CONCLUSION for Overall Research Project Degree Semester 1 

            This device is a new improvement to reduce the human use and cover the problem from the environment surrounding that always has a noise sound on it with attach a counting time for heart beats per minute. For this time, a lot of medical device come with new design and more complicated function on it base on the era of globalization.

    This medical device is the basic apparatus that always with the doctor every time. The doctor will know patient condition when they hear the sound of heart beats. The main objective to enhance this project is co give a small contribution from the engineering design to simplify the work of doctor from wear a watch and the check the time, with the action now change by waiting the counting finish, the result will appears at the monitor. Other then that, the doctor can also gets the result even though he or she checks the patient in the noise surrounding area not at the small and silent room anymore.

               The medical equipments are always upgrading their idea and it also give a lot of knowledge and how to control and understand the device feature. The idea for change this stethoscope to become the new one that is Digital Electronic Stethoscope is the great idea that can give a lot of extra advantages by using this device.

SUPER VOLTAGE CONVERTER (ICL 7600S)

The ICL7660S performs supply voltage conversion from positive to negative for an input range of 1.5V to 12V, resulting in complementary output voltages of -1.5V to - 12V.

Figure 2 : Super Voltage Converter ICL 7660S

To run this both op-amp and voltage comparator, it need to supply the + voltage and – voltage, so this super voltage converter is the best and suitable IC (integrated controlled) to convert the input that is +12 volt from the power supply to make their own output that is -12 volt to supply for the both IC that is operational amplifier LM 741 and voltage comparator LM311.

 VOLTAGE COMPARATOR ( LM 311)

Figure 1 : Datasheet of LM 211H or LM 311H

LM311 are voltage comparators that have input currents nearly a thousand times lower. This integrated controller (IC) is single high-speed voltage comparators. These devices are designed to operate from a wide range of power supply voltages, including ±15-V supplies for operational amplifiers.

Figure 2 : Voltage Comparator LM 311

By using the circuit of interface with high level logic with voltage comparator it is to maximize the input that came from op-amp for their counter of the circuit to make either high or low output signal that will came out to as a output signal then.

CONDENSER MICROPHONE

Condenser means capacitor, an electronic component which stores energy in the form of an electrostatic field. The term condenser is actually obsolete but has stuck as the name for this type of microphone, which uses a capacitor to convert acoustical energy into electrical energy.

Condenser microphones require power from a battery or external source. The resulting audio signal is stronger signal than that from a dynamic. Condensers also tend to be more sensitive and responsive than dynamics, making them well-suited to capturing subtle nuances in a sound. They are not ideal for high-volume work, as their sensitivity makes them prone to distort.

How Condenser Microphones Work

A capacitor has two plates with a voltage between them. In the condenser mic, one of these plates is made of very light material and acts as the diaphragm. The diaphragm vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. Specifically, when the plates are closer together, capacitance increases and a charge current occurs. When the plates are further apart, capacitance decreases and a discharge current occurs.

A voltage is required across the capacitor for this to work. This voltage is supplied either by a battery in the mic or by external phantom power.

Figure 1: Overview Condenser Microphone Sensor

The Electret Condenser Microphone

The electret condenser mic uses a special type of capacitor which has a permanent voltage built in during manufacture. This is somewhat like a permanent magnet, in that it doesn't require any external power for operation. However good electret condenser mics usually include a pre-amplifier which does still require power.

Other than this difference, you can think of an electret condenser microphone as being the same as a normal condenser.

PRINCIPLES OF THE ELECTRET CONDENSER MICROPHONE

An electret condenser microphone (ECM) consists of a very light diaphragm (moving plate) and back plate (stationary or static plate) and has a permanent charge implanted in an electret material to provide polarizing voltage. The principle of operation is that sound waves impinging on the diaphragm cause the capacitance between it and the back plate to change synchronously, this in turn induces an AC voltage on the back plate.

1. Foil Electret Condenser Microphone (also called Middle or Classic) - Type of condenser microphone  where the electret material is the diaphragm. (Sometimes referred to as "Front" type.)
2. Back Electret Condenser Microphone -Type of condenser microphone where the electret material is the back plate.
3.   Front Electret Condenser Microphone -Type of condenser microphone where the electret material is the inside of the case of the microphone.

OPERATIONAL AMPLIFIER (LM 741)

Figure 1: Datasheet of LM 741

      An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. An opamp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.

The circuit symbol for an op-amp is shown to the right, where:

• ·         V+ : Non-inverting input
• ·         V- : Inverting input
• ·         V_out : Output
• ·         V_S+ : +12V positive power supply
• ·         V_S- : -12V negative power supply

By using non inverting circuit, this op-amp will amplified higher signal input that came from the voltage of heart beat to the circuit voltage comparator to get the output.

Figure 2: Op amp 741 with Non-inverting amplifier circuit

WORK PLAN

The time frame allocated for this project study is 12 months. It will start in July 2012 and is projected to be completed in June 2013. The Gantt chart for the project and its milestone are shown as in Table 1.

