TRADE PROJECT

RIFT VALLEY TECHNICAL TRAINING INSTITUTE

P.O BOX 244

ELDORET

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

COURSE TITLE: DIPLOMA IN MEDICAL ENGINEERING

PROJECT TITLE: PULSE OXIOMETER PROJECT

PRESENTED BY:

INDEX:

Supervisor:

THIS PROJECT IS PRESENTED TO THE KENYA NATIONAL EXAMINATION

COUNCIL FOR THE PARTIAL FULFILLMENT FOR THE AWARD OF DIPLOMA IN

MEDICAL ENGINEERING.

JULY 2025

i
 DECLARATION

I declare that this is my original work and has never been presented to any institution of higher

learning for diploma award.

Date………………. Sign………………

SUPERVISOR

I declare that this work has been submitted to the Institute with my approval as the supervisor,

Rift Valley Technical Training Institute, Department Electrical and Electronics Engineering

Mr. Tororei

Sign________ Date_________

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 ACKNOWLEDGEMENT

I would like to thank the Almighty God for His provisions and protection in my life and especially

throughout my academic learning. Special thanks also goes to my lecturers, Department of Electrical

and Electronics Engineering for the good foundation they laid in my life in the field of electrical for

the last three years and especially my project supervisor, for the guidance in my trade project as a

whole. I also thank my parents for their prayers and financial support in ensuring the success of this

project. May God bless you all.

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 DEDICATION
I dedicate this trade project to my parents, brothers, sisters and my future children

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 Abstract

In this report, the design and implementation of a low-cost, portable and wearable

pulse oximeter is presented. A pulse oximeter is a non-invasive device capable of

monitoring the blood’s oxygen saturation. It has been widely used in the medical, fitness

and clinical care worlds. A low-cost wearable oximeter can significantly expand its

applicability. The goal of this capstone design project was to design and build a low-cost

wearable pulse oximeter, by using wearable electronics. The system consists of three main

parts: 1) the optical sensor: consisting of the optical transmitter and receiver for emitting

the light and receiving it and filter; 2) the microcontroller: which receives and processes the

signal to display the heart rate and blood’s oxygen saturation on an LCD display in real

time; and 3) mobile phone app which is designed to receive data wirelessly through

Bluetooth. The app can send the data to another phone via text message, which will make it

easy for sending the heart-rate information to medical doctors in real time, in case of

emergency.

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Contents
DECLARATION.................................................................................................................................2
ACKNOWLEDGEMENT...................................................................................................................3
DEDICATION.....................................................................................................................................4
Abstract................................................................................................................................................5
CHAPTER 1........................................................................................................................................7
I. Introduction.................................................................................................................................7
1.1 Background..........................................................................................................................9
1.2 Problem Statement.............................................................................................................10
1.3 Objectives of Project..........................................................................................................11
1.4 Scopes of Project................................................................................................................11
CHAPTER 2......................................................................................................................................12
REVIEW OF PATİENT MONITORING..........................................................................................12
2.2 Releated Research..............................................................................................................13
2.3 PIC16F877A Microcontroller.............................................................................................15
2.4 LCD Display......................................................................................................................16
2.5 Heart Rate Sensor...............................................................................................................17
2.6 Temperature Sensor............................................................................................................18
2.7 Humidity Sensor SHT-11...................................................................................................18
2.8 MikroC...............................................................................................................................19
CHAPTER 3 METHODOLOGY.......................................................................................................22
3.1 Introduction........................................................................................................................22
3.2 Design.................................................................................................................................22
3.2. Flow Chart of System.........................................................................................................25
Codes;.............................................................................................................................................28
CHAPTER FOUR..............................................................................................................................35
4.1 Conclusion..........................................................................................................................35
REFERENCES...................................................................................................................................37

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 CHAPTER 1

I. Introduction

Pulse oximeter is a medical instrument that can detect heart-rate and oxygen saturation

as signatures of our level of health condition. It can be implemented as a small device, and

therefore, has been used widely in different applications. The core theory behind the pulse

oximeter is the variability of the absorption coefficient of photons going through human

tissues at different wavelength. Since people are caring about the amount of oxygen

saturation in our blood, the specific wavelength region should be settled which is the most

sensitive to the oxygen in our blood. In our blood, oxygenated hemoglobin (Hb) and

deoxygenated hemoglobin (deoxy-Hb), which can be used to measure human blood oxygen

level, have stronger absorbers of light with wavelength in the range of 650 nm-1000 nm

(Figure 1). In this wavelength range, other layers of human body, for instance water and fat,

have a very low absorption coefficient comparing with that of oxygenated hemoglobin and

deoxygenated hemoglobin. Also the good news is that the light absorption of Hb and

deoxy-Hb at the two different wavelengths is different. When the light of around 650 nm

wavelength is emitted to our blood, deoxy-Hb absorbs more than oxy.

