Patent Description:
Implantable medical devices (IMDs) may be configured to sense physiological parameters and/or provide therapy and may include one or more electrodes for performing aspects of these functions. IMDs may also include antennas for communicating with other devices. Conventionally, devices such as programmers and wands have been used to cause IMDs to take various actions such as for example, marking recordings of physiological parameters, initiating communications with other devices, and the like. <CIT> discusses an active implantable medical device with RF telemetry comprising subcutaneous ECG electrodes. The case of the device comprises electrodes for collecting subcutaneous ECG signals coming into contact with the patient's tissues surrounding the case after implantation, as well as an RF telemetry antenna. These ECG electrodes are surface electrodes and the RF antenna is a surface antenna. The case presents a significantly planar face for mounting the ECG electrodes in an arrangement where these electrodes are significantly coplanar and spaced apart with each other, and receiving the surface RF antenna. A platelet mounted onto the case comprises an insulating substrate comprising on its free face, conductive deposits forming the ECG electrodes and the RF antenna. <CIT> discusses an implantable medical device including a liquid crystal polymer outer housing defining an outer surface of the IMD, circuitry disposed within the LCP outer housing, an electrical feedthrough extending through the LCP outer housing from a first end proximate the circuitry to a second end proximate to the outer surface, and an electrode structure disposed on the outer surface. The electrode structure may include a LCP substrate defining a first major surface and a second major surface substantially opposite the first major surface, a contact pad disposed on the first major surface, and an electrode disposed on the second major surface. The LCP substrate may be attached to the LCP outer housing and the contact pad may be electrically coupled to the electrical feedthrough.

Exemplary embodiments of the present disclosure include, but are not limited to, the following examples.

In an Example, a method for forming an electrode on an implantable medical device (IMD), comprises: forming a nonconductive body comprising a well having a bottom surface and at least one side surface extending from the bottom surface; forming a conduit through the bottom surface; inserting the nonconductive body into an opening in an external surface of the IMD; depositing conductive material into the well; and coupling the conductive material to a circuit of the IMD via the conduit through the bottom surface of the well.

Optionally, coupling the conductive material to the circuit of the IMD comprises brazing a wire that couples the conductive material to the circuit.

Optionally the at least one side extends perpendicular from the bottom surface.

Optionally, the method further comprises surface-grinding a top of the nonconductive body, the conductive material, or the nonconductive body and the conductive material to remove excess of the nonconductive body, the conductive material, or the nonconductive body and the conductive material.

Optionally, the method further comprises laser etching a top of the nonconductive body, the conductive material, or the nonconductive body and the conductive material to remove excess of the nonconductive body, the conductive material, or the nonconductive body and the conductive material.

Optionally, the method further comprises applying a mask to the conductive material to remove any excess of the conductive material.

Optionally depositing conductive material into the well comprises using photolithography and/or vapor deposition techniques.

Optionally the conductive material is titanium nitride (TiN).

Optionally the nonconductive body is made of ceramic, glass, or sapphire.

Optionally, the well is approximately <NUM> to <NUM> millimeters deep.

Optionally, an outer diameter of the nonconductive body is between approximately <NUM> to <NUM> times larger a diameter of the bottom surface.

In another Example, an implantable medical device (IMD), comprising: a housing enclosing a power supply, a processing device, and memory; a nonconductive body arranged in an opening of the housing, the nonconductive body comprising a well having a bottom surface and at least one side surface extending from the bottom surface; a conductive material deposited into the well, wherein the conductive material is electrically coupled to the processing device.

Optionally, in the IMD, a top surface of the conductive material is flush with a top surface of the housing, wherein a top surface of the conductive material is flush with a top surface of the nonconductive body, or wherein a top surface of the conductive material is flush with the top surface of the housing and the top surface of the nonconductive body.

Optionally, in the IMD, the at least one side extends perpendicular from the bottom surface.

Optionally, in the IMD, the nonconductive body is made of ceramic, glass, or sapphire.

