Motion-based feedback for photoacoustic sensors

Abstract

Some disclosed examples involve: receiving an ultrasonic receiver signal from an ultrasonic receiver system corresponding to an ultrasonic wave generated by a target object in response to light from a light source system; estimating one or more vascular characteristics based at least in part on the ultrasound receiver signal; and estimating blood pressure based at least in part on the one or more blood vessel features. Some examples disclosed involve: receiving inertial sensor data from an inertial sensor system; determining whether the inertial sensor data indicates a device motion exceeding a threshold; and controlling a photoacoustic plethysmography (PAPG) system including a light source system and an ultrasound receiver system according to whether the device motion exceeds a threshold.

Description

Priority Statement

[0001] This application claims priority to U.S. Patent Application No. 18 / 461,429, filed September 5, 2023, entitled “MOTION-BASED FEEDBACK FOR APHOTOACOUSTIC SENSOR,” which is incorporated herein by reference for all purposes. Technical Field

[0002] This disclosure relates in general to photoacoustic devices, and more specifically to light source systems for photoacoustic devices. Related technical descriptions

[0003] 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 for continuous, non-invasive, and non-bedridden monitoring. Some of these devices are or include photoacoustic devices. While some previously deployed photoacoustic devices and systems have provided acceptable results, improved photoacoustic devices and systems are desirable. Summary of the Invention

[0004] The systems, methods, and apparatus disclosed herein each have several aspects, and no single aspect is solely responsible for the desired properties disclosed herein.

[0005] One innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus. The apparatus may include one or more motion detectors and a photoacoustic volumetric plethysmography (PAPG) system. The PAPG system may include: a light source system configured to provide light to a target object on an outer surface of the apparatus; and an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object in response to the light from the light source system and to generate an ultrasonic receiver signal based at least in part on the ultrasonic waves generated by the target object. The receiver system may be or may include an ultrasonic receiver system. In some embodiments, a mobile device (such as a wearable device, a cellular phone, etc.) may be or may include at least a portion of the apparatus.

[0006] 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 receive ultrasound receiver signals from the ultrasound receiver system. The control system may be configured to estimate one or more vascular features based at least in part on the ultrasound receiver signals. The control system may be configured to estimate blood pressure based at least in part on the one or more vascular features. The control system may be configured to receive inertial sensor data from the inertial sensor system. The control system may be configured to determine whether the inertial sensor data indicates device movement exceeding a threshold.

[0007] The control system can be configured to control the PAPG system based on whether the device movement exceeds a threshold. In some examples, controlling the PAPG system may involve suspending the functionality of the PAPG system when the device movement exceeds the threshold. In some examples, the device may include a user interface system. In some such examples, the control system can be configured to provide a user prompt via the user interface system that biometric measurements have been suspended. In some examples, controlling the PAPG system may involve controlling one or more light-directing devices of the light source system when the device movement exceeds the threshold. In some such examples, controlling the one or more light-directing devices may involve controlling the one or more light-directing devices to compensate for the device movement. The one or more light-directing devices may, for example, include one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof. However, in some alternative examples, the light source system may not include a light-directing system.

[0008] Other innovative aspects of the subject matter described in this disclosure can be implemented in a method. The method may involve: receiving an ultrasound receiver signal from an ultrasound receiver system corresponding to an ultrasound wave generated by a target object in response to light from a light source system. The method may involve: estimating one or more vascular features based at least in part on the ultrasound receiver signal. The method may involve: estimating blood pressure based at least in part on the one or more vascular features. The method may involve: receiving inertial sensor data from an inertial sensor system. The method may involve: determining whether the inertial sensor data indicates device motion exceeding a threshold. The method may involve: controlling a PAPG system including the light source system and the ultrasound receiver system based on whether the device motion exceeds the threshold.

[0009] In some examples, controlling the PAPG system may involve suspending the functionality of the PAPG system when the device movement exceeds the threshold. In some examples, the device may include a user interface system. In some such examples, the method may involve providing a user prompt via the user interface system that biometric measurements have been suspended. In some examples, controlling the PAPG system may involve controlling one or more light-directing devices of the light source system when the device movement exceeds the threshold. In some such examples, controlling the one or more light-directing devices may involve controlling the one or more light-directing devices to compensate for the device movement. The one or more light-directing devices may, for example, include one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof. However, in some alternative examples, the light source system may not include a light-directing system.

[0010] 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.

[0011] 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. It should be noted that the relative dimensions in the following drawings may not be drawn to scale. Attached Figure Description

[0012] Figure 1A An example of a light source properly aligned with an artery is shown.

[0013] Figure 1B An example of a light source that is not properly aligned with an artery is shown.

[0014] Figure 1C This is a graph showing examples of heart rate waveforms obtained from stationary and moving objects.

[0015] Figure 1D This is a block diagram illustrating example components of a device according to some specific implementations disclosed.

[0016] Figure 2 An example of a device including a light source system with a light steering system is shown.

[0017] Figure 3A , Figure 3B and Figure 3C An example of a light source system that includes another type of light steering system is shown.

[0018] Figure 4 Another example of a light source system including a light steering system is shown.

[0019] Figure 5 Another example of a light source system including a light steering system is shown.

[0020] Figure 6 Another example of a light source system including a light steering system is shown.

[0021] Figure 7 An example of an array of ultrasonic receiver elements is shown.

[0022] Figure 8A An example of a device configured to perform a receiver-side beamforming process is shown.

[0023] Figure 8B An example of an alternative specific implementation is shown.

[0024] Figure 9 This is a flowchart illustrating examples of some of the disclosed operations.

[0025] Figure 10 This is a flowchart illustrating examples of some of the alternative operations disclosed.

[0026] Figure 11 It shows that it can be based on Figure 9 Examples of specific implementations of the method for extracting heart rate waveform (HRW) features.

[0027] Figure 12 An example of a device is shown that can be used in a system for estimating blood pressure based at least in part on pulse transit time (PTT).

[0028] Figure 13 A cross-sectional side view showing a schematic representation of a portion of an artery through which a pulse is propagating.

[0029] Figure 14A An example of a non-bedridden monitoring device designed to be worn around the wrist is shown according to some specific implementations.

[0030] Figure 14B An example of a non-bedridden monitoring device designed to be worn on a finger is shown according to some specific implementations.

[0031] Figure 14C An example of a non-bedridden monitoring device designed to reside on an earpiece is shown according to some specific implementations.

[0032] The same reference numerals and names in the various figures indicate the same elements. Detailed Implementation

[0033] The following description is directed to certain specific embodiments 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 various electronic devices, such as, but not limited to: mobile phones, cellular phones with multimedia-enabled networks, 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, laptops, notebook computers, smart e-books, tablet computers, printers, photocopiers, scanners, fax machines, GPS receivers / navigators, cameras, digital media players, game consoles, wristwatches, clocks, computers, 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 displays for vehicle rearview cameras), 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 broad applicability will be apparent to those skilled in the art.

[0034] Compared to more invasive health monitoring devices, such as cuff-based or catheter-based blood pressure measurement devices, non-invasive health monitoring devices (such as devices with photoacoustic plethysmography (PAPG) capability) offer various potential advantages. However, designing a satisfactory PAPG-capable device has proven challenging. One challenge is managing the low signal-to-noise ratio (SNR) of the signals, such as the ultrasound signals corresponding to the photoacoustic response of the arterial wall. For example, the signals corresponding to the arterial wall are typically significantly lower in amplitude than the signals corresponding to the photoacoustic response of the skin.

[0035] Another challenge is that the orientation of the same artery can vary from user to user and even within the same user's body. Such variations in arterial orientation can make directing light to the artery challenging. An example of an artery properly illuminated is... Figure 1A The figure shows a waveform within an artery representing the photoacoustic response to light provided by a single vertical cavity surface-emitting laser (VCSEL). Figure 1B An example of light misalignment from a light source and an artery is shown. Simulations indicate that even a 1.5 mm misalignment of the light can lead to a significant degradation of the resulting photoacoustic signal. One solution for potential misalignment would be to use an array of suitable light sources. However, such a specific implementation would require high input power and / or switching capability for each light source in the array. Laser sources, such as vertical cavity surface-emitting lasers (VCSELs) and edge-emitting lasers (EELs), require high (e.g., 10 to 25 amps) current pulses, for example, with intervals of 200 nanoseconds (ns) or less. Therefore, a device with PAPG capability and a suitable array of light sources can be expensive and complex, and may consume a large amount of power. Furthermore, simply including an array of light sources does not address the problems caused by human movement during measurement. Figure 1C These are graphs illustrating examples of heart rate waveforms obtained from stationary and moving objects. In such examples, curve 115 shows a heart rate waveform obtained from a person who is moving at the time of measurement, and curve 120 shows a heart rate waveform obtained from a person who is stationary at the time of measurement. It can be observed that the heart rate waveforms of curve 115 and curve 120 are substantially different.

