Blood pressure measuring device and method of use thereof

Abstract

This application discloses a blood pressure measurement device and method for use thereof. It provides a device and method for measuring blood pressure using an electroacoustic transducer combined with a piezoelectric ultrasonic transducer. This device and method can provide continuous, non-invasive blood pressure monitoring.

Description

[0001] Cross-references

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 966,927, filed January 28, 2020, which is incorporated herein by reference. Background Art

[0003] Blood pressure is a fundamental vital sign routinely used to manage patient care. Methods for measuring blood pressure are often complex and cumbersome. Typical methods have several limitations, including sensitivity to ambient noise, patient discomfort, and the inability to obtain continuous blood pressure measurements. An alternative approach is invasive blood pressure measurement. While this provides higher-quality data than an external cuff, its invasive nature also carries higher risks, including infection, bleeding, or ischemia. Alternative, non-invasive methods for measuring blood pressure are highly desirable, particularly as hypertension has become an increasingly common medical problem in the United States and elsewhere in the world. Summary of the Invention

[0004] This document provides an embodiment of a blood pressure measurement device, comprising: a first transducer configured to direct sound waves into a blood vessel; and a second transducer configured to direct ultrasound waves into the blood vessel, receive ultrasound waves reflected by the echogenic boundary of the blood vessel, and measure the radius and wall thickness of the blood vessel's cross section. The first transducer may be an electroacoustic transducer and / or the second transducer may be a piezoelectric ultrasonic transducer. The device may also include an audio signal generator coupled to the first transducer. In some embodiments, the audio signal generator includes at least a variable resistor that adjusts the frequency of the sound waves. In some embodiments, the variable resistor may be a potentiometer. In some embodiments, the audio signal generator displays the frequency of the sound waves. The second transducer may monitor the vibration of the blood vessel's cross section. In some embodiments, the second transducer monitors the vibration of the blood vessel's cross section, and the piezoelectric ultrasonic transducer records the frequency of the vibration of the cross section and determines its resonant frequency. The resonant frequency may be determined when the vibration of the blood vessel's cross section is maximum. In some embodiments, the frequency of the sound waves ranges from 1 Hz to 3000 Hz. In some embodiments, the frequency of the sound waves ranges from 670 Hz to 2300 Hz. The electroacoustic transducer may be an audio speaker, and the audio speaker may be a tweeter.The blood vessel may be an artery or a vein.

[0005] Further provided herein is an embodiment of a method for measuring blood pressure, the method comprising: determining a radius and thickness of a cross-section of a blood vessel; directing an acoustic wave into the blood vessel; varying the frequency of the acoustic wave; detecting a maximum resonance of the cross-section of the blood vessel to determine the resonant frequency of the blood vessel; and calculating the blood pressure in the blood vessel based on the determined resonant frequency. Varying the frequency of the acoustic wave may include varying the frequency of the acoustic wave within a range of 1 Hz to 3000 Hz. In some embodiments, varying the frequency of the acoustic wave includes varying the frequency of the acoustic wave within a range of 670 Hz to 2300 Hz. The resonant frequency may be determined using a piezoelectric ultrasonic transducer for detecting the maximum resonance. The piezoelectric ultrasonic transducer may have a sampling rate of at least 3 kHz. In some embodiments, determining the radius and thickness of the blood vessel comprises directing an ultrasonic wave into the blood vessel and receiving a reflected ultrasonic wave reflected from an echogenic boundary of the blood vessel. In some embodiments, the method may further comprise measuring a Doppler shift of the reflected ultrasonic wave and calculating the wave velocity of the blood vessel. The Doppler shift may be measured using the piezoelectric ultrasonic transducer. The blood vessel may be an artery or a vein.

[0006] Provided herein is an embodiment of a blood pressure measurement device, comprising: a first transducer configured to emit a plurality of sound waves having a plurality of frequencies, the sound waves being configured to vibrate a blood vessel of a subject; a second transducer configured to capture one or more ultrasound images of the blood vessel; and a processing device configured to: determine a resonant frequency of the blood vessel based on the one or more captured ultrasound images; and calculate the blood pressure of the blood vessel or the subject based on the wall thickness of the blood vessel, the radius or diameter of the blood vessel, and the determined resonant frequency.

[0007] In some embodiments, one or more captured ultrasound images are used to measure the wall thickness of the blood vessel and the radius or diameter of the blood vessel. In some embodiments, the one or more captured ultrasound images include a plurality of ultrasound images, wherein determining the resonant frequency of the blood vessel includes: determining a frequency of the blood vessel that maximizes vibration of the blood vessel from a plurality of frequencies based on the plurality of ultrasound images; and selecting the frequency as the resonant frequency. In some embodiments, the device further includes: an audio signal generator electrically coupled to the first transducer, the audio signal generator configured to adjust the frequency of the sound waves emitted by the first transducer. In some embodiments, the audio signal generator includes at least one variable resistor that adjusts the frequency of the sound waves emitted by the first transducer. In some embodiments, each frequency is between 1 Hz and 3000 Hz. In some embodiments, each frequency is between 670 Hz and 2300 Hz.

[0008] In some embodiments, the blood vessel is a carotid artery of a subject. In some embodiments, the first transducer is an audio speaker. In some embodiments, the device further comprises: a substrate, wherein the substrate comprises an adhesive surface for adhering to the subject's skin, wherein the first transducer and the second transducer are incorporated into the substrate. In some embodiments, the substrate is adhered near the blood vessel. In some embodiments, the blood vessel is a carotid artery. In some embodiments, the substrate comprises an alignment line. In some embodiments, the substrate comprises a transparent window.

[0009] In some embodiments, the apparatus further comprises a third transducer configured to capture a second set of one or more ultrasound images of the blood vessel. In some embodiments, the second transducer and the third transducer each have a respective resonant frequency, and wherein the second transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer; and the processing device processes measurements taken by the first transducer and the second transducer. In some embodiments, the processing of the measurements taken by the first transducer and the second transducer comprises normalizing the first frequency response and the second frequency response.

[0010] In some embodiments, the device further comprises a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel. In some embodiments, the device further comprises a substrate, wherein the substrate comprises an adhesive surface for adhering to the subject's skin, wherein the first transducer, the second transducer, and the third transducer are incorporated into the substrate. In some embodiments, the substrate is adhered near the blood vessel. In some embodiments, the blood vessel is a carotid artery. In some embodiments, the substrate comprises an alignment line. In some embodiments, the substrate further comprises a transparent window.

[0011] In some embodiments, the apparatus further comprises a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel. In some embodiments, the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer. In some embodiments, the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer. In some embodiments, the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer and the third transducer.

[0012] In some embodiments, the device further comprises a substrate, wherein the substrate comprises an adhesive surface for adhering to the skin of a subject, wherein the first transducer, the second transducer, and the third transducer are incorporated into the substrate. In some embodiments, the substrate is adhered near a blood vessel. In some embodiments, the blood vessel is a carotid artery. In some embodiments, the substrate comprises an alignment line. In some embodiments, the substrate further comprises a transparent window.

[0013] In some embodiments, the apparatus further comprises a third transducer configured to capture a second set of one or more ultrasound images of the blood vessel. In some embodiments, the second transducer and the third transducer each have a respective resonant frequency, and wherein the second transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer; and the processing device processes the measurements taken by the first transducer and the second transducer. In some embodiments, the processing of the measurements taken by the first transducer and the second transducer comprises normalizing the first frequency response and the second frequency response.

[0014] In some embodiments, the device further comprises a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel. In some embodiments, the device further comprises a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel. In some embodiments, the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer. In some embodiments, the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer. In some embodiments, the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer and the third transducer.

[0015] According to some embodiments, the present invention provides a non-transitory computer-readable storage medium storing instructions executable by a processor, wherein execution of the instructions causes a blood pressure measurement device to perform operations including: using a first transducer near a subject's blood vessel to transmit multiple sound waves having multiple frequencies, the sound waves causing the subject's blood vessel to vibrate; determining the resonant frequency of the blood vessel based on the vibration response of the blood vessel to the multiple sound waves; determining the wall thickness and radius or diameter of the blood vessel using a second transducer that transmits ultrasonic waves; and calculating the subject's blood pressure based on the resonant frequency, the wall thickness of the blood vessel, and the radius or diameter of the blood vessel.

[0016] In some embodiments, the operations further include: using a second transducer to capture multiple ultrasound images of the blood vessel as the blood vessel vibrates in response to sound waves, wherein determining the resonant frequency of the blood vessel includes: determining the resonant frequency of the blood vessel based on the ultrasound images. In some embodiments, determining the wall thickness and radius of the blood vessel includes: using the second transducer to direct ultrasound waves into the blood vessel; and using the second transducer to receive ultrasound waves reflected from echogenic boundaries of the blood vessel. In some embodiments, after calculating the blood pressure, the operations further include: using the first transducer and the second transducer to determine an updated radius of the blood vessel and an updated velocity of blood flowing through the blood vessel; and calculating an updated blood pressure based on the updated radius and the updated velocity.

[0017] In some embodiments, the plurality of frequencies of the plurality of sound waves are between 1 Hz and 3000 Hz. In some embodiments, the plurality of frequencies of the plurality of sound waves are between 670 Hz and 2300 Hz. In some embodiments, the first transducer is an audio speaker.

[0018] In some embodiments, the operations further include capturing a first set of ultrasound images of the blood vessel using a third transducer. In some embodiments, the operations further include capturing a second set of ultrasound images of the blood vessel using a second transducer. In some embodiments, the operations further include normalizing the second set of ultrasound images by the first set of ultrasound images.

[0019] In some embodiments, the operations further include capturing a third set of ultrasound images of the blood vessel using a fourth transducer. In some embodiments, the operations further include normalizing the second set of ultrasound images by the first set of ultrasound images. In some embodiments, the operations further include normalizing the second set of ultrasound images by the third set of ultrasound images.

[0020] According to some embodiments, a method is provided herein, comprising: using a first transducer near a subject's blood vessel to transmit multiple sound waves having multiple frequencies, the sound waves causing the subject's blood vessel to vibrate; determining the resonant frequency of the blood vessel based on the vibration response of the blood vessel to the sound waves; using a second transducer that transmits ultrasonic waves to determine the wall thickness and radius or diameter of the blood vessel; and calculating the subject's blood pressure based on the resonant frequency, the wall thickness of the blood vessel, and the radius or diameter of the blood vessel.

[0021] In some embodiments, the method further comprises: capturing, using a second transducer, a plurality of ultrasound images of the blood vessel as the blood vessel vibrates in response to the sound waves, wherein determining the resonant frequency of the blood vessel comprises: determining the resonant frequency of the blood vessel based on the ultrasound images. In some embodiments, determining the wall thickness and radius of the blood vessel comprises: directing ultrasound waves into the blood vessel using the second transducer; and receiving, using the second transducer, the ultrasound waves reflected from an echogenic boundary of the blood vessel.

[0022] In some embodiments, the method further comprises: determining an updated radius of the blood vessel and an updated velocity of blood flowing through the blood vessel using the first transducer and the second transducer; and calculating an updated blood pressure based on the updated radius and the updated velocity. In some embodiments, each frequency is between 670 Hz and 2300 Hz.

[0023] In some embodiments, the method further comprises capturing, using a third transducer, a second plurality of ultrasound images of the blood vessel as the blood vessel vibrates in response to the acoustic waves. In some embodiments, the method further comprises normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer with the second plurality of ultrasound images of the blood vessel captured by the third transducer.

[0024] In some embodiments, the method further comprises capturing a third plurality of ultrasound images of the blood vessel using a fourth transducer while the blood vessel vibrates in response to the acoustic waves. In some embodiments, the method further comprises normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer using the second plurality of ultrasound images of the blood vessel captured by the third transducer. In some embodiments, the method further comprises normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer using the third plurality of ultrasound images of the blood vessel captured by the fourth transducer.

[0025] According to some embodiments, this document provides a blood pressure measurement device, which includes: a first transducer configured to guide sound waves to a blood vessel; and a second transducer configured to guide ultrasonic waves to the blood vessel, receive ultrasonic waves reflected by the echo boundary of the blood vessel, measure the diameter or radius of the cross section of the blood vessel, and measure the wall thickness of the cross section of the blood vessel.

[0026] In some embodiments, the first transducer is an electroacoustic transducer and the second transducer is a piezoelectric ultrasonic transducer. In some embodiments, the device further comprises an audio signal generator coupled to the first transducer. In some embodiments, the audio signal generator is configured to change the frequency of the sound wave. In some embodiments, the device further comprises a display. In some embodiments, the display shows the frequency of the sound wave.

[0027] In some embodiments, the second transducer monitors vibrations of a cross-section of the blood vessel. In some embodiments, the second transducer monitors vibrations of a cross-section of the blood vessel, and wherein the second transducer records a frequency of the vibrations of the cross-section and determines a resonant frequency thereof. In some embodiments, wherein the resonant frequency is determined when the vibrations of the cross-section of the blood vessel are at a maximum

[0028] In some embodiments, the frequency of the sound waves varies in the range of 1 Hz to 3000 Hz. In some embodiments, the frequency of the sound waves varies in the range of 670 Hz to 2300 Hz. In some embodiments, the electroacoustic transducer is an audio speaker. In some embodiments, the audio speaker is a tweeter.

[0029] In some embodiments, the blood vessel is an artery or a vein. In some embodiments, the first transducer and the second transducer are coupled to a substrate, and wherein the substrate includes an adhesive backing. In some embodiments, the substrate is adhered adjacent to the blood vessel. In some embodiments, the blood vessel is a carotid artery. In some embodiments, the substrate includes an alignment line. In some embodiments, the substrate includes an alignment line and a transparent window.

[0030] According to some embodiments, this document provides a method for measuring blood pressure, which includes: determining the radius and wall thickness of a cross-section of a blood vessel; guiding sound waves to the blood vessel; changing the frequency of the sound waves; detecting the maximum resonance of the cross-section of the blood vessel to determine the resonant frequency of the blood vessel; and calculating the blood pressure in the blood vessel based on the determined resonant frequency, radius, and wall thickness of the blood vessel.

[0031] In some embodiments, changing the frequency of the sound wave comprises changing the frequency of the sound wave within a range of 1 Hz to 3000 Hz. In some embodiments, changing the frequency of the sound wave comprises changing the frequency of the sound wave within a range of 670 Hz to 2300 Hz.

[0032] In some embodiments, the resonant frequency is determined using a piezoelectric ultrasonic transducer for detecting maximum resonance. In some embodiments, the piezoelectric ultrasonic transducer has a sampling rate of at least 3 kHz. In some embodiments, determining the radius and wall thickness of the blood vessel comprises directing ultrasonic waves into the blood vessel and receiving reflected ultrasonic waves reflected from the echogenic boundaries of the blood vessel. In some embodiments, the method further comprises measuring a Doppler shift of the reflected ultrasonic waves and calculating the wave velocity of the blood vessel. In some embodiments, the Doppler shift is measured by the piezoelectric ultrasonic transducer.

[0033] In some embodiments, the blood vessel is an artery or a vein. In some embodiments, the method further comprises directing the first set of transmitted ultrasonic waves toward the blood vessel and capturing the first set of reflected ultrasonic waves from the blood vessel. In some embodiments, the steps of directing the first set of transmitted ultrasonic waves toward the blood vessel and capturing the first set of reflected ultrasonic waves from the blood vessel are performed by a single ultrasonic transducer.

[0034] In some embodiments, the method further comprises directing the first set of transmitted ultrasound waves toward the blood vessel using the first ultrasound transducer, and capturing the first set of reflected ultrasound waves from the blood vessel using the second ultrasound transducer. In some embodiments, the method further comprises directing the first set of transmitted ultrasound waves toward the blood vessel using the first ultrasound transducer, and capturing the first set of reflected ultrasound waves from the blood vessel using the first ultrasound transducer and the second ultrasound transducer. In some embodiments, the method further comprises directing the first set of transmitted ultrasound waves toward the blood vessel using the first ultrasound transducer, and capturing the first set of reflected ultrasound waves from the blood vessel using the first ultrasound transducer.

[0035] In some embodiments, the method further comprises capturing a second reflected ultrasound signal from the blood vessel using a second ultrasound transducer. In some embodiments, the method further comprises normalizing the first reflected ultrasound signal with the second reflected ultrasound signal.

[0036] In some embodiments, the method further comprises capturing a third reflected ultrasound signal from the blood vessel using a third ultrasound transducer. In some embodiments, the method further comprises normalizing the first reflected ultrasound signal using the third reflected ultrasound signal. In some embodiments, the blood vessel is a carotid artery.