In another Example, a method for forming an electrode on an implantable medical device (IMD), comprising: forming a nonconductive body comprising a well having a bottom surface and at least one side surface extending from the bottom surface; forming a conduit through the bottom surface; inserting the nonconductive body into an opening in an external surface of the IMD; depositing conductive material into the well; and coupling the conductive material to a circuit of the IMD via the conduit through the bottom surface of the well.

Optionally, the at least one side extends perpendicular from the bottom surface.

Optionally, the method further comprises laser cleaning a top of the nonconductive body, the conductive material, or the nonconductive body and the conductive material to remove excess of the nonconductive body, the conductive material, or the nonconductive body and the conductive material.

Optionally, depositing conductive material into the well comprises using photolithography and/or vapor deposition techniques.

Optionally, the conductive material is titanium nitride (TiN).

Optionally, the nonconductive body is made of ceramic, glass, or sapphire.

Optionally, the well is approximately <NUM> to <NUM> millimeters deep.

Optionally, in the IMD, the conductive material is titanium nitride (TiN). In another Example, a method for forming an antenna on an implantable medical device (IMD), comprising: forming an elongated nonconductive body; forming a conduit through the nonconductive body; inserting the nonconductive body into an opening in an external surface of the IMD; depositing a conductive material onto the nonconductive body, wherein the conductive material is deposited in a non-linear path; and coupling the conductive material to a circuit of the IMD via the conduit through the nonconductive body.

Optionally, the method further comprises surface-grinding or laser etching a top of the nonconductive body, the conductive material, or the nonconductive body and the conductive material to remove excess of the nonconductive body, the conductive material, or the nonconductive body and the conductive material.

While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the subject matter disclosed herein.

While the subject matter disclosed herein is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the subject matter disclosed herein as defined by the appended claims.

Although the term "block" may be used herein to connote different elements illustratively employed, the term should not be interpreted as implying any requirement of, or particular order among or between, various steps disclosed herein unless and except when explicitly referring to the order of individual steps.

Implantable medical device (IMD) may be used to sense one or more physiological measurements of a subject. To do so, IMDs often include one or more electrodes, which is attached to an outer surface of the IMDs. The embodiments disclosed herein provide a more efficient and cost-effective way to incorporate electrodes into an IMD.

<FIG> is a schematic illustration of a system <NUM> including an IMD <NUM> implanted within a patient's body <NUM> and configured to communicate with a receiving device <NUM>. In embodiments, the IMD <NUM> may be implanted subcutaneously within an implantation location or pocket in the patient's chest or abdomen and may be configured to monitor (e.g., sense and/or record) physiological parameters associated with the patient's heart <NUM>. In embodiments, the IMD <NUM> may be an implantable cardiac monitor (ICM) (e.g., an implantable diagnostic monitor (IDM), an implantable loop recorder (ILR), etc.) configured to record physiological parameters such as, for example, one or more cardiac activation signals, heart sounds, blood pressure measurements, oxygen saturations, and/or the like.

In certain instances, the IMD <NUM> may be configured to monitor physiological parameters that may include one or more signals indicative of a patient's physical activity level and/or metabolic level, such as an acceleration signal. In certain instances, the IMD <NUM> may be configured to monitor physiological parameters associated with one or more other organs, systems, and/or the like. The IMD <NUM> may be configured to sense and/or record at regular intervals, continuously, and/or in response to a detected event. In certain instances, such a detected event may be detected by one or more sensors of the IMD <NUM>, another IMD (not shown), an external device (e.g., the receiving device <NUM>), and/or the like.

In addition, the IMD <NUM> may be configured to detect a variety of physiological signals that may be used in connection with various diagnostic, therapeutic, and/or monitoring implementations. For example, the IMD <NUM> may include sensors or circuitry for detecting respiratory system signals, cardiac system signals, and/or signals related to patient activity. In certain instances, the IMD <NUM> may be configured to sense intrathoracic impedance, from which various respiratory parameters may be derived, including, for example, respiratory tidal volume and minute ventilation. Sensors and associated circuitry may be incorporated in connection with the IMD <NUM> for detecting one or more body movement or body posture and/or position related signals. For example, accelerometers and/or GPS devices may be employed to detect patient activity, patient location, body orientation, and/or torso position.

