Pulse group based driving method for controlling a light source of a photoacoustic device

Abstract

Some disclosed examples involve directing two or more groups of optical pulses toward a target object during a total optical transmit time interval, each pulse group time interval within the total optical transmit time interval being spaced apart from a successive pulse group time interval by a break time interval. The target object can be a portion of a human or animal body. In some examples, no light is transmitted toward the target object during the break time interval. Some disclosed examples involve receiving acoustic signals corresponding to a photoacoustic (PA) response of the target object to the two or more pulse groups and determining one or more heart rate waveforms of the human or animal body based on the acoustic signals.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Patent Application No. 18 / 468,934, filed September 18, 2023, entitled “PULSE GROUP-BASED DRIVE METHODSFOR CONTROLLING LIGHT SOURCES OF PHOTOACOUSTIC DEVICES,” which is incorporated herein by reference and for all purposes. Technical Field

[0003] This disclosure relates in general to photoacoustic devices, and more specifically to light sources for controlling photoacoustic devices.

[0004] Related technical descriptions

[0005] Various sensing technologies and algorithms are being implemented in devices for a wide range of biometric and biomedical applications, including health and wellness monitoring. This push is partly due to the limited availability 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, improvements in photoacoustic devices and systems are desirable. Summary of the Invention

[0006] The systems, methods, and apparatuses disclosed herein each have multiple aspects, and no single aspect is solely responsible for the desired properties disclosed herein.

[0007] One innovative aspect of the subject matter described in this disclosure can be implemented in an apparatus. The apparatus may include a light source system, a receiver system, and a control system configured to electrically communicate with the light source system and the receiver system. The receiver system may be or may include an ultrasonic receiver system. In some examples, the receiver system may include an array of ultrasonic receiver elements. In some embodiments, a mobile device (such as a wearable device, a cellular phone, etc.) may be at least part of the apparatus or may include at least part of the apparatus.

[0008] 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 components, discrete hardware components, or combinations thereof. The control system may be configured to control the light source system to direct two or more groups of light pulses toward a target object during a total light transmission interval. The target object may be part of a human or animal body. In some examples, the time interval for each group of pulses within the total light transmission interval may be separated from the time interval for consecutive groups of pulses by an “interruption interval” during which no light is transmitted toward the target object. The control system may be configured to receive, via the receiver system, a receiver signal corresponding to the acoustic waves generated by the photoacoustic (PA) response of the target object to the two or more groups of pulses. The control system may be configured to determine one or more heart rate waveforms of the human or animal body based on the receiver signal.

[0009] In some examples, the control system may be configured to estimate one or more cardiac characteristics, at least in part, based on the one or more heart rate waveforms. In some such examples, estimating the one or more cardiac characteristics may involve estimating blood pressure.

[0010] According to some examples, the exposure duration is equal to a pulse group time interval plus an interruption time interval. In some such examples, the average optical power density during this exposure duration can be as low as 0.01 W / cm². 2 Up to 1.00 W / cm 2 Within this range. In some examples, the average optical power density during this exposure duration is less than the maximum permissible exposure (MPE) corresponding to the wavelength of the emitted light, as published by the American National Standards Institute's Laser Safety Use Standards.

[0011] Other inventive aspects of the subject matter described in this disclosure can be implemented in a method. This method may involve directing two or more groups of optical pulses toward a target object, which is part of a human or animal body, during a total optical transmission time interval. In some examples, the time interval of each group of pulses within the total optical transmission time interval may be separated from the time interval of consecutive groups of pulses by an interruption time interval during which no light is transmitted toward the target object. The method may also involve receiving an acoustic signal corresponding to the photoacoustic (PA) response of the target object to the two or more groups of pulses and determining one or more heart rate waveforms of the human or animal body based on the acoustic signal.

[0012] In some examples, the method may involve estimating one or more cardiac features based at least in part on the one or more heart rate waveforms. In some such examples, estimating the one or more cardiac features may involve estimating blood pressure.

[0013] 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.

[0014] Details of one or more specific embodiments of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. Note that the relative dimensions in the following drawings may not be drawn to scale. Attached Figure Description

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

[0016] Figure 2A and Figure 2B An example of a driving scheme for controlling a light source system is shown.

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

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

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

[0020] Figure 4 Example components of a device according to some alternative specific implementations are shown.

[0021] Figure 5 Example components of a device according to some alternative specific implementations are shown.

[0022] Figure 6 An example of a device configured to perform a receiver-side beamforming process is shown.

[0023] Figure 7 This is a flowchart illustrating some examples of the disclosed operations.

[0024] Figure 8 It shows that it can be based on Figure 7 Examples of specific implementations of the method for extracting heart rate waveform (HRW) features.

[0025] Figure 9 An example of a device that can be used in a system for estimating blood pressure based at least in part on pulse conduction time (PTT) is shown.

[0026] Figure 10 A cross-sectional side view showing a schematic representation of a portion of an artery through which a pulse is propagating.

[0027] Figure 11A An example of a non-recumbent monitoring device designed to be worn on the wrist is shown according to some specific implementations.

[0028] Figure 11B An example of a non-recumbent monitoring device designed to be worn on a finger is shown according to some specific implementations.

[0029] Figure 11C An example of a non-recumbent monitoring device designed to reside on an earpiece is shown according to some specific implementations.

[0030] Similar reference numerals and names in the various figures indicate similar elements. Detailed Implementation

[0031] The following description is directed to certain implementations and is intended to describe various aspects of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in many different ways. Some of the concepts and examples provided in this disclosure are particularly applicable to blood pressure monitoring applications. However, some specific embodiments are also applicable to other types of biosensing applications, as well as other fluid flow systems. The described specific embodiments can be implemented in any device, apparatus, or system that includes the means disclosed herein. Furthermore, it is contemplated that the described specific embodiments can be included in or associated with a variety of electronic devices, such as, but not limited to: mobile phones, cellular phones implemented with multimedia 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, netbooks, laptops, smart e-readers, tablets, printers, copiers, 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 rearview camera displays in vehicles), building structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washing machines, dryers, washer / dryer units, parking meters, car doors, autonomous or semi-autonomous vehicles, drones, Internet of Things (IoT) devices, etc. Therefore, this teaching is not intended to be limited to the specific particular embodiments depicted and described with reference to the accompanying drawings; rather, its broad applicability will be readily apparent to those skilled in the art.

[0032] 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)) have various potential advantages. However, it has proven difficult to design satisfactory PAPG-based devices. One challenge is the low signal-to-noise ratio (SNR) of the signal being monitored (such as the signal corresponding to ultrasound waves induced by the photoacoustic response of the arterial wall). For example, the amplitude of the signal corresponding to the arterial wall is typically significantly lower than that corresponding to the photoacoustic response of the skin. The SNR can be enhanced by reducing irrelevant noise. Some currently implemented methods involve delivering continuous laser pulses to the target object using a continuous pulse repetition frequency (PRF), followed by averaging the data corresponding to the photoacoustic (PA) responses of the target object on multiple samples (such as 100 or more). The SNR can also be enhanced by increasing the power of the light source. However, for PAPG-based methods, it is necessary to avoid using excessively strong light sources (such as laser sources) that could damage human skin. The American National Standards Institute (ANSI) has published Maximum Permissible Exposure (MPE) standards for safe use of lasers. These MPE standards indicate average power limits and single-pulse limits for lasers transmitted at various wavelengths to ensure the safety of skin and eyes exposed to lasers.

[0033] Some of the disclosed devices include a light source system, an ultrasonic receiver system, and a control system. According to some specific embodiments, the control system can be configured to control the light source system according to a pulse group-based driving scheme. Some disclosed examples involve directing two or more groups of light pulses toward a target object during a total light transmission interval. In some such examples, each pulse group time interval within the total light transmission interval may be separated from the continuous pulse group time interval by what will be referred to herein as an “interruption time interval.” An interruption time interval is a time interval during which no light is transmitted toward the target object. However, in some alternative examples, instead of interruption time intervals, there may be “lower intensity” time intervals between continuous pulse group time intervals, during which the intensity of light transmitted toward the target object is much lower than the intensity of light transmitted during the pulse group time intervals, and “lower PRF” time intervals between continuous pulse group time intervals, during which the light transmitted toward the target object has a very low PRF or both. In some alternative examples, the lower intensity interval can be a time interval in which the intensity of light transmitted toward the target object during the pulse group interval is one-tenth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, or one-hundredth of the intensity of light transmitted during the pulse group interval, etc. In some alternative examples, the time interval between consecutive pulse group intervals can be a time interval in which the intensity of light transmitted toward the target object during the pulse group interval is the same as the intensity of light transmitted during the pulse group interval, but this time interval is a "lower PRF" time interval in which light is transmitted at one-tenth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, etc., of the PRF. In some specific implementations, the control system can be configured to receive a receiver signal corresponding to the acoustic waves generated by the photoacoustic (PA) response of the target object to two or more pulse groups, and to determine one or more heart rate waveforms, one or more vascular features, or both, based on the receiver signal. In some examples, the control system may be configured to estimate one or more cardiac features, at least in part, based on one or more heart rate waveforms, one or more vascular features, or both. According to some examples, estimating these one or more cardiac features may involve estimating blood pressure.

