The goal of this project is to demonstrate the feasibility of using of acoustic shear wave motion for characterization of a nanoparticle and assembly of nanoparticles, and its/their interaction with a substrate. Such nanoparticle properties as size, mass or density, and the binding energy of a particle to the substrate are targetedparameters for measurements. An acoustic shear wave is generated by solid-state transducers, which provide a non-contact mean of delivering a mechanical force to the particle. This force, which extends from the transducer substrate into ambient air on the order on tens to hundreds of nanometers, excites a particle into a resonant motion. From the analysis of that resonant motion one can infer the above listed characteristic parameters of the particle. Specifically, several carefully designed experimental and theoretical efforts are proposed to study physical mechanisms of operation of an Acoustic Wave Nanoparticle Analyzer (AWNA).
Employed methods: The work proposed falls into three broad activities: device development, theoretical modeling and the concept validation. These three areas are not mutually exclusive and will proceed simultaneously. Device development includes design, fabrication and testing of the very high frequency shear wave transducers, electronics and software for efficient generation of mechanical interfacial forces. Theoretical models describing an interaction of a particle with the surface of a transducer will incorporate the Nanoscale complexity of the system and the multiple length scales of the systems to be studied. These developments will be validated using different models in which various aspects created by particle size and interfacial forces will be examined in carefully controlled or simulated experimental conditions. Finally, the measured acoustical responses will be correlated with standard optical (micron-size particles) and Atomic Force Microscope (AFM) techniques.
The intellectual merit of the proposed activity: Since many of the properties of nanometer-sized particles and features are not predictable from observation at a larger scale, the published work on the interaction of acoustic waves with macroscopic objects and our own preliminary data on micrometer sized particles cannot reliably suggest that same phenomena will be observed for nanoparticles. In addition, there are substantial theoretical difficulties because the reduced (finite) size of the nanostructural components, which is intermediate between the condensed-phase and molecular regimes, makes both continuum models and atomic model inapplicable directly to the nanoparticles. These challenges highlight the exploratory nature of this project. The acoustic shear wave nanoparticle analysis technique, once developed, will be complementary to current micro-and nano-particle techniques for nanoparticle separation, such as AFM or SEM. In particular, this technique will provide an efficient method for characterization of nanoparticles according to their size, shape or interaction properties. The acoustic shear wave analysis technique will be effective on nanoparticles regardless of their optical, electrical and magnetic properties, and thus can be used in various environments and in different media. These unique features of the acoustic nanoparticle analyzer will significantly impact the fields of characterization and application of nanoparticles. The long-term objective of this research is to develop an AWNA chip capable of autonomous and programmable analysis of nanoparticles in gases and liquids. AWNA chip will provide an experimental platform for analysis, design and monitoring of various biochemical and biophysical processes involving inorganic nanoparticles as well biological objects such as proteins or cells.
The broader impacts resulting from the proposed activity: Analysis of nanoparticles, in addition to its technological importance, brings an effective tool for teaching and publicizing nanotechnology. The proposed research and educational efforts will impact many areas and specifically, it will: (i) expand the knowledge on interfacial phenomena at the nanoscale level, (ii) provide a new research tool for analysis of nanoparticles, as well a new tool for nanofabrication processes, (iii) enhance awareness of nanotechnology by the public, (iv) enhance nanotechnology-oriented curricula by providing cost-effective instrumentation for laboratory experimentation, (v) attract more students to the area of nanotechnology (vi) due to its potential visual appeal (seeing moving particles), it will capture the imaginations of high school students, including those with limited interest in science (females and underrepresented ethnic groups), and as a result will attract more students to science and engineering, (vii) enhance collaborations among scientists in physics, biology, chemistry and engineering.
The category of the proposal in the NER program is "Nanoscale devices and system architecture".
