Simple measurement system for non-contact oxygen saturation measurement

We propose a method of non-contact oxygen saturation measurement, which is simpler and less expensive than conventional camera methods. We constructed a simple system using a camera lens and a phototransistor. We considered that measurement with this system is possible using pulse oximetry to calculate percutaneous oxygen saturation. In order to confirm whether change in oxygen saturation can be measured using the proposed system, we conducted a breath holding experiment and performed measurements simultaneously using the proposed system and a transmission pulse oximeter. The experiment was conducted in a lighted room with the subject sitting in a chair. The subject breathed for 2 minutes and then held the breath for as long as possible. Measurement was continued for 3 minutes after the subject resumed breathing. For the proposed system, the measurement target was the left-hand middle finger nail, and the distance from the camera lens to the pedestal on which the measurement target was placed was set at 100 mm. The pulse oximeter was attached to the little finger of the left hand. From the results of the experiment, the proposed system showed a general response in which the oxygen saturation level decreased when a subject held the breath and gradually returned to normal level when breathing was resumed. These findings suggest that the proposed method is able to estimate oxygen saturation in a non-contact manner. © 2019, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved.