Though resonant, electromechanical nanosystems have been shown to offer distinct potential in applications ranging from radio-frequency (RF) filtering to highly-sensitive mass sensing, their practical implementation is currently impeded by the comparatively-small output signals they produce, and by their comparatively-low quality (Q) factors of resonance. While on-chip, low-noise amplifiers can be used to partially negate these constraints, an alternative, and in many ways more attractive approach, is to realize output signals of sufficient (usable) amplitude by exploiting dynamic phenomena, namely parametric amplification and/or parametric resonance, within the resonators themselves.
The proposed project, incorporating both analytical and experimental activities, seeks to investigate the nonlinear dynamics and stability of parametrically-excited, high-frequency nanoelectromechanical systems (NEMS), such as nanotube and nanowire resonators, in order to significantly improve their performance in emerging applications such as nanomechanical, radio-frequency (RF) signal processing, nanomechanical mass detection, and ultra-fast sensing and actuation. The research effort will initially focus on the development of multi-physics, distributed-parameter models of representative, electrostatically-actuated nanoelectromechanical devices. These models, incorporating realistic noise sources, will be systematically discretized and analyzed using standard perturbation methods. The results of these analyses will be used to identify regions of stable and unstable operation, to develop predictive design tools, and to distill promising device designs. Single-walled carbon nanotube resonators based on these designs will be subsequently fabricated and tested, using the fabrication and electrical characterization suites available at Purdue University?s Birck Nanotechnology Center, to verify predicted dynamic behaviors. Ultimately, the work will develop a refined understanding of the complex nonlinear behaviors associated with parametric effects at the nanoscale and, with this understanding in hand, will actively exploit these nonlinear behaviors to realize improved performance metrics and device outputs of sufficient amplitude to be of use in practical implementation.
To ensure the rapid distribution of pertinent research results, the project will leverage the cyber-infrastructure of the nanoHUB, the science portal of the NSF?s Network for Computational Nanotechnology (NCN), which provides online services for research, learning, and collaborations. Specifically, the PI?s will develop and deploy on the nanoHUB a comprehensive software tool for the simulation of nanotube/nanowire resonators with different geometric configurations, material properties, transduction mechanisms, and noise sources. Scientists and students working worldwide will be able to use this tool to predict the dynamic range, nonlinear phenomena, mixing/filtering, and noise effects of such resonators, leading to the better design of nanoelectromechanical systems. The online tool will be supplemented by freely-available, online user guides, tutorials, and an introductory lecture on ?Micro and Nanoresonators?. These resources, with others, will be profitably utilized in the development of a new class focusing on the dynamics of MEMS/NEMS, as well as tutorials that the PIs intend to offer at major international conferences. Under-represented undergraduate students will assist in the development of the online resources through specifically targeted SURF (summer undergraduate research fellowship) endeavors at Purdue University.
