SURFACE ACOUSTIC-WAVE VAPOR SENSORS BASED ON RESONATOR DEVICES

Surface acoustic wave (SAW) devices fabricated in the resonator configuration have been utilized as organic vapor sensors and compared with delay line devices more commonly used. The experimentally determined mass sensitivities of 200-, 300-, and 400-MHz resonators and 158-MHz delay lines coated with Langmuir-Blodgett (LB) films of poly(vinyl tetradecanal) are in excellent agreement with theoretical predictions. The responses of LB- and spray-coated sensors to various organic vapors were determined, and scaling laws for mass sensitivities, vapor sensitivities, and detection limits are discussed. The 200-MHz resonators provide the lowest noise levels and detection limits of all the devices examined.