Abstract: One aspect of the subject matter described in this disclosure can be implemented in a device capable of use in estimating blood pressure. The device includes one or more arterial sensors configured to obtain arterial measurements at two or more elevations. The device additionally includes one or more processors configured to determine one or more calibration parameters for a first blood pressure model based on the arterial measurements and a hydrostatic pressure difference between at least two of the elevations. The processors also are configured to determine a first blood pressure based on the first blood pressure model, the calibration parameters and the arterial measurements. The processors also are configured to determine a second blood pressure based in part on a second blood pressure model, one or more calibration parameters and the arterial measurements. The processors are further configured to provide a final blood pressure based on the first and second blood pressures.

Abstract: A device may be configured for performing signal processing in impedance sensing applications, and more specifically, for recovering data from an amplitude-modulated signal. In one aspect, a device includes a sensing circuit operable to sense an amplitude-modulated signal having a carrier frequency. The device also includes a mixer operable to mix the amplitude-modulated signal with a mixing signal having a mixing frequency to provide a frequency-downshifted signal having an intermediate frequency less than the carrier frequency. The device also includes a filter operable to filter the frequency-downshifted signal to provide a filtered signal. The device further includes a sampler operable to undersample the filtered signal at an undersampling frequency to provide a digital signal, the digital signal being representative of a modulating signal.

Abstract: Various embodiments enable calibrating a non-invasive blood pressure measurement device by determining multiple parameters defining a stress-strain relationship of an artery of a patient. The device may obtain output signals from a blood pressure sensor at two or more measurement elevations. The obtained measurement signals may be filtered into AC and quasi-DC components, and results fit to exponential functions to calculate an arterial time constant and a veinous time constant related to vein draining/filling rates. The arterial and veinous time constants may be used to calculate an infinity ratio. The infinity ratio and the obtained sensor output may be used to calculate values for multiple parameters defining a stress-strain relationship of a measured artery. Once defined, this stress-strain relationship may be stored and applied to future sensor output signals (e.g., blood pressure measuring sessions) to infer patient blood pressure.

Abstract: A system for calculating blood pressure may include a sensor system and a control system. The control system may be capable of controlling one or more sensors of the sensor system to take at least two measurements, the at least two measurements including at least one measurement taken at each of two or more different measurement elevations of a subject's limb. In some examples, the control system may be capable of determining a blood flow difference based on the at least two measurements, of determining a hydrostatic pressure difference based on the two or more different elevations of the at least two measurements and of estimating a blood pressure based on one or more values of blood flow, the hydrostatic pressure difference and the blood flow difference.

Abstract: An ultrasound cardiovascular measuring device may include an ultrasonic sensor system having an ultrasound transmitter layer configured to generate ultrasonic plane waves and a focusing layer that includes one or more lenses. One or more of the lenses may be configured to generate output signals corresponding to detected ultrasonic reflections. The measuring device may include a control system capable of processing the output signals to calculate values corresponding to one or more cardiovascular properties.

Abstract: Methods, devices, and systems for determining an estimated pulse wave velocity of an artery of a subject. Embodiment methods may include applying a series of counter pressures, measuring a first parameter related to pulse wave velocity, estimating a second parameter in a model, and determining the estimated pulse wave velocity. The counter pressures may be applied at a set location on the subject over the artery with a pressure device. Each of the counter pressures may be different from one another, applied at the set location, and between zero and a diastolic pressure of the subject. The first parameter may be measured when each of the series of counter pressures is applied. The model may establish a relationship of the first parameter measured to each of the series of counter pressures. The estimated pulse wave velocity may be determined based on the second parameter estimated in the model.

Abstract: Various embodiments include methods and devices for measuring blood pressure. Various embodiments may include receiving, from one or more arterial measurement sensors, a pulse waveform representing arterial pressure as a function of time for each pulse of a series of blood pressure pulses. The series of blood pressure pulses may be correlated to arterial distension at a measurement location of the arterial measurement sensors on a subject's body. One or more elevations of the measurement location may be received from one or more elevation sensors. At least one pulse in the series of pulses may be identified that represents a transitional pulse based on one or more characteristics of the at least one pulse. A diastolic blood pressure may be determined based on the at least one identified transitional pulse and elevation measurements that correspond to the one identified pulse.

Abstract: Various embodiments identify valid arterial pulses of a subject. The method may include accessing one or more measured pulses from one or more arterial measurement sensors. The processor may identify one or more valid pulses from the one or more measured pulses based on a comparison of one or more pulse characteristics of the one or more measured pulses to one or more reference pulses. The one or more pulse characteristics are determined based on the one or more measured pulses and a wavelet transform. The wavelet transform is determined based on the one or more reference pulses.

Abstract: One aspect of the subject matter described in this disclosure can be implemented in a device capable of estimating blood pressure. The device includes two or more sensors capable of performing measurements along an artery. The device also includes at least one processing unit coupled with the two or more sensors. The processing unit is capable of accessing one or more parameters including a stress-strain parameter based on a hydrostatic pressure calibration. The processing unit also is capable of determining a pulse transit time (PTT) based on the measurements, and determining a pulse wave velocity (PWV) based on the PTT. The processing unit is further capable of determining a blood pressure based on the PWV and the stress-strain parameter.

Abstract: Methods, devices, systems, and non-transitory processor-readable storage media are disclosed for determining one or more biometric properties of a subject using multiple sensors positioned along a flexible backing. At least one processor of the multi-sensor device may be configured to receive output signals from the multiple sensors, identify at least one output signal from the received output signals that exhibit measurements of a targeted biological structure, determine the one or more biometric properties of the subject based on the identified at least one output signal received from at least one of the multiple sensors, and provide the determined one or more biometric properties.

