Physical Sciences

On-Chip Microfluidic Components for In Situ Analysis, Separation, and Detection of Amino Acids

This innovation can be integrated in a lab-on-a-chip device for biological and analytical instruments. The Astrobiology Analytical Laboratory at GSFC has identified amino acids in meteorites and returned cometary samples by using liquid chromatography-electrospray ionization time-of-flight mass spectrometry (LCMS). These organic species are key markers for life, having the property of chirality that can be used to distinguish biological from non-biological amino acids. One of the critical components in the benchtop instrument is liquid chromatography (LC) analytical column. The commercial LC analytical column is an over-250-mm-long and 4.6-mm-diameter stainless steel tube filled with functionized microbeads as stationary phase to separate the molecular species based on their chemistry. Miniaturization of this technique for spaceflight is compelling for future payloads for landed missions targeting astrobiology objectives.

Posted in: Physical Sciences, Briefs, TSP

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CRUQS: A Miniature Fine Sun Sensor for Nanosatellites

Size, mass, and power make the sensor suited to small satellite applications, especially nanosatellites. A new miniature fine Sun sensor has been developed that uses a quadrant photodiode and housing to determine the Sun vector. Its size, mass, and power make it especially suited to small satellite applications, especially nanosatellites. Its accuracy is on the order of one arcminute, and it will enable new science in the area of nanosatellites.

Posted in: Physical Sciences, Briefs, TSP

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Spectroscopic Determination of Trace Contaminants in High-Purity Oxygen

A glow discharge emission system is used to detect and quantify trace amounts of argon in pure oxygen. Oxygen used for extravehicular activities (EVAs) must be free of contaminants because a difference in a few tenths of a percent of argon or nitrogen content can mean significant reduction in available EVA time. These inert gases build up in the extravehicular mobility unit because they are not metabolized or scrubbed from the atmosphere. A prototype optical emission technique capable of detecting argon and nitrogen below 0.1% in oxygen has been developed. This instrument uses a glow discharge in reduced-pressure gas to produce atomic emission from the species present. Because the atomic emission lines from oxygen, nitrogen, and argon are discrete, and in many cases well-separated, trace amounts of argon and nitrogen can be detected in the ultraviolet and visible spectrum. This is a straightforward, direct measurement of the target contaminants, and may lend itself to a device capable of on-orbit verification of oxygen purity.

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Atomic Force Microscope Mediated Chromatography

Trace-chemical and microfluidic analyses are taken to higher precision. The atomic force microscope (AFM) is used to inject a sample, provide shear-driven liquid flow over a functionalized substrate, and detect separated components. This is demonstrated using lipophilic dyes and normal phase chromatography. A significant reduction in both size and separation time scales is achieved with a 25- micron-length column scale, and one-second separation times. The approach has general applications to trace chemical and microfluidic analysis.

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Dielectrophoresis-Based Particle Sensor Using Nanoelectrode Arrays

An array of nanostructure electrodes can provide a more sensitive reading than conventional microelectrodes. A method has been developed for concentrating, or partly separating, particles of a selected species from a liquid or gas containing these particles, and flowing in a channel. An example of this is to promote an accumulation (and thus concentration) of the selected particle (e.g., biological species such as E. coli, salmonella, anthrax, tobacco mosaic virus or herpes simplex, and non-biological materials such as nano- and microparticles, quantum dots, nanowires, nanotubes, and other inorganic particles) adjacent to the first surface.

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Global Shutter Imaging

Recent improvements in CMOS sensors enable advanced high-speed machine vision. In order to deliver crisp images in high-speed machine vision applications, image sensors require high-speed shuttering ability. The industry has traditionally relied on charge-coupled device (CCD) image sensors using interline transfer architectures to deliver this functionality. However, recent improvements in CMOS sensor design have enabled CMOS technology to achieve the image quality and true global shuttering performance necessary to meet high-speed machine vision demands. And with parallel outputs, windowing, and on-chip integration, well-designed CMOS imagers can offer compelling advantages in speed and system throughput.

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Multi-Dimensional Damage Detection for Surfaces and Structures

This system determines the size, depth, and location of damage in a multi-layered system. Current designs for inflatable or semirigidized structures for habitats and space applications use a multiple-layer construction, alternating thin layers with thicker, stronger layers, which produces a layered composite structure that is much better at resisting damage. Even though such composite structures or layered systems are robust, they can still be susceptible to penetration damage.

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