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Lab News -- December 9, 2005

December 9, 2005

LabNews 12/09/2005PDF (650KB)

Researchers model nano-size battery to be implanted in eye to power artificial retina

By Chris Burroughs

Several Sandia researchers, led by principal investigator Susan Rempe (8333), are part of a multi-institutional, multidisciplinary team developing a nano-size battery that one day may be implanted in the eye to power an artificial retina.

They are among the recipients of a five-year, $6.5 million grant recently awarded by the National Eye Institute of the National Institutes of Health (NIH) to establish a new center, the National Center for Design of Biomimetic Nanoconductors. Based at the University of Illinois Urbana-Champaign under the direction of principal investigator Eric Jakobsson, the center is designed to rapidly launch revolutionary ideas in the use of nanomedicine.

The center will design, model, synthesize, and fabricate nanomedical devices based on natural and synthetic ion transporters — proteins that control ion motion across the membranes of every living cell.

The first task for the center will be to design a class of devices for generating electric power — biobatteries — for a wide array of implantable devices, starting with an artificial retina that has already been developed at the Doheny Eye Institute at the University of Southern California. The artificial retina and accompanying nanobattery will be used to combat certain types of macular degeneration.

Sandia’s role is on the theoretical and computational side of the project, according to Susan.

Understanding and predicting

“We will use our expertise in multi-scale modeling to understand and predict how transporter structure leads to function, with an initial focus on specialized transporters found in the specialized electric organs of certain fish,” Susan says. “This information will give us a better understanding of how power is naturally created in biological organisms — information to be used for designing and building the nanobattery.”

Speaking of the vital role of modeling, she adds, “If you don’t understand it, you can’t engineer it.”

Ultimately the algorithms, software, design expertise, and scientific knowledge gained through the modeling efforts, in which Susan is joined by Kevin Leung (1114) and Steve Plimpton (1412), will be shared with the external community through workshops, seminars, conferences, and collaborations.

Working on another aspect of the project is Jeff Brinker (1002), who is affiliated with both Sandia and the University of New Mexico. He will engineer components of the biobattery using silica technology.

The team plans to translate several categories of biological function into new devices that would treat disease and lead to implantable devices. Properties of interest that appear in the biological ion transporters include electrical signaling, osmotic pumping, and molecular detection.

A multi-institutional project

Sandia is one of the center’s participants, as are the Doheny Eye Institute at the University of Southern California, the Illinois Institute of Technology, Purdue University, the University of California-Davis, the University of Illinois at Ubana-Champaign, Oxford University (UK), Wabash College, and Weill Medical College of Cornell University.

The National Center for Design of Biomimetic Nanoconductors is part of a package of about $43 million for four advanced national centers in nanomedicine announced this year under the NIH’s New Pathways to Discovery Program. The NIH program began in 2003 as a Roadmap for Medical Research initiative to spur medial research discoveries from bench to bedside. The other centers will be at the Baylor College of Medicine in Houston, the University of California at San Francisco, and Columbia University in New York City.

-- Chris Burroughs

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Sandia researchers aim to keep points-of-entry safe through systems-level modeling of operations

By Mike Janes

Carolyn Pura (8115), program deputy for borders and transportation security in the Labs’ Homeland Security Strategic Management Unit, is blunt in assessing the nature of her job. “Protecting our borders is difficult and expensive,” she says.

Almost as quickly, however, she asserts that Sandia’s recent work on border security is well on its way to becoming an enormously valuable national asset by providing federal agencies with a reliable and comprehensive simulation capability that lets officials “test drive” various security solutions before investing in them.

The focus of the Borders Grand Challenge, funded by a three-year, $6 million Laboratory Directed Research and Development project, was to develop simulation-based systems analyses characterizing the security of the US Border System and the impact of new detection technologies and concepts of operation. The work capitalizes on a range of existing Sandia capabilities, including the Weapons of Mass Destruction Decision Analysis Center (WMD-DAC), the National Infrastructure Simulation and Analysis Center (NISAC), and even the Labs’ robotics expertise. Some 21 Sandia researchers from both the California and New Mexico sites worked on the project, with Carolyn serving as principal investigator and Dan Horschel (6221) as project manager.

