NIBP

A NON-INVASIVE BLOOD PRESSURE DEVICE
Team Members:
Anirudh Ashok (aa2343)
Vaishali Bala (vb287)
Shreya Cullopulli (sc2697)
Akanksha Kapoor (ak2388)
Aditi Khattar (ak2392)
Soumyaa Varshni (ssv34)

1
TABLE OF CONTENTS
BACKGROUND OF THE INVENTION……………………………………………………….2
NEEDS STATEMENT…………………………………………………………………………...3
NEEDS CRITERIA……………………………………………………………………………....3
OVERVIEW OF CURRENT SOLUTIONS……………………………………………………..3
MARKET ANALYSIS……………………………………………………………………………5
EXPLORATION OF CURRENT BLOOD PRESSURE MEASUREMENT MODALITIES…..7
INITIAL CONCEPTS SELECTION…………………………………………………………….10
CONCEPT SCREENING……………………………………………………………………….11
CONCEPT DEFINITION………………………………………………………………………..14
BUSINESS MODEL…………………………………………………………………………….20
SWOT ANALYSIS……………………………………………………………………………...21

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BACKGROUND OF THE INVENTION
Blood pressure measurement helps in diagnosing cardiovascular diseases. Every single heartbeat
results in the flow of blood in the arteries of the body. This flow of blood varies with time, and is
caused by a periodic rise in blood pressure from a static value to a maximum value. The two
extremes are called diastolic pressure and systolic pressure respectively. This variation in blood
pressure caused by heartbeats results in a change in the optical properties of blood. The variation
of blood pressure in a heartbeat induces a variation in the optical properties of the blood. It is
important in the administration of anesthesia and in monitoring the patient’s physiology
continuously.
The blood pressure measurement device are divided into two major classes: invasive and non-
invasive devices. Most commonly used devices for monitoring blood pressure usually involve an
inflatable cuff. The cuff is placed around a patient’s arm, and is inflated so as to compress the
artery responsible for circulating blood to that arm. Then, the cuff is deflated slowly. This allows
for the determination of both diastolic pressure and systolic pressure by measurement. However,
this process is tedious, and often causes discomfort to the patient.
“Beat Vine” allows for non-invasive measurement of blood pressure using laser and signal
processing. This system provides a way to measure blood pressure using a wearable device that
has no cuff. It also transmits the patient’s data wirelessly to a central hub. This is highly useful for
monitoring the state of the patient, and significantly reduces the response time for a healthcare
professional in case something untoward happens. This device focuses on patients in a clinical
environment (ICU, operation theatre and emergency medical services) and home environment.
Being a portable device, it gives patients a sense of mobility and helps the doctors and nurses keep
a constant track of their blood pressure without having to do regular follow ups.
Figure 1: Target areas for Beat Vine

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NEEDS STATEMENT
A method to measure blood pressure continuously and accurately using a non-invasive device in
any clinical environment and home environment.
NEED CRITERIA
The following are need criteria that the solution must meet:
● Solution should work continuously in real time without any interruptions.
● Solution should be lightweight and portable.
● Solution should automatically monitor blood pressure non-invasively.
● Solution should be able to reduce the time required for patients to measure blood
pressure.
● Solution should be a wearable device.
● Solution should be able to provide accurate measurements compared to current devices in
market.
● Solution should be convenient for the patient to use and wear.
OVERVIEW OF CURRENT SOLUTIONS
Blood pressure cuffs are usually placed on the upper arm to obtain non-invasive BP measurements.
However, there have been studies where upper arm cannot be used which are why clinicians have
started using alternatives. Currently, measuring blood pressure at locations distal to the upper arm
for example forearm, wrist, and finger/thumb which are associated with increased resistance to
blood flow in smaller diameter arteries is a novelty.
As noticed in the BME instrumentation lab, blood pressure is usually monitored using a
sphygmomanometer, or colloquially known as a blood pressure cuff, which outputs systolic and
diastolic pressure measurements along with heart rate. There are other ways to determine blood
pressure such as using Tonometry, Palpation, Auscultatory, Oscillometric, and Ultrasound method
etc.
Tonometry
Tonometry of radial artery provides an accurate, reproducible, noninvasively monitors central
waveform. Using a probe over the radial artery and applying mild pressure to partially squeeze the
artery, pressure is then transmitted from the vessel to the sensor (strain gauge) and recorded
digitally. Furthermore, Fourier transformation is used to calculate of central systolic blood pressure
collected from peripheral brachial blood pressure to radial artery.
Palpation
Palpation method uses a technique of deflating or inflating arm cuff to occlude by either the
brachial artery and then detect the pulsation changes of the radial artery. A minimum systolic value
can be estimated with any equipment by palpation in emergency situations. However, diastolic
blood pressure cannot be measured by this method.
Auscultatory

