System and method for acquiring an impedance cardiography (ICG) signal using a wearable device

Abstract

A method of acquiring an impedance cardiography signal from a user of a wearable computing device includes receiving, from one or more dry electrodes on the wearable computing device, impedance cardiography data for a given time period. The impedance cardiography data is representative of thoracic and peripheral impedance changes of the user. The method also includes processing, via at least one processor of the wearable computing device, the impedance cardiography data to obtain the impedance cardiography signal. Further, the method includes displaying, via an electronic display of the wearable computing device, the impedance cardiography signal to the user.

Description

SYSTEM AND METHOD FOR ACQUIRING AN IMPEDANCE CARDIOGRAPHY (ICG) SIGNAL USING A WEARABLE DEVICEFIELD OF THE INVENTION

[0001] The present disclosure relates generally to wearable computing devices, and more particularly, to systems and methods for acquiring an impedance cardiography (ICG) signal using a wearable computing device.BACKGROUND

[0002] Impedance cardiography (ICG) is a non-invasive cardiovascular measurement technique that measures changes in the electrical impedance across the chest from each heartbeat that is used to calculate a number of cardiovascular parameters, such as heart rate, cardiac output, ventricular ejection time, and stroke volume. Conventional ICG measurement techniques involve the use of gel electrodes applied across the chest, so that the measured impedance occurs over the heart. As the heart cyclically pumps blood throughout the body, this produces a hemodynamic change in blood flow, blood volume, and blood pressure that is correlated to a change in the measured impedance. By continuously measuring the changes in impedance over time, an ICG waveform can be generated that is used to identify key cardiovascular features such as the left ventricular ejection time.

[0003] An advantage of ICG is that it is a non-invasive procedure, which means that it does not require the insertion of any catheters or needles into the body. The non-invasive nature of measuring ICG renders it a safe and well-tolerated procedure for patients of all ages. ICG is also relatively inexpensive, making it a cost-effective option for monitoring cardiac function. As such, ICG can be used to evaluate a wide range of cardiovascular conditions, including heart failure, arrhythmias, and hypertension. ICG is also used to assess the effects of medication and therapy, and to evaluate the progress of patients before and after surgery.

[0004] There are two primary considerations when measuring ICG for human subjects: 1) the electrical technique used to measure changes in electrical impedance and 2) the type and positioning of electrodes to facilitate measurement. The fundamental principle of ICG measurement relies upon the direct relationship between voltage, currents, and impedances in the body wherein V is the voltage, Z is the impedance of the body, and I is an alternating current: V = I*Z.

[0005] As blood is a conductor and due to the hemodynamics of the changes to blood flow throughout the body, changes to blood volume throughout a heart beat cycle reflects changesto thoracic impedance; i.e., Z changes with respect to time (dZ / dt). By inducing an alternating current across the thoracic region, impedance changes can be measured for each heartbeat from which there are signal features that feed into equations for the calculation of stroke volume. It is important to note that this derivation is based on a system without additional inductive / capacitive elements. For dry electrode ICG measurements, electrode contact impedance can be a challenge. This is because a majority of the ICG literature reports on gel electrodes wherein contact impedance is reduced or negligible - i.e. how contact impedance impacts the ICG waveform is not well understood.

[0006] There are two components to the electrical measurement of conventional ICG. The first component is the injection of a high frequency, low magnitude current that is transmitted through the chest between two current electrodes. The second component is the measurement of impedance across the chest (within the placement of the stimulating electrodes) that is used to measure the impedance (between two voltage / recording electrodes) developed across the impedance which is driven by the current. Often, there is also uniform distribution of excitation current density over the voltage electrodes. Furthermore, when performing ICG measurements across the chest, the current electrodes are typically placed outwards (distal) relative to the sensing electrodes (i.e. the sensing electrodes are between the current electrodes).

[0007] Current ICG applications have been limited to gel electrodes, wherein the gel electrodes are typically positioned on the thorax or neck in a clinical setting. As such, conventional ICG measurement set-up is time consuming, relies upon bulky ICG instrumentation, and is restricted to short-term usage due to the nature of gel electrodes. As a consequence, ICG is typically restricted to clinical settings, including hospitals, clinics, and research institutions.

