Device and system for controlling pressure during sensing

Abstract

Devices and systems for controlling pressure during sensing are disclosed herein. Such sensors and / or systems may be embodied in wearable user devices. A wearable user device may include an endless band configured to apply pressure to a portion of a user at a plurality of discrete pressure levels over a plurality of time periods; a biometric sensor configured to acquire a plurality of sensor measurements associated with a blood vessel of the user at a corresponding discrete pressure level of the plurality of discrete pressure levels during a corresponding time period of the plurality of time periods; and a wearable structure including an endless band and a biometric sensor.

Description

Related applications

[0001] This application claims the benefit of priority to U.S. Patent Application No. 18 / 478,936, filed September 29, 2023, entitled “DEVICES AND SYSTEMS FORCONTROLLING PRESSURE DURING SENSING”, which has been assigned to the assignee of this application and is incorporated herein by reference in its entirety for all purposes. Technical Field

[0002] This disclosure relates in general to devices and systems that use biometric sensors. Background Technology

[0003] Various sensing technologies and algorithms are being implemented in devices for a wide range of biometric and biomedical applications, including health and wellness monitoring. This push is partly driven by the limitations of traditional measurement devices for continuous, non-invasive, and non-bedridden monitoring. Some of these devices are or incorporate photoacoustic sensors. While some previously deployed devices provide acceptable results, improved detection devices and systems are desirable. Summary of the Invention

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

[0005] In one aspect of this disclosure, a wearable user device is disclosed. In some embodiments, the wearable user device may include: a loop configured to apply pressure to a portion of a user at multiple discrete pressure levels over multiple time periods; a biometric sensor configured to acquire multiple sensor measurements associated with a blood vessel of the user at a corresponding discrete pressure level within the multiple time periods, the multiple sensor measurements being correlated with multiple data points relating to characteristics of the user's blood vessel, the multiple data points relating to characteristics of the blood vessel enabling determination of the user's blood pressure; and a wearable structure including the loop and the biometric sensor.

[0006] In another aspect of this disclosure, a method for determining a user's physiological parameters is disclosed. In some embodiments, the method may include: acquiring one or more first sensor measurements from the user's blood vessels when the pressure applied to a portion of the user is at a first target pressure level at a first time, the one or more first sensor measurements being correlated with the first data of characteristics of the blood vessels; acquiring one or more second sensor measurements from the user's blood vessels when the pressure applied to the portion of the user is at a second target pressure level at a second time, the one or more second sensor measurements being correlated with the second data of characteristics of the blood vessels; and determining the user's physiological parameters based at least on the first data and the second data of characteristics of the blood vessels.

[0007] In another aspect of this disclosure, an apparatus is disclosed. In some embodiments, the apparatus may include: components for applying pressure to a portion of a user at multiple discrete pressure levels over multiple time periods; components for acquiring multiple sensor measurements associated with a blood vessel of the user at a corresponding discrete pressure level within a corresponding time period of the multiple time periods, the multiple sensor measurements being associated with multiple data points relating to characteristics of the user's blood vessel, the multiple data points relating to characteristics of the blood vessel enabling the determination of the user's blood pressure; and a wearable component including the components for applying the pressure to the portion of the user and the components for acquiring the multiple sensor measurements.

[0008] In another aspect of this disclosure, 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 one or more processors, cause the device to: acquire one or more first sensor measurements from the user's blood vessels when the pressure applied to a portion of the user is at a first target pressure level at a first time, the one or more first sensor measurements being correlated with the first data of characteristics of the blood vessels; acquire one or more second sensor measurements from the user's blood vessels when the pressure applied to the portion of the user is at a second target pressure level at a second time, the one or more second sensor measurements being correlated with the second data of characteristics of the blood vessels; and determine the user's physiological parameter based at least on the first data and the second data of characteristics of the blood vessels.

[0009] 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

[0010] FIG. 1 An example of a blood pressure monitoring device based on photoacoustic volume plethysmography (PAPG) is shown.

[0011] FIG. 2 This is a block diagram illustrating example components of a sensor device according to some disclosed specific implementations.

[0012] FIG. 3 An example of a blood pressure monitoring device based on photoplethysmography (PPG) is shown.

[0013] FIG. 4 Examples of heart rate waveform (HRW) features that can be extracted according to some specific implementations are shown.

[0014] FIG. 5A An example monitoring device designed to be worn around the wrist is shown according to some specific implementations.

[0015] FIG. 5B An example monitoring device designed to be worn on a finger is shown according to some specific implementations.

[0016] FIG. 5C An example monitoring device designed to reside on an earbud-type headphone is shown according to some specific implementations.

[0017] FIG. 6 This is a block diagram of an example sensor device based on some implementation schemes.

[0018] FIG. 7 A cross-sectional view depicts an example structure of a sensor device that can be used with some implementation schemes.

[0019] FIG. 8 Example pressure versus flow rate curves are shown at different voltages applied to the pump of the sensor device disclosed herein.

[0020] FIG. 9 This is a graph showing an example of stepped pressure levels that can be applied using the sensor devices disclosed herein.

[0021] FIG. 9A This is another example of a graph showing the stepped pressure levels that can be applied using the sensor devices disclosed herein.

[0022] FIG. 10 This is a block diagram of an example sensor device based on some implementation schemes.

[0023] FIG. 11 This is a block diagram of another example sensor device according to some implementation schemes.

[0024] FIG. 11AAn example of a membership function applied by a fuzzer is shown, which is useful for utilizing... FIG. 11 The example sensor device is useful for implementing fuzzy logic.

[0025] FIG. 11B A simplified block diagram illustrating how fuzzy logic receives target information and feedback information and generates control signals is shown.

[0026] FIG. 11C This is a block diagram of a proportional-integral-derivative (PID) controller in a feedback loop, which is for... FIG. 11 The example sensor device is useful.

[0027] FIG. 12 This is a block diagram of an example sensor device using fuzzy logic and a PID controller, based on some implementation schemes.

[0028] FIG. 13 The graph shows how the applied pressure and current consumption change with voltage.

[0029] FIG. 14 It is a graph showing a set of example data points of pulse wave velocity (PWV) varying with applied external pressure according to some implementation schemes.

[0030] FIG. 15 It is a flowchart of a method for determining a user's physiological parameters based on some publicly disclosed implementation schemes.

[0031] FIG. 16 This is a flowchart of another method for determining a user's physiological parameters, based on some publicly disclosed implementation schemes.

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

[0033] The following description is directed to certain implementations and is intended to describe various aspects of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in a variety of 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 implementations are also applicable to other types of biosensing applications, as well as other fluid flow systems. The described specific implementations can be implemented in any device, apparatus, or system that includes the means disclosed herein. Furthermore, it is contemplated that the described specific implementations may be included in or associated with a variety of electronic devices, such as, but not limited to: mobile phones, cellular phones with multimedia-enabled networks, mobile TV receivers, wireless devices, smartphones, smart cards, wearable devices (such as wristbands, armbands, wrist straps, rings, headbands, patches, chest straps, anklets, etc.), Bluetooth. ®Devices, personal data assistants (PDAs), wireless email receivers, handheld or portable computers, laptops, notebook computers, smart e-books, tablet computers, printers, copiers, scanners, fax machines, GPS receivers / navigators, cameras, digital media players, game consoles, wristwatches, clocks, computers, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), mobile health devices, computer monitors, automotive displays (including odometer and speedometer displays, etc.), cockpit controls and / or displays, camera view displays (such as displays for vehicle rearview cameras), building structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washing machines, dryers, washer / dryer units, parking meters, car doors, Internet of Things (IoT) devices, etc. Therefore, this teaching is not intended to be limited to the specific specific implementations depicted and described with reference to the accompanying drawings; rather, its broad applicability will be apparent to those skilled in the art.

[0034] There is an urgent need in clinical and consumer applications for accurate, non-invasive, and continuously monitoring wearable devices, such as those for measuring physiological parameters like a user's blood pressure. Specifically, non-invasive blood pressure monitoring is desired. Continuous blood pressure monitoring opens pathways for the efficient and effective diagnosis and treatment of cardiovascular diseases (e.g., hypertension), cardiovascular event detection, and stress monitoring. This also allows for daily spot checks of cardiovascular diseases, including blood pressure, as well as overnight sleep monitoring. A positive user experience during overnight sleep monitoring is desired. For example, the user should experience minimal discomfort during the operation of the wearable device, including during sleep.

[0035] Sensing mechanisms that allow for the efficient collection of biometric measurements (photoacoustic, optical, etc.) and measurements of physiological characteristics (pulse wave velocity (PWV) of blood vessels, user's blood pressure) could be a step in this direction. Existing band-based blood pressure measurement methods (such as oscilloscopes and arterial volume clamps) require the use of a counter-pressure band and pressure control. Pulse wave analysis (PWA) using an oscilloscope determines blood pressure by inflating a band worn by the user to high pressure to cut off blood flow and gradually releasing the band pressure while the pulse wave is measured using a pressure sensor. The waveform representing arterial blood pressure is analyzed to non-invasively estimate blood pressure. Regular calibration may be required. Arterial volume clamps involve clamping an artery in the finger at a constant diameter by applying external band pressure to the finger. The clamp system may have a built-in optical (PPG) sensor, a fast pneumatic servo system (applying pulsating band pressure to the finger artery with pressure exactly opposite to that inside the artery), and a dynamic servo setpoint adjuster (for automated calibration to maintain the correct setpoint level for tracking finger blood pressure). When the band pressure equals the arterial pressure, the transmural pressure inside relative to the outside is zero. Another traditional method is intraocular tonometry, which measures arterial pressure by applying force (e.g., using a ring) to a superficial artery (e.g., the radial artery) to cause the vessel to twist, and the probe displacement caused by the arterial pulsation is considered proportional to the intra-arterial pressure. This method is prone to error and requires ring calibration.

[0036] Photoacoustic measurements provide valuable data for determining vascular characteristics. For example, artery size can be determined based on photoacoustic measurements, and artery size can be used to determine the pulse wave velocity (PWV) of the vessel. PWV varies with arterial wall stiffness and tension, blood density, body posture, blood pressure, etc. Therefore, PWV is a relevant characteristic of interest because human biometrics and physiological parameters, such as blood pressure, are correlated with PWV. Accurate and flexible PWV measurements, which can be conveniently and efficiently acquired (e.g., using a single device or system), along with other information such as artery diameter and dilation, are valuable for continuous and non-invasive tracking of biometrics and physiological parameters. Therefore, accurate and convenient acquisition of such information is valuable for blood pressure estimation, including as a wearable device.

[0037] Wearable devices configured to apply pressure using a loop system require small pumps that operate quietly and electrically efficiently. For this reason, piezoelectric transducer pumps can be used due to their simple structure, low power requirements, and ability to operate in the range of ultrasonic frequencies inaudible to the human ear. Advantageously, pressure feedback from the loop system (ideally located close to the photoacoustic sensor) allows for precise and automatic control of the target pressure to enhance the user experience (e.g., supporting overnight sleep monitoring, including remotely), without requiring pressure calibration.

[0038] However, various problems can arise when using a pump to operate the device. One problem is noise. The airbag or bladder inflates and deflates to apply pressure. The airbag is inflated by air when power is applied to the pump and deflates when power is removed from the pump. In some cases, the pump may not be designed to maintain the pressure at the constant (or substantially constant) pressure value required for accurate photoacoustic and PWV measurements. The target pressure may drop when power to the pump is turned off, so maintaining the pressure may require intermittent or frequent inflation. Inflation and deflation contribute to noise. Furthermore, although the pump can operate in the ultrasonic frequency range, it may still cause audible noise due to nonlinear ultrasonic effects (the propagation of ultrasound is nonlinear) or mechanical noise coupled through the structure. The device may include and operate other sensors, such as photoacoustic sensors sensitive to sound and noise, microphones, etc. Therefore, it is desirable to avoid or mitigate the noise generated during pump operation while acquiring photoacoustic (or other acoustic, e.g., microphone) sensor measurements, and maintaining the target pressure in the airbag.

[0039] Another issue is that pressure is sensitive to temperature and altitude. For example, for every 30 seconds of continuous pump operation, the temperature of the air inside the gas bag rises by 10 degrees Celsius. As noted above, accurate photoacoustic and PWV measurements may require a substantially constant pressure level. This natural temperature rise from operating the pump alters the pressure and adversely affects the measurements.

[0040] Although applying a pulse-width modulation (PWM) voltage to the pump can maintain the bag pressure at the target value, audible sounds can still be heard from the movement of passive valves (e.g., the passive movement of a check valve). The sound frequency depends on the PWM frequency. Pressure may also exhibit a chain reaction from continuous inflation (electrically on) or deflation (electrically off).

[0041] The added problem is that piezoelectric transducer pumps are difficult to control precisely due to the inherent nonlinear and hysteretic behavior of piezoelectric materials. The air pressure established by the pump driver via a voltage calibrated based on specific temperature and altitude can result in pressures exceeding or falling below the target pressure. The actual target pressure can also change due to variations in temperature and altitude.

[0042] To address the aforementioned problems, the sensor device embodiments disclosed herein provide various mechanisms for acquiring accurate sensor measurements while avoiding noise and pressure variations. In some embodiments, discrete pressure levels are applied externally to the user using or wearing the band via an air bladder or pouch of the band. Precise discrete pressure levels can be applied based on the voltage level applied to the pump, causing the air bladder to inflate when the vent is closed. To deflate, the vent can be opened when the pressure is below the target pressure level, and / or the pump can increase the pressure to the target level. During sensor measurements, each discrete pressure level can be maintained independently for a period of time. In particular, photoacoustic sensors can operate with almost no noise during this time because the pressure is maintained at the target pressure level through the closed vent, and there is no mechanical or acoustic interference from pump operation, airflow, deflation, etc.