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The auscultatory method uses a stethoscope and a sphygmomanometer to audibly detect korotkoff
sounds. This is an inflatable cuff is placed around the upper arm approximately at the same height
as the heart. It is attached to a mercury or aneroid manometer. The pressure at which this sound is
first heard is the systolic blood pressure. The cuff pressure is further released until no sound can
be heard (fifth Korotkoff sound), at the diastolic arterial pressure.
Oscillometry
Oscillometric blood pressure measurements are obtained by using automated device using an
electronic sensor to detect or monitor the pulsatile changes in pressure that are caused by the flow
of blood through an artery that is restricted by occluding cuff. However, oscillometric monitors in
the market produces inaccurate readings in patients with heart and circulation problems like
arteriosclerosis, arrhythmia, preeclampsia.
Ultrasound
In recent methods, arterial blood pressure is preferable because of the potential portability of an
ultrasound system and minimizing tissue damage as well as possibility of infection. In this method,
blood pressure is measured by identifying elastic and mechanical properties of arterial walls, which
are referred as pulse wave velocity. As ultrasound waves travels through the walls of brachial
which is relatively easy to detect, involves monitoring the motion of arterial pulse wave under an
occlusive cuff. Systolic pressure can be determined by using the Doppler’s principle. Through
Doppler’s principle, velocity-time integrals and cross sectional areas at the same anatomical
location and at the same time is measured. The results presented on the machine is as a results of
blood flow and resistance. This tool of measuring blood pressure using ultrasound is inexpensive
yet a powerful cardiovascular diagnostic tool.
The aforementioned methods have certain limitations like taking pressure on the upper arm is
painful for patients and provides non-continuous results, while taking readings the patient has to
avoid any movement interruption. Also, these techniques are stressful for certain group of
population because the occlusion of the whole arm leads to venous congestion. Therefore, Our
major targets for designing a new device Beat Vine was to demonstrate accurate readings, making
the device cuff-less, a method that does not disturb the patients and permits him to follow daily
activities.

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MARKET ANALYSIS
The size of the non-invasive blood pressure monitoring device market is well defined. The size of
the population forming this market is about 65 million individuals in the United States alone. That
is about 30% of the entire population.
Hypertension can be associated with various factors in contemporary lifestyle. Hypertension is
checked in all individuals in a clinical environment as a regular protocol which increases the size
of the market, but our product being priced slightly higher may only be used in specific clinical
environment like the AKD (ambulatory kidney dialysis) unit. So we have focused our market
analysis towards the domain of hypertension.
The Beat Vine unlike other devices in the market, measures blood pressure real time. It is a cuffless
device and is not reliant on the exertion of pressure. There is no defined market size for devices
that continuously measure BP. Any value purported by a market analysis for continuous BP
monitoring would only be a guesstimate as most devices are in their conceptual stages and many
are yet to exit product pipelines. The best manner in which the price of an end product can be
predicted in our case is to compare to other wearables the general public and clinical bodies are
investing in.
The traditional anemometric method that uses a Sphygmomanometer is still the most relied on
method used in hospitals as doctors and staff have relied on its simple, infallible technique since
Samuel Siegfried Karl Ritter von Basch invented it in 1881.
Nurses and other ancillary staff on duty take BP readings at least thrice a day and even more
regularly in clinical environments like the Ambulatory Kidney Dialysis Units.
Size of the market
The size of the Hypertension market is $42.9 billion USD.
Figure 2: The market can be segmented on the basis of essential and secondary hypertension

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Figure 3: Prices and rating of various non-invasive Blood Pressure devices.
The willingness to pay has been estimated at $2000 to $3000 for a product of this caliber and
sophistication.

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EXPLORATION OF CURRENT BLOOD PRESSURE MEASUREMENT MODALITIES
Analysis of non-invasive blood pressure devices in the bioinstrumentation lab
Figure 4: Our team had an effective session at the bioinstrumentation lab. We discovered
various shortcomings in the current blood pressure devices in the market.

