Gathering Data From Earth and Sky

To assess environmental impacts, researchers first have to collect data and make sense of it.

At Purdue's Laboratory for Applications of Remote Sensing (LARS), faculty from Agricultural and Biological Engineering, Civil Engineering, and Electrical and Computer Engineering, as well as the colleges of Science and Agriculture, exploit sensing capabilities including the new Purdue Terrestrial Observatory (PTO). This observatory, a real-time, on-the-ground receiving station, takes in data 24 hours a day from NASA’s GOES meteorological satellite and other satellites. The data, along with access to LARS archival data, aids both change detection and responsiveness to biogenic and anthropogenic disasters.

“The linkages between LARS and the Purdue Terrestrial Observatory are strong and vibrant,” says Gilbert Rochon, associate vice president of Information Technology at Purdue and the PTO’s collaborative research director. “LARS-affiliated faculty members now have enhanced access to PTO data and our archival satellite data as well. Both are needed for change detection and trend analysis.” Purdue engineering research into subjects including watershed sustainability, water quality, and the integrity of the nation’s power grid is benefiting from the collaboration.

Another collaboration, through the Physiological Sensing Facility at Discovery Park’s Bindley Bioscience Center, involves agricultural and biological engineering (ABE)professor Marshall Porterfield and Jenna Rickus (of ABE and the Weldon School of Biomedical Engineering) on environmental sensors. The researchers are developing a nanoflow microlaboratory bioprobe for a broad new class of wireless sensor devices that can be adapted for real-time analysis and diagnostics.

The technology involves MEMS (microelectromechanical systems)-biosensor-based porous sensing materials for sampling and analyzing liquid media. Based on electronic or optical signals, the sensors can be designed to detect basic environmental contaminants like ammonia and nitrate—common problems in commercial agriculture. Sensors can also detect important environmental toxins like lead, arsenate, and cadmium, industrial byproducts that are known hazards to human health.

“The promise of this work,” says Porterfield, “is that applying these new technologies will drive rapid progress in environmental and biological sciences.” The researchers have already initiated collaborations with participants in Purdue’s Center for the Environment. Marisol Sepulvida, a civil engineering and forestry and natural resources professor, is interested in evaluating the sublethal effects of contaminants and other environmental stressors on the reproductive physiology of fish and wildlife.

Porterfield and Rickus also are developing wireless devices for determining water quality in municipal water-supply systems, in collaboration with Kathy Banks, a civil engineering professor and interim head of the school.

In Civil Engineering, assistant professor Joe Sinfield is developing a real-time, in-situ sensing system that can monitor levels of compounds such as nitrogen and phosphorus in farmland effluent, animal wastes, and cultivated soils by using optical spectroscopic techniques.

“Traditionally,” he says, “to do this type of assessment, we’d collect field samples at a limited number of dispersed locations and perform in-laboratory analysis, using a range of wet-chemistry and bench-top spectroscopic techniques. That approach, however, is expensive, time-consuming, and limited in value due to the inherent spatial variability of the quantities under investigation and the limited amount of information gathered from the few samples that can be cost-effectively analyzed.”

Sinfield’s work, utilizing recent advances in diode laser technology and fiber optics, promises real-time capabilities on site, providing greater spatial resolution and convenience at as little as one-tenth the cost.

The approach relies on Raman spectroscopy to reveal the molecular signature of compounds that are present in a sample. “It’s a disruptive innovation,” Sinfield says. “For industrial contexts, we’re developing solutions that trade off quality in terms of spectral performance for convenience and much lower cost”—in other words, solutions that are simply good enough.

Sinfield foresees, in a few years’ time, a commercialized, miniaturized device in the form of a box with an optical fiber coming out of it. “You’d be able to put it in a well or in a waste stream on a farm,” he says. And the ultimate scenario? He imagines the device attached to a tractor, “interrogating” the ground in real time, analyzing which compounds are present, and feeding the information on the fly to the farmer at the wheel.