[0043] Additionally, the embodiments disclosed herein can use a feedback loop to maintain the pressure level at a target pressure level. If the current pressure is below or above the expected target pressure level (whether due to temperature or altitude, prolonged operation of the sensor device, or any other reason), feedback information (e.g., pressure, voltage) from the pressure sensor of the sensor device can be compared with the target information (e.g., pressure, voltage). Depending on the specific implementation, fuzzy logic, neural networks, and / or PID (proportional-integral-derivative) controllers can be used to determine whether to correct the deviated pressure and to determine the appropriate voltage for the pump or the control signal for the vent.

[0044] Finally, photoacoustic measurements at the corresponding pressure level (and therefore PWV) provide data that can be used to estimate the user's physiological parameters (e.g., blood pressure). In some implementations, predictive machine learning or artificial intelligence models can be trained to predict blood pressure. In some implementations, predictive models can be trained to output control signals (e.g., voltages indicating the pressure level to be applied for correction). Furthermore, some or all of the sensor-based measurements can be retained or discarded based on any inconsistency between the sensor-based estimates and the model-generated predictions.

[0045] Specific embodiments of the subject matter described herein can be implemented to achieve one or more of the following potential advantages. Performing photoacoustic, acoustic (e.g., microphone), or other noise-sensitive biometric measurements at discrete pressure levels when the noise source is not operating results in clean information that is less prone to errors, outliers, etc. The methods described herein can lead to information for estimating parameters such as blood pressure, thereby promoting higher accuracy for monitoring devices that are also non-invasive and capable of continuous measurement (including during sleep). The collected data is also compatible with machine learning or deep learning implementations, where the data can be used as input to machine learning or artificial intelligence models and further improve the accuracy of blood pressure measurements.

[0046] Additional details will follow the initial description of the relevant systems and technologies.

[0047] FIG. 1 An example of a blood pressure monitoring device based on photoacoustic volume plethysmography (referred to herein as PAPG) is shown. FIG. 1 The same example of arteries, veins, arterioles, venules, and capillaries within a body part (in this example, finger 115) is shown. In some examples, FIG. 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 openings can also be connected to openings in interfaces that can contact body parts. 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, infrared, and / or near-infrared (NIR) light) that has penetrated the tissue of finger 115 in the illuminated area.

[0048] exist FIG. 1 In the example shown, the blood vessels (and components of the blood itself) are heated by incident light from a light source and emit 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 acoustic receiver. In some embodiments, the acoustic receiver may be an ultrasound receiver, which in this example is a piezoelectric receiver. The photoacoustic emission 102 from the illuminated tissue detected by the acoustic receiver can be used to detect changes in blood volume in the illuminated area of ​​the finger 115, corresponding to physiological data within the illuminated tissue of the finger 115, such as heart rate waveforms. Although some tissue areas shown as illuminated are offset from the tissue areas shown as generating photoacoustic emission 102, this is merely for illustrative purposes. It should be understood that the illuminated tissue is actually the tissue that generates 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 illumination level.

[0049] Optical technologies (such as systems based on photoplethysmography (PPG)) and FIG. 1 One important difference between PAPG-based methods is that FIG. 1 The sound waves shown travel much slower than the reflected light waves involved in PPG. Therefore, FIG. 1 The depth discrimination based on sound wave arrival time shown is feasible, while depth discrimination based on light wave arrival time in PPG may not be feasible. This depth discrimination allows some of the disclosed specific implementations to isolate sound waves received from different blood vessels.

[0050] Based on some examples of this, such 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 using the depth discrimination-based PAPG method can be substantially more accurate than blood pressure estimation using the PPG-based method.

[0051] FIG. 2 This is a block diagram illustrating example components of a sensor device 200 according to some specific embodiments. In this example, the sensor device 200 includes an interface 201, a receiver system 202, a light source system 204, and a ring system 205. In some cases, the waveguide system may be included as a separate component of the sensor device 200, or in some cases, it may be part of the light source system 204. Some specific embodiments of the sensor device 200 may include a control system 206, an interface system 208, a noise reduction system 210, a biometric sensor 212, or combinations thereof.

[0052] This document discloses various examples of interface 201 and various configurations of receiver system 202 and light source system 204. Some examples are described in more detail below.

[0053] In some embodiments, interface 201, receiver system 202, and light source system 204 may be components of a photoacoustic (PAPG) sensor of sensor device 200. That is, in some embodiments, sensor device 200 may include a photoacoustic sensor and a loop system 205. In the various specific embodiments described herein, the photoacoustic sensor and / or its components may operate in conjunction with the loop system 205, for example, to time the acquisition of photoacoustic measurements relative to the operation of the loop system 205. Example configurations of example components of sensor device 200 will be described in more detail below.

[0054] Some of the PAPG sensors disclosed herein may include a platform, a light source system, and an ultrasonic receiver system. According to some embodiments, the light source system may include a light source configured to generate and direct light. In some embodiments, the platform may include an anti-reflective layer, a mirror layer, or a combination thereof. According to some embodiments, the platform may have an outer surface or a layer on the outer surface having an acoustic impedance configured to approximate the acoustic impedance of human skin. In some embodiments, the platform may have a surface adjacent to the ultrasonic receiver system, or a layer on the surface adjacent to the ultrasonic receiver system, having an acoustic impedance configured to approximate the acoustic impedance of the ultrasonic receiver system.

[0055] Some of the PAPG sensors disclosed herein may include an interface, a light source system, and an ultrasonic receiver system. Some such devices may not include a rigid platform. According to some embodiments, the interface may be a physical, flexible interface constructed from one or more suitable materials having one or more desired properties, such as acoustic impedance, acoustic properties like the softness of the material. In some embodiments, the interface may be a flexible interface accessible to a target object that may approach or contact the interface. Such interfaces may differ significantly from platforms. In some embodiments, the light source system may be configured to guide light using one or more optical waveguides (e.g., optical fibers) configured to direct light toward the target object. According to some embodiments, the interface may have an outer surface or a layer on the outer surface having an acoustic impedance configured to approximate the acoustic impedance of human skin. Such an outer surface may have a contact portion accessible to 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 direct light transmitted by the optical waveguide toward tissue very close to it. The outer surface and / or other portions of the interface may be compliant, flexible, adaptable, 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 ultrasonic receiver system, or a layer on the surface adjacent to the ultrasonic receiver system, having an acoustic impedance configured to approximate the acoustic impedance of the ultrasonic receiver system.

[0056] In some specific implementations of receiver system 202, including an ultrasonic receiver system, interface 201 may be configured to connect to a user's body part (such as...). FIG. 1 The interface of the contact portion that the finger 115 (shown) contacts.

[0057] In some embodiments, the light source system 204 may include one or more light sources. In some embodiments, 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 204 may include one or more neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers.

[0058] Therefore, the light source system 204 may include, for example, an array of laser diodes, light-emitting diodes (LEDs), or either or both. The light source system 204 may be configured to generate and emit optical signals. In some examples, the light source system 204 may be configured to emit light within one or more wavelength ranges. In some examples, the light source system 204 may be configured to emit light in the 500 nanometer (nm) to 600 nanometer (nm) wavelength range. According to some examples, the light source system 204 may be configured to emit light in the 800 nm to 950 nm wavelength range. According to some examples, the light source system 204 may be configured to emit light in the infrared or near-infrared (NIR) region of the electromagnetic spectrum (approximately 700 nm to 2500 nm). Given factors such as skin reflectivity, flux, absorption coefficients of blood and various tissues, and skin safety limitations, one or both of these wavelength ranges may be suitable for a variety of applications. For example, wavelength ranges of 500 nm to 600 nm and 800 nm to 950 nm are suitable for obtaining photoacoustic responses from relatively small, shallow blood vessels, such as those found in a finger with a diameter of approximately 0.5 mm and a depth in the range of 0.5 mm to 1.5 mm. Wavelength ranges of 800 nm to 950 nm, or approximately 700 nm to 900 nm, or approximately 600 nm to 1100 nm are suitable, for example, for obtaining photoacoustic responses from relatively large, deep blood vessels, such as those found in an adult wrist with a diameter of approximately 2.0 mm and a depth in the range of 2 mm to 3 mm. In some specific embodiments, the light source system 204 may be configured, for example, to switch wavelengths based on signals from the control system 206 to capture acoustic information from different depths.

[0059] 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, since heme 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 heme. However, in some examples, the control system 206 can control the wavelength of the light emitted by the light source system 204 to preferentially sense acoustic waves in blood vessels, other soft tissues, and / or bones. For example, an infrared (IR) light-emitting diode (LED) can be selected, and short pulses of IR light can be emitted to illuminate a portion of a target object and generate acoustic emission, which is then detected by the receiver system 202. In another example, IR LEDs and red LEDs or other colors, such as green, blue, white, or ultraviolet (UV), can be selected, and short pulses of light can be emitted sequentially from each light source, wherein an ultrasound image is obtained after each light source emits light. In other embodiments, one or more light sources of different wavelengths can be lit sequentially or simultaneously to generate acoustic emission detectable by an ultrasound receiver. Image data acquired from an ultrasound receiver using light sources of different wavelengths and at different depths (e.g., varying distance gate delay (RGD)) within a target object can be combined to determine the location and type of material within the target object. Image contrast is possible because materials in a subject typically absorb light of different wavelengths differently. When materials in a subject absorb light of a specific wavelength, they may heat up differently and generate acoustic emission of light pulses with sufficient intensity and shortness. Depth contrast can be obtained using light of different wavelengths and / or intensities at each selected wavelength. That is, continuous images can be obtained at a fixed RGD (which may correspond to a fixed depth of the target object) using varying light intensities and wavelengths to detect material and its location within the target object. For example, hemoglobin, blood glucose, or blood oxygen within blood vessels in a target object such as a finger can be detected photoacously.

[0060] 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 204 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 can 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 achieving accumulation of the received ultrasonic waves and a higher resulting signal strength. In some embodiments, filtered light or a light source with a specific wavelength used to detect the selected material may be included in the light source system 204. In some embodiments, the light source system 204 may include a light source such as red, green, and blue LEDs of a display, which may be enhanced by light sources of other wavelengths (such as IR and / or UV) and higher optical power. For example, high-power laser diodes or electronic flash units (e.g., LED or xenon flash units) with or without filters may be used for short-term illumination of the target object.

[0061] According to some examples, the light source system 204 may also include one or more light guiding elements configured to guide light from the light source system 204 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.

[0062] In various configurations, the light source system 204 may incorporate an anti-reflective (AR) coating, a mirror, a light-blocking layer, a shield to minimize crosstalk, etc.

[0063] 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 may generate 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 driving circuitry) configured to cause the light source system 204 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 204 to emit light pulses at pulse repetition frequencies ranging from 1 kHz to 100 kHz.

[0064] In some example implementations, some or all of the light sources of the light source system 204 may be positioned or along an axis parallel to or at an angle to the central axis associated with the platform or interface 201. Optical signals may be emitted toward a target object (e.g., a blood vessel), causing the target object to generate ultrasound waves. Such ultrasound waves may be detected by one or more receiver elements of the receiver system 202.

[0065] Various examples of receiver system 202 disclosed herein may include acoustic receiver systems (e.g., ultrasonic receiver systems), optical receiver systems, or combinations thereof. In some embodiments, receiver system 202 includes an ultrasonic receiver system having one or more receiver elements. In embodiments including an ultrasonic receiver system, 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 act 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 array of PMUTs, or CMUT elements in a monolayer array of CMUTs may be used as both an ultrasonic transmitter and an ultrasonic receiver. According to some examples, receiver system 202 may be or may include an array of ultrasonic receivers. In some examples, sensor device 200 may include one or more separate ultrasonic transmitter elements or an array of one or more separate ultrasonic transmitter elements. In some examples, the ultrasonic transmitter may include an ultrasonic plane wave generator.

[0066] In some embodiments, at least a portion of the sensor 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, light-reflecting materials, or combinations thereof. In some examples, the sound-insulating material may reside between at least a portion of the light source system 204 and the receiver system 202. In some examples, at least a portion of the sensor device 200 (e.g., receiver system 202, light source system 204, or both) 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 the receiver system 202 from the light source system 204.

[0067] In some embodiments, sensor device 200 may include loop system 205. In some specific embodiments, loop system 205 may include a pump, airbag, and / or pressure sensor. Further components of loop system 205 may include vents, pump drivers, controllers, printed circuit boards, temperature sensors, memory, processors, valves, nozzles, tubing, power sources or batteries, physical structures (e.g., wearable structures, housings, loops), or combinations thereof.

[0068] A pump can be configured to allow air to flow into an airbag to create positive pressure within the airbag. The airbag can be constructed as an air bag pressurized by the air contained therein. In some configurations, a pump driver (including, for example, circuitry, logic, or a processor) controls the pump and allows air to flow into the airbag. A voltage can be applied to the pump via the pump driver or a controller to control the airflow. In some implementations, the pressure caused by the air can be kept constant over a period of time. Such pressure can be changed incrementally by adjusting the voltage level. Thus, an external pressure can be applied and maintained at discrete pressure levels. The vent can also be controlled by a controller to allow air to escape from the airbag, which reduces the pressure. A pressure sensor can be used to detect the pressure within the airbag, resulting in pressure data used for the operations described herein. The pressure can be adjusted to a specified level based on the detected pressure. The components of the ring system 205 will be discussed in more detail below in conjunction with system implementation schemes.

[0069] 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, sensor device 200 may have a memory system including one or more memory devices, but... FIG. 2The 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 sensor 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.

