DEVELOPMENT OF WIRELESS
PHOTOPLETHYSMOGRAPH BASED HEALTH MONITORING SYSTEM
BY
NUR IZZATI ZAINAL
A thesis submitted in fulfilment of the requirement for the degree of Master of Science
(Communication Engineering)
Kulliyyah of Engineering
International Islamic University Malaysia
JUNE 2017
ii
ABSTRACT
The demand for use in medical application of enhancing technology is gradually on the rise every year. All crucial devices currently used in hospitals for health-monitoring services, are wired. The use of wired equipment for applications of electrocardiogram (ECG) machine or photoplethysmography (PPG) may be cumbersome due to physical movement in ambulatory vehicles. The PPG embedded with wireless features make the best non-invasive alternative by being simple and low cost device. This thesis thus presents the development of wireless PPG based health monitoring system. The main objectives of this research are focusing on both establishing the hardware and software for a comprehensive overall system. The further analysis will be done based on full hardware and software architecture for developing and designing a complete device for wireless PPG based health monitoring system. The proposed methodology is based on the hardware block diagram, component selection, calibration and system integration.
The integration of electronic components of microcontroller, PPG sensor, Bluetooth module and display module will make a complete prototype of the proposed system. A Graphical User Interface (GUI) is developed in Matlab software to capture and record the transmitted PPG signal from the PPG sensor. In this research, two prototypes are constructed for health monitoring system. The second prototype is the enhancement version of the first prototype in term of wiring, display and design. The results show that both prototypes developed for wireless transmission are performing appropriately.
The range for of the proposed system with Bluetooth module can go up to sixteen meters for successful transmission of PPG signal. As a proof of concept, Heart Beat Count is measured from six subjects in sitting and standing positions. The PPG signals collected are also being analyzed in time domain and frequency domain using Kubios HRV software. The outcome shows that PPG signals is more stable when the person is in rest condition. With the positive results that has been obtained from this research, wireless PPG based health monitoring system is bound to be with convincing potential for future medical technology development.
iii
ثحبلا ةصلاخ
ABSTRACT IN ARABICABSTRACT IN ARABIC
دادزي بلطلا لا تاقيبطتلا مادختسا ىلع ماع لك في اييجردت ايجولونكتلارود زيزعتل ةيبط
. ةمهلما ةزهجلأا عيجم ،نأ
يفشتسلما في ايلاح ةمدختسلما يه ،ةيحصلا تامدلخا ةبقارلم تا
جا ةزه تلل ةيكلسلا تادعلما مادختسا .ةيكلسلا تاقيبط
ةيليلحتلا ةروصلا وا هيئبارهكلا هيللاا
(PPG)
لا .ةلقنتلما تابكرلما في ةيدسلجا ةكرلحا ببسب هليقث نوكت دق
(PPG)
عتج تيلا ةيكلسلالا تازيملما عم أزجتي لا اءزج ةليدبلا ةيزاغلا يرغ نم لضفأ اهل
لياتلباو .نمثلا ةليلق اتهزهجاو ةطيسب انهوك
هذه نإف لا ا مدقت ثحب يكلسلالا روطتل
(PPG)
دمتعي ثحبلا اذله يساسلاا فدلها .يحصلا دصرلا ماظن يلع نيبلما
ىلع ءانب لماش ماظن متكلما ةزهجلأا ساسأ ىلع ليلاحتلا نم ديزم ءارجإ متيسو .اتهايمجربو ةزهجلأل
ةيسدنلها اتهايمجربو ةل
ةيكلسلا لماك زاهج ميمصتو ريوطتل
(PPG)
صلا دصرلا ماظن يلع نيبم تستو .يح
يلع ةحترقلما ةيجهنلما دن ططمخ
ماظنلا لماكتو ةرياعلما ،تناوكلما رايتخا ،ةزهجلأا مد .
،مكحتلما عم ةينوتركللإا تناوكلما ج م
رعشتس
(PPG)
ةدحو ،
مدختسلما موسرلا ةهجاو .حترقلما ماظنلل لاماك ايلوأ اجذونم كلذ لعتج ضرعو ثوتولب
(GUI)
في اهريوطت تم تايمجرب
لاثالما تاراشلاا ليجستو طاقتللا ب
(PPG)
نم ةلسرلما م
رعشتس
(PPG)
ماظنل ينجذونم ءاشنإ تم ،ثحبلا اذه في .
