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Tech Beat - July 28, 2009

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Editor: Michael Baum
Date created: December 30, 2010
Date Modified: December 30, 2010 
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‘Microfluidic Palette’ May Paint Clearer Picture of Biological Processes

NIST microfluidic palette
NIST microfluidic palette

(Top) The NIST microfluidic palette. The mixing area is the pin-sized chamber bordered by three holes in the center of the top layer. (Bottom) For each of the three dyes injected into the NIST microfluidic palette, an independent gradient forms that remains constant as long as flow into the system does not change. Overlapping the three gradients results in a blend of dye concentrations, but the combination of colors in any single location is distinctly different from all others location.

Credit: G. Cooksey, NIST (top) and J. Atencia, NIST (bottom) View hi-resolution top image and bottom image.

The masterpieces that spring from the talents of Rembrandt, Van Gogh and other artists often begin with the creation of a gradient of colors on a palette. In a similar manner, researchers at the National Institute of Standards and Technology (NIST) have created an innovative device called the “microfluidic palette” to produce multiple, steady-state chemical gradients—gradual changes in concentration across an area—in a miniature chamber about the diameter of a pinhead. The tool can be used to study the complex biological mechanisms in cells responsible for cancer metastasis, wound healing, biofilm formation and other fluid-related processes.

The advantage of the NIST system, as described in a new paper,* is that the gradients are generated by diffusion—the gentle movement of matter from one point to another by random molecular motion. Microfluidic systems usually mix fluids more actively, by pumps and the circulation of currents. Diffusion gradients allow cells being studied to remain in the microchamber without the chance of their being swept away. Diffusion also permits chemical molecules to move in and out of the cells naturally and eliminates the risk of shear stresses, commonly produced by currents, which could cause the cells to rupture or behave abnormally.

The NIST microfluidic palette manages this with a clever plumbing trick. The key element of the palette is the microchamber, a small disk-shaped area only 1.5 millimeters (0.06 inch) across etched into the center of a glass wafer. Tiny holes at its circumference—three in the prototype, but it could be more—allow various mixtures to flow into the chamber. Beneath the chamber, each access port connects to the long tail of a Y-shaped channel etched into a second layer. These channels deliver test chemicals to the chamber. Fluid flow in and out of the short arms of each Y at constant pressure assures a constant stream of fresh chemicals. Because the pressure in the chamber is balanced by filling it previously with a buffer solution, the test chemicals that migrate from the channels into the chamber do so almost entirely by diffusion. Therefore, as long as a constant flow of fluid is maintained through the Y’s, the gradients in the chamber can be maintained virtually indefinitely.

To demonstrate how the microfluidic palette works, the NIST researchers inject dyes of the three primary colors—red, yellow and blue—separately into the three inlets of the system. For each dye, an independent gradient forms that remains constant as long as flow rate into the system does not change. Overlapping the three gradients results in a blend of dye concentrations in which the combination of colors at one location is distinctly different from any other location.

Similarly, if three separate drugs were injected into the palette where the microchamber contained a culture of cells, individual cells at different locations in the chamber would be exposed to different combinations of the drugs. In a single experiment, one could easily study the effects of a wide range of mixed drug concentrations on the same cell type.

Another potential application of the microfluidic palette is the study of chemotaxis, the movement of cells along a chemical gradient, a biological phenomenon that plays a role in the spread of cancer (metastasis), wound healing, infection and carbon cycling in the ocean.

The microfluidic palette technology is available for licensing. For more information, see the Federal Register, Vol. 74, No. 73, page 17819 (April 17, 2009).

* J. Atencia, J. Morrow and L.E. Locascio. The microfluidic palette: A diffusive gradient generator with spatio-temporal control. Lab on a Chip. Posted online June 22, 2009.

Media Contact: Michael E. Newman, michael.newman@nist.gov, 301-975-3025

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NIST Scientists Study How to Stack the Deck for Organic Solar Power

A new class of economically viable solar power cells - cheap, flexible and easy to make - has come a step closer to reality as a result of recent work* at the National Institute of Standards and Technology (NIST), where scientists have deepened their understanding of the complex organic films at the heart of the devices.

illustration of a photovoltaic cell

In this cross-section of an organic photovoltaic cell, light passes through the upper layers (from top down, glass, indium tin dioxide, and thermoplastic) and generates a photocurrent in the polymer-fullerene layer. Channels formed by polymers (tan) and fullerenes (dark blue) allow electric current to flow into the electrode at bottom. NIST research has revealed new information about how the channels form, potentially improving cell performance.

