Providing user prompts corresponding to wearable device sensor positioning

Abstract

Some disclosed examples involve obtaining a first heart rate waveform via a sensor system of a wearable device in a first wearable device configuration, the first wearable device configuration corresponding to a first location of at least a portion of the sensor system. Some examples involve prompting a user via a user interface of the wearable device to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system. Some examples involve obtaining a second heart rate waveform in the second wearable device configuration, and determining, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform. Some examples involve prompting the user to change the wearable device configuration or maintain the current wearable device configuration.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Patent Application No. 18 / 461,416, filed September 5, 2023, entitled “Providing User Prompts for Wearable Device Sensor Positions,” which is incorporated herein by reference for all purposes. Technical Field

[0003] This disclosure relates in its entirety to wearable devices including sensor systems configured for biometric applications, biomedical applications, or both.

[0004] Related technical descriptions

[0005] Various sensing technologies and algorithms are being implemented in devices for a wide range of biometric and biomedical applications, including health and wellness monitoring. This drive is partly due to the limitations of traditional measurement devices in terms of their availability for continuous, non-invasive, and dynamic monitoring. Some of these devices are photoacoustic devices or incorporate photoacoustic elements. While some previously deployed photoacoustic devices and systems have provided acceptable results, improved photoacoustic devices and systems are desirable. Summary of the Invention

[0006] The systems, methods, and apparatuses disclosed herein each have several aspects, none of which individually is fully responsible for the desired properties disclosed herein.

[0007] One innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus. In some embodiments, the apparatus may be a wearable device or may include a wearable device. The apparatus may include a sensor system, a user interface system, and a control system. In some examples, the sensor system may be adaptable to a variety of configurations, which may be referred to herein as a "wearable device configuration." In some examples, the sensor system may be configured to obtain a heart rate waveform from a user of the wearable device. According to some examples, the sensor system may be a photoacoustic sensor system or may include a photoacoustic sensor system. The photoacoustic sensor system may include a light source system and a receiver system. The receiver system may be an ultrasonic receiver system or may include an ultrasonic receiver system having an array of ultrasonic receiver elements.

[0008] In some implementations, the device may include a control system. The control system may include one or more general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or combinations thereof. The control system may be configured to: obtain a first heart rate waveform via the sensor system in a first wearable device configuration, the first wearable device configuration corresponding to a first location of one or more sensors of the sensor system; and control the user interface system to prompt the user to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system. The control system may be configured to: obtain a second heart rate waveform via the sensor system in the second wearable device configuration; determine, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform; and control the user interface system to prompt the user to change the wearable device configuration or maintain the current wearable device configuration.

[0009] In some examples, determining whether to change the wearable device configuration or maintain the current wearable device configuration may involve: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determining a second SNR corresponding to the second heart rate waveform; and comparing the first SNR with the second SNR. In some examples, the control system may be configured to obtain first to Nth heart rate waveforms via the sensor system with first to Nth wearable device configurations, where N is an integer greater than 2. In some examples, the control system may be configured to: select one of the first to Nth wearable device configurations at least in part based on the first to Nth heart rate waveforms; and control the user interface system to prompt the user to change the wearable device configuration to the selected wearable device configuration.

[0010] Other innovative aspects of the subject matter described in this disclosure can be implemented in a method. The method may involve: obtaining a first heart rate waveform via a sensor system of a wearable device in a first wearable device configuration, the first wearable device configuration corresponding to a first location of one or more sensors of the sensor system. The method may involve: prompting a user via a user interface of the wearable device to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system. The method may involve: obtaining a second heart rate waveform via the sensor system in the second wearable device configuration; and determining, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform. The method may involve: prompting the user via the user interface to change the wearable device configuration or maintain the current wearable device configuration.

[0011] In some examples, determining whether to change the wearable device configuration or maintain the current wearable device configuration may involve: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determining a second SNR corresponding to the second heart rate waveform; and comparing the first SNR with the second SNR. In some examples, the method may involve: obtaining first to Nth heart rate waveforms via the sensor system with first to Nth wearable device configurations, where N is an integer greater than 2. In some examples, the method may involve: selecting one of the first to Nth wearable device configurations at least in part based on the first to Nth heart rate waveforms; and controlling the user interface system to prompt the user to change the wearable device configuration to the selected wearable device configuration.

[0012] Some or all of the methods described herein can be executed by one or more devices according to instructions (e.g., software) stored on a non-transitory medium. Such non-transitory media may include memory devices such as those described herein, including but not limited to random access memory (RAM) devices, read-only memory (ROM) devices, etc. Therefore, some innovative aspects of the subject matter described herein can be implemented in one or more non-transitory media on which software is stored. The software may include instructions for controlling one or more devices to perform one or more of the disclosed methods.

[0013] Details of one or more specific embodiments of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. Note that the relative dimensions in the following drawings may not be drawn to scale. Attached Figure Description

[0014] Figure 1This is a block diagram illustrating example components of a device according to some disclosed specific implementations.

[0015] Figure 2A Example components of an apparatus according to some of the disclosed specific implementations are shown.

[0016] Figure 2B , Figure 2C , Figure 2D , Figure 2E and Figure 2F Examples of graphical user interfaces (GUIs) that can be presented via a device's display system according to some disclosed specific implementations are shown.

[0017] Figure 2G Example components of an apparatus according to some of the disclosed specific implementations are shown.

[0018] Figure 3A , Figure 3B and Figure 3C It shows how it can be arranged. Figure 2G Different examples of some components of the device shown.

[0019] Figure 3D The diagram shows the arrangement of additional components. Figure 2G Examples of components of the device shown.

[0020] Figure 4 Another example of an array of ultrasonic receiver elements is shown.

[0021] Figure 5 An example of a device configured to perform a receiver-side beamforming process is shown.

[0022] Figure 6 This is a flowchart illustrating some examples of the disclosed operations.

[0023] Figure 7 An example of heart rate waveform (HRW) features that can be extracted according to some specific implementations is shown.

[0024] Figure 8 An example of a device that can be used in a system for estimating blood pressure based at least in part on pulse transit time (PTT) is shown.

[0025] Figure 9 A schematic cross-sectional side view showing a portion of the artery 900 through which the pulse 902 propagates.

[0026] Figure 10A An example dynamic monitoring device 1000 designed to be worn on the wrist is shown according to some specific implementations.

[0027] Figure 10BAn example dynamic monitoring device 1000 designed to be worn on a finger is shown according to some specific implementations.

[0028] Figure 10C An example dynamic monitoring device 1000 designed to reside on an earpiece is shown according to some specific implementations.

[0029] The same reference numerals and names in the various figures indicate the same elements. Detailed Implementation

[0030] The following description is directed to certain implementations and is intended to describe various aspects of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in many different ways. Some of the concepts and examples provided in this disclosure are particularly applicable to blood pressure monitoring applications. However, some specific embodiments are also applicable to other types of biosensing applications, as well as other fluid flow systems. The described specific embodiments can be implemented in any device, apparatus, or system that includes the means disclosed herein. Furthermore, it is contemplated that the described specific embodiments may be included in or associated with a variety of electronic devices such as, but not limited to: mobile phones, cellular phones with multimedia internet enabled, mobile TV receivers, wireless devices, smartphones, smart cards, wearable devices (such as wristbands, armbands, wrist straps, rings, headbands, patches, etc.), Bluetooth. ® Devices, personal data assistants (PDAs), wireless email receivers, handheld or portable computers, netbooks, laptops, smartbooks, tablets, printers, copiers, scanners, fax machines, GPS receivers / navigators, cameras, digital media players, game consoles, wristwatches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), mobile health devices, computer monitors, automotive displays (including odometer and speedometer displays, etc.), cockpit controls and / or displays, camera view displays (such as rearview camera displays in vehicles), building structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washing machines, dryers, washer / dryer units, parking meters, car doors, autonomous or semi-autonomous vehicles, drones, Internet of Things (IoT) devices, etc. Therefore, this teaching is not intended to be limited to the specific specific implementations depicted and described with reference to the accompanying drawings; rather, its applicability is broad and will be apparent to those skilled in the art.

[0031] Compared to more invasive health monitoring devices, such as cuff-based or catheter-based blood pressure measurement devices, wearable and non-invasive health monitoring devices (including, but not limited to, devices with photoacoustic plethysmography (PAPG) capabilities) offer a variety of potential advantages. However, designing satisfactory PAPG-based devices has proven challenging. One challenge is the low signal-to-noise ratio (SNR) of the signals of interest, such as the ultrasound signals corresponding to the photoacoustic response of the arterial wall. For example, the amplitude of the signal corresponding to the arterial wall is significantly lower than that of the signal corresponding to the photoacoustic response of the skin.

[0032] Another challenge is that the orientation of the same artery can vary from user to user, and even within the same user's body. These variations in arterial orientation can make it challenging to properly position the ultrasound receiver of a PAPG-based device, or any wearable device that includes a sensor system configured to acquire heart rate waveforms or other signals of interest related to blood vessels or blood within them. Furthermore, the wearable device's positioning relative to the user can change as the user engages in physical activities such as exercise, housework, etc. Even small changes in sensor system positioning can lead to significant differences in the received heart rate waveform signals, such as those corresponding to the arterial wall. If the sensor system is mispositioned, signal quality can be poor, and depth discrimination may be impossible.

[0033] In some implementations, the wearable device may include a sensor system, a user interface system, and a control system. The sensor system may be adaptable to various wearable device configurations. Each wearable device configuration may correspond to a different location of at least a portion of the sensor system, such as the location of one or more sensors of the sensor system. In some examples, the sensor system may be configured to obtain a heart rate waveform from a user of the wearable device. According to some examples, the control system may be configured to obtain signals via the sensor system for each of the various wearable device configurations, which may include signals associated with the heart rate waveform. In some examples, the control system may be configured to determine, based on the heart rate waveform, whether to change the wearable device configuration or maintain the current wearable device configuration. The determination may be, for example, at least in part, based on a comparison of the signal-to-noise ratio (SNR) corresponding to the signals obtained for each wearable device configuration. According to some examples, the control system may be configured to control the user interface system to prompt the user to change the wearable device configuration or maintain the current wearable device configuration. In some examples, the sensor system may be a photoacoustic sensor system or may include a photoacoustic sensor system. The photoacoustic sensor system may include a light source system and a receiver system. The receiver system may be an ultrasonic receiver system or may include an ultrasonic receiver system having an array of ultrasonic receiver elements.

[0034] Specific embodiments of the subject matter described in this disclosure can be implemented to achieve one or more of the following potential advantages. Various disclosed embodiments provide a wearable device having a sensor system capable of adjusting for multiple wearable device configurations and a control system configured to select the optimal wearable device configuration from among the multiple wearable device configurations. The control system may be configured to control a user interface system to prompt a user to change the wearable device configuration or maintain the current wearable device configuration. The prompt may be based, for example, on a comparison of the signal frequency (SNR) corresponding to the signal obtained in each wearable device configuration. The prompt may, for example, correspond to a wearable device configuration that corresponds to the highest SNR of one or more signals of interest, such as signals corresponding to one or more vascular features. Thus, some embodiments have the potential advantage of selecting the optimal wearable device configuration to obtain one or more signals of interest. In some examples, the control system may be configured to estimate blood pressure at least in part based on vascular features. Enhancing the SNR of the signal corresponding to the vascular features can result in a relatively more accurate blood pressure estimate.

[0035] Figure 1 This is a block diagram illustrating example components of an apparatus according to some of the disclosed embodiments. In this example, apparatus 100 includes a sensor system 103, a control system 106, and an interface system 108 including a user interface system. In some examples, sensor system 103 may be a PAPG system or may include a PAPG system comprising an ultrasound receiver system 102 and a light source system 104. According to some examples, sensor system 103 may include one or more other types of sensors capable of detecting heart rate waveforms, such as a photoplethysmography (PPG) system, one or more microphones, one or more accelerometers, etc. Some embodiments of apparatus 100 may include a pressure plate 101, a noise reduction system 110, or both. With respect to other disclosed embodiments, in some alternative embodiments, apparatus 100 may include more components, fewer components, or different components.

