Photoacoustic apparatus and system

Abstract

Photoacoustic devices and systems are disclosed. A user device can include a light source system comprising one or more light sources; a receiver system comprising one or more receivers configured to detect acoustic signals generated based on light signals from the one or more light sources; an interface layer contactable by a user, the interface layer comprising a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic property corresponding to an acoustic property of the user and a second acoustic property corresponding to an acoustic property of the one or more receivers; and a waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the light signals from the one or more light sources to at least the portion of the user.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Indian Provisional Application No. 202341062837 entitled “PHOTOACOUSTIC DEVICES AND SYSTEMS”, filed on 19 September 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates in general to photoacoustic devices and systems.

[0004] Related technical descriptions

[0005] A variety of sensing technologies and algorithms are being applied to devices to enable a wide range of biometric and biomedical applications, including health and wellness monitoring. This trend stems in part from the limitations of traditional measurement devices in terms of continuous, non-invasive, and dynamic monitoring. Some of these devices are photoacoustic devices, or incorporate photoacoustic elements. While some previously deployed photoacoustic devices and systems have provided acceptable results, improvements to photoacoustic devices and systems are still expected. Summary of the Invention

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

[0007] In one aspect of this disclosure, a user equipment is disclosed. In some embodiments, the user equipment may include: a light source system comprising one or more light sources; a receiver system comprising one or more receivers configured to detect an acoustic signal generated by a target object based on an optical signal from the one or more light sources; an interface layer accessible to a user, the interface layer comprising a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; and a waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the at least a portion of the user.

[0008] In another aspect of this disclosure, a method for monitoring a user's physiological parameters using a photoacoustic device is disclosed. In some embodiments, the method may include: transmitting an optical signal via one or more waveguides from a light source system of the photoacoustic device toward a portion of a receiver system of the photoacoustic device near a user, the receiver system being disposed away from the light source system and not in direct contact with the light source system, the photoacoustic device comprising: the light source system including one or more light sources; the receiver system including one or more receivers configured to detect an acoustic signal generated by a target object based on an optical signal from the one or more light sources; an interface layer accessible to the user, the interface layer comprising a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; and a waveguide system including one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the at least a portion of the user; receiving information from the receiver system regarding the acoustic signal detected by the one or more receivers; and determining the user's physiological parameters based on the information regarding the acoustic signal.

[0009] In another aspect of this disclosure, an apparatus is disclosed. In some embodiments, the apparatus may include: a light source component for transmitting light, the light source component including one or more light sources; a receiver component for detecting an acoustic signal generated by a target object based on the light signal from the light source component, the receiver component including one or more receiver elements; an interface component accessible to a user, the interface component comprising a flexible material configured to conform to at least a portion of the user and adjacent to the receiver component, the interface component having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the receiver component; and a waveguide component for transmitting the light signal from the one or more light sources to the at least a portion of the user, the waveguide component including one or more waveguides at least partially embedded in the interface layer.

[0010] In another aspect of the invention, a non-transitory computer-readable device is disclosed. In some embodiments, the non-transitory computer-readable device may include a storage medium comprising a plurality of instructions configured to, when executed by a control system, cause a photoacoustic device to: transmit an optical signal via one or more waveguides from a light source system of the photoacoustic device toward a portion of a receiver system of the photoacoustic device near a user, the receiver system being positioned away from the light source system and not in direct contact with it; the photoacoustic device comprising: the light source system including one or more light sources; the receiver system including one or more receivers configured to detect an acoustic signal generated by a target object based on the optical signal from the one or more light sources; and an interface layer. The interface layer, accessible to a user, comprises a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; and a waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the at least a portion of the user; receiving information from the receiver system regarding the acoustic signal detected by the one or more receivers; and determining the user's physiological parameters based on the information regarding the acoustic signal.

[0011] Details of one or more specific embodiments of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. Note that the relative dimensions in the following drawings may not be drawn to scale. Attached Figure Description

[0012] Figure 1 An example of a blood pressure monitoring device based on photoacoustic volume plethysmography (which may be referred to herein as PAPG) is shown.

[0013] Figure 2 This is a block diagram illustrating example components of a device according to some disclosed specific implementations.

[0014] Figures 3A to 3C This illustrates some of the specific implementations disclosed. Figure 2 An example of a hierarchical portion or hierarchical layer of the interface of a device.

[0015] Figures 4A to 4C An example configuration of the optical waveguide of the interface, receiver element of the receiver system, and photoacoustic device according to some of the disclosed specific implementations is shown.

[0016] Figures 4D to 4FAn example configuration of multiple optical waveguides for an interface, receiver system receiver element, and photoacoustic device according to some disclosed specific implementations is shown.

[0017] Figure 5A and Figure 5B Example implementations of receiver elements of receiver systems according to some disclosed specific embodiments are shown.

[0018] Figure 6 An example configuration of a photoacoustic device according to some of the disclosed specific implementations is shown.

[0019] Figure 7 It is a flowchart based on some publicly disclosed specific implementations of methods for monitoring users' physiological parameters.

[0020] The same reference numerals and names in the various figures indicate the same elements. Detailed Implementation

[0021] The following description relates to certain specific embodiments 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 or the monitoring of other physiological parameters. However, some specific embodiments are also applicable to other types of biosensing applications and 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 supporting multimedia internet, mobile TV receivers, wireless devices, smartphones, smart cards, wearable devices (such as wristbands, armbands, wrist straps, rings, headbands, patches, chest straps, anklets, etc.), Bluetooth devices, etc. ®Devices, personal data assistants (PDAs), wireless email receivers, handheld or portable computers, netbooks, laptops, smartbooks, tablets, printers, copiers, scanners, fax machines, GPS receivers / navigators, cameras, digital media players, game consoles, wristwatches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), mobile health devices, computer monitors, automotive displays (including odometer and speedometer displays, etc.), cockpit controls and / or displays, camera view displays (such as rearview camera displays in vehicles), building structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washing machines, dryers, washer / dryer units, parking meters, car doors, Internet of Things (IoT) devices, etc. Therefore, this teaching is not intended to be limited to the specific embodiments depicted and described with reference to the accompanying drawings; rather, as will be apparent to those skilled in the art, this teaching has broad applicability.

[0022] Non-invasive health monitoring devices, such as those based on photoacoustic plethysmography (PAPG), offer a variety of potential advantages over more invasive devices, such as cuff-based or catheter-based blood pressure measurement devices. However, designing a satisfactory, compact, wearable PAPG-based device has proven challenging. Some wearable PAPG-based devices may include a platform for transmitting both light and acoustic signals. The platform should be optically transparent and ideally have an acoustic impedance closely matched to that of human skin. The requirement for an optically transparent platform material can result in suboptimal acoustic transmission characteristics. The use of a platform may also limit the number of independent light sources available for data collection due to space constraints. Wearable PAPG-based devices with a single or several light source locations may not be optimal, at least in part, because alignment with a target, such as an artery, can be challenging.

[0023] Some of the disclosed devices described herein include interfaces, light source systems, and ultrasonic receiver systems. Some such devices may not include a rigid platform. According to some embodiments, the interface may be a physically flexible interface made of one or more suitable materials having one or more desired properties, such as acoustic properties like acoustic impedance, or the softness of the material. In some embodiments, the interface may be a flexible interface that can contact a target object that can approach or contact the interface. There may be significant differences between such an interface and a platform. In some embodiments, the light source system may be configured to guide light using one or more optical waveguides (e.g., optical fibers), which are configured to guide light toward a target object. According to some embodiments, the interface may have an outer surface or a layer on that outer surface whose acoustic impedance is configured to approximate that of human skin. This outer surface may have contact portions that can be contacted by a user or a part of the user's body (e.g., fingers, wrist). In some examples, the optical waveguide may be embedded in one or more acoustic matching layers configured to bring light transmitted by the optical waveguide very close to tissue. The outer surface and / or other portions of the interface may be malleable, flexible, or otherwise at least partially conformable to the shape and contour of a user's body part. In some embodiments, the interface may have a surface adjacent to the ultrasound receiver system, or a layer on that surface adjacent to the ultrasound receiver system, whose acoustic impedance is configured to approximate the acoustic impedance of the ultrasound receiver system.

[0024] 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 devices with PAPG capability that utilize flexible materials, allowing these devices to be worn to acquire and evaluate measurements, such as cardiac measurements, via photoacoustic components. According to some examples, optical waveguides can be configured to provide light at various lateral distances along a target, such as an artery. In some such examples, an array of receiver elements can be configured to receive ultrasound waves generated by the photoacoustic response of light from the optical waveguide within human tissue. Such embodiments allow for the collection of multi-point information about blood pressure, pulse wave velocity, depth discrimination, heart rate, etc. An acoustic impedance matching layer mitigates unwanted reflections of sound waves, thereby reducing noise. Some disclosed devices include an impedance matching layer with relatively low acoustic attenuation compared to commonly used platform materials, which improves the signal-to-noise ratio (SNR).

[0025] Figure 1 An example of a blood pressure monitoring device based on photoacoustic volume plethysmography (which may be referred to herein as PAPG) is shown. Figure 1The same example of arteries, veins, arterioles, venules, and capillaries inside a body part (in this example, finger 115) is shown. In some examples, Figure 1 The light source shown can be coupled to a light source system (not shown) located away from a body part (e.g., finger 115). In some embodiments, the light source can be an opening in an optical fiber or other waveguide. Such an opening can also be connected to an opening in an interface that can contact a body part. In some embodiments, the light source system may include one or more LEDs, one or more laser diodes, etc. In this example, the light source has emitted light (in some examples, green, red, and / or near-infrared (NIR) light) that has penetrated the tissue of the finger 115 in the irradiated area.

