Arrays of such sensors are constructed with at least two sensors having {HEAD ~ different chemically sensitive resistors} providing {TAIL ~ dissimilar such differences} in resistance 
providing
Arrays of such sensors are constructed with at least two sensors having { HEAD ~ different chemically sensitive resistors } providing { TAIL ~ dissimilar such differences } in resistance
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH