International University, Vietnam National University –
HCMC
School of Biomedical Engineering
DESIGN 2B FINAL PROJECT REPORT
ECG Monitor
Name:
Instructor:
Dr. Tran Le Giang
TA1:
Nguyen Quoc Hung
TA2:
Truong Quoc Viet
Nguyễn Trung Sơn - BEBEIU20041
Dương Trung Kiên - BEBEIU20210
Huỳnh Nguyễn Minh Trí - BEBEIU20257
Semester: 2 - 2022
International University, Vietnam National University – HCMC | 2
Contents
I. Introduction ............................................................................................................................ 2
1. Problem/Issue/Motivation ................................................................................................ 3
2. Objective + Initial requirements ........................................................................................ 4
3. Related Works .................................................................................................................... 4
4. Idea introduction ............................................................................................................... 5
II. Design specifications .............................................................................................................. 6
III. Materials & Methods ............................................................................................................ 6
1. Materials ............................................................................................................................ 6
2. Block diagram..................................................................................................................... 6
3. Electrical Wiring/Schematics ............................................................................................. 7
4. Mechanical Design ............................................................................................................. 8
5. Firmware & Software ......................................................................................................... 8
IV. Testing Methodology ............................................................................................................ 9
V. Results & Discussions........................................................................................................... 10
1. Result ............................................................................................................................... 10
2. Discussion......................................................................................................................... 10
VI. Cost analysis........................................................................................................................ 11
1. Cost of product ................................................................................................................ 11
2. Existing commercial products .......................................................................................... 11
VII. Conclusion & Limitation & Future works........................................................................... 12
VIII. Task Division and Timeline ............................................................................................... 13
IX. References .......................................................................................................................... 13
Figures
Figure 1: WHO data ................................................................................................................... 3
Figure 2: Different components of a typical ECG signal [2] ..................................................... 4
Figure 3: IoT Based ECG Monitoring with AD8232 Sensor and ESP32 [3] ............................... 5
Figure 4: Block diagram ............................................................................................................. 6
Figure 5: Electrical schematic .................................................................................................... 7
Figure 6: 3D design and component ......................................................................................... 8
Figure 7: Data given by ECG simulator ..................................................................................... 9
Figure 8: Data given by human body ........................................................................................ 9
Figure 9: Final product (exterior) ............................................................................................ 10
Figure 10: Final product (interior) .......................................................................................... 10
International University, Vietnam National University – HCMC | 3
I. Introduction
1. Problem/Issue/Motivation
World Health Organization (WHO) data stated that heart diseases cause about 31% of
deaths in Vietnam. In Vietnam, devices used to monitor the heart’s activity or
electrocardiogram (ECG) are mostly owned by big hospitals.
Figure 1: WHO data
According to newly released research by the Asia Pacific Observatory on Public Health
Systems Policies, each main Public Health Center (PHC) has more than 6000 patients - which
sometimes consists of no more than three rooms with extremely basic healthcare tools and
setup. There is just one hospital bed per 1000 patients in each of these PHCs [1], indicating
the country's suffering healthcare system's lack of infrastructure and facilities. Nonetheless,
the country's battle to deal with fatalities and illnesses continues — noncommunicable
disease mortality rates remain on the increase. Cardiovascular diseases (CVDs) account for
more than 26% of all fatalities in 2010 [1]. Fast-paced lives, harmful activities, and poor dietary
habits are all contributing to an increase in CVDs. Although CVD is relatively common – and is
especially prevalent in rural areas - present healthcare systems are unable to meet the rising
demand.
Electrocardiogram (ECG) devices are a vital diagnostic tool used to detect a wide range of
cardiovascular disorders. Typical ECG equipment gives a graphical picture of the activity and
rhythm of the heart. It captures the electrical activity of the heart to generate an
electrocardiograph, which when evaluated by a clinician may lead to an accurate diagnosis of
a CVD. An ECG may be used to identify diseases such as arrhythmia, myocardial infarction, or
tissue damage; it can also be used to monitor the effects of medicines on the heart,
pacemaker performance, or post-operative conditions. Despite its significance and frequency
of usage, the device's mobility and cost remained on the upper end of the affordability scale.