[0036] Some of the disclosed devices include a control system, an inertial sensor system, and a PAPG system, the PAPG system including a light source system configured to provide light to a target object and an ultrasonic receiver system. The ultrasonic receiver system may be configured to receive ultrasonic waves generated by the target object in response to light from the light source system and to generate an ultrasonic receiver signal based at least in part on the ultrasonic waves generated by the target object. The inertial sensor system may include one or more motion detectors, such as one or more accelerometers, one or more gyroscopes, etc. The control system may be configured to receive inertial sensor data from the inertial sensor system, determine whether the inertial sensor data indicates device motion exceeding a threshold, and control the PAPG system based on whether the device motion exceeds the threshold. In some examples, the control system may be configured to receive an ultrasonic receiver signal from the ultrasonic receiver system, estimate one or more vascular features based at least in part on the ultrasonic receiver signal, and estimate blood pressure based at least in part on the one or more vascular features.

[0037] According to some examples, a light source system may include a light steering system having one or more light steering devices configured to direct light emitted by one or more light sources of the light source system to multiple regions of a target object. The light steering system may, for example, include one or more rotatable micromirrors, such as one or more microelectromechanical (MEMS) torsional micromirrors. Alternatively or additionally, the light steering system may include one or more movable lenses, one or more movable diffraction gratings, etc. In some examples, controlling the PAPG system may involve controlling one or more light steering devices of the light steering system when the device movement exceeds a threshold.

[0038] 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 configurations include PAPG-capable devices that can control a PAPG system based on whether device movement exceeds a threshold. In some such examples, controlling the PAPG system may involve suspending the functionality of the PAPG system when device movement exceeds a threshold. Such examples have the potential advantage of eliminating potentially unreliable PAPG data and thus potentially incorrect blood pressure estimates. Some such examples may involve providing a user prompt to remain still to allow reliable biometric measurements to be resumed. Specific embodiments including a light steering system can be configured to direct light to multiple areas of a target object, while including only one or two light sources. Therefore, the number of illuminated areas of the target object can be greater than the number of light sources (e.g., 5x, 10x, 15x, 20x, etc.). Therefore, a PAPG-capable device with a light steering system may be less expensive, less complex, and may consume less power compared to a PAPG-capable device with an array of light sources, where each light source corresponds to one of multiple illuminated areas of the target object. Some specific embodiments including a light steering system can be configured to control the light steering system to compensate for device movement. Such examples have the potential advantage of transforming potentially unreliable PAPG data into reliable PAPG data.

[0039] Figure 1D This is a block diagram illustrating example components of a device according to some of the disclosed embodiments. In this example, device 100 includes a PAPG system 103, a control system 106, and an inertial sensor system 112. In this example, PAPG system 103 includes an ultrasonic receiver system 102 and a light source system 104. In some embodiments, PAPG system 103 may include a light steering system 105. Some embodiments of device 100 may include a platform 101, an interface system 108, a noise reduction system 110, or combinations thereof. With regard to other disclosed embodiments, in some alternative embodiments, device 100 may include more components, fewer components, or different components.

[0040] According to some examples, the platform 101 (if present) 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 the platform 101.

[0041] In some examples, at least a portion of the outer surface of the platform 101 (if present) may have an acoustic impedance configured to approximate the acoustic impedance of human skin. The portion of the outer surface of the platform 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 “finger portion” are used interchangeably, such that the thumb is an example of a finger.) Typical acoustic impedance of human skin ranges from 1.53 million reels (MRayl) to 1.680 million reels (MRayl). In some examples, at least the outer surface of the platform 101 may have an acoustic impedance in the range of 1.4 million reels to 1.8 million reels or in the range of 1.5 million reels to 1.7 million reels.

[0042] Alternatively or additionally, in some examples, at least the outer surface of the platform 101 (if present) may be configured to conform to the surface of human skin. In some such examples, at least the outer surface of the platform 101 may have material properties similar to putty or chewing gum.

[0043] In some examples, at least a portion of the platform 101 (if present) 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 platform 101 and one or more receiver elements may have an acoustic impedance configured to approximate the acoustic impedance of one or more receiver elements. Alternatively or additionally, in some examples, the layer residing between the platform 101 and one or more receiver elements may have an acoustic impedance within the range of acoustic impedance between the acoustic impedance of the platform and the acoustic impedance of one or more receiver elements.

[0044] According to some examples, the platform 101 (if present) may include one or more light guides. In some such examples, each of the one or more light guides may be configured to guide a first portion of the received light along the axis of the light guide. In some such examples, each of the one or more light guides may include one or more light extraction elements. According to some such examples, each of the one or more light guides may be configured to guide a second portion of the received light toward a target object.

[0045] Various examples and configurations of the ultrasonic receiver system 102 may be used in the specific embodiments disclosed herein. Some examples are described in more detail below. According to some examples, part or all of the ultrasonic receiver system 102—such as electrodes, piezoelectric materials, or both—may include a transparent material. In some examples, the ultrasonic receiver system 102 may include an array of ultrasonic receiver elements, such as a linear array or a two-dimensional array. However, other examples may not 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, or a piezoelectric composite material layer. In some specific embodiments, other piezoelectric materials, such as aluminum nitride (AlN) or lead zirconate titanate (PZT), may be used in the piezoelectric layer. In some examples, the ultrasonic receiver system 102 may include an array of ultrasonic transducer elements, such as a piezoelectric micromechanical ultrasonic transducer (PMUT) array, a capacitive micromechanical ultrasonic transducer (CMUT) array, etc. In some such examples, a piezoelectric receiver layer, a PMUT element in a single-layer array of PMUTs, or a CMUT element in a single-layer 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 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.

[0046] According to some embodiments, the light source system 104 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 (EELs). 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. However, limiting the number of light-emitting elements to a relatively small number may be advantageous, such as one light-emitting element, two light-emitting elements, three light-emitting elements, etc.

[0047] According to some examples, the light source system 104 may include a light steering system 105. In some such examples, the light steering system 105 may include one or more light steering devices configured to direct light emitted by one or more light sources of the light source system 104 to multiple regions of a target object. According to some examples, the one or more light steering devices may include one or more movable micromirrors, such as one or more movable MEMS micromirrors. Alternatively or additionally, the one or more light steering devices may include one or more movable lenses, one or more movable diffraction gratings, etc. In some examples, the light steering system 105 may be configured to direct light emitted by one or more light sources of the light source system to multiple regions of a target object through a transparent portion of the ultrasonic receiver system 102.

[0048] In some examples, a single light steering device can be configured to direct light emitted by two or more light sources of a light source system to multiple regions of a target object. According to some such examples, at least one of the two or more light sources may have a peak frequency different from the other light sources. In some examples, the light steering device can be configured to direct first light emitted by a first light source to a first plurality of regions, and is configured to direct second light emitted by a second light source to a second plurality of regions. According to some such examples, the light steering device can be configured to direct the first light to the first plurality of regions at a first time, and is configured to direct the second light to the second plurality of regions at a second time different from the first time. In some such examples, the first light may have a peak amplitude at a first wavelength, and the second light may have a peak amplitude at a second wavelength. In some alternative examples, the first light steering device can be configured to direct the first light emitted by the first light source to the first plurality of regions, and the second light steering device can be configured to direct the second light emitted by the second light source to the second plurality of regions.

[0049] According to some examples, one or more light steering devices may be configured to direct light emitted by at least a first light source to each of a plurality of light guides. In some examples, the platform 101 may include a plurality of light guides. According to some examples, the ultrasonic receiver system 102 may include a plurality of receiver sections. In some such examples, each receiver section may correspond to one of the plurality of light guides.

[0050] In some examples, the light source system 104 can be configured to emit light within one or more wavelength ranges. In some examples, the light source system 104 can be configured to emit light in the 500 nm to 600 nm wavelength range. According to some examples, the light source system 104 can be configured to emit light in the 800 nm to 950 nm wavelength range.

[0051] 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 driving circuitry) 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.

[0052] In some examples, the light source system 104 may include a light source system surface having a normal parallel to or substantially parallel to the first axis. In some such examples, the light source of the light source system may reside on or adjacent to the light source system surface.

[0053] 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, since 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 short pulses of IR light can be emitted 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, IR LEDs and red LEDs 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 embodiments, one or more light sources of different wavelengths can be lit sequentially or simultaneously to generate acoustic emission detectable by an ultrasound receiver. Image data acquired from an ultrasound receiver using light sources of different wavelengths and at different depths (e.g., varying RGDs) within a target object can be combined to determine the location and type of material within the target object. Image contrast is possible because materials in a subject typically absorb light of different wavelengths differently. When materials in a subject absorb light of a specific wavelength, they may heat up differently, generating acoustic emission of light pulses with sufficient intensity and shortness. Depth contrast can be obtained using light of different wavelengths and / or intensities at each selected wavelength. That is, continuous images can be obtained at a fixed RGD (which may correspond to a fixed depth of the target object) using varying light intensities and wavelengths to detect material and its location within the target object. For example, hemoglobin, blood glucose, or blood oxygen within blood vessels in a target object such as a finger can be detected photoacously.

[0054] According to some embodiments, the light source system 104 can be configured to emit light pulses with a pulse width of less than about 100 nanoseconds. In some embodiments, the light pulses may have a pulse width 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 a pulse repetition frequency 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 a pulse repetition frequency 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 a pulse repetition frequency 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 can 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, thereby achieving accumulation of the 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 include a light source such as red, green, and blue LEDs for a display, which may be enhanced by light sources of other wavelengths (such as IR and / or UV) and 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.

[0055] 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 1D 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 implementations, 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.