[0036] According to some examples, pressure plate 101 (when present) or another part of the device may include one or more anti-reflective layers. In some examples, one or more anti-reflective layers may reside on or near one or more outer surfaces of pressure plate 101.

[0037] In some examples, at least a portion of the outer surface of the pressure plate 101 (when present) may have an acoustic impedance configured to approximate the acoustic impedance of human skin. This portion of the outer surface of the pressure plate 101 may, for example, be a portion configured to receive a target object, such as a human finger. (As used herein, the terms “finger” and “fingertip” are used interchangeably, such that the thumb is an example of a finger.) The typical range of acoustic impedance for human skin is 1.53 to 1.680 megaretes. In some examples, at least the outer surface of the pressure plate 101 may have an acoustic impedance in the range of 1.4 to 1.8 megaretes or in the range of 1.5 to 1.7 megaretes.

[0038] Alternatively or additionally, in some examples, at least the outer surface of the pressure plate 101 may be configured to conform to the surface of human skin. In some such examples, at least the outer surface of the pressure plate 101 may have material properties similar to putty or chewing gum.

[0039] In some examples, at least a portion of the pressure plate 101 may have an acoustic impedance configured to approximate the acoustic impedance of one or more receiver elements of the ultrasonic receiver system 102. According to some examples, a layer residing between the pressure plate 101 and the one or more receiver elements may have an acoustic impedance configured to approximate the acoustic impedance of the one or more receiver elements. Alternatively or additionally, in some examples, the layer residing between the pressure plate 101 and the one or more receiver elements may have an acoustic impedance within a range between the acoustic impedance of the pressure plate and the acoustic impedance of the one or more receiver elements.

[0040] This document discloses various examples and configurations of an ultrasonic receiver system 102. Some examples are described in more detail below. In some examples, the ultrasonic receiver system 102 (where present) may include a piezoelectric receiver layer, such as a PVDF polymer layer, a PVDF-TrFE copolymer layer, or a piezoelectric composite layer. In some implementations, other piezoelectric materials, such as aluminum nitride (AlN) or lead zirconate titanate (PZT), may be used in the piezoelectric layer.

[0041] In some examples, the ultrasonic receiver system 102 may include an array of ultrasonic receiver elements. In some examples, the ultrasonic receiver system 102 may include an array of electrodes disposed on a piezoelectric receiver layer (such as a PVDF polymer layer, a PVDF-TrFE copolymer layer, AlN, or PZT) or on a piezoelectric composite material layer. In some examples, the ultrasonic receiver system 102 may include an array of ultrasonic transducer elements, such as an array of piezoelectric micromechanical ultrasonic transducers (PMUTs), an array of capacitive micromechanical ultrasonic transducers (CMUTs), etc. In some such examples, a piezoelectric receiver layer, PMUT elements in a monolayer array of PMUTs, or CMUT elements in a monolayer array of CMUTs can be used as both an ultrasonic transmitter and an ultrasonic receiver. According to some examples, the ultrasonic receiver system 102 may be an ultrasonic receiver array or may include an ultrasonic receiver array. In some examples, the device 100 may include one or more separate ultrasonic transmitter elements. In some such examples, the ultrasonic transmitter may include an ultrasonic plane wave generator. According to some examples, the ultrasonic receiver system 102 may include an array of ultrasonic receiver elements residing in a receiver plane.

[0042] According to some embodiments, the light source system 104 (when present) may include one or more light-emitting diodes (LEDs). In some embodiments, the light source system 104 may include one or more laser diodes. According to some embodiments, the light source system 104 may include one or more vertical cavity surface-emitting lasers (VCSELs). In some embodiments, the light source system 104 may include one or more edge-emitting lasers. In some embodiments, the light source system may include one or more neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. In some examples, the light source system 104 may include an array of light-emitting elements, such as an array of LEDs, an array of laser diodes, an array of VCSELs, an array of edge-emitting lasers, or combinations thereof.

[0043] According to some examples, the light source system 104 may include one or more light guiding elements configured to guide light from the light source system toward a target object along a first axis. In some examples, the one or more light guiding elements may include at least one diffraction grating. Alternatively or additionally, the one or more light guiding elements may include at least one lens.

[0044] In some examples, the light source system 104 may be configured to emit light in one or more wavelength ranges. In some examples, the light source system 104 may be configured to emit light in the 500 nm to 600 nm wavelength range. According to some examples, the light source system 104 may be configured to emit light in the 800 nm to 950 nm wavelength range.

[0045] Depending on the specific implementation, the light source system 104 may include various types of driving circuitry. In some disclosed embodiments, the light source system 104 may include at least one multi-junction laser diode, which may generate less noise than a single-junction laser diode. In some examples, the light source system 104 may include driving circuitry (also referred to herein as a driving circuitry system) configured to cause the light source system to emit light pulses with pulse widths ranging from 3 nanoseconds to 1000 nanoseconds. According to some examples, the light source system 104 may include driving circuitry configured to cause the light source system to emit light pulses at pulse repetition frequencies ranging from 1 kHz to 100 kHz.

[0046] In some examples, the light source system 104 may include a light source system surface having a normal that is parallel or substantially parallel to the first axis. In some such examples, the light source of the light source system may reside on or near the light source system surface.

[0047] In some embodiments, the light source system 104 can be configured to emit light of various wavelengths, which can be selected to trigger acoustic emission primarily from a specific type of material. For example, because heme in blood absorbs near-infrared light very strongly, in some embodiments, the light source system 104 can be configured to emit light of one or more wavelengths in the near-infrared range to trigger acoustic emission from heme. However, in some examples, the control system 106 can control the wavelength of the light emitted by the light source system 104 to preferentially sense acoustic waves in blood vessels, other soft tissues, and / or bones. For example, an infrared (IR) light-emitting diode (LED) can be selected and emits short pulses of IR light to illuminate a portion of a target object and generate acoustic emission, which is then detected by the ultrasound receiver system 102. In another example, an IR LED and a red LED or other colors, such as green, blue, white, or ultraviolet (UV), can be selected and short pulses of light can be emitted sequentially from each light source, wherein an ultrasound image is obtained after each light source emits light. In other specific implementations, one or more light sources of different wavelengths can be illuminated sequentially or simultaneously to generate acoustic emissions detectable by an ultrasonic receiver. Image data obtained from the ultrasonic receiver using light sources of different wavelengths at different depths (e.g., varying RGDs) within the target object can be combined to determine the location and type of material within the target object. Image contrast is possible because materials in the body typically absorb light of different wavelengths differently. When materials in the body absorb light of a specific wavelength, they may heat up differently and generate acoustic emissions with sufficiently strong and short light pulses. Depth contrast can be obtained using light of different wavelengths and / or intensities at each selected wavelength. That is, continuous images can be obtained using varying light intensities and wavelengths at a fixed RGD (which may correspond to a fixed depth of the target object) to detect material and its location within the target object. For example, hemoglobin, blood glucose, or blood oxygen in blood vessels within a target object such as a finger can be detected photoacously.

[0048] According to some embodiments, the light source system 104 can be configured to emit light pulses with pulse widths less than about 100 nanoseconds. In some embodiments, the light pulses may have pulse widths between about 10 nanoseconds and about 500 nanoseconds or longer. According to some examples, the light source system can be configured to emit multiple light pulses at pulse repetition frequencies between 10 Hz and 100 kHz. Alternatively or additionally, in some embodiments, the light source system 104 can be configured to emit multiple light pulses at pulse repetition frequencies between about 1 MHz and about 100 MHz. Alternatively or additionally, in some embodiments, the light source system 104 can be configured to emit multiple light pulses at pulse repetition frequencies between about 10 Hz and about 1 MHz. In some examples, the pulse repetition frequency of the light pulses may correspond to the acoustic resonant frequency of the ultrasonic receiver and the substrate. For example, a set of four or more light pulses may be emitted from the light source system 104 at a frequency corresponding to the resonant frequency of the resonant acoustic cavity in the sensor stack, allowing for the accumulation of received ultrasonic waves and a higher resulting signal strength. In some embodiments, filtered light or a light source with a specific wavelength for detecting the selected material may be included in the light source system 104. In some embodiments, the light source system may contain light sources such as red, green, and blue LEDs for displays, which may be enhanced by light sources of other wavelengths (such as IR and / or UV) and light sources with higher optical power. For example, high-power laser diodes or electronic flash units (e.g., LED or xenon flash units) with or without filters may be used for short-term illumination of the target object.

[0049] The control system 106 may include one or more general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or combinations thereof. The control system 106 may also include (and / or be configured to communicate with) one or more memory devices such as one or more random access memory (RAM) devices, read-only memory (ROM) devices, etc. Therefore, the device 100 may have a memory system including one or more memory devices, but... Figure 1 The memory system is not shown. The control system 106 can be configured to receive and process data from the ultrasonic receiver system 102, for example, as described below. If the device 100 includes an ultrasonic transmitter, the control system 106 can be configured to control the ultrasonic transmitter. In some embodiments, the functionality of the control system 106 can be divided among one or more controllers or processors, such as between a dedicated sensor controller and an application processor in a mobile device.

[0050] In some examples, the control system 106 may be configured to acquire a first heart rate waveform via the sensor system 103 in a first wearable device configuration. The first wearable device configuration may correspond to a first location of one or more sensors of the sensor system 103. For example, in some embodiments where the sensor system 103 includes an ultrasound receiver system 102, the first wearable device configuration may correspond to a first location of at least a portion of the ultrasound receiver system 102. In some embodiments where the sensor system 103 includes a light source system 104, the first wearable device configuration may correspond to a first location of at least a portion of the light source system 104.

[0051] According to some examples, the control system 106 may be configured to control the user interface system to prompt a user to change the wearable device configuration to a second wearable device configuration. According to some such examples, the control system 106 may be configured to control at least one display, at least one speaker, or both of the user interface system to provide user prompts. In this example, the second wearable device configuration corresponds to a second positioning of one or more components of the sensor system 103. In some examples, the control system 106 may be configured to obtain a second heart rate waveform via the sensor system 103 in the second wearable device configuration.

[0052] In some examples, the control system 106 may be configured to determine whether to change the wearable device configuration or maintain the current wearable device configuration, based at least in part on a first heart rate waveform and a second heart rate waveform. In some such examples, the control system 106 may be configured to make this determination based at least in part on a comparison of a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform and a second SNR corresponding to the second heart rate waveform. According to some examples, the control system 106 may be configured to control the user interface system to prompt the user to change the wearable device configuration or maintain the current wearable device configuration.

[0053] According to some examples, the control system 106 may be configured to receive a signal from each of a plurality of ultrasonic receiver elements in an array of ultrasonic receiver elements of the ultrasonic receiver system 102. The signal may correspond to ultrasonic waves generated by a target object in response to light from the light source system 104. In some examples, the control system 106 may be configured to apply a receiver-side beamforming process to the ultrasonic receiver signal to generate a beamformed ultrasonic receiver image. According to some examples, the control system 106 may be configured to detect blood vessels within a target object based at least in part on the beamformed ultrasonic receiver image. In some such examples, the control system 106 may be configured to estimate one or more vascular features based at least in part on the beamformed ultrasonic receiver image. In some examples, the control system 106 may be configured to estimate one or more cardiac features based at least in part on one or more arterial signals and vascular features. According to some examples, the cardiac features may be blood pressure or may include blood pressure.

[0054] In this example, device 100 has an interface system 108 that includes a user interface system. According to some examples, the user interface system may include a microphone system, a speaker system, a haptic feedback system, a voice command system, one or more displays, or a combination thereof. In some examples, the user interface system may include a touch sensor system, a gesture sensor system, or a combination thereof. The touch sensor system (if present) may be a resistive touch sensor system, a surface capacitive touch sensor system, a projected capacitive touch sensor system, a surface acoustic wave touch sensor system, an infrared touch sensor system, any other suitable type of touch sensor system, or a combination thereof, or may include all of the foregoing.

[0055] In some examples, interface system 108 may include a wireless interface system. In some specific implementations, interface system 108 may include one or more network interfaces, one or more interfaces between control system 106 and memory system, and / or one or more interfaces between control system 106 and one or more external device interfaces (e.g., ports or application processors), or combinations thereof.