Credit: NIST
View hi-resolution image

Organic photovoltaics, which rely on organic molecules to capture sunlight and convert it into electricity, are a hot research area because in principle they have significant advantages over traditional rigid silicon cells. Organic photovoltaics start out as a kind of ink that can be applied to flexible surfaces to create solar cell modules that can be spread over large areas as easily as unrolling a carpet. They’d be much cheaper to make and easier to adapt to a wide variety of power applications, but their market share will be limited until the technology improves. Even the best organic photovoltaics convert less than 6 percent of light into electricity and last only a few thousand hours. “The industry believes that if these cells can exceed 10 percent efficiency and 10,000 hours of life, technology adoption will really accelerate,” says NIST’s David Germack. “But to improve them, there is critical need to identify what’s happening in the material, and at this point, we’re only at the beginning.”

The NIST team has advanced that understanding with their latest effort, which provides a powerful new measurement strategy for organic photovoltaics that reveals ways to control how they form. In the most common class of organic photovoltaics, the “ink” is a blend of a polymer that absorbs sunlight, enabling it to give up its electrons, and ball-shaped carbon molecules called fullerenes that collect electrons. When the ink is applied to a surface, the blend hardens into a film that contains a haphazard network of polymers intermixed with fullerene channels. In conventional devices, the polymer network should ideally all reach the bottom of the film while the fullerene channels should ideally all reach the top, so that electricity can flow in the correct direction out of the device. However, if barriers of fullerenes form between the polymers and the bottom edge of the film, the cell’s efficiency will be reduced.

By applying X-ray absorption measurements to the film interfaces, the team discovered that by changing the nature of the electrode surface, it will repulse fullerenes (like oil repulses water) while attracting the polymer. The electrical properties of the interface also change dramatically. The resultant structure gives the light-generated photocurrent more opportunities to reach the proper electrodes and reduces the accumulation of fullerenes at the film bottom, both of which could improve the photovoltaic’s efficiency or lifetime.

“We’ve identified some key parameters needed to optimize what happens at both edges of the film, which means the industry will have a strategy to optimize the cell’s overall performance,” Germack says. “Right now, we’re building on what we’ve learned about the edges to identify what happens throughout the film. This knowledge is really important to help industry figure out how organic cells perform and age so that their life spans will be extended.”

* D.S. Germack, C.K. Chan, B.H. Hamadani, L.J. Richter, D.A. Fischer, D.J. Gundlach and D.M. DeLongchamp. Substrate-dependent interface composition and charge transport in films for organic photovoltaics. Applied Physics Letters, 94, 233303 (2009), DOI: 10.1063/1.3149706.

Media Contact: Chad Boutin, boutin@nist.gov, 301-975-4261

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Shake, Rattle, No Roll: Construction Guide for Earthquake-Resistant Buildings

A guide* for designing buildings using steel moment frames to resist earthquakes has been published by the National Institute of Standards and Technology (NIST) as part of its support for the National Earthquake Hazards Reduction Program (NEHRP).

Beams, columns and beam-column connections are specially designed in “structural steel special moment frames” to withstand building sway during the ground shaking that accompanies earthquakes. The new publication, Seismic Design of Steel Special Moment Frames: A Guide for Practicing Engineers, consolidates requirements of the International Building Code, which is the code generally adopted throughout the United States, and related standards including ASCE 7, AISC 341 and AISC 358.

The guide covers code requirements and accepted approaches to their implementation, including background and sketches to illustrate the requirements. It also includes chapters on the use of special moment frames, their principles, guidance on analysis and design, additional requirements and detailing and constructability issues. The authors, professional engineers Ronald O. Hamburger, Helmut Krawinkler, James O. Malley and Scott M. Adan, also present best practice recommendations for design and construction that may not be specifically required by the codes or standards.

Seismic Design of Steel Special Moment Frames: A Guide for Practicing Engineers is written for structural engineers, building officials, educators and students. It is the second in a series of technical briefs that NIST is publishing to address topics of interest to earthquake professionals, primarily those in the design and construction industries. Future technical briefs are expected to cover performing nonlinear structural analyses and seismic analysis and design of reinforced concrete diaphragms.

The guide is available at www.nehrp.gov/pdf/nistgcr9-917-3.pdf .

* R.O. Hamburger, H. Krawinkler, J.O. Malley and S.M. Adan. Seismic design of steel special moment frames: A guide for practicing engineers (NIST GCR 09-917-3). June 2009.

Media Contact: Evelyn Brown, evelyn.brown@nist.gov, 301-975-5661

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September PerMIS Workshop Takes Measure of Intelligent System Performance

Intelligent machines of the future will turn custom designs into finished products quickly and efficiently, save lives in catastrophes, and minimize complications caused by surgeries. Researchers involved in advancing artificial intelligence in robots and other systems will gather Sept. 21-23 at the National Institute of Standards and Technology (NIST) in Gaithersburg, Md. to attend the ninth annual Performance Metrics for Intelligent Systems (PerMIS’09) workshop.