[0034] Specific embodiments of the subject matter described in this disclosure can be implemented to achieve one or more of the following potential advantages. Various disclosed configurations include PAPG-equipped devices that can provide higher SNR compared to previously deployed PAPG-equipped devices. Some such examples relate to pulse group-based driving schemes for light source systems, where each pulse group time interval within the total light transmission time interval is separated from the continuous pulse group time interval by an interruption time interval. Some examples relate to increasing the PRF during the pulse group time interval compared to the PRF used in previously implemented continuous PRF driving schemes. Some such examples have the potential benefit of reducing irrelevant noise and thus increasing SNR, while maintaining below the MPE limit of the maximum average optical power density, etc. Furthermore, some disclosed examples have the potential benefit of saving power by driving the light source system for less time and potentially using less total power.

[0035] Figure 1 This is a block diagram illustrating example components of an apparatus according to some of the disclosed embodiments. In this example, apparatus 100 includes a receiver system 102, a light source system 104, and a control system 106. According to some examples, receiver system 102 is or includes an ultrasonic receiver system. Some embodiments of apparatus 100 may include a pressure plate 101, an interface system 108, a noise reduction system 110, or combinations thereof. As with other disclosed embodiments, in some alternative embodiments, apparatus 100 may include more components, fewer components, or different components.

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

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

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

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

[0040] In some examples, receiver system 102 may include a piezoelectric receiver layer, such as a PVDF polymer layer, a PVDF-TrFE copolymer layer, or a piezoelectric composite layer. In some implementations, other piezoelectric materials, such as aluminum nitride (AlN) or lead zirconate titanate (PZT), may be used in the piezoelectric layer. In some examples, receiver system 102 may include an array of ultrasonic receiver elements. This array may be a linear array, a two-dimensional array, etc. In some examples, the array may include an array of electrodes residing on the piezoelectric material layer. In some examples, 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, PMUT elements in a monolayer PMUT array, or CMUT elements in a monolayer CMUT array may be used as both an ultrasonic transmitter and an ultrasonic receiver. According to some examples, receiver system 102 may be or may include an ultrasonic receiver array. In some examples, device 100 may include one or more individual ultrasonic transmitter elements. In some such examples, the ultrasonic transmitter may include an ultrasonic plane wave generator.

[0041] 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. 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.

[0042] In some examples, the light source system 104 may be configured to transmit light within one or more wavelength ranges. In some examples, the light source system 104 may be configured to transmit light within a wavelength range of 500 nanometers to 600 nanometers. According to some examples, the light source system 104 may be configured to transmit light within a wavelength range of 800 nanometers to 950 nanometers.

[0043] 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 with pulse repetition frequencies ranging from 1 kHz to 100 kHz.

[0044] In some embodiments, the light source system 104 may be configured to emit light of various wavelengths, which may be selectable to trigger acoustic emission primarily from a particular type of material. For example, because hemoglobin in blood absorbs near-infrared light very strongly, in some embodiments, the light source system 104 may be configured to emit light of one or more wavelengths in the near-infrared range to trigger acoustic emission from hemoglobin. However, in some examples, the control system 106 may control the wavelength of the light emitted by the light source system 104 to preferably sense acoustic waves in blood vessels, other soft tissues, and / or bones. For example, an infrared (IR) light-emitting diode (LED) may be selected and emits short pulses of IR light to illuminate a portion of a target object and generate acoustic emission, which is subsequently detected by the receiver system 102. In another example, an IR LED and a red LED or other color (such as green, blue, white, or ultraviolet (UV)) may be selected and short light pulses may be emitted sequentially from each light source, wherein an ultrasound image is obtained after each light source emits light. In other specific implementations, one or more light sources of different wavelengths can be illuminated sequentially or simultaneously to generate acoustic emissions detectable by an ultrasound receiver. Image data obtained from the ultrasound receiver using light sources of different wavelengths and at different depths (e.g., varying RGDs) within the target object can be combined to determine the location and type of material within the target object. Since materials within the body typically absorb light of different wavelengths differently, image contrast may occur. When materials within the body absorb light of a specific wavelength, they may heat up differently and generate acoustic emissions of sufficiently short light pulses with sufficient intensity. 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 within a target object such as a finger can be detected photoacously.

[0045] 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 may be emitted from the light source system 104 at a frequency corresponding to the resonant frequency of the resonant acoustic cavity in the sensor stack, thereby allowing the received ultrasonic waves to accumulate and the resulting signal strength to be higher. In some embodiments, filtered light or a light source with a specific wavelength for detecting selected materials may be included in the light source system 104. In some embodiments, the light source system may include light sources such as red, green, and blue LEDs for displays, which may be enhanced using light sources of other wavelengths (such as IR and / or UV) and light sources with higher optical power. For example, high-power laser diodes or electronic flash units (e.g., LED or xenon flash units) with or without filters may be used for short-term illumination of the target object.

[0046] 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 components, discrete hardware components, or combinations thereof. The control system 106 may also include (and / or be configured to communicate with) one or more memory devices such as one or more random access memory (RAM) devices, read-only memory (ROM) devices, etc. Therefore, the device 100 may have a memory system including one or more memory devices, but... Figure 1 The memory system is not shown. The control system 106 can be configured to receive and process data from the 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.

[0047] In some examples, the control system 106 may be configured to control the light source system 104 to direct two or more groups of light pulses toward a target object during a total light transmission interval. In some such examples, the time interval between each group of pulses within the total light transmission interval may be separated from the time interval between consecutive groups of pulses by an “interruption time interval.” In some instances, the interruption time interval may be a time interval during which no light is transmitted toward the target object. However, in some alternative examples, the time interval between consecutive group of pulses may be a time interval in which the intensity, PRF, or both of the light transmitted toward the target object during that time interval are significantly lower than the intensity, PRF, or both of the light transmitted during the pulse group of pulses interval. According to some alternative examples, the time interval between consecutive group of pulses may be a time interval in which the light transmitted toward the target object during that time interval has an intensity below a first threshold, a PRF below a second threshold, or both. In some alternative examples, the time interval between consecutive pulse group intervals can be a lower intensity time interval such that the intensity of light transmitted toward the target object during this lower intensity time interval is one-tenth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, or one-hundredth of the intensity of light transmitted during the pulse group interval, etc. In some alternative examples, the time interval between consecutive pulse group intervals can be a "lower PRF" time interval such that the intensity of light transmitted toward the target object during this "lower PRF" time interval is the same as the intensity of light transmitted during the pulse group interval, but one-tenth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, one-hundredth, or one-hundredth of the PRF, etc. In some alternative examples, the time interval between consecutive pulse group intervals can be a time interval such that the light transmitted toward the target object during this time interval has a different intensity (e.g., lower intensity) than the light transmitted during the pulse group interval, and is also transmitted with a different PRF (e.g., lower PRF).

[0048] In some implementations, control system 106 may be configured to receive from receiver system 102 a receiver signal corresponding to an acoustic wave caused by a photoacoustic (PA) response of a target object to two or more pulse groups, and to determine one or more heart rate waveforms, one or more vascular features, or both, based on the receiver signal. In some examples, control system 106 may be configured to estimate one or more cardiac features, at least in part, based on one or more heart rate waveforms, one or more vascular features, or both. According to some examples, estimating the one or more cardiac features may involve estimating blood pressure. In some examples, control system 106 may be configured to receive from receiver system 102 a receiver signal corresponding to an acoustic wave caused by a PA response of a target object to two or more pulse groups, and to determine one or more cardiac features, such as blood pressure, based on the receiver signal. In some such examples, control system 106 may be configured to determine one or more cardiac features based on the receiver signal without intermediate processes of determining one or more heart rate waveforms, one or more vascular features, or both. In some examples, control system 106 may be configured to implement a neural network trained to estimate one or more cardiac features, potentially including blood pressure, using the receiver signal as input. For example, a neural network can be trained using blood pressure measurements from blood pressure measurement devices (such as cuff-based, catheter-based, or other blood pressure measurement devices) as "real values" in the neural network training process.

[0049] As mentioned elsewhere, according to some examples, receiver system 102 may include an array of receiver elements. In some such examples, 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, 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, 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, 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.

[0050] Some specific implementations of device 100 may include interface system 108. In some examples, interface system 108 may include a wireless interface system. In some specific implementations, 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, interface system 108 has and includes a user interface system, which 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.

[0051] 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.

[0052] 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 receiver system 102. In some implementations, noise reduction system 110 may include one or more sound-absorbing layers, sound-insulating materials, light-absorbing materials, reflective 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 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 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, reflective materials, or combinations thereof may be components of receiver system 102, light source system 104, or both. Although in fact the receiver system 102, the light source system 104 and the noise reduction system 110 are in Figure 1 While shown as a separate component, such components can still be considered as elements of the noise reduction system 110.

[0053] 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.

[0054] Figure 2A and Figure 2B Examples of driving schemes for controlling a light source system are shown. In these examples, time is represented along a horizontal axis and proceeds from left to right. According to these examples, "pulse width" is the duration or time interval of a single light pulse. As used herein, the terms "duration" and "time interval" are used synonymously.

