SBIR-STTR-Success: Microsensor Systems (ENMET, LLC)

Company Name:
Post Date:
February 12, 2020
Company Location:
62 Corporate Court
Bowling Green, KY 42103 0667
Company Website:

On March 20, 1995, five men boarded the Tokyo subway on separate lines, all headed to¬ward Tsukiji Station in Central Tokyo. It was Monday morning rush hour, a time when it would have been easy to blend into the bustling crowds at one of the world’s busiest commuter centers. The men carried bags with containers that would later be described as resembling lunch boxes or thermoses. Inside the con¬tainers was a colorless, odorless liquid that, when acti¬vated, would release a nerve gas called Sarin. At a coor¬dinated moment, not long after stationing themselves in their selected cars, the five men dropped their bags and exited the subway while the fumes from the liquid began to leak out. In a panic, sick passengers exited at various stations, carrying traces of the fumes with them. When bystanders tried to help the victims, they were also exposed. In all, 13 people died and more than 5,500 people were injured by the attack, which was later con¬nected to a doomsday cult called Aum Shinrikyo. The incident sparked renewed recognition that transporta¬tion infrastructures, especially where there are people in confined spaces, were particularly vulnerable to assault. And it also raised the question of how to handle the immediate aftermath of a chemical attack.
“The desire to monitor these locations for any trace releases was already a high priority,” said Hank Wohltjen, founder of the Bowling Green, Kentucky-based Microsensor Systems, Inc. “But even in the Tokyo subway incident, the people who were injured were immediately transported to the hospital, and, at that point, no one knew what they were deal¬ing with. Of course their clothes were contaminated, so lots of people associated with the incident were inad¬vertently exposed to low levels of these toxic chemicals.”
For four decades, Wohltjen has been exploring the question of how technology can monitor low-level traces of toxic chemicals. In the late 1970s, as a graduate student at Virginia Tech, he invented the Surface Acoustic Wave (SAW) micro¬sensor—a small chip of quartz with a microelectrode patterned onto the surface. He continued to develop the technology in the early 1980s as a researcher at the U.S. Naval Research Laboratory (NRL) in Washington D.C.
“The quartz device mechani¬cally resonates—like the string on a guitar—at very high frequencies,” Wohltjen says. “We apply extremely thin coatings of a polymer to the devices to make the vibra¬tions sensitive to chemical vapors. The coating acts as a ‘sponge’ for certain types of vapor. When the ‘sponge’ absorbs a particular vapor molecule, it gets heavier and causes the resonant frequency of the chip to decrease. Using this technique we can measure mass changes as small as a few picograms.”
In 1985, Wohltjen and some of his col¬leagues left the NRL and formed Micro¬sensor Systems, Inc. where they worked on the commercial development of SAW microsensors. They created a pocket-sized chemical warfare detection system using the technology, and they also began man¬ufacturing gas chromatographs for agen¬cies such as the Occupational Safety and Health Administration (OSHA) who used the chromatographs for industrial safety and hygiene purposes.
Then, in 1995, the Tokyo subway was attacked, and the desire for Microsensor Systems’ technology spiked. Through the Small Business Inno¬vation Research (SBIR) program, the U.S. Department of Defense (DoD) called upon Wohltjen’s company to create a detection system that would help protect U.S. troops and American citizens from similar chemical attacks and their consequences. The company con¬tracted with the Defense Advanced Research Projects Agency (DARPA) to develop a fully-automated, high-perfor¬mance SAW microsensor array for mobile air sampling and chemical monitoring. The first phase of the technology was completed in 1998 and combined the SAW technology with the miniature gas chromatographs and pattern detection software. It’s since been developed into a highly reliable, portable monitor that can be deployed anywhere in the world with the unique ability to detect low levels of chemical agents. The proj¬ect, as it was originally developed with DARPA, has been focused on intelligence gathering. Those programs are classified but, according to Wohltjen, the technol¬ogy has been used to help protect key facilities across the country, including major metropolitan mass transit systems.
“I can say that it was successfully deployed in the field and that it was in operation for several years monitoring for unexpected releases of toxic chemicals.” Wohltjen said. ”It has turned out to be a useful device in monitoring the presence of toxic materials in scenarios where it was necessary to protect people from potential exposure.”
The detection system measure emissions so that refineries can meet environ¬mental standards. Other commercial applications over¬lap with the goals of DoD and public health agencies. Monitors have been deployed at chemical weapons han¬dling depots to detect leaks. And hospitals can use the monitors in the event of a chemical weapons attack, if something like that were to happen in the U.S. Wohlt¬jen says the machine could be positioned in the emer-gency room where it would continuously analyze the air.
“As people came in, it would be able to detect toxic materials present and sound an alarm,” he said. “Then people would know to take more careful action in han¬dling these people who are coming in for triage.”
Wohltjen has come a long way from when he first founded Microsensor Systems, Inc. In the early days, he said, he was simply fueled by the belief that the detec¬tion technology he and his colleagues were developing had the potential to make a contribution to society. Now Wohltjen serves on several boards for tech start-ups and has worked as the principal investigator on more than $10 million of U.S. government funded R&D projects.
As for Microsensor Systems, Inc., it no longer exists by that name, having gone through sev¬eral acquisitions, most recently by ENMET, LLC, in Ann Arbor, Michigan (for whom Wohltjen serves as the CTO). Still, Wohltjen says, a lot of the people who started with the SBIR contract in 1996 continue to work at their same desks in the Bowling Green office. And the detection technology? It has relied on niche applications in which it continues to be highly relevant and effective. For example, Wohltjen’s company builds and maintains critical infrastructure detectors in Washington, D.C., New York, Boston, Los Angeles, and Chicago.
The SBIR program, through its support for growing businesses and nascent technologies, provides a launch¬pad for passionate innovators looking to develop their ideas. “You have some technical people who have an idea and want to commercialize it, but who know noth-ing about business or production—I’m speaking mainly about myself,” he said. “But we believed the technology had utility. There’s a relentless effort required to adapt technology as required to solve a specific prob¬lem for a specific customer. It’s something that takes many, many years. But that has been our passion. And we’ve stayed with it.”

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