For purposes of illustration, and not of limitation, various embodiments of devices that may be used to record physiological parameters in accordance with the present disclosure are described herein in the context of IMDs that may be implanted under the skin in the chest region of a patient.

As shown, the IMD <NUM> may include a housing <NUM> having two electrodes <NUM> and <NUM> coupled thereto. According to certain instances, the IMD <NUM> may include any number of electrodes (and/or other types of sensors such as, e.g., thermometers, barometers, pressure sensors, optical sensors, motion sensors, and/or the like) in any number of various types of configurations, and the housing <NUM> may include any number of different shapes, sizes, and/or features. In certain instances, the IMD <NUM> may be configured to sense physiological parameters using, e.g., the electrodes <NUM>, <NUM>, and record the physiological parameters. For example, the IMD <NUM> may be configured to activate (e.g., periodically, continuously, upon detection of an event, and/or the like), record a specified amount of data (e.g., physiological parameters) in a memory, and communicate that recorded data to a receiving device <NUM>. In the case of an IDM, for example, the IMD <NUM> may activate, record cardiac signals for a certain period of time, deactivate, and activate to communicate the recorded signals to the receiving device <NUM>.

In various instances, the receiving device <NUM> may be, for example, a programmer, controller, patient monitoring system, and/or the like. Although illustrated in <FIG> as an external device, the receiving device <NUM> may include an implantable device configured to communicate with the IMD <NUM> that may, for example, be a control device, another monitoring device, a pacemaker, an implantable defibrillator, a cardiac resynchronization therapy (CRT) device, and/or the like, and may be an implantable medical device known in the art or later developed, for providing therapy and/or diagnostic data about the patient and/or the IMD <NUM>. In certain instances, the IMD <NUM> may be a pacemaker, an implantable cardioverter defibrillator (ICD) device, or a cardiac resynchronization therapy (CRT) device. In certain instances, the IMD <NUM> may include both defibrillation and pacing/CRT capabilities (e.g., a CRT-D device).

The system <NUM> may be used to implement coordinated patient measuring and/or monitoring, diagnosis, and/or therapy in accordance with embodiments of the disclosure. The system <NUM> may include, for example, one or more patient-internal medical devices, such as an IMD <NUM>, and one or more patient-external medical devices, such as receiving device <NUM>. The receiving device <NUM> may be configured to perform monitoring, and/or diagnosis and/or therapy functions external to the patient (i.e., not invasively implanted within the patient's body). The receiving device <NUM> may be positioned on the patient, near the patient, or in any location external to the patient.

The IMD <NUM> and the receiving device <NUM> may communicate through a wireless link. For example, the IMD <NUM> and the receiving device <NUM> may be coupled through a short-range radio link, such as Bluetooth, IEEE <NUM>, and/or a proprietary wireless protocol. The communications link may facilitate uni-directional and/or bidirectional communication between the IMD <NUM> and the receiving device <NUM>. Data and/or control signals may be transmitted between the IMD <NUM> and the receiving device <NUM> to coordinate the functions of the IMD <NUM> and/or the receiving device <NUM>. Patient data may be downloaded from one or more of the IMD <NUM> and the receiving device <NUM> periodically or on command. The physician and/or the patient may communicate with the IMD <NUM> and the receiving device <NUM>, for example, to acquire patient data or to initiate, terminate, or modify recording and/or therapy.

The illustrative system <NUM> shown in <FIG> is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the subject matter disclosed throughout this disclosure. Neither should the illustrative system <NUM> be interpreted as having any dependency or requirement related to any single component or combination of components illustrated in <FIG>. For example, in embodiments, the illustrative system <NUM> may include additional components. Additionally, any one or more of the components depicted in <FIG> can be, in embodiments, integrated with various ones of the other components depicted therein (and/or components not illustrated). Any number of other components or combinations of components can be integrated with the illustrative system <NUM> depicted in <FIG>, all of which are considered to be within the ambit of this disclosure.

