Manufacturing & Prototyping

Mechanically Induced Nucleation Improves Crystalline Quality During Melt Growth of Semiconductors

Significantly lower supercooling results in the ideal growth condition of single crystal nucleation. Marshall Space Flight Center, Alabama For certain semiconductors with important applications, the existing bulk crystal growth technique from the melt usually results in poor-quality multi-crystalline ingots that cause the typically low yield of the commercial growth process. The low-quality, multi-grained crystal growth is mainly caused by the large supercool of the melt, which prohibits the ideal growth condition that a small, single-crystal nucleus forms at the very tip and grows into a large single crystal. For instance, semi-insulating cadmium zinc telluride (CdZnTe) crystal is a highly promising material for room-temperature x-ray and gamma ray detectors. However, the major hurdle in using the CdZnTe crystals is its cost. The ability to pack many data acquisition channels (hundreds) with the stopping power for high-energy radiation requires large single crystals of CdZnTe.

Posted in: Briefs

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Fabrication of a Nanopipette Array for Biosensing

Ames Research Center, Moffett Field, California Development of biosensors is an active field due to a wide range of applications in lab-on-a-chip, diagnostics of infectious diseases, cancer diagnostics, environment monitoring, biodetection, and others. One of the strategies used for selective identification of a target is to preselect a probe that has a unique affinity for the target, or can uniquely interact or hybridize with the target — a lock and key approach. In this approach, one then needs a platform to support the probe and a recognizing element that can recognize the said interaction between the probe and the target. Electrical readout biosensors have gained much attention because, in principle, they can be made more compact than optical technologies.

Posted in: Briefs

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Fabrication of a Nanopipette Array for Biosensing

Ames Research Center, Moffett Field, California Development of biosensors is an active field due to a wide range of applications in lab-on-a-chip, diagnostics of infectious diseases, cancer diagnostics, environment monitoring, biodetection, and others. One of the strategies used for selective identification of a target is to preselect a probe that has a unique affinity for the target, or can uniquely interact or hybridize with the target — a lock and key approach. In this approach, one then needs a platform to support the probe and a recognizing element that can recognize the said interaction between the probe and the target. Electrical readout biosensors have gained much attention because, in principle, they can be made more compact than optical technologies.

Posted in: Briefs, Sensors

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Variable-Sweep-Wing Aircraft Configuration

There are significant improvements in structural, aerodynamic, and energy efficiency. Ames Research Center, Moffett Field, California Efficient aircraft designs are increasingly desired in order to support the continued growth of the air transportation industry. Continued expansion of this vital mode of transportation is threatened due to concerns over ever-increasing emissions, noise, and the demand for fuel. Current airport runway, ramp, and terminal facilities are increasingly constrained by encroaching growth and neighborhood environmental issues. The challenges associated with ever-increasing demand for air travel will require the development of aircraft that can fly efficiently over wide speed ranges, minimize their environmental impacts, offer the potential for sizing and growth relative to market demand, and make efficient use of constrained airport and airspace resources.

Posted in: Articles, Briefs, Aviation, Energy Efficiency

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Process for Coating Substrates With Catalytic Materials

This process can remove volatile organic compounds from indoor air in planes, automobiles, homes, and industrial plants. Langley Research Center, Hampton, Virginia This invention relates to the process of coating substrates with one or more components to form a catalyst; specifically, the process of layering one or more catalytic components onto a honeycomb monolith to form a carbon monoxide oxidation that combines CO and O2 to form CO2, or alternatively, a volatile organic compound oxidation catalyst that combines the compound and O2 to form CO2 and H2O.

Posted in: Briefs, TSP

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Portable Friction Stir Welding Machine

The machine is capable of butt-welding aluminum 1,100 workpieces 1/8 in. (≈3 mm) thick. Marshall Space Flight Center, Alabama A preliminary design of a portable friction stir welding (FSW) machine for use in space has been developed. The in-space FSW machine takes the form of a handheld router tool that is historically used in woodworking applications. With the design of the in-space FSW machine, the FSW tool is directly connected to the motor shaft while the motor is mounted to a small frame that supports the tool. The frame has handlebars that allow the operator to grasp the welder and maneuver it along a desired weld path. The key enabler of the in-space FSW machine is an innovative FSW tool design. The FSW tool is a fixed shoulder-to-shoulder bobbin tool that self-aligns and adjusts to the workpiece. The self-aligning and adjusting FSW (SAA-FSW) tool floats freely in the vertical direction, thereby eliminating any external axial load on the machine or operator. The total weight of the in-space FSW machine is 73 lb (≈33 kg), and it only requires one operator. The machine is capable of butt-welding aluminum 1,100 workpieces 1/8 in. (≈3 mm) thick.

Posted in: Briefs

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Multimode, Fiber-Coupled, Tungsten Silicide, Superconducting Nanowire Single-Photon Detector Array

Amorphous WSi allows a much greater active area due to lower incidence of nanowire constrictions. NASA’s Jet Propulsion Laboratory, Pasadena, California The superconducting nanowire single-photon detector (SNSPD) arrays created in this innovation were fabricated using a WSi nanowire process. A gold mirror layer is deposited on an oxidized silicon wafer, and amorphous-state WSi is sputtered from a compound target at a thickness of 5 nm. The WSi nanowire is embedded at the center of a three-layer vertical optical cavity consisting of two silica layers and a titanium oxide anti-reflective coating. The layer thicknesses were chosen, on the basis of simulations and measured material parameters, to optimize efficiency at the target communication wavelength of 1,550 nm, and to minimize the polarization dependence of the detector response.

Posted in: Briefs, TSP

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