[0037] According to some embodiments, provided herein is a system for transmitting and receiving ultrasonic signals, the system comprising: a software-defined radio including one or more outputs and one or more inputs; an ultrasonic signal processing circuit electrically coupled to the software-defined radio; and one or more ultrasonic transducers electrically coupled to the ultrasonic signal processing circuit, wherein the ultrasonic signal processing circuit processes one or more ultrasonic transmission signals from one or more outputs of the software-defined radio and transmits the processed ultrasonic transmission signals to the one or more ultrasonic transducers to generate ultrasonic waves, and wherein a signal processing unit processes one or more received ultrasonic signals from the one or more ultrasonic transducers and transmits the processed received ultrasonic signals to the one or more inputs of the software-defined radio.

[0038] In some embodiments, the ultrasound processing circuitry includes at least one high voltage amplifier to amplify one or more ultrasound transmission signals from one or more outputs of the software defined radio. In some embodiments, the ultrasound processing circuitry includes at least one variable gain amplifier to amplify one or more received ultrasound signals from one or more ultrasound transducers.

[0039] In some embodiments, the ultrasound processing circuitry includes at least one variable gain amplifier to amplify one or more received ultrasound signals from one or more ultrasound transducers. In some embodiments, the output of the software-defined radio includes a gain ramp and a transmit pulse. In some embodiments, the ultrasound processing circuitry includes a high voltage amplifier to amplify the transmit pulse.

[0040] In some embodiments, the ultrasound processing circuit includes a variable gain amplifier to amplify one or more received ultrasound signals from the one or more ultrasound transducers based on a gain ramp transmitted by the software-defined radio. In some embodiments, the amplification rate of the ramp signal corresponds to the time since the initial pulse of the software-defined radio transmission of the ramp signal.

[0041] In some embodiments, the ultrasonic transducer includes a first pixel group and a second pixel group. In some embodiments, the first pixel group and the second pixel group each include 16 pixels. In some embodiments, the first pixel group is configured to receive the processed ultrasonic transmission signal. In some embodiments, only the first pixel group receives the processed ultrasonic transmission signal.

[0042] In some embodiments, one or more received ultrasound signals are received by the first pixel group and the second pixel group and transmitted to the ultrasound processing circuit. In some embodiments, the variable gain amplifier is a low noise, single-ended, linear, universal variable gain amplifier.

[0043] In some embodiments, the ultrasound transducer includes a first pixel group and a second pixel group. In some embodiments, the first pixel group is configured to receive a processed ultrasound transmission signal. In some embodiments, the first pixel group receives the processed ultrasound transmission signal.

[0044] In some embodiments, the system further comprises a computing device coupled to the software-defined radio such that the computing device controls one or more outputs of the software-defined radio. In some embodiments, the computing device comprises a display, wherein the display displays data received by the one or more inputs of the software-defined radio. In some embodiments, the display displays one or more ultrasound images acquired by the one or more ultrasound transducers.

[0045] In some embodiments, the system further comprises a computing device connected to the software-defined radio such that the computing device controls one or more outputs of the software-defined radio. In some embodiments, the computing device comprises a display, wherein the display displays data received by one or more inputs of the software-defined radio.

[0046] The system of claim 123, wherein the display displays one or more ultrasound images obtained by one or more ultrasound transducers.

[0047] According to some embodiments, provided herein is a method of conditioning one or more ultrasonic signals, the method comprising: receiving a first transmission signal from a software-defined radio; amplifying the first transmission signal to form an amplified transmission signal; forwarding the amplified transmission signal to one or more ultrasonic transducers with a first multiplexer; receiving one or more received ultrasonic signals from the one or more ultrasonic transducers with the first multiplexer; and amplifying the one or more received ultrasonic signals to form one or more amplified received ultrasonic signals.

[0048] In some embodiments, amplification of the one or more received ultrasound signals is based on a gain ramp of a radio transmission defined by software. In some embodiments, amplification is time-dependent. In some embodiments, amplification of the one or more received ultrasound signals is performed by one or more low-noise, single-ended, linear, general-purpose variable gain amplifiers. In some embodiments, amplification of the one or more received ultrasound signals is performed by one or more low-noise, single-ended, linear, general-purpose variable gain amplifiers.

[0049] In some embodiments, the method further comprises transmitting one or more ultrasonic waves toward at least one object, wherein the at least one object reflects the one or more ultrasonic waves, and wherein the reflected ultrasonic waves are detected by the one or more ultrasonic transducers and form one or more received ultrasonic signals.

[0050] In some embodiments, the amplification of the one or more received ultrasound signals is based on a gain ramp transmitted by the radio defined by software. In some embodiments, the amplification is time-dependent. In some embodiments, the amplification of the one or more received ultrasound signals is performed by one or more low-noise, single-ended, linear, general-purpose variable gain amplifiers.

[0051] In some embodiments, at least one object is a blood vessel of the subject. In some embodiments, the blood vessel is a carotid artery. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the invention will be obtained by reference to the following detailed description which sets forth illustrative embodiments in which the principles of the invention are utilized, and the accompanying drawings (also referred to herein as "drawings" and "figures"), in which:

[0053] Figure 1 depicts forces acting on an arterial membrane according to some embodiments;

[0054] Figure 2 depicts vibrations of an arterial wall at a resonant frequency according to some embodiments;

[0055] Figure 3 is a block diagram illustrating some components of a continuous blood pressure measurement device according to some embodiments of the present disclosure;

[0056] Figure 4 depicting echogenic boundaries of an arterial wall according to some embodiments;

[0057] Figure 5 An adhesive patch including an integrated continuous blood pressure measurement device according to some embodiments is described;

[0058] Figure 6 is an operational flow chart illustrating an example method for measuring blood pressure of a subject, according to some embodiments;

[0059] Figure 7A-7B depicts the frequency responses of three ultrasonic sensors of a continuous ultrasonic measurement device according to some embodiments;

[0060] Figures 8A-8D Describes techniques for cross-correlation in ultrasonic measurement equipment;

[0061] Figure 9depicts a block diagram illustrating an example system according to some embodiments;

[0062] Figure 10 A computer system programmed or otherwise configured to implement the methods provided herein according to some embodiments is described;

[0063] Figure 11 A method of forming an ultrasound image from a plurality of ultrasound transducers according to some embodiments is shown; and

[0064] Figure 12 Example chip sets are described that can be used to implement the architecture and methods according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0065] Provided herein is a device capable of continuous, non-invasive blood pressure measurement. In some embodiments, the device includes one or more ultrasonic transducers. In some embodiments, the device presented herein eliminates the need for a calibration step and provides continuous, non-invasive blood pressure monitoring capabilities in an inexpensive and easy-to-use form.

[0066] According to some embodiments, the technology disclosed herein is directed to a blood pressure measurement device that is capable of continuous, non-invasive blood pressure measurement using sound and ultrasonic transducers. In some embodiments, an electroacoustic transducer is used to generate an audio signal that stimulates vibrations in an artery. By varying the frequency of the acoustic signal, the resonant frequency at which the artery vibrates most strongly can be determined. This resonant frequency can be combined with a measurement of the artery radius to calculate absolute blood pressure. In some embodiments, the radius of the artery is measured by one or more ultrasonic transducers using ultrasound imaging methods. Methods of measuring blood pressure using acoustic stimulation can eliminate the need for a separate calibration step and can provide blood pressure monitoring in an inexpensive and easy-to-use form.

[0067] To understand the basic principles of the technology described herein, it is helpful to consider the potential forces of blood flowing through an artery. Figure 1 Depicted is an arterial wall 110, which can be represented as a tube made of elastic material. The dynamics of arterial wall 110 are governed by the balance between blood pressure 120, which pushes the wall out, and tension 130, which holds the wall together. Laplace's law states that for a fluid flowing through a cylindrical elastic membrane with a constant radius R, the fluid pressure P and the tension T in the membrane are related by the equation T=RP.

[0068] The radius of the artery can be measured using one or more ultrasound devices. Therefore, the remaining task for determining the fluid pressure P is to measure the tension in the wall of the artery. In some embodiments, the tension can be determined by measuring how the arterial wall responds to pulses from an acoustic stimulus. Figure 2This process is depicted. In some embodiments, acoustic stimuli 240 generated by an electroacoustic transducer 250 are used to induce measurable perturbations in the arterial wall 210. This method can utilize acoustic stimuli emitted at acoustic intensities well below the acoustic intensity limits set by FDA guidelines. By focusing on the vibrational modes surrounding the artery, particularly the lowest energy vibrations that can be excited around it, tension can be estimated as follows.

[0069] The lowest energy vibration has a wavelength of λ = πR. The mechanical properties of the arterial wall also govern the velocity v ω , the vibration propagates along the circumference of the wall at this speed. The wave speed and wavelength are combined to produce the resonant frequency f = v ω / λ. If an external stimulus (e.g., a sound wave) is applied at frequency f, the wall will vibrate very strongly, but if the frequency of the stimulus is varied away from f, the amplitude of the vibration will decrease. Therefore, f can be determined by applying an acoustic stimulus over a range of frequencies and finding the frequency at which the artery vibrates most strongly. This, in turn, will tell us the wave velocity v w =λf=πRf. In an elastic material under tension, with bulk density ρ and thickness h, this wave velocity is related to the tension by the following equation: T=ρhv w 2 The volume density of the arterial wall is nearly constant between patients, and the wall thickness can be measured from ultrasound images in the same way as R. Using this information, the pressure can be determined based on equation (1):

[0070] P=T / R=ρhv w 2 / R=π 2 ρhRf 2 (1)

[0071] Therefore, measuring h and R via standard ultrasound imaging and measuring f by determining the resonance point of the artery's vibration response will allow blood pressure to be calculated.

[0072] 1. Feasibility analysis.

[0073] To demonstrate the feasibility of the continuous blood pressure measurement technique described in this article, the following factors can be considered. First, to demonstrate the practicality of this blood pressure measurement method, it is necessary to ensure that the resonant frequency f is a reasonable value in a typical patient. In the common carotid artery, the values ​​of the measured quantities are typically: P is approximately 100 mmHg, R is 2.5 mm, h is 0.3 mm, and p is 1 g / mL. Substituting these values ​​into equation (1) yields a predicted resonant frequency of approximately 1.3 kHz. Therefore, to detect this vibration, sampling of at least ~3 kHz may be required to exceed the Nyquist rate. Currently available ultrasound devices can produce imaging rates of at least 8 kHz, far exceeding the minimum sampling rate. 1.3 kHz is also far higher than the heart rate, which, even under extreme conditions, does not exceed 5 Hz in human patients. Because the resonance occurs at a frequency much higher than the rate of pressure change during the heartbeat, the blood pressure (and thus the tension) can be assumed to be constant for the duration of each vibration cycle, greatly simplifying the analysis. Furthermore, 1.3 kHz falls comfortably within the range of existing commercially available loudspeakers, so no specialized hardware is required to produce tones of sufficient amplitude and frequency to stimulate arterial vibrations.

[0074] Second, another measure of feasibility is the frequency range in which the electroacoustic transducer may need to operate. Under extreme conditions, a patient's blood pressure may be as low as 25 mmHg or as high as 300 mmHg. Using the artery dimensions given above, this corresponds to a resonant frequency range of 670 Hz to 2.3 kHz, still within the acoustic range produced by commercially available speakers.

[0075] Third, one can also consider the level of frequency resolution required to achieve a useful level of accuracy in pressure measurements. To be comparable to the current clinical gold standard for continuous blood pressure measurement, a blood pressure measurement device should be able to measure pressure with an accuracy of at least ±5 mmHg. Based on the arterial dimensions given above, blood pressure fluctuations of this magnitude would result in a change in the resonant frequency of ±34 Hz, or approximately 2.5%. This level of accuracy can also be readily achieved with commercially available loudspeakers.

[0076] Figure 3is a block diagram illustrating some components of a continuous blood pressure measurement device 300 according to some embodiments of the present disclosure. As shown, the device 300 includes an audio signal generator 305, an electroacoustic transducer 310, at least one ultrasonic sensor 320, at least one processing device 330, at least one machine-readable medium 340, a wireless transmitter 315, and optionally, one or more non-ultrasonic sensors 360. The electrical components of the device 300 can be powered by a battery 301, which is connected to a power supply circuit 302 for distributing power. The battery 301 can be rechargeable (e.g., via a USB port and / or an AC / DC converter). Although a battery 301 is shown in this example, it should be understood that any suitable battery or power supply technology can be used to power the components of the device 300. For example, lithium-ion batteries, single-cell batteries, piezoelectric or vibration energy harvesters, photovoltaic cells, AC / DC sources, or other similar devices can be used.

[0077] The electroacoustic transducer 310 can be implemented as an audio speaker that can output sound waves within a suitable frequency range (e.g., to find the resonant frequency of the blood vessels). For example, the speaker can be implemented as a woofer, a midrange speaker, and / or a treble speaker (e.g., a tweeter). In some embodiments, a combination of speakers can be used to output sound within a suitable frequency range. An audio signal generator 305 that adjusts the frequency of the sound waves can be coupled to the transducer 310. In some embodiments, the audio signal generator includes at least a variable resistor that adjusts the frequency of the sound waves. The variable resistor can be a potentiometer. In some embodiments, the blood pressure measurement device 300 can display the frequency of the sound waves. In some embodiments, the audio signal generator 305 is a component of the processing device 330.

[0078] In some embodiments, the sound waves output by the electroacoustic transducer 310 can be configured to vary in a frequency range from about 100 Hz to about 3,500 Hz. In one embodiment, the frequency range of the electroacoustic transducer 310 varies from about 100 Hz to about 500 Hz, about 100 Hz to about 1,000 Hz, about 100 Hz to about 1,500 Hz, about 100 Hz to about 2,000 Hz, about 100 Hz to about 2,500 Hz, about 100 Hz to about 3,000 Hz, about 100 Hz to about 3,500 Hz, about 500 Hz to about 1,000 Hz, about 500 Hz to about 1,500 Hz, about 500 Hz to about 2,000 Hz, about 500 Hz to about 2,500 Hz, about 500 Hz to about 3,000 Hz, about 500 Hz to about 3,500 Hz, about 1,000 Hz to about 1,500 Hz , about 1,000 Hz to about 2,000 Hz, about 1,000 Hz to about 2,500 Hz, about 1,000 Hz to about 3,000 Hz, about 1,000 Hz to about 3,500 Hz, about 1,500 Hz to about 2,000 Hz, about 1,500 Hz to about 2,500 Hz, about 1,500 Hz to about 3,000 Hz, about 1,500 Hz to about 3,500 Hz, about 2,000 Hz to about 2,500 Hz, about 2,000 Hz to about 3,000 Hz, about 2,000 Hz to about 3,500 Hz, about 2,500 Hz to about 3,000 Hz, about 2,500 Hz to about 3,500 Hz, or about 3,000 Hz to about 3,500 Hz. In some embodiments, the frequency range of electroacoustic transducer 310 varies between about 100 Hz, about 500 Hz, about 1,000 Hz, about 1,500 Hz, about 2,000 Hz, about 2,500 Hz, about 3,000 Hz, or about 3,500 Hz. In some embodiments, the frequency range of electroacoustic transducer 310 varies between at least about 100 Hz, about 500 Hz, about 1,000 Hz, about 1,500 Hz, about 2,000 Hz, about 2,500 Hz, or about 3,000 Hz. In some embodiments, the frequency range of electroacoustic transducer 310 varies between at most about 500 Hz, about 1,000 Hz, about 1,500 Hz, about 2,000 Hz, about 2,500 Hz, about 3,000 Hz, or about 3,500 Hz.

[0079] In some embodiments, the audio signal generator 305 can be configured to adjust the frequency of the sound wave output by the transducer 310 in appropriate increments in order to search for the resonant frequency of the vibration with sufficient accuracy. For example, the frequency can be adjusted in increments between 1 Hz and 500 Hz (such as 1 Hz, 5 Hz, 10 Hz, 25 Hz, 50 Hz, 100 Hz, 200 Hz, 500 Hz, etc.). The accuracy of the estimated resonant frequency can be improved by reducing the size of each increment. Conversely, the time it takes to determine the resonant frequency can be improved by increasing the size of each increment.

[0080] One or more ultrasonic sensors 320 (individually referred to as "ultrasonic sensor 320") are configured to collect imaging data of a subject (e.g., a blood vessel of the subject). The imaging data can be used to measure the wall thickness of the blood vessel and the radius of the blood vessel. The blood vessel can be an artery or a vein. In addition, the imaging data can be used to determine the resonant frequency of the vibration of the blood vessel, which vibrates in response to the sound waves output by the electroacoustic transducer 310. Each ultrasonic sensor 320 includes a transducer that is configured to convert electricity into ultrasound and vice versa. For example, the transducer can be a piezoelectric transducer that oscillates and generates ultrasonic pulses when an alternating current voltage is applied. Alternatively, the transducer can be a capacitive transducer that uses an electrostatic field between a conductive diaphragm and a backplate to generate ultrasonic waves. The ultrasonic sound waves can be generated at a frequency greater than or equal to about 20 kilohertz (KHz). In some embodiments, the transducer of the ultrasonic sensor 320 can generate ultrasound at any frequency between 2 megahertz (MHz) and 20 MHz. When the transducer receives a reflected ultrasound signal (ie, an "echo"), an electrical signal may be generated and used by the ultrasound sensor 120 to determine the distance to the imaged subject. In some embodiments, the transducer may generate ultrasound at a frequency between 7 MHz and 11 MHz.

