Heart rate and blood pressure monitoring biosensors

Embodiments of the present invention are directed to a systems and methods for registration of pulse wave signal and determining arterial pressure. A non-limiting example of the system includes a strain gauge sensor. A non-limiting example of the method includes receiving, to a processor, a first pressure pulse signal from a first strain gauge sensor. The method also includes receiving, to the processor, a second pressure pulse signal from a second strain gauge sensor. The method also includes determining a pulse transit time between the first strain gauge sensor and the second strain gauge sensor based at least in part upon the first pressure pulse signal and the second pressure pulse signal. The method also includes determining an arterial pressure based at least in part upon the pulse transit time.

BACKGROUND

The present invention generally relates to fabrication methods and resulting structures for biosensors. More specifically, the present invention relates to heart rate and blood pressure monitoring using wearable sensors.

Blood pressure and pulse monitoring can be important in the treatment and prevention of a variety of medical conditions. For example, monitoring pressure pulse waves, heart rate variability, and arterial pressure can be important to characterize cardiovascular disease and other conditions involving altered cardiac function. Heart contractions generate pulse waves that travel to peripheral arteries. The characteristics of such pulse waves can provide a number of insights into the status of internal systems. For example, the speed of travel of the pulse waves and rhythmically of pulse waves can correlate to arterial stiffness, heart rate variability, and blood pressure. Monitoring and characterizing aspects of blood flow, such as pressure pulse wave characteristics and arterial pressure, can provide indicators, for instance, of cardiovascular events, hypertension, organ damage, and even lung function.

SUMMARY

Embodiments of the present invention are directed to a computer implemented method for determining arterial pressure. A non-limiting example of the method includes receiving, to a processor, a first pressure pulse signal from a first strain gauge sensor. The method also includes receiving, to the processor, a second pressure pulse signal from a second strain gauge sensor. The method also includes determining a pulse transit time between the first strain gauge sensor and the second strain gauge sensor based at least in part upon the first pressure pulse signal and the second pressure pulse signal.

Embodiments of the present invention are directed to a computer-implemented method for determining arterial pressure. A non-limiting example of the method includes receiving, to a processor, an electrocardiogram (ECG) signal from an ECG electrode. The method also includes receiving, to the processor, a pressure pulse waveform from a strain gauge sensor. The method also includes extracting, by the processor, an ECG feature from the ECG signal. The method also includes extracting, by the processor, a pressure pulse wave feature from the pressure pulse waveform. The method also includes determining, by the processor, an arterial pressure based at least in part upon the pressure pulse wave features and the ECG features.

Embodiments of the present invention are directed to a biosensor system. A non-limiting example of the system includes a wearable sensor capable of detecting a pressure pulse wave signal through the skin of a subject. The system also includes a wearable device for affixing the wearable sensor to a skin of a subject. The system also includes a circuitry module including a control unit for receiving signals from the wearable sensor and a data communication unit capable of communicating with an external device.

In the accompanying figures and following detailed description of the described embodiments, the various elements illustrated in the figures are provided with two or three-digit reference numbers. With minor exceptions, the leftmost digit(s) of each reference number correspond to the figure in which its element is first illustrated.

DETAILED DESCRIPTION

Turning now to an overview of technologies that are more specifically relevant to aspects of the invention, monitoring of pressure pulse waves, heart rate variability, and arterial pressure are important to prevent, treat, or manage cardiovascular diseases and ischemic strokes and other medical conditions.

A common conventional method to record pulse pressure waves is photoplethysmography. In photoplethysmography, blood volume changes in peripheral arteries are detected by optical sensors based on principles of light scattering. Such optical sensors can be placed on the chest, wrist, or finger of a subject.

Conventionally, non-invasive arterial pressure measurements can be measured by the sphygmomanometer, which includes inflatable cuffs commonly used in doctor's offices, clinics, and in home-based settings.

