Are all the Spo2 Sensors can be in common used?   
                     No, Most of the Spo2 sensors are different, and below are the normal differences of the sensors:
1.    Base on the Chips: All ways have 660/905-2, 660/940-3, 660/805-3, 660/940-2 ect, they are all different.
2.   Base on the out put tech: Always have Analogy and Digital Technology, and they are different.
3.   Base on the Patients type: Have, Adult, Pediatrick, Infant and Neonate.
4.   Base on the body part of the sensor’s detected: Finger, Foot, Forehead and ear.
5.   Base on the times of the used: Disposable and Reusable.  
From these differences, you can see, most of the sensors are in different, It is not in common used.