Design and performance analysis of an infra-red based heart rate monitoring system

Abstract

The rate of the human heartbeat is an indication of the health status of the heart and circulatory system and many humans are potential candidates of stress-related health conditions due to the non-availability of a heart rate measuring device that is both affordable and easy to operate. This paper presents a study on the design and performance analysis of an efficient infrared based heart rate monitoring (HRM) system that is economical and portable. The heart rate is measured by placing the finger on an Infra-Red (IR) sensor unit composed of the IR Light Emitting Diode (LED) and a photo-diode. The heart rate is detected from the blood flow through the finger and the pulse signals pass through some filtering and amplification to be detected by the microcontroller. The HRM system employs a microcontroller, PIC16F628A which serves as a central processing unit (CPU) to process and analyze the heart beats detected as electrical signals from the IR sensor unit and converts the measured heart rate to a numerical value which is displayed via a 3-digit seven segment display. The designed HRM device is portable, durable and cost-effective. It can be used to monitor the human heart rate in both clinical and non-clinical environments with the advantage of being operated by non-professionals. The HRM system was tested in the laboratory and 50 samples of heart rates was analyzed to determine its performance level. The accuracy test results of the HRM device showed that the average error rate is 1.85%, when compared with a Blood Pressure Monitor. Hence, the performance of the HRM device is high with negligible error rate.