[0081] In some embodiments, ultrasound measurements are performed using only a single piezoelectric element. Ultrasound waves in the body are primarily reflected by sharp boundaries between regions of different densities. Many arteries (including the carotid artery) are embedded in soft tissue of relatively uniform density, so the only significant source of echoes is the boundary 460 formed by the inner and outer edges of the arterial wall 410, as shown in FIG. Figure 4 By measuring the delays between the echoes received from these different boundaries, accurate determination of arterial radius and wall thickness from a single piezoelectric ultrasound transducer element 450 can be achieved.

[0082] like Figure 2As depicted, when an acoustic stimulus 240 is applied to an artery (e.g., using a tweeter), the resulting vibrations will cause the artery diameter, observed using ultrasound imaging, to oscillate sinusoidally as it expands and contracts along an axis perpendicular to the incident sound wave. If the power of the stimulus is kept constant, the oscillations will have a maximum amplitude when the stimulus is applied at a frequency that matches the resonant frequency of the arterial wall 210. Therefore, the resonant frequency can be determined by applying the acoustic stimulus over a range of frequencies and determining, via ultrasound imaging, the point at which the observed oscillation amplitude is maximum. Using this setup, the wall velocity can also be determined independently of its location by measuring the Doppler shift of the return echo. Since the wall velocity will also be maximized at resonance, the velocity measurement will provide an orthogonal method for determining the resonance point, thereby improving accuracy.

[0083] In another embodiment, accuracy can be increased by increasing the number of ultrasound piezoelectric elements. In some embodiments, four piezoelectric elements can be utilized. One piezoelectric element can generate the ultrasound signal, while the other three piezoelectric elements listen for echoes, thereby triangulating the echoes as they are received. This embodiment can allow for better rejection of false echoes, thereby providing better isolation of echoes generated by the arterial wall.

[0084] Ultrasound entering tissue can be transmitted, attenuated, or reflected. While higher-frequency ultrasound can provide a higher-resolution signal, it can also provide poorer deep penetration into the imaged tissue. Conversely, while lower-frequency ultrasound can provide a lower-resolution signal, it can provide better deep penetration into the imaged tissue. To overcome these limitations, some embodiments may use multiple ultrasound sensors 320, each with a transducer configured with a unique resonant frequency. Specifically, the ultrasound transducers can be selected so that their acoustic frequency responses are non-overlapping. By actuating the transducers in a time-staggered manner, each transducer can be used to image the sample's surface at a unique depth. Furthermore, each transducer can be actuated simultaneously with a combination of other transducers to generate higher-order harmonics that enable sub-pixel feature resolution. In some embodiments, ultrasound transducers can be selected with frequency responses that are near and partially overlap in frequency response, allowing measurements from any pair of sensors to be normalized, thereby reducing system noise sources and significantly improving signal integrity. Furthermore, transducers with different resonant frequencies can be used to simultaneously interrogate a surface to generate super-resolution ultrasound images. In some embodiments, the frequency overlap between transducers can be configured to be approximately 200 kHz or less. In some embodiments, the frequency overlap between sensors can be configured such that the frequency response range of one ultrasonic sensor does not overlap with the resonant frequency of another ultrasonic sensor, where the resonant frequency of an ultrasonic sensor can refer to the operating frequency at which the transducer most efficiently converts electrical energy into mechanical energy.

[0085] Processing device 330 can be configured to control the operation of components of device 300, including audio signal generator 305 (which, in some embodiments, is a component of processing device 130), electroacoustic transducer 310, ultrasonic sensor(s) 320, and non-ultrasonic sensor(s) 360 (discussed further below). For example, processing device 330 can be configured to cause electroacoustic transducer 310 to emit sound at a specific frequency or frequency range. Furthermore, processing device 330 can be configured to cause ultrasonic sensor 320 and / or non-ultrasonic sensor(s) 360 to perform image acquisition. Furthermore, processing device 330 can receive, store (e.g., in machine-readable medium 340), and / or process signal measurements received from ultrasonic sensor 320 and / or non-ultrasonic sensor 360. In some embodiments, processing device 330 can also be configured to use the signal measurements received from ultrasonic sensor 320 to continuously measure blood pressure in an artery or other blood vessel. Processing device 330 can apply the above-described methods by executing instructions stored on machine-readable medium 340. In one embodiment, processing device 330 may be implemented as a single integrated circuit (IC) microcontroller that includes memory (eg, machine-readable medium 340 ) for storing program information and data.

[0086] As described above, the continuous blood pressure measurement device 300 can accurately determine blood pressure based solely on arterial radius, wall thickness, and resonant frequency. However, these three values ​​are not the only information that can be determined. In some embodiments, in the process of measuring the vibration response of the artery over a certain frequency range, additional information can be obtained, including: the strength and width of the resonance peak, the baseline excitation level at low frequencies, and / or the excitation level of high-energy vibration modes. Changes in these parameters can also be observed during the heartbeat as blood pressure and tension levels change. Ultrasonic imaging of the arteries can also produce information about the echogenicity of the arterial walls, which can provide insights into the levels of calcification and plaque accumulation. All of this additional information can be used to refine calculations, achieve better accuracy, and / or provide additional information about the patient's overall health.

[0087] In some embodiments, the continuous blood pressure measurement device 300 may include one or more non-ultrasonic sensors 360 to allow multimodal measurement of other health indicators besides blood pressure. For example, an LED light source and a photodiode receiver may be integrated into a wireless platform to measure blood oxygenation via a pulse oximeter. Other example sensors that may be implemented include sensors for detecting fluid status, ejection fraction of the heart, or other vital measurements may be integrated into the hardware / sensor package. In some embodiments, measurements taken using the non-ultrasonic sensors 360 may be correlated and normalized with ultrasonic measurements used to calculate blood pressure. By using additional modalities in addition to the ultrasonic sensor 320 to measure blood pressure, the accuracy of the device 300 may be improved.

[0088] exist Figure 3 In the example of , the continuous blood pressure measurement device 300 includes a wireless transmitter 315 (e.g., a transceiver) configured to transmit ultrasound measurement data to a wireless receiver 355 (e.g., a transceiver) of a display system 350. Depending on the ultrasound imaging application, the received ultrasound measurement data can be processed using a processing device 352 of the display system 355 (e.g., in a format suitable for display) and / or displayed using a display 354. Instructions for formatting can be stored on a machine-readable medium 356. For example, the display 354 can be a component of a heart monitor, a mobile device (e.g., a smartphone or a head-mounted display), or some other suitable display device. The display 354 can also display the frequency of the sound waves that the electroacoustic transducer 310 is configured to transmit (e.g., via the audio signal generator 305). The wireless communication link between the wireless transmitter 315 and the wireless receiver 355 can be a radio frequency link, such as or Low Energy (LE) links, In some embodiments, data transmission between the device 300 and the display system 350 can be implemented using a wired transmitter or other suitable wired interface. For example, data can be transmitted using a USB-C connector, a USB 2.x or 3.x connector, a micro USB connector, a Thunderbolt connector, an Ethernet cable, etc.

[0089] In some embodiments, the functionality of the display 354 and / or display system 350 can be integrated into the continuous blood pressure measurement device 300. In some embodiments, the continuous blood pressure measurement device 300 can still retain the transmitter 315 to transmit historical or current blood pressure measurement data to an external device (such as a smartphone).

[0090] Figure 6is an operational flow chart illustrating an example method 600 for measuring blood pressure of a subject, according to some embodiments of the present disclosure. In some embodiments, method 600 may be implemented using the continuous blood pressure measurement device 300 described above.

[0091] At operation 610, the ultrasonic transducer and the electroacoustic transducer are brought near a blood vessel of a subject. For example, the continuous blood pressure measurement device 300 including the electroacoustic transducer 310 and the ultrasonic sensor 320 can be brought near an artery (e.g., a carotid artery or a brachial artery) of the patient. In some embodiments, the substrate 500 including the device 300 can be aligned with the subject's artery and then adhered. For example, the substrate 500 can be adhered to the vicinity of the brachial artery of the patient's arm. Alternatively, the substrate can be adhered to the vicinity of the carotid artery of the patient's neck. In some embodiments, the position of the ultrasonic transducer and the electroacoustic transducer (e.g., the device 300 or the substrate 500) can be adjusted to maximize the amplitude and / or signal-to-noise ratio of the measurement signal.

[0092] At operation 620, the electroacoustic transducer is actuated to emit a plurality of sound waves having a plurality of frequencies. For example, the audio signal generator 305 can be configured to cause the electroacoustic transducer 310 to emit sound waves at a plurality of different frequencies. The sound waves can generate a vibration response in the blood vessel (e.g., in a cross-section of the blood vessel to which the sound waves are directed). The vibration response can have an amplitude that varies depending on the frequency of the sound waves.

[0093] In some embodiments, the frequency of each sound wave can be between 1 Hz and 3000 Hz. In some embodiments, the frequency of each sound wave can be between 670 Hz and 2300 Hz. In some embodiments, the frequency of each sound wave is about 300 Hz to about 3,000 Hz. In some embodiments, the frequency of each sound wave is about 1 Hz to about 3,000 Hz. In some embodiments, the frequency of each sound wave is from about 1 Hz to about 300 Hz, from about 1 Hz to about 500 Hz, from about 1 Hz to about 750 Hz, from about 1 Hz to about 1,000 Hz, from about 1 Hz to about 1,500 Hz, from about 1 Hz to about 2,000 Hz, from about 1 Hz to about 2,500 Hz, from about 1 Hz to about 3,000 Hz, from about 300 Hz to about 500 Hz, from about 300 Hz to about 750 Hz, from about 300 Hz to about 1,000 Hz, from about 300 Hz to about 1,500 Hz, from about 300 Hz to about 2,000 Hz, from about 300 Hz to about 2,500 Hz, from about 300 Hz to about 3,000 Hz, from about 500 Hz to about 750 Hz, from about 500 Hz to about 1,000 Hz, from about 500 Hz to about 1,500 Hz, from about 500 Hz to about 2,000 Hz, about 500 Hz to about 2,500 Hz, about 500 Hz to about 3,000 Hz, about 750 Hz to about 1,000 Hz, about 750 Hz to about 1,500 Hz, about 750 Hz to about 2,000 Hz, about 750 Hz to about 2,500 Hz, about 750 Hz to about 3,000 Hz, about 1,000 Hz to about 1,500 Hz, about 1,000 Hz to about 2,000 Hz, about 1,000 Hz to about 2,500 Hz, about 1,000 Hz to about 3,000 Hz, about 1,500 Hz to about 2,000 Hz, about 1,500 Hz to about 2,500 Hz, about 1,500 Hz to about 3,000 Hz, about 2,000 Hz to about 2,500 Hz, about 2,000 Hz to about 3,000 Hz, or about 2,500 Hz to about 3,000 Hz. In some embodiments, the frequency of each sound wave is about 1 Hz, about 300 Hz, about 500 Hz, about 750 Hz, about 1,000 Hz, about 1,500 Hz, about 2,000 Hz, about 2,500 Hz, or about 3,000 Hz. In some embodiments, the frequency of each sound wave is at least about 1 Hz, about 300 Hz, about 500 Hz, about 750 Hz, about 1,000 Hz, about 1,500 Hz, about 2,000 Hz, or about 2,500 Hz. In some embodiments, the frequency of each sound wave is at most about 300 Hz, about 500 Hz, about 750 Hz, about 1,000 Hz, about 1,500 Hz, about 2,000 Hz, about 2,500 Hz, or about 3,000 Hz.

[0094] In some embodiments, the frequency of each sound wave is from about 1 KHz to about 3,000 KHz. In some embodiments, the frequency of each sound wave is from about 1 KHz to about 3,000 KHz. In some embodiments, the frequency of each sound wave is from about 1 KHz to about 250 KHz, from about 1 KHz to about 750 KHz, from about 1 KHz to about 1,000 KHz, from about 1 KHz to about 1,250 KHz, from about 1 KHz to about 1,500 KHz, from about 1 KHz to about 1,750 KHz, from about 1 KHz to about 2,000 KHz, from about 1 KHz to about 2,250 KHz, from about 1 KHz to about 2,500 KHz, from about 1 KHz to about 2,750 KHz, from about 1 KHz to about 3,000 KHz, from about 250 KHz to about 750 KHz, from about 250 KHz to about 1,000 KHz, from about 250 KHz to about 1 , 250KHz, about 250KHz to about 1,500KHz, about 250KHz to about 1,750KHz, about 250KHz to about 2,000KHz, about 250KHz to about 2,250KHz, about 250KHz to about 2,500KHz, about 250KHz to about 2,750KHz, about 250KHz to about 3,000KHz, about 750KHz to about 1,000KHz, about 750KHz to about 1,250KHz, about 750KHz to about 1,500KHz, about 750KHz to about 1,750KHz, about 750KHz to about 2,000KHz, about 750KHz to about 2,250KHz, about 750KHz to 2,500KHz, about 750KHz to about 2,750KHz, about 750KHz to about 3,000KHz, about 1,000KHz to about 1,250KHz, about 1,000KHz to about 1,500KHz, about 1,000KHz to about 1,750KHz, about 1,000KHz to about 2,000KHz, about 1,000KHz to about 2,250KHz, about 1,000KHz to about 2,500KHz, about 1,000KHz to about 2,750KHz, about 1,000KHz to about 3,000KHz, about 1,250KHz to about about 1,500 KHz, about 1,250 KHz to about 1,750 KHz, about 1,250 KHz to about 2,000 KHz, about 1,250 KHz to about 2,250 KHz, about 1,250 KHz to about 2,500 KHz, about 1,250 KHz to about 2,750 KHz, about 1,250 KHz to about 3,000 KHz, about 1,500 KHz to about 1,750 KHz, about 1,500 KHz to about 2,000 KHz, about 1,500 KHz to about 2,250 KHz, about 1,500 KHz to about 2,500 KHz, about 1,500 KHz to about 2,750 KHz, about 1,500KHz to about 3,000KHz, about 1,750KHz to about 2,000KHz, about 1,750 to about 2,250KHz, about 1,750KHz to about 2,500KHz, about 1,750KHz to about 2,750KHz, about 1,750KHz to about 3,000KHz, about 2,000KHz to about 2,250KHz, about 2,000KHz to about 2,500KHz, about 2, In some embodiments, the frequency of each sound wave is about 1 KHz, about 250 KHz, about 750 KHz, about 1,000 KHz, about 1,250 KHz, about 1,500 KHz, about 1,750 KHz, about 2,000 KHz, about 2,250 KHz, about 2,500 KHz, about 2,750 KHz, or about 3,000 KHz. In some embodiments, the frequency of each sound wave is at least about 1 KHz, about 250 KHz, about 750 KHz, about 1,000 KHz, about 1,250 KHz, about 1,500 KHz, about 1,750 KHz, about 2,000 KHz, about 2,250 KHz, about 2,500 KHz, or about 2,750 KHz. In some embodiments, the frequency of each sound wave is at most about 250 KHz, about 750 KHz, about 1,000 KHz, about 1,250 KHz, about 1,500 KHz, about 1,750 KHz, about 2,000 KHz, about 2,250 KHz, about 2,500 KHz, about 2,750 KHz, or about 3,000 KHz.

[0095] At operation 630, based on the vibrational response of the blood vessel to the acoustic waves at each of the plurality of different frequencies, a resonant frequency of the blood vessel's vibration may be determined (e.g., based on the frequency that produces the greatest response amplitude). In some embodiments, the resonant frequency may be held for a moment and then recorded in a memory (e.g., in computer-readable medium 340).

[0096] In some embodiments, an ultrasound sensor is configured to detect a resonant frequency by capturing images of a blood vessel (e.g., a cross-section) as the blood vessel vibrates in response to different applied frequencies. The frequency that produces the highest vibration amplitude can be selected as the resonant frequency (e.g., by a processing device communicatively coupled to the sensor). In some embodiments, the ultrasound transducer has a sampling rate of at least 3 kHz.

[0097] In some embodiments, the electroacoustic transducer and the ultrasonic sensor can be placed adjacent to each other and driven synchronously. For example, a small speaker can be placed on either side of the ultrasonic sensor, and the two devices / components can be driven synchronously.

[0098] In some embodiments of operations 620 and 630, in order to improve the speed of finding the resonant frequency, an optimized search algorithm can be used to adjust the frequency of the sound wave output by the electroacoustic transducer between the measured values. The search algorithm can utilize suitable boundary conditions (e.g., maximum frequency, minimum frequency, frequency adjustment rate, etc.). The search algorithm can start with a wide frequency scan over a large frequency range, which uses the large frequency changes between the measured values ​​to find the narrower frequency range where the resonant peak is located, and then transition to a narrow frequency scan within this narrower frequency range to find the resonant frequency. In some embodiments, the resonant frequency can be held for a moment and then recorded in a memory (e.g., in computer-readable medium 340).