Despite an increase in the number of patients suffering from cardiovascular disorders in
developing nations, the cost of ECG equipment has remained expensive, and their mobility
has been limited. The picture below depicts the phases of the cardiac blood pumping cycle
and the accompanying ECG signal components for a typical ECG signal.
International University, Vietnam National University – HCMC | 4
Figure 2: Different components of a typical ECG signal [2]
2. Objective + Initial requirements
This project envisions a low-cost, portable ECG monitor that gains access to any device and
platform with the same Wi-Fi connection to obtain the result over a local website. The entire
system is comprised of an analog circuit and a processing unit. Bioelectric-potential sensors
or the more well recognized AgCl electrodes are used to detect the signal from the body. An
analog circuit retrieves and amplifies the signals received from the body to enable extra
processing. Furthermore, a critical component of the processing unit is the ability for users to
study the signal and facilitate more precise output signal filtering through the web. Since the
product is portable, the power supply source should be compact. The electrical source should
be provided by a mini-USB cable directly to the gate of the ESP32 microcontroller. Besides a
rechargeable battery is also considered, the battery is charged by a Type-C USB cable which
is one of the most ubiquitous types of cable these days. The design employed is functional,
inexpensive, and simple enough that it may be readily replicated. Besides, the display module
should be excluded to cut down on the overall cost since the result is obtained via a local
website on any platforms or devices with the same internet connection.
3. Related Works
•
IoT Based ECG Monitoring with AD8232 Sensor and ESP32: [3]
This is an IoT Based ECG Monitoring with AD8232 ECG Sensor & ESP32 using an online IoT
platform called Ubidots, and through parameters like API Key or Token, the data is sent to the
ECG graph to the cloud using MQTT Broker.
The drawbacks of this interpretation are that the Ubidots platform data presented is not as
smooth as our prototype, and it does not have a quick rate response and thus does not
acquire the simultaneousness criteria.
International University, Vietnam National University – HCMC | 5
Figure 3: IoT Based ECG Monitoring with AD8232 Sensor and ESP32 [3]
•
Blue ECG with Bluetooth feature integrated with smartphone: [4]
The main components of the Blue ECG device can be split into three components: (1) Arduino
UNO, (2) AD8232 set, and (3) HC-05 Bluetooth module. And the HC-05 Bluetooth module will
send the cardiac data collected from amplified and filtered analog signals in Arduino to
Bluetooth.
The restriction in detection range due to the use of Bluetooth (about 10m) in this approach
has proved to be a downside compared to our prototype, which can maintain a real-time
measurement in a large area as long as a Wi-Fi connection remains.
4. Idea introduction
In this project, our group will design and fabricate a low-cost portable ECG monitor. Our ECG
monitoring system consists of interfacing the AD8232 ECG sensor with ESP32 to show the
graph over a webserver.
The overview of this method is connecting the AD8232 Sensor with ESP32 Wi-Fi and Bluetooth
development board to get the ECG graph in real-time over a local website.
Our main hardware components should be ESP32, ECG Module (AD8232), ECG electrodes,
ECG electrode connector switch, and power supply (Lipo battery 3.7V). Since the Lipo battery
is rechargeable, a charging board with 5V output should be considered.
About the website, we intended to use the WebSocket protocol instead of other ways such
as MQTT or HTTP. As a result, the coding parts consist of the embedded code and the website
code.
When it comes to the testing, we perform two trials as the reference data. The first case is
with the ECG simulator. The second one is the human body with three limb electrodes applied
as a form of Einthoven’s triangle.
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II. Design specifications
Weight
103 grams
Size
55x67x50mm
Power
Lipo battery 3.7V
Charging method
Type-C USB gate
Charging time
Approximately 1 hour
Table 1. Design specifications
III. Materials & Methods
1. Materials
No.