[0056] In some examples, interface system 108 may include a force sensor system, a pressure sensor system, or both. The force sensor system and / or pressure sensor system (if present) may be a piezoresistive sensor, a capacitive sensor, a thin-film sensor (e.g., a polymer-based thin-film sensor), another suitable type of force sensor, or a combination thereof, or may include all of the foregoing. If the force sensor system and / or pressure sensor system includes a piezoresistive sensor, the piezoresistive sensor may include silicon, metal, polycrystalline silicon, glass, or a combination thereof. In some specific embodiments, the ultrasonic fingerprint sensor and the force sensor system and / or pressure sensor system may be mechanically coupled. In some such examples, the force sensor system and / or pressure sensor system may be integrated into the circuitry of the ultrasonic fingerprint sensor. In some examples, interface system 108 may include an optical sensor system, one or more cameras, or a combination thereof.

[0057] According to some examples, device 100 may include a noise reduction system 110. For example, noise reduction system 110 may include one or more mirrors configured to reflect light from light source system 104 away from ultrasonic receiver system 102. In some implementations, noise reduction system 110 may include one or more sound-absorbing layers, sound-insulating materials, light-absorbing materials, light-reflecting materials, or combinations thereof. In some examples, noise reduction system 110 may include sound-insulating materials that may reside between, on, or in combination with at least a portion of the light source system 104 and ultrasonic receiver system 102. In some examples, noise reduction system 110 may include one or more electromagnetically shielded transmission lines. In some such examples, the one or more electromagnetically shielded transmission lines may be configured to reduce electromagnetic interference received by ultrasonic receiver system 102 from circuitry of light source system 104, receiver system circuitry, or combinations thereof. In some examples, one or more electromagnetic shielding transmitting lines, sound-absorbing layers, sound-insulating materials, light-absorbing materials, light-reflecting materials, or combinations thereof may be components of the ultrasonic receiver system 102, the light source system 104, or both. Although in fact the ultrasonic receiver system 102, the light source system 104, and the noise reduction system 110 are... Figure 1 While shown as a separate component, such components can still be considered as elements of the noise reduction system 110.

[0058] Device 100 can be used in a variety of different contexts, many of which are disclosed herein. For example, in some embodiments, a mobile device may include device 100. In some such examples, the mobile device may be a smartphone. In some embodiments, a wearable device may include device 100, or device 100 may be a wearable device. Wearable devices may be, for example, wristbands, armbands, watchbands, rings, headbands, or patches. Thus, in some examples, device 100 may be configured to be worn by or attached to a person.

[0059] Figure 2A Example components of a device according to some of the disclosed specific embodiments are shown. For the purposes of the other figures provided herein, Figure 2A The number, type, and arrangement of the components shown are presented by way of example only. In this example, device 100 is... Figure 1 An example of device 100 is shown. According to this example, device 100 includes a sensor system 103 and a control system 106. Figure 2A (Not shown) and an interface system 108 including a user interface system. In this example, device 100 is a wearable device that includes a strip 215 for securing device 100 to a person's arm, wrist, ankle, etc. According to some examples, device 100 may be a smartwatch, such as a smartwatch configured to communicate wirelessly with a cellular phone.

[0060] In this example, device 100 is shown in a specific wearable device configuration corresponding to the positioning of sensor system 103. According to this example, a user of device 100 can position sensor system 103 in any of seven wearable device configurations: Figure 2A One wearable device configuration is shown, which can be considered as "zero-position," and six other wearable device configurations are indicated by positioning indicators 205, which display positions -3, -2, -1, +1, +2, and +3. In other specific embodiments of the device 100, the sensor system 103 can be positioned with more or fewer wearable device configurations, such as 2 wearable device configurations, 3 wearable device configurations, 4 wearable device configurations, 5 wearable device configurations, 6 wearable device configurations, 8 wearable device configurations, 9 wearable device configurations, 10 wearable device configurations, etc.

[0061] In some alternative examples, only a portion of the sensor system 103 can be configured for positioning with multiple wearable devices. In some such examples, the sensor system 103 may include a transmitter portion (such as a light source system, an ultrasonic transmitter system, etc.) that can be positioned relative to the receiver portion in various locations, or vice versa. In some PAPG-enabled examples, Figure 1The light source system 104 can be positioned in various locations relative to the ultrasonic receiver system 102. Each location corresponds to a wearable device configuration.

[0062] In some examples, the control system 106 can be configured to acquire heart rate waveforms via the sensor system 103 for each of a variety of wearable device configurations. Figure 2A In the example shown, the control system 106 is configured to acquire a heart rate waveform via the sensor system 103 for each of seven possible wearable device configurations. According to some examples, the control system 106 may be configured to acquire the heart rate waveform for each of a plurality of wearable device configurations and then select a wearable device configuration based on the heart rate waveform. For example, the control system 106 may be configured to determine the sum of frequencies (SNR) corresponding to each heart rate waveform and select a wearable device configuration based on the SNR. In some such examples, the control system 106 may be configured to select the wearable device configuration corresponding to the highest SNR.

[0063] In other examples, the control system 106 may be configured to obtain signals from the sensor system 103 corresponding to one or more other targets of interest in each of a variety of wearable device configurations, and to select a wearable device configuration based on the signals corresponding to the one or more other targets of interest. For example, one or more other targets of interest may include one or more blood vessel walls, such as one or more arterial walls. For example, the control system 106 may be configured to determine the signal frequency (SNR) corresponding to each of the signals corresponding to one or more other targets of interest, and to select a wearable device configuration based on the SNR. In some such examples, the control system 106 may be configured to select the wearable device configuration corresponding to the highest SNR.

[0064] According to this example, the control system 106 is configured to provide user prompts to the user interface of the control interface system 108. In some examples, the prompts may be visual cues made via one or more displays of the interface system 108, such as display 208, or may include such visual cues. Alternatively or additionally, the prompts may be audio cues made via one or more speakers of the interface system 108, or may include such audio cues. Some such user prompts may be prompts to change the current wearable device configuration or maintain the current wearable device configuration, or may include such user prompts. In some examples, the user prompt may be a prompt to change the current wearable device configuration to another wearable device configuration to allow the control system 106 to obtain signals from the sensor system 103 in the wearable device configuration.

[0065] Figure 2B , Figure 2C , Figure 2D, Figure 2E and Figure 2F Examples of graphical user interfaces (GUIs) that can be presented via a device's display system according to some of the disclosed specific embodiments are shown. For the purposes of the other figures provided herein, Figures 2B to 2F The number, type, and arrangement of the components shown are for illustrative purposes only. In these examples, the GUI is displayed on the monitor 208 of device 100, which is... Figure 1 and Figure 2A Examples of the device 100 shown. In these examples, the display 208 is... Figure 1 and Figure 2A The components of the interface system 108 shown. According to these examples, the device 100 also includes a touch sensor system 225, which is also... Figure 1 and Figure 2A The components of the interface system 108 shown.

[0066] Figures 2B to 2F An example is shown where the control system 106 (not shown) can cause a user prompt to be displayed on the display 208. In some examples, the prompt may include an audio prompt made via one or more speakers of the interface system 108. In these examples, the user prompt is a prompt to change the current wearable device configuration to another wearable device configuration to allow the control system 106 to obtain signals from the sensor system 103 for the next wearable device configuration.

[0067] Figure 2B This shows when device 100 is in Figure 2A When the wearable device is configured, or when device 100 is in contact with... Figure 2A The example shown illustrates how the control system 106, when configured with wearable devices corresponding to positions -1, -2, or -3, can result in a user prompt displayed on the display 208. According to this example, the GUI 220a includes a text prompt 211a and location change information 213a. In this example, the text prompt 211a instructs the user to move the sensor 103 to position +1. The location change information 213a includes an arrow 209 indicating the direction in which the sensor system 103 should move, and... Figure 2A The device 100 shown represents the positioning 205. In this example, the positioning change information 213a uses a patterned background to display positioning +1 in order to indicate that positioning +1 is the desired positioning.

[0068] In some examples, the control system 106 may have been configured by the sensor system 103 with one or more other wearable devices (such as...) before the display 208 renders the GUI 220a. Figure 2AThe wearable device configuration shown obtains a heart rate waveform (or a signal corresponding to one or more other targets of interest). According to this example, after causing display 208 to display GUI 220a, and after the device is in the wearable device configuration corresponding to position +1, control system 106 is configured to obtain an additional heart rate waveform (or an additional signal corresponding to one or more other targets of interest) via sensor system 103 in the wearable device configuration corresponding to position +1. In some examples, after obtaining data in the wearable device configuration corresponding to position +1, control system 106 may determine that sufficient information is needed to select a wearable device configuration. For example, control system 106 may determine that the peak SNR was obtained in a previous wearable device configuration. In some examples, the peak SNR may be the peak SNR of various photoacoustic signals from sensor system 103. In some such examples, the photoacoustic signals may be “raw” signals, on which little or no preprocessing is performed before SNR evaluation. Alternatively or additionally, control system 106 may evaluate the peak SNR of processed signals (such as filtered signals, beamforming signals, heart rate waveforms constructed from received signals, etc.).

[0069] However, in these examples, after causing display 208 to render GUI 220a and after obtaining data from sensor system 103 in a wearable device configuration corresponding to position +1, control system 106 causes display 208 to render... Figure 2C The GUI 220b shown is an example. According to this example, GUI 220b includes a text prompt 211b and a location change information 213b. In this example, the text prompt 211b instructs the user to move sensor 103 to location +2. According to this example, the location change information 213b displays location +2 using a patterned background to indicate that location +2 is the desired location.

[0070] According to this example, after causing display 208 to display GUI 220b, and after the device is in a wearable device configuration corresponding to location +2, control system 106 is configured to acquire additional heart rate waveforms (or signals corresponding to one or more other targets of interest) via sensor system 103 in the wearable device configuration corresponding to location +2. In some examples, after acquiring data in the wearable device configuration corresponding to location +2, control system 106 may determine that sufficient information is needed to select a wearable device configuration.

[0071] However, in these examples, after causing display 208 to render GUI 220b and after acquiring data in the wearable device configuration with the corresponding position +2, control system 106 causes display 208 to render... Figure 2DThe GUI 220c shown is an example. According to this example, text prompt 211c instructs the user to move sensor 103 to location +3, and location change information 213c displays location +3 using a patterned background to indicate that location +3 is the desired location.

[0072] According to this example, after causing display 208 to display GUI 220c, and after the device is in a wearable device configuration corresponding to location +3, control system 106 is configured to acquire additional heart rate waveforms (or signals corresponding to one or more other targets of interest) via sensor system 103 in the wearable device configuration corresponding to location +3. In some examples, after acquiring data in the wearable device configuration corresponding to location +3, control system 106 may determine that sufficient information is needed to select a wearable device configuration.

[0073] However, in these examples, after causing display 208 to render GUI 220c and after acquiring data in the wearable device configuration with the corresponding position +3, control system 106 causes display 208 to render... Figure 2E The GUI 220d shown is illustrated. According to this example, text prompt 211d instructs the user to move sensor 103 to location-1, and location change information 213d displays location-1 using a patterned background to indicate that location-1 is the desired location.

[0074] According to this example, after causing display 208 to display GUI 220d, and after the device is in wearable device configuration corresponding to position-1, control system 106 is configured to acquire additional heart rate waveforms (or signals corresponding to one or more other targets of interest) via sensor system 103 in wearable device configuration corresponding to position-1. In this example, after acquiring data in wearable device configuration corresponding to position-1, control system 106 determines that sufficient information is needed to select wearable device configuration.

[0075] In this example, the control system selects the wearable device configuration corresponding to position +1. For example, the control system may determine that the peak SNR was obtained with the wearable device configuration corresponding to position +1. Therefore, the control system 106 causes the display 208 to display... Figure 2F The GUI 220e is shown. According to this example, text prompt 211e instructs the user to return sensor 103 to location +1 and leave sensor 103 at location +1. Location change information 213e displays location +1 using a patterned background to indicate that location +1 is the desired location.

