PANI/TiO₂ nanocomposite-based chemiresistive gas sensor for the detection of E. Coli bacteria

In the modern pace of the world, food safety is a major concern. In this work, a simple chemiresistive type gas sensor was fabricated to detect Escherichia Coli (E. coli) bacteria. Polyaniline (PANI) films were deposited on the indium tin oxide substrate by an electrochemical deposition method. TiO₂ nanoparticles were synthesised by facile hydrothermal method. PANI films were modified using hydrothermally prepared TiO₂ nanoparticles by a spin coating method. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and ultraviolet-visible spectrophotometer techniques were used to characterise the PANI/TiO₂ nanocomposites. The peaks obtained in the XRD pattern confirmed the anatase phase of TiO₂ nanoparticles. FESEM analysis showed the nanofibrous structure of the nanocomposite. The FTIR characteristic peaks confirmed the formation of the nanocomposite. The electrical resistance of the sensors was evaluated as a function of the bacterial concentration. The PT2 (TiO₂ coated 5 times on PANI) in comparison with PT1 (TiO₂ coated 3 times on PANI) exhibited good sensitivity to the gas molecules at room temperature. The p-n junction at PANI/TiO₂ interface improved the physical adsorption of gas molecules. Since no specific antibodies or receptors are used, the sensor has the potential for adaptation to real-life applications. Thus low cost, real-time, portable, reusable and sensitive bacteria sensors were fabricated and tested.