Component
Quantity
Purchased locations
1.
ESP32
1
epcb.vn
2.
ECG module (AD8232)
1
epcb.vn
3.
Lipo battery 3.7V
1
Hshop.vn
4.
electrodes
3
epcb.vn
5
Type-C gate charging circuit
1
epcb.vn
6.
Switch
1
Nhat Tao market
Table 2: Material list
2. Block diagram
Figure 4: Block diagram
Our project includes three main parts: the microcontroller, the ECG module and a cover.
The microcontroller: Powered by the Lipo battery, received ECG signal from the ECG
module and transferred it into the local website. The ESP32 should be considered since we
want our system to be compact and easy to deploy, also the result is displayed on a local
International University, Vietnam National University – HCMC | 7
website so the ESP32 is a good choice with faster Wi-Fi compared to other microcontrollers
such as ESP8266.
The ECG module: The AD8232 receives the signal and amplifies it so the ECG result
could be obtained and the module also lightweight and compact. However, the AD8232 does
not consist of a signal filter.
The Cover: The light, small and compact cover, made by 3D printing. We intended to
use PLA plastic as the material for the cover. Although 3D printing may be quite expensive,
with the modest design, the cost for the cover is affordable (90k), which meets our initial
requirement: cheap
3. Electrical Wiring/Schematics
Figure 5: Electrical schematic
•
•
Board label
Pin function
ESP32 Connection
GND
Ground
GND
3.3V
3.3V Power Supply
3.3V
OUTPUT
Output Signal
A0
+5V (charging board)
Voltage supply
VIN
-5V (charging board)
Voltage supply
GND
Charging and power supply: For the power supply, the +5V and -5V pin of the
charging board are connected to the ESP32 at the VIN pin and GND pin, respectively.
The charging board also connected with the Lipo 3.7V battery, with the BAT+ pin is
connected to positive wire of the battery and the BAT – pin linked to the negative
one that makes the battery become chargeable.
Receiving and transmitting ECG signal: There are three pins of the ECG module that
need connecting to work properly. Firstly, the GND of the ECG module is the ground
and is connected to the GND pin of the ESP 32. Secondly, the 3.3V pin of ECG module
is where it receives power, which is supplied from the ESP 32. Finally, the OUTPUT pin,
which is in charge of transmitting ECG signal to the ESP, is linked to the A0 pin.
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4. Mechanical Design
Figure 6: 3D design and component
Component
Lid
ESP32
AD8232
Cover
Function
Provide a canopy for the cover and shelter the components inside
With delicate positioning on the inner side face of the cover to ensure
compactness and efficiency, it interfaces AD8232 sensor to show the
graph on the local webserver
ECG module to record the ECG signal
Small, light cover to ensure the compacity of the device
Type-C gate
charging circuit
Makes the Lipo battery become chargeable
Battery holder
Since the Lipo battery is hot when charging, the battery holder
separates it from other components.
Switch
Turn on/off the prototype
Table 3: Mechanical design description
5. Firmware & Software
In this project, the WebSocket protocol is implemented instead of other protocols such as
HTTP or MQTT. It is because when you require frequent two-way communication between
devices, the WebSocket protocol is an excellent alternative to HTTP. When two devices
interact using WebSocket, a network connection is maintained between them, allowing for
the efficient transmission of short messages such as delivering a sensor reading or an order
to switch on a light. Only the client may make a request with HTTP, and the server always
answers. WebSocket, on the other hand, is a peer-to-peer protocol that allows both devices
to send and receive messages. It's often a suitable option for IoT items that need to deliver a
large number of tiny messages. However, since it maintains a connection between two
devices, it often consumes more memory than HTTP. As a result, when applying the
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WebSocket, the local website does not require refreshment by pressing F5 to obtain the new
data as the data is automatically updated.
IV. Testing Methodology
The prototype's weight is measured via a balance after the prototype is completed. We
measure the size of the cover and the lid by adjusting the size parameters while designing in
Fusion 360. The working distance of the prototype is tested and estimated through various
practical measurements. In addition, the accuracy of the prototype is assessed over trials of
code implementation and webserver observation. When continuous operation, the battery
could last long, approximately 9 to 14 hours.
