Patent Description:
The present disclosure relates to systems, methods, and devices for tracking items. More specifically, the disclosure relates to systems, methods, and devices for electromagnetically tracking medical devices used in medical procedures.

A variety of systems, methods, and devices can be used to track medical devices. Tracking systems can use generated magnetic fields that are sensed by at least one tracking sensor in the tracked medical device. The generated magnetic fields provide a fixed frame of reference, and the tracking sensor senses the magnetic fields to determine the location and orientation of the sensor in relation to the fixed frame of reference.

Document <CIT> describes a system and a method for providing a position and orientation sensor package having a reduced size in at least one dimension. The position and orientation sensor package includes a dielectric substrate and a first magneto-resistance sensor chip attached to the dielectric substrate, the first magneto-resistance sensor chip including at least one magneto-resistance sensor circuit. The position and orientation sensor package also includes a second magneto-resistance sensor chip attached to the dielectric substrate and positioned adjacent the first magneto-resistance sensor chip, the second magneto-resistance sensor chip including at least one magneto-resistance sensor circuit. The position and orientation sensor package is constructed such that the at least one magneto-resistance sensor circuit of the first magneto-resistance sensor chip is oriented in a different direction than the at least one magneto-resistance sensor circuit of the second magneto-resistance sensor chip.

Optional features are provided in the dependent claims. Examples and embodiments not falling under the scope of the claims are provided for illustrative purposes. A sensor assembly in accordance with the invention includes a multilayer circuit, a first magnetic field sensor, and a second magnetic field sensor. The multilayer circuit extends between a proximal end and a distal end along a longitudinal axis. The multilayer circuit includes a plurality of electrical pads positioned at the proximal end. The first magnetic field sensor is coupled to the multilayer circuit and has a primary sensing direction aligned with the longitudinal axis. The second magnetic field sensor is coupled to the multilayer circuit and oriented with respect to the first magnetic field sensor such that the second magnetic field sensor has a primary sensing direction aligned with an axis orthogonal to the longitudinal axis.

The multilayer circuit includes a flexible substrate layer, wherein a first subset of the plurality of electrical pads is positioned on a first side of the flexible substrate layer, and wherein a second subset of the plurality of electrical pads is positioned on a second side of the flexible substrate layer opposite the first side.

In an example, a proximal section of the multilayer circuit is folded such that at least one of the plurality of electrical pads is positioned on a different plane than the other plurality of electrical pads.

In an example, a proximal section of the multilayer circuit is substantially c-shaped.

In an example, the proximal section includes a fold portion only partially covered by a mask layer such that a portion of the flexible substrate layer is exposed.

In an example, the multilayer circuit includes six to nine electrical pads at the proximal end.

In an example, the sensor assembly further comprises a plurality of electrical leads, each electrically coupled to one of the plurality of electrical pads.

In an example, the sensor assembly further comprises a housing surrounding the multilayer circuit, the first magnetic sensor, and the second magnetic sensor.

In an example, the housing includes four quadrants of substantially equal size, wherein at least one electrical lead is positioned within each of the four quadrants.

In an example, the housing is cylinder, polygon, or rectangular shaped.

In an example, the housing has a cross-section area of. <NUM><NUM>.

In an example, the housing comprises epoxy.

In an example, the housing includes an outer shell.

In an example, the first magnetic field sensor and the second magnetic field sensors include one of inductive sensing coils, magneto-resistive sensing elements, giant magneto-impedance sensing elements, and flux-gate sensing elements.

In an example, the first magnetic field sensor or the second magnetic field sensor is a multi-axis sensor and includes a second primary sensing direction.

In an example, a system includes a sensor assembly having a multilayer circuit, a first magnetic field sensor, and a second magnetic field sensor. The multilayer circuit includes a proximal section, a distal section, and a longitudinal axis. The proximal section includes a plurality of electrical pads and is at least partially folded. The first magnetic field sensor is coupled to the multilayer circuit at the distal section and has a primary sensing direction aligned with the longitudinal axis. The second magnetic field sensor is coupled to the multilayer circuit at the distal section and oriented with respect to the first magnetic field sensor such that the second magnetic field sensor has a primary sensing direction aligned with an axis orthogonal to the longitudinal axis.

In an example, the multilayer circuit includes a flexible substrate layer, wherein a first subset of the plurality of electrical pads is positioned on a first side of the flexible substrate layer, and wherein a second subset of the plurality of electrical pads is positioned on a second side of the flexible substrate layer opposite the first side.

In an example, the proximal section of the multilayer circuit is substantially c-shaped.

In an example, the proximal section of the multilayer circuit includes a flexible substrate only partially covered by a mask layer such that a portion of the flexible substrate layer is exposed.

In an example, the multilayer circuit includes six to nine electrical pads at the proximal section.

In an example, the system further comprises a plurality of electrical leads, each electrically coupled to one of the plurality of electrical pads.

In an example, the system further comprises a housing surrounding the multilayer circuit, the first magnetic sensor, and the second magnetic sensor.

In an example, the housing comprises an outer shell and is at least partially filled with epoxy.

In an example, the system comprises a third magnetic field sensor coupled to the multilayer circuit at the distal section and oriented with respect to the first magnetic field sensor such that the third magnetic field sensor has a primary sensing direction orthogonal to the longitudinal axis.

In an example, the proximal section includes a first leg portion, a second leg portion, and a bend portion positioned between the first leg portion and the second leg portion.

In an example, a first subset of the plurality of electrical pads is positioned on the first leg portion, and wherein a second subset of the plurality of electrical pads is positioned on the second leg portion.

In an example, the system further comprises a medical device, wherein the sensor assembly is positioned within the medical device.

In an example, a method is disclosed for forming a multilayer circuit having a proximal section, a distal section, a first set of a plurality of electrical pads positioned at the proximal section, and a second set of a plurality of electrical pads positioned at the distal section. The method includes electrically coupling a plurality of magnetic field sensors to the second set of the plurality of electrical pads, electrically coupling a plurality of electrical leads each to one of the first set of the plurality of electrical pads while such electrical pads are positioned within substantially the same plane, and folding the proximal section such that the proximal section includes a bend portion having a substantially constant bending radius such that the first set of the plurality of electrical pads are no longer positioned within substantially the same plane.

In an example, the method further comprises after the folding step, positioning the multilayer circuit into a housing.

In an example, the method further comprises after the folding step, encapsulating at least a portion of the multilayer circuit in epoxy.

In an example, a medical device comprises the sensor assembly in accordance with the invention.

In an example, the medical device is a catheter.

In an example, the sensor assembly is positioned within the catheter.

In an example, the sensor assembly is positioned at or near a distal end of the catheter.

While the invention 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 invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

During medical procedures, medical devices such as probes (e.g., catheters, guidewires, scopes) are inserted into a patient. To track the location and orientation of a probe within the patient, probes can be provisioned with magnetic field sensors that detect various magnetic fields generated by transmitters near the patient.

<FIG> is a schematic block diagram depicting a tracking system <NUM> that is configured to determine location information corresponding to the medical device <NUM> based on information collected using a receiver (e.g., sensor) <NUM> associated with a medical device <NUM>. The information collected by the receiver <NUM> includes a received field signal corresponding to an electromagnetic field defined by a set of electromagnetic signals transmitted by one or more magnetic field transmitter assemblies <NUM>, <NUM>, and <NUM>. According to embodiments, one or more magnetic field transmitter assemblies <NUM>, <NUM>, and <NUM>, are configured to transmit (e.g., radiate) electromagnetic signals, which produce a magnetic field within which a subject <NUM> is disposed. According to embodiments, the system <NUM> includes a magnetic field controller <NUM> configured to manage operation of the magnetic field transmitter assemblies <NUM>, <NUM>, and <NUM>.