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 The optical sensor is consisted of two different wavelength LEDs and a photo-

detector for receiving the light coming from the finger. In Figure 2, the probe

structure has been shown.

The small amplitude analog current coming from the photo-detector needs to be

amplified by the transimpedance amplifier (TIA) and then processed by a filter.

The microcontroller is one of the most important parts in our design. We

programmed it in order to do the necessary calculations to measure the heart rate

and oxygen saturation level. Also, the Bluetooth communication and LCD

display are controlled by our microcontroller. In the end, the software engineer

of the team developed a phone application which is used to manipulate the

whole system. Figure3 shows the design vision of our target system.

2
1.1 Background

Telemedicine is the use of medical information exchanged from one site to

another via electronic communications to improve patients’ health status.

Telemedicine is a newest technology which combining telecommunication and

information technology for medical purposes [1]. It gives a new way to deliver

health care services when the distance between the doctor and patient is significantly

away. Rural area will get the benefit from this application. Patient monitoring is one

of the telemedicine, which always needs improvement to make it better. It is vital to

care in operating and emergency rooms, intensive care and critical care units. It is

also important for respiratory therapy, recovery rooms, out-patient care, radiology,

ambulatory, home and sleep screening applications.

The advantages of a patient monitoring system are it can reduce the risk of

infection and other complication in order to make the patients comfortable.

Furthermore, implement of patient monitoring in hospitals might reduce the costs in

terms of installation and also maintenance of wiring [2]. Since many critical patients

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need a high attention in intensive care unit (ICU) and cardiac care unit (CCU), thus

the bedside in the hospitals over the limit as provided to the patients. Otherwise, this

creation will help

more elderly patients who need constant monitoring, both in the hospital or home

environment.

Previously, the available medical monitoring system is generally bulky and

thus uncomfortable to be carried by patients. Patient monitoring using wireless

sensor network has a greater potential in the future in order to achieve the best

performance health care services and also to avoid from cost pressure in the hospital.

1.2 Problem Statement

As we know, patient monitor is vital for monitoring patients’ condition

especially in intensive care unit (ICU). Thus, demand on patient monitor is high but

a variety of problems appeared in terms of lack of space in hospitals and also need

high cost maintenance for wiring and installation. The problems can be solve by

using wireless sensor network to ensure the

4
patients can be monitor continuously by doctors, nurses or caregivers anywhere and

anytime even though the patients stay at home. Besides, the costs for wiring and

installation might be reducing as well.

1.3 Objectives of Project

The objectives of the project are:

1. To design and fabricate patient monitoring system for monitoring Hearth rate

signal.

2. To develop wireless system of monitoring system using bluetooth module.

3. To develop data monitoring system using integration between IC and Mobile

platforms.

1.4 Scopes of Project

In order to achieve the objectives of the project, there are several scopes had

been outlined. The scopes in this project include the hardware and software parts.

Systems are controlled by PIC 16F877a , which connected to the bluetooth module

and need some programming works. For the software part, Hyperterminal and

microC for PIC software have been used. Hyperterminal is functioned for

connection between PIC and bluetooth module in order to transmit and receive the

data correctly.

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 CHAPTER 2

REVIEW OF PATİENT MONITORING

Heart rate measurement is one of the very important parameters of the human

cardiovascular system. The heart rate of a healthy adult [1] at rest is around 72 beats

per minute (bpm). Athletes normally have lower heart rates than less active people.

Babies have a much higher heart rate at around 120 bpm, while older children have

heart rates at around 90 bpm. The heart rate rises gradually during exercises [2] and

returns slowly to the rest value after exercise. The rate when the pulse returns to

normal is an indication of the fitness of the person. Lower than normal heart rates

are usually an indication of a condition known as bradycardia, while higher than

normal heart rates are known as tachycardia. Heart rate is simply and traditionally

measured by placing the thumb over the subject’s arterial pulsation, and feeling,

timing and counting the pulses usually in a 30 second period. Heart rate (bpm) of

the subject is then found by multiplying the

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obtained number by 2. This method although simple, is not accurate and can give

errors when the rate is high. More sophisticated methods to measure the heart rate

utilize electronic techniques. Electro-cardiogram (ECG) is [3,4] one of frequently

used and accurate methods for measuring the heart rate. ECG is an expensive device

