Label-free electrochemical biosensor for real-time detection of live Salmonella typhimurium in salad samples using...

Rapid detection of live Salmonella typhimurium in food is critical for preventing contamination and protecting public health. Traditional methods, though reliable, are slow, costly, and require centralized labs. Many existing biosensors primarily detect dead bacteria, increasing false-positive risks. To address these limitations, we report a portable biosensor that for the first time enables rapid, label-free, viability-specific detection of live S. typhimurium in food using non-Faradaic electrochemical impedance spectroscopy (EIS). The sensor achieves a detection limit of 9 CFU/mL within 5 min, significantly improving upon conventional techniques. Validation against ELISA confirmed its sensitivity and specificity. The platform exhibits strong analytical performance, maintaining inter- and intra-study coefficient of variation (%CV) below 20 %, confirming its reproducibility. Additionally, the biosensor demonstrates a positive predictive value (PPV) and a negative predictive value (NPV) exceeding 85 %, ensuring reliable detection accuracy. By distinguishing live bacteria, this biosensor provides more precise pathogen assessment, reducing false positives. Its rapid response time, high sensitivity, and ease of use make it an ideal tool for routine food safety testing. This study enhances biosensor technology by integrating a ZnO/Au-based non-Faradaic EIS platform offering a reliable, efficient, and field-deployable solution for bacterial detection, contributing to public health and global food security through timely intervention and contamination prevention.