<FIG> is a perspective view of the IMD <NUM> according to an embodiment as disclosed herein. The IMD <NUM> has the first electrode <NUM> and the second electrode <NUM> as well as an antenna <NUM> embedded in the housing <NUM>. Each of the first electrode <NUM>, the second electrode <NUM>, and the antenna <NUM> includes a conductive portion <NUM> that is surrounded by a larger nonconductive portion <NUM> to prevent the conductive portion <NUM> from coming into contact with an outer surface <NUM> of the housing <NUM>, which may be conductive.

In some examples, the electrodes <NUM> and <NUM> and the antenna <NUM> are all located on the same side of the outer surface <NUM>, such as on a frontward facing portion <NUM> or a rearward facing portion <NUM> of the outer surface <NUM>. The IMD <NUM> has a longitudinal axis <NUM> along which the components of the IMD <NUM> are positioned. The antenna <NUM> may be configured for wirelessly communicating data with the receiving device <NUM>. The housing <NUM> is made of any suitable material such as metal, for example titanium, whereas the nonconductive portions <NUM> are made of any suitable material with nonconductive or insulating properties such as ceramic substrate, glass, or sapphire, etc. The nonconductive portions <NUM> may be transparent, translucent, or opaque according to the material used.

<FIG> shows an example of the components in IMD <NUM> according to some embodiments. The housing <NUM> contains a battery <NUM>, a charging coil <NUM> for wireless charging of the battery <NUM> using an external charging device <NUM>, assuming that battery <NUM> is a rechargeable battery. If the battery <NUM> is not rechargeable, the charging coil <NUM> and the external charger <NUM> can be eliminated. The IMD <NUM> also includes control circuitry such as a microcontroller <NUM>, and/or one or more Application Specific Integrated Circuit (ASICs) <NUM>, as suitable. ASIC(s) <NUM> can include current generation circuitry for providing stimulation pulses at one or more of the electrodes <NUM> and <NUM> and may also include telemetry modulation and demodulation circuitry for enabling bidirectional wireless communications at the antenna <NUM>, battery charging and protection circuitry couplable to charging coil <NUM>, DC-blocking capacitors in each of the current paths proceeding to the electrodes <NUM> and <NUM>, etc..

Components within the housing <NUM> are integrated via a printed circuit board (PCB) <NUM> which includes electrical traces (not shown) printed on one or more of surfaces <NUM> and <NUM> of the PCB <NUM> to electrically couple the individual components to each other, as suitable. For example, the traces may be used to electrically couple the control circuitry (e.g., microcontroller <NUM> and ASICs <NUM>) with the electrodes <NUM>,<NUM> and the antenna <NUM>. The traces are made of any suitable conductive material, such as gold, silver, or platinum alloys, for example.

<FIG> further shows the external components (for example, the receiving device <NUM> referenced above, which may be used to communicate with the IMD <NUM>. The receiving device <NUM> may include an external charger <NUM> and an external controller <NUM>. The external controller <NUM> may be used to control and monitor the IMD <NUM> via a bidirectional wireless communication link <NUM> passing through a patient's tissue. For example, the external controller <NUM> may be used to monitor the measurements taken by the electrodes <NUM> and <NUM>.

Communication on the wireless communication link <NUM> can occur via magnetic inductive coupling between an antenna (not shown) in the external controller <NUM> and the antenna <NUM> in the IMD <NUM>. The magnetic field comprising the link <NUM> may be modulated via Frequency Shift Keying (FSK) or the like, to encode transmitted data. Other methods including but not limited to short-range RF telemetry (e.g., Bluetooth, WiFi, Zigbee, MICS, etc.) may also be employed.