[0026] exist Figure 1 In the example shown, the blood vessels (and components of the blood itself) are heated by incident light from a light source and are emitting sound waves 102. In this example, the emitted sound waves 102 include ultrasound. According to this specific embodiment, the sound wave emission 102 is detected by an ultrasound receiver, which in this example is a piezoelectric receiver. The photoacoustic emission 102 from the irradiated tissue detected by the piezoelectric receiver can be used to detect volume changes in the blood in the irradiated area of ​​the finger 115, which correspond to physiological data within the irradiated tissue of the finger 115, such as heart rate waveforms. Although some tissue areas are shown as irradiated, they are offset from the tissue areas shown as generating photoacoustic emission 102, but this is merely for illustrative purposes. It should be understood that the irradiated tissue will actually be those tissues that generate photoacoustic emission. Furthermore, it should be understood that the maximum level of photoacoustic emission will generally be generated along the same axis as the maximum level of irradiation. In some examples, the ultrasound receiver may be the one referred to below. Figure 2 An example of the receiver system 202 described.

[0027] Optical techniques such as those based on photoplethysmography (PPG) systems and Figure 1 One important difference between PAPG-based methods is that Figure 1 The sound waves shown travel much slower than the reflected light waves involved in PPG. Therefore, based on Figure 1 Depth discrimination based on the arrival time of sound waves is possible, whereas depth discrimination based on the arrival time of light waves in a PPG may not be feasible. This depth discrimination allows some of the disclosed specific implementations to isolate sound waves received from different blood vessels.

[0028] Based on some such examples, this depth discrimination allows for the differentiation of arterial heart rate waveforms from venous heart rate waveforms and other heart rate waveforms. Therefore, blood pressure estimation based on the depth discrimination PAPG method can be significantly more accurate than blood pressure estimation based on PPG-based methods.

[0029] Example PAPG device

[0030] Figure 2 This is a block diagram illustrating example components of a device according to some disclosed specific embodiments. In this example, device 200 includes an interface 201, a receiver system 202, a light source system 204, and a waveguide system 205. Although the light source system 204 and the waveguide system 205 are... Figure 2 While shown as a separate element, in some instances, waveguide system 205 may be described as part of light source system 204. Some specific implementations of device 200 may include control system 206, interface system 208, noise reduction system 210, or combinations thereof.

[0031] This document discloses various examples of interface 201 and various configurations of light source system 204 and receiver system 202. Some examples are described in more detail below.

[0032] In some specific embodiments of the receiver system 202, including an ultrasound receiver system, the interface 201 may be an interface with a contact portion configured to contact a user's body part (such as...). Figure 1 The fingers shown (115) make contact.

[0033] In some embodiments, the light source system 204 may include one or more light sources positioned remotely from the interface 201 and / or receiver system 202. As will be described elsewhere herein, in some example embodiments, some or all of the one or more light sources may be positioned substantially opposite to the interface 201 and / or receiver system 202. In some example embodiments, some or all of the one or more light sources may be positioned at or along an axis angled relative to or along a central axis associated with the interface 201 and / or receiver system 202. For illustrative purposes, in a device 200 implemented as a wearable device such as a wristband or ring, the interface 201 and / or receiver system 202 may be positioned at the bottom portion of the wearable device, while one or more light sources may be positioned at the top portion opposite the bottom portion or along the side of the wearable device. As will be discussed further, light may propagate via one or more optical waveguides of the waveguide system 205 toward a target object (e.g., a body part, tissue of interest) approaching the interface 201 and / or receiver system 202, and ultrasonic waves (e.g., 102) may be generated by the target object. For example, one or more optical waveguides can be optical fibers.

[0034] According to some examples, interface 201 may include different portions with varying thicknesses, depending on the specific implementation. In some examples, interface 201 may include a first portion residing between the light source system 204 and the outer surface of interface 201. In some examples, the first portion may have a first portion thickness less than a second portion thickness residing between at least one receiver element of receiver system 202 and the outer surface of interface 201. In some such examples, the first portion may be configured to receive light from light source system 204 and may also be configured to reflect ultrasonic waves generated by a target object toward at least one receiver element of receiver system 202. However, in some examples, the first portion residing between light source system 204 and the outer surface of interface 201 may have a first portion thickness greater than the second portion residing between at least one receiver element of receiver system 202 and the outer surface of interface 201.

[0035] In some embodiments, interface 201 may be made of a flexible material and include one or more of different portions (e.g., layers) having specific acoustic properties (e.g., acoustic impedance). In some specific embodiments, the first layer of interface 201 having a contact portion may be a material having an acoustic impedance within, approximately within, or in the range of acoustic impedance of human skin (1.5 MNayl) or muscle (1.71 MNayl). For example, the first layer or a portion thereof may be polyethylene having an acoustic impedance of 1.73 MNayl. In various specific embodiments, the first layer may have an acoustic impedance within the range of acoustic impedance of human skin. As an example only, the acoustic impedance of the first layer may be between 1.5 MNayl and 2.0 MNayl to facilitate approximation or matching of acoustic impedance. Therefore, in some exemplary embodiments, materials with acoustic impedance within this range (such as low-density polyethylene with an acoustic impedance of 1.79 MNayl, styrene-butadiene (or its rubber derivative) with an acoustic impedance of 1.95 MNayl, ethyl vinyl acetate containing 18% acetate with an acoustic impedance of 1.69 MNayl, or ethyl vinyl acetate containing 28% acetate with an acoustic impedance of 1.60 MNayl) can be used in the first layer of interface 201 that contacts the user's skin. Unlike typically rigid platforms, the material of interface 201 can be malleable, flexible, or otherwise conformable to the shape and contour of the user's body parts (e.g., at fingers 115, wrists, waist, etc.).

[0036] In some specific implementations, interface 201 may have a second layer having a surface close to (e.g., in contact with) receiver system 202. This second layer is a material whose acoustic impedance is configured to approximate that of receiver system 202, similar to the acoustic properties of the first layer approximating skin. An example range for the acoustic impedance values ​​associated with receiver system 202 could be 2 MRayl to 10 MRayl.

[0037] In some implementations, more than two layers may exist in interface 201. For example, interface 201 may include two layers adjacent to the user's body part and a layer adjacent to the receiver system 202. In some cases, the two layers adjacent to the user's body part may be materials with different acoustic impedances approximating the body part, such as polyethylene (acoustic impedance of 1.73 MNayl) and low-density polyethylene (acoustic impedance of 1.79 MNayl). This type of hierarchical configuration can introduce a gradual change in acoustic properties or acoustic impedance, which gradually matches the acoustic properties or acoustic impedance of the skin or body part and the acoustic properties or acoustic impedance of the receiver system 202, thereby advantageously minimizing acoustic energy loss across interface 201 and improving the efficiency of sound wave transmission.

[0038] Figure 3A This is an example of a hierarchical portion or layer of interface 201 of a device 200 according to some disclosed specific embodiments. In this example, a first layer 301a is disposed adjacent to (e.g., disposed above) a second layer 301b. The first layer 301a may have a first acoustic property, such as the acoustic impedance of a first material (e.g., polyethylene). The first layer 301a may have a contact portion that abuts against a body part of a user. The second layer 301b may have a second acoustic property, such as the acoustic impedance of a second material (e.g., low-density polyethylene). In some variations of this example, the second acoustic property of the second layer 301b may be closer to or better approximated to the acoustic impedance of a receiver or receiver element 302. Receiver element 302 may be an example of a receiver element of receiver system 202. In some variations, the first acoustic property of the first layer 301a may be closer to or better approximated to the acoustic impedance of a target object, such as skin (1.5), muscle (1.71), fat (1.34), blood (1.65), or other body parts.

[0039] Figure 3B This is another example of a hierarchical portion or layer of the interface 201 of a device 200 according to some disclosed specific embodiments. In this example, the first layer 301a, the second layer 301b, and the third layer 301c may be arranged adjacent to each other. Similar to Figure 3A For example, each of these layers can have corresponding acoustic properties.

[0040] In some configurations, at least one layer may be removable, applyable, or replaceable. This type of layer may function as an interface between the skin and the optical waveguide. This helps protect the soft skin from the potentially sharp edges of the waveguide and from environmental contaminants such as dust and liquids. Therefore, in some configurations, this protective layer may be the top layer (e.g., first layer 301a). This layer may be a transparent polymer film or strip with useful optical and acoustic transmitting properties. An example of this layer may be a thin polymer film made of a transparent and flexible material, at least a portion of which has adhesive or tacky properties, similar to a screen protector for a user device. This tacky polymer film may have an acoustic impedance closely matched to the skin's acoustic impedance (approximately 1.5 M Nayl), or in some instances, an acoustic impedance closely matched to the acoustic impedance of an adjacent layer (e.g., second layer 301b or third layer 301c). In some configurations, this type of layer may be non-removable and permanently attached to an adjacent layer or receiver element 302.

[0041] Figure 3C This is another example of a hierarchical portion or layer of the interface 201 of a device 200 according to some disclosed specific embodiments. In this example, the properties of the interface layer 301 are even comparable to... Figure 3B The examples are more granular, having multiple layers or sections with gradually increasing or decreasing acoustic impedance. In some specific implementations, the interface layer 301 may instead be a material with gradually varying acoustic impedance, possibly due to the material being more or less densely packed across the thickness of layer 301.

[0042] In some embodiments, the first layer 301a of interface 201 or its contact portion may include a coating material. In some cases, the coating material may be a transparent polymer strip or film, which may be removable or applyable. Such a coating material may serve as a protective layer (e.g., a protective layer as discussed above) and / or further facilitate the transition of acoustic properties between the body part and the layer.