[0070] In some examples, control system 206 may be communicatively coupled to light source system 204 and configured to control the light source system to emit light toward a target object on the outer surface of interface 201. In some such examples, control system 206 may be configured to receive from an ultrasound receiver system (including one or more receiver elements) a signal corresponding to ultrasound waves generated by the target object in response to light from the light source system. In some examples, 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 vascular 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 the arteries of the target object, and one or more venous blood signals corresponding to ultrasound waves generated by blood within the veins of the target object. In some examples, 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 a combination thereof. According to some examples, the physiological parameter may be or may include blood pressure. In some methods, blood pressure can be estimated at least in part based on PWV, as will be discussed below.

[0071] In some examples, control system 206 may be communicatively coupled to receiver system 202. Receiver system 202 may be configured to detect acoustic signals from a target object. 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 (based on, for example, signal-to-noise ratio (SNR)) may be relatively higher than some other signals or higher than a predetermined threshold or percentile that 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 (PWV), arterial size, or both, based on information about the detected acoustic signals.

[0072] Some specific implementations of sensor device 200 may include interface system 208. In some examples, interface system 208 may include a wireless interface system. In some specific implementations, 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. According to some examples where interface system 208 is present and includes a user interface system, the user interface system may include a microphone system, a speaker system, a haptic feedback system, a voice command system, one or more displays, or combinations thereof. According to some examples, interface system 208 may include a touch sensor system, a gesture sensor system, or combinations thereof. The touch sensor system (if present) may be or may include a resistive touch sensor system, a surface capacitive touch sensor system, a projected capacitive touch sensor system, a surface acoustic wave touch sensor system, an infrared touch sensor system, any other suitable type of touch sensor system, or combinations thereof.

[0073] In some examples, interface system 208 may include a force sensor system. The force sensor system (if present) may be or may include a piezoresistive sensor, a capacitive sensor, a thin-film sensor (e.g., a polymer-based thin-film sensor), another suitable type of force sensor, or a combination thereof. If the force sensor system includes a piezoresistive sensor, the piezoresistive sensor may include silicon, metal, polycrystalline silicon, glass, or a combination thereof. In some embodiments, the ultrasonic fingerprint sensor and the force sensor system may be mechanically coupled. In some embodiments, the force sensor system may be mechanically coupled to a platform. 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.

[0074] According to some examples, sensor 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, light-reflecting materials, or combinations thereof. In some examples, noise reduction system 210 may include sound-insulating materials that may reside between, on, or in combination with at least a portion of 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 the receiver system from circuitry of the light source system, receiver system circuitry, or combinations thereof.

[0075] In some embodiments, sensor device 200 may be a wearable device configured to be worn by a user around, for example, the wrist, fingers, arm, leg, ankle, or another limb, or another part of the body. In an example specific embodiment, sensor device 200 may have the form of a watch and be worn around the wrist. A loop system 205 may apply pressure around the wrist while the skin at the wrist contacts via interface 201, and photoacoustic measurements can be performed by manipulating the properties of receiver system 202 and light source system 204. However, the embodiments described herein are not so limited. In some cases, not all components of sensor device 200 may be worn. For example, loop system 205 may be worn around a limb (similar to a blood pressure monitor), but other components (such as receiver system 202 and light source system 204) may be in a separate PAPG sensor assembly and / or not in a wearable housing to collect photoacoustic measurements.

[0076] In some implementations, the photoacoustic sensor and / or components thereof may operate in conjunction with at least one biometric sensor 212. An example of the biometric sensor 212 may be an optical sensor, such as one configured to operate according to the following description relative to... FIG. 3 The described principle operates as an optical volumetric plethysmography (PPG) sensor. Additionally or alternatively, the biometric sensor 212 may include an ultrasonic sensor (e.g., an ultrasonic transmitter and receiver) or other acoustic sensors (e.g., a microphone), a speckle volumetric plethysmography (SPG) sensor, and / or an electrocardiogram (EKG) electrode or sensor. In fact, any desired type of biometric sensor can be used. In many specific embodiments, the biometric sensor may have contact with the skin (which may occur via interface 201) to obtain consistent and useful sensor data. Strictly speaking, the photoacoustic sensor (including interface 201, receiver system 202, and light source system 204) may also be referred to as a biometric sensor. However, the biometric sensor 212 may optionally provide additional sensing modalities, such as PPG. Such a biometric sensor 212 may or may not be used in conjunction with the ring system 205.

[0077] FIG. 3 An example of a blood pressure monitoring device based on photoplethysmography (PPG) is shown. FIG. 3 Examples of arteries, veins, arterioles, venules, and capillaries of the circulatory system are shown, including those inside the finger 115. FIG. 3 In the example shown, an electrocardiogram (EKG) sensor has detected a proximal arterial pulse near heart 316. The following describes some examples of measuring arterial pulse transit time (PTT) based on arterial pulses measured by two sensors; in some implementations, one of these sensors may be an electrocardiogram sensor.

[0078] according to FIG. 3 The example shown includes a light source, such as one or more lasers or light-emitting diodes (LEDs), that emits light (in some examples, green, red, infrared, and / or near-infrared (NIR) light) that has penetrated the tissue of the finger 115 in the illuminated area. The reflection from such tissue, detected by a photodetector, can be used to detect changes in blood volume in the illuminated area of ​​the finger 115 corresponding to a heart rate waveform.

[0079] like FIG. 3 As shown in heart rate waveform 318, microvascular heart rate waveform 319 has a different shape and phase shift compared to arterial heart rate waveform 317. In this simplified example, the detected heart rate waveform 321 is a combination of microvascular heart rate waveform 319 and arterial heart rate waveform 317. In some instances, the response of one or more other vessels may also be a portion of heart rate waveform 321 detected by a PPG-based blood pressure monitoring device.

[0080] FIG. 4 Examples of heart rate waveform (HRW) features that can be extracted according to some specific implementations are shown. FIG. 4 The horizontal axis represents time, and the vertical axis represents signal amplitude. The cardiac cycle is indicated by the time between adjacent peaks of the HRW. The systolic and diastolic time interval is indicated below the horizontal axis. During the systolic phase of cardiac circulation, as the pulse travels along the artery through a specific location, the arterial wall expands according to the pulse waveform and the elastic properties of the arterial wall. Accompanying this expansion is a corresponding increase in blood volume at the specific location or region, and with the increase in blood volume, one or more properties in that region change accordingly. Conversely, during the diastolic phase of cardiac circulation, blood pressure in the artery decreases and the arterial wall constricts. Accompanying this constriction is a corresponding decrease in blood volume at the specific location, and with the decrease in blood volume, one or more properties in that region change accordingly.

[0081] FIG. 4 The HRW features illustrated herein relate to the width of the systolic and / or diastolic portions of the HRW curve at various “heights,” indicated by a percentage of the maximum amplitude. For example, the SW50 feature is the width of the systolic portion of the HRW curve at a “height” of 50% of the maximum amplitude. In some embodiments, the HRW features used for blood pressure estimation may include some or all of the HRW features SW10, SW25, SW33, SW50, SW66, SW75, DW10, DW25, DW33, DW50, DW66, and DW75. In other embodiments, additional HRW features may be used for blood pressure estimation. In some instances, such additional HRW features may include the superposition and ratio of SW and DW at one or more "heights," such as (DW75+SW75), DW75 / SW75, (DW66+SW66), DW66 / SW66, (DW50+SW50), DW50 / SW50, (DW33+SW33), DW33 / SW33, (DW25+SW25), DW25 / SW25, and / or (DW10+SW10), DW10 / SW10. Other implementations may use even more HRW features for blood pressure estimation. In some instances, such additional HRW features may include superposition, difference, ratio, and / or other operations based on more than one "height," such as (DW75+SW75) / (DW50+SW50), (DW50+SW50 / (DW10+SW10), etc.

[0082] In some implementations, the monitoring device can be positioned around the user's wrist as a strip or band, similar to a watch or fitness / activity tracker. FIG. 5AAn example device 500, designed to be worn around the wrist according to some specific embodiments, is shown. In some embodiments, the example device 500 may include a sensor device 200 to allow components of the sensor device 200 to interact with the user, for example, via the user's skin. In the illustrated example, the monitoring device 500 includes a housing 502 integrally formed, coupled, or otherwise integrated with a wristband 504. In some instances, a first artery sensor 506 and a second artery sensor 508 may each include an instance of the ultrasound receiver system described above and a portion of the light source system. In this example, the example device 500 is coupled around the wrist such that the first artery sensor 506 and the second artery sensor 508 within the housing 502 are each positioned along a segment of the radial artery 510 (it should be noted that when the monitoring device is coupled to an object, the sensors are typically concealed when viewed from the object-facing exterior or outer surface of the housing, but exposed on the inner surface of the housing to allow the sensors to acquire measurements from the artery beneath the object's skin). Also as shown, the first artery sensor 506 and the second artery sensor 508 are positioned at a fixed distance. D is separated. In some other specific implementations, example device 500 may be similarly designed or adapted for positioning around the forearm, upper arm, ankle, lower leg, thigh, or fingers (all of which are referred to as "limbs" below) using strips or bands.

[0083] FIG. 5B An example device 500, designed to be worn on a finger according to some specific embodiments, is shown. In some instances, the first artery sensor 506 and the second artery sensor 508 may each include an instance of the ultrasound receiver described above and a portion of a light source system.

[0084] In some other embodiments, the devices disclosed herein can be positioned on a user’s area of ​​concern without the use of strips or bands. For example, the first arterial sensor 506 and the second arterial sensor 508, along with other components of the monitoring device, can be enclosed in a housing that is secured to the user’s skin in the area of ​​concern using an adhesive or other suitable attachment mechanism (an example of a “patch” monitoring device).

[0085] FIG. 5C An example device 500, designed to reside in an earbud-type headset according to some specific embodiments, is shown. According to this example, the monitoring device 500 is coupled to the housing of an earbud 520. In some instances, a first artery sensor 506 and a second artery sensor 508 may each include an instance of the ultrasound receiver described above and a portion of a light source system.

[0086] Example sensor device As noted elsewhere, the sensor device (e.g., sensor device 200) may be worn at least partially by the user to apply pressure at different discrete pressure levels and acquire photoacoustic signals and measurements. This pressure applied by the sensor device may be referred to herein as external pressure or externally applied pressure. In some specific implementations, data segments may be collected, for example, under multiple external pressures applied by the loop system 205. For example, photoacoustic signals may be acquired by the sensor device (e.g., using receiver system 202 and light source system 204) within time periods corresponding to the external pressures. That is, photoacoustic measurements acquired for each pressure level are used to obtain information about the target object (e.g., blood vessels).

[0087] The disclosed implementation of the sensor device (configured to determine arterial diameter, dilation, PWV, etc.) benefits from precise backpressure control, but operates in a completely different manner compared to conventional volumetric clamp and oscilloscope-based methods. PWV curves can be measured because single-point PWV or PTT measurements can be unreliable due to electrical noise, motion artifacts, EKG noise, respiratory events, etc. Photoacoustic waveforms and localized PWV can be affected by backpressure applied to the artery. The PWV versus external pressure curve provides important clues to an individual's blood pressure (systolic, diastolic, and mean) and individual blood pressure calibration information.

[0088] In the embodiments disclosed herein, “closed-loop” control of pump pressure (e.g., based on feedback pressure and voltage information) can be used to more accurately control the target pressure.

[0089] FIG. 6 This is a block diagram 600 of an example sensor device according to some implementation schemes. The example sensor device may include a controller 602, a pump 604, a valve 606, an air bladder 608, a vent 610, and a pressure sensor 612, etc. In some examples, a force sensor 614 may also be included. In some embodiments, the controller 602 may be an example of a control system 206, while in other embodiments, the controller 602 may be a separate control system capable of performing functions similar to those of control system 206.

[0090] In some implementations, pump 604 may be configured to allow air to flow into airbag 608 through valve 606. Airbag 608 may be an air bladder. The amount of air entering airbag 608 may be based on a voltage applied by controller 602. For example, a constant-amplitude square wave voltage may be applied to pump 604 (or a driver of pump 604, embodied as a pump drive plate) until a certain applied pressure, such as a target pressure level, is reached. This applied pressure may generate and / or provide as output 618, which may be used, for example, as feedback information in a closed-loop system. During air inflow, vent 610 may be closed (e.g., by controller 602) to prevent air from escaping from airbag 608. Vent 610 may be opened to release air and cause airbag 608 to deflate. In some implementations, a voltage may be applied to pump 604 to establish a negative pressure and remove air from airbag 608 until a certain pressure is reached (e.g., another target level or zero applied external pressure), instead of allowing the air inside airbag 608 to become atmospheric pressure outside airbag 608 via an open valve.

[0091] When the vent 610 is closed, the pressure in the airbag 608 may be maintained or substantially maintained. Substantial maintenance of pressure may mean that the pressure is maintained within a certain range of the target pressure, such as ±1 mmHg. The tolerance range may be specific to and depend on the usage. As illustrative examples, ±2 mmHg, ±1%, ±5%, or ±10% of the target pressure may be used. In some scenarios, the pressure may change over time due to changes in temperature or altitude, or, for example, structural leakage in valve 606. In some embodiments described below, the air pressure within the airbag 608, or the pressure associated with the airbag 608, may be detected by pressure sensor 612, and the pressure information may be fed back to controller 602 as input 620. The pressure associated with the airbag 608 may be, for example, the pressure experienced by a target object (such as a blood vessel) near the user of the airbag 608. That is, for the purposes of this disclosure, the ring pressure may be the pressure on the blood vessel wall. Sensor 622 (e.g., a photoacoustic sensor) may be proximate to the component and may acquire biometric measurements while the pressure within airbag 608 is maintained or substantially maintained at a target pressure level. The biometric measurements may correspond to the target pressure level. In some cases, force sensor 614 may detect forces not associated with the air pressure within airbag 608, such as forces or pressures at the surface of airbag 608 (e.g., at the location of sensor 622). This force information may also be fed back as input 620 to controller 602. In some cases, if there is a strong correlation between the readings of pressure sensor 612 and force sensor 614, the pressure detected solely by pressure sensor 612 may be used to determine the pressure; this simplifies system design by reducing the number of sensors.

