Palm-size wireless piezoelectric immune-biosensing system for rapid E. coli O157:H7 detection

Rapid and accurate