[0076] Figure 2G Example components of a device according to some of the disclosed specific embodiments are shown. For the purposes of the other figures provided herein, Figure 2G The number, type, and arrangement of the components shown are presented by way of example only. In this example, device 100 is... Figure 1 An example of device 100 is shown. According to this example, device 100 includes a pressure plate 101, a receiver system 102, and a light source system 104. In this example, the outer surface 218a of the pressure plate 101 is configured to receive a target object, such as a finger 255, wrist, etc.

[0077] According to this example, receiver system 102 is an ultrasonic receiver system or includes an ultrasonic receiver system. In this example, receiver system 102 includes receiver stack portion 102a and receiver stack portion 102b. In this example, receiver stack portion 102a includes piezoelectric material 217a, electrode layer 220a on a first side of piezoelectric material 217a, and electrode layer 222a on a second side of piezoelectric material 217a. According to some examples, an anisotropic conductive film (ACF) layer may reside between each of electrode layers 220a and 220b and piezoelectric material 217a. In this example, electrode layer 222a resides between piezoelectric material 217a and backing layer 230a. Electrode layers 220a and 220b include a conductive material, which may be a conductive metal or may include a conductive metal, such as copper in some instances. Electrode layers 220a and 220b may be electrically connected to Figure 2G The receiver system circuitry is not shown in the diagram. The receiver system circuitry may be considered as a reference herein. Figure 1 This is a part of the described control system 106, a part of the receiver system 102, or both. The piezoelectric material 217a may include, for example, a polyvinylidene fluoride (PVDF) polymer, a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer, aluminum nitride (AlN), lead zirconate titanate (PZT), piezoelectric composite materials (such as 1-3 composites, 2-2 composites, 3-3 composites, etc.), or combinations thereof. The backing layer 230a may be configured to suppress at least some acoustic artifacts and provide a relatively higher signal-to-noise ratio (SNR) than the receiver system 102 without a backing layer. In some examples, the backing layer 230a may comprise a metal, an epoxy resin, or a combination thereof.

[0078] In this example, receiver stack portion 102b includes a piezoelectric material 217b, an electrode layer 220b on a first side of the piezoelectric material 217b, and an electrode layer 222b on a second side of the piezoelectric material 217b. Here, the electrode layer 222b resides between the piezoelectric material 217b and the backing layer 230b. According to this example, receiver stack portion 102a resides near the first side of the light guide assembly 240a, and receiver stack portion 102b resides near the second side of the light guide assembly 240a. In this example, piezoelectric materials 216a and 216b are configured to generate electrical signals in response to received acoustic waves (such as photoacoustic waves PA1 and PA2).

[0079] According to this example, the light source system 104 includes at least a first light-emitting component (light-emitting component 235a in this example), at least a first light-guiding component (light-guiding component 240a in this example), and a light source system circuit 245a. The light-emitting component 235a may, for example, include one or more light-emitting diodes, one or more laser diodes, one or more VCSELs, one or more edge-emitting lasers, one or more Nd:YAG lasers, or combinations thereof.

[0080] The light guide assembly 240a may include any suitable material or combination of materials for propagating at least some of the light emitted by the light-emitting component 235a within the light guide assembly 240a, for example, due to total internal reflection between one or more core materials and one or more cladding materials of the light guide assembly 240a. In such examples, the core material will have a higher refractive index than the cladding material. In a specific and non-limiting example, the core material may have a refractive index of about 1.64, and the cladding material may have a refractive index of about 1.3. In some examples, the core material may include glass, silica, quartz, plastic, zirconium fluoride, chalcogenides, or combinations thereof. According to some examples, the cladding material may include polyvinyl chloride (PVC), acrylic, polytetrafluoroethylene (PTFE), polysiloxane, or fluorocarbon rubber. In some examples, the light guide assembly 240a may include one or more optical fibers. As used herein, the terms "light guide" and "optical tube" are used synonymously.

[0081] In some examples, the width W3 of the light guide component 240a may be in the range of 0.25 mm to 3 mm, such as 0.5 mm, 1.0 mm, 1.5 mm, etc. According to some examples, the width W2 of the space between the receiver stack portion 102a and the receiver stack portion 102b may be in the range of 0.5 mm to 5 mm, such as 1.0 mm, 1.5 mm, 2 mm, 2.5 mm, etc. In some examples, the space 233a between the receiver stack portion 102a and the light guide component 240a, and the space 233b (if any) between the receiver stack portion 102b and the light guide component 240a—in other words, the space (if any) between W2 and W3—may include light-absorbing material. According to some examples, spaces 233a and 233b (if any) may include air. In some examples, spaces 233a and 233b (if any) may include sound-absorbing material, preferably a sound-absorbing material with a relatively low Grüneisen parameter.

[0082] In this example, the light source system 104 is configured to emit light through a first region of the pressure plate toward a target object in contact with a first region of the pressure plate 101. According to this example, the light source system 104 is configured to direct light (in...) Figure 2G The light rays (represented by ray 250a and 250b) are transmitted through the light guide assembly 240a and the pressure plate region 201a toward the finger 255 in contact with the pressure plate region 201a. In this example, the arterial wall of the artery 207 generates photoacoustic waves PA1 and PA2 in response to the light rays 250a and 250b, respectively.

[0083] The pressure plate 101 may comprise any suitable material, such as glass, acrylic, polycarbonate, combinations thereof, etc. In some examples, the width W1 of the pressure plate 101 may range from 2 mm to 10 mm, for example, 4 mm, 5 mm, 6 mm, etc. According to some examples, the thickness of the pressure plate 101 (in...) Figure 2G The coordinate system shown (in the z-direction) can range from 50 micrometers to 500 micrometers, for example, 150 micrometers, 200 micrometers, 250 micrometers, 300 micrometers, etc.

[0084] In this example, the pressure plate 101 includes pressure plate regions 201a, 201b, and 201c. In this example, pressure plate region 201a resides adjacent to the light guide component 240a. Therefore, in this example, at least pressure plate region 201a includes a transparent material. According to some examples, the pressure plate 101 may include one or more anti-reflective layers. In some examples, one or more anti-reflective layers may reside on or near the pressure plate 101, for example, on or near the outer surface 218a.

[0085] According to this example, pressure plate region 201b resides near receiver stack portion 102a and pressure plate region 201c resides near receiver stack portion 102c. In this example, mirror layer 202a, matching layer 212a, and adhesive layer 216a reside between pressure plate region 201b and receiver stack portion 102a. Similarly, in this example, mirror layer 202b, matching layer 212b, and adhesive layer 216b reside between pressure plate region 201c and receiver stack portion 102b. Matching layers 212a and 212b may have acoustic impedance selected to reduce sound wave reflections caused by acoustic impedance contrasts between one or more layers of receiver stack portions 102a and 102b adjacent to or near matching layers 212a and 212b. According to some examples, matching layers 212a and 212b may comprise polyethylene terephthalate (PET). In some examples, adhesive layers 216a and 216b may include pressure-sensitive adhesive (PSA) material.

[0086] exist Figure 2G In the example shown, the device has a thickness (along the z-axis) T1 from the top of the pressure plate to the substrate of the backing layers 230a and 230b, and a thickness T2 from the top of the pressure plate to the substrate of the light source system circuitry. In some examples, T2 may range from 2 mm to 10 mm. According to some examples, T1 may range from 1 mm to 8 mm. The thickness of the backing layers 230a and 230b may range from 3 mm to 7 mm, such as 4.5 mm, 5.0 mm, 5.5 mm, etc. Thus, an embodiment lacking one or more backing layers can be substantially thinner than an embodiment including one or more backing layers.

[0087] Figure 3A , Figure 3B and Figure 3C It shows how it can be arranged. Figure 2G Different examples of some components of the apparatus shown. For the purposes of the other figures provided herein, Figures 3A to 3C The number, type, and arrangement of the components shown are presented by way of example only. In these examples, device 100 is... Figure 1 and Figure 2G Examples of the apparatus 100 shown. In each of these examples, a top view of the apparatus 100 is shown, the view along... Figure 2G The z-axis of the coordinate system shown. In these examples, the light guide component 240a is shown as having a circular cross-section. However, in alternative examples, the light guide component 240a may have different cross-sectional shapes, such as a square cross-section, a rectangular cross-section, a hexagonal cross-section, etc.

[0088] In these examples, the outlines of receiver stack portion 102a and receiver stack portion 102b (and in Figure 3B In the diagram, the outlines of receiver stack portions 102c to 102h are shown in dashed lines, indicating that these elements are below the outer surface 218a of the pressure plate 101. According to these examples, receiver stack portion 102a resides near a first side of the light guide assembly 240a, and receiver stack portion 102b resides near a second side of the light guide assembly 240a. In these examples, receiver stack portion 102a resides near pressure plate region 102b on the first side of pressure plate region 102a (in this example, below that pressure plate region, further away from the observer along the z-axis), and receiver stack portion 102b resides near pressure plate region 102c on the second and opposite side of pressure plate region 102a.

[0089] according to Figure 3A In the example shown, receiver stack portion 102a and receiver stack portion 102b are discrete elements of a linear array of receiver stack portions having N receiver elements, where N is 2 in this example. In an alternative example, N may be greater than 2.

[0090] exist Figure 3B In the example shown, receiver stack portion 102a and receiver stack portion 102b are discrete elements of a two-dimensional receiver array having M receiver elements, where M is 9 in this example. In an alternative example, M may be greater than or less than 9.

[0091] according to Figure 3C In the example shown, receiver stack portions 102a and 102b are portions of receiver stack ring 305a. In this example, receiver stack ring 305a is configured to surround light guide assembly 240a. According to this example, an annular region of pressure plate 301 (which includes pressure plate regions 201b and 201c) near receiver stack ring 305a (in this example, above the receiver stack ring, closer to the observer along the z-axis) is configured to surround pressure plate region 201a.

[0092] Figure 3D The diagram shows the arrangement of additional components. Figure 2G Examples of components of the apparatus shown. For the purposes of the other accompanying figures provided herein, Figure 3D The number, type, and arrangement of the components shown are presented by way of example only. In these examples, device 100 is... Figure 1 An example of device 100 is shown. In this example, a top view of device 100 is shown, the view along... Figure 2G The z-axis of the coordinate system shown. In this example, the light guide component 240a is shown as having a circular cross-section. However, in an alternative example, the light guide component 240a may have a different cross-sectional shape.

[0093] In this example, receiver stack portions 102a and 102b are portions of receiver stack ring 305a. According to this example, receiver stack ring 305a is configured to surround light guide assembly 240a. In this example, receiver stack ring 305a includes receiver stack portions 102a and 102b, and pressure plate regions 201b and 201c. According to this example, receiver stack ring 305b is configured to surround receiver stack ring 305a. In this example, receiver stack ring 305b includes receiver stack portions 102c and 102d, and pressure plate regions 201j and 201k.

[0094] Figure 4 Another example of an array of ultrasonic receiver elements is shown. In this example, the array 402 of ultrasonic receiver elements is a two-dimensional array of ultrasonic receiver elements. According to this example, the array 402 of ultrasonic receiver elements is arranged in a square, with 6 active ultrasonic receiver elements 223 on each side and a total of 36 active ultrasonic receiver elements 223. Each column and each row in the array 402 of ultrasonic receiver elements can be considered as a linear array with 6 active ultrasonic receiver elements 223. For the purposes of other disclosed examples, Figure 4 The types, numbers, sizes, and arrangements of the elements shown and described herein are merely examples. For instance, alternative examples of a two-dimensional array of ultrasonic receiver elements may be arranged in different shapes, such as non-square rectangular shapes, hexagonal shapes, etc. Some alternative examples of a two-dimensional array of ultrasonic receiver elements may include different numbers of active ultrasonic receiver elements 223, such as 16, 20, 25, 30, 32, 36, 40, 48, etc.

[0095] Figure 5 An example of an apparatus configured to perform a receiver-side beamforming process is shown. In this example, the receiver-side beamforming process is a delay-summation beamforming process. Regarding other disclosed examples, Figure 5 The types, numbers, sizes, and arrangements of the elements shown and described herein, as well as the associated methods described herein, are merely examples.