[0055] Figure 2AAn example of a driving scheme for controlling the continuous pulse repetition frequency (PRF) of a light source system is shown. According to this example, the pulse group time interval, the total exposure duration, and the total light transmission time interval are all equal. In one example, the transmitted light has a wavelength of 905 nanometers (nm), the pulse width of each light pulse is 200 nanoseconds (ns), the PRF is 3.2 kHz, and the pulse group time interval, the total exposure duration, and the total light transmission time interval are all 20 seconds (s). As used herein, the terms "pulse group" and "light pulse group" have the same meaning. Different specific implementations may involve different parameters.

[0056] However, for PAPG implementation devices used in the United States that employ lasers as a light source for human subjects, the average power limit and single-pulse limit of the emitted laser wavelength must be less than or equal to the Maximum Permissible Exposure (MPE) standard published by the American National Standards Institute (ANSI) for the safe use of lasers (ANSI Z136.1). For example, this applies to laser sources with wavelengths in the range of 400 nm to 1400 nm and total exposure durations. t It is 10 -7 From s to 10s, the MPE is 1.1 C. A t 0.25 C A It is a wavelength-dependent correction factor. For wavelengths in the range of 400nm to 700nm, C A It is 1.0, for wavelengths in the range of 700nm to 1050nm, C A It is 10 0.002(λ-700) Furthermore, for wavelengths in the range of 1050nm to 1400nm, C A It is 5.0. This applies to laser sources with wavelengths ranging from 400nm to 1400nm and a total exposure duration. t The range is from 10s to 30,000s, and the MPE is 0.2 C. A .

[0057] The amplitude of the uncorrelated noise is proportional to 1 / sqrt(N), where N represents the number of samples. In some examples, N can be 100 or greater. Based on some continuous PRF examples, the PRF is 3.2kHz and the effective PRF required for a particular use case is 25Hz, so N = 3.2kHz / 25Hz = 128 samples. Different implementations may involve averaging different numbers of samples.

[0058] Due to MPE limitations, it's impossible to simultaneously achieve high peak optical power density (POP) and high peak power density (PRF). Since POP is proportional to the obtained PA signal, some PAPG implementations may prioritize POP at the expense of high PRF. Maximum average optical power density = Peak optical power density. Pulse width PRF. Some successive PRF implementations maximize peak optical power density and optimize the pulse width of the PA signal amplitude. Therefore, the PRF is limited, which in turn limits the noise reduction that can be achieved by averaging.

[0059] Figure 2B An example of a pulse-group-based driving scheme for controlling a light source system is shown. According to this example, the pulse group time interval, total exposure duration, and total light transmission time interval are all different. In one example, the transmitted light has a wavelength of 905 nanometers (nm), a pulse width of 200 nanoseconds (ns), a PRF of 7.7 kHz, a pulse group time interval of 3.0 s, an interruption time interval between pulse groups of 4.2 s, and a total exposure duration (the sum of one pulse group time interval and one interruption time interval) of 7.2 s. In another example of this type, there are a total of three pulse groups and the total light transmission time interval is 17.4 seconds. (Refer to the above) Figure 2A Compared to the described example, Figure 2B This particular example enables devices equipped with PAPGs to maintain below the maximum average optical power density while reducing unrelated noise by a factor of (7.7 / 3.2). 0.5 =1.6.

[0060] Different specific implementations may involve different parameters, including but not limited to different numbers of pulse groups in the total light transmission time interval. In various disclosed examples, the average optical power density during the exposure duration is less than the MPE corresponding to the wavelength of the transmitted light as specified in the American National Standards Institute (ANSI) laser safety use standards (such as ANSI Z136.1) and the international standard for laser product safety (IEC 60825-1). In some such examples, the pulse group time interval can range from 0.0014 seconds to 7 seconds. According to some examples, the interruption time interval can range from 2 seconds to 5 seconds, such as 2.0 seconds, 2.5 seconds, 3.0 seconds, 3.5 seconds, 4.0 seconds, 4.5 seconds, 5.0 seconds, etc.

[0061] In some examples, the width of each optical pulse in the pulse group can range from 50 nanoseconds to 500 nanoseconds. According to some examples, the total light transmission time interval can range from 9 seconds to 25 seconds. In some examples, the PRF of the optical pulses in the pulse group can range from 0.5 kHz to 200 kHz. According to some examples, the peak amplitude of each optical pulse in the pulse group can range from 600 nm to 1064 nm in wavelength. In some examples, the average optical power density during the exposure duration can be 0.01 W / cm². 2 Up to 1.00 W / cm 2 Within the range.

[0062] In some examples, PA technology is used to estimate blood pressure, and for slow heart rate waveforms (HRW) with a period of up to 2 seconds, pulse group intervals of several seconds (such as 2.5 seconds, 3.0 seconds, etc.) may be required. However, for other use cases or for use cases involving HRWs with a period of less than 2 seconds, this limitation may not exist.

[0063] Skin and eye safety are both essential requirements for meeting laser safety standards. When used correctly, the disclosed embodiments also meet eye safety requirements. In many of the disclosed embodiments, for example, when the device is used correctly, light is delivered directly to the skin within the wearable device, thus protecting the user's eyes. Figure 2C , Figure 4 , Figure 9 and Figures 11A to 11C An example of such a device is shown.

[0064] Figure 2C Example components of an apparatus according to some of the disclosed specific embodiments are shown. (As with other appendices provided herein...) Figure 1 Sample, Figure 2C The number, type, and arrangement of the components shown are presented by way of example only. In this example, device 100 is Figure 1 An example of device 100 is shown. According to this example, device 100 includes a pressure plate 101, a receiver system 102, and a light source system 104. In this example, the outer surface 208a of the pressure plate 101 is configured to receive a target object (such as a finger 255, wrist, etc.). In some examples, device 101 may be configured to implement one or more of the pulse group-based driving schemes disclosed herein for controlling the light source system 104.

[0065] According to this example, receiver system 102 is or includes an ultrasonic receiver system. In this example, receiver system 102 includes receiver stack portion 102a and receiver stack portion 102b. In this example, receiver stack portion 102a includes piezoelectric material 215a, electrode layer 220a on a first side of piezoelectric material 215a, and electrode layer 222a on a second side of piezoelectric material 215a. According to some examples, an anisotropic conductive film (ACF) layer may reside between each of electrode layers 220a and 220b and piezoelectric material 215a. In this example, electrode layer 222a resides between piezoelectric material 215a and backing layer 230a. In some instances, electrode layers 220a and 220b include a conductive material, which may be or may include a conductive metal, such as copper. Electrode layers 220a and 220b may be electrically connected to receiver system circuitry, which in... Figure 2C The receiver system circuitry is not shown in the diagram. It may be considered a reference to this document. Figure 1 This is a portion of the described control system 106, a portion of the receiver system 102, or both. The piezoelectric material 215a may, for example, include a polyvinylidene fluoride (PVDF) polymer, a polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer, aluminum nitride (AlN), lead zirconate titanate (PZT), piezoelectric composite materials (such as 1-3 composites, 2-2 composites, 3-3 composites, etc.), or combinations thereof. The backing layer 230a may be configured to suppress at least some acoustic artifacts and provide a relatively higher signal-to-noise ratio (SNR) than the receiver system 102 without a backing layer. In some examples, the backing layer 230a may comprise a metal, an epoxy resin, or a combination thereof.

[0066] In this example, the receiver stack portion 102b includes a piezoelectric material 215b, an electrode layer 220b on a first side of the piezoelectric material 215b, and an electrode layer 222b on a second side of the piezoelectric material 215b. Here, the electrode layer 222b resides between the piezoelectric material 215b and the backing layer 230b. According to this example, the receiver stack portion 102a resides near the first side of the light guide assembly 240a, and the receiver stack portion 102b resides near the second side of the light guide assembly 240a. In this example, the piezoelectric materials 215a and 215b are configured to generate electrical signals in response to received acoustic waves (such as photoacoustic waves PA1 and PA2).

[0067] According to this example, the light source system 104 includes at least a first light-emitting component (light-emitting component 235a in this example), at least a first light-guiding component (light-guiding component 240a in this example), and a light source system circuit 245a. The light-emitting component 235a may, for example, include one or more light-emitting diodes, one or more laser diodes, one or more VCSELs, one or more edge-emitting lasers, one or more neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers, or combinations thereof.

[0068] The light guide assembly 240a may include any suitable material or combination of materials for propagating at least some of the light emitted by the light-emitting assembly 235a within the light guide assembly 240a, for example, due to total internal reflection between one or more core materials and one or more cladding materials. In such examples, the core material will have a higher refractive index than the cladding material. In a particular and non-limiting example, the core material may have a refractive index of about 1.64, and the cladding material may have a refractive index of about 1.3. In some examples, the core material may include glass, silica, quartz, plastic, zirconium fluoride, chalcogenides, or combinations thereof. According to some examples, the cladding material may include polyvinyl chloride (PVC), acrylic, polytetrafluoroethylene (PTFE), polysiloxane, or fluorocarbon rubber. In some examples, the light guide assembly 240a may include one or more optical fibers. As used herein, the terms “light guide” and “optical tube” are used synonymously.