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Brainstorming
Three brainstorming sessions were conducted amongst the team members.
Session 1:
The first session involved generation of many concepts. Members of the team took apart the
current modalities and argued how they would tackle the same scenario uniquely. Session 1
ended with the team shortlisting Ultrasound and Lasers as their approaches of interest.
Figure 5: Initial brainstorming session
Figure 6: Left: Brainstorming several blood pressure measuring techniques
Right: Determining anatomical location of device placement

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Session 2:
The second brainstorming session involved discussing those three concepts. A final concept was
chosen after this session.
Figure 7: Concept Screening
Figure 8: Analyzing laser technique of measuring blood pressure

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Figure 9: Analyzing the ultrasound technique of measuring blood pressure
INITIAL CONCEPTS SELECTION
The brainstorming session led to the creation of many ideas and concepts, however after screening
all the concepts it was clear that three of those concepts- Ultrasound, LEDs and Laser Holography-
offered relevant solutions to the problem. The ideas generated were compared against the need
statement and need criteria defined in the initial stages of the biodesign process. The organizing
principles that have been taken into consideration to cluster the ideas generated.from first
brainstorming session are as follows: anatomic location, accuracy of device, mechanism of action,
technical feasibility, portability of device and funding required to implement the solution.
The following table compares three concepts that were initially selected to be taken forward in the
design process and were compared using the organizing principles:

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Concept Anatomic
location
Accuracy Source Technical
feasibility
Fund
requirement
Portability
Ultrasound upper arm high ultrasound
waves
generated
from a
piezoelectric
crystal
high high bulky
Laser upper arm high laser beam
generated
from
sapphire
crystal
high high portable
LED used in
areas of thin
cross
section
low light (red
and infrared)
emitted from
photodiodes
high low portable
CONCEPT SCREENING
Laser was chosen over the above mentioned methods due to the following reasons:
● Laser is comparatively more cost effective. The set-up is smaller in size and not many
components are involved hence the deflation in cost.
● Laser is more accurate. Studies show that the standard deviations of the differences from
actual blood pressure were lesser for laser automated devices than compared to
conventional methods (sphygmomanometry).
● Laser can be applied to any part of the body (including the eye), hence the blood pressure
can be measured anywhere on the body.
● It is known that greater the scattering (shorter wavelength), lesser the depth of laser
penetration and more possibility of its absorption. A wavelength of ~685nm (low
wavelength, high frequency) can be used, which falls under the visible light range-near
infrared.
● The low wavelength and high frequency allow the photons to penetrate deep into the
tissue without the effect of heat. Hence the product is safe for human use.

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Session 3:
The third session involved discussing the prototype and brand name of the device. The sessions
were made successful by following some of the brainstorming rules set forth by the product
design company IDEO.
Figure 10: Determination of device design, brand name and brand logo

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CONCEPT DEFINITION/SPECIFICATION
The Beat vine is a non-invasive, real time blood monitoring device that uses a design inspired by
grape vines. This simple to wear device easily opens into a long belt and can conform to the arm
of any adult human being. The device unlike most pressure cuffs does not use inflation and
oscillometry to gauge blood pressure. This first of a kind device uses Laser Holographic
interference to predict blood pressure in the arteries. This device uses holography which is a 3D
imaging technique that captures the volumetric information of an object instantaneously and blood
pressure is then calculated due to the interference of the waves by using laser Doppler flowmetry
technique. This process requires a laser of high frequency and low wavelength as the light source
because shorter wavelength leads to greater scattering and this implies less depth of penetration
and more possibility for absorption. This procedure uses a high frequency sapphire laser to
illuminate the tissue, light is scattered in the tissues and moving blood cells. Light scattered by the
moving blood cells, is broadened spectrally using the Doppler effect.
The device consists of a laser source, beam splitter, mirror, CCD sensor, microcontroller unit and
digital signal processor.

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Figure 11: Working principle of Laser Doppler
As soon as the device gets activated, laser beam is generated from the sapphire crystal. A part of
the laser beam is directly shone onto the recording medium, and the other part onto the object in a
way that the scattered light hits the object and is reflected onto the recording medium.
The laser beam is passed through the beam splitter which divides the laser beam into two halves
in two different directions; namely, reference beam and illuminating beam.
The illuminating beam is focused onto the object with the help of the mirror. Some part of the light
is reflected or scattered from the object, hits the mirror and falls into the recording medium. The
reference beam is directly focused onto the recording media. When the two laser beams reach the
recording medium, their light waves interfere with each other because of the phase difference
between the reference and illuminating beam. The interference pattern is imprinted on the
recording media and is encoded by a charge coupled device which electronically records light
waves which are processed by a microprocessor and the final digital output is displayed on the
capacitive screen.