[0056] In some examples, the control system 106 may be configured to control the light source system 104 to emit light toward a target object on the outer surface of the platform 101. In some such examples, the control system 106 may be configured to control the light steering system 105 to direct light emitted by at least a first light source of the light source system 104 to multiple regions of the target object on or near the outer surface of the device 100—for example, to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more regions.

[0057] According to some such examples, the control system 106 may be configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object that has been illuminated by the light source system 104. The signals may correspond to ultrasonic waves generated by the target object in response to light from the light source system 104 in each of a first plurality of areas. In some such examples, the control system 106 may be configured to receive signals from each of a plurality of ultrasonic receiver elements in an array of ultrasonic receiver elements of the ultrasonic receiver system 102.

[0058] In some examples, the control system 106 may be configured to receive an ultrasound receiver signal from an ultrasound receiver system, and to estimate one or more vascular features based at least in part on the ultrasound receiver signal. In some examples, the control system 106 may be configured to estimate blood pressure based at least in part on one or more vascular features.

[0059] According to some examples, the control system 106 may be configured to determine selected areas of a target object from which additional ultrasound receiver signals will be received. In some such examples, determining the selected area may involve detecting blood vessels within the target object. In some examples, determining the selected area may involve estimating the signal-to-noise ratio (SNR) of the ultrasound receiver signal corresponding to at least a portion of the blood vessel. In some such examples, the control system 106 may be configured to determine the selected area by selecting the area corresponding to the highest SNR.

[0060] In some examples, the control system 106 may be configured to apply a receiver-side beamforming process to the ultrasound receiver signal to generate a beamformed ultrasound 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 ultrasound 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 ultrasound 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, cardiac features may be or may include blood pressure.

[0061] Some specific embodiments of device 100 may include interface system 108. In some examples, interface system 108 may include a wireless interface system. In some specific embodiments, interface system 108 may include a user interface system, 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. According to some examples in which interface system 108 is present and includes a user interface system, 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 combinations thereof. According to some examples, interface system 108 may include a touch sensor system, a gesture sensor system, or combinations thereof. The touch sensor system (if present) may be or may include 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 combinations thereof.

[0062] In some examples, interface system 108 may include a force sensor system. The force sensor system (if present) may be or may include 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. If the force sensor system includes a piezoresistive sensor, the piezoresistive sensor may include silicon, metal, polycrystalline silicon, glass, or a combination thereof. In some implementations, the ultrasonic fingerprint sensor and the force sensor system may be mechanically coupled. In some such examples, the force 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.

[0063] 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 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, 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 electromagnetically shielded transmission lines, sound-absorbing layers, sound-insulating materials, light-absorbing materials, light-reflecting materials, or combinations thereof may be components of ultrasonic receiver system 102, light source system 104, or both. Despite the ultrasonic receiver system 102, the light source system 104, and the noise reduction system 110 in Figure 1D Although shown as a separate component, such components can still be considered as elements of the noise reduction system 110.

[0064] In this example, device 100 includes an inertial sensor system 112. In some examples, the inertial sensor system 112 may include one or more gyroscopes, one or more accelerometers, or combinations thereof. One or more accelerometers are examples of what may be referred to herein as "motion detectors." In some specific implementations, control system 106 may be configured to receive inertial sensor data from inertial sensor system 112 and to control optical steering system 105 at least in part based on the inertial sensor data. For example, control system 106 may be configured to determine whether the inertial sensor data indicates motion of device 100 exceeding a threshold, and to control the PAPG system based on whether the device motion exceeds the threshold. According to some examples, controlling the PAPG system may involve suspending the functionality of the PAPG system when the device motion exceeds the threshold. In some examples, controlling the PAPG system may involve controlling one or more optical steering devices of the optical steering system based on whether the device motion exceeds the threshold.

[0065] According to some examples, the control system 106 may be configured to control the light steering system 105 to compensate for device movement. For example, if the control system 106 determines that the device 100 has moved relative to or is moving toward a target object in contact with the device, the control system 106 may be configured to control the light steering system 105 to compensate for device movement. In one such example, if the control system 106 determines that the device 100 has moved 3 spatial units in the x-direction and 4 spatial units in the y-direction relative to the target object, the control system 106 may be configured to control the light steering system 105 to direct light emitted by at least a first light source of the light source system 104 to new multiple regions shifted 3 spatial units along the x-axis and 4 spatial units along the y-axis from previous multiple regions.

[0066] 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. Wearable devices may be, for example, bracelets, armbands, wristbands, watches, rings, headbands, or patches. Thus, in some examples, device 100 may be configured to be worn by or attached to a person.

[0067] Figure 2 An example of a device including a light source system with a light steering system is shown. Regarding other disclosed examples, Figure 2 The types, quantities, dimensions, and arrangements of the components shown and described herein are merely examples. According to this example, device 100 includes a platform 101, an ultrasonic receiver system 102, a light source system 104, and a control system 106 (not shown). Figure 2 In the example shown, the light source system 104 includes at least a light source 204 (which is a laser light source in this example) and at least one light steering device 205 (which is a movable MEMS micromirror in this example). The light source 204 may be or may include a VSCEL, EEL, or laser diode (LD). According to this example, the ultrasonic receiver system 102 includes an array of receiver elements 202. In this example, the array includes five receiver elements 202. Other examples may include more or fewer than five receiver elements 202.

[0068] In this example, human tissue 211 is on the outer surface of device 100, contacting platform 101. Here, artery 210 resides within human tissue 211. Human tissue 211 is an example that may be referred to herein as the "target object".

[0069] According to this example, the light steering system 105 is configured to guide light emitted by at least the light source 204 to multiple areas of a target object. Here, the light steering system 105 is configured to guide reflected light 214a' of the light emitted by the light source 204 toward multiple areas of the target object. Arrow 216 indicates the range in which the light steering system 105 is configured to provide reflected light 214a' to the target object, and arrow 207 indicates the positional range in which the light steering system 105 can be positioned. Figure 2 In the diagram, the reflected light 214a' currently being guided towards tissue 211 by the light steering system 105 is shown with a solid gray outline. However, other instances of the reflected light 214a' that the light steering system 105 may guide towards other areas of tissue 211 when the light steering system 105 is positioned differently are shown with dashed, unfilled outlines. In some such examples, the control system 106 may be configured to control the light steering system 105 to guide light from the light source 204 to multiple areas of the target object. For example, the control system 106 may be configured to control the light steering system 105 to guide the reflected light 214a' to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more areas of tissue 211.

[0070] According to some such examples, the control system 106 may be configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a'. The signals may correspond to ultrasonic waves resulting from the photoacoustic response of each area of ​​the target object illuminated by reflected light 214a'. In this example, the control system 106 is configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a'. Figure 2 Each receiver element in receiver element 202 of the array of ultrasonic receiver elements shown receives a signal.

[0071] According to some examples, the control system 106 may be configured to determine a selected region of a target object from which additional ultrasound receiver signals will be received. In some such examples, determining the selected region may involve detecting an artery 210 within tissue 211, another blood vessel, or another target of interest. In some examples, determining the selected region may involve estimating the signal-to-noise ratio (SNR) of the ultrasound receiver signal corresponding to at least a portion of the artery 210. In some such examples, the control system 106 may be configured to determine the selected region by selecting the region corresponding to the highest SNR. According to some examples, the control system 106 may be configured to control the light source system 104 to receive additional ultrasound receiver signals from the selected region.

[0072] Figure 3A , Figure 3B and Figure 3CAn example of a light source system including another type of light steering system is shown. Regarding the other examples disclosed, Figures 3A to 3C The types, quantities, sizes, and arrangements of the elements shown and described herein are merely examples. According to such examples, the light source system 104 includes a light steering system 105 having at least one light steering device 205, which in this example is a movable lens. The light source 204 may be or may include a VSCEL, EEL, or laser diode.

[0073] According to such examples, the light steering system 105 is configured to direct light emitted by at least the light source 204 to multiple areas of a target object (not shown). In such examples, the light steering system 105 is configured to direct refracted light 214c emitted by the light source 204 toward multiple areas of the target object.

[0074] exist Figure 3A In the example shown, the light steering device 205 is depicted as guiding refracted light 214c toward a region 310a that coincides with axis 305. In this example, axis 305 and Figures 3A to 3C The y-axis of the coordinate system shown is parallel.

[0075] exist Figure 3B In the example shown, the light steering device 205 is shown to guide refracted light 214c toward region 310b, which is relative to axis 305 and relative to... Figures 3A to 3C The coordinate system shown is offset in the positive x-direction. Here, the light steering device 205 is also offset in the positive x-direction relative to the axis 305 and the coordinate system.

[0076] according to Figure 3C In the example shown, the light steering device 205 is depicted guiding refracted light 214c toward region 310c, which is offset in the negative x-direction relative to axis 305 and the coordinate system. Here, the light steering device 205 is also offset in the negative x-direction relative to axis 305.

[0077] Figure 4 Another example of a light source system including a light steering system is shown. Regarding the other examples disclosed, Figure 4 The types, quantities, dimensions, and arrangements of the components shown and described herein are merely examples. According to this example, device 100 includes a platform 101, an ultrasonic receiver system 102, a light source system 104, and a control system 106 (not shown). Figure 4In the example shown, the light source system 104 includes at least light sources 204a and 204b (which are laser light sources in this example) and at least light steering devices 205a and 205b (which are movable MEMS micromirrors in this example). According to this example, the ultrasonic receiver system 102 includes an array of receiver elements 202.