[0069] In some examples, the width W3 of the light guide component 240a can be in the range of 0.25 mm to 3 mm, such as 0.5 mm, 1.0 mm, 1.5 mm, etc. According to some examples, the width W2 of the space between the receiver stack portion 102a and the receiver stack portion 102b can be in the range of 0.5 mm to 5 mm, such as 1.0 mm, 1.5 mm, 2 mm, 2.5 mm, etc. In some examples, the space 233a between the receiver stack portion 102a and the light guide component 240a, and the space 233b between the receiver stack portion 102b and the light guide component 240a (if any) (in other words, the space between W2 and W3 (if any)) may include light-absorbing material. According to some examples, spaces 233a and 233b (if any) may include air. In some examples, spaces 233a and 233b (if any) may include sound-absorbing material, preferably a sound-absorbing material with a relatively low Grünersen parameter.

[0070] In this example, the light source system 104 is configured to emit light toward a target object in contact with the first region of the pressure plate 101 through the first region of the pressure plate. According to this example, the light source system 104 is configured to direct light (in the direction of contact) through the light guide assembly 240a and the pressure plate region 201a. Figure 2CThe light rays (represented by ray 250a and 250b) are directed toward the finger 255 in contact with the pressure plate area 201a. In this example, the arterial wall of the artery 207 generates photoacoustic waves PA1 and PA2 in response to the light rays 250a and 250b, respectively.

[0071] The pressure plate 101 may comprise any suitable material, such as glass, acrylic resin, polycarbonate, combinations thereof, etc. In some examples, the width W1 of the pressure plate 101 may range from 2 mm to 10 mm, for example, 4 mm, 5 mm, 6 mm, etc. According to some examples, the thickness of the pressure plate 101 (in...) Figure 2C The coordinate system shown can be in the range of 50 micrometers to 500 micrometers (in the z direction), for example, 150 micrometers, 200 micrometers, 250 micrometers, 300 micrometers, etc.

[0072] In this example, the pressure plate 101 includes pressure plate regions 201a, 201b, and 201c. In this example, pressure plate region 201a resides adjacent to the light guide component 240a. Therefore, in this example, at least pressure plate region 201a includes a transparent material. According to some examples, the pressure plate 101 may include one or more anti-reflective layers. In some examples, one or more anti-reflective layers may reside on or near the pressure plate 101, for example, on or near the outer surface 208a.

[0073] According to this example, pressure plate region 201b resides near receiver stack portion 102a and pressure plate region 201c resides near receiver stack portion 102c. In this example, mirror layer 205a, matching layer 210a, and adhesive layer 215a reside between pressure plate region 201b and receiver stack portion 102a. Similarly, in this example, mirror layer 205b, matching layer 210b, and adhesive layer 215b reside between pressure plate region 201c and receiver stack portion 102b. Matching layers 210a and 210b may have acoustic impedance selected to reduce sound wave reflections caused by acoustic impedance contrast between one or more layers of receiver stack portions 102a and 102b adjacent to or near matching layers 210a and 210b. According to some examples, matching layers 210a and 210b may comprise polyethylene terephthalate (PET). In some examples, adhesive layers 215a and 215b may include pressure-sensitive adhesive (PSA) material.

[0074] exist Figure 2CIn the example shown, the device has a thickness T1 (along the z-axis) from the top of the pressure plate to the base of the backing layers 230a and 230b, and a thickness T2 from the top of the pressure plate to the base of the light source system circuitry. In some examples, T2 can range from 2 mm to 10 mm. According to some examples, T1 can range from 1 mm to 8 mm. The thickness of the backing layers 230a and 230b can range from 3 mm to 7 mm, such as 4.5 mm, 5.0 mm, 5.5 mm, etc. Therefore, an embodiment lacking one or more backing layers can be substantially thinner than an embodiment including one or more backing layers.

[0075] Figure 3A , Figure 3B and Figure 3C It shows Figure 2C The illustrated device presents different examples of how some components can be arranged. (See other appendices provided herein.) Figure 1 Sample, Figures 3A to 3C The number, type, and arrangement of the components shown are presented by way of example only. In these examples, device 100 is... Figure 1 Examples of the device 100 shown in Figure 2 are illustrated. In each of these examples, a top view of the device 100 is shown, which follows the... Figure 2C The z-axis of the coordinate system is shown. In these examples, the light guide component 240a is shown with a circular cross-section. However, in alternative examples, the light guide component 240a may have different cross-sectional shapes, such as a square cross-section, a rectangular cross-section, a hexagonal cross-section, etc.

[0076] In these examples, the outlines of receiver stack portion 102a and receiver stack portion 102b (and, in Figure 3B In the diagram, the outlines of receiver stack portions 102c to 102h are shown in dashed lines, indicating that these elements are located below the outer surface 208a of the pressure plate 101. According to these examples, receiver stack portion 102a resides near a first side of the light guide assembly 240a, and receiver stack portion 102b resides near a second side of the light guide assembly 240a. In these examples, receiver stack portion 102a resides near pressure plate region 102b on the first side of pressure plate region 102a (in this example, located below along the z-axis, further away from the observer), and receiver stack portion 102b resides near pressure plate region 102c, located on the second and opposite sides of pressure plate region 102a.

[0077] according to Figure 3A In the example shown, receiver stack sections 102a and 102b are discrete elements of a linear array of receiver stack sections having N receiver elements, where N is 2 in this example. In an alternative example, N may be greater than 2.

[0078] exist Figure 3B In the example shown, receiver stack portions 102a and 102b are discrete elements of a two-dimensional receiver array having M receiver elements, where M is 9 in this example. In an alternative example, M may be greater than or less than 9.

[0079] according to Figure 3C In the example shown, receiver stack portions 102a and 102b are portions of receiver stack ring 305a. In this example, receiver stack ring 305a is configured to surround light guide assembly 240a. According to this example, an annular region of pressure plate 301 near receiver stack ring 305a (in this example, located above along the z-axis, closer to the observer) is configured to surround pressure plate region 201a, which includes pressure plate region 201b and pressure plate region 201c.

[0080] Figure 3D The diagram shows the arrangement of additional components. Figure 2C Examples of components of the apparatus shown. As with other appendices provided herein. Figure 1 Sample, Figure 3D The number, type, and arrangement of the components shown are presented by way of example only. In these examples, device 100 is... Figure 1 An example of device 100 is shown. In this example, a top view of device 100 is shown, the view along... Figure 2C The z-axis of the coordinate system is shown. In this example, the light guide component 240a is shown with a circular cross-section. However, in an alternative example, the light guide component 240a may have a different cross-sectional shape.

[0081] In this example, receiver stack portions 102a and 102b are portions of receiver stack ring 305a. According to this example, receiver stack ring 305a is configured to surround light guide assembly 240a. In this example, receiver stack ring 305a includes receiver stack portions 102a and 102b, and pressure plate regions 201b and 201c. According to this example, receiver stack ring 305b is configured to surround receiver stack ring 305a. In this example, receiver stack ring 305b includes receiver stack portions 102c and 102d, and pressure plate regions 201j and 201k.

[0082] Figure 4 Example components of a device according to some alternative embodiments are shown. (See other appendices provided herein.) Figure 1 Sample, Figure 4 The number, type, and arrangement of the components shown are presented by way of example only. In this example, device 100 is Figure 1An example of device 100 is shown. According to this example, device 100 includes... Figure 2C All the elements shown are included. However, in this example, the light source system 104 also includes an optical coupling element 405. In this example, the optical coupling element 405 is configured to couple light from the light-emitting component 235a to the light guide component 240a. In some examples, the device 101 may be configured to implement one or more of the pulse group-based driving schemes disclosed herein for controlling the light source system 104.

[0083] exist Figure 4 In this design, the optical coupling element 405 is represented as having a width (along the x-axis) that decreases from a first side coupled to the light-emitting component 235a to a second side coupled to the light-guiding component 240a. In some examples, the optical coupling element 405 may comprise one or more materials that are the same as the material forming the light-guiding component 240a. According to some alternative examples, the optical coupling element 405 may be or may comprise a lens configured to focus light from the light-emitting component 235a into the light-guiding component 240a. In some examples, the optical coupling provided by the optical coupling element 405 may allow the light-guiding component 240a to have a relatively smaller width or diameter than the light-guiding component 240a of the device 100 without the optical coupling element 405.

[0084] Figure 5 Example components of a device according to some alternative embodiments are shown. (See other appendices provided herein.) Figure 1 Sample, Figure 5 The number, type, and arrangement of the components shown are presented by way of example only. In this example, device 100 is Figure 1 An example of device 100 is shown. According to this example, device 100 includes... Figure 2CAll elements shown are included. In some examples, device 101 may be configured to implement one or more of the pulse-group-based driving schemes disclosed herein for controlling light source system 104. However, in this example, light source system 104 includes light-emitting components 235a and 235b, and light source system circuitry 245a and 245b. In this example, light source system 104 includes L instances of light-emitting components, where L is an integer greater than 1. In this example, L equals 2. In other examples, L may be greater than 2. Therefore, in this example, the light source system includes at least a second light-emitting component and at least a second light-guiding component. In some examples, light source system 104 may include a first light-emitting component that emits light of a first wavelength and a second light-emitting component that emits light of a second wavelength. For example, light-emitting component 235a may be configured to emit light of a first wavelength, and light-emitting component 235b may be configured to emit light of a second wavelength. In some such examples, control system 106 may be configured to cause light-emitting component 235a to emit light at a first time and light-emitting component 235b to emit light at a second time. According to some examples, the light source system 104 may include three or more light-emitting components configured to emit three or more different wavelengths of light.