The receiver <NUM> (e.g., magnetic field sensor) (which may include one or more receivers/sensors) may be configured to produce an electrical response to the magnetic field(s) generated by the magnetic field transmitter assemblies <NUM>, <NUM>, and <NUM>. For example, the receiver <NUM> may include one or more magnetic field sensors such as inductive sensing coils and/or various sensing elements such as magneto-resistive (MR) sensing elements (e.g., anisotropic magneto-resistive (AMR) sensing elements, giant magneto-resistive (GMR) sensing elements, tunneling magneto-resistive (TMR) sensing elements, Hall effect sensing elements, colossal magneto-resistive (CMR) sensing elements, extraordinary magneto-resistive (EMR) sensing elements, spin Hall sensing elements, and the like), giant magneto-impedance (GMI) sensing elements, and/or flux-gate sensing elements. The receiver <NUM> is configured to sense the generated magnetic fields and provide tracking signals indicating the location and orientation of the receiver <NUM> in up to six degrees of freedom (i.e., x, y, and z measurements, and pitch, yaw, and roll angles). Generally, the number of degrees of freedom that a tracking system is able to track depends on the number of magnetic field sensors and magnetic field generators. For example, a tracking system with a single magnetic field sensor may not be capable of tracking roll angles and thus are limited to tracking in only five degrees of freedom (i.e., x, y, and z coordinates, and pitch and yaw angles). This is because a magnetic field sensed by a single magnetic field sensor does not change as the single magnetic field sensor is "rolled. " The magnetic field sensors can be powered by voltages or currents to drive or excite elements of the magnetic field sensors. The magnetic field sensor elements receive the voltage or current and, in response to one or more of the generated magnetic fields, the magnetic field sensor elements generate sensing signals, which are transmitted to the magnetic field controller <NUM>.

As shown in <FIG>, the magnetic field controller <NUM> includes a signal generator <NUM> configured to provide driving current to each of the magnetic field transmitter assemblies <NUM>, <NUM>, and <NUM>, causing each magnetic field transmitter assembly to transmit an electromagnetic signal. In certain embodiments, the signal generator <NUM> is configured to provide variable (e.g., sinusoidal) driving currents to the magnetic field transmitter assemblies <NUM>, <NUM>, and <NUM>. The magnetic field controller <NUM> can be implemented using firmware, integrated circuits, and/or software modules that interact with each other or are combined together. For example, the magnetic field controller <NUM> may include computer-readable instructions/code for execution by a processor (see <FIG>). Such instructions may be stored on a non-transitory computer-readable medium (see <FIG>) and transferred to the processor for execution. In some embodiments, the magnetic field controller <NUM> can be implemented in one or more application-specific integrated circuits and/or other forms of circuitry suitable for controlling and processing magnetic tracking signals and information.

The sensed magnetic field signal may include multiple magnetic field signals, each of which may be processed to extract field components corresponding to one or more magnetic field transmitter assemblies. The sensed magnetic field signal is communicated to a signal processor <NUM>, which is configured to analyze the sensed magnetic field signal to determine location information corresponding to the receiver <NUM> (and, thus, the medical device <NUM>). Location information may include any type of information associated with a location and/or position of a medical device <NUM> such as, for example, location, relative location (e.g., location relative to another device and/or location), position, orientation, velocity, acceleration, and/or the like. As mentioned above, rotating magnetic field-based tracking can utilize phase (e.g., differences in phase) of the sensed magnetic field signal to determine location and orientation of the probe.

The tracking system <NUM> can also include at least one sensor that is configured and arranged to sense the magnetic fields generated by the magnetic field transmitter assemblies, <NUM>-<NUM>. The sensor can be a magnetic sensor (e.g., dual-axis magnetic sensor, tri-axis magnetic sensor) and be positioned at a known reference point in proximity to the magnetic field transmitter assemblies, <NUM>-<NUM>, to act as a reference sensor. For example, one or more sensors can be coupled to the subject's bed, the subject herself, an arm of an x-ray machine, or at other points a known distance from the magnetic field transmitter assemblies, <NUM>-<NUM>. In some embodiments, the at least one sensor is mounted to one of the magnetic field transmitter assemblies, <NUM>-<NUM>.

The medical device <NUM> may include, for example, a catheter (e.g., a mapping catheter, an ablation catheter, a diagnostic catheter, an introducer), an endoscopic probe or cannula, an implantable medical device (e.g., a control device, a monitoring device, a pacemaker, an implantable cardioverter defibrillator (ICD), a cardiac resynchronization therapy (CRT) device, a CRT-D), guidewire, endoscope, biopsy needle, ultrasound device, reference patch, robot and/or the like. For example, in embodiments, the medical device <NUM> may include a mapping catheter associated with an anatomical mapping system. The medical device <NUM> may include any other type of device configured to be at least temporarily disposed within a subject <NUM>. The subject <NUM> may be a human, a dog, a pig, and/or any other animal having physiological parameters that can be recorded. For example, in embodiments, the subject <NUM> may be a human patient.

As shown in <FIG>, the medical device <NUM> may be configured to be disposed within the body of a subject <NUM>, and may be configured to be communicatively coupled to the signal processor <NUM> via a communication link <NUM> (shown in phantom). In embodiments, the communication link <NUM> may be, or include, a wired communication link (e.g., a serial communication), a wireless communication link such as, for example, a short-range radio link, such as Bluetooth, IEEE <NUM>, a proprietary wireless protocol, and/or the like. The term "communication link" may refer to an ability to communicate some type of information in at least one direction between at least two devices, and should not be understood to be limited to a direct, persistent, or otherwise limited communication channel. That is, in some embodiments, the communication link <NUM> may be a persistent communication link, an intermittent communication link, an ad-hoc communication link, and/or the like. The communication link <NUM> may refer to direct communications between the medical device <NUM> and the signal processor <NUM>, and/or indirect communications that travel between the medical device <NUM> and the signal processor <NUM> via at least one other device (e.g., a repeater, router, hub, and/or the like). The communication link <NUM> may facilitate uni-directional and/or bi-directional communication between the medical device <NUM> and the signal processor <NUM>. Data and/or control signals may be transmitted between the medical device <NUM> and the signal processor <NUM> to coordinate the functions of the medical device <NUM> and/or the signal processor <NUM>.

The signal processor <NUM> further includes a location unit <NUM> configured to determine, based on the sensed field signal (e.g., the phase, amplitude, differences in phase and/or amplitude of the sensed field signal), location information corresponding to the medical device <NUM>. The location unit <NUM> may be configured to determine location information according to any location-determination technique that uses magnetic navigation. According to various embodiments of the disclosed subject matter, any number of the components depicted in <FIG> (e.g., the field controller <NUM>, the signal generator <NUM>, the signal processor <NUM>) may be implemented on one or more computing devices, either as a single unit or a combination of multiple devices. The system <NUM> can include a display for visualizing the position and/or orientation of the medical device <NUM> in the subject <NUM>.

