CN118177774A - Respiratory Measurement System - Google Patents

Abstract

The present disclosure provides a respiratory measurement system. The present embodiments relate to a wearable device that may include a housing; a touch sensitive display coupled to the housing; a strap coupled to the housing and configured to secure the housing to a user; and a plurality of electrodes that contact the user when the user wears the wearable device. The wearable device may be configured to: causing the plurality of electrodes to apply an electrical signal to the user; measuring the electrical signals from the user using the plurality of electrodes; generating a set of impedance data from the measured electrical signals; and using the set of impedance data to identify one or more respiratory cycles.

Description

Respiratory Measurement System

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application of U.S. Provisional Patent Application No. 63/432,293, entitled “Respiratory Measurement System,” filed on December 13, 2022, and claims the benefit of the U.S. Provisional Patent Application under 35 U.S.C. §119(e), the contents of which are incorporated herein by reference as if fully disclosed herein.

Technical Field

The described embodiments relate generally to systems and methods for monitoring respiratory parameters of a user, and more particularly to systems and methods for determining a user's respiratory rate using impedance-based measurements.

Background technique

Wearable electronic devices are increasingly incorporating sensing systems that measure physiological parameters of a user. Depending on the physiological parameter being measured and the desired sensing modality for making the measurement, certain sensing locations are more conducive to obtaining accurate and repeatable measurements. For example, a user's breathing rate can be more easily measured at the user's torso, which contracts and expands as the user breathes. Measuring breathing at a user's limbs (such as at the wrist) or at the user's head can be challenging because the movement of these parts of the body during breathing can be somewhat decoupled from the movement of the torso. Therefore, it is desirable to provide a wearable electronic device that can measure a user's breathing rate at various body parts.

Summary of the invention

The present embodiment is directed to a wearable device, comprising: a band configured to secure the wearable device to a user's wrist; and a plurality of electrodes positioned to contact the user when the band secures the wearable device to the user's wrist. The wearable device may include a processor configured to: cause the plurality of electrodes to apply electrical signals to the user; use the plurality of electrodes to measure the electrical signals from the user; generate a set of impedance data based on the measured electrical signals; and use the set of impedance data to identify one or more respiratory cycles.

The present embodiment also relates to a wearable device, comprising: electrodes, the electrodes are configured to apply one or more electrical signals to a user and sense the one or more electrical signals from the user. The wearable device may include a processor, the processor being configured to: use the electrodes to perform one or more first impedance measurements to determine a set of contact metrics; use the set of contact metrics to select a subset of the electrodes; use the subset of the electrodes to perform one or more second impedance measurements to generate a set of impedance data; and determine one or more breathing cycles of the user based on the set of impedance data.

The present embodiment also relates to a wearable sensing device for measuring a user's respiratory parameters, and the wearable sensing device includes: a set of electrodes, the set of electrodes is configured to apply an electrical signal to the user's body and sense the electrical signal from the body; and a motion sensor, the motion sensor is configured to measure the user's movement. The wearable sensing device may include a processor configured to use the measured movement to determine that the user's movement state meets the low movement standard. In response to determining that the movement state meets the low movement standard, the processor may use the set of electrodes to measure the user's impedance when the set of electrodes contacts the user; and determine the user's respiratory parameters based on the measured impedance.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, in which like reference numerals refer to like structural elements, and in which:

FIG1 illustrates a functional block diagram of an exemplary electronic device that may be used to perform impedance-based respiration measurement;

FIG2A illustrates an exemplary watch that may incorporate a sensing system as described herein;

FIG2B illustrates a rear view of the exemplary watch of FIG2A including a sensing system positioned on the housing of the watch;

FIG3 illustrates an exemplary process for performing impedance respiration measurements using an electronic device;

FIG4 shows a visual example of impedance data generated by a sensing system as described herein;

FIG5 illustrates an exemplary process for selecting electrodes and performing impedance respiration measurements using the selected electrodes as described herein;

FIG6 illustrates an exemplary process for using motion data to determine when to perform impedance respiration measurements; and

7 illustrates a block diagram of an exemplary electronic device that may incorporate a sensing assembly as described herein.

Detailed ways

Reference will now be made specifically to the representative embodiments shown in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to a preferred embodiment. On the contrary, it is intended to cover alternatives, modifications and equivalent forms that may be included in the essence and scope of the embodiments defined by the appended claims.

Embodiments disclosed herein relate to devices and techniques for determining physiological parameters of a user using impedance data. The device may include one or more electrodes positioned to contact the user and used to perform impedance measurements at a body part of the user. The device may generate impedance data based on the measurement results and process the impedance data to determine physiological parameters including respiratory parameters, cardiac parameters, or other parameters of the user. In some cases, the impedance measurement may detect changes in blood flow through a body part of the user (e.g., as a result of a cardiac cycle), and the impedance data may be analyzed to identify deviations in blood flow caused by the user's breathing. For example, the impedance measurement may capture pulsating fluctuations in blood flow and changes in pulsating blood flow caused by breathing. Analyzing the impedance data may include identifying pulsating characteristics of blood flow and identifying respiratory-induced deviations of the pulsating signal. The device and system may derive one or more respiratory parameters including respiratory rate, and display or otherwise output the parameters to the user.

The impedance measurement system described herein can be incorporated into various electronic devices including wearable devices. Some wearable devices may be configured to be releasably coupled to a user's limbs (e.g., an arm or leg of a user), and may include smart watches, bracelets, cuffs, finger rings, bands, etc. In some of these examples, the wearable device can be releasably fixed to the user's wrist to allow the device to measure the user's respiratory parameters at the wrist. In other examples, the exemplary wearable device may be configured to be releasably coupled to the user's head, and may include a head-mounted device, a headband, headphones, etc. The wearable device can be releasably fixed to the user in any suitable manner, such as via a strap or other fastener (e.g., a smart watch band), via an adhesive (e.g., an adhesive patch), incorporated into clothing, etc.