جئاتنلا ترهظأ .ميمصتلاو ضرعلا ،كلاسلأا ثيح نم لولأا جذومنلل ةنسلمحا ةخسنلا وه نياثلا جذومنلا .يحصلا ةبقارلما سلالا لاسرلإل اهمريوطت تم نيذللا ينجذومنلا نم لاك نأ يكل
نيادؤي امهلمع ماظنلل يطغلما قاطنلا .بسانم لكشب
لقنل اترم رشع ةتس لىإ لصت نأ نكيم ثوتولبلا ةدحو عم حترقلما تاراشا
لا حانج
(PPG)
نهرب تتمو . ة
ساقب ،كلذ
صاخشا ةتس نم بلقلا تبارض تاضبن با
اضو لاو سوللجا لثم هفلتمخ ع و
وق ف لا تاراشا .
(PPG)
اهعمتج تم تيلا
هليلتحو سيبوك تايمحرب مادختسبا ددترلا قاطنو نيمزلا لالمجا في اضيأ ا
(HRV)
لا تاراشا نأ جئاتنلا ترهظاو .
(PPG)
.ةحارلا ةلاح في صخشلا نوكي امدنع ارارقتسا رثكأ نوكت نم
،ثحبلا اذه نم اهيلع لوصلحا تم تيلا ةيبايجلإا جئاتنلا
نكيم يكلسلالا ماظن نا لوقلا
(PPG)
لا يلع نيبلما ةيبط ايجولونكت ريوطتل ةعنقم تنااكمإ وذ ماظن وه يحصلادصر
لبقتسلما في
.
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APPROVAL PAGE
I certify that I have supervised and read this study and that in my opinion, it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a thesis for the degree of Master of Science (Communication Engineering)
………..
Sheroz Khan Supervisor
………..
Mohamed Hadi Habaebi Co-Supervisor
I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a thesis for the degree of Master of Science (Communication Engineering)
………..
Hasmah Mansor Internal Examiner
………..
Anis Nurashikin Nordin Internal Examiner
This thesis was submitted to the Department of Electrical and Computer Engineering and is accepted as a fulfilment of the requirement for the degree of Master of Science (Communication Engineering)
………..
Anis Nurashikin Nordin Head, Department of Electrical and Computer Engineering
This thesis was submitted to the Kulliyyah of Engineering and is accepted as a fulfilment of the requirement for the degree of Master of Science (Communication Engineering)
………..
Erry Yulian Triblas Adesta Dean, Kulliyyah of Engineering
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DECLARATION
I hereby declare that this dissertation is the result of my own investigations, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institutions.
Nur Izzati Zainal
Signature ... Date ...
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INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA
DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH
DEVELOPMENT OF WIRELESS PHOTOPLETHYSMOGRAPH BASED HEALTH MONITORING SYSTEM
I declare that the copyright holders of this dissertation are jointly owned by the student and IIUM.
Copyright © 2017 Nur Izzati Zainal and International Islamic University Malaysia. All rights reserved.
No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below
1. Any material contained in or derived from this unpublished research may be used by others in their writing with due acknowledgement.
2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purposes.
3. The IIUM library will have the right to make, store in a retrieved system and supply copies of this unpublished research if requested by other universities and research libraries.
Affirmed by Nur Izzati Zainal
……..……….. ………..
Signature Date
vii
To my lovely husband, who gave me endless love, trust, constant encouragement over the year.
To my family, for their patience, support, love, and for enduring the ups and downs during the completion of this thesis.
I dedicate this research work to them.
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ACKNOWLEDGEMENTS
In The Name of Allah, The Most Beneficent, The Most Merciful
First and for most, praise to Allah for His blessings and guidance which enable me to complete this report.
I would like to express my deepest gratitude to my supervisor, Dr Sheroz Khan for guiding, teaching and supervising me in this project. He had thought me to become a good researcher in this field, as well as providing and guiding me to the right path in doing the project.
Besides that, I would like to dedicate this work to my dear husband, Mohd Zuhaili Mohd Rodzi, my father, Zainal Mohd Roslan, my mother, Mohibah Jamin and my family, who kept supporting, motivating and encouraging me during my research in master degree. They had inspired me to keep on exploring and investigating new things for knowledge.