[0096] In this example, the source is shown as emitting ultrasonic waves 501, which are detected by active ultrasonic receiver elements 223a, 223b, and 223c in an array 502 of ultrasonic receiver elements. The array 502 of ultrasonic receiver elements is part of the ultrasonic receiver system 102. In some examples, ultrasonic waves 501 may correspond to the photoacoustic response of a target object to light emitted by the light source system 104 of device 100. In this example, the active ultrasonic receiver elements 223a, 223b, and 223c provide ultrasonic receiver signals 523a, 523b, and 523c to the control system 106, respectively.

[0097] According to this example, the control system 106 includes a delay module 505 and a summing module 510. In this example, the delay module 505 is configured to determine whether a delay should be applied to each of the ultrasonic receiver signals 523a, 523b, and 523c, and if so, what delay to apply. According to this example, the delay module 505 determines that a delay d0 of t2 should be applied to the ultrasonic receiver signal 523a, a delay d1 of t1 should be applied to the ultrasonic receiver signal 523b, and no delay should be applied to the ultrasonic receiver signal 523c. Therefore, the delay module 505 applies the delay of t2 to the ultrasonic receiver signal 523a to generate the ultrasonic receiver signal 523a', and applies the delay of t1 to the ultrasonic receiver signal 523b to generate the ultrasonic receiver signal 523b'.

[0098] In some examples, delay module 505 may determine what delay (if any) to apply to the input ultrasonic receiver signals by performing correlation operations on the input ultrasonic receiver signals. For example, delay module 505 may perform correlation operations on ultrasonic receiver signals 523a and 523c, and may determine that by applying a time offset of t2 to ultrasonic receiver signal 523a, ultrasonic receiver signal 523a will be strongly correlated with ultrasonic receiver signal 523c. Similarly, delay module 505 may perform correlation operations on ultrasonic receiver signals 523b and 523c, and may determine that by applying a time offset of t1 to ultrasonic receiver signal 523b, ultrasonic receiver signal 523b will be strongly correlated with ultrasonic receiver signal 523c.

[0099] According to this example, the summing module 510 is configured to sum the ultrasonic receiver signals 523a', 523b', and 523c, thereby generating a summed signal 520. It can be observed that the amplitude of the summed signal 520 is greater than the amplitude of any one of the ultrasonic receiver signals 523a, 523b, or 523c. In some instances, the signal-to-noise ratio (SNR) of the summed signal 520 may be greater than the SNR of any one of the ultrasonic receiver signals 523a, 523b, or 523c.

[0100] Figure 6 This is a flowchart illustrating some examples of the disclosed operations. Figure 6 The box can be, for example, made of Figure 1 The apparatus 100, the apparatus 100 of FIG. 2, or a similar apparatus may be used. Regarding other methods disclosed herein, Figure 6 The methods outlined herein may include more or fewer boxes than those shown. Furthermore, the boxes in the methods disclosed herein are not necessarily executed in the indicated order. In some instances, Figure 6One or more boxes in the box shown can be executed concurrently.

[0101] In this example, block 605 relates to obtaining a first heart rate waveform via a sensor system of a wearable device in a first wearable device configuration. According to this example, the first wearable device configuration corresponds to a first location of one or more sensors of the sensor system. The first heart rate waveform may be obtained, for example, from a target object (such as a finger, wrist, ankle, etc.), depending on the specific implementation. In some alternative examples, block 605 (or another aspect of method 600) may relate to obtaining a signal corresponding to one or more other targets of interest, such as a signal corresponding to at least a portion of a blood vessel, a signal corresponding to blood within a blood vessel, etc.

[0102] According to this example, box 610 relates to prompting a user to change the wearable device configuration to a second wearable device configuration via the user interface of the wearable device. In this example, the second wearable device configuration corresponds to a second location of one or more sensors of a sensor system. Box 610 may, for example, involve presenting one or more visual cues (such as...) Figures 2B to 2E (One of the illustrated visual cues), presenting one or more audio cues, or a combination thereof.

[0103] According to this example, box 615 relates to obtaining a second heart rate waveform via a sensor system configured as a second wearable device. In some alternative examples, box 615 may relate to obtaining a signal corresponding to one or more other targets of interest.

[0104] In this example, box 620 relates to determining whether to change the wearable device configuration or maintain the current wearable device configuration, based at least in part on a first heart rate waveform and a second heart rate waveform. In some alternative examples, box 620 may relate to determining whether to change the wearable device configuration or maintain the current wearable device configuration, based at least in part on a first instance and a second instance of a signal corresponding to one or more other targets of interest. In some examples, box 620 (or another aspect of method 600) may relate to: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform (or other signal of interest); determining a second SNR corresponding to the second heart rate waveform (or other signal of interest); and comparing the first SNR with the second SNR.

[0105] According to this example, box 625 involves prompting the user via a user interface to change the wearable device configuration or maintain the current wearable device configuration.

[0106] In some examples, method 600 may involve obtaining first to Nth heart rate waveforms (or first to Nth instances of other signals of interest) via a sensor system in first to Nth wearable device configurations, where N is an integer greater than 2. In some such examples, method 600 may involve selecting one of the first to Nth wearable device configurations based at least in part on the first to Nth heart rate waveforms (or first to Nth instances of other signals of interest). In some such examples, method 600 may involve prompting a user via a user interface to change the wearable device configuration to the selected wearable device configuration.

[0107] According to some examples, heart rate waveforms (or other signals of interest) can be obtained via a photoacoustic process. In some such examples, the photoacoustic process may involve: controlling the light source system of a wearable device to direct light to a target part of the user's body; and obtaining an acoustic signal corresponding to the photoacoustic response of the target part of the user's body to the light via the receiver system of the wearable device. Figure 2G Examples are provided in the corresponding descriptions.

[0108] In some examples, method 600 may involve obtaining sensor data at a current pressure applied to a user's body by a wearable device in its current configuration via a sensor system. The sensor data may be obtained, for example, by one or more pressure sensors of sensor system 103. The current pressure may, for example, correspond to a strip, band, or similar mechanism (such as...) used to secure device 100 to a person's arm, wrist, ankle, etc. Figure 2A The tightness of the strip 215 shown. In some examples, method 600 may involve determining, at least in part, whether to prompt the user to change the current pressure to another pressure based on sensor data. For example, method 600 may involve determining, at least in part, whether to prompt the user to tighten or loosen the strip 215 based on sensor data. According to some examples, determining whether to prompt the user to change the current pressure to another pressure may involve determining whether the current pressure is within the desired pressure range.

[0109] According to some examples, determining whether to prompt the user to change the current pressure to another pressure may involve determining whether vasodilation has decreased at the current pressure. For example, if the user has tightened bar 215 (in some instances, according to a prompt caused by the control system) and if the control system determines that sensor data obtained after tightening indicates that vasodilation has decreased at the current pressure, the control system may cause the interface system to provide a prompt to the user to loosen bar 215 compared to a previously measured vasodilation based on a signal obtained at a lower pressure.

[0110] In some examples, a user may use their hand (such as their right hand) to change the configuration of a wearable device worn on their left wrist or elsewhere on their body. In some such instances, the proximity of the hand used to change the wearable device's configuration may cause interference if the user leaves the hand on or near the wearable device while it is acquiring heart rate waveforms or other signals. Therefore, in some examples, method 600 may involve prompting the user via a user interface to retract the hand used to change the wearable device's configuration.

[0111] In some examples, method 600 may involve estimating one or more vascular features based at least in part on signals obtained from sensor system 103. The one or more vascular features may include, for example, vessel diameter, vessel area, vessel profile, vessel dilation, volumetric flow rate, pulse wave velocity, vessel wall thickness, or combinations thereof. In some examples, the one or more vascular features may be arterial features. In some examples, method 600 may involve estimating one or more cardiac features based at least in part on one or more vascular features. According to some such examples, method 600 may involve estimating blood pressure based at least in part on one or more vascular features.

[0112] In some examples, method 600 may involve estimating blood pressure based at least in part on a heart rate waveform obtained by sensor system 103. According to some examples, method 600 may involve extracting and evaluating heart rate waveform features.

[0113] Figure 7 An example of heart rate waveform (HRW) features that can be extracted according to some specific implementations is shown. Figure 7 The horizontal axis represents time, and the vertical axis represents signal amplitude. The cardiac cycle is indicated by the time between adjacent peaks of the HRW (Heart Rate Wave). The systolic and diastolic time intervals are indicated below the horizontal axis. During the systolic phase of the cardiac cycle, as the pulse travels along the artery through a specific location, the arterial wall expands according to the pulse waveform and the elastic properties of the arterial wall. Accompanying this expansion is a corresponding increase in blood volume at the specific location or region, and with the increase in blood volume, one or more properties in that region change accordingly. Conversely, during the diastolic phase of the cardiac cycle, blood pressure in the artery decreases and the arterial wall constricts. Accompanying this constriction is a corresponding decrease in blood volume at the specific location, and with the decrease in blood volume, one or more properties in that region change accordingly.

[0114] Figure 7The illustrated HRW features represent the width of the contraction and / or diastolic portions of the HRW curve at different "heights," expressed as a percentage of the maximum amplitude. For example, the SW50 feature is the width of the contraction portion of the HRW curve at a "height" of 50% of the maximum amplitude. In some embodiments, the HRW features used for blood pressure estimation may include some or all of the HRW features SW10, SW25, SW33, SW50, SW66, SW75, DW10, DW25, DW33, DW50, DW66, and DW75. In other embodiments, additional HRW features may be used for blood pressure estimation. In some instances, such additional HRW features may include the sum and ratio of SW and DW at one or more “heights,” such as (DW75 + SW75), DW75 / SW75, (DW66 + SW66), DW66 / SW66, (DW50 + SW50), DW50 / SW50, (DW33 + SW33), DW33 / SW33, (DW25 + SW25), DW25 / SW25, and / or (DW10 + SW10), DW10 / SW10. Other implementations may use other HRW features for blood pressure estimation. In some instances, such additional HRW features may include sums, differences, ratios, and / or other calculations based on more than one “height,” such as (DW75 + SW75) / (DW50 + SW50), (DW50 + SW50 / (DW10 + SW10), etc.

[0115] Figure 8 An example of a device that can be used in a system for estimating blood pressure based at least in part on pulse transit time (PTT) is shown. The number, type, and arrangement of elements are presented by way of example only, as far as the other figures provided herein are concerned. According to this example, system 800 includes at least two sensors. In this example, system 800 includes at least an electrocardiogram sensor 805 and a device 810 configured to be mounted on a finger of a person 801. In this example, device 810 is an apparatus configured to perform at least some of the PAPG methods disclosed herein, or includes such an apparatus. For example, device 810 may be device 300 of FIG. 3 or a similar apparatus, or may include such an apparatus or a similar apparatus.

[0116] As shown in Figure 820, PAT comprises two components: the pre-ejection phase (PEP, the time required to convert the electrical signal into mechanical pumping force and isovolumetric contraction to open the aortic valve) and PTT. The start time of PAT can be estimated based on the QRS complex (the electrical signal characteristics of ventricular electrical stimulation). As shown in Figure 820, in this example, the start of the pulse arrival time (PAT) can be calculated based on the R-wave peak measured by the ECG sensor 805, and the end of PAT can be detected by analysis of the signal provided by the device 810. In this example, it is assumed that the end of PAT corresponds to the intersection between the tangent of the local minimum detected by the device 810 and the tangent of the maximum slope / first derivative of the sensor signal after the minimum time.

[0117] There are many known blood pressure estimation algorithms based on PTT and / or PAT, some of which are outlined in Table 1 and described in their corresponding texts on pages 5 through 10 of Cuff-Less and Continuous Blood Pressure Monitoring: A Methodological Review (“Sharma”) published by Sharma, M. et al. in Multidisciplinary Digital Publishing Institute (MDPI) Technologies 2017, 5, 21, both of which are hereby incorporated by reference.

[0118] Some previously disclosed methods have involved calculating blood pressure based on PTT and / or PAT measured by a sensor system including a PPG sensor, according to one or more equations in Sharma's Table 1 or other known equations. As noted above, some disclosed PAPG-based implementations are configured to distinguish arterial HRW from other HRWs. Such implementations provide more accurate PTT and / or PAT measurements compared to those measured by a PPG sensor. Therefore, the disclosed PAPG-based implementations provide more accurate blood pressure estimates, even when the blood pressure estimate is based on previously known formulas.