The electrodes may be positioned in a variety of configurations across one or more wearable devices. For example, in the case of a smartwatch, the electrodes may be positioned on the body of the watch, the band of the watch, and/or a combination thereof. Additionally or alternatively, the electrodes may be positioned on one or more other wearable devices such as an armband, a headband, a headset, an adhesive patch, or other wearable device. In some instances, the wearable device performing impedance may not include a display for presenting breathing parameters to the user. In these cases, the wearable device may transmit the impedance data (or calculated breathing parameters) to an additional device having a display.

In some cases, the electronic device may dynamically select a subset of electrodes for measuring respiratory parameters. In this way, different subsets may be selected in different instances in an effort to improve the accuracy of these measurements. For example, the electronic device may perform a first set of measurements ("contact impedance measurements") to evaluate the contact quality between different subsets of electrodes and the user's skin. The first set of measurements can be used to identify electrodes with sufficient (i.e., threshold level) contact quantity/quality with the user, and electrodes for performing a second set of measurements ("respiratory impedance measurements") are selected based on the measured contact impedance. In some cases, the same electrode may operate as a drive electrode for applying an electrical signal to the user and a sensing electrode for sensing the applied electrical signal from the user. In other cases, different electrodes may be used as drive electrodes and sensing electrodes. For example, impedance measurements may include applying a potential to the user via a pair of drive electrodes while measuring impedance using a pair of sensing electrodes.

The electronic device can use information from other sensors to determine when to initiate these measurements. For example, in some cases, the signal-to-noise ratio of the respiratory impedance measurement can be improved by measuring the impedance during the user's low motion state, which can reduce the noise associated with the user's movement. The electronic device may include a motion sensor that determines when the motion state of the device meets a specific standard (low motion condition) indicating that the electronic device is not moving in an undesirable manner. When the electronic device meets the low motion condition, the electronic device may initiate and perform contact impedance measurement and/or respiratory impedance measurement. Therefore, in some cases, the device may be configured to obtain the user's impedance data when the movement is low (this may be when the user is sleeping, sitting, or otherwise in a low motion state).

In some cases, the impedance data may be combined with other data collected from other sensors and analyzed together to determine one or more breathing parameters of the user. For example, the impedance data may be analyzed using electrocardiogram (ECG) data, photoplethysmography (PPG) data, motion data, or any other suitable physiological data. Respiratory parameters may be determined in a variety of ways and/or from multiple measurement sources. For example, an electronic device may collect a data set from each of a variety of different sensor types. In some instances, an electronic device may derive a respiratory rate from only one sensor type and its associated data set at any given time. For example, a physiological parameter may be derived from a sensing modality, and its associated data set may be selected based on a confidence metric associated with each data set in the data set. In other cases, a physiological parameter may be derived from a combination of sensing modalities such as a weighted average of the respiratory rates of two or more data sets from different data sets.

These and other embodiments are discussed below with reference to Figures 1 to 7. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for illustrative purposes only and should not be construed as limiting.

FIG1 shows a functional block diagram of an exemplary electronic device 100 that can be used to perform impedance-based respiration measurement as described herein. The electronic device 100 may include an impedance sensor 104, which may include one or more electrodes 106 that contact the user 101. The electronic device 100 may also include other sensors 110, a controller 112, a processor 114, and a user interface 116. The electronic device 100 may include a housing 102, and one or more of the impedance sensor 104, the other sensors 110, the controller 112, and the processor 114, and the user interface may be at least partially positioned within the housing 102.

The impedance sensor 104 may include electrodes 106 that may be controlled to apply one or more electrical signals to the user 101 and/or sense electrical signals after they have interacted with the user 101. In some cases, the first electrode 106a (or a set of electrodes) may operate as a drive electrode that applies one or more electrical signals 108a to the user 101, and the second electrode 106b (or a set of electrodes) may operate as a sensing electrode that measures the one or more electrical signals 108b that have been applied to the user 101. The processor 114 may determine one or more respiration parameters based on impedance data generated by the controller 112 based on the applied and sensed electrical signals 108. For example, the applied electrical signal 108a may be offset or otherwise changed by blood flow through the body of the user 101. The controller 112 may use the applied electrical signal 108a and the sensed electrical signal 108b to generate impedance data, and the processor 114 may use the impedance data to determine a respiration metric of the user, as described herein.

In some cases, the controller 112 may operate one or more electrodes 106 to act as a driving electrode and a sensing electrode. In these cases, the same electrode may apply an electrical signal 108a to the user and measure an electrical signal 108b returned from the user 101. In other cases, the impedance sensor 104 may use one or more first electrodes 106a (one of which is marked for clarity) as a driving electrode and one or more second electrodes 106b (one of which is marked for clarity) as a sensing electrode. The controller 112 may be configured to select the driving electrode and the sensing electrode 106. In some cases, the controller 112 may select the driving electrode and the sensing electrode 106 by analyzing the electrical signal transmitted and/or sensed by the electrode 106. For example, the controller 112 may perform a contact impedance measurement for one or more of the electrodes 106, which may be used to determine the electrodes for additional respiratory impedance measurement to determine the user's physiological parameters.

The impedance sensor 104 and/or the controller 112 may include circuitry that connects the different electrodes to the measurement circuitry for measuring impedance. For example, the impedance sensor 104 and/or the controller 112 may include a multiplexer or other suitable electronic components that connect selected electrodes to the drive circuitry for generating the applied electrical signal and the sensing circuitry for measuring impedance.

