Use noncontact sensor to detect E. coli.

Researchers at SatCon Technology Corp. (161 First St., Cambridge, MA 02142) are developing a Remote Inspection Biological Sensor (RIBS) at the company's Space and Electro-optics Division (Tucson, AZ). The non-contact sensor has successfully detected E. coli and Salmonella in contaminated meat on a real-time basis. Scientists have been working with Northern Plains Premium Beef, a state agricultural cooperative encompassing several Midwestern states and Canadian provinces, to ensure that when completed, the device can be efficiently integrated into beef processing lines.

The scientists also expect that the sensor will detect other food pathogens, including those in poultry, seafood, fruits and vegetables. Researchers intend to develop and manufacture engineering and beta site units. The sensor is reported to use a laser spectrographic technique. The device uses laser light that reflects off and interacts with pathogens on a carcass surface. The sensor detects the characteristics of the returning signal.

Because pathogens have a very specific signature, the system can make an identification and give a general indication of the number of organisms that are present. The developers believe the technology will have a detection sensitivity of 5 CFU/cm2 and effectively discriminate target organisms from background.

According to the U.S. Centers for Disease Control and Prevention, an estimated 5 million cases of food-related illness occur each year, and 4,000 of these cases result in death.

In the past, we reported that an integrated optic biosensor developed at the Georgia Institute of Technology (Georgia Tech Research Institute, EOEML, Room 223, Baker Building, Atlanta, GA 30332) detected Salmonella in meat in less than 3 hr, compared with other techniques that take 6 hr. Researchers would like to cut detection time to 1 hr by streamlining sample preparation and incubation time.

The basic transducer technology for the device found its first application as a sensor for monitoring ammonia levels in crop lands to improve fertilizer management. Besides Salmonella-tainted meat, the developers believe the sensor can detect other bacteria in a variety of foods.

The biosensor is based on light that slows down or speeds up when passing through substances that have different optical properties. Direct detection is possible by measuring an organism's influence on the sensor's optical properties. A tiny laser transmits a beam along a micro-thin disposable waveguide deposited on a small glassy electronic chip. A waveguide is a 0.1-micron to 1-micron-thick film deposited on the substrate of a fused silica disk. It is the sensing element.

Chemically-selective agents, such as microbial antibodies that bind to specific microorganisms, attach to the surface of a waveguide. When certain microorganisms are present in samples applied to the sensor, their cellular components, such as flagella, quickly attach to the antibodies on the waveguide. When light passes through the waveguide, its altered optical properties cause it to move at a slower speed.

Further information. At SatCon: William O'Donnell; phone: [phone]; fax: [phone]. At Georgia Tech: Nile Hartman; phone: [phone]; fax: [phone].