Special Report - Sensor fish make a splash
Sensor systems are like scientific extensions of a human's five senses. While they don't actually see, hear, smell, taste or touch, their job is to collect data and use it to help detect, identify and measure different substances and assess different situations. Pacific Northwest National Laboratory has developed sensor, measurement and electronic technologies for research and for a variety of industrial applications. The stories on the next few pages highlight some of these interesting projects to give you a sense of Pacific Northwest's broad capabilities and expertise in this area.
They may not swim, but the sensor-packed synthetic salmon that are making their way through the turbines at Bonneville Dam and other hydroelectric projects in the Columbia River are doing something that real fish cannot. The six-inch, rubber-coated sensor fish developed at Pacific Northwest National Laboratory are measuring the conditions that real fish encounter as they pass through turbines of hydroelectric dams on the way to the ocean—valuable information that could lead to more fish-friendly turbines in the future.
"The vast majority of juvenile salmon and steelhead passing through the turbines survive without injury, even so, the rate at which injuries occur is considered unacceptable," said Tom Carlson of Pacific Northwest's ecology group who leads the project. "The information that we're collecting could help engineers design hydropower turbines that are safer for fish."
As the sensor fish pass through the turbines, their sensors gather specific information such as changes in pressure and acceleration. Little balloons attached to the fish inflate and bring them to the surface at the end of their swirling trip. An attached micro-radio transmitter helps people in boats locate and recover the data-collecting devices in the dam tailrace, downstream of the turbine exit. The sensor fish then are attached to a computer and the recorded data is downloaded for analysis.
"This technology will provide scientists with the first opportunity to measure actual environmental conditions in operating hydropower turbines—at measurement scales directly applicable to juvenile fish," Carlson said. "We're learning more about what leads to direct injuries to fish as well as to indirect injuries such as temporary disorientation or stunning that make them more susceptible to predators downstream."
A school of nine sensor fish went through turbines at Bonneville Dam near Portland, Ore., a total of about 90 times in December 1999 and January 2000. The study was designed to compare the passage conditions of two turbines—one installed when the dam was built in the 1930s and one equipped with a minimum gap runner, a new turbine runner design that is expected to make turbines more efficient and less harmful to fish. Researchers plan to deliver final data from these tests in fall 2000.
Another field study in June collected data on the conditions present in high-flow outfalls or bypass systems designed to pass fish around the dams rather than through the turbines. That study continues in October.
"After developing our first prototype, we made modifications to the sensor package that measures changes in the motion of the sensor fish," said Dennis Dauble, a technical resource manager for the Environmental Technology Division. He explained that Pacific Northwest has the capability and expertise to redesign the sensor fish for a variety of research applications.
The U.S. Army Corps of Engineers Portland and Walla Walla districts, the Bonneville Power Administration and the Department of Energy's Advanced Hydropower Turbine System (AHTS) Program are supporting the sensor fish's continued development, deployment and data analysis.
"For a few years, I had been thinking that I'd really like to have a dummy fish to reduce the need for testing on live fish," said Peggy Brookshier, technical program manager for AHTS.
Brookshier said that she expects her organization to continue funding upgrades and enhancements. "Our program is nationwide so there are a lot of potential benefits. For the dissolved oxygen problems in the Southeast, where there's not enough oxygen in the water—or for industry—the sensor fish might be modified to help take measurements and see patterns."
Researchers at Pacific Northwest National Laboratory may have the right recipe to help solve process control problems in industry.
They've consolidated ultrasonic sensor capabilities from throughout Pacific Northwest's four research divisions into a single laboratory specifically designed to address problems relating to process control for food processing, chemical, forest products and other industries.
The primary focus of the Food Science and Process Measurement Laboratory is food processing, an industry that employs nearly 40,000 people and earns more than $7.7 billion in annual revenues in Washington state alone. "We have an extensive portfolio of ultrasonic sensor technologies originally developed for a variety of applications that can be used to increase efficiencies, quality and safety in food processing," said Wally Weimer, a manager of the Process and Measurement Technology Product Line.
According to Dennis Stiles, manager of Pacific Northwest's Agriculture & Food Processing Technology Initiative, the food processing industry needs new technologies to measure and precisely control product quality. "U.S. food processors sell into a very competitive marketplace and must continually provide products that meet consumer requirements," he said. "The ability to make real-time measurements of product quality and use those measurements to optimize process parameters to ensure consistent quality—while maintaining peak process line productivity—affords a significant competitive advantage."