[0078] In this example, human tissue 211 is on the outer surface of device 100, contacting platform 101. According to this example, artery 210 resides within human tissue 211. In this example, light steering system 105 is configured to direct light emitted by light sources 204a and 204b to multiple regions of a target object. Here, light steering device 205a is configured to reflect reflected light 214a' of light 214a emitted by light source 204a toward a first plurality of regions of the target object. Similarly, light steering device 205b is configured to reflect reflected light 214b' of light 214b emitted by light source 204b toward a second plurality of regions of the target object. In some examples, the first plurality of regions may be the same as the second plurality of regions; however, in other examples, the first plurality of regions may be different from the second plurality of regions. According to some such examples, light steering system 105 may be configured to direct first light to the first plurality of regions at a first time, and is configured to direct second light to the second plurality of regions at a second time different from the first time. In some such examples, the first light may have a peak amplitude at a first wavelength, and the second light may have a peak amplitude at a second wavelength. Arrows 216a and 216b indicate that light-directing devices 205a and 205b are configured to provide the range of reflected light 214a' and 214b'. Here, arrows 207a and 207b indicate the range to which light-directing devices 205a and 205b are configured to be positioned, in this example, by rotating light-directing devices 205a and 205b. In some examples, the light-directing system 105 may include light-directing devices that can be rotated and translated or moved relative to the platform 101 and relative to a target object on the platform 101.

[0079] According to some examples, the control system 106 may be configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a' and 214b'. These signals may correspond to ultrasonic waves resulting from the photoacoustic response of each area of ​​the target object illuminated by reflected light 214a' and 214b'. In this example, the control system 106 is configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a' and 214b'. Figure 4 Each receiver element in receiver element 202 of the array of ultrasonic receiver elements shown receives a signal.

[0080] According to some examples, the control system 106 may be configured to determine a selected region of a target object from which additional ultrasound receiver signals will be received. In some such examples, determining the selected region may involve detecting an artery 210 within tissue 211. In some examples, determining the selected region may involve estimating the signal-to-noise ratio (SNR) of the ultrasound receiver signal corresponding to at least a portion of the artery 210. In some such examples, the control system 106 may be configured to determine the selected region by selecting the region corresponding to the highest SNR. According to some examples, the control system 106 may be configured to control the light source system 104 to receive additional ultrasound receiver signals from the selected region.

[0081] Figure 5 Another example of a light source system including a light steering system is shown. Regarding the other examples disclosed, Figure 5 The types, quantities, dimensions, and arrangements of the components shown and described herein are merely examples. According to this example, device 100 includes a platform 101, an ultrasonic receiver system 102, a light source system 104, and a control system 106 (not shown). Figure 5 In the example shown, the light source system 104 includes at least light sources 204a and 204b (which are laser light sources in this example) and at least one light steering device 205 (which is a movable MEMS micromirror in this example). According to this example, the ultrasonic receiver system 102 includes an array of receiver elements 202.

[0082] In this example, the light steering device 205 is configured to direct light emitted by light sources 204a and 204b to multiple regions of a target object. Here, the light steering device 205 is configured to reflect reflected light 214a' of light 214a emitted by light source 204a toward a first plurality of regions of the target object. Similarly, the light steering device 205 is configured to reflect reflected light 214b' of light 214b emitted by light source 204b toward a second plurality of regions of the target object. In some examples, the first plurality of regions may be the same as the second plurality of regions; however, in other examples, the first plurality of regions may be different from the second plurality of regions. According to some such examples, the light steering device 205 may be configured to direct first light to the first plurality of regions at a first time, and is configured to direct second light to the second plurality of regions at a second time different from the first time. In some such examples, the first light may have a peak amplitude at a first wavelength, and the second light may have a peak amplitude at a second wavelength. Arrow 216a indicates the range of light steering device 205 configured to provide reflected light 214a' and 214b'. In this example, arrow 207 indicates the range of motion of light steering device 205.

[0083] According to some such examples, the control system 106 may be configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a' and 214b'. These signals may correspond to ultrasonic waves resulting from the photoacoustic response of each area of ​​the target object illuminated by reflected light 214a' and 214b'. In this example, the control system 106 is configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a' and 214b'. Figure 5 Each receiver element in receiver element 202 of the array of ultrasonic receiver elements shown receives a signal.

[0084] According to some examples, the control system 106 may be configured to determine a selected region of a target object from which additional ultrasound receiver signals will be received. In some such examples, determining the selected region may involve detecting an artery 210 within tissue 211. In some examples, determining the selected region may involve estimating the signal-to-noise ratio (SNR) of the ultrasound receiver signal corresponding to at least a portion of the artery 210. In some such examples, the control system 106 may be configured to determine the selected region by selecting the region corresponding to the highest SNR. According to some examples, the control system 106 may be configured to control the light source system 104 to receive additional ultrasound receiver signals from the selected region.

[0085] Figure 6 Another example of a light source system including a light steering system is shown. Regarding the other examples disclosed, Figure 6 The types, quantities, dimensions, and arrangements of the components shown and described herein are merely examples. According to this example, device 100 includes a platform 101, an ultrasonic receiver system 102, a light source system 104, and a control system 106 (not shown). Figure 6 In the example shown, the light source system 104 includes at least a light source 204 (which is a laser light source in this example) and at least one light steering device 205 (which is a movable MEMS micromirror in this example).

[0086] In this example, the light source system 104 includes a plurality of light guides 604. According to this example, the light steering system 105 is configured to guide light 214a emitted by the light source 204 to reflected light 214a' in each of the plurality of light guides 604. In this example, arrow 207 indicates the range of motion of the light steering device 205, and arrow 216 indicates the range by which the light steering device 205 is configured to provide reflected light 214' to the plurality of light guides 604. According to this example, the stage 101 includes light guides 604. Therefore, the light guides 604 can be considered as part of the stage 101, part of the light source system 104, or both.

[0087] According to this example, the ultrasonic receiver system 102 includes an array of receiver elements 202. In this example, the array includes five receiver elements 202. In this example, one receiver element 202 corresponds to one of a plurality of light guides 604. For example, one receiver element 202 may be positioned near one light guide 604, another receiver element 202 may be positioned near another light guide 604, and so on. Other examples may include more or fewer than five receiver elements 202, different arrangements of the receiver elements 202 relative to the light guides 604, or combinations thereof.

[0088] In this example, each light guide 604 is configured to guide a first portion of the received light—here, the reflected light 214a'—along an axis corresponding to the x-axis in this example. According to this example, each light guide 604 is configured to guide a second portion of the received light—here, the extracted light 214a''— toward a target object, which in this example is tissue 211. In this example, each light guide 604 includes a plurality of light extraction elements 610 configured to extract at least some of the reflected light 214a' and guide the extracted light 214a'' toward the tissue 211.

[0089] According to some such examples, the control system 106 may be configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a''. These signals may correspond to ultrasonic waves resulting from the photoacoustic response of each area of ​​the target object illuminated by reflected light 214a''. In this example, the control system 106 is configured to receive signals from the ultrasonic receiver system 102 corresponding to each area of ​​the target object illuminated by reflected light 214a''. Figure 6 Each receiver element in receiver element 202 of the array of ultrasonic receiver elements shown receives a signal.

[0090] Figure 7 An example of an array of ultrasonic receiver elements is shown. In this example, the array of ultrasonic receiver elements 702 is a two-dimensional array of ultrasonic receiver elements. According to this example, the array of ultrasonic receiver elements 702 is arranged in a square with 6 active ultrasonic receiver elements 202 on each side and a total of 36 active ultrasonic receiver elements 202. Regarding other examples disclosed, Figure 7 The types, quantities, 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 202, such as 16, 20, 25, 30, 32, 36, 40, 48, etc.

[0091] Figure 8A 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-superposition beamforming process. Regarding other examples disclosed, Figure 8A The types, quantities, sizes, and arrangements of the elements shown and described herein, as well as the associated methods described herein, are merely examples.

[0092] In this example, a source emitting ultrasonic waves 305 is shown, which are detected by active ultrasonic receiver elements 202a, 202b, and 202c of an array of ultrasonic receiver elements 202. The array of ultrasonic receiver elements 202 is part of the ultrasonic receiver system 102. In some examples, ultrasonic waves 305 may correspond to the photoacoustic response of a target object to light emitted by the light source system 104 of device 101. In this example, the active ultrasonic receiver elements 202a, 202b, and 202c provide ultrasonic receiver signals 815a, 815b, and 815c to the control system 106, respectively.

[0093] According to this example, the control system 106 includes a delay module 805 and a superposition module 810. In this example, the delay module 805 is configured to determine whether a delay should be applied to each of the ultrasonic receiver signals 815a, 815b, and 815c, and if so, what delay should be applied. According to this example, the delay module 805 determines that a delay d0 of t2 should be applied to the ultrasonic receiver signal 815a. 、 The delay d1 of t1 is applied to the ultrasonic receiver signal 815b, and the delay should not be applied to the ultrasonic receiver signal 815c. Therefore, the delay module 805 applies the delay d1 of t2 to the ultrasonic receiver signal 815a to generate the ultrasonic receiver signal 815a', and applies the delay d1 of t1 to the ultrasonic receiver signal 815b to generate the ultrasonic receiver signal 815b'.

