Design and Construction of an Electronic Heart Beat Monitor.
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Date
1986
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Publisher
Obafemi Awolowo University
Abstract
The design of safe monitors of physiological events in humans is of paramount importance in the field of medical electronics, and this report describes the development of a safe computer-based heart beat monitor for hospital use. The heart beats are detected by passing light through a finger into a photo-diode. Each time the heart beats, it pumps blood round the body and this causes the density of many parts of the body to vary, particularly the finger tips.
By passing light through the finger tip onto a photodiode, this variation in density is converted into electrical signal that varies with the heart beat. The output of the photodiode is amplified in detection and amplification circuit to produce a CMOS compatible pulse each time the heart beats.
An electronic method that does not employ a computer is first designed as a basis for comparison with the computer based method. In this method the time interval between successive three heart beats is measured and on the basis of the measured interval, the heart rate is computed by employing digital division method. This method, like others employing digital division method in computing the heart rate, has a reliable narrow operating frequency from 40 to 200 BPM, and a resolution of IBPM. Its main problem arises from truncation error.
In the computer based method, the heart beat detection and amplification circuit is interfaced with a digital micro-computer. The microcomputer is programmed to measure the time interval between successive three heart beats, to compute the heart beat rate and to provide both graphical and numerical indications of the heart beat rate. This method has a wide operating range (10 to 10920 BPM), and a resolution less than BPM.
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Keywords
Electronic heartbeat monitor, photodiode
Citation
APA