<FIG> is a schematic block diagram depicting an illustrative computing device <NUM>, in accordance with embodiments of the disclosure. The computing device <NUM> may include any type of computing device suitable for implementing aspects of embodiments of the disclosed subject matter. Examples of computing devices include specialized computing devices or general-purpose computing devices such "workstations," "servers," "laptops," "desktops," "tablet computers," "hand-held devices," "general-purpose graphics processing units (GPGPUs)," and the like, all of which are contemplated within the scope of <FIG> and <FIG>, with reference to various components of the tracking system <NUM> and/or computing device <NUM>.

In embodiments, the computing device <NUM> includes a bus <NUM> that, directly and/or indirectly, couples the following devices: a processor <NUM>, a memory <NUM>, an input/output (I/O) port <NUM>, an I/O component <NUM>, and a power supply <NUM>. Any number of additional components, different components, and/or combinations of components may also be included in the computing device <NUM>. The I/O component <NUM> may include a presentation component configured to present information to a user such as, for example, a display device, a speaker, a printing device, and/or the like, and/or an input component such as, for example, a microphone, a joystick, a satellite dish, a scanner, a printer, a wireless device, a keyboard, a pen, a voice input device, a touch input device, a touch-screen device, an interactive display device, a mouse, and/or the like.

The bus <NUM> represents what may be one or more busses (such as, for example, an address bus, data bus, or combination thereof). Similarly, in embodiments, the computing device <NUM> may include a number of processors <NUM>, a number of memory components <NUM>, a number of I/O ports <NUM>, a number of I/O components <NUM>, and/or a number of power supplies <NUM>. Additionally any number of these components, or combinations thereof, may be distributed and/or duplicated across a number of computing devices. As an example only, the processor <NUM> may include the signal processor <NUM>, but other suitable configurations are also contemplated to suit different applications.

In embodiments, the memory <NUM> includes computer-readable media in the form of volatile and/or nonvolatile memory and may be removable, nonremovable, or a combination thereof. Media examples include Random Access Memory (RAM); Read Only Memory (ROM); Electronically Erasable Programmable Read Only Memory (EEPROM); flash memory; optical or holographic media; magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices; data transmissions; and/or any other medium that can be used to store information and can be accessed by a computing device such as, for example, quantum state memory, and/or the like. In embodiments, the memory <NUM> stores computer-executable instructions <NUM> for causing the processor <NUM> to implement aspects of embodiments of system components discussed herein and/or to perform aspects of embodiments of methods and procedures discussed herein.

The computer-executable instructions <NUM> may include, for example, computer code, machine-useable instructions, and the like such as, for example, program components capable of being executed by one or more processors <NUM> associated with the computing device <NUM>. Program components may be programmed using any number of different programming environments, including various languages, development kits, frameworks, and/or the like. Some or all of the functionality contemplated herein may also, or alternatively, be implemented in hardware and/or firmware.

The illustrative computing device <NUM> shown in <FIG> is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the present disclosure. Neither should the illustrative computing device <NUM> be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. Additionally, various components depicted in <FIG> may be, in embodiments, integrated with various ones of the other components depicted therein (and/or components not illustrated), all of which are considered to be within the ambit of the present disclosure.

<FIG> show a sensor assembly <NUM> that can be used in a medical device (like the medical device <NUM> in <FIG>). For example, the sensor assembly <NUM> can be positioned within the medical device (e.g., at or near a distal end of the medical device). The sensor assembly <NUM> includes a multilayer circuit assembly <NUM> electrically coupled to electrical leads <NUM> and positioned within a housing <NUM>. <FIG> shows the multilayer circuit assembly <NUM> before a multilayer circuit <NUM> is formed into its final shape and before the multilayer circuit assembly <NUM> is incorporated into the sensor assembly <NUM>.

The multilayer circuit assembly <NUM> includes a multilayer circuit <NUM> extending between a proximal end 310A and a distal end 310B. The multilayer circuit <NUM> comprising a flexible substrate <NUM> (e.g., polyimide, polyester/PET, PEEK, parylene, LCP, PEN, PEI, FEP), a first mask layer 314A, a second mask layer 314B, electrical lead pads <NUM> (see <FIG>), electrical mounting pads <NUM> (see <FIG>), and electrical traces (not shown) that electrically couple certain electrical lead pads <NUM> to certain electrical mounting pads <NUM>. The first mask layer 314A and the second mask layer 314B are positioned on opposite sides of the flexible substrate <NUM>. In certain embodiments, the multilayer circuit <NUM> is <NUM>-<NUM> microns thick.

The multilayer circuit assembly <NUM> further includes first, second, and third magnetic field sensors, 320A, 320B, and 320C, and first, second, and third sensor circuits 322A, 322B, and 322C (e.g., application-specific integrated circuits (ASICs), circuits with diode(s) and capacitor(s)). As shown in <FIG>, the magnetic field sensors, 320A-320C, and the sensor circuits, 322A-322C, can be implemented on separate dies and positioned next to each other. In such embodiments, the magnetic field sensors, 320A-320C, and the sensor circuits, 322A-322C, can be electrically and communicatively coupled together. In certain embodiments, respective magnetic field sensors, 320A-320C, and the sensor circuits, 322A-322C, can be implemented on the same die or substrate (e.g., a monolithic design). For example, the magnetic field sensors, 320A-320C, can be fabricated on top of respective sensor circuits, 322A-322C.

The magnetic field sensors 320A, 320B, and 320C can include sensors such as inductive sensing coils and/or various sensing elements such as MR sensing elements (e.g., AMR sensing elements, GMR sensing elements, TMR sensing elements, Hall effect sensing elements, CMR sensing elements, EMR sensing elements, spin Hall sensing elements, and the like), GMI sensing elements, and/or flux-gate sensing elements. The MR sensing elements are configured to sense magnetic fields, like those generated by the magnetic field transmitter assemblies, <NUM>-<NUM> of <FIG>, and generate a responsive sensing signal. In addition, the multilayer circuit assembly <NUM> can feature other types of sensors, such as temperature sensors, ultrasound sensors, etc. Sensing signals generated by the magnetic field sensors 320A-320C can be transmitted from the sensor assembly <NUM> to a controller, such as the magnetic field controller <NUM> of <FIG>, wirelessly or via one or more conductors.

In certain embodiments, the magnetic field sensors 320A-320C are arranged in a dual-axis, six degree-of-freedom arrangement. In such embodiments, the first magnetic field sensor 320A and the second magnetic field sensor 320B are oriented such that their primary sensing direction is aligned along a longitudinal axis <NUM> (e.g., X-axis) of the sensor assembly <NUM>. The third magnetic field sensor 320C is oriented such that its primary sensing direction is aligned along an axis (e.g., Y-axis) orthogonal to the longitudinal axis <NUM>. In certain embodiments, the magnetic field sensors 320A-320C are arranged in a tri-axis, six degree-of-freedom arrangement. In such embodiments, the magnetic field sensors' primary sensing directions are orthogonal to each other. Although the first, second, and third magnetic field sensors, 320A, 320B, and 320C, and the first, second, and third sensor circuits, 322A, 322B, and 322C are shown as being generally oriented within the same plane, the magnetic field sensors can be oriented in different planes (e.g., orthogonal planes). Although <FIG> show the magnetic field sensors 320A-320C and the sensor circuits 322A-322C as being positioned on the same side of the multilayer circuit <NUM>, the magnetic field sensors 320A-320C and the sensor circuits 322A-322C can be distributed between both sides of the multilayer circuit <NUM>. Example orientations of magnetic field sensors on a sensor assembly are disclosed in <CIT>, entitled "SENSOR ASSEMBLIES FOR ELECTROMAGNETIC NAVIGATION SYSTEMS", which is herein incorporated by reference for the purposes of disclosing orientations of magnetic field sensors on a sensor assembly. In certain embodiments, the multilayer circuit assembly <NUM> only includes two magnetic field sensors having different primary sensing directions. In certain embodiments, one or more of the magnetic field sensors is a dual-axis or tri-axis sensor having two or three primary sensing directions, respectively. The first, second, and third magnetic field sensors, 320A-320C, are configured to generate, in response to a magnetic field, responsive sensing signals. The sensing signals are used to determine location and orientation of the sensor assembly <NUM>.