[0008] Accordingly, systems and methods for acquiring an ICG signal using a wearable computing device that addresses the aforementioned issues would be welcomed in the art.SUMMARY OF THE INVENTION

[0009] Aspects and advantages of embodiments of the present disclosure will be set forth in part in the following description, or can be learned from the description, or can be learned through practice of the embodiments.

[0010] In an aspect, the present disclosure is directed to a method of acquiring an impedance cardiography signal from a user of a wearable computing device. The method includes receiving, from one or more dry electrodes on the wearable computing device, impedancecardiography data for a given time period. The impedance cardiography data is representative of thoracic and peripheral impedance changes of the user. The method also includes processing, via at least one processor of the wearable computing device, the impedance cardiography data to obtain the impedance cardiography signal. Further, the method includes displaying, via an electronic display of the wearable computing device, the impedance cardiography signal to the user.

[0011] In another aspect, the present disclosure is directed to a wearable computing device. The wearable computing device includes an electronic display, one or more dry electrodes, and one or more processors configured to perform a plurality of operations, including but not limited to receiving, from the one or more dry electrodes, impedance cardiography data for a given time period, the impedance cardiography data being representative of thoracic and peripheral impedance changes of a user of the wearable computing device, processing the impedance cardiography data to obtain an impedance cardiography signal, and displaying, via the electronic display, the impedance cardiography signal to the user.

[0012] These and other features, aspects, and advantages of various embodiments of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate example embodiments of the present disclosure and, together with the description, serve to explain the related principles.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Detailed discussion of embodiments directed to one of ordinary skill in the art is set forth in the specification, which makes reference to the appended figures, in which:

[0014] FIG. 1 provides a front perspective view of an embodiment of a wearable computing device on a wrist of a user according to the present disclosure;

[0015] FIG. 2 provides a rear view of the wearable computing device of FIG. 1 according to the present disclosure;

[0016] FIG. 3 provides a side view of the wearable computing device of FIGS. 1 and 2 according to the present disclosure;

[0017] FIG. 4 illustrates various controller components of an embodiment of a system that can be utilized with the wearable computing device of FIGS. 1-3 according to the present disclosure;

[0018] FIG. 5 illustrates a schematic diagram of an embodiment of an environment in which a wearable computing device according to the present disclosure can be utilized; and

[0019] FIG. 6 illustrates a flow diagram of an embodiment of a method of acquiring an impedance cardiography signal from a user of a wearable computing device according to the present disclosure.DETAILED DESCRIPTION

[0020] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0021] Generally, the present disclosure is directed to a method of using a wearable computing device for acquiring an impedance cardiography (ICG) signal using dry electrodes that is representative of both across-chest (thoracic) and peripheral impedance changes. As such, the ICG signal can be used for the evaluation of cardiovascular health; particularly mechanical heart health, peripheral vascular health, left ventricular ejection time, and / or cardiac output. More specifically, the wearable computing device includes an electrode system having a plurality of dry electrodes (such as a four electrode system). For example, in an embodiment, the wearable computing device may generally include a pair of dry electrodes on an underside (e.g., wrist-facing) and a pair of dry electrodes on the top or side surface (e.g., for finger placement). It should be understood that any number of dry electrodes having any suitable arrangement may also be utilized.

[0022] By doing so, an electrical circuit is formed wherein a time-series impedance measurement is acquired resembling changes to vascular hemodynamic changes occurring across the body. Accordingly, in certain embodiments, methods of the present disclosure may include a user placing the wearable computing device on-wrist, the user selecting the wearable computing device to perform an ICG measurement, and the user placing one or more fingers on the top-side electrodes. Signal acquisition then begins for a defined time period. After the defined time period ends, signal acquisition stops, and the user removes finger placement from the top-side electrodes. The wearable computing device is then configured to display cardiovascular metrics to the user. As such, the present disclosureprovides various advantages over conventional ICG measurement systems. In particular embodiments, measuring ICG with dry electrodes is more user friendly than using gel electrodes. Furthermore, on-wrist application of ICG does not require complex set-up (e.g., wires, gel electrodes, chest placement, etc.). Moreover, systems and methods of the present disclosure provide a measurement of both thoracic and peripheral (arm) hemodynamics to the user in a quick, simple, and accurate manner.

