April 9, 2012
APL-Built Chamber Puts Biosensors Through Real-World Tests
In early March, the head of the U.S. Central Command warned a Senate Armed Services subcommittee that Syria’s regime had stockpiled a “substantial amount” of chemical and biological weapons—yet another example of why protecting U.S. forces and domestic interests from these types of threats remains critical.
The good news? Our nation’s defenses are keeping pace, with the introduction of intricate sensors designed to detect biological agents. APL’s work in this area reached a milestone in January with the completion of the Dynamic Concentration Aerosol Generator (DyCAG), which bolsters the nation’s ability to test sensors and equipment used to detect biological threats.
“The battlefield conditions our warfighters face vary greatly—some are in the desert, others on mountaintops and others on ships at sea,” says the Asymmetric Operations Department’s (AOD’s) Chris Carter, a program manager in the Homeland Protection Business Area. “Sensors must be ready to detect threats in any environment and under any conditions to provide the best protection possible, and DyCAG allows us to do that.”
Working with the Joint Program Executive Office for Chemical and Biological Defense, APL scientists and engineers developed the state-of-the-art test bed, installed at Dugway Proving Ground in Utah, earlier this year. DyCAG provides the capability to rapidly challenge multiple sensors in different tests.
“We’ve worked very closely with the system’s sponsor and end users to make sure the system meets their immediate testing needs,” says AOD’s Dan Simon, project manager for the Dugway DyCAG. “But we also designed it with enough flexibility to facilitate a wide variety of bio-aerosol testing scenarios down the road.”
Biodetection sensors are evaluated using methods that simulate a plausible biological attack in real environments. APL scientists and engineers develop challenging conditions in test environments by including background (or “ambient”) aerosols found in the atmosphere—such as salt spray from the ocean, dust from desert sands, tree pollen, and volcanic ash.
“In designing DyCAG, we used real-world data to devise ways for it to mimic real-world conditions,” says Shanna Ratnesar, a project manager in AOD’s Aerosol Sciences Group.
This new and improved version of DyCAG—the initial version is at APL—delivers a supply of aerosolized particles and is able to change their concentrations over time. It can also generate one aerosol, isolate it from the rest of the system, and challenge multiple sensors with the same aerosol mixture at once. This allows each system to experience the same concentrations and temporal changes, and exact test conditions are automatically documented—increasing the challenge’s ability to be reproduced.
“The ability to duplicate challenges is key,” says Ratnesar. “We can evaluate the performance of biological sensor systems more effectively when we are able to recreate these realistic environmental test conditions, time and time again.”
The DyCAG tests bio-aerosol sensors alone and side by side under a wide array of conditions, including tests with simulants of chemical weapons. To mimic these, chemically similar compounds with much lower toxicity are used. To substitute for biological weapons, dead, nonpathogenic, or low-pathogenic organisms are used. This provides the needed understanding of sensor performance while safeguarding the testing team.
“APL is improving the technology available to our country to detect and defeat biological attacks,” says Carter. “And DyCAG is an example of an innovative way that APL is working with the government to fulfill our mission of ensuring the security of the nation.”