Not the pulse, if the green light for the heart rate sensor is on constantly just like the blood oxygen sensor, the battery would drain out very fast.I noticed that as well, in v1.0 (No powerbank case, just bare watch) i could run my finger over the bottom to wake or keep it on
I do wonder if it 'senses' just capacitance of skin to determine if its being worn, or if the sensor is detecting pulse before it decides it is being worn!
hmmmm
So it should be capacitive, man.