Setup 1

A variety of designs were used to test our pulse oximeter in its preliminary stages. The configuration with one photodiode and 2 LEDs (see diagram below) was used as the base model since buttons were being used to turn the LEDs on and off rather than pulsing them. A black t-shirt is used to cover the device because the walls of our setup were made out of perforated boards, which had holes in them. This early stage of our pulse oximeter had no issues in sensing the infrared LED since the photodiode wavelength detection curve peaked at 940nm. Initially, the values given from sensing the red LED were too small and resulted in oxygen saturation percentages over 100%. The problem was solved using a brighter red LED and scaling it’s values to a working pulse oximeter. With the changes implemented, our device can consistently produce oxygen saturation percentages that are similar to a working pulse oximeter. However, we have not properly tested cases in which oxygen saturation would be lower than typical levels.