[0043] As a general approach, the material of the layer of interface 201 can be selected according to the following equation (Equation 1), which represents the reflection coefficient Γ of sound waves propagating through or interacting with interface 201:

[0044] In Equation 1, Z1 represents the impedance of the first material, Z2 represents the impedance of the second material, and E 1i Let E represent the root-mean-square amplitude of the electric field of the incident sound wave. 1r This represents the amplitude of the electric field of the reflected sound wave. The reflection coefficient Γ is E 1r With E 1i The ratio.

[0045] In an example configuration of interface 201, if Z1 = 1.5 (skin) and Z2 = 1.73 (polyethylene), then Γ is approximately 7.1%, so 92.9% of the acoustic energy can be transmitted through interface 201. In another example configuration of interface 201, if Z1 = 1.71 (muscle) and Z2 = 1.79 (low-density polyethylene), then Γ is approximately 2.3%, so 97.7% of the acoustic energy can be transmitted through interface 201. A similar determination of transmission efficiency can be made relative to additional layers (e.g., a graded matching layer). Based on the choice of materials with higher transmission efficiency, a lower reflection coefficient Γ can lead to higher acoustic transmission efficiency and higher signal quality (e.g., higher signal-to-noise ratio (SNR)).

[0046] Advantageously, according to the embodiments described herein, a platform is not required to implement the PAPG-based method. While platforms typically have rigid and inflexible surfaces, the interface 201 disclosed herein may not be so rigid. The use of embedded optical fibers or waveguides allows for a wider selection of polymers as matching layers, which optimally match the acoustic impedance of the user (e.g., skin) with low attenuation. For example, it becomes feasible to construct the interface 201 and device 200 using flexible materials (e.g., polyethylene). Furthermore, the acoustic attenuation layer and the positioning and number of components (e.g., light source, receiver elements) can be optimized without constraints such as the shape and size of device 200. Thus, device 200 can be implemented and operated as a user-conforming wearable device (wristband, ring, bracelet, anklet, etc.). Specific implementations and variations thereof will be described in more detail below. In such wearable devices, interface 201 can achieve direct contact with tissue of interest (e.g., near blood vessels) to acquire and evaluate photoacoustic signals (e.g., emitted sound waves 102). Therefore, device 200 can be a user-friendly, lightweight, compact or semi-compact and portable device for enhanced and consistent monitoring of physiological parameters such as blood pressure.

[0047] According to some examples, interface 201 (or another part of device 200) may include one or more anti-reflective layers. In some examples, the one or more anti-reflective layers may reside on or be close to one or more outer surfaces of interface 201.

[0048] In some examples, at least a portion of the outer surface of interface 201 may have an acoustic impedance configured to approximate that of human skin. This portion of the outer surface of interface 201 may, for example, be a portion configured to receive a target object (such as a human finger or other appendage). (As used herein, the terms "finger" and "tip" 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 interface 201 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.

[0049] Alternatively or additionally, in some examples, at least the outer surface of interface 201 may be configured to conform to the surface of human skin. In fact, device 200 may be formed substantially of a material conformable to the surface of human skin. In some such examples, at least the outer surface of interface 201 may have material properties similar to those of putty or chewing gum.

[0050] In some examples, at least a portion of interface 201 has an acoustic impedance configured to approximate the acoustic impedance of one or more receiver elements of receiver system 202. According to some examples, a layer residing between interface 201 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 interface 201 and one or more receiver elements may have an acoustic impedance within a range between the acoustic impedance of the platform and the acoustic impedance of one or more receiver elements.

[0051] This document discloses various examples of receiver systems 202, some of which may include ultrasonic receiver systems, optical receiver systems, or combinations thereof. In some embodiments including ultrasonic receiver systems, an ultrasonic receiver and an ultrasonic transmitter may be combined in an ultrasonic transceiver. In some examples, receiver system 202 may include a piezoelectric receiver layer, such as a PVDF polymer layer or a PVDF-TrFE copolymer layer. In some embodiments, a single piezoelectric layer may be used as an ultrasonic receiver. In some embodiments, 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 202 may include an array of ultrasonic transducer elements, such as an array of piezoelectric micromechanical ultrasonic transducers (PMUTs), an array of capacitive micromechanical ultrasonic transducers (CMUTs), etc. In some such examples, a piezoelectric receiver layer, PMUT elements in a monolayer 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 202 may be an ultrasonic receiver array, or may include an ultrasonic receiver array. In some examples, device 200 may include one or more individual ultrasonic transmitter elements. In some such examples, the ultrasonic transmitter may include an ultrasonic plane wave generator.

[0052] In some examples, the light source system 204 may include one or more light-emitting diodes (LEDs). In some embodiments, the light source system 204 may include one or more laser diodes. According to some embodiments, the light source system 204 may include one or more vertical cavity surface-emitting lasers (VCSELs). In some embodiments, the light source system 204 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.

[0053] According to some examples, the light source system 204 may include one or more light guiding elements configured to guide light from the light source system toward a target object along a first axis. In some examples, the one or more light guiding elements may include at least one diffraction grating. Alternatively or additionally, the one or more light guiding elements may include at least one lens.

[0054] In some examples, the light source system 204 can be configured to emit light in one or more wavelength ranges. In some examples, the light source system 304 can be configured to emit light in a wavelength range of 500 nanometers (nm) to 600 nanometers (nm). According to some examples, the light source system 304 can be configured to emit light in a wavelength range of 800 nm to 950 nm. Taking into account factors such as skin reflectivity, energy density, absorption coefficients of blood and various tissues, and skin safety limits, one or both of these wavelength ranges can be suitable for a variety of use cases. For example, both the 500 nm to 600 nm wavelength range and the 800 nm to 950 nm wavelength range can be suitable for obtaining photoacoustic responses from relatively small, shallow blood vessels, such as those with a diameter of approximately 0.5 mm and a depth in the range of 0.5 mm to 1.5 mm, such as those found in a finger. The wavelength range of 800 nm to 950 nm can, for example, be used to obtain photoacoustic responses from relatively large, deep blood vessels, such as those with a diameter of about 2.0 mm and a depth in the range of 2 mm to 3 mm, such as those found in an adult wrist.

[0055] Depending on the specific implementation, the light source system 204 may include various types of driving circuitry. In some disclosed embodiments, the light source system 204 may include at least one multi-junction laser diode, which can produce less noise than a single-junction laser diode. In some examples, the light source system 204 may include driving circuitry (also referred to herein as drive 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 204 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.

[0056] In some embodiments, at least a portion of device 200 (e.g., receiver system 202, light source system 204, or both) may include one or more sound-absorbing layers, sound-insulating materials, light-absorbing materials, reflective materials, or combinations thereof. In some examples, the sound-insulating material may reside between at least a portion of light source system 204 and receiver system 202. In some examples, at least a portion of device 200 (e.g., receiver system 202, light source system 204, or both) may include one or more electromagnetically shielded transmitting lines. In some such examples, the one or more electromagnetically shielded transmitting lines may be configured to reduce electromagnetic interference received by receiver system 202 from light source system 204.

[0057] In some embodiments, the light source system 204 can be configured to emit light of various wavelengths, which can be selected to trigger acoustic emission primarily from a specific type of material. For example, because hemoglobin in blood absorbs near-infrared light very strongly, in some embodiments, the light source system 204 can 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 206 can control the wavelength of the light emitted by the light source system 204 to preferentially induce acoustic emission in blood vessels, other soft tissues, and / or bone. For example, an infrared (IR) light-emitting diode (LED) can be selected, and short IR light pulses are emitted to irradiate a portion of the target object and generate acoustic emission, which is then detected by the receiver system 202. In another example, an IR LED and a red LED or other color (such as green, blue, white, or ultraviolet (UV)) can be selected, and short light pulses are emitted sequentially from each light source, wherein an ultrasound image is obtained after light has been emitted from each light source. In other embodiments, one or more light sources of different wavelengths can be excited sequentially or simultaneously to generate acoustic emission detectable by an ultrasound receiver. Image data from an ultrasound receiver can be combined to determine the location and type of material within a target object. This image data is obtained using light sources of different wavelengths at different depths (e.g., different RGDs) within the target object. Image contrast can occur because materials in the body typically absorb light of different wavelengths in different ways. Since materials in the body absorb light of specific wavelengths, they can differentially heat up and generate acoustic emissions carrying sufficiently short light pulses of adequate intensity. Depth contrast can be obtained at each selected wavelength using light of different wavelengths and / or intensities. That is, continuous images can be obtained at a fixed RGD (which may correspond to a fixed depth within the target object) using different light intensities and wavelengths to detect material and its location within the target object. For example, photoacoustic detection can be used to detect hemoglobin, blood glucose, or blood oxygen within blood vessels inside a target object, such as a finger.

[0058] According to some embodiments, the light source system 204 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 204 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 204 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 204 at a frequency corresponding to the resonant frequency of the resonant acoustic cavity in the sensor stack, thereby allowing the accumulation of received ultrasonic waves and a higher synthesized signal intensity. In some embodiments, the light source system 204 may include filtered light or a light source with a specific wavelength for detecting the selected material. In some embodiments, the light source system 204 may include light sources such as red, green, and blue LEDs of a display, 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 lamps (e.g., LEDs or xenon flash lamps) with or without filters may be used for short-term illumination of the target object.

[0059] Control system 206 may include one or more general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or combinations thereof. Control system 206 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, device 200 may have a memory system including one or more memory devices, but... Figure 2 The memory system is not shown. Control system 206 can be configured to receive and process data from receiver system 202, for example, as described below. If device 200 includes an ultrasonic transmitter, control system 206 can be configured to control the ultrasonic transmitter. In some implementations, the functionality of control system 206 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).

