Langasite-based surface acoustic wave resonator for acetone vapor sensing

High concentration of acetone sensing is of an increasing interest due to its particular application in health monitoring for medical use as well as chemical industries. This paper proposes an advanced sensor that is based off of a Langasite (LGS) surface acoustic wave (SAW) resonator for acetone vapor sensing/detection. The detection of acetone vapor is based off of the chemo-resistive adsorption of pre-installed air on the LGS resonator surface, which will be significantly reduced via chemical reaction and lead to resonant frequency drift of the resonator. Lab tests of acetone vapor sensing are carried out with various concentration at various operating temperature (50 degrees C-200 degrees C). The sensitivity is investigated numerically and experimentally, where a rigorous proportionality between frequency drift and acetone concentration is observed and the temperature effect is further discussed. Compared to the conventional SAW gas sensor, the proposed acetone sensor employs the SAW piezoelectric substrate, LGS, as the sensing material, which not only eliminates the use of extra sensing thin film and consequently reduce the cost of fabrication, but also provides a promising high temperature stability due to the nature of LGS. Therefore, the proposed acetone sensor is of low cost, high sensitivity, and low maintenance, which can be further miniaturized and simplified for MEMS application and real environment acetone sensing in health monitoring.