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Block Copolymers as Templates for Arrays of Carbon Nanotubes

The spontaneous formation of nanostructures in block copolymers would be exploited. A method of manufacturing regular arrays of precisely sized, shaped, positioned, and oriented carbon nanotubes has been proposed. Arrays of carbon nanotubes could prove useful in such diverse applications as communications (especially for filtering of signals), biotechnology (for sequencing of DNA and separation of chemicals), and micro- and nanoelectronics (as field emitters and as signal transducers and processors). The method is expected to be suitable for implementation in standard semiconductor-device fabrication facilities.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Electrophoretic Deposition for Fabricating Microbatteries

Discharge capacities can be much greater than those achieved previously. An improved method of fabrication of cathodes of microbatteries is based on electrophoretic deposition. Heretofore, sputtering (for deposition) and the use of photoresist and liftoff (for patterning) have been the primary methods of fabricating components of microbatteries. The volume of active electrode material that can be deposited by sputtering is limited, and the discharge capacities of prior microbatteries have been limited accordingly. In addition, sputter deposition is slow. In contrast, electrophoretic deposition is much faster and has shown promise for increasing discharge capacities by a factor of 10, relative to those of microbatteries fabricated by prior methods.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Tool For Friction Stir Tack Welding of Aluminum Alloys

The same setup can be used for tack welding and full friction stir welding. A small friction-stir- welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Improving Plating by Use of Intense Acoustic Beams

This method affords enhanced capabilities for maskless plating and process control. An improved method of selective plating of metals and possibly other materials involves the use of directed high-intensity acoustic beams. The beams, typically in the ultrasonic frequency range, can be generated by fixed- focus transducers (see figure) or by phased arrays of transducers excited, variously, by continuous waves, tone bursts, or single pulses. The nonlinear effects produced by these beams are used to alter plating processes in ways that are advantageous.

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Fabricating Composite-Material Structures Containing SMA Ribbons

Repeatable, predictable structures can be fabricated. An improved method of designing and fabricating laminated composite-material (matrix/fiber) structures containing embedded shape-memory-alloy (SMA) actuators has been devised. Structures made by this method have repeatable, predictable properties, and fabrication processes can readily be automated.

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Pressure-Sensor Assembly Technique

An essential underfilling step can be performed without compromising a diaphragm. Nielsen Engineering & Research (NEAR) recently developed an ultrathin data acquisition system for use in turbomachinery testing at NASA Glenn Research Center. This system integrates a microelectro- mechanical-systems- (MEMS-) based absolute pressure sensor [0 to 50 psia (0 to 345 kPa)], temperature sensor, signal-conditioning application-specific integrated circuit (ASIC), microprocessor, and digital memory into a package which is roughly 2.8 in. (7.1 cm) long by 0.75 in. (1.9 cm) wide. Each of these components is flip-chip attached to a thin, flexible circuit board and subsequently ground and polished to achieve a total system thickness of 0.006 in. (0.15 mm). Because this instrument is so thin, it can be quickly adhered to any surface of interest where data can be collected without disrupting the flow being investigated.

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Wafer-Level Membrane-Transfer Process for Fabricating MEMS

This process is well suited for structures fabricated on dissimilar substrates. A process for transferring an entire wafer-level micromachined silicon structure for mating with and bonding to another such structure has been devised. This process is intended especially for use in wafer-level integration of microelectro- mechanical systems (MEMS) that have been fabricated on dissimilar substrates.

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