Rapid and Sensitive Electrochemical Detection of <i>Escherichia coli</i> in Water Using Cr–Au IDE-Porous Silicon Sensor

An efficient electrochemical sensor based on Cr–Au interdigitated electrode porous silicon has been developed to rapidly assess <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Escherichia coli (E. coli)</i> bacteria in water. Coliform bacteria, particularly <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E. coli</i>, contribute significantly to waterborne contamination, driven by overuse and insufficient cleanliness around water bodies. This letter incorporates the fabrication of porous silicon (PSi), characterization, synthesis of bacterial dilutions, and testing of the sensor in the presence of varying <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E. coli</i> dilutions. The dilutions are prepared from the stock solution of bacterial concentrations and hydrogen peroxide (H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>). The interaction of porous silicon with bacteria incubated in H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> leads to a change in potential across the electrodes in real time. The limits of detection and sensitivity for the sensor are 0.187 CFU/mL and 113 mV⋅mL/CFU, respectively. The response time and the recovery time of the sensor are 80 and 90 ms, respectively. In addition, analyses such as repeatability and testing in tap water, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pseudomonas</i>, and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Citrobacter</i> are conducted. For a user-friendly output, the sensor has been interfaced with a signal conditioning circuit and a display. This prototype offers a quick and precise way to identify the quality of drinking water, making it a potential solution to the growing problems caused by water pollution.