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Emerald Group Publishing Limited
Copyright © 2009, Emerald Group Publishing Limited
Sensor applications in homeland security: Where are we? Where do we go from here?
Article Type: Viewpoint From: Sensor Review, Volume 29, Issue 1
Keywords: Sensors, State security, Radioactive materials, Terrorism, Contamination
The World Trade Center and Pentagon attacks and the Madrid and London train bombings have underscored the urgent need for continued R&D in the area of homeland defense sensors and systems that monitor and detect threats from gas, chemical, radioactive, and biological agents. Sensors allow us to monitor and detect abnormalities in the surrounding environment without human presence. Needed is sensor technology that can provide real-time detection to reduce the impact of threats; be deployed remotely so that direct contact with toxic agents can be avoided; and cover a large area – to increase detection efficiency.
So where are we?
Seaport safety. Millions of cargo containers arrive each day; each container may potentially contain harmful materials. Inspecting cargo is a tremendously challenging task? A system called SeaAway, designed by RAND Corporation, is under construction in the State of Florida. The concept is to move the inspection process several miles away from the seaport. A parallel chute-like structure is anchored to the sea floor, forming a massive sensory system that can scan an entire ship from top to bottom for presence of chemical, biological, or radioactive materials.
Border patrol. Two basic approaches to border monitoring have been reported. One approach involves use of imaging sensors (optical and infrared) and networks to provide real-time monitoring of vehicle and human activity across a section of a border – for example, the OmniSense battery powered sense module developed by McQ. The second approach is to use unmanned aerial vehicles to conduct aerial surveillance.
Airport/border point of entry. Biometric sensors have been developed to inspect individual travelers’ irises, faces, and voices. Puffing sensory machines have also been employed to check for the presence of explosive particles on skin or clothing. Low-energy γ ray sensory systems have been developed to see into lead-lined boxes and the interiors of trucks and cargo containers without prying them open.
Through the wall surveillance. Through the wall surveillance (TWS) technologies utilize active radars operating in the UHF, L, S (ultra wideband), X, and Ku Bands. Currently, the US Air Force Research Laboratory and Department of Justice are evaluating TWS technology. The data displayed by these systems can indicate either range (1D) or range and azimuth (2D) of moving individuals.
Water supply. Pathogenic microorganisms are generally small and easily transported in water; therefore, chlorine is routinely added to treat water before its release into distribution systems. In addition, the US Department of Defense is looking into employing bluegill fish as live sensors to monitor water quality, since even slight impurities can effect significant changes in their vital signs.
Public places. BioWatch, a network of miniature toxin detectors, has been deployed in 30 American cities to collect toxins in air samples using air filters. The samples are then sent out for inspection.
Where do we go from here?
Learn from insects and animals. Observe and learn how they detect and interact with bio and chemical agents and develop new types of live sensors. For example, when bees detect a target odor, they extend their proboscises. A camera records the positive response, and a computer alerts an operator.
Create a networked early warning system integrating live and artificial sensors, a controller, and warning devices. For example, you could have transparent flower box with holes with bees inside. These can be deployed around the city to beautify the streets. A camera can be used to monitor the bees’ behavior. A warning device could be energized to warn passers-by if things do not go right; and at the same time, a central command station can be notified about the location of the alarm so that rescue and decontamination personnel can be notified.
Integrate live sensors with nanosensors. Nanoscale sensors are generally designed to form a weak chemical bond to the substance of whatever is to be sensed, and then to change their properties in response. This could involve a color change or a change in conductivity, fluorescence, or weight. So, for example, you could paint a very thin layer of nanosensors on cockroaches’ shells and then direct them to screen a complex building by placing bait on the other side of the structure.
Coat building walls, clothing, and packaging materials with nanomaterials that can react to the presence of biological agents. These nanomaterials would bind to the target DNA of the given biological agent and can thus be used to detect substances such as anthrax.
Integrate miniature cameras with animals and insects such as pigeons and butterflies for border monitoring or building surveying.
In summary, much progress has been made, but there is much territory yet to explore. The ideas presented here represent a challenging R&D agenda, but protecting the safety of our public transportation, food supplies, water, utilities, public places, borders, ports and entry points is an essential and critical issue.
Sheng-Jen (“Tony”) Sheng-Jen “Tony” Hsieh Dwight Look College of Engineering, Texas A&M University, College Station, Texas, USA