Finally, special thanks to all my fellow friends for their generosity in sharing and giving their opinion during my project progression until the report has been successfully being completed.
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TABLE OF CONTENTS
Abstract ... ii
Abstract in Arabic ... iii
Approval Page ... iv
Declaration ... v
Copyright Page ... vi
Acknowledgements ... vii
Table of Contents ... ix
List of Tables ... xi
List of Figures ... xii
List of Abbreviation ... xv
CHAPTER ONE: INTRODUCTION ... 1
1.1 Background of the Study ... 1
1.2 Problem Statement ... 4
1.3 Research Objectives... 5
1.4 Significance of the Study ... 5
1.5 Scope of Research... 6
1.6 Expected Outcome and Contributions ... 7
1.7 Thesis Organization ... 7
CHAPTER TWO: LITERATURE REVIEW ... 8
2.1 Introduction... 8
2.2 Overview of PPG and Wireless Technology ... 8
2.2.1 Overview of PPG ... 9
2.2.2 Wireless Transmission System ... 15
2.3 Related Works on PPG Device ... 17
2.4 Related Works on Health Monitoring System ... 22
2.5 Related Works on PPG based Heart Rate Variability (HRV) ... 23
2.6 Critical Analysis of Related Research Works ... 24
2.7 Bluetooth based Wireless Transmission System ... 26
2.8 Open Research Issue ... 27
2.9 Summary ... 27
CHAPTER THREE: RESEARCH METHODOLOGY ... 28
3.1 Introduction... 28
3.2 Development of Hardware Block Diagram ... 30
3.3 Component Selection ... 31
3.3.1 Microcontroller ... 32
3.3.2 PPG Sensor ... 33
3.3.3 Bluetooth Module ... 34
3.3.4 Display Module ... 35
3.4 Design and Fabrication of Main Controller Board ... 35
3.4.1 Circuit Block Diagram ... 35
3.4.2 PCB Design ... 36
3.5 Component Calibration ... 37
x
3.5.1 PPG Sensor ... 37
3.5.2 Bluetooth Module ... 41
3.6 Hardware Development ... 42
3.7 Software Development ... 44
3.7.1 Software Development (Transmitter) ... 44
3.7.2 Software Development (Receiver) ... 45
3.7.1 Mobile Application ... 46
3.8 System Integration ... 47
3.8.1 First Prototype ... 47
3.8.2 Second Prototype ... 48
3.8.3 Prototype Specification ... 50
3.9 The Acquisition of PPG Signal... 50
3.9.1 Signal Acquisition ... 51
3.9.2 Pre-processing ... 53
3.9.3 Feature Extraction ... 54
3.9.4 Classification ... 54
3.10 Summary ... 55
CHAPTER FOUR: RESULT ANALYSIS ... 56
4.1 Introduction... 56
4.2 PPG Sensors Testing and Experimentation ... 56
4.3 GUI at the Receiver ... 60
4.3.1 GUI of Real-time PPG Data Acquisition ... 61
4.4 PPG Data Transmission Evaluation in term of Transmission Distance ... 61
4.5 Transmission Testing ... 62
4.5.1 Result Analysis of PPG Signal Transmission ... 62
4.6 PPG Signal Result Evaluation ... 63
4.7 Comparison of Heart Rate (Heart Beat Count) of PPG signal ... 66
4.8 HRV Analysis of PPG Signal ... 68
4.9 Time Domain Analysis ... 69
4.10 Frequency Domain Analysis... 71
4.11 Summary ... 72
CHAPTER FIVE: CONCLUSION AND FUTURE WORK ... 75
5.1 Conclusion ... 75
5.2 Future Work ... 77
LIST OF PUBLICATION ... 79
REFERENCES ... 80
APPENDIX I ... 83
APPENDIX II ... 85
APPENDIX III ... 91
APPENDIX IV ... 92
APPENDIX V ... 93
xi
LIST OF TABLES
Table No. Page No.
Table 2.1 Comparison of Related Works on PPG Device 25
Table 3.1: Component Selection Parameter 32
Table 3.2 Comparison Between First and Second Prototype 49
Table 3.3 Specification of the Final Prototype 50
Table 4.1 Data Collected from 6 Subjects 64
Table 4.2 Heart Rate Measurement of Subject A 67
Table 4.3 𝑅𝑅 and SDRR for 6 Subjects 71
xii
LIST OF FIGURES
Figure No. Page No.
