Desenvolvimento de um oxímetro de pulso para avaliação da oxigenação sanguínea

Abstract

This work presents the development of a pulse oximeter, which is a medical device for the noninvasive measurement of peripheral oxygen saturation (SpO2) values. The paper covers topics such as the history of oximetry, the principle of operation using the spectrophotometry technique, the Beer-Lambert Law and calculations for measuring blood saturation. The development of the project is divided into steps beginning with the construction of a finger sensor model where it lies between the photodiode sensor and the light-emitting diodes of different wavelengths. The acquisition and treatment of the sampled signal are performed through an analog circuit composed of the following steps: current-to-voltage signal conversion, band reject filters, high-pass and low-pass filters, besides gain and offset voltage regulator at signal. With the conditioning of the oximetry signal the analog / digital conversion takes place using the Arduino platform, which performs serial communication with the MATLAB® software responsible for all the digital filtering process and calculation of the oxygen saturation rate in the blood. The presented project allows to understand the pulse oximetry and the implemented equipment presents itself as a didactic tool useful in the disciplines of biomedical engineering.