Thermal transport in 2D and 3D nanowire networks

We report on thermal transport properties in 2 and 3 dimensions interconnected nanowire networks (strings and nodes). The thermal conductivity of these nanostructures decreases in increasing the distance of the nodes, reaching ultra-low values. This effect is much more pronounced in 3D networks due to increased porosity, surface to volume ratio and the enhanced backscattering at 3D nodes compared to 2D nodes. We propose a model to estimate the thermal resistance related to the 2D and 3D interconnections in order to provide an analytic description of thermal conductivity of such nanowire networks; the latter is in good agreement with Molecular Dynamic results

Cumulene Molecular Wire Conductance from First Principles

We present first principles calculations of current-voltage characteristics (IVC) and conductance of Au(111):S2-cumulene-S2:Au(111) molecular wire junctions with realistic contacts. The transport properties are calculated using full self-consistent ab initio NEGF-DFT methods under external bias. The conductance of the cumulene wires shows oscillatory behavior depending on the number of carbon atoms (double bonds). Among all conjugated oligomers, we find that cumulene wires with odd number of carbon atoms yield the highest conductance with metallic-like ballistic transport behavior. The reason is the high density of states in broad LUMO levels spanning the Fermi level of the electrodes. The transmission spectrum and the conductance depend only weakly on applied bias, and the IVC is nearly linear over a bias region from +1 to -1 V. Cumulene wires are therefore potential candidates for metallic connections in nanoelectronic applications.Comment: Accepted in Phys. Rev. B; 5 pages and 6 figure

First Principles Study of Work Functions of Double Wall Carbon Nanotubes

Using first-principles density functional calculations, we investigated work functions (WFs) of thin double-walled nanotubes (DWNTs) with outer tube diameters ranging from 1nm to 1.5nm. The results indicate that work function change within this diameter range can be up to 0.5 eV, even for DWNTs with same outer diameter. This is in contrast with single-walled nanotubes (SWNTs) which show negligible WF change for diameters larger than 1nm. We explain the WF change and related charge redistribution in DWNTs using charge equilibration model (CEM). The predicted work function variation of DWNTs indicates a potential difficulty in their nanoelectronic device applications.Comment: 11 pages, 3 figures, to appear as rapid communication on Physical Review

Synthetic Nanoelectronic Probes for Biological Cells and Tissues

Research at the interface between nanoscience and biology could yield breakthroughs in fundamental science and lead to revolutionary technologies. In this review, we focus on the interfaces between nanoelectronics and biology. First, we discuss nanoscale field effect transistors (nanoFETs) as probes to study cellular systems; specifically, we describe the development of nanoFETs that are comparable in size to biological nanostructures involved in communication through synthesized nanowires. Second, we review current progress in multiplexed extracellular sensing using planar nanoFET arrays. Third, we describe the designs and implementation of three distinct nanoFETs used to perform the first intracellular electrical recording from single cells. Fourth, we present recent progress in merging electronic and biological systems at the three-dimensional tissue level by use of macro-porous nanoelectronic scaffolds. Finally, we discuss future developments in this research area, unique challenges and opportunities, and the tremendous impact these nanoFET-based technologies might have on biological and medical sciences.Chemistry and Chemical BiologyEngineering and Applied Science