Figure 1.1 - California Biomedical Industry Report on Top Biomedical Employment
(Gillenwater et al., 2014) 2
Figure 1.2 - Placement Positions of Three Sets Electrodes (Cao et al., 2011) 4 Figure 2.1 - (a) Water Type Plethysmogram (The Great Soviet Encyclopedia, n.d.), (b) Air type Plethysmogram (Ellis, 2000), (c) Strain Gauge Type Plethysmogram (Poblete, 2007), (d) Impedance Type Plethysmogram (Malloy et al., 1990) 10
Figure 2.2 - Basic PPG Device 11
Figure 2.3 - PPG Probes (a) Transillumination Mode (b) Reflection Mode (Bernardi et
al., 1994) 12
Figure 2.4 - A Typical Waveform of the PPG and Its Characteristic Parameters
(Daimiwal et al., 2014) 12
Figure 2.5 - Collision of Light Photon with Red Blood Cell (Bernardi et al., 1994) 13 Figure 2.6 - Schematic of the PPG Signal Showing the AC and DC Signals (Akl et al.,
2014) 14
Figure 2.7 - Wireless Transmission between Device and Mobile Phone and 15 Figure 2.8 - Data Acquisition Method for Wireless Transmission by (a) Rajeshkumar et
al. and (b) Sumathi et al. 16
Figure 2.9 - Absorption spectra of Hemoglobin and Deoxyhemoglobin (Reddy et al.,
2009) 18
Figure 2.10 - Diagram of the Multimode PPG Finger Probe Identifying the Configuration (Placement) of All Optical Devices (LEDs and Photodiodes) (Shafique et al., 2012) 19
Figure 2.11 - PPG Signal Process (Lin et al., 2011) 20
Figure 2.12 - Infrared Sensor TCRT1000 (Vishay Semiconductor, 2009) 21 Figure 2.13 - Illustration of the e-Health Monitoring Architecture (Mukherjee et al.,
2014) 23
Figure 2.14 - (a) TCRT5000 (Vishay Semiconductor, 2009) (b) TCRT1000 (Vishay Semiconductor, 2009) and (c) HRM2511e (Embedded-lab, 2013) 26
Figure 3.1 - Flowchart of the Research 29
Figure 3.2 - Proposed Research Methodology 30
xiii
Figure 3.3 - Hardware Block Diagram 31
Figure 3.4 - ATmega 328p Microcontroller and Its Pinout 33
Figure 3.5 - (a) TCRT5000 (Vishay Semiconductor, 2009) (b) TCRT1000 (Vishay Semiconductor, 2009) and (c) HRM2511e (Embedded-lab, 2013) 33 Figure 3.6 - (a) HC-05 Bluetooth Module (Singh et al., 2016; Nandkishor et al., 2014) (b)
HC-06 Bluetooth Module (Subbu et al., 2014) 34
Figure 3.7 - (a) Liquid Crystal Display (b) Nextion TFT Display 35
Figure 3.8 - Circuit Block Diagram 36
Figure 3.9 - PCB Design for Main Controller Board 37
Figure 3.10 - HRM 2511e and Filtering Circuit 38
Figure 3.11 - Screenshot from Computer based Oscilloscope Software for Raw PPG
Signal 39
Figure 3.12 - Screenshot from Computer based Oscilloscope Software for First Filtering
Stage 39
Figure 3.13 - Screenshot from Computer based Oscilloscope Software for Second
Filtering Stage 40
Figure 3.14 - Screenshot from Computer based Oscilloscope Software for Filtered PPG
Signal 40
Figure 3.15 - Experimental Setup for Acquiring PPG Signal 41 Figure 3.16 - HC-05 Module Connection with Computer Via USB to TTL Adapter 42
Figure 3.17 - Connection Diagram 42
Figure 3.18 - Complete Prototype Wiring (First Version) 43
Figure 3.19 - Complete Prototype Wiring (Second Version) 44
Figure 3.20- Screenshot of GUI Application for Wireless PPG Signal Acquisition 45
Figure 3.21 - Screenshot of ezplotter apps 47
Figure 3.22 - An Operating Prototype (First Version) 48
Figure 3.23 - An Operating Prototype (Second Version) 49
Figure 3.24 - HBC Measurement Approach 51
Figure 3.25 - Software Flowchart 52
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Figure 3.26 - Software GUI Display 52
Figure 3.27 - Pre-processing Technique 53
Figure 3.28 - HBC Flowchart Calculation 54
Figure 4.1 - Red LED based PPG Sensor Circuit 57
Figure 4.2 - Red LED based PPG Sensor Circuit Graph 57
Figure 4.3 - IR LED (TCRT 1000) 58
Figure 4.4 - IR LED (TCRT 1000) based PPG Sensor Circuit 58
