In This Issue...
Nanopower: Avoiding Electrolyte Failure in Nanoscale Lithium Batteries
It turns out you can be too thin—especially if you’re a nanoscale battery. Researchers from the National Institute of Standards and Technology (NIST), the University of Maryland, College Park, and Sandia National Laboratories built a series of nanowire batteries to demonstrate that the thickness of the electrolyte layer can dramatically affect the performance of the battery, effectively setting a lower limit to the size of the tiny power sources.* The results are important because battery size and performance are key to the development of autonomous MEMS—microelectromechanical machines—which have potentially revolutionary applications in a wide range of fields.
MEMS devices, which can be as small as tens of micrometers (that is, roughly a tenth the width of a human hair), have been proposed for many applications in medicine and industrial monitoring, but they generally need a small, long-lived, fast-charging battery for a power source. Present battery technology makes it impossible to build these machines much smaller than a millimeter—most of which is the battery itself—which makes the devices terribly inefficient.
NIST researcher Alec Talin and his colleagues created a veritable forest of tiny—about 7 micrometers tall and 800 nanometers wide—solid-state lithium ion batteries to see just how small they could be made with existing materials and to test their performance.
Starting with silicon nanowires, the researchers deposited layers of metal (for a contact), cathode material, electrolyte, and anode materials with various thicknesses to form the miniature batteries. They used a transmission electron microscope (TEM) to observe the flow of current throughout the batteries and watch the materials inside them change as they charged and discharged.
The team found that when the thickness of the electrolyte film falls below a threshold of about 200 nanometers,** the electrons can jump the electrolyte border instead of flowing through the wire to the device and on to the cathode. Electrons taking the short way through the electrolyte—a short circuit—cause the electrolyte to break down and the battery to quickly discharge.
“What isn’t clear is exactly why the electrolyte breaks down,” says Talin. “But what is clear is that we need to develop a new electrolyte if we are going to construct smaller batteries. The predominant material, LiPON, just won’t work at the thicknesses necessary to make practical high-energy-density rechargeable batteries for autonomous MEMS.”
*D. Ruzmetov, V.P. Oleshko, P.M. Haney, H.J. Lezec, K. Karki, K.H. Baloch, A.K. Agrawal, A.V. Davydov, S. Krylyuk, Y. Liu, J. Huang, M. Tanase, J. Cumings and A.A. Talin. Electrolyte stability determines scaling limits for solid-state 3D Li-ion batteries, Nano Letters 12, 505-511 (2011).
** Represents the group's latest data collected after publication of the paper cited above.
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NIST Findings Awaken Age-Old Anesthesia Question
Why does inhaling anesthetics cause unconsciousness? New insights into this century-and-a-half-old question may spring from research performed at the National Institute of Standards and Technology (NIST).* Scientists from NIST and the National Institutes of Health have found hints that anesthesia may affect the organization of fat molecules, or lipids, in a cell’s outer membrane—potentially altering the ability to send signals along nerve cell membranes.
“A better fundamental understanding of inhaled anesthetics could allow us to design better ones with fewer side effects,” says Hirsh Nanda, a scientist at the NIST Center for Neutron Research (NCNR). “How these chemicals work in the body is a scientific mystery that stretches back to the Civil War.”
At the turn of the 20th century, doctors suspected inhaled anesthetics had some effect on cell membranes, an animal cell’s outer boundary. Despite considerable investigation, however, no one was able to demonstrate that anesthetics produced changes in the physical properties of membranes large enough to cause anesthesia. But eventually, understanding of membrane function grew more refined as scientists learned more about ion channels.
Ion channels—large proteins embedded in the relatively small lipid molecules forming the membrane—are responsible for conducting electrical impulses along nerve cells in the brain and throughout our body. By a few decades ago, the prevailing theory held that inhaled anesthetics directly interacted with these protein channels, affecting their behavior in some fashion. But no one could find a single type of ion channel that reacted to anesthetics in a way pivotal enough to settle the matter, and the question remained open.
“That’s where we picked up the thread,” says Nanda. “We had been looking at how different types of lipid molecules affect ion channels.”
While a cell membrane is a highly fluid film made of many different kinds of lipid molecules, the region immediately surrounding an ion channel often consists of a single type of lipids that form a sort of “raft” that is more ordered and less fluid then the rest of the membrane. When the team heard other researchers had found that disrupting these lipid rafts could affect a channel’s function, they put to work their own previous experience working with the channels.
“We decided to test whether inhaled anesthetics could have an effect on rafts in model cell membranes,” Nanda says. “No one had thought to ask the question before.”
Using the NCNR’s neutron and X-ray diffraction devices as their microscope, the team explored how a model cell membrane responded to two chemicals—inhaled anesthetic, and another that has many of the same chemical properties as anesthetic but does not cause unconsciousness. Their finding showed a distinct difference in the way the lipid rafts responded: Exposing the membranes to an anesthetic caused the rafts to grow disorderly, freely mixing its lipids with the surrounding membrane, but the second chemical had a dramatically smaller effect.
