Wearable health monitoring device

Abstract

A health monitoring device for detecting blood pressure includes a blood pressure sensor comprising a first fiber Bragg grating (FBG) of refractive index positioned close to an artery or vein in contact with the skin. A baseline sensor comprising a second fiber Bragg grating (FBG), also of refractive index, is positioned away from the artery or vein in contact with the skin to provide a baseline refractive index. The device pulses light waves through the FBG to provide a processor with a reading of the refractive index from the FBG. Based on the effective shift of the Bragg wavelength due to axial strain on the FBG, a blood pressure estimator estimates systolic and diastolic blood pressure based on a calibration curve comparing pressure and strain.

Description

[0001] Cross-reference to related applications

[0002] This application is a continuation of U.S. Application No. 16 / 723,078, filed December 20, 2019. The entire teachings of the above application are incorporated herein by reference. Background Technology

[0003] A person's health status is typically measured using certain vital signs, including blood pressure, respiratory rate, heart rate, blood oxygen saturation, and body temperature. Blood pressure is the pressure exerted by circulating blood against the walls of blood vessels as the heart pumps blood through the circulatory system. Blood pressure is usually expressed as the systolic pressure (the maximum pressure during one heartbeat) exceeding the diastolic pressure (the minimum pressure between two heartbeats), and is measured in millimeters of mercury (mmHg) above ambient atmospheric pressure.

[0004] The average normal resting blood pressure for an adult is approximately 120 mmHg systolic and 80 mmHg diastolic (120 / 80). Sustained high blood pressure is called hypertension, while low blood pressure is called hypotension. Long-term hypertension is a risk factor for many diseases, including heart disease, stroke, and kidney failure.

[0005] Blood pressure is typically measured using a sphygmomanometer, which usually consists of an inflatable cuff, a measuring unit (e.g., a mercury manometer or anhydrous manometer), and an inflation mechanism, which can be a manually operated glass bulb and valve or an electrically operated pump. The inflatable cuff is placed around the upper arm (or, in some cases, around the wrist) and inflated to constrict the blood vessels in the arm and inside. The examiner listens to the brachial artery at the elbow with a stethoscope and slowly releases the pressure from the cuff. As the pressure in the cuff decreases, a whooshing or pounding sound is heard as blood first begins to flow in the artery. The pressure at which this sound begins is noted and recorded as the systolic pressure. The cuff pressure is further released until the sound can no longer be heard. This is recorded as the diastolic pressure. Digital instruments use a cuff that, depending on the instrument, can be placed around the upper arm, wrist, or fingers, in all cases raised to the same height as the heart. The automatic instrument inflates the cuff and gradually reduces the pressure in the same manner as the manual instrument, and uses an oscillometric method to measure blood pressure by measuring the oscillation of the cuff pressure caused by blood pressure.

[0006] In recent years, methods and systems for measuring blood pressure without applying any pressure (or very little pressure) to the patient's body have been developed. One method estimates blood pressure based on the time difference (propagation velocity) between pulse waves measured by fiber optic Bragg grating sensors (hereinafter referred to as "FBG sensors") attached to multiple locations on the subject. Another method estimates blood pressure using a calibration model that represents the correlation between measured waveform data of the acceleration pulse wave measured by the FBG and measured blood pressure values ​​measured at individual time points of the measured waveform data, and the calibration model is used to estimate the subject's blood pressure value at the time of acceleration pulse wave measurement based on the waveform data of the acceleration pulse wave measured from the subject. Summary of the Invention

[0007] Embodiments of the present invention provide a wearable health monitoring device for detecting blood pressure. In one embodiment according to the principles of the invention, a first fiber Bragg grating (FBG) is configured to be placed close to an artery or vein in contact with the skin. A second fiber Bragg grating (FBG) is configured to be placed away from the artery or vein in contact with the skin to provide a baseline. The device has a light emitter that transmits pulsed light waves through the FBG, and a light sensor that receives the pulsed light waves to provide a processor with the effective Bragg wavelength (λ) of the FBG. eff The data acquisition module receives the peak wavelength of the light sensor reflected by the FBG. A comparator determines the effective offset of the Bragg wavelength due to axial strain on the FBG, thus providing a complete measurement of the blood pressure pulse. The blood pressure estimator is configured to calculate the entire blood pressure pulse and, along the effective offset of the Bragg wavelength of the first and second FBGs, estimate the systolic and diastolic blood pressure based on a calibration curve comparing pressure and strain. The device uses a display to provide the estimated systolic and diastolic blood pressure.

