Patent Description:
<CIT> discloses a blood pressure measurement device comprising:.

According to an aspect of the present invention, there is provided a blood pressure measurement device, as set out in claim <NUM>.

According to another aspect of the present invention, there is provided a non-transitory computer-readable storage medium storing instructions executable by a processor of a blood pressure measurement device, as set out in claim <NUM>.

According to another aspect of the present invention, there is provided a method, as set out in claim <NUM> Further aspects are set out in the dependent claims.

A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also "Figure" and "FIG. " herein), of which:.

Provided herein is a device which will enable continuous, non-invasive blood pressure measurement. In some embodiments, the device comprises one or more ultrasound transducers. In some embodiments, the device presented herein removes the need for a calibration step and provides a continuous, non-invasive blood pressure monitoring capability in an inexpensive and easy-to-use form.

According to some embodiments, the technology disclosed herein is directed to a blood pressure measurement apparatus that enables continuous, non-invasive blood pressure measurement using sound and ultrasound 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, a resonant frequency at which the artery vibrates most strongly may be determined. This resonant frequency may be combined measurements of the radius of the artery to calculate an absolute blood pressure. In some embodiments, the radius of the artery is measured by one or more of the ultrasound transducers utilizing ultrasound imaging methods. Methods of measuring blood pressure utilizing acoustic stimulation may eliminate the need for a separate calibration step and blood pressure monitoring may be provided in an inexpensive and easy-to-use form.

To understand the principles underlying the technology described herein, it is instructive to consider the forces underlying blood flow through an artery. <FIG> depicts an arterial wall <NUM>, which may be represented as a tube composed of elastic material. The dynamics of arterial wall <NUM> are dictated by the balance between blood pressure <NUM> pushing the wall out and tensile force <NUM> holding the wall together. Laplace's law states that for fluid flowing through a cylindrical elastic membrane with constant radius R, the fluid pressure P and the tensile force in the membrane T are related by the equation T = RP.

The radius of the artery may be measured using one or more ultrasound devices. As such, the remaining task for determining the fluid pressure P is measuring the tensile force in the wall of the artery. In some embodiments, the tensile force may be determined by measuring how the arterial wall responds to an impulse from an acoustic stimulus. <FIG> depicts this process. In some embodiments, an acoustic stimulus <NUM>, produced by an electroacoustic transducer <NUM>, is used to induce measurable perturbations in the arterial wall <NUM>. This method may utilize an acoustic stimulus which is emitted at an acoustic intensity well below the acoustic intensity limits specified by FDA guidelines. By focusing on vibrational modes around the circumference of the artery, and particularly, the lowest-energy vibration which can be excited around the circumference, the tensile force may be estimated as follows.

The lowest-energy vibration has a wavelength of λ = πR. The mechanical properties of the arterial wall also dictate a speed, vw, at which vibrations travel along the circumference of the wall. The wave speed and wavelength quantities combine to produce a resonant frequency f = vw/λ. If an external stimulus (e.g. a sounds wave) is applied with 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. Thus, f may be determined by applying an acoustic stimulus across a frequency range and finding the frequency at which the artery vibrates most strongly. This, in turn, will tell us the wave speed vw = λf = πRf. In an elastic material under tension, with volumetric density ρ and thickness h, this wave velocity is related to the tensile force via the equation T = phvw<NUM>. The volumetric density of the arterial wall is nearly constant across patients, and the wall thickness may be measured from an ultrasound image in the same manner as R. Using this information, pressure may be determined based on Equation (<NUM>): <MAT>.

Thus, measuring h and R via standard ultrasound imaging and measuring f by determining the resonance point by the artery's vibrational response will allow calculation of a blood pressure.

To illustrate the feasibility of the continuous blood pressure measurement techniques described herein, the following factors may be considered. First, to illustrate the practically of this blood pressure measurement method, it may be ensured that the resonant frequency, f, will take on a reasonable value in the typical patient. In a common carotid artery, the measurement quantities typically have values of about <NUM> mmHg for P, <NUM> for R, <NUM> for h, and <NUM>/mL for p. Inserting these values into Equation (<NUM>) yields a predicted resonant frequency of approximately <NUM>. Thus, in order to detect this vibration, sampling may need to be conducted at least ~<NUM> in order to surpass the Nyquist rate. Currently available ultrasound instruments may produce imaging rates of at least <NUM>, far surpassing the minimum sampling rate. <NUM> is also far higher than the frequency of heartbeats, which in human patients does not exceed <NUM> even under extreme conditions. Because resonant vibrations occur at a much higher frequency than the rate of change in pressure from the heartbeat, blood pressure (and thus the tensile force) may be assumed as constant over the duration of each vibrational cycle, substantially simplifying analysis. Furthermore, <NUM> falls comfortably in the range of existing commercial speakers, so no specialized hardware is required to produce a tone with sufficient amplitude and frequency to stimulate arterial vibration.

Second, another measure of feasibility is the frequency range over which the electroacoustic transducer may need to operate. Under extreme conditions, a patient's blood pressure may be as low as <NUM> mmHg or as high as <NUM> mmHg. With the arterial dimensions given above, this corresponds to a resonant frequency range of <NUM> to <NUM>, still well within the acoustic range produced by commercial speakers.

Third, the level of frequency resolution required to obtain a useful level of precision in pressure measurements may also be considered. In order to be comparable to the current clinical gold standard of continuous blood pressure measurement, a blood pressure measurement device should be able to measure pressure to a precision of at least ±<NUM> mmHg. With the arterial dimensions given above, a blood pressure swing of this magnitude would result in a change in the resonant frequency of ±<NUM>, or roughly <NUM>%. This level of precision can also be readily obtained from commercially available speakers.

<FIG> is a block diagram illustrating some components of a continuous blood pressure measurement device <NUM>, in accordance with some embodiments of the disclosure. As depicted, device <NUM> includes an audio signal generator <NUM>, an electroacoustic transducer <NUM>, at least one ultrasound sensor <NUM>, at least one processing device <NUM>, at least one machine readable medium <NUM>, a wireless transmitter <NUM>, and, optionally, one or more non-ultrasound sensor(s) <NUM>. The electrical components of device <NUM> may be powered by a battery <NUM> that connects to power circuitry <NUM> for distributing power. The battery <NUM> may be rechargeable (e.g., via a USB port and/or an AC/DC converter). Although a battery <NUM> is shown in this example, it should be appreciated that any suitable battery or power supply technologies may be used to power the components of device <NUM>. For example, lithium-ion batteries, cell batteries, piezo or vibration energy harvesters, photovoltaic cells, AC/DC sources, or other like devices can be used.

Electroacoustic transducer <NUM> may be implemented as an audio speaker that can output sound waves within a suitable range of frequencies (e.g., to find a resonant frequency of a blood vessel). For example, the speaker may be implemented as a bass speaker, a mid-range speaker, and/or a treble speaker (e.g., tweeter). In some embodiments, a combination of speakers may be used to output sound within a suitable range of frequencies. An audio signal generator <NUM> that adjusts a frequency of sound waves may be coupled to transducer <NUM>. In some embodiments, the audio signal generator comprises at least a variable resistor that adjusts a frequency of the sound waves. The variable resistor may be a potentiometer. In some embodiments, the blood pressure measurement device <NUM> may display the frequency of the sound waves. In some embodiments, the audio signal generator <NUM> is a component of a processing device <NUM>.