[0092] FIG. 7This is a cross-sectional view of an example structure of an example sensor device 700 that can be used with some embodiments. In some embodiments, the example sensor device 700 may include a pressure sensor 702, a sensor housing 720, and a coupling structure 730 that is communicatively coupled to a main housing 710 and / or components of the main housing 710, and at least partially secures or supports the main housing 710, the sensor housing 720, and the airbag 740. In some embodiments, the coupling structure 730 may include one or more strips, belts, or other securing mechanisms. In some embodiments, the coupling structure 730 may partially or completely accommodate the aforementioned components.

[0093] In some implementations, the example sensor device 700 may be a wearable user device, in which space may be provided for a portion 750 of the user's body, such as a limb like the wrist, fingers, arm, ankle, or leg, or other body parts that facilitate wearing, such as the waist or neck. The portion 750 (or body part) may include a target object, such as a blood vessel 752. The example sensor device 700 may be structured for directional wear with the target object (e.g., blood vessel 752) close to the sensor housing 720. In this way, the target object may be exposed to the sensor 722 or within the sensing range of the sensor 722 when the target object is active and / or when the user's skin 754 comes into contact with an interface associated with the sensor housing 720 or the sensor 722.

[0094] In some embodiments, the main housing 710 of the example sensor device 700 may include a motherboard 712, which may be a printed circuit board (PCB) having control components (e.g., logic, controller, memory, and / or memory with instructions). The main housing 710 may further include at least a portion of a pump 714 and a valve 716, the pump 714 being coupled to the valve 716, the valve 716 being mated to an airbag 740 to provide an air inlet and outlet. In some specific embodiments, the main housing 710 may further include a control board 718, which may be another PCB having control components (e.g., logic, controller, memory, and / or memory with instructions). In some specific embodiments, the control board 718 may be coupled to the motherboard 712 via a board-to-board interface 717. The main housing 710 may further include a power source, such as a battery 719. The battery 719 may power one or more components of the main housing 710, such as the pump 714, valve 716, motherboard 712, control board 718, or combinations thereof.

[0095] In some configurations, the mainboard 712 or control board 718 can generate control signals. These control signals can be configured to apply a voltage corresponding to a specified pressure level to the pump 714. More specifically, in some configurations, the DC voltage applied to the pump control circuitry during pressurization can generate a constant-amplitude square wave to drive the pump. The target pressure and airflow rate are proportional to the applied DC voltage. A passive check valve can open or close the air path at the inlet, outlet, or vent, and can remain stationary during inflation and deflation operations. Removing power from the pump opens the outlet and vent paths, causing the airbag to deflate during the deflation process.

[0096] Simple reference FIG. 8 This diagram illustrates example pressure versus flow rate curves obtained at different voltages applied to the pump of the sensor device disclosed herein. For example, the flow rate becomes zero when the pressure reaches the target pressure. Curve 802 represents the pressure relative to the flow rate at a first voltage level. Curve 804 represents the pressure relative to the flow rate at a second voltage level. Curve 806 represents the pressure relative to the flow rate at a third voltage level. Curve 808 represents the pressure relative to the flow rate at a fourth voltage level. Each linear curve represents the case where the target pressure is proportional to the air flow rate, as noted above. Furthermore, it can be seen that the pressure and flow rate can vary depending on the applied voltage. In the depicted curves, the second voltage level can be higher than the first voltage level, the third voltage level can be higher than the second voltage level, and the fourth voltage level can be higher than the third voltage level. While other voltage levels are feasible, illustrative example values ​​for such voltage levels are as follows: 8V for the first voltage level; 11V for the second voltage level; 13V for the third voltage level; and 16.5V for the fourth voltage level.

[0097] return FIG. 7 In some implementations, board-to-board interface 717 can provide a data connection to signal pump 714 via control board 718. In some embodiments, pressure sensor 702 can detect the pressure inside airbag 740. The pressure information can be provided (feedback) to control board 718 (or main board 712), which can determine the voltage to be applied to pump 714. The new pressure can then be detected by pressure sensor 702, resulting in a feedback loop of pressure sensor 702, pump 714, and airbag 740 (and / or vent for releasing air, not shown).

[0098] In some embodiments, sensor housing 720 may include sensor 722. In some configurations, sensor 722 may be a biometric sensor, such as a photoacoustic sensor. As mentioned above, the biometric sensor may additionally include other types of sensors, such as PPG sensors. In some embodiments, sensor housing 720 may also include force sensor 724. In some configurations, main housing 710 and sensor housing 720 may be electrically coupled to sensor 722 via a first bus 732 between mainboard 712 and the sensor. In some cases, the first bus 732 may be located between control board 718 and sensor 722. The first bus 732 may convey control signals configured to operate sensor 722 and / or data signals related to measurements performed by sensor 722. For example, when skin 754 of portion 750 contacts sensor housing 720 under one or more external pressure levels applied by airbag 740, the photoacoustic sensor may acquire photoacoustic data from blood vessel 752 once or multiple times. FIG. 9 As illustrated, one or more external pressure levels can be discrete pressure levels at corresponding times, where the transition portions between them resemble steps, as discussed below. This photoacoustic data can be transmitted to a motherboard 712 and / or a control board 718, where the data can be stored in memory. In some configurations, the main housing 710 and the sensor housing 720 can be electrically coupled to the motherboard 712 (or control board 718) via a second bus 734 between the force sensor 724 and the motherboard 712 (or control board 718) to exchange control signals and / or measurements performed by the force sensor 724. The first bus 732 and / or the second bus 734 can be configured to deliver power to components of the sensor housing 720.

[0099] FIG. 9 Figure 900 shows an example of a stepped pressure level applied using the sensor device disclosed herein. In this example, during time t0, the airbag or bladder may be at an initial pressure level 902, for example, an external pressure of 0 mmHg is applied. No voltage is applied to the pump associated with the airbag. The airbag may be an example of airbag 740 and is part of the ring system 205 of the sensor device 200.

[0100] During the transition portion 904 at time t1, the external pressure applied by the airbag can increase toward pressure level 906. The pressure can be increased by allowing air to flow into the airbag via a corresponding voltage applied to the pump while the vent is closed, until the pressure reaches the next pressure level 906. Pressure level 906 can be considered as the target pressure level for the duration of time t2. At the subsequent time t3, the pressure can decrease toward pressure level 910 during the transition portion 908. The pressure can be decreased by opening the vent until the pressure reaches the next pressure level 910 during time t4. In some configurations, the pressure can be decreased by applying voltage to the pump to create a negative pressure and remove air from the airbag. Similar to pressure level 906, pressure level 910 can be the target pressure level for the duration of time t4. In the example illustrated by diagram 900, external pressure levels (such as pressure levels 906 and 910) can be discrete pressure levels at corresponding times, where the transition portions between them appear as steps. Pressure levels 914 and 918 are further examples of discrete pressure levels. During the time interval t5 to t9, the pressure level can be maintained in a similar manner until the pressure returns to the initial pressure level of 902 (e.g., 0 mmHg).

[0101] Example ranges for the applied discrete external pressure levels may be 20 mmHg to 90 mmHg or 20 mmHg to 50 mmHg. Other pressure levels or ranges that the user deems comfortable may be applied, including for nighttime biometric measurements during sleep. Each discrete pressure level may be maintained at a constant or substantially constant level. That is, the pressure may have an error or range, for example, ±1 mmHg. The error range may be specific to and depend on the usage. As illustrative example values, ±2 mmHg, ±1%, ±5%, or ±10% of the target pressure may be used. An example error range for a pressure level 910 is depicted by range 911.

[0102] FIG. 9AFigure 920 is another example of a stepped pressure level that can be applied using the sensor device disclosed herein. It can be a continuation of Figure 900 ending at t4, except that the conditions may differ. For example, the temperature or altitude may differ, causing a deviation from the target pressure level. As an example, at transition portion 922 during t5, the pressure applied by the airbag decreases from the previous pressure level 910 to the target pressure level 924. However, due to lower temperatures or higher altitudes, such as when the airbag pressure increases, the pressure drop during t5 is more pronounced than the previous pressure drop during a typical transition period or a previous transition period (e.g., t3). Furthermore, the target pressure level 924 may drift downwards rather than remain constant or substantially constant, possibly again due to lower temperatures or higher altitudes. As will be discussed below, in such cases, the pressure can be detected by a pressure sensor and known by a controller or control board, which in some cases can compensate for the lower pressure and restore the pressure to the expected target pressure level (e.g., alternative pressure level 925). This change can be achieved by adjusting the pressure at time t. 6a During this period, an appropriate voltage is applied to the pump to generate pressure to reach the expected target pressure level.

[0103] During time t7, the pressure may decrease by a normal amount, as in other transition cycles. However, during time t8, pressure level 926 may increase instead of remaining constant or substantially constant. This could be due to, for example, extended pump operation, higher temperatures, or lower altitudes compared to previous periods. However, this higher pressure can be detected by pressure sensors and known to a controller or control board, which, in some cases, can compensate for the higher pressure and restore the pressure to the expected target pressure level (e.g., alternative pressure level 927). Alternative pressure levels 925, 927 may have their own corresponding transitions 935, 937, during which no noise-sensitive measurements may be performed.

[0104] In Figures 900 and 920, the goal is to maintain a discrete pressure level at a constant or substantially constant pressure level during which sensor measurements can be acquired. In some methods, in the case of photoacoustic measurements, the photoacoustic sensor may operate and acquire photoacoustic measurements only during the discrete pressure level period, and the photoacoustic sensor may not be able to acquire photoacoustic measurements during transition periods (including periods for compensating for undesired pressure changes, e.g., at time t). 6a During this period, the pump and / or valves (near the photoacoustic sensor) may generate noise during inflation and deflation, which could interfere with noise-sensitive photoacoustic measurements. Pump operation can be stopped during photoacoustic measurements while the target pressure is maintained in the bladder.

[0105] Example pressure control system A significant aspect of the sensor device discussed throughout this disclosure is its ability to provide discrete, precisely controlled target pressure levels. As elsewhere has been proposed, in some embodiments, the sensor device may include at least a photoacoustic sensor that acquires photoacoustic measurements from the target object when pressure is applied by the ring system. It is desirable that this pressure be accurate for the desired target pressure level to obtain an accurate correlation between the pressure and the measurement (and derived characteristics of the target object, such as PWV associated with blood vessels). Acquiring accurate measurements and key characteristics such as PWV allows for useful input parameters for estimating valuable parameters, such as blood pressure. To this end, various methods for controlling pressure and compensating for pressure changes are described herein.

[0106] FIG. 10 This is a block diagram of an example sensor device 1000 according to some implementation schemes. The example sensor device 1000 may be... FIG. 6 Example sensor devices or FIG. 7 This is an example of an example sensor device 700. In some embodiments, the example sensor device 1000 may include a pump 1002. The pump 1002 may be connected to an air bag 1004 (also referred to herein as an air bladder) and supply air through an air discharge port or nozzle 1003 of the pump 1002, and through an exhaust port 1005 of the pump 1002 to a vent 1006. Air may be received through an air inlet 1007 and flow into the air bag 1004 via a tube 1020 (based on a positive voltage), or the flow may be stopped (at zero voltage) based on a control signal generated by a controller 1010 of the example sensor device 1000 (providing an on / off effect to the pump 1002). The control signal may be transmitted to a pump driver 1012, which may supply the pump 1002 with a voltage corresponding to a target pressure level. In some configurations, the pump driver 1012 may be part of the pump 1002. A constant electrical current (DC voltage) may be applied to the pump 1002. In some specific embodiments, the pump driver 1012 may be an example of a control board 718. The controller 1010 can also transmit control signals to the vent 1006 to open or close during the inflation or deflation of the air bag 1004. For example, the vent 1006 can be closed when the pump 1002 is inflating the air bag 1004, and can be opened to deflate the air bag 1004. In some variations, the pump 1002 may have structural features such as an external terminal 1015.

[0107] In some implementations, example sensor device 1000 may employ a closed loop. Pressure sensor 1008 may detect the pressure of air within airbag 1004 or the pressure of air entering airbag 1004. Pressure information 1009 may be transmitted as feedback information to controller 1010. Based on the pressure information and a target pressure level (e.g., a comparison or difference between two pressures), controller 1010 may adjust the voltage supplied to pump 1002, thereby implementing the feedback loop. One objective of the feedback loop may be to minimize the difference between the feedback pressure and the target pressure. Biometric sensor 1018 (e.g., photoacoustic sensor) may be proximate to the component and may acquire biometric measurements while the pressure in airbag 1004 is maintained or substantially maintained at the target pressure level. The acquired biometric measurements may therefore correspond to the target pressure level.

[0108] Example operation involving the example sensor device 1000 may include one or more of the following: (1) the vent 1006 may be closed and the air bag 1004 may be inflated (e.g., by applying a voltage, such as a constant amplitude square wave voltage, to the pump 1002). This voltage may correspond to a target pressure level applied by the air bag 1004 to a portion of the user.