The electrical signal applied by the impedance sensor 104 may travel into the user's body via direct or indirect contact of the electrodes 106 with the user 101. The electrical signal may interact with the user 101, which may include a portion of the electrical signal being absorbed by the user's tissue (e.g., skin, blood, blood vessels, muscles, etc.) and/or being modified by interaction with the user's tissue, and a portion of the electrical signal may return to the impedance sensor 104, where they may be sensed by one or more electrodes 106. The drive circuit system may apply a constant or time-varying voltage to the tissue, which generates a current between the drive electrodes. The amount of current depends on the impedance of the tissue between the electrodes, and the drive circuit system measures the current to determine the impedance between the same electrodes. In some cases, the system may include dedicated sensing electrodes and a sensing circuit system that measures the current to determine the impedance.

The sensed electrical signal may represent the waveform of the returned electrical signal 108b. The measured impedance may include a pulsatile component due to interaction with blood flow in the user 101 and/or a non-pulsatile component due to interaction with other tissues. The processor 114 may determine the amplitude, phase, modulation, etc. of the pulsatile component and/or the non-pulsatile component of the sensed electrical signal, and determine the respiratory parameter based on the amplitude, phase, modulation, etc.

Sensor 110 may include other types of sensors for determining one or more parameters of a user. The sensor may include a motion sensor such as an inertial measurement unit (IMU), a light-based sensor such as a PPG sensor, a temperature sensor, an ECG sensor, and/or any other suitable sensor. Sensor 110 may operate in conjunction with impedance sensor 104. For example, controller 112 and/or processor 114 may use data from sensor 110 to determine when to initiate impedance measurement. For example, a motion sensor may be used to identify a low motion state of user 101, and controller 112 may initiate impedance measurement at impedance sensor 104 in response to identifying a low motion state of user 101. In other cases, controller 112 and/or processor 114 may use data from sensor 110 to supplement impedance data or as an alternative to impedance data, as described herein.

The controller 112 can be operably coupled to the processor 114, the impedance sensor 104, and the other sensors 110. In some cases, all or part of the controller 112 can be implemented as a computer executable code executed on the processor 114. In some cases, all or part of the controller 112 can include or be implemented by dedicated hardware, including hardware for selectively operating the electrodes in a drive mode and/or a sensor mode. In some cases, the controller 112 may include a dedicated processing unit for performing one or more functions of the impedance sensor 104 or other sensors 110, as described herein.

The user interface 116 may include a display, a touch-sensitive display, a speaker, a microphone, a haptic engine, or any other suitable input/output device. The user interface may include components located within the interior of the electronic device 100, components partially located within the housing of the electronic device 100 (e.g., a display), and/or components that are separate from the electronic device 100 and operably coupled to the electronic device (e.g., a headset).

The electronic device 100 may include additional and/or alternative components not shown in FIG. 1 . For example, the electronic device 100 may include input devices, output devices, memory, a power source, and/or electrical connectors that operably couple components of the electronic device 100. Exemplary components of the wearable electronic device 100 are discussed in more detail with respect to FIG. 7 . Exemplary electronic devices may include smart phones, tablet computers, portable music players, or other portable electronic devices; wearable electronic devices as described herein include smart watches (e.g., as described with reference to FIGS. 2A and 2B ).

FIG. 2A shows an exemplary watch 200 that can be combined with a sensing system as described herein. The watch 200 can be an electronic watch including a smart watch that can be combined with an impedance sensing system and/or other sensing systems as described herein. The watch 200 can include a watch body 206 and a watch band 207. Other devices that can be combined with the crown assembly include other wearable electronic devices, other timing devices, other health monitoring or fitness devices, other portable computing devices, mobile phones (including smart phones), tablet computing devices, digital media players, etc. The watch 200 can have components, structures and/or functions similar to the wearable electronic device 100 described with respect to FIG. 1. The watch 200 can provide time and timing functions, receive messages and alarms, and can track the user's activities. In some cases, the watch can monitor the user's biological conditions or characteristics.

The watch body 206 may include a housing 202. The housing 202 may include a front housing member that faces away from the user's skin when the user wears the watch 200, and a rear housing member that faces the user's skin. Alternatively, the housing 202 may include a single housing member or more than two housing members. One or more housing members may be metal, plastic, ceramic, glass, or other types of housing members (or combinations of these materials).

The housing 202 may include a cover 202a that is mounted to form the front side of the watch body 206 (i.e., away from the user's skin) and may protect a display 204 mounted within the housing 202. The display 204 may generate a graphical output that the user can see through the cover 202a. In some cases, the cover 202a may be part of a display stack that may include touch sensing or force sensing capabilities. The display may be configured to depict a graphical output of the watch 200, and the user may interact with the graphical output (e.g., using a finger, stylus, or other pointer). As an example, the user may select a graphic, icon, etc. presented on the display (or otherwise interact with it) by touching or pressing (e.g., providing touch input) a graphical location on the cover 202a. As used herein, the term "cover" may be used to refer to any transparent, translucent, or semi-transparent surface made of glass, crystalline materials (such as sapphire or zirconium oxide), plastic, etc. Therefore, it should be understood that the term "cover" as used herein includes amorphous solids as well as crystalline solids. The cover 202a may form a portion of the housing 202. In some examples, the cover 202a may be a sapphire cover. The cover 202a may also be formed of glass, plastic, or other materials.

Watch 200 may include one or more input devices (e.g., crown 203, button 209, scroll wheel, knob, dial, etc.). The input device may be used to provide input to watch 200. Crown 203 and/or button 209 may be positioned along a portion of housing 202, such as along a sidewall of the housing, as shown in FIG2. In some cases, housing 202 defines an opening through which a portion of crown 203 and/or button 209 extends.

Crown 203 may be user-rotatable and may be manipulated (e.g., rotated, pressed) by the user. As an example, crown 203 and/or button 209 may be mechanically, electrically, magnetically, and/or optically coupled to components within housing 202. User manipulation of crown 203 and/or button 209 may in turn be used to manipulate or select various elements displayed on a display, adjust the volume of a speaker, turn watch 200 on or off, and the like.