In some embodiments, the sound waves output by electroacoustic transducer <NUM> may be configured to be varied over a range of frequencies from about <NUM> to about <NUM>,<NUM>. In an embodiment, the range of frequencies the electroacoustic transducer <NUM> is varied over is about <NUM> to about <NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, or about <NUM>,<NUM> to about <NUM>,<NUM>. In some embodiments, the range of frequencies the electroacoustic transducer <NUM> is varied over is about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>. In some embodiments, the range of frequencies the electroacoustic transducer <NUM> is varied over is at least about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>. In some embodiments, the range of frequencies the electroacoustic transducer <NUM> is varied over is at most about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>.

] In some embodiments, audio signal generator <NUM> may be configured to adjust the frequency of sound waves output by transducer <NUM> in suitable increments to search for the resonant frequency of vibration at a sufficient accuracy. For example, the frequency may be adjusted in increments between <NUM> and <NUM> such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. The accuracy of the estimated resonant frequency may be improved by decreasing the size of each increment. Conversely, the time it takes to determine the resonant frequency may be improved by increasing the size of each increment.

The one or more ultrasound sensors <NUM> (individually referred to as "an ultrasound sensor <NUM>") are configured to collect imaging data of a subject (e.g., blood vessel a subject). The imaging data may be used to measure the wall thickness of a blood vessel and the radius of the blood vessel. The blood vessel may be an artery or a vein. Additionally, the imaging data may be used to determine the resonant frequency of vibration of the blood vessel, which vibrates in response to the sound waves output by electroacoustic transducer <NUM>. Each ultrasound sensor <NUM> includes a transducer configured to convert electricity to ultrasound and vice versa. For example, the transducer may be a piezoelectric transducer that oscillates and produces an ultrasonic pulse when an AC voltage is applied. Alternatively, the transducer may be a capacitive transducer that produces ultrasonic soundwaves using electrostatic fields between a conductive diaphragm and a backing plate. Ultrasound soundwaves may be a produced at a frequency greater than or equal to about <NUM> kilohertz (KHz). In some embodiments, the transducer of an ultrasound sensor <NUM> may produce ultrasound in a frequency anywhere between <NUM> megahertz (MHz) and <NUM> When a reflected ultrasound signal (i.e., an "echo") is received by the transducer, an electrical signal may be generated and used by ultrasound sensor <NUM> to determine a distance to the imaged subject. In some embodiments, the transducer may produce ultrasound in a frequency between <NUM> and <NUM>.

In some embodiments, ultrasonic measurement is performed using only a single piezoelectric element. Ultrasonic waves in the body are primarily reflected by sharp boundaries between regions of different densities. Many arteries, including the carotid, are embedded in soft tissue of relatively uniform density, so the only significant sources of echoes are the boundaries <NUM> formed by the inner and outer edges of the arterial wall <NUM> as depicted by <FIG>. By measuring the delay between echoes received from these different boundaries, accurate determination of arterial radius and wall thickness from a single piezoelectric ultrasound transducer element <NUM> is achievable.

As depicted in <FIG>, when an acoustic stimulus <NUM> is applied to an artery (e.g., using a tweeter), the resulting vibration will cause the arterial diameter, observed using ultrasound imaging, to oscillate sinusoidally as the axis perpendicular to the incident sound waves expands and contracts. If the power of the stimulus is kept constant this oscillation will have maximum amplitude when the stimulus is applied at a frequency matching the resonant frequency of the arterial wall <NUM>. Thus, the resonant frequency may be determined by applying the acoustic stimulus at a range of different frequencies and determining, via ultrasound imaging, the point at which the observed amplitude of oscillation is at a maximum. With this setup, the velocity of the wall may also be determined independently of its position by measuring the Doppler shift of the returned echo. Since wall velocity will also be maximized at resonance, the velocity measurement will give an orthogonal means of determining the resonance point and thereby increase precision.

In a further embodiment, precision may be increased by increasing the number of ultrasonic piezoelectric elements. In some embodiments, four piezoelectric elements may be utilized. One of the piezoelectric elements could produce an ultrasonic signal while the other three listen for echoes, allowing for triangulation of echoes as they are received. This embodiment may allow for better exclusion of spurious echoes and thereby provide better isolation of echoes being produced by the arterial wall.

Ultrasound that enters tissue may be transmitted, attenuated or reflected. While higher frequency ultrasound may provide for a higher resolution signal, it may provide poor depth penetration of imaged tissue. Conversely, while lower frequency ultrasound may provide for a lower resolution signal, it may provide better depth penetration of imaged tissue. To overcome these limitations, some embodiments may use multiple ultrasound sensors <NUM>, with each ultrasound sensor <NUM> having a transducer configured with a unique resonance frequency. Specifically, the ultrasound transducers may be selected such that their acoustic frequency responses are non-overlapping. By actuating the transducers in a time interleaved fashion, each sensor may be used to image a surface of a sample at a unique depth. Furthermore, each transducer may be simultaneously actuated with a combination of other transducers to generate higher order harmonics that allow for sub-pixel feature resolution. In some embodiments, ultrasound sensor transducers may be selected that are adjacent and partially overlapping in frequency response, allowing for the normalization of the measurement of any pair of sensors, thereby reducing systemic sources of noise and significantly increasing signal integrity. Additionally, the simultaneous interrogation of a surface with transducers with distinct resonance frequencies may be used to generate super-resolution ultrasound images. In some embodiments, the frequency overlap between sensors may be configured to be about <NUM> or less. In some embodiments, the frequency overlap between sensors may be configured such that a frequency response range of one ultrasound sensor does not overlap with a resonant frequency of another ultrasound sensor, where the resonant frequency of the ultrasound sensor may refer to an operating frequency at which the transducer most efficiently converts electrical energy into mechanical energy.

Processing device <NUM> may be configured to control operation of the components of device <NUM>, including audio signal generator <NUM> (which in some embodiments is a component of processing device <NUM>), electroacoustic transducer <NUM>, ultrasound sensor(s) <NUM>, and non-ultrasound sensor(s) <NUM> (further discussed below). For example, processing device <NUM> may be configured to cause electroacoustic transducer <NUM> to emit sound at a specific frequency or range of frequencies. Additionally, processing device <NUM> may configured to cause ultrasound sensors <NUM> and/or non-ultrasound sensor(s) <NUM> to perform image acquisition. Furthermore, processing device <NUM> may receive, store (e.g., in machine readable medium <NUM>), and/or process signal measurements received from ultrasound sensors <NUM> and/or non-ultrasound sensors <NUM>. In some embodiments, processing device <NUM> may also be configured to use signal measurements received from ultrasound sensors <NUM> to continuously measure blood pressure of an artery or other blood vessel. The aforementioned methods may be applied by processing device <NUM> by executing instructions stored on a machine readable medium <NUM>. In one embodiment, processing device <NUM> may be implemented as a single integrated circuit (IC) microcontroller that includes memory (e.g., machine readable medium <NUM>) for storing program information and data.

As described above, continuous blood pressure measurement device <NUM> may accurately determine blood pressure solely from arterial radius, wall thickness, and resonant frequency. However, those three values are not the only information that may be determined. In some embodiments, in the course of measuring the vibrational response of the artery under a range of frequencies, additional information may be obtained, including: the strength and width of the resonance peak, the baseline excitation level at low frequencies, and/or the level of excitation of higher-energy vibrational modes. Changes in these parameters may also be observed over the course of a heartbeat as blood pressure and tension levels change. Ultrasound imaging of the artery may also yield information about the echogenicity of the arterial wall, which may provide insight into levels of calcification and plaque buildup. All the additional information may be used to refine calculations, attain better precision, and/or provide additional information about the patient's overall health.

