 to 6 μm.

[0150] FIGS. 21a and 21b respectively illustrate an exploded view and an assembled / bonded view of a gold-tin bonding stack (210) comprising a nitinol stack (211) bonded to a base substrate stack (219) comprising a hard-stop forming body (201) according to one or more embodiments. The hard-stop (201) has a critical bonding line gap distance / height ( d 1It can be used to provide ). As illustrated, the hard-stop (201) may be positioned laterally to the outside of at least one portion of the gold-tin junction (215) (i.e., between the gold-tin (215) and the outside of the device including the stack structure (210). As with other embodiments disclosed herein, the thin film nitinol structure (211) may be gold-seeded with a layer of gold (214) (or similar metal) and / or an intermediate seed layer (213) (e.g., titanium, chromium, platinum, nickel, etc.). Likewise, the base substrate (219) may include a layer (218) of ceramic, glass, etc., and may be gold-seeded with a layer of gold (216) (or similar metal) and / or an intermediate seed layer (217) (e.g., chromium, titanium, silicon dioxide, tungsten, etc.). The gold seed layer(s) may be patterned on each material by lithography or applied in other ways. The hard-stop forming body disclosed herein may comprise a metal and / or may be formed using a metal manufacturing process. However, it should be understood that any hard-stop disclosed herein may comprise a non-metal forming body, such as a ceramic, glass, or other rigid material, and the corresponding non-metal forming body / substrate extruded from such material.

[0151] A hard stop (201) that can help make the bonding between the nitinol (211) and non-nitinol (219) structures more reproducible and / or reliable can be formed and / or configured in various ways. For example, the use of hard-stop forming(s) can provide an alignment mechanism that can facilitate the reproducible placement of gold-tin preforms. The hard stop (201) may include gold or a similar metal, and a set distance ( d 1It may be extruded or formed in some other way to provide ). As described throughout this disclosure, when a gold-tin (AuSn) joint is formed between structures (211, 219), the AuSn layer (215) (e.g., a preform structure) may be melted similarly to solder. That is, as the AuSn (215) eutecticizes, it melts and takes on a liquid form of AuSn, thereby allowing it to flow outward to some extent when compressed / pressed in the vertical direction (based on the orientation of FIG. 21a and 21b) without maintaining a rigid layer thickness when force is applied. The thickness of the AuSn layer (215) is dimensional ( d 1 To prevent the hard-stop (201) from decreasing to less than ) the structure (211, 219) has an interposed thickness dimension ( d 1 It prevents the separation distance from approaching the dimensions allowed by ), thereby allowing the AuSn layer (215) to be compressed to a very specific dimension / height ( d 1 Allows setting to ).

[0152] Physical vapor deposition processes provide various tools for creating extrusions such as hard-stop extrusions (201). For example, the extrusion (201) can be sputtered / vapor deposition, electroplated, patterned, or coated using electron beam deposition, focused ion beam milling or deposition, laser microfabrication, etc.

[0153] FIG. 22a illustrates a sensor base structure (229) comprising an embossed hard-stop bump (203) according to one or more embodiments. FIG. 22b and 22c illustrate an exploded and assembled / bonded view of a device (220) comprising a gold-tin joint (225) between a nitinol (221) and a non-nitinol (228) structure, wherein the gap between the bonded structures ( d 2) is set / determined by a hard-stop bump (203). The hard-stop 203 is implemented as an embossed gold bump to provide an accurate distance ( d 2 () can be provided, thereby enabling direct reflow using AuSn (225) as a eutectic solder to bond the structures together. In some embodiments, the bump (203) is a gold stud bump ultrasonically placed on a ceramic (or glass, PCB, etc.) substrate (228). This process can implement standard semiconductor packaging technology using gold ball wirebonder equipment. For example, unlike the process of placing a first ball joint and then pulling out a thin gold cable as is done in some wire-bonded integrated circuit chip applications, the cable can be cut immediately to leave a hard stop extrusion. To flatten this extrusion, the ball joint can be 'pressed'. Since gold is generally ductile, this process can be performed by pressing the ball joint, flattening the extrusion, and deforming the ball joint into a more cylindrical shape. The base structure (229) may include a recess (202) having a lower layer (204) configured to provide a volume for placing a sensor device, wherein the volume (202) may be filled with a pressure-transmitting fluid as described in detail herein.

[0154] The hard-stop (203) can be formed by masking and electroplating, or alternatively by using a gold stud having a configuration similar to a microchip wire bond. In some embodiments, the hard-stop bump (203) is a flattened cut wire to create an embossed form, rather than being extruded. That is, without forming a full wire bond, the gold wire can be cut to leave a bump, where the bond is created using an ultrasonic mechanism to form a solid metal-to-metal bond. The bump (203) can be embossed to a thickness of less than 20 μm (e.g., 10 to 20 μm). The bump (203) can be embossed by physical pressure, as the gold material constituting it is malleable. The embossing can be performed using equipment configured to implement ultrasonic pulses while extruding the gold wire to create the metal-to-metal bond.

[0155] The gold hard-stop bump (203) is advantageously not a eutectic, and the bump (203) remains in a solid state and dimensions ( d 2 To maintain ) it has a higher melting point than gold-tin (225). That is, during the heating process to melt the AuSn layer (225), due to the corresponding eutectic properties, AuSn becomes the only layer / material that melts.

[0156] FIG. 23a illustrates a sensor base structure (239) comprising a hard-stop extrusion (206) according to one or more embodiments. FIG. 23b and 23c illustrate, respectively, an exploded view and an assembled / bonded view of a gold-tin (AuSn) joint comprising a hard-stop extrusion (206). The hard-stop extrusion (206) may have the form of a continuous flange surrounding an intermediate region of the structure (239) on the inner radius of the AuSn joint track (235). The base structure (239) may include a recess (205) having a lower layer (207) configured to provide a volume for placing a sensor device, wherein the volume (205) may be filled with a pressure-transmitting fluid as described in detail herein.

[0157] Hard-stop (206) is a hard-stop dimension ( d 3 It may include an electrodeposited gold (Au) extrusion that can be formed into a continuous eutectic flow blocking flange / rib providing. For example, the gold seed layer of the base structure (238) may be patterned to form a track that is not a continuous plane. In some embodiments, the ceramic (or other material) substrate (238) may be patterned to create a flange (206), regardless of whether it contains a gold layer thereon. For example, a hard-stop flange may be formed on the ceramic or glass substrate (238), and a thin gold layer may be applied over the flange. The hard-stop flange (206) can advantageously prevent the molten gold-tin (AuSn) layer (235) (e.g., preform structure) from flowing into the internal sensor space (205).

[0158] When melted, the AuSn layer (235) has dimensions ( d 3It can be pushed outward when compressed / flattened to a thickness of ) and can fill the edge of the joined assembly by being pushed outward from the flange (206). The hard-stop (206) can be dimensioned so that no substantial volume of AuSn is pushed outward when the lid (231) and the base (238) are joined.

