title: Acoustic wave-based sensors using mode conversion in periodic gratings.
abstract: Using periodic gratings etched into the surface of a piezoelectric plate, surface acoustic waves (SAW) can be converted into bulk waves and vice versa with high efficiency. If parallel grating structures are fabricated on opposite surfaces of a piezoelectric plate, a SAW also can be directed from one surface to the other. Using such structures, acoustic wave-based sensors can be designed that utilize SAW for the detection of chemical analytes on an electrode-free surface, i.e., the back surface. As a result, spurious sensor response and electrode aging that may occur when a chemical analyte comes in contact with the transducers are minimized. The design principles of these grating-based SAW sensors are explained, and the mass sensitivity is investigated using chemical vapor deposited thin polymer films, a type of material used in many practical chemical sensor applications. Experimental results are presented for the detection of nitrogen dioxide (NO(2 )) in sub-ppm concentrations.
authors.affiliation: Angewandte Phys. Chem., Heidelberg Univ.
authors.forename: F
authors.initials: F
authors.lastname: Bender
authors.forename: R
authors.initials: R
authors.lastname: Dahint
authors.forename: F
authors.initials: F
authors.lastname: Josse