A Single-Chip Pulsoximeter Design Using the MSP430

This application report discusses the design of non-invasive optical plethysmography also called as pulsoximeter using the MSP430FG437 Microcontroller (MCU). The pulsoximeter consists of a peripheral probe combined with the MCU displaying the oxygen saturation and pulse rate on a LCD glass. The same sensor is used for both heart-rate detection and pulsoximetering in this application. The probe is placed on a peripheral point of the body such as a finger tip, ear lobe or the nose. The probe includes two light emitting diodes (LEDs), one in the visible red spectrum (660nm) and the other in the infrared spectrum (940nm). The percentage of oxygen in the body is worked by measuring the intensity from each frequency of light after it transmits through the body and then calculating the ratio between these two intensities.