Practically, reliability is often more difficult to specify than many major performance characteristics and is certainly more difficult than most to measure. The accurate assessment of the reliability of a product in use is often difficult because of the long period needed or the large number of samples required in order to gain statistical confidence in the assessment. In reliability estimation, the failure rate models are approximations to reality. The failure rate models are normally based on the best field data that could be obtained for a wide variety of parts and systems. This data is then analysed, with many simplifying assumptions applied, to create usable models.

 Thus, one should not treat a reliability estimation numbers for the system as an absolute prediction of field failure rate. Generally, it has been agreed that these estimations can be very useful when used for relative comparison, such as comparing design alternatives, or comparing products.

Table 1 : Work Plan Schedule

BENEFIT of the PROJECT

Figure 1

                                                     

Based on the objective above, this project study will be develops of analogue stethoscope to electronic stethoscope. Most of the existing stethoscopes nowadays are manually use by doctor, medical assistant and so on. It’s because the analogue stethoscope the result will get not accurate compared used the digital stethoscope.  Therefore, in the study of this project will develop an electronic stethoscope to contribute to the convenience of users and technological advancements.

            Electronic stethoscope also can enhance the Medical Equipment to reduce Human user and noise surrounding because the analogue stethoscope have more noise and the electronic stethoscope the user like doctor can listen to life with ease and also more comfortable and they get more accurate result when they use the electronic stethoscope.

            This electronic stethoscope is easy to bring anywhere because it’s design to be friendly and nice to user because it’s in pocket size compared to analogue stethoscope that have long rubber tube to carry anywhere they go. They also no need to wear ear plug because the electronic stethoscope has been replace with a suitable sensor like Condenser Sensor.

Electronic Stethoscope can used at home to check out body or children are in the good condition or not base on the heart beat of the lung and heart. It's also can use by untrained and non-technical person and can detect the heart beats with accurate result for the sound of heart beats at many places with high sound of noise surrounding.

ARDUINO SOFTWARE

       For this project i use Arduino Software for display the output data or result, signal input enter into the microcontroller of arduino that is at atmega 328P to run the software program that being initialize to get the output for display result at the LCD monitor.

      Arduino is an open-source single-board microcontroller; the hardware consists of a simple open hardware design for the arduino board with an Atmel AVR processor and on-board I/O support. The software consists of a standard programming language and the boot loader that runs on the board. arduino hardware is programmed using a Wiring based language (syntax + libraries), similar to C++ with some simplifications and modifications, and a Processing-based IDE.    

Arduino Software

A screenshot of the Arduino IDE showing a

simple example program.

Developer(s): Arduino Software

 Stable release: 022 / December 24, 2010; 3 months ago

 Written in:  Java

Operating system: Cross-platform

Type:  Integrated development environment

License: LGPL or GPL license

Website: http://www.arduino.cc/en/

Figure 1: Arduino Screenshot Software

         The arduino duemilanove (2009) is a microcontroller board based on the atmega168 (datasheet) or atmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as pulse width modulator, PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

Arduino Duemilanove

         This is the microcontroller board that is used to run the software program of arduino when it attached to the power supply laptop with 5 volt maximum. Then after uploading the program at atmega 328p, this ic can stand alone with their own circuit to run the software of the programming with hardware for this project, Electronic Stethoscope.

As we know, nowadays the used of stethoscope is already familiar always with the doctors. This medical device that can produce the auscultation result on it give the result to the doctor to hear the heart beat sound either from lung or heart. This device not only can give the sound of normal patient but also can detect the irregularly sound of heart that is in others conditions such as pain, bleeding and so on.

The normal rate for the heart beat per minute is 60 bpm while the dangerous heart beat is 120 bpm. This device is only for monitoring and therapy, because it only gives the result base on the detection of sound effect. So the main problem that it been change from the old counting heart beat by the doctor for 60 second that come from his or her watches, to get the heart beat per minute from it patient is not suitable at the surrounding that to noises.

This new design and idea can give a lot of advantage to the doctor to get the heart beat of their patient. Not only can give an accurate result base on the detection of the sensor of sound the microphone stethoscope that can convert the sound of heart beat to digital output.

This is the special product that can give the result for counting that is more relay able compare with human ears. This device also can be used at home to check out body or children are in the good condition or not base on the heart beat of the lung and heart. It is the first monitoring device that can make sure use to maintain our healthier of the body.

OBJECTIVE

Main objectives for this project are:

• Upgrading the Monitoring System for existing method (analogue type) to modern method (digital approach)
• Enhance the Medical Equipment to reduce Human user and noise surrounding
• To provide the opportunity for student to apply and integrate the knowledge
• The philosophy for this project is to Study of Medical Electronic Device Industry and how does it function and detect the signal.

    

These objectives are achieved and the application is working with the desired output.

PROBLEM STATEMENT

         The sound of environment surrounding is the main problem for conventional stethoscope to produce the result. The doctor could not hear the sound of heart beat if it in the noising area because the interruption will make the counting of heart beats become error or wrong. By changing the result into the digital output signal it will give more accurate counting for the heart beat per minute by the sound of heart on it. 