The external charger <NUM> provides power to recharge the battery <NUM> should the battery <NUM> be rechargeable. Such power transfer may occur by energizing a charging coil (not shown) in the external charger <NUM>, which produces a magnetic field <NUM> which then energizes the charging coil <NUM> in the IMD <NUM>, which is rectified, filtered, and used to recharge the battery <NUM>.

Furthermore, the antenna <NUM> may be positioned to face the tissue, or positioned to be at the location closest to the skin side or the exterior side of the patient's body, in order to minimize or avoid RF interference by having less body tissue to transmit wireless data therethrough. In addition, the integrated circuitry in some examples includes a Kelvin connection to the first electrode <NUM> and the second electrode <NUM>. In certain instances, the IMD <NUM> may include an accelerometer to determine whether or not the IMD <NUM> has turned or flipped. The accelerometer may determine periods of electrode inactivity to determine a stable signal and select between the first electrode <NUM> and the second electrode <NUM>.

In some examples, the housing <NUM> may be formed by having two separate housing portions (for example, one defining the frontward facing portion <NUM> and the other defining the rearward facing portion <NUM>) combined or conjoined together into one component. In some examples, the combined portions may be laser-welded or ultrasonically welded together to form the housing <NUM>. In some examples, the combined portions may be brazed together using any suitable metal such as gold alloys to form the housing <NUM>. In some examples, the combined portions may be attached together using a suitable adhesive to form the housing <NUM>. In some examples, the combined portions may be shrink-wrapped to form the housing <NUM> using any suitable polymer, including but not limited to PVC, polyolefin, polyethylene, and polypropylene. In some examples, the housing <NUM> is sealed to ensure hermiticity using any one or more of the methods outlined above.

The functionality of the first electrode <NUM> and the second electrode <NUM> may be controlled by the integrated circuitry (e.g., microcontroller <NUM> and/or ASICs <NUM>). For example, the integrated circuitry may be configured to select between the first electrode <NUM> and the second electrode <NUM>. In addition, the integrated circuitry may be configured to measure sensing capability of the first electrode <NUM> and sensing capability of the second electrode <NUM>. In certain instances, the integrated circuitry may be configured to select between the first electrode <NUM> and the second electrode <NUM> in response to determining which of the first electrode <NUM> and the second electrode <NUM> has a greater of the sensing capability. The integrated circuitry may be configured to measure impedance on a sensed signal of the first electrode <NUM> and an impedance on a sensed signal of the second electrode <NUM> to determine the sensing capability of the first electrode <NUM> and the sensing capability of the second electrode <NUM>. The integrated circuitry being configured to select between the first electrode <NUM> and the second electrode <NUM> may increase sensing capabilities and signal capture by selecting whichever of the first electrode <NUM> and the second electrode <NUM> has the stronger signal for sensing.

<FIG> shows an example of a nonconductive body <NUM> used as the nonconductive portion <NUM> to contain the electrode <NUM>,<NUM> or the antenna <NUM> while insulating these components from the housing <NUM> of the IMD <NUM>, according to some embodiments. Specifically, the nonconductive body <NUM> has an outer portion defined by a top surface <NUM> and a side surface <NUM>. The nonconductive body <NUM> also includes a well <NUM> that defines a recess relative to the top surface <NUM>. In some examples, the well <NUM> is approximately <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM> lower than the top surface <NUM>. The well <NUM> may further include a conduit <NUM> which is defined as an opening, hole, or aperture that extends through the nonconductive body <NUM>.

Although the nonconductive body <NUM> is shown as circular in shape when seen from above, it is to be understood that the nonconductive body <NUM> may be formed in any shape or configuration. For example, the nonconductive body <NUM> may be formed as an elongated ovular shape according to the nonconductive portion <NUM> surrounding the antenna <NUM>, as shown in <FIG>. When the nonconductive body <NUM> is an elongated ovular shape, it may or may not include a well that defines a recess relative to the top surface <NUM>. In some examples, an outer diameter <NUM> of the nonconductive body <NUM> (also referred to as a diameter of the nonconductive portion <NUM>) may be between approximately <NUM> to <NUM> times, <NUM> to <NUM> times, <NUM> to <NUM> times, <NUM> to <NUM> times, or <NUM> to <NUM> times greater than an outer diameter <NUM> of the well <NUM> (also referred to as a diameter of the conductive portion <NUM>), for example.