Conventional methods of measuring pressure pulse waves and arterial pressure suffer from a number of drawbacks. For example, photoplethysmography signals can be extremely sensitive to motion and, as such, are not useful for monitoring pressure pulse waves when a person walks or exercises. Sphygmomanometers and other known systems for measuring arterial pressure have a number of limitations. For instance, the sphygmomanometer, the most reliable device to measure arterial pressure (Pa), does not provide continuous measurements. Other methods can suffer from poor reliability issues.

Turning now to an overview of the aspects of the invention, one or more embodiments of the invention address the above-described shortcomings of the prior art by providing continuous estimation of heart rate variability and/or systolic and diastolic arterial pressure. Some embodiments of the invention provide non-invasive recording of pressure pulse waves at peripheral locations to determine heart rate variability and blood pressure. Some embodiments of the invention enable acquisition of heart and blood pressure data while a subject is in motion.

The above-described aspects of the invention address the shortcomings of the prior art by including semiconductor strain gauge materials to record transit time and wave form of the blood pressure wave. In some embodiments of the invention, semiconductor strain gauge sensors are included in patch systems that can be applied to the skin of a subject. In some embodiments of the invention, semiconductor strain gauge sensors are included in electrodes. Semiconductor strain gauge materials can be used to measure transit time and wave form of a blood pressure wave by placing sensors including semiconductor strain gauge materials on or near blood vessels, such as externally near an artery, such as on the neck, wrist, or temple, internally on or near an artery, or combinations of such placements. Sensors including semiconductor strain gauge materials can be used to determine blood pressure.

Embodiments of the invention can provide reliable, non-invasive measurements of vessel expansions induced by pressure pulse waves to provide blood pressure monitoring and subject health. The time interval needed by a pulse wave to travel from the heart to a peripheral artery or from a proximal artery to a distal one, referred to as pulse transit time (PTT), can provide information pertinent to monitoring subject health. Pressure pulse waves are generated as heart contractions cause blood to travel to peripheral arteries. A pulse pressure wave contains information relevant to a number of internal systems and processes. Pulse wave velocity depends, in part, on arterial pressure.

Systolic and diastolic arterial pressure can be estimated from PTT. PTT can be obtained by using two sensors that record electrocardiogram (ECG) and a plethysmogram, or two plethysmograms taken at different locations by either piezoelectric or piezoresistive sensors. Arterial pressure can be determined from PTT through the Moens-Korteweg equation, taking into account constitutive laws for arterial stiffness. Arterial pressure can, in some cases, be related to PTT by linear regression or non-linear formulas fit to experimental distributions of PTT-Pa data. Embodiments of the invention can measure blood flow characteristics through placement of strain gauge sensors using, for instance, Moens-Korteweg equation.

Turning now to a more detailed description of aspects of the present invention,FIG. 1depicts exemplary pressure pulse wave charts. The chart depicts a typical ECG waveform202. Methods and apparatuses for obtaining such signals are known. ECG signals can be, for example, digitized and analyzed according to various known methods to characterize a number of systemic features and conditions, such as heart rate and arrhythmias. The chart also depicts a strain gauge based wave form 204 that can be obtained according to embodiments of the invention. As shown, R represents an R peak, which can play an important role, for instance, in diagnosing heart rhythm abnormalities. According to embodiments of the invention, PTT can be obtained by using two sensors that record ECG and a plethysmogram. PTT is defined here as the time interval between the R-peak of the ECG, as shown, and the arrival of the pulse wave to one of the peripheral arteries (such as a radial artery), which can be observed via a strain gauge sensor according to embodiments of the invention as illustrated as point P1206inFIG. 1.

Systems according to embodiments of the invention can record pressure pulse waves at multiple peripheral locations, such as two or more locations, to characterize biological systems and conditions, including for instance characterization and determination of heart rate variability and systolic blood pressure. Sensors according to embodiments of the invention, including semiconductor or metal strain gauge sensors that use piezoresistive effect and/or piezoelectric-based strain gauge sensors and electrodes, can be used to record pulse transit time and the wave form of a blood pressure wave. Features of blood pressure wave form and ECG can be used, in some embodiments of the invention, for continuous estimation of systolic and diastolic arterial pressure.

