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SANDIA LAB NEWS

March 4, 2005

LabNews 03/04/2005PDF (805KB)

Sampling 'small atmospheres' in the tiny new worlds of MEMS

By Neal Singer

Just as astronomers want to understand the atmospheres of planets and moons, so engineers want atmospheric knowledge of worlds they create that are the size of pinheads, their “skies” capped by tiny glass bubbles.

Should their silicon inhabitants — microcircuits, microgears, and micro-power drivers — exist in a vacuum? An atmosphere of nitrogen? Air as we know it? More important, whatever atmosphere was intended, how long will it stay that way? Is the protective barrier hermetic or will its atmosphere change over time, potentially leading to the early death of the device? Will water vapor seep in, with its sticky molecules causing unpredictable behavior? What, in short, can engineers say about how long this little world and its inhabitants will survive and function?

The most advanced place in the world for such evaluative work is at Sandia. “I know of no one, anywhere else, who can do this kind of testing,” says Steve Thornberg (1861) of the sampling procedure he developed to look at small atmospheres with University of New Mexico undergraduate chemistry student Therese Padilla and graduate chemistry student James Hochrein.

John Maciel agrees. Chief Operating Officer of Radant MEMS, a three-year-old start-up company in Stow, Mass., he is under contract with DARPA to develop high-reliability MEMS (microelectromechanical) switches for microwave devices and phased array antennas. He also sees markets for his MEMS switches in cell phones. For long-term reliability, small-atmosphere stability is a must. “We can’t go to a commercial house to get this work done,” he says. “We can’t find the capability anywhere else but Sandia.”

His parts are checked here under a subcontract with DARPA.

The Sandia method — funded by LDRD, revealed in late January at the SPIE Photonics Meeting in San Jose, Calif., and presented for consideration to Sandia’s patent office — involves a small commercial valve that comes down like a trash compactor and crushes a tiny device until it releases its gases — currently, about 30 nanoliters — into a custom-built intake manifold.

Picobursts of gas

Because Steve’s test mechanism requires only picoliters, his sensitive device can recheck measurements — using bursts of gas delivered in a series of puffs — dozens of times from the same crushed device in a 20-minute time span.

The method thus provides statistically significant atmospheric measurements at any given moment in a component’s life cycle. (Current industry tests can achieve at best only a single reading from the release of nanoliters of gas. A single, statistically unverifiable result may contain significant error.)

By waiting a longer period of time — weeks, or even months — other microdevices from the same batch can be crushed and then analyzed to see what changes have occurred in their atmosphere over time.

Currently, the system is able to measure gases emerging in pressures ranging from one atmosphere to 10 to the minus 4 torr. (One atmosphere is 760 torr.) The group hopes soon to decrease its lower sensitivity limit to 10 to the minus 6 torr — in effect, to be able to measure the quality of vacuums.

Danelle Tanner (1762), who describes herself as “a reliability-and-aging mechanism physicist” working on the silicon re-entry switch of the SiRES package for MESA, says, “We want 100 percent nitrogen [atmosphere] in our device. Steve’s group gave us a really good idea of what species other than nitrogen were present in the package.”

“Maintaining the integrity of the internal atmosphere of a hermetic device is essential for long-term component reliability,” says Steve. “It is within this environment that all internal materials age.”

Success of his group’s new investigatory technique lies in the details of the test mechanism.

A precisely machined sample holder holds the MEMS package to be crushed within the sampler valve. If the sample holder is too low, the part would not crush the MEMS device; too high, and the device would crush prematurely, letting gases escape unmeasured.

Because tested devices come in many sizes, height adjustments to the crushing mechanisms are needed for each sample

The problem of debris from the smashed MEMS part interfering with gases that must pass through tiny tubes was solved by sintering a filter into a central gasket. Perhaps most important, manifold volumes were minimized to maximize pressures when MEMS-released gases expand, reducing the amount of gas needed for an analyzable puff.

Still ahead is success in measuring very small amounts of moisture, which stick to manifold walls without making it to the detector.