[0159] FIGS. 24a and 24b respectively illustrate an exploded view and an assembled / bonded view of a gold-tin (AuSn) junction stack structure (240) comprising overlapping bonding / sealing portions (302a, 302b) according to one or more embodiments. The structure (240) comprises a nitinol stack (241) comprising a nitinol thin film substrate (242) having a plurality of tracks (245) of an AuSn junction forming body, which may have an intermediate seed layer (243) having any suitable material as described herein. The nitinol stack (241) is bonded to a non-nitinol substrate (248) seeded with gold (246) and a non-nitinol substrate stack (249) comprising an optional intermediate layer (247).

[0160] The bonding line of the stack (240) comprises a plurality of segments (245a, 245b) of gold-tin (AuSn) to form a plurality of bonding line seals. For example, the AuSn (245a, 245b) may be patterned in such a way that they create laterally spaced AuSn formations (245a, 245b), which in some embodiments may be at least partially insulated from each other thermally and / or electrically. Physical vapor deposition or other process(s) may be utilized to form the segmented AuSn bonding formations. For example, lithography may be implemented for this purpose, thereby allowing any pattern to be patterned. The space (301) between the AuSn formations may be filled with air, vacuumed, or filled with another material selected to provide desirable insulation or other properties. By implementing redundant AuSn seals, the remaining seal(s) may advantageously be independently sufficient to provide hermetic seals, so that even if one of the AuSn seals fails or becomes inefficient, it may not cause failure of the hermetic seal of the stack (240). Thus, redundant AuSn seals as disclosed herein can provide a failure-safe mechanism for implant devices and other applications. Additionally, the use of redundant seals can provide improved structural and / or electrical properties for the implant joint line. Some of the following embodiments provide variations of redundant AuSn seals according to aspects of the present disclosure.

[0161] Individual bonding tracks (302a, 302b) may be patterned into continuous tracks, and one or both of these tracks provide hermetic and / or electrical interfaces / sealings. Overlapping bonding as disclosed herein can address potential problems related to mismatches in the coefficients of thermal expansion between bonded materials. Additional bonding can accommodate thermal deformation and provide countermeasures against bonding failure. For example, overlapping tracks / bondings (302a / 302b) can provide mechanical advantages for hermetic sealing, such as protection against a damaged bond propagating cracks / defects throughout the seal. For example, a defect in bonding (302a) may be confined to that bonding due to a spatial separation (301) that prevents structural defects from affecting adjacent bonding (302b). Additionally, since thermal expansion is a process associated with volume change, the relatively small volume of the segmented bonding can reduce the volume expansion difference.

[0162] FIGS. 25a and 25b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure (250) having one or more gold-tin (AuSn) seals (255) disposed on a nitinol bonding line structure according to one or more embodiments. In the embodiments of FIGS. 25a and 25b, the AuSn seals (255) provide a track seal around a periphery (259) of the structure (250), wherein the periphery (259) comprises nitinol built up around the outside of the structure (250) to provide a hermetic seal surrounding an inner diaphragm (252). Although it is illustrated as having a peripheral built-up / protrusion (259), it should be understood that in some embodiments, the nitinol region (252, 259) has a uniform thickness such that the peripheral (259) of the nitinol layer and the surface of the diaphragm (252) are in the same plane. The diaphragm structure (250) may be bonded to a corresponding base structure (not shown in FIG. 25a and 25b for visual clarity) according to any embodiment disclosed herein.

[0163] FIGS. 26a and 26b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure (260) having one or more gold-tin (AuSn) seals (265) disposed on a nitinol bonding line structure according to one or more embodiments. In the embodiments of FIGS. 26a and 26b, the AuSn seals (265) provide a track seal around a periphery (269) of the structure (260), wherein the periphery (269) comprises nitinol built-up around the outside of the structure (260) to provide a hermetic seal surrounding an inner diaphragm (262). The structure (250) further comprises an inner nitinol built-up (267) around a row of diaphragms (262) that may have an elliptical shape / boundary as illustrated. Although illustrated as having peripheral and internal built-up / protrusions (269, 267), it should be understood that in some embodiments, the nitinol regions (262, 267, 269) have a uniform thickness such that the peripheral (269) and internal (267) nitinol and the surface of the nitinol diaphragm (262) are in the same plane. The diaphragm structure (260) may be bonded to a corresponding base structure (not shown in FIG. 26a and 26b for visual clarity) according to any embodiment disclosed herein.

[0164] FIGS. 27a and 27b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure (270) having one or more gold-tin (AuSn) seals (275) disposed on a nitinol bonding line structure according to one or more embodiments. In the embodiments of FIGS. 27a and 27b, the AuSn seals (275) provide a track seal around a periphery (279) of the structure (270), wherein the periphery (279) comprises nitinol built up around the outer periphery of the structure (270) to provide a hermetic seal surrounding an inner diaphragm region (272). Compared to the embodiments of FIGS. 25a / 25b and FIGS. 26a / 26b, the diaphragm structure (270) does not include a plurality of elliptical thin film diaphragms, but rather includes a single diaphragm (272) within a space surrounded by the periphery seals (275 / 279). Although it is illustrated as having a peripheral built-up / protrusion (279), it should be understood that in some embodiments, the nitinol region (272, 279) has a uniform thickness such that the peripheral (279) and the surface of the nitinol diaphragm (272) are on the same plane. The diaphragm structure (270) may be bonded to a corresponding base structure (not shown in FIG. 27a and 27b for visual clarity) according to any embodiment disclosed herein.

[0165] FIGS. 28a and 28b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure (280) having overlapping parallel gold-tin (AuSn) seals (285) according to one or more embodiments. The diaphragm structure (280) may be joined to a corresponding base structure (not shown in FIGS. 28a and 28b for visual clarity) according to any embodiment disclosed herein.

[0166] In the embodiments of FIGS. 28a and 28b, the AuSn seal (285) provides a track seal (285) parallel to the periphery of the structure (280), wherein the periphery includes a Nitinol track (289) on which AuSn (285) is formed, built-up around the outer periphery of the structure (280) to provide a hermetic seal surrounding an inner diaphragm region (282). The redundant seal (289 / 285) may be implemented for any embodiment disclosed herein, for example, for any one of the periphery seals of the embodiments of FIGS. 25a / 25b, 26a / 26b, or 27a / 27b described above. Additionally, while two parallel seals are shown, it should be understood that the redundant seal according to the embodiments of the present disclosure may have any number of parallel or non-parallel seals. Although it is illustrated as having a peripheral built-up / protrusion (289), it should be understood that in some embodiments, the nitinol region (282, 289) has a uniform thickness such that the peripheral region / track (289) of the nitinol layer and the surface of the nitinol diaphragm (282) are coplanar. In such embodiments, AuSn can simply be applied onto the uniform nitinol layer in the illustrated sealing track pattern.