In some embodiments, continuous blood pressure measurement device <NUM> may include one or more non-ultrasound sensors <NUM> to allow for multi-modal measurement of other health indicators besides blood pressure. For example, LED light sources and photodiode receivers may be integrated onto the wireless platform to measure blood oxygenation through pulse oximetry. Other example sensors that may be implemented include sensors for detecting body fluid status, ejection fraction of the heart, or other vital measurements may be integrated into the hardware/sensor package. In some embodiments, the measurements made using non-ultrasound sensors <NUM> may be correlated and normalized with ultrasound measurements used to calculate blood pressure. By virtue of using additional modalities besides ultrasound sensors <NUM> to measure blood pressure, the accuracy of device <NUM> may be improved.

In the example, of <FIG>, continuous blood pressure measurement device <NUM> includes a wireless transmitter <NUM> (e.g., transceiver) that is configured to communicate ultrasound measurement data to wireless receiver <NUM> (e.g., transceiver) of display system <NUM>. Depending on the ultrasound imaging application, the received ultrasound measurement data may be processed using processing device <NUM> of display system <NUM> (e.g., into a format appropriate for display) and/or displayed using display <NUM>. Instructions for formatting may be stored on a machine readable medium <NUM>. For example, the display <NUM> may be a component of a cardiac monitor, a mobile device (e.g., smartphone or head mounted display), or some other suitable display device. The display <NUM> may also display the frequency of sound waves electroacoustic transducer <NUM> is configured to emit (e.g., via audio signal generator <NUM>). The wireless communication link between wireless transmitter <NUM> and wireless receiver <NUM> may be a radio frequency link such as a Bluetooth® or Bluetooth® low energy (LE) link, a Wi-Fi® link, a ZigBee link, or some other suitable wireless communication link. In some embodiments, data transfer between device <NUM> and display system <NUM> may be achieved using a wired transmitter or other suitable wired interface. For example, data may be transferred using a USB-C connector, a USB <NUM>. x or <NUM>. x connector, a micro-USB connector, a THUNDERBOLT connector, an Ethernet cable, etc..

In some embodiments, display <NUM> and/or the functions of display system <NUM> may be integrated into continuous blood pressure measurement device <NUM>. In some embodiments, continuous blood pressure measurement device <NUM> may still retain transmitter <NUM> to communicate historical or current blood pressure measurement data to an external device such as a smartphone.

<FIG> is an operational flow diagram illustrating an example method <NUM> for measuring blood pressure of a subject, in accordance with some embodiments of the disclosure. In some embodiments, method <NUM> may be implemented using a continuous blood pressure measurement device <NUM> as described above.

At operation <NUM>, an ultrasound transducer and electroacoustic transducer are brought into proximity of a blood vessel of the subject. For example, a continuous blood pressure measurement device <NUM> including an electroacoustic transducer <NUM> and ultrasound sensor <NUM> may be brought into proximity of an artery (e.g., carotid artery or brachial artery) of the patient. In some embodiments, a substrate <NUM> including device <NUM> may be aligned with the subject's artery and subsequently adhered. For example, the substrate <NUM> may be adhered to the patient's arm in proximity to the brachial artery. Alternatively, the substrate may be adhered to the patient's neck in proximity to the carotid artery. In some embodiments, the position of the ultrasound transducer and electroacoustic transducer (e.g., device <NUM> or substrate <NUM>) may be adjusted to maximize the amplitude and/or signal-to-noise ratio of measurement signals.

At operation <NUM>, the electroacoustic transducer is actuated to emit a plurality of soundwaves having a plurality of frequencies. For example, audio signal generator <NUM> may be configured to cause electroacoustic transducer <NUM> to emit sound waves at a plurality of different frequencies. The sound waves may produce a vibrational response in blood vessel (e.g., in a cross section of the blood vessel that the sound waves are directed to). The vibrational response may have an amplitude that varies depending on the frequency of the sound waves.

In some embodiments, the frequency of each of the sound waves may be between <NUM> and <NUM>. In some embodiments, the frequency of each of the sound waves may be between <NUM> and <NUM>. In some embodiments, the frequency of each of the soundwaves is about <NUM> to about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves about <NUM> to about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, or about <NUM>,<NUM> to about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves at least about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves at most about <NUM>, about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>.

In some embodiments, the frequency of each of the soundwaves is about <NUM> to about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves is about <NUM> to about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves is about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, about <NUM>,<NUM> to about <NUM>,<NUM>, or about <NUM>,<NUM> to about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves is about <NUM>, about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves is at least about <NUM>, about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>. In some embodiments, the frequency of each of the soundwaves is at most about <NUM>, about <NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, about <NUM>,<NUM>, or about <NUM>,<NUM>.

At operation <NUM>, based on the vibrational response of the blood vessel to the soundwaves at each of the plurality of different frequencies, the resonant frequency of vibration of the blood vessel may be determined (e.g., based on the frequency that produced the greatest amplitude of response). In some embodiments, the resonant frequency may be held for a moment and then recorded in memory (e.g., in computer readable medium <NUM>).

In some embodiments, an ultrasonic sensor is used to detect the resonant frequency by capturing images of the blood vessel (e.g., the cross section) as it vibrates in response to different applied frequencies. The frequency that produces the highest amplitude of vibration may be selected (e.g., by a processing device communicatively coupled to the sensor) as the resonant frequency. In some embodiments, the ultrasonic transducer has a sampling rate of at least <NUM>.

In some embodiments, the electroacoustic transducer and ultrasonic sensor may be placed adjacent one another and driven in synchronization. For example, a small speaker may be placed on either side of the ultrasonic sensor, and the two devices/components may be synchronously driven.

In some embodiments of operations <NUM> and <NUM>, to improve the speed of finding the resonant frequency, an optimized search algorithm may be used to adjust the frequency of soundwaves output by the electroacoustic transducer in-between measurements. The search algorithm may utilize suitable boundary conditions (e.g., maximum frequency, minimum frequency, rate of frequency adjustment, etc.). The search algorithm may begin with a wide frequency scan over a large frequency range that uses large changes of frequency between measurements to find a narrower frequency range within which the resonant peak lies, and then transition to a narrow frequency scan within this narrower frequency range to find the resonant frequency. In some embodiments, the resonant frequency may be held for a moment and then recorded in memory (e.g., in computer readable medium <NUM>).

At operation <NUM>, the wall thickness and radius of the blood vessel (e.g., for the cross section) are determined. These parameters may be determined from the ultrasound images captured using an ultrasound sensor <NUM>. For example, echo-mode ultrasonography may be utilized to determine the wall thickness and radius. Ultrasonic waves may be directed to the blood vessel and ultrasonic waves reflected from echogenic boundaries of the blood vessel may be received. A doppler shift of the reflected ultrasonic waves may be measured using the ultrasonic sensor, and a wave velocity of the blood vessel may be calculated based on this doppler shift. In some embodiments, multiple ultrasonic transducers may be utilized to improve imaging accuracy and/or speed. For example, one transducer could produce an ultrasonic signal while three others listen for echoes, allowing for triangulation of echoes as they are received.

At operation <NUM>, the blood pressure is calculated based on the resonant frequency, the wall thickness, and the radius. The calculated blood pressure may establish a baseline diastolic pressure. Once an absolute diastolic pressure is established, changes in blood pressure over time (e.g., using doppler ultrasound imaging) may be measured with the ultrasound sensor(s) to extract a continuous waveform. When employing this type of differential measurement, a small but persistent inaccuracy aggregate into a large drift over the course of many heartbeats. Thus, periodic re-baselining may be required to maintain accuracy for a patient under long-term monitoring. This demonstrates another advantage of the proposed method; while other baselining techniques would require repeated application of an external pressure cuff or force probe, using the method herein, the baselining can be performed automatically at regular intervals using the electroacoustic transducer and the same ultrasonic hardware being employed to perform the continuous monitoring.

