Micro Converter Based Pulse Oximeter

The project utilizes ADuC7024 to produce a pulse oximeter that is a medical device used to measure the amount of oxygen in a patient’s blood.

The Pulse Oximetry is considered as the fifth vital sign of health status where its sensor has a pair of LED that face a photodiode through a translucent part of the patient’s body. This is in addition to heart rate, blood pressure, respiratory rate, and temperature. Based on the absorption rate from each wavelength of light after it passes through the patient’s body, the percentage of blood oxygen is calculated.

The device includes ADCs and DACs along with a microcontroller and associated memory in addition to analog signal conditioning circuitry. There are 32-bit ARM7TDMI core included in the microcontroller that runs at 41.8MHz and provides a very powerful computational platform. The LEDs are powered sequentially by a MOSFET bridge while the constant current sink is controlled by the DAC output of the Micro Converter.

The light received is converted into a voltage by the photodiode amplifier and is inversely proportional to the light absorbed by the patient’s tissue. Red and infrared wavelengths are making up the measurement alternatively.
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