Design and Implementation of a Compact Temperature, Heartbeat and ECG Measurement Module

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International Journal of Engineering Trends and Technology ( IJETT ) – Volume 61 Number 1 – July 2018
ISSN: 2231 – 5381 http://www.ijettjournal.org Page 31
Design and Implementation of a Compact
Temperature, Heartbeat and ECG
Measurement Module
Jibesh Kanti Saha1, Shahadat Hussain Parvez2, Puja Rani Saha3
1Faculty, Dept. of EEE, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh.
2Faculty, Dept. of CSE, North East University Bangladesh, Sylhet-3110, Bangladesh.
1Faculty, Dept. of CSE, Leading University, Sylhet-3110, Bangladesh.
Abstract
In this work we designed a user friendly
compact biomedical device that helps user to monitor
and record change in general vital signs like- body
temperature, heartbeat and ECG (electrocardiogram)
with simple digital sensor models. Conventional
biomedical devices are costly and requires expert
personnel to operate the device. This device was
designed to ensure portability, user-friendliness,
reliability, ease of maintenance and cost optimization.
The device also incorporates a computer interface
software which will show real time ECG graphs and
other measured biomedical data. This device can ensure
user-friendly patient monitoring and better
medication based on data statistics collected.
Keywords — Biomedical Device, Patient
Monitoring, Real Time ECG, Body Temperature,
Heartbeat, Computer Interface, Biomedical sensors.
I. INTRODUCTION
Day by day health conscious people are increasing
and they urge for frequent monitoring of their health
for a sound life. But this leads to exponential increase
in cost and hazards for ensuring care of general mass.
And in developing countries with less health care
facilities and practitioners in comparison with
popularity cannot cope up with this scenario.
Therefore, people are heading to cheap, reliable and
easily accessible health monitoring systems. This
golden era of electronics with its rapid advancement
opened up vast opportunities in this field. Measuring
instruments are also getting more compact and user
friendly. Newer and newer innovations are enriching
medical sectors greatly and this plays crucial role in
our civilization. Our work is a health monitoring
system with user friendly computer interface can
facilitate greatly as an easy household device. Such
remote patient monitoring framework is quite
common in technologically advanced countries in
different models like clinical monitoring, wearable
sensor network and so on [1]. These models save
huge time, money and hazards and also encourage
people to be more conscious of their own health.
Moreover, treatments with statistical data and
continuous monitoring can be achieved very easily
which helps different physicians deeply. In
developing countries such trend can have massive
impact on social and health development of general
mass.
II. OBJECTIVES
The objectives of this project are to design and
implement a compact biomedical module facilitated
with computer interface which can measure basic
vital body signs like temperature, heart rate variability
and electrocardiogram. The data can be viewed in real
time via the interface both graphically and textually.
The whole model can be divided into four sections
shown in fig.1 below which are linearly connected
and dependent.
Fig. 1 System overview
III. METHODOLOGY
A. Body Temperature Measurement
1) Background Study: Body temperature is one
of the oldest known diagnostic methods and is still a
vital sign of healthiness [1]. Variation from normal
temperature dictates disturbance in body system.
Body temperature is body's measurement of
generating and getting rid of heat. When heat rises the
blood vessels in skin widen to carry the excess heat to
skin's surface and helps cooling your body. Again,
when heat in body falls, blood vessels get narrower
and reduces blood flow to save body heat. Measuring
one‟s body temperature is an initial part of a full
clinical examination. Body‟s core temperature refers
to the thoracic and abdominal contents, some muscles
and brain, while the peripheral temperature relates to
a relatively small amount of subcutaneous tissue and
mostly the skin [2]. Generally, there exists thermal
gradient between the body surface and the deeper
tissues. It is seen that for each 4mm depth
temperature rises about 1°C approximately [3].
Specifically, the pulmonary artery (PA) measures the
temperature of mixed venous blood from the upper
and the lower parts of the body as well as the core and

International Journal of Engineering Trends and Technology ( IJETT ) – Volume 61 Number 1 – July 2018
ISSN: 2231 – 5381 http://www.ijettjournal.org Page 32
the periphery and so considered as the gold standard
of core temperature generally [4]. Usually in clinical
and household practice non-invasive methods are
popular [5].
