We are trying to build a circuit that can sense if a human is wearing the helmet(for motorbike) or not.....we are placing it inside the helmet so it needs to be really small. Which sensor should we use?
What's your budget? What's the risk of being wrong (saying helmet is on a human when it is not, or saying it is not on a human when it is on a human). What are the possible alternatives that could be a false positive (water balloon inside helmet, warm towel in the helmet - or is the helmet simply either empty or on a human)? How long can the sensor take to determine it is a human head inside the helmet?