Low cost ECG monitor for developing countries

Abstract

Cardiac or cardiovascular disease (CSD) will become the leading cause of death worldwide by the year 2010. To help doctors in developing countries make an accurate diagnosis, an electrocardiogram (ECG) of low cost has been built and fully tested. Though primarily designed for cardiac diagnosis, respiratory rates and other vital health information such as Sleep Apnea can be extracted from ECG signals. There has been an unprecedented increase in the number of mobile phone subscribers in the developing world which has seen mobile phones used in ways not seen in the developed world. Mobile phones can be used to display the patient's ECG, thus dramatically reducing the cost, and to provide doctors stationed on site a means of diagnosis before the need for any medical evacuation. Electricity outages, remoteness of location, poor maintenance and consumable shortages mean that commercial electrocardiograms (ECGs) used to diagnose such diseases in developing nations, if present, are left unused. This project aims to design and construct at least two of the four main components in a basic modern ECG data logging system — the patient's electrodes and the amplifier. Problematic issues in implementing the ECG system are addressed by ensuring that costs are minimised and that all components are reusable. Three electrodes made from scrap material will connect to a low power amplifier of high gain which will easily run off batteries. As nearly all mobile phones have USB and bluetooth ports, low cost interfaces built using microcontrollers can be used which convert the analog ECG signals to a digital stream suitable for display on a phone. The resulting digital signals are intended to be sent from the interface to the phone via a USB cable connected to the phone's USB port, and displayed on the phone's screen. The ECG data on a PDA have been displayed after successful testing using firmware written which passes the ECG signals to the PDA as a digital stream through the PDA's bluetooth port via a laptop through its USB port. The ECG signals have also been graphed and displayed successfully on a laptop running Windows XP.