[0008] Another embodiment of the invention includes a heart rate monitor configured to detect periodic changes in surface deformation associated with heartbeat.

[0009] In addition to using FBG to monitor blood pressure, some embodiments of wearable health monitors may also include various physiological attributes or health monitors, such as blood oxygen saturation sensors, blood glucose sensors, or body temperature sensors. For example, the device may include optical sensors or skin temperature sensors.

[0010] Embodiments of the device may further include a transmitter that provides blood pressure pulse and estimated systolic and diastolic blood pressure information for display on a remote device. This information may also be transmitted to the remote device for monitoring purposes and data analysis to derive health indicators.

[0011] Another embodiment of the invention may include a plurality of fiber Bragg gratings (FBGs) configured to be placed adjacent to an artery or vein in contact with human skin. Each FBG is shifted relative to another by a predetermined amount. Attached Figure Description

[0012] The foregoing will become clear from the following more detailed description of exemplary embodiments, as illustrated in the accompanying drawings, in which similar reference numerals refer to the same parts in different views. The drawings are not necessarily drawn to scale and are intended to illustrate the embodiments.

[0013] Figure 1 It is a representative FBG in optical fiber core.

[0014] Figure 2 This is an exemplary wearable health monitoring device based on the principles of the present invention.

[0015] Figure 3A It is a representative collection of optical fibers with FBGs arranged in it.

[0016] Figure 3B Is to implement Figure 3A The optical fiber assembly shown is an exemplary wearable health monitoring device according to the principles of the present invention.

[0017] Figure 4 This is an exemplary wearable health monitoring device based on the principles of the present invention.

[0018] Figure 5 This is a flowchart illustrating a method for estimating blood pressure using FBG measurement according to the principles of the present invention. Detailed Implementation

[0019] The example embodiment is described below.

[0020] like Figure 1 As shown, the fiber Bragg grating (FBG) 100 is a short-length optical fiber 120 that includes multiple reflection points 130a-n that produce a periodic variation in refractive index. The FBG reflects a unique wavelength (λB) centered on a bandwidth ΔλB. The periodicity Δ of the grating is related to the Bragg wavelength λB.

[0021] lB = 2.n eff. Λ……………………(1)n eff This is the effective refractive index of a single-mode optical fiber. As the fiber is stretched and the grating parameter Λ increases, the effective refractive index n... eff Decrease δn eff Bragg wavelength λB offset

[0022] δlB=2{n eff. δΛ+Λ.δn eff}。 …………………(1a)

[0023] By embedding one or more optical fibers with one or more FBGs into wearable materials that can be wound around relevant parts of the human body's anatomy, the wearable materials can be used to sense surface deformation of that part caused by physiological processes such as heartbeat and changes between systolic and diastolic blood pressure. Figure 2 As shown, a band 200 can be provided to wrap around an appendage, such as a user's wrist A. A blood pressure sensor 230 containing an FBG can be placed within the band and configured to detect subtle changes in the user's skin, particularly near an artery, such as the radial artery B. By measuring surface deformation of the skin, the device 200 can detect and track periodic movements caused by the user's pulse (e.g., radial pulse), which is caused by pressure waves generated by changes in arterial blood pressure as a beating heart pumps oxygenated blood through the body. By counting the number of blood pressure signal pulses over a specified time period and the time intervals between pulses, the system can be used to detect pulse / heart rate and any changes in heart rate.

[0024] Additionally, the device can measure a user's blood pressure using a calibration curve that correlates the change in Bragg wavelength (and consequently strain) caused by deformation of the FBG due to pulse with the pressure required to induce that change. Another sensor acts as a baseline sensor 270, comprising an optical fiber with an embedded FBG positioned away from artery B, enabling real-time baseline measurements. Based on the calibration curve comparing pressure with strain or wavelength, and strain data from both sets of sensors, both systolic and diastolic blood pressure can be detected. The effective Bragg wavelength (λ) of the FBG is also known. eff The second FBG measures the baseline, which may vary due to temperature changes or any other variable, and also provides a method for measuring temperature. The second FBG can be used to correct for time-varying λ caused by the blood pressure pulse in the first FBG in contact with the artery. eff Offset.