To overcome this problem, the Sandia group is working with Savannah River National Laboratory to incorporate that lab’s optical moisture measurement techniques based on surface plasmon resonance (SPR). In that technique, an optical fiber is used to transmit light from a specially coated lens. Moisture levels are measured from wavelength shifts.

Says Fred Sexton (1762), “Steve’s group is making great inroads on measuring atmospheric composition in very small packages. This work was performed under an LDRD championed by the Reliable Predictable Microsystem Program.” -- Neal Singer

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You are ‘great explorers of our society,’ DOE Secretary Samuel Bodman tells Sandia researchers

By Bill Murphy

A chemical engineer by training and temperament, just-confirmed DOE Secretary Samuel Bodman told a near-capacity audience of Sandians at the Steve Schiff Auditorium that he is “in a bit of awe at being here, a bit in awe of the technical excellence and historical significance that Sandia and its sister laboratories represent. I consider it to be a personal and professional honor to be here.”

Bodman, making his first official trip as DOE secretary, received a day-long series of briefings at Sandia last week before speaking to the all-hands meeting that afternoon. Although Bodman spent many years in the financial industry — he was CEO of Fidelity Investments after serving as head of Fidelity Ventures — and served as deputy secretary in both the Commerce and Treasury departments during President Bush’s first administration, he still “I like to think I have retained the perspective of an engineer.” (He has a PhD from MIT and taught chemical engineering there for several years.)

In measured and deliberate words, Bodman spelled out his thoughts about his new job, his expectations of the laboratories, and his hopes for the continued relevance and success of DOE.

Speaking about how he will approach his job, Bodman cited lessons he learned in his reading of Richard Rhodes’ Pulitzer Prize-winning classic, The Making of the Atomic Bomb.

The book, he noted, offered deep insights into the personalities and the thinking of that generation of scientists who embodied — even invented — 20th century science.

The voices of those pioneering giants, coming to us across the span of years, Bodman said, can teach us that “science and technology have consequences.” “Now, that may sound like a simple idea — even trite — but I think its something worth reminding ourselves about.

“Research has implications beyond the quest for the accumulation of knowledge. Some outcomes are miraculously positive . . . but some have the potential to cause great harm. Does the fact that scientific advances may be used for catastrophic ends mean that we should not pursue them? Of course the answer to that question is no. But we must be aware of potential consequences and carefully consider them.

“In other words, as world-renowned engineers, chemists, biologists, materials scientists, computer scientists, developers of microsystems, and nanotechnology, you embody both vast opportunity and great responsibility.”

That responsibility, Bodman said, extends “beyond your commitments to intellectual rigor and ethics. You have real responsibilities to society. It is a public trust that we as a nation placed in our scientists and engineers and it is one that is well-earned.

“Our nation counts on you for great science, but it also counts on you to safeguard our most precious scientific information, information that must be protected from disclosure to ensure our collective national defense. In addition, you have a fundamental responsibility to protect yourselves and your fellow workers from harm so that you can continue to do the valuable science and engineering for which this great laboratory is known.

“Let me be crystal clear about this: It is unimaginable to me that one can separate scientific and technical excellence from security and safety at this laboratory, or anywhere else throughout our nuclear weapons complex.

“I expect that safety and security are integral to what you do and how you do it. No matter the temptations, scientific or otherwise, we must never lapse into complacency, [which is] the enemy of safety.

“Simply put, safety and security are critical, essential, and inexorably linked components of our mission at this lab. We cannot guarantee security if there are lapses in our safety, and we cannot guarantee safety if we compromise our security.

“I would hope that you will view me as a colleague, and I would like to think that you will be pleased at the work we will do together.

“This department started 60 years ago — not formally but started in fact 60 years ago on a nice spot in the desert of New Mexico. It is not random that I have come here on my first trip as your leader.

“To me, you are the great explorers of our society, people who are energetically pushing us forward into the unknown, to better, more prosperous, safe, and more secure days ahead. But also, be ever-cautious of the path you are forging. That is how I see you, and that is how I see this laboratory and this department. And that is how I hope the American people will come to view us and the work you do here.