In certain embodiments, the magnetic field sensors, 320A-320C, and/or the sensor circuits, 322A-322C, are electrically coupled to respective electrical mounting pads <NUM> via wire bonds <NUM>. In some embodiments, the magnetic field sensors, 320A-320C, and/or the sensor circuits, 322A-322C, are electrically coupled to respective electrical mounting pads <NUM> via a flip-chip fashion, through-silicon vias, fan-out wafer-level packaging, or other form of packaging known to the art. As previously mentioned, the electrical mounting pads <NUM> are electrically coupled to the electrical lead pads <NUM> by electrical traces. Example electrical connections among magnetic field sensors, sensor circuits, electrical lead pads, and electrical mounting pads are disclosed in <CIT>, entitled "ELECTROMAGNETIC NAVIGATION SYSTEM WITH MAGNETO-RESISTIVE SENSORS AND APPLICATION-SPECIFIC INTEGRATED CIRCUITS", which is hereby incorporated by reference for the purposes of disclosing example electrical connections.

In certain embodiments, when the magnetic field sensors 320A-320C are arranged in either a dual-axis or tri-axis arrangement, the multilayer circuit <NUM> includes six or seven electrical lead pads <NUM>, and the multilayer circuit assembly <NUM> includes six or seven electrical leads <NUM>. In the dual-axis arrangement, the multilayer circuit assembly <NUM> can include six electrical lead pads <NUM>: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, and one negative Y-axis signal lead pad. In the tri-axis arrangement, the multilayer circuit assembly <NUM> can include eight or nine electrical lead pads: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, one negative Y-axis signal lead pad, one positive Z-axis signal lead pad, one negative Z-axis signal lead pad, and a reset lead pad. In certain embodiments, the electrical leads <NUM> comprise a conductive material (e.g., copper), and the electrical lead pads <NUM> are spaced from each other at the proximal end 310A for sufficient electrical isolation. In certain embodiments, the magnetic field sensors are arranged in a single-axis, five degree-of-freedom arrangement.

<FIG> shows the multilayer circuit assembly <NUM> before a multilayer circuit <NUM> is formed into its final shape and before the multilayer circuit assembly <NUM> is incorporated into the sensor assembly <NUM>. For each of the electrical lead pads <NUM> and the electrical mounting pads <NUM>, the first mask layer 314A is removed such that the pads are exposed and accessible for electrical coupling respective electrical leads <NUM> and the wire bonds <NUM>, etc..

The multilayer circuit <NUM> includes a proximal section <NUM> with the exposed electrical lead pads <NUM> and a distal section <NUM> with the exposed electrical mounting pads <NUM>. During manufacture, the electrical leads <NUM> can be coupled to the electrical lead pads <NUM> via a plurality of approaches (e.g., reflowing solder such that the solder melts and solidifies, welding (laser and the like), tape-automated bonding, thermo-compression, ultrasonic compression, anisotropic conductive film, brazing, and the like) to mechanically and electrically couple the electrical leads <NUM> and the electrical lead pads <NUM>. Providing the electrical lead pads <NUM> on one side of the multilayer circuit <NUM> makes manufacturing easier, for example, because solder can be reflowed once on only one side of the multilayer circuit <NUM>. As noted above, the magnetic field sensors, 320A-320C, and the sensor circuits 322A-322C, can be electrically coupled to the electrical mounting pads <NUM> via wire bonds, flip-chips, through-silicon vias, fan-out wafer-level packaging, and the like. After the various electrical couplings are made, the proximal section <NUM> can be folded (e.g., rolled).

As shown in <FIG>, the proximal section <NUM> is folded such that the multilayer circuit <NUM> (and therefore the multilayer circuit assembly <NUM>) consumes a smaller cross-section area at the proximal end 310A of the multilayer circuit assembly <NUM>. In certain embodiments, the proximal section <NUM> is folded and forms a substantially c-shape. In such embodiments, the proximal section <NUM> has a substantially constant bending radius throughout a length of the cross-section. As shown in <FIG>, in certain embodiments, the proximal section <NUM> includes a first leg portion 330A and a second leg portion 330B and a bend portion <NUM> extending between the first leg portion 330A and the second leg portion 330B. The electrical lead pads <NUM> are positioned on the first leg portion 330A and the second leg portion 330B. The bend portion <NUM> has a substantially constant bending radius throughout its cross-section length while the first leg portion 330A and the second leg portion 330B are substantially straight. As shown in <FIG>, once the multilayer circuit <NUM> is folded, the electrical leads <NUM> and the electrical lead pads <NUM> are positioned within an inner area of the proximal section <NUM>. In other embodiments, once the multilayer circuit <NUM> is folded, the electrical leads <NUM> and the electrical lead pads <NUM> can be positioned outside the inner area of the proximal section <NUM> closer to the housing <NUM>.

As shown in <FIG> and <FIG>, the proximal section <NUM> has a length, L, extending along the longitudinal axis <NUM>. Only a portion of the proximal section <NUM> is covered by the second mask layer 314B such that flexible substrate <NUM> is exposed. Limiting coverage of the second mask layer 314B on the proximal section <NUM> may provide additional flexibility for folding or rolling the proximal section <NUM>. For example, without full coverage of the second mask layer 314B, the proximal section <NUM> can be folded with a small bending radius. In certain embodiments, to provide additional flexibility for folding or rolling the proximal section <NUM>, portions of one or more of the layers of the multilayer circuit <NUM> has a reduced thickness.

As shown in <FIG>, the cross-section area of the housing <NUM> can be separated into four quadrants 334A-334D and/or an upper half 336A and a lower half 336B, with each of the quadrants 334A-334D, and the halves 336A-336B having substantially the same respective cross-sectional area. As shown in <FIG>, when the multilayer circuit <NUM> is folded, at least one of the electrical leads <NUM> is positioned in each of the quadrants 334A-334D and the halves 336A-336B. This approach helps fully utilize the given cross-sectional area such that a sufficient number of electrical leads <NUM> and electrical lead pads <NUM> can be used without interfering with each other and without the electrical traces within the multilayer circuit <NUM> interfering with each other. In certain embodiments, the housing <NUM> has a diameter of. <NUM>-<NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> has a diameter of. <NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> is square or rectangular shaped. In certain embodiments the housing <NUM> includes an outer shell <NUM> comprising a material such as polyimide, PEEK, PTFE, FEP, polyurethane, silicone, parylene, metals (e.g., stainless steel, aluminum, titanium, nickel-based alloys, cobalt-base alloys, and the like), etc., and an epoxy filler material within the outer shell <NUM> to maintain the position of the multilayer circuit assembly <NUM> in the housing <NUM>. In certain embodiments, the entire housing <NUM> comprises an epoxy material.

<FIG> show a sensor assembly <NUM> that can be used in a medical device (like the medical device <NUM> in <FIG>). For example, the sensor assembly <NUM> can be positioned within the medical device (e.g., at or near a distal end of the medical device). The sensor assembly <NUM> includes a multilayer circuit assembly <NUM> electrically coupled to electrical leads <NUM> and positioned within a housing <NUM>.