[0099] At operation 640, the wall thickness and radius of the blood vessel are determined (e.g., for a cross section). These parameters can be determined from an ultrasound image captured using the ultrasound sensor 320. For example, echo mode ultrasonography can be used to determine the wall thickness and radius. Ultrasound waves can be directed to the blood vessel and ultrasound waves reflected from the echogenic boundaries of the blood vessel can be received. The Doppler shift of the reflected ultrasound waves can be measured using the ultrasound sensor, and the wave velocity of the blood vessel can be calculated based on the Doppler shift. In some embodiments, multiple ultrasound transducers can be used to improve imaging accuracy and / or speed. For example, one transducer can generate an ultrasound signal while the other three transducers listen for echoes, thereby triangulating the echoes as they are received.

[0100] At operation 650, blood pressure is calculated based on the resonant frequency, wall thickness, and radius. The calculated blood pressure can establish a baseline diastolic pressure. Once the absolute diastolic pressure is established, the changes in blood pressure over time can be measured with (one or more) ultrasonic sensors (e.g., using Doppler ultrasound imaging) to extract a continuous waveform. When this type of differential measurement is used, a small but persistent inaccurate drift can aggregate into a large drift over many heartbeats. Therefore, it may be necessary to periodically reset the baseline to maintain accuracy for patients under long-term monitoring. This demonstrates another advantage of the proposed method; while other baseline techniques would require repeated application of an external pressure cuff or force probe, using the method of this article, baseline setting can be performed automatically at regular intervals using an electroacoustic transducer and the same ultrasound hardware used to perform continuous monitoring.

[0101] In some embodiments, the device 300 or the external display system 350 can display the calculated blood pressure over time.In some embodiments, the processing device 330 of the continuous blood pressure measurement device 300 can perform the necessary DSP and calculations to obtain the patient's blood pressure.

[0102] In some embodiments, the electroacoustic transducer can be omitted, and acoustic signals of different frequencies can be generated by pulsing the ultrasound transducer at different frequencies to deliver energy to the blood vessel. This alternative design may have the advantage of using a single transducer to both generate a resonant response and capture ultrasound imaging data.

[0103] In some embodiments, the system includes an ultrasound platform for driving one or more ultrasound transducers. In some embodiments, the ultrasound platform processes and / or conditions signals received by the one or more ultrasound transducers.

[0104] 2. Adhesive patch monitoring equipment

[0105] In some embodiments, Figure 5 As depicted, the continuous blood pressure measurement device 500 can be incorporated into a substrate 510. As shown, the device 500 can include one or more alignment lines 565 or other markings for aligning one or more sensors or transducers 520, 530, 540, 550 of the device 500 with the patient's artery before actuating the transducer 310 and taking an ultrasound measurement. In some embodiments, a transparent window 575 is provided for aligning one or more sensors or transducers 520, 530, 540, 550 of the device 500 with the patient's artery before actuating the transducer 310 and taking an ultrasound measurement. In some embodiments, the device can include a transparent window 575 for viewing the artery behind the substrate during placement. The combination of the transparent window and the alignment markings can further facilitate placement of the device.

[0106] In addition, the substrate 510 may include an adhesive for holding the substrate in place and aligned with the patient's artery. During application, the adhesive can be exposed by peeling off the paper backing. The adhesive may include a rubber, acrylic, or acrylic blend adhesive. In some embodiments, the device can be placed on the patient's neck to measure blood pressure through the carotid artery. Similar measurements can be made on the radial or ulnar arteries. With some embodiments, the measurement of blood pressure can be non-invasive, reliable, rapid, and provide continuous measurements, thereby taking into account beat-to-beat variations. As described above, these continuous variations can be presented to the user on the display system 350.

[0107] In some embodiments, the sensors and transducers of device 500 include at least one ultrasonic transducer and at least one electroacoustic transducer. Including more than one ultrasonic transducer can allow for increased resolution as described herein. In some embodiments, the device includes two ultrasonic transducers and one electroacoustic transducer. In some embodiments, the patch includes three ultrasonic transducers and one electroacoustic transducer. In some embodiments, the patch includes four ultrasonic transducers. Each transducer 520, 530, 540, 550 can be configured as a transmitter, a receiver, or both a transmitter and a receiver (transceiver). In some embodiments, transducer 520 is configured as a transmitter and transducer 540 is configured as a receiver. In some embodiments, transducer 520 is configured as a transmitter and transducer 530 is configured as a receiver. In some embodiments, transducer 520 is configured as a transmitter and transducer 550 is configured as a receiver. In some embodiments, transducer 530 is configured as a transmitter and transducer 520 is configured as a receiver. In some embodiments, transducer 530 is configured as a transmitter and transducer 540 is configured as a receiver. In some embodiments, transducer 530 is configured as a transmitter and transducer 550 is configured as a receiver. In some embodiments, transducers 520 and 530 are configured as transmitters and transducers 540 and 550 are configured as receivers. In some embodiments, transducers 530 and 540 are configured as transmitters and transducers 520 and 550 are configured as receivers. In some embodiments, transducers 520 and 550 are configured as transmitters and transducers 530 and 540 are configured as receivers. In some embodiments, transducers 520 and 540 are configured as transmitters and transducers 530 and 550 are configured as receivers. In some embodiments, transducer 520 is configured as a transmitter and transducers 530 and 540 are configured as receivers. In some embodiments, transducer 530 is configured as a transmitter and transducers 550 and 540 are configured as receivers.

[0108] In some embodiments, one or more transducers are incorporated into a wearable device. The wearable device may include a wristband or watch in which one or more transducers are directed to the brachial artery to determine mean arterial pressure. In some embodiments, a substrate including one or more transducers is incorporated into the wearable device. The wearable device may wirelessly communicate with an external computing device to display or record data.

[0109] In some embodiments, the device includes four ultrasonic transducers and an electroacoustic transducer or speaker. In some embodiments, the image or signal captured by the ultrasonic transducer is input into a rotation matrix. Rotation and / or skew matrices can be applied to correctly orient the received signal for convolution, deconvolution, or normalization. As disclosed herein, normalization can be applied to the received signal. In some embodiments, a skew parameter is applied to the rotation matrix.

[0110] Each of the plurality of ultrasonic transducers may be configured to transmit a transmitted ultrasonic imaging signal to the subject. Each of the plurality of ultrasonic transducers may be configured to transmit a transmitted ultrasonic imaging signal having a frequency of about 100 KHz, about 200 KHz, about 300 KHz, about 400 KHz, about 500 KHz, about 650 KHz, about 700 KHz, about 800 KHz, about 850 kHz, about 900 kHz, about 1 MHz, about 2 MHz, about 3 MHz, about 5.5 MHz, about 6 MHz, about 8 MHz, about 11 MHz, about 15 MHz, about 20 MHz, about 25 MHz, or about 30 MHz. Each of the plurality of ultrasonic transducers may be configured to transmit a transmitted ultrasonic imaging signal having a frequency within a range defined by any two of the aforementioned values.

[0111] Each of the plurality of ultrasonic transducers may be configured to receive a received ultrasonic imaging signal from the subject. Each of the plurality of ultrasonic transducers may be configured to receive a received ultrasonic imaging signal having a frequency of about 100 KHz, about 200 KHz, about 300 KHz, about 400 KHz, about 500 KHz, about 650 KHz, about 700 KHz, about 800 KHz, about 850 kHz, about 900 kHz, about 1 MHz, about 2 MHz, about 3 MHz, about 5.5 MHz, about 6 MHz, about 8 MHz, about 11 MHz, about 15 MHz, about 20 MHz, about 25 MHz, or about 30 MHz. Each of the plurality of ultrasonic transducers may be configured to receive a received ultrasonic imaging signal having a frequency within a range defined by any two of the aforementioned values.

[0112] Each of the plurality of ultrasonic transducers may be configured to transmit and receive. Each of the plurality of ultrasonic transducers may be configured to transmit or receive ultrasonic imaging signals at the same frequency as one or more of the frequencies transmitted or received by another of the plurality of ultrasonic transducers. Each of the plurality of ultrasonic transducers may be configured to transmit or receive ultrasonic imaging signals at a frequency different from all frequencies transmitted or received by all other ultrasonic transducers in the plurality of ultrasonic transducers. Each of the plurality of ultrasonic transducers may be configured to transmit or receive simultaneously with one or more other ultrasonic transducers in the plurality of ultrasonic transducers.

[0113] For example, a first transmitted imaging signal of a first ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency of about 100 KHz, about 200 KHz, about 300 KHz, about 400 KHz, about 500 KHz, about 650 KHz, about 700 KHz, about 800 kHz, about 850 kHz, about 900 kHz, about 1 MHz, about 2 MHz, about 3 MHz, about 5.5 MHz, about 6 MHz, about 8 MHz, or about 11 MHz. A second transmitted imaging signal of a second ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency in the range of about 0.5 MHz to about 30 MHz. The first received imaging signal of a first ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency of about 100 KHz, about 200 KHz, about 300 KHz, about 400 KHz, about 500 KHz, about 650 KHz, about 700 KHz, about 800 KHz, about 850 KHz, about 900 KHz, about 1 MHz, about 2 MHz, about 3 MHz, about 5.5 MHz, about 6 MHz, about 8 MHz, or about 11 MHz. The second received imaging signal of a second ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency in the range of about 0.5 MHz to about 30 MHz.

[0114] In another example, a first transmitted imaging signal of a first ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency in the range of about 0.5 MHz to about 30 MHz. A second transmitted imaging signal of a second ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency in the range of about 0.5 MHz to about 30 MHz, but the frequency is different from the frequency of the first transmitted imaging signal. A first received imaging signal of a first ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency in the range of about 0.5 MHz to about 30 MHz. A second received imaging signal of a second ultrasonic transducer of the plurality of ultrasonic transducers may have a frequency in the range of about 0.5 MHz to about 30 MHz, but the frequency is different from the frequency of the first received imaging signal.

[0115] The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal of the third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer may have a frequency of about 100 KHz, about 200 KHz, about 300 KHz, about 400 KHz, about 500 KHz, about 650 KHz, about 700 kHz, about 800 kHz, about 850 kHz, about 900 kHz, about 1 MHz, about 2 MHz, about 3 MHz, about 5.5 MHz, about 6 MHz, about 8 MHz, or about 11 MHz, respectively. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal may have a frequency within the range described by any two of the aforementioned values. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal may have a value in the range of about 0.5 MHz to about 30 MHz. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal may have a frequency different from one or more of the frequencies of the first and second transmitted imaging signals.

[0116] The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal of the third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer, respectively, may have a frequency of about 100 KHz, about 200 KHz, about 300 KHz, about 400 KHz, about 500 KHz, about 650 KHz, about 700 KHz, about 800 KHz, about 850 KHz, about 900 KHz, about 1 MHz, about 2 MHz, about 3 MHz, about 5.5 MHz, about 6 MHz, about 8 MHz, or about 11 MHz. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may have a frequency within the range described by any two of the aforementioned values. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may have a value in the range of about 0.5 MHz to about 30 MHz. The frequency of the third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may have a frequency different from one or more of the frequencies of the first and second transmitted imaging signals.

[0117] Each ultrasonic transducer of the plurality of transducers can transmit or receive ultrasonic imaging signals within a bandwidth. The first ultrasonic transducer can have a first bandwidth and the second ultrasonic transducer can have a second bandwidth. The first bandwidth and the second bandwidth can overlap. The first bandwidth and the second bandwidth can partially overlap. The first bandwidth and the second bandwidth can not overlap. Similarly, the third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer can have a third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth bandwidth, respectively. Any of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth bandwidths can overlap with each other. Any of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth bandwidths can partially overlap with each other. Any of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth bandwidths may not overlap with each other.

[0118] The received imaging signals may be subjected to pre-processing operations. For example, the first received imaging signal may form the basis for normalizing the other received imaging signals. The second received imaging signal may be normalized by the first received imaging signal. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may be normalized by the first received imaging signal.

[0119] The system may include a transmit (Tx) generator. The transmit generator may include a host computer, a software-defined radio, and an ultrasonic signal processing circuit (USPC) as disclosed herein. The Tx generator may be a Tx beamformer. The Tx generator may be configured to operate any one ultrasonic transducer to transmit a first, second, third, or fourth transmitted ultrasonic imaging signal, respectively. The Tx generator may simultaneously operate any two or more of the first, second, third, or fourth ultrasonic imaging transducers. The system may also include an image synthesis module. The image synthesis module may include a receive (Rx) beamformer. The Rx beamformer may be configured to operate any one ultrasonic transducer to receive a first, second, third, or fourth received ultrasonic imaging signal, respectively. The image synthesis module may perform an ultrasonic image reconstruction operation on the received ultrasonic imaging signal. For example, the image synthesis module may perform a delay and summation operation on the received ultrasonic imaging signal. The image synthesis module may perform any ultrasonic image reconstruction operation on the received ultrasonic imaging signal. The Tx generator may be configured to operate the fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer to transmit the fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted ultrasonic imaging signal, respectively. The Tx generator may simultaneously operate any two or more of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic imaging transducers. Similarly, the Rx beamformer may be configured to operate the fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer to transmit the fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted ultrasonic imaging signal, respectively.

[0120] The Tx generator can be configured to operate any one of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth or sixteenth ultrasound transducers to transmit sequentially.

[0121] Figure 11A method for forming an ultrasound image from multiple ultrasound transducers is schematically illustrated. The method can utilize measurements from multiple ultrasound imaging sensors. The method can utilize single-pixel and multi-pixel image processing techniques. In the case of a single pixel, the nth ultrasound imaging measurement (where n is a positive integer) can be input to a signal processing unit. The signal processing unit can apply any ultrasound signal processing program to the nth ultrasound imaging measurement. The signal processing unit can output the measurement results of the signal processing to the image processing unit and the single-pixel feature extraction unit. The image processing unit can apply any ultrasound image processing program. The single-pixel feature extraction unit can apply any ultrasound single-pixel feature extraction program. The single-pixel feature extraction unit can output the extracted features to an operator.

[0122] In the multi-pixel case, the mth and (m+1th) (where m and m+1 are positive integers) ultrasound imaging measurements can be input to a multi-pixel image synthesis unit and a multi-pixel feature extraction unit. The image synthesis unit can apply any ultrasound image synthesis program. The multi-pixel feature extraction unit can apply any ultrasound multi-pixel feature extraction program. The multi-feature extraction unit can output the extracted features to the operator. Multi-pixel extraction can be used to construct 3D pixels (i.e., voxels).

[0123] In the case of multiple pixels, image processing methods such as two-dimensional smoothing filters, Harm filters, Gaussian filters, and integrators can be used to improve the recorded image. In addition, each pixel can be filtered in the time domain to highlight signal features. Single or multiple Butterworth, Chebyshev, and elliptic filters can be used to suppress noise and enhance feature extraction.

[0124] The sensors of the device may also include temperature sensors, optical sensors, electrical sensors, chemical sensors, and electrochemical sensors. In some embodiments, additional sensors allow measurement of body temperature, respiratory rate, blood pressure levels, and blood oxygen saturation (spO2) levels.

[0125] The stethoscope device may include a first ultrasonic transducer, a light source, and a light detector. The stethoscope device may optionally include a second ultrasonic transducer. The first ultrasonic transducer may operate in a Tx mode. The second ultrasonic transducer may operate in a receive mode. The stethoscope device may be placed on the skin of a subject (such as the skin in the subject's arm). When a bolus of blood travels through an artery under the subject's skin, the stethoscope device may transmit an ultrasonic signal from the first ultrasonic transducer and an optical signal from the light source. The ultrasonic signal or optical signal may be scattered, dispersed, or reflected from the bolus. The scattered, dispersed, or reflected ultrasonic signal or optical signal may be detected by the second ultrasonic transducer or the light detector, respectively. The intensity of the scattered, dispersed, or reflected ultrasonic signal or optical signal may be compared to the intensity of the transmitted ultrasonic signal or the transmitted optical signal, respectively. These measurements may generate the velocity of the blood bolus measured by the ultrasonic imaging signal and the optical signal, respectively. The velocity of the blood bolus as measured by the ultrasonic imaging signal may be normalized by the velocity of the blood bolus as measured by the optical signal, or vice versa. These values ​​may be synthesized and correlated to determine one or more physiological parameters of the subject, such as the subject's heart rate, blood pressure, or respiration.

