The fabrication of a designed arrangement of matter at the nano-scale level is a central goal of contemporary engineering endeavours. Silver nanoparticles synthesized by a laser ablation method in pure water are able to produce the aggregates, agglomerates and crystals due to condensed matter physics and chemistry. The stability of agglomerates and crystals is variable, depending on the composition of ensembles dominated by Ag2O and Ag respectively. The paper will present some fascinating nanostructures, such as films and vesicles.
Notable recent developments toward the realization of electronic nanocomputers have assembled logic circuits from semiconductor nanowires and individual carbon nanotube molecules. In spite of the broadly based and encouraging recent progress, a set of technical challenges still must be overcome to make a robust, commercially viable computer integrated on the molecular scale. The assembly of colloidal particles under an electric field offers many opportunities for the fabrication of ordered arrays, nanostructured films and microwires. We describe a method for the fabrication of gold nano/microstructures such as wires and dendrites on a lithographically patterned aluminium electrode with electric-field-induced assembly. The simple fabrication process will make these structures suitable for the miniaturisation of electronic circuits that can find application in sensors, actuators, and lab-on-a-chip devices. Our approach to electric-field-mediated fabrication exposes colloidal gold particles to the high electric field that can be generated between electrodes only 200 mm apart. We introduce an electric field of 100 Hz to 10 MHz by application of an alternating voltage of 5 to 10 V to the lithographically patterned microelectrodes. A suspension of gold nanoparticles of diameter 2.5 nm is added. We observe three types of fabrication, represented by three zones due to the different dielectophoretic force and convection effects. Some fibres grow through the liquid from one electrode toward the other, as could be seen in-situ by inverse optical microscopy. Dielectrophoretic-force-mediated fabrication, which is very flexible depending on the magnitudes of electric-field strength and frequency applied, has produced a notable advance in making mechanically flexible nano/microelectronic devices and led to a new understanding of the factors controlling the growth of nano/microstructures. When drops of suspension are patterned on the faces of components, three-dimensional structures can be generated. This type of system indicates how functional, self-assembling nano/microelectronic systems may be made. It provides a faster way of making devices, and the process can be very economical.
Stacking triblock copolymers as represented in Fig 1 would be extended more or less indefinitely in both directions to produce very long-range linear nanostructures. The concepts of template fabrication have become increasingly important, isotropic, anisotropic, or hierarchical structures can be obtained, depending on the type of template self-organization mechanism employed. The use of template structures to organise sol gel precursors opens up the huge potential for monolithic materials.
A 3 axis acceleration sensing system has been developed using force balance techniques based around 3 silicon capacitive accelerometers, a custom chip providing signal detection and control actuation and a DSP to implement the control algorithm. The accelerometers have a dual capacitor structure with a cantilevered central plate. The chip features a stray-insensitive switched capacitor integrator which uses synchronous detection to remove noise effects enabling the measurement of very small capacitance changes. On-chip digitization is provided by a sigma-delta converter. A DSP is used to implement a PID control algorithm providing force balance back to the accelerometers. The system has been modeled and simulated using combined mechanical and electrical models and the SABER mixed signal simulator. Good agreement has been obtained between simulated and measured frequency response for the capacitance accelerometers used. Simulations have identified the stable region of operation of the force balance system and enabled selection of the control coefficients. Both simulated and measured results are presented for the 3 axis system.