and its use for the measurement of the heart rate only is not economical. Low-cost

devices in the form of wrist watches [5,6] are also available for the instantaneous

measurement of the heart rate. Such devices can give accurate measurements but

their cost is usually in excess of several hundred dollars, making them

uneconomical. Most hospitals and clinics in the UK use integrated devices designed

to measure the heart rate, blood pressure, and temperature of the subject. Although

such devices are useful, their cost is usually high and beyond the reach of

individuals. This paper describes the design of a very low-cost device which

measures the heart rate of the subject by clipping sensors on one of the fingers and

then displaying the result on a text based LCD. The device has the advantage that it

is microcontroller based and thus can be programmed to display various quantities,

such as the average, maximum and minimum rates over a period of time and so on.

Another advantage of such a design is that it can be expanded and can easily be

connected to a recording device or a PC to collect and analyse the data for over a

period of time. The building cost of the proposed device is around $20. One similar

basic device from Cosy Communications

[7] with no extension capabilities costs around $100.

2.2 Releated Research

Arun et al. [3]. Every patient is connected with a temperature sensor and

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parameters that are measured are interfaced with the system at the patient end as

shown in Figure 2.1. The patient end system is connected with server and doctor

mobile via Bluetooth. The server stores the central database of all the patients. If the

status is normal, the parameter is transmitted to the server and entered in the

database meanwhile if the status is abnormal, then the parameter is immediately

intimated to the doctor end the data stored in the database of the server. The

weaknesses of this project are the Bluetooth has a short-range communications

where the range is limited, high current consumption and expensive compared to

zigbee.

Ili Najaa Aimi [17] did a project based on wireless to monitor ECG signal

and heart rate of patients via Labview. The complete system is illustrated in Figure

2.3. Basically, the system architecture involves an ECG processing circuit system, a

Labview to display graphical user interface (GUI) which act as a transmitter station

meanwhile the EZ430-Chronos watch is act a receiver station. Input data acquisition

(DAQ), ECG electrodes are used to acquire heart signals from a patients and

8
connected to the computer and processed by Labview. The process includes the

calculation of heart rate and EZ430-Chronos watch which receiver station of

wireless data transmission.

2.3 PIC16F877A Microcontroller

The PIC 16F877 is an 8-bit microcontroller, which has an on-chip eight

channel 10-bit Analog-to- Digital Converter (ADC).First we detect fall down

using accelerometer and fed to the I 2C ports. The amplified and conditioned Heart

Rate signal is fed to input port RB0 (INT) of the microcontroller. Also, upon

command, the microcontroller reads the temperature sample stored in the RAM of

the LM35 through the ADC port RA0. It is then converted and stored in the

PIC16F877 memory as two 8-bit unsigned integers.

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 After completion of signals acquisition, the microcontroller constructs the

SMS messages and packs the data samples in these messages to the desired

length, then communicates with the mobile phone using at-commands on its GSM

modem port to send the message(s). A complete system can therefore be built

using one MCU chip and a few I/O devices such as a keypad, display and other

interfacing circuits. Most of the pins are for input and output, and arranged as 5

ports: PORTA (5pins), PORTB (8pins), PORTC (8pins), PORTD (8pins) and

PORTE (3 pins), total of 32 I/O pins [5], [14].

2.4 LCD Display

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 The Model JHD 162A Series LCD is the typical standard HD44780 type of

LCD with 16characters x 2 row LCD module. Since this project the Heart Rate,

temperature, adders and contact no to display; therefore, a LCD module is

necessary.

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2.5 Heart Rate Sensor

Heart beat sensor is designed to give digital output of heat beat when a finger

is placed on it. When the heart beat detector is working, the beat LED flashes in

unison with each heart beat. This digital output can be connected to

microcontroller directly to measure the Beats per Minute (BPM) rate. It works on

the principle of light modulation by blood flow through Fig 3. At each pulse [13].

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2.6 Temperature Sensor

We used a special rapid, low-cost, integrated-circuit temperature sensors. The

LM35 sensor thus has an advantage over linear temperature sensors calibrated in °

Kelvin, as the user is not required to subtract a large constant voltage from its

output to obtain convenient Centigrade scaling. The LM35 sensor does not require

any external calibration or trimming to provide typical accuracies of ±¼°C at

room temperature and ±¾°C over a full -55 to

+150°C temperature range. It can be Operates from 4 to 30 volts. As it draws only

60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The

LM35 is rated to operate over a -55° to +150°C temperature range. We interface

the temperature sensor to the PIC16F877A microcontroller using the ADC port on

the microcontroller [4].

