Spotting the presence of E. coli can go a long way toward preventing the spread of this bacterium through food and water. Currently, testing can take hours, sometimes even over a day, a serious problem as people eat and drink multiple times daily. Researchers from the Univeristy of Quebec and Indian Institute of Technology Kanpur developed a new sensor that that detect E. coli within twenty minutes and to do so at temperatures from 20° Celsius to 40° Celsius.
Instead of culturing to be able to detect it, the sensor spots E. coli directly by relying on a bacteriophage that sticks to its body. The bacteriophage is coated over an optical fiber and when E. coli is nearby, it binds with it and in turn changes the optical properties of the optical fiber. When a beam of light is directed over it, the reflecting wavelengths are different depending on whether the bacteria is attached to it or not.
Similar devices have been designed in the past, but they were always very sensitive to the surrounding temperature, only working within a narrow temperature range. This required careful handling, additional expense, and difficulty of using it in the field. The team developed a way to calibrate the device to compensate for different temperatures it would be used in.
Study in Optics Letters: Compact and cost-effective temperature-insensitive bio-sensor based on long-period fiber gratings for accurate detection of E. coli bacteria in water…
Via: The Optical Society…