Figure 4.5 - IR LED (TCRT 1000) based PPG Sensor Circuit Graph 59
Figure 4.6 - IR LED (HRM 2511e) based PPG Sensor Circuit 60
Figure 4.7 - IR LED (HRM 2511e) based PPG Sensor Circuit Graph 60 Figure 4.8 - GUI for Wireless PPG Signal Acquisition for Health Monitoring Application
61
Figure 4.9 - Multipath Propagation Phenomenon 62
Figure 4.10 - Experimentation Setup for Transmission Testing 62 Figure 4.11 - Screenshot of Mobile Application and PPG Device at 16 Meters
Transmission Distance 63
Figure 4.12 - PPG Signal of 6 Subject (Sitting and Standing Position) 65 Figure 4.13 - Automatic Blood Pressure Monitor (HuBDIC) (Medical Expo. Source from: http://www.medicalexpo.com/prod/hubdic/product-68774-750670.html) 66 Figure 4.14 – PPG Signal of Subject A in Sitting Position 67 Figure 4.15 - PPG Signal of Subject A in Standing Position 67
Figure 4.16 - A Constant RR Interval of PPG Signal 68
Figure 4.17 - Real PPG Signal 69
Figure 4.18 - PPG Signal of All 6 Subjects in Time Domain 70 Figure 4.19 - PPG Signal of All 6 Subjects in Frequency Domain 72 Figure 4.20 - (a) Proposed PPG Device (b) A Subject Tested the Proposed PPG Device
(Ghamari et al, 2016) 73
Figure 4.21 - Experimental Setup and Measurement Screen (Vasile et al., 2015) 74
xv
LIST OF ABBREVIATION
PPG Photoplethysmograph ECG Electrocardiogram EEG Electroencephalogram EMG Electromyography GUI Graphical User Interface HbO2 oxygenated haemoglobin
Hb deoxyhaemoglobin
SpO2 blood oxygen saturation
RF radio frequency
HRV Heart Rate Variability PCB Printed Circuit Board LED Light Emitting Diode
PPGV Photoplethysmograph Variability PTT Pulse Transit Time
PCG Phonocardiography SAR Specific Absorption Rate
IDE Integrated Development Environment LCD Liquid Crystal Display
TFT Thin-film Transistor USB Universal Serial Bus THM Through hole mounted SMT Surface mounted technology
1
CHAPTER ONE INTRODUCTION
1.1 BACKGROUND OF THE STUDY
According to the report done by California biomedical industry, top biomedical employment including academic research, biopharmaceuticals, medical devices, research and development and wholesale trade had undergone an average increment of 1.4 % from 2012 to 2013 (Gillenwater et al., 2014) as illustrated in Figure 1.1. This report shows that biomedical industry demand has kept on increasing over the year.
Commonly used applications in the biomedical field consist of health-monitoring devices. A quick review on how health monitoring devices have been depicted in a lot of applications over the years can explain how crucial is this application in the medical field. Health monitoring devices involve a lot of biomedical equipment items such as electrocardiogram (ECG), electromyogram (EMG), electroencephalography (EEG) and others. It is important to understand the system which integrates these numerous equipment items used in assisting user in obtaining important data related to human physiology. Therefore, in this research, a PPG non-invasive device for health monitoring system is developed for clinical applications.
2
Figure 1.1 - California Biomedical Industry Report on Top Biomedical Employment (Gillenwater et al., 2014)
The demand for biomedical technology capture the industry market attention. In fact, there are many improvements that can be made in the currently used health monitoring system. Furthermore, providing another medical health sensor as an alternative among the commonly used medical sensor like ECG and EMG may give and open new idea among researchers and doctors to explore more in its usage in medical field. One of such medical sensors, called photoplethysmograph (PPG), capable of providing non-invasively the oxygen saturation information of blood of a person.