[0109] (2) When the air bag 1004 is inflated to the target pressure level (detected and output by the pressure sensor 1008), the voltage applied to the pump 1002 can be reduced to zero. The pump 1002 is off in this state. In some cases, the exhaust port 1005 to the pipe 1022 can be open. Since the vent 1006 is closed at this time and the pressure in the air bag 1004 is maintained, it can be assumed that no air is leaking from the air bag 1004.

[0110] The pressure and corresponding voltage can be correlated based on calibration performed prior to the use of the example sensor device 1000, where a predetermined relationship between pressure and voltage is established in advance. For example, pressure and voltage data can be measured and stored in a data structure such as a lookup table, list, or matrix. This predetermined relationship can be used to ensure that the pressure reaches a target pressure level accordingly. FIG. 9A An example of this type of pressure decrease and increase is shown. FIG. 8 An example voltage and corresponding airflow rate for the pressure level in airbag 1004 are shown.

[0111] (3) Sensor measurements can be performed relative to a target object, such as photoacoustic measurements from a user's blood vessels, when pump 1002 is off and air bag 1004 is at a target pressure level. In some implementations, if the pressure decreases between measurements or relative to the target pressure level, the pressure in air bag 1004 increases to the target pressure level; if the pressure increases between measurements or relative to the target pressure level, the pressure decreases to the target pressure level. Such unintended pressure increases or decreases may be caused by changes in conditions, such as temperature or altitude. For example, the temperature may have decreased and reduced the pressure, or the temperature may have increased (e.g., at least in part due to higher temperatures of the sensor device or prolonged operation). Pressure can be monitored by pressure sensor 1008 and provided as pressure information to controller 1010 at a predetermined frequency (e.g., every 0.005 seconds, 0.1 seconds, 0.5 seconds). The detection frequency may depend on the error range (e.g., ±1 mmHg).

[0112] (4) The air bag 1004 can be inflated or deflated to a new target pressure level. If the new target pressure level is greater than the current pressure level set by the previous target pressure level, power can be supplied to the pump 1002 to open it, while the vent 1006 closes until the new target pressure level is reached. If the new target pressure level is lower than the current pressure level set by the previous target pressure level, the vent 1006 can be opened until the pressure drops below the new target pressure level, and then power can be supplied to the pump 1002 to open it, while the vent 1006 closes until the new target pressure level is reached. In another method, the vent 1006 can be opened until the pressure drops directly to the previous target pressure level. While this method saves power, it may not be as accurate as dropping the pressure below the new target pressure level and then increasing it to the new target pressure level. While the air bag 1004 is being inflated or deflated, photoacoustic measurements (or other sensing modalities involving acoustic signals, such as microphones or ultrasonic receivers) may not be performed to mitigate noise interference. However, in some cases, other types of sensors can be active, such as optical sensors (e.g., PPG sensors).

[0113] Therefore, the example operation described above uses a feedback loop of pressure information (e.g., to maintain a constant or substantially constant pressure at the target pressure level of the airbag 1004) so ​​that the externally applied pressure is known, accurately measured, and correlated with the sensor measurements performed. The pressure information can indicate deviations from the target pressure level (e.g., as a result of temperature or altitude) or the difference between the current target pressure level and the next target pressure level. During pressure level changes, the example sensor device 1000 can stop performing certain measurements to avoid noise interference.

[0114] FIG. 11This is a block diagram of an example sensor device 1100 according to some implementation schemes. The example sensor device 1100 may be... FIG. 6 Example sensor devices or FIG. 7 An example of an example sensor device 700. In some embodiments, the example sensor device 1100 may include at least a pump 1102, an air bag 1104, an air exhaust port or nozzle 1103, an exhaust port 1105, a vent 1106, an air inlet 1107, a pump driver 1112, a pressure sensor 1108, structural features such as an external terminal 1115, a sensor 1118 (e.g., a photoacoustic sensor) near the assembly, and tubes 1120 and 1122. Such components may be similar to or relative to FIG. 10 Examples of their counterparts are described, and their descriptions will be omitted for brevity.

[0115] Example sensor device 1100 may include control system 1101, which includes controller 1110. Control system 1101 and / or its components may be configured to generate and transmit control signals (to provide an on / off effect to pump 1102 and / or to open or close vent 1106 during inflation or deflation of air bag 1104), similar to controller 1010. However, control system 1101 and / or controller 1110 may include additional features.

[0116] In some specific implementations, control system 1101 and / or controller 1110 may be configured to implement additional logic, such as fuzzy logic 1113. Fuzzy logic can refer to degree-based calculations rather than binary or Boolean-type true or false (1 or 0) logic. Systems using fuzzy logic with more than two levels or states may have so-called membership values ​​or so-called membership degrees in so-called fuzzy sets. Examples of fuzzy sets may be {large positive, medium positive, small, medium negative, large positive} and {definitely yes, possibly, uncertain, possibly no, definitely no}. Each member of a fuzzy set may have a membership function that increases or decreases relative to the input or variable. That is, fuzzy logic can consider states between 0 and 1 depending on the degree of the characteristic and is more closely similar to granular (human-like) reasoning. Systems implementing fuzzy logic can achieve faster responses to changes in conditions (e.g., temperature), resulting in smaller overshoot or undershoot in the response, and better overall tracking and performance because fuzzy logic can provide decisions based on a variety of inputs, whether they are imprecise, distorted, or noisy input information. Furthermore, controllers using fuzzy logic are inherently nonlinear controllers, capable of handling time-varying systems, such as... FIG. 11 and FIG. 12 The control system of the type shown.

[0117] In some methods, the output of fuzzy logic 1113 may include a voltage value provided to controller 1110 and / or a control signal for pump driver 1112 or vent 1106, which is associated with the desired pressure to be applied. The voltage value and / or control signal can indicate or adjust the current pressure level by comparing feedback information 1109 from pressure sensor 1108 with target information 1111 input to control system 1101.

[0118] FIG. 11A Examples of membership functions 1150, 1152, and 1154, useful for implementing fuzzy logic, are shown. More specifically, FIG. 11A Membership functions 1150, 1152, and 1154 applied by a trapezoidal or triangular fuzzer are shown. The first membership function 1150 can be associated with insufficient pressure, the second membership function 1152 with sufficient pressure, and the third membership function 1154 with excessive pressure. FIG. 11A In this context, membership functions 1150, 1152, and 1154 can be distinguished by the corresponding thickness of the line. Membership functions do not necessarily have peaks or linear relationships as shown; for example, in some cases, there may be varying slopes, curves, or flat areas along the function.

[0119] A system using fuzzy logic may include four components: a fuzzer (accepting input), a rule base, an inference engine, and a defuzzer (providing output). The fuzzer receives feedback information 1109 from pressure sensor 1108 as input. Based on the feedback information 1109 and the rule base, the inference engine determines whether the pressure in airbag 1104 is “insufficient,” “sufficient,” “excessive” (as an illustrative example), or somewhere in between. This informs the importance of the pressure in airbag 1104 and any necessary actions (e.g., changes in pressure or associated voltage). The importance of the determined state is determined by a defuzzification process, which may result in outputs such as control signals being sent to pump 1102 or vent 1106.

[0120] exist FIG. 11AIn one example scenario, the fuzzer can receive a pressure of P1. P1 can correspond to approximately 0.75 along the first membership function 1150, indicating that the pressure is "quite low" because it is relatively high along the first membership function 1150 and falls between "insufficient" and "sufficient". Another way to interpret 0.75 is that there is a 75% probability that the input pressure is insufficient. P1 can also correspond to approximately 0.25 along the second membership function 1152 and approximately 0.00 along the third membership function 1154. The fuzzy variables [0.75, 0.25, 0] can thus be determined. A set of rules from the rule base can indicate that if the pressure along the membership function is higher than 0.5, and the target pressure is higher than the input pressure (e.g., P... 1), then the pressure should be increased. Fuzzy logic 1113 can therefore output and transmit a control signal to apply the corresponding voltage to drive pump 1102 to inflate air bag 1104.

[0121] In another example scenario, the pressure P2 can be received. Based on the example rule set along the membership function 1152 at 0.75 or greater as needed, it can be determined that no pressure change is required. However, if the example rule set requires the membership function 1152 to be at 0.95 or greater and the target pressure is low, it can be determined that P2 is too high. In such cases, a control signal can be generated that opens the vent 1106 to vent the air bag 1104 and / or uses a voltage to bring the pressure to the target pressure to start the pump 1102.

[0122] In another example scenario, pressure P3 is acceptable. Similar to the example above, depending on the rule set and the target pressure level 1111, this pressure may be considered excessive (or not excessive).

[0123] In some implementations, fuzzy logic 1113 may be implemented using neural network 1130 (e.g., artificial neural network (ANN) or radial basis function (RBF) network) to generate a self-learning model. In some configurations, neural network 1130 may include an input layer, a fuzzy layer, a fuzzy inference layer, and an output layer. In other configurations, neural network 1130 may include more or fewer layers. For example, a hidden layer with a nonlinear RBF activation function may be implemented between the input layer and the output layer. Thus, fuzzy logic 1113 can benefit not only from mimicking the granular output of human decisions about whether and how to control the pressure applied by example sensor device 1100, but also from the self-learning of neural network 1130 to further refine the output.

[0124] FIG. 11BA simplified block diagram illustrates how fuzzy logic 1113 receives target information 1111 and feedback information 1109 (e.g., from a component of example sensor device 1100, such as pressure sensor 1108) and generates control signals for that component. This enables "fuzzy" and human-like reasoning regarding whether and how the pressure granularity in airbag 1104 is adjusted.

[0125] The above example is merely an illustration of a method that can be used to adjust pressure as needed using feedback pressure information 1109 and fuzzy logic 1113. Maintaining pressure at a specific pressure level is crucial for estimating physiological parameters such as blood pressure using sensor measurements. Other types of fuzzers that can be used by controller 1110 may include singleton fuzzers or Gaussian fuzzers.

[0126] In some specific implementations, control system 1101 may be or include a proportional-integral-derivative (PID) controller, and controller 1110 may be a PID controller. PID controllers can be used with feedback control loop mechanisms, which are useful for control systems. FIG. 11C This is a block diagram of a PID controller in a feedback loop. PID controllers are robust, simple to design and retune, and can demonstrate clear relationships between system parameters. PID controllers are designed to handle linear control systems with stability and dynamic response, and their parameters can be tuned via iterative processes or other metaheuristic methods. The effectiveness of a PID controller is based on the accuracy of the system model and variables.

[0127] A PID controller can use three control terms that have proportional (P), integral (i), and derivative (D) effects on the output to apply accurate and optimal control. Term P is proportional to the error e(t), which is the difference between the desired target (e.g., based on target information y(t)) and the measured output of process y(t). The gain factor Kp is proportional to the magnitude of the error e(t). Term I is the integral of past values ​​of the error e(t) over time, taking into account the historical accumulation of the error. Factor Ki adds the control effect seeking to eliminate residual error. Term D is an estimate of the future trend of the error e(t) based on the current rate of change. Factor Kd seeks to reduce or mitigate the effect of the error e(t), where the faster the change, the greater the control effect. The effects produced by these three terms are balanced by tuning the control loop to produce the optimal control function.

[0128] In some specific implementations, FIG. 10 The controller 1010 may also implement one or more of the features described above for the controller 1110 (e.g., fuzzy logic, neural network, or PID controller). In this way, the pressure in the air bag 1004 can be better controlled without using calibrated rules.

[0129] FIG. 12 This is a block diagram of an example sensor device 1200 using fuzzy logic 1213 and a PID controller 1210 according to some implementation schemes. The example sensor device 1200 may further include a pump 1202, a vent 1206, and a pressure sensor 1208, which may be similar to or relative to... FIG. 10 and FIG. 11 Examples of their counterparts are described, and their descriptions will be omitted for brevity. In some embodiments, the input may be based on target information 1211 and feedback information 1209, such as the difference between the target pressure level and the pressure of the airbag or air bag (not shown) measured by pressure sensor 1208, or the error e(t). The input may be fed to PID controller 1210 and / or fuzzy logic 1213. In some cases, fuzzy logic 1213 may determine the error itself rather than being provided with an error.

[0130] In some methods, fuzzy logic 1213 can determine whether the pressure detected and indicated in feedback information 1209 is too high, too low, or sufficient compared to the target pressure level indicated by target information 1211 through the fuzzification and defuzzification processes described above. Information or control signals corresponding to voltage levels configured to compensate for any deviation from the target pressure can be generated and output. PID controller 1210 can use this error to determine Kp, Ki, Kd, ​​and generate outputs including information or control signals for pump 1202 (e.g., a voltage corresponding to the desired or target pressure level) and / or vent 1206 (e.g., a control signal 1206 for opening or closing the vent). In short, FIG. 13 The graphs showing the applied pressure and current consumption as a function of voltage are presented. Graph 1302 shows the pressure as a function of voltage. Graph 1304 shows the current consumption as a function of voltage. It can be seen that there is a roughly proportional correlation between voltage, pressure, and current. This information can be useful in determining the amount of voltage to be applied for the desired pressure.

[0131] In some cases, the PID controller 1210 may compare its output with information output by the fuzzy logic 1213. If a substantial difference exists, such as a difference between the outputs exceeding an error threshold, one or both outputs may be discarded. If an acceptable difference exists, such as within the error threshold, the output of the PID controller 1210 or the output of the fuzzy logic 1213 may be used to control the pump 1202 and / or the vent 1206.

[0132] Therefore, the example sensor device 1200 can use a closed-loop system to control and maintain the pressure level. More specifically, a voltage or signal corresponding to the desired target pressure level can be applied to the pump 1202 and / or the vent 1206, as described herein. Sensor measurements can be performed based on the timing of inflation or deflation.