While Nanda says the discovery does not answer the question definitively, he and his co-authors are following up with other experiments that could clarify the issue. “We feel the discovery has opened up an entirely new line of inquiry into this very old puzzle,” he says.
* M. Weinrich, H. Nanda, D.L. Worcester, C.F. Majkrzak, B.B. Maranville and S.M. Bezrukov. Halothane changes the domain structure of a binary lipid membrane. Langmuir, Feb. 21, 2012. DOI: dx.doi.org/10.1021/la204317k.
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'Nanoslinky': A Novel Nanofluidic Technology for DNA Manipulation and Measurement
Remember Slinky®, the coiled metal spring that “walks” down stairs with just a push, momentum and gravity? Researchers at the National Institute of Standards and Technology (NIST) have developed their own version of this classic—albeit 10 million times smaller—as a novel technology for manipulating and measuring DNA molecules and other nanoscale (billionth of a meter) materials.
In the first of two recent papers,* Samuel Stavis, Elizabeth Strychalski and colleagues demonstrated that a nanoscale fluidic channel shaped like a staircase with many steps (developed previously at NIST and Cornell University**) can be used to control the otherwise random drift of a DNA molecule through a fluid. Squeezed into the shallowest step at the top of the staircase, a strand of DNA diffuses randomly across that step. The DNA molecule seeks to increase its entropy—the universal tendency towards disorder in a system—by relieving its confinement, and therefore, “walks” down onto the next deeper step when it reaches the edge. The motion of the molecule down the staircase, which the researchers termed “entropophoresis” (entropy-driven transport), ends when it becomes trapped on the deepest step at the bottom. Because this motion resembles that of a Slinky®, the researchers nicknamed their system the “nanoslinky.” The researchers found that DNA molecules of different sizes and shapes descended the staircase at different rates—which suggests the structure could be used to separate, concentrate and organize mixtures of nanoscale objects.
Stavis says that this novel technology provides advantages over traditional nanofluidic methods for manipulating and measuring DNA. “Control over the behavior of a DNA molecule is built into the staircase structure. After placing the molecule on the top step [by driving the DNA strand up the staircase with an electric field], no external forces are needed to make it move,” Stavis says. “The staircase is a passive nanofluidic technology that automates complex manipulations and measurements of DNA.”
This NIST advance in nanofluidic technology dovetails nicely with a NIST innovation in measurement science—specifically, determining the size of a DNA molecule in nanofluidic “slitlike confinement” imposed by the narrow gap between the floor of each step and the ceiling of the channel. In the “nanoslinky” system, Strychalski explains, the coiled and folded DNA strand contracts progressively as it moves down the steps. “Because there are many steps, we can make more detailed measurements than previous studies,” she says.
Getting the most from those measurements was the goal of the research reported in the NIST team’s second paper. *** “The challenge was to make our measurements of DNA size more quantitative,” Strychalski says.
Previous measurements of DNA dimensions in nanofluidic systems, Strychalski says, have been limited by imaging errors from the optical microscopes used to measure the dimensions of DNA molecules labeled with a fluorescent dye. “The first problem is the diffraction limit, or the optical resolution, of the fluorescence microscope,” she says. “The second problem is the pixel resolution of the camera. Because a DNA molecule is not much larger than the wavelength of light and the effective pixel size, images of fluorescent DNA molecules are blurred and pixilated, and this increases the apparent size of the molecule.”
To improve their measurements of DNA molecules during their descent, the NIST researchers used models to approximate the effects of diffraction and pixilation. Applying these “numerical simulations” to the images of DNA molecules confined by the staircase made the final measurements of DNA size the most quantitative to date. These measurements also showed that more work is needed to fully understand this complicated system.
According to Stavis and Strychalski, the staircase is a simple prototype of a new class of engineered nanofluidic structures with complex three-dimensional surfaces. With further refinements, the technology may someday be mass produced for measuring and manipulating not just DNA molecules, but other types of biopolymers and nanoscale materials for health care and nanomanufacturing.
Slinky® is a registered trademark of POOF-Slinky, Inc.
* S.M. Stavis, J. Geist, M. Gaitan, L.E. Locascio and E.A. Strychalski. DNA molecules descending a nanofluidic staircase by entropophoresis. Lab on a Chip (2012). DOI: 10.1039/c21c21152a.
** See the April 7, 2009, Tech Beat article “World’s First Nanofluidic Device with Complex 3-D Surfaces Built” at www.nist.gov/public_affairs/tech-beat/tb20090407.cfm#nanofluidic.