The multilayer circuit assembly <NUM> includes a multilayer circuit <NUM> extending between a proximal end (not shown) and a distal end <NUM>. The multilayer circuit <NUM> comprising a flexible substrate <NUM>, a first mask layer 714A, a second mask layer 714B, electrical lead pads <NUM>, electrical mounting pads <NUM>, and electrical traces (not shown) that electrically couple certain electrical lead pads <NUM> to certain electrical mounting pads <NUM>. The first mask layer 714A and the second mask layer 714B are positioned on opposite sides of the flexible substrate <NUM>. In certain embodiments, the multilayer circuit <NUM> is about <NUM> micrometers thick.

The multilayer circuit assembly <NUM> further includes first, second, and third magnetic field sensors, 720A, 720B, and 720C, and first, second, and third sensor circuits, 722A, 722B, and 722C. As shown in <FIG>, the magnetic field sensors, 720A-720C, and the sensor circuits, 722A-722C, can be implemented on separate dies and positioned next to each other. In such embodiments, the magnetic field sensors, 720A-720C, and the sensor circuits, 722A-722C, can be electrically and communicatively coupled together. In certain embodiments, respective magnetic field sensors, 720A-720C, and the sensor circuits, 722A-722C, can be implemented on the same die or substrate (e.g., a monolithic design). For example, the magnetic field sensors, 720A-720C, can be fabricated on top of respective sensor circuits, 722A-722C.

The magnetic field sensors 720A-720C can include sensors such as inductive sensing coils and/or various sensing elements such as MR sensing elements (e.g., AMR sensing elements, GMR sensing elements, TMR sensing elements, Hall effect sensing elements, CMR sensing elements, EMR sensing elements, spin Hall sensing elements, and the like), GMI sensing elements, and/or flux-gate sensing elements. The MR sensing elements are configured to sense magnetic fields, like those generated by the magnetic field transmitter assemblies, <NUM>-<NUM> of <FIG>, and generate a responsive sensing signal. In addition, the multilayer circuit assembly <NUM> can feature other types of sensors, such as temperature sensors, ultrasound sensors, etc. Sensing signals generated by the magnetic field sensors 720A-720C can be transmitted from the sensor assembly <NUM> to a controller, such as the magnetic field controller <NUM> of <FIG>, wirelessly or via one or more conductors.

In certain embodiments, the magnetic field sensors 720A-720C are arranged in a dual-axis, six degree-of-freedom arrangement. In such embodiments, the first magnetic field sensor 720A and the second magnetic field sensor 720B are oriented such that their primary sensing direction is aligned along a longitudinal axis <NUM> (e.g., X-axis) of the sensor assembly <NUM>. The third magnetic field sensor 720C is oriented such that its primary sensing direction is aligned along an axis (e.g., Y-axis) orthogonal to the longitudinal axis <NUM>. In certain embodiments, the magnetic field sensors 720A-720C are arranged in a tri-axis, six degree-of-freedom arrangement. In such embodiments, the magnetic field sensors' primary sensing directions are orthogonal to each other. Although the first, second, and third magnetic field sensors, 720A, 720B, and 720C, and the first, second, and third sensor circuits, 722A, 722B, and 722C are shown as being generally oriented within the same plane, the magnetic field sensors can be oriented in different planes (e.g., orthogonal planes). Although <FIG> show the magnetic field sensors 720A-720C and the sensor circuits 722A-722C as being positioned on the same side of the multilayer circuit <NUM>, the magnetic field sensors 720A-720C and the sensor circuits 722A-722C can be distributed between both sides of the multilayer circuit <NUM>. In certain embodiments, the multilayer circuit assembly <NUM> only includes two magnetic field sensors having different primary sensing directions. In certain embodiments, one or more of the magnetic field sensors is a dual-axis or tri-axis sensor having two or three primary sensing directions, respectively. The first, second, and third magnetic field sensors, 720A-720C, are configured to generate, in response to a magnetic field, responsive sensing signals. The sensing signals are used to determine location and orientation of the sensor assembly <NUM>. In certain embodiments, the magnetic field sensors are arranged in a single-axis, five degree-of-freedom arrangement.

In certain embodiments, the magnetic field sensors, 720A-720C, and/or the sensor circuits, 722A-722C, are electrically coupled to respective electrical mounting pads <NUM> via wire bonds <NUM>. In some embodiments, the magnetic field sensors, 720A-720C, and/or the sensor circuits, 722A-722C, are electrically coupled to respective electrical mounting pads <NUM> via a flip-chip fashion, through-silicon vias, or fan-out wafer-level packaging. As previously mentioned, the electrical mounting pads <NUM> are electrically coupled to the electrical lead pads <NUM> by electrical traces.

In certain embodiments, when the magnetic field sensors 720A-720C are arranged in either a dual-axis or tri-axis arrangement, the multilayer circuit <NUM> includes six or seven electrical lead pads <NUM>, and the multilayer circuit assembly <NUM> includes six or seven electrical leads <NUM>. In the dual-axis arrangement, multilayer circuit assembly <NUM> can include six electrical lead pads <NUM>: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, and one negative Y-axis signal lead pad. In the tri-axis arrangement, the multilayer circuit assembly <NUM> can include eight or nine electrical lead pads: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, one negative Y-axis signal lead pad, one positive Z-axis signal lead pad, one negative Z-axis signal lead pad, and a reset lead pad In certain embodiments, the electrical leads <NUM> comprise a conductive material (e.g., copper), and the electrical lead pads <NUM> are spaced from each other at the proximal end for sufficient electrical isolation.

As shown in <FIG>, the multilayer circuit <NUM> is not folder or rolled like the multilayer circuit <NUM> of <FIG>. Instead of folding or rolling, the multilayer circuit <NUM> is able to fit the electrical lead pads <NUM> into a limited cross-section area by distributing the electrical lead pads <NUM> between both sides of the flexible substrate <NUM>. Further, because the multilayer circuit <NUM> is not folder or rolled, the multilayer circuit <NUM> can be rigid and utilize more rigid printed circuit boards compared to the multilayer circuit <NUM> of <FIG>. During manufacture, the electrical leads <NUM> can be coupled to the electrical lead pads <NUM> via a plurality of approaches (e.g., reflowing solder such that the solder melts and solidifies, welding (laser and the like), tape-automated bonding, thermo-compression, ultrasonic compression, anisotropic conductive film, brazing, and the like) to mechanically and electrically couple the electrical leads <NUM> and the electrical lead pads <NUM>. As noted above, the magnetic field sensors, 720A-720C, and the sensor circuits 722A-722C, can be electrically coupled to the electrical mounting pads <NUM> via wire bonds, flip-chips, through-silicon vias, fan-out wafer-level packaging, and the like.

As shown in <FIG>, the cross-section area of the housing <NUM> can be separated into four quadrants 726A-726D and/or an upper half 728A and a lower half 728B, with each of the quadrants 726A-726D, and the halves 728A-728B having substantially the same respective cross-sectional area. As shown in <FIG>, in such a configuration, at least one of the electrical leads <NUM> is positioned in each of the quadrants 726A-726D and the halves 728A-728B. This approach helps fully utilize the given cross-sectional area such that a sufficient number of electrical leads <NUM> and electrical lead pads <NUM> can be used without interfering with each other and without the electrical traces within the multilayer circuit <NUM> from interfering with each other. In certain embodiments, the housing <NUM> has a diameter of. <NUM>-<NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> has a diameter of. <NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> is square or rectangular shaped. In certain embodiments the housing <NUM> includes an outer shell <NUM> comprising a material such as polyimide, PEEK, PTFE, FEP, polyurethane, silicone, parylene, metals (e.g., stainless steel, aluminum, titanium, nickel-based alloys, cobalt-base alloys, and the like), etc., and an epoxy filler material to maintain the position of the multilayer circuit assembly <NUM> in the housing <NUM>. In certain embodiments, the entire housing <NUM> comprises an epoxy material.