•
First case: Data given by the ECG simulator
Figure 7: Data given by ECG simulator
•
Second case: electrodes placed on right and left upper chest at the Pectoralis Major
area and left hip (Einthoven’s triangle).
Figure 8: Data given by human body
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V. Results & Discussions
1. Result
Figure 9: Final product (exterior)
Via Blynk
Figure 10: Final product (interior)
Via Webserver
At first, we intended to use the Blynk application to display our results. However, the Chart
function in Blynk is not designed for the analog signal such as the ECG signal since with a 40Hz
or higher signal, the Blynk server will be flooded. Developing a web server is a good alternative
as the graph settings could be adjusted, such as max data points, so everything is under
control.
2. Discussion
Trial with ECG Simulator as reference data, showing a healthy heart wave (Normal
Sinus Rhythm). The frequency of heartbeats within 60 seconds time period. A healthy heart
rate is 60 - 100 BPM while in a resting state. All the components of the signal PQRST are
available and easily distinguishable. However, it is still noisy due to the DC power supply. Since
the DC supply is not pure, which might have a frequency of 1.2 Hz represents the noise.
Trial with the human body as the reference data, the subjects do not have any
unhealthy heart conditions. The hardest hurdle was to eliminate the external noises during
the implementation process. Besides the power supply noise, there are also several types of
other noise signals, such as baseline wander (caused due to improper electrodes (electrode-
International University, Vietnam National University – HCMC | 11
skin impedance), patient’s movement and breathing (respiration). The frequency content of
the baseline wander is in the range of 0.5 Hz); muscle noise (50/60 Hz interference), Electrode
Motion Artifacts (occur mainly in the range from 1 to 10 Hz).
Noises occur since the hardware does not contain a high-pass filtering option, which
is a limitation of the AD8232.
VI. Cost analysis
1. Cost of product
At the beginning of the project, we intended to use 18650 batteries as the power supply for
our device. However, we switched to the Lipo battery 3.7V 500mAh as it is more efficient and
smaller than the 18650 one, but the Lipo battery’s cost is higher. As a result, we could possess
a product that is as compact as possible, and the price does not change much since the
exterior design’s cost is reduced because of the compactness of the Lipo battery. The Lipo
battery is rechargeable, so it has to be attached to a charging board, but 3.7V is not enough
to supply the ESP32 microcontroller, so the charging board ought to have a 5V output that
acts as the input voltage for the ESP32. Instead of using the TP4056 lithium battery charge
controller and a booster circuit, applying the 5V output charging board is less complex and
cheaper. The table below (Table) shows all the materials and their prices in our final product,
which gives the cost of approximately 500,000 VND in total.
Item
Unit Required
Unit Price
Total
ESP 32
1
180k
180k
AD8232
1
150k
150k
Type-C charger board
1
20k
20k
Switch
1
1k
1k
Lipo battery 3.7V
1
35k
35k
Exterior design
1
90k
90k
Total
476k
Table 4: List of materials used and total cost of the final product
2. Existing commercial products
Nihon Kohden Model
Cyka Blyat
Spandan 4.0 Portable
ECG 2150
12-lead ECG device
Portable ECG machine
• The machine has a
• Allows instant heart
• Fast in setting up
monochrome liquid
monitoring
• Users may find it
crystal display with a • Comes with intelligent
friendly and easy to
4.8-inch-wide back
Advantages
ECG technology
use
light designed to help
• Advanced prediction
• Low cost
observe 12 ECG leads
of heart defects
• Fast charging time
Features
International University, Vietnam National University – HCMC | 12
at the same time
easily
• Classifies 12 different
abnormal conditions
• Monitor the ECG
• Advanced graphic
before recording,
representation
helping to reduce the • Works fast and
need to repeat the
efficiently
recording process
• Expensive
• Limit the number of
connected devices
• Connecting to LAN is
Limitations
Cost
Mass
• Only for Android
complicated and
smartphones
requires well-trained
physicians to perform
• Need a power plug to
use
VND 35.000.000
(USD1500)
1700g
• Results could be
obtained on any
devices with Wi-Fi
connection
• Not really high
resolution
• Do not give
prediction of heart
defects
• Do not save data or
record
VND 2.400.000
(USD103)
200g
VND 476k (USD 22)
103g
Currently, ECG equipment costs about VND 35.000.000 (USD 1500) for each item, which might
be too expensive for most people in the underdeveloped world. As a result, the majority of
the components employed in this design are low-cost yet effective. As a consequence, the
prototype could be kept around VND 500 (USD 22), making it not only incredibly helpful but
also simply accessible to anyone.