Embodiments of the invention include sensors positioned on or near an artery. In some embodiments of the invention, biosensors, including strain gauge sensors, are placed on the skin at a location where an artery is capable of being compressed near the surface of the body, including at the carotid artery, brachial artery, radial artery, femoral artery, popliteal artery, posterior tibial artery, and/or the dorsalis pedis artery. In some embodiments of the invention, biosensors, including piezoresistive type strain gauge sensors and/or piezoelectric type strain gauge sensors, are implanted near an artery. For instance, biosensors can be inserted subcutaneously or can be placed directly on an artery. In some embodiments of the invention, biosensors are coated with a biocompatible material prior to insertion or implantation.

FIG. 2Adepicts a side view of an exemplary biological monitoring system300according to embodiments of the invention. As is shown, aspects of a sensing system300can be applied to the surface of the skin at an area in close proximity to an artery, such the surface of the skin308at a wrist. The system300can include a piezoelectric or piezoresistive sensor unit306and a circuitry module304. The piezoelectric or piezoresistive sensor unit can be a wearable sensor capable of detecting a pressure pulse wave through the skin of a subject. The circuitry module304can include, for example, a microcontroller, an amplifier, an analog to digital (A/D) converter, and a power and/or data communication unit capable of communicating wirelessly or via a wired connection to an external device such as smart phone, watch, tablet, notebook, etc. In some embodiments of the invention, the piezoelectric or piezoresistive sensor unit306and the circuitry module304are fastened to a band or belt302capable of encircling a body part, such as a wrist. The piezoelectric or piezoresistive sensor unit306is positioned, in some embodiments of the invention, against the surface of the skin. The circuitry module304can include a power source and can receive signals from the strain gauge sensor306and the external device, such as smart phone, watch, tablet, computer, or other electronic device.

FIG. 2Bdepicts a top down view of another exemplary biological monitoring system309. The system309includes a piezoelectric or piezoresistive sensor unit306, a circuitry module304electrically connected to the sensor unit306, and a band or belt302. The band or belt302, as shown, includes a protrusion310at the location of the sensor unit306to improve or enhance contact between the sensor unit306and the surface of the skin308. In some embodiments of the invention, the band or belt302includes a clasp312to fasten the band or belt302around the body.

Piezoelectric or piezoresistive sensor unit306can include piezoresistive based strain gauge sensors or piezoelectric based strain gauge sensors. In some embodiments of the invention, systems include biosensors including piezoelectric materials. In some embodiments of the invention, systems include semiconductor based strain guage sensors and piezoelectric based strain gauge sensors. As will be appreciated by those skilled in the art, the electrical properties of a semiconductor material in a semiconductor based strain gauge can be adjusted by modifying dopants and/or doping conditions, such as patterns and concentrations of dopant, depending on the desired properties and applications.

Embodiments of the invention include sensors including semiconductor and/or metal (e.g. nanoparticle based) strain gauge materials. Strain gauges measure strain that can be imparted by stress, torque, and a host of other stimuli such as displacement, acceleration, and position. The gauge factor for semiconductors can be several magnitudes larger than the gauge factor for metal. Thus, the change in conductivity due to strain can be much larger in semiconductor strain gauge materials relative to conductive strain gauge materials, providing highly sensitive strain detection and measurements.

Embodiments of the invention include metal based strain gauge sensors including, for example, nanoparticle-based materials, carbon nanotube based materials, nanofiber based materials, and/or combinations thereof.

In a semiconductor strain gauge material, a semiconductor substrate can provide a means of straining a silicon chip. Semiconductor base materials can be doped, for example by diffusion of doping materials, to obtain a desired base resistance. Advantageously, strain gauge materials can be several magnitudes smaller than metal sensors due in part on the difference in gauge factor. Strain gauges can be described, in some instances, with a function as follows:

Δ⁢⁢RR=Δρρ+Δ⁢⁢LL-Δ⁢⁢AA
where ρ is the resistivity of the material, L is the length of the material, A is the cross-sectional area of the material.