[0167] Parallel tracks (285a / 289a, 285b / 289b) may have the same common width, or one of the tracks may be wider than the other. Parallel tracks (285) may provide lateral space (286) between adjacent tracks, and this space may be filled with air, vacuumed, or filled with a material suitable for providing insulation and / or structural support for the parallel tracks when the diaphragm structure (280) is assembled as a sensor device or other sealed assembly. By using multiple overlapping tracks separated by lateral spacing between tracks, flexibility in the area of ​​the seal may be increased. Thermal expansion mismatch occurs at the corresponding bonding surface / structure of the base to which the bonding protrusion (299 / 295) and the plate (290) may be bonded. Thus, in contrast to the solid tracks of FIGS. 25–27, laterally discontinuous overlapping tracks may help to mitigate the mismatch.

[0168] FIGS. 29a and 29b respectively illustrate a plan view and a side cross-sectional view of a diaphragm structure (290) having parallel gold-tin (AuSn) seals (295) according to one or more embodiments. The diaphragm structure (290) may be hermetically joined to a corresponding base structure (not shown in FIGS. 29a and 29b for visual clarity) using the AuSn seals (295) according to any embodiment disclosed herein.

[0169] In the embodiments of FIGS. 29a and 29b, the AuSn seal (295) provides three parallel track seals (295a, 295b, 295c) around the periphery of the structure (290), wherein the periphery includes a Nitinol track (299) on which AuSn (295) is formed / coated, built-up around the outer periphery of the structure (290) to provide a hermetic seal surrounding an inner diaphragm region (292). The overlapping seal (299 / 295) may be implemented for any embodiment disclosed herein, for example, for any one of the periphery seals of the embodiments of FIGS. 25a / 25b, 26a / 26b, or 27a / 27b described above. Additionally, while three parallel seals are illustrated, it should be understood that the overlapping seal according to the embodiments of the present disclosure may have any number of parallel or non-parallel seals. Although it is illustrated as having a peripheral built-up / protrusion (299), it should be understood that in some embodiments, the nitinol region (292, 299) has a uniform thickness such that the peripheral region / track (299) of the nitinol layer and the surface of the nitinol diaphragm (292) are coplanar. In such embodiments, AuSn can simply be applied onto the uniform nitinol layer in the illustrated sealing track pattern.

[0170] Parallel tracks (295a / 299a, 295b / 299b, 295c / 299c) may have the same common width, or one of the tracks may be wider than the other. For example, in the illustrated embodiment, the middle track (299b / 295b) is wider than the inner track (299c / 295c) and the outer track (299a / 295a); any combination of relative track widths may be implemented in relation to the embodiments of the present disclosure, including an embodiment in which the outermost track is wider than one or more inner tracks, or the innermost track is wider than one or more outer tracks. Parallel tracks (299) may provide a lateral space (296) between adjacent tracks, and this space may be filled with air, vacuumed, or filled with a material suitable for providing insulation and / or structural support for the parallel tracks when the diaphragm structure (290) is assembled as a sensor device or other sealed assembly.

[0171] FIG. 30 illustrates a plan view of a diaphragm structure (300) having a gold-tin seal (394, 395) of a grid pattern according to one or more embodiments. The seal may include a plurality of parallel tracks (395) that may extend along the periphery of the structure (300), as well as a plurality of tracks (394) perpendicular to the periphery track(s), so that the paths of the tracks (395) and the tracks (394) intersect. This grid pattern may create a cell (393) surrounded by the seal tracks (394, 395), and such a cell may be air-filled, vacuum-sealed, or filled with a material suitable for providing insulation and / or structural support for the parallel tracks. Although the tracks (394, 395) are generally depicted as having a vertical arrangement, embodiments may include tracks having any suitable or desirable relative angle.

[0172] FIGS. 31a, 31b, and 31c illustrate a separated, exploded, and bonding / assembly view of a material stack structure (325) comprising a plurality of gold-tin (AuSn) bonds (314, 324) according to one or more embodiments. The process disclosed herein may be implemented to create a first AuSn bond by melting an AuSn layer, and then to create one or more subsequent AuSn bonds without disturbing or reworking the previous bond(s). Through this process, it becomes possible to assemble a plurality of thin film nitinol components (311, 321) on a single substrate (317). A double-sided AuSn bond as illustrated in FIGS. 31a through 31c may be used in applications such as the double-sided diaphragm sensor (1400) illustrated in FIGS. 14a and 14b, which comprises AuSn bonds on both sides of a base substrate (1401).

[0173] FIG. 31a illustrates a material stack structure joint / bond (310) having a previously implemented hermetic seal between a thin film nitinol (or other metal) layer (311) and a first surface (308) of a heterogeneous substrate (317) (e.g., ceramic, glass) using a gold-tin alloy filler (314), which may be similar to any of the gold-tin bond structures disclosed herein. In some embodiments, the AuSn layer(s) (314) may comprise about 80 wt% gold (Au) and 20 wt% tin (e.g., within a margin of error of about 5 wt%). Such a composition may provide a eutectic alloy, and the material melts or solidifies at a single temperature similar to a pure metal, without spanning a temperature range like many alloys. The eutectic temperature for the AuSn layer (314) can advantageously be relatively low, for example, about 280°C (536°F), which is significantly lower than the melting point of pure gold (1064°C or 1947°F).

[0174] The gold-tin (AuSn) layer (314) hermetically bonds the nitinol (311) and ceramic / glass (317) stacks, each of which may have a seed layer (312 / 313, 315 / 316) such as the gold seed layer as described above. The seed layer material (312, 316) for each gold layer (313, 315) may include titanium, nickel, chromium, or other materials described herein. The gold (Au) layer(s) (313, 315) may advantageously provide a barrier as described above and / or facilitate adhesion. The bonded stack structure (310) may be formed using standard semiconductor packaging tools, such as flip-chip junctions, to accurately align and apply controlled force and heat, thereby creating a hermetic seal.

[0175] In addition to the gold seeding and gold-tin (AuSn) bonding implemented on the upper surface (308) of the base substrate (317) (based on the orientation of FIG. 31a), the substrate (317) may be further prepared for bonding on the other surface (309) of the substrate (317) (e.g., the lower surface based on the orientation of FIG. 31a), and this additional bonding may be implemented after the AuSn bonding (314) is completed. Thus, as shown in FIG. 31a, the lower surface (309) of the ceramic or glass (or other material) substrate (317) may be seeded with a gold or other metal layer (319) and / or an intermediate metal / oxide layer (318) (e.g., titanium).