[0023] With reference now to the figures, example embodiments of the present disclosure will be discussed in further detail.

[0024] Referring now to the drawings, FIGS. 1-6 illustrate various views of a wearable computing device 100 according to the present disclosure and various controller components of an example system and various devices that can be utilized with such wearable computing device 100. In particular, as shown in FIG. 1, the wearable computing device 100 may be worn on a user’s forearm 102 like a wristwatch. Thus, as shown, the wearable computing device 100 may include a wristband 104 having one or more parts, such as two wristband straps 106, 108, for securing the wearable computing device 100 to the user’s forearm 102. However, it should be appreciated that the wearable computing device 100 may be worn at any other suitable location by a user, such as, for example, on an ankle.

[0025] In addition, as shown in FIGS. 1-3 and 6, the wearable computing device 100 has a housing 110 that contains the electronics associated with the wearable computing device 100. The housing 110 has an upper side having a top surface 112 including an electronic display 114 and an outer covering 116. For example, in an embodiment, the outer covering 116 may be constructed of glass, polycarbonate, acrylic, or similar. The electronic display 114 may be arranged within the housing 110 and viewable through the outer covering 116. Moreover, in an embodiment, the electronic display 114 may cover an electronics package (not shown), which may also be housed within the housing 110. Additionally, the wearable computing device 100 may also include one or more buttons 118 (FIG. 3), such as on a perimeter 120 of the housing 110, that may be implemented to provide a mechanism to activate various sensors of the wearable computing device 100 to collect certain health data of the user and / or for a user to otherwise interact with the wearable computing device 100.

[0026] Referring particularly to FIGS. 1 and 2, the housing 110 of the wearable computing device 100 further includes a dorsal wrist-side face 122 (alternatively referred to herein as “bottom surface 122”) configured to be closest to a user when worn. For instance, the bottom surface 122 of the housing 110 may sit against a dorsal wrist of a user when being worn by the user. As particularly shown in FIG. 3, the perimeter 120 of the housing 110 of thewearable computing device 100 generally extends between the top surface 112 and the bottom surface 122 of the housing 110. In some instances, the wristband straps 106, 108 may be attached to the housing 110 on the perimeter 120.

[0027] One or more dry electrodes 124 may be positioned on the top surface 112 and / or the bottom surface 122 of the housing 110 so as to allow the user to have skin contact with the dry electrodes in at least two body locations, e.g., when the wearable computing device 100 is worn by the user. More specifically, in an embodiment, the wearable computing device 100 may include one or more first dry electrodes 125 (FIG. 1) arranged at a first location on the wearable computing device 100 and one or more second dry electrodes 127 (FIG. 2) arranged at a different, second location on the wearable computing device 100. For example, as shown, the first location corresponds to the top surface 112 of the wearable computing device 1000 and the second location corresponds to the bottom surface 122 of the wearable computing device 100. More specifically, in an embodiment, as shown in FIGS. 1 and 2, the wearable computing device 100 may include at least four dry electrodes 124, with at least two of the first dry electrodes 125 arranged on the top surface 112 of the wearable computing device 100 and at least two of second dry electrodes 127 arranged on the bottom surface 122 of the wearable computing device 100. In further embodiments, it should be understood that the top surface of the wearable computing device 100 may include the top surface 112 of the electronic display 114 (as shown in FIG. 1), as well as a top surface of one or more of the wristband straps 106, 108 of the wearable computing device 100. Moreover, in an embodiment, a shape of the first dry electrode(s) 125 and / or the second dry electrode(s) 127 may conform to a shape of the electronic display 114 or the housing 110 of the wearable computing device 100.

[0028] Thus, in such embodiments, each of the dry electrodes 124 may be configurable to measure, at least, an impedance cardiography (ICG) signal of the user at a location of the skin contact. Accordingly, in one or more embodiments, one or more (or all) of the plurality of dry electrodes 124 may be impedance sensor electrodes. As used herein, ICG generally refers to a non-invasive technology measuring total electrical conductivity of the thorax and its changes in time to process continuously a number of cardio dynamic parameters, such as stroke volume (SV), heart rate (HR), cardiac output (CO), ventricular ejection time (VET), pre-ejection period. As such, ICG can be used to detect the impedance changes caused by a high-frequency, low magnitude current flowing through the thorax between two pairs of electrodes located outside of the measured segment.

