NIST Tech Beat - October 28, 2008

Marrying a sensitive detector technology capable of distinguishing hundreds of different chemical compounds with a pattern-recognition module that mimics the way animals recognize odors, researchers at the National Institute of Standards and Technology (NIST) have created a new approach for “electronic noses.” Described in a recent paper,* their electronic nose is more adept than conventional methodologies at recognizing molecular features even for chemicals it has not been trained to detect and is also robust enough to deal with changes in sensor response that come with wear and tear. The detector could be a potent tool for applications such as sniffing out nerve agents, environmental contaminants, and trace indicators of disease, in addition to monitoring industrial processes and aiding in space exploration.

In animals, odorant molecules in the air enter the nostrils and bind with sensory neurons in the nose that convert the chemical interactions into an electrical signal that the brain interprets as a smell. In humans, there are about 350 types of sensory neurons and many copies of each type; dogs and mice have several hundreds more types of sensory neurons than that. Odor recognition proceeds in a step-by-step fashion where the chemical identity is gradually resolved: initial coarse information (e.g. ice-cream is fruit-flavored vs. chocolate) is refined over time to allow finer discrimination (strawberry vs. raspberry). This biological approach inspired the researchers to develop a parallel “divide and conquer” method for use with the electronic nose.

The technology is based on interactions between chemical species and semiconducting sensing materials placed on top of MEMS microheater platforms developed at NIST. (See “NIST ‘Microhotplate’ May Help Search for Extraterrestrial Life,” NIST Tech Beat, Oct., 2001.) The electronic nose employed in the current work is comprised of eight types of sensors in the form of oxide films deposited on the surfaces of 16 microheaters, with two copies of each material. Precise control of the individual heating elements allows the scientists to treat each of them as a collection of “virtual” sensors at 350 temperature increments between 150 to 500 °C, increasing the number of sensors to about 5,600. The combination of the sensing films and the ability to vary the temperature gives the device the analytical equivalent of a snoot full of sensory neurons.

Much like people detect and remember many different smells and use that knowledge to generalize about smells they haven’t encountered before, the electronic nose also needs to be trained to recognize the chemical signatures of different smells before it can deal with unknowns. The great advantage of this system, according to NIST researchers Barani Raman and Steve Semancik, is that you don’t need to expose the array to every chemical it could come in contact with in order to recognize and/or classify them. Breaking the identification process down into simple, small, discrete steps using the most information rich data also avoids ‘noisy’ portions of the sensor response, thereby incorporating robustness against the effects of sensor drift or aging.

The researchers say that they are continuing to work on applications involving rapid identification of chemicals in unknown backgrounds or in a complex cocktail.

A novel technique* under development at the National Institute of Standards and Technology (NIST) uses a relatively inexpensive optical microscope to quickly and cheaply analyze nanoscale dimensions with nanoscale measurement sensitivity. Termed “Through-focus Scanning Optical Microscope” (TSOM) imaging, the technique has potential applications in nanomanufacturing, semiconductor process control and biotechnology.

Optical microscopes are not widely considered for checking nanoscale (below 100 nanometers) dimensions because of the limitation imposed by wavelength of light—you can’t get a precise image with a probe three times the object’s size. NIST researcher Ravikiran Attota gets around this, paradoxically, by considering lots of “bad” (out-of-focus) images. “This imaging uses a set of blurry, out-of-focus optical images for nanometer dimensional measurement sensitivity,” he says. Instead of repeatedly focusing on a sample to acquire one best image, the new technique captures a series of images with an optical microscope at different focal positions and stacks them one on top of the other to create the TSOM image. A computer program Attota developed analyzes the image.

While Attota believes this simple technique can be used in a variety of applications, he has worked with two. The TSOM image can compare two nanoscale objects such as silicon lines on an integrated circuit. The software “subtracts” one image from the other. This enables sensitivity to dimensional differences at the nanoscale—line height, width or side-wall angle. Each type of difference generates a distinct signal.

