Design and Implementation of a Heart Rate Monitor

Abstract:

A heart rate monitor measures the heart beat. Heart beat is the number of heartbeat per unit time, and is expressed as beats per minute (BPM). The measurement of heart rate is used by medical professionals to assist in the diagnosis and tracking of medical conditions amongst other applications. This paper describes the design of a heart rate monitor which measures the heart rate from the finger using an optical sensor which consists of an infrared light-emitting-diode (IR LED) and a phototransistor. The IR LED transmits an infrared light into the fingertip, and the phototransistor senses the portion of the light that is reflected back, each heartbeat slightly alters the amount of reflected infrared light that can be detected by the phototransistor. A non-inverting amplifier is used to detect this little change in the amplitude of the reflected light. The pulses are filtered to remove unwanted signals, counted by Atmega16L microcontroller, and the result is displayed on a text based LCD in beats per minute. An experiment was performed that demonstrated an increase in heart rate as the human activity level increases. Tests were performed on ten children between ages 3 and 10 years. The average heart beat per minute were between 94 and 119. Tests were also performed on ten students with increased physical activity and they were found to have average heartbeat per minute of between 98 and 111.

• Periodical: Advanced Materials Research (Volume 824)
• Pages: 145-150
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.824.145
• Online since: September 2013
• Authors: J.A. Igimoh, Susan Konyeha
• Keywords: Heart Rate, LCD, Microcontroller, Pulse Rate

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