Design of Pulse Oximetry Based on Photoplethysmography and Beat Rate Signal Using DS-100 Probe Sensor for SpO2 Measurement

This paper presents the design of pulse oximetry to measure oxygen in blood saturation (SpO2) using an Arduino Uno module. The SpO2 measurement was conducted by acquiring the signal photoplethysmography (PPG) at the fingertip using a DS-100A probe consisting of an infrared (960 nm) and a red (640 nm) light sources, and also a photodiode. The signal of the photodiode is amplified and filtered with three frequency poles, i.e., 0.5 Hz, 1 Hz and 1.6 Hz. The result of the filtering shows that the PPG signal at the fingertip gives stable maximum and minimum values of 1.1697 volts and 1.1557 volts for red and 3.3946 volts and 3.3092 volts for infrared rays. From these results, the AC/DC voltage can be calculated for red and infrared lights resulting 98.26% SpO2 level, which states normal conditions. The maximum AC/DC voltage value occurs at the little finger and the minimum value occurs at the thumb finger. SpO2 signal was compared to the JZK-301 calibrator and shows the percentage error results ($\varepsilon$) less than 1% on each finger.