Graphene-Based Nanosensor Device for Rapid, Onsite Detection of E.coli in Water

Abstract

E. coli bacteria are widely accepted as the indicator bacteria to predict the presence of pathogens in water intended for human consumption. One of the strains of E. coli is the specific subspecies serotype E. coli O157:H7, which is the most prevalent bacterial contaminant and responsible for most E. coli outbreaks in the US. E. coli O157:H7 can cause bloody diarrhea, kidney failure and may even lead to death. E. coli infection in the U.S. afflicts ~70,000 people per year mostly from food, and ~ 15% of the cases are from tainted water according to the CDC. In May 2014, E. coli-contaminated water supply in Portland, OR, which covers several suburban cities, affected ~670,000 people. Several approaches have been developed to detect E. coli O157:H7, including the culture and colony counting method, polymerase chain reaction (PCR), and immunological methods; however, all these methods require long detection time and are unsuitable for in situ detection. We propose a novel method for real-time, in situ detection of E. coli in water by using a graphene-based sensor. Graphene has excellent electrical conductivity and is very sensitive to surface changes enabling it to detect E. coli bacteria down to a few colony forming units (cfu). The proposed sensor is based on a novel, micro-sized amperometric sensor that outperforms existing E. coli sensing methods and is simple to implement, eliminating many of the disadvantages associated with current practices. Additionally, we plan to integrate this sensor in a handheld electronic device with features such as high sensitivity and selectivity, rapid response, ease of use and affordability.