1. INTRODUCTION1.1 Project definition1.2 Significance1.3 Social, Ethical, Economic Issues1.4 Technical Background

1.4.1 Theory1.4.2 Literature Review

1.5 Technical Challenges2. DESIGN

2.1 Design And Research Plan Proposed2.2 Materials And Methods

2.2.1 Hardware Components1. Microchip PIC16(L)F1825/18292. TCRT 1010

2.2.2 Final Block Diagram2.2.3 Circuit Diagram2.2.4 C Language Coding

3. CONCLUSION

1.1 PROJECT DEFINITION Embedded systems are one of the emerging technologies which are

touching every nook and corner of the mind. “It is impossible to live without these embedded gadgets”-says ELECTRONICS magazine.

The purpose of this project was to design, develop, and test a wrist watch-consisting, light-based heart rate and pulse rate monitor and to measure blood pressure. To develop a portable device, which can measure the three important health characterizing aspects, i.e. Heart Beat, Pulse Rate and Blood Pressure.

As a watch can result into idle device to measure all these because its size is too small compared to traditional equipments. So it comes too handy an easy which doesn’t involve any cumbersome processes to know your heart beat and pulse rate and blood pressure.

Existing Systems1. Analog sphygmomanometer.

2. Needs trained persons.

3. Human error is more.

 

Why Digital Life Watch?1. Replaces the stethoscope and mercury level system.

2. Reduce human error.

3. Can be used at any place.

4. Product is portable.

1.2 1.2 SIGNIFICANCSIGNIFICANC

EE

In India many people are suffering from common disease of heart attack and high blood pressure. The reason behind these disease are that we are not health conscious in today’s fast and challenging life style. The average Indians of young generation depends on easy activities and less hard work.

Current athletic devices for real-time monitoring tend to be mobility-restrictive .

 Personal physical monitoring devices and non-invasive medical diagnostics are becoming more pervasive. 

1.3 SOCIAL, ETHICAL ECONOMIC ISSUES

The main issues concerning this device are acceptance, privacy, accuracy, and cost. The impact of this device directly corresponds to its degree of acceptance and the effect it has on the exercise regiment of the owner.

The accuracy of the device is an important consideration. If it is not sufficiently accurate it a variety of situations, it will have low appeal to consumers. If its accuracy is very high, it has the potential to be able to be used in clinical situations as a substitute for standard heart rate and blood pressure measuring monitors.

The cost of the device will have a very large impact on its popularity. The device was very inexpensive to build and could likely be mass-produced for the same price as a standard device.

1.4 TECHNICAL

BACKGROUND

1.4.1 Theory In order to identify a heartbeat, the heart rate monitor uses a method known

as photo plethysmo graphy (PPG). This method measures the absorption of light by a tissue to determine properties of that tissue. There are two main forms of PPG, transmittance and reflectance, which differ in the relative orientation of the light emitter, light receiver, and tissue being investigated.6 In transmittance PPG, the emitter, usually a light-emitting diode (LED), is directed into one side of the tissue and the receiver is aligned directly on the opposite side of the tissue and oriented to face the LED.

The receiver then measures the intensity of light transmitted through the tissue. In contrast, reflectance PPG works by placing both the emitter and receiver on the same side of the tissue, with both components directed into the tissue. In this case, the receiver measures the intensity of light reflected by the tissue. In both cases, changes in the relative absorption of the tissue directly result in changes in the measured light intensity at the receiver.

Each time the subject’s heart beats, the perfusion of blood in the tissue rises and then falls, and the absorbance of light in the infrared (IR) spectrum increases and then decreases accordingly because blood exhibits strong absorbance in the IR spectrum. This enables heartbeats to be detected by measuring the pulsations in the intensity of light at the receiver. There is some constant absorbance by the skin, muscle, tendons, bone, and average blood volume, but variation in the absorbance is mainly due to the pulsatile blood flow through the tissue.

The variable, or AC, component of the signal that corresponds to the heartbeats can then be isolated from the static, or DC, component of the signal that corresponds to the background tissue with a high-pass filter.

…cont’d In order to identify a heartbeat, the heart rate monitor uses a method known

as photo-plethysmo-graphy (PPG). This method measures the absorption of light by a tissue to determine properties of that tissue. There are two main forms of PPG, transmittance and reflectance, which differ in the relative orientation of the light emitter, light receiver, and tissue being investigated.6 In transmittance PPG, the emitter, usually a light-emitting diode (LED), is directed into one side of the tissue and the receiver is aligned directly on the opposite side of the tissue and oriented to face the LED.