[0119] Other embodiments of system 800 may not include electrocardiogram sensor 805. In some such embodiments, device 815 configured to be mounted on the wrist of person 801 may be an apparatus configured to perform at least some of the PAPG methods disclosed herein, or may include such an apparatus. For example, device 815 may be device 100 of FIG. 2 or a similar apparatus, or may include such an apparatus or a similar apparatus. According to some such examples, device 815 may include a light source system and two or more ultrasound receivers. Reference is made below. Figure 10ADescribe an example. In some examples, device 815 may include an array of ultrasonic receivers.

[0120] In some specific embodiments of system 800 that does not include electrocardiogram sensor 805, device 810 may include a light source system and two or more ultrasound receivers. See below for reference. Figure 10B Describe an example.

[0121] Figure 9 A schematic cross-sectional side view showing a portion of the artery 900 through which the pulse 902 propagates. Figure 9 The boxed arrows in the diagram indicate the direction of blood flow and pulse propagation. As schematically shown, the propagating pulse 902 causes strain in the arterial wall 904, which manifests as an expansion (referred to as "dilation") in the diameter (and therefore cross-sectional area) of the arterial wall. The actual spatial length L of the propagating pulse along the artery (in the direction of blood flow) is typically comparable to the length of a limb, such as the distance from the subject's shoulder to their wrist or fingers, and is usually less than one meter (m). However, the length L of the propagating pulse can vary considerably between different subjects and, for a given subject, may vary significantly over time depending on various factors. The spatial length L of the pulse will generally decrease with increasing distance from the heart until the pulse reaches the capillaries.

[0122] As described above, certain specific implementations involve devices, systems, and methods for estimating blood pressure or other cardiovascular characteristics based on estimations of arterial dilation waveforms. Unless otherwise indicated, the terms “estimate,” “measure,” “calculate,” “infer,” “derive,” “evaluate,” “determine,” and “monitor” are used interchangeably herein where appropriate. Similarly, derivatives of the roots of these terms are used interchangeably where appropriate; for example, the terms “estimate,” “measure,” “calculate,” “infer,” and “determine” are used interchangeably herein. In some implementations, the pulse wave velocity (PWV) of the propagating pulse can be estimated by measuring its pulse transit time (PTT) as the pulse travels from a first physical location along the artery to a second physical location further distal along the artery. It should be understood that this PTT differs from the PTT described above with reference to Figure 15. However, either version of the PTT can be used for the purpose of blood pressure estimation. The physical distance between the first and second physical locations is assumed. It is deterministic; PWV can be estimated as the physical spatial distance the pulse travels. Divide by the distance the pulse travels through physical space The quotient of the time taken (PTT). Typically, a first sensor located at a first physical location is used to determine the start time of the pulse's arrival or propagation through the first physical location (also referred to herein as the "first time location"). A second sensor located at a second physical location is used to determine the end time of the pulse's arrival or propagation through the second physical location and continuing through the remainder of the arterial branch (also referred to herein as the "second time location"). In such examples, PTT represents the time distance (or time difference) between the first time location and the second time location (start time and end time).

[0123] The fact that arterial dilation waveforms are measured at two different physical locations means that the estimated PWV inevitably represents the total path distance traveled by the pulse between the first and second physical locations. The average value is calculated based on blood density. More specifically, PWV typically depends on several factors, including blood density. Arterial wall stiffness (or conversely, elasticity), arterial diameter, arterial wall thickness, and blood pressure. Because both arterial wall elasticity and baseline resting diameter (e.g., the diameter at the end of ventricular diastole) vary significantly throughout the arterial system, the PWV estimate obtained from a PTT measurement is essentially an average (the total path length between the two locations where the measurement was performed). (Take the average from above).

[0124] In conventional methods for acquiring pulse wave velocity (PWV), electrocardiogram (ECG) sensors (which detect electrical signals from the heart) have been used to obtain the onset time of the pulse at the heart. For example, the onset time can be estimated based on the QRS complex (the electrical signal characteristics of ventricular electrical stimulation). In such methods, different sensors positioned at a second location (e.g., the finger) are typically used to obtain the end time of the pulse. As those skilled in the art will understand, there are numerous arterial discontinuities, branches, and variations along the entire path from the heart to the finger. Variations in PWV can reach or exceed one order of magnitude along various extensions of the entire path from the heart to the finger. Therefore, PWV estimations based on such a long path length are unreliable.

[0125] In the various specific embodiments described herein, PPT estimation is obtained based on measurements associated with an arterial dilation signal (also referred to as "arterial dilation data" or more commonly "sensor data"), obtained by each of a first arterial dilation sensor 906 and a second arterial dilation sensor 908, respectively, along the artery of interest near a first physical location and a second physical location. In some specific embodiments, the first arterial dilation sensor 906 and the second arterial dilation sensor 908 are advantageously positioned near the first and second physical locations, between which arterial properties of the artery of interest, such as wall elasticity and diameter, can be considered or assumed to be relatively constant. In this way, PWV calculated based on PTT estimation is more representative of the actual PWV along a specific segment of the artery. Furthermore, blood pressure estimated based on PWV... This better represents true blood pressure. In some specific implementations, the separation distance between the first arterial dilation sensor 906 and the second arterial dilation sensor 908... The magnitude of the pulse (and therefore the distance between the first and second positions along the artery) can range from about 1 centimeter (cm) to tens of centimeters, long enough to distinguish the arrival of the pulse at the first physical position from the arrival of the pulse at the second physical position, but close enough to ensure arterial consistency. In some specific embodiments, the distance between the first arterial dilation sensor 906 and the second arterial dilation sensor 908... The distance can be in the range of approximately 1 cm to approximately 30 cm, and in some embodiments, less than or equal to approximately 20 cm, and in some embodiments, less than or equal to approximately 10 cm, and in some specific embodiments, less than or equal to approximately 5 cm. In some other embodiments, the distance between the first arterial dilation sensor 906 and the second arterial dilation sensor 908... The distance can be less than or equal to 1 cm, for example, about 0.1 cm, about 0.25 cm, about 0.5 cm, or about 0.75 cm. For reference, a typical PWV can be about 15 m / s. Using a distance of about 5 cm between the first arterial dilation sensor 906 and the second arterial dilation sensor 908, and assuming a PWV of about 15 m / s means a PTT of about 3.3 ms for dynamic monitoring devices.

[0126] The distance between the first arterial dilation sensor 906 and the second arterial dilation sensor 908 The values ​​of the pulse can be pre-programmed into the memory within the monitoring device that integrates the sensors (e.g., the memory of the control system 306 described above with reference to FIG3, or a memory configured to communicate with that memory). As those skilled in the art will understand, in such an embodiment, the spatial length L of the pulse can be greater than the distance from the first arterial dilation sensor 906 to the second arterial dilation sensor 908. Therefore, although Figure 9 The illustrated pulse 902 is shown as having a spatial length L equivalent to the distance between the first arterial dilation sensor 906 and the second arterial dilation sensor 908, but in reality, each pulse can typically have a distance greater than and even much greater than (e.g., about an order of magnitude or more) the distance between the first arterial dilation sensor 906 and the second arterial dilation sensor 908. The spatial length L.

[0127] Sensing architecture and topology

[0128] In some embodiments of the dynamic monitoring device disclosed herein, the first arterial dilation sensor 906 and the second arterial dilation sensor 908 are both sensors of the same sensor type. In some such embodiments, the first arterial dilation sensor 906 and the second arterial dilation sensor 908 are identical sensors. In such embodiments, each of the first arterial dilation sensor 906 and the second arterial dilation sensor 908 utilizes the same sensor technology with the same sensitivity to arterial dilation signals caused by propagating pulses, and has the same time delay and sampling characteristics. In some embodiments, each of the first arterial dilation sensor 906 and the second arterial dilation sensor 908 is configured for, for example, photoacoustic volumetric plethysmography (PAPG) sensing as disclosed elsewhere herein. Some such embodiments include a light source system and two or more ultrasonic receivers, which may be examples of the light source system 304 and receiver system 302 of FIG. 3. In some embodiments, each of the first arterial dilation sensor 906 and the second arterial dilation sensor 908 is configured for ultrasonic sensing via the transmission of ultrasonic signals and the reception of corresponding reflections. In some alternative embodiments, each of the first arterial dilation sensor 906 and the second arterial dilation sensor 908 may be configured for impedance plethysmography (IPG) sensing, also known in a biomedical context as bioimpedance sensing. In various embodiments, regardless of the type of sensor used, each of the first arterial dilation sensor 906 and the second arterial dilation sensor 908 functions broadly to capture and provide arterial dilation data indicating an arterial dilation signal generated by the propagation of a pulse through a portion of the artery adjacent to the corresponding sensor. For example, the arterial dilation data may be provided from the sensor to the processor in the form of a voltage signal generated or received by the sensor based on an ultrasound signal or impedance signal sensed by the corresponding sensor.

[0129] As described above, during the systolic phase of the cardiac cycle, as the pulse travels along the artery through a specific location, the arterial wall expands according to the pulse waveform and the elastic properties of the arterial wall. This expansion is accompanied by a corresponding increase in blood volume at that specific location or region, and with this increase in blood volume, one or more properties in that region change accordingly. Conversely, during the diastolic phase of the cardiac cycle, blood pressure in the artery decreases and the arterial wall constricts. This constriction is accompanied by a corresponding decrease in blood volume at that specific location, and with this decrease in blood volume, one or more properties in that region change accordingly.

[0130] In the context of bioimpedance sensing (or impedance plethysmography), blood in an artery has a higher conductivity than the surrounding or adjacent skin, muscle, fat, tendons, ligaments, bone, lymph, or other tissues. The susceptivity (and therefore dielectric constant) of blood also differs from that of other types of surrounding or nearby tissues. As a pulse propagates through a location, the corresponding increase in blood volume results in an increase in conductivity (and more generally, an increase in admittance, or equivalently, a decrease in impedance) at that location. Conversely, during the diastolic phase of the cardiac cycle, the corresponding decrease in blood volume results in an increase in resistivity (and more generally, an increase in impedance, or equivalently, a decrease in admittance) at that location.

[0131] Bioimpedance sensors typically function by applying an electrically excited signal at an excitation carrier frequency to a region of interest via two or more input electrodes and detecting an output signal (or multiple output signals) via two or more output electrodes. In some more specific embodiments, the electrically excited signal is a current signal injected into the region of interest via the input electrodes. In some such embodiments, the output signal is a voltage signal representing the voltage response of the tissue in the region of interest to the applied excitation signal. The detected voltage response signal is influenced by the different (and in some instances time-varying) electrical properties of the various tissues through which the injected excitation current signal passes. In some embodiments where the bioimpedance sensor is operable to monitor blood pressure, heart rate, or other cardiovascular characteristics, the detected voltage response signal is amplitude and phase modulated by the time-varying impedance (or conversely, admittance) of the underlying artery, as described above, which fluctuates in sync with the user's heartbeat. To determine various biological characteristics, information from the detected voltage response signal is typically demodulated from the excitation carrier frequency component using various analog or digital signal processing circuits, which may include passive and active components.

[0132] In some examples of incorporating ultrasound sensors, the measurement of arterial dilation may involve, for example, guiding ultrasound waves into the limb toward the artery via one or more ultrasound transducers. Such ultrasound sensors are also configured to receive reflected waves, at least in part based on the guided waves. The reflected waves may include scattered waves, specular reflections, or both. The reflected waves provide information about the arterial wall and, therefore, information about arterial dilation.