The laboratory is equipped with an industrial-sized mixer, oven, steam kettle and other standard food processing equipment, all of which have been instrumented with ultrasonic sensors that can determine how long it takes for ingredients to become fully mixed or for vegetables to be properly blanched. "Ensuring the ideal mixture of various product ingredients directly affects product quality, shortens production time and reduces unnecessary energy expenses, regardless of what is being produced—from cookie dough to shampoo," said Dick Pappas, project manager.
In addition to focusing on food-related activities, the new laboratory also serves other industrial clients. For example, it has an instrumented, 30-foot-long process flow loop that can be used to measure attributes of almost any material that can be pumped through it, including mixtures and slurries that are common in the chemical, forest products and consumer products industries.
Pacific Northwest already is working with several large food processing and consumer product corporations at this new laboratory and continues to pursue potential clients who would like access to the specialized facility.
A cracked bolt may not faze Tim "The Tool Man" Taylor as he does home improvements, but it can debilitate an industrial or nuclear plant if undetected. A new inspection device developed at the U.S. Department of Energy's Pacific Northwest National Laboratory detects cracks in bolts more easily and less expensively than alternatives.
Pacific Northwest's device relies on ultrasonic electronics to retrieve more accurate readings by limiting background noise. Also, the device allows fasteners to be inspected while in place, thereby reducing inspection time and allowing periodic monitoring. Inspectors have a greater opportunity to interpret the data and make repair decisions with a complementary computer tool that gives a visual representation of the fastener and any fractures or degradation.
The words, "I better stop to catch my breath," might soon mean something different to industrial workers who think they may have been exposed to hazardous chemicals. A new real-time breath-analyzing device can determine the kinds of chemicals and levels of exposure more quickly and accurately than conventional monitoring and detection methods.
"Rather than sending blood or urine samples to the lab and waiting days or even weeks for results, the Exposure-to-Risk Monitor can immediately analyze breath samples onsite and determine if someone has been exposed to dangerous chemicals," said Karla Thrall, a staff scientist at Pacific Northwest National Laboratory. Thrall and her colleagues at Pacific Northwest in Richland, Wash., and at Battelle's headquarters in Columbus, Ohio, developed the Exposure-to-Risk Monitor, which is also know as E2RM. Battelle operates Pacific Northwest for the U.S. Department of Energy.
In addition to timeliness, the E2RM system overcomes other limitations of conventional technologies. Stationary devices in the workplace or worn by workers measure the concentration of substances in the air—not how much of a compound may have entered the body. The E2RM, on the other hand, relates levels of exposure with the dose that a person actually received internally. It also accounts for different routes of exposure such as inhalation, ingestion or through the skin.
"A more accurate way to identify the chemical or chemicals, determine the levels of exposure and how much of the chemical remains in the body provides a much clearer picture of the resulting health risk," Thrall said.
At the heart of the monitoring system is a commercial mass spectrometer—a scientific instrument used to identify chemicals by transferring them into ions and separating the ions based on size and charge—and a breath inlet device that collects breath samples.
The E2RM system can scan for volatile organic chemicals such as benzene, carbon tetrachloride, trichlorethylene and others in 1.5 seconds, testing for several in the breath samples simultaneously.
If people believe they have been exposed to a chemical they would breathe into the system's mouthpiece for one to two minutes while the mass spectrometer analyzes their breath samples for chemical concentrations as low as single parts per billion. Once the chemical or chemicals and concentration are known, a physiologically based pharmacokinetic mathematical model built into the system can evaluate internal dose. It describes how a compound gets into the body, where it goes within the body, how it breaks down and how it leaves the body.
Physiologically based models take into consideration a person's height, weight and body fat content, making a better determination of how chemicals will be distributed in specific organs in individuals.
"Some day, this monitoring system could be ideal for emergency response situations as we work to make it more portable." Thrall said. "It could let people know immediately if they should seek treatment. It also could determine quickly if an area needs to be controlled for environmental risks and to prevent further exposure to workers or the public."