The receiver then measures the intensity of light transmitted through the tissue. In contrast, reflectance PPG works by placing both the emitter and receiver on the same side of the tissue, with both components directed into the tissue. In this case, the receiver measures the intensity of light reflected by the tissue. In both cases, changes in the relative absorption of the tissue directly result in changes in the measured light intensity at the receiver

Each time the subject’s heart beats, the perfusion of blood in the tissue rises and then falls, and the absorbance of light in the infrared (IR) spectrum increases and then decreases accordingly because blood exhibits strong absorbance in the IR spectrum. This enables heartbeats to be detected by measuring the pulsations in the intensity of light at the receiver. There is some constant absorbance by the skin, muscle, tendons, bone, and average blood volume, but variation in the absorbance is mainly due to the pulsatile blood flow through the tissue.

The variable, or AC, component of the signal that corresponds to the heartbeats can then be isolated from the static, or DC, component of the signal that corresponds to the background tissue with a high-pass filter.

Blood pressure (BP), sometimes referred to as arterial blood pressure, is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systematic circulation. During each heartbeat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure. The blood pressure in the circulation is principally due to the pumping action of the heart. 

Your systolic pressure (the first and highest number), is the pressure or force the heart places on the walls of your blood vessels as it is working/pumping with each heart beat. Diastolic pressure (the second and lowest number) is the lowest pressure the blood places on the walls of your blood vessels when the heart is relaxed between beats.

…cont’dBoth of these measurements are important. A high systolic pressure indicates

strain on the blood vessels when the heart is attempting to pump blood into your blood stream. If your diastolic pressure is high, it means that your blood vessels have little chance to relax between heartbeats. The only way to tell if you have high blood pressure (hypertension) is to have it checked.

The oscillometric method was first demonstrated in 1876 and involves the observation of oscillations in the sphygmomanometer cuff pressure which are caused by the oscillations of blood flow, i.e., the pulse. The electronic version of this method is sometimes used in long-term measurements and general practice. It uses a sphygmomanometer cuff, like the auscultatory method, but with an electronic pressure sensor (trasnducer) to observe cuff pressure oscillations, electronics to automatically interpret them, and automatic inflation and deflation of the cuff. The pressure sensor should be calibrated periodically to maintain accuracy.

Since the invention of the electrocardiogram (ECG), technology for continuous heart rate monitoring has been improving. With the discovery of photoplethysmography (PPG), another source of physiological data was provided that could be recorded from almost any skin area. Decades later, almost all heart rate monitors still utilize either one or the other of these two fundamentally different data sources.

As PPG has become better explored, additional applications have been uncovered. One additional benefit of using PPG over ECG is the presence of both heart and respiratory information in the signal. This provides the ability for an effective PPG-based device to gather both heart rate and respiratory rate information from the same probe.

1.5 TECHNICAL1.5 TECHNICAL CHALLENGESCHALLENGES

At the outset of this project, there were two known technical issues that needed to be addressed. Most predominant was the issue of motion resistance and motion artifacts in the PPG signal. As previously described, PPG sensors are notorious for motion artifacts, and much work has been put into devising motion resistant sensors and motion compensation algorithms. This is likely one reason why ECG sensors dominate the current consumer heart rate monitor market, but significant research efforts are currently underway to improve PPG devices to broaden their application.

For this project, this challenge was met through targeted device and filter design, with the attempt to try to reduce the motion of the device as much as possible, as well as eliminate motion artifacts from the captured signal. Further, the signal to noise ratio was so poor in initial trials that digital signal processing was not a reasonable approach. A major focus of the project was thus on the challenge of acquiring an adequate signal and effectively filtering it in the analog domain.

The system model uses MICROCHIP PIC16(L)F1825/1829 Microcontroller to perform the task of measuring heart rate, pulse rate and blood pressure. The controller first filters the noise from input signal. It then processes and identifies the received signal. In this blood pressure monitor we can use Korotkoff, Oscillometry, or Pulse Transit Time methods to measure blood pressure. They employ a pressure cuff, pump, and transducer to measure blood pressure and heart rate in three phases: Inflation, Measurement, and Deflation.

The pressure transducer produces the output voltage proportional to the applied differential input pressure. The output voltages of the pressure transducer range from 0 to 40 mV, which need to be amplified so that the output voltage of the DC amplifier has a range from 0 to 5V. Then the signal from the DC amplifier will be passed on to the band-pass filter.

2.1 DESIGN AND RESEARCH PLAN PROPOSED

The DC amplifier amplifies both DC and AC component of the signal. The filter is designed to have large gain at around 1-4 Hz and attenuate any signal that is out of the pass band. The AC component from filter is important for determining when to capture the systolic/diastolic pressures, pulse rate and heart rate of the patient. The final stage of the front end is an AC coupling stage, after which the signal is sent to analog to digital converters, and digitized.

