Polymer coated thin film plate acoustic resonators (FPAR) for gas sensing applications

Abstract

Mass sensitivity of thin aluminum nitride (AlN) film S0 plate wave resonators is theoretically and experimentally studied. Here, two-port 888MHz synchronous thin film plate acoustic resonators (FPAR) are micromachined and subsequently coated with plasma-polymerized hexamethyldisiloxane (pp-HMDSO) thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented in a comparative manner. Measurements in gas phase environment are further presented in a comparative manner.

Influence of liquid properties on the performance of S0-mode Lamb wave sensors: A theoretical analysis

“…It is then of crucial importance to consider the noise present in this oscillating circuit, since it directly affects the accuracy with which we are able to measure the resonant frequency. Therefore the resolution, being directly related to the noise present in the system, can be determined as [22]:…”

“…where δ is called limit of detection or normalized smallest detectable change in the measured signal (Δf min /f 0 ) in the presence of noise. δ can be estimated as three times the noise floor (σ у (τ) min ) [22].…”

Thin film electroacoustic resonators for physical and chemical sensing

“…Initially they were exploited in delay line configurations [113], and more recently very high mass sensitivities were proved with AlN-based LWR [85].…”

“…Their detailed description, together with some fundamentals of EA resonators, is performed in Chapter 2. The other important sensor parameters are the following [85]:…”

“…It is then of crucial importance to consider the noise present in this oscillating circuit, since it directly affects the accuracy with which we are able to measure the resonant frequency. Therefore the resolution, being directly related to the noise present in the system, can be determined as [85]:…”