Hydrogen bond acidic polymers for surface acoustic wave vapor sensors and arrays

Four hydrogen bond acidic polymers are examined as sorbent layers on acoust ic wave devices for the detection of basic vapors. A polysiloxane polymer w ith pendant hexafluoro-2-propanol groups and polymers with hexafluorobisphe nol groups linked by oligosiloxane spacers yield sensors that respond more rapidly and with greater sensitivity than fluoropolyol, a material used in previous SAW sensor studies. Sensors coated with the new materials all reac h 90% of full response within 6 s of the first indication of a response. Un supervised learning techniques applied to pattern-normalized sensor array d ata were used to examine the spread of vapor data in feature space when the array does or does not contain hydrogen bond acidic polymers. The radial d istance in degrees between pattern-normalized data points was utilized to o btain quantifiable distances that could be compared as the number and chemi cal diversity of the polymers in the array were varied. The hydrogen bond a cidic polymers significantly increase the distances between basic vapors an d nonpolar vapors when included in the array.