Thin-film anodized aluminum on an acoustic sensor

An empirical model has been developed to predict the effect of a thin, porous anodized aluminum film on a solid-state flexural plate wave (FPW) chemical vapor sensor. A method of defining a precise anodization region using photolithography was developed. Initial experiments have shown through static measurements that a downward shift on the order of 100 kHz in the 4 MHz resonant frequency of the FPW device can be detected after aluminum anodization. Linear regression techniques were used to develop a model to predict frequency shift for given anodization parameters. Anodization variables investigated were anodization voltage and electrolyte concentration. The measured device frequency can be used to determine material properties of the anodized film.