[0025] Before embedded strain gauges (FBGs) could be used as strain gauges, their response function and linearity were characterized as functions of the load. To characterize the FBG's response function and linearity, an electrical strain gauge can be used to calibrate the FBG such that the applied tensile load approximates the readings of displacement of a user's skin due to blood flow. Once calibrated, the FBG's response can be reliably used as an embedded strain gauge for detecting deformation of an object's surface.

[0026] For an FBG to function as a reliable strain gauge, the change in its reflected wavelength under tensile load must linearly track the data from an electrical strain gauge. It has been shown that the Bragg wavelength shift of an embedded FBG under tensile load is linearly correlated with the induced strain measured by an electrical strain gauge within elastic constraints. It is also known that, in the low-strain schemes of current applications, the stress (in pressure units) defined as the tensile load divided by the cross-sectional area is linearly correlated with the induced strain, where the proportionality constant is the elastic modulus. This is the classic definition of Hooke's law. Based on these two linear relationships, it can be inferred that stress is linearly correlated with the Bragg wavelength, and vice versa. This proportion is used to infer blood pressure from the Bragg wavelength shift of an embedded FBG. Within reasonable constraints on the elasticity of the instrument, it can also be used to detect the degree of displacement of an object's surface to determine blood pressure readings.

[0027] Returning to reference device 200, an FBG sensor is embedded longitudinally along a band 200, which typically extends in a direction perpendicular to blood flow in the aorta or vein B. The band 200 may have an input 225 for a laser or light source through which light is transmitted via the FBG 230. The FBG 230 is connected to a light sensor 220 that receives pulsed light waves from the light source 225. The light sensor is connected to a processor 210, which is configured to analyze data regarding light transmission through the FBG 230. The processor 210 identifies shifts in the refractive index of the FBG 230 and calculates the user's blood pressure based on those readings. In addition to reading blood pressure, the FBG sensor can also be used to measure pulse rate by detecting periodic changes in surface deformation caused by the pumping of blood through the user's circulatory system.

[0028] In the embodiment shown in device 200, the blood pressure calculation and / or pulse rate can then be transmitted by transmitter 240 to an application on an external device (not shown), such as a mobile phone or handheld reader. The band can be designed to communicate wirelessly via Bluetooth, cellular data, local WiFi, or some other wireless transmission. The embodiment shown in device 200 also provides a localized display 250, thereby allowing real-time reading of the user's blood pressure and other readings without the use of an external device reader. The circuitry in the band may include other known components known to those skilled in the art, such as wireless communication circuitry, energy storage devices, and other processors (not shown).

[0029] Therefore, the band 200 can provide blood pressure and pulse rate using one or more embedded FBG sensors, which can be used as a stand-alone blood pressure monitor without physically moving parts, such as the pump used in current versions of blood pressure monitors, making the blood pressure monitor robust to environmental conditions and more cost-effective to manufacture. Both hospitals and healthcare facilities can use wearable blood pressure monitors without any wired connections and general health monitors, as well as cumbersome devices (e.g., pumps and inflatable cuffs) that may have user displays and / or remotely transmit health data for viewing or monitoring.

[0030] While such devices may be particularly helpful in situations requiring patient monitoring, personal health monitoring devices have become increasingly popular, allowing individuals with non-critical needs to track their health. Tracking vital signs such as blood pressure, blood oxygen, and blood glucose levels can enable early detection of many conditions, such as sleep apnea monitored by blood oxygen saturation; and heart conditions such as patent foramen ovale (PFO) and atrial septal aneurysm (ASA) monitored by blood pressure and blood oxygen saturation. Furthermore, comprehensive real-time measurements of blood pressure and pulse waveforms can open new avenues for assessing lung function by measuring the isthmus and for identifying conditions of septic or neurogenic shock. With the advent of big data analytics and artificial intelligence, comprehensive vital sign data from individuals and groups can be mined to detect and predict conditions that are currently impossible to detect. Health monitors based on the principles of this invention can go far beyond health and activity monitoring and become powerful tools in preventative healthcare.

[0031] The wearable band 200 should be made of a thin, elastic material or other flexible material, such as a stretchable fabric, so that the material can move slightly across the user's skin when the band is configured to fit a part of the user's body. The band may be configured to press the FBG 230 against the body part where surface deformation is to be detected. The band material should be elastic enough that the stiffness of the band material does not interfere with the flexural movement of the embedded optical fiber and FBG.