*** E.A. Strychalski, J. Geist, M. Gaitan, L.E. Locascio and S.M. Stavis. Quantitative measurements of the size scaling of linear and circular DNA in nanofluidic slitlike confinement. Macromolecules (2012). DOI: 10.1021/ma202559k.
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NIST Releases Technical Guidance for Evaluating Electronic Health Records
An important aspect of any product is how easily someone can use it for its intended purpose, also known as usability. Electronic health records (EHR) that are usable have the potential to improve patient care, which is why the National Institute of Standards and Technology (NIST) has outlined formal procedures for evaluating the usability of EHR systems.
The proposed usability protocol encourages a user-centered approach to the development of EHR systems. It provides methods to measure and address critical errors in user performance before those systems are deployed in a medical setting.
“This guidance can be a useful tool for EHR developers to demonstrate that their systems don’t lead to use errors or user errors,” said NIST researcher Matt Quinn. “It will provide a way for developers and evaluators to objectively assess how easy their EHR systems are to learn and operate, while maximizing efficiency.”
The protocol is a three-step process consisting of an analysis of how the application functions, expert review, and validation testing of the user interface to make sure it works as intended.
The protocol includes general steps and guidance for evaluating an EHR user interface from a clinical perspective—does it contain, collect and display the information it needs to—and human factors perspectives—can the user understand it and easily find needed information. The interface is then tested by representative user groups performing realistic tasks.
“We hope this encourages system developers to apply human factors best practices and incorporate user-centered design processes,” said Quinn. “These practices and processes have proven records in industries such as aviation, military systems, transportation, nuclear power, and others where safety is a concern.”
The EHR Usability Evaluation Protocol (EUP), Technical Evaluation, Testing and Validation of the Usability of Electronic Health Records (NIST Interagency Report 7804), is available at www.nist.gov/healthcare/usability/index.cfm. A draft version of the document was released for public comment in September 2011. The current version incorporates feedback received.
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NIST Announces $2.6 Million in Funding for Novel Semiconductor Research
The National Institute of Standards and Technology (NIST) is soliciting proposals to support long-term research in next-generation semiconductor technology, which is critical to the future of the U.S. electronics industry.
To launch the effort, NIST plans to provide up to $2.6 million in federal cost-shared funding for a project’s first year, with the potential for continued funding for up to five years. Under the terms of the proposal request, posted March 15, 2012, at Grants.gov (www.grants.gov), the consortium that receives the funding will be required to provide a minimum of 25 percent of its budget from nonfederal sources.
The new effort targets the development of novel technologies that will be radically different than what is used in today’s computer chips, known as complementary metal oxide semiconductor (CMOS) technology. CMOS is expected to reach its physical limits within 10-15 years as components shrink to the atomic scale, rendering it more and more difficult to increase the density of components on a chip and achieve low-power operation.
NIST seeks to support a program involving an industry-guided partnership—possibly including commercial, academic, nonprofit and/or governmental organizations—to help overcome these technical hurdles. Accordingly, the funding recipient is expected to be a consortium of organizations that can undertake a far-reaching effort beyond the resources of any individual consortium member.
Proposal submissions must be received no later than 5 p.m. Eastern time on Monday, April 16, 2012. Selection and award processing is expected to be completed in July, and the earliest anticipated start date for awards is expected to be October 1, 2012.
For more information, including submission guidelines and evaluation criteria, please visit www.grants.gov and search for Funding Opportunity Number 2012-NIST-POST-CMOS-01.
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NIST April Workshop to Examine Federal Conformity Assessment Practices
The National Institute of Standards and Technology (NIST) is hosting a free public workshop on best practices in federal conformity assessment activities Wednesday, April 11, 2012, at NIST’s Gaithersburg, Md., site. “Conformity assessment” determines whether a process, product or service meets standards and requirements, and the process has important consequences. Federal conformity assessments impact the regulatory process, international trade, procurement and federal assistance programs.
The “Energy Star” program that directs consumers to energy efficient appliances is one familiar example of a voluntary conformity assessment program supported by a federal agency. Other federal conformity assessment programs provide confidence in the safety of electrical equipment used in regulated workplaces in the United States.
The NIST workshop is being held to examine current approaches to conformity assessment at federal agencies and in the private sector. It will provide a forum for federal agencies, private industry and other stakeholders to give feedback to NIST on conformity assessment practices, the challenges encountered and the ways these challenges are being addressed.
The workshop will include panel discussions on the breadth of conformity assessments in the federal arena, and examine case studies and international conformity assessment. Workshop attendees also will be asked to provide comments related to a planned update of the Guidance on Federal Conformity Assessment Activities (15 C.R.F. Part 287).
NIST is required under the National Technology Transfer and Advancement Act to coordinate federal, state and local standards activities and conformity assessment activities with the private sector with the goal of eliminating unnecessary duplication and complexity.