[0029] Further, the dry electrodes 124 described herein may be constructed of any suitablematerial. For example, in an embodiment, the dry electrodes 124 described herein may be constructed of stainless steel, graphene, or any other material having a suitable conductivity and / or corrosion resistance and may have an optional PVD coating, that may be 1 -micrometer thick titanium nitride. In such embodiments, the PVD coating may provide a desired color to the dry electrodes 124, thereby preventing oxidation beyond what the stainless steel already provides, and also increases durability. In additional embodiments, PVD and surface finish can be used to increase / decrease moisture retention, which affects the impedance signal and user comfort. In particular embodiments, the dry electrodes 124 may be formed of an alloy of tin and nickel (TiN) with a shiny or mirror surface finish. Moreover, in an embodiment, the dry electrodes 124 may be constructed of a hydrophobic material or a transparent material.

[0030] In some embodiments, the wearable computing device 100 may also include at least one additional biometric sensor electrode in addition to the impedance dry electrodes 124. In such embodiments, the additional biometric sensor electrode may include one or more temperature sensors (such as an ambient temperature sensor or a skin temperature sensor), a humidity sensor, a pressure sensor, a microphone, an optical sensor (e.g., a lights sensor such as a photoplethysmography (PPG) sensor), and / or the like. For instance, the wearable computing device 100 is illustrated as including multiple detectors 126 for detecting light. Moreover, the wearable computing device 100 is illustrated as including multiple light sources or emitters 128 (e.g., light-emitting diodes (LEDs)) for emitting light. The detectors 126 may be used alone and be used to detect ambient light (light not emitted from the wearable computing device 100) or may be used in combination with the emitters 128 such that the detectors 126 detect both ambient light and light from the emitters 128. Use of emitters 128 may particularly be useful in dark environments, where there is little ambient light.

[0031] The detectors 126 and emitters 128 may be arranged within the housing 110 and at least partially exposed through the bottom surface 122 of the housing 110. The dry electrodes 124 may be positioned around the detectors 126 and emitters 128 on the bottom surface 122 of the housing 110. In alternative embodiments, the detectors 126 and emitters 128 may be positioned around the dry electrodes 124 and / or in another other suitable configuration such as adjacent to, interspersed with, surrounded by, or below the dry electrodes 124. For example, in embodiments where the dry electrodes 124 are transparent, the dry electrodes 124 may be arranged atop the detectors 126 and emitters 128.

[0032] Referring now to FIG. 4, components of an example system 150 that can be utilizedwith the wearable computing device 100 in accordance with various embodiments are illustrated. In particular, as shown, the system 150 may also include at least one controller 152. In an embodiment, the controlled s) 152 may be a central processing unit (CPU) or graphics processing unit (GPU) for executing instructions that can be stored in a memory device 154, such as flash memory or DRAM, among other such options. For example, in an embodiment, the memory device 154 may include RAM, ROM, FLASH memory, or other non-transitory digital data storage, and may include a control program comprising sequences of instructions which, when loaded from the memory device 154 and executed using the controlled s) 152, cause the controlled s) 152 to perform the functions that are described herein. As would be apparent to one of ordinary skill in the art, the system 150 can include many types of memory, data storage, or computer-readable media, such as data storage for program instructions for execution by the controller or any suitable processor. The same or separate storage can be used for images or data, a removable memory can be available for sharing information with other devices, and any number of communication approaches can be available for sharing with other devices.

[0033] The system 150 also includes one or more power components 156, such as may include a battery operable to be recharged through conventional plug-in approaches, or through other approaches such as capacitive charging through proximity with a power mat or other such device.

