Noses are actually alarmingly complicated organs, and are also very poorly studied compared to other sensory organs. Progress on electronic noses has been slow

Noses are actually alarmingly complicated organs, and are also very poorly studied compared to other sensory organs. Progress on electronic noses has been slow to date, and existing devices tend to be fragile and expensive. http://en.wikipedia.org/wiki/Electronic_nose http://en.wikipedia.org/wiki/Electronic_nose