Generally, PPG is used to measure blood volume changes in microvascular bed of
3
tissue. With several health information that can be provided by PPG, it carries the potential of becoming an alternative health care system device. Therefore, some medical devices used in clinics and hospitals use invasive techniques. Invasive techniques based medical sensor usually need to be handled by expertise. This issue becomes a constraint causing public concerns, who have got basic skill in using invasive technique-based devices. PPG is a device that use a non-invasive technique. Besides, the method of acquiring data from PPG device is simple and straight forward.
Nowadays, the term ‘wearable technology’ is not strange anymore. According to an in-depth analysis reported by European Parliament, wearable technology is among the top ten technologies which could change people lives (Woensel et al., 2015). PPG device has a great potential to be used as wearable or portable technology by clinicians and hospitals. In addition, the embodiment of existing medical devices with wireless technology give benefits to the user in term of data acquisition. Portable medical device is flexible and can be applied in a number of applications such as in ambulatory services.
Besides that, wireless data acquisition helps medical practitioner to collect information from patients for statistical analysis. Therefore, this research suggests that a real-time wireless based application for use in the health monitoring systems.
There are several studies related to wireless PPG device, which are done by ongoing contemporary researchers. Ghamari et al. (2016) has conducted similar research which is about design and prototyping of wireless PPG device. The study proposes PPG signal for measuring HRV for collecting relevant data using wireless means. Another research had been performed by Vasile et al., (2015) about PPG signal for analysis of cardio-vascular parameters. The research is focusing on circuit development for data acquisition of PPG signal. Therefore, it explains in detail about the circuit construction and functionality specifically made for reading of PPG signal.
4
Thus, in this research, PPG signal obtained using our proposed method will be benchmarked with research done by Ghamari et al. and Vasile et al.
1.2 PROBLEM STATEMENT
In today’s world, medical devices are as common as reliable they have been becoming.
The mediocre health monitoring appliances in hospitals mostly involve ECG and EEG machines. To transform these types of machines into becoming more mobile and portable in applications, a lot of aspects need to be reconsidered. Inventing a wearable sensor for health monitoring system give some challenges in a such as power consumption, size limitation and reducing the effect of motion artifact (Kim et al., 2014). Besides that, most ECG devices require the user to use electrode pads patched to the body area. There has been a previous study on developing wireless ECG system.
Cao et al. (2011) proposed ECG system using three electrode pads. The placement position of the electrode pads is depicted in Figure 1.2.
Figure 1.2 - Placement Positions of Three Sets Electrodes (Cao et al., 2011)
5
The acquisition of ECG data in most cases require the user to patch the electrode pads in the body area. Such circumstance creates uncomfortable situation to some users.
Although a portable ECG machine has been developed, however, the data acquisition is directly fed into that medical devices. There is thus lies the need of a medical device that is portable and is equipped with features of more convenience for patients.
Wireless technology nowadays keeps on developing. It started to be employed in all fields of applications. Therefore, without wireless technology, real-time data acquisition becomes difficult to handle. It eliminates the portability criterion of the system. With the existence of internet as well as the assistant from wireless application, it helps people to improve the current technology. Therefore, in this research, the development of wireless PPG based health monitoring application is proposed to compete with current technology development.
1.3 RESEARCH OBJECTIVES
This thesis has three objectives:
1. To develop a wireless PPG based health monitoring system which consist of the hardware and software.
2. To evaluate and benchmark the performance of the proposed system.
3. To test and validate the developed prototype.
1.4 SIGNIFICANCE OF THE STUDY
PPG based health monitoring system can become a potential medical device in the market. Many researchers work in medical field are focusing on obtaining non- invasively PPG signals data. However, in this research, the medical information
6
extraction will be focusing on Heart Rate Variability as a proof of concept for PPG based health-monitoring system.
Establishing a wireless system for this application is another challenge in this research. The application of this project is for detecting signal comes from human’s body. It is very important to choose the right wireless transmission medium. One of the aspects that we need to consider is the issue of radiation. Radio frequency (RF) based wireless transmission usually have got low frequency with higher amplitude. It emits higher radiation wave compared to Bluetooth based wireless transmission system.