[0094] In some examples, the delay module 805 can determine what delay (if any) to apply to the ultrasonic receiver signal by performing a correlation operation on the input ultrasonic receiver signal. For example, the delay module 805 can perform a correlation operation on ultrasonic receiver signals 815a and 815c, and can determine that ultrasonic receiver signal 815a will be strongly correlated with ultrasonic receiver signal 815c by applying a time offset of t2 to ultrasonic receiver signal 815a. Similarly, the delay module 805 can perform a correlation operation on ultrasonic receiver signals 815b and 815c, and can determine that ultrasonic receiver signal 815b will be strongly correlated with ultrasonic receiver signal 815c by applying a time offset of t1 to ultrasonic receiver signal 815b.

[0095] According to this example, the superposition module 810 is configured to superimpose ultrasonic receiver signals 815a', 815b', and 815c to generate a superimposed signal 820. It can be observed that the amplitude of the superimposed signal 820 is greater than the amplitude of any one of the ultrasonic receiver signals 815a, 815b, or 815c. In some instances, the signal-to-noise ratio (SNR) amplitude of the superimposed signal 820 may be greater than the SNR of any one of the ultrasonic receiver signals 815a, 815b, or 815c.

[0096] Figure 8B An example of an alternative specific implementation is shown. In this example, the light source system 104 includes five light sources 804 (LS1 to LS5), five corresponding instances of drive circuitry 808 (D1 to D5), and a processor 806 configured to control the light source system 104 and receive signals from the ultrasonic receiver system 102. In this example, the instances of drive circuitry 808 and processor 806 are components of the control system 106. Here, the ultrasonic receiver system 102, the light source system 104, and the control system 106 are examples of the ultrasonic receiver system 102, the light source system 104, and the control system 106 of FIG. 1. For the other examples disclosed, Figure 8B The types, quantities, sizes, and arrangements of the elements shown and described herein are merely examples. Other specific implementations may include different numbers of light sources 804, receiver elements 202, or both.

[0097] As mentioned elsewhere in this document, the various specific embodiments disclosed involve controlling a light source system to direct light to multiple areas of a target object. According to this example, controlling the light source system to direct light to multiple areas of a target object involves controlling multiple light sources 804 to direct light to multiple areas of the target object 211. One example of the area of ​​the target object 211 to which light is directed is the illuminated area 810 of the target object 211 that contacts the table 101. Another example of the area of ​​the target object 211 to which light is directed is the illuminated volume 812 of the target object 211. Thus, in this context, the illuminated volume can be considered a “region.” According to a particular example, the target object 211 may be a finger, wrist, etc. According to this example, a blood vessel 210 resides within the target object 211. In some examples, the control system may cause two, three, four, five, or more light sources 804 to sequentially direct light to multiple areas of the target object.

[0098] Some examples may involve receiving an ultrasonic receiver signal from an ultrasonic receiver system corresponding to the photoacoustic response of a target object to light provided by a light source system to each of a first plurality of regions. The ultrasonic receiver signal may at least partially correspond to the ultrasonic waves generated by the target object in response to light from the light source system.

[0099] Some examples may involve identifying selected regions of a target object from which additional ultrasound receiver signals will be received. In some such examples, identifying the selected region may involve detecting blood vessels within the target object. For example, blood vessels may be detected based on a time window corresponding to the speed of sound traveling to a range of expected depths up to the blood vessel. Alternatively or additionally, blood vessels may be detected based on one or more characteristics of the photoacoustic response of the vessel wall, the blood within the vessel, or a combination thereof. In some examples, identifying the selected region may involve estimating the signal-to-noise ratio (SNR) of the ultrasound receiver signal corresponding to at least a portion of the blood vessel, and selecting the region corresponding to the highest SNR.

[0100] Some examples might involve selecting light source 804 that corresponds to the highest SNR. In Figure 8B In the example shown, light source LS5 illuminates blood vessel 210 most efficiently, and therefore produces the highest SNR in the resulting photoacoustic response. Therefore, based on this example, light source LS5 can be selected.

[0101] Some examples may involve controlling a light source system to obtain an additional ultrasonic receiver signal from a selected area, via a selected light source, or both. According to some such examples, a control system 106 (not shown) may cause a light source LS5 to emit light toward a selected area, such that an additional ultrasonic receiver signal can be obtained from the selected area. In some examples, the control system 106 may control a light source system 104 to cause the light source LS5 to emit light at a desired wavelength, pulse width, pulse rate, power level, or a combination thereof.

[0102] Figure 9 This is a flowchart illustrating examples of some of the disclosed operations. For example, Figure 9 The block can be executed by the device 100 of Figure 1 or a similar device. In some examples, Figure 9 Some or all of the boxes can be executed by the control system 106. Similar to other methods disclosed herein, Figure 9 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 9 One or more boxes in the box shown can be executed concurrently.

[0103] In this example, block 905 relates to receiving an ultrasonic receiver signal from an ultrasonic receiver system corresponding to an ultrasonic wave generated by a target object in response to light from a light source system. Block 905 may relate to the control system 106 of FIG1 receiving an ultrasonic receiver signal from an ultrasonic receiver system 102 corresponding to an ultrasonic wave generated by a target object in response to light from a light source system 104.

[0104] According to this example, block 910 relates to estimating one or more vascular features, at least in part, based on ultrasound receiver signals. Block 910 may, for example, relate to estimating vessel diameter, vascular dilation, volumetric flow rate, pulse wave velocity, vessel wall thickness, or combinations thereof. In some examples, the ultrasound receiver system may include an array of ultrasound receiver elements, and block 910 may relate to receiving ultrasound receiver signals from each of a plurality of ultrasound receiver elements in the array. The array may be a linear array, a two-dimensional array, etc. In some examples, method 900 may relate to applying a receiver-side beamforming process to the ultrasound receiver signals to produce a beamformed ultrasound receiver image. The receiver-side beamforming process may be or may include a delay-superposition beamforming process.

[0105] In this example, box 915 relates to estimating blood pressure based at least in part on one or more vascular features. This disclosure includes various non-limiting examples of box 915.

[0106] According to this example, block 920 relates to receiving inertial sensor data from an inertial sensor system. In block 920, control system 106 may, for example, receive inertial sensor data from inertial sensor system 112.

[0107] In this example, box 925 relates to determining whether inertial sensor data indicates device motion exceeding a threshold. The device motion threshold can be, for example, an acceleration threshold, a swaying or rocking threshold, or a combination thereof.

[0108] According to this example, block 930 relates to controlling a PAPG system, including a light source system and an ultrasonic receiver system, based on whether the device movement exceeds a threshold. For example, block 930 may relate to a control system 106 controlling a PAPG system 103 based on whether the device movement exceeds a threshold.

[0109] In some examples, box 930 may relate to pausing the PAPG system's functionality when device movement exceeds a threshold. According to some such examples, box 930 (or another box of method 900) may relate to providing a user prompt via a user interface system that biometric measurements have been paused. This prompt may be or may include audio prompts, visual prompts, haptic feedback, or combinations thereof. Some such examples may relate to providing a user prompt via a user interface system to remain still to allow biometric measurements to resume.

[0110] According to some examples, block 930 may relate to controlling one or more light-directing devices of the light source system when the device movement exceeds a threshold. In some such examples, controlling the one or more light-directing devices may involve controlling the one or more light-directing devices to compensate for the device movement.

[0111] In some examples, block 930 may involve applying a filter to the ultrasonic receiver signal when the device motion exceeds a threshold. Such examples may involve applying a filter to compensate for device motion. In some examples, the filter may be, or may include, an inverse filter corresponding to the device motion. For example, the received ultrasonic receiver signal may be represented as a convolution of a signal corresponding to the device motion (which may be obtained from the inertial sensor system 112) and a signal corresponding to the photoacoustic response of the target object. In some such examples, method 900 may involve deconvolving the received ultrasonic receiver signal using an inverse filter corresponding to the device motion.

[0112] According to some examples, controlling a PAPG system may involve sequentially activating multiple light sources in a light source system. Some such examples may involve sequentially activating multiple light sources in the light source system when the device movement exceeds a threshold. Other examples may involve sequentially activating multiple light sources in the light source system when the device movement does not exceed a threshold. In either case, some examples may involve evaluating the signal-to-noise ratio (SNR) of the ultrasonic receiver signal corresponding to the ultrasonic waves generated by the target object in response to light emitted by each of the multiple light sources. Some examples may involve selecting the light source corresponding to the highest SNR.

[0113] Figure 10 This is a flowchart illustrating examples of some of the disclosed operations. For example, Figure 10 The block can be executed by the device 100 of Figure 1 or a similar device. In some examples, Figure 10 Some or all of the boxes can be executed by the control system 106. Similar to other methods disclosed herein, Figure 10 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 10 One or more boxes in the box shown can be executed concurrently.

[0114] In this example, box 1005 relates to controlling a light steering system to direct light emitted by at least a first light source of a light source system to first plurality of regions of a target object. According to this example, controlling the light steering system involves controlling one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof. According to a particular example, the target object may be a finger, wrist, etc.

[0115] According to this example, block 1010 relates to receiving an ultrasonic receiver signal from an ultrasonic receiver system corresponding to the photoacoustic response of a target object to light provided by a light source system to each of a first plurality of regions. In this example, the ultrasonic receiver signal corresponds to ultrasonic waves generated by the target object in response to light from the light source system.