Models examine flow of people, goods

The interactive analysis that serves as the hallmark of the program has largely focused on illegal smuggling of radiological/nuclear material but can also be applied to other threats such as explosives or chemical/biological agent attack. The work uses detailed models that replicate actual facilities and procedures and examines border operations of all kinds. Of utmost concern is the flow of people and goods through the various border choke points.

“There is a cost-benefit tradeoff associated with any technology that might be used in border security,” Dan explains. With commerce, for example, officials must consider the flow of people and goods crossing the border, any delays that may occur due to security provisions, and operational costs that emerge as a consequence of the flow and delay. Sandia’s unique systems-level methodologies and tools address these complexities and allow homeland security officials to make data-driven decisions.

Mark Ehlen (6221) served as the lead for economic modeling. Mark points out that a unique feature of the program is its ability to project the economic impact that might be felt if a venue implements certain security options. A typical port whose processing time increases due to a newly configured set of chemical detectors, for example, might expect to increase its on-site inventories and shipments by up to 15 percent, leading to increased business costs and decreased sales. In addition, says Mark, firms that ship through the port will be affected by delays and increased costs and may take their business elsewhere. Such consequences will fluctuate from venue to venue, of course, depending on the security measures and the venue’s own operational plan.

Sandia’s models, by simulating the effects of detector placement, the use of facial recognition software, or the impact of other technology devices and strategies, can give decision-makers specific and reliable data to help make sound decisions about how and where to invest.

Mid-fidelity vs. High-fidelity modeling

The models themselves come in two primary forms.

“Mid-fidelity” models offer a broader, bigger-picture look at a border location that might give users the ability, for example, to view personally owned vehicle and cargo vehicle flows at an actual facility, using that facility’s own procedures. A “higher-fidelity” model, seen on the computer screen when the operator “zooms in” on the activity, might focus on security interrogation and feature detailed sensor modeling. High-fidelity models, because of their visualization features and accurate geometries and motion, provide a sound environment for training and can be quickly reconfigured to address border concepts of operation.

Sandia’s models have been integrated to include multiple domains, including air, sea, and land. All domains have been built with the capability to analyze the impacts of different types of sensing equipment, from radiation detection to x-ray equipment. Both a land-crossing pedestrian model and an airport, for example, examine the movements of people and look at biometrics technology, while a seaport and land cargo port analyze cargo inspection equipment.

“Hot source” dilemma

One significant issue that security officials face is the problem of “hot sources.” These occur when multiple detectors sound alarms simultaneously due to benign radiation sources. Hot sources significantly disrupt port operations by causing large delays while the source is sorted out and determined to be non-threatening.

Sandia’s modeling helps system users address the hot source problem by examining various detection scenarios and options to consider. An “in-situ” option, where traffic is stopped while threat sources are localized with a portable detector and removed from the primary traffic stream, might be suitable for certain venues. Others might choose to maintain a “self-identification pre-sort” traffic lane that allows medical patients or known radioactive shipments to sort themselves out of traffic. Sandia-developed simulations help officials identify the best “encounter geometry” within their facilities and the most “throughput-friendly” detector locations.

Though Carolyn and Dan say the work represents the most comprehensive modeling work available on border security, the research has the potential to go much further. Ideally, Sandia could extend the capability to all ports of entry across the country, creating a complete national model that is able to examine changing security measures and operations and their impact. “What we have now are high-quality, targeted studies,” says Dan. “The value a national model could offer decision-makers at the highest level could be immeasurable.”

-- Mike Janes

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Exciting beginning, interesting future: Z machine turns 20

By Neal Singer

It was a “mere” 20 years ago on Dec. 11, 1985, that a 108-ft.-diameter Sandia machine then called PBFA-II first made the ground shake, lit up the surface of the water surrounding its tiny target area with electrical arcs and sparks, and generated talk of controlled nuclear fusion from jubilant researchers.

Tension had built for weeks in Area 4 as to whether the huge machine, which sent massive electrical currents surging through 36 transmission lines to activate a lithium ion beam, would work as planned. Some thought it might not. Some thought it might explode.

The tension, reported the Lab News at that time, was similar to that before the last game of a tight World Series.

Theme music of the TV series “Star Trek” played over loudspeakers with voice-overs reminding the listeners that Sandia “boldly goes where no man has ever gone before.”

“Most exciting moment of my life”

This exhilarating message was soon replaced by a dour disclaimer, humorously borrowed from the television show “Mission Impossible”: “As always, if you fail, Sandia and DOE will disavow any knowledge of your mission.”

