Design, Fabrication, Assembly and Characterization of a SWNT Switch for Non-volatile Memory Applications

A SWNT based non-volatile nano-electromechanical bi-stable switch for memory applications is proposed and fabricated. Conventional E-beam lithography and microfabrication methods are used to fabricate the switch while modified electric field assisted directed assembly process is used to assemble the SWNTs on to these fabricated structures. In this bi-stable switch the actuation of states are achieved at the same voltage when compared to several other SWNT electromechanical devices. Further modifications to the existing design would result in Latches, Flip-Flops, registers, etc which are the back bones of a computer processor chip. These devices can also be incorporated with existing CMOS process to fabricate other volatile memory devices

Plasmonic Monopole Antenna Arrays for Biosensing, Spectroscopy and nm-Precision Optical Trapping

We propose surface plasmon polariton driven plasmonic monopole antenna array system for biosensing, nanospectroscopy and optical trapping. The structure exhibits high refractive index sensitivities, nearfield resolution and optical gradient force

Monopole antenna arrays for optical trapping, spectroscopy, and sensing

We introduce a nanoplasmonic platform merging multiple modalities for optical trapping, nanospectroscopy, and biosensing applications. Our platform is based on surface plasmon polariton driven monopole antenna arrays combining complementary strengths of localized and extended surface plasmons. Tailoring of spectrally narrow resonances lead to large index sensitivities (S similar to 675 nm/RIU) with record high figure of merits (FOM similar to 112.5). These monopole antennas supporting strong light localization with easily accessible near-field enhanced hotspots are suitable for vibrational nanospectroscopy and optical trapping. Strong optical forces (350 pN/W/mu m(2)) are shown at these hotspots enabling directional control with incident light polarization. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559620

Applications to regional tectonics: [chapter 11] /

Despite the interesting fundamental science of SERS, the promise of the technique as the basis for portable chemical sensors has not been fully realized yet. The reason for this gap between the science and engineering lies in the formidable nanofabrication challenges, which can be summed up as the need to prepare large numbers of very small yet highly controlled “hot spots” for the sensing device. In this work, we will describe newly-developed techniques for forming dense periodic two-dimensional plasmonic arrays for SERS sensing applications. These techniques utilize 157-nm interference lithography on a 90-nm pitch grid for 1) direct patterning of Ag nanocones and 2) convective assembly of Au nanoparticles into pre-patterned PMMA templates. Both fabrication methods result in a high areal density of plasmonic nano-gap “hot spots.” These arrays were used to achieve area-averaged Raman enhancement factor of adsorbed benzenethiol of ≥5 x 106. The fabrication process employed here is scalable to large areas, and therefore it can enable the manufacturing of highly sensitive chemical sensors that detect the greatly enhanced Raman scattering signal

Three-Dimensional Crystalline and Homogeneous Metallic Nanostructures Using Directed Assembly of Nanoparticles

Directed assembly of nano building blocks offers a versatile route to the creation of complex nanostructures with unique properties. Bottom-up directed assembly of nanoparticles have been considered as one of the best approaches to fabricate such functional and novel nanostructures. However, there is a dearth of studies on making crystalline, solid, and homogeneous nanostructures. This requires a fundamental understanding of the forces driving the assembly of nanoparticles and precise control of these forces to enable the formation of desired nanostructures. Here, we demonstrate that colloidal nanoparticles can be assembled and simultaneously fused into 3-D solid nanostructures in a single step using externally applied electric field. By understanding the influence of various assembly parameters, we showed the fabrication of 3-D metallic materials with complex geometries such as nanopillars, nanoboxes, and nanorings with feature sizes as small as 25 nm in less than a minute. The fabricated gold nanopillars have a polycrystalline nature, have an electrical resistivity that is lower than or equivalent to electroplated gold, and support strong plasmonic resonances. We also demonstrate that the fabrication process is versatile, as fast as electroplating, and scalable to the millimeter scale. These results indicate that the presented approach will facilitate fabrication of novel 3-D nanomaterials (homogeneous or hybrid) in an aqueous solution at room temperature and pressure, while addressing many of the manufacturing challenges in semiconductor nanoelectronics and nanophotonics

Template Directed Assembly of Polymer Blends into Nonuniform Geometries at Multiple Length Scales

CHN has developed a suite of templates and assembly processes for directing the assembly of a variety of nanoelements. These assembly processes utilize both electric fields and/or chemical functionalization. Chemically functionalized templates have been used to direct the assembly of polymer blends into uniform and nonuniform patterns. The selective assembly process can be finished in 30 seconds directly from a solution of the two polymers. Using a short solvent annealing step allows the assembly of multiple length scales on a single template. Electrophoretic and Dielectrophoretic assembly processes have been used to pattern conducting polymers followed by transfer to a secondary substrate. Conducting polymers and carbon nanotubes have been successfully transferred to a polymer substrate. The entire process of patterning and transfer takes less than five minutes, which is commercially relevant and can be utilized for real time processing