Detection of Heart Rate Using Reflectance Mode Photoplethysmography

This paper represents the working of a low-cost design of heart beat monitoring device using reflectance mode Photoplethysmography (PPG). PPG can provide information about the changes in cardiac activity as well as aid in earlier non-invasive diagnostics and is known for its simple construction, ease of use and cost effectiveness. The PPG device is divided into three parts. First is the detection of pulses through the fingertip using light dependent resistor and red LED. Second, the signal is passed to the signal processing unit for amplification, filtering and digitizing. Finally, the heart rate is calculated and displayed on the computer using LabView. The device is used to detect the variation of heart rate in sleep apnea condition.