<FIG> show a sensor assembly <NUM> that can be used in a medical device (like the medical device <NUM> in <FIG>). For example, the sensor assembly <NUM> can be positioned within the medical device (e.g., at or near a distal end of the medical device). The sensor assembly <NUM> includes a multilayer circuit assembly <NUM> electrically coupled to electrical leads <NUM> and positioned within a housing <NUM>.

The multilayer circuit assembly <NUM> includes a multilayer circuit <NUM> extending between a proximal end (not shown) and a distal end <NUM>. The multilayer circuit <NUM> comprising a flexible substrate <NUM>, a first mask layer 914A, a second mask layer 914B, electrical lead pads <NUM>, electrical mounting pads <NUM>, and electrical traces (not shown) that electrically couple certain electrical lead pads <NUM> to certain electrical mounting pads <NUM>. The first mask layer 914A and the second mask layer 914B are positioned on opposite sides of the flexible substrate <NUM>. In certain embodiments, the multilayer circuit <NUM> is about <NUM> micrometers thick.

The multilayer circuit assembly <NUM> further includes first, second, and third magnetic field sensors, 920A, 920B, and 920C, and first, second, and third sensor circuits, 922A, 922B, and 922C. As shown in <FIG>, the magnetic field sensors, 920A-920C, and the sensor circuits, 922A-922C, can be implemented on separate dies and positioned next to each other. In such embodiments, the magnetic field sensors, 920A-920C, and the sensor circuits, 922A-922C, can be electrically and communicatively coupled together. In certain embodiments, respective magnetic field sensors, 920A-920C, and the sensor circuits, 922A-922C, can be implemented on the same die or substrate (e.g., a monolithic design). For example, the magnetic field sensors, 920A-920C, can be fabricated on top of respective sensor circuits, 922A-922C.

The magnetic field sensors 920A, 920B, and 920C can include sensors such as inductive sensing coils and/or various sensing elements such as MR sensing elements (e.g., AMR sensing elements, GMR sensing elements, TMR sensing elements, Hall effect sensing elements, CMR sensing elements, EMR sensing elements, spin Hall sensing elements, and the like), GMI sensing elements, and/or flux-gate sensing elements. The MR sensing elements are configured to sense magnetic fields, like those generated by the magnetic field transmitter assemblies, <NUM>-<NUM> of <FIG>, and generate a responsive sensing signal. In addition, the multilayer circuit assembly <NUM> can feature other types of sensors, such as temperature sensors, ultrasound sensors, etc. Sensing signals generated by the magnetic field sensors 920A-920C can be transmitted from the sensor assembly <NUM> to a controller, such as the magnetic field controller <NUM> of <FIG>, wirelessly or via one or more conductors.

In certain embodiments, the magnetic field sensors 920A-920C are arranged in a dual-axis, six degree-of-freedom arrangement. In such embodiments, the first magnetic field sensor 920A and the second magnetic field sensor 920B are oriented such that their primary sensing direction is aligned along a longitudinal axis <NUM> (e.g., X-axis) of the sensor assembly <NUM>. The third magnetic field sensor 920C is oriented such that its primary sensing direction is aligned along an axis (e.g., Y-axis) orthogonal to the longitudinal axis <NUM>. In certain embodiments, the magnetic field sensors 920A-920C are arranged in a tri-axis, six degree-of-freedom arrangement. In such embodiments, the magnetic field sensors' primary sensing directions are orthogonal to each other. Although the first, second, and third magnetic field sensors, 920A, 920B, and 920C, and the first, second, and third sensor circuits, 922A, 922B, and 922C are shown as being generally oriented within the same plane, the magnetic field sensors can be oriented in different planes (e.g., orthogonal planes). Although <FIG> show the magnetic field sensors 920A-920C and the sensor circuits 922A-922C as being positioned on the same side of the multilayer circuit <NUM>, the magnetic field sensors 920A-920C and the sensor circuits 922A-922C can be distributed between both sides of the multilayer circuit <NUM>. In certain embodiments, the multilayer circuit assembly <NUM> only includes two magnetic field sensors having different primary sensing directions. In certain embodiments, one or more of the magnetic field sensors is a dual-axis or tri-axis sensor having two or three primary sensing directions, respectively. The first, second, and third magnetic field sensors, 920A-920C, are configured to generate, in response to a magnetic field, responsive sensing signals. The sensing signals are used to determine location and orientation of the sensor assembly <NUM>.

In certain embodiments, the magnetic field sensors, 920A-920C, and/or the sensor circuits, 922A-922C, are electrically coupled to respective electrical mounting pads <NUM> via wire bonds <NUM>. In some embodiments, the magnetic field sensors, 920A-920C, and/or the sensor circuits, 922A-922C, are electrically coupled to respective electrical mounting pads <NUM> via a flip-chip fashion, through-silicon vias, or fan-out wafer-level packaging. As previously mentioned, the electrical mounting pads <NUM> are electrically coupled to the electrical lead pads <NUM> by electrical traces.

In certain embodiments, when the magnetic field sensors 920A-920C are arranged in either a dual-axis or tri-axis arrangement, the multilayer circuit <NUM> includes six or seven electrical lead pads <NUM>, and the multilayer circuit assembly <NUM> includes six or seven electrical leads <NUM>. In the dual-axis arrangement, multilayer circuit assembly <NUM> can include six electrical lead pads <NUM>: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, and one negative Y-axis signal lead pad. In the tri-axis arrangement, the multilayer circuit assembly <NUM> can include eight or nine electrical lead pads: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, one negative Y-axis signal lead pad, one positive Z-axis signal lead pad, one negative Z-axis signal lead pad, and a reset lead pad. In certain embodiments, the electrical leads <NUM> comprise a conductive material (e.g., copper), and the electrical lead pads <NUM> are spaced from each other at the proximal end for sufficient electrical isolation.

The multilayer circuit <NUM> includes a proximal section <NUM> with the exposed electrical lead pads <NUM> and a distal section <NUM> with the exposed electrical mounting pads <NUM>. During manufacture, the electrical leads <NUM> can be coupled to the electrical lead pads <NUM> via a plurality of approaches (e.g., reflowing solder such that the solder melts and solidifies, welding (laser and the like), tape-automated bonding, thermo-compression, ultrasonic compression, anisotropic conductive film, brazing, and the like) to mechanically and electrically couple the electrical leads <NUM> and the electrical lead pads <NUM>. As noted above, the magnetic field sensors, 920A-920C, and the sensor circuits 922A-922C, can be electrically coupled to the electrical mounting pads <NUM> via wire bonds, flip-chips, through-silicon vias, fan-out wafer-level packaging, and the like. After the various electrical couplings are made, the proximal section <NUM> can be folded (e.g., rolled).