[0126] 3. Methods for improving ultrasound resolution

[0127] Ultrasonic tissue imaging can be plagued by poor optical and acoustic transmittance and beam scattering. To address these difficulties and improve resolution, a method of multi-wavelength ultrasound imaging can be used by collecting information from multiple ultrasound sensors, each of which has an ultrasound transducer with a unique resonant frequency. By virtue of the resonant physiology of multiple ultrasound sensors operating at different resonant frequencies, ultrasound emitted by multiple transducers can simultaneously penetrate different depths in a given cross-sectional area of ​​physiology (e.g., tissue). In particular, ultrasound sensors with acoustic frequency responses can be actuated in a time-interleaved manner so that each sensor can be used to image a physiological surface at a unique depth. This can achieve high-resolution tomography without increasing the gain or number of ultrasound imaging sensors. In addition, each sensor can be actuated simultaneously with a combination of other sensors to generate higher harmonics that allow sub-pixel feature resolution (i.e., super-resolution imaging).

[0128] As used herein with respect to a transducer, the term "resonant frequency" generally refers to the operating frequency at which the transducer most efficiently converts electrical energy into mechanical energy. For example, in the context of a piezoelectric transducer, the term resonant frequency may refer to the operating frequency at which the piezoelectric material most readily vibrates and most efficiently converts electrical energy into mechanical energy.

[0129] Ultrasound entering the tissue may be transmitted, attenuated, or reflected. Although higher frequency ultrasound can provide a higher resolution signal, it can provide poorer depth penetration of the imaged tissue. Conversely, although lower frequency ultrasound can provide a lower resolution signal, it can provide better depth penetration of the imaged tissue. In order to overcome these limitations of conventional ultrasound imaging systems, each ultrasound sensor can have a transducer configured with a unique resonant frequency. Specifically, the ultrasound transducers can be selected so that their acoustic frequency responses do not overlap. By actuating the transducers in a time-interleaved manner, each sensor can be used to image the surface of the sample at a unique depth. In addition, each transducer can be actuated simultaneously with a combination of other transducers to generate higher harmonics that allow sub-pixel feature resolution.

[0130] like Figure 7A As shown, selecting transducers 711, 712, 713 with partially overlapping frequencies can allow for self-normalization and cross-correlation of the signals. In some embodiments, by selecting sensor transducers that are adjacent and partially overlapping in frequency response, the measurements of any pair of sensors can be normalized, thereby reducing system noise sources and significantly improving signal integrity. In addition, transducers with different resonant frequencies can be used to simultaneously interrogate the surface to generate super-resolution ultrasound images of the object 700. In some embodiments, the frequency overlap between sensors 711, 712, 713 can be configured to be approximately 200KHz or less. In some embodiments, the frequency overlap between sensors can be configured so that the frequency response range of one sensor does not overlap with the resonant frequency of another sensor. For example, as Figure 7B As depicted, the first sensor 711 having a resonant frequency 721 and the second sensor 712 having a resonant frequency 722 partially overlap in frequency response. Additionally, the second sensor 712 and the third sensor 713 having a resonant frequency 723 partially overlap in frequency response.

[0131] In some embodiments, the frequency overlap between the sensors is from about 10 KHz to about 500 KHz. In some embodiments, the frequency overlap between the sensors is from about 10 KHz to about 20 KHz, from about 10 KHz to about 30 KHz, from about 10 KHz to about 40 KHz, from about 10 KHz to about 50 KHz, from about 10 KHz to about 75 KHz, from about 10 KHz to about 100 KHz, from about 10 KHz to about 150 KHz, from about 10 KHz to about 200 KHz, from about 10 KHz to about 300 KHz, from about 10 KHz to about 400 KHz, from about 10 KHz to about 500 KHz, from about 20 KHz to about 30 KHz, from about 20 KHz to about 40 KHz, from about 20 KHz to about 50 KHz, from about 20 KHz to about 75 KHz. 5KHz, about 20KHz to about 100KHz, about 20KHz to about 150KHz, about 20KHz to about 200KHz, about 20KHz to about 300KHz, about 20KHz to about 400KHz, about 20KHz to about 500KHz, about 30KHz to about 40KHz, about 30KHz to about 50KHz, about 30KHz to about 75KHz, about 30KHz to about 100KHz, about 30KHz to about 150KHz, about 30KHz to about 200KHz, about 30KHz to about 300KHz, about 30KHz to about 400KHz, about 30KHz to about 500KHz, about 40KHz Hz to about 50KHz, about 40KHz to about 75KHz, about 40KHz to about 100KHz, about 40KHz to about 150KHz, about 40KHz to about 200KHz, about 40KHz to about 300KHz, about 40KHz to about 400KHz, about 40KHz to about 500KHz, about 50KHz to about 75KHz, about 50KHz to about 100KHz, about 50KHz to about 150KHz, about 50KHz to about 200KHz, about 50KHz to about 300KHz, about 50KHz to about 400KHz, about 50KHz to about 500KHz, about 75KHz to about 100KHz Hz, about 75KHz to about 150KHz, about 75KHz to about 200KHz, about 75KHz to about 300KHz, about 75KHz to about 400KHz, about 75KHz to about 500KHz, about 100KHz to about 150KHz, about 100KHz to about 200KHz, about 100KHz to about 300KHz, about 100KHz to about 400KHz, about 100KHz to about 500KHz, about 150KHz to about 200KHz, about 150KHz to about 300KHz, about 150KHz to about 400KHz, about 150KHz to about 500KHz, about 200KHz to about 3In some embodiments, the frequency overlap between sensors is about 100 KHz, about 200 KHz to about 400 KHz, about 200 KHz to about 500 KHz, about 300 KHz to about 400 KHz, about 300 KHz to about 500 KHz, or about 400 KHz to about 500 KHz. In some embodiments, the frequency overlap between sensors is about 10 KHz, about 20 KHz, about 30 KHz, about 40 KHz, about 50 KHz, about 75 KHz, about 100 KHz, about 150 KHz, about 200 KHz, about 300 KHz, about 400 KHz, or about 500 KHz. In some embodiments, the frequency overlap between sensors is at least about 10 KHz, about 20 KHz, about 30 KHz, about 40 KHz, about 50 KHz, about 75 KHz, about 100 KHz, about 150 KHz, about 200 KHz, about 300 KHz, or about 400 KHz. In some embodiments, the frequency overlap between sensors is at most about 20 KHz, about 30 KHz, about 40 KHz, about 50 KHz, about 75 KHz, about 100 KHz, about 150 KHz, about 200 KHz, about 300 KHz, about 400 KHz, or about 500 KHz.

[0132] Figures 8A-8D A technique for cross-correlation in an ultrasound measurement device is depicted. As depicted, cross-correlation of signals from any pair of sensors 811, 812, 813 whose frequency responses overlap allows for redundant measurements of voxels. Specifically, the transducers of the sensors can be actuated in a time-interleaved manner. For each actuation (e.g., actuation of sensor 812), a signal is transmitted to the object 800, and the received echo can be represented by, for example, Figure 8B All three transducers 811, 812, 812 are measured, and the following is obtained on all three transducers: Figure 8C Depicted are received signals 821, 822, 823. By looking at the correlation of the received signals across all three sensors, the signals can be normalized. Figure 8C The event of measuring the echo from the actuation of the second sensor 812 by all three sensors is illustrated. In some embodiments, the frequency responses of the first sensor 811 and the second sensor 812 are convolved with the received echo waveform in the frequency domain. When deconvolved, at step 805, the measurement from the third sensor can be correlated with the measurement from the second sensor while normalizing the measurement from the second sensor using the measurement from the first sensor. Figure 8D As depicted, sharper peaks are obtained in the signal monitored by the second sensor, and these sharper peaks can be achieved by the aforementioned cross-frequency normalization.

[0133] 4. Signal Generation, Transmission, and Reception

[0134] In some embodiments, circuitry is utilized to process the ultrasound signal. Figure 9 Processing circuitry (USPC) 950 is depicted according to some embodiments and is configured to process and / or condition ultrasound signals transmitted between one or more ultrasound transducers 930 and a software defined radio system 920. A system for generating and receiving ultrasound signals, such as Figure 9 As shown, it can correspond to a transmit (Tx) generator and / or receive (Rx) beamformer as described herein. One or more signals transmitted by a software-defined radio system can be referred to as an output of the software-defined radio system. One or more signals transmitted by a software-defined radio system can be referred to as an input to the software-defined radio system.

[0135] In some embodiments, the software defined radio system 920 transmits one or more signals 922, 924 to an ultrasonic signal processing circuit (USPC) 950. In some embodiments, the first transmission signal 922 comprises a transmission pulse or a reference clock. In some embodiments, the second transmission signal 924 comprises a gain ramp. In some embodiments, the transmission pulse 922 is a low voltage transmission pulse. In some embodiments, the transmission pulse 922 is a + / - 4 volt signal.

[0136] In some embodiments, the first transmission signal 922 is received by the high-voltage amplifier 952. In some embodiments, a transmission pulse or a reference clock is input to the high-voltage amplifier 952. In some embodiments, the amplified signal from the high-voltage amplifier 952 passes through a diode 954. In some embodiments, the first transmission signal 922 is then transmitted to the first multiplexer 982. In some embodiments, the first transmission signal 922 is a transmission pulse or a reference clock transmitted to the first multiplexer 982. In some embodiments, the diode 954 is an anti-parallel diode configured to block the received signal from the ultrasonic transducer 930 or the multiplexer 982 to the high-voltage amplifier 952. The high-voltage amplifier can be a discrete amplifier. In some embodiments, the high-voltage amplifier output signal is a + / - 100 volt amplifier. In some embodiments, the high-voltage amplifier 952 generates a + / - 100 volt device signal from the low-voltage output of the software-defined radio 920.

[0137] In some embodiments, the output from the first multiplexer 928 is transmitted to one or more ultrasonic transducers 930. In some embodiments, the output from the first multiplexer 928 is received by a first pixel group of the ultrasonic transducer 930. The ultrasonic transducer 930 may then transmit the first pixel group ultrasonic signal to the object. The object may then reflect the transmitted ultrasonic signal, and the ultrasonic transducer 930 may receive the reflected signal. In some embodiments, the reflected signal is received as part of the first pixel group. In some embodiments, the reflected signal is received as part of the second pixel group. In some embodiments, the reflected signal forms both the first pixel group and the second pixel group. The ultrasonic transducer 930 may then transmit the received reflected signal as an electrical signal. The reflected signal received from the first pixel group may be considered a first received signal. In some embodiments, the first received signal may be received from the transducer 930 by the first multiplexer 982. The reflected signal received from the second pixel group may be considered a second received signal. In some embodiments, the second received signal may be received from the transducer 930 by the second multiplexer 984. In some embodiments, signals are transmitted wirelessly between the multiplexers 982, 984 and the one or more ultrasound transducers 930. The wireless communication link between the multiplexers 982, 984 and the ultrasound transducer 930 may be a wireless mode, such as or Low Energy (LE) links, In some embodiments, the wired communication link between the multiplexers 982, 984 and the ultrasonic transducer 930 can be implemented using a wired transmitter or other suitable wired interface. For example, data can be transmitted using a USB-C connector, a USB 2.x or 3.x connector, a micro USB connector, a Thunderbolt connector, an Ethernet cable, etc.

[0138] The one or more signals transmitted to the ultrasonic transducer may be referred to as the input to the ultrasonic transducer. The one or more signals transmitted by the ultrasonic transducer may be referred to as the output of the ultrasonic transducer. The output of the ultrasonic transducer may correspond to the reflected ultrasonic signal measured or detected by the ultrasonic transducer.

[0139] In some embodiments, the first multiplexer 982 transmits the first received signal from the first pixel group to the first low-noise amplifier 964. In some embodiments, the first received signal passes through a high-voltage blocker 966. The high-voltage blocker 966 can prevent the signal from the high-voltage amplifier 952 from passing to the first low-noise amplifier. The blocker 966 can be a high-voltage protection transmit / receive switch (T / R switch), such as the MDO100. In some embodiments, the first low-noise amplifier 964 is a low-noise, single-ended, linear-in-dB, general-purpose variable-gain amplifier, such as the AD8336. In some embodiments, the first received signal is then received by the first variable-gain amplifier 962. In some embodiments, the variable-gain amplifier 962 is a low-noise, single-ended, linear-in-dB, general-purpose variable-gain amplifier, such as the AD8336. In some embodiments, the first low-noise amplifier 964 and the first variable-gain amplifier 962 utilize the same chip type.

[0140] In some embodiments, second multiplexer 984 transmits the first received signal from the second pixel group to second low-noise amplifier 974. In some embodiments, diode 976 prevents the transmitted signal from being output to second multiplexer 984. In some embodiments, diode 976 is an anti-parallel diode. In some embodiments, second low-noise amplifier 974 is a low-noise, single-ended, linear-in-dB, general-purpose variable-gain amplifier, such as the AD8336. In some embodiments, the second received signal is then received by second variable-gain amplifier 972. In some embodiments, variable-gain amplifier 972 is a low-noise, single-ended, linear-in-dB, general-purpose variable-gain amplifier, such as the AD8336. In some embodiments, first low-noise amplifier 964, first variable-gain amplifier 962, second low-noise amplifier 974, and second variable-gain amplifier 972 utilize the same chip type. In some embodiments, amplifiers 962, 964, 972, and 974 receive weak return pulses and amplify them according to the gain ramp signal. In some embodiments, 962, 964, 972, 974 receive weak return pulses and amplify them based on the second transmitted signal 924, which is a gain ramp signal. In some embodiments, the amplification of the ramp signal corresponds to the time since the input pulse. In some embodiments, the rate or ratio of amplification is determined by the time since the initial pulse of the gain ramp signal was transmitted. In some embodiments, the return pulse is the received signal.

[0141] In some embodiments, the second transmission 924 signal is transmitted to the first variable gain amplifier 962. In some embodiments, the signal output by the first variable gain amplifier 962 is received by the software defined radio system 920 and the first receive channel 926 of the second variable gain amplifier 972.

[0142] In some embodiments, the signal output by the second variable gain amplifier 972 is received by the second receive channel 928 of the software defined radio system 920 .

[0143] In some embodiments, the first multiplexer 982 is a 16-channel multiplexer. In some embodiments, the second multiplexer 984 is a 16-channel multiplexer. In some embodiments, the first pixel group includes 16 pixels. In some embodiments, the second pixel group includes 16 pixels. In some embodiments, the first pixel group functions as a transmit and receive (transceiver) group. In some embodiments, the second pixel group functions as a receive-only group. In some embodiments, the system has a 14-bit resolution. In some embodiments, the system has a 16-bit resolution. In some embodiments, the system is modular and can increase the number of channels using additional hardware. In some embodiments, the system can include from 16 channels to 2,048 channels. In some embodiments, the system may include 16 channels to 32 channels, 16 channels to 64 channels, 16 channels to 128 channels, 16 channels to 256 channels, 16 channels to 512 channels, 16 channels to 1,024 channels, 16 channels to 2,048 channels, 32 channels to 64 channels, 32 channels to 128 channels, 32 channels to 256 channels, 32 channels to 512 channels, 32 channels to 1,024 channels, 32 channels to 2,048 channels, 64 channels to 128 channels, 64 channels to 2 2,048 channels, 16 channels, 32 channels, 64 channels, 128 channels, 256 channels, 512 channels, 1,024 channels, 2,048 channels, or 1,024 channels. In some embodiments, the system may include 16 channels, 32 channels, 64 channels, 128 channels, 256 channels, 512 channels, 1,024 channels, or 2,048 channels. In some embodiments, the system may include at least 16 channels, 32 channels, 64 channels, 128 channels, 256 channels, 512 channels, or 1,024 channels. In some embodiments, the system may include up to 32 channels, 64 channels, 128 channels, 256 channels, 512 channels, 1,024 channels, or 2,048 channels.

[0144] In some embodiments, the software defined radio system 920 is a universal software radio peripheral (USRP), such as the National Instruments USRP N210. In some embodiments, the software defined radio system 920 is connected to a host computer 910. In some embodiments, the radio system 920 is connected to the computer 910 via a high-speed link. In some embodiments, the high-speed link comprises an Ethernet connection. In some embodiments, the Ethernet connection is a Gigabit Ethernet connection, which can allow a sampling rate of up to 50MS / s (megasamples per second). In some embodiments, host-based software is loaded onto the computer 910 and is used to control radio system hardware and transmit / receive data. In some embodiments, the general functions of the host computer are implemented in the radio system 920 with an embedded processor, which allows the radio system 920 to operate in a standalone manner.

[0145] In some embodiments, the connection to the computer 910 includes a universal serial bus (USB) connection, a fiber optic connection, a peripheral component interconnect express (PCIe) connection, or other suitable connection. In some embodiments, the connection to the computer 910 can allow the system to utilize the computer's fast access memory (RAM). In some embodiments, the embedded processor can include a RAM buffer. In some embodiments, the RAM buffer can include 4, 8, 16, 32, 64, 80, 128, or 256 gigabytes (GB).