[0060] In some examples, the control system 206 may be communicatively coupled to the light source system 204 and configured to control the light source system 204 to emit light toward a target object on the outer surface of the interface 201. In some such examples, the control system 206 may be configured to receive from the ultrasound receiver system 202 a signal corresponding to ultrasound waves generated by the target object in response to light from the light source system 204. In some examples, the control system 206 may be configured to identify one or more vascular signals, such as arterial or venous signals, from the ultrasound receiver system. In some such examples, the one or more arterial or venous signals may be, or may include, one or more vessel wall signals corresponding to ultrasound waves generated by one or more arterial or venous walls of the target object. In some such examples, the one or more arterial or venous signals may be, or may include, one or more arterial blood signals corresponding to ultrasound waves generated by blood within an artery of the target object or one or more venous blood signals corresponding to ultrasound waves generated by blood within a vein of the target object. In some examples, the control system 206 may be configured to determine or estimate one or more physiological parameters or cardiac characteristics based at least in part on one or more arterial signals, one or more venous signals, or combinations thereof. According to some examples, a heart characteristic can be blood pressure, or can include blood pressure.

[0061] In another example, control system 206 may be communicatively coupled to receiver system 202. Control system 206 may be configured to select at least one receiver element from a plurality of receiver elements of receiver system 202. Such selected receiver element may correspond to the optimal signal from the plurality of receiver elements. In some embodiments, the selection of at least one receiver element may be based on information about detected acoustic signals (e.g., arterial or venous signals) from the plurality of receivers. For example, the signal quality or signal strength of some signals (e.g., based on signal-to-noise ratio (SNR)) may be relatively higher than some other signals, or higher than a predetermined threshold or percentile, which may indicate the optimal signal. In some specific embodiments, control system 206 may also be configured to determine or estimate at least one characteristic of a blood vessel, such as pulse wave velocity (indicating arterial stiffness), arterial size, or both, based on information about the detected acoustic signals.

[0062] Some specific embodiments of device 200 may include interface system 208. In some examples, interface system 208 may include a wireless interface system. In some specific embodiments, interface system 208 may include a user interface system, one or more network interfaces, one or more interfaces between control system 206 and memory system, and / or one or more interfaces between control system 206 and one or more external device interfaces (e.g., ports or application processors), or combinations thereof. Depending on some examples where interface system 208 is present and the interface system includes a user interface system, the user interface system may include a microphone system, a speaker system, a haptic feedback system, a voice command system, one or more displays, or combinations thereof. Depending on some examples, interface system 208 may include a touch sensor system, a gesture sensor system, or combinations thereof. The touch sensor system (if present) may be a resistive touch sensor system, a surface capacitive touch sensor system, a projected capacitive touch sensor system, a surface acoustic wave touch sensor system, an infrared touch sensor system, any other suitable type of touch sensor system, or a combination thereof, or may include a resistive touch sensor system, a surface capacitive touch sensor system, a projected capacitive touch sensor system, a surface acoustic wave touch sensor system, an infrared touch sensor system, any other suitable type of touch sensor system, or a combination thereof.

[0063] In some examples, interface system 208 may include a force sensor system. The force sensor system (if present) may be a piezoresistive sensor, a capacitive sensor, a thin-film sensor (e.g., a polymer-based thin-film sensor), another suitable type of force sensor, or a combination thereof, or may include 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 embodiments, 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 208 may include an optical sensor system, one or more cameras, or a combination thereof.

[0064] According to some examples, device 200 may include a noise reduction system 210. For example, noise reduction system 210 may include one or more mirrors configured to reflect light from light source system 204 away from receiver system 202. In some implementations, noise reduction system 210 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 210 may include sound-insulating materials that may reside between, on, or in at least a portion of receiver system 202, or in a combination thereof, the light source system 204 and receiver system 202. In some examples, noise reduction system 210 may include one or more electromagnetically shielded transmission lines. In some such examples, the one or more electromagnetically shielded transmission lines may be configured to reduce electromagnetic interference received by receiver system 202 from circuitry of light source system 204, receiver system circuitry, or combinations thereof.

[0065] Device 200 can be used in a variety of different contexts, many of which are disclosed herein. For example, in some implementations, a mobile device may include device 200. In some such examples, the mobile device may be a smartphone. In some implementations, a wearable device may include device 200. Wearable devices may be, for example, wristbands, armbands, watches, rings, headbands, or patches.

[0066] Example configuration of a PAPG device

[0067] Figure 4A An example configuration of an interface 401, a receiver element 402 of a receiver system, and an optical waveguide 404 of a photoacoustic device according to some disclosed specific embodiments is shown. The photoacoustic device may be an example of device 200 and may be configured to perform the PAPG-based method as described herein. Interface 401 may be an example of interface 201 and may be constructed to be flexible and conform to a user's body part 415 or other appendage. The receiver system may be an example of receiver system 202. Receiver element 402 may be an example of receiver element 302. Receiver element 402 may be at least partially embedded in interface 401. As described with respect to interface 201 and receiver system 202, interface 401 may be made of one or more materials having acoustic properties. The acoustic properties may be an acoustic impedance approximating the acoustic impedance of interface 201 or a portion thereof, receiver system 202 or a portion thereof, and / or at least a portion of body part 415.

[0068] refer to Figure 4AAs can be seen from the example, interface 401 is positioned adjacent to receiver element 402. In some embodiments, waveguide 404 may be coupled to a light source system (not shown) at one end, at least partially embedded in interface 401, and terminate at an opening 406 of interface 401 at the other end. Waveguide 404 does not extend into human skin, but may be adjacent to or terminated on the skin of body part 415. In some instances, waveguide 404 and skin may be separated by a thin polymer film (such as the protective layer discussed above). In some embodiments, waveguide 404 may have a degree of relaxation within interface 401 to allow for adjustability. Consider a use case in which the photoacoustic device is implemented as a wearable device such as a flexible wristband or ring. Since at least a portion of the wristband or ring (e.g., interface 201) may be made of a relatively flexible material, at least a portion (or the entire wristband or ring) may be stretched or opened to a certain extent when worn or attempted to be worn, and retract to its original shape when manual pressure is removed. This can help to apply pressure conformally to the user's tissues. In some implementations, waveguide 404 may extend adjacent to receiver element 402 or be built into receiver element 402 (e.g., extending through a hole or opening in the receiver element).

[0069] Depending on the specific implementation, opening 406 may be covered by a transparent material, covered by the material of interface 401, or exposed to the outside of the photoacoustic device. In some implementations, opening 406 may terminate at a protrusion of interface 401. Physical protrusions may further aid in guiding light toward a target object or provide the user with tactile indication of where the light is being emitted or should be emitted. Numerous variations will be apparent to those skilled in the art. Optical waveguides embedded in the acoustic matching layer can also bring light very close to tissue. When a user's body part 415 contacts interface 401, light emitted from the light source system of the photoacoustic device via waveguide 404 can be guided toward a target part of interest, such as one or more blood vessels in body part 415. In some embodiments, the light source system and one or more of its light sources may be positioned remotely from receiver element 402 and / or receiver system.

[0070] In some embodiments, waveguide 404 may be an optical fiber. Advantageously, the flexible construction of interface 201 and its layers allows waveguide 404 to be embedded in interface 201 at any angle. Furthermore, the small area irradiation provided by waveguide 404 helps reduce signal noise. In some scenarios, this reduction in signal noise includes a reduction in background acoustic signals (e.g., background acoustic signals caused by the interaction of light with tissues and organs of no interest). As discussed throughout this disclosure, optically opaque materials with desired acoustic transmission properties can be used as interface materials to achieve this. Furthermore, angulating waveguide 404 can help improve the detection of acoustic signals in response to light generation and reception by allowing a clean acoustic path to receiver element 402. Receiver element 402 may be communicatively coupled to the control system of the photoacoustic device and may be configured to transmit acoustic signals to the control system. Figure 4A In the example, waveguide 404 is angled (θ) relative to the surface of interface 201, or more specifically, angled relative to the top layer of interface 201 (capable of contacting body part 415). Other angles and approaches are also possible, as indicated by the dashed lines representing possible waveguide configurations, including waveguide configurations extending adjacent to (or through) receiver element 402, curved waveguide configurations, and waveguide configurations with corners.

[0071] Figure 4B This example configuration is shown according to some disclosed specific embodiments of interface 401, receiver element 402 of receiver system, and optical waveguide 404 of photoacoustic device. Here, the components of photoacoustic device are configured such that, except that waveguide 404 is substantially parallel to or transverse to interface 201 or at an angle to the surface of interface 201, the configuration is similar to... Figure 4A The configurations are the same.

[0072] Figure 4C Another example configuration of interface 401, receiver element 402 of receiver system, and optical waveguide 404 of photoacoustic device according to some disclosed specific embodiments is shown. Here, receiver element 402 may be disposed adjacent to interface 401, but with... Figure 4A and Figure 4B Compared to the previous example, it is set in a different location. Since the waveguide 404 can be angled in any convenient way, the receiver element 402 can also be positioned in any convenient location. This can be useful for the small form factor and rack of semi-compact and compact devices such as wearable devices.

[0073] Figure 4D An example configuration of an interface 401, a receiver element 402 of a receiver system, and multiple optical waveguides 404a, 404b of a photoacoustic device, according to some disclosed specific embodiments, is shown. Similar to... Figure 4B and Figure 4C An example is shown, which illustrates substantially horizontal optical waveguides 404a, 404b, which originate from different directions toward the opening 406 of the interface 401, are embedded in the interface 401, and point toward the user's body part 415.