       The analogue voltage needs to be conditioned and then converted into a digital by using an audio analogue-to-digital converter (ADC) or audio code. For these reasons, it is important to develop methods to estimate the reliability of such program, to ensure it will perform satisfactorily when needed the in the specific way. The circuit for this project uses op-amps to greatly amplify a standard sound of heartbeat, and also includes a low pass filter with voltage comparator to remove the background noise from surrounding areas.

SCHEMATIC DIAGRAM

                                                          Schematic Diagram of Electronic Stethoscope

•      CONDENSER MICROPHONE:

           ~ As a sensor that will give the signal of counting  vibration heart beats.

•      OPERATIONAL  AMPLIFIER (Non-Inverting):

           ~This op-amp will amplify higher signal input that came from the voltage of heart beat to

             the circuit voltage comparator to get the output.

•      VOLTAGE COMPARATOR:

           ~Interface with high level logic with voltage comparator it is to maximize the input that came

             from op-amp.

•      ARDUINO:

         ~ This is the microcontroller board that is used to run the software program of arduino when

            it attached  to the power supply with 5 volt maximum.

BLOCK DIAGRAM

This is block diagram of development of electronic stethoscope.  For this block diagram, the input that the microphone stethoscope will receive is heart beats vibration on the diaphragm. Then this vibration of sound will enter to the condenser sensor to produce the voltage output for heart beat. Operational amplifier will increase the voltage supply when move to the output, then enter the voltage comparator as a high or low circuit to make the digital input signal that can be read by the software IC  that is as an indicator to the signal that came out from the heart beats sound signal.

This signal input then will enter the microcontroller of arduino that is at atmega 328P to run the software program that being initialize to get the output for display result at the LCD monitor. The result will appear as same as the instruction from the software program that is need.

FUTURE DESIGN of STETHOSCOPE

Several other minor refinements were made to stethoscopes, until in the early 1960s Dr. David Littmann, a Harvard Medical School professor, created a new stethoscope that was lighter than previous models and had improved acoustics. In the late 1970s, 3M-Littmann introduced the tunable diaphragm: a very hard (G-10) glassepoxy resin diaphragm member with an overmolded silicone flexible acoustic surround which permitted increased excursion of the diaphragm member in a "z"-axis with respect to the plane of the sound collecting area. The left shift to a lower resonant frequency increases the volume of some low frequency sounds due to the longer waves propagated by the increased excursion of the hard diaphragm member suspended in the concentric acoustic surround.

Conversely, restricting excursion of the diaphragm by pressing the stethoscope diaphragm surface firmly against the anatomical area overlying the physiological sounds of interest, the acoustic surround could also be used to dampen excursion of the diaphragm in response to "z"-axis pressure against a concentric fret. This raises the frequency bias by shortening the wavelength to auscultate a higher range of physiological sounds. 3-M Littmann is also credited with a collapsible mold frame for sludge molding a single column bifurcating stethoscope tube with an internal septum dividing the single column stethoscope tube into discrete left and right binaural channels (AKA "cardiology tubing"; including a covered, or internal leaf springbinaural ear tube connector).

  Future Design of Stethoscope

Above is 2 different design the latest digital stethoscope that contain a digital counting and also the waveform of heart beat that will appears at the display monitor of it. This is very useful for the doctor to declare the situation patient while monitor them.

HISTORICAL of STETHOSCOPE

The stethoscope (from Greek στηθοσκόπιο, of στήθος, stéthos - chest and σκοπή, skopé - examination) is an acoustic medical device for auscultation, or listening to the internal sounds of an animal body. It is often used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure. Less commonly, "mechanic's stethoscopes" are used to listen to internal sounds made by machines, such as diagnosing a malfunctioning automobile engine by listening to the sounds of its internal parts. Stethoscopes can also be used to check scientific vacuum chambers for leaks, and for various other small-scale acoustic monitoring tasks. A stethoscope that intensifies auscultatory sounds is called phonendoscope.

                                         

     Early Stethoscope

Stethoscope history began in 1816 with French physician, Dr. Rene Laennec at the Necker-Enfants Malades Hospital in Paris. It consisted of a wooden tube and was monaural. His device was similar to the common ear trumpet, a historical form of hearing aid; indeed, his invention was almost indistinguishable in structure and function from the trumpet call microphone.

Dr. Laennec spent the next three years perfecting his stethoscope's historical design and listening to the chest findings of patients with pneumonia, comparing what he heard to their autopsy lung findings. From this he published the first seminal work on the use of the stethoscope to listen to body sounds entitled De L'auscultation Mediatein 1819 at thirty-eight years old. Ironically, Laennec himself died of tuberculosis on August 13th, 1826.

Stethoscope history further evolved to the biaural two ear stethoscope types in 1852 by the work of American, George Cammann. And most recently, electronic stethoscopes with microphones, amplifiers, and fuzzy logic have been developed but have not been widely adapted to date. And here ends the stethoscope history for now.

                                                    

                                                  Invention Stethoscope