In some embodiments, device <NUM> or an external display system <NUM> may display the computed blood pressure over time. In some embodiments, a processing device <NUM> of continuous blood pressure measurement device <NUM> may perform the necessary DSP and calculations to arrive at the patient's blood pressure.

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

In some embodiments, the system comprises an ultrasound platform for driving one or more ultrasonic transducers. In some embodiments, the ultrasound platform processes and/or conditions signals received by one or more ultrasound transducers.

In some embodiments, depicted by <FIG>, a continuous blood pressure measurement device <NUM> may be incorporated into a substrate <NUM>. As illustrated, the device <NUM> may include one or more alignment lines <NUM> or other markings for aligning one or more sensors or transducers <NUM>, <NUM>, <NUM>, <NUM> of the device <NUM> with an artery of a patient prior to taking actuating transducer <NUM> and taking ultrasound measurements. In some embodiments, a transparent window <NUM> is provided for aligning one or more sensors or transducers <NUM>, <NUM>, <NUM>, <NUM> of the device <NUM> with an artery of a patient prior to taking actuating transducer <NUM> and taking ultrasound measurements. In some embodiments, the device may comprise a transparent window <NUM> for viewing the artery behind the substrate during placement. A combination of a transparent window and alignment marker may further facilitate placement of the device.

Additionally, substrate <NUM> may include an adhesive that used to hold substrate in place and in alignment with the patient's artery. During application, the adhesive may be exposed by peeling away a paper backing. Adhesives 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 may be made on the radial or ulnar arteries. By virtue of some embodiments, the measurement of blood pressure may be noninvasive, reliable, fast, and provide continuous measurement, thus considering beat to beat variation. These continuous variations may be presented to a user on a display system <NUM> as described above.

In some embodiments, the sensors and transducers of the device <NUM> include at least one ultrasound transducer and at least one electroacoustic transducer. Inclusion of more than one ultrasound transducers may allow for increased resolution as described herein. In some embodiments, a device comprises two ultrasound transducers and one electroacoustic transducer. In some embodiments the patch comprises three ultrasound transducers and one electroacoustic transducer. In some embodiments the patch comprises four ultrasound transducers. Each transducer <NUM>, <NUM>, <NUM>, <NUM> may be configured as a transmitter, receiver, or both a transmitter and receiver (transceiver). In some embodiments, transducer <NUM> is configured as a transmitter and transducer <NUM> is configured as a receiver. In some embodiments, transducer <NUM> is configured as a transmitter and transducer <NUM> is configured as a receiver. In some embodiments, transducer <NUM> is configured as a transmitter and transducer <NUM> is configured as a receiver. In some embodiments, transducer <NUM> is configured as a transmitter and transducer <NUM> is configured as a receiver. In some embodiments, transducer <NUM> is configured as a transmitter and transducer <NUM> is configured as a receiver. In some embodiments, transducer <NUM> is configured as a transmitter and transducer <NUM> is configured as a receiver. In some embodiments, transducers <NUM> and <NUM> are configured as transmitters and transducers <NUM> and <NUM> are configured as receivers. In some embodiments, transducers <NUM> and <NUM> are configured as transmitters and transducers <NUM> and <NUM> are configured as receivers. In some embodiments, transducers <NUM> and <NUM> are configured as transmitters and transducers <NUM> and <NUM> are configured as receivers. In some embodiments, transducers <NUM> and <NUM> are configured as transmitters and transducers <NUM> and <NUM> are configured as receivers. In some embodiments, transducer <NUM> is configured as transmitters and transducers <NUM> and <NUM> are configured as receivers. In some embodiments, transducer <NUM> is configured as transmitters and transducers <NUM> and <NUM> are configured as receivers.

In some embodiments, the one or more transducers is incorporate into a wearable device. Wearable devices may include a wristband or watch, wherein the one or more transducers are directed to a brachial artery to determine a mean arterial pressure. In some embodiments, the substrate comprising the one or more transducers is incorporated into a wearable device. The wearable device may communicate wirelessly with an external computing device to display or record data.

In some embodiments, the device comprises four ultrasound transducers and an electroacoustic transducer or speaker. In some embodiments, images or signals captured by the ultrasound transducers are input into a rotational matrix. Rotation and/or skew matrices may be applied to properly orient the received signals for convolution, deconvolution, or normalization. Normalization may be applied to received signals, as disclosed herein. In some embodiments, a skew parameter is applied to the rotational matrices.

Each ultrasonic transducer of the plurality of ultrasonic transducers may be configured to transmit a transmitted ultrasonic imaging signal to an object. Each ultrasonic transducer of the plurality may be configured to transmit a transmitted ultrasonic imaging signal having a frequency of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> Each ultrasonic transducer of the plurality may be configured to transmit a transmitted ultrasonic imaging signal having a frequency that is within a range defined by any two of the preceding values.

Each ultrasonic transducer of the plurality of ultrasonic transducers may be configured to receive a received ultrasonic imaging signal from an object. Each ultrasonic transducer of the plurality may be configured to receive a received ultrasonic imaging signal having a frequency of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> Each ultrasonic transducer of the plurality may be configured to receive a received ultrasonic imaging signal having a frequency that is within a range defined by any two of the preceding values.

Each ultrasonic transducer of the plurality may be configured both to transmit and to receive. Each ultrasonic transducer of the plurality may be configured to transmit transmitted ultrasonic imaging signals or receive received ultrasonic imaging signals at a frequency that is the same as one or more of the frequencies transmitted or received by other ultrasonic transducer of the plurality. Each ultrasonic transducer of the plurality may be configured to transmit transmitted ultrasonic imaging signals or receive received ultrasonic imaging signals at a frequency that is different from all of frequencies transmitted or received by all other ultrasonic transducer of the plurality. Each of the ultrasonic transducer of the plurality may be configured to transmit or receive at the same time as one or more other ultrasonic transducer of the plurality.

For instance, a first transmitted imaging signal of a first ultrasonic transducer of the plurality may have a frequency of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> A second transmitted imaging signal of a second ultrasonic transducer of the plurality may have a frequency that is in a range from about <NUM> to about <NUM>. A first received imaging signal of a first ultrasonic transducer of the plurality may have a frequency of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> A second received imaging signal of a second ultrasonic transducer of the plurality may have a frequency that is in a range from about <NUM> to about <NUM>.

In another example, a first transmitted imaging signal of a first ultrasonic transducer of the plurality may have a frequency that is in a range from about <NUM> to about <NUM> A second transmitted imaging signal of a second ultrasonic transducer of the plurality may have a frequency that is in a range from about <NUM> to about <NUM>, but that is different from the frequency of the first transmitted imaging signal. A first received imaging signal of a first ultrasonic transducer of the plurality may have a frequency that is in a range from about <NUM> to about <NUM> A second received imaging signal of a second ultrasonic transducer of the plurality may have a frequency that is in a range from about <NUM> to about <NUM>, but that is different from the frequency of the first received imaging signal.

A third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal of a third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer, respectively, may have a frequency that is about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal may have a frequency that is within a range described by any two of the preceding values. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal may have a value that is in a range from about <NUM> to about <NUM>. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted imaging signal may have a frequency that is different from one or more of the frequencies of the first and second transmitted imaging signals.

A third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal of a third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducer, respectively, may have a frequency that is about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may have a frequency that is within a range described by any two of the preceding values. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may have a value that is in a range from about <NUM> to about <NUM>. The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth received imaging signal may have a frequency that is different from one or more of the frequencies of the first and second transmitted imaging signals.