[0034] In addition, as shown, the system 150 includes any suitable user interface elements in communication with the controller 152, such as the electronic display 114 of the wearable computing device 100. The electronic display 114 may be any suitable display type, such as a touch screen, organic light emitting diode (OLED), liquid crystal display (LCD), and / or the like. In further embodiments, the system 150 can also include at least one additional I / O device 158 configured to allow the controller 152 to receive conventional inputs from a user. These conventional inputs can include, for example, a push button (e.g., button 118 in FIG. 3), touch pad, touch screen, wheel joystick, keyboard, mouse, keypad, and / or any other such device or element whereby a user can input a command to the system 150. In another embodiment, the EO device(s) 158 may be connected by a wireless infrared or Bluetooth or other link as well in some embodiments. In some embodiments, the EO device(s) 158 may additionally, or alternatively, include a microphone or other audio capture element that accepts voice or other audio commands. For example, in particular embodiments, the system 150 may not include any buttons, but might be controlled only through a combination of visual and audio commands, such that a user can control the wearable computing device 100without having to be in contact therewith. In certain embodiments, the I / O elements 158 may also include one or more of the dry electrodes 124 described herein, optical sensors, barometric sensors (e.g., altimeter, etc.), and the like.

[0035] The system 150 may also include one or more wireless components 160 operable to allow the controller 152 to communicate with one or more electronic devices within a communication range of the particular wireless channel. The wireless channel can be any appropriate channel used to enable devices to communicate wirelessly, such as Bluetooth, cellular, NFC, Ultra-Wideband (UWB), or Wi-Fi channels. It should be understood that the system 150 can have one or more conventional wired communications connections as known in the art.

[0036] Still referring to FIG. 4, the system 150 may also include an optics package 130, where the optics package 130 at least includes a plurality of the detectors 126 and, optionally includes one or more emitters 128. In an embodiment, the detectors 126 and optional emitters 128 may be coupled to the controller 152 directly or indirectly using driver circuitry 162 by which the controller 152 may drive the emitters 128 and obtain signals from the detectors 126.

[0037] Moreover, the system 150 may include one or more internal motion sensors 164 (e.g., accelerometers, gyroscopes, and / or the like) inside the housing 110 and configured to generate motion data indicative of movement of the wearable computing device 100, with the motion sensors 164 being in communication with the controller 152.

[0038] A host computer 168 can communicate with the wireless networking components 160 via one or more networks 166, which may include one or more local area networks, wide area networks, UWB, and / or internetworks using any of terrestrial or satellite links. In some embodiments, the host computer 168 executes control programs and / or application programs that are configured to perform some of the functions described herein.

[0039] Referring now to FIG. 5, a schematic diagram of an environment 170 in which aspects of various embodiments can be implemented is illustrated. In particular, as shown, a user might have a number of different devices that are able to communicate using at least one wireless communication protocol. For example, as shown, the user might have a wearable computing device, such as a smartwatch or fitness tracker (e.g., the wearable computing device 100), which the user would like to be able to communicate with other devices, such as a smartphone 172, a tablet computer 174, and / or the like. As used herein, the wearable computing device 100 may be a watch, a phone, a headset, a chest strap, a ring, an earbud, or the like.

[0040] Applications may allow communication between multiple devices and a wearable computing device to enable a user to obtain information from the wearable computing device 100. For example, data captured using a sensor of the wearable computing device 100 may be communicated to the smartphone 172 and / or the tablet computer 174 using an application installed on the smartphone 172 and / or the tablet computer 174. The user may also want the wearable computing device 100 to be able to communicate with a service provider 171, or other such entity, that is able to obtain and process data from the wearable computing device 100 and provide functionality that may not otherwise be available on the wearable computing device 100 or applications installed on the other devices. In addition, as shown, the wearable computing device 100 may be able to communicate with the service provider (e.g., the service provider 171 of the service provider) through at least one network (e.g., the network 166), such as the Internet or a cellular network, or may communicate over a wireless connection such as Bluetooth® to the other device(s) (e.g., the smartphone 172 and / or the tablet computer 174), where the other device(s) then communicate with the service provider over the at least one network. There may be a number of other types of, or reasons for, communications in various embodiments.

[0041] In addition to being able to communicate, a user may also want the devices to be able to communicate in a number of ways or with certain aspects. For example, the user may want communications between the devices to be secure, particularly where the data may include personal health data or other such communications. The device or application providers may also be required to secure this information in at least some situations. The user may want the devices to be able to communicate with each other concurrently, rather than sequentially. This may be particularly true where pairing may be required, as the user may prefer that each device be paired at most once, such that no manual pairing is required. The user may also desire the communications to be as standards-based as possible, not only so that little manual intervention is required on the part of the user but also so that the devices can communicate with as many other types of devices as possible, which is often not the case for various proprietary formats.