[0085] In this example, the light source system also includes a light guide component 240b configured to transmit light 250b from the light-emitting component 235b to the light guide component 250a. Therefore, in this example, the light source system includes at least a second light-emitting component and at least a second light guide component configured to transmit light from the second light-emitting component to at least a portion of the first light guide component. According to this example, the light guide component 240b is also configured to transmit light 250a from the light-emitting component 235a to the light guide component 250a. Although the light guide component 240b is shown as having a 90-degree bend, this is merely an example. In some specific implementations, the light guide component 240b may include a flexible material, such as one or more optical fibers, thereby allowing the light guide component 240b to form an arcuate shape and greater bending.

[0086] Figure 6 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 and summation beamforming process. As with other disclosed examples, Figure 6 The types, quantities, sizes, and arrangements of the elements shown and described herein, as well as the associated methods described herein, are merely examples.

[0087] In this example, a source is shown emitting ultrasonic waves 601, which are detected by active ultrasonic receiver elements 655a, 655b, and 655c of an ultrasonic receiver element array 602. The ultrasonic receiver element array 602 is part of a receiver system 102. In some examples, ultrasonic waves 601 may correspond to the photoacoustic response of a target object to light emitted by a light source system 104 of device 101. In this example, active ultrasonic receiver elements 655a, 655b, and 655c provide ultrasonic receiver signals 615a, 615b, and 615c, respectively, to a control system 106.

[0088] According to this example, the control system 106 includes a delay module 605 and a summing module 610. In this example, the delay module 605 is configured to determine whether a delay should be applied to each of the ultrasonic receiver signals 615a, 615b, and 615c, and if so, to determine what kind of delay should be applied. According to this example, the delay module 605 determines that a delay d0 of t2 should be applied to ultrasonic receiver signal 615a, a delay d1 of t1 should be applied to ultrasonic receiver signal 615b, and no delay should be applied to ultrasonic receiver signal 615c. Therefore, the delay module 605 applies the delay of t2 to ultrasonic receiver signal 615a, generating ultrasonic receiver signal 615a', and applies the delay of t1 to ultrasonic receiver signal 615b, generating ultrasonic receiver signal 615b'.

[0089] In some examples, the delay module 605 can determine what kind of delay, if any, should be applied to the ultrasonic receiver signal by performing correlation operations on the input ultrasonic receiver signal. For example, the delay module 605 can perform correlation operations on ultrasonic receiver signals 615a and 615c, and can determine that by applying a time shift of t2 to ultrasonic receiver signal 615a, ultrasonic receiver signal 615a will be strongly correlated with ultrasonic receiver signal 615c. Similarly, the delay module 605 can perform correlation operations on ultrasonic receiver signals 615b and 615c, and can determine that by applying a time shift of t1 to ultrasonic receiver signal 615b, ultrasonic receiver signal 615b will be strongly correlated with ultrasonic receiver signal 615c.

[0090] According to this example, the summing module 610 is configured to sum the ultrasonic receiver signals 615a', 615b', and 615c, generating a summed signal 620. It can be observed that the amplitude of the summed signal 620 is greater than the amplitude of any one of the ultrasonic receiver signals 615a, 615b, or 615c. In some instances, the signal-to-noise ratio (SNR) of the summed signal 620 may be greater than the SNR of any one of the ultrasonic receiver signals 615a, 615b, and 615c.

[0091] Figure 7 This is a flowchart illustrating examples of some of the disclosed operations. For example, Figure 7 The frame can be made of Figure 1 The apparatus 100 or similar apparatus shall be used to perform this. As with other methods disclosed herein, Figure 7 The methods outlined may include more or fewer boxes than those indicated. Furthermore, the boxes in the methods disclosed herein are not necessarily executed in the indicated order. In some instances, Figure 7 One or more boxes shown can be executed simultaneously.

[0092] In this example, box 705 relates to directing two or more groups of light pulses toward a target object during a total light transmission interval. Depending on the specific example, the target object could be a finger, wrist, etc. According to this example, each pulse group time interval within the total light transmission interval is separated from the continuous pulse group time interval by an interruption time interval. In this example, no light is transmitted toward the target object during the interruption time interval. However, in some alternative examples, the time interval between continuous pulse group time intervals can be a lower intensity time interval such that the intensity of the light transmitted toward the target object during this lower intensity time interval is much lower than the intensity of the light transmitted during the pulse group time interval, for example, one-tenth, one-hundredth, one-hundredth, one-hundred-thousandth, one-hundred-thousandth, one-hundred-thousandth, one-hundred-thousandth, etc. In some alternative examples, the time interval between consecutive pulse group intervals can be a lower PRF time interval such that the intensity of light transmitted toward the target object during this lower PRF time interval is the same as the intensity of light transmitted during the pulse group interval, but one-tenth, 1 / 100, 1 / 1000, 1 / 10000, etc. of the PRF. In some alternative examples, the time interval between consecutive pulse group intervals can be a time interval such that the light transmitted toward the target object during this time interval has a different intensity (e.g., a lower intensity) than the light transmitted during the pulse group interval, and is also transmitted with a different PRF (e.g., a lower PRF).

[0093] According to this example, block 710 relates to receiving an acoustic signal corresponding to the photoacoustic (PA) response of a target object to two or more pulse groups. In some examples, block 710 may relate to a receiver signal received by a control system corresponding to the sound waves caused by the PA response of a target object to two or more pulse groups.

[0094] In this example, box 715 relates to determining one or more heart rate waveforms based on acoustic signals. Alternatively or additionally, box 715 (or another aspect of method 700) may relate to determining one or more vascular features. In some examples, method 700 may relate to estimating one or more cardiac features based at least in part on one or more heart rate waveforms, one or more vascular features, or both. According to some examples, estimating the one or more cardiac features may involve estimating blood pressure.

[0095] In some examples, box 715 (or another aspect of method 700) may involve determining one or more cardiac features, such as blood pressure, based on receiver signals. In some such examples, method 700 may involve determining one or more cardiac features based on receiver signals without determining one or more heart rate waveforms, one or more vascular features, or an intermediate process involving both. In some examples, method 700 may involve (e.g., via...) Figure 1 The control system 106 implements a neural network that has been trained to estimate one or more cardiac features, potentially including blood pressure, using receiver signals as input. For example, the neural network may have been trained using blood pressure measurements from a blood pressure measuring device (such as cuff-based, catheter-based, or other blood pressure measuring devices) as “true values” for the neural network training process.

[0096] According to some examples, the exposure duration can be equal to a pulse group time interval plus an interruption time interval. In some examples, the average optical power density during the exposure duration is less than or equal to the MPE corresponding to the wavelength of the emitted light as specified in the American National Standards Institute's Laser Safety Use Standard (ANSI Z136.1) and the International Standard for Laser Product Safety (IEC 60825-1). In some such examples, the pulse group time interval can range from 0.0014 seconds to 7 seconds. According to some examples, the interruption time interval can range from 2 seconds to 5 seconds.

[0097] In some examples, the width of each optical pulse in the pulse group can range from 50 nanoseconds to 500 nanoseconds. According to some examples, the total light transmission time interval can range from 9 seconds to 25 seconds. In some examples, the PRF of the optical pulses in the pulse group can range from 0.5 kHz to 200 kHz. According to some examples, the peak amplitude of each optical pulse in the pulse group can range from 600 nm to 1064 nm in wavelength. In some examples, the average optical power density during the exposure duration can be 0.01 W / cm². 2 Up to 1.00 W / cm 2 Within the range.

[0098] According to some examples, one or more criteria used to control a light source system based on a pulse group-based approach may be at least partially based on one or more observed cardiac events. As mentioned elsewhere in this document, in some examples, PA techniques are used to estimate blood pressure, and for slow heart rate waveforms (HRW) with a period of up to 2 seconds, pulse group intervals of 2.5 seconds, 3.0 seconds, or more seconds may be required. However, this limitation may not exist for other use cases or for use cases involving HRWs with a period of less than 2 seconds. Some examples may involve measuring one or more HRW criteria according to any convenient method, such as HRW period, pulse rate, etc. Some such examples may involve measuring one or more HRW criteria using PAPG-based methods, photoplethysmography (PPG)-based methods, electrocardiogram-based methods, or other methods. Some such examples may involve determining the pulse group interval, interruption interval, or both based on the HRW period, pulse rate, etc. Some examples may involve determining the start time of the pulse group interval, interruption interval, or both based on the measured or expected start time of a cardiac event. In some examples, the average optical power density during the exposure duration is less than or equal to the MPE corresponding to the wavelength of the emitted light as specified in the American National Standards Institute's Laser Safety Use Standard (ANSI Z136.1) and the International Standard for Laser Product Safety (IEC 60825-1).

[0099] In some examples, one or more criteria for controlling the light source system according to a pulse group-based approach may be at least partially based on observed device motion. According to some such examples, device 100 may include a motion sensor system. The motion sensor system may, for example, include one or more accelerometers, one or more gyroscopes, or one or more other types of motion sensors. In some examples, when motion sensor system data indicates that device motion is at or above a device motion threshold, control system 106 may temporarily prevent light source system 104 from emitting light pulses.