2) Hardware: For measurement we used DS18B20
sensor which has a wide range of features other than
the popular use of temperature measurement. In this
sensor temperature measurements are made using two
bandgap-generated voltage sources. It senses
temperature by its unique 1-wire interface. Fig. 2
shows the waterproof model of DS18B20 sensor. In
final model temperature circuitry needs only these
following components:
 DS18B20 Digital temperature sensor
 Microcontroller (ATmega 328)
 Resistor (4.7K)
Fig. 2 DS18B20 sensor
3) Process Flow: Heartbeat detection model is
implemented with different phase of actions. Fig. 3
illustrates the process flow comprising with the
subdivisions to implement the total thing.
Fig. 3 Process flow of Temperature measurement
4) Schematic: The following Fig. 4 is the
schematic diagram of the circuit designed for
temperature measurement.
Fig. 4 Temperature measurement circuit schematic
B. Heart Rate Measurement
1) Background Study: In 2005, WHO (World
Health Organization) reported that about seventeen
million people died in heart disease around the world
[6]. So, it is unquestionable that heart rate monitoring
has a great importance in patient monitoring. Heart
beat is a vital body sign which indicates the time
duration of a cardiac cycle. It is related to the
contraction of the muscles of the heart or a perceived
effect of it. As the heart pushes blood through the
arteries, the arteries expand and contract with the
flow of the blood. Resting heart rate means when
heart is pumping lowest amount of blood. It is usually
within 60 to 100 BPM according to many test-cites
[7]. Fast heart rate above 100 bpm at rest is defined as
Tachycardia [8]. Heartbeat of irregular pattern is
referred to as an arrhythmia. Heart rate pattern is
important because abnormalities of heart rate can
indicate different disease [9]. The heart rate monitor
can find several types of applications. Such as they
can be used in the hospitals, elderly health care,
personal emergency response or sport training [10].
Heart rate variability (HRV) is a special parameter
that can be measured during heart beat measurement.
While heart rate measures average beats per minute, it
measures the specific changes in time between
successive heart beats. HRV is generally measured in
milliseconds. HRV is best to measure at rest. At rest a
high HRV is generally preferable. Whereas in an
active state lower relative HRV is generally
favourable.
The principle of operation is based on photoelectric
plethysmography. There are two types of
photoelectric plethysmography.
 Transmission based
 Reflection based
We used the reflection-based process.
Haemoglobin of blood can absorb a substantial
portion of light in our body and rest of them are
reflected from the body parts. In each cardiac cycle
blood concentration varies. This concentration
variation changes the amount of light reflected back
from the body parts. For our measurement we used
green light from a solid-state LED lamp instead of IR.
Green light has much less wavelength (about 525 nm)
than IR light as seen from the relative absorbance of
haemoglobin in Fig. 5 [11].
Fig. 5 Relative absorbance of hemoglobin

International Journal of Engineering Trends and Technology ( IJETT ) – Volume 61 Number 1 – July 2018
ISSN: 2231 – 5381 http://www.ijettjournal.org Page 33
2) Hardware: To implement the heartbeat
measuring circuitry we used following components.
 SEN-11574 pulse sensor
 Microcontroller (ATmega 328)
 Low power Op-amp
 Resistors and capacitors
SEN-11574 is integrated with a solid state green
LED and an ambient light photo sensor, which fits
our need.
3) Process Flow: Heartbeat detection model is
implemented with different phase of actions. The
process flow in the Fig. 6 shows the working process
of heartbeat measurement.
Fig. 5 Process flow of heartbeat detection
4) Schematic: There as three parts of the schematic
for the heartbeat measurement circuit as shown in Fig.
6.
Fig. 6 Schematic of heartbeat measurement circuit
The first portion is named as „Capturing reflection‟.
With necessary circuitry there are a green led and a
photodetector. The light from the green led reflects
due to blood volume variation and photodetector gets
readings capturing the reflection. Photodetector
output comes with noise that is managed by the
filtering potion. The filtering portion is the second
part that comes with necessary circuitry named as
„Filtering part‟. The third and last part is „Amplifying
part‟. This section amplifies the processed filtered
output to a meaningful level. This output is feed to
microprocessor analog read. The further processing is
done through coding logics implemented according to
this reading.
