A Low-Cost Electrochemical Biosensor for Rapid Bacterial Detection

A three-electrode electrochemical biosensor has been developed using printed circuit boards for detecting bacterial contamination. This low-cost, small-size device consists of thin-film gold electrodes and is fabricated using photo-lithography paired with electro-deposition. Pathogen presence is deduced by detection of change in electrical impedance caused by binding of the pathogen to bio-receptors coated on the sensor surface. The biosensor has a total area of 3.2 cm and requires only 100 L of test sample for detection. The sensor geometry has been optimized using techniques from Design of Experiments, and the device can be operated using a small ac excitation potential of magnitude 5 mV. The sensor is tested on the common food-borne pathogen Salmonella typhimurium and is able detect bacterial concentrations of the order of 500 CFU/mL within 6 min. In this paper, the design and fabrication of the biosensor is detailed along with the experiments that validate its performance.