[0176] Where a gold-tin (AuSn) bond (314) has been previously implemented, as illustrated in FIG. 31b and 31c, the stack structure (310) can subsequently be bonded to another thin-film nitinol structure (320). That is, the second surface (309) of the substrate (317) can be bonded to the nitinol layer (321) through an AuSn layer (324), which can be bonded to the nitinol (321) through a seed layer comprising gold, AuSn, titanium, and / or other suitable materials. Subsequently bonding the nitinol layer / stack (320) to the substrate (317) without disturbing the previously implemented bond (314) can be facilitated by the ability of the AuSn alloy (314), after being reflowed over the gold seed layer(s) (313, 315) via eutectic alloying, to significantly increase its melting temperature. For example, during the reflow of the AuSn layer (314), heat diffuses and mixes the gold and tin atoms of the AuSn layer (314) at the interface between the gold seed layer(s) and the deposited AuSn alloy, thereby inducing a change in its melting characteristics, and through this stoichiometric change, the melting point of the AuSn joint (314) is increased.

[0177] FIG. 32 is a graph showing the relationship between the weight-based content of gold and tin in a gold-tin (AuSn) alloy according to one or more embodiments and the associated melting point. As shown in the graph, when the concentration of tin (Sn) is negligibly low, gold (Au) melts at about 1000°C, whereas as Sn is added to the alloy, the melting temperature tends to drop sharply until it reaches a local minimum melting temperature (303) of about 280°C at a ratio of 80% Au to 20% Sn, and after passing that point, the melting temperature rises again by a certain amount and then drops gradually again as the Sn concentration increases. Since a higher Au concentration can provide better electrical conductivity characteristics, a lower melting temperature (303) associated with a local minimum on the side of the spectrum with a higher Au concentration may be more desirable than the melting temperature of an alloy with a higher Sn concentration. Accordingly, Au80Sn20 and nearby concentrations having a melting point located at or adjacent to a local minimum (303) may be advantageous for the applications disclosed herein in reflow below the transformation temperature of nitinol.

[0178] Referring again to FIG. 31a, the diffusion of AuSn molecules following the reflow of the AuSn layer (314) can advantageously induce the formation of a higher concentration of Au and a lower concentration of Sn within the bonding layer (314) through the diffusion of tin (Sn) into the gold (Au) seed layer(s) (313, 315) and / or the diffusion of Au from the Au seed layer(s) (313, 315) into the AuSn layer (314), thereby causing the melting point of the layer (314) to rise again to a higher melting temperature (e.g., above 320°C, e.g., about 350°C) along the melting curve shown in FIG. 32. Accordingly, since the melting temperature of the previously formed joint (314) is elevated, the subsequent reflow of the AuSn joint / layer (324) can be implemented at a lower melting temperature (about 280°C or nearby) without melting / disturbing the layer (314) with a higher Au concentration. The diffusion of Au into the AuSn layer (314) may vary depending on the thickness of the Au layer(s) (313, 315). Thus, the melting temperature of the AuSn layer (314) can be controlled at least partially by implementing a specific thickness(s) for the Au layer(s) (313, 315). By raising the melting temperature of the AuSn layer (314) to 280°C, i.e., above the minimum value of 280°C, subsequent heating of the layer (314) does not reach a eutectic melting temperature that could disturb the joint, which is an important aspect for hermetic sealing. Therefore, the diffusion of adjacent Au into AuSn can provide significant advantages for the bonding of hermetic devices.

[0179] FIGS. 33a and FIGS. 33b illustrate an exploded and joining / assembly view of a structure (330) having gold-tin joint(s) (401, 402) that provide hermetic sealing and electrical connection between a nitinol substrate (332) and a non-nitinol substrate (348) according to one or more embodiments, wherein the substrate (332, 348) is integrated with a conductive path electrically connected across the joint(s) (402), a passive electronic device, and / or an active electronic device. As described herein, in addition to forming a hermetic seal, gold-tin (AuSn; e.g., Au80Sn20) can provide the ability to electronically connect a functional thin film nitinol (332) to a passive (e.g., printed circuit board (PCB), flex cable, or microelectronic device 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 (348).

[0180] FIG. 33a illustrates 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) via physical vapor deposition or other processes, as described in detail above. An intermediate layer (373) of a high dielectric constant, such as titanium oxide or other suitable oxide, may be interposed between the gold layer (482) and the nitinol (332). Additionally, gold-tin (AuSn) forming(s) (471) may be applied to the electrode (482) to provide an electrical contact portion to the electrode (482). The nitinol substrate (332) may additionally include AuSn bumps / tracks (335) outside the electrode (482) region to provide a hermetic bond to the device / structure (330), wherein the bonding tracks (335) may be configured to provide a hermetic seal around the electrode (482), so that the assembled device (330) may be suitable for, for example, implantation in the human body and maintenance for a long time. The hermetic bonding structure (335) may be seeded with a seed material (333), such as titanium or other suitable metal / oxide.

[0181] The base substrate (348) may comprise any suitable material in which an electrical element can be integrated. In some embodiments, the base substrate (348) comprises a bonding protrusion / track (346), which may be bonded to an opposing AuSn junction (335) to form a hermetic seal (401). The substrate (348) may further comprise an electrode or other passive or active circuit portion (481). The electrode (481) may function as a counter electrode to a capacitive electrode (482) associated with the nitinol substrate (332), which may be implemented on the seed layer (373). Thus, when combined as shown in FIG. 33b, the electrode (482, 481) may function as a plate of a capacitor, which may be used in pressure sensing applications or other applications. Embodiments of such a sensor device have been described in detail.

[0182] The base substrate (348) may further include an electrical contact (491) which may include gold or other conductive metal, and such contact (491) is configured to be bonded to an AuSn electrical contact (471) associated with a nitinol substrate (332). The assembled configuration shown in FIG. 33b illustrates an electrical internal junction (402) and a hermetic peripheral junction (401) formed so that any number / type of converter directly integrated on the thin film nitinol substrate (332) can be connected to an electronic device / circuit associated with the corresponding active or passive substrate (348). Intermediate seed layers (247, 377) may be implemented for the AuSn layers (347, 491), respectively.

[0183] In some embodiments, the same junction may be formed on the inside (402) and outside (401) of the device (330) in terms of material composition and / or arrangement. The diaphragm in FIG. 33b illustrates the electrical connection / junction through a resistor icon. Generally, the AuSn junction (402) may provide sufficiently low electrical resistance to accommodate use in sensor applications and other applications described herein.

[0184] The junction forming body (335) can be implemented as a flip-chip bump / forming body that allows for the flip-chip combination demonstrated by the diaphragm of FIG. 33a and 33b. Accordingly, according to an embodiment of the present disclosure, a sensor electronic device, e.g., an electronic device integrated on a thin film nitinol substrate (e.g., multiple capacitive electrodes, multiple piezoresistors) can be connected to individual AuSn junction forming bodies, and the connection to these junction forming bodies can be formed using traditional flip-chip junction techniques to bond the nitinol to a flexible cable or other substrate.

[0185] FIGS. 34a and 34b respectively illustrate a plan view and a side view of a nitinol sensor structure / device (351) having a gold-tin (AuSn) electrical contact (354) according to one or more embodiments. FIG. 35 illustrates a nitinol sensor structure / device (351) having a gold-tin electrical contact (354) joined to a corresponding electrical contact (366) of an electrical device / substrate (368) according to one or more embodiments.

