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