In this slide the finger probe with the two LEDs is shown, and the detector (photo diode) of the light that has not been absorbed by the finger, which feeds into the MSP430. Also, a self-contained system can be seen that is performing signal conditioning with the A/D converter, the op-amps, as well as the DAC, and providing some control to the LEDs. An integrated LCD driver is used to display the blood oxygenation or the heart rate of the patient. All of this powered by a coin cell.