In some embodiments, the button 209, crown 203, scroll wheel, knob, dial, etc. can be touch-sensitive, conductive and/or have a conductive surface, and a signal path can be provided between the conductive portion and the circuitry within the watch body 206 (such as a processing unit).

The housing 202 may include structure for attaching the strap 207 to the watch body 206. In some cases, the structure may include an elongated recess or opening through which the ends of the strap 207 may be inserted and attached to the watch body 206. In other cases (not shown), the structure may include indentations (e.g., pits or depressions) in the housing 202 that may receive the ends of spring pins that attach to or pass through the ends of the strap to attach the strap to the watch body. The strap 207 may be used to secure the watch 200 to a user, another device, a retaining mechanism, etc.

In some examples, the watch 200 may lack any or all of the cover 202a, the display 204, the button 209, or the crown 203. For example, the watch 200 may include an audio input or output interface, a touch input interface, a force input or tactile output interface, or other input or output interfaces that do not require the display 204, the button 209, or the crown 203. In addition to the display 204, the button 209, or the crown 203, the watch 200 may also include the aforementioned input or output interfaces. When the watch 200 does not have a display, the front side of the watch 200 may be covered by the cover 202a or covered by a metal or other type of housing member.

The watch 200 may include an impedance sensing system including an impedance sensor (e.g., impedance sensor 104) and a controller (e.g., controller 112), as described herein. The impedance sensor may include one or more sets of electrodes positioned at different locations of the watch 200. For example, a first set 210a of electrodes may be positioned on a band 207 of the electronic device 100. In some cases, multiple sets of electrodes may be positioned at different locations on the band, although one set is shown for simplicity. In other cases, one or more sets of electrodes may include electrodes dispersed across a larger area of the band.

In some cases, the sensing systems described herein (e.g., impedance sensor 104, controller 112, other sensors 110, etc.) and other components of the electronic device (e.g., processor 114, user interface 116, etc.) may be incorporated into other wearable electronic devices. For example, a wearable electronic device may include a band that is attached to/wrapped around a limb of a user and may not include watch components (e.g., housing, display, crown, and/or other input buttons). For example, a band may include sensing system components and/or other components integrated into the band structure.

In other cases, the sensing system and/or other components may be integrated into other wearable devices such as head-mounted devices, as described herein. The band, head-mounted device, or other device may or may not include a dedicated user interface. For example, a wearable device such as a band may be configured to transmit impedance measurements and/or impedance data to another device such as a smart phone, smart watch, tablet, or computer, which may output impedance data and/or determined physiological parameters to the user. In other cases, the wearable device may include a dedicated user interface that may display output, receive input, include a speaker and/or microphone, include a tactile device, and the like. These dedicated user interfaces may be configured to provide outputs and/or receive inputs that are primarily related to physiological measurements (e.g., impedance measurements) being performed by the wearable device.

FIG. 2B shows a rear view of the exemplary watch 200 of FIG. 2A . As shown in FIG. 2B , the watch body 206 defines the rear outer surface of the watch 200. In some cases, one or more sets of electrodes may be positioned on the watch body 206. For example, a second set 210 b of electrodes may be positioned along the rear side of the watch body 206. In the case where different electrodes are positioned along different portions of the device (e.g., along the housing and the band), a subset of electrodes may be selected to include electrodes from different portions of the device. The electrodes may be used to measure the impedance of the user, as described herein. The electrodes may be used to determine other biological parameters such as heart rate, electrocardiogram, etc. In some cases, the electrodes are used in conjunction with one or more additional electrodes (such as the surface of a crown assembly or other input device).

3 shows an exemplary process 300 for performing impedance respiration measurement using an electronic device. The process 300 may be performed by electronic devices described herein, including the electronic device 100 and the watch 200.

At operation 302, process 300 may include applying one or more electrical signals to the user. The electrical signals may be applied by one or more electrodes and applied to one or more parts of the user's body, as described herein. For example, in some embodiments, the electrical signals may be applied to the user's wrist (e.g., via a watch), and in other embodiments, the electrical signals may be applied to the user's head (e.g., via a head-mounted device such as a headband or headphones). The electrical signals may be applied as constant or time-varying voltage signals that generate currents in the user's skin at levels that are safe for the human body. The electrical signals may be applied by electrodes that directly contact the user's body (e.g., the conductive surface of the electrode is placed directly on the user's skin). In other cases, the electrodes may include a cover or other coupling mechanism that directly contacts the user's skin. The cover or coupling mechanism may include conductive or semi-conductive materials, or other materials that help transmit the electrical signals to the user's body.

At operation 304, process 300 may include measuring one or more electrical signals from the user. The electrical signals may be measured using electrodes that transmit the signals into the user's body and/or using different electrodes, as described herein. The electrical signals may be measured using electrodes that directly contact the user's body and/or using electrodes that include a cover or other coupling material therebetween, as described herein.

Applying and sensing electrical signals may be performed as a multiplexed operation, wherein applying electrical signals and sensing electrical signals are performed at different times. In other cases, electrodes may be operated to apply and sense electrical signals simultaneously or during overlapping time periods.

At operation 306, process 300 may include generating a set of impedance measurements based on the applied and sensed electrical signals. The impedance data may include information about changes in the measured impedance over one or more time periods, and may capture transient physiological processes, such as the pulsating characteristics of blood flow through the user's body. The impedance data may be processed to convert the electrical measurements into digital signals. In some cases, the measured signals may be filtered (e.g., bandpass filtered) or otherwise processed to isolate specific effects, such as changes in the measured impedance due to pulsating blood flow in the user's body. Additionally or alternatively, the measured impedance data may be filtered or processed to remove noise, etc.