[0100] Figure 8 It shows that it can be based on Figure 7 Examples of specific implementations of the method for extracting heart rate waveform (HRW) features. Figure 8The 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 intervals are indicated below the horizontal axis. During the systolic phase of the cardiac cycle, as the pulse travels along the artery through a specific location, the arterial wall expands according to the pulse waveform and the elastic properties of the arterial wall. Accompanying this expansion is a corresponding increase in blood volume at the specific location or region, and with the increase in blood volume, one or more properties in that region change accordingly. Conversely, during the diastolic phase of the cardiac cycle, blood pressure in the artery decreases and the arterial wall constricts. Accompanying this constriction is a corresponding decrease in blood volume at the specific location, and with the decrease in blood volume, one or more properties in that region change accordingly.

[0101] Figure 8 The illustrated HRW features relate to the width of the contraction and / or diastolic portions of the HRW curve at different "heights" indicated by the percentage of maximum amplitude. For example, the SW50 feature is the width of the contraction portion of the HRW curve at a "height" of 50% of maximum amplitude. In some embodiments, the HRW features used for blood pressure estimation may include some or all of the features of the SW10, SW25, SW33, SW50, SW66, SW75, DW10, DW25, DW33, DW50, DW66, and DW75 HRW features. In other embodiments, additional HRW features may be used for blood pressure estimation. In some instances, such additional HRW features may include the sum and ratio of SW and DW at one or more “heights,” such as (DW75 + SW75), DW75 / SW75, (DW66 + SW66), DW66 / SW66, (DW50 + SW50), DW50 / SW50, (DW33 + SW33), DW33 / SW33, (DW25 + SW25), DW25 / SW25, and / or (DW10 + SW10), DW10 / SW10. Other implementations may use other HRW features for blood pressure estimation. In some instances, such additional HRW features may include sums, differences, ratios, and / or other operations based on more than one “height,” such as (DW75 + SW75) / (DW50 + SW50), (DW50 + SW50) / (DW10 + SW10), etc.

[0102] Figure 9 An example of a device that can be used in a system for estimating blood pressure based at least in part on pulse conduction time (PTT) is shown. (See other appendices provided herein.) Figure 1The number, type, and arrangement of components are presented by way of example only. According to this example, system 900 includes at least two sensors. In this example, system 900 includes at least an electrocardiogram sensor 905 and a device 910 configured to be mounted on a finger of a person 901. In this example, device 910 is or includes means configured to perform at least some of the PAPG methods disclosed herein. For example, device 910 may be or may include... Figure 1 The device 100 or similar device.

[0103] As mentioned in Figure 920, PAT comprises two components: the pre-ejection phase (PEP, the time required to convert the electrical signal into mechanical pumping force and isovolumetric contraction to open the aortic valve) and PTT. The start time of PAT can be estimated based on the QRS complex (the electrical signal characteristics of ventricular electrical stimulation). As shown in Figure 920, in this example, the start of the pulse arrival time (PAT) can be calculated based on the R-wave peak measured by the ECG sensor 905, and the end of PAT can be detected via analysis of the signal provided by the device 910. In this example, it is assumed that the end of PAT corresponds to the intersection between the tangent of the local minimum detected by the device 910 and the tangent of the maximum slope / first derivative of the sensor signal after the minimum time.

[0104] There are many known blood pressure estimation algorithms based on PTT and / or PAT, some of which are outlined in Table 1 and described in the corresponding text on pages 5–10 of Sharma, M. et al., in “Cuffless and Continuous Blood Pressure Monitoring: A Methodological Review” (“Sharma”), published by the Multidisciplinary Digital Publishing Institute (MDPI) in Technology, Volume 5, Issue 21, 2017, both of which are incorporated herein by reference.

[0105] 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 mentioned 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.

[0106] Other embodiments of system 900 may not include electrocardiogram sensor 905. In some such embodiments, device 915, configured to be mounted on the wrist of person 901, may be or may include means configured to perform at least some of the PAPG methods disclosed herein. For example, device 915 may be or may include device 200 of FIG2 or similar means. According to some such examples, device 915 may include a light source system and two or more ultrasound receivers. Reference is made below. Figure 11A Describe an example. In some examples, device 915 may include an array of ultrasonic receivers.

[0107] In some specific embodiments of system 900 excluding electrocardiogram sensor 905, device 910 may include a light source system and two or more ultrasound receivers. See below for reference. Figure 11B Describe an example.

[0108] Figure 10 A schematic cross-sectional side view showing a portion of the artery 1000 through which the pulse 1002 propagates. Figure 10 The boxed arrows indicate the direction of blood flow and pulse propagation. As illustrated, the propagating pulse 1002 causes strain in the arterial wall 1004, which manifests as an expansion of the arterial wall's diameter (and therefore its cross-section), a phenomenon referred to as "dilation." The actual spatial length of the 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 considerably between different subjects, and for a given subject, it can depend on various factors that vary 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.

[0109] As described above, certain specific implementations involve devices, systems, and methods for estimating blood pressure or other cardiovascular characteristics based on estimations of arterial dilation waveforms. Unless otherwise indicated, the terms “estimate,” “measure,” “calculate,” “infer,” “derive,” “evaluate,” “determine,” and “monitor” are used interchangeably herein where appropriate. Similarly, derivatives of the roots of these terms are used interchangeably where appropriate; for example, the terms “estimate,” “measure,” “calculate,” “infer,” and “determine” are used interchangeably herein. In some implementations, the pulse wave velocity (PWV) of the propagating pulse can be estimated by measuring its pulse conduction 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. Assume a physical distance between the first physical location and the second physical location. It is deterministic; PWV can be estimated as the spatial distance of the pulse travels. Divide by the distance the pulse travels through physical space The quotient of the time taken (PTT). Typically, a first sensor located at a first physical location is used to determine the start time of the pulse's arrival or propagation through the first physical location (also referred to herein as the "first time location"). A second sensor at a second physical location is used to determine the end time of the pulse's arrival or propagation through the second physical location and continuing through the remainder of the arterial branch (also referred to herein as the "second time location"). In such examples, PTT represents the time distance (or time difference) between the first time location and the second time location (start time and end time).

[0110] 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 blood density. More specifically, PWV typically depends on several factors, including blood density. Arterial wall stiffness (or conversely, elasticity), arterial diameter, arterial wall thickness, and blood pressure. Because both arterial wall elasticity and baseline resting diameter (e.g., the diameter at the end of ventricular diastole) vary significantly throughout the arterial system, the PWV estimate obtained from a PTT measurement is essentially an average (the total path length between the two locations where the measurement was performed). (Take the average from above).

[0111] In conventional methods for obtaining pulse wave velocity (PWV), electrocardiogram (ECG) sensors (which detect electrical signals from the heart) have been used to determine 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 determine the end time of the pulse. As those skilled in the art will understand, there are numerous arterial discontinuities, branches, and variations along the entire path from the heart to the finger. Variations in PWV can reach or exceed one order of magnitude along various extensions of the entire path from the heart to the finger. Therefore, PWV estimations based on such a long path length are unreliable.

[0112] 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 specifically, "sensor data"), obtained by each of a first arterial dilation sensor 1006 and a second arterial dilation sensor 1008, respectively, near a first physical location and a second physical location of the artery of interest. In some specific embodiments, the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 are advantageously positioned near the first physical location and the second physical location, and between the first physical location and the second physical location, arterial properties of the artery of interest, such as wall elasticity and diameter, can be considered or assumed to be relatively constant. In this way, PWV calculated based on PTT estimation is more representative of the actual PWV along a specific segment of the artery. Furthermore, blood pressure estimated based on PWV... This better represents true blood pressure. In some specific implementations, the separation distance between the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008... The magnitude of the pulse (and therefore the distance between the first and second locations along the artery) can range from about 1 centimeter (cm) to tens of centimeters, long enough to distinguish the arrival of the pulse at the first physical location from the arrival of the pulse at the second physical location, but close enough to ensure arterial consistency. In some specific embodiments, the distance between the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 is... The distance can be from about 1 cm to about 30 cm, and in some embodiments, it is less than or equal to about 20 cm, in some embodiments, it is less than or equal to about 10 cm, and in some specific embodiments, it is less than or equal to about 5 cm. In some other embodiments, the distance between the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 is... 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 meters per second (m / s). Using a first arterial dilation sensor 1006 and a second arterial dilation sensor 1008 to separate a distance of about 5 cm, and assuming a PWV of about 15 m / s, this means a non-recumbent PWV monitoring device with a PWV of about 3.3 milliseconds (ms).

[0113] The distance between the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 The values ​​of the quantities can be pre-programmed into the memory within the monitoring device of the combined sensors (e.g., as in the reference above). Figure 1 The memory of the described control system 106, or a memory configured to communicate therewith. As those skilled in the art will understand, in such a specific implementation, the spatial length of the pulse... L It can be greater than the distance from the first arterial dilation sensor 1006 to the second arterial dilation sensor 1008. Therefore, although Figure 10 The illustrated pulse 1002 is shown to have a spatial length equivalent to the distance between the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008. L However, 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 1006 and the second arterial dilation sensor 1008. Spatial length L .

