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NEW CHIP COMBINES ELECTRONICS WITH LIVING
SENSORS
By Sean Henahan, Access Excellence OAK RIDGE, Tenn. (April 28, 1997) A bioluminescent bioreporter integrated circuit, dubbed "Critters on a Chip," offers a innovative, and inexpensive, method for detection of pollutants, explosives and chemicals in soil and water. The half-living, half-silicon chip was developed at the Department of Energy's Oak Ridge National Laboratory (ORNL). The chip consists of living sensors -- such as bioluminescent bacteria -- placed on a standard integrated circuit, or chip. In the presence of targeted substances, including pollutants and explosives, the bacteria emit a visible blue-green light. "Because the integrated circuits are small, low-power, rugged and can be made wireless, they can be placed in areas other devices cannot," said ORNL's Mike Simpson, developer of the hybrid chip. "The bioreporters can be engineered to be very specific and sensitive to a particular substance." Simpson, a member of the lab's Instrumentation and Controls Division, expects the chip to cost less than $1 apiece to mass produce. Other potential uses for the chip, which can be designed to transmit a signal to a receiver that's connected to a computer, include in medical diagnostics and industrial process monitors. The critters chip is small -- 2 millimeter x 2 millimeter and about a half millimeter thick -- and can be produced using standard integrated circuit manufacturing processes. Simpson and Gary Sayler, who heads the University of Tennessee's Center for Environmental Biotechnology, recently produced a prototype using Pseudomonas fluorescens HK44, a genetically engineered microorganism that produces light as it breaks down hazardous waste. Sayler and Simpson exposed the prototype chip to naphthalene, a component of crude petroleum, and were able to clearly detect a signal, demonstrating that the critter chip was working. Because the chip is small, inexpensive and provides information quickly, monitoring of remediation at contaminated sites could be done more accurately and more efficiently. The critters on a chip could replace today's bulky, expensive and complicated optical detection systems that use photo multipliers and optical fibers buried in the ground. It could also allow for more extensive monitoring of a remediation site with no increase in cost, Simpson said. "This new development using an integrated chip-based approach with living organisms could dramatically advance the ability to sense a variety of chemical agents in the environment, such as chemical warfare agents or other toxic substances and things like environmental estrogens that could have detrimental effects on living systems," Sayler said. "If it is indeed possible to manufacture these part electronic and part biological systems as a small, inexpensive chip, it would dramatically improve the ability to monitor many different types of environments." Related information on the Internet
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