[0042] A user may thus desire to be able to walk in a room with one device and have such device automatically communicate with another target device with little to no effort on the part of the user. In various conventional approaches, a device will utilize a communication technology such as Wi-Fi to communicate with other devices using wireless local area networking (WLAN). Smaller or lower capacity devices, such as many Internet of Things (loT) devices, instead utilize a communication technology such as Bluetooth®, and inparticular Bluetooth Low Energy (BLE) which has very low power consumption.

[0043] In further embodiments, the environment 170 illustrated in FIG. 5 enables data to be captured, processed, and displayed in a number of different ways. For example, data may be captured using sensors on the wearable computing device 100, but due to limited resources on the wearable computing device 100, the data may be transferred to the smartphone 172, the tablet computer 174, and / or the service provider 171 (or a cloud resource) for processing, and results of that processing may then be presented back to that user on the wearable computing device 100, smartphone 172, the tablet computer 174 and / or another such device associated with that user.

[0044] Referring now to FIG. 6, a flow diagram of one embodiment of a method 200 of acquiring an impedance cardiography (ICG) signal from a user of a wearable computing device is provided according to the present disclosure. In an embodiment, for example, the wearable computing device may be any suitable wearable computing device, such as the wearable computing device 100 described herein with reference to FIGS. 1-5. Thus, in general, the method 200 is described herein with reference to the wearable computing device 100 of FIGS. 1-5. However, it should be appreciated that the disclosed method 200 may be implemented with any other suitable wearable computing device having any other suitable configurations and with any other suitable proximity data. In addition, although FIG. 6 depict steps performed in a particular order for purposes of illustration and discussion, the methods discussed herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods disclosed herein can be omitted, rearranged, combined, added, and / or adapted in various ways without deviating from the scope of the present disclosure.

[0045] As shown at (202), the method 200 may optionally include placing the wearable computing device 100 on a wrist of the user such that the bottom surface 122 of the wearable computing device corresponds to a wrist-side of the wearable computing device 100. As shown at (204), the method 200 may optionally include receiving, via the processor(s) of the wearable computing device 100, an input from the user to initiate receiving of the impedance cardiography data. As shown at (206), the method 200 includes receiving, from the one or more dry electrodes 124 on the wearable computing device 100, impedance cardiography data for a given time period. In an embodiment, for example, the impedance cardiography data is representative of thoracic and peripheral impedance changes of the user.

[0046] As shown at (208), the method 200 includes processing, via at least one processor of the wearable computing device 100, the impedance cardiography data to obtain theimpedance cardiography signal. Further, in an embodiment, as shown at (210), the method 200 may optionally include evaluating, via the processor(s) of the wearable computing device 100, cardiovascular health of the user using the impedance cardiography signal. In such embodiments, for example, the cardiovascular health of the user may generally include mechanical heart health of the user, peripheral vascular health of the user, left ventricular ejection time, and / or cardiac output. More specifically, in an embodiment, evaluating the cardiovascular health of the user using the impedance cardiography signal may include generating a cardiovascular score relating to the cardiovascular health of the user and / or notifying the user about changes in the impedance cardiography signal above a baseline threshold, e.g. that may be based on historical data of the user.

[0047] In additional embodiments, the method 200 may include placing first and second body locations of the user in contact with the one or more first and second dry electrodes 125, 127 of the wearable computing device 100. In particular embodiments, for example, the first and second body locations may include any of a wrist, one or more fingers, a hand, an arm, a chest, a leg, a foot, or a head of the user. More specifically, in an embodiment, the first body location may include one or more fingers and the second body location may include the wrist of the user. Thus, in such embodiments, one of the first dry electrode(s) 125 or the second dry electrode(s) 127 injects current into the first body location or the second body location and the other of the first dry electrode(s) 125 or the second dry electrode(s) 127 measures impedance from the other of the first body location or the second body location. In another embodiment, the method 200 may include utilizing one or more additional sensed parameters from one or more additional sensors of the wearable computing device 100 (such as PPG sensors, electrocardiography (ECG) sensors, and / or any of the biometric sensor electrodes described herein, etc.) combined with the impedance cardiography signal to determine one or more cardiac metrics.