2.7 Humidity Sensor SHT-11

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 Introduction When it comes to precision temperature and humidity

measurement, Sensirion (www.sensirion.com) has simplified the process their

SHT1x sensor series. Through a two-wire serial interface, both temperature and

humidity can be read with excellent response time and accuracy. Parallax has

simplified the use of the SHT11 by mounting it in a user-friendly 8-pin DIP

module. The module includes a data-line pull-up and series limiter making it

possible to connect directly to the BASIC or Javelin Stamp.

2.8 MikroC

MikroC is one of the powerful and easy to use software for programming PIC

micro controllers in embedded C. mikroC is a powerful, feature rich development

tool for PICmicros. It is designed to provide the customer what the easiest possible

solution for developing applications for embedded systems, without compromising

performance or control. Applications can be developed quickly and easily using

mikroC for PIC microcontrollers. It provides a simple windows based point-and-

click environment for developing applications.

PIC and C fit together well: PIC is the most popular 8-bit chip in the world,

used in a wide variety of applications, and C, prized for its efficiency, is the natural

choice for developing embedded systems. mikroC provides a successful match

featuring highly advanced IDE, ANSI

14
complaint compiler, broad set of hardware libraries, comprehensive documentation,

and plenty of ready-to-run examples.

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16
 CHAPTER 3

METHODOLOGY

3.1 Introduction

This chapter describes the method which has been implemented in this

project. This project is divided into two main parts which are hardware design and

software design. For the hardware design, it is focus on the main controller

hardware, Arduino Uno board which connected to the IC circuit and temperature

sensor (LM 35). Meanwhile, for the software design, Pulse Oximeter Sensor, PIC

and HyperTerminal software have been used.

3.2 Design

In this section, the hardware implementation is discussed which are

consisting of IC circuit PCB, Blutooth transmitter and receiver. Block diagram of the

system is shown in Figure

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18
 The data of Pulse signal and temperature body which obtains from the patient

should be analyzed first. In the project, the heart beat of patient obtained from the

patient stimulator meanwhile the body temperature measurement is measured from

the heat of fingertips. Then, the Circuit board read and interpreted the data which

been transferred by Blutooth transmitter to the laptop and receive the data using

receiver. Flow chart of patient monitoring wireless sensor network is shown in

Figure

19
3.2. Flow Chart of System

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3.3 Software Design

In this section, the software that involved in the project is discussed. microC

PRO software is used to program the PIC and blutooth transmitter to transfer data

from the terminal transmitter to the terminal receiver. The connection both of them

should be programmed first by using HyperTerminal software. Meanwhile, Android

HyperTerminal software is used to display the result (GUI) obtained from the

project. Finally, the data will be displayed in HyperTerminal RS232 software which

can be monitored continuously by the doctors, nurses or caregivers.

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22
Codes;

#include

<16F877A.h>

#device adc=10

#FUSES NOWDT //No Watch Dog Timer

#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz

for PCD) #FUSES NOPUT //No Power Up Timer

#FUSES NOPROTECT //Code not protected

from reading #FUSES NODEBUG //No Debug mode for

ICD #FUSES NOBROWNOUT //No brownout reset

#FUSES NOLVP //No low voltage prgming, B3(PIC16) or

B5(PIC18) used for I/O

#FUSES NOCPD //No EE protection

#FUSES WRT_50% //Lower half of Program Memory is Write Protected

#use delay(clock=4000000)

#use

rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bit

s=8) #include <lcd.c>

int nabiz;

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void main()

setup_adc_ports(NO_ANALOG);

setup_adc(ADC_CLOCK_INTERNAL);

setup_psp(PSP_DISABLED);

setup_spi(SPI_SS_DISABLED);

setup_timer_0(RTCC_INTERNAL|

RTCC_DIV_1);

setup_timer_1(T1_DISABLED);

setup_timer_2(T2_DISABLED,0,1);

setup_comparator(NC_NC_NC_NC);

setup_vref(FALSE);

// TODO: USER CODE!!

lcd_init();

while(true)

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 set_adc_channel(3

); delay_us(20);

nabiz=read_adc();

sht_rd (restemp, truehumid);

if((nabiz>60)&&(nabiz<120))

set_adc_channel(3

); delay_us(20);

nabiz=read_adc();

sht_rd (restemp, truehumid);

printf(lcd_putc,"\fNABIZ :%D ",nabiz);

delay_ms(3000); //delay 500 ms between reading to prevent self heating of sensor

else

set_adc_channel(3

); delay_us(20);

nabiz=read_adc();