The impedance data may indicate the specific sensor used, the location of the sensor, an indication of the quality of the measurement (e.g., contact impedance), and/or other signal metrics. In some cases, the impedance data may span one or more time periods. For example, a first time period may capture a first series of blood pressure pulses in a user, which may span multiple respiratory cycles. In some cases, a respiratory cycle (inhalation and exhalation) may span multiple blood pressure pulses, and the first time period may capture one or more respiratory cycles. Additionally, the impedance data set may include one or more additional time periods that may overlap with the first time period or be discrete from the first time period. Each additional time period may capture one or more respiratory cycles.

In some cases, each time period may be a predetermined period for collecting impedance data. In some cases, each time period may correspond to one or more rolling windows. In other cases, the duration of the time period may be determined based on the measured impedance data and/or other physiological data collected by the electronic device. For example, the measurement data may be analyzed as it is collected, and the duration of the time period may be determined based on whether the collected data meets a defined confidence metric or other metric. In other cases, the duration may last for a specified number of heart rate cycles and/or breathing cycles, which may be determined based on impedance data and/or other measurement modalities such as motion sensors, ECG sensors, PPG sensors, etc.

At operation 308, process 300 may include determining one or more breathing parameters of the user based on the impedance data. Determining the breathing parameters may include identifying changes caused by breathing across one or more blood pressure pulses. For example, the measurement engine and/or the processing unit may be configured to identify the blood pressure pulse amplitude based on the impedance data. Breathing may cause changes in the blood pressure pulse amplitude across the respiratory cycle. For example, the impedance may rise and fall across each blood pressure pulse, which can be used to identify the user's heart rate. Additionally or alternatively, the average impedance amplitude of the blood pressure pulse may rise during inspiration and fall during exhalation. In some cases, the blood pressure pulse and the impedance data may not be completely synchronized with the user's breathing, for example, the blood pressure pulse and the impedance data may be phase shifted relative to the user's breathing. Therefore, the device may be configured to identify a rise in the average impedance value within multiple blood pressure pulses and/or a phase shift to identify the user's breathing rate.

Additionally or alternatively, the impedance data may be used to determine other physiological parameters of the user. For example, the impedance data may be used to determine stroke volume changes based on changes in the amplitude of the impedance signal, and/or determine respiratory sinus arrhythmia based on changes in heart rate changes between breaths.

FIG4 shows a visual example of impedance data 400 generated by a sensing system as described herein. Impedance data 400 is shown using a graph including a first axis 401 corresponding to impedance magnitude and a second axis 403 corresponding to time. Impedance data 400 may include an impedance signal 402, which includes changes in measured impedance over time. As shown in FIG4, the impedance signal may change with heart rate, and changes in the impedance signal may track changes in each blood pressure pulse. For example, changes in the impedance signal 402 may increase and decrease based on changes in blood volume and/or blood pressure in the user's body within each blood pressure pulse.

Impedance signal 402 may be used to identify a user's breathing rate. In some cases, the magnitude of impedance signal 402 will vary across one or more breathing cycles. For example, a breathing signal 404 representing changes in impedance caused by breathing may be determined from impedance signal 402. This may include taking an average of the impedance magnitude within each heart rate cycle, which may be used to generate breathing signal 404. In other cases, any other suitable technique may be used to generate a breathing signal, including curve fitting, rolling averaging, taking the median of each impedance cycle, etc.

The breathing rate may be identified based on the breathing signal 404, for example, based on each peak of the breathing signal 404 (e.g., each peak represents a new breath). Additionally or alternatively, other suitable techniques may be used to identify the breathing rate, including identifying each valley of the breathing signal 404, averaging or otherwise analyzing multiple cycles of the breathing signal 404, etc. In some cases, changes in the amplitude, average amplitude, phase, or other metrics of the impedance signal 402 and/or the breathing signal may be used to determine the breathing rate and/or other breathing metrics. For example, changes in the amplitude of the impedance signal may be used to determine the breathing depth, which may characterize the depth of the user's breathing (e.g., the amount of inspiration and/or expiration).

In some cases, impedance signal 402 can be used to determine other physiological parameters of the user. For example, the pulse amplitude of each heartbeat can change based on the change in the user's stroke volume. Therefore, changes in the individual pulse amplitudes of impedance signal 442 can be used to derive information about the change in the user's stroke volume. Additionally or alternatively, the heart rate can change between breaths, which can be indicated by changes in frequency modulation in impedance signal 402. Therefore, changes in the frequency of impedance signal 402 can be used to determine information about respiratory sinus arrhythmia of the user.

5 shows an exemplary process 500 for selecting electrodes and performing impedance respiration measurement using the selected electrodes. Process 500 may be performed by electronic devices described herein, including electronic device 100 and watch 200.

At operation 502, process 500 may include performing a first set of impedance measurements using one or more sets of electrodes. The first set of impedance measurements may include one or more contact metrics characterizing contact of the electrodes with a user. For example, when the user wears the wearable device, the anatomy of a particular user and/or how the user wears the device may affect the contact of each of the electrodes with the user. The first set of impedance measurements may be configured to apply an electrical signal to the user's skin to assess the ability of each electrode to transmit an electrical signal to the user's tissue, such as a blood vessel. The contact metric may be a measure of contact of one or more electrodes with the user.

Contact metrics may be determined for different combinations of electrodes within a set of electrodes. For example, if the set of electrodes includes three electrodes positioned on the back of a watch case, contact metrics may be determined using different combinations of the three electrodes. In one case, a first electrode may apply an electrical signal to a user, and a second electrode may sense the electrical signal from the user. Different combinations of electrodes may be evaluated to generate multiple skin contact impedance metrics corresponding to different combinations of electrodes. Contact metrics may also be generated for electrodes in different sets, which may be located at different locations on an electronic device. For example, in the case of a watch, a set of electrodes may be located on a band of the watch. The system may determine contact metrics for different combinations of electrodes in a set of electrodes located on the band. Additionally or alternatively, the system may determine contact metrics for combinations of electrodes in different sets. For example, contact metrics may be determined for electrodes located on the body of the watch and electrodes on the band.

