SURFACE ACOUSTIC WAVE CHEMICAL MICROSENSORS FOR MONITORING AND CONTROL OF VAPOR PHASE INDUSTRIAL PROCESSES AND WASTE STREAMS AT HIGH TEMPERATURE AND PRESSURE

THIS PROJECT INVESTIGATES THE USE OF VERY SMALL, SENSITIVE SURFACE ACOUSTIC WAVE (SAW) MICROSENSORS AS HIGHLY LOCALIZED, RAPIDLY RESPONDING, IN-SITU CHEMICAL VAPOR SENSORS CAPABLE OF OPERATION AT HIGH TEMPERATURES AND PRESSURES. SAW MICROELECTRONIC DEVICES CURRENTLY UNDER DEVELOPMENT ARE AS SMALL AS A FEW SQUARE MILLIMETERS, HAVE RESPONSE TIMES OF ONLY A FEW SECONDS, AND ARE INHERENTLY STABLE AT HIGH TEMPERATURES. MULTIPLE SAW SENSOR ARRAYS, IN WHICH EACH SENSOR HAS A COATING WITH DIFFERENT CHEMICAL SELECTIVITY, COULD BE USED WITH SIMPLE PATTERN RECOGNITION SCHEMES TO MONITOR THE COMPOSITION OF MANUFACTURING PROCESSES, DETECT CHEMICAL CHANGES IN WASTE STREAMS, OR SIMPLY IDENTIFY SPECIFIC CHEMICAL VAPORS. HOWEVER, CURRENT STATE-OF-THE-ART SAW CHEMICAL MICROSENSORS ARE LIMITED ESSENTIALLY TO ANALYTICAL MEASUREMENTS AT OR NEAR AMBIENT TEMPERATURE, BECAUSE OF THE CHEMICALLY SELECTIVE ORGANIC COATINGS USED FOR THEIR SPECIFICITY AND SENSITIVITY. THE PRINCIPAL EFFORTS IN PHASE I ARE TO (1) DEVELOP CHEMICALLY SELECTIVE COATINGS BASED ON THE USE OF THERMALLY STABLE MATERIALS TO EXTEND THE NEW SAW TECHNOLOGY TO HIGH TEMPERATURE AND PRESSURE APPLICATIONS AND (2) EXPLORE INNOVATIVE SAW DESIGNS TO FURTHER REDUCE DEVICE SIZE AND IMPROVE PERFORMANCE. PHASE II WOULD BE AN ENGINEERING EFFORT TO FABRICATE PROTOTYPE SAW ARRAY SENSORS, INCORPORATING THE NEWLY DEVELOPED COATINGS AND DEVICE DESIGNS, FOR TEST AND EVALUATION IN EXTREME TEMPERATURE AND PRESSURE ENVIRONMENTS.