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Nose on a chip provides low-cost chemical detection
OAK RIDGE, Tenn.,
April 28, 1998
Microsensors able to sniff out mercury, natural gas, carbon monoxide and other chemicals are just a nose away from becoming a reality at the Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL).
The "nose on a chip," which could be incorporated into household gas appliances, consists of an array of tiny sensors on one integrated circuit and electronics on another. By selectively coating the microcantilever arrays with appropriate chemicals, the chip can be customized to detect virtually any chemical or biological species. Developers say a single chip could detect thousands of chemicals.
"Major advantages of the nose on a chip include its low cost, the fact it provides instant results and can be customized for dozens of applications with little or no modification of geometry or electronics," said Chuck Britton, one of the developers and a member of ORNL's Instrumentation and Controls Division.
The microcantilever-based technology relies on the fact the tiny diving board-like platforms bend ever so slightly in the presence of chemicals. Selective coating makes the microcantilevers sensitive to different gases or chemicals. For example, a gold-coated microcantilever is useful for detecting mercury.
"Most existing sensors can detect only single species and have large volume and power requirements," Britton said "Our solution is to use miniature arrays of low power-consumption sensors and electronics on a single chip to simultaneously detect many different species."
Britton is also part of a team led by Steve Smith that is equipping the nose on a chip with a radio frequency transmitter that sends signals to receivers and instruments that allow operators to record and interpret readings. The same technology can also be applied to acoustics, vibration and for geosensing.
Another advantage of the nose on a chip is that it could be manufactured using the standard semiconductor process, making it inexpensive to produce. "Ultimately, this could be something you throw away after using it," said Britton, who added that it's conceivable that some day the chips could be coated using ink jet technology. That would lower the cost still more.
Britton and colleagues expect first applications of the device to be in consumer devices with environmental uses to come later. For example, the tiny nose on a chip could be incorporated into a gas stove or heater, providing the consumer with an added degree of safety and peace of mind.
"The applications are mind-boggling," Britton said. "The ongoing need for improvements in sensor technology cuts across every field of science, and ORNL is poised to continue its leadership in sensor technologies well into the next decade.
"This also illustrates DOE's concern for the environment and any potential impact its facilities may have on the environment. Sensors are a natural development for the DOE labs because you have to be able to detect something before you can clean it up."
Funding for the project was provided through the Laboratory Directed Research and Development program. Other researchers who have helped develop this technology are W.L Bryan, Bill Dress, Nance Ericson and Tim McIntyre of the Instrumentation and Controls Division, Gil Brown of the Chemical and Analytical Sciences Division and Bruce Warmack, Rick Oden and Thomas Thundat of the Life Sciences Division. Rob Jones and Jim Rochelle of the University of Tennessee are also part of the research team.
The collaboration among three ORNL divisions is a key to the success of the nose on a chip, according to Britton, who noted that the Instrumentation and Controls Division provided the expertise in integrated circuit design while the cantilever design and expertise came out of the Life Sciences Division. Brown and colleagues in the Chemical and Analytical Sciences Division have the knowledge of chemical coatings needed for the nose on a chip to work.
ORNL, one of DOE's multiprogram research facilities, is managed by Lockheed Martin Energy Research Corporation.