“I commit to you that I will do everything in my power to ensure that the people of this laboratory receive the proper credit for what they have done in the past, for what they are doing in the present, and for what they will do in the future. In return, I would ask for your commitment to work with me to help find solutions to the common challenges that we face together and to move us forward to a future of many more breakthroughs and many more successes of the sort that you have experienced in the past.” -- Bill Murphy

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Success story for Sandia’: Munitions-destroying Explosive Destruction System shown to employees

By Nancy Garcia

Sandia, UT unveil agreement for close strategic partnership

“A success story for Sandia” is how John Didlake (8228) characterized the Explosive Destruction System (EDS), of which he is the project manager, during an overview for employees last month when the fifth and final EDS left Sandia/California.

The EDS is a customized flatbed trailer with a vessel that resembles a large, front-loading washing machine in which explosively configured chemical munitions can be destroyed in a contained manner. The Army approached Sandia 10 years ago seeking an alternative to open burn/open detonation of aging, unstable munitions recovered on former Department of Defense property that has been turned over to public use or borders public developments.

238 operations, tests already

“Processing three to six munitions in a year was the original envisioned usage of the system,” John said. In the last six years, however, there have been 238 Army operations and tests in which 106 actual recovered munitions were destroyed — including one on the very morning of his talk (in a previously delivered system at Aberdeen Proving Ground in Maryland). The other operations included 56 destructions of cylinders bearing chemical agent and 76 of simulated agent. (Simulated agent tests are used for procedures verification and crew training.)

Just the week before his talk, Sandia issued a report documenting the system’s efficacy against surrogates of anthrax, Bacillus thuringiensis and Bacillus stearothermophilus. The Sandia team undertook a $60,000 Laboratory-Directed Research and Development project to demonstrate its effectiveness against bacterial spores, which could provide a means to neutralize an improvised terrorist device.

“There’s high value in extending the EDS’ successful track record into other areas,” said Technology Application Dept. 8228 Manager Mary Clare Stoddard. “Should the need arise, a solution stands ready” for destroying weapons bearing biological agents, of which anthrax is among the most resistant to disinfection.

Sandia’s novel concept

Operated by Army ordnance disposal experts, the system, she said, marries previously existing technologies in a novel way. Sandia’s concept was to first detonate a device’s explosives, then neutralize the agent it contains, all within a sealed stainless steel vessel.

Explosive charges are applied on the outside of the device to explode the munition’s burster and cleave open the shell, exposing the agent inside. The charges are set off inside a fragment-suppressing pipe loaded into the vessel.

Then chemical reagents are pumped into the sealed vessel, which is agitated and heated to accelerate neutralization. The effluent is collected for environmentally sound disposal.

The latest EDS unit was just transported from Livermore to Albuquerque for more explosives testing. It is one of two larger units, with a vessel volume of 160 gallons, able to handle 4.8 lbs. of TNT equivalent. The entire trailer weighs 55,000 lbs. and was custom-made for the US Army Non-Stockpile Chemical Materiel program.

It is deployed along with a diesel power generator and a utility trailer containing spare parts, consumables, and tools. John said EDS is unique in being the first and so far, only, system certified to destroy these type weapons in the US. It has been approved by both the military and regulators in the five states where it has been used (Alabama, Colorado, Delaware, Maryland and Utah). An Army study identified more than 100 sites around the country where aging munitions might be uncovered.

If necessary, the $3.5 to $5 million systems can be air-shipped to respond to unearthing of a vintage munition of uncertain pedigree. When a munition is recovered from a former testing site or other civilian location, it is nondestructively imaged to determine its fuzing and contents. The system processing is then operated in keeping with those observations, and the results are checked by testing vessel contents before they are drained and the vessel door opened.

The EDS was designed to be transported because, by Department of Transportation regulations, an explosively configured recovered munition cannot be moved. Three smaller systems, an initial prototype that was put into operation and two “production” models, have a vessel rating of just over 1 lb. TNT equivalent and are compact enough to ship in an Army C-141 aircraft (the larger systems would require an Air Force C-5A). These smaller systems are capable of handling 90 percent of the munitions the Army expects to find.