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

The received imaging signals may be subjected to pre-processing operations. For instance, a first received imaging signal may form a basis for normalizing other received imaging signals. A second received imaging signal may be normalized by the first received imaging signal. A 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.

The system may comprise a transmit (Tx) generator. The transmit generator may comprise a host computer, software-defined radio, and ultrasound 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 of the ultrasonic transducers to transmit a first, second, third, or fourth transmitted ultrasonic imaging signal, respectively. The Tx generator may operate any two or more of the first, second, third, or fourth ultrasonic imaging transducers simultaneously. The system may further comprise an image synthesis module. The image synthesis module may comprise a receive (Rx) beamformer. The Rx beamformer may be configured to operate any one of ultrasonic transducers to receive a first, second, third, or fourth received ultrasonic imaging signal, respectively. The image synthesis module may subject the received ultrasonic imaging signals to an ultrasonic image reconstruction operation. For instance, the image synthesis module may subject the received ultrasonic imaging signals to a delay and sum operation. The image synthesis module may subject the received ultrasonic imaging signals to any ultrasonic image reconstruction operation. The Tx generator may be configured to operate fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducers to transmit fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted ultrasonic imaging signals, respectively. The Tx generator may 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 simultaneously. Similar, the Rx beamformer may be configured to operate fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth ultrasonic transducers to transmit fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, or sixteenth transmitted ultrasonic imaging signals, respectively.

The Tx generator may 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 ultrasonic transducers to transmit in sequence.

<FIG> schematically illustrates a method of forming ultrasonic images from a plurality of ultrasonic transducers. The method may utilize measurements from a plurality of ultrasonic imaging sensors. The method may utilize single-pixel and multi-pixel image processing techniques. In the single-pixel case, an n-th ultrasonic imaging measurement (where n is a positive integer) may be input to a signal processing unit. The signal processing unit may apply any ultrasonic signal processing procedure to the n-th ultrasonic imaging measurement. The signal processing unit may output a signal processed measurement to an image processing unit and to a single-pixel feature extraction unit. The image processing unit may apply any ultrasonic image processing procedure. The single-pixel feature extraction unit may apply any ultrasonic single-pixel feature extraction procedure. The single-pixel feature extraction unit may output an extracted feature to an operator.

In the multi-pixel case, an m-th and an (m+<NUM>)-th (where m and m+<NUM> are positive integers) ultrasonic imaging measurement may be input to a multi-pixel image synthesis unit and to a multi-pixel feature extraction unit. The image synthesis unit may apply any ultrasonic image synthesis procedure. The multi-pixel feature extraction unit may apply any ultrasonic multi-pixel feature extraction procedure. The multi-feature extraction unit may output an extracted feature to an operator. Multi-pixel extraction may be utilized to build 3D pixels (i.e. voxels).

In the multi-pixel case, image processing methods such as <NUM>-dimensional smoothing filters, Harr filters, Gaussian filters, and integrators may be used to improve the recorded image. Furthermore, each pixel may be filtered in the time-domain to accentuate signal features. A single or multiple Butterworth, Chebyshev, and elliptic filters can be used to suppress noise and enhance feature extraction.

Sensors of the device may further comprise a temperature sensor, an optical sensor, an electrical sensor, a chemical sensor and an electrochemical sensor. In some embodiments, additional sensors allow measurement of body temperature, a respiration rate, a blood pressure level, and a blood oxygenation saturation (spO<NUM>) level.

The stethoscope device may comprise a first ultrasonic transducer, a light source, and a light detector. The stethoscope device may optionally comprise 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 above the skin of a subject (such as skin in a subject's arm). As a bolus of blood travels through an artery beneath the skin of the subject, 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 the optical signal may be scattered, dispersed, or reflected from the bolus. The scattered, dispersed, or reflected ultrasonic signal or optical signal may be detector 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 yield a velocity of the blood bolus as 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.

Ultrasonic tissue imaging may be plagued by poor optical and acoustic transmissivity as well as beam scattering. To address such difficulties and increase resolution, a method of multi-wavelength ultrasound imaging by collection of information from a plurality of ultrasound sensors, where each sensor has an ultrasound transducer with a unique resonance frequency may be utilized. By virtue of resonating physiology with multiple ultrasound sensors operating at distinct resonance frequencies, ultrasound emitted by the plurality of transducers may simultaneously penetrate various depths in a given cross-sectional area of physiology (e.g., tissue). In particular, ultrasound sensors having acoustic frequency responses may be actuated in a time interleaved fashion such that each sensor may be used to image a physiological surface at a unique depth. This may enable high resolution tomography without needing to increase the gain or the number of ultrasound imaging sensors. Furthermore, each sensor may be simultaneously actuated with a combination of other sensors to generate higher order harmonics which allow for sub-pixel feature resolution (i.e., super resolution imaging).

As used herein to refer to a transducer, the term "resonant frequency" generally refers to an 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 an operating frequency at which the piezoelectrical material most readily vibrates and converts electrical energy into mechanical energy most efficiently.

Ultrasound that enters tissue may be transmitted, attenuated or reflected. While higher frequency ultrasound may provide for a higher resolution signal, it may provide poor depth penetration of imaged tissue. Conversely, while lower frequency ultrasound may provide for a lower resolution signal, it may provide better depth penetration of imaged tissue. To overcome these limitations of conventional ultrasound imaging systems, each ultrasound sensor may have a transducer configured with a unique resonance frequency. Specifically, the ultrasound transducers may be selected such that their acoustic frequency responses are non-overlapping. By actuating the transducers in a time interleaved fashion, each sensor may be used to image a surface of a sample at a unique depth. Furthermore, each transducer may be simultaneously actuated with a combination of other transducers to generate higher order harmonics that allow for sub-pixel feature resolution.

As shown by <FIG>, selecting transducers <NUM>, <NUM>, <NUM> having frequencies which are partially overlapping may allow for self-normalization and cross-correlation of signals. In some embodiments, by selecting sensor transducers that are adjacent and partially overlapping in frequency response, the measurement of any pair of sensors may be normalized, thereby reducing systemic sources of noise and significantly increasing signal integrity. Additionally, the simultaneous interrogation of a surface with transducers with distinct resonance frequencies can be used to generate super-resolution ultrasound images of an object <NUM>. In some embodiments, the frequency overlap between sensors <NUM>, <NUM>, <NUM> may be configured to be about <NUM> or less. In some embodiments, the frequency overlap between sensors may be configured such that a frequency response range of one sensor does not overlap with a resonant frequency of another sensor. For example, as depicted by <FIG>, a first sensor <NUM> having a resonant frequency <NUM> and a second sensor <NUM> having a resonant frequency <NUM> partially overlap in frequency response. Additionally, a second sensor <NUM> and a third sensor <NUM> having a resonant frequency <NUM> partially overlap in frequency response.

In some embodiments, the frequency overlap between sensors is about <NUM> to about <NUM>. In some embodiments, the frequency overlap between sensors is about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>. In some embodiments, the frequency overlap between sensors is about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. In some embodiments, the frequency overlap between sensors is at least about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. In some embodiments, the frequency overlap between sensors is at most about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>.

