Use of the longitudinal mode of screen-printed piezoelectric cantilevers coated with PEUT for toluene detection: Comparison with silicon cantilevers

Self-actuated and self-read-out piezoelectric cantilevers made of Au/PZT/Au (8 mm × 2 mm × 0.095 mm) beam layers on an alumina substrate are fabricated thanks to the association of screen-printing and sacrificial layer techniques. Then, PZT cantilevers used as piezoelectric resonant type sensors are functionalized with an organic PEUT layer (≈30 μm) for toluene detection at room temperature. The first and second unusual in-plane 31-longitudinal modes presenting high resonant frequencies (respectively 70 kHz and 214 kHz) and good quality factors (≈200) are used for toluene detection. Sensitivities and LOD are compared for both modes. Due to their higher resonant frequency, PZT cantilevers using these longitudinal vibration modes have higher sensitivities (15.0 mHz ppm−1 at 70 kHz) than those actuated with the classical flexural mode of silicon cantilever (0.9 mHz ppm−1 at 3 kHz). These interesting results demonstrate the potentialities of printed piezoelectric cantilevers for gas detection. Their performances are compared with those of silicon cantilevers actuated with transverse classical flexural modes.