Nanocell

Much of this chapter was adapted from the Rice University Ph.D. Thesis of Summer Husband, a student leading our NanoCell programming effort. Significant contributions from the Thesis work of Christopher Husband are also added. L. Wilson and J. Daniels of our Rice University NanoCell programming team contributed important findings, but to a lesser degree than Husband and Husband. 

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NANOCELL Nanocompounds application to design of fuel cell membranes. 

Self-Assembly in the NanoCell Approach to Molecular Computing... 

For the last two years our lab has focused on the NanoCell approach to molecular computing. We have shown via computer simulation that it is possible to program an assembled NanoCell.72 The NanoCell is illustrated in Figure 5.14. 

Once the physical topology of the self-assembly is formed in the NanoCell, it remains static there is no molecule or nanoparticle dynamic character (other than bond rotations or vibrations) to the highly crosslinked network. The only changeable behavior is in the molecular states conducting ON or non-conducting OFF, as set by voltage pulses from the periphery of the cell, or as defined by the search algorithms in these simulations. 

Several types of room temperature-operable molecular switches have been synthesized and demonstrated in nanopores and atop silicon-chip platforms. The functional molecular switches can be reversibly switched from an OFF state to an ON state, and/or the reverse, based on stimuli such as voltage pulses. The number of nanoparticles (usually metallic or semiconducting) and the number of the interconnecting molecular switches can vary dramatically based on the chosen size of the NanoCell and on the dimensions of the nanoparticles and molecules chosen.10... 

Training a NanoCell in a reasonable amount of time will be critical. Eventually, trained NanoCells will be used to teach other NanoCells. NanoCells will be tiled together on traditional silicon wafers to produce the desired circuitry. We expect to be able to make future NanoCells 0.1 pm2 or smaller if the input/output leads are limited in number, i.e. one on each side of a square. 

We have had problems with this approach to the NanoCell due to troubles getting the nanoparticles anchored in the molehole. In an alternative process, we fabricated a two-dimensional unit of juxtaposed Au electrodes atop a Si/Si02 substrate. A discontinuous Au film was vapor deposited onto the Si02 in the central region. Electrical measurements confirmed the absence of DC conduction paths across the discontinuous Au film between the pairs of 5 pm-spaced electrodes (< 1 picoamp up to 30 V). Each pair can serve as an independent memory bit address system. 

Molecular Dynamics Simulations of a Molecular Electronics Device The NanoCell (.J. Seminario, P. Derosa, L. Cordova B. Bozard)... 

Nanocell is the smallest electrochemical cell developed by Sugimura and Nakagiri [11] and further developed and utilized for ENT by BloeB et al. [10]. The nanocell consists of two electrodes distance between electrodes is generally maintained in the order of less than 1 nm. In between two electrodes, absorbed water film acts as an electrolyte whose volume is maintained by vapor pressure and ranges from 10 to 10 cm. Double layer capacitance is not formed across the solid liquid interface in the nanocell due to the much smaller inter-electrode gap and hence, generated hydrogen ion and hydroxyl ion recombine immediately. Nanotip of microtool such as tip of scanning probe microscope (SPM) or AFM tip is most suitable for the formation of electrochemical nanoceU. 

Due to ambient humidity, one or very few layers of absorbed water formed due to condensation results in the formation of water meniscus between the conductive tip and the substrate. Thus highly resistive electrolyte is formed by a thin water film in wet gas atmosphere which facilitates formation of nanostructures by oxidation of the metal substrate. The introduction of reference electrode in the electrochemical nanocell is not at all possible due to space constraint. A large potential drop in the electrolyte and at the counter electrode, i.e., AFM tip is encountered due to the absence of reference electrode. Several attempts have been made for nanostructure formation on metal substrates such as Si,... 

Ti, and Nb by AFM tip induced nano oxidation with the help of forming electrochemical nanocell. A typical nanocell utilizing AFM tip for formation of Si02 nanostmcture is shown in Fig. 13.3 [10]. Figure 13.3 schematically represents different phases of electrochemical nanocell where AFM tip acts as a cathode and Si substrate acts as an anode. 

The various reactions occur in nanocell due to the anodic oxidation of Si in pure water are as... 

Nanostructures fabricated by ENT (a) Nickel nanotubes [7] (b) square nanocells of AI2O3 [12] and (c) Si02 nanodots on silicon wafer [10],... 

H. BloeB, G. Staikov, J.W. Schultze, AFM induced formation of Si02 structures in the electrochemical nanocell, Electrochim. Acta 47 (2001) 335-344. 

J. M. Calderon-Moreno, T. Fujino, and M. Yoshimura, Carbon nanocells grown in hydrothermal fluids. 

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