[0048] Referring still to FIG. 6, as shown at (212), the method 200 includes displaying, via the electronic display 114 of the wearable computing device 100, the impedance cardiography signal as well as the cardiovascular health (and / or the cardiovascular score, changes in the ICG signal, etc.) to the user.

[0049] The technology discussed herein makes reference to servers, databases, software applications, and other computer-based systems, as well as actions taken, and information sent to and from such systems. The inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components. For instance, processes discussed herein canbe implemented using a single device or component or multiple devices or components working in combination. Databases and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0050] While the present subject matter has been described in detail with respect to various specific example embodiments thereof, each example is provided by way of explanation, not limitation of the disclosure. Those skilled in the art, upon attaining an understanding of the foregoing, can readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the subject disclosure does not preclude inclusion of such modifications, variations and / or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such alterations, variations, and equivalents.

Claims

WHAT IS CLAIMED IS:

1. A method of acquiring an impedance cardiography signal from a user of a wearable computing device, the method comprising: receiving, from one or more dry electrodes on the wearable computing device, impedance cardiography data for a given time period, the impedance cardiography data being representative of thoracic and peripheral impedance changes of the user; processing, via at least one processor of the wearable computing device, the impedance cardiography data to obtain the impedance cardiography signal; and displaying, via an electronic display of the wearable computing device, the impedance cardiography signal to the user.

2. The method of claim 1, further comprising: evaluating, via the at least one processor of the wearable computing device, cardiovascular health of the user using the impedance cardiography signal; and displaying, via the electronic display of the wearable computing device, the evaluation to the user.

3. The method of claim 2, wherein evaluating the cardiovascular health of the user using the impedance cardiography signal further comprises at least one of generating a cardiovascular score relating to the cardiovascular health of the user or notifying the user about changes in the impedance cardiography signal above a baseline threshold.

4. The method of claim 2, wherein the cardiovascular health of the user comprises at least one of mechanical heart health of the user, peripheral vascular health of the user, left ventricular ejection time, or cardiac output.

5. The method of claim 1, wherein the one or more dry electrodes comprise a plurality of dry electrodes.

6. The method of claim 5, wherein the plurality of dry electrodes comprises one or more first dry electrodes arranged at a first location on the wearable computing device and one or more second dry electrodes arranged at a different, second location on the wearable computing device.

7. The method of claim 6, wherein the first location comprises a top or side surface of the wearable computing device and the second location comprises a bottom surface of the wearable computing device.

8. The method of claim 7, wherein the top or side surface of the wearable computing device comprises at least one of a top or side surface of the electronic display or a top or side surface of a band of the wearable computing device.

9. The method of claim 7, further comprising placing the wearable computing device on a wrist of the user such that the bottom surface of the wearable computing device corresponds to a wrist-side of the wearable computing device.

10. The method of claim 9, further comprising receiving, via the at least one processor of the wearable computing device, an input from the user to initiate receiving of the impedance cardiography data.

11. The method of claim 7, wherein the plurality of dry electrodes comprises at least four dry electrodes, and wherein at least two of the one or more first dry electrodes are arranged on the top or side surface of the wearable computing device and at least two of the one or more second dry electrodes are arranged on the bottom surface of the wearable computing device.

12. The method of claim 6, further comprising placing first and second body locations of the user in contact with the one or more first and second dry electrodes of the wearable computing device.

13. The method of claim 12, wherein one of the one or more first dry electrodes or the one or more second dry electrodes injects current into one of the first body location or the second body location and the other of the one or more first dry electrodes or the one or more second dry electrodes measures impedance from one of the first body location or the second body location.

14. The method of claim 13, wherein the first and second body locations comprise at least one of a wrist, one or more fingers, a hand, an arm, a chest, a leg, a foot, or a head of the user.

15. The method of claim 14, wherein the first body location comprises the one or more fingers and the second body location comprises the wrist of the user.

