Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Membrane”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Novel Elastomeric Membranes Developed for Polymer Electrolytes in Lithium Batteries

Lithium-based polymer batteries for aerospace applications need to be highly conductive from -70 to 70 C. State-of-the-art polymer electrolytes are based on polyethylene oxide (PEO) because of the ability of its ether linkages to solvate lithium ions. Unfortunately, PEO has a tendency to form crystalline regions below 60 C, dramatically lowering conductivity below this temperature. PEO has acceptable ionic conductivities (10(exp -4) to 10(exp -3) S/cm) above 60 C, but it is not mechanically strong. The room-temperature conductivity of PEO can be increased by adding solvent or plasticizers, but this comes at the expense of thermal and mechanical stability. One of NASA Glenn Research Center s objectives in the Polymer Rechargeable System program (PERS) is to develop novel polymer electrolytes that are highly conductive at and below room temperature without added solvents or plasticizers.

Tigelaar, Dean M.↗
NASA NTRS2004

Proton Exchange Membrane (PEM) Fuel Cells for Space Applications

This presentation will provide a summary of the PEM fuel cell development at the National Aeronautics and Space Administration, Johnson Space Center (NASA, JSC) in support of future space applications. Fuel cells have been used for space power generation due to their high energy storage density for multi-day missions. The Shuttle currently utilizes the alkaline fuel cell technology, which has highly safe and reliable performance. However, the alkaline technology has a limited life due to the corrosion inherent to the alkaline technology. PEM fuel cells are under development by industry for transportation, residential and commercial stationary power applications. NASA is trying to incorporate some of this stack technology development in the PEM fuel cells for space. NASA has some unique design and performance parameters which make developing a PEM fuel cell system more challenging. Space fuel cell applications utilize oxygen, rather than air, which yields better performance but increases the hazard level. To reduce the quantity of reactants that need to be flown in space, NASA also utilizes water separation and reactant recirculation. Due to the hazards of utilizing active components for recirculation and water separation, NASA is trying to develop passive recirculation and water separation methods. However, the ability to develop recirculation components and water separators that are gravity-independent and successfully operate over the full range of power levels is one of the greatest challenges to developing a safe and reliable PEM fuel cell system. PEM stack, accessory component, and system tests that have been performed for space power applications will be discussed.

Bradley, Karla↗
NASA NTRS2005

Characterization of Unimorph-Membrane Microactuators and Error-Analysis of the Characterization Process

Microactuators are versatile, low-cost, low-mass electrical-mechanical devices that can be used in many applications. Microactuators consist of two electrodes sandwiching a PZT (piezo-electric) film between them. The centers of the microactuators deflect when a voltage is applied across the electrodes. In order to correctly apply this technology for use, it is important to fully characterize the actuation behavior. Measuring the deflection profile as a function of the voltage of various microactuators is crucial. This measurement process has errors associated with it, so it is being studied to determine the accuracy of the data. In certain applications, microactuators may undergo many cycles of deflection; testing various microactuators through many cycles of deflection simulates these circumstances. However, due to an unknown issue, many of the microactuators exhibit defects that cause them to fail when voltage is applied to their electrodes. These defects do not allow for the acquisition of significant deflection profiles. Vibrations are the largest cause of error in deflection measurements, and the microactuators withstand continuous cycles of deflection, yet the cause of damage is still to be determined. Future projects will be needed to characterize the deflection profiles of various microactuators and to overcome the defects in the microactuators that are currently present.

Wright, Matthew W.↗
NASA NTRS2006

Bucky Paper as a Support Membrane in Retinal Cell Transplantation

A method for repairing a retinal system of an eye, using bucky paper on which a plurality of retina pigment epithelial cells and/or iris pigment epithelial cells and/or stem cells is deposited, either randomly or in a selected cell pattern. The cell-covered bucky paper is positioned in a sub-retinal space to transfer cells to this space and thereby restore the retina to its normal functioning, where retinal damage or degeneration, such as macular degeneration, has occurred.