<FIG> depicts a technique for cross-correlation in an ultrasound measurement device. As depicted, the cross-correlation of signals from any pair of sensors <NUM>, <NUM>, <NUM> whose frequency responses overlap allows for a redundant measurement of a voxel. Specifically, the transducers of the sensors may be actuated in a time-interleaved fashion. For each actuation, for example an actuation of sensor <NUM> to transmit a signal to an object <NUM>, the received echo may be measured by all three transducers <NUM>, <NUM>, <NUM> as depicted in <FIG> to obtain received signals <NUM>, <NUM>, <NUM> on all three transducers as depicted in <FIG>. By looking at the correlation of the received signals on all three sensors, the signals may be normalized. <FIG> illustrates the event where the echo from actuation of a second sensor <NUM> is measured by all three sensors. In some embodiments, the frequency response of a first sensor <NUM> and a second sensor <NUM> is convolved in the frequency domain with the received echo waveform. When deconvolved, at step <NUM> the measurement from the third sensor may be correlated with the measurement from the second sensor while using the measurement of first sensor to normalize the measurement of the second sensor. As depicted by <FIG>, a much sharper peak in a signal monitored by the second sensor is obtained, and those sharper peaks may be achieved by the aforementioned cross-frequency normalization.

In some embodiments, a circuit is utilized to process ultrasound signals. <FIG> depicts an ultrasound signal processing circuit (USPC) <NUM> configured to process and/or condition ultrasound signals transmitted between one or more ultrasound transducers <NUM> and a software-defined radio system <NUM>, according to some embodiments. The system used to generate and receive ultrasound signals, as depicted in <FIG>, may be correspond to a transmit (Tx) generator and/or a receive (Rx) beamformer as described herein. One or more signals transmitted by the software-defined radio system may be referred to as the outputs of the software-defined radio system. One or more signals transmitted by the software-defined radio system may be referred to as the inputs of the software-defined radio system.

In some embodiments, the software-defined radio system <NUM> transmits one or more signals <NUM>, <NUM> to the ultrasound signal processing circuit (USPC) <NUM>. In some embodiments, a first transmission signal <NUM> comprises a transmission pulse or reference clock. In some embodiments, a second transmission <NUM> signal comprises a gain ramp. In some embodiments, the transmission pulse <NUM> is a low-voltage transmission pulse. In some embodiments, the transmission pulse <NUM> is a +/- <NUM> volt signal.

In some embodiments, a first transmission signal <NUM> is received by a high-voltage amplifier <NUM>. In some embodiments, a transmission pulse or reference clock is input into the high-voltage amplifier <NUM>. In some embodiments, an amplified signal from the high-voltage amplifier <NUM> passes through a diode <NUM>. In some embodiments, the first transmission signal <NUM> is then transmitted to a first multiplexer <NUM>. In some embodiments, the first transmission signal <NUM> is a transmission pulse or reference clock transmitted to the first multiplexer <NUM>. In some embodiments, diode <NUM> is an anti-parallel diode configured to block received signals from the ultrasound transducer <NUM> or multiplexer <NUM> to the high-voltage amplifier <NUM>. A high-voltage amplifier may be a discrete amplifier. In some embodiments, the high voltage amplifier output signal is a +/- <NUM> volt amplifier. In some embodiments, the high voltage amplifier <NUM> creates a +/- <NUM> volt device signal from a low voltage output of the software-defined radio <NUM>.

In some embodiments, an output from the first multiplexer <NUM> is transmitted to the one or more ultrasound transducers <NUM>. In some embodiments, the output from the first multiplexer <NUM> is received by a first pixel group of the ultrasound transducers <NUM>. The ultrasound transducers <NUM> may then transmit a first pixel group ultrasonic signal to an object. The object may then reflect the transmitted ultrasonic signal and the ultrasound transducers <NUM> may receive the reflected signal. In some embodiments the reflected signal is received as part of a first pixel group. In some embodiments, the reflected signal is received as part of a second pixel group. In some embodiments, the reflected signal forms both a first pixel group and a second pixel group. The ultrasound transducers <NUM> may then transmit the received reflected signal as an electrical signal. The received reflected signal from a first pixel group may be considered a first received signal. In some embodiments, the first received signal may be received from the transducers <NUM> by the first multiplexer <NUM>. The received reflected signal from a second pixel group may be considered a second received signal. In some embodiments, the second received signal may be received from the transducers <NUM> by the second multiplexer <NUM>. In some embodiments, signals are wirelessly transmitted between the multiplexers <NUM>, <NUM> and the one or more ultrasound transducers <NUM>. A wireless communication link between the multiplexers <NUM>,<NUM> and ultrasound transducers <NUM> may be a wireless mode such as a Bluetooth® or Bluetooth® low energy (LE) link, a Wi-Fi® link, a ZigBee link, or some other suitable wireless communication link. In some embodiments, a wired communication link between the multiplexers <NUM>,<NUM> and ultrasound transducers <NUM> may be achieved using a wired transmitter or other suitable wired interface. For example, data may be transferred using a USB-C connector, a USB <NUM>. x or <NUM>. x connector, a micro-USB connector, a THUNDERBOLT connector, an Ethernet cable, etc..

One or more signals transmitted to the ultrasound transducers may be referred to as the inputs of the ultrasound transducers. One or more signals transmitted by the ultrasound transducers may be referred to as the outputs of ultrasound transducers. The outputs of the ultrasound transducers may correspond to the reflected ultrasound signals measured or detected by the ultrasound transducers.

In some embodiments, the first multiplexer <NUM> transmits the first received signal from the first pixel group to a first low-noise amplifier <NUM>. In some embodiments, the first received signal passes through a high-voltage blocker <NUM>. The high voltage blocker <NUM> may prevent signals from the high-voltage amplifier <NUM> from passing to the first low-noise amplifier. The blocker <NUM> may be a high voltage protection transmit/ receive switch (T/R switch), such as a MD0100. In some embodiments, the first low-noise amplifier <NUM> is a low noise, single-ended, linear in dB, general purpose variable gain amplifier, such as an AD8336. In some embodiments, the first received signal is then received by a first variable gain amp <NUM>. In some embodiments, variable gain amp <NUM> is a low noise, single-ended, linear in dB, general purpose variable gain amplifier, such as an AD8336. In some embodiments, the first low-noise amplifier <NUM> and the first variable gain amplifier <NUM> utilize the same chip type.

In some embodiments, the second multiplexer <NUM> transmits the first received signal from the second pixel group to a second low-noise amplifier <NUM>. In some embodiments, diode <NUM> is prevents a transmitted signal from being output to the second multiplexer <NUM>. In some embodiments, diode <NUM> is an anti-parallel diode. In some embodiments, the second low-noise amplifier <NUM> is a low noise, single-ended, linear in dB, general purpose variable gain amplifier, such as an AD8336. In some embodiments, the second received signal is then received by a second variable gain amp <NUM>. In some embodiments, variable gain amp <NUM> is a low noise, single-ended, linear in dB, general purpose variable gain amplifier, such as an AD8336. In some embodiments, the first low-noise amplifier <NUM>, the first variable gain amplifier <NUM>, the second low-noise amplifier <NUM>, and the second variable gain amplifier <NUM> utilize the same chip type. In some embodiments, amplifiers <NUM>, <NUM>, <NUM>, <NUM> receive faint return pulses an amplify them according to a gain ramp signal. In some embodiments, <NUM>, <NUM>, <NUM>, <NUM> receive faint return pulses an amplify them according to a second transmission signal <NUM> which is 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 ration of amplification is determined by the time since the initial pulse of the gain ramp signal was emitted. In some embodiments, the return pulses are the received signals.

In some embodiments, a second transmission <NUM> signal is transmitted to a first variable gain amplifier <NUM>. In some embodiments, the signal output by the first variable gain amplifier <NUM> is received by the first receive channel <NUM> of the software-defined radio system <NUM> and the second variable gain amplifier <NUM>. In some embodiments, a signal output by the second variable gain amplifier <NUM> is received by the second receive channel <NUM> of the software-defined radio system <NUM>.

