AVS 56th International Symposium & Exhibition
    MEMS and NEMS Friday Sessions
       Session MN-FrM

Paper MN-FrM3
High-Q, In-plane Modes of Nanomechanical Resonators Operated in Air

Friday, November 13, 2009, 9:00 am, Room B3

Session: Multi-scale Interactions of Materials and Fabrication at the Micro- and Nano-scale
Presenter: P. Waggoner, Cornell University
Authors: P. Waggoner, Cornell University
C. Tan, Cornell University
L. Bellan, Cornell University
H. Craighead, Cornell University
Correspondent: Click to Email
Viscous damping is perhaps the greatest limitation on the applicability of nanomechanical resonant sensors, typically reducing device quality factors by several orders of magnitude when operated in air or liquid as compared to vacuum. In addition to degraded sensitivity due to lower quality factors, the viscous media also effectively adds mass to the sensors, shifting the resonant frequency and further decreasing sensitivity to added mass. In order to achieve real-time, ambient sensing of biological and chemical analytes, a solution to these problems must be achieved. We have fabricated arrays of 90 nm thick mechanical resonators, studied their resonance spectrum as a function of pressure, and found that some higher order resonant modes feature quality factors on the order of 2000 at atmospheric pressure, namely two symmetric, in-plane resonant modes. The side-to-side resonance of these trampoline-shaped resonators was confirmed using finite element analysis and by experimentally exciting device resonance non-uniformly. Even after deposition of a relatively thick polymer layer, the quality factor of the in plane mode in air only decreased slightly, suggesting that functional sensing layers can be used with devices operated in air. These encouraging results open the door for resonant micro- and nanoelectromechanical systems (NEMS & MEMS) to biosensor and chemical sensor applications at atmospheric pressure.