As shown in <FIG>, the proximal section <NUM> is folded such that the multilayer circuit <NUM> (and therefore the multilayer circuit assembly <NUM>) consumes a smaller cross-section area at the proximal end of the multilayer circuit assembly <NUM>. In certain embodiments, the proximal section <NUM> is folded and forms a substantially c-shape. In such embodiments, the proximal section <NUM> has a substantially constant bending radius throughout a length of the cross-section. As shown in <FIG>, in certain embodiments, the proximal section <NUM> includes a first leg portion 930A and a second leg portion 930B and a bend portion <NUM> extending between the first leg portion 930A and the second leg portion 930B. The electrical lead pads <NUM> are positioned on the first leg portion 930A and the second leg portion 930B. The bend portion <NUM> has a substantially constant bending radius throughout its cross-section length while the first leg portion 930A and the second leg portion 930B are substantially straight. In addition to folding the proximal section <NUM>, the multilayer circuit <NUM> distributes the electrical lead pads <NUM> between both sides of the flexible substrate <NUM>. For example, the multilayer circuit <NUM> includes four electrical lead pads <NUM> on a first side of the flexible substrate <NUM> and two electrical lead pads on an opposite side of the flexible substrate <NUM>. As shown in <FIG>, once the multilayer circuit <NUM> is folded, the electrical leads <NUM> and the electrical lead pads <NUM> are positioned within an inner area and an outer area of the proximal section <NUM>. In particular, two of the electrical lead pads <NUM> are positioned within the inner area of the folded proximal section <NUM> and four of the electrical lead pads <NUM> are positioned outside the inner area.

As shown in <FIG>, only a portion of the proximal section <NUM> is covered by the second mask layer 914B such that the flexible substrate <NUM> is exposed. Limiting coverage of the second mask layer 914B on the proximal section <NUM> may provide additional flexibility for folding or rolling the proximal section <NUM>. For example, without full coverage of the second mask layer 914B (or first mask layer 914A), the proximal section <NUM> can be folded with a small bending radius. In certain embodiments, to provide additional flexibility for folding or rolling the proximal section <NUM>, portions of one or more of the layers of the multilayer circuit <NUM> has a reduced thickness.

As shown in <FIG>, the cross-section area of the housing <NUM> can be separated into four quadrants 934A-934D and/or an upper half 936A and a lower half 936B, with each of the quadrants 934A-934D, and the halves 936A-936B having substantially the same respective cross-sectional area. As shown in <FIG>, when the multilayer circuit <NUM> is folded, at least one of the electrical leads <NUM> is positioned in each of the quadrants 934A-934D and the halves 936A-936B. This approach helps fully utilize the given cross-sectional area such that a sufficient number of electrical leads <NUM> and electrical lead pads <NUM> can be used without interfering with each other and without the electrical traces within the multilayer circuit <NUM> from interfering with each other. In certain embodiments, the housing <NUM> has a diameter of. <NUM>-<NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> has a diameter of. <NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> is square or rectangular shaped. In certain embodiments the housing <NUM> includes an outer shell <NUM> comprising a material such as polyimide, PEEK, PTFE, FEP, polyurethane, silicone, parylene, metals (e.g., stainless steel, aluminum, titanium, nickel-based alloys, cobalt-base alloys, and the like), etc., and an epoxy filler material to maintain the position of the multilayer circuit assembly <NUM> in the housing <NUM>. In certain embodiments, the entire housing <NUM> comprises an epoxy material.

<FIG> show a sensor assembly <NUM> or portions thereof that can be used in a medical device (like the medical device <NUM> in <FIG>). For example, the sensor assembly <NUM> can be positioned within the medical device (e.g., at or near a distal end of the medical device). The sensor assembly <NUM> includes a multilayer circuit assembly <NUM> electrically coupled to electrical leads <NUM> (see <FIG>) and positioned within a housing <NUM> (see <FIG> shows the multilayer circuit assembly <NUM> before a multilayer circuit <NUM> is formed into its final shape and before the multilayer circuit assembly <NUM> is incorporated into the sensor assembly <NUM>.

The multilayer circuit assembly <NUM> includes a multilayer circuit <NUM> extending between a proximal end 1110A and a distal end 1110B. The multilayer circuit <NUM> comprising a flexible substrate <NUM>, a first mask layer 1114A, a second mask layer 1114B, electrical lead pads <NUM>, electrical mounting pads <NUM>, and electrical traces (not shown) that electrically couple certain electrical lead pads <NUM> to certain electrical mounting pads <NUM>. The first mask layer 1114A and the second mask layer 1114B are positioned on opposite sides of the flexible substrate <NUM>. In certain embodiments, the multilayer circuit <NUM> is about <NUM> micrometers thick.

The multilayer circuit assembly <NUM> further includes first, second, and third magnetic field sensors, 1120A, 1120B, and 1120C, and first, second, and third sensor circuits, 1122A, 1122B, and 1122C. As shown in <FIG>, the magnetic field sensors, 1120A-1120C, and the sensor circuits, 1122A-1122C, can be implemented on separate dies and positioned next to each other. In such embodiments, the magnetic field sensors, 1120A-1120C, and the sensor circuits, 1122A-1122C, can be electrically and communicatively coupled together. In certain embodiments, respective magnetic field sensors, 1120A-1120C, and the sensor circuits, 1122A-1122C, can be implemented on the same die or substrate (e.g., a monolithic design). For example, the magnetic field sensors, 1120A-1120C, can be fabricated on top of respective sensor circuits, 1122A-1122C.

The magnetic field sensors 1120A, 1120B, and 1120C can include sensors such as inductive sensing coils and/or various sensing elements such as MR sensing elements (e.g., AMR sensing elements, GMR sensing elements, TMR sensing elements, Hall effect sensing elements, CMR sensing elements, EMR sensing elements, spin Hall sensing elements, and the like), GMI sensing elements, and/or flux-gate sensing elements. The MR sensing elements are configured to sense magnetic fields, like those generated by the magnetic field transmitter assemblies, <NUM>-<NUM> of <FIG>, and generate a responsive sensing signal. In addition, the multilayer circuit assembly <NUM> can feature other types of sensors, such as temperature sensors, ultrasound sensors, etc. Sensing signals generated by the magnetic field sensors 1120A-1120C can be transmitted from the sensor assembly <NUM> to a controller, such as the magnetic field controller <NUM> of <FIG>, wirelessly or via one or more conductors.

In certain embodiments, the magnetic field sensors 1120A-1120C are arranged in a dual-axis, six degree-of-freedom arrangement. In such embodiments, the first magnetic field sensor 1120A and the second magnetic field sensor 1120B are oriented such that their primary sensing direction is aligned along a longitudinal axis <NUM> (e.g., X-axis) of the sensor assembly <NUM>. The third magnetic field sensor 1120C is oriented such that its primary sensing direction is aligned along an axis (e.g., Y-axis) orthogonal to the longitudinal axis <NUM>. In certain embodiments, the magnetic field sensors 1120A-1120C are arranged in a tri-axis, six degree-of-freedom arrangement. In such embodiments, the magnetic field sensors' primary sensing directions are orthogonal to each other. Although the first, second, and third magnetic field sensors, 1120A, 1120B, and 1120C, and the first, second, and third sensor circuits, 1122A, 1122B, and 1122C are shown as being generally oriented within the same plane, the magnetic field sensors can be oriented in different planes (e.g., orthogonal planes). Although <FIG> show the magnetic field sensors 1120A-1120C and the sensor circuits 1122A-1122C as being positioned on the same side of the multilayer circuit <NUM>, the magnetic field sensors 1120A-1120C and the sensor circuits 1122A-1122C can be distributed between both sides of the multilayer circuit <NUM>. In certain embodiments, the multilayer circuit assembly <NUM> only includes two magnetic field sensors having different primary sensing directions. In certain embodiments, one or more of the magnetic field sensors is a dual-axis or tri-axis sensor having two or three primary sensing directions, respectively. The first, second, and third magnetic field sensors, 1120A-1120C, are configured to generate, in response to a magnetic field, responsive sensing signals. The sensing signals are used to determine location and orientation of the sensor assembly <NUM>.

