The development of heart rate monitor using finger detector / Hanif Baki

This paper presents the development of heart rate monitoring using finger detector. The portable hardware consists of circuit design for heart rate is developed as a medical tool to measure the cardiovascular pulse wave that is found throughout the human body. An ordinary infrared LED / photodetector can sense this rhythmic change as small as but detectable variation in skin contrast. When gently held against the skin (too much pressure will flatten the surface capillaries and suppress the pulsation effect), some of the radiation from LED, reflects back into photodetector. Photodetector produces an analogue pulse for every 1% change in skin reflectance. This logarithmic relationship is constant over many orders of magnitude of photodetector. Consequently, reliable circuit operation is possible despite wide variations n skin contrast and light level. Oscilloscope is used to monitor the heart rate signal.