The sensing element can be coupled to a bottle of {TAIL ~ fluid}, or {HEAD ~ a carrier} with a timer 
The sensing element can be coupled to a bottle of { TAIL ~ fluid } , or { HEAD ~ a carrier } with a timer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH