Design and development of a phonocardiograph for telemedicine applications

Cardiovascular diseases (CVDs) represent one of the leading causes of death in low income countries where there is in general an absence of necessary medical devices and access to qualified medical professionals, particularly in the rural areas. A simple device like the phonocardiograph (PCG) linking patients in these areas to city based qualified medical professionals through telemedicine could provide an important solution. In this paper, the design and development of a low cost, user-friendly phonocardiograph system for telemedicine applications is presented. The device is composed of three main parts namely, the acoustic sensor module, the audio amplifier module and the application software. The acoustic sensor module is made up of a chest piece and a microphone enclosed in an acoustic insulator. COMSOL Multiphysics software was used to simulate the transmission loss through the acoustic insulator to find the material and thickness that will provide of the optimal insulation. It was found that a combination of a 2 mm thickness of Poly Lactic Acid (PLA) with a 10 mm thickness of Polystyrene provided an optimal insulation. The microphone converts the sound waves from the chest piece into electrical signals. This signal is then filtered and amplified by the audio amplifier module and sent to a PC via its microphone input. Using the application software, the electrical signal is digitized and processed for visualization and analysis in situ or remotely. The developed system works in the frequency range of 20 Hz to 1 kHz, with amplification of up to 100 times, and a noise attenuation of 89%.