TSOM has also been theoretically evaluated in another quality control application. Medical researchers are studying the use of gold nanoparticles to deliver advanced pharmaceuticals to specific locations within the human body. Perfect size will be critical. To address this application, a TSOM image of a gold nanoparticle can be taken and compared to a library of simulated images to obtain “best-match” images with the intent of determining if each nanoparticle passes or fails.

This new imaging technology requires a research-quality optical microscope, a camera and a microscope stage that can move at preset distances. “The setup is easily under $50,000, which is much less expensive than electron or probe microscopes currently used for measuring materials at the nanoscale,” Attota explains. “This method is another approach to extend the range of optical microscopy from microscale to nanoscale dimensional analysis.” So far, sensitivity to a 3 nm difference in line widths has been demonstrated in the laboratory.

* R. Attota, T.A. Germer and R.M. Silver. Through-focus scanning-optical-microscope imaging method for nanoscale dimensional analysis, Optics Letters 33, 1990 (2008).

As the weather grows cold and people start planning for the holidays, researchers at the National Institute of Standards and Technology (NIST) have released two new research videos that illustrate the benefit of having sprinkler systems in homes. Scientists exposed two dry Christmas trees to an open flame in a living room mock-up built inside their laboratory and recorded the results.

The video of the room with the sprinkler shows that the sprinkler eventually dampens and extinguishes the tree fire. Without a sprinkler system, the other video shows that the tree burns rapidly. Research videos also confirm that well-maintained, moist trees are much less likely to burn than trees that have not received adequate water in the home.

Christmas trees are involved in causing hundreds of home fires each year. These fires cause injury, death and millions of dollars annually in property damage.

“Fire research, such as our videos and measurement science, are showing the importance of residential sprinkler systems,” explains Dick Bukowski, coordinator of codes and standards for NIST’s Building and Fire Research Laboratory. Sprinkler systems have been required for years in high-rise buildings, he says, and with the 2009 editions of both of the model building codes, they will be required in all new residential buildings. Fire and building researchers hope that as the number of homes with sprinkler systems increases, the number of fatalities from Christmas tree fires will decrease, says Dan Madrzykowski, a NIST fire protection engineer.

Buildings in the United States account for more than 40 percent of the nation’s total energy consumption, and that is just one of their impacts on the environment. In a major statement on “green” building technology, a new report from the National Science and Technology Council (NSTC) sets out a broad agenda for research and development on technologies to decrease use of natural resources and improve indoor environments while reducing greenhouse gas emissions and other harmful pollutants from the building sector.

The report Federal R&D Agenda for Net-Zero Energy, High-Performance Green Buildings was produced by the NSTC’s Buildings Technology Research and Development Subcommittee under the auspices of the Office of Science and Technology Policy (OSTP) in the Executive Office of the President. It draws on the recommendations of 16 executive branch agencies along with the Architect of the Capitol and the Smithsonian Institution. The National Institute of Standards and Technology (NIST) played a key role in developing the report’s goals for measurement science methods, energy efficiency technologies, indoor environment quality and knowledge transfer.

The major goals outlined in the NSTC report include developing technologies, tools and practices that could significantly reduce the use of energy, water and other natural resources, promoting environmentally friendly products and practices, and reducing building material waste while meeting building performance design standards. The agenda calls for supporting these goals through the full spectrum of R&D activities, including use-inspired basic research, applied research, measurement science, development, demonstration and implementation. The report also addresses barriers to widespread acceptance and surveys policy options to change current buildings sector practices.

The report responds to provisions in the Energy Policy Act of 2005 and the Energy Independence and Security Act of 2007 to enhance federal R&D that could enable more efficient and higher performance residential and commercial buildings.

Each year the Baldrige Program recruits experts from business, education organizations, health care providers, nonprofits and other groups to serve on the Board of Examiners for the Malcolm Baldrige National Quality Award. Examiners evaluate applications for the Award and prepare feedback reports to applicants that cite strengths and opportunities for improvement.

