“…These materials are now predominantly used instead of quartz not only because they have more advantageous costs, but also because of their different piezoelectric properties, which ‒for the latter PbZr x Ti 1−x O 3 family‒ can also be changed by adjusting the composition of the material, and can also exhibit other useful sensing properties, e.g., pyroelectricity. Moreover, SAW sensors can also be realized as thin-film bulk acoustic resonators (FBARs or TFBARs) using the previous materials or others, such as aluminum nitride (AlN) and zinc oxide (ZnO), which can be easily coated on top of other devices or materials, such as Si wafers, thus offering better capability of integration in LOC smart systems [51,52,53,54,55,56] and/or with signal processing integrated circuits (ICs).While a great number of both QCM & SAW realizations have been reported, here just a few relevant illustrative examples will be given.…”