Keywords

microcantilever, mercury, vapor detection

Abstract

We demonstrate the use of thermally induced higher order modes of a microcantilever as an alternate detection technique by studying Au-Hg interactions. The first four thermally induced flexural modes - i.e., the fundamental and first three higher order modes - have been examined for two different Au coatings. In the first case, 50 nm thick Au is sputter deposited along the entire length of a rectangular Si microcantilever. In the second case the Au is confined to a 30 µm length at the tip of the Si microcantilever. In both cases the microcantilever spectral response and deflection has been studied as a function of Hg concentration and total exposure time. For the low doses studied, the higher order modes show a distinct Hg sensing response whereas the fundamental mode does not. The frequency shift for the fourth order mode for a total exposure of 300 s to approximately 15 ppb Hg in N2 is found to be -320 and -70 Hz for the first and second cases, respectively.

Original Publication Citation

Ashwini. R. Kadam, G. P. Nordin, and Michael A. George, "Use of thermally induced higher order modes of a microcantilever for mercury vapor detection," J. Appl Phys. 99, 9495 (26)