[0146] In some embodiments, the software-defined radio system 920 includes a motherboard. The motherboard can provide the following subsystems: clock generation and synchronization, a field-programmable gate array (FPGA), one or more analog-to-digital converters (ADCs), one or more digital-to-analog converters (DACs), a host processor interface, and power supply regulation. In some embodiments, a modular front end or daughterboard is used for analog operations such as up / down conversion, filtering, and other signal conditioning. This modularity can allow the software-defined radio system 920 to serve applications operating between DC and 6 GHz. In some embodiments, the system operates between DC and 5 MHz. In some embodiments, the system only operates down to 1 MHz, which can be considered the limit of normal ultrasonic signals. In some embodiments, the system operates at frequencies of approximately 1 Hz to 3000 Hz to generate resonant mode sound waves.

[0147] In some embodiments, a signal received by the first receive channel 926 or the second receive channel 928 of the software defined radio system 920 may be adjusted to provide a received signal gain of approximately -14 decibels (dB) to +60 dB.

[0148] In some embodiments, the transmitter daughterboard module is implemented to modulate the output signal to a higher frequency. In some embodiments, the receiver daughterboard module is implemented to acquire the RF signal and convert it to baseband. In some embodiments, the transceiver daughterboard module is implemented to combine the functionality of a transmitter and a receiver.

[0149] In some embodiments, the FPGA of the software-defined radio system 920 performs several digital signal processing (DSP) operations. In some embodiments, the DSP operations performed by the FPGA provide the conversion from real-world signals in the analog domain to lower-rate, complex baseband signals in the digital domain. In some embodiments, these complex samples are fed to / from applications running on the host processor, which perform the DSP operations.

[0150] In some embodiments, the hardware driver of the software-defined radio system 920 supports operating systems such as Linux, MacOS, and Windows platforms. In some embodiments, the hardware driver can be used by several frameworks including GNU Radio, LabVIEW, MATLAB, and Simulink. The functions provided by the hardware driver can also be directly accessed through the hardware driver application programming interface (API). In some embodiments, the API provides native support for C++ or any other language that can import C++ functions.

[0151] According to some embodiments, the present disclosure provides a computer system programmed to implement the methods of the present disclosure. Figure 10 A computer system 1001 is shown that is programmed or otherwise configured to, for example, implement the methods disclosed herein. The computer system 1001 may be a user's electronic device or a computer system remotely located relative to the electronic device. The electronic device may be a mobile electronic device.

[0152] Computer system 1001 includes a central processing unit (CPU, also referred to herein as a "processor" and "computer processor") 1005, which can be a single-core or multi-core processor, or multiple processors for parallel processing. Computer system 1001 also includes memory or memory locations 1010 (e.g., random access memory, read-only memory, flash memory), electronic storage 1015 (e.g., a hard disk), a communication interface 1020 (e.g., a network adapter) for communicating with one or more other systems, and peripherals 1025 (such as cache, other memory, data storage, and / or an electronic display adapter). Memory 1010, storage 1015, interface 1020, and peripherals 1025 communicate with CPU 1005 via a communication bus (solid lines), such as a motherboard. Storage 1015 can be a data storage unit (or data repository) for storing data. Computer system 1001 can be operatively coupled to a computer network ("network") 1030 with the aid of communication interface 1020. Network 1030 can be the Internet, an intranet and / or an extranet, or an intranet and / or an extranet in communication with the Internet. In some cases, network 1030 is a telecommunications and / or data network. Network 1030 can include one or more computer servers that can implement distributed computing, such as cloud computing. In some cases, with the help of computer system 1001, network 1030 can implement a peer-to-peer network, which can enable devices coupled to computer system 1001 to act as clients or servers.

[0153] The CPU 1005 can execute a series of machine-readable instructions, which can be embodied in a program or software. The instructions can be stored in a memory location, such as the memory 1010. The instructions can be directed to the CPU 1005, which can then be programmed or otherwise configured to implement the methods of the present disclosure. Examples of operations performed by the CPU 1005 can include fetching, decoding, executing, and writing back.

[0154] CPU 1005 may be part of a circuit, such as an integrated circuit. One or more other components of system 1001 may be included in the circuit. In some cases, the circuit is an application-specific integrated circuit (ASIC).

[0155] Storage unit 1015 can store files such as drivers, libraries, and saved programs. Storage unit 1015 can store user data, such as user preferences and user programs. In some cases, computer system 1001 can include one or more additional data storage units external to computer system 1001, such as located on a remote server that communicates with computer system 1001 via an intranet or the Internet.

[0156] Computer system 1001 can communicate with one or more remote computer systems via network 1030. For example, computer system 1001 can communicate with a user's remote computer system (e.g., a smartphone, a laptop). Examples of remote computer systems include personal computers (e.g., portable PCs), tablets or tablet PCs (e.g., iPad, Galaxy Tab), phones, smartphones (e.g. iPhone, Android-enabled devices, ) or a personal digital assistant. A user can access the computer system 1001 via the network 1030.

[0157] The methods described herein can be implemented by a machine (e.g., a computer processor) of executable code stored on an electronic storage location (such as, for example, memory 1010 or electronic storage unit 1015) of computer system 1001. The machine-executable or machine-readable code can be provided in the form of software. During use, the code can be executed by processor 1005. In some cases, the code can be retrieved from storage unit 1015 and stored in memory 1010 for rapid access by processor 1005. In some cases, electronic storage unit 1015 can be eliminated, and the machine-executable instructions can be stored on memory 1010.

[0158] The code may be precompiled and configured for use with a machine having a processor suitable for executing the code, or may be compiled during runtime. The code may be supplied in a programming language that may be selected so that the code can be executed in a precompiled or compiled form.

[0159] Aspects of the systems and methods provided herein (such as computer system 1001) can be embodied in programming. Various aspects of the technology can be considered to be "products" or "articles" in the form of machine (or processor) executable code and / or related data carried or embodied on a type of machine-readable medium. Machine executable code can be stored on an electronic storage unit, such as a memory (e.g., read-only memory, random access memory, flash memory) or a hard disk. "Storage" type media can include any or all tangible memories of a computer, processor, or the like or its associated modules, such as various semiconductor memories, tape drives, disk drives, and the like, which can provide non-transitory storage for software programming at any time. All or part of the software can sometimes be communicated via the Internet or various other remote communication networks. For example, such communication can enable software to be loaded from one computer or processor to another, for example, from a management server or host computer to a computer platform of an application server. Therefore, another type of medium that can carry software elements includes light waves, radio waves, and electromagnetic waves (such as across physical interfaces between local devices, through wired and optical landline networks, and through various air links). The physical elements that carry such waves (such as wired or wireless links, optical links, or the like) may also be considered to be the medium that carries the software. As used herein, unless restricted to non-transitory, tangible "storage" media, terms such as computer or machine "readable media" refer to any medium that participates in providing instructions to a processor for execution.

[0160] Thus, a machine-readable medium (such as computer executable code) may take a variety of forms, including but not limited to tangible storage media, carrier media, or physical transmission media. Non-volatile storage media include, for example, optical or magnetic disks, such as any storage device in any computer(s) or the like, such as may be used to implement the databases shown in the accompanying drawings, etc. Volatile storage media include dynamic memory, such as the main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that make up a bus within a computer system. Carrier transmission media may take the form of electrical or electromagnetic signals, or acoustic or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Thus, common forms of computer-readable media include, for example: a floppy disk, a flexible disk, a hard disk, magnetic tape, any other magnetic medium, a CD-ROM, a DVD or DVD-ROM, any other optical medium, punched card stock tape, any other physical storage medium with a pattern of holes, RAM, ROM, PROM and EPROM, FLASH-EPROM, any other memory chip or cartridge, a carrier wave that transports data or instructions, a cable or link that transports such a carrier wave, or any other medium from which a computer can read programming code and / or data. Many of these forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[0161] Computer system 1001 may include or be in communication with an electronic display 1035 that includes a user interface (UI) 1040. Examples of UIs include, but are not limited to, graphical user interfaces (GUIs), mobile device applications, and web-based user interfaces.

[0162] Figure 11 A chip set 1300 is illustrated according to some embodiments. Chip set 1300 may include, for example, a processor and memory components incorporated into one or more physical packages. For example, a physical package includes the arrangement of one or more materials, components, and / or wires on a structural assembly (e.g., a substrate) to provide one or more characteristics, such as physical strength, dimensional conservation, and / or limitation of electrical interactions.

[0163] In one embodiment, the chipset 1300 includes a communication mechanism such as a bus 1302 for transferring information between the components of the chipset 1300. The processor 1304 has connectivity with the bus 1302 to execute instructions and process information stored in the memory 1306. The processor 1304 includes one or more processing cores, each configured to execute independently. A multi-core processor can implement multiprocessing within a single physical package. Examples of multi-core processors include two, four, eight, or more processing cores. Alternatively or additionally, the processor 1304 includes one or more microprocessors configured in series via the bus 1302 to implement independent execution of instructions, pipelining, and multithreading. The processor 1304 may also be accompanied by one or more specialized components to perform certain processing functions and tasks, such as one or more digital signal processors (DSPs) 1308, and / or one or more application-specific integrated circuits (ASICs) 1310. The DSP 1308 can generally be configured to process real-world signals (e.g., sound) in real time independently of the processor 1304. Similarly, ASIC 1310 can be configured to perform specialized functions that are not easily performed by general-purpose processors. Other specialized components that help perform the inventive functions described herein include one or more field programmable gate arrays (FPGAs) (not shown), one or more controllers (not shown), or one or more other special-purpose computer chips.

[0164] The processor 1304 and accompanying components are connected to a memory 1306 via a bus 1302. The memory 1306 includes dynamic memory (e.g., RAM) and static memory (e.g., ROM) for storing executable instructions that, when executed by the processor 1304, cause the DSP 1308 and / or ASIC 1310 to perform the processes of the example embodiments as described herein. The memory 1306 also stores data associated with or generated by the execution of the processes.

[0165] In this document, the terms "machine-readable medium," "computer-readable medium," and similar terms are generally used to refer to non-transitory, volatile, or non-volatile media that stores data and / or instructions that cause a machine to operate in a specific manner. Common forms of machine-readable media include, for example, hard disks, solid-state drives, magnetic tape or any other magnetic data storage medium, optical disks or any other optical data storage medium, any physical medium with a pattern of holes, RAM, PROM, EPROM, FLASH-EPROM, NVRAM, any other memory chip or cartridge, and networked versions thereof.

[0166] These and other various forms of computer-readable media may be used to carry one or more sequences of one or more instructions to a processing device for execution. Such instructions embodied on the media are generally referred to as "instructions" or "code." The instructions may be grouped in the form of a computer program or other groupings. When executed, such instructions may enable the processing device to perform the features or functions of the present application as discussed herein.

[0167] In this document, a "processing device" may be implemented as a single processor that performs processing operations or a combination of specialized and / or general-purpose processors that perform processing operations. A processing device may include a CPU, GPU, APU, DSP, FPGA, ASIC, SOC, and / or other processing circuitry.

[0168] The various embodiments described herein are described with reference to exemplary block diagrams, flow charts, and other illustrations. As will become apparent to those skilled in the art after reading this document, the illustrated embodiments and their various alternatives may be implemented without limitation to the illustrated examples. For example, the block diagrams and accompanying descriptions should not be construed as mandating a specific architecture or configuration.

[0169] Each of the processes, methods, and algorithms described in the foregoing sections may be embodied in a code component executed by one or more computer systems or computer processors comprising computer hardware, and fully or partially automated thereby. The processes and algorithms may be implemented in part or in whole in dedicated circuits. The various features and processes described above may be used independently of one another, or may be combined in various ways. Different combinations and sub-combinations are intended to fall within the scope of this disclosure, and certain method or process blocks may be omitted in some embodiments. In addition, unless the context indicates otherwise, the methods and processes described herein are not limited to any particular order, and the blocks or states associated therewith may be executed in other appropriate orders, or may be executed in parallel, or in other ways. Blocks or states may be added to or removed from the disclosed example embodiments. The performance of certain operations or processes may be distributed among computer systems or computer processors, not only residing within a single machine, but also deployed on multiple machines.

[0170] The devices and methods described herein can be used in applications beyond the aforementioned medical fields. For example, these devices and methods can be used to provide information about the internal condition of a mechanical system, such as a vehicle's engine or transmission. The stethoscope function can be used to detect anomalies in the mechanical processes of the engine or transmission. The ultrasonic function can be used to image the engine or transmission to determine if it has suffered internal damage. Non-stethoscope, non-ultrasonic sensors can provide additional information about the condition of the engine or transmission, such as its temperature.

[0171] The apparatus and methods can be used for nondestructive testing of infrastructure. For example, the apparatus and methods can be used to examine the internal structure of concrete (in streets or highways, bridges, buildings, or other structures) to determine whether the concrete or metal rebar within the concrete has been damaged. The apparatus and methods can also be used to examine the internal structure of pipes to determine whether they are damaged and could pose a threat to life, property, or the environment.

[0172] The apparatus and methods described herein may be used to inspect the internal structure of other building materials, such as stone, brick, wood, drywall, insulation, plastic pipes, polyvinyl chloride (PVC) pipes, fiberglass, or paint.

[0173] 5. Currently preferred implementation

[0174] 1. In a currently preferred embodiment, the present invention provides a blood pressure measurement device comprising: a first transducer configured to emit a plurality of sound waves having a plurality of frequencies, the sound waves being configured to cause a subject's blood vessels to vibrate; a second transducer configured to capture one or more ultrasound images of the blood vessels; and a processing device configured to: determine a resonant frequency of the blood vessels based on the one or more captured ultrasound images; and calculate the blood pressure of the blood vessels or the subject based on the wall thickness of the blood vessels, the radius or diameter of the blood vessels, and the determined resonant frequency.

[0175] 2. The blood pressure measurement device according to paragraph 1, wherein the one or more captured ultrasound images are used to measure the wall thickness of the blood vessel and the radius or diameter of the blood vessel.

[0176] 3. The blood pressure measurement device of paragraphs 1 or 2, wherein the one or more captured ultrasound images include a plurality of ultrasound images, and wherein determining the resonant frequency of the blood vessel includes:

[0177] determining a frequency that maximizes vibration of the blood vessel among a plurality of frequencies based on the plurality of ultrasound images; and

[0178] Select the frequency as the resonant frequency.

[0179] 4. The blood pressure measurement device according to any of the preceding paragraphs, further comprising: an audio signal generator electrically coupled to the first transducer, the audio signal generator being configured to adjust the frequency of the sound waves emitted by the first transducer.

[0180] 5. The blood pressure measurement device according to any of the preceding paragraphs, wherein the audio signal generator comprises at least one variable resistor that adjusts the frequency of the sound waves emitted by the first transducer.

[0181] 6. A blood pressure measuring device according to any of the preceding paragraphs, wherein each frequency is between 1 Hz and 3000 Hz.

[0182] 7. A blood pressure measurement device according to any of the preceding paragraphs, wherein each of the frequencies is between 670 Hz and 2300 Hz.

[0183] 8. A blood pressure measurement device according to any preceding paragraph, wherein the blood vessel is a carotid artery of the subject.

[0184] 9. A blood pressure measurement device according to any of the preceding paragraphs, wherein the first transducer is an audio speaker.

[0185] 10. The blood pressure measurement device of any preceding paragraph, further comprising: a substrate, wherein the substrate comprises an adhesive surface for adhering to the skin of a subject, wherein the first transducer and the second transducer are incorporated into the substrate.

[0186] 11. The blood pressure measurement device according to paragraph 10, wherein the substrate is adhered in the vicinity of the blood vessel.

[0187] 12. The blood pressure measurement device according to paragraph 11, wherein the blood vessel is a carotid artery.

[0188] 13. The blood pressure measurement device of any of paragraphs 10 to 12, wherein the substrate includes alignment lines.

[0189] 14. The blood pressure measurement device of paragraph 13, wherein the substrate includes a transparent window.

[0190] 15. The blood pressure measurement device of paragraph 10, further comprising a third transducer configured to capture a second set of one or more ultrasound images of the blood vessel.

[0191] 16. A blood pressure measurement device according to paragraph 15, wherein the second transducer and the third transducer each have a corresponding resonant frequency, and wherein the second transducer includes a frequency response that partially overlaps with the frequency response of the third transducer; and the processing device processes the measurements made by the first transducer and the second transducer.

[0192] 17. The blood pressure measurement device of paragraph 16, wherein processing the measurements made by the first transducer and the second transducer includes normalizing the first frequency response and the second frequency response.

[0193] 18. The blood pressure measurement device of paragraph 15, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

[0194] 19. The blood pressure measurement device of paragraph 15, further comprising: a substrate, wherein the substrate includes an adhesive surface for adhering to the skin of a subject, wherein the first transducer, the second transducer, and the third transducer are incorporated into the substrate.

[0195] 20. The blood pressure measurement device according to paragraph 19, wherein the substrate is adhered in the vicinity of the blood vessel.

[0196] 21. The blood pressure measurement device according to paragraph 20, wherein the blood vessel is a carotid artery.

[0197] 22. The blood pressure measurement device of paragraph 21, wherein the substrate includes alignment lines.

[0198] 23. The blood pressure measurement device of paragraph 22, wherein the substrate further comprises a transparent window.