The application form for the 2009 Board of Examiners will be available starting Nov. 5, 2008, at http://baldrige.nist.gov/Examiner_Application.htm. Applications must be submitted electronically; the deadline is 2 p.m. Eastern time on Jan. 6, 2009.

The board consists of more than 500 volunteers, including 12 judges and about 60 senior examiners representing many industries and sectors. Service on the board provides opportunities to enhance one’s knowledge about improving processes and achieving world-class results, develop a network of like-minded colleagues, earn professional development Continuing Education Units (CEUs), and help improve U.S. competitiveness.

Highly qualified applicants may not be selected in a given year in order to balance the board with examiners from different sectors or with different work experiences. Therefore, past applicants who have not been selected are encouraged to apply again.

For assistance in preparing an examiner application, contact examappl@nist.gov or call the Examiner Hotline toll-free at (877) 237-9064.

Named after Malcolm Baldrige, the 26th Secretary of Commerce, the Baldrige Award was established by Congress in 1987 and is managed by the National Institute of Standards and Technology (NIST) in cooperation with the private sector. The Baldrige Program promotes excellence in organizational performance, recognizes the achievements and results of U.S. organizations, and publicizes successful performance management strategies. The Baldrige Award is not given for specific products or services. Since 1988, 72 organizations have received Baldrige Awards.

William R. Ott, deputy director of the NIST Physics Laboratory, has been named as a recipient of the 2008 Presidential Rank Award. The awards recognize exceptional long-term accomplishments in public service by career senior government executives. Ott is a recipient of an award in the category for 2008 Meritorious Senior Professionals & Executives.

The award acknowledges Ott for his leadership at NIST in establishing interdisciplinary technical programs and providing a stimulating intellectual climate for scientific research. It recognizes Ott for helping to instill a culture of excellence and creativity epitomized by the unprecedented award of three Nobel Prizes to Physics Laboratory scientists for work supporting the NIST mission.

Ott has worked at NIST and its predecessor, the National Bureau of Standards, since 1968. About 25 years ago Ott was the first to establish a research group with world-class measurement capability in nanoscale science that, in 2006, became the core of NIST’s new Center for Nanoscale Science and Technology. Most recently he established a new program in biophysics, medical physics, and molecular imaging that responds to the measurement needs of the health care community

Carlos Gutierrez, Secretary of the Department of Commerce (DOC), will recognize Ott and other DOC awardees at a photo ceremony on Nov. 6, 2008. Award winners are nominated by agency heads, evaluated by boards of private citizens, and approved by the President. For the list of all other winners, please see “Presidential Rank Awards” at the U.S. Office of Personnel Management Web site.

Three staff members of the National Institute of Standards and Technology (NIST) were honored last week by the American National Standards Institute (ANSI) for their work in the field of standards development and standards conformity assessment. The awards were presented at the 2008 ANSI Awards Banquet on Oct. 22.

Belinda L. Collins, Director of NIST Technology Services (TS), was awarded the Howard Coonley Medal. This medal recognizes an executive that has benefited the national economy through voluntary standardization and conformity assessment and has given outstanding support to standardization as a management tool.

Ajit Jillavenkatesa, who manages TS programs that work to remove standards-related barriers to trade, was one of two winners of the ANSI Next Generation Award, which recognizes “individuals who have been engaged in standardization or conformity assessment activities for less than eight years and who have, during this time, demonstrated vision, leadership [and] dedication” and made significant contributions to the field.

Gordon Gillerman, an expert in conformity assessment for organizations implementing testing programs for homeland security, was one of six individuals to receive Meritorious Service Awards in recognition of their outstanding contributions to the U.S. voluntary standardization system.

One of the most visible faces of NIST, Technology Services provides access to NIST calibration services, standard reference materials, standard reference data and laboratory accreditation programs, and works with state weights and measures offices and national and international standards bodies and research institutions to promote understanding of standards and conformity assessment activities.

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Editor: Michael Baum

Date created: October 28, 2008
Date updated: October 28, 2008
Contact: inquiries@nist.gov