The nonconductive body <NUM> with the well <NUM> may be prepared using any insulating material including but not limited to ceramic, glass, or sapphire. The conduit <NUM> may then brazed with a conductive material such as copper and zinc alloy. In some examples, the housing <NUM> has an opening into which the nonconductive body <NUM> may be positioned prior to or after brazing. In embodiments, one end of the wire is brazed to the conduit <NUM> and the other end of the wire may be connected to the PCB <NUM>. Alternatively, in some examples, the nonconductive body <NUM> may be brazed directly to the surface <NUM> of the PCB <NUM>, where the electrical traces may be printed on the surface <NUM>, instead of to the wire. After brazing, a conductive material to form the conductive portion <NUM> of the electrode, for example titanium nitride (TiN), may be deposited or sputtered into the conduit <NUM> and the well <NUM> until a top portion <NUM> of the conductive material is level with or protrudes past the top surface <NUM> of the nonconductive body <NUM> as shown in <FIG>.

In embodiments, the extraneous portion that extends past the top surface <NUM> (including the top portion <NUM>) may be smoothened using methods such as laser etching or surface grinding such that the surface of the conductive portion <NUM> is essentially flush with the top surface <NUM> of the nonconductive body <NUM> as shown in <FIG>. The term "essentially flush" may indicate that the difference between the two neighboring surfaces is small enough to be essentially undetectable by the naked eye, or if the difference is minuscule so as to not have any effect during the use of the device. In some examples, the difference may be less than approximately <NUM> or <NUM>. In some examples, this difference may be less than approximately <NUM> or even less than <NUM>.

In some examples, the surface grinding may be achieved via back grinding using suitable back-grinding tapes. In some examples, masking processes may be employed in addition, or alternative, the back-grinding method. Alternatively, other methods of depositing the conductive material into the conduit <NUM> and the well <NUM> may be employed. In some examples, semiconductor photolithography may be used, which can pattern or define the electrode or conductive region <NUM> with more precision than some of other methods. If ceramic is used for the nonconductive body <NUM>, the resulting electrode <NUM>,<NUM> formed using the nonconductive body <NUM> in <FIG> retains physical properties similar to a cermet, for example having high temperature resistance and hardness as well as the ability to undergo plastic deformation without rupturing or fracturing.

Additionally, or alternatively, the antenna <NUM> and/or the nonconductive body <NUM> may be made to be essentially flush with the outer surface <NUM> (i.e., the frontward facing portion <NUM> or the rearward facing portion <NUM>) of the IMD <NUM>, which allows for a smaller profile for the IMD <NUM> as compared to having the metal components directly attached to the outer surface <NUM> of the IMD <NUM>.

The illustrative components shown in the figures are not intended to suggest any limitation as to the scope of use or functionality of embodiments of the disclosed subject matter. Neither should the illustrative components be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. Additionally, any one or more of the components depicted in the figures may be, in embodiments, integrated with various other components depicted therein (and/or components not illustrated), all of which are considered to be within the ambit of the disclosed subject matter.

Claim 1:
A method for forming an electrode on an implantable medical device, IMD (<NUM>), wherein the IMD comprises a housing (<NUM>) enclosing a power supply, a control circuitry, and memory, the method comprising:
forming a nonconductive body (<NUM>) comprising a well (<NUM>) having a bottom surface and at least one side surface extending from the bottom surface;
forming a conduit (<NUM>) through the bottom surface;
inserting the nonconductive body (<NUM>) into an opening in an external surface of the IMD (<NUM>);
depositing conductive material into the well (<NUM>); and
coupling the conductive material to the control circuitry of the IMD via the conduit (<NUM>) through the bottom surface of the well (<NUM>).