“The most exciting moment of my life,” said former Sandia VP Pace VanDevender, then director of pulsed power sciences, when the first shot proved successful.

VP Gerry Yonas (7000), one of the machine’s founding fathers, listened on a telephone line from Washington, where he was serving as the Strategic Defense Initiative’s chief scientist. He afterwards declared himself speechless, then said, “I could feel the machine’s vibrations up my spine all the way across the country.”

More measurably, according to Mary Ann Sweeney (1670), who was present at the time, scientists and engineers who could not fit into the building’s crowded control room felt the ground shake in Bldg. 960 hundreds of feet away.

Believe it or not

Since then, many things have happened.

The machine was featured in Ripley’s “Believe It Or Not” list of oddities with this somewhat obscure citation: “At Sandia National Laboratories in Albuquerque, N.M., a futuristic research center can make more power than all US utilities produce at any one time dance on the head of a pin.”

Ktech technicians Dan Jobe (1670) and Scott Drennan (1654), who took the first photos of PBFA-II firing, found that their photographic techniques lived on. Open-shutter methods they employed were used subsequently by Walt Dickenman (dec.), and nearly a decade later by Sandia staff photographer Randy Montoya (3651) who created the most widely reproduced picture Sandia ever released: the “arcs and sparks” light show of the accelerator firing.

“Dan and Scott knew the pond,” says Randy, “and they showed the rest of us where to stand to get the best fish.”

The two technicians had experimented with open-shutter photography to aid them in looking for breakdowns in the accelerator when it fired. Among media that published images based on the pair’s early expertise was National Geographic magazine. Among the many places a Sandia-taken “arcs and sparks” photo appeared was the cover of the book Physics in the 20th Century, published by the American Physical Society to celebrate its 100th anniversary. The author, former Washington Post writer Curt Suplee, learned of Z at a meeting with Sandia media staff.

Probably one of the most significant moments in the machine’s later history occurred ten years ago when researchers replaced the lithium ion beam diode with a simple Z-pinch containing many wires.

Soon afterwards, the Particle Beam Fusion Accelerator exchanged its wordy moniker for a single letter — Z — but controlled nuclear fusion remains a goal for Sandia’s Z machine.

Sandia refines Z-pinch concept

A Z-pinch wire array is essentially the size of a spool of thread, with tungsten wires about a tenth the thickness of a human hair hung vertically over the spool, rather than wrapped around it horizontally as is the practice with cotton thread.

While wire-array Z pinches had been used for decades, Sandia’s innovation was to dramatically increase the number of wires — something that had never been satisfactorily done.

Electrical current surging through the tiny wires obliterates them in what is effectively a massive short circuit. The magnetic field of the current compresses the resultant cloud of tungsten ions like a fist closing on a sponge. When the ions have nowhere further to go — at about the thickness of a pencil lead in the vertical, or Z, direction — their sudden braking from speed that is a significant fraction of the speed of light releases more energy and power in X-rays than ever before achieved in a laboratory.

The immediate surge in X-ray power output at that time led many to wish their stock market holdings produced graphs with such vertical rises in prices.

As the X-ray power output doubled, tripled, and then quadrupled, Sandia researchers were able to produce fusion neutrons — a feat reported at the March Meeting of the American Physical Society two years ago.

The story continues into the present with the addition of one of the world’s most powerful lasers, dubbed Z-Beamlet, to image Z’s compression of target capsules.

The X-ray intensities needed to drive capsules to the still-distant goal of break-even fusion, researchers say, must be generated by a much larger machine.

Meanwhile, the Z machine will soon take a rest while its 20-year-old capacitors and switches are replaced by more modern technology. And then the flashes and groundshakings and onward march toward fusion will continue, with attendant work in testing materials under huge compression, launching swift flyer plates with magnetic propulsion, characterizing the composition of the cores of planets and the sun, simulating environments around neutron stars and black holes, and observing defense-related tests not suitable for discussion here.

As the wry joke goes, break-even with controlled nuclear fusion is probably still only 20 years away. But given recent progress, along with anticipation of new results made possible by the coming upgrade, the role of Z as a possible avenue to the high-energy future cannot be understated.

Says current director Keith Matzen (1600), “Our intensity and enthusiasm remain high to create a significant fusion burn.” -- Neal Singer

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