Robots with intelligence have to be able to sense, perceive, reason, learn and adapt. Other intelligent systems may have other abilities, for instance, analyzing videotapes to detect suspicious behaviors in individuals within a crowd. The annual PerMIS workshop is the only one of its kind dedicated to defining measures and methodologies to evaluate performance of intelligent systems. PerMIS’09 addresses the question “Does performance measurement accelerate the pace of advancement for intelligent systems?” The workshop focuses on application of performance measures to practical problems in sectors such as industrial, medical, emergency response, transportation, homeland security and defense.

PerMIS is an excellent forum for sharing lessons learned and discussions as well as fostering collaborations between researchers and practitioners from industry, academia and government agencies, according to PerMIS General Chair Elena Messina.

Notable plenary speakers include Tom Mitchell of Carnegie Mellon University whose research in machine learning methods and brain imaging was recently featured on CBS’s 60 Minutes, David Bruemmer of Idaho National Laboratory discussing robots and threat detection, Ben Kuipers of University of Michigan, Ann Arbor, describing a cognitive mapper for mobile robots, Paul Cohen of the University of Arizona arguing against sophistication in performance assessments, and Raffaello D’Andrea of ETH Zurich talking about his plan to use hundreds of networked, autonomous mobile robots for order fulfillment in warehousing.

More information about the workshop can be found at www.isd.mel.nist.gov/PerMIS_2009/. For registration information, see www.nist.gov/public_affairs/confpage/090921.htm. For special inquiries, please contact Elena Messina at elena.messina@nist.gov or Raj Madhavan at raj.madhavan@nist.gov. Journalists interested in covering the meeting should contact Evelyn Brown, evelyn.brown@nist.gov.

Media Contact: Evelyn Brown, evelyn.brown@nist.gov, 301-975-5661

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NIST Awards $55.5 Million for New University Research Facilities

On July 20, the National Institute of Standards and Technology (NIST) announced the award of new grants totaling more than $55.5 million to four universities to provide cost-shared support for the construction of new scientific research facilities.

The cost-shared awards include:

  • $15 million to the University of Miami (Miami, Fla.) for a Marine Technology and Life Sciences Seawater Research Building, matched by $28.8 million;
  • $14.4 million to Auburn University (Auburn, Ala.) for a Center for Advanced Science, Innovation and Commerce, matched by an equal amount;
  • $11.1 million to the Rice University (Houston, Texas) for the new Brockman Hall for Physics, matched by $33.4 million; and
  • $15 million to the University of North Carolina Wilmington (Wilmington, N.C.) for a new facility for the Marine Biotechnology in North Carolina (MARBIONC) program, matched by an equal amount.


The new research buildings will provide state-of-the-art laboratory facilities supporting academic research across a broad range of topics affecting the missions of the research agencies of the Department of Commerce, including fundamental physics research, nanotechnology, aquaculture and marine ecology.

Funding for the new grants was provided under the American Recovery and Reinvestment Act of 2009. For additional information on the grants and details of the four projects, see the news release, “NIST Awards $55.5 Million in Grants for New University Research Facilities.”

Media Contact: Michael Baum, michael.baum@nist.gov, 301-975-2763

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Quicklinks

Recent NIST Smart Grid Testimony

NIST’s work on standards and cyber security for a nationwide “smart” electric power grid was featured in recent congressional testimony. On July 21, Cita Furlani, director NIST’s Information Technology Laboratory, described how NIST is collaborating with other agencies and private sector organization to address the cyber security requirements of the Smart Grid, a key component of President Obama’s comprehensive energy plan, which aims to reduce U.S. dependence on foreign oil and create jobs. Furlani testified before a subcommittee of the House Committee on Homeland Security. To read the testimony, go to: www.nist.gov/testimony/2009/cyber%20sec-smart%20grid%20house%20hs%20hearing%20furlani%20final.pdf

Appearing before a subcommittee of the House Committee on Science and Technology, George Arnold, national coordinator for smart grid interoperability, reviewed NIST’s progress in carrying out standards-related responsibilities assigned by the Energy Independence and Security Act of 2007. “Modernizing and digitizing the nation’s electrical power grid—the largest interconnected machine on Earth—is an enormous challenge and a tremendous opportunity,” Arnold said in his July 23 testimony. “Success requires a combination of quick action and sustained progress in implementing and integrating the components, systems, and networks that will make up the Smart Grid.”

To read the testimony, go to: www.nist.gov/testimony/2009/arnold%20smart%20grid%20testimony%20house%20s&t%20subc%20on%20e&e.pdf

Media Contact: Mark Bello, mark.bello@nist.gov, 301-975-3776

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Brochure Available on New NIST Boulder Laboratory

A new, high-performance research and measurement laboratory is under construction at the National Institute of Standards and Technology (NIST) campus in Boulder, Colo.