16. The method of claim 6, wherein a shape of at least one of the one or more first dry electrodes or the one or more second dry electrodes conforms to a shape of at least one of the electronic display or a housing of the wearable computing device.

17. The method of claim 1, further comprising utilizing one or more additional sensed parameters from one or more additional sensors of the wearable computing device combined with the impedance cardiography signal to determine one or more cardiac metrics.

18. The method of claim 1, wherein the wearable computing device comprises at least one of a watch, a phone, a headset, a chest strap, a ring, or an earbud.

19. A wearable computing device, comprising: an electronic display;one or more dry electrodes; and one or more processors configured to perform a plurality of operations, the plurality of operations comprising: receiving, from the one or more dry electrodes, impedance cardiography data for a given time period, the impedance cardiography data being representative of thoracic and peripheral impedance changes of a user of the wearable computing device; processing the impedance cardiography data to obtain an impedance cardiography signal; and displaying, via the electronic display, the impedance cardiography signal to the user.

20. The wearable computing device of claim 19, wherein the plurality of operations further comprise: evaluating, via the one or more processors of the wearable computing device, cardiovascular health of the user using the impedance cardiography signal; and displaying, via the electronic display of the wearable computing device, the evaluation to the user.

21. The wearable computing device of claim 20, wherein evaluating the cardiovascular health of the user using the impedance cardiography signal further comprises at least one of generating a cardiovascular score relating to the cardiovascular health of the user or notifying the user about changes in the impedance cardiography signal above a baseline threshold.

22. The wearable computing device of claim 20, wherein the cardiovascular health of the user comprises at least one of mechanical heart health of the user, peripheral vascular health of the user, left ventricular ejection time, or cardiac output.

23. The wearable computing device of claim 19, wherein the one or more dry electrodes comprise a plurality of dry electrodes.

24. The wearable computing device of claim 23, wherein the plurality of dry electrodes comprises one or more first dry electrodes arranged at a first location on the wearable computing device and one or more second dry electrodes arranged at a different, second location on the wearable computing device.

25. The wearable computing device of claim 24, wherein the first location comprises a top or side surface of the wearable computing device and the second location comprises a bottom surface of the wearable computing device.

26. The wearable computing device of claim 25, wherein the top or side surface of the wearable computing device comprises at least one of a top or side surface of the electronic display or a top or side surface of a band of the wearable computing device.

27. The wearable computing device of claim 25, further comprising placing the wearable computing device on a wrist of the user such that the bottom surface of the wearable computing device corresponds to a wrist-side of the wearable computing device.

28. The wearable computing device of claim 19, further comprising receiving, via the one or more processors, the wearable computing device, an input from the user to initiate receiving of the impedance cardiography data.

29. The wearable computing device of claim 25, wherein the plurality of dry electrodes comprises at least four dry electrodes, and wherein at least two of the one or more first dry electrodes are arranged on the top or side surface of the wearable computing device and at least two of the one or more second dry electrodes are arranged on the bottom surface of the wearable computing device.

30. The wearable computing device of claim 24, further comprising placing first and second body locations of the user in contact with the one or more first and second dry electrodes of the wearable computing device.

31. The wearable computing device of claim 30, wherein one of the one or more first dry electrodes or the one or more second dry electrodes injects current into one of the first body location or the second body location and the other of the one or more first dry electrodes or the one or more second dry electrodes measures impedance from one of the first body location or the second body location.

32. The wearable computing device of claim 31, wherein the first and second body locations comprise at least one of a wrist, one or more fingers, a hand, an arm, a chest, a leg, a foot, or a head of the user.

33. The wearable computing device of claim 32, wherein the first body location comprises the one or more fingers and the second body location comprises the wrist of the user.

34. The wearable computing device of claim 24, wherein a shape of at least one of the one or more first dry electrodes or the one or more second dry electrodes conforms to a shape of at least one of the electronic display or a housing of the wearable computing device.

35. The wearable computing device of claim 19, wherein the plurality of operations further comprise utilizing one or more additional sensed parameters from one or more additional sensors of the wearable computing device combined with the impedancecardiography signal to determine one or more cardiac metrics.

36. The wearable computing device of claim 19, wherein the wearable computing device comprises at least one of a watch, a phone, a headset, a chest strap, a ring, or an earbud.

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