Screen-Printed Microcantilevers Coated With Functionalized Mesocellular Foam Silica for Detection of Solvent Vapors

This work presents an application of mass-sensitive microcantilevers coated with a new alternative of sensitive materials that is hexamethyldisilazane functionalized mesocellular foam silica (HMDS-MCF-Si) for detection of solvent vapors. The microcantilevers (3 mm
$\times2$
mm
$\times0.1$
mm) based on a lead zirconate titanate (PZT) beam sandwiched by thin gold (Au) electrodes were fabricated by screen-printing. Mesocellular foam silica (MCF-Si) was synthesized and used as the sensitive material due to its high specific surface area and pore volume. This material was functionalized by hexamethyldisilazane (HMDS) to enhance hydrophobicity. By a small deposition of HMDS-MCF-Si, the obtained devices demonstrated longitudinal vibration mode with the quality factor of approximately 200 at ambient temperatures. Responsiveness of the microcantilever coated with HMDS-MCF-Si to each solvent vapor at room temperature was compared. The largest response was obtained from exposure to toluene vapor with the sensitivity of 0.85 ppm/ppmV (218 mHz/ppmV) and a limit of detection (LOD) of 28 ppmV. The sensitivity dropped by almost six times when exposed to the higher polar vapor of ethanol. Very low response to water vapor (0.05 ppm/ppmV) confirmed the hydrophobic behavior of HMDS-MCF-Si. Detectable performances under different vapors of our device can be utilized as a guide for developing sensitive materials and resonant microcantilever-based vapor sensors.