Special Coverage

Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines

Nano-Engineered Catalysts for Direct Methanol Fuel Cells

Small particle sizes and large surface areas can be produced economically and consistently.

Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W•h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity.

Posted in: Briefs, TSP, Materials, Catalysts, Fuel cells, Methanol, Fabrication, Nanotechnology

Capillography of Mats of Nanofibers

These mats can be the basis of small devices and instruments.

Capillography (from the Latin capillus, “hair”, and the Greek graphein, “to write”) is a recently conceived technique for forming mats of nanofibers into useful patterns. The concept was inspired by experiments on carpetlike mats of multiwalled carbon nanotubes. Capillography may have the potential to be a less-expensive, less- time-consuming alternative to electron- beam lithography as a means of nanoscale patterning for the fabrication of small devices and instruments.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fabrication, Fibers, Nanomaterials

HEMT Amplifiers and Equipment for Their On-Wafer Testing

Power levels in CPW circuits can be measured without packaging.

Power amplifiers comprising InP-based high-electron-mobility transistors (HEMTs) in coplanar-waveguide (CPW) circuits designed for operation at frequencies of hundreds of gigahertz, and a test set for on-wafer measurement of their power levels have been developed. These amplifiers utilize an advanced 35-nm HEMT monolithic microwave integrated-circuit (MMIC) technology and have potential utility as local- oscillator drivers and power sources in future submillimeter-wavelength heterodyne receivers and imaging systems. The test set can reduce development time by enabling rapid output power characterization, not only of these and similar amplifiers, but also of other coplanar-waveguide power circuits, without the necessity of packaging the circuits.

Posted in: Briefs, Semiconductors & ICs, Amplifiers, Integrated circuits, Amplifiers, Integrated circuits, Test procedures

On-Wafer Measurement of a Silicon-Based CMOS VCO at 324 GHz

Compact, low-power, electronically tunable submillimeter-wave local oscillators are now feasible.

The world’s first silicon- based complementary metal oxide/semi- conductor (CMOS) integrated-circuit voltage-controlled oscillator (VCO) operating in a frequency range around 324 GHz has been built and tested. Concomitantly, equipment for measuring the performance of this oscillator has been built and tested. These accomplishments are intermediate steps in a continuing effort to develop low-power- consumption, low-phase-noise, electronically tunable signal generators as local oscillators for heterodyne receivers in submillimeter-wavelength (frequency > 300 GHz) scientific instruments and imaging systems. Submillimeter-wavelength imaging systems are of special interest for military and law-enforcement use because they could, potentially, be used to detect weapons hidden behind clothing and other opaque dielectric materials. In comparison with prior submillimeter-wavelength signal generators, CMOS VCOs offer significant potential advantages, including great reductions in power consumption, mass, size, and complexity. In addition, there is potential for on-chip integration of CMOS VCOs with other CMOS integrated circuitry, including phase-lock loops, analog-to-digital converters, and advanced microprocessors.

Posted in: Briefs, TSP, Semiconductors & ICs, Amplifiers, Imaging, Imaging and visualization, Integrated circuits, Semiconductor devices, Amplifiers, Imaging, Imaging and visualization, Integrated circuits, Semiconductor devices, Silicon alloys

High-Voltage, Asymmetric-Waveform Generator

This circuit would be optimized for a capacitive load.

The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers.

Posted in: Briefs, TSP, Electronics & Computers, Capacitors, High voltage systems, Spectroscopy, Switches, Capacitors, High voltage systems, Spectroscopy, Switches, Test equipment and instrumentation

Group-III Nitride Field Emitters

Growing group-III nitride films spontaneously split into columns.

Field-emission devices (cold cathodes) having low electron affinities can be fabricated through lattice- mismatched epitaxial growth of nitrides of elements from group III of the periodic table. Field emission of electrons from solid surfaces is typically utilized in vacuum microelectronic devices, including some display devices. The present field-emission devices and the method of fabricating them were developed to satisfy needs to reduce the cost of fabricating field emitters, make them compatible with established techniques for deposition of and on silicon, and enable monolithic integration of field emitters with silicon-based driving circuitry.

Posted in: Briefs, Electronics & Computers, Electronic equipment, Electronic equipment, Displays, Displays, Fabrication

Magic-T Junction Using Microstrip/Slotline Transitions

Economical broadband junctions have potential utility in diverse microwave systems.

An improved broadband planar magic-T junction that incorporates microstrip/slotline transitions has been developed. In comparison with a prior broadband magic-T junction incorporating microstrip/slotline transitions, this junction offers superior broadband performance. In addition, because this junction is geometrically simpler and its performance is less affected by fabrication tolerances, the benefits of the improved design can be realized at lower fabrication cost. There are potential uses for junctions like this one in commercial microwave communication receivers, radar and polarimeter systems, and industrial microwave instrumentation.

Posted in: Briefs, TSP, Electronics & Computers, Connectors and terminals, Waveguides, Connectors and terminals, Waveguides, Fabrication

Improved Gas Filling and Sealing of an HC-PCF

Compact hermetic joint is formed to seal connectorized all-fiber gas reference cell.

An improved packaging approach has been devised for filling a hollow-core photonic-crystal fiber (HC-PCF) with a gas, sealing the HC-PCF to retain the gas, and providing for optical connections and, optionally, a plumbing fitting for changing or augmenting the gas filling. Gas-filled HC-PCFs can be many meters long and have been found to be attractive as relatively compact, lightweight, rugged alternatives to conventional gas-filled glass cells for use as molecular-resonance frequency references for stabilization of lasers in some optical-metrology, lidar, optical-communication, and other advanced applications. Prior approaches to gas filling and sealing of HC-PCFs have involved, variously, omission of any attempt to connectorize the PCF, connectorization inside a vacuum chamber (an awkward and expensive process), or temporary exposure of one end of an HC-PCF to the atmosphere, potentially resulting in contamination of the gas filling. Prior approaches have also involved, variously, fusion splicing of HC-PCFs with other optical fibers or other termination techniques that give rise to Fresnel reflections of about 4 percent, which results in output intensity noise.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Fiber optics, Fiber optics, Gases, Refractory materials, Reliability, Reliability

Thermal Spray Formation of Polymer Coatings

This innovation forms a sprayable polymer film using powdered precursor materials and an in-process heating method. This device directly applies a powdered polymer onto a substrate to form an adherent, mechanically-sound, and thickness-regulated film. The process can be used to lay down both fully dense and porous, e.g., foam, coatings. This system is field-deployable and includes power distribution, heater controls, polymer constituent material bins, flow controls, material transportation functions, and a thermal spray apparatus.

Posted in: Briefs, Manufacturing & Prototyping, Coatings Colorants and Finishes, Coatings, colorants, and finishes, Polymers

Embedded Computing Options Meet Rugged Industrial Requirements

While industrial applications typically require high levels of reliability, availability, ruggedness, and longevity, there often is a set of unique system requirements dependent upon the specific goals of the system. For instance, an industrial automation application may call for a particular I/O interface or the ability to support custom control software.

Posted in: Articles, Electronics & Computers, Automation

The U.S. Government does not endorse any commercial product, process, or activity identified on this web site.