25
 sht_rd (restemp, truehumid);

printf(lcd_putc,"\fNABIZ YOK ");

delay_ms(3000);

The platform or Operating System (OS) used to run the application software at

receiving device will influence the choice of the preferred programming language

used in implementing the software. The smart-phone we have used was the Motorola

mobile phone. Capturing the data and decoding them, and extracting the user data

part . The software decodes each data and extracts the time and date, originating

mobile number, and the transmitted patients temperature and Heart Rate samples in

the payload. Figure shows a screen interface of the application software running and

displaying a list of received and decoded datas

26
27
28
 The software converts the data in the message from binary to ASCII and displays

the contents of the message as shown Figure . The first three digits represent body

temperature (were obtained from two bytes) with an implicit decimal point after the

first two digits from the left. Each Heart Rate sample can take a value between 0 and

255 as a maximum since we originally used eight bit accuracy in our ADC Also, the

application software has a menu button, which allows for plotting the Heart Rate

sample points and displaying the Body temperature reading contained in the selected

datae from the list. Figure shows the Samsung smart phone displaying a Heart Rate

with a body temperature reading at the top.

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 CHAPTER FOUR
4.1 Conclusion

A low cost mobile patient monitoring system that utilizes designed, developed,

and tested. An Infrared temperature sensor was integrated with a three lead Heart

Rate monitor (client unit) on a cellular (mobile) phone platform, which can be

considered as a real time transmission mode. Application software is required at the

receiving mobile device (consultation unit) to decode the signal data and Show the

Heart Rate and display the body temperature. The system has a significantly reduced

size and weight, which improves its versatility and mobility. Besides, data can be the

most suitable, if not the only, method of data transmission in emergency situations in

remote area where broadband data communications (like GPRS, EDGE … etc.) are

not available. Steps performed by the microcontroller to retrieve the digital

representation of Heart Rate and Temperature transmit them to the receiver using the

wireless transmission system outlined above. In future work more powerful

transmitters with higher range will be used and the flexibility to use the internet to

send the data to the receiving site will be fully explored.

4.2 Recommendations

1. Enhance Signal Processing Techniques

To improve the accuracy of heart rate and SpO₂ readings, it is recommended to

implement advanced digital filtering techniques, such as moving average filters,

low-pass filters, or machine learning-based artifact rejection methods.

2. Improve Physical Design for Sensor Stability

A custom-designed finger clip or sensor casing should be used to minimize the

effects of external light and movement, ensuring more consistent and reliable

30
 readings.

3. Calibrate Against Medical-Grade Devices

Regular calibration and validation using certified pulse oximeters are essential for

ensuring the reliability of the device, particularly if it is intended for use in clinical

or emergency scenarios.

4. Integrate Wireless Communication

For real-time remote monitoring, integrating Bluetooth or Wi-Fi modules (e.g.,

ESP32 or HC-05) is recommended. This would allow patients or users to transmit

data to mobile apps or web dashboards for further analysis and record-keeping.

5. Include Data Logging Capabilities

Adding an SD card module or cloud storage functionality would enable users to

track historical trends in their biometric data, which is especially beneficial for

managing chronic conditions.

6. Focus on Power Efficiency for Portability

If the device is intended for mobile use, low-power microcontrollers and energy-

efficient components should be selected. Additionally, implementing sleep modes

can extend battery life.

7. User Feedback and Signal Quality Indicators

Incorporating visual or auditory feedback (e.g., LEDs, buzzers, or display messages)

indicating proper finger placement or signal quality will enhance user interaction

and reduce erroneous readings.

8. Expand to Multi-Parameter Monitoring

Future improvements could involve integrating additional sensors (e.g., body

temperature, ECG) to create a comprehensive health monitoring system.

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 REFERENCES

1. S. Edwards., “Heart rate Monitor Book”, Leisure systems international, Dec. 1993.

2. M. Malik and A. J. Camm., “Heart Rate Variability”., Futura Publishing Co. Inc., sept.

1995.

3. J. R. Hampton., “The ECG In Practice”., Churchill Livingstone., Mar. 2003.

4. A. R. Houghton and D. Gray., “making sense of the ECG”., Hodder Arnold

Publishing.m 2003.

5. Forerunner 201/301 User Guide,

web site: http://www.grmin.com

6. Pulsar heart rate monitors, web site: http://www.heartratemonitor.co.uk

7. Cosy Communications web site: http://cosycommunications.com

8. Microchip web site: http://microchip.com

9. PROTON+ User Guide, web site: http://www.crownhill.co.uk

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