For more information on the workshop and to register, see www.nist.gov/director/sco/ca-workshop-2012.cfm.
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NIST Announces Funding to Form Steering Group to Support Trusted Identities in Cyberspace
On March 9, the National Institute of Standards and Technology (NIST) announced that it is soliciting proposals to establish a steering group in support of the National Strategy for Trusted Identities in Cyberspace (NSTIC) and to provide the group with ongoing secretarial, administrative and logistical support. NIST anticipates supporting one proposal with approximately $2 million in funding for up to two years.
In April 2011, President Obama released NSTIC as a way to improve security in cyberspace and e-commerce. NSTIC charts a course for the public and private sectors to collaborate to raise the level of trust associated with the identities of individuals, organizations, networks, services and devices involved in online transactions.
"This grant will help to establish an independent steering committee led by the private sector that works in conjunction with the federal government to support NSTIC,” said Jeremy Grant, NIST’s senior executive advisor for identity management. “The committee will guide creation of an ‘Identity Ecosystem’ in which businesses and individuals can have more confidence in the security and privacy of their online transactions. The committee will also be responsible for identifying resources that will support the effort into the future.”
Accredited institutions of higher education, non-profit organizations and commercial organizations located in the United States and its territories are eligible to submit a proposal for the NSTIC Steering Group Secretariat Cooperative Agreement. Proposers are expected to maintain a neutral stance toward the outcome of the steering group process and must agree not to become a voting member of the steering group.
The purpose of the cooperative agreement is to fund a secretariat for the steering group during its initial and early phases. A major role of the secretariat is to serve as an honest broker between multiple stakeholders, with a focus on facilitating the creation of consensus standards and policies that will serve as the foundation of the Identity Ecosystem. Given this, it is important that the entity selected through this funding opportunity be objective and independent.
The recently released Recommendations for Establishing an Identity Ecosystem Governance Structure for the National Strategy for Trusted Identities in Cyberspace (“Governance Recommendations”) provides guidance for the steering committee and should serve as a “touchstone” for proposals, according to the solicitation. The report can be found at www.nist.gov/nstic/2012-nstic-governance-recs.pdf.
Applications are due on April 11, 2012. For detailed information and application requirements, see the entry at Grants.gov (www.grants.gov) for the National Strategy for Trusted Identities in Cyberspace (NSTIC) Steering Group Secretariat Cooperative Agreement at http://www07.grants.gov/search/search.do?&mode=VIEW&oppId=151313.
NIST will hold a webinar information session for organizations considering applying to this opportunity on Mon., March 19, 2012. Organizations wishing to participate in the webinar must register at the NIST public Web site http://www.nist.gov/itl/nstic-031912.cfm.
On Thurs., March 15, NIST will host the NSTIC Identity Ecosystem Governance Workshop at the Department of Commerce in Washington, D.C. The workshop will review and take questions on the Governance Recommendations and on specific issues concerning the establishment of the governance structure. For more information and to register for the workshop (which will also be webcast), visit www.nist.gov/itl/nstic_ieg_workshop.cfm.
Further information about this event and other upcoming NSTIC events will be available at: www.nist.gov/nstic.
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Federal Committee Seeks Information on Domestic Forging Capabilities
Does the United States have sufficient industrial capabilities to produce adequate supplies of forged-quality metal parts to meet the needs of the Defense Department and other federal agencies?
That is what the Metal Fabrication Study Group, part of the interagency Defense Production Act Committee (DPAC), wants to know. The study group has issued a request for information at FEDBIZOPS.gov (www.governmentbids.com).
Responses are due no later than 3 p.m. Eastern Time, April 9, 2012.
Forged-quality parts are essential components of aircraft wheels and landing gear, vehicle armor, energy generation equipment, railroad cars, rocket engines, and other manufactured products.
The study group, led by Howard Harary, deputy director for manufacturing in the Engineering Laboratory of the National Institute of Standards and Technology, conducted an initial survey of domestic forging capabilities. It found that current capabilities stem from investments made several decades ago, yet the need for forged-quality parts has not diminished. As a consequence, supplies of some critical forged-quality parts have been inadequate to meet important government needs.
In its request, the study group seeks industry insights into ways to address current limitations on supplies of forged-quality parts, as well as to understand the opportunities to address those limitations. Key areas of interest include process capabilities and limitations, supply-chain-related issues, and alternative manufacturing methods and barriers to their implementation.
Under the Defense Production Act of 1950, the DPAC advises the president on strategies to ensure adequate domestic production of critical components, critical technology items, and industrial resources essential for national security.
Read more about the DPAC at http://www.dpacommittee.com/. The study group’s request for information is at https://www.fbo.gov/index?s=opportunity&mode=form&id=bebaebd0f1bc3190b2cd97553dc87dfa&tab=core&_cview=0.
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