[0032] Other embodiments of the invention may use multiple FBGs embedded in a band to obtain multiple different readings that can be coordinated with each other to provide a more accurate calculation of blood pressure. Figure 3A and 3B Another embodiment according to the principles of the present invention is shown. Figure 3A A sensor strip 310 with fiber optic assemblies 320, 330, 340, and 350 is shown, wherein the embedded FBGs 325a-n, 335a-n, 345a-n, and 355a-n are slightly shifted relative to each other. Figure 3BIn the wearable band 300, a blood pressure sensor 310 is included, which includes multiple optical fibers, such as... Figure 3A As shown in the diagram, the optical fiber of sensor strip 310 crosses the area directly above the radial artery B and, as an example, can measure pulse shape. Another embedded optical fiber 370 with an embedded FBG is positioned away from the artery to perform real-time baseline measurements. Each of optical fibers 320, 330, 340, 350, and 370 uses both a light source sensor and a light sensor (not shown) to provide pulsed light wave data to processor 380. Figure 3B The belt 300 shown also includes a transmitter 385 that allows the belt 300 to send data to an application on an external device (not shown), such as a mobile phone or a handheld reader. Additionally, the belt 300 provides a localized display 390.

[0033] Similarly, although Figure 2 and Figure 3B The optical fiber and FBG shown are embedded along the longitudinal direction of the strip 200, but in an alternative embodiment, data can be acquired by one or more FBGs embedded perpendicular to the length of the strip, where the processor analyzes the deformation accordingly.

[0034] Furthermore, in other embodiments according to the principles of the invention, the blood pressure monitor described above can also be combined with other small physiological monitors (measuring blood oxygen saturation, body temperature, and blood glucose using known contact temperature sensors and optical methods) to create a comprehensive wearable health monitor. These other small physiological monitors can be individual devices or components of some embodiments, used in separate, independent devices for communicating with the health monitor via wireless transmission (e.g., Bluetooth or near-field communication). For example, the blood oxygen saturation sensor can be in the form of a ring that communicates with the health monitor.

[0035] In other embodiments, a single optical fiber having multiple FBGs (each FBG having a unique Bragg wavelength and spaced apart from each other by a predetermined distance) tangent along its length can be configured such that some FBGs are at the top of an artery (e.g., the radial artery), while others are away from the artery. Such an optical fiber can be detected using a single light source and a light sensor. In this configuration, the pulsating component of the Bragg wavelength offset of the FBGs overlapping the artery can be used to measure the BP waveform, while the non-pulsating wavelength offset of the FBGs not overlapping the artery can be used to correct for baseline offset of the blood pressure waveform and also for temperature sensing.

[0036] Figure 4 Another embodiment according to the principles of the invention is shown. Figure 4In this embodiment, the wearable blood pressure monitoring system 400 comprises a blood pressure processing unit 450 and a detachable band 440. The detachable band 440 includes at least one blood pressure sensing optical fiber 410 with an FBG and a baseline optical fiber 460 with an FBG. The blood pressure processing unit 450 includes internal electronics (not shown) that enable pulsed laser or light to pass through the optical fibers 410 and 460 of the band 440, sensing the refractive index of the passing fibers, and processing a label to determine the blood pressure of the wearer A. The band 440 is removably connected to the blood pressure processing unit 450 such that, after connection, the unit 450 can pulse laser or light through the band 440. As a wearable device, the band 440 may become dirty or damaged. However, as a removable component of the device, the band 440 can be easily replaced at minimal cost.

[0037] Figure 5 This is a flowchart illustrating a method 500 for detecting blood pressure using a wearable device with an embedded fiber Bragg grating (FBG). Blood pressure detection can be initiated by a user or can be detected and monitored periodically. Once initiated, peak wavelength data is acquired from at least one FBG positioned along the wearable device in step 510. In step 520, data is continuously acquired, and the user's skin is monitored to obtain the effective offset of the FBG's Bragg wavelength due to surface deformation. When an offset is detected in step 530, the data is processed to calculate estimated systolic and diastolic blood pressure in step 540. The estimated systolic and diastolic blood pressure are then displayed in step 550.

[0038] All teachings of patents, published applications and references cited in this article are incorporated herein by full citation.

[0039] Although exemplary embodiments have been specifically shown and described, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the appended claims.

