By Candace Stuart
Small Times Senior Writer
Environmental researchers are taking existing small tech tools and refitting them to take the pulse of the oceans, the sky and the earth. Eventually they hope to use microsystems to clean up spills and even serve as and chip-size factories to minimize, and possibly even prevent, disasters.
MEMS and microsystems are bit players in Earth Day celebrations going on this weekend. But that should change in the next few years.
For decades, environmental scientists have used high-tech devices to analyze air, water and soil quality and measure temperature, pressure and humidity in specific places. But the equipment was too cumbersome and expensive to investigate a vast expanse of ocean or the atmosphere. They needed something they could chuck from airplanes or boats in large quantities over wide areas that could relay data quickly and not deface the ecosystem they were striving to protect.
“It has to be cheap enough that we can use it,” said David Carlson, an oceanographer and director of the Atmospheric Technology Division at the National Center for Atmospheric Research in Boulder.
The low cost of commercial MEMS sensors caught his eye as he was designing a program to track hurricanes. Independently, University of South Florida engineer David Fries realized he could create a test for toxins in the waters off Tampa using MEMS components. In Albuquerque, chemist Al Sylwester recognized that a microsensor he developed at Sandia National Laboratories to sniff out deadly sarin nerve gas could be adapted to register health-threatening pollutants.
“There is an abundance of wonderful MEMS devices,” Fries said. They have the advantages of being small — many measure in microns — light, fast, reliable, inexpensive and disposable. They’re even green, requiring little material to make and little energy to power.
With no tinkering, they can be used for environmental purposes — but only in an ideal world. And Mother Nature’s world is harsh, with fierce winds or waves, frigid or torrid temperatures, and habitats like corrosive oceans.
“The question is, how do you take a MEMS device and put it in a real world situation, like a sensor system that has to sit on ice in Antarctica?” Carlson said. “We have to repackage them so they work in the real world.”
Carlson’s division refitted a sensor from a Finnish company and incorporated it and other components into a dropsonde, a tube attached to a parachute that is dropped from jets near and into hurricanes to measure temperature, barometric pressure and other phenomena. The findings are beamed to satellites and back to control stations for tracking and forecasting hurricanes. One test can require 20 to 30 dropsondes — sometimes as many as 50 — each at $550 apiece.
“They have an enormous impact on forecasting,” Carlson said. Using data from the dropsondes, researchers have been able to test computer models to ascertain which best predict the path and strength of hurricanes. With a good predictive model in place, scientist then can enter real-time data from a hurricane developing over an ocean to issue accurate warnings.
Over the next five years, Carlson plans to take microsensors used to measure car exhaust and adapt them with other microsystems to monitor conditions in remote places like icecaps, as well as conduct widespread atmospheric studies. Among the benefits will be the ability to track and predict the path of plumes from accidental or deliberate chemical and biochemical releases.
Fries customizes MEMS made by Agilent Technologies to produce sensors that recognize and measure the concentration of a toxin that causes red tide. Red tides can sicken people, kill fish, contaminate shellfish and play havoc on coastal economies. Gymnodinium breve, the tiny plant that releases the toxin, is itself harmless.
Fries and colleagues at the USF’s Center of Ocean Technology are designing three prototypes, each progressively more accurate and sensitive. Sensitivity is especially important in ocean testing, where the sample is small relative to the body of water.
The first microsystem combines pumps, capillaries and sensors to detect red tide toxin. The second adds “gene chips” and spectrometry components. The gene chips contain toxin antibodies that undergo an electrochemical reaction in the presence of the toxin. The reaction emits light that the spectrometry devices detect and analyze; the more concentrated the toxin, the more intense the light. In the third, Fries adds an even more sensitive fluorescent marker, which will reveal the most minute amounts of toxin.
He plans to adapt WIMS — wireless integrated microsystems — to send signals back acoustically through water to provide nearly instantaneous reports. He expects to have the first prototype completed this year. Once refined, the platform could be adapted to detect a variety of water contaminants.
The ocean will put any microsystem to the test, Fries concedes. “The coastal environment is salt water; it’s corrosive, vibrating … organisms grow on it. We’ll wrestle with some of these issues and then it will be easy to design for fresh water.”
A manager at Sandia, Sylwester has been overseeing the development of a hand-held chemical analyzer used by the military that can detect trace amounts of life-threatening biological and chemicals agents and alert soldiers of the danger. It is capable of separating complex chemical stews into their individual ingredients and identifying what, if any, are hazardous. His goal is make the system reliably detect as little as one part per billion, with a response time of mere seconds.
Sylwester recognized that this technology could work well along other battlefronts — environmental ones. His technology now includes liquid and gas separation techniques and sensors — “labs-on-a-chip” — that can be assembled onto a circuit board for specific applications like testing for PCBs, or polychlorinated biphenyls. PCBs, industrial chemicals once found in everything from transformers to adhesives, are now considered a likely carcinogen. Quick detection of leaks can prevent needless exposure to people and the environment.
“The advantages are it’s small, fast, reliable and low costing,” Sylwester said.
He predicts his brick-size chemistry labs will be used in the field for pollution detection and monitoring in three years. He expects to shrink the system even more, to put an entire integrated system on a dime-size chip, within five years.
Environmental researchers may find more ready-made MEMS in their toolbox as industrial suppliers begin to incorporate microsystems into their products. AIR-WORLD Environmental, Inc., a North Miami Beach-based company that provides emissions monitoring devices for manufacturing giants like General Electric and Pratt &Whitney, has reduced its $250,000 10-by-10-by-15-foot continuous emissions monitors to $80,000 27-by-30-by-12-inch boxes. Florida International University in Miami will use an AIR-WORLD monitor in its combustion laboratory, where researchers are making fuel sources cleaner and more efficient.
In the future, microsystems may one day be called on to clean up chemical spills. The Pacific Northwest National Laboratory’s Micro Chemical and Thermal Systems (MicroCATS) division in Richland, Wash., is developing microsensors and microseparation devices for environmental restoration. The microsensors will detect leaks from underground storage tanks and identify any contaminants leaching into the soil or groundwater. Microseparation devices will be implanted in tanks to filter out contaminants that can then be removed, or placed in contaminated groundwater to isolate the pollutants for removal.
PNNL also foresees the day when microsystems eliminate the need to transport or store the toxic chemicals manufacturers need. Instead, diminutive factories will produce only the needed amount of a chemical on site.
Today small tech has a modest role in our ability to protect the environment, but that may change, Carlson said. “There are a lot of good ideas out there, but almost nothing in place,” he said. “But a few of us are on the fringe. We’re looking for (MEMS devices) we can bend a bit to fit our needs.”