[0116] In some examples, box 1015 relates to determining a selected region of a target object from which additional ultrasound receiver signals will be received. According to this example, determining the selected region involves detecting blood vessels within the target object. For example, blood vessels may be detected based on a time window corresponding to the speed of sound traveling a range of expected depths to the blood vessel. Alternatively or additionally, blood vessels may be detected based on one or more characteristics of the photoacoustic response of the vessel wall, the blood within the vessel, or a combination thereof. In some examples, determining the selected region may involve estimating the signal-to-noise ratio (SNR) of the ultrasound receiver signal corresponding to at least a portion of the blood vessel, and selecting the region corresponding to the highest SNR.

[0117] According to this example, box 1020 relates to controlling a light source system to obtain signals from an additional ultrasonic receiver from a selected area.

[0118] In some examples, method 1000 may involve controlling a light steering system to direct light emitted by a second light source of a light source system to a second plurality of regions of a target object. The second plurality of regions may correspond to, or not correspond to, the first plurality of regions, or may be the same as the first plurality of regions, depending on a particular implementation.

[0119] According to some examples, controlling this light steering system may involve guiding light emitted by at least a first light source to each of a plurality of light guides. In some specific implementations, a platform (such as those shown in Figure 1 or...) Figure 6 The described platform 101 may include a light guide.

[0120] In some examples, the ultrasonic receiver system 102 may include an array of ultrasonic receiver elements. In some such examples, method 1000 may involve receiving an ultrasonic receiver signal from each of a plurality of ultrasonic receiver elements in the array. According to some examples, the array of ultrasonic receiver elements may be or may include a linear array of ultrasonic receiver elements or a two-dimensional array of ultrasonic receiver elements. In some examples, the array of ultrasonic receiver elements may be or may include an array of electrodes disposed on a piezoelectric layer. In some instances, the piezoelectric layer may be or may include lead zirconate titanate (PZT) or a piezoelectric composite.

[0121] According to some examples, method 1000 may involve applying a receiver-side beamforming process to an ultrasonic receiver signal by a control system to produce a beamformed ultrasonic receiver image. In some examples, the receiver-side beamforming process may be or may include a delay-superposition beamforming process. For example, the receiver-side beamforming process may involve referencing... Figure 8A The process described is the same as the process described.

[0122] According to some examples, method 1000 may involve receiving inertial sensor data from an inertial sensor system—such as inertial sensor system 112 of FIG. 1—and controlling an optical steering system at least in part based on the inertial sensor data. For example, method 1000 may involve determining whether the inertial sensor data indicates that the device 100 has moved beyond a threshold, and controlling the optical steering system 105 based on whether the device movement exceeds the threshold.

[0123] In some examples, method 1000 may involve controlling the light steering system 105 to compensate for device movement. For example, if control system 106 determines that device 100 has moved or is moving relative to a target object in contact with the device, method 1000 may involve controlling the light steering system 105 to compensate for device movement. In one such example, if control system 106 determines that device 100 has moved 5 spatial units in the x-direction and 2 spatial units in the y-direction relative to the target object, method 1000 may involve controlling the light steering system 105 to direct light emitted by at least a first light source of light source system 104 to new multiple regions shifted 5 spatial units along the x-axis and 2 spatial units along the y-axis from previous multiple regions.

[0124] In some examples, method 1000 may involve estimating one or more vascular features based at least in part on an additional ultrasound receiver signal. These one or more vascular features may include, for example, vessel diameter, vascular 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 1000 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 1000 may involve estimating blood pressure based at least in part on one or more vascular features. According to some examples, method 1000 may involve extracting and evaluating heart rate waveform (HRW) features.

[0125] Figure 11 It shows that it can be based on Figure 9 Method or Figure 10 Examples of specific implementations of the method for extracting heart rate waveform (HRW) features. Figure 11The 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. The systolic and diastolic time interval is indicated below the horizontal axis. During the systolic phase of cardiac circulation, 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 cardiac circulation, 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.

[0126] Figure 11 The HRW features illustrated herein relate to the width of the systolic and / or diastolic portions of the HRW curve at various “heights,” indicated by a percentage of the maximum amplitude. For example, the SW50 feature is the width of the systolic 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 superposition 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 even more HRW features for blood pressure estimation. In some instances, such additional HRW features may include superposition, difference, ratio, and / or other operations based on more than one “height,” such as (DW75 + SW75) / (DW50 + SW50), (DW50 + SW50 / (DW10 + SW10), etc.

[0127] Figure 12An example of a device is shown that can be used in a system for estimating blood pressure based at least in part on pulse transit time (PTT). 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 1200 includes at least two sensors. In this example, system 1200 includes at least an electrocardiogram sensor 1205 and a device 1210 configured to be mounted on a finger of a person 1201. In this example, device 1210 is or includes means configured to perform at least some of the PAPG methods disclosed herein. For example, device 1210 may be or may include the device 300 of FIG3 or a similar means.

[0128] As mentioned in graph 1220, PAT comprises two components: 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 graph 1220, in this example, the start of PAT can be calculated based on the R-wave peak value measured by ECG sensor 1205, and the end of PAT can be detected by analyzing the signal provided by device 1210. In this example, it is assumed that the end of PAT corresponds to the intersection of the tangent of the local minimum detected by device 1210 and the tangent of the maximum slope / first derivative of the sensor signal after the time of that minimum.

[0129] There are many known blood pressure estimation algorithms based on PTT and / or PAT, some of which are outlined in Table 1 and in Sharma, M. et al., published in Multidisciplinary Digital Publishing Institute (MDPI) Technologies, 2017, 5, 21. Cuff-Less and Continuous Blood Pressure Monitoring: a Methodological Review The description of (“Sharma”) is found in the corresponding text on pages 5 through 10, both of which are hereby incorporated herein by reference.

[0130] Some previously disclosed methods involve 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.

[0131] Other embodiments of system 1200 may not include electrocardiogram sensor 1205. In some such embodiments, device 1215, configured to be mounted on the wrist of person 1201, may be or may include means configured to perform at least some of the PAPG methods disclosed herein. For example, device 1215 may be or may include Figure 2 Device 200 or similar devices. According to some such examples, device 1215 may include a light source system and two or more ultrasonic receivers. See below for reference. Figure 14A An example is described. In some examples, device 1215 may include an array of ultrasonic receivers.

[0132] In some specific embodiments of system 1200 excluding electrocardiogram sensor 1205, device 1210 may include a light source system and two or more ultrasound receivers. See below for reference. Figure 14B An example is described.

[0133] Figure 13 A cross-sectional side view, illustrated, shows a portion of the artery 1300 through which the pulse 1302 propagates. Figure 13 The boxed arrows indicate the direction of blood flow and pulse propagation. As illustrated, the propagating pulse 1302 causes strain in the arterial wall 1304, which manifests as an increase in the diameter (and therefore cross-sectional area) of the arterial wall—a phenomenon referred to as "dilation." The spatial length of the actual propagating pulse along the artery (along the direction of blood flow) is also shown. L It is usually comparable to the length of a limb, such as the distance from the subject's shoulder to their wrist or fingers, and is typically less than one meter (m). However, the length of the pulse transmission... L It can vary greatly between different objects, and for a given object, it may depend on various factors that change significantly over time. Spatial length of the pulse. L It usually decreases as the distance from the heart increases until the pulse reaches the capillaries.

[0134] 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 such terms are also used interchangeably where appropriate; for example, the terms “estimate,” “measure,” “calculate,” “infer,” and “determine” are also 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 traveled by the pulse. Divide by the distance the pulse travels across that physical space The time taken (PTT) is the quotient of the time elapsed. Generally, a first sensor located at a first physical location is used to determine the start time of the pulse's arrival at that point or its propagation through the first physical location (also referred to herein as the "first time location"). A second sensor at a second physical location is used to determine the end time of the pulse's arrival at that point or its propagation through the second physical location and its continuation through the rest 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).

[0135] The fact that arterial dilation waveform measurements are performed 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 the mean. More specifically, PWV typically depends on several factors, including blood density. The stiffness of the arterial wall (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). (Above average).

[0136] 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 many arterial discontinuities, branches, and variations along the entire path from the heart to the finger. Variations in PWV can reach or exceed an 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.

[0137] 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 as “sensor data”), obtained by each of a first arterial dilation sensor 1306 and a second arterial dilation sensor 1308, respectively, along the artery of interest adjacent to a first physical location and a second physical location. In some specific embodiments, the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 are advantageously positioned near the first and second physical locations, such that the arterial properties of the artery of interest between the first and second physical locations 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. Subsequently, blood pressure is estimated based on PWV. This provides a more accurate representation of actual blood pressure. In some specific implementations, the separation distance between the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308... The magnitude (and therefore the distance between the first and second positions along the artery) can range from about 1 centimeter 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 provide a sufficient guarantee of arterial consistency. In some specific implementations, the distance between the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 is... 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 1306 and the second arterial dilation sensor 1308... It 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 non-asylum monitoring device with the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 separated by a distance of about 5 cm and assuming a PWV of about 15 m / s means a PTT of about 3.3 ms.