[0040] It should be understood that the exemplary embodiments described above can be implemented in many different ways. In some cases, the various methods and machines described herein can be implemented as physical, virtual, or hybrid general-purpose computers, each having a central processing unit, memory, disk or other mass storage device, communication interface, input / output (I / O) device, and other peripheral devices. A general-purpose computer can be transformed into a machine that performs the methods described above, for example, by loading software instructions into a data processor and then causing the instructions to be executed to perform the functions described herein.

[0041] As is known in the art, such computers may include a system bus, where a bus is a set of hardware lines used for data transfer among components of a computer or processing system. One or more buses are essentially shared conduits connecting different components of a computer system, such as processors, disk storage devices, memory, input / output ports, network ports, etc., enabling information transfer between these components. One or more central processing units are attached to the system bus and provide execution of computer instructions. I / O device interfaces for connecting various input and output devices, such as keyboards, mice, displays, printers, speakers, etc., to the computer are also typically attached to the system bus. Network interfaces allow the computer to connect to various other devices attached to a network. Memory provides volatile storage for computer software instructions and data for implementing embodiments. Disks or other mass storage devices provide non-volatile storage for computer software instructions and data for implementing various programs, such as those described herein.

[0042] Therefore, embodiments can typically be implemented in hardware, firmware, software, or any combination thereof.

[0043] In some embodiments, the programs, apparatuses, and processes described herein constitute a computer program product comprising a non-transitory computer-readable medium, such as a removable storage medium providing at least a portion of software instructions for a system, such as one or more DVD-ROMs, CD-ROMs, disks, magnetic tapes, etc. Such computer program products can be installed by any suitable software installer, as is well known in the art. In another embodiment, at least a portion of the software instructions may also be downloaded via cable, communication, and / or wireless connections.

[0044] Furthermore, firmware, software, routines, or instructions may be described herein as performing certain actions and / or functions of a data processor. However, it should be understood that such descriptions included herein are for convenience only and such actions are actually caused by a computing device, processor, controller, or other device executing firmware, software, routines, instructions, etc.

[0045] It should also be understood that flowcharts, block diagrams, and network diagrams may contain more or fewer elements, may be arranged in different ways, or may be presented in different ways. However, it should be further understood that certain implementations may indicate the block diagrams and network diagrams illustrating the execution of embodiments implemented in a particular manner, as well as the number of block diagrams and network diagrams.

[0046] Therefore, other embodiments may be implemented using various computer architectures, physical virtual cloud computers, and / or a combination thereof, and thus the data processor described herein is intended for illustrative purposes only and is not intended to limit the embodiments.

[0047] Although the invention has been specifically shown and described with reference to these exemplary embodiments, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as covered by the appended claims.

Claims

1. A health monitoring device, comprising: A blood pressure sensor comprising a first fiber Bragg grating configured to be placed near an artery or vein in contact with human skin and having a first Bragg wavelength; A baseline sensor comprising a second fiber Bragg grating configured to be placed away from the artery or vein in contact with human skin and having a second Bragg wavelength, and a second fiber Bragg grating providing a measurement baseline signal; A light emitter configured to transmit pulsed light waves through the fiber Bragg grating; An optical sensor configured to receive pulsed light waves; Processor, comprising: A data acquisition module is configured to receive the peak wavelength reflected by the fiber Bragg grating from the optical sensor; A comparator is configured to determine the effective offset of the first Bragg wavelength and the effective offset of the second Bragg wavelength over time; as well as A blood pressure estimator is configured to estimate systolic and diastolic blood pressure based on: 1) an effective offset of the first Bragg wavelength corrected for drift in the baseline signal based on an effective offset of the second Bragg wavelength; and 2) a calibration function; and A display used to provide estimated systolic and diastolic blood pressure. The health monitoring device uses the pulsating component of the first Bragg wavelength offset to measure the blood pressure waveform, and uses the non-pulsating wavelength offset of the second Bragg wavelength to correct the baseline offset of the blood pressure waveform.

2. The apparatus of claim 1, wherein the processor further comprises a heart rate monitor configured to detect periodic changes in surface deformation associated with heartbeat.

3. The device according to claim 1, further comprising a physiological attribute monitor.

4. The device according to claim 3, wherein the physiological property monitor measures one of blood oxygen saturation, body temperature, and blood glucose.

