ITHACA, N.Y. -- A train has derailed at the edge of a city, spreading toxic chemicals and fumes over a wide area. Before rescue and decontamination workers can enter the danger zone, they need more information: How widespread is the contamination? Where are the hotspots? Where and how are toxic gases moving?
A helicopter swoops over the area, releasing a flurry of tiny devices, each about the size of a dime. They contain sensors that sample the air for toxins and tiny radio transceivers that allow them to communicate with one another and report to a van at the fringe of the disaster area. Inside the van, a screen lights up showing where the contamination is and how it's spreading.
Such a system is the goal of a new research project at Cornell University that brings together molecular biologists, device physicists, telecommunications engineers, information and game theorists, and civil engineers to develop "self-configuring"sensor networks for disaster recovery. The project, involving researchers from Cornell and the Wadsworth Center of the New York State Department of Health, is funded by a $2.5 million, five-year Information Technology Research (ITR) grant from the National Science Foundation (NSF).
While initial research will focus on the detection of biohazards, the underlying principles can be applied to many other situations, including searches for earthquake victims (using audio and body-heat sensors) and monitoring of municipal water systems for leaks or contamination, according to Stephen Wicker, Cornell professor of electrical and computer engineering, who heads the research team.
In the aftermath of a disaster -- whether it be an earthquake, fire, building collapse or terrorist attack -- the most pressing need is for information, Wicker explains. Because often it would be dangerous or even impossible to collect data manually, the plan is to create an automated self-configuring remote sensor network. The idea grew out of studies of how such networks could be used on the battlefield, Wicker notes, but the NSF project focuses on civilian applications. "If they can save the lives of soldiers, you can use them to save the lives of civilians," he says.
The project will operate on several levels at once:
Sensors: Two types of biosensors are being developed that will detect a variety of agents, including toxins and bacteria, using biological material incorporated into silicon microcircuits. One type uses a membrane topped with binding sites like those on the surface of a living cell, layered onto a silicon microcircuit. When a molecule, such as a neurotoxin, binds to the surface ----just as it would when attacking a living target-- a protein channel is opened allowing ions to flow through the membrane, creating an electrical signal detected by the underlying circuit. The other sensor under development contains antibodies placed between tiny electric contacts. When an agent such as a virus, bacteria or spore binds to the antibody, the current flowing between the contacts is altered.
Communication: To keep size and power requirements small, the devices will communicate using very-low-power radio signals, allowing each device to reach only a few others in its immediate neighborhood. Rather than using GPS (global positioning system) technology, which would add weight and power requirements, the sensors will use the strength and direction of radio signals from their neighbors to map their locations. To report in, signals will be relayed from one device to another until they reach a human operator at the edge of the territory. In theory, the "reachout point" could be a van, a low-flying aircraft or even a satellite.
Self-configuration: The engineers will draw on game theory -- which deals with how a group of individuals interacts and competes for resources -- to program the devices to work together. The devices will decide, for example, the order and direction in which messages should be relayed, avoiding redundant signals. If the coverage mapping shows that some areas are not covered, the network will be able to call for the deployment of additional sensors.
Applications: The researchers will draw on case histories of earthquake effects, accidents in crowded urban environments and the aftermath of the World Trade Center attack to develop prototype applications, which in turn will determine the design of the sensors and networks. This work will draw on a database developed by the Multidisciplinary Center for Earthquake Engineering Research at the University of Buffalo -- and on interviews with experienced rescue workers, including some who worked in the wreckage of the World Trade Center.
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oStephen Wicker: http://people.