[0186] As illustrated, AuSn solder bumps (354) are directly patterned onto a thin film nitinol substrate (352) and can be connected between any number / type of sensors / transducers (353) on the nitinol (352) to form an electrical connection. The electrical connection between the AuSn contacts (354) and each sensor element (353) can be made through a conductive trace (355) formed on the nitinol (352). Similar to solder bumps used in flip-chip bonding, AuSn junction forms (354) can also be used for a similar purpose. In the illustrated configuration, a plurality of AuSn junction pads (354) are connected to one or more nodes of the sensors (353), which may be passive or active electrical elements implemented on the nitinol (352). For example, in some embodiments, the sensor(s) (352) may include a plurality (e.g., nine) of gold, platinum, or other microelectrode(s) or other types of electrode(s) used to capture an electrocardiogram (ECG) signal. Each microelectrode may be electrically connected to a corresponding AuSn solder bump (354) and wired onto a base / substrate (368).

[0187] The substrate (368) may be a flexible cable or other passive (e.g., printed circuit board (PCB), flex cable, or microelectronic 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, etc.) substrate. The substrate (368) may have contact pads (366) that may include gold or other conductors seeded on the substrate (368), wherein the pads (366) are aligned with AuSn pads (354) in a flip-chip array. Due to the low melting temperature of the AuSn junction pads (354), the nitinol structure configuration (351) provides the ability to bond multiple nitinol components on the same substrate (368) without negative disturbance to the previous bonding portion.

[0188] When implemented as a gold-tin (AuSn) solder bump, the contact pad (354) may not include gold seeding for the AuSn bump, as it may be difficult to implement the AuSn contact through the stacking of preform AuSn. Rather, the AuSn pad (354) can advantageously be sputtered directly onto the nitinol (352). The contact (366) on the substrate (368) may provide a gold seed layer for the AuSn bond. The illustrated layer (356) may include a nickel-titanium mixture of a certain composition, or other layers used to create the bond, such as a metal with a thickness in the range of 5 to 100 nm.

[0189] The AuSn contact bump (354) may have a height of any suitable height, such as about 15 to 20 μm, which may be sufficient to achieve a solid joint and accommodate the relevant planar tolerance. The AuSn bump (354) may not provide a hermetic seal due to its non-inclusive form / configuration. Accordingly, the combined device (350) may be implemented using a peripheral seal, which may or may not include AuSn as described in detail herein.

[0190] Vascular / cardiac access for sensor implantation

[0191] A packaged sensor implant device according to one or more examples of the present disclosure may be advanced to an associated target ventricle or blood vessel and / or vascular system of the heart using any suitable or preferred procedure. FIG. 36 is a cross-sectional view of a human heart (1) and an associated vascular system showing a specific catheter (111) access route for an implantation procedure for implanting a sensor device (370), which may be similar in one or more respects to any of the embodiments disclosed herein according to one or more embodiments. Specifically, access to various ventricles / blood vessels of the heart may be made through the right atrium (5) and / or inferior vena cava (16) using a delivery system (111), for example, via a transfemoral or other transcatheter procedure. Such access routes are indicated by reference numeral 111a. Reference numeral 111b indicates access to the right atrium (5) through the superior vena cava. In some embodiments, access to the left atrium (2) or left ventricle may be made using a transseptal approach, which may be made by entering the left atrium (2) from the right atrium (5) through the septal wall (18) via the inferior vena cava (16) or superior vena cava (19), respectively, as illustrated. In the case of a transaortic approach, a delivery catheter (111c) may enter the left atrium (2) through the mitral valve (6) by passing through the descending aorta (27), the aortic arch (12), the ascending aorta, and the aortic valve (7). In the case of a transapical approach, a delivery catheter (111d) may directly enter the left ventricle (3) via the apex (39) of the heart (1) and the left atrium (2) via the mitral valve (6). Other access routes other than the route illustrated in FIG. 36 are also possible. Various transcatheter delivery systems and routes described may include the steps of transporting a sensor implant device (1900) within the shaft / lumen of the corresponding device and deploying the device (1900) from the delivery system at a target anatomical site.

[0192] Further explanation of the examples

[0193] A list of embodiments is provided below, each of which may include an aspect of any other embodiment disclosed herein. Additionally, any aspect of any of the aforementioned embodiments may be implemented in any of the numbered embodiments provided below.

[0194] Example 1: A sealing structure comprising a nitinol layer, a non-nitinol material layer, and a eutectic gold-tin intermediate layer configured to bond the nitinol layer to the non-nitinol layer.

[0195] Example 2: Any one of the embodiments of the present invention, particularly Example 1, wherein the non-nitinol material is ceramic or glass, a sealing structure.

[0196] Example 3: Any one of the embodiments of the present invention, particularly Example 2, a sealing structure further comprising a gold seed layer interposed between a eutectic gold-tin layer and a non-nitinol material layer.

[0197] Example 4: Any one of the embodiments of the present invention, particularly Example 3, wherein the gold seed layer comprises a gold layer and a layer interposed between a non-nitinol material layer and the gold layer, the gold layer comprising at least one of chromium, titanium, tungsten, or palladium, a sealing structure.

[0198] Example 5: Any one of the embodiments of the present invention, particularly Example 1, a sealing structure further comprising a gold-tin seed layer interposed between a eutectic gold-tin layer and a nitinol layer.

[0199] Example 6: Any one of the embodiments of the present invention, particularly Example 1, wherein the eutectic gold-tin layer is 80 wt% gold and 20 wt% tin prior to reflow, a sealing structure.

[0200] Example 7: A sealing structure configured such that, in any one of the embodiments of the present invention, particularly Example 6, the eutectic gold-tin layer is reflowed and the gold content by weight is increased from the gold layer interposed between the eutectic gold-tin layer and the nitinol layer or a layer of non-nitinol material, thereby increasing the melting point of the gold-tin layer.

[0201] Example 8: Any one of the embodiments of the present invention, particularly Example 1, a sealing structure in which a eutectic gold-tin layer is sputtered onto a nitinol layer.

[0202] Example 9: Any one of the embodiments of the present invention, particularly Example 1, a sealing structure in which the nitinol layer is a thin film layer formed using physical vapor deposition.

[0203] Example 10: Any one of the embodiments of the present invention, particularly Example 9, further comprises a sputtered gold layer applied to a nitinol layer, said sputtered gold layer interposed between the nitinol layer and the eutectic gold-tin layer.

[0204] Example 11: Any one of the embodiments of the present invention, particularly Example 1, a sealing structure in which the eutectic gold-tin layer is a preform structure.

[0205] Example 12: Any one of the embodiments of the present invention, particularly Example 1, further comprising a hard-stop shape interposed between a nitinol layer and a non-nitinol material layer, wherein the metal hard-stop shape has a melting point higher than the melting point of the eutectic gold-tin layer.