[0114] Sensing architecture and topology

[0115] In some embodiments of the non-ambulatory monitoring device disclosed herein, the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 are both sensors of the same sensor type. In some such embodiments, the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 are identical sensors. In such embodiments, each of the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 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 1006 and the second arterial dilation sensor 1008 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... Figure 1Examples of a light source system 104 and a receiver system 302. In some embodiments, each of the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 is configured for ultrasonic sensing via the transmission of an ultrasonic signal and the reception of a corresponding reflection. In some alternative embodiments, each of the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 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 1006 and the second arterial dilation sensor 1008 is broadly designed to capture and provide arterial dilation data indicating an arterial dilation signal generated by the propagation of a pulse through a portion of the artery near the location of the respective 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 the ultrasonic signal or impedance signal sensed by the respective sensor.

[0116] As described above, during the systolic phase of the cardiac cycle, as the pulse travels along the artery through a specific location, the arterial wall expands according to the pulse waveform and the elastic properties of the arterial wall. This expansion is accompanied by a corresponding increase in blood volume at that specific location or region, and with this increase in blood volume, one or more properties in that region change accordingly. Conversely, during the diastolic phase of the cardiac cycle, blood pressure in the artery decreases and the arterial wall constricts. This constriction is accompanied by a corresponding decrease in blood volume at that specific location, and with this decrease in blood volume, one or more properties in that region change accordingly.

[0117] 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 particular location, the corresponding increase in blood volume results in an increase in conductivity (and more specifically, an increase in admittance, or equivalently, a decrease in impedance) at that location. Conversely, during the diastolic phase of the cardiac cycle, the corresponding decrease in blood volume results in an increase in resistivity (and more specifically, an increase in impedance, or equivalently, a decrease in admittance) at that location.

[0118] 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, bioimpedance sensors are operable to monitor blood pressure, heart rate, or other cardiovascular characteristics, with the detected voltage response signal amplitude and phase modulated by the time-varying impedance (or conversely, admittance) of the underlying artery, which fluctuates in sync with the user's heartbeat, as described above. 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.

[0119] In some examples incorporating ultrasound sensors, the measurement of arterial dilation may involve, for example, directing ultrasound waves toward the artery into the limb via one or more ultrasound transducers. Such ultrasound sensors are also configured to receive reflected waves, at least in part based on the directed 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.

[0120] In some specific implementations, regardless of the type of sensor used for the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008, both the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 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 a subject, both the first arterial dilation sensor 1006 and the second arterial dilation sensor 1008 are in contact with or near the user's skin at a first position and a second position, respectively, with a separation distance of [missing information]. Furthermore, in some embodiments, it may be assumed that the various arterial properties along the arterial extension are relatively constant. In various embodiments, the housing of the non-ambulatory monitoring device is a wearable housing or incorporated into or integrated with such a wearable housing. In some specific embodiments, the wearable housing includes a physical coupling mechanism (or connection thereto) for removable, 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, etc. Moreover, the housing can be made of any of a variety of suitable materials, including but not limited to plastics, metals, glass, rubber, and ceramics, or combinations of these or other materials. In certain embodiments, the housing and coupling mechanism enable fully ambulatory 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 of interest to obtain a better picture of such characteristics over extended periods, and specifically, to obtain a better picture of the user's health.

[0121] In some implementations, non-bedridden monitoring devices can be positioned around the user's wrist using strips or bands, similar to watches or fitness / activity trackers. Figure 11A An example of a non-recumbent monitoring device 1100 designed to be worn on the wrist is shown according to some specific embodiments. In the illustrated example, the monitoring device 1100 includes a housing 1102 integrally formed, coupled, or otherwise integrated with a wristband 1104. In some instances, a first arterial dilation sensor 1106 and a second arterial dilation sensor 1108 may each include the components referenced above. Figure 1 The described receiver system 102 is an example of a light source system 104. In this example, the non-recumbent monitoring device 1100 is coupled around the wrist, such that a first arterial dilation sensor 1106 and a second arterial dilation sensor 1108 within the housing 1102 are each positioned along a segment of the radial artery 1110 (it should be noted that the sensors are typically concealed when viewed from the exterior or outer surface of the housing facing the subject, while the monitoring device is coupled to the subject but exposed on the inner surface of the housing so that the sensors can obtain measurements from the underlying artery through the subject's skin). Also as shown, the first arterial dilation sensor 1106 and the second arterial dilation sensor 1108 are separated by a fixed distance. In some other specific implementations, the non-recumbent monitoring device 1100 may be similarly designed or adapted to use strips or bands around the forearm, upper arm, ankle, lower leg, thigh, or fingers (all of which are referred to below as "limbs") for positioning.

[0122] Figure 11B An example of a non-recumbent monitoring device 1100 designed to be worn on a finger is shown according to some specific embodiments. In some instances, a first arterial dilation sensor 1106 and a second arterial dilation sensor 1108 may each include the components referenced above. Figure 1 The described receiver system 102 is an example and part of the light source system 104.

[0123] 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 1106 and the second arterial dilation sensor 1108, 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).

[0124] Figure 11C An example of a non-reliable monitoring device 1100 designed to reside on an earplug is shown according to some specific embodiments. According to this example, the non-reliable monitoring device 1100 is coupled to the housing of an earplug 1120. In some instances, a first arterial dilation sensor 1106 and a second arterial dilation sensor 1108 may each include the elements referenced above. Figure 1 The described receiver system 102 is an example and part of the light source system 104.

[0125] Specific implementation examples are described in the following numbered clauses: 1. A method comprising: directing two or more groups of light pulses toward a target object, the target object being part of a human or animal body, during a total light transmission time interval, wherein each pulse group time interval within the total light transmission time interval is separated from the continuous pulse group time interval by an interruption time interval during which no light is transmitted toward the target object; receiving an acoustic signal corresponding to a photoacoustic (PA) response of the target object to the two or more pulse groups; and determining one or more heart rate waveforms of the human or animal body based on the acoustic signal.

[0126] 2. The method according to Clause 1, the method further comprising estimating one or more cardiac features based at least in part on the one or more heart rate waveforms.

[0127] 3. The method according to Clause 2, wherein estimating the one or more cardiac characteristics involves estimating blood pressure.

[0128] 4. The method according to any one of clauses 1 to 3, wherein the time interval between each pulse group is in the range of 0.0014 seconds to 7 seconds.

[0129] 5. The method according to any one of Clauses 1 to 4, wherein each interruption time interval is in the range of 2 to 5 seconds.

[0130] 6. The method according to any one of Clauses 1 to 5, wherein the total optical transmission time interval is in the range of 5 seconds to 25 seconds.

[0131] 7. The method according to any one of clauses 1 to 6, wherein the width of each optical pulse in the pulse group is in the range of 50 nanoseconds to 500 nanoseconds.

[0132] 8. The method according to any one of clauses 1 to 7, wherein the pulse repetition frequency (PRF) of the optical pulses in the pulse group is in the range of 0.5 kHz to 200 kHz.

[0133] 9. The method according to any one of clauses 1 to 8, wherein the peak amplitude of each optical pulse in the pulse group is in the wavelength range of 600 nanometers to 1064 nanometers.

[0134] 10. The method according to any one of clauses 1 to 9, wherein the exposure duration is equal to a pulse group time interval plus an interruption time interval.

[0135] 11. The method according to Clause 10, wherein the average optical power density during the exposure duration is in the range of 0.01 W / cm² to 1.00 W / cm².

[0136] 12. The method according to Clause 10 or Clause 11, wherein the average optical power density during the exposure duration is less than the maximum permissible exposure (MPE) corresponding to the wavelength of the emitted light as published by the American National Standards Institute's Laser Safety Use Standards.

[0137] 13. The method according to any one of clauses 1 to 12, wherein the interrupt time interval is greater than the pulse group time interval.

[0138] 14. The method according to Clause 13, wherein the exposure duration is equal to a pulse group time interval plus an interruption time interval, and wherein the ratio of the interruption time interval to the pulse group time interval causes the average optical power density to be below a threshold during the exposure duration.

[0139] 15. One or more non-transitory computer-readable media having instructions stored thereon for performing a method comprising: directing two or more groups of light pulses toward a target object, the target object being part of a human or animal body, during a total light transmission time interval, wherein each pulse group time interval within the total light transmission time interval is separated from the continuous pulse group time interval by an interruption time interval during which no light is transmitted toward the target object; receiving an acoustic signal corresponding to a photoacoustic (PA) response of the target object to the two or more pulse groups; and determining one or more heart rate waveforms of the human or animal body based on the acoustic signal.

[0140] 16. The method further comprises estimating one or more cardiac features based at least in part on the one or more heart rate waveforms, according to one or more non-transitory computer-readable media as described in Clause 15.

[0141] 17. An apparatus comprising: a light source system; a receiver system; and a control system configured to electrically communicate with the light source system and the receiver system, the control system being configured to: control the light source system to direct two or more groups of light pulses toward a target object, the target object being part of a human or animal body, during a total light transmission time interval, wherein each pulse group time interval within the total light transmission time interval is separated from the continuous pulse group time interval by an interruption time interval during which no light is transmitted toward the target object; receive, via the receiver system, a receiver signal corresponding to an acoustic wave caused by a photoacoustic (PA) response of the target object to the two or more pulse groups; and determine one or more heart rate waveforms of the human or animal body based on the receiver signal.

