Pulse oximeter for homecare

Noninvasive monitoring of arterial oxygen saturation by means of pulse oximeters is currently a routine procedure in a wide variety of medical disciplines. Particularly, oximetry tests are a reasonable means of first-line testing for sleep apnea. An oximeter with recording capabilities, designed for home usage, is very interesting for this purpose, allowing reduction of hospital wait lists. A set of specifications are required for this usage, including safety, accuracy, size and cost. In this paper we are going to show some techniques for reducing size and cost by using microcontrollers as the oximeter control unit. The use of an oscillator controlled by the photodetector signal will offer an important noise reduction in the signal adquisition. Processing saturation at every sample will reduce the necessity of precise cardiac pulse detection. Results have been compared with comertial oximeters, obtaining similar results with a more reduced circuitery.