Preliminary results of the feasibility of hydrogen detection by the use of uncoated silicon microcantilever-based sensors

Hydrogen is a key parameter to monitor radioactive disposal facility such as the envisioned French geological repository for nuclear wastes. The use of microcantilevers as chemical sensors usually involves a sensitive layer whose purpose is to selectively sorb the analyte of interest. The sorbed substance can then be detected by monitoring either the resonant frequency shift (dynamic mode) or the quasi-static deflection (static mode). The objective of this paper is to demonstrate the feasibility of eliminating the need for the sensitive layer in the dynamic mode, thereby increasing the long-term reliability. The microcantilever resonant frequency allows probing the mechanical properties (mass density and viscosity) of the surrounding fluid and, thus, to determine the concentration of a species in a binary gaseous. Promising preliminary work has allowed detecting concentration of 200 ppm of hydrogen in air with non-optimized geometry of silicon microcantilever with integrated actuation and read-out.