C. Electrocardiogram (ECG)
1) Background Study: ECG is short form for
electrocardiogram or electrocardiograph, which is the
measurement process of heart‟s electrical activity, the
more appropriate term for which is the cardiac
conduction system. There are several ways to
measure ECG but mostly used and popular among
them is standard 12 lead ECG. In this method 12
electrodes are placed along chest, abdomen, hand and
leg and different signals are measured from these
electrodes. Besides the standard 12 lead ECG there
are several other methods in use [12].
 3 channel ECG
 5 channel ECG
 Vector electrocardiography
 Body surface mapping
In our thesis work we used a modified version of the
3-channel approach. This method is known as Wilson
electrode system combined with right leg driven
circuit. The right leg drive circuit works to reduce
interference from the amplifier. Amplifying an ECG
signal and creating a DC common mode bias off the
inputs of the differential amplifier causes extreme
susceptibility to common mode interference. Fig. 7
illustrates the right leg drive circuit [13].
Fig. 7 Right leg drive circuit
2) Hardware: The following components are used
for ECG measurement process:
 AD8232 sensor
 Microcontroller (ATmega 328)
 ECG leads
AD8232 sensor is a single lead ECG front end with
common mode rejection ratio of 80 dB (dc to 60 Hz).
It works with two or three electrode configurations.
The integrated right leg drive amplifier is a major part
of this sensor. It also provides leads off detection both
for ac and dc. We used normal electrodes that are
used to measure such biopotential signals. These are
composed of a metal (usually silver for ECG

International Journal of Engineering Trends and Technology ( IJETT ) – Volume 61 Number 1 – July 2018
ISSN: 2231 – 5381 http://www.ijettjournal.org Page 34
measurement) and a salt of the metal (usually silver
chloride). Additionally, some form of electrode grade
or jelly is applied between the electrode and the skin.
3) Process Flow: ECG measurement needs several
phases to operate. In the process flow we have
subdivided the operations in simple three parts as
shown as Fig. 8 below.
Fig. 8 Process flow of ECG measurement
3) Schematic: Schematic circuit for ECG
measurement is shown in Fig 9.
Fig. 9 Schematic circuit of ECG detection
The RL, LA, RA connection are for electrode
placement. We used color coded ECG electrodes
where RL, LA and RA are attached to right leg, left
arm and right arm respectively.
IV. INTEGRATED SYSTEM
The integrated system combines all the
measurement units together. With this major
integration there comes some other implementations
that paved the way to the final model.
We implemented a system interface for the project.
The interface has been developed by Processing
software. It incorporates following features:
• A window for showing graphical change of
results over time. For special purpose two windows
are also used. Like implementing heartbeat
measurement one window shows the pulse variation
and a smaller one beside it shows inter beat interval
variation curve.
• Mode selection option for switching to different
measurement. It is set as pressing „p‟ key goes to
previous mode and pressing „n‟ key takes to next
mode.
• Each mode is presented as user understand the
state. Besides the name of the measurement a
graphical presentation is made to show on the
interface.
• Computer port selecting options for
microcontrollers.
• Snapshot of the window can be taken anytime
for storing the result curve by pressing „s‟ key.
• Measurement result is averaged after a defined
time and average value is shown as a continuous
manner.
• Styling of the interface can be modified through
coding for better look and feel. And other features or
controls can easily be integrated.
• The interface is flexible to change it for
measuring a single parameter or some parameters
based on choice by some modification. This can help
to meet varieties of need of patients.
Fig. 10 Block diagram of the final prototype
V. RESULT
After completion of the prototype, all the data
were measured on different subject to compare our
measurement with other conventional technique or
instruments.
For temperature measurement waterproof
DS18B20 sensor was used. In the GUI the temperaure
was plotted to show the change of temperature over
time. The Fig.11 shows the comparision of our
temperature measurement with conventional mercury
thermometer and digital thermometer.