The $102.2 million Precision Measurement Laboratory (PML) will help NIST better meet the needs of U.S. industry and science in key national priority areas such as nanotechnology, new energy sources, enhanced telecommunications, and radically new information technology such as quantum computers.

Designed as an extension to the existing Building 1, the new laboratory will be one of the most advanced in the world. The PML will boost research productivity by offering stringent vibration isolation, temperature and humidity control, air cleanliness, and electrical power quality. The new lab will also enable new measurements and research needed to support future innovations. Construction began in late 2008 and is expected to last about 2 1/2 years.

For printed copies of the brochure, contact inquiries@nist.gov or 301-975-NIST. Read it on-line at http://www.nist.gov/public_affairs/factsheet/newboulderpml.cfm.

Media Contact: Laura Ost, laura.ost@nist.gov, 303-497-4880

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New NIST Video Highlights Postdoctoral Fellowships in Materials Science

Every year, the Materials Science and Engineering Laboratory (MSEL) at the National Institute of Standards and Technology appoints 10 to 15 new postdoctoral research fellowships under a program sponsored by NIST and managed by the National Research Council. According to MSEL Acting Director, Eric Amis, NIST programs are significantly enriched by the fresh ideas and talent brought by NRC postdocs, who enjoy close interactions with a broad range of experienced researchers and access to world-class equipment and resources.

A new NIST video, “Door to the Future” highlights this program. MSEL has nearly 200 postdoctoral research opportunities that span the materials spectrum, from metals and semiconductors to polymers and biomaterials. These include exciting opportunities in materials measurements for applications in electronics, energy, healthcare, nanotechnology, physical infrastructure and manufacturing.

Application deadlines are Feb. 1 and Aug. 1 of each year. for more information see “NRC Postdoctoral Research Fellowships @ MSEL” at www.nist.gov/msel/postdoc.cfm.

NIST generally hires approximately 60 NRC postdoctoral fellows annually. In addition to materials science, research opportunities are available in chemistry, physics, mathematics, computer sciences and engineering. For more information, see “NIST Postdoctoral Research Associateships Program.” at www.nist.gov/oiaa/postdoc.htm.

Media Contact: Michael Baum, michael.baum@nist.gov, 301-975-2763

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Product Incorporating NIST Expert System Wins R&D 100 Award

Commercial process-design software that incorporates NIST’s thermophysical and thermochemical property data sets will receive a 2009 R&D 100 award, R&D Magazine has announced. The annual award recognizes the 100 most technologically significant products introduced during the past year.

The award recognizes Aspen Plus® 2006.5 with NIST ThermoData Engine (TDE), a process simulator that provides new tools to significantly increase the number and variety of chemical components that may be considered by the process design engineer, while dramatically reducing the time required for compilation and critical evaluation of component properties. The product is marketed by Aspen Technology Inc. of Burlington, Mass., and is used in a range of industries: oil & gas, petroleum refining, chemicals, power, pharmaceuticals, metal & mining, for the design and optimization of processes.

The NIST ThermoData Engine combines a sophisticated expert system with a large electronic database to provide critically evaluated property data for a wide range of organic compounds on demand, helping engineers to rapidly develop accurate, high-fidelity chemical process models. (See “New Web-based System Leads to Better, More Timely Data”, NIST Tech Beat, Oct. 26, 2006.)

Six NIST personnel worked on the cooperative project with Aspen Tech, including Thermodynamics Research Center group leader Michael Frenkel, chemist Robert Chirico, physicist Chris Muzny, chemical engineer Eric Lemmon, physicist Andrei Kazakov, and NIST associate Vladimir Diky. NIST participates in such projects to help assure that U.S. industry has access to accurate and reliable data and predictive models to determine the chemical and physical properties of materials and processes.

The awards will be presented on Nov. 12, 2009, in Orlando, Fla.

For more, see www.rdmag.com/RD100Home.html.

Media Contact: Laura Ost, laura.ost@nist.gov, 303-497-4880

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NIST Physicist Cited as 'Federal Player of the Week'

NIST physicist Ian Spielman has been profiled at washingtonpost.com as “This Week’s Federal Player”, a regular feature created by the Washington Post Web site and the Partnership for Public Service. Spielman was recognized for his innovations in the study of high-temperature superconductivity. Read “Ian Spielman: Cracking the Code of Superconductivity” at www.washingtonpost.com/wp-dyn/content/article/2009/07/27/AR2009072700664.html.

Media Contact: Michael Baum, michael.baum@nist.gov, 301-975-2763

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