[0074] Figure 4E An example configuration of an interface 401, a receiver element 402 of a receiver system, and multiple optical waveguides 404a, 404b of an optoacoustic device according to some disclosed specific embodiments is shown. Here, waveguides 404a, 404b are arranged from the same side ( Figure 4E (Approaching from the left side). It can also be seen that multiple receiver elements 402a, 402b are included in the device. Each of these receiver elements 402a, 402b can detect acoustic signals generated due to the interaction of light with the body part 415. It should be understood that receiver elements 402a, 402b do not necessarily correspond to a specific one of the optical waveguides 404a, 404b. That is, any one of receiver elements 402a or receiver elements 402b can be configured to detect acoustic signals generated due to light from any one of the optical waveguides 404a or optical waveguides 404b. However, receiver elements 402a, 402b and optical waveguides 404a, 404b can be positioned such that the reception of acoustic signals is optimized to achieve minimal noise (e.g., high SNR) or maximum detectability (e.g., unobstructed path or line of sight to the body part 415). For example, in Figure 4E As can be seen, receiver elements 402a and 402b on one side (right side) can create space for optical waveguides 404a and 404b to enter from the other side (left side).

[0075] Figure 4F An example configuration of an interface 401, a plurality of receiver elements 402a, 402b of a receiver system, and a plurality of optical waveguides 404a, 404b of a photoacoustic device, according to some disclosed specific embodiments, is shown. As shown, a user's body part (e.g., finger 415) can be pressed onto the interface 401. The non-cross-sectional view is shown for illustrative and perspective purposes and illustrates that the optical waveguides and receiver elements can be oriented in different ways, such as orthogonal to the optical waveguides and the positioning of the receiver elements shown so far (e.g., in…). Figures 4A to 4E (in Chinese). Furthermore, optical waveguides 404a and 404b do not need to be straight and linear, such as... Figures 4A to 4EThe optical waveguide shown is illustrated. The optical fiber can be embedded and oriented in a relatively loose configuration, similar to a cable, to accommodate the positioning of openings and components of the photoacoustic device, such as receiver elements 402a, 402b. The finger 415 may have a target object, such as a blood vessel 416. Light emitted from the opening 406 of the optical waveguides 404a, 404b can interact with the blood vessel 416, causing an acoustic signal to be generated by the target object and transmitted toward the receiver elements 402a, 402b of the receiver system.

[0076] Although two receiver elements 402a, 402b and two optical waveguides 404a, 404b are shown, this is by no means intended to imply that each optical waveguide has a corresponding receiver element. For example, for Figure 4F An optical-acoustic device may contain one receiver element, three or more receiver elements, one waveguide, or three or more waveguides to transmit optical signals and receive acoustic signals. However, as will now be explained, using more receiver elements or more waveguides can optimize signal selection (e.g., less noise).

[0077] Therefore, it can be seen that many different light emission configurations are possible for different purposes. For example, such as Figures 4A to 4F As illustrated, vertical, angled, and / or horizontal emission is possible. Multi-point information about at least one characteristic of body part 415 can be obtained from multiple waveguides, multiple receiver elements, and / or multiple light sources. This characteristic may be blood pressure, heart rate, pulse wave velocity (PWV, a measure of arterial stiffness), arterial size, or another cardiac feature. Furthermore, as mentioned above, using the PAPG method to obtain acoustic signals can achieve enhanced depth discrimination superior to the PPG method. Thus, at least one characteristic associated with one or more vessels of body part 415, such as blood pressure, PWV, heart rate, etc., can be characterized and monitored. Depending on some approach, the angle of a given waveguide 404 or a plurality of waveguides 404a, 404b can be selected based on noise or signal quality (e.g., SNR) and / or the detectability or line of sight of the received acoustic signal.

[0078] Furthermore, having multiple waveguides and / or angles allows for optimization of signals from a single wavelength. That is, in some cases, multiple waveguides can transmit light of the same wavelength at different times (e.g., time-shifted pulses) to distinguish optical signals, and the waveguide capable of providing light resulting in minimal noise or highest detectability can be selected or given higher weight for continuous or future light transmission. See also the discussion below related to delay-summing beamforming. In some cases, having multiple waveguides and / or angles allows for easier implementation of multiple wavelengths. That is, optical signals with different wavelengths can be transmitted via different waveguides. In some cases, multiple channels can be designed for different optical waveguides and optical fibers, where these waveguides can carry light from different sources (which can generate or provide optical signals with single or multiple wavelengths) and emit that light at different points in the target object.

[0079] Figure 5A An example of an array of ultrasound receiver elements for use with the specific embodiments disclosed herein is shown. In this example, the array of ultrasound receiver elements 502 is a two-dimensional (regional) array of ultrasound receiver elements. According to this example, the array of ultrasound receiver elements 502 is arranged in a square having six (6) active ultrasound receiver elements 515 on each side, and a total of 36 active ultrasound receiver elements 515. As with other disclosed examples, Figure 5A The types, numbers, sizes, and arrangements of the elements shown and described herein are merely examples. For instance, alternative examples of a two-dimensional array of ultrasound receiver elements may be arranged in different shapes, such as non-square rectangular shapes, hexagonal shapes, etc. Some alternative examples of a two-dimensional array of ultrasound receiver elements may include different numbers of active ultrasound receiver elements 515, such as 16, 20, 25, 30, 32, 36, 40, 48, etc.

[0080] Figure 5B Another example of an array of ultrasound receiver elements for use with the specific embodiments disclosed herein is shown. In this example, the array of ultrasound receiver elements 504 is a linear array of ultrasound receiver elements. According to this example, the array of ultrasound receiver elements 502 is arranged in a row having six (6) active ultrasound receiver elements 515.

[0081] In some specific implementations, the array of ultrasound receiver elements can be an array of arrays. For example, the array can be a linear array or a two-dimensional array within a two-dimensional array of ultrasound receiver elements 502. As another example, the array can be a linear array or a two-dimensional array within a linear array of ultrasound receiver elements 504.

[0082] Having multiple receiver elements is advantageous for the disclosed specific implementations because it eliminates the need for precise positioning of the body part of interest or target object relative to the receiver elements. For example, a user can wear the wearable photoacoustic device in any orientation or position along the wrist or fingers and still be able to monitor physiological parameters because the ubiquitous presence of the receiver elements (and / or other components, such as waveguides) allows the PAPG method described herein to be performed with the wrist or fingers, and in some specific implementations, leads to the selection of the optimal or best receiver element or waveguide for determining the physiological parameters as described elsewhere herein.

[0083] In some cases, multiple receiver elements may be used to implement the delay-summing beamforming process. More specifically, a delay can be applied to the ultrasound receiver signals by performing a correlation operation on the input ultrasound receiver signals. For example, the control system may perform a correlation operation on a first ultrasound receiver signal and a second ultrasound receiver signal, and may determine that by applying a first time shift to the first ultrasound receiver signal, the first ultrasound receiver signal will be strongly correlated with the third ultrasound receiver signal. Similarly, the control system may perform a correlation operation on the second and third ultrasound receiver signals, and may determine that by applying a second time shift to the second ultrasound receiver signal, the second ultrasound receiver signal will be strongly correlated with the third ultrasound receiver signal. According to this example, the control system may be configured to sum the first time-shifted ultrasound receiver signal, the second time-shifted ultrasound receiver signal, and the third ultrasound receiver signal to generate a summed signal. The amplitude of this summed signal may be greater than the amplitude of any one of the first, second, or third ultrasound receiver signals. In some instances, the signal-to-noise ratio (SNR) of the summed signal may be greater than the SNR of any one of the first, second, or third ultrasound receiver signals. Therefore, a cleaner signal with less noise can be obtained by using multiple receiver elements.

[0084] Figure 6 An example configuration of a photoacoustic device 600 according to some disclosed specific implementations is shown. The photoacoustic device 600 may be an example of device 200. As noted elsewhere herein, the photoacoustic device 600 may be implemented and operated as a wearable device, such as a ring, watch, wristband, belt, etc. For example, the photoacoustic device 600 may be a watch that can be worn on a user's wrist, or it may be a ring that can be worn on a user's finger. A user's body part may be associated with a target object or tissue of interest, such as the location of blood vessels. Thus, the photoacoustic device 600 may perform PAPG-based techniques as discussed above to monitor physiological parameters such as blood pressure, heart rate, PWV, arterial size, or other cardiac characteristics.