[0199] 24. The blood pressure measurement device of paragraph 16, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

[0200] 25. The blood pressure measurement device of paragraph 24, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer.

[0201] 26. The blood pressure measurement device of paragraph 24, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer.

[0202] 27. The blood pressure measurement device of paragraph 24, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency responses of the second transducer and the third transducer.

[0203] 28. The blood pressure measurement device of paragraph 24, further comprising: a substrate, wherein the substrate includes an adhesive surface for adhering to the skin of a subject, wherein the first transducer, the second transducer, and the third transducer are incorporated into the substrate.

[0204] 29. The blood pressure measurement device according to paragraph 28, wherein the substrate is adhered in the vicinity of the blood vessel.

[0205] 30. The blood pressure measurement device according to paragraph 29, wherein the blood vessel is a carotid artery.

[0206] 31. The blood pressure measurement device of paragraph 30, wherein the substrate includes alignment lines.

[0207] 32. The blood pressure measurement device of paragraph 31, wherein the substrate further comprises a transparent window.

[0208] 33. The blood pressure measurement device of any preceding paragraph, further comprising a third transducer configured to capture a second set of one or more ultrasound images of the blood vessel.

[0209] 34. A blood pressure measurement device according to paragraph 33, wherein the second transducer and the third transducer each have a corresponding resonant frequency, and wherein the second transducer includes a frequency response that partially overlaps with the frequency response of the third transducer; and the processing device processes the measurements made by the first transducer and the second transducer.

[0210] 35. The blood pressure measurement device of paragraph 34, wherein processing the measurements made by the first transducer and the second transducer includes normalizing the first frequency response and the second frequency response.

[0211] 36. The blood pressure measurement device of paragraph 33, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

[0212] 37. The blood pressure measurement device of paragraph 34, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

[0213] 38. The blood pressure measurement device of paragraph 37, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer.

[0214] 39. The blood pressure measurement device of paragraph 37, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer.

[0215] 40. The blood pressure measurement device of paragraph 37, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency responses of both the second transducer and the third transducer.

[0216] 41. In a currently preferred embodiment, the present invention provides a non-transitory computer-readable storage medium storing instructions executable by a processor, wherein execution of the instructions causes a blood pressure measurement device to perform operations including: using a first transducer near a subject's blood vessel to emit multiple sound waves having multiple frequencies, which sound waves cause the subject's blood vessel to vibrate; determining the resonant frequency of the blood vessel based on the vibration response of the blood vessel to the multiple sound waves; using a second transducer that emits ultrasonic waves to determine the wall thickness and radius or diameter of the blood vessel; and calculating the subject's blood pressure based on the resonant frequency, the wall thickness of the blood vessel, and the radius or diameter of the blood vessel.

[0217] 42. The non-transitory computer-readable storage medium of paragraph 41, wherein the operation further comprises: using the second transducer to capture a plurality of ultrasound images of the blood vessel as the blood vessel vibrates in response to the sound waves, wherein determining the resonant frequency of the blood vessel comprises: determining the resonant frequency of the blood vessel based on the ultrasound images.

[0218] 43. The non-transitory computer-readable storage medium of paragraphs 41 or 42, wherein determining the wall thickness and radius of the blood vessel comprises: directing ultrasound waves to the blood vessel using the second transducer; and receiving ultrasound waves reflected from echogenic boundaries of the blood vessel using the second transducer.

[0219] 44. The non-transitory computer-readable storage medium of paragraph 41, wherein after calculating the blood pressure, the operation further comprises: determining an updated radius of the blood vessel and an updated velocity of blood flowing through the blood vessel using the first transducer and the second transducer; and calculating an updated blood pressure based on the updated radius and the updated velocity.

[0220] 45. The non-transitory computer-readable storage medium of any preceding paragraph, wherein the plurality of frequencies of the plurality of sound waves are between 1 Hz and 3000 Hz.

[0221] 46. ​​The non-transitory computer-readable storage medium of any preceding paragraph, wherein the plurality of frequencies of the plurality of sound waves are between 670 Hz and 2300 Hz.

[0222] 47. The non-transitory computer-readable storage medium of any preceding paragraph, wherein the first transducer is an audio speaker.

[0223] 48. The non-transitory computer-readable storage medium of any of the preceding paragraphs, wherein the operations further comprise capturing a first set of ultrasound images of the blood vessel using a third transducer.

[0224] 49. The non-transitory computer-readable storage medium of paragraph 48, wherein the operations further comprise capturing a second set of ultrasound images of the blood vessel using a second transducer.

[0225] 50. The non-transitory computer-readable storage medium of paragraph 49, wherein the operations further comprise normalizing the second set of ultrasound images by the first set of ultrasound images.

[0226] 51. The non-transitory computer-readable storage medium of paragraph 49, wherein the operations further comprise capturing a third set of ultrasound images of the blood vessel using a fourth transducer.

[0227] 52. The non-transitory computer-readable storage medium of paragraph 51, wherein the operations further comprise normalizing the second set of ultrasound images by the first set of ultrasound images.

[0228] 53. The non-transitory computer-readable storage medium of paragraph 52, wherein the operations further comprise normalizing the second set of ultrasound images by the third set of ultrasound images.

[0229] 54. In a currently preferred embodiment, the present invention provides a method comprising: using a first transducer near a subject's blood vessel to transmit multiple sound waves having multiple frequencies, which sound waves cause the subject's blood vessel to vibrate; determining the resonant frequency of the blood vessel based on the vibration response of the blood vessel to the sound waves; using a second transducer that transmits ultrasonic waves to determine the wall thickness and radius or diameter of the blood vessel; and calculating the subject's blood pressure based on the resonant frequency, the wall thickness of the blood vessel, and the radius or diameter of the blood vessel.

[0230] 55. The method of paragraph 54 further comprising: using a second transducer to capture a plurality of ultrasound images of the blood vessel as the blood vessel vibrates in response to the sound waves, wherein determining the resonant frequency of the blood vessel comprises: determining the resonant frequency of the blood vessel based on the ultrasound images.

[0231] 56. The method of paragraph 54 or 55, wherein determining the wall thickness and radius of the blood vessel comprises: directing ultrasound waves into the blood vessel using a second transducer; and receiving ultrasound waves reflected from echogenic boundaries of the blood vessel using the second transducer.

[0232] 57. A method according to any of the preceding paragraphs, wherein after calculating the blood pressure, the method further comprises: determining an updated radius of the blood vessel and an updated speed at which blood flows through the blood vessel using the first transducer and the second transducer; and calculating an updated blood pressure based on the updated radius and the updated speed.

[0233] 58. A method according to any preceding paragraph, wherein each frequency is between 670 Hz and 2300 Hz.

[0234] 59. The method of paragraph 55 further comprising capturing a second plurality of ultrasound images of the blood vessel using a third transducer as the blood vessel vibrates in response to the sound waves.

[0235] 60. The method of paragraph 59, further comprising normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer with a second plurality of ultrasound images of the blood vessel captured by the third transducer.

[0236] 61. The method of paragraph 59, further comprising capturing a third plurality of ultrasound images of the blood vessel using a fourth transducer as the blood vessel vibrates in response to the sound waves.

[0237] 62. The method of paragraph 61, further comprising normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer with a second plurality of ultrasound images of the blood vessel captured by the third transducer.

[0238] 63. The method of paragraph 62, further comprising normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer with a third plurality of ultrasound images of the blood vessel captured by a fourth transducer.

[0239] 64. In a currently preferred embodiment, the present invention provides a blood pressure measuring device, comprising: a first transducer, configured to guide sound waves to a blood vessel; a second transducer, configured to guide ultrasonic waves to the blood vessel, receive ultrasonic waves reflected by the echo boundary of the blood vessel, measure the radius or diameter of the cross section of the blood vessel, and measure the wall thickness of the cross section of the blood vessel.

[0240] 65. The blood pressure measurement device of paragraph 64, wherein the first transducer is an electroacoustic transducer and the second transducer is a piezoelectric ultrasonic transducer.

[0241] 66. The blood pressure measurement device of paragraph 64 or 65, wherein the device further comprises an audio signal generator coupled to the first transducer.

[0242] 67. The blood pressure measurement device of paragraph 66, wherein the audio signal generator is configured to change the frequency of the sound waves.

[0243] 68. The blood pressure measurement device of paragraph 67, further comprising a display.

[0244] 69. A blood pressure measurement device according to paragraph 68, wherein the display shows the frequency of the sound waves.

[0245] 70. The blood pressure measurement device of paragraph 69, wherein the second transducer monitors vibrations of a cross-section of the blood vessel.

[0246] 71. The blood pressure measurement device of paragraph 67, wherein the second transducer monitors vibrations of a cross-section of the blood vessel, and wherein the second transducer records the frequency of the vibrations of the cross-section and determines its resonant frequency.

[0247] 72. The blood pressure measurement device according to paragraph 71, wherein the resonant frequency is determined when the vibration of the cross section of the blood vessel is at a maximum.

[0248] 73. A blood pressure measuring device according to any of the preceding paragraphs, wherein the frequency of the sound waves varies in the range of 1 Hz to 3000 Hz.

[0249] 74. A blood pressure measuring device according to any of the preceding paragraphs, wherein the frequency of the sound waves varies within the range of 670 Hz to 2300 Hz.

[0250] 75. A blood pressure measurement device according to any of the preceding paragraphs, wherein the electroacoustic transducer is an audio speaker.

[0251] 76. The blood pressure measurement device of paragraph 75, wherein the audio speaker is a tweeter.

[0252] 77. The blood pressure measurement device of any of paragraphs 64 to 76, wherein the blood vessel is an artery or a vein.

[0253] 78. The blood pressure measurement device of any of the preceding paragraphs, wherein the first transducer and the second transducer are coupled to a substrate, and wherein the substrate includes an adhesive backing.

[0254] 79. The blood pressure measurement device of paragraph 78, wherein the substrate is adhered in the vicinity of the blood vessel.

[0255] 80. The blood pressure measurement device of paragraph 79, wherein the blood vessel is a carotid artery.

[0256] 81. The blood pressure measurement device of any of paragraphs 78 to 80, wherein the substrate includes alignment lines.

[0257] 82. The blood pressure measurement device of any of paragraphs 78 to 80, wherein the substrate includes alignment lines and a transparent window.

[0258] 83. In a currently preferred embodiment, the present invention provides a method for measuring blood pressure, the method comprising: determining the radius and wall thickness of a cross section of a blood vessel; guiding sound waves to the blood vessel; changing the frequency of the sound waves; detecting the maximum resonance of the cross section of the blood vessel to determine the resonant frequency of the blood vessel; and calculating the blood pressure in the blood vessel based on the determined resonant frequency, the radius and wall thickness of the blood vessel.

[0259] 84. The method of paragraph 83, wherein changing the frequency of the sound waves comprises changing the frequency of the sound waves within a range of 1 Hz to 3000 Hz.

[0260] 85. The method of paragraph 83, wherein changing the frequency of the sound waves comprises changing the frequency of the sound waves within a range of 670 Hz to 2300 Hz.

[0261] 86. A method according to any of the preceding paragraphs, wherein the resonant frequency is determined by detecting a maximum resonance using a piezoelectric ultrasonic transducer.

[0262] 87. The method of paragraph 86, wherein the piezoelectric ultrasonic transducer comprises a sampling rate of at least 3 kHz.

[0263] 88. The method of any preceding paragraph, wherein the step of determining the radius and wall thickness of the blood vessel comprises directing ultrasound waves into the blood vessel and receiving reflected ultrasound waves reflected from echogenic boundaries of the blood vessel.

[0264] 89. The method of paragraph 88, further comprising measuring a Doppler shift of the reflected ultrasound waves and calculating the wave velocity of the blood vessel.

[0265] 90. The method of paragraph 89, wherein the Doppler shift is measured by a piezoelectric ultrasound transducer.

[0266] 91. The method of any preceding paragraph, wherein the blood vessel is an artery or a vein.

[0267] 92. The method of any of the preceding paragraphs, further comprising directing a first set of transmitted ultrasonic waves toward a blood vessel and capturing a first set of reflected ultrasonic waves from the blood vessel.

[0268] 93. The method of paragraph 92, wherein the steps of directing the first set of transmitted ultrasonic waves toward the blood vessel and capturing the first set of reflected ultrasonic waves from the blood vessel are performed by a single ultrasonic transducer.

[0269] 94. The method of any of the preceding paragraphs, further comprising directing a first set of transmitted ultrasonic waves toward a blood vessel using a first ultrasonic transducer and capturing a first set of reflected ultrasonic waves from the blood vessel using a second ultrasonic transducer.

[0270] 95. The method of any of the preceding paragraphs, further comprising directing a first set of transmitted ultrasonic waves toward a blood vessel using the first ultrasonic transducer and capturing a first set of reflected ultrasonic waves from the blood vessel using the first ultrasonic transducer and the second ultrasonic transducer.

[0271] 96. The method of any of the preceding paragraphs, further comprising directing a first set of transmitted ultrasound signals toward a blood vessel using a first ultrasound transducer, and capturing a first reflected ultrasound signal from the blood vessel using the first ultrasound transducer.

[0272] 97. The method of paragraph 96, further comprising capturing a second reflected ultrasound signal from the blood vessel with a second ultrasound transducer.

[0273] 98. The method of paragraph 97 further comprising normalizing the first reflected ultrasound signal with the second reflected ultrasound signal.

[0274] 99. The method of paragraph 97 further comprising capturing a third reflected ultrasound signal from the blood vessel using a third ultrasound transducer.

[0275] 100. The method of paragraph 99, further comprising normalizing the first reflected ultrasonic signal with the third reflected ultrasonic signal.

[0276] 101. The method of any preceding paragraph, wherein the blood vessel is the carotid artery.

[0277] 102. In a presently preferred embodiment, the present invention provides a system for transmitting and receiving ultrasonic signals, the system comprising: a software-defined radio including one or more outputs and one or more inputs; an ultrasonic signal processing circuit electrically coupled to the software-defined radio; and one or more ultrasonic transducers electrically coupled to the ultrasonic signal processing circuit, wherein the ultrasonic signal processing circuit processes one or more ultrasonic transmission signals from one or more outputs of the software-defined radio and transmits the processed ultrasonic transmission signals to the one or more ultrasonic transducers to generate ultrasonic waves, and wherein the signal processing unit processes one or more received ultrasonic signals from the one or more ultrasonic transducers and transmits the processed received ultrasonic signals to the one or more inputs of the software-defined radio.

[0278] 103. The system of paragraph 102, wherein the ultrasound processing circuitry includes at least one high voltage amplifier to amplify one or more ultrasound transmission signals from one or more outputs of the software defined radio.

[0279] 104. The system of paragraph 103, wherein the ultrasound processing circuit comprises at least one variable gain amplifier to amplify one or more ultrasound signals received from the one or more ultrasound transducers.

[0280] 105. The system of any of the preceding paragraphs, wherein the ultrasound processing circuitry comprises at least one variable gain amplifier to amplify one or more received ultrasound signals from the one or more ultrasound transducers.

[0281] 106. A system as described in any of the preceding paragraphs, wherein the output of the software defined radio includes a gain ramp and a transmit pulse.

[0282] 107. The system of paragraph 106, wherein the ultrasound processing circuit includes a high voltage amplifier for amplifying the transmission pulses.

[0283] 108. The system of paragraph 107, wherein the ultrasound processing circuit includes a variable gain amplifier to amplify one or more received ultrasound signals from the one or more ultrasound transducers based on a gain ramp of radio transmissions defined by software.

[0284] 109. The system of paragraph 108, wherein the amplification rate of the ramp signal corresponds to the time since the software defined radio transmitted an initial pulse of the ramp signal.

[0285] 110. The system of paragraph 109, wherein the ultrasound transducer comprises a first pixel group and a second pixel group.

[0286] 111. The system of paragraph 110, wherein the first pixel group and the second pixel group each include 16 pixels.

[0287] 112. The system of paragraph 111, wherein the first pixel group is configured to receive the processed ultrasound transmission signal.

[0288] 113. The system of paragraph 111, wherein only the first pixel group receives the processed ultrasound transmission signal.

[0289] 114. The system of paragraph 113, wherein the one or more received ultrasound signals are received by the first pixel group and the second pixel group and transmitted to the ultrasound processing circuit.

[0290] 115. The system of paragraph 108, wherein the variable gain amplifier is a low noise, single-ended, linear, universal variable gain amplifier.

[0291] 116. A system according to any of the preceding paragraphs, wherein the ultrasound transducer includes a first pixel group and a second pixel group.

[0292] 117. The system of paragraph 116, wherein the first pixel group is configured to receive the processed ultrasound transmission signal.

[0293] 118. The system of paragraph 117, wherein only the first pixel group receives the processed ultrasound transmission signal.

[0294] 119. The system of paragraph 118, further comprising a computing device coupled to the software defined radio, such that the computing device controls one or more outputs of the software defined radio.

