UA Research: Building a Better Bomb Sniffer

What do identifying explosives in a piece of luggage, determining the origin of a bullet and unlocking the age of rocks have in common?

They all employ a technology called mass spectrometry, used to detect minute traces of a substance and determining its chemical composition.

In the first major improvement in mass spectrometry detection technology in more than two decades, a research group led by M. Bonner Denton and Roger Sperline in the University of Arizona's department of chemistry and biochemistry has developed a way to dramatically improve the detection capabilities of mass spectrometers, which in turn could advance monitoring for nuclear activity, environmental damage, forensic testing and more.

The technology improves the performance of a widely used scientific instrument that enables quick and efficient analysis of research samples and was developed with collaborators at iMAGERLABS, Pacific Northwest National Laboratory, Indiana University and Spectro Analytical Instruments.

R&D Magazine honored the achievement, called Array Detection Technology for Mass Spectrometry, with its 2011 R&D 100 Award, which is given annually to recognize the 100 most technologically significant new products introduced in the past year.

Similar to the way an optical spectrometer splits light into its different wavelengths, a mass spectrometer splits an unknown substance into its chemical components and mass fragments. By precisely measuring the fragments' atomic masses, which are specific to each chemical element, the mass spectrometer gives its operator clues as to the composition of the sample.

“Whether we want to analyze a molecule or an atom, mass spectrometry can give us insight into the composition,” Denton explained. “The first step is to give the molecules, molecular fragments or atoms an electric charge. Once we give them an electrical charge, we can accelerate them with an electrical field.”

As the particles fly along their trajectories, the lighter particles will be deflected more than the heavier particles by the magnetic force, causing them to fan out and hit the detector in different places along a so-called focal plane. The place a particle hits depends on its mass and thus gives clues to its identity.

“Traditionally in dispersive mass spectrometry, one observed one mass for a period of time, before scanning over to observe the next mass,” Denton said. “Our new technology observes the entire mass range for the same period of time conventionally spent at each mass, and we obtain the entire spectrum with high sensitivity in one single observation period. This has never been possible before.”

Denton said that if one wanted to scan isotope ratios – atoms of the same element that have different masses – approximately 10,000 resolution channels would be required for a complete elemental analysis, and the measurement would take a considerable amount of time.

“With our technology, it takes approximately one to three minutes because all masses are observed simultaneously.”

The biggest hurdle facing the team on the track to a faster and more sensitive detector was to find a way to make the individual detection units small enough to fit hundreds of them onto an extremely small area.

“In the first versions, we had to make a wire bond for each pixel, so we were forced to utilize more and more wire bonds that were narrower and narrower, and soon we reached a point where we could not make individual pixels any smaller,” Denton said.

“So I thought, why don't we make a linear device with a large number of tiny, finely spaced metal fingers on the same substrate as the amplifiers using the same integrated circuit fabrication technology? That way, we can forget about the wire bonding, which limits how small we can go with the technology.”

So small are the pixels or sensing elements in the latest version of the new detector array that approximately six of its detection units would fit across the edge of a sheet of paper.

The first company to commercialize the technology is SPECTRO Analytical Instruments GmbH based in Germany. According to Denton, the Spectro instrument contains 9,600 pixels grouped in pairs of low sensitivity and high sensitivity, which together are able to simultaneously monitor all elemental masses across the periodic table of elements, from hydrogen all the way to uranium.

Potential applications are many, Denton said, from handheld instruments sniffing out explosives at ports of entry, determining the age of rocks, tracing the source of agricultural products based on the soil they were grown in, to crime scene investigations. Mass spectrometry can reveal, for example, where the lead was mined that later was manufactured into a bullet.

In a different line of research, Denton said his team is already using similar technology to develop a device capable of detecting traces of explosives in the air hundreds of feet away. Such a device would make it much easier for military and civilian personnel to detect and disarm improvised explosive bombs before they could unleash their deadly force.

According to R&D Magazine, the R&D 100 Awards have long been a benchmark of excellence for industry sectors as diverse as telecommunications, high-energy physics, software, manufacturing and biotechnology.

For industry leaders, government labs and academic institutions, the awards can be vital for gauging their efforts at commercialization of emerging technologies. In winning an R&D 100 Award, developers often find the push their product needs to find success in the marketplace.

Since 1963, the R&D 100 Awards have identified revolutionary technologies newly introduced to the market. Many of these have become household names, including ATMs (1973), the fax machine (1975), the liquid crystal display (1980), the Nicoderm anti-smoking patch (1992), Taxol anticancer drug (1993) and high-definition TV (1998).

The Array Detection Technology for Mass Spectrometry is the result of long-standing collaborations among several academic and industry partners and funding provided by the Department of Energy, Denton said.

“Our group, together with iMAGERLABS, Inc. developed the original technology,” he said. “We sent our prototypes to collaborators at the Pacific Northwest Northern Laboratory and Indiana University, where they were tested for their capabilities. The product was then adapted into a commercial application by SPECTRO Analytical Instruments. This award really recognizes all the parties involved.”

LINK:
2011 R&D 100 Awards:
http://www.rdmag.com/News/2011/06/R-D-100-2011-Winners-Announced .
CONTACTS:
M. Bonner Denton
Department of Chemistry and Biochemistry
The University of Arizona
520-621-8246
Daniel Stolte
University Communications
The University of Arizona
520-626-4402
stolte@email.arizona.edu