Loftus, David J.↗
NASA NTRS2005

Investigation of Ruthenium Dissolution in Advanced Membrane Electrode Assemblies for Direct Methanol Based Fuel Cell Stacks

Dissolution of ruthenium was observed in the 80-cell stack. Duration testing was performed in single cell MEAs to determine the pathway of cell degradation. EDAX analysis on each of the single cell MEAs has shown that the Johnson Matthey commercial catalyst is stable in DMFC operation for 250 hours, no ruthenium dissolution was observed. Changes in the hydrophobicity of the cathode backing papers was minimum. Electrode polarization analysis revealed that the MEA performance loss is attributed to changes in the cathode catalyst layer. Ruthenium migration does not seem to occur during cell operation but can occur when methanol is absent from the anode compartment, the cathode compartment has access to air, and the cells in the stack are electrically connected to a load (Shunt Currents). The open-to-air cathode stack design allowed for: a) The MEAs to have continual access to oxygen; and b) The stack to sustain shunt currents. Ruthenium dissolution in a DMFC stack can be prevented by: a) Developing an internally manifolded stacks that seal reactant compartments when not in operation; b) Bringing the cell voltages to zero quickly when not in operation; and c) Limiting the total number of cells to 25 in an effort to limit shunt currents.

alternative power sources↗
NASA NTRS2005

Investigation of Ruthenium Dissolution in Advanced Membrane Electrode Assemblies for Direct Methanol Based Fuel Cells Stacks

This viewgraph presentation gives a detailed review of the Direct Methanol Based Fuel Cell (DMFC) stack and investigates the Ruthenium that was found at the exit of the stack. The topics include: 1) Motivation; 2) Pathways for Cell Degradation; 3) Cell Duration Testing; 4) Duration Testing, MEA Analysis; and 5) Stack Degradation Analysis.

Direct Methanol Fuel Cells, (DMFC)↗
NASA NTRS2005

Low-cycle Fatigue and Dynamic Fracture in Gold Thin Films on SiN Supported Membranes

This slide presentation focuses on the dynamic mechanical response and fatigue behavior in sub-micron thick Au-films deposited onto amorphous Si(sub X)N(sub y) substrates, with spider-web geometry, that were subjected to forced vibration (3-axis random vibration with 2 kHz roll-off frequency). The work is to advance cyrogenic detectors that can operate at 100mK, that is required to create cryogenic detectors that are to search for present day signatures of the big bang.

fatigue↗
NASA NTRS2010

OMEGA (Offshore Membrane for Enclosing Algae). NASA-NAVY: A Strategic Planning Discussion

This briefing packet provides a short introduction to OMEGA and a truncated version of our project approach, with an example of the kind of work break down structure (WBS) used to guide our Phase I activities. It is meant to give you an impression of how we are approaching the challenge of creating the world's first marine photobioreactor (PBR) that will scale to address the strategic energy problems confronting the United States and the world. Some of our conceptual PBR designs and plans for logistics are included to communicate the path we have taken. We have also included an aerial photograph of the experimental tanks we are using at the Cal Fish and Game, followed by concluding remarks. The overarching purpose of the strategic planning discussion in Norfolk is to establish the relationship between the NASA OMEGA Team and the Navy, to unite the strengths of both agencies, and to map a mutual way forward along the project's established critical path.

Trent, Jonathan↗
NASA NTRS2011

Force and deflection sensor with shell membrane and optical gratings and method of manufacture

A sensor for force is formed from an elastomeric cylinder having a region with apertures. The apertures have passageways formed between them, and an optical fiber is introduced into these passageways, where the optical fiber has a grating for measurement of tension positioned in the passageways between apertures. Optionally, a temperature measurement sensor is placed in or around the elastomer for temperature correction, and if required, a copper film may be deposited in the elastomer for reduced sensitivity to spot temperature variations in the elastomer near the sensors.

Park, Yong-Lae↗
NASA NTRS2012

Method of fabricating lipid bilayer membranes on solid supports

The present invention provides a method of producing a planar lipid bilayer on a solid support. With this method, a solution of lipid vesicles is first deposited on the solid support. Next, the lipid vesicles are destabilized by adding an amphipathic peptide solution to the lipid vesicle solution. This destabilization leads to production of a planar lipid bilayer on the solid support. The present invention also provides a supported planar lipid bilayer, where the planar lipid bilayer is made of naturally occurring lipids and the solid support is made of unmodified gold or titanium oxide. Preferably, the supported planar lipid bilayer is continuous. The planar lipid bilayer may be made of any naturally occurring lipid or mixture of lipids, including, but not limited to phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinsitol, cardiolipin, cholesterol, and sphingomyelin.

Cho, Nam-Joon↗