At operation 504, process 500 may include selecting a subset of electrodes based on the first set of impedance measurements. For example, the system may select a subset of electrodes with the lowest skin contact impedance. In some cases, the system may select the same electrodes to operate as drive electrodes and sense electrodes. In other cases, the system may select different electrodes to operate as drive electrodes and sense electrodes.

At operation 506, process 500 may include performing a second impedance measurement (eg, a respiratory impedance measurement as described herein) using the selected electrodes. The second impedance measurement may be used to generate impedance data for the user and determine one or more physiological parameters such as respiratory rate, as described herein.

In some cases, the system may periodically evaluate the contact of a selected subset of electrodes, for example by performing additional skin contact impedance measurements. In some cases, the system may continue to use the selected subset of electrodes until the contact impedance metric drops below the contact criterion. In other cases, the system may use other sensors to determine when to evaluate the contact metric of the selected subset of electrodes and/or select different electrodes for performing a second impedance measurement. For example, the system may monitor the user's movement, and if the user's movement state meets the movement threshold, the system may re-evaluate the contact metric of the subset of electrodes and/or select a new subset of electrodes.

The system may also use the contact metrics to determine whether to perform a second impedance measurement. For example, the system may determine whether the contact metrics of one or more combinations of electrodes meet an impedance threshold. If the system determines that the contact metrics meet the impedance threshold, the system may initiate a second set of impedance measurements. If the system determines that the contact metrics do not meet the impedance threshold, the system may abort or delay the second impedance measurement. In some cases, the system may continue to evaluate the contact metrics to determine whether they meet the impedance threshold.

At operation 508, process 500 may include determining a breathing parameter of the user using the impedance data generated from the selected subset of electrodes. Determining the breathing parameter of the user may include identifying breathing-induced changes across one or more blood pressure pulses, as described herein.

FIG6 illustrates an exemplary process 600 for determining when to perform impedance respiration measurement using motion data. Process 600 may be performed by an electronic device described herein including electronic device 100 and watch 200. The device described herein may monitor a low motion state before initiating an impedance measurement of the user. In some cases, determining that the user is in a low motion state before initiating an impedance measurement may help improve the accuracy of a physiological parameter determined from the impedance data.

At operation 602, process 600 may include performing a set of motion measurements of a user. The motion measurements may be used to determine the motion state of the user. In some cases, the motion measurements may be used to determine whether the user is in a low motion state before initiating impedance measurements of the user. The motion measurements may be performed by one or more sensors including an IMU (such as one or more accelerometers configured to measure motion in one or more directions). The motion sensor may output an indication of the amount or size of the user's motion. In some cases, the output from the motion sensor may be used to determine the motion state of the user, including whether the user is in a sleeping state, a resting state, etc.

The motion data can be analyzed in conjunction with other data to determine the user's motion state. For example, the motion data can be correlated with the time of day to determine whether the user is sleeping, which can be associated with longer durations of low motion states. The impedance measurement can be adjusted accordingly, including collecting more impedance data sets during longer durations of low motion states.

In some cases, the system may use impedance data obtained while the user is sleeping to generate a baseline data set of impedance-based respiration measurements. The system may opportunistically obtain respiratory impedance measurements of the user throughout the day (e.g., during short durations of low motion states, which may include when the user is sitting or otherwise sedentary). These opportunistic impedance measurements may be collected over shorter durations and have higher thresholds for movement or other noise than impedance measurements obtained while the user is sleeping. The opportunistic measurements may be compared or otherwise correlated with the baseline data set to assess changes in the user's respiration based on the baseline data set.

At operation 604, process 600 may include determining whether the motion measurement meets a low motion criterion. The low motion criterion may be defined as a motion state that identifies when the user is sleeping, resting, or in another low motion state. In some cases, the low motion criterion may be defined as other similar metrics that identify when the user's movement is below an acceleration threshold or characterizes the amount or intensity of the user's movement. The low motion criterion may include determining that the user's motion state is below a threshold within a defined duration. For example, the low motion criterion may include a duration for distinguishing between transient conditions and longer low motion conditions (such as those associated with sleep periods or longer rest periods).

If the low motion state determined based on the motion measurements does not meet the low motion criteria, process 600 may include continuing to perform additional motion measurements of the user at operations 602 and 604 of process 600. In some cases, the process may include determining a wait time between performing a first set of motion measurements and a second set of motion measurements.

At operation 606, if the low motion state determined based on the motion measurements meets the low motion criteria, process 600 may include performing a set of impedance measurements for the user, as described herein. At operation 608, process 600 may include using the impedance data to determine one or more breathing parameters of the user, as described herein.

FIG. 7 is an exemplary block diagram of an impedance measurement system 700, which may take the form of any of the devices described with reference to FIGS. 1 to 6. The impedance measurement system 700 may include a processor 702, an input/output (I/O) mechanism 704 (e.g., a wired or wireless communication interface), a display 706, a memory 708, a sensor 710 (e.g., a physiological sensor, such as those described herein), and a power source 712 (e.g., a rechargeable battery). The processor 702 may control some or all of the operations of the impedance measurement system 700. The processor 702 may communicate directly or indirectly with some or all of the components of the impedance measurement system 700. For example, a system bus or other communication mechanism 714 may provide communication between the processor 702, the I/O mechanism 704, the memory 708, the sensor 710, and the power source 712.

