Owing to the limitation associated with lithography based processes, fabrication of nanoscale structure by micromachining has been very difficult, and usually involves introducing large amount of surface damages onto the nanostructure due to the etching and oxidation processes. The effect of such damages is more prominent in the nanoscale structure as the surface to volume ratio is inversely proportional to r, for example, for a rod having a radius of r. This becomes the limiting factor in using such fabricated nanostructures for ultrahigh frequency and ultrahigh quality factor resonator applications. Surface damages serve as scattering centers for energy dissipation, thus the damping, in mechanical resonance system. In addition, the fabrication of uniform, suspended beam structure having a diameter around tens of nanometer is still a challenging task even for most advanced lithography facilities. Novel nanostructures, such as BN and C nanotubes, have attracted great attention recently due to their excellent mechanical, electrical and structural properties, which promises their applications in sensing, materials reinforcement, vacuum microelectronics, and micro- or nano- electromechanical systems (MEMS/ NEMS). The extremely small physical dimensions of such nanostructures imply theoretically high sensitivity to external perturbation, which is thus advantageous for femto-gram mass measurement, and bio-molecule and gas sensing. We intend to integrate such nanostructures with MEMS and to explore unique resonance principles to achieve ultrahigh frequency and ultrahigh sensitivity sensing.
The intellectual merits of the proposed research: The research objective of the proposed research is to study the resonance sensing behavior of unique nanomaterials and apply the discovery for the development of ultrahigh sensitivity sensor. The research implementation is based on the advanced research capability, the in situ free space nanomanipulation and characterization with electron microscopy, which allows the effective and flexible investigation and device-prototyping of multifunctional materials at the nanoscale; and the research fundamental is based on the principle of parametric resonance, which exhibits instability in its resonance behavior that will be utilized for amplifying extremely small perturbation. Overall, the research aims to realize and characterize the parametric resonance of individual nanotubes with nanomanipulation inside scanning electron microscope and transmission electron microscope; to prototype parametric resonance sensor integrated with excitation and sensing mechanisms, and to develop device with microfabrication of parametric resonance sensor incorporating nanotubes. The study will help to resolve the long standing experimental challenges, such as electronic sensing of electromechanical response at the nanoscale and device integration of nanomaterials for NEMS, facing the application of nanomaterials for high sensitivity resonance sensing.
The broader impact of the proposed research: The proposed study assimilates the forefront results in the development of advanced research capabilities and the study of novel nanomaterials to realize unique NEMS devices by applying advanced physics, mechanics, electronics and micromachining technology. The study aims to advance the current state of the art in mechanical resonance research to achieve extremely high sensitivity sensing. The research will extend the application of electromechanical sensing to a new level and to a new dimension never explored before, and will ultimately lead to the development of nanoscale sensor useful for single molecule level mass sensing and single charge electromechanical sensing. The methods and technologies developed in this study are broadly translatable to many other studies involving sensing and characterization at the nanoscale. Strongly coupled with this innovative and multidisciplinary research program is an educational initiative that will naturally introduce undergraduate students into scientific research, proactively promote the participation of woman and minority students, and effectively engage and disseminate scientific knowledge to the general public.
