Heart-Rate Monitoring Using PIC16F72

Abstract

Heart rate measurement indicates the soundness of the human cardio-vascular system. The basic concept on which this project works is dependent on the concept of photopleythysmography( volumetric measurement of an organ .This project demonstrates a technique to measure the heart rate by sensing the change in blood volume in a finger artery while the heart is pumping the blood .It consist of an infrared LED that transmits an IR signal through fingertip of the subject parts of which is reflected by the blood cells .The reflected signal is detected by a photo diode sensors. The changing blood volume with heart beat results in a train of pulses at the output of the photodiode , the magnitude of which is to small to be detected directly by a micro-controller .Therefore , two – stage high gain ,active low pass filer is designed using Operational amplifier s (OpAmps) to filter and amplify the signal appropriate voltage level so that the pulses can be counted by micro –controller .The heart rate is displayed on 3 digit seven segment display . The micro –controller used in this project is PIC16F72.