Processor 702 may be implemented as any electronic device capable of processing, receiving or sending data or instructions. For example, processor 702 may be a microprocessor, a central processing unit (CPU), an application specific integrated circuit (ASIC), a digital signal processor (DSP), or a combination of such devices. As described herein, the term "processor" is intended to encompass a single processor or processing unit, multiple processors, multiple processing units, or one or more other suitable computing elements. The processing unit may be programmed to perform various aspects of the system described herein.

It should be noted that the components of the impedance measurement system 700 may be controlled by multiple processors. For example, selected components of the impedance measurement system 700 (e.g., the sensor 710) may be controlled by a first processor, and other components of the impedance measurement system 700 (e.g., the I/O 704) may be controlled by a second processor, where the first processor and the second processor may or may not be in communication with each other.

I/O device 704 can transmit data to a user or another electronic device and/or receive data from a user or another electronic device. I/O devices can transmit electrical signals via a communication network such as a wireless and/or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular networks, Wi-Fi, Bluetooth, IR, and Ethernet connections. In some cases, I/O device 704 can communicate with external electronic devices, such as smart phones, electronic devices, or other portable electronic devices, as described herein.

The impedance measurement system may optionally include a display 706, such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a light emitting diode (LED) display, etc. If the display 706 is an LCD, the display 706 may also include a backlight component that can be controlled to provide variable display brightness levels. If the display 706 is an OLED or LED type display, the brightness of the display 706 can be controlled by modifying the electrical signal provided to the display element. The display 706 may correspond to any of the displays shown or described herein.

The memory 708 can store electronic data that can be used by the impedance measurement system 700. For example, the memory 708 can store electronic data or content, such as, for example, audio files and video files, documents and applications, device settings and user preferences, timing signals, control signals, and data structures or databases. The memory 708 can be configured as any type of memory. By way of example only, the memory 708 can be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage elements, or a combination of such devices.

The impedance measurement system 700 may also include one or more sensors 710 positioned substantially anywhere on the impedance measurement system 700. The sensors 710 may be configured to sense one or more types of parameters, such as, but not limited to, pressure, light, touch, heat, movement, relative motion, biometric data (e.g., biological parameters), etc. For example, the sensors 710 may include pressure transducers, thermal sensors, accelerometers, gyroscopes, position sensors, light or optical sensors, magnetometers, health monitoring sensors, etc. Furthermore, the one or more sensors 710 may utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasonic, piezoelectric, and thermal sensing technologies.

The power source 712 may be implemented with any device capable of providing energy to the impedance measurement system 700. For example, the power source 712 may be one or more batteries or rechargeable batteries. Additionally or alternatively, the power source 712 may be a power connector or power cord that connects the impedance measurement system 700 to another power source, such as a wall outlet.

As described above, one aspect of the present technology is to monitor and manage the physiological conditions of users such as respiratory parameters, etc. The present disclosure contemplates that, in some instances, these collected data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data may include demographic data, location-based data, phone numbers, email addresses, Twitter IDs (or other social media aliases or handles), home addresses, data or records related to the user's health or fitness level (e.g., vital sign measurements, medication information, exercise information), date of birth, or any other identifying information or personal information.

The present disclosure recognizes that the use of such personal information data in the present technology can be used to benefit the user. For example, the personal information data can be used to provide a user-customized tactile or audio-visual output. In addition, the present disclosure also anticipates other uses of the personal information data that benefit the user. For example, health and fitness data can be used to provide insights into the user's overall health, or can be used as positive feedback to individuals using technology to pursue health goals.

This disclosure envisions that entities responsible for collecting, analyzing, disclosing, transmitting, storing or otherwise using such personal information data will comply with established privacy policies and/or privacy practices. Specifically, such entities should implement and adhere to privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining the privacy and security of personal information data. Such policies should be easily accessible to users and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable purposes of the entity and not shared or sold outside of these legitimate uses. In addition, such collection/sharing should be performed after receiving informed consent from the user. In addition, such entities should consider taking any necessary steps to defend and safeguard access to such personal information data and ensure that others who have access to personal information data comply with their privacy policies and processes. In addition, such entities may subject themselves to third-party assessments to demonstrate their compliance with widely accepted privacy policies and practices. In addition, policies and practices should be adjusted to specific types of personal information data collected and/or accessed, and modified to apply to applicable laws and standards including specific considerations of jurisdiction. For example, in the United States, the collection or access of certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA), while health data in other countries may be subject to other regulations and policies and should be handled accordingly. Therefore, different privacy practices should be maintained in each country for different types of personal data.

Regardless of the foregoing, the present disclosure also contemplates implementation scenarios in which users selectively block the use or access of personal information data. That is, the present disclosure contemplates that hardware elements and/or software elements may be provided to prevent or block access to such personal information data. For example, with respect to determining spatial parameters, the technology of the present invention may be configured to allow users to choose to "opt in" or "opt out" to participate in the collection of personal information data at any time during or after registration for a service. In addition to providing "opt-in" and "opt-out" options, the present disclosure also contemplates providing notifications related to access or use of personal information. For example, a user may be notified that their personal information data will be accessed when downloading an application, and then be reminded again just before the personal information data is accessed by the application.

Furthermore, it is an object of the present disclosure that personal information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use. Risks can be minimized by limiting data collection and deleting data once it is no longer needed. Additionally, and when applicable, including in certain health-related applications, data de-identification can be used to protect the privacy of users. Where appropriate, de-identification can be facilitated by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or characteristics of stored data (e.g., collecting location data at a city level rather than an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods.

Thus, while the present disclosure broadly covers the use of personal information data to implement one or more of the various disclosed embodiments, the present disclosure also contemplates that various embodiments may also be implemented without access to such personal information data. That is, the various embodiments of the present technology will not fail to function properly due to the lack of all or a portion of such personal information data. For example, tactile output may be provided based on non-personal information data or an absolute minimum amount of personal information (such as an event or state at a device associated with a user, other non-personal information, or publicly available information).