Methods of manufacturing strain gauge sensors, including semiconductor strain gauge sensors, are known. In some embodiments of the invention, a semiconductor base material of a semiconductor based strain gauge sensor can be doped. Doping can be selective doping, such that a specific area or region of the substrate is doped, or doping can be non-selective, for example such that the entire silicon substrate is doped to obtain a base resistance as needed. Non-limiting examples of suitable dopant materials include p-type dopants (e.g., boron), n-type dopants (e.g., phosphorus, arsenide, antimony), or any combination thereof. A substrate can provide strain for a silicon chip. In some embodiments, metal connections can be provided at the ends of a device.

Piezoelectric materials that can be used include, for instance, perovskite based materials and non-perovskite piezo-electric materials. Piezoelectric materials can include, for example, lead zirconate titanates (PZTs), potassium niobate, sodium tungstate, barium titanate (BaTiO3), and lead titanate (PbTiO3). Piezoelectric materials that directly generate a voltage that is a function of the strain can advantageously have higher efficiency than piezoresistive materials and can require less surface area. Moreover, piezoelectric based strain gauge sensors can be integrated in back end of the line (BEOL) of semiconductor manufacturing process.

Selected exemplary properties of piezoelectric materials and piezoresistive materials (semiconductor based strain gauge materials) are depicted below. The properties of piezoelectric materials can be varied, for instance depending on materials used, based upon the desired properties and applications.

FIGS. 3A and 3Bdepict another exemplary system400according to one or more embodiments of the invention, in whichFIG. 3Adepicts a side view of a system400according to an exemplary embodiment of the invention applied to the surface of the skin at an area in close proximity to an artery, such the surface of the skin at a wrist402.FIG. 3Bshows a top down view of the system400. The system400can include a piezoelectric or piezoresistive sensor unit306, an adhesive patch406, and a circuitry module408, including control and communication circuitry for the strain gauge sensor. The strain gauge sensor can include a piezoresistive material (e.g. semiconductor) or a piezoelectric material. The adhesive patch406can facilitate placement of the piezoelectric or piezoresistive sensor unit306in contact with the skin. The adhesive patch can include, for instance, a backing material such as a fabric or a flexible polymer, and an adhesive material capable of maintaining the placement of a sensor against the skin, including known dermal adhesives. The piezoelectric or piezoresistive sensor unit306send signals via the circuitry module408to an external device, such as a computer, tablet, or smart device (not shown inFIGS. 4A and 4B).

FIG. 4depicts another exemplary system500according to one or embodiments of the invention. The system500includes a headband504including a piezoelectric or piezoresistive sensor unit306and a circuitry module506. The headband504can be placed around a user's head502so as to position the sensor306near the temporal artery. The circuitry module506, which can include communication circuitry, can be placed on the headband, as shown.

Strain gauge sensor units according to embodiments of the invention, for instance systems as depicted inFIGS. 6 and 7, can be placed at single or multiple locations on a body. Embodiments of the invention including multiple strain gauge sensors can be formed in a variety of patterns and configurations.FIGS. 5A-5Ddepict shape of piezoresistive type strain gauge sensors according to embodiments of the invention.

FIG. 5Adepicts a linear pattern in which two strain gauge sensing pads are in a linear configuration separated by a connecting line of distance Y1 from 50 μm to 50 mm, and having a width X1 from 2 μm to 10 mm. The sensing pads can each have a width X2 from 50 μm to 5 mm and height Y3 from 50 μm to 5 mm.FIG. 5Bdepicts a u-shaped pattern in which two sensing pads, in which the connecting line X3can have a length, for instance of 6 μm to 30 mm.FIG. 5CandFIG. 5Ddepict alternate configurations including connecting lines including a plurality of deflection points.