Abstract: A biometric measuring device for obtaining biometric measurements on a limb or digit, such as a finger. The biometric measuring device may include a rollable sleeve that is rollable along a longitudinal axis of the limb or digit and multiple biometric sensors attached to the rollable sleeve such that the biometric sensors are positioned on the rollable sleeve to enable the sleeve to be rolled.

Abstract: An optical sensor and a method of using the optical sensor in an optical measuring device that measures cardiovascular properties and compensates for movement artifacts by directing a sheet of light towards an artery. The optical sensor may include one or more light sources, one or more transmit light guides coupled to the one or more light sources and configured to direct light from the one or more light sources as a sheet of light towards an artery, such that the cross-sectional profile of the sheet of light may have a length transverse to a longitudinal direction of the artery that is longer than the diameter of the artery. The optical sensor may include one or more light detectors configured to receive backscattered light and generate an output based on the received backscattered light that is a reflection of the sheet of light from the artery and surrounding tissues.

Abstract: Systems, methods, and devices of various embodiments enable measurement of blood pressure from an artery. The various embodiments may measure, using a non-interfering arterial measurement sensor, a first change in distension of the artery at a measurement location without interference to an arterial pressure at the measurement location during a series of pulses. A first pulse rate and estimated pulse pressures may be determined from the first change in distension. A coefficient may be determined fitting an exponentially decaying function representing an exponential decay of a portion of a diastolic phase to select ones of the estimated pulse pressures corresponding to the diastolic phase. An absolute blood pressure may be determined by applying the coefficient to a select mathematical model expressing a first relationship between the first change in distension of the artery and the pulse pressure in the artery at the measurement location.

Abstract: Systems, methods, and devices of the various embodiments enable continuous non-invasive monitoring of blood pressure with a minimum of interference. The various embodiments may provide a method for adaptation for the calibration for continuous measurements of blood pressure, wherein the measured quantity may be related to an arterial lumen or arterial cross sectional area comprising calibrating the conversion for incremental variations of arterial properties and absolute value adaptation by exploitation of the exponential decay during the diastole. In various embodiments, continuous calibration of a non-interfering blood pressure measurement device may be initiated based on a change in mean arterial pressure being greater than a threshold value, such as a pressure value associated with an actual measured distension of a patient's artery.

Abstract: One aspect of the subject matter described in this disclosure can be implemented in a device capable of use in estimating blood pressure. The device includes one or more arterial sensors configured to obtain arterial measurements at two or more elevations. The device additionally includes one or more processors configured to determine one or more calibration parameters for a first blood pressure model based on the arterial measurements and a hydrostatic pressure difference between at least two of the elevations. The processors also are configured to determine a first blood pressure based on the first blood pressure model, the calibration parameters and the arterial measurements. The processors also are configured to determine a second blood pressure based in part on a second blood pressure model, one or more calibration parameters and the arterial measurements. The processors are further configured to provide a final blood pressure based on the first and second blood pressures.

Abstract: Various embodiments enable calibrating a non-invasive blood pressure measurement device by determining multiple parameters defining a stress-strain relationship of an artery of a patient. The device may obtain output signals from a blood pressure sensor at two or more measurement elevations. The obtained measurement signals may be filtered into AC and quasi-DC components, and results fit to exponential functions to calculate an arterial time constant and a veinous time constant related to vein draining/filling rates. The arterial and veinous time constants may be used to calculate an infinity ratio. The infinity ratio and the obtained sensor output may be used to calculate values for multiple parameters defining a stress-strain relationship of a measured artery. Once defined, this stress-strain relationship may be stored and applied to future sensor output signals (e.g., blood pressure measuring sessions) to infer patient blood pressure.

Abstract: Methods, devices, systems, and non-transitory processor-readable storage media are disclosed for determining one or more biometric properties of a subject using multiple sensors positioned along a flexible backing. At least one processor of the multi-sensor device may be configured to receive output signals from the multiple sensors, identify at least one output signal from the received output signals that exhibit measurements of a targeted biological structure, determine the one or more biometric properties of the subject based on the identified at least one output signal received from at least one of the multiple sensors, and provide the determined one or more biometric properties.

Abstract: Various embodiments include methods and devices for measuring blood pressure. Various embodiments may include receiving, from one or more arterial measurement sensors, a pulse waveform representing arterial pressure as a function of time for each pulse of a series of blood pressure pulses. The series of blood pressure pulses may be correlated to arterial distension at a measurement location of the arterial measurement sensors on a subject's body. One or more elevations of the measurement location may be received from one or more elevation sensors. At least one pulse in the series of pulses may be identified that represents a transitional pulse based on one or more characteristics of the at least one pulse. A diastolic blood pressure may be determined based on the at least one identified transitional pulse and elevation measurements that correspond to the one identified pulse.

Abstract: A biometric measuring device for obtaining biometric measurements on a limb or digit, such as a finger. The biometric measuring device may include a rollable sleeve that is rollable along a longitudinal axis of the limb or digit and multiple biometric sensors attached to the rollable sleeve such that the biometric sensors are positioned on the rollable sleeve to enable the sleeve to be rolled.

Abstract: An optical sensor and a method of using the optical sensor in an optical measuring device that measures cardiovascular properties and compensates for movement artifacts by directing a sheet of light towards an artery. The optical sensor may include one or more light sources, one or more transmit light guides coupled to the one or more light sources and configured to direct light from the one or more light sources as a sheet of light towards an artery, such that the cross-sectional profile of the sheet of light may have a length transverse to a longitudinal direction of the artery that is longer than the diameter of the artery. The optical sensor may include one or more light detectors configured to receive backscattered light and generate an output based on the received backscattered light that is a reflection of the sheet of light from the artery and surrounding tissues.