The digital measurements of blood pressure, pulse rate and heart rate are performed by the microcontroller. Measurements results are stored in EEPROM or FLASH memory as a data log that can be viewed in future. The analog circuit is used to amplify both the DC and AC components of the output signal of pressure transducer so that we can use the MCU to process the signal and obtain useful information about the patient's health.

2.2.1 Hardware ComponentsThe major equipments required for this project are;

1. MICROCHIP PIC16(L)F1825/1829

It is a 14/20-Pin Flash Microcontrollers with nano Watt XLP Technology. Some of features about the PIC16(L)F1825/1829 are given as below.

High-Performance RISC CPU: Only 49 Instructions to Learn:

- All single-cycle instructions except branches Operating Speed:

- DC – 32 MHz oscillator/clock input

- DC – 125 ns instruction cycle Up to 16 Kbytes Linear Program Memory Addressing Up to 1024 bytes Linear Data Memory Addressing

Interrupt Capability with automatic context saving 16-Level Deep Hardware Stack with Optional Overflow/Underflow Reset Direct, Indirect and Relative Addressing modes:

- Two full 16-bit File Select Registers (FSRs)

- FSRs can read program and data memory

Flexible Oscillator Structure: Precision 32 MHz Internal Oscillator Block:

- Factory calibrated to ± 1%, typical

- Software selectable frequencies range of 31 kHz to 32 MHz 31 kHz Low-Power Internal Oscillator Four Crystal modes up to 32 MHz Three External Clock modes up to 32 MHz

…cont’d 4X Phase Lock Loop (PLL) Fail-Safe Clock Monitor:

- Allows for safe shutdown if peripheral clock stops Two-Speed Oscillator Start-up Reference Clock Module:

- Programmable clock output frequency and duty-cycle

Peripheral Highlights: Up to 17 I/O Pins and 1 Input Only Pin:

- High current sink/source 25 mA/25 mA

- Programmable weak pull-ups

- Programmable interrupt-on-change pins Two Enhanced CCP (ECCP) Modules:

- Software selectable time bases

- Auto-shutdown and auto-restart

- PWM steering Up to two Master Synchronous Serial Port (MSSP) with SPI and I2CTM

with:

- 7-bit address masking

- SMBus/PMBusTM compatibility

Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) Module

mTouch™ Sensing Oscillator Module:

- Up to 12 input channels

Data Signal Modulator Module:

-Selectable modulator and carrier sources  SR Latch:

- Multiple Set/Reset input options

- Emulates 555 Timer applications

2.TCRT 1010

Features of TCRT1010.

Reflective Optical Sensor with Transistor OutputPackage type: leadedDetector type: phototransistorDimensions (L x W x H in mm): 7 x 4 x 2.5Peak operating distance: 1 mm

…Cont’dOperating range within > 20 % relative collector current:

0.2 mm to 4 mmTypical output current under test: IC = 0.5 mADaylight blocking filterEmitter wavelength: 950 nmLead (Pb)-free soldering releasedMaterial categorization

Schematic diagram

APPLICATIONSOptoelectronic scanning and switching

devices i.e., index sensing, coded disk scanning etc. (optoelectronic encoder assemblies for transmissive sensing). The TCRT1000 and TCRT1010 are reflective sensors which include an infrared emitter and phototransistor in a leaded package which blocks visible light.

2.2.2 Final block diagram

Cicuit diagram**:

…cont’d**This circuit diagram only consist of circuitry for heart

beat measurement and pulse rate, and it doesn’t contain blood pressure circuitry. As the remaining project is under progress and construction.

Biomedical engineering (BME) is the application of engineering principles and techniques to the medical field. It combines the design and problem solving skills of engineering with medical and biological sciences to improve patient’s health care and the quality of life of individuals. A medical device is intended for use in the diagnosis of disease, or in the cure, treatment, or prevention of diseases.

From this project our intent is to have a watch which can be used for our health conciousness. So with the help of our internal guide Umang H. Soni and research on references we concluded that we can develop this device with more accurate and precise results compared to other devices and its previous versions.

Along with this a person can check his heart rate, pulse rate and blood pressure any time with this watch. Heart beat is measured using LED, LDR(TCRT1010) and operational amplifier. The blood pressure can be measured by pressure belts and transducers. Hence both parameters can be displayed on a LCD display.

FUTURE SCOPEOther health parameters can also be monitored.

Continuous monitoring and future diagnosis can be performed via the same system.

More than a single patient at a place can be monitored using single system.

BENEFICIARIESNo need of traditional stethoscope, Mercury filled

blood pressure measuring instrument.

It can save the life of a person from any unexpected health degradation.

Patient can monitor/measure his Heartbeat, pulse rate & blood pressure any time.

We have studied and researched about DIGITAL LIFE WATCH via:

www.alldatasheets.comwww.microchip.comwww.vishay.comwww.electronicforu.comwww.wikipedia.com