[0133] Example operation involving example sensor device 1100 or 1200 may include one or more of the following: (1) The air bag 1104 may be inflated by pump 1202 based on the application of an initial voltage to pump driver 1112.

[0134] (2) The control system 1101 and / or the controller 1110 (which may be implemented as PID controllers 1110, 1210) can maintain the difference between the tracking target voltage and the feedback voltage and generate a control signal indicating the voltage to the pump driver 1112. Fuzzy logic 1113, 1213 can also be used to evaluate the difference.

[0135] (3) The control system 1101 and / or the controller 1110 may use a control signal configured to close or open the vent 1106 to control the vent 1106.

[0136] (4) When the PID error (e(t)) is less than the threshold, the control system 1101 and / or the controller 1110 can shut down the pump 1102, which indicates that the pressure has reached the target pressure.

[0137] (5a) Sensor 1118 (e.g., photoacoustic sensor) can measure relative to a target object (e.g., a user's blood vessel) when pump 1202 is off. The pressure applied to the user by air bag 1104 can be maintained at the target pressure.

[0138] (5b) Changes in conditions (such as temperature or altitude) can occur and cause a corresponding change in the applied pressure. For example, the temperature may have decreased and reduced the pressure, or the temperature may have increased (e.g., at least in part due to the higher temperature of the sensor device or prolonged operation). In such scenarios, the pressure in the air bag 1104 can be compensated accordingly (e.g., by applying a voltage to the pump driver 1112 to increase the pressure in the air bag 1104). The voltage used for compensation can be determined by PID controllers 1110, 1210 and / or fuzzy logic 1113, 1213, as discussed above.

[0139] (6) The control system 1101 and / or controller 1110 may inflate the air bag 1104 to the next target pressure. In some embodiments, a new control signal indicating a new pump voltage may be generated. In some cases, another new control signal may be generated, configured to appropriately open or close the vent 1106. The new control signal may be applied to the pump driver 1112 and / or up to the vent 1106 until the new target pressure is reached, thereby establishing, for example, FIG. 9 The stepped pressure distribution shown is either without pressure compensation or 9A (with pressure compensation).

[0140] During any transition cycle in which the pressure is changing, whether based on the next target pressure or if compensation is required, the photoacoustic sensor may not take measurements to mitigate noise interference caused by the operation of pump 1202 or vent 1106 (or other components that generate noise during operation).

[0141] Machine learning In some implementations, machine learning models can be used to predict physiological parameters, such as a user's blood pressure. In some implementations, machine learning models can be used to predict voltage (e.g., to be applied to a pump) based on target pressure information and measured feedback pressure information. A machine learning model (or artificial intelligence model) can refer to a computational algorithm that indicates the relationship between input variables and output variables. In some implementations, the machine learning model can be trained. Training a machine learning model may involve determining weight values, etc., associated with the machine learning model, wherein the relationship between input variables and output variables is at least partially based on the determined weight values. In one specific implementation, the machine learning model can be trained in a supervised manner using a training set that includes labeled training data. In a more specific example, the labeled training data may include inputs and manually annotated outputs that the machine learning model will approximate using the determined weight values. In another specific implementation, the machine learning model can be trained in an unsupervised manner, wherein weight values ​​are determined without manually labeled training data.

[0142] An example training process for a machine learning model may involve providing training data that includes various data such as known target pressure, measured feedback pressure, current temperature, current altitude, temperature changes, altitude changes, a known difference (error) between the target pressure and the measured feedback pressure, inflation or deflation time and / or fuzzy variables, and output characteristics or parameters labeled as "benchmark true" or known, such as the voltage to be applied to the pump (if the model's goal is to determine the voltage) or the user's blood pressure (if the model's goal is to predict blood pressure). In some approaches, a portion of the training data (e.g., 20%) may be used as part of the validation set for the machine learning model. Using the training data and validation set, one or more loss functions can be implemented. A loss function is an optimization function in which the error is iteratively minimized, for example, by gradient descent. An effective learning rate can also be set during training, which determines the "steps" taken by gradient descent to find the minimum error. During this learning process, one or more parameters of the machine learning model can be tuned and optimized to make the predicted output more accurate.

[0143] Therefore, a trained machine learning model can be generated. In some implementations, this trained machine learning model can be used to further enhance the accuracy and reliability of the estimated physiological characteristics or parameters. For example, a user's blood pressure derived from sensor measurements can be provided to a machine learning model (stored at the sensor or host device, and / or accessible by its control system) for comparison with the blood pressure estimated by the machine learning model. If there is an inconsistency greater than a threshold between the sensor-based estimate and the model-generated prediction, the acquired estimate can be further evaluated or discarded. If discarded, the model-generated prediction or additional measurements by the sensor can be used. On the other hand, if the inconsistency is below a threshold, the sensor-based estimate can be selected or retained for use.

[0144] PWV and pressure data A significant use of stepped pressure levels is to provide data representing discrete pressure levels as part of the input to a predictive model for estimating a user's physiological parameters (e.g., blood pressure). In some configurations, the predictive model can be a machine learning model. Pressure levels can be provided as input to the predictive model in the form of one or more charts (e.g., Chart 900 or 920) or in data structures such as lists, matrices, or tables, including pressure levels and / or other types of information such as duration, time, transition cycles, errors, temperature changes, etc.

[0145] In some implementations, the sensor (e.g., a photoacoustic sensor) may acquire measurements during the time when the pressure applied to the user is at discrete pressure levels (e.g., 906, 910, 914, 918, 924, 926) or during a portion of such time when no pressure correction is performed (e.g., transition cycles 935, 937 associated with alternative pressure levels 925, 927).

[0146] Therefore, this method can be used to obtain PWV data corresponding to the appropriate pressure level within a pressure range. In some implementations, multi-point PWV curves can be generated. FIG. 14 This is a graph showing the change in PWV (Pulse Wave Volume) as applied external pressure, based on a set of example data points 1402 according to some implementation schemes. In some methods, a curve 1410, such as an exponential, polynomial, or logarithmic curve, can be fitted over the data points 1402. In some cases, the curve 1410 may be linear, depending on the range of data points or the degree of data constraint; smaller portions of the curve 1410 may be substantially linear. In some cases, the slope of the curve 1410 can provide useful information, such as compliance or portions of the Bramwell-Hill equation, which relate to arterial dilatation, pressure changes, and PWV.

[0147] Some or all of the above information can be provided to the aforementioned predictive model for training and / or inference. In some methods, training the predictive model may further include providing a set of labeled baseline real blood pressure data, such as known blood pressure based on PWV and pressure data.

[0148] In some implementations, the control system or controller of the type described above can be configured to implement a predictive model. In some configurations, the predictive model can be trained to output the user's blood pressure based on input data including multiple PWVs and multiple discrete pressure levels.

[0149] Example method FIG. 15 This is a flowchart of a method 1500 for determining a user's physiological parameters according to some publicly disclosed embodiments. It is used for execution... FIG. 15 The functional structures illustrated in one or more of the boxes shown can be performed by hardware and / or software components of a computerized device or system (which in some embodiments may be implemented as a wearable user device). Components of such a device or system may include, for example, one or more sensors, a control system (including one or more processors), memory, and / or a 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 the device to perform the operations indicated by the boxes below when executed by the control system. FIG. 2, FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Example components of the device are illustrated below, which are described in more detail above.

[0150] FIG. 15 The block can be executed, for example, by the means shown in the figures above or by similar means or components thereof (e.g., a control system). As with other methods disclosed herein, FIG. 15 The methods outlined herein may include more or fewer boxes than those shown. Furthermore, the boxes in the methods disclosed herein are not necessarily executed in the indicated order. In some instances, FIG. 15 One or more boxes in the box shown can be executed simultaneously.

[0151] At block 1510, method 1500 may include acquiring one or more first sensor measurements from the user's blood vessels when the pressure applied to a portion of the user is at a first target pressure level at a first moment, the one or more first sensor measurements relating to first data on the characteristics of the blood vessels. In some embodiments, the first data on the characteristics of the blood vessels may include a first pulse wave velocity (PWV) of the blood vessels.

[0152] Components for performing functionality at frame 1510 may include interface 201, receiver system 202, light source system 204, ring system 205, biometric sensors 212 (sensors 622, 722, 1018, 1118), pumps 604, 714, 1002, 1102, 1202, airbags 608, 740 (air bags 1004, 1104), vents 610, 1006, 1106, 1206, and / or such as FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0153] At block 1520, method 1500 may include acquiring one or more second sensor measurements from the user's blood vessel when the pressure applied to a portion of the user is at a second target pressure level at a second time, the one or more second sensor measurements relating to second data on the characteristics of the blood vessel. In some embodiments, the second data on the characteristics of the blood vessel may include a second PWV of the blood vessel.

[0154] In some implementations, the pressure applied to a portion of the user at a first target pressure level and a second target pressure level may be based on a calibrated relationship between the first target pressure level and the second target pressure level and the corresponding voltage level that can be applied to the wearable user device.

[0155] Components for performing functionality at frame 1520 may include interface 201, receiver system 202, light source system 204, ring system 205, biometric sensors 212 (sensors 622, 722, 1018, 1118), pumps 604, 714, 1002, 1102, 1202, airbags 608, 740 (air bags 1004, 1104), vents 610, 1006, 1106, 1206, and / or such as FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0156] At box 1530, method 1500 may include first and second data based at least on vascular characteristics to determine a user's physiological parameters. In some embodiments, the wearable user device may further include a control system configured to implement a predictive model that outputs a user's physiological parameters (e.g., blood pressure) based on input data including multiple pressure values ​​(e.g., first and second PWVs of the blood vessels) and multiple discrete pressure levels (e.g., a first target pressure level and a second target pressure level). In some cases, PWVs acquired during discrete pressure levels can be used to determine blood pressure using relationships such as the Bramwell-Hill equation. However, the method described herein offers significant advantages because the biometric measurements (e.g., photoacoustic measurements) and therefore the PWVs acquired using the embodiments described herein are cleaner data that is less affected by noise and errors than previous methods.

[0157] Components used to perform functionality at frame 1530 may include control system 206, controller 602, main board 712, control board 718, controller 1010, control system 1101, controller 1110, and / or such as FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0158] In some embodiments, the wearable user device or its loop may be configured to cease operation when the applied pressure is at one of a plurality of discrete pressure levels (e.g., a first target pressure level, a second target pressure level), and to operate to apply pressure during one or more transitions between two of the plurality of discrete pressure levels; and the wearable user device's biometric sensor may be configured to acquire sensor measurements when the applied pressure is at the plurality of discrete pressure levels and not acquire sensor measurements during one or more transitions between the plurality of discrete pressure levels. In some specific embodiments, the biometric sensor may acquire sensor measurements, wherein the biometric sensor may include: a photoacoustic sensor configured to acquire a photoacoustic signal generated from light incident on the user's blood vessels; an acoustic sensor configured to acquire an acoustic signal; or both. In some specific embodiments, the loop may be further configured to adjust the pressure to one of the plurality of discrete pressure levels based on a calibrated relationship between the plurality of discrete pressure levels and corresponding voltage levels in response to a deviation of the pressure applied to a portion of the user from the plurality of discrete pressure levels.

[0159] In some embodiments, method 1500 may further include, when the vent of the wearable user device is closed: setting the pressure applied to a portion of the user to a first target pressure level by applying a first voltage corresponding to a first target pressure level to the inflatable portion of the wearable user device; and, after reaching the first target pressure level, reducing the first voltage applied to the inflatable portion to zero. One or more first sensor measurements from the user's blood vessels may be acquired when the first voltage applied to the inflatable portion is zero. In some specific embodiments, after acquiring one or more first sensor measurements, method 1500 may further include, when the vent of the wearable user device is closed: setting the pressure applied to a portion of the user to a second target pressure level by applying a second voltage corresponding to a second target pressure level to the inflatable portion of the wearable user device; and, after reaching the second target pressure level, reducing the second voltage applied to the inflatable portion to zero. One or more second sensor measurements from the user's blood vessels may be acquired when the second voltage applied to the inflatable portion is zero.

[0160] In some embodiments, method 1500 may further include increasing or decreasing the pressure applied to a portion of the user during a transition period between a first time and a second time via the operation of the loop of the wearable user device. In some methods, method 1500 may further include preventing sensor measurements during the operation of the loop. In some methods, the acquisition of one or more first sensor measurements and one or more second sensor measurements may occur when the loop is not in operation.

[0161] In some implementations, method 1500 may further include detecting that the pressure applied to a portion of the user has deviated from a first target pressure level or a second target pressure level; and in response to the deviation of the pressure, adjusting the pressure applied to the portion of the user back to the first target pressure level or the second target pressure level.

[0162] In some embodiments, method 1500 may further include determining a current pressure applied to a portion of the user; wherein the pressure applied to the portion of the user at a first target pressure level and a second target pressure level is based at least on a feedback loop involving the difference between the current pressure and the target pressure levels. In some embodiments, method 1500 may further include determining a voltage level to compensate for the difference between the current pressure and the target pressure level. In some embodiments, the voltage level may be determined by fuzzy logic, a neural network, a proportional-integral-derivative (PID) controller, or a combination thereof.

[0163] FIG. 16 This is a flowchart of a method 1600 for determining a user's physiological parameters according to some publicly disclosed implementation schemes. It is used to perform... FIG. 16 The functional structures illustrated in one or more of the boxes shown can be performed by hardware and / or software components of a computerized device or system (which may be implemented as a wearable device in some embodiments). Components of such a device or system may include, for example, one or more sensors, a control system (including one or more processors), memory, and / or a 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 the device to perform the operations indicated by the boxes below when executed by the control system. FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Example components of the device are illustrated below, which are described in more detail above.