[0133] In some specific implementations, regardless of the type of sensor used for the first arterial dilation sensor 906 and the second arterial dilation sensor 908, both the first arterial dilation sensor 906 and the second arterial dilation sensor 908 may be arranged, assembled, or otherwise included within a single housing of a single dynamic monitoring device. As described above, the housing and other components of the monitoring device may be configured such that when the monitoring device is fixed or otherwise physically coupled to a subject, the first arterial dilation sensor 906 and the second arterial dilation sensor 908 are in contact with or near the user's skin at a first position and a second position, respectively, at a distance from each other. Furthermore, in some embodiments, it may be assumed that the various arterial properties along the arterial extension are relatively constant. In various embodiments, the housing of the dynamic monitoring device is a wearable housing, incorporated into a wearable housing, or integrated with a wearable housing. In some specific embodiments, the wearable housing includes a physical coupling mechanism (or connection thereto) for detachable, non-invasive attachment to the user. The housing can be formed using any process from a variety of suitable manufacturing processes, including injection molding and vacuum forming. Additionally, the housing can be made from any of a variety of suitable materials, including but not limited to plastics, metals, glass, rubber, and ceramics, or combinations of these or other materials. In certain embodiments, the housing and coupling mechanism enable fully dynamic use. In other words, some embodiments of the wearable monitoring device described herein are non-invasive, non-physically inhibiting, and generally do not restrict the free and uninhibited movement of the subject's arms or legs, enabling continuous or periodic monitoring of cardiovascular characteristics, such as blood pressure, even when the subject is moving or otherwise engaging in physical activity. Therefore, dynamic monitoring devices facilitate and enable long-term wear and monitoring (e.g., uninterrupted for days, weeks, or a month or longer) of one or more biometric features to obtain a better picture of such features over extended periods, and generally, a better picture of the user's health.

[0134] In some implementations, motion monitoring devices can be positioned around the user's wrist using a strip or band, similar to a watch or fitness / activity tracker. Figure 10A An example dynamic monitoring device 1000 designed to be worn on the wrist is shown according to some specific embodiments. In the illustrated example, the monitoring device 1000 includes a housing 1002 integrally formed, coupled, or otherwise integrated with a wristband 1004. In some instances, a first arterial dilation sensor 1006 and a second arterial dilation sensor 1008 may each include the components referenced above. Figure 1The described example is an instance of an ultrasound receiver system 102 and part of a light source system 104. In this example, a dynamic monitoring device 1000 is coupled around the wrist, such that a first arterial dilation sensor 1006 and a second arterial dilation sensor 1008 within the housing 1002 are each positioned along a segment of the radial artery 1010 (it should be noted that the sensors are typically concealed when viewed from the exterior or outer surface of the housing facing the subject, while the monitoring device is coupled to the subject but exposed on the inner surface of the housing so that the sensors can obtain measurements from the underlying artery through the subject's skin). Also as shown, the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 are separated by a fixed distance. In some other specific implementations, the dynamic monitoring device 1000 may similarly be designed or adapted to locate the forearm, upper arm, ankle, calf, thigh, or fingers (all of which are referred to below as "limbs") using strips or bands.

[0135] Figure 10B An example dynamic monitoring device 1000 designed to be worn on a finger is shown according to some specific embodiments. In some instances, a first arterial dilation sensor 1006 and a second arterial dilation sensor 1008 may each include the components referenced above. Figure 1 An example of the described ultrasonic receiver 102 and part of the light source system 104.

[0136] In some other embodiments, the dynamic monitoring device disclosed herein can be positioned on a user’s area of ​​interest without the use of strips or bands. For example, the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008, along with other components of the monitoring device, can be enclosed in a housing that is secured to the user’s skin in the area of ​​interest using an adhesive or other suitable attachment mechanism (an example of a “patch” monitoring device).

[0137] Figure 10C An example motion monitoring device 1000, designed to reside on an earbud according to some specific embodiments, is shown. According to this example, the motion monitoring device 1000 is coupled to the housing of an earbud 1020. In some instances, a first arterial dilation sensor 1006 and a second arterial dilation sensor 1008 may each include the references above. Figure 1 An example of the described ultrasonic receiver 102 and part of the light source system 104.

[0138] Specific implementation examples are described in the following numbered clauses:

[0139] 1. A method comprising: obtaining a first heart rate waveform via a sensor system of a wearable device in a first wearable device configuration, the first wearable device configuration corresponding to a first location of one or more sensors of the sensor system; prompting a user via a user interface of the wearable device to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system; obtaining a second heart rate waveform via the sensor system in the second wearable device configuration; determining, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform; and prompting the user via the user interface to change the wearable device configuration or maintain the current wearable device configuration.

[0140] 2. The method according to Clause 1, wherein the determination further comprises: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determining a second SNR corresponding to the second heart rate waveform; and comparing the first SNR with the second SNR.

[0141] 3. The method according to Clause 1 or Clause 2, wherein the method further comprises: obtaining first to Nth heart rate waveforms via the sensor system in first to Nth wearable device configurations, where N is an integer greater than 2; selecting one of the first to Nth wearable device configurations based at least in part on the first to Nth heart rate waveforms; and prompting the user via the user interface to change the wearable device configuration to the selected wearable device configuration.

[0142] 4. The method according to any one of clauses 1 to 3, wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

[0143] 5. The method according to Clause 4, wherein the photoacoustic process involves: controlling the light source system of the wearable device to direct light to a target part of the user's body; and obtaining an acoustic signal corresponding to the photoacoustic response of the target part of the user's body to the light via the receiver system of the wearable device.

[0144] 6. The method according to any one of clauses 1 to 5, the method further comprising: obtaining sensor data at a current pressure, the current pressure being applied to a user's body by the wearable device in the current wearable device configuration; and determining, at least in part, based on the sensor data, whether to prompt the user to change the current pressure to another pressure.

[0145] 7. The method according to Clause 6, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether the current pressure is within the desired pressure range.

[0146] 8. The method according to Clause 6 or Clause 7, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether vasodilation has been reduced at the current pressure.

[0147] 9. The method according to any one of clauses 1 to 8, the method further comprising: prompting the user to retract the hand used to change the configuration of the wearable device via the user interface.

[0148] 10. The method according to any one of clauses 1 to 9, further comprising: estimating blood pressure based at least in part on a heart rate waveform obtained by the sensor system.

[0149] 11. A wearable device, the wearable device comprising: a sensor system configured to obtain a heart rate waveform from a user of the wearable device, the sensor system being adjustable according to multiple wearable device configurations; a user interface system; and a control system configured to: obtain a first heart rate waveform via the sensor system in a first wearable device configuration, the first wearable device configuration corresponding to a first location of one or more sensors of the sensor system; control the user interface system to prompt the user to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system; obtain a second heart rate waveform via the sensor system in the second wearable device configuration; determine, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform; and control the user interface system to prompt the user to change the wearable device configuration or maintain the current wearable device configuration.

[0150] 12. The wearable device according to Clause 11, wherein the determination further comprises: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determining a second SNR corresponding to the second heart rate waveform; and comparing the first SNR with the second SNR.

[0151] 13. The wearable device according to Clause 11 or Clause 12, wherein the control system is further configured to: obtain first to Nth heart rate waveforms via the sensor system in first to Nth wearable device configurations, where N is an integer greater than 2; select one of the first to Nth wearable device configurations at least in part based on the first to Nth heart rate waveforms; and control the user interface system to prompt the user to change the wearable device configuration to the selected wearable device configuration.

[0152] 14. The wearable device according to any one of clauses 11 to 13, wherein the sensor system includes a photoacoustic sensor system, and wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

[0153] 15. The wearable device according to Clause 14, wherein the photoacoustic sensor system includes a light source system and a receiver system, and wherein the photoacoustic process involves: controlling the light source system to direct light to a target part of the user's body; and obtaining an acoustic signal corresponding to the photoacoustic response of the target part of the user's body to the light via the receiver system of the wearable device.

[0154] 16. The wearable device according to any one of clauses 11 to 15, wherein the control system is further configured to: acquire sensor data at a current pressure applied to a user's body by the wearable device in the current wearable device configuration; and determine, at least in part, whether to prompt the user to change the current pressure to another pressure based on the sensor data.

[0155] 17. The wearable device according to Clause 16, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether the current pressure is within the desired pressure range.

[0156] 18. The wearable device according to Clause 16 or Clause 17, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether vasodilation has been reduced under the current pressure.

[0157] 19. The wearable device according to any one of clauses 11 to 18, wherein the control system is further configured to: control the user interface system to prompt the user to retract the hand used to change the configuration of the wearable device.

[0158] 20. The wearable device according to any one of clauses 11 to 19, wherein the control system is further configured to estimate blood pressure at least in part based on the heart rate waveform obtained by the sensor system.

[0159] 21. The wearable device according to any one of Clauses 11 to 20, wherein the control system is further configured to: determine a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determine whether the first SNR is equal to or exceeds an SNR threshold; and, in response to determining that the first SNR is equal to or exceeds the SNR threshold, control the user interface system to prompt the user to maintain the current wearable device configuration.

[0160] 22. A wearable device, the wearable device comprising: a sensor system configured to acquire a heart rate waveform from a user of the wearable device, the sensor system being adjustable according to multiple wearable device configurations; a user interface system; and a control unit configured to: acquire a first heart rate waveform via the sensor system in a first wearable device configuration, the first wearable device configuration corresponding to a first location of one or more sensors of the sensor system; control the user interface system to prompt the user to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system; acquire a second heart rate waveform via the sensor system in the second wearable device configuration; determine, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform; and control the user interface system to prompt the user to change the wearable device configuration or maintain the current wearable device configuration.

[0161] 23. The wearable device according to Clause 22, wherein the determination further comprises: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determining a second SNR corresponding to the second heart rate waveform; and comparing the first SNR with the second SNR.

[0162] 24. The wearable device according to Clause 22 or Clause 23, wherein the control component includes components for: obtaining first to Nth heart rate waveforms via the sensor system in first to Nth wearable device configurations, where N is an integer greater than 2; selecting one of the first to Nth wearable device configurations based at least in part on the first to Nth heart rate waveforms; and controlling the user interface system to prompt the user to change the wearable device configuration to the selected wearable device configuration.

[0163] 25. The wearable device according to any one of clauses 22 to 24, wherein the sensor system includes a photoacoustic sensor system, and wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

[0164] 26. One or more computer-readable nontransitory media having instructions stored thereon for controlling one or more devices to perform a method, the method comprising: obtaining a first heart rate waveform in a first wearable device configuration via a sensor system of a wearable device, the first wearable device configuration corresponding to a first location of one or more sensors of the sensor system; prompting a user via a user interface of the wearable device to change the wearable device configuration to a second wearable device configuration, the second wearable device configuration corresponding to a second location of one or more sensors of the sensor system; obtaining a second heart rate waveform in the second wearable device configuration via the sensor system; determining, at least in part, whether to change the wearable device configuration or maintain the current wearable device configuration based on the first heart rate waveform and the second heart rate waveform; and prompting the user via the user interface to change the wearable device configuration or maintain the current wearable device configuration.

[0165] 27. One or more computer-readable non-transient media as described in Clause 26, wherein the determination further comprises: determining a first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; determining a second SNR corresponding to the second heart rate waveform; and comparing the first SNR with the second SNR.

[0166] 28. One or more computer-readable nontransient media as described in Clause 26 or Clause 27, wherein the method further comprises: obtaining first to Nth heart rate waveforms via the sensor system in first to Nth wearable device configurations, where N is an integer greater than 2; selecting one of the first to Nth wearable device configurations based at least in part on the first to Nth heart rate waveforms; and prompting the user via the user interface to change the wearable device configuration to the selected wearable device configuration.

[0167] 29. One or more computer-readable nontransient media according to any one of Clauses 26 to 28, wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

[0168] 30. One or more computer-readable nontransient media as described in Clause 29, wherein the photoacoustic process involves: controlling a light source system of the wearable device to direct light to a target portion of a user's body; and obtaining an acoustic signal corresponding to the photoacoustic response of the target portion of the user's body to the light via a receiver system of the wearable device.

[0169] As used in this article, the phrase “at least one of the items” refers to any combination of these items, including a single member. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc.

[0170] The various exemplary logics, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the specific implementations disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. The interchangeability of hardware and software has been broadly described in terms of functionality and illustrated in the aforementioned exemplary components, blocks, modules, circuits, and processes. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0171] Hardware and data processing means for implementing the various exemplary logic units, logic blocks, modules, and circuits described herein can be implemented or executed using general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic units, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some specific implementations, specific processes and methods can be performed by circuitry specific to a given function.

