Development of the Sensor Coating Materials and Application Techniques Necessary for On-Chip Chemical Analysis Using Solid-State Chemical

Many of the solid-state chemical microsensors, including surface acoustic wave (SAW) devices and the organic or inorganic semiconductors, are ideally suited as sensors for on-chip chemical analysis systems as they are inherently very small, low power and readily manufactured by photolithographic techniques. The major technical problems associated with the development of integrated chemical microsensor systems based on these devices is the lack of sufficiently sensitive and selective coating materials for the devices and the means to apply the coatings uniformly and reproductively to very specific, highly localized sites on a substrate surface. The approach to solving these technological issues will be based on the exciting new materials processing technique of Pulsed Lase Deposition (PLD). A unique advantage of PLD is that plumes of charged particles of coating material ablated by an excimer laser can be precisely focused on specific target locations and the amount deposited can be closely controlled. Another advantage of PLD is that many highly sorptive and selective materials that can not be applied by standard surface techniques, can be deposited by PLD. These include such materials as molecular sieves, high surface area carbons and certain organic polymers (flouorocarbons) that can not be easily dissolved or suspended in solvents. Phase I will focus on using PLD to prepare coatings of these new candidate materials and then performance as coatings on SAW devices. Pertinent characterization will include chemical sensitivity, selectivity, and reproducibility.