Electronic sensor to detect E coli
24 October 2006
A sensor that can detect E coli bacteria within minutes by measuring
changes in frequency of vibration of the detector is being developed at
Drexel University in the USA.
Dr Raj Mutharasan, a professor of chemical engineering at Drexel
University, has developed an “intelligent” sensor technology that is
precise, accurate and cheap. Costing just a few dollars, the sensor can
provide a result within 10 minutes and can detect pathogens or bacteria,
like E. coli, with a sensitivity of four cells per milliliter.
The standard detection process of E. coli bacteria in food processing
takes about 24 hours. A sample is taken to a lab and placed on a nutrient
agar. If E. coli is present, they will multiply on the agar and researchers
can visibly identify them.
Mutharasan’s sensor can be placed into a palm-sized device that can be
placed in the hands of food inspectors and growers, and is even cheap enough
to one day enter the home.
The sensor uses E. coli antibodies to detect the bacteria in much the way
that our bodies work. These antibodies are affixed to a narrow sliver of
glass. Attached to the other end of the glass is a ceramic layer that
generates voltage in response to applied mechanical stress.
A voltage is applied to the ceramic layer, making it expand and contract,
causing the glass sliver to vibrate. The sensor detects changes in the glass
sliver’s resonate frequency (the point where vibration is the greatest) and
uses this to determine both the presence and concentration of E. coli
Mutharasan is working with a company to commercialize the device and
expects it to be in the hands of food safety experts soon. Other possible
applications for the sensor technology include detecting prostate cancer
without a biopsy and detecting Alzheimer’s disease.