Fig. 11 Comparison of different temperature
measurement

International Journal of Engineering Trends and Technology ( IJETT ) – Volume 61 Number 1 – July 2018
ISSN: 2231 – 5381 http://www.ijettjournal.org Page 35
The graph in figure 12 below compares the heart
rate of 4 different subjects measured using our heart
rate sensor and by conventional manual method. For
heart rate measurement the GUI shows the pulse
variation with a smaller window showing inter beat
interval variation curve.
Fig. 12 Comparison of different Heart Rate
measurement
The three lead ECG used in our prototype is not
similar to traditional twelve lead ECG. Our goal was
to implement a simple system that will be easy to use
but will provide an useful data for quick diagnosis.
The figure 13 below shows how the GUI shows the
ECG wave.
Fig. 13 ECG data on the GUI
VI. CONCLUSION
Rapid innovations in electronics and
biomedical field are revolutionizing the research
fields. These tacky devices are finding their path in
consumers market and making self-health monitoring
a common day‟s work for ordinary people. Our
designed module presents a new approach in health
monitoring. One of the main perk of our design is that,
the device is compact and integrable. It is very easy to
incorporate other forms of biomedical sensors with
our device. In future, this compact device will
incorporate sensors which will help to monitor and
record change in vital signs like- respiratory rate,
blood oxygen saturation, blood pressure etc. In near
future, compact heath monitoring devices like this
will revolutionize our everyday life.
REFERENCES
[1] J.G. Ebster, Encyclopedia of Medical and Devices and
Instrumentation, New York: Wiley and Sons, 2006.
[2] E. Atkins, “Fever: Its history, cause, and function”, The Yale
Journal of Biology and Medicine, 1982.
[3] E.F. DuBois, “The many different temperatures of the human
body and its parts. Western Journal of Surgery”, Western
Journal of Surgery, 1951.
[4] Philip A. Mackowiak, Fever: basic mechanisms and
management. Lippincott Williams & Wilkins, 1997.
[5] K. Lattawo, J. Britt and M. Dobal, “Agreement between
measures of pulmonary artery and tympanic temperatures”,
Research in Nursing & Health, 1995.
[6] Sund-Levander, Märtha, and Ewa Grodzinsky. "Assessment
of body temperature measurement options." British Journal of
Nursing vol. 22, pp: 882-888, 2013.
[7] “World Health Report 2002: Reducing risks, promoting
healthy life”, WHO, Switzerland, 2002
[8] Amer I Aladin, Seamus P Whelton, Mouaz H Al-Mallah,
Michael J Blaha, Steven J Keteyian, Stephen P Juraschek,
Jonathan Rubin, Clinton A Brawner, Erin D Michos,
"Relation of resting heart rate to risk for all-cause mortality
by gender after considering exercise capacity (the Henry Ford
exercise testing project)". The American Journal of
Cardiology, Vol. 114 (11),pp: 1701–06, 2014.
[9] Ake Hjalmarson, Elijabeth A. Gilpin, John Kjekshus,
Gregory Schieman, Pascal Nicod, Hartmut Henning, John
Ross Jr, "Influence of heart rate on mortality after acute
myocardial infarction", The American Journal of Cardiology,
vol. 65 (9), pp: 547–53, 1990.
[10] Davies MJ. Pathology of coronary atherosclerosis. Hurst‟s
The Heart, 10th ed, USA. International Edition McGraw-Hill
Medical Publishing Division, 2001.
[11] N. H. Mahmood, N. Uyop, N. Zulkarnain, F. K. C. Harun, M.
F. Kamarudin, and A. Linoby, "LED indicator for heart rate
monitoring system in sport application", IEEE 7th
International Colloquium, 2011.
[12] Duncan Macintyre, James Samsoondar, “Spectroscopic
method for total hemoglobin measurement”, US patent no.:
1586887.
[13] Y. G. Lim, K. K. Kim, & S. Park, “ECG measurement on a
chair without conductive contact,” in IEEE Transactions on
Biomedical Engineering, 53(5), pp: 956-959, 2006.
[14] R. J. Prineas, R. S. Crow, and Z. M. Zhang, The Minnesota
code manual of electrocardiographic findings, Springer
Science & Business Media, 2009.