Heart rate and blood oxygen monitoring

With a heart rate and blood oxygenation detection module as its core, the data reception, calculation, and transmission are controlled by an STM32F103C8T6 microcontroller. A dedicated sensor acquires heart rate and blood oxygenation samples; only data meeting the criteria is used. Based on the sampled data, the heart rate and blood oxygenation values ​​are calculated and displayed on an OLED screen along with their waveforms. Blood oxygenation measurement is mainly divided into transmissive and reflective methods, with transmissive methods currently being the mainstream, although their principles are similar. Both use light-emitting diodes (RED, IR, GREEN, and BLUE, etc.) to illuminate the measured area, and then a photodiode receives the transmitted/reflected light, converting the light signal into an electrical signal. A high-precision ADC then measures the reflected current to assess the oxygen content in the blood. The principle can be simplified as: light --> analog signal --> digital signal. Therefore, we need to control the current intensity and sampling rate of the LED light source, as well as the ADC accuracy (xbit) of the photosensitive sensor. This design is compact, lightweight, simple, and intuitive. Its watch-style design makes it easy to carry, and its high-frequency sampling sensor provides accurate data. An independent rechargeable lithium battery eliminates the hassle of cables. In short, this design has strong practical applications.