[0172] In one or more aspects, the described functionality may be implemented in hardware, digital electronic circuits, computer software, firmware, including the structures disclosed in this specification and their structural equivalents or any combination thereof. Specific implementations of the subject matter described in this specification may also be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a computer storage medium for execution by a data processing apparatus or for controlling the operation of a data processing apparatus.

[0173] If implemented in software, the functions can be stored as one or more instructions or codes on or transmitted via a computer-readable medium such as a non-transitory medium. The processes of the methods or algorithms disclosed herein can be implemented in a processor-executable software module that can reside on a computer-readable medium. Computer-readable media include both computer storage media and communication media, including any medium capable of transferring a computer program from one location to another. Storage media can be any available medium accessible to a computer. By way of example and not limitation, non-transitory media can include RAM, ROM, EEPROM, CD-ROM or other optical disc storage devices, disk storage devices or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and is accessible to a computer. Additionally, any connection can be appropriately referred to as a computer-readable medium. As used herein, disks and optical discs include compact optical discs (CDs), laser discs, optical discs, digital versatile optical discs (DVDs), floppy disks, and Blu-ray discs, wherein disks typically magnetically reproduce data, while optical discs optically reproduce data using lasers. Combinations of the above should also be included within the scope of computer-readable media. In addition, the operation of a method or algorithm may reside as a set of code and instructions or any combination of code and instructions on a machine-readable medium and a computer-readable medium that may be incorporated into a computer program product.

[0174] Various modifications to the specific embodiments described herein may be apparent to those skilled in the art, and the general principles defined herein may be applied to other specific embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the specific embodiments shown herein, but is to be accorded the widest scope consistent with the claims, principles, and novel features disclosed herein. The word “exemplary” (if any) is used herein specifically to mean “serving as an example, instance, or illustration.” Any specific embodiment described herein as “exemplary” is not necessarily to be construed as superior to or better than other specific embodiments.

[0175] Certain features described in this specification in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although features may be described above as operating in certain combinations and even originally claimed in this way, one or more features from the claimed combination may be removed from that combination in some cases, and the claimed combination may be for sub-combinations or variations thereof.

[0176] Similarly, although operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed in the shown specific order or sequential order, or to perform all illustrated operations to achieve the desired result. In some environments, multitasking and parallel processing are advantageous. Furthermore, the separation of the various system components in the embodiments described above should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired result.

[0177] It should be understood that unless features in any particular embodiment of the description are explicitly identified as incompatible with each other, or the surrounding context suggests that they are mutually exclusive and not easily combined in a complementary and / or supporting sense, the general conception and ideas of this disclosure may be selectively combined with specific features of those complementary embodiments to provide one or more comprehensive but slightly different technical solutions. Therefore, it should also be understood that the above description is given by way of example only and may be modified in detail within the scope of this disclosure.

[0178] Various modifications to the specific embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other specific embodiments without departing from the spirit or scope of this disclosure. Therefore, the following claims are not intended to be limited to the specific embodiments shown herein, but should be granted the broadest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0179] Additionally, some features described in this specification in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, individual features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although some features are described above as working in a particular combination and even initially claimed in this way, in some cases, one or more features from the claimed combination may be separated from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0180] Similarly, although operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed in the indicated specific order or sequential order, or to perform all illustrated operations to achieve the desired result. Furthermore, the drawings may schematically depict one or more example processes in the form of flowcharts. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. Moreover, the various operations in the described and illustrated operations may themselves include and collectively refer to several sub-operations. For example, each operation in the operations described above may itself involve the execution of a process or algorithm. Furthermore, in some embodiments, the various operations in the described and illustrated operations may be combined or performed in parallel. Similarly, the separation of various system components in the embodiments described above should not be construed as requiring such separation in all embodiments. Therefore, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result.

Claims

1. A method, the method comprising: A first heart rate waveform is obtained via a sensor system of a wearable device in a first wearable device configuration, the first wearable device configuration corresponding to a first position of one or more sensors of the sensor system; The user is prompted via the user interface of the wearable device to change the wearable device configuration to a second wearable device configuration, which corresponds to a second location of one or more sensors of the sensor system; A second heart rate waveform is obtained via the sensor system in the configuration of the second wearable device; The determination of whether to change the wearable device configuration or maintain the current wearable device configuration is based at least in part on the first heart rate waveform and the second heart rate waveform. as well as The user is prompted via the user interface to change the wearable device configuration or maintain the current wearable device configuration.

2. The method according to claim 1, wherein the determination further comprises: Determine the first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; Determine the second SNR corresponding to the second heart rate waveform; as well as Compare the first SNR with the second SNR.

3. The method according to claim 1, wherein the method further comprises: The first to Nth heart rate waveforms are obtained via the sensor system in the configuration of the first to Nth wearable devices, where N is an integer greater than 2; The selection of one of the first to Nth wearable device configurations is based at least in part on the first to Nth heart rate waveforms; as well as The user is prompted via the user interface to change the wearable device configuration to the selected wearable device configuration.

4. The method of claim 1, wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

5. The method of claim 4, wherein the photoacoustic process involves: The wearable device's light source system is controlled to direct light to a target part of the user's body; and Acoustic signals corresponding to the photoacoustic response of the target part of the user's body to the light are obtained via the receiver system of the wearable device.

6. The method according to claim 1, further comprising: Obtain sensor data under the current pressure, which is applied to the user's body by the wearable device in the current wearable device configuration; as well as The determination of whether to prompt the user to change the current pressure to another pressure is based at least in part on the sensor data.

7. The method of claim 6, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether the current pressure is within a desired pressure range.

8. The method of claim 6, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether vasodilation has been reduced under the current pressure.

9. The method according to claim 1, further comprising: The user is prompted via the user interface to retract the hand used to change the configuration of the wearable device.

10. The method according to claim 1, further comprising: Blood pressure is estimated at least in part based on the heart rate waveform obtained by the sensor system.

11. A wearable device, the wearable device comprising: A sensor system configured to obtain heart rate waveforms from a user of the wearable device, the sensor system being adjustable for various wearable device configurations; User interface system; and The control system is configured to: A first heart rate waveform is obtained via the sensor system in a first wearable device configuration, the first wearable device configuration corresponding to a first position of one or more sensors of the sensor system; The user interface system prompts the user to change the wearable device configuration to a second wearable device configuration, which corresponds to a second location of one or more sensors of the sensor system. A second heart rate waveform is obtained via the sensor system in the configuration of the second wearable device; The determination of whether to change the wearable device configuration or maintain the current wearable device configuration is based at least in part on the first heart rate waveform and the second heart rate waveform. as well as The user interface system prompts the user to change the wearable device configuration or maintain the current wearable device configuration.

12. The wearable device of claim 11, wherein the determination further comprises: Determine the first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; Determine the second SNR corresponding to the second heart rate waveform; as well as Compare the first SNR with the second SNR.

13. The wearable device of claim 11, wherein the control system is further configured to: The first to Nth heart rate waveforms are obtained via the sensor system in the configuration of the first to Nth wearable devices, where N is an integer greater than 2; The selection of one of the first to Nth wearable device configurations is based at least in part on the first to Nth heart rate waveforms; as well as The user interface system prompts the user to change the wearable device configuration to the selected wearable device configuration.

14. The wearable device of claim 11, wherein the sensor system comprises a photoacoustic sensor system, and wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

15. The wearable device of claim 14, wherein the photoacoustic sensor system comprises a light source system and a receiver system, and wherein the photoacoustic process involves: The control system directs light to the target part of the user's body; and Acoustic signals corresponding to the photoacoustic response of the target portion of the user's body to the light are obtained via the receiver system of the wearable device.

16. The wearable device of claim 11, wherein the control system is further configured to: Obtain sensor data at the current pressure, which is applied to the user's body by the wearable device in the current wearable device configuration; and The determination of whether to prompt the user to change the current pressure to another pressure is based at least in part on the sensor data.

17. The wearable device of claim 16, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether the current pressure is within a desired pressure range.

18. The wearable device of claim 16, wherein determining whether to prompt the user to change the current pressure to another pressure involves determining whether vasodilation has been reduced under the current pressure.

19. The wearable device of claim 11, wherein the control system is further configured to: control the user interface system to prompt the user to retract their hand used to change the configuration of the wearable device.

20. The wearable device of claim 11, wherein the control system is further configured to estimate blood pressure at least in part based on the heart rate waveform obtained by the sensor system.

21. The wearable device of claim 11, wherein the control system is further configured to: Determine the first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; Determine whether the first SNR is equal to or exceeds the SNR threshold; and In response to determining that the first SNR is equal to or exceeds the SNR threshold, the user interface system is controlled to prompt the user to maintain the current wearable device configuration.

22. A wearable device, the wearable device comprising: A sensor system configured to obtain heart rate waveforms from a user of the wearable device, the sensor system being adjustable for various wearable device configurations; User interface system; and Control component, the control component being used for: A first heart rate waveform is obtained via the sensor system in a first wearable device configuration, the first wearable device configuration corresponding to a first position of one or more sensors of the sensor system; The user interface system prompts the user to change the wearable device configuration to a second wearable device configuration, which corresponds to a second location of one or more sensors of the sensor system. A second heart rate waveform is obtained via the sensor system in the configuration of the second wearable device; The determination of whether to change the wearable device configuration or maintain the current wearable device configuration is based at least in part on the first heart rate waveform and the second heart rate waveform. as well as The user interface system prompts the user to change the wearable device configuration or maintain the current wearable device configuration.

23. The wearable device of claim 22, wherein the determination further comprises: Determine the first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; Determine the second SNR corresponding to the second heart rate waveform; as well as Compare the first SNR with the second SNR.

24. The wearable device of claim 22, wherein the control component includes components for performing the following actions: The first to Nth heart rate waveforms are obtained via the sensor system in the configuration of the first to Nth wearable devices, where N is an integer greater than 2; The selection of one of the first to Nth wearable device configurations is based at least in part on the first to Nth heart rate waveforms; as well as The user interface system prompts the user to change the wearable device configuration to the selected wearable device configuration.

25. The wearable device of claim 22, wherein the sensor system comprises a photoacoustic sensor system, and wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

26. One or more computer-readable non-transitory media, the one or more computer-readable non-transitory media having instructions stored thereon for controlling one or more devices to perform a method, the method comprising: A first heart rate waveform is obtained via a sensor system of a wearable device in a first wearable device configuration, the first wearable device configuration corresponding to a first position of one or more sensors of the sensor system; The user is prompted via the user interface of the wearable device to change the wearable device configuration to a second wearable device configuration, which corresponds to a second location of one or more sensors of the sensor system; A second heart rate waveform is obtained via the sensor system in the configuration of the second wearable device; The determination of whether to change the wearable device configuration or maintain the current wearable device configuration is based at least in part on the first heart rate waveform and the second heart rate waveform. as well as The user is prompted via the user interface to change the wearable device configuration or maintain the current wearable device configuration.

27. The one or more computer-readable non-transitory media according to claim 26, wherein the determination further comprises: Determine the first signal-to-noise ratio (SNR) corresponding to the first heart rate waveform; Determine the second SNR corresponding to the second heart rate waveform; as well as Compare the first SNR with the second SNR.

28. The one or more computer-readable non-transitory media according to claim 26, wherein the method further comprises: The first to Nth heart rate waveforms are obtained via the sensor system in the configuration of the first to Nth wearable devices, where N is an integer greater than 2; The selection of one of the first to Nth wearable device configurations is based at least in part on the first to Nth heart rate waveforms; as well as The user is prompted via the user interface to change the wearable device configuration to the selected wearable device configuration.

29. One or more computer-readable non-transient media according to claim 26, wherein the first heart rate waveform and the second heart rate waveform are obtained via a photoacoustic process.

30. One or more computer-readable non-transient media according to claim 29, wherein the photoacoustic process involves: The wearable device's light source system is controlled to direct light to a target part of the user's body; and Acoustic signals corresponding to the photoacoustic response of the target part of the user's body to the light are obtained via the receiver system of the wearable device.

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