Bluetooth use a very high frequency which generates low signal amplitude. Therefore, in this research, we proposed Bluetooth wireless transmission system for wireless PPG- based health monitoring application, keeping radiations-related concerns to minimum.
1.5 SCOPE OF RESEARCH
This research will be focusing on prototype development for acquisition of PPG signal data through employing cordless transmission medium. However, as a proof of concept, heart beat count (HBC) and Heart Rate Variability (HRV) measurements based on acquired PPG signal are measured and analysed. PPG signal is obtained through voluntarily consents from healthy Malaysian subjects Malaysian on IIUM campus. This research excludes exploring factors causing major disturbances and changes toward the fluctuation of PPG signal. Hence the study of PPG signals related to professions of hard labour or sports of the subjects is excluded. The research is done in an indoor normal environment, excluding thus the effect of any major environment changes such as extremely cold weather or in harsh conditions involving tsunami during earthquakes.
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1.6 EXPECTED OUTCOME AND CONTRIBUTIONS
With the development of a complete working prototype of wireless PPG based health monitoring system, the target user is not only aim for medical practitioner, it is also can be used by public community. This implication creates health awareness among citizens. Therefore, this prototype provides the community with another alternative to use as sensor in health monitoring device and increase the trustworthiness and confidence level of people towards PPG based health monitoring device. The real-time wireless PPG data acquisition enables researchers to explore more about PPG in wide perspective and scope.
1.7 THESIS ORGANIZATION
The thesis is organized such that Chapter Two describes the literature relevant to PPG based health monitoring system and wireless technology for use in medical applications.
Chapter Three gives the methodology of the study. The methodology comprises the
overall research approach to solve the research problem. This chapter also explain the process ranging from software code development to hardware implementation. The outcome of this project is also including the final prototype product. Chapter Four gives details of topologies on the research including some observations and analysis to show the outcome of the project. Chapter Five briefly elaborates in compact form the conclusion and some idea about future works for this study. It also highlights the contribution of this thesis for improving the health levels of society alongside suggesting further work.
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CHAPTER TWO LITERATURE REVIEW
2.1 INTRODUCTION
Medical sensor technology had been invented since over decades ago. Every year, there have been a lot of research works produced to upgrade and increase the performance of medical sensor technology. The study of this research which is focusing on wireless PPG signal acquisition requires a thorough learning and exploring of related and contemporary research. In this chapter related works are elaborated on three main aspects: namely, PPG device, health monitoring system, and wireless technology.
2.2 OVERVIEW OF PPG AND WIRELESS TECHNOLOGY
The use of wireless technology has influenced our society life style in many ways. Most of the technology devices have started getting upgraded to wireless-based system, venturing gradually into the medical technology. People have opted choosing wireless technology mainly for the reason of ease, mobility, and comfort. The implementation of wireless based health monitoring system expands its applications into the area of ambulatory services (BSR, 2012). The parameters of interest in this regard are issues related to synchronization, the effect of the harsh environment and the use of security coding for obtaining real-time data in assisting meaningfully the ambulance or caring service being provided. Therefore, this research suggests that a real-time wireless based application in the health monitoring system.
Biomedical sensing technologies such as electrocardiogram (ECG), electromyogram (EMG) and electroencephalogram (EEG) are widely used in medical applications. In most cases, these human bodies physiological measurements require a
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lot of power rendering them with limited mobility. Another biomedical device that can provide medical information is photoplethysmograph (PPG). PPG is a technique of measuring the amount of blood volume changes in the microvascular bed of tissue (Tamura et al., 2014). It is one of biomedical sensors that are suitable for applications requiring low power consumption and enhanced portability. Since PPG is a non- invasive device, therefore, it is easier to be used by community. In this research, the proposed biomedical device for the development of real-time health monitoring system is based on PPG.
2.2.1 Overview of PPG
There have been several types of plethysmography techniques including water, air, strain-gauge, and impedance as shown Figure 2.1. However, photoelectric plethysmography (PTG) or photoplethysmography (PPG) is said to be easier in setting up, more convenient, simpler and more efficient compared to other types of plethysmograph (Spachos et al., 2011). The application of PPG helps the user of this technology to investigate mainly about the erythrocyte volume changes in the microvascular bed of tissue. The discovery of PPG signal has opened another gateway for researchers to explore new study involving the plethsmography field.