[0164] FIG. 16 The block can be executed, for example, by the means shown in the figures above or by similar means or components thereof (e.g., a control system). As with other methods disclosed herein, FIG. 16 The methods outlined herein may include more or fewer boxes than those shown. Furthermore, the boxes in the methods disclosed herein are not necessarily executed in the indicated order. In some instances, FIG. 16 One or more boxes in the box shown can be executed simultaneously.

[0165] At block 1610, method 1600 may include applying pressure to a portion of the user at a first discrete pressure level by at least increasing or decreasing the current pressure of the ring to a first target pressure level.

[0166] In some implementations, increasing the current pressure of the annulus to a first target pressure level may include inflating a portion of the annulus (e.g., an air bladder, air bag) based on a corresponding voltage applied to a pump associated with the annulus. In some configurations, the vent associated with the annulus may be closed while the current pressure of the annulus is increasing. In some implementations, decreasing the current pressure of the annulus to the first target pressure level may include deflating a portion of the annulus, inflating a portion of the annulus, or a combination thereof. In some configurations, partially deflating the annulus may include opening the vent associated with the annulus. In some configurations, decreasing the current pressure of the annulus to the first target pressure level may include partially deflating the annulus to below the first target pressure level, and then subsequently partially inflating the annulus based on a corresponding voltage applied to a pump.

[0167] Components used to perform functionality at frame 1610 may include a belt system 205, pumps 604, 714, 1002, 1102, 1202, airbags 608, 740 (airbags 1004, 1104), vents 610, 1006, 1106, 1206, and / or such as FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0168] At block 1620, method 1600 may include acquiring one or more first sensor measurements associated with a user's target object when the applied pressure is at a first target pressure level. In some embodiments, acquiring one or more first sensor measurements associated with a user's target object may include using a photoacoustic sensor to acquire one or more photoacoustic measurements generated from light incident on the user's blood vessels. In some embodiments, one or more first sensor measurements are not acquired when the applied pressure is not at the first target pressure level (or any target pressure level) (e.g., during a transition period between target pressure levels).

[0169] Components for performing functionality at frame 1620 may include interface 201, receiver system 202, light source system 204, ring system 205, biometric sensors 212 (sensors 622, 722, 1018, 1118), airbags 608, 740 (air bags 1004, 1104), vents 610, 1006, 1106, 1206, and / or as... FIG. 2 ,FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0170] At block 1630, method 1600 may include applying pressure to a portion of the user at a second discrete pressure level by at least increasing or decreasing the current pressure of the ring from a first target pressure level to a second target pressure level. Increasing or decreasing the current pressure may be similar to the operation described relative to block 1610.

[0171] Components used to perform functionality at frame 1630 may include a belt system 205, pumps 604, 714, 1002, 1102, 1202, airbags 608, 740 (airbags 1004, 1104), vents 610, 1006, 1106, 1206, and / or such as FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0172] At block 1640, method 1600 may include acquiring one or more second sensor measurements associated with a user's target object when the applied pressure is at a second target pressure level. Acquiring one or more second sensor measurements when the applied pressure is at a second target pressure level may be similar to the operation described with respect to block 1620.

[0173] Components for performing functionality at frame 1640 may include interface 201, receiver system 202, light source system 204, ring system 205, biometric sensors 212 (sensors 622, 722, 1018, 1118), airbags 608, 740 (air bags 1004, 1104), vents 610, 1006, 1106, 1206, and / or as... FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 Other components of the apparatus shown.

[0174] At block 1650, method 1600 may include determining a user's physiological parameters based at least on one or more first sensor measurements and one or more second sensor measurements associated with a target object of the user. In some embodiments, the user's physiological parameters may include the user's blood pressure. In some embodiments, multiple pulse-wave volumes (PWVs) of the user's blood vessels may be derived from one or more first sensor measurements and one or more second sensor measurements. In some embodiments, a predictive model (e.g., a machine learning model) may be configured to determine the user's blood pressure using the methods described above, including using data associated with multiple PWVs of the blood vessels, as well as first and second PWVs.

[0175] Feedback loops can be implemented to maintain discrete pressure levels based on target pressure levels. In some scenarios, the current pressure of the ring, a first target pressure level, or a second target pressure level may deviate from the expected pressure level due to factors such as temperature fluctuations, changes in operating time and / or altitude. In some implementations, feedback information from pressure sensors (e.g., pressure at the ring or voltage at the pump) and target information (e.g., target pressure or target voltage of the ring) can be used to correct the pressure applied to a portion of the user. In some specific implementations, a PID controller can determine the optimal voltage level to be applied to the pump to increase the current pressure to the correct level, or determine a control signal to be applied to the vent of the ring to decrease the current pressure to the correct level. In some specific implementations, fuzzy logic can be used to determine the voltage level for the pump or the control signal for the vent. In some specific implementations, a neural network can be used to determine the voltage level for the pump or the control signal for the vent.

[0176] Components used to perform functionality at frame 1650 may include control system 206, controller 602, main board 712, control board 718, controller 1010, control system 1101, controller 1110, and / or such as FIG. 2 , FIG. 6 , FIG. 7 , FIG. 10 , FIG. 11 and FIG. 12 FIG. 2 FIG. 6 FIG. 7 FIG. 10 FIG. 11 FIG. 12 FIG. 2 FIG. 6 FIG. 7 FIG. 10 FIG. 11 FIG. 12 FIG. 2 FIG. 6 FIG. 7 FIG. 10 FIG. 11 FIG. 12 FIG. 2 FIG. 6 FIG. 7 FIG. 10 FIG. 11 FIG. 12 FIG. 2 FIG. 6 FIG. 7 FIG. 10 FIG. 11 FIG. 12 FIG. 2 FIG. 6 FIG. 7 FIG. 1 Other components of the apparatus shown.

[0177] As used in this article, the phrase “at least one of the items” refers to any combination of these items, including a single member. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc.

[0178] The various exemplary logics, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the specific implementations disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. The interchangeability of hardware and software has been broadly described in terms of functionality and illustrated in the aforementioned exemplary components, blocks, modules, circuits, and processes. Whether such functionality is implemented in hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0179] Hardware and data processing means for implementing the various exemplary logic, logic blocks, modules, and circuits described herein can be implemented or executed using general-purpose single-chip or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some specific implementations, specific processes and methods can be performed by circuitry specific to a given function.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] Certain features described in this specification in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although features may be described above as operating in certain combinations and even originally claimed in this way, one or more features from the claimed combination may be removed from that combination in some cases, and the claimed combination may be for sub-combinations or variations thereof.

[0184] Similarly, although operations are depicted in a specific order in the figures, this should not be construed as requiring such operations to be performed in the shown specific order or sequential order, or to perform all illustrated operations to achieve the desired result. In some environments, multitasking and parallel processing are advantageous. Furthermore, the separation of the various system components in the embodiments described above should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired result.

[0185] 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.

[0186] Various modifications to the specific embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other specific embodiments without departing from the spirit or scope of this disclosure. Therefore, the following claims are not intended to be limited to the specific embodiments shown herein, but should be granted the broadest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0187] Additionally, some features described in this specification within the context of individual embodiments may also be implemented in combination within a single embodiment. Conversely, features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, while some features are described above as working in a particular combination and even initially claimed in this way, in some cases, one or more features from the claimed combination may be extracted from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0188] 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 specific order shown or in sequential order, or to perform all illustrated operations to achieve the desired result. Furthermore, the figures may schematically depict one or more example processes in the form of flowcharts. However, other operations not depicted may be incorporated into the schematically illustrated example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. Moreover, the various operations in the described and illustrated operations may themselves include and collectively refer to multiple sub-operations. For example, each operation in the operations described above may itself involve the execution of a process or algorithm. Furthermore, in some embodiments, the various operations in the described and illustrated operations may be combined or performed in parallel. Similarly, the separation of various system components in the embodiments described above should not be construed as requiring this in all embodiments. Thus, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result.

[0189] Specific implementation examples are described in the following numbered clauses: Clause 1: A wearable user device comprising: a loop configured to apply pressure to a portion of a user at multiple discrete pressure levels over multiple time periods; a biometric sensor configured to acquire, during corresponding time periods of the multiple time periods, multiple sensor measurements associated with a blood vessel of the user at a corresponding discrete pressure level among the multiple discrete pressure levels, the multiple sensor measurements being correlated with multiple data points relating to characteristics of the user's blood vessel, the multiple data points relating to characteristics of the blood vessel enabling determination of the user's blood pressure; and a wearable structure comprising the loop and the biometric sensor.

[0190] Clause 2: The wearable user device according to Clause 1, wherein: the loop is further configured to cease operation when the applied pressure is at one of the plurality of discrete pressure levels, and to operate to apply the pressure during one or more transitions between two of the plurality of discrete pressure levels; and the biometric sensor is further configured to acquire the plurality of sensor measurements when the applied pressure is at the plurality of discrete pressure levels and not acquire the plurality of sensor measurements during the one or more transitions between the plurality of discrete pressure levels.

[0191] Clause 3: A wearable user device according to any one of Clauses 1 to 2, wherein the characteristic of the blood vessel includes the pulse wave velocity (PWV) of the blood vessel; the plurality of data of the characteristic of the blood vessel includes a plurality of PWVs corresponding to a respective discrete pressure level among the plurality of discrete pressure levels; and the user's blood pressure is determined based on the plurality of PWVs and the plurality of discrete pressure levels.

[0192] Clause 4: The wearable user device according to any one of Clauses 1 to 3, the wearable user device further includes a control system configured to implement a predictive model, the predictive model being configured to output the user's blood pressure based on input data including the plurality of PWVs and the plurality of discrete pressure levels.

[0193] Clause 5: A wearable user device according to any one of Clauses 1 to 4, wherein the biometric sensor comprises: a photoacoustic sensor configured to acquire a photoacoustic signal generated from light incident on the user's blood vessels; an acoustic sensor configured to acquire an acoustic signal; or both.

[0194] Clause 6: A wearable user device according to any one of Clauses 1 to 5, wherein the loop further comprises: an airbag configured to maintain the pressure to the portion of the user at each of the plurality of discrete pressure levels according to a corresponding voltage level; and a vent configured to close during inflation of the airbag and maintenance of the pressure, and to open during deflation of the airbag.

[0195] Clause 7: The wearable user device according to any one of Clauses 1 to 6, the wearable user device further comprising: a pressure sensor configured to detect that the pressure applied to the portion of the user has deviated from the plurality of discrete pressure levels; wherein, in response to the deviation of the pressure, the loop is further configured to adjust the pressure to one of the plurality of discrete pressure levels.

[0196] Clause 8: A wearable user device according to any one of Clauses 1 to 7, wherein the pressure applied to the portion of the user at the plurality of discrete pressure levels is based on a calibrated relationship between the plurality of discrete pressure levels and the corresponding voltage levels that can be applied to the ring.

[0197] Clause 9: A wearable user device according to any one of Clauses 1 to 8, wherein the loop is further configured to adjust the pressure to one of the plurality of discrete pressure levels based on the calibrated relationship between the plurality of discrete pressure levels and the corresponding voltage levels in response to a deviation of the pressure applied to the portion of the user from the plurality of discrete pressure levels.

[0198] Clause 10: A wearable user device according to any one of Clauses 1 to 9, the wearable user device further comprising a pressure sensor configured to determine a current pressure applied to the portion of the user and a voltage level corresponding to the current pressure; wherein the pressure applied to the portion of the user at the plurality of discrete pressure levels is based at least on a feedback loop that minimizes (i) the difference between the voltage corresponding to the current pressure provided by the pressure sensor and (ii) a target voltage.

[0199] Clause 11: A wearable user device according to any one of Clauses 1 to 10, wherein the voltage level corresponding to the pressure applied to the portion of the user is generated at least in part using: a neural network receiving the current pressure, the voltage level corresponding to the current pressure, the current temperature associated with the ring, the target voltage, or a combination thereof.

[0200] Clause 12: The wearable user device according to any one of Clauses 1 to 11, the wearable user device further includes a control system configured to implement fuzzy logic via the neural network to generate the voltage level corresponding to the pressure applied to the portion of the user.

[0201] Clause 13: A wearable user device according to any one of Clauses 1 to 12, wherein the plurality of data of the characteristics of the blood vessels includes a plurality of PWVs corresponding to a respective discrete pressure level among the plurality of discrete pressure levels; and the wearable user device further includes a control system configured to determine the user's blood pressure based on the plurality of PWVs.

[0202] Clause 14: A wearable user device according to any one of Clauses 1 to 13, wherein the control system is further configured to determine the user's blood pressure based on a predictive model, the predictive model being configured to receive curves of the plurality of PWVs varying with the plurality of discrete pressure levels as input.

[0203] Clause 15: Wearable user device according to any one of Clauses 1 to 14, wherein the plurality of discrete pressure levels include pressure levels in the range of 20 mmHg to 90 mmHg (inclusive).

[0204] Clause 16: A method for determining a user's physiological parameters using a wearable user device, the method comprising: acquiring one or more first sensor measurements from the user's blood vessels when pressure applied to a portion of the user is at a first target pressure level at a first time, the one or more first sensor measurements being correlated with the first data of characteristics of the blood vessels; acquiring one or more second sensor measurements from the user's blood vessels when pressure applied to the portion of the user is at a second target pressure level at a second time, the one or more second sensor measurements being correlated with the second data of the characteristics of the blood vessels; and determining the user's physiological parameters based at least on the first data and the second data of the characteristics of the blood vessels.