Lab and field tests have been successful and researchers are seeking partners to commercialize the technology. In addition to testing breath for chemical exposure, researchers use exhaled breath analysis to conduct basic studies on chemical mixture interactions and are exploring its use in disease diagnosis.
The science of spectroscopy boils down to the art of making rainbows and interpreting them to identify chemicals.
While spectrometers are typically very delicate devices that require precise adjustments, researchers at Pacific Northwest National Laboratory have developed a simple, rugged spectrometer that could be used in the field to detect nuclear materials, pollutants, byproducts of methamphetamine production and more.
Mirrors are a key component of Fourier spectrometers. Based on the way that light enters the device and bounces off the mirrors, the spectrometer creates a jumbled string of data called an interferogram. Using computational mathematics, scientists interpret the interferogram, which results in a rainbow where different colors represent the presence of different chemicals.
Unlike conventional Fourier spectrometers with moving mirrors, the one developed at Pacific Northwest has no moving parts. It is less expensive, easier to operate and requires less data analysis—without sacrificing the needed level of preciseness. "This simplicity and durability makes it attractive as a component for systems used in the field," said Mary Bliss in the radiological and chemical sciences group.
Researchers at Pacific Northwest began pursuing this idea in 1997 as a more convenient and cost-effective way to read the fiber optic strain gauges that are built into bridges, dams and roads to determine structural integrity and risk of failure. Norm Anheier, who built the first prototype of Pacific Northwest's spectrometer, estimates that its cost would be less than one tenth of the price of conventional instruments used to read these optical sensors today.
Development efforts have since moved into other kinds of optical sensors, including those that detect chemicals. Researchers at Pacific Northwest are investigating the use of custom silicone polymers to coat the fibers or the mirror itself. Because different polymers attract and concentrate different types of chemicals on the detector, special coatings could allow a system to be tailored to detect certain things. For example, a sensor could be built specifically to detect carbon tetrachloride in soil or to monitor levels of certain chemicals in smokestack emissions.
"Everyone who might be interested in this technology could have a different end use," said Dick Craig, of Pacific Northwest's sensors and measurement systems group. "This concept could be the enabling technology for an entire specialized system."
Pacific Northwest has a patent pending on this technology and is looking for a sponsor that is interested in developing it further for specific applications.
An extremely sensitive sensor technology designed for laboratory research shows promise for industrial applications as researchers at Pacific Northwest National Laboratory explore innovative uses of the technology as well as how to make it smaller, more portable and less expensive.
Research scientists Nancy Foster-Mills, Tom Autrey and Jim Amonette are experimenting with photoacoustic sensors that provide nondestructive, real-time chemical monitoring of complex mixtures, including those that are difficult to analyze using more conventional techniques.
"These sensors are 100 to 1,000 times more sensitive than conventional absorption spectroscopy technologies used to identify the presence and concentration of specific chemicals," said Foster-Mills, who helped build the Environmental Molecular Sciences Laboratory's capability in photoacoustic sensors and spectroscopy.
In research funded through the Environmental Management Science Program, scientists used a photoacoustic sensor to determine the concentration of chromate, a common pollutant on the U.S. Department of Energy's Hanford Site, in order to study how it is taken up by minerals in the soil.
"The technique that we're using is not only more sensitive, it's faster," Foster-Mills said. "It could provide analysis in seconds, where other technologies might take minutes or hours. Because it's nondestructive, these sensors also are practical for studies of ongoing processes."
Here's how a photoacoustical sensor works. The first step is to shine light of the appropriate wavelength on the sample, which excites the molecules in the mixture. As the molecules return to a relaxed state, they give off heat. The released heat energy, in turn, creates a pressure wave that travels through the sample. By detecting and measuring the pressure wave, researchers can determine how much of a chemical is in the sample.
Photoacoustic sensor technologies potentially could be used for routine analysis in industry most anywhere that nondestructive, in situ, real-time monitoring is needed and could be integrated into continuous monitoring devices.
"With their better detection limits, photoacoustic sensors could be valuable in quality assurance, industrial processing, safety, and environmental monitoring," Foster-Mills said.
Researchers are working to make the technology less expensive and more portable. One approach is to use alternative light sources and eliminate the need for lasers, which can be costly and bulky.
Pacific Northwest is seeking industrial partners, including those who may be interested in Cooperative Research and Development Agreements, to help develop photoacoustic sensor technology to meet their needs.