FIG. 6depicts a schematic of an exemplary strain gauge sensor unit700according to embodiments of the invention. The strain gauge sensor unit700includes a semiconductor-based strain gauge sensor including a Wheatstone bridge circuit702. A Wheatstone bridge circuit702consists of resistors and it has the ability to provide accurate measurements. The unit700also includes an amplifier circuit704used for increasing amplitude of output signal from the Wheatstone bridge circuit702and an analog to digital (A/D) converter706. The strain gauge sensor unit700can also include a microcontroller708. The microcontroller708receives signals from A/D converter706and can have a capability of signal processing. In some embodiments of the invention, signal processing is performed by one or more external devices in communication with the exemplary strain gauge sensor unit700. The strain gauge sensor unit700can also include a register710including, for instance, flash memory and/or SRAM.

FIG. 7depicts a schematic of another exemplary strain gauge sensor unit800according to embodiments of the invention. The strain gauge sensor unit800includes a piezoelectric strain gauge sensor802. The unit800also includes an analog to digital (A/D) converter804that converts the analog signals coming from the piezoelectric strain sensor802into digital signals for input into microcontroller806. The strain gauge sensor unit800can also include a microcontroller806. The microcontroller806receives signals from A/D Converter804and can have signal processing capabilities. The strain gauge sensor unit800can also include a register808.

Advantageously, PZT sensors can be self-powered, for instance directly generating voltage that is a function of strain. In some embodiments of the invention, a piezoelectric strain gauge sensor unit does not have an external power system.

FIG. 8depicts a schematic of an exemplary strain gauge sensor system900according to one or more embodiments of the invention. The system900includes a sensing patch or band904and an external computing device902electrically and mechanically connected by wires. The sensing patch or band904can include a strain gauge sensor integrated within an adhesive patch, wrist band, head band, leg band, or other patch or band suitable for positioning a strain gauge sensor at or near an artery.

The external computing device902can include a PC, tablet, smart phone or other portable device. The external computing device902includes, for instance, a power supply906such as a battery, memory908, a controller910, and an interface controller912. The external computing device902can transfer power914and data916through wired connections to the sensing patch or band904.

The sensing patch or band904can include an interface controller918, a sensor control module920, and a piezoelectric or piezoresistive sensor unit306. The piezoelectric or piezoresistive sensor unit306can include a semiconductor based strain gauge sensor with a Wheatstone bridge circuit or a piezoelectric sensor. The interface controller918can include one or more interfaces924in communication with memory926and logic928. The sensor control module920can include for instance an amplifier, an A/D converter and a microcontroller.

FIG. 9depicts a schematic of another exemplary strain gauge sensor system1000according to one or more embodiments of the invention. The system1000includes a sensing unit1004and an external computing device1002. The sensing patch or band can include a strain gauge sensor integrated within an adhesive patch, wrist band, head band, leg band, or other patch or band suitable for positioning a strain gauge sensor at or near an artery. In some embodiments, the sensing unit is a component of an implantable device, such as a device positioned at or near an artery. An implantable device includes a device that includes or has been treated with a biocompatible coating suitable for implantation within a subject.

The external computing device1002can include a PC, tablet, smart phone or other portable device. The external computing device1002includes, for instance, a power supply1006such as a battery, memory1008, a controller1010, and a radio frequency (RF) reader/writer1012. The external computing device1002can send/receive data1016through a wireless connection (e.g. Bluetooth, WiFi, Near field communication (NFC), etc.) to the sensing unit1004by way of, for example, an electromagnetic field generated by antenna1013included in the external computing device1002and the sensing unit1004. In some embodiments, not shown inFIG. 9, power can be transmitted to the sensing unit1004by NFC.

The sensing unit1004can include an RF interface controller1018, a sensor control module1020, a piezoelectric or piezoresistive sensor unit306, and a power supply1014. The piezoelectric or piezoresistive sensor unit306can include a semiconductor based strain gauge sensor with a Wheatstone bridge circuit or a piezoelectric sensor. In some embodiments of the invention, the system1000includes a piezoelectric strain gauge sensor in place of the semiconductor-based strain gauge sensor, without a Wheatstone bridge circuit. The interface controller1018can include an interface1030in communication with memory1026, logic1028, and RF interface1024. The sensor control module1020can include for instance an amplifier, an analog to digital converter and a microcontroller.