VII. Conclusion & Limitation & Future works
The device has proved to be compact, and it holds an instant rate of cardiac data transferred
as a graph on the webserver, which yields the advantage of real-time measurement. Our
prototype also possesses a humble production cost and can thus be sold at under 1 million
VND (USD 44) for 50% profit. However, there are still some trivial signaling noises since we
have not applied the additional filtering options, and the device does not save data for
individuals.
•
•
•
•
Applying hardware filtering options and using computational signal processing to
obtain the best output for the ECG signal.
The result is displayed via the internet.
Data could be saved and printed out; auto-heartrate detection.
Applying Machine Learning and Deep Learning to diagnosing cardiovascular diseases
such as myocardial infraction
Compared with other commercial products, our device shows the advantages of being
compact, lightweight, easy to use, and also still gives quite distinguishable magnification and
resolution that can illuminate the intervals. Its cost is much cheaper than almost all other ECG
machines on the market. However, the resolution should be improved for better results as
the signal is still noisy.
International University, Vietnam National University – HCMC | 13
A decent and portable ECG monitor, in our opinion, is one that can be readily transported and
utilized to deliver or permit fast diagnosis during an emergency. Although direct product
comparison is outside the scope of this study, the quality of the T and QRS complicated graph
form it creates is noticeably better than before. The ECG machine presented here would be a
first step in developing a low-cost, low-maintenance healthcare module that can be quickly
copied to offer service in distant places, during catastrophes, or in emergencies.
VIII. Task Division and Timeline
IX. References
[1] Chong K.L, Holden D & Olin T, " Analogue Electronics: Heart Monitor " in IEEEXplore
www.ieee.com. Retrieved March, 18, 2018.
[2] PrepGenie, The graphical representation of the electrocardiogram. 2017. Available:
https://prepgenie.com.au/gamsat/importance-ofgraphs-and-data-tables-in-gamsat-biologyquestions/. [Accessed: 12-Mar-2018].
[3] Admin, IoT Based ECG Monitoring with AD8232 Sensor and ESP32. 2020. Available:
https://how2electronics.com/iot-ecg-monitoring-ad8232-sensoresp32/?fbclid=IwAR3qXk5YbVEcyC6YF44BD-TeT71vBR2l-9q2UBYIowinU9c474G-27dRDtU.
[Accessed: 17-May-2020].
[4] William Jerrel Iskandar, Ibnu Roihan, and Raldi Artono Koestoer , "Blue
electrocardiogram (ECG): ECG with bluetooth feature integrated with smartphone", AIP
Conference Proceedings 2344, 050003 (2021) https://doi.org/10.1063/5.0047431
International University, Vietnam National University – HCMC | 14
DESIGN 2B
FINAL REPORT RUBRIC
No.
Items
Max pts
1
Problem & Related works
2
Objective & Initial requirements
5 (ABET)
3
Design specifications
10 (ABET)
4
Block diagram
10
5
Materials
5
6
Electrical Schematic
10
7
Mechanical Design
10
8
Firmware & Software
10
9
Testing
10
10
Cost analysis
5
11
Conclusion & Limitation & Future works
10
12
Task division & timeline
Total
10
5 (ABET)
100