Stethoscopes are in use for more than 200 years for medical diagnostics, especially for auscultation in the healthcare domain. Recently, unprecedented growth in mobile technology has revived the use of stethoscopes for Telehealthcare. Digital or electronic stethoscopes are increasingly researched for use in Telehealthcare within the healthcare domain. Cardiovascular diseases have become highly prevalent worldwide, especially in the subcontinent. Improvements in diagnostics will improve the quality of life and prevent the loss of life. This research paper mainly focuses on the acoustical and multiphysics design aspects of the stethoscope for improved acoustical performance. A COMSOL model of the stethoscope chest piece was developed. The model was setup to investigate the effects of geometry, material of construction, noise and input pressure. The sound transmission efficiency of the components was investigated with multiphysics models by coupling the acoustical and structural performances. The effect of ambient noise on the performance was also studied and reported. This COMSOL model wasis further used to investigate the effects of shape, size and material parameters on the performance and improvement in the acoustic transmission and noise isolation. The frequency response of the system was also investigated for resonance and performance in relation to auscultation of cardio, lung and other sounds. Through this research paper the researchers share the initial findings for the development of acoustical and multiphysics design aspects of the stethoscope. The ultimate objective is to leverage the improvement in the acoustics of the stethoscope for use in Telehealthcare.
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ATOA Scientific Technologies Multiphysics CAE for Innovation TM Acoustical Design of Digital Stethoscope for Improved Performance Dr Raj C Thiagarajan 1 , Dr Prema Sankaran 2 , Dr Abdul Hafeez Baig 3 , Er Kodeeswari Elangovan 1 , Dr Raj Gururajan 3 1 ATOA Scientific Technologies Pvt Ltd , Bangalore, India. 2 RMK Engineering College, Department of Management, Chennai, India. 3 University of Southern Queensland, Toowoomba, Queensland, 4350, Australia.
Transcript
ATOA Scientific Technologies Multiphysics CAE for Innovation TM
Acoustical Design of Digital Stethoscope for Improved Performance Dr Raj C Thiagarajan1, Dr Prema Sankaran2, Dr Abdul Hafeez Baig3,
Er Kodeeswari Elangovan1, Dr Raj Gururajan3
1ATOA Scientific Technologies Pvt Ltd , Bangalore, India. 2RMK Engineering College, Department of Management, Chennai, India. 3University of Southern Queensland, Toowoomba, Queensland, 4350, Australia.
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
ATOA Scientific Technologies (ATOAST)
• Engineering Simulation Solution Provider for First Time Right Design.
• Bridge Atom to Application to Proliferate Simulation (Multiphysics, Multiscale & multimaterial) for cost effective Innovation.
• ATOAST’s Technical Vision is Driven by Material Unity
• ATOAST Global with HQ’s in Bangalore
• India’s First COMSOL Certified Consultant
• ATOAST JYOTHI Foundation empowers our social mission.
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ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Stethoscope
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• Stethoscopes are used for auscultation of heart, lung and murmurs for over two centuries.
• New development in digital stethoscope convert acoustical energy into other forms (electromagnetic, electrostatic) and back to acoustical energy.
• Our objective is to improve the basic acoustics for use in telehealth environment.
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Telehealthcare
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• There's a huge, unmet healthcare need in India.
• Unprecedented growth in mobile communication
• Telemedicine is a good for Affordable Solution
– Low cost + Digital+ Communication
– WHO eHealth /mhealth
– Quality healthcare for all
• Digital healthcare devices
• Telecommunication
• Rural/Developing
• Urban/Developed
Affordable, Quality
healthcare
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Acoustical Design
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• Performance improvement
• Sound propagation
• Noise effects
• Material of construction
• Geometry
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Governing Equation
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• The acoustic wave propagation in the stethoscope is governed by the wave propagation equation.
• The frequency domain pressure acoustics interface in COMSOL was used for this investigation.
• Sound waves in a lossless medium are governed by the inhomogeneous Helmholtz equation.
Q
p
t
p
cs
q .0
2
2
20
1
1
Where, ρ0 in kg/m3, refers to the density cs in m/s is the speed of sound, p in (N/m2), is the differential Pressure Q in 1/s2
is the source
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
DoE Design and Simulation
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• Parametric CAD model and FEA mesh
• The air column inside the stethoscope, Aluminum or stainless steel casing and the surrounding air were modeled as separate domains.
• The model was equipped to investigate the effects of geometry, construction material, and environment variables on the acoustic performance for optimization.
• The frequency response of the stethoscope from 10 to 2000 Hz was investigated.
Material Density (kg/m2)
Speed of sound (m/s)
Aluminum 2700 6420
Brass 8480 390
Stainless Steel 7850 6100
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Results and Discussion
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• Sound Pressure level of the air column
• Propagation pattern varies with frequency
• Significant for auscultation and signal processing.
Sound Pressure at 100 Hz
Sound Pressure level at 1500 Hz.
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Results and Discussion
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• Sound propagation performance of the stethoscope with the air column and Al casing
• Contributes to the efficiency of the sound propagation
Sound Pressure level of the aluminum stethoscope at 100 Hz.
Sound Pressure level of the aluminum stethoscope at 1500 Hz.
Frequency response
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Results and Discussion
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• Auscultation Pressure + Noise Input
• Interaction effects as function of frequency on the transmission.
• SS vs AL Pressure and noise interaction contour plots of stainless steel stethoscope at 100 Hz.
Pressure and noise interaction contour plots of stainless steel stethoscope at 1500 Hz
Sound Pr level at the for SS and AL Stethoscopes
ATOA Scientific Technologies Multiphysics CAE for Innovation TM |www.atoastech.com |COMSOL 2012| Acoustics of DS
Conclusion
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• Parametric COMSOL model is useful in estimating the performance of the stethoscope.
• Geometry, Frequency, noise, material construction performance investigated.
• Results will be used to improve the performance for use in telehealth environment.
• Multiphysics coupling and FSI will be used in the future for product design and finalization.