In some embodiments of the invention, a strain gauge sensor is used in combination with other biosensors, such as heart rate monitors, pulse oximeters, thermometers, ECG instrumentation, respiration monitors, and the like. In some embodiments of the invention, systems include combinations of ECG sensors and strain gauge sensors.

Embodiments of the invention include methods for analyzing pressure pulse waves, heart rate variability, and/or arterial pressure derived from strain gauge sensors. Such methods can include obtaining a pressure pulse signal from a first strain gauge sensor, obtaining a pressure pulse signal from a second strain gauge sensor, wherein the second strain gauge sensor is positioned at a different location on a body than the first strain gauge sensor, and calculating the transit time of the blood from the first strain gauge sensor to the second strain gauge sensor. In some embodiments of the invention, a blood pressure is derived from the transit time. In some embodiments of the invention, a vascular stiffness parameter, such as an arterial stiffness index or other arterial stiffness characteristic, is derived from the transit time. In some embodiments of the invention, methods include extracting information from the pressure pulse signal waveform, for instance by machine learning. For example, the pressure pulse signal can be obtained over a period of time or over multiple periods of time for a subject and/or for other subjects and saved in a pressure pulse signal database. A pressure pulse signal can be compared to the pressure pulse signal database and unique, abnormal, or infrequent signal features and/or signal features associated with or that correlate to abnormal or problematic conditions can be derived from the pressure pulse signal based upon the database.

In some embodiments of the invention, strain gauge sensors are used for continuous determination of systolic and diastolic arterial pressure.

Embodiments of the invention include detection of heart failure by obtaining a pressure pulse signal from a strain gauge sensor and determining the presence or absence of heart failure by analyzing the pressure pulse signal.

FIG. 10depicts a flow diagram of a method1100for determining arterial pressure according to one or more embodiments of the present invention. The method1100includes, as shown at block1102receiving an ECG signal from an ECG electrode.

The method1100includes, as shown at block1104receiving a pressure pulse waveform from a wearable sensor, such as a sensor including a piezoelectric or piezoresistive material, such as a strain gauge sensor. The pressure pulse waveform can be recorded by plethysmography using a single semiconductor strain gauge sensing unit, such as a patch, band, or implantable device or a strain gauge sensing unit in combination with other biosensors, such as light sensors or other devices for plethysmography.

In some embodiments of the invention, ECG and/or plethysmography signals can be filtered with standard signal processing routines. In some embodiments of the invention, signal processing is performed by a device external to a wearable or implantable device. The method1100includes, as shown at block1106, extracting features from the ECG signal, such as an R-peak of a QRS complex and RR-intervals between neighboring QRS waves. The method1100includes, as shown at block1108, extracting pressure pulse wave features from the pressure pulse waveform, such as time of onset of the pulse pressure wave, time of wave peak, and time of the peak of reflection wave.

The method1100includes, as shown at block1110, determining arterial pressure based at least in part upon the pressure pulse wave features and the ECG features. For instance, systolic and diastolic arterial pressure can be estimated or determined based at least in part upon the interval between the R-peak and the onset of the blood pressure wave RP1(as depicted inFIG. 1), the interval between the onset of the pressure wave and the peak P1P2(as depicted inFIG. 1) of point P1206and point P2208, and the RR-intervals (RR, as depicted inFIG. 1). Arterial pressure or blood pressure can be computed based on linear regression or non-linear formulas derived from wave propagation principles.

FIG. 11depicts a flow diagram of another method1200for determining arterial pressure according to one or more embodiments of the present invention. The method1200includes, as shown at block1202, receiving a first pressure pulse signal from a first wearable sensor including a piezoelectric or piezoresistive material. The method1200includes, as shown at block1204, receiving a second pressure pulse signal from a second wearable sensor including a piezoelectric or piezoresistive material. For instance, a strain gauge sensor can be placed near a carotid artery and another strain gauge sensor can be placed on the wrist. The method1200includes, as shown at block1206, determining a pulse transit time between the first strain gauge sensor and the second strain gauge sensor based at least in part upon the first pressure pulse signal and the second pressure pulse signal.

