AVS 53rd International Symposium
    MEMS and NEMS Monday Sessions
       Session MN+BI-MoA

Paper MN+BI-MoA4
Energy Dissipation in Chemically Functionalized Micromechanical Silicon Resonators

Monday, November 13, 2006, 3:00 pm, Room 2007

Session: Surface and Interface Science of MEMS and NEMS
Presenter: D. Sengupta, Cornell University
Authors: D. Sengupta, Cornell University
A.M. Richter, Cornell University
I.T. Clark, Cornell University
M.A. Hines, Cornell University
Correspondent: Click to Email
Chemically functionalized micro- or nanomechanical resonators have been proposed as the basis for low cost, high performance chemical or biological sensors; however, this application has been stymied, in part, by the relatively high rate of mechanical energy dissipation (i.e. relatively low quality factors or Q's) displayed by most micromechanical resonators. Importantly, quality factors plummet as the device size shrinks. In previous research, we showed that the Q of MHz-range micromechanical silicon resonators is sensitive to monolayer-level changes in surface chemistry; resonators terminated with a single monolayer of methyl groups have both good stability and high Q. In this talk, we report on efforts to introduce chemical functionality into these monolayers while preserving high-Q performance. In general, resonators functionalized with monolayers of "chemically interesting" species (e.g., -COOH terminated monolayers) display poor performance, as the chemically interesting functionality prevents the formation of a close-packed monolayer. To combat this problem, we have produced resonators functionalized with mixed organic monolayers that combine the chemically resistant methyl termination with a low density of more reactive species, such as 1,3-dioxan-2-ylethyl moieties. The chemistry to produce mixed monolayers was characterized by surface infrared spectroscopy, which confirmed the presence of chemically reactive species. The mechanical properties of micromechanical resonators functionalized with mixed organic monolayers were tested. The performance of functionalized devices in different chemical environments is reported.