[0206] Example 13: Any one of the embodiments of the present invention, particularly Example 12, wherein the hard-stop feature is a sealing structure having a track feature.

[0207] Example 14: Any one of the embodiments of the present invention, particularly Example 12, wherein the hard-stop feature is a sealing structure having a bump feature.

[0208] Example 15: Any one of the embodiments of the present invention, particularly Example 12, wherein the metal hard-stop shape is configured to laterally block the eutectic gold-tin layer from flowing past the metal hard-stop shape when the eutectic gold-tin layer is melted, a sealing structure.

[0209] Example 16: A sealing structure in which, in any one of the embodiments of the present invention, particularly Example 1, the nitinol layer and the eutectic gold-tin layer are bonded to a first surface of a non-nitinol material layer, and the second nitinol layer is bonded to a second surface of the non-nitinol material layer through a second layer of gold-tin.

[0210] Example 17: Any one of the embodiments of the present invention, particularly Example 1, a sealing structure in which the eutectic gold-tin layer provides an electrical path that electrically couples a first conductor on a nitinol layer to a second conductor on a non-nitinol material layer.

[0211] Example 18: An implantable sensor device comprising a vapor-deposited nitinol layer including one or more deflection diaphragms, a non-nitinol base substrate, and one or more gold-tin shaped bodies bonded between the nitinol layer and the base substrate, wherein the one or more gold-tin shaped bodies provide a hermetic seal between the nitinol layer and the base substrate.

[0212] Example 19: Any one of the embodiments of the present invention, particularly Example 18, further comprising a first capacitive electrode formed conformally on one of one or more deflection diaphragms of a nitinol layer, and a second capacitive electrode coupled to a base substrate, wherein the second capacitive electrode and the first capacitive electrode form a variable capacitor.

[0213] Example 20: An implantable sensor device comprising, in any one of the embodiments of the present invention, particularly Example 19, one or more gold-tin electrical contacts providing an electrical connection between a first capacitive electrode and an electrical element associated with a base substrate.

[0214] Example 21: Any one of the embodiments of the present invention, particularly Example 18, an implantable sensor device further comprising one or more gold contacts formed on a base substrate and configured to be bonded to one or more gold-tin forming bodies.

[0215] Example 22: An implantable sensor device comprising, in any one of the embodiments of the present invention, particularly Example 18, one or more gold-tin electrical contacts each electrically coupled to one or more of the sensor elements implemented on the nitinol layer.

[0216] Example 23: An implantable sensor device comprising, in any one of the embodiments of the present invention, particularly Example 22, further comprising one or more electrical contacts implemented on a base substrate and arranged to be bonded to one or more gold-tin electrical contacts at a flip-chip connection.

[0217] Example 24: An implantable sensor device in which, in any one of the embodiments of the present invention, particularly Example 22, one or more gold-tin electrical contacts are disposed on a track around the periphery of a nitinol layer.

[0218] Example 25: An implantable sensor device comprising: a vapor-deposited nitinol layer comprising one or more deflection diaphragms, a non-nitinol base substrate, and a hermetic seal formed between the nitinol layer and the base substrate, wherein the hermetic seal is formed as a track around the periphery of the nitinol layer comprising eutectic gold-tin.

[0219] Example 26: Any one of the embodiments of the present invention, particularly Example 25, wherein the track comprises one or more nitinol tracks, and gold-tin is formed thereon, an implantable sensor device.

[0220] Example 27: An implantable sensor device in which, in any one of the embodiments of the present invention, particularly Example 26, one or more nitinol tracks comprise a plurality of redundant parallel tracks.

[0221] Example 28: An implantable sensor device in which, in any one of the embodiments of the present invention, particularly Example 27, a plurality of parallel tracks are formed by two parallel tracks extending along the periphery of a nitinol layer.

[0222] Example 29: An implantable sensor device in which, in any one of the embodiments of the present invention, particularly Example 27, a plurality of parallel tracks are formed by three parallel tracks extending along the periphery of a nitinol layer.

[0223] Example 30: An implantable sensor device in any one of the embodiments of the present invention, particularly Example 29, wherein the central track among the three parallel tracks has a width greater than the widths of the inner track and the outer track among the three parallel tracks.

[0224] Example 31: An implantable sensor device comprising, in any one of the embodiments of the present invention, particularly Example 25, a metal hard-stop structure disposed on the inner radius of the track to set a gap dimension between the nitinol layer and the base substrate.

[0225] Example 32: A method for bonding a nitinol structure to a non-nitinol structure, comprising: providing a first thin film nitinol structure; providing a non-nitinol base structure; placing a first eutectic gold-tin forming body between the first nitinol structure and a first surface of the base structure; and reflowing the first gold-tin forming body to bond the first nitinol structure to the first surface of the base structure.

[0226] Example 33: A method in which, in any one of the embodiments of the present invention, particularly Example 32, prior to the reflow step, the first gold-tin forming body is a solid preform structure.

[0227] Example 34: Any one of the embodiments of the present invention, particularly Example 32, a method further comprising the step of forming a seed layer on a first surface of a base structure prior to the reflow step of the first gold-tin forming body.

[0228] Example 35: Any one of the embodiments of the present invention, particularly Example 34, a method in which the seed layer comprises a gold layer.

[0229] Example 36: Any one of the embodiments of the present invention, particularly Example 35, a method further comprising the step of increasing the melting point of the first gold-tin formation by diffusing gold from a seed layer into the first gold-tin formation during the reflow step of the first gold-tin formation.

[0230] Example 37: Any one of the embodiments of the present invention, particularly Example 36, a method further comprising the step of reflowing a second gold-tin structure onto a second surface of a base structure after the reflow step of the first gold-tin structure to bond a second thin film nitinol structure to said second surface of the base structure.

[0231] Example 38: In any one of the embodiments of the present invention, particularly Example 37, a method in which, when the second gold-tin forming body is reflowed, the second gold-tin forming body is not melted because the second gold-tin forming body has a melting point lower than the melting point of the first gold-tin forming body.

[0232] Example 39: Any one of the embodiments of the present invention, particularly Example 32, a method further comprising the step of pressing a nitinol structure against a base structure while reflowing a gold-tin formed body to facilitate bonding.

[0233] Example 40: Any one of the embodiments of the present invention, particularly Example 32, a method further comprising the step of pressing the nitinol structure against the base structure to compress the gold-tin formation between the nitinol structure and the base structure.

[0234] Example 41: Any one of the embodiments of the present invention, particularly Example 40, a method in which the step of compressing the gold-tin forming body is limited by a non-nitinol hard-stop forming body disposed between a nitinol structure and a base structure.

[0235] Example 42: Any one of the embodiments of the present invention, particularly Example 32, a method further comprising the step of transmitting an electrical signal from a first electrical element on a first nitinol structure to a second electrical element on a base structure through a junction.