In some embodiments, the first multiplexer <NUM> is a <NUM>-channel multiplexer. In some embodiments, the second multiplexer <NUM> is a <NUM>-channel multiplexer. In some embodiments, the first pixel group comprises a <NUM> pixels. In some embodiments, the second pixel group comprises a <NUM> 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 resolution of the system is <NUM> bits. In some embodiments, the resolution of the system is <NUM> bits. In some embodiments, the system is module and additional hardware may be utilized to increase the channel number. In some embodiments, the system may comprise <NUM> channels to <NUM>,<NUM> channels. In some embodiments, the system may comprise <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, <NUM> channels to <NUM>,<NUM> channels, or <NUM>,<NUM> channels to <NUM>,<NUM> channels. In some embodiments, the system may comprise <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM>,<NUM> channels, or <NUM>,<NUM> channels. In some embodiments, the system may comprise at least <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, or <NUM>,<NUM> channels. In some embodiments, the system may comprise at most <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM> channels, <NUM>,<NUM> channels, or <NUM>,<NUM> channels.

In some embodiments, the software-defined radio system <NUM> is a Universal Software Radio Peripheral (USRP), such as a National Instruments USRP N210. In some embodiments, the software-defined radio system <NUM> connects to a host computer <NUM>. In some embodiments, the radio system <NUM> connects to the computer <NUM> through 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 may allow for sampling rates up <NUM>/s (Mega Samples per second). In some embodiments, a host-based software is loaded onto the computer <NUM> and utilized to control the radio system hardware and transmit/receive data. In some embodiments, the general functionality of a host computer is implemented into the radio system <NUM> with an embedded processor that allows the radio system <NUM> to operate in a stand-alone fashion.

In some embodiments, connection to a computer <NUM> comprises a universal serial bus (USB) connection, a fiber optical connection, a peripheral component interconnect expresses (PCle) connection, or other suitable connection. In some embodiments, connection to a computer <NUM> may allow the system to utilize the rapid access memory (RAM) of the computer. In some embodiments, an embedded processor may comprise a RAM buffer. In some embodiments, the RAM buffer may comprise <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> gigabytes (GB).

In some embodiments, the software-defined radio system <NUM> comprises a motherboard. The motherboard may provide the following subsystems: clock generation and synchronization, a field-programmed gate array (FPGA), one or more analog-to-digital converters (ADCs), one or more digital-to-analog converters (DACs), a host processor interface, and a power 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 may permit the software-defined radio system <NUM> to serve applications that operate between DC and <NUM>. In some embodiments, the system operates between DC and <NUM>. In some embodiments, the system operates only down to <NUM>, which may be considered the limit of a normal ultrasonic signal. In some embodiments, the system operates at about <NUM> to <NUM> frequencies for production of resonant mode soundwaves.

In some embodiments, signals received by a first receive channel <NUM> or a second receive channel <NUM> of the software-defined radio system <NUM> may be adjusted to provide a received signal gain of about -<NUM> decibels (dB) to +<NUM> dB.

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

In some embodiments, the FPGA of the software-defined radio system <NUM> performs several digital signal processing (DSP) operations. In some embodiments, the DSP operation performed by the FPGA provide translation from real signals in the analog domain to lower-rate, complex, baseband signals in the digital domain. In some embodiments, these complex samples are transferred to/from applications running on a host processor, which perform DSP operations.

In some embodiments, the hardware driver of the software-defined radio system <NUM> supports an operating system, such as Linux, MacOS, and Windows platforms. In some embodiments several frameworks, including GNU Radio, LabVIEW, MATLAB and Simulink may use the hardware driver. The functionality provided by hardware driver may also be accessed directly with a 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.

The present disclosure provides computer systems that are programmed to implement methods of the disclosure, according to some embodiments. <FIG> shows a computer system <NUM> that is programmed or otherwise configured to, for example, implement the methods disclosed herein. The computer system <NUM> can be an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

The computer system <NUM> includes a central processing unit (CPU, also "processor" and "computer processor" herein) <NUM>, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system <NUM> also includes memory or memory location <NUM> (e.g., random-access memory, read-only memory, flash memory), electronic storage unit <NUM> (e.g., hard disk), communication interface <NUM> (e.g., network adapter) for communicating with one or more other systems, and peripheral devices <NUM>, such as cache, other memory, data storage and/or electronic display adapters. The memory <NUM>, storage unit <NUM>, interface <NUM> and peripheral devices <NUM> are in communication with the CPU <NUM> through a communication bus (solid lines), such as a motherboard. The storage unit <NUM> can be a data storage unit (or data repository) for storing data. The computer system <NUM> can be operatively coupled to a computer network ("network") <NUM> with the aid of the communication interface <NUM>. The network <NUM> can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. The network <NUM> in some cases is a telecommunication and/or data network. The network <NUM> can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network <NUM>, in some cases with the aid of the computer system <NUM>, can implement a peer-to-peer network, which may enable devices coupled to the computer system <NUM> to behave as a client or a server.

The CPU <NUM> can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory <NUM>. The instructions can be directed to the CPU <NUM>, which can subsequently program or otherwise configure the CPU <NUM> to implement methods of the present disclosure. Examples of operations performed by the CPU <NUM> can include fetch, decode, execute, and writeback.

The CPU <NUM> can be part of a circuit, such as an integrated circuit. One or more other components of the system <NUM> can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

The storage unit <NUM> can store files, such as drivers, libraries, and saved programs. The storage unit <NUM> can store user data, e.g., user preferences and user programs. The computer system <NUM> in some cases can include one or more additional data storage units that are external to the computer system <NUM>, such as located on a remote server that is in communication with the computer system <NUM> through an intranet or the Internet.

The computer system <NUM> can communicate with one or more remote computer systems through the network <NUM>. For instance, the computer system <NUM> can communicate with a remote computer system of a user (e.g., a smartphone, a laptop computer). Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC's (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user can access the computer system <NUM> via the network <NUM>.

Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system <NUM>, such as, for example, on the memory <NUM> or electronic storage unit <NUM>. The machine executable or machine-readable code can be provided in the form of software. During use, the code can be executed by the processor <NUM>. In some cases, the code can be retrieved from the storage unit <NUM> and stored on the memory <NUM> for ready access by the processor <NUM>. In some situations, the electronic storage unit <NUM> can be precluded, and machine-executable instructions are stored on memory <NUM>.

The code can be pre-compiled and configured for use with a machine having a processer adapted to execute the code or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a pre-compiled or as-compiled fashion.

Aspects of the systems and methods provided herein, such as the computer system <NUM>, can be embodied in programming. Various aspects of the technology may be thought of as "products" or "articles of manufacture" typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machine-executable code can be stored on an electronic storage unit, such as memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. "Storage" type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical, and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links, or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible "storage" media, terms such as computer or machine "readable medium" refer to any medium that participates in providing instructions to a processor for execution.

Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may 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.

The computer system <NUM> can include or be in communication with an electronic display <NUM> that comprises a user interface (UI) <NUM>. Examples of UI's include, without limitation, a graphical user interface (GUI), a mobile device application, and web-based user interface.

<FIG> illustrates a chip set <NUM>, according to some embodiments. Chip set <NUM> can include, for instance, processor and memory components incorporated in one or more physical packages. By way of example, a physical package includes an arrangement of one or more materials, components, and/or wires on a structural assembly (e.g., a baseboard) to provide one or more characteristics such as physical strength, conservation of size, and/or limitation of electrical interaction.

