MODELING AND OBSERVATION OF WAVE MODES IMPORTANT TO THE FUNCTIONING OF PIEZOELECTRIC MASS SENSORS

THE LONG-TERM OBJECTIVE OF THE PLANNED WORK IS TO PRODUCE ADVANCED CHEMICAL SENSORS FOR ENVIRONMENTAL MONITORING, INDUSTRIAL PROCESS CONTROL, AND OTHER POTENTIAL APPLICATIONS. THE OBJECTIVES OF PHASE I ARE TO PRODUCE AN ACCURATE MATHEMATICAL MODEL OF THE PHYSICAL AND ELECTRICAL BEHAVIOR OF SURFACE ACOUSTIC WAVE (SAW) MASS SENSORS IN ORDER TO ACHIEVE SIGNIFICANTLY IMPROVED DESIGNS. IT IS KNOWN THAT SAW SENSORS ARE ELECTRONIC DEVICES THAT RESPOND TO THE DEPOSITION OF MASS ON THEIR SURFACE. IN THIS RESEARCH PLAN THE PROPAGATION OF ACOUSTIC SURFACE WAVES THROUGH THIN PIEZOELECTRIC CRYSTALS WILL BE STUDIED TODETERMINE HOW MASS RESPONSE OCCURS IN THE PRESENCE OF A LIQUID AND HOW SUCH A RESPONSE CAN BE CONTROLLED. PRELIMINARY MODELS WILL BE PREPARED, AND THEIR PREDICTIONS WILL BE COMPARED WITH EXPERIMENTAL OBSERVATIONS OF ACOUSTIC WAVE VELOCITIES AND CRYSTAL PARTICLE DISPLACEMENTS.MODIFICATIONS TO THE MODEL AND EXPERIMENTAL MEASUREMENTS WILL BE MADE REPETITIVELY UNTIL THE TWO CONVERGE. THE MODEL WILL THEN BE EXTENDED TO ACCOUNT FOR THE PRESENCE OF THIN FILMS AND LIQUIDS ON THE SURFACE OF THE SAW DEVICES.THE SAME STRATEGY OF COMPARISON BETWEEN MODEL PREDICTIONS AND EXPERIMENT WILL BE APPLIED TO ENSURE MODEL ACCURACY. AFTER AN EXTENDED MODEL IS COMPLETED, IT WILL BE USED TO PREDICT A BEST SENSOR DESIGN, WHICH THEN WILL BE EXPERIMENTALLY TESTED AND OPTIMIZED THROUGH A SPECIALIZED EXPERIMENTAL DESIGN STRATEGY.