In some embodiments of the invention, a pressure pulse signal is processed by an external device, such as a computer, tablet, or smart device in communication with the sensor, for example via circuitry in proximity to the sensor. In some embodiments of the invention, a pressure pulse signal is analyzed in the cloud.

Characteristics are as follows:

Service Models are as follows:

Deployment Models are as follows:

A cloud computing environment is service oriented with a focus on statelessness, low coupling, modularity, and semantic interoperability. At the heart of cloud computing is an infrastructure including a network of interconnected nodes.

Referring now toFIG. 13, a set of functional abstraction layers provided by cloud computing environment50(FIG. 12) according to one or more embodiments of the present invention is shown. It should be understood in advance that the components, layers, and functions shown inFIG. 13are intended to be illustrative only and embodiments of the invention are not limited thereto. As depicted, the following layers and corresponding functions are provided:

Hardware and software layer60includes hardware and software components. Examples of hardware components include: mainframes61; RISC(Reduced Instruction Set Computer) architecture based servers62; servers63; blade servers64; storage devices65; and networks and networking components66. In some embodiments, software components include network application server software67and database software68.

Referring now toFIG. 14, a schematic of a cloud computing node100included in a distributed cloud environment or cloud service network is shown according to one or more embodiments of the present invention. The cloud computing node100is only one example of a suitable cloud computing node and is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the invention described herein. Regardless, cloud computing node100is capable of being implemented and/or performing any of the functionality set forth hereinabove.

As shown inFIG. 14, computer system/server12in cloud computing node100is shown in the form of a general-purpose computing device. The components of computer system/server12can include, but are not limited to, one or more processors or processor16, a system memory28, and a bus18that couples various system components including system memory28to processor16.

Computer system/server12typically includes a variety of computer system readable media. Such media can be any available media that is accessible by computer system/server12, and it includes both volatile and non-volatile media, removable and non-removable media.

Program/utility40, having a set (at least one) of program modules42, can be stored in memory28by way of example, and not limitation, as well as an operating system, one or more application programs, other program modules, and program data. Each of the operating system, one or more application programs, other program modules, and program data or some combination thereof, can include an implementation of a networking environment. Program modules42generally carry out one or more functions and/or methodologies in accordance with some embodiments of the present invention.

Example 1—Comparison Between Strain Gauge Sensor and Conventional Pulse Oximeter

A semiconductor-based strain gauge sensor according to embodiments of the invention was applied to a wrist of a human subject with an adhesive material and connected to an external computing unit via a wired communication. A pulse measurement signal was obtained by the semiconductor-based strain gauge sensor and compared to a pulse measurement signal collected by a conventional pulse oximeter. The pulse measurement signals obtained are depicted inFIG. 15. As is shown, the strain gauge sensor correctly detects the periodicity of the pulse pressure signal, similar to prior art systems such as the pulse oximeter.

Example 2—Embodiment Including ECG and Strain Gauge Sensors

An ECG and a signal from a strain gauge sensor were simultaneously obtained for a subject known to have high systolic blood pressure. A strain gauge sensor recording was obtained for a period of ten minutes.FIG. 16Ashows the pressure pulse wave form obtained from the strain gauge sensor.FIG. 16Bdepicts the data obtained from the strain gauge sensor after filtering and extraction of features for estimation of blood pressure. After initial calibration with a conventional arm pressure cuff system, Systolic blood pressure was calculated from the filtered and extracted data by the Moens-Korteweg equation. Estimated pressure tracing is shown inFIG. 16C. A second arm cuff pressure measurement was performed at the end of the ten-minute session, showing good agreement between the conventional pressure cuff system and the combined ECG-strain gauge system.