In one embodiment, chip set <NUM> includes a communication mechanism such as a bus <NUM> for passing information among the components of the chip set <NUM>. A processor <NUM> has connectivity to bus <NUM> to execute instructions and process information stored in a memory <NUM>. Processor <NUM> includes one or more processing cores with each core configured to perform independently. Alternatively, or in addition, processor <NUM> includes one or more microprocessors configured in tandem via bus <NUM> to enable independent execution of instructions, pipelining, and multithreading. Processor <NUM> may also be accompanied with one or more specialized components to perform certain processing functions and tasks such as one or more digital signal processors (DSP) <NUM>, and/or one or more application-specific integrated circuits (ASIC) <NUM>. DSP <NUM> can typically be configured to process real-world signals (e.g., sound) in real time independently of processor <NUM>. Similarly, ASIC <NUM> can be configured to performed specialized functions not easily performed by a general purposed processor.

Processor <NUM> and accompanying components have connectivity to the memory <NUM> via bus <NUM>. Memory <NUM> includes both dynamic memory (e.g., RAM) and static memory (e.g., ROM) for storing executable instructions that, when executed by processor <NUM>, DSP <NUM>, and/or ASIC <NUM>, perform the process of example embodiments as described herein. Memory <NUM> also stores the data associated with or generated by the execution of the process.

In this document, the terms "machine readable medium," "computer readable medium," and similar terms are used to generally refer to non-transitory mediums, volatile or non-volatile, that store data and/or instructions that cause a machine to operate in a specific fashion. Common forms of machine readable media include, for example, a hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, an optical disc or any other optical data storage medium, any physical medium with patterns of holes, a RAM, a PROM, EPROM, a FLASH-EPROM, NVRAM, any other memory chip or cartridge, and networked versions of the same.

These and other various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processing device for execution. Such instructions embodied on the medium, are generally referred to as "instructions" or "code. " Instructions may be grouped in the form of computer programs or other groupings. When executed, such instructions may enable a processing device to perform features or functions of the present application as discussed herein.

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.

The various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives can be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.

Each of the processes, methods, and algorithms described in the preceding sections may be embodied in, and fully or partially automated by, code components executed by one or more computer systems or computer processors comprising computer hardware. The processes and algorithms may be implemented partially or wholly in application-specific circuitry. 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. Additionally, unless the context dictates otherwise, the methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate, or may be performed in parallel, or in some other manner. Blocks or states may be added to or removed from the disclosed example embodiments. The performance of certain of the operations or processes may be distributed among computer systems or computers processors, not only residing within a single machine, but deployed across a number of machines.

The devices and methods described herein may be utilized for applications in fields outside of the medical fields described above. For instance, the devices and methods may be used to provide information about the internal conditions of mechanical systems, such as the engines or transmissions of vehicles. The stethoscope functionality may be used to detect abnormalities in the mechanical processes of an engine or transmission. The ultrasonic functionality may be used to image the engine or transmission to determine if it has sustained internal damage. The non-stethoscopic, non-ultrasonic sensors may provide additional information about the state of the engine or transmission, such as its temperature.

The devices and methods may be used for non-destructive testing of infrastructure. For instance, the devices and methods may 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 devices and methods may be used to examine the internal structures of pipelines to determine whether they are damaged and may represent a threat to life, property, or the environment.

The devices and methods described herein may be utilized to examine the internal structures of other building materials, such as stone, brick, wood, sheetrock, thermal insulating, plastic piping, polyvinyl chloride (PVC) piping, fiberglass, or paint.

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

Throughout this application, various embodiments may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosure.

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 "a sample" includes a plurality of samples, including mixtures thereof.

The terms "determining," "measuring," "evaluating," "assessing," "assaying," and "analyzing" are often used interchangeably herein to refer to forms of measurement. The terms include determining if an element is present or not (for example, detection). These terms can include quantitative, qualitative or quantitative and qualitative determinations. Assessing can be relative or absolute. "Detecting the presence of can include determining the amount of something present in addition to determining whether it is present or absent depending on the context.

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

The term "in vivo" is used to describe an event that takes place in a subject's body.

The term "ex vivo" is used to describe an event that takes place outside of a subject's body. An ex vivo assay is not performed on a subject. Rather, it is performed upon a sample separate from a subject. An example of an ex vivo assay performed on a sample is an "in vitro" assay.

The term "in vitro" is used to describe an event that takes places contained in a container for holding laboratory reagent such that it is separated from the biological source from which the material is obtained. In vitro assays can encompass cell-based assays in which living or dead cells are employed. In vitro assays can also encompass a cell-free assay in which no intact cells are employed.

As used herein, the term "about" a number refers to that number plus or minus <NUM>% of that number. The term "about" a range refers to that range minus <NUM>% of its lowest value and plus <NUM>% of its greatest value.

As used herein, the term "or" may be construed in either an inclusive or exclusive sense. Moreover, the description of resources, operations, or structures in the singular shall not be read to exclude the plural. Conditional language, such as, among others, "can," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps.

Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. Adjectives such as "conventional," "traditional," "normal," "standard," "known," and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. The presence of broadening words and phrases such as "one or more," "at least," "but not limited to" or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent.

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

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

In an example of measuring blood pressure using previous methods which utilize a sphygmomanometer cuff, a patient's arm is laid out on a comfortable surface. A trained nurse or doctor then places a properly sized cuff around the upper arm of the patient. A stethoscope is placed on the brachial artery of the patient just below the cuff.

The trained person then inflates the cuff to <NUM> mmHG and begins releasing air from the cuff at a suggest rate of <NUM>/sec. The trained person must simultaneously observe they sphygmomanometer of the cuff while listening with the stethoscope.

A first "knocking sound" indicates the point at which the systolic pressure of the patient is to be measured using the sphygmomanometer. When the "knocking sound" disappears, the diastolic pressure of the patient is to be measured using the sphygmomanometer. The measured systolic and diastolic pressures should be recorded.

It is further recommended that measurements are taken in the other arm. Any difference between measurements of the arm should be recorded. Further, the subject's position and the cuff sized used should be recorded.

If the subject's blood pressure appears to be elevated, it is recommended that the patient's blood pressure be measured at least two additional times. With a rest period in given in between measurements.

An adhesive substrate comprising one or more ultrasound transducers and an electroacoustic transducer is adhered proximal to the patient's carotid artery. An electroacoustic transducer provided on the adhesive substrate is activated.

The electroacoustic transducer is varied through a range of audio frequencies. The ultrasound transducer detects when resonance in the artery is at a maximum level. The resonance frequency is held for a moment and recorded. The ultrasound transducer determines the arterial wall thickness and diameter of the artery. The blood pressure of the patient is then calculated and recorded.

Claim 1:
A blood pressure measurement device (<NUM>), comprising:
a first transducer (<NUM>, <NUM>) configured to emit multiple soundwaves (<NUM>) having multiple frequencies, the soundwaves configured to cause a blood vessel of a subject to vibrate;
a second transducer (<NUM>) configured to capture multiple ultrasound images of the blood vessel; and
a processing device (<NUM>) configured to:
determine, based on the multiple captured ultrasound images, a resonant frequency of the blood vessel; and
calculate, based on a wall (<NUM>, <NUM>) thickness of the blood vessel, a radius or diameter of the blood vessel, and the determined resonant frequency, a blood pressure (<NUM>) of the blood vessel or the subject,
wherein determining the resonant frequency of the blood vessel comprises:
determining, from the multiple ultrasound images, based on a vibrational response of the blood vessel to the soundwaves, a frequency of the multiple frequencies that maximizes a vibration of the blood vessel: and
selecting the frequency as the resonant frequency.