[0205] Clause 17: The method according to Clause 16, the method further comprising: when the vent of the wearable user device is closed: setting the pressure applied to the portion of the user to the first target pressure level by applying a first voltage corresponding to the first target pressure level to the inflatable portion of the wearable user device; and after the first target pressure level is reached, reducing the first voltage applied to the inflatable portion to zero; wherein the one or more first sensor measurements from the user's blood vessels are acquired when the first voltage applied to the inflatable portion is zero.

[0206] Clause 18: The method according to any one of Clauses 16 to 17, the method further comprising: after acquiring the one or more first sensor measurements, when the vent of the wearable user device is closed: setting the pressure applied to the portion of the user to the second target pressure level by applying a second voltage corresponding to the second target pressure level to the inflatable portion of the wearable user device; and after reaching the second target pressure level, reducing the second voltage applied to the inflatable portion to zero; wherein the one or more second sensor measurements of the blood vessels of the user are acquired when the second voltage applied to the inflatable portion is zero.

[0207] Clause 19: The method according to any one of Clauses 16 to 18, the method further comprising: increasing or decreasing the pressure applied to the portion of the user during a transition period between the first time and the second time via the operation of the loop of the wearable user device.

[0208] Clause 20: The method according to any one of Clauses 16 to 19, the method further comprising: preventing sensor measurements during operation of the ring belt.

[0209] Clause 21: The method according to any one of Clauses 16 to 20, wherein the acquisition of the one or more first sensor measurements and the one or more second sensor measurements occurs when the loop is not in operation.

[0210] Clause 22: The method according to any one of Clauses 16 to 21, the method further comprising: detecting that the pressure applied to the portion of the user has deviated from the first target pressure level or the second target pressure level; and in response to the deviation of the pressure, adjusting the pressure applied to the portion of the user to the first target pressure level or the second target pressure level.

[0211] Clause 23: The method according to any one of Clauses 16 to 22, wherein the first data of the characteristic of the blood vessel includes a first pulse wave velocity (PWV) of the blood vessel, and the second data of the characteristic of the blood vessel includes a second PWV of the blood vessel.

[0212] Clause 24: The method according to any one of Clauses 16 to 23, wherein the pressure applied to the portion of the user at the first target pressure level and the second target pressure level is based on a calibrated relationship between the first target pressure level and the second target pressure level and a corresponding voltage level that can be applied to the wearable user device.

[0213] Clause 25: The method according to any one of Clauses 16 to 24, the method further comprising: determining a current pressure applied to the portion of the user; wherein the pressure applied to the portion of the user at a first target pressure level and a second target pressure level is based at least on a feedback loop involving (i) the difference between the current pressure and (ii) the target pressure level.

[0214] Clause 26: The method according to any one of Clauses 16 to 25, the method further comprising: determining a voltage level to compensate for the difference between the current pressure and the target pressure level.

[0215] Clause 27: The method according to any one of Clauses 16 to 26, wherein the voltage level is determined by fuzzy logic, neural network, proportional-integral-derivative (PID) controller, or a combination thereof.

[0216] Clause 28: An apparatus comprising: means for applying pressure to a portion of a user at a plurality of discrete pressure levels over a plurality of time periods; means for acquiring, during corresponding time periods of the plurality of time periods, a plurality of sensor measurements associated with a blood vessel of the user at a corresponding discrete pressure level among the plurality of discrete pressure levels, the plurality of sensor measurements being associated with a plurality of data relating to characteristics of the blood vessel of the user, the plurality of data relating to characteristics of the blood vessel enabling determination of the user's blood pressure; and a wearable means comprising the means for applying the pressure to the portion of the user and the means for acquiring the plurality of sensor measurements.

[0217] Clause 29: The apparatus according to Clause 28, wherein: the component for applying the pressure to the portion of the user includes a component for stopping operation when the applied pressure is at one of the plurality of discrete pressure levels and a component for operating to apply the pressure during one or more transitions between two of the plurality of discrete pressure levels; and the component for acquiring the plurality of sensor measurements includes a component for acquiring the plurality of sensor measurements when the applied pressure is at the plurality of discrete pressure levels and not acquiring the plurality of sensor measurements during the one or more transitions between the plurality of discrete pressure levels.

[0218] Clause 30: A non-transitory computer-readable device comprising a storage medium including a plurality of instructions configured to, when executed by one or more processors, cause the device to: acquire one or more first sensor measurements from a blood vessel of a user when pressure applied to a portion of the user is at a first target pressure level at a first time, the one or more first sensor measurements relating to the first data of a characteristic of the blood vessel; acquire one or more second sensor measurements from the blood vessel of the user when pressure applied to the portion of the user is at a second target pressure level at a second time, the one or more second sensor measurements relating to the second data of the characteristic of the blood vessel; and determine physiological parameters of the user based at least on the first data and the second data of the characteristic of the blood vessel.

Claims

1. A wearable user device, the wearable user device comprising: A ring band, the ring band being configured to apply pressure to a portion of the user at multiple discrete pressure levels over multiple time periods; A biometric sensor configured to acquire multiple sensor measurements associated with a user's blood vessels at corresponding discrete pressure levels within a plurality of time periods, the multiple sensor measurements being correlated with multiple data points relating to characteristics of the user's blood vessels, the multiple data points relating to characteristics of the blood vessels enabling the determination of the user's blood pressure; and A wearable structure, the wearable structure including the loop and the biometric sensor.

2. The wearable user device according to claim 1, wherein: The annular belt is further configured to stop operating when the applied pressure is at one of the plurality of discrete pressure levels, and to operate to apply the pressure during one or more transitions between two of the plurality of discrete pressure levels; and The biometric sensor is further configured to acquire the plurality of sensor measurements when the applied pressure is at the plurality of discrete pressure levels and not acquire the plurality of sensor measurements during the one or more transitions between the plurality of discrete pressure levels.

3. The wearable user device according to claim 1, wherein: The characteristics of the blood vessel include the pulse wave velocity (PWV) of the blood vessel. The plurality of data relating to the characteristics of the blood vessel include a plurality of PWVs corresponding to a respective discrete pressure level among the plurality of discrete pressure levels; and The user's blood pressure is determined based on the plurality of PWVs and the plurality of discrete pressure levels.

4. The wearable user device of claim 3, further comprising a control system configured to implement a predictive model, the predictive model being configured to output the user's blood pressure based on input data including the plurality of PWVs and the plurality of discrete pressure levels.

5. The wearable user device according to claim 1, wherein the biometric sensor comprises: A photoacoustic sensor configured to acquire a photoacoustic signal generated from light incident on the user's blood vessels; An acoustic sensor configured to acquire acoustic signals; or both.

6. The wearable user device of claim 1, wherein the loop further comprises: An airbag configured to maintain pressure to the portion of the user at each of a plurality of discrete pressure levels based on a corresponding voltage level; and A vent, configured to close during inflation and pressure maintenance of the airbag, and to open during deflation of the airbag.

7. The wearable user device according to claim 1, wherein the wearable user device further comprises: A pressure sensor configured to detect that the pressure applied to the portion of the user has deviated from the plurality of discrete pressure levels; In response to the deviation of the pressure, the annular band is further configured to adjust the pressure to one of the plurality of discrete pressure levels.

8. The wearable user device of claim 1, wherein the pressure applied to the portion of the user at the plurality of discrete pressure levels is based on a calibrated relationship between the plurality of discrete pressure levels and corresponding voltage levels that can be applied to the ring band.

9. The wearable user device of claim 8, wherein the loop is further configured to adjust the pressure to one of the plurality of discrete pressure levels based on the calibrated relationship between the plurality of discrete pressure levels and the corresponding voltage levels in response to a deviation of the pressure applied to the portion of the user from the plurality of discrete pressure levels.

10. The wearable user device of claim 1, further comprising a pressure sensor configured to determine a current pressure applied to the portion of the user and a voltage level corresponding to the current pressure; The pressure applied to the portion of the user at the plurality of discrete pressure levels is based at least on a feedback loop that minimizes (i) the difference between the voltage level corresponding to the current pressure provided by the pressure sensor and (ii) the target voltage.

11. The wearable user device of claim 10, wherein the voltage level corresponding to the pressure applied to the portion of the user is generated at least in part using: a neural network receiving the current pressure, the voltage level corresponding to the current pressure, the current temperature associated with the ring, the target voltage, or a combination thereof.

12. The wearable user device of claim 11, further comprising a control system configured to implement fuzzy logic via the neural network to generate a voltage level corresponding to the pressure applied to the portion of the user.

13. The wearable user device according to claim 1, wherein: The plurality of data relating to the characteristics of the blood vessel include a plurality of PWVs corresponding to a respective discrete pressure level among the plurality of discrete pressure levels; and The wearable user device further includes a control system configured to determine the user's blood pressure based on the plurality of PWVs.

14. The wearable user device of claim 13, wherein the control system is further configured to determine the user's blood pressure based on a predictive model, the predictive model being configured to receive curves of the plurality of PWVs varying with the plurality of discrete pressure levels as input.

15. The wearable user device of claim 1, wherein the plurality of discrete pressure levels include pressure levels ranging from 20 mmHg to 90 mmHg (inclusive).

16. A method for determining a user's physiological parameters using a wearable user device, the method comprising: When the pressure applied to a portion of the user is at a first target pressure level at a first moment, one or more first sensor measurements are acquired from the user's blood vessels, the one or more first sensor measurements being correlated with first data on the characteristics of the blood vessels; When the pressure applied to the user's portion is at a second target pressure level at a second time, one or more second sensor measurements are acquired from the user's blood vessel, the one or more second sensor measurements being correlated with second data regarding the characteristics of the blood vessel; and The user's physiological parameters are determined based at least on the first and second data, which are based on the characteristics of the blood vessels.

17. The method of claim 16, further comprising: When the vent of the wearable user device is closed: The pressure applied to the part of the user is set as the first target pressure level by applying a first voltage corresponding to the first target pressure level to the inflatable part of the wearable user device; as well as After the first target pressure level is reached, the first voltage applied to the inflatable part is reduced to zero; The one or more first sensor measurements of the blood vessels of the user are acquired when the first voltage applied to the inflatable part is zero.

18. The method of claim 17, further comprising: After acquiring the measurements from the one or more first sensors: When the vent of the wearable user device is closed: By applying a second voltage corresponding to the second target pressure level to the inflatable portion of the wearable user device, the pressure applied to the portion of the user is set to the second target pressure level; as well as After the second target pressure level is reached, the second voltage applied to the inflatable part is reduced to zero; The one or more second sensor measurements of the blood vessels of the user are acquired when the second voltage applied to the inflatable part is zero.

19. The method of claim 16, further comprising: The operation of the loop of the wearable user device increases or decreases the pressure applied to the portion of the user during the transition period between the first time and the second time.

20. The method of claim 19, further comprising: Prevent sensor measurements during operation of the ring belt.

21. The method of claim 19, wherein the acquisition of the one or more first sensor measurements and the one or more second sensor measurements occurs when the ring is not in operation.

22. The method of claim 16, further comprising: The pressure applied to the user's portion has deviated from either the first target pressure level or the second target pressure level. as well as In response to the deviation of the pressure, the pressure applied to the portion of the user is adjusted to either the first target pressure level or the second target pressure level.

23. The method of claim 16, wherein the first data of the characteristic of the blood vessel includes a first pulse wave velocity (PWV) of the blood vessel, and the second data of the characteristic of the blood vessel includes a second PWV of the blood vessel.

24. The method of claim 16, wherein the pressure applied to the portion of the user at the first target pressure level and the second target pressure level is based on a calibrated relationship between the first target pressure level and the second target pressure level and a corresponding voltage level that can be applied to the wearable user device.

25. The method of claim 16, further comprising: Determine the current pressure applied to the portion of the user; The pressure applied to the portion of the user at the first target pressure level and the second target pressure level is based at least on a feedback loop involving (i) the difference between the current pressure and (ii) the target pressure level.

26. The method of claim 25, further comprising: A voltage level is determined to compensate for the difference between the current pressure and the target pressure level.

27. The method of claim 26, wherein the voltage level is determined by fuzzy logic, a neural network, a proportional-integral-derivative (PID) controller, or a combination thereof.

28. An apparatus comprising: A component used to apply pressure to a part of the user at multiple discrete pressure levels over multiple time periods; Components for acquiring multiple sensor measurements associated with the user's blood vessels at corresponding discrete pressure levels within corresponding time periods of the multiple time periods, the multiple sensor measurements being related to multiple data points relating to the characteristics of the user's blood vessels, the multiple data points relating to the characteristics of the blood vessels enabling the determination of the user's blood pressure; and A wearable component, the wearable component including a component for applying the pressure to the portion of the user and a component for acquiring measurements from the plurality of sensors.

29. The apparatus of claim 28, wherein: The component for applying the pressure to the portion of the user includes a component for stopping operation when the applied pressure is at one of the plurality of discrete pressure levels and a component for operating to apply the pressure during one or more transitions between two discrete pressure levels of the plurality of discrete pressure levels. and The components for acquiring the plurality of sensor measurements include components for acquiring the plurality of sensor measurements when the applied pressure is at the plurality of discrete pressure levels and for not acquiring the plurality of sensor measurements during the one or more transitions between the plurality of discrete pressure levels.

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 one or more processors, cause the device to: When the pressure applied to a portion of the user is at a first target pressure level at an immediate moment, one or more first sensor measurements are acquired from the user's blood vessels, the one or more first sensor measurements being correlated with first data on the characteristics of the blood vessels; When the pressure applied to the user's portion is at a second target pressure level at a second time, one or more second sensor measurements are acquired from the user's blood vessel, the one or more second sensor measurements being correlated with second data regarding the characteristics of the blood vessel; and The user's physiological parameters are determined based at least on the first and second data, which are based on the characteristics of the blood vessels.

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