Sensor Application Using Longitudinal Mode of Screen-Printed PZT Cantilever

High gas sensitivity, expected when using the unusual longitudinal vibration mode of PZT cantilever for such application, is based on its higher resonant frequency when compared to transversal bending mode. For this purpose, a new PZT cantilever structure has been fabricated with thick-film technology based on the sacrificial layer method. This structure is well adapted to generate the 31's longitudinal vibration. Studies of the composition and microstructure of Au/PZT/Au beam show the harmlessness of the process. Advantage of the 31's longitudinal mode for gas detection is confirmed by the values of resonant frequency and good quality factor for a 8x2x0.08 mm(3) PZT based cantilever. Indeed, taking a 0.1Hz frequency resolution for the second 31 mode, the limit of detection of 6 ppm toluene is reached with a 44 mu m PEUT coating.