Real-time Voltage Mode Pulse Oximetry System

Pulse oximeters are widely used for measuring the oxygen level and heart-rate because of their noninvasive, low power, fast and accurate measurements. Here, we have developed a transimpedance amplifier based pulse oximeter which determines the SpO
2
and heart rate of the person. The transimpedance amplifier is being used to convert the generated photocurrent of photodetector into its respective voltage with the gain of 32 dB and having bandwidth of 125 Hz to form the PPG signal. With the proposed circuit, SpO
2
and heart-rate are being measured and compared with a commercial pulse oximeter (ZM-700-01). The accuracy for SpO
2
and heart-rate is to be found ±4% and ±2 bpm respectively, with the operating ranges of 70 – 100% for SpO
2
and 25 – 300 bpm for heart-rate. Then, the measured values are displayed on a 3.5 inch TFT LCD and also sent over a secure internet web server so that one can monitor the values on his/her mobile or desktop. Further, a prototype PCB is also designed and a prototype is developed.