[0142] 18. The apparatus of claim 17, wherein the control system is further configured to estimate one or more cardiac features at least in part based on the one or more heart rate waveforms, wherein estimating the one or more cardiac features involves estimating blood pressure.

[0143] 19. The apparatus according to any one of clauses 16 to 18, wherein the time interval between each pulse group is in the range of 0.0014 seconds to 7 seconds.

[0144] 20. The apparatus according to any one of clauses 16 to 19, wherein each interruption time interval is in the range of 2 to 5 seconds.

[0145] 21. The apparatus according to any one of Clauses 16 to 20, wherein the total optical transmission time interval is in the range of 9 seconds to 25 seconds.

[0146] 22. The apparatus according to any one of clauses 16 to 21, wherein the width of each optical pulse in the pulse group is in the range of 50 nanoseconds to 500 nanoseconds.

[0147] 23. The apparatus according to any one of clauses 16 to 22, wherein the pulse repetition frequency (PRF) of the optical pulses in the pulse group is in the range of 0.5 kHz to 200 kHz.

[0148] 24. The apparatus according to any one of clauses 16 to 23, wherein the peak amplitude of each optical pulse in the pulse group is in the wavelength range of 600 nanometers to 1064 nanometers.

[0149] 25. The apparatus according to any one of clauses 16 to 24, wherein the exposure duration is equal to a pulse group time interval plus an interruption time interval.

[0150] 26. The apparatus according to Clause 25, wherein the average optical power density during the exposure duration is in the range of 0.01 W / cm² to 1.00 W / cm².

[0151] 27. The apparatus according to Clause 25 or Clause 26, wherein the average optical power density during the exposure duration is less than the maximum permissible exposure (MPE) corresponding to the wavelength of the emitted light as published by the American National Standards Institute's Laser Safety Use Standards.

[0152] 28. An apparatus comprising: a light source system; a receiver system; and a control unit for: controlling the light source system to direct two or more groups of light pulses toward a target object, the target object being part of a human or animal body, during a total light transmission time interval, wherein each pulse group time interval within the total light transmission time interval is separated from the continuous pulse group time interval by an interruption time interval during which no light is transmitted toward the target object; receiving, via the receiver system, an acoustic signal corresponding to a photoacoustic (PA) response of the target object to the two or more pulse groups; and determining one or more heart rate waveforms of the human or animal body based on the acoustic signal.

[0153] 29. The apparatus according to Clause 28, wherein the control component includes a component for estimating one or more cardiac characteristics based at least in part on the one or more heart rate waveforms.

[0154] 30. The device according to Clause 29, wherein estimating the one or more cardiac characteristics involves estimating blood pressure.

[0155] 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.

[0156] 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 various exemplary components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0157] Hardware and data processing means for implementing the various exemplary logic, 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 components, 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.

[0158] 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.

[0159] 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. Additionally, 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.

[0160] 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.

[0161] 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.

[0162] Similarly, although operations are depicted in a specific order in the figures, 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.

[0163] 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.

[0164] 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 are to be accorded the widest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0165] Additionally, some features described in this specification within the context of individual embodiments may also be implemented in combination within a single embodiment. Conversely, individual features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, 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.

[0166] Similarly, although operations are depicted in a specific order in the figures, 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 figures 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 such separation in all embodiments. Therefore, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result.

Claims

1. A method, the method comprising: During the total light transmission interval, two or more groups of light pulses are directed toward a target object, which is part of a human or animal body, and the time interval of each group of pulses within the total light transmission interval is separated from the time interval of consecutive groups of pulses by an interruption interval during which no light is transmitted toward the target object; Receive acoustic signals corresponding to the photoacoustic (PA) response of the target object to the two or more pulse groups; as well as One or more heart rate waveforms of the human body or animal body are determined based on the acoustic signals.

2. The method of claim 1, further comprising estimating one or more cardiac features at least in part based on the one or more heart rate waveforms.

3. The method of claim 2, wherein estimating the one or more cardiac features involves estimating blood pressure.

4. The method of claim 1, wherein the time interval between each pulse group is in the range of 0.0014 seconds to 7 seconds.

5. The method of claim 1, wherein each interruption time interval is in the range of 2 to 5 seconds.

6. The method according to claim 1, wherein the total optical transmission time interval is in the range of 5 seconds to 25 seconds.

7. The method of claim 1, wherein the width of each optical pulse in the pulse group is in the range of 50 nanoseconds to 500 nanoseconds.

8. The method of claim 1, wherein the pulse repetition frequency (PRF) of the optical pulses in the pulse group is in the range of 0.5 kHz to 200 kHz.

9. The method of claim 1, wherein the peak amplitude of each optical pulse in the pulse group is in the wavelength range of 600 nm to 1064 nm.

10. The method of claim 1, wherein the exposure duration is equal to a pulse group time interval plus an interruption time interval.

11. The method of claim 10, wherein the average optical power density during the exposure duration is 0.01 W / cm². 2 Up to 1.00 W / cm 2 Within the range.

12. The method of claim 10, wherein the average optical power density during the exposure duration is less than the maximum permissible exposure (MPE) corresponding to the wavelength of the emitted light, as published by the American National Standards Institute's Laser Safety Use Standards.

13. The method according to claim 1, wherein the interrupt time interval is greater than the pulse group time interval.

14. The method of claim 13, wherein the exposure duration is equal to a pulse group time interval plus an interrupt time interval, and wherein the ratio of the interrupt time interval to the pulse group time interval causes the average optical power density to be below a threshold during the exposure duration.

15. One or more non-transitory computer-readable media, the one or more non-transitory computer-readable media having instructions stored thereon for performing a method, the method comprising: During the total light transmission interval, two or more groups of light pulses are directed toward a target object, which is part of a human or animal body, and the time interval of each group of pulses within the total light transmission interval is separated from the time interval of consecutive groups of pulses by an interruption interval during which no light is transmitted toward the target object; Receive acoustic signals corresponding to the photoacoustic (PA) response of the target object to the two or more pulse groups; as well as One or more heart rate waveforms of the human body or animal body are determined based on the acoustic signals.

16. The method of one or more non-transitory computer-readable media according to claim 15, further comprising estimating one or more cardiac features at least in part based on the one or more heart rate waveforms.

17. An apparatus comprising: Light source system; Receiver system; and A control system configured to electrically communicate with the light source system and the receiver system, the control system being configured to: The light source system is controlled to direct two or more groups of light pulses toward a target object, which is part of a human or animal body, during a total light transmission time interval, wherein the time interval of each group of pulses within the total light transmission time interval is separated from the time interval of consecutive groups of pulses by an interruption time interval during which no light is transmitted toward the target object; The receiver system receives receiver signals corresponding to the acoustic waves caused by the photoacoustic (PA) response of the target object to the two or more pulse groups; as well as One or more heart rate waveforms of the human body or animal body are determined based on the receiver signal.

18. The apparatus of claim 17, wherein the control system is further configured to estimate one or more cardiac features at least in part based on the one or more heart rate waveforms, wherein estimating the one or more cardiac features involves estimating blood pressure.

19. The apparatus of claim 16, wherein the time interval between each pulse group is in the range of 0.0014 seconds to 7 seconds.

20. The apparatus of claim 16, wherein each interruption time interval is in the range of 2 seconds to 5 seconds.

21. The apparatus of claim 16, wherein the total optical transmission time interval is in the range of 9 seconds to 25 seconds.

22. The apparatus of claim 16, wherein the width of each optical pulse in the pulse group is in the range of 50 nanoseconds to 500 nanoseconds.

23. The apparatus of claim 16, wherein the pulse repetition frequency (PRF) of the optical pulses in the pulse group is in the range of 0.5 kHz to 200 kHz.

24. The apparatus of claim 16, wherein the peak amplitude of each optical pulse in the pulse group is in the wavelength range of 600 nm to 1064 nm.

25. The apparatus of claim 16, wherein the exposure duration is equal to a pulse group time interval plus an interruption time interval.

26. The apparatus of claim 25, wherein the average optical power density during the exposure duration is 0.01 W / cm². 2 Up to 1.00 W / cm 2 Within the range.

27. The apparatus of claim 25, wherein the average optical power density during the exposure duration is less than the maximum permissible exposure (MPE) corresponding to the wavelength of the emitted light, as published by the American National Standards Institute's Laser Safety Use Standards.

28. An apparatus comprising: Light source system; Receiver system; and Control unit, the control unit being used for: The light source system is controlled to direct two or more groups of light pulses toward a target object, which is part of a human or animal body, during a total light transmission time interval, wherein the time interval of each group of pulses within the total light transmission time interval is separated from the time interval of consecutive groups of pulses by an interruption time interval during which no light is transmitted toward the target object; The receiver system receives acoustic signals corresponding to the photoacoustic (PA) response of the target object to the two or more pulse groups; as well as One or more heart rate waveforms of the human body or animal body are determined based on the acoustic signals.

29. The apparatus of claim 28, wherein the control component includes a component for estimating one or more cardiac characteristics based at least in part on the one or more heart rate waveforms.

30. The apparatus of claim 29, wherein estimating the one or more cardiac characteristics involves estimating blood pressure.

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