‘Things started working quickly’

Early on, EDS was dispatched to Porton Down in England for testing on WWI-era recovered shells and projectiles. From December 1999 to November 2000 the first system destroyed 12 munitions there containing phosgene and 14 containing mustard.

One additional test was conducted at Porton Down just before the system came back to the US and demonstrated EDS could destroy a container with 1.3 lbs. of sarin. Meanwhile, six sarin-filled bomblets, the size of a grapefruit, were found at Rocky Mountain Arsenal outside Denver, currently a Superfund cleanup site.

Although EDS was ranked fifth of the alternatives considered for ridding the arsenal of the bomblets, it was picked on Dec. 1, 2000, at the urging of the Colorado governor and the six were destroyed starting on Superbowl Sunday in 2001. “Things moved very quickly because a four-star general wanted it to happen,” John said.

Four more bomblets were destroyed there just after the Fourth of July in 2001, and in 2002, EDS was put into action over Labor Day, disposing of an armed and fuzed phosgene-containing mortar found in a farmer’s field (formerly Camp Sibert land) near Gadsden, Ala. “We don’t get holidays on this program,” John quipped.

In fact, the morning of the talk he’d been roused at 5 a.m. with a technical question from Aberdeen, where the second Lewisite munition to be destroyed in this country was being neutralized, a three-day-long operation due to the complex chemistry of the Lewisite agent inside.

“We keep expanding the capabilities and we keep expanding the agents,” he said later that day, touring both employees and reporters through the EDS, parked outside the Combustion Research Facility.

For instance, the National Research Council conducted a study that concluded that using three EDS units would have the highest probability of meeting schedule and be the most cost-effective way to dispose of 1,200 munitions at Pine Bluff Arsenal in Arkansas destined for demilitarization under the Chemical Weapons Convention. The Chemical Weapons Convention Treaty initially called for completion of demilitarization of chemical weapon stockpiles in 2007 (now extended to 2012). The Pine Bluff EDS operation is expected to begin later this year.

The initial need was sparked when construction of luxury homes in the Spring Valley development in Washington, D.C., near American University in 1992 unearthed four explosively configured mortars containing chemical agent, prompting evacuation of the neighborhood. The standard method of destroying these munitions is called “open burn, open detonation (OB/OD). It involves packing five times the amount of the explosive as the amount of agent around the munition and setting the explosive off to breech the shell and consume the agent in the ensuing fireball. Interestingly, Sandia/New Mexico did the calculations that derived the five times explosive factor for the Army. The noise and complications of blowing out windows and damaging houses from setting off 10 to 15 pounds of explosive made OB/OD unsuitable for Washington, D.C., John said. This caused the Army to seek some other technology. Ultimately many more munitions were unearthed and transported with special waivers out of the area. However, nearly a decade later, in 2003, EDS set up operations 100 yards behind Sibley Hospital in Spring Valley and neutralized 15 munitions containing mustard — six of them explosively configured.

Next explosives tests in Albuquerque

From July to September of 2004, 22 items were destroyed at Dugway Proving Ground in Utah that had been in storage since 1980. In October 2004 EDS destroyed a 75 mm mortar containing mustard found at a chicken ranch in Bridgeville, Del. Although EDS has never had a deployment in California there have been two close calls. A 4.2-inch mortar containing phosgene was found in 2003 near a housing development in Vista, north of Escondido, and later that year a 10-pound sarin bomblet was found at Edwards Air Force Base. The phosgene round was not explosively configured and could be transported to a destruction site and the bomblet was a trainer.

Explosives tests in Albuquerque will focus on preparations for the Pine Bluff arsenal operations. There are more than 700 recovered 4.2-inch mortars and over 400 German traktor rockets stored at Pine Bluff. The tests will demonstrate the capability to do six mortars or six traktor rockets at one time in the larger EDS. -- Nancy Garcia

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