[0295] 120. The system of paragraph 119, wherein the computing device includes a display, wherein the display displays data received by one or more inputs of the software defined radio.

[0296] 121. The system of paragraph 120, wherein the display displays one or more ultrasound images obtained by the one or more ultrasound transducers.

[0297] 122. The system of any preceding paragraph, further comprising a computing device coupled to the software defined radio such that the computing device controls one or more outputs of the software defined radio.

[0298] 123. The system of paragraph 122, wherein the computing device includes a display, wherein the display displays data received by one or more inputs of the software defined radio.

[0299] 124. The system of paragraph 123, wherein the display displays one or more ultrasound images obtained by the one or more ultrasound transducers.

[0300] 125. In a presently preferred embodiment, the present invention provides a method of conditioning one or more ultrasound signals, the method comprising: receiving a first transmission signal from a software defined radio; amplifying the first transmission signal to form an amplified transmission signal;

[0301] forwarding the amplified transmission signal to one or more ultrasonic transducers with a first multiplexer; receiving one or more received ultrasonic signals from the one or more ultrasonic transducers with the first multiplexer; and amplifying the one or more received ultrasonic signals to form one or more amplified received ultrasonic signals.

[0302] 126. A method according to any of the preceding paragraphs, wherein amplification of one or more received ultrasound signals is based on a gain ramp of the radio transmission defined by software.

[0303] 127. The method of paragraph 126, wherein the amplification is time-dependent.

[0304] 128. The method of paragraph 127, wherein amplification of the one or more received ultrasound signals is performed by one or more low-noise, single-ended, linear, general-purpose variable gain amplifiers.

[0305] 129. A method according to any of the preceding paragraphs, wherein amplification of one or more received ultrasound signals is performed by one or more low-noise, single-ended, linear, general-purpose variable gain amplifiers.

[0306] 130. The method according to any of the preceding paragraphs further includes transmitting one or more ultrasonic waves toward at least one object, wherein the at least one object reflects the one or more ultrasonic waves, and wherein the reflected ultrasonic waves are detected by one or more ultrasonic transducers and form one or more received ultrasonic signals.

[0307] 131. The method of paragraph 130, wherein the amplification of one or more received ultrasound signals is based on a gain ramp of the radio transmission defined by software.

[0308] 132. The method of paragraph 131, wherein the amplification is time-dependent.

[0309] 133. The method of paragraph 132, wherein amplification of the one or more received ultrasound signals is performed by one or more low-noise, single-ended, linear, general-purpose variable gain amplifiers.

[0310] 134. The method of paragraph 130, wherein at least one object is a blood vessel of the subject.

[0311] 135. The method of paragraph 134, wherein the blood vessel is a carotid artery.

[0312] VI. Definition

[0313] Unless otherwise defined, all technical terms, symbols, and other technical and scientific terms or technical terminology used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which the claimed subject matter belongs. In some cases, terms with commonly understood meanings are defined herein for clarity and / or for ease of reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference from what is generally understood in the art.

[0314] Throughout this application, various embodiments may be presented in range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as a hard limit to the scope of the present disclosure. Therefore, the description of a range should be considered to have specifically disclosed all possible subranges and individual numerical values ​​within that range. For example, a description of a range such as 1 to 6 should be considered to have specifically disclosed subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual numbers within that range, such as 1, 2, 3, 4, 5, and 6. This applies regardless of the width of the range.

[0315] As used in the specification and claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, the term "sample" includes a plurality of samples, including mixtures thereof.

[0316] The terms "determine," "measure," "assess," "assess," "determine," and "analyze" are often used interchangeably herein to refer to forms of measurement. These terms include determining whether an element is present (e.g., detecting). These terms can include quantitative, qualitative, or both quantitative and qualitative determinations. Assessments can be relative or absolute. "Detecting the presence" can include determining the amount of something that is present, as well as determining whether it is present, depending on the context.

[0317] The terms "subject," "individual," or "patient" are often used interchangeably herein. A "subject" can be a biological entity comprising expressed genetic material. A biological entity can be a plant, an animal, or a microorganism, including, for example, bacteria, viruses, fungi, and protozoa. A subject can be a tissue, cell, or progeny of a biological entity obtained in vivo or cultured in vitro. A subject can be a mammal. A mammal can be a human. A subject can be diagnosed or suspected of being at high risk for a disease. In some cases, a subject is not necessarily diagnosed or suspected of being at high risk for the disease.

[0318] The term "in vivo" is used to describe events that occur within the body of a subject.

[0319] The term "ex vivo" is used to describe an event that occurs outside the body of a subject. An ex vivo assay is not performed on a subject. Instead, it is performed on a sample that is separate from the subject. An example of an ex vivo assay performed on a sample is an "in vitro" assay.

[0320] The term "in vitro" is used to describe an event that occurs in a container containing laboratory reagents so that they are separated from the biological source from which the material was obtained. In vitro assays can include cell-based assays that use living or dead cells. In vitro assays can also include cell-free assays that do not use intact cells.

[0321] As used herein, the term "about" a number refers to the number plus or minus 10%. The term "about" a range refers to the range minus 10% of its minimum value and plus 10% of its maximum value.

[0322] As used herein, the term "or" may be interpreted as inclusive or exclusive. Furthermore, descriptions of resources, operations, or structures in the singular should not be interpreted as excluding the plural. Conditional language (such as "can," "may," "might," or "could"), unless expressly stated otherwise or otherwise understood in the context of use, is generally intended to convey that certain embodiments include, while other embodiments do not, certain features, elements, and / or steps.

[0323] Unless expressly stated otherwise, the terms and phrases used in this document, and variations thereof, should be interpreted as open ended and non-restrictive. Adjectives such as "conventional," "traditional," "normal," "standard," "known," and terms of similar meaning should not be construed to limit the items described to a given time period or as of a given time, but should be read as encompassing conventional, traditional, normal, or standard technology that may be available or known at any time now or in the future. In certain cases, the presence of broadening words and phrases such as "one or more," "at least," "but not limited to," or other similar phrases should not be understood to mean that a narrower situation is expected or required where such broadening phrases may not be present.

[0324] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0325] 7. Examples

[0326] The following examples are included for illustrative purposes only and are not intended to limit the scope of the invention.

[0327] Example 1: Measuring blood pressure using a cuff

[0328] In an example of measuring blood pressure using a previous method using a blood pressure cuff, the patient's arm is positioned on a comfortable surface. A trained nurse or physician then places an appropriately sized cuff on the patient's upper arm. A stethoscope is placed on the patient's brachial artery, just below the cuff.

[0329] The trained person then inflates the cuff to 180 mmHG and begins releasing air from the cuff at a recommended rate of 3 mm / second. The trained person must observe the blood pressure of the cuff while listening with a stethoscope.

[0330] The first "knock" indicates the point at which the sphygmomanometer will be used to measure the patient's systolic blood pressure. When the "knock" stops, use the sphygmomanometer to measure the patient's diastolic blood pressure. The measured systolic and diastolic blood pressures should be recorded.

[0331] It is further recommended that measurements be taken in the other arm. Any discrepancies between the measurements of the arms should be recorded. In addition, the subject's position and the cuff size used should be recorded.

[0332] If a subject's blood pressure appears elevated, it is recommended that the patient's blood pressure be measured at least two additional times, with a rest period between measurements.

[0333] Example 2: Measuring Blood Pressure Using Arterial Resonance

[0334] An adhesive substrate including one or more ultrasound transducers and an electroacoustic transducer is adhered to a patient near a carotid artery. The electroacoustic transducer disposed on the adhesive substrate is activated.

[0335] The electroacoustic transducer varies within a range of audio frequencies. The ultrasound transducer detects when the resonance in the artery is at its maximum level. The resonant frequency is held for a moment and recorded. The ultrasound transducer determines the arterial wall thickness and diameter. The patient's blood pressure is then calculated and recorded.

[0336] Although preferred embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that these embodiments are provided as examples only. Without departing from the present invention, those skilled in the art will now appreciate that many variations, changes, and replacements may be employed in practicing the present invention. It should be understood that various alternatives to the embodiments of the present invention described herein may be employed. The accompanying claims are intended to define the scope of the present invention, and methods and structures within the scope of these claims and their equivalents are thereby covered.

Claims

1. A blood pressure measuring device, comprising: a first transducer configured to transmit a plurality of acoustic waves having a plurality of frequencies, the acoustic waves configured to vibrate a blood vessel of the subject; a second transducer configured to capture a plurality of ultrasound images of the blood vessel as the blood vessel vibrates in response to the acoustic waves; and A processing device configured to: determining a resonant frequency of the blood vessel based on a vibrational response of the blood vessel to the acoustic wave from the plurality of ultrasound images; and calculating the subject's blood pressure based on the wall thickness of the blood vessel, the radius or diameter of the blood vessel, and the determined resonant frequency; Wherein determining the resonance frequency of the blood vessel comprises: determining a frequency among the plurality of frequencies that maximizes vibration of the blood vessel based on the plurality of ultrasound images; as well as The frequency is selected as the resonant frequency. 2 . The blood pressure measurement apparatus according to claim 1 , wherein the plurality of ultrasonic images are used to measure the wall thickness of the blood vessel and the radius or the diameter of the blood vessel.

3. The blood pressure measurement device according to claim 1, further comprising: An audio signal generator is electrically coupled to the first transducer, the audio signal generator being configured to adjust a frequency of sound waves emitted by the first transducer. 4 . The blood pressure measurement device according to claim 3 , wherein the audio signal generator comprises at least one variable resistor that adjusts the frequency of the sound wave emitted by the first transducer. 5 . The blood pressure measurement apparatus according to claim 1 , wherein each of the frequencies is between 1 Hz and 3000 Hz. 6 . The blood pressure measurement device according to claim 5 , wherein each of the frequencies is between 670 Hz and 2300 Hz. The blood pressure measurement device according to claim 1 , wherein the blood vessel is a carotid artery of the subject.

8. The blood pressure measurement device of claim 1, wherein the first transducer is an audio speaker.

9. The blood pressure measurement device according to claim 8, wherein the audio speaker is a tweeter.

10. The blood pressure measurement device according to claim 1, further comprising: A substrate, wherein the substrate comprises an adhesive surface for adhering to the skin of the subject, wherein the first transducer and the second transducer are incorporated in the substrate. The blood pressure measurement device according to claim 10 , wherein the substrate is adhered near the blood vessel. 12 . The blood pressure measurement device according to claim 11 , wherein the blood vessel is a carotid artery.

13. The blood pressure measurement device according to any one of claims 10 to 12, wherein the substrate comprises alignment lines. The blood pressure measurement device of claim 13 , wherein the substrate comprises a transparent window. 15 . The blood pressure measurement device of claim 10 , further comprising a third transducer configured to capture a second set of one or more ultrasound images of the blood vessel.

16. The blood pressure measurement device of claim 15 , wherein the second transducer and the third transducer each have a respective resonant frequency, and wherein the second transducer includes a frequency response that partially overlaps with the frequency response of the third transducer; and the processing device processes measurements made by the first transducer and the second transducer.

17. The blood pressure measurement device of claim 16, wherein processing the measurements made by the first transducer and the second transducer comprises normalizing the first frequency response and the second frequency response. 18 . The blood pressure measurement device of claim 15 , further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

19. The blood pressure measurement device according to claim 15, further comprising: A substrate, wherein the substrate comprises an adhesive surface for adhering to the skin of the subject, wherein the first transducer, the second transducer, and the third transducer are incorporated into the substrate.

20. The blood pressure measurement device according to claim 19, wherein the substrate is adhered in the vicinity of the blood vessel.

21. The blood pressure measurement device according to claim 20, wherein the blood vessel is a carotid artery.

22. The blood pressure measurement device of claim 21, wherein the substrate includes alignment lines.

23. The blood pressure measurement device of claim 22, wherein the substrate further comprises a transparent window.

24. The blood pressure measurement device of claim 16, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

25. The blood pressure measurement device of claim 24, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer.

26. The blood pressure measurement device of claim 24, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer.

27. The blood pressure measurement device of claim 24, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency responses of the second transducer and the third transducer.

28. The blood pressure measurement device according to claim 24, further comprising: A substrate, wherein the substrate comprises an adhesive surface for adhering to the skin of the subject, wherein the first transducer, the second transducer, and the third transducer are incorporated in the substrate.

29. The blood pressure measurement device according to claim 28, wherein the substrate is adhered in the vicinity of the blood vessel.

30. The blood pressure measurement device according to claim 29, wherein the blood vessel is a carotid artery.

31. The blood pressure measurement device of claim 30, wherein the substrate includes alignment lines.

32. The blood pressure measurement device of claim 31, wherein the substrate further comprises a transparent window.

33. The blood pressure measurement device of claim 1, further comprising a third transducer configured to capture a second set of one or more ultrasound images of the blood vessel.

34. A blood pressure measurement device according to claim 33, wherein the second transducer and the third transducer each have a corresponding resonant frequency, and wherein the second transducer includes a frequency response that partially overlaps with the frequency response of the third transducer; and the processing device processes measurements made by the first transducer and the second transducer.

35. The blood pressure measurement device of claim 34, wherein the processing the measurements made by the first transducer and the second transducer comprises normalizing the first frequency response and the second frequency response.

36. The blood pressure measurement device of claim 33, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

37. The blood pressure measurement device of claim 34, further comprising a fourth transducer configured to capture a third set of one or more ultrasound images of the blood vessel.

38. The blood pressure measurement device of claim 37, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the second transducer.

39. The blood pressure measurement device of claim 37, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency response of the third transducer.

40. The blood pressure measurement device of claim 37, wherein the fourth transducer comprises a frequency response that partially overlaps with the frequency responses of both the second transducer and the third transducer.

41. The blood pressure measurement device of claim 1, wherein the first transducer is an electroacoustic transducer and the second transducer is a piezoelectric ultrasonic transducer.

42. The blood pressure measurement device of claim 1, further comprising a display.

43. The blood pressure measurement device of claim 42, wherein the display shows the frequency of the sound wave. The blood pressure measurement device according to claim 1 , wherein the blood vessel is an artery or a vein.

45. A method for use in the medical field, comprising: transmitting, using a first transducer proximate a blood vessel of a subject, a plurality of acoustic waves having a plurality of frequencies, the acoustic waves causing the blood vessel of the subject to vibrate; capturing a plurality of ultrasound images of the blood vessel using a second transducer as the blood vessel vibrates in response to the acoustic waves; determining a resonant frequency of the blood vessel based on a vibrational response of the blood vessel to the sound waves from the plurality of ultrasound images; determining the wall thickness and radius or diameter of the blood vessel using the second transducer; and calculating the subject's blood pressure based on the resonant frequency, the wall thickness of the blood vessel, and the radius or the diameter of the blood vessel; Wherein determining the resonance frequency of the blood vessel comprises: determining, based on the plurality of ultrasound images, a frequency among the plurality of frequencies that maximizes vibration of the blood vessel; as well as The frequency is selected as the resonant frequency.

46. ​​The method of claim 45, wherein determining the wall thickness and the radius of the blood vessel comprises: directing ultrasound waves to the blood vessel using the second transducer; and Ultrasonic waves reflected from the echogenic boundary of the blood vessel are received using the second transducer.

47. The method of claim 45, wherein after calculating the blood pressure, the method further comprises: determining an updated radius of the blood vessel and an updated velocity of blood flowing through the blood vessel using the first transducer and the second transducer; as well as An updated blood pressure is calculated based on the updated radius and the updated speed.

48. The method of claim 45, wherein each of the frequencies is between 670 Hz and 2300 Hz.

49. The method of claim 45, further comprising capturing, using a third transducer, a second plurality of ultrasound images of the blood vessel as the blood vessel vibrates in response to the acoustic waves.

50. The method of claim 49, further comprising normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer using the second plurality of ultrasound images of the blood vessel captured by the third transducer.

51. The method of claim 49, further comprising capturing a third plurality of ultrasound images of the blood vessel using a fourth transducer as the blood vessel vibrates in response to the acoustic waves.

52. The method of claim 51, further comprising normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer using the second plurality of ultrasound images of the blood vessel captured by the third transducer.

53. The method of claim 52, further comprising normalizing the plurality of ultrasound images of the blood vessel captured by the second transducer using the third plurality of ultrasound images of the blood vessel captured by the fourth transducer.

54. The method of claim 45, wherein the plurality of frequencies of the plurality of sound waves are between 1 Hz and 3000 Hz.

55. The method of claim 45, wherein the second transducer is a piezoelectric ultrasonic transducer.

56. The method of claim 55, wherein the piezoelectric ultrasonic transducer comprises a sampling rate of at least 3 kHz.

57. The method of claim 46, further comprising measuring a Doppler shift of the reflected ultrasonic wave and calculating a wave velocity of the blood vessel.

58. The method of claim 57, wherein the Doppler shift is measured by a piezoelectric ultrasound transducer.

59. The method of claim 45, wherein the blood vessel is a carotid artery.

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