[0085] In some embodiments, the photoacoustic device 600 may include a user interface 602, a wearable structure 604, a light source system (having at least one light source 606), a receiver system (having one or more receiver elements, such as receiver elements 609a-609n), an interface 610, and a waveguide system 612. In some embodiments, the user interface 602 may include a dial (e.g., a watch face), a display screen, a touch screen, and / or physical controls (e.g., a dial, a switch). In some embodiments, the user interface 602 may be part of a housing 601 that may house other components, such as a memory, storage device, a control system 206, and / or an interface system 208. In some embodiments, the wearable structure 604 may include strips or flexible bands to form a loop shape (e.g., circular, elliptical, or one or more overlapping strips). The interface 610 is incorporated into the wearable structure 604 and may have contact portions that can contact a user's body part. In some embodiments, the contact portion may face inward toward the open space 618 surrounded by the wearable structure 604. However, in some embodiments, the contact portion may also face outward, in which case the interface 610 may also include the outer surface of the wearable structure 604. Interface 610 may be an example of interface 201. Thus, in some embodiments, at least a portion of the material of interface 610 may be flexible, resilient, or otherwise conform to the shape of a body part. For example, at least the inner surface of the wearable structure 604 may be made of a flexible material to comfortably conform to a user's body part. The inner surface may include a first layer 301a, which, for example, as discussed above, may be made of a relatively soft material (e.g., a polymer such as polyethylene). In another example, the entire wearable structure 604 may be made of a flexible material. In some embodiments, the receiver system may include one or more receiver elements 609a-609n. At least some of the one or more light sources (one of which is shown as light source 606) may be located near (e.g., near region 614) a portion of the photoacoustic device 600 that is substantially opposite to one or more receiver elements and close to the location of housing 601 or user interface 602. In some contexts, receiver elements 609a-609c may be considered substantially opposite to region 614. In some contexts, receiver element 609d may be considered substantially opposite to region 614. In some contexts, receiver element 609n may be considered substantially opposite to region 614. Advantageously, the light source system and receiver system being at least partially separated in position and / or located in substantially opposite regions of the photoacoustic device 600 rather than close to each other allows for flexibility in the placement of such components and allows waveguide emission of small-area irradiation to reduce background noise and provide a point light source directed toward a target of interest to the user.Having a light source system (e.g., circuitry associated with light source 606) on the opposite side of the receiver system (e.g., one or more of receiver elements 609a-609n) presents another potential advantage. More specifically, the light source system circuitry can be a significant source of noise, so having human tissue (the user's arm, fingers, etc.), including conductive materials, between the light source system and the receiver system in the open space 618 (in which a user's body part can be inserted) can significantly reduce the received noise. In some cases, one or more receiver elements 609a-609n may be embedded in and positioned along the wearable structure 604 (e.g., regions 616, 617). In this context, a component positioned "along the wearable structure" may mean at any radial location on the circumference of the wearable structure 604. In some specific embodiments, the light source system may include one or more light sources 606. At least some of the one or more light sources may be located near or inside the housing 601, for example, near region 614 and / or embedded in and positioned along the wearable structure 604 (e.g., regions 616, 617). In some cases, one or more light sources may be located near one or more of the receiver elements 609a-609n; in such cases, the intensity of light emission may be stronger than in cases where light is transmitted from, for example, the housing 601 via a longer optical waveguide. Similarly. Figure 5A and Figure 5BThe receiver element array, one or more light sources can be arranged as a two-dimensional array or a linear array, or an array within an array. In some specific embodiments, the waveguide system 612 may include one or more optical waveguides (such as optical fibers) and one or more waveguide terminals that terminate at interface 610 and are configured to be close to and deliver light to the user's tissue. For simplicity, one waveguide is shown. However, it can be seen in this example that individual waveguides may branch toward different portions of the wearable structure 604. One or more optical waveguides may be coupled to one or more light sources, embedded in and extending along the wearable structure 604, and terminate at an opening at interface 610. Seven waveguide terminals are illustrated, with three examples labeled 620a-620c, and five examples located near receiver elements 609a-609n (one of which is waveguide terminal 620b). However, in different configurations, there may be more or fewer waveguide terminals. There does not need to be a one-to-one relationship between the number of waveguide terminals and receiver elements. The waveguide terminals do not all need to be located in the same position relative to the receiver element or within the receiver element. The openings of the waveguide terminals may face inwards toward the open space 618 surrounded by the wearable structure 604. Such openings may be an example of the opening 406 described above. Light 622 emitted from one or more light sources may be emitted from the openings and interact with a target object (e.g., a blood vessel) to generate an acoustic signal 624 from the target object. The acoustic signal may be received by one or more receiver elements 609a-609n. According to an example configuration of the photoacoustic device 600, depending on the configuration and orientation of the waveguide, light may be emitted substantially vertically from a single waveguide or optical fiber relative to the surface of the interface 610, and the acoustic signal may be received at a single receiver element (similar to...). Figure 4A (One or more configurations shown). In some scenarios, according to, for example... Figures 4A to 4F The example configuration illustrates how this process can occur depending on the waveguide angle and / or receiver element positioning. Note that the number of light sources, receiver elements, and waveguides does not necessarily correspond to each other. For example, there may be fewer waveguides than light sources, and vice versa. Similarly, there may be fewer light sources than receiver elements, and vice versa.

[0086] In some embodiments, the control system may be another component of the photoacoustic device 600. For example, housing 601 may house the control system. In other embodiments, the control system may be separate from the photoacoustic device 600. The control system here may be an example of control system 206 and may be configured to perform various operations and applications related to the operation of the photoacoustic device 600. In some specific embodiments, the control system may be configured to select an optimal location for monitoring physiological parameters (e.g., blood pressure, heart rate). To achieve this, the control system may determine noise and / or detectability associated with various acoustic signals generated by light emitted toward a target object (e.g., a blood vessel) via one or more waveguides of waveguide system 612 and detected by one or more receiver elements 609a-609n of receiver system. Noise may be determined based on the signal strength and / or signal quality (e.g., SNR) of the acoustic signals. Detectability may involve the presence of an unobstructed path or line of sight to the target object, which may also be a function of noise.

[0087] In some embodiments, the photoacoustic device 600 may include a plurality of receiver elements 609a-609n. Five (5) receiver elements 609a-609n are shown placed in Figure 6 In the example locations shown, some receiver elements may be more clustered than others, such as the receiver elements in region 616 (receiver elements 609a-609c). These receiver elements may be embedded in the wearable structure 604 and arranged along the wearable structure (e.g., in regions 616, 617), arranged in an array (such as...). Figure 5A and Figure 5B The array shown is located at individual positions along the wearable structure 604, or as an array of respective positions along the wearable structure 604. The arrangement of the receiver elements allows them to be positioned close to potential target objects and areas of interest on the user's body parts (e.g., the base of the wrist, fingers). (See also...) Figures 4A to 4F As explained, the waveguide can emit light from the light source system (e.g., from at least one light source 606) toward the opening at any angle relative to the surface of interface 610.

[0088] Based on the structure of the example photoacoustic device 600 described above, the embodiments and specific implementations of the device described herein can fix a target body part or tissue of interest and obtain an optimal acoustic signal regardless of the movement of the user's body part or appendage. In some other example embodiments, the photoacoustic device 600 may be a cuff, or may include a cuff configured to apply uniform pressure around an appendage (such as a user's arm). This can improve the quality of the signal data.

[0089] Example Method

[0090] Figure 7 This is a flowchart of a method 700 for monitoring a user's physiological parameters using a photoacoustic device, based on some disclosed specific embodiments. It is used to perform... Figure 7 The functional structures illustrated in one or more boxes shown can be implemented by hardware and / or software components of a computerized device or system (in some embodiments, which may be implemented as a wearable device). Components of such a device or system may include, for example, one or more sensors, one or more light sources, one or more receiver elements, one or more optical waveguides, one or more control systems (including one or more processors), one or more memories, and / or one or more computer-readable means including a storage medium storing computer-readable and / or computer-executable instructions configured to cause the control system, one or more processors, or devices to perform the operations indicated by the boxes below when executed by the control system. Figure 2 Example components of the device are illustrated below, which are described in more detail above.

[0091] For example, Figure 7 The frame can be made of Figure 2 The device 200 or similar device or its components (e.g., a control system) performs the operation. Similar to other methods disclosed herein, Figure 7 The methods outlined herein 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 in the box shown can be executed concurrently.

[0092] At block 710, method 700 may include: transmitting an optical signal via one or more waveguides from a light source system of an optoacoustic device toward a portion of a receiver system of the optoacoustic device near a user, the receiver system being positioned away from and not in direct contact with the light source system, the receiver system being configured to detect an acoustic signal generated based on the optical signal. The receiver system may include one or more receiver elements or an array thereof. The light source system may include one or more light sources or an array thereof.

[0093] In some embodiments, the photoacoustic device may include: a light source system comprising one or more light sources; a receiver system comprising one or more receivers configured to detect acoustic signals generated based on optical signals from the one or more light sources; an interface layer accessible to a user, the interface layer comprising a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; a waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit optical signals from the one or more light sources to the user; or a combination thereof.

[0094] In some embodiments, the device may also include a wearable structure that can be attached to a user and includes a light source system, a receiver system, an interface layer, and a waveguide system.

[0095] In some embodiments, the device may be a wearable user device. A light source system may be disposed at a first portion of the user device, and at least one of one or more receivers may be disposed at a second portion of the user device; the first and second portions may be positioned such that when the user wears the user device, at least a portion of the user resides between the first and second portions; and at least one of one or more waveguides may be configured to provide light from the first portion of the user device toward the second portion. (Reference) Figure 6 As an example, the first part of the user equipment may correspond to region 614, and the second part of the user equipment may correspond to region 616.

[0096] In some embodiments, the first acoustic characteristic may include a first acoustic impedance associated with the user's skin, and the second acoustic characteristic may include a second acoustic impedance associated with one or more receivers. In some specific embodiments, the first acoustic impedance may be between about 1.5 and about 2.0, and the second acoustic impedance may correspond to the material of one or more receivers. In some approaches, the first and second acoustic impedances may be selected based on Equation 1.

[0097] In some embodiments, the interface layer may include a mating layer having a first surface and a second surface, the first surface being contactable with and configured to abut against the user's skin, and the second surface being adjacent to and configured to abut against the receiver system. In some embodiments, the mating layer may at least partially comprise polyethylene (or polyethylene variants, such as low-density polyethylene or high-density polyethylene in some cases). Other types of materials may be used as needed, as discussed above. In some embodiments, the mating layer may have an acoustic impedance that gradually varies between a first acoustic impedance associated with the user's skin and a second acoustic impedance associated with one or more receivers. In some embodiments, the first surface may have a first acoustic impedance, and the second surface may have a second acoustic impedance.

[0098] In some embodiments, the device may also include a control system configured to determine a user's physiological parameters based on detected acoustic signals. In some embodiments, the physiological parameters may include the user's blood pressure. In other embodiments, the physiological parameters may include heart rate, pulse wave velocity (PWV), arterial size, or another cardiac characteristic.