[0138] The distance between the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 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 Figure 3, or a memory configured to communicate with the control system). As those skilled in the art will understand, in such embodiments, the spatial length of the pulse... L It can be greater than the distance from the first arterial dilation sensor 1306 to the second arterial dilation sensor 1308. Therefore, although Figure 13 The illustrated pulse 1302 is shown to have a spatial length equivalent to the distance between the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308. L 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 1306 and the second arterial dilation sensor 1308. Spatial length L . Sensing architecture and topology

[0139] In some embodiments of the non-asylum monitoring device disclosed herein, the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 are both sensors of the same sensor type. In some such embodiments, the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 are identical sensors. In such embodiments, each of the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 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 1306 and the second arterial dilation sensor 1308 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 ultrasound receivers, which may be examples of the light source system 104 and receiver system 102 of FIG. 1. In some embodiments, each of the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 is configured for ultrasound sensing via the transmission of ultrasound signals and the reception of corresponding reflections. In some alternative embodiments, each of the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 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 1306 and the second arterial dilation sensor 1308 functions broadly to capture and provide arterial dilation data indicating an arterial dilation signal generated by the propagation of a pulse through an artery adjacent to the location of 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.

[0140] As described above, during the systolic phase of cardiac circulation, as the pulse travels along the arteries through a specific location, the arterial walls expand according to the pulse waveform and the elastic properties of the arterial walls. 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 cardiac circulation, blood pressure in the arteries decreases and the arterial walls constrict. 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.

[0141] In the context of bioimpedance sensing (or impedance plethysmography), blood in an artery has a higher conductivity than 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 cardiac circulation, 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.

[0142] 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 circuitry, which may include passive and active components.

[0143] 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.

[0144] In some specific implementations, regardless of the type of sensor used for the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308, both the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 may be arranged, assembled, or otherwise included within a single housing of a single non-ambulatory 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 an object, the first arterial dilation sensor 1306 and the second arterial dilation sensor 1308 are respectively at a distance The separate first and second positions are in contact with or adjacent to the user's skin, and in some embodiments, it can be assumed that the various arterial properties along the arterial extension between them are relatively constant. In various embodiments, the housing of the non-motorized monitoring device is a wearable housing or incorporated into 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 of 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 such or other materials. In some specific embodiments, the housing and coupling mechanism enable fully non-motorized 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, non-bedridden monitoring devices facilitate and enable long-term wear and monitoring (e.g., uninterrupted for days, weeks, or months or more) of one or more biometrics to obtain a better picture of such characteristics over extended periods, and generally, a better picture of the user's health.

[0145] In some implementations, non-bedridden monitoring devices can be positioned around the user's wrist using a strip or band, similar to a watch or fitness / activity tracker. Figure 14AAn example of a non-motorized monitoring device 1400 designed to be worn on the wrist is shown according to some specific embodiments. In the illustrated example, the monitoring device 1400 includes a housing 1402 integrally formed, coupled, or otherwise integrated with a wristband 1404. In some instances, a first arterial dilation sensor 1406 and a second arterial dilation sensor 1408 may each include an example of an ultrasound receiver system 302 described above with reference to FIG. 3 and a light source system 304. In this example, the non-motorized monitoring device 1400 is coupled around the wrist such that the first arterial dilation sensor 1406 and the second arterial dilation sensor 1408 within the housing 1402 are each positioned along a segment of the radial artery 1410 (it should be noted that when the monitoring device is coupled to an object, the sensors are typically concealed when viewed from the object-facing exterior or outer surface of the housing, but exposed on the inner surface of the housing so that the sensors can obtain measurements from the artery beneath the object's skin). Also as shown, the first arterial dilation sensor 1406 and the second arterial dilation sensor 1408 are positioned at a fixed distance. Separately. In some other specific implementations, the non-bedridden monitoring device 1400 may be similarly designed or adapted for positioning using strips or bands around the forearm, upper arm, ankle, lower leg, thigh, or fingers (all of which are referred to below as "limbs").

[0146] Figure 14B An example of a non-bedridden monitoring device 1400 designed to be worn on a finger is shown according to some specific embodiments. In some instances, the first arterial extension sensor 1406 and the second arterial extension sensors 1408 may each include an example of an ultrasound receiver 302 described above with reference to FIG3 and a portion of a light source system 304.

[0147] In some other embodiments, the non-bedridden monitoring device disclosed herein can be positioned on a user’s area of ​​concern without the use of strips or bands. For example, the first arterial dilation sensor 1406 and the second arterial dilation sensor 1408, 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 ​​concern using an adhesive or other suitable attachment mechanism (an example of a “patch” monitoring device).

[0148] Figure 14C An example of a non-bedridden monitoring device 1400 designed to reside on an earplug is shown according to some specific embodiments. According to this example, the non-bedridden monitoring device 1400 is coupled to a housing of an earplug 1420. In some instances, a first arterial dilation sensor 1406 and a second arterial dilation sensor 1408 may each include an example of an ultrasound receiver 302 described above with reference to FIG. 3 and a portion of a light source system 304.

[0149] Specific implementation examples are described in the following numbered clauses: 1. An apparatus comprising: an inertial sensor system including one or more motion detectors; a photoacoustic volumetric plethysmography (PAPG) system including: a light source system configured to provide light to a target object on an outer surface of the apparatus; and an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object in response to the light from the light source system and to generate an ultrasonic receiver signal based at least in part on the ultrasonic waves generated by the target object; and a control system configured to: receive the ultrasonic receiver signal from the ultrasonic receiver system; estimate one or more vascular features based at least in part on the ultrasonic receiver signal; estimate blood pressure based at least in part on the one or more vascular features; receive inertial sensor data from the inertial sensor system; determine whether the inertial sensor data indicates apparatus motion exceeding a threshold; and control the PAPG system based on whether the apparatus motion exceeds the threshold.

[0150] 2. The apparatus according to Clause 1, wherein controlling the PAPG system involves suspending the functionality of the PAPG system when the movement of the apparatus exceeds the threshold.

[0151] 3. The apparatus according to Clause 2, further comprising a user interface system, wherein the control system is further configured to provide a user notification via the user interface system that biometric measurements have been paused.

[0152] 4. The apparatus according to Clause 2 or Clause 3, further comprising a user interface system, wherein the control system is further configured to provide user prompts via the user interface system to remain still to allow biometric measurements to resume.

[0153] 5. The apparatus according to any one of clauses 1 to 4, wherein controlling the PAPG system involves controlling one or more light-directing devices of the light source system when the apparatus moves beyond the threshold.

[0154] 6. The apparatus according to Clause 5, wherein controlling the one or more light-directing devices involves: controlling the one or more light-directing devices to compensate for movement of the apparatus.

[0155] 7. The apparatus according to Clause 5 or Clause 6, wherein the one or more light steering devices comprise one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof.

[0156] 8. The apparatus according to any one of clauses 1 to 7, wherein controlling the PAPG system involves applying a filter to the ultrasonic receiver signal when the movement of the apparatus exceeds the threshold.

[0157] 9. The apparatus according to Clause 8, wherein the application of the filter involves: compensating for the motion of the apparatus.

[0158] 10. The apparatus according to Clause 8 or Clause 9, wherein the filter includes an inverse filter corresponding to the movement of the apparatus.

[0159] 11. The apparatus according to any one of clauses 1 to 10, wherein controlling the PAPG system involves: sequentially activating a plurality of light sources of the light source system when the apparatus moves beyond the threshold.

[0160] 12. The apparatus according to Clause 11, wherein the control system is further configured to: evaluate the signal-to-noise ratio (SNR) of an ultrasonic receiver signal corresponding to an ultrasonic wave generated by the target object in response to light transmitted by each of the plurality of light sources.

[0161] 13. The apparatus according to Clause 12, wherein the control system is further configured to select a light source corresponding to the highest SNR.

[0162] 14. The apparatus according to any one of Clauses 1 to 13, wherein the one or more motion detectors comprise one or more accelerometers.

[0163] 15. The device according to any one of Clauses 1 to 14, wherein the one or more vascular features include vascular diameter, vascular dilation, volumetric flow rate, pulse wave velocity, vascular wall thickness, or a combination thereof.

[0164] 16. The apparatus according to any one of Clauses 1 to 15, wherein the ultrasonic receiver system comprises an array of ultrasonic receiver elements, and wherein the control system is configured to receive an ultrasonic receiver signal from each of the plurality of ultrasonic receiver elements in the array.

[0165] 17. The apparatus according to Clause 16, wherein the array of ultrasonic receiver elements comprises a two-dimensional array of ultrasonic receiver elements.

[0166] 18. The apparatus according to Clause 16 or Clause 17, wherein the array of ultrasonic receiver elements comprises an array of electrodes disposed on a piezoelectric layer.

[0167] 19. The device according to Clause 18, wherein the piezoelectric layer comprises lead zirconate titanate (PZT) or a piezoelectric composite.

[0168] 20. The apparatus according to any one of clauses 16 to 19, wherein the control system is configured to apply a receiver-side beamforming process to the ultrasonic receiver signal to generate a beamformed ultrasonic receiver image.

[0169] 21. The apparatus according to Clause 20, wherein the receiver-side beamforming process includes a delay-overlay beamforming process.

[0170] 22. The device according to any one of clauses 1 to 21, wherein the device is configured to be worn or attached to a person.