For the purpose of illustration, the foregoing description uses specific nomenclature to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that specific details are not required in order to practice the embodiments. Therefore, for the purpose of illustration and description, the foregoing description of the specific embodiments described herein is presented. They are not intended to be exhaustive or to limit the embodiments to the disclosed precise forms. It will be apparent to those of ordinary skill in the art that, in view of the above teachings, many modifications and variations are feasible.

Claims (20)

1. A wearable device, comprising:

A strap configured to secure the wearable device to a wrist of a user;

a plurality of electrodes positioned to contact the user when the strap secures the wearable device to the wrist of the user; and

A processor configured to:

Causing the plurality of electrodes to apply an electrical signal to the user;

measuring the electrical signal from the user using the plurality of electrodes;

Generating a set of impedance data from the measured electrical signals; and

One or more respiratory cycles are identified using the set of impedance data.

2. The wearable device of claim 1, wherein the processor is configured to:

Performing a set of measurements using the plurality of electrodes to determine a plurality of contact metrics for a plurality of subsets of the plurality of electrodes, wherein each contact metric of the plurality of contact metrics represents a contact quality for a corresponding subset of the plurality of subsets;

Selecting a subset of the plurality of subsets using the plurality of contact metrics; and

The electrical signal from the user is measured using a selected subset of the plurality of subsets.

3. The wearable device of any of claims 1-2, wherein the processor is configured to:

Determining a first subset of electrodes from the plurality of electrodes for applying the electrical signal to the user; and

A second subset of electrodes for measuring the electrical signal from the user is determined from the plurality of electrodes.

4. A wearable device according to claim 3, wherein the first subset of electrodes comprises different electrodes than the second subset of electrodes.

5. The wearable device of any of claims 1-2, further comprising: a motion sensor positioned at least partially within the wearable device, wherein the processor is configured to:

determining a motion state of the user using the motion sensor; and

The plurality of electrodes is caused to apply the electrical signal in response to determining that the motion state meets a low motion criterion.

6. The wearable device of any of claims 1-2, further comprising: an optical sensor coupled to the wearable device, wherein the processor is configured to:

generating a set of optical data using the optical sensor; and

The set of optical data is used to identify the one or more respiratory cycles.

7. The wearable device of any of claims 1-2, further comprising:

A housing; and

A touch sensitive display coupled to the housing; wherein:

The strap is configured to secure the housing to the wrist of a user; and

At least one electrode of the plurality of electrodes is positioned on the belt.

8. A wearable device, comprising:

An electrode configured to:

Applying one or more electrical signals to a user; and

Sensing the one or more electrical signals from the user; and

A processor configured to:

performing one or more first impedance measurements using the electrodes to determine a set of contact metrics;

Selecting a subset of the electrodes using the set of contact metrics;

performing one or more second impedance measurements using the subset of electrodes to generate a set of impedance data; and

One or more respiratory cycles of the user are determined from the set of impedance data.

9. The wearable device of claim 8, wherein determining the set of contact metrics comprises determining a contact impedance of one or more of the electrodes.

10. The wearable device of any of claims 8-9, wherein the selecting the subset of the electrodes comprises:

Selecting a first subset of the electrodes for applying the one or more electrical signals to the user; and

A second subset of the electrodes for sensing the one or more electrical signals from the user is selected.

11. The wearable device of claim 10, wherein the first subset of the electrodes comprises different electrodes than the second subset of the electrodes.

12. The wearable device of any of claims 8-9, wherein the processor is configured to:

determining whether the set of contact metrics meets an impedance threshold; and

In response to determining that the set of contact metrics meets the impedance threshold, the one or more second impedance measurements are initiated.

13. The wearable device of claim 12, wherein in response to determining that the set of contact metrics does not meet the impedance threshold, the processor is configured to abort the one or more second impedance measurements.

14. The wearable device of any of claims 8-9, wherein:

The electrode includes a first set of electrodes positioned at a first location of the wearable device and a second set of electrodes positioned at a second location of the wearable device; and

The selecting the subset of the electrodes includes selecting one of the first set of electrodes or the second set of electrodes.

15. The wearable device of claim 14, further comprising:

A housing; and

A strap configured to secure the housing to the user, wherein the first set of electrodes is positioned on the strap.

16. A wearable sensing device for measuring a respiratory parameter of a user, comprising:

a set of electrodes configured to apply an electrical signal to a body of the user and to sense the electrical signal from the body;

a motion sensor configured to measure motion of the user; and

A processor configured to:

determining that the motion state of the user meets a low motion criterion using the measured motion; and

Responsive to the determining that the motion state meets the low motion criterion:

Measuring an impedance of the user using the set of electrodes while the set of electrodes contacts the user; and

The breathing parameter of the user is determined from the measured impedance.

17. The wearable sensing device of claim 16, wherein:

the motion sensor includes an accelerometer configured to output an acceleration measurement; and

Determining that the motion state of the user meets the low motion criteria includes determining that an acceleration measurement is below a defined acceleration value.

18. The wearable sensing device of any of claims 16-17, wherein:

The set of electrodes includes:

a first electrode configured to apply the electrical signal to the user; and

A second electrode configured to sense the electrical signal from the user; and

The measured impedance of the user is determined from the applied and sensed electrical signals.

19. The wearable sensing device of claim 18, wherein the processor is configured to:

Performing one or more contact impedance measurements using the set of electrodes to determine a set of contact metrics; and

The first electrode and the second electrode are selected using the set of contact metrics.

20. The wearable sensing device of any of claims 16-17, further comprising:

a housing;

A touch sensitive display coupled to the housing; and

A strap coupled to the housing and configured to secure the housing to the user, wherein one or more electrodes of the set of electrodes are positioned on the strap.