[0236] Example 43: A method in which, in any one of the embodiments of the present invention, particularly Example 32, the reflow step of the first gold-tin forming body is implemented in a state where the first nitinol structure and the base structure are in a flip-chip array.

[0237] Example 44: A sealing structure comprising a first substrate having a layer of sputtered material, a second substrate having a layer of non-sputtered material, and an intermediate layer of eutectic gold-tin configured to bond the first substrate and the second substrate.

[0238] Example 45: A sealing structure in which, in any one of the embodiments of the present invention, particularly Example 44, the sputtered material is nitinol.

[0239] Example 46: A sealing structure in which, in any one of the embodiments of the present invention, particularly Example 44, the sputtered material is titanium.

[0240] The methods and structures disclosed herein for treating a patient also include similar methods and structures performed on or deployed thereon with respect to a simulated patient, which are useful, for example, for education, demonstration, procedure and / or device development, etc. The simulated patient may be physical, virtual, or a combination of physical and virtual. The simulation may include a simulation of all or part of a patient, for example, the whole body, a part of the body (e.g., the chest), a system (e.g., the cardiovascular system), an organ (e.g., the heart), or any combination thereof. The physical element may be natural, including a human or animal cadaver or a part thereof; synthetic; or any combination of natural and synthetic. The virtual element may be a whole, or may be overlaid on one or more of the physical components. The virtual element may be presented on any combination of a screen, headset, holography, projection, loud speakers, headphones, pressure transducers, or temperature transducers, or may be presented using any combination of suitable technologies.

[0241] Any various systems, devices, instruments, etc. in the present disclosure may be sterilized (e.g., with heat, radiation, ethylene oxide, hydrogen peroxide, etc.) to ensure safety of use for patients, and the method of the present invention may include sterilization of associated systems, devices, instruments, etc. (e.g., using heat, radiation, ethylene oxide, hydrogen peroxide, etc.).

[0242] According to the embodiments, specific actions, events, or functions of any process or algorithm described herein may be performed in a different order, added, merged, or excluded together. Accordingly, in certain embodiments, not all described actions or events are essential to the implementation of the method.

[0243] In particular, conditional language used herein, such as “can,” “could,” “may,” “for example,” etc., unless otherwise specifically stated or understood within the context in which they are used otherwise, generally implies that a given embodiment does not include a specific feature, element, and / or step, while the given embodiment is intended to include such feature, element, and / or step. Accordingly, such conditional language is not intended to imply that a feature, element, and / or step is generally required in any way for one or more embodiments, or that one or more embodiments necessarily include logic to determine whether such feature, element, and / or step will be included or performed in any particular embodiment, depending on the author’s input or prompt. Terms such as “including,” “comprising,” “having,” etc., are synonyms and are used in their ordinary senses and are used in an open and inclusive manner, and do not exclude additional elements, features, actions, operations, etc. Additionally, the term "or" is used in its inclusive sense (though not its exclusive sense) so that, for example, when used to link a list of elements, the term "or" implies one, some, or all of the elements within the list. Unless otherwise specifically stated, conjunctions such as the phrase "at least one of X, Y, and Z" are generally understood in the context of being used to convey that an item, term, element, etc., may be any one of X, Y, or Z. Accordingly, such conjunctions are generally not intended to imply that a particular embodiment requires the existence of at least one of X, at least one of Y, and at least one of Z, respectively.

[0244] In the description of the embodiments described above, it should be understood that various features may be grouped together in a single embodiment, drawing, or description for the purpose of simplifying the disclosure and facilitating understanding of one or more of the various aspects of the invention. However, the method of the disclosure shall not be interpreted as reflecting an intention that any claim requires more features than explicitly cited in the claim. Furthermore, any component, feature, or step exemplified and / or described in a particular embodiment of the present invention may be applied to or used in conjunction with any other embodiment(s). Also, a component, feature, step, or group of components, features, or steps is not necessary or indispensable to each embodiment. Accordingly, the scope of the invention disclosed herein and claimed below is not intended to be limited by the particular embodiments described above, but is to be determined only by a fair interpretation of the following claims.

[0245] It should be understood that specific ordinal terms (e.g., "first" or "second") may be provided for convenience of reference and do not necessarily imply physical characteristics or order. Accordingly, as used herein, ordinal terms used to modify elements such as structures, components, operations, etc. (e.g., "first," "second," "third," etc.) do not necessarily indicate the priority or order of the element relative to any other element, but can distinguish that element from other elements having similar or identical names (however, in the case of the use of ordinal terms). Furthermore, as used herein, the indefinite articles (“a” and “an”) may indicate “one or more” rather than “one.” Additionally, an action performed “based on” a condition or event may also be performed based on one or more other conditions or events not explicitly cited.

[0246] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which the exemplary embodiments pertain. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with that of the relevant art field, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0247] Spatially relative terms "external," "internal," "upper," "lower," "below," "upper," "vertical," "horizontal," and similar terms may be used herein for convenience of description to explain the relationship between one element or component and another element or component as illustrated in the drawings. It will be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation illustrated in the drawings. For example, if the device illustrated in the drawings is inverted, another device may be positioned "below" or "under," and another device may be positioned "above." Thus, the exemplary term "below" may include both lower and upper positions. The device may also be oriented in different directions, and therefore spatially relative terms may be interpreted differently depending on the orientation.

[0248] Unless otherwise explicitly stated, comparative and / or quantitative terms such as "less," "more," "greater," etc., are intended to include the concept of equality. For example, "less" can mean not only "small" in the strictest mathematical sense but also "less than or equal to."

