Smart Sensors

New environmental monitoring system based on integrated optic sensors will reduce costs and improve efficiency.

By Jane M. Sanders

A common piece of workplace advice — "work smart" — can be aptly applied to a revolutionary environmental monitoring and analysis system that promises to reduce the time and costs involved in analyzing contaminants.

This diagram illustrates the E-SMART environmental monitoring and analysis system developed by a team of researchers, including some from Georgia Tech. Click on graphic to see larger, 65k version.

A team of researchers that includes Georgia Institute of Technology engineers has developed the system — called E-SMART (Environmental Systems Management, Analysis and Reporting neTwork). Researchers predict it will dramatically improve the efficiency and effectiveness of environmental monitoring. The system — consisting of data management hardware and software and integrated optic chemical sensors — operates in real time and measures very small amounts of contaminants. In addition, researchers say it will reduce health and safety risks and help ensure environmental compliance.

"Right now the only way technicians have for field analysis is to go out and take samples, bring them back to the laboratory and perform wet chemistry tests," says Nile Hartman, a principal research engineer at the Georgia Tech Research Institute (GTRI). "It's expensive — about $200 a sample plus the technician's time. So instead we have developed a sensor that operates in situ (at the site of contamination) and continuously monitors the site. So you have huge savings in time and cost."

At the heart of the project are smart sensors that detect a variety of chemical contaminants, including heavy metals, solvents, and petroleum oil and lubricants. The integrated optic interferometric sensors were developed over the past decade and patented in 1997 by Hartman and the Georgia Tech Research Corporation.

The sensor was licensed commercially by the Atlanta-based Photonic Sensor Systems Inc., a recent graduate of Georgia Tech's Advanced Technology Development Center, a business incubator for high-tech companies. Photonic Sensor Systems is also a member of the Department of Defense (DOD) funded E-SMART research team, and GTRI is its subcontractor for the project. Other members of the E-SMART team are General Atomics, U.S. Air Force Armstrong Laboratory, Isco Inc. and Science & Engineering Analysis Corporation.

Laser-based technology originally developed for optical communications allows the multichannel microsensor fitted with the proper chemical coatings to detect multiple contaminants in soil, groundwater and air. The speed of light increases or decreases when passing through materials of differing optical properties, Hartman explains. Detection of contaminants becomes possible by measuring a contaminant's influence on the optical properties of the sensor. Then researchers observe the effects on these properties through changes in the transmitted laser light.

The sensors are integrated into the E-SMART team's standardized smart sensor networks that collect, manage and analyze the sensor data. The resulting analysis will allow environmental site managers to predict fate and transport of contaminants, perform remedial design, and gain regulatory and public approval of remedial approaches.

"This system will allow real-time assessments of what we're doing to the environment," Hartman says. "We can see if we're doing bad things to it or if we're making improvements through pollution abatement techniques and processes."

An E-SMART field test, expected to begin later this year, will probably be conducted at a U.S. Air Force base where cleaning agents used to degrease metal aircraft parts have seeped into soil and groundwater, Hartman says. Researchers will install sensors in monitoring wells, streams and in cone penetrometers, rods driven 200 to 300 feet into the ground. The sensors will be designed to detect benzene, toluene, ethyl benzene and xylene (BTEX compounds). With the contaminant type and concentration data collected by the sensors, E-SMART will map the contaminant plume at the site. Then site managers can take this easily interpreted analysis and take appropriate corrective action, if needed, Hartman says.

Field tests at other Department of Defense sites, and even perhaps at a Department of Energy site, will follow this one, Hartman says. With this step yet to complete, the sensor technology is still a year or two from availability on the national and international commercial markets, he added.

When it does become available, the E-SMART system and even the sensor as a stand-alone environmental monitor will have numerous applications in the private sector, Hartman says. Manufacturing facilities might use the sensor to simply monitor their output. Site monitoring personnel could determine their exposure to dangerous chemicals. And water plant managers could better monitor their process control to ensure properly cleaned drinking water.

"The big advantage of this sensor is that it operates in real time in situ. You get an output that is concentration dependent," says Hartman, a part owner of Photonic Sensor Systems.

"Speed is another advantage of these sensors. Compared to most sensors, these operate fairly fast: You get a response in seconds," Hartman says. "Also, the fact that these sensors work in water is a big advantage. There are not many sensors out there that can make that claim. One more advantage is the sensors' sensitivity. They can measure down in the parts per billion range."

In addition to environmental monitoring, the sensors are expected to have applications in food safety and medical testing, Hartman says. This fall, Hartman, GTRI research engineer Dr. Dan Campbell and Georgia Tech biology professor Dr. Paul Edmonds will supervise a field test of a biosensor intended to rapidly detect salmonella bacteria in meat in poultry processing plants.

For more information, you may contact Nile Hartman, Electro-Optics, Environment and Materials Laboratory, Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, GA 30332- 0825. (Telephone: 404/894-3503) (E-mail: nile.hartman@gtri.gatech.edu)

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Last updated: October 7, 1998