High temperature piezoelectric bulk acoustic wave mass sensor for thermogravimetric analysis of nano-layer polymer

The acoustic wave (AW) sensors can response to a physical, chemical, or biological stimulus in a sensitive and real-time manner, so they have drawn increasing attraction in recent years. Among the AW sensors, the piezoelectric ones show a lot of extraordinary merits such as high resolution, wide frequency and temperature ranges, high stability, low power consumption, and low cost, and they are able to sense many physical and chemical quantities such as temperature, pressure, mass, gas concentration, and liquid viscosity [1-3]. To date, many surface acoustic wave (SAW) sensors [4], thin film bulk acoustic resonators (FBAR) [5], and bulk acoustic wave (BAW) [6] sensors have been reported as mass sensors. Compared to the former two types, BAW mass sensors are with the property of simple preparation process, easy to use, high temperature-tolerance, high repeatability and durability, and little damping, because neither the interdigitated transducers (IDTs) nor the functional piezoelectric thin film is needed. Therefore, piezoelectric BAW mass sensors that can be used at elevated temperature range are ideal devices for thermogravimetric analysis (TGA) applications.