[0099] In some embodiments, the receiver system may include a plurality of receivers, each configured to transmit information about detected acoustic signals to a control system; and the control system may be configured to select at least one of the plurality of receivers based on the corresponding information received from the plurality of receivers regarding the detected acoustic signals. In some specific embodiments, the control system may be further configured to use the selected at least one receiver to estimate at least one characteristic of at least one of the user's blood vessels, representing at least a portion thereof. At least one characteristic of the one or more blood vessels may include pulse wave velocity (PWV), which may indicate arterial stiffness or be related to blood pressure, and / or arterial size.

[0100] In some implementations, at least one of the waveguides may be angled relative to the surface of the interface layer (e.g., as shown in the figure). Figure 4A and Figure 4E (As illustrated). In some embodiments, at least one of the waveguides may be substantially parallel to the surface of the interface layer at an angle (e.g., as shown). Figures 4B to 4E (As illustrated). In some embodiments, at least a portion of at least one of the waveguides can be embedded in the interface layer in a free-form manner (e.g., as shown). Figure 4F exemplified).

[0101] Components for performing functionality at frame 710 may include interface 201, receiver system 202 and light source system 204, waveguide system 205, control system 206 and / or such as Figure 2 Other components of the apparatus shown.

[0102] At block 720, method 700 may include receiving information from a receiver system about acoustic signals detected by the receiver system. The information about the acoustic signals may include waveforms associated with acoustic signals from each receiver element of the receiver system, processed information (e.g., intervals in the waveform), and wave parameters (e.g., wavelength, amplitude).

[0103] Components for performing functionality at block 720 may include receiver system 202 and / or, as well as... Figure 2 Other components of the apparatus shown.

[0104] At box 730, method 700 may include: determining the user's physiological parameters based on information about acoustic signals.

[0105] Components for performing the functionality at block 730 may include control system 206 and / or, for example, Figure 2 Other components of the apparatus shown.

[0106] As used in this article, the phrase “at least one of the items” refers to any combination of these items, including a single member. For example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc.

[0107] 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.

[0108] 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, 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] Some 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 functioning in certain combinations and even originally claimed in this way, in some cases, one or more features from the claimed combination may be removed from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0113] 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 this 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 appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired result.

[0114] 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.

[0115] 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 appended claims are not intended to limit them to the specific embodiments shown herein, but are to be accorded the broadest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0116] Additionally, certain features described in this specification within the context of individual embodiments may also be implemented in combination within a single embodiment. Conversely, the 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 functioning in certain combinations and even originally claimed in this way, in some cases, one or more features from the claimed combination may be removed from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0117] 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 multiple sub-operations 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 the various system components in the embodiments described above should not be construed as requiring this separation in all embodiments. Therefore, other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result.

[0118] Specific implementation examples are described in the following numbered clauses: Clause 1: A user equipment comprising: a light source system including one or more light sources; a receiver system including one or more receivers configured to detect an acoustic signal generated by a target object based on an optical signal from the one or more light sources; an interface layer accessible to a user, the interface layer comprising a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; and a waveguide system including one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the at least a portion of the user.

[0119] Clause 2: The user equipment according to Clause 1 further includes a wearable structure capable of being attached to the user and including the light source system, the receiver system, the interface layer and the waveguide system.

[0120] Clause 3: A user equipment according to any one of Clauses 1 to 2, wherein the first acoustic characteristic includes a first acoustic impedance associated with the user's skin, and the second acoustic characteristic includes a second acoustic impedance associated with the one or more receivers.

[0121] Clause 4: A user equipment according to any one of Clauses 1 to 3, wherein the first acoustic impedance is between about 1.5 and about 2.0, and the second acoustic impedance corresponds to the material of the one or more receivers.

[0122] Clause 5: A user equipment according to any one of Clauses 1 to 4, wherein the interface layer includes a mating layer having a first surface and a second surface, the first surface being contactable by the user's skin and configured to abut the user's skin, and the second surface being adjacent to the receiver system and configured to abut the receiver system.

[0123] Clause 6: User equipment according to any one of Clauses 1 to 5, wherein the mating layer comprises at least partially polyethylene.

[0124] Clause 7: A user equipment according to any one of Clauses 1 to 6, wherein the matching layer has an acoustic impedance that varies gradually between a first acoustic impedance associated with the user's skin and a second acoustic impedance associated with the one or more receivers.

[0125] Clause 8: A user equipment according to any one of Clauses 1 to 7, wherein the first surface has the first acoustic impedance and the second surface has the second acoustic impedance.

[0126] Clause 9: The user equipment according to any one of Clauses 1 to 8 further includes a control system, wherein the control system is configured to determine the user's physiological parameters based on the detected acoustic signals.

[0127] Clause 10: User equipment according to any one of Clauses 1 to 9, wherein the physiological parameter includes the user's blood pressure.

[0128] Clause 11: The user equipment according to any one of Clauses 1 to 10, the user equipment further comprising a control system, wherein: the receiver system includes a plurality of receivers, each of the plurality of receivers being configured to transmit information about a detected acoustic signal to the control system; and the control system being configured to select at least one of the plurality of receivers based on corresponding information about the detected acoustic signal received from the plurality of receivers.

[0129] Clause 12: A user equipment according to any one of Clauses 1 to 11, wherein the control system is further configured to use at least one selected receiver of the plurality of receivers to estimate at least one characteristic of the target object, the target object comprising one or more blood vessels of at least a portion of the user.

[0130] Clause 13: User equipment according to any one of Clauses 1 to 12, wherein at least one of the one or more waveguides is angled relative to the surface of the interface layer.

[0131] Clause 14: User equipment according to any one of Clauses 1 to 13, wherein at least one of the one or more waveguides is substantially parallel to the surface of the interface layer at an angle.

[0132] Clause 15: A user equipment according to any one of Clauses 1 to 14, wherein the light source system is disposed at a first portion of the user equipment, and at least one of the one or more receivers is disposed at a second portion of the user equipment; the first portion and the second portion are positioned such that when the user wears the user equipment, at least one portion of the user resides between the first portion and the second portion; and at least one of the one or more waveguides is configured to provide light from the first portion of the user equipment toward the second portion.

[0133] Clause 16: A method for monitoring a user's physiological parameters using a photoacoustic device, the method comprising: transmitting an optical signal via one or more waveguides from a light source system of the photoacoustic device toward a portion of a receiver system of the user proximate to the photoacoustic device, the receiver system being disposed remotely from the light source system and not in direct contact with the light source system, the photoacoustic device comprising: the light source system including one or more light sources; the receiver system including one or more receivers configured to detect an acoustic signal generated by a target object based on the optical signal from the one or more light sources; and an interface layer accessible to the user, the interface layer comprising a component configured to... A flexible material conforming to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; and a waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the at least a portion of the user; receiving information from the receiver system regarding the acoustic signal detected by the one or more receivers; and determining the user's physiological parameters based on the information regarding the acoustic signal.

[0134] Clause 17: The method according to Clause 16, wherein the photoacoustic device further includes a wearable structure capable of being attached to the user and includes the light source system, the receiver system, the interface layer, and the waveguide system.

[0135] Clause 18: The method according to any one of Clauses 16 to 17, wherein the first acoustic characteristic includes a first acoustic impedance associated with the user's skin, and the second acoustic characteristic includes a second acoustic impedance associated with the one or more receivers.

[0136] Clause 19: The method according to any one of Clauses 16 to 18, wherein the first acoustic impedance is between about 1.5 and about 2.0, and the second acoustic impedance corresponds to the material of the one or more receivers.

[0137] Clause 20: The method according to any one of Clauses 16 to 19, wherein the interface layer includes a mating layer having a first surface and a second surface, the first surface being contactable by the user's skin and configured to abut the user's skin, and the second surface being adjacent to the receiver system and configured to abut the receiver system.

[0138] Clause 21: The method according to any one of Clauses 16 to 20, wherein the matching layer comprises at least partially polyethylene.

[0139] Clause 22: The method according to any one of Clauses 16 to 21, wherein the matching layer has an acoustic impedance that varies gradually between a first acoustic impedance associated with the user's skin and a second acoustic impedance associated with the one or more receivers.

[0140] Clause 23: The method according to any one of Clauses 16 to 22, wherein the photoacoustic device further includes a control system configured to determine the user's physiological parameters based on the detected acoustic signals.

[0141] Clause 24: The method according to any one of Clauses 16 to 23, wherein the physiological parameter includes the user's blood pressure.

[0142] Clause 25: The method according to any one of Clauses 16 to 24, wherein the photoacoustic device further comprises a control system, wherein: the receiver system comprises a plurality of receivers, each of the plurality of receivers being configured to transmit information about a detected acoustic signal to the control system; and the control system is configured to: select at least one of the plurality of receivers based on corresponding information received from the plurality of receivers about the detected acoustic signal; and use the selected at least one of the plurality of receivers to estimate at least one characteristic of the target object, the target object comprising one or more blood vessels of at least a portion of the user.

[0143] Clause 26: The method according to any one of Clauses 16 to 25, wherein at least one of the one or more waveguides is angled relative to the surface of the interface layer, or is angled substantially parallel to the surface of the interface layer.

[0144] Clause 27: An apparatus comprising: a light source component for transmitting light, the light source component including one or more light sources; a receiver component for detecting an acoustic signal generated by a target object based on the light signal from the light source component, the receiver component including one or more receiver elements; an interface component accessible to a user, the interface component comprising a flexible material configured to conform to at least a portion of the user and adjacent to the receiver component, the interface component having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the receiver component; and a waveguide component for transmitting the light signal from the one or more light sources to the at least a portion of the user, the waveguide component including one or more waveguides at least partially embedded in the interface component.