Claims

Claim 1 As an implantable sensor device: comprising a sealing structure, wherein the sealing structure is: Nitinol layer; non-nitinol material layer; and An implantable sensor device comprising a eutectic gold-tin intermediate layer configured to bond the nitinol layer to the non-nitinol layer. Claim 2 An implantable sensor device according to claim 1, wherein the non-nitinol material is ceramic or glass; and the sealing structure further comprises a gold seed layer interposed between a eutectic gold-tin layer and a non-nitinol material layer. Claim 3 An implantable sensor device according to claim 2, wherein the gold seed layer comprises a gold layer and a layer interposed between a non-nitinol material layer and the gold layer, and the gold layer comprises at least one of chromium, titanium, tungsten, or palladium. Claim 4 An implantable sensor device according to any one of claims 1 to 3, further comprising a gold-tin seed layer interposed between a eutectic gold-tin layer and a nitinol layer. Claim 5 An implantable sensor device according to any one of claims 1 to 3: wherein the eutectic gold-tin layer is 80 wt% gold and 20 wt% tin prior to the reflow step; and wherein the eutectic gold-tin layer is reflowed and the gold content is increased by weight from the gold layer interposed between the eutectic gold-tin layer and the nitinol layer or a layer of non-nitinol material, thereby increasing the melting point of the gold-tin layer. Claim 6 An implantable sensor device according to any one of claims 1 to 3, wherein the eutectic gold-tin layer is sputtered onto a nitinol layer. Claim 7 An implantable sensor device according to any one of claims 1 to 3, wherein the nitinol layer is a thin film layer formed using physical vapor deposition; and the sealing structure further comprises a sputtered gold layer applied to the nitinol layer, said sputtered gold layer interposed between the nitinol layer and the eutectic gold-tin layer. Claim 8 An implantable sensor device according to any one of claims 1 to 3, wherein the eutectic gold-tin layer is a preform structure. Claim 9 An implantable sensor device according to any one of claims 1 to 3, further comprising a metal hard-stop shape interposed between a nitinol layer and a non-nitinol material layer, wherein: the metal hard-stop shape has a melting point higher than the melting point of a eutectic gold-tin layer; and the metal hard-stop shape is configured to laterally block the eutectic gold-tin layer from flowing past the metal hard-stop shape when the eutectic gold-tin layer melts. Claim 10 An implantable sensor device according to any one of claims 1 to 3, wherein: a nitinol layer and a eutectic gold-tin layer are bonded to a first surface of a non-nitinol material layer; and a second nitinol layer is bonded to a second surface of a non-nitinol material layer through a second layer of gold-tin. Claim 11 An implantable sensor device according to any one of claims 1 to 3, wherein the eutectic gold-tin layer provides an electrical path that electrically couples a first conductor on a nitinol layer to a second conductor on a non-nitinol material layer. Claim 12 An implantable sensor device comprising: a vapor-deposited nitinol layer including one or more deflected diaphragms; a non-nitinol base substrate; and one or more gold-tin features bonded between the nitinol layer and the base substrate, wherein the one or more gold-tin features provide a hermetic seal between the nitinol layer and the base substrate. Claim 13 An implantable sensor device according to claim 12, further comprising: a first capacitive electrode formed conformally on one of one or more bias diaphragms of a nitinol layer; and a second capacitive electrode coupled to a base substrate, wherein the second capacitive electrode and the first capacitive electrode form a variable capacitor. Claim 14 An implantable sensor device according to claim 13, further comprising one or more gold-tin electrical contacts that provide an electrical connection between a first capacitive electrode and an electrical element associated with a base substrate. Claim 15 An implantable sensor device according to any one of claims 12 to 14, further comprising one or more gold contact portions formed on a base substrate and configured to be bonded to one or more gold-tin forming bodies. Claim 16 An implantable sensor device according to any one of claims 12 to 14: one or more gold-tin electrical contacts each electrically coupled to one of each of one or more sensor elements implemented on a nitinol layer; and one or more electrical contacts implemented on a base substrate and disposed to be joined to the one or more gold-tin electrical contacts at a flip-chip connection. Claim 17 An implantable sensor device according to any one of claims 12 to 14, further comprising one or more gold-tin electrical contacts electrically coupled to each of one or more sensor elements implemented on a nitinol layer, wherein the one or more gold-tin electrical contacts are disposed on a track around the periphery of the nitinol layer. Claim 18 An implantable sensor device comprising: a vapor-deposited nitinol layer comprising one or more deflected diaphragms; a non-nitinol base substrate; and a hermetic seal formed between the nitinol layer and the base substrate, wherein the hermetic seal is formed as a track around the periphery of the nitinol layer comprising eutectic gold-tin. Claim 19 An implantable sensor device according to claim 18: the track comprises one or more nitinol tracks, wherein a gold-tin layer is formed thereon; said one or more nitinol tracks comprises two or more parallel tracks extending along the periphery of the nitinol layer. Claim 20 An implantable sensor device according to claim 18 or 19, further comprising a metal hard-stop structure disposed on the inner radius of the track to set a gap dimension between the nitinol layer and the base substrate. Claim 21 A method for 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; placing a first eutectic gold-tin formation between the first nitinol structure and a first surface of the base structure; and reflowing the first gold-tin formation to bond the first nitinol structure to the first surface of the base structure. Claim 22 The method of claim 21 further comprises: a step of forming a seed layer on a first surface of a base structure before the reflow step of the first gold-tin forming body; a step of increasing the melting point of the first gold-tin forming body by diffusing gold from the seed layer into the first gold-tin forming body during the reflow step of the first gold-tin forming body; and a step of reflowing a second gold-tin forming body onto a second surface of a base structure after the reflow step of the first gold-tin forming body to bond a second thin film nitinol structure to the second surface of the base structure; wherein, when the second gold-tin forming body is reflowed, the second gold-tin forming body is not melted because the second gold-tin forming body has a melting point lower than the melting point of the first gold-tin forming body. Claim 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 intermediate layer of eutectic gold-tin configured to bond the first substrate and the second substrate. Claim 24 An implantable sensor device according to claim 23, further comprising an anchoring structure for fixing the sensor device to a blood vessel. Claim 25 In paragraph 24, an implantable sensor device wherein the anchoring structure is shaped to be anchored within a pulmonary artery. Claim 26 As an implantable sensor device: an inorganic nonmetallic casing; a vapor-deposited thin film nitinol diaphragm layer, wherein: A deflection portion configured to be deflected in response to changes in pressure conditions outside the implantable sensor device; and An implantable sensor device comprising: a thin film nitinol diaphragm layer including a non-biased peripheral portion; a eutectic gold-tin (AuSn) layer bonding the inorganic nonmetal casing to the peripheral portion of the thin film nitinol diaphragm layer, wherein the eutectic AuSn layer has a melting point below the transition temperature of the thin film nitinol diaphragm layer; and a capacitive sensor element disposed within a chamber that is at least partially hermetically sealed by the layer of eutectic AuSn and surrounded on at least one face by the biased portion of the thin film nitinol diaphragm layer. Claim 27 An implantable sensor device according to claim 26, further comprising: a first seed layer comprising titanium directly applied to a peripheral portion of a thin film nitinol diaphragm layer; a first gold layer disposed between the first seed layer and a eutectic AuSn layer; a second seed layer comprising titanium directly applied to an inorganic nonmetallic casing; and a second gold layer disposed between the second seed layer and the eutectic AuSn layer. Claim 28 An implantable sensor device according to claim 26: a first seed layer comprising titanium directly applied to a peripheral portion of a thin film nitinol diaphragm layer, wherein a layer of eutectic AuSn is directly disposed on the first seed layer; a second seed layer comprising titanium directly applied to an inorganic nonmetallic casing; and further comprising a gold layer disposed between the second seed layer and the eutectic AuSn layer. Claim 29 An implantable sensor device according to any one of claims 26 to 28, further comprising a gold hard-stop forming laterally disposed on the outer side of at least one portion of the eutectic AuSn layer. Claim 30 An implantable sensor device according to any one of claims 26 to 28, wherein the chamber is filled with an incompressible fluid configured to transmit pressure on a deflection portion of a thin film nitinol diaphragm layer to a capacitive sensor element.

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