5. The apparatus of claim 1, wherein the display is located on a remote device, and further comprises a transmitter configured to transmit estimated systolic and diastolic blood pressure to the display.

6. The apparatus of claim 1, wherein the blood pressure sensor further comprises a plurality of fiber Bragg gratings configured to be placed near an artery or vein in contact with human skin and having a Bragg wavelength, wherein each fiber Bragg grating is shifted relative to another by a predetermined amount, and wherein the processor is configured to coordinate data acquired from the plurality of fiber Bragg gratings to optimize measurements of effective shift of the Bragg wavelength of the blood pressure sensor.

7. The apparatus of claim 1, further comprising a processor configured to determine the pulse pressure waveform based on an effective offset of the first Bragg wavelength corrected for drift in the baseline signal based on an effective offset of the second Bragg wavelength.

8. The apparatus of claim 7, wherein the processor is further configured to analyze pulse pressure waveform characteristics including the drop-off.

9. A health monitoring device, comprising: Processing unit, which includes i) A light emitter configured to emit pulsed light waves; ii) An optical sensor configured to receive pulsed light waves; iii) A data acquisition module configured to receive the peak wavelength reflected by the fiber Bragg grating from the optical sensor; iv) A comparator configured to determine the effective offset of the first Bragg wavelength and the effective offset of the second Bragg wavelength over time. as well as v) A blood pressure estimator configured to estimate systolic and diastolic blood pressure based on: 1) an effective offset of the first Bragg wavelength corrected for drift in the baseline signal based on an effective offset of the second Bragg wavelength; and 2) a calibration function; and vi) A display used to provide estimated systolic and diastolic blood pressure. The health monitoring device uses the pulsating component of the first Bragg wavelength offset to measure the blood pressure waveform, and uses the non-pulsating wavelength offset of the second Bragg wavelength to correct the baseline offset of the blood pressure waveform; and A flexible strip removably connected to the processing unit, comprising: i) A blood pressure sensor comprising a first fiber Bragg grating configured to receive pulsed light waves from the light emitter in the processing unit and configured to be placed close to an artery or vein in contact with human skin and having the first Bragg wavelength; ii) A baseline sensor comprising a second fiber Bragg grating configured to receive pulsed light waves from the light emitter in the processing unit and configured to be positioned away from the artery or vein to contact human skin and having the second Bragg wavelength and providing a measurement signal for the baseline.

10. The device of claim 9, wherein the blood pressure sensor further comprises a plurality of fiber Bragg gratings configured to be placed near an artery or vein in contact with human skin and having a Bragg wavelength, wherein each fiber Bragg grating is shifted relative to another by a predetermined amount.

11. A health monitoring device, comprising: A blood pressure sensor comprising a first fiber Bragg grating configured to be placed near an artery or vein in contact with human skin and having a first Bragg wavelength; A baseline sensor comprising a second fiber Bragg grating configured to be placed away from the artery or vein in contact with human skin and having a second Bragg wavelength, and a second fiber Bragg grating providing a measurement baseline signal; A light emitter configured to transmit pulsed light waves through the fiber Bragg grating; An optical sensor configured to receive pulsed light waves; Processor, comprising: A data acquisition module is configured to receive the peak wavelength reflected by the fiber Bragg grating from the optical sensor; A comparator is configured to determine the effective offset of the first Bragg wavelength and the effective offset of the second Bragg wavelength over time; as well as The processor is configured to determine the pulse pressure waveform based on the effective offset of the first Bragg wavelength, which is corrected by the drift in the baseline signal based on the effective offset of the second Bragg wavelength. as well as A display is provided to show the pulsed pressure waveform. The health monitoring device uses the pulsating component of the first Bragg wavelength offset to measure the blood pressure waveform, and uses the non-pulsating wavelength offset of the second Bragg wavelength to correct the baseline offset of the blood pressure waveform.

12. The apparatus of claim 11, wherein the processor is further configured to analyze pulse pressure waveform characteristics including the drop-off.

13. The device according to claim 11, further comprising a physiological attribute monitor.

14. The apparatus of claim 13, wherein the physiological property monitor measures one of blood oxygen saturation, body temperature, and blood glucose.

15. The apparatus of claim 13, wherein the processor is further configured to determine estimates of systolic and diastolic blood pressure based on the pulse pressure waveform and physiological properties measured by the physiological property monitor.

Images