[0145] Clause 28: The apparatus according to Clause 27, wherein: the interface component includes a mating layer having a first surface and a second surface, the first surface being contactable by the user's skin and configured to abut the user's skin, the second surface being adjacent to the receiver component and configured to abut the receiver component; and the first acoustic characteristic includes a first acoustic impedance associated with the user's skin, and the second acoustic characteristic includes a second acoustic impedance associated with the one or more receivers, the mating layer having a graded acoustic impedance that gradually varies between the first acoustic impedance associated with the user's skin and the second acoustic impedance associated with the one or more receivers.

[0146] Clause 29: The apparatus according to any one of Clauses 27 to 28, wherein at least one of the one or more waveguides is angled relative to the surface of the interface component, or is angled substantially parallel to the surface of the interface component.

[0147] Clause 30: A non-transitory computer-readable device, the non-transitory computer-readable device comprising a storage medium including a plurality of instructions configured to, when executed by a control system, cause an optoacoustic device to: transmit an optical signal via one or more waveguides from a light source system of the optoacoustic device toward a portion of a receiver system of the optoacoustic device proximate to a user, the receiver system being disposed remotely from the light source system and not in direct contact with the light source system, the optoacoustic device comprising: the light source system including one or more light sources; the receiver system including one or more receivers configured to detect an acoustic signal generated by a target object based on the optical signal from the one or more light sources; and an interface layer, the interface layer being configured to be used to detect an acoustic signal generated by a target object based on the optical signal from the one or more light sources. The interface layer is accessible to a user, comprising a flexible material configured to conform to at least a portion of the user and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers; and a waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the at least a portion of the user; receiving information from the receiver system regarding the acoustic signal detected by the one or more receivers; and determining the user's physiological parameters based on the information regarding the acoustic signal.

Claims

1. A user equipment, the user equipment comprising: A light source system, comprising one or more light sources; A receiver system comprising one or more receivers configured to detect acoustic signals generated by a target object based on light signals from the one or more light sources; An interface layer, which can be touched by a user, comprises a flexible material configured to conform to at least a portion of the user and is adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers. and A waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the user at least a portion thereof.

2. The user equipment according to claim 1, further comprising a wearable structure, the wearable structure being attachable to the user and including the light source system, the receiver system, the interface layer, and the waveguide system.

3. The user equipment of claim 1, wherein the first acoustic characteristic includes a first acoustic impedance associated with the user's skin, and the second acoustic characteristic includes a second acoustic impedance associated with the one or more receivers.

4. The user equipment of claim 3, wherein the first acoustic impedance is between about 1.5 and about 2.0, and the second acoustic impedance corresponds to the material of the one or more receivers.

5. The user equipment of claim 3, wherein the interface layer comprises a mating layer having a first surface and a second surface, the first surface being contactable by the user's skin and configured to abut the user's skin, and the second surface being adjacent to the receiver system and configured to abut the receiver system.

6. The user equipment of claim 5, wherein the matching layer comprises at least partially polyethylene.

7. The user equipment of claim 5, wherein the matching layer has an acoustic impedance that varies gradually between a first acoustic impedance associated with the user's skin and a second acoustic impedance associated with the one or more receivers.

8. The user equipment according to claim 5, wherein: The first surface has the first acoustic impedance, and the second surface has the second acoustic impedance.

9. The user equipment of claim 1, further comprising a control system, wherein the control system is configured to determine the user's physiological parameters based on the detected acoustic signals.

10. The user equipment of claim 9, wherein the physiological parameter includes the user's blood pressure.

11. The user equipment according to claim 1, further comprising a control system, wherein: The receiver system includes a plurality of receivers, each of which is configured to transmit information about the detected acoustic signal to the control system. and The control system is configured to select at least one of the plurality of receivers based on relevant information received from the plurality of receivers regarding the detected acoustic signals.

12. The user equipment of claim 11, wherein the control system is further configured to use at least one selected receiver of the plurality of receivers to estimate at least one characteristic of the target object, the target object comprising one or more blood vessels of at least a portion of the user.

13. The user equipment of claim 1, wherein at least one of the one or more waveguides is angled relative to the surface of the interface layer.

14. The user equipment of claim 1, wherein at least one of the one or more waveguides is substantially parallel to the surface of the interface layer at an angle.

15. The user equipment according to claim 1, wherein: The light source system is disposed at a first part of the user equipment, and at least one of the one or more receivers is disposed at a second part of the user equipment; The first portion and the second portion are positioned such that when the user wears the user device, at least one portion of the user resides between the first portion and the second portion; and At least one of the one or more waveguides is configured to provide light from the first portion of the user equipment toward the second portion.

16. A method for monitoring a user's physiological parameters using a photoacoustic device, the method comprising: The photoacoustic device transmits an optical signal via one or more waveguides from a light source system towards a receiver system near a user, the receiver system being positioned away from and not in direct contact with the light source system. The light source system includes one or more light sources; The receiver system includes one or more receivers, the one or more receivers being configured to detect acoustic signals generated by a target object based on light signals from the one or more light sources; An interface layer, accessible to a user, comprising a flexible material configured to conform to at least a portion of the user's acoustic characteristics and adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the user's acoustic characteristics and a second acoustic characteristic corresponding to the one or more receivers; and A waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the user at least a portion thereof; Receive information from the receiver system regarding the acoustic signals detected by the one or more receivers; and The user's physiological parameters are determined based on the information about the acoustic signals.

17. The method of claim 16, wherein the photoacoustic device further comprises a wearable structure capable of being attached to the user and comprising the light source system, the receiver system, the interface layer, and the waveguide system.

18. The method of claim 16, wherein the first acoustic characteristic includes a first acoustic impedance associated with the user's skin, and the second acoustic characteristic includes a second acoustic impedance associated with the one or more receivers.

19. The method of claim 18, wherein the first acoustic impedance is between about 1.5 and about 2.0, and the second acoustic impedance corresponds to the material of the one or more receivers.

20. The method of claim 18, wherein the interface layer comprises a mating layer having a first surface and a second surface, the first surface being contactable by the user's skin and configured to interface with the user's skin, and the second surface being adjacent to the receiver system and configured to interface with the receiver system.

21. The method of claim 20, wherein the matching layer comprises at least partially polyethylene.

22. The method of claim 20, wherein the matching layer has an acoustic impedance that varies gradually between a first acoustic impedance associated with the user's skin and a second acoustic impedance associated with the one or more receivers.

23. The method of claim 16, wherein the photoacoustic device further comprises a control system configured to determine the user's physiological parameters based on the detected acoustic signals.

24. The method of claim 23, wherein the physiological parameter includes the user's blood pressure.

25. The method of claim 16, wherein the photoacoustic device further comprises a control system, wherein: The receiver system includes multiple receivers, each configured to transmit information about the detected acoustic signals to the control system; and The control system is configured as follows: At least one receiver among the plurality of receivers is selected based on the corresponding information received from the plurality of receivers regarding the detected acoustic signal; as well as At least one receiver selected from the plurality of receivers is used to estimate at least one characteristic of the target object, the target object comprising one or more blood vessels of at least a portion of the user.

26. The method of claim 16, wherein at least one of the one or more waveguides is angled relative to the surface of the interface layer, or is angled substantially parallel to the surface of the interface layer.

27. An apparatus comprising: A light source component for transmitting light, the light source component comprising one or more light sources; A receiver component for detecting an acoustic signal generated by a target object based on an optical signal from the light source component, the receiver component comprising one or more receiver elements; An interface component, which is accessible to a user, comprises a flexible material configured to conform to at least a portion of the user and is adjacent to the receiver component, the interface component having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the receiver component. and A waveguide component for transmitting the optical signal from the one or more light sources to the user, the waveguide component comprising one or more waveguides at least partially embedded in the interface component.

28. The apparatus according to claim 27, wherein: The interface component includes a mating layer having a first surface and a second surface, the first surface being contactable by the user's skin and configured to abut against the user's skin, and the second surface being adjacent to the receiver component and configured to abut against the receiver component; and The first acoustic characteristic includes a first acoustic impedance associated with the user's skin, and the second acoustic characteristic includes a second acoustic impedance associated with the one or more receivers, the matching layer having a graded acoustic impedance that gradually varies between the first acoustic impedance associated with the user's skin and the second acoustic impedance associated with the one or more receivers.

29. The apparatus of claim 27, wherein at least one of the one or more waveguides is angled relative to the surface of the interface component, or is angled substantially parallel to the surface of the interface component.

30. A non-transitory computer-readable device, the non-transitory computer-readable device comprising a storage medium, the storage medium comprising a plurality of instructions configured to, when executed by a control system, cause a photoacoustic device to: The photoacoustic device transmits an optical signal via one or more waveguides from a light source system towards a receiver system near a user, the receiver system being positioned away from and not in direct contact with the light source system. The light source system includes one or more light sources; The receiver system includes one or more receivers, the one or more receivers being configured to detect acoustic signals generated by a target object based on light signals from the one or more light sources; An interface layer, which can be touched by a user, comprises a flexible material configured to conform to at least a portion of the user and is adjacent to the one or more receivers, the interface layer having both a first acoustic characteristic corresponding to the acoustic characteristics of the user and a second acoustic characteristic corresponding to the acoustic characteristics of the one or more receivers. and A waveguide system comprising one or more waveguides at least partially embedded in the interface layer and configured to transmit the optical signal from the one or more light sources to the user at least a portion thereof; Receive information from the receiver system regarding the acoustic signals detected by the one or more receivers; as well as The user's physiological parameters are determined based on the information about the acoustic signals.

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