[0171] 23. The apparatus according to any one of clauses 1 to 22, wherein the ultrasonic receiver system comprises a transparent material, and wherein the light source system is configured to provide light to the target object through the transparent material.

[0172] 24. An apparatus comprising: an inertial sensor system including one or more motion detectors; a photoacoustic volumetric plethysmography (PAPG) system including: a light source system configured to provide light to a target object on an outer surface of the apparatus; and an ultrasonic receiver system configured to receive ultrasonic waves generated by the target object in response to the light from the light source system and to generate an ultrasonic receiver signal based at least in part on the ultrasonic waves generated by the target object; and a control component for: receiving the ultrasonic receiver signal from the ultrasonic receiver system; estimating one or more vascular features based at least in part on the ultrasonic receiver signal; estimating blood pressure based at least in part on the one or more vascular features; receiving inertial sensor data from the inertial sensor system; determining whether the inertial sensor data indicates apparatus motion exceeding a threshold; and controlling the PAPG system based on whether the apparatus motion exceeds the threshold.

[0173] 25. The apparatus according to Clause 24, wherein controlling the PAPG system involves: suspending the functionality of the PAPG system when the device moves beyond the threshold; controlling the light steering device of the light source system when the device moves beyond the threshold; applying a filter to the ultrasonic receiver signal when the device moves beyond the threshold; sequentially activating a plurality of light sources of the light source system; or a combination thereof, when the device moves beyond the threshold.

[0174] 26. A method comprising: receiving an ultrasound receiver signal from an ultrasound receiver system corresponding to an ultrasound wave generated by a target object in response to light from a light source system; estimating one or more vascular features based at least in part on the ultrasound receiver signal; estimating blood pressure based at least in part on the one or more vascular features; receiving inertial sensor data from an inertial sensor system; determining whether the inertial sensor data indicates device motion exceeding a threshold; and controlling a photoacoustic volumetric plethysmography (PAPG) system including the light source system and the ultrasound receiver system based on whether the device motion exceeds the threshold.

[0175] 27. The method according to Clause 26, wherein controlling the PAPG system involves: suspending the functionality of the PAPG system when the device moves beyond the threshold.

[0176] 28. The method according to Clause 26 or Clause 27, wherein controlling the PAPG system involves controlling the light steering device of the light source system when the device moves beyond the threshold.

[0177] 29. The method according to any one of clauses 26 to 28, wherein controlling the PAPG system involves applying a filter to the ultrasonic receiver signal when the device moves beyond the threshold.

[0178] 30. The method according to any one of clauses 26 to 29, wherein controlling the PAPG system involves: sequentially activating a plurality of light sources of the light source system when the device moves beyond the threshold.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] Additionally, some features described in this specification within the context of individual embodiments may also be implemented in combination within a single embodiment. Conversely, features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, while 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 extracted from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0190] 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 multiple 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 this in all embodiments. Thus, 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. An apparatus, the apparatus comprising: An inertial sensor system, the inertial sensor system including one or more motion detectors; A photoacoustic volumetric plethysmography (PAPG) system, the PAPG system comprising: A light source system configured to provide light to a target object on the outer surface of the device; and An ultrasonic receiver system configured to receive ultrasonic waves generated by the target object in response to light from the light source system and to generate an ultrasonic receiver signal based at least in part on the ultrasonic waves generated by the target object; and The control system is configured to: Receive the ultrasonic receiver signal from the ultrasonic receiver system; One or more vascular features are estimated, at least in part, based on the ultrasound receiver signal; Blood pressure is estimated at least in part based on one or more of the aforementioned vascular features; Receive inertial sensor data from the inertial sensor system; Determine whether the inertial sensor data indicates device motion exceeding a threshold; and The PAPG system is controlled based on whether the movement of the device exceeds the threshold.

2. The apparatus of claim 1, wherein controlling the PAPG system involves suspending the functionality of the PAPG system when the movement of the apparatus exceeds the threshold.

3. The apparatus of claim 2, further comprising a user interface system, wherein the control system is further configured to provide a user notification via the user interface system that biometric measurements have been paused.

4. The apparatus of claim 2, further comprising a user interface system, wherein the control system is further configured to provide user prompts via the user interface system to remain still to allow biometric measurements to resume.

5. The apparatus of claim 1, wherein controlling the PAPG system involves controlling one or more light-directing devices of the light source system when the apparatus moves beyond the threshold.

6. The apparatus of claim 5, wherein controlling the one or more light-directing devices involves controlling the one or more light-directing devices to compensate for movement of the apparatus.

7. The apparatus of claim 5, wherein the one or more light steering devices comprise one or more adjustable micromirrors, one or more adjustable lenses, one or more adjustable diffraction gratings, or combinations thereof.

8. The apparatus of claim 1, wherein controlling the PAPG system involves applying a filter to the ultrasonic receiver signal when the apparatus moves beyond the threshold.

9. The apparatus of claim 8, wherein applying the filter relates to compensating for the movement of the apparatus.

10. The apparatus of claim 8, wherein the filter comprises an inverse filter corresponding to the movement of the apparatus.

11. The apparatus of claim 1, wherein controlling the PAPG system involves: sequentially activating a plurality of light sources of the light source system when the apparatus moves beyond the threshold.

12. The apparatus of claim 11, wherein the control system is further configured to: evaluate the signal-to-noise ratio (SNR) of an ultrasonic receiver signal corresponding to an ultrasonic wave generated by the target object in response to light transmitted from each of the plurality of light sources.

13. The apparatus of claim 12, wherein the control system is further configured to select a light source corresponding to the highest SNR.

14. The apparatus of claim 1, wherein the one or more motion detectors comprise one or more accelerometers.

15. The apparatus of claim 1, wherein the one or more vascular features include vascular diameter, vascular dilation, volumetric flow rate, pulse wave velocity, vascular wall thickness, or combinations thereof.

16. The apparatus of claim 1, wherein the ultrasonic receiver system comprises an array of ultrasonic receiver elements, and wherein the control system is configured to receive an ultrasonic receiver signal from each of the plurality of ultrasonic receiver elements in the array.

17. The apparatus of claim 16, wherein the array of ultrasonic receiver elements comprises a two-dimensional array of ultrasonic receiver elements.

18. The apparatus of claim 16, wherein the array of ultrasonic receiver elements comprises an array of electrodes disposed on a piezoelectric layer.

19. The device of claim 18, wherein the piezoelectric layer comprises lead zirconate titanate (PZT) or a piezoelectric composite.

20. The apparatus of claim 16, wherein the control system is configured to apply a receiver-side beamforming process to the ultrasonic receiver signal to generate a beamformed ultrasonic receiver image.

21. The apparatus of claim 20, wherein the receiver-side beamforming process includes a delay-superposition beamforming process.

22. The device of claim 1, wherein the device is configured to be worn or attached to a person.

23. The apparatus of claim 1, wherein the ultrasonic receiver system comprises a transparent material, and wherein the light source system is configured to provide light to the target object through the transparent material.

24. An apparatus comprising: An inertial sensor system, the inertial sensor system including one or more motion detectors; A photoacoustic volumetric plethysmography (PAPG) system, the PAPG system comprising: A light source system configured to provide light to a target object on the outer surface of the device; and An ultrasonic receiver system configured to receive ultrasonic waves generated by the target object in response to light from the light source system and to generate an ultrasonic receiver signal based at least in part on the ultrasonic waves generated by the target object; and Control unit, the control unit being used for: Receive the ultrasonic receiver signal from the ultrasonic receiver system; One or more vascular features are estimated, at least in part, based on the ultrasound receiver signal; Blood pressure is estimated at least in part based on one or more of the aforementioned vascular features; Receive inertial sensor data from the inertial sensor system; Determine whether the inertial sensor data indicates device motion exceeding a threshold; and The PAPG system is controlled based on whether the movement of the device exceeds the threshold.

25. The apparatus of claim 24, wherein controlling the PAPG system comprises: suspending the functionality of the PAPG system when the device moves beyond the threshold; controlling the light steering device of the light source system when the device moves beyond the threshold; applying a filter to the ultrasonic receiver signal when the device moves beyond the threshold; sequentially activating a plurality of light sources of the light source system; or a combination thereof, when the device moves beyond the threshold.

26. A method, the method comprising: Receives an ultrasonic receiver signal from the ultrasonic receiver system that corresponds to the ultrasonic wave generated by the target object in response to light from the light source system; One or more vascular features are estimated, at least in part, based on the ultrasound receiver signal; Blood pressure is estimated at least in part based on one or more of the aforementioned vascular features; Receive inertial sensor data from the inertial sensor system; Determine whether the inertial sensor data indicates device motion exceeding a threshold; and The photoacoustic volumetric plethysmography (PAPG) system, comprising the light source system and the ultrasonic receiver system, is controlled based on whether the movement of the device exceeds the threshold.

27. The method of claim 26, wherein controlling the PAPG system involves suspending the functionality of the PAPG system when the device moves beyond the threshold.

28. The method of claim 26, wherein controlling the PAPG system involves controlling the light steering device of the light source system when the device moves beyond the threshold.

29. The method of claim 26, wherein controlling the PAPG system involves applying a filter to the ultrasonic receiver signal when the device moves beyond the threshold.

30. The method of claim 26, wherein controlling the PAPG system involves sequentially activating a plurality of light sources to estimate the light source system when the device moves beyond the threshold.

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