In certain embodiments, the magnetic field sensors, 1120A-1120C, and/or the sensor circuits, 1122A-1122C, are electrically coupled to respective electrical mounting pads <NUM> via wire bonds <NUM>. In some embodiments, the magnetic field sensors, 1120A-1120C, and/or the sensor circuits, 1122A-1122C, are electrically coupled to respective electrical mounting pads <NUM> via a flip-chip fashion, through-silicon vias, or fan-out wafer-level packaging. As previously mentioned, the electrical mounting pads <NUM> are electrically coupled to the electrical lead pads <NUM> by electrical traces.

In certain embodiments, when the magnetic field sensors 1120A-1120C are arranged in either a dual-axis or tri-axis arrangement, the multilayer circuit <NUM> includes six or seven electrical lead pads <NUM>, and the multilayer circuit assembly <NUM> includes six or seven electrical leads <NUM>. In the dual-axis arrangement, multilayer circuit assembly <NUM> can include six electrical lead pads <NUM>: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, and one negative Y-axis signal lead pad. In the tri-axis arrangement, the multilayer circuit assembly <NUM> can include eight or nine electrical lead pads: one ground lead pad, one bias lead pad, one positive X-axis signal lead pad, one negative X-axis signal lead pad, one positive Y-axis signal lead pad, one negative Y-axis signal lead pad, one positive Z-axis signal lead pad, one negative Z-axis signal lead pad, and a reset lead pad. In certain embodiments, the electrical leads <NUM> comprise a conductive material (e.g., copper), and the electrical lead pads <NUM> are spaced from each other at the proximal end for sufficient electrical isolation.

<FIG> shows the multilayer circuit assembly <NUM> before a multilayer circuit <NUM> is formed into its final shape and before the multilayer circuit assembly <NUM> is incorporated into the sensor assembly <NUM>. For each of the electrical lead pads <NUM> and the electrical mounting pads <NUM>, the first mask layer 1114A is removed such that the pads are exposed and accessible for electrical coupling respective electrical leads <NUM> and the wire bonds <NUM>, etc..

The multilayer circuit <NUM> includes a proximal section <NUM> with the exposed electrical lead pads <NUM> and a distal section <NUM> with the exposed electrical mounting pads <NUM>. During manufacture, the electrical leads <NUM> can be coupled to the electrical lead pads <NUM> via a plurality of approaches (e.g., reflowing solder such that the solder melts and solidifies, welding (laser and the like), tape-automated bonding, thermo-compression, ultrasonic compression, anisotropic conductive film, brazing, and the like) to mechanically and electrically couple the electrical leads <NUM> and the electrical lead pads <NUM>. As noted above, the magnetic field sensors, 1120A-1120C, and the sensor circuits 1122A-1122C, can be electrically coupled to the electrical mounting pads <NUM> via wire bonds, flip-chips, through-silicon vias, fan-out wafer-level packaging, and the like. After the various electrical couplings are made, the proximal section <NUM> can be folded (e.g., rolled).

As shown in <FIG>, the proximal section <NUM> is folded such that the multilayer circuit <NUM> (and therefore the multilayer circuit assembly <NUM>) consumes a smaller cross-section area at the proximal end 1110A of the multilayer circuit assembly <NUM>. In certain embodiments, the proximal section <NUM> is folded and forms shape that at least partially mimics a shape of the housing <NUM>. In such embodiments, a portion of the proximal section <NUM> has a substantially constant bending radius throughout a length of the cross-section. As shown in <FIG>, in certain embodiments, the proximal section <NUM> includes a leg portion and a bend portion. The electrical lead pads <NUM> are positioned on both the leg portion and the bend portion. In particular, four of the electrical lead pads <NUM> are positioned on the bend portion and two of the electrical lead pads <NUM> are positioned on the leg portion. The bend portion has a substantially constant bending radius throughout its cross-section length while the leg portion is substantially straight. As shown in <FIG>, once the multilayer circuit <NUM> is folded, the electrical leads <NUM> and the electrical lead pads <NUM> are positioned within an inner area of the proximal section <NUM>.

As shown in <FIG>, the proximal section <NUM> has a length, L, extending along the longitudinal axis <NUM>. In certain embodiments, to provide additional flexibility for folding or rolling the proximal section <NUM>, portions of one or more of the layers of the multilayer circuit <NUM> has a reduced thickness or can be removed.

As shown in <FIG>, the cross-section area of the housing <NUM> can be separated into four quadrants 1134A-1134D and/or an upper half 1136A and a lower half 1136B, with each of the quadrants 1134A-1134D, and the halves 1136A-1136B having substantially the same respective cross-sectional area. As shown in <FIG>, when the multilayer circuit <NUM> is folded, at least one of the electrical leads <NUM> is positioned in each of the quadrants 1134A-1134D and the halves 1136A-1136B. This approach helps fully utilize the given cross-sectional area such that a sufficient number of electrical leads <NUM> and electrical lead pads <NUM> can be used without interfering with each other and without the electrical traces within the multilayer circuit <NUM> from interfering with each other. In certain embodiments, the housing <NUM> has a diameter of. <NUM>-<NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> has a diameter of. <NUM> (i.e., cross-section area of. <NUM><NUM>) and a length of <NUM>-<NUM>. In certain embodiments, the housing <NUM> is square or rectangular shaped. In certain embodiments the housing <NUM> includes an outer shell <NUM> comprising a material such as polyimide, PEEK, PTFE, FEP, polyurethane, silicone, parylene, metals (e.g., stainless steel, aluminum, titanium, nickel-based alloys, cobalt-base alloys, and the like), etc., and an epoxy filler material to maintain the position of the multilayer circuit assembly <NUM> in the housing <NUM>. In certain embodiments, the entire housing <NUM> comprises an epoxy material.

Claim 1:
A sensor assembly (<NUM>; <NUM>) comprising:
a multilayer circuit (<NUM>; <NUM>) extending between a proximal end and a distal end along a longitudinal axis (<NUM>; <NUM>), the multilayer circuit (<NUM>; <NUM>) including a plurality of electrical pads positioned at the proximal end;
a first magnetic field sensor (720A; 920A) coupled to the multilayer circuit (<NUM>; <NUM>) and having a primary sensing direction aligned with the longitudinal axis (<NUM>; <NUM>); and
a second magnetic field sensor (720B; 920B) coupled to the multilayer circuit (<NUM>; <NUM>) and oriented with respect to the first magnetic field sensor (720A; 920A) such that the second magnetic field sensor (720B; 920B) has a primary sensing direction aligned with an axis orthogonal to the longitudinal axis (<NUM>; <NUM>),
wherein the multilayer circuit (<NUM>; <NUM>) includes a flexible substrate layer (<NUM>; <NUM>), wherein a first subset of the plurality of electrical pads is positioned on a first side of the flexible substrate layer (<NUM>; <NUM>), characterized in that
a second subset of the plurality of electrical pads is positioned on a second side of the flexible substrate layer (<NUM>; <NUM>), and wherein the first side and the second side face in opposite directions.