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The Logic Flow chart is shown below:
Interference pattern
Memory
Digital
signal
Processor
Microcontroller
Unit
Signal
processing
algorithm is
executed
Analog to
Digital
conversion
Charge
coupled
device
Relay
data
wirelessly
to server
Laser probe
Laser is
incident
on artery
Laser reference
i l
Reflected
signal

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Overview for Texas Ins. MSP 4302P4x Low Power + Performance Microcontroller Unit
MSP Low Power, Performance microcontrollers (MCUs) from Texas Instruments (TI) provides
us with increased processing capability, smart analog, advanced security, and display and
communication peripherals while using less wattage. This is our processor of choice as we need
to increase the operating time of our device over several days without it being charged. The MSP
4302P4x series of controllers have a fast processor and also readily interface with capacitive
screens, Usb ports and are the weapon of choice for designers of wearable technology.
Figure 12: Microcontroller Architecture
Texas Instruments C55x Dual MAC DSP
A DSP or a digital signal processor allows us to transduce the Charge coupled device signal to a
digital signal and apply our signal conversion algorithm or the Fast Fourier transform (FFT).
The reasons we've picked Texas Instrument's C55x are given below.
· Ultra-low power DSP
· Tightly coupled hardware FFT accelerator
· Integrated USB 2.0
· Audio and speech codecs
· DSP math libraries

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Figure 13: DSP c55x Architecture
Method For Calculating Blood Pressure Using DSP
Traditional non-invasive electronic cuff devices use Navier Stokes differential equations which
provide a relationship between blood pressure and velocity pulse but they do not take blood
viscosity, blood density and arterial diameter which are important parameters influencing blood
pressure. This explains the inaccuracy in the final measurements. The technique used in the device
proposed implements laser doppler flowmetry to calculate the blood pressure. This method utilises
pulse wave velocity, arterial diameter and reflection coefficient into consideration.
Measuring blood pressure non-invasively and without external pressure is determined by
measuring other cardiovascular parameters. Relationship between the three arterial pulse forms
of pressure pulse p, flow or velocity pulse i or v and volume pulse R are derived for blood
pressure measurement.
The general form of the motion equation for a flowing, incompressible fluid (Navier Stokes
equation system) is considered.
Figure 14: Propagation of a pulse wave in an arterial segment
(1)

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To solve the partial nonlinear equation (1), some assumptions are made. The convective
acceleration can be neglected because of slow velocities. The nonlinear parts can also be
neglected, since the phase velocities are greater than the axial velocity, phase velocity is much
greater than the radial velocity. Additionally, the second order derivatives of z can be neglected.
External forces, e.g. gravity, and the radial pressure gradient can also be neglected.
(2)
After converting equation (2) with a harmonic separation statement of the superposition of
forward and backward waves and equating the axial acceleration component to zero at r = 0, the
forward and backward pressure of the arterial system are determined.
From the equations mentioned above, it is evident that the pressure pulse consists of the sum, the
flow pulse of the difference of a forward and backward wave.
Considering two locations z1 = 0 and z2 = l at one vessel segment, pressure p1 can be calculated.
(3)
Therefore, blood pressure p depends on the flow pulse i or the mean velocity pulse v = i /
Pi*R0^2, the propagation coefficient and the cardiovascular parameter.
The graphs below describe the measured flow pulse and calculated blood pressure. The graphs
are generated and processed in the DSP, Analog to Digital Conversion. The final readings are
calibrated by forming a causal relationship between traditional techniques and the values seen in
our device. This technique is called the Riva Rocci calibration method.

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Figure 15: Measured flow pulse and calculated blood pressure
Wireless chip eZ430-RF/CC430 SoCs
An interfacing chip that enables the MSP processor from TI to communicate over WI-fi
networks with radio frequency waves that it generates. This component is used to transfer
measurement to the server which enables communication of records between the doctor and
patients.
BUSINESS MODEL
CONTRACT
MODEL
TRAINING
FREE
SERVICE
PRODUCT IS
LEASED AS PER
SUBSCRIPTION
PRODUCT IS
STILL OWNED
BY BEAT VINE
INC.
HIGH
MARGIN
PAY PER
MONTH
SALES
FORCE
MARKETING
TEAM &
PROMOTIONAL
MATERIAL
FORSEEABL
E REVENUE

20
The Contract based model is chosen as our path to market. The reason is that the device by
itself is expensive and might not be purchased outright by Institutions and homes requiring it.
The plan is to lease these devices on a contract basis. This way any fault or damage to the
device can easily be taken care of by the company without the user sharing liability. The
company can easily replace the machine and repair it at a minuscule cost.
SWOT Analysis
A SWOT analysis was conducted to understand the strength, weaknesses, opportunities and threats
involved in our business and for the product offering being made.
Figure 16: SWOT analysis

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REFERENCES
1) http://www.biomedical-engihttp://www.medgadget.com/2012/01/company-claims-
optical-blood-pressure-monitor-breakthrough.html
2) neering-online.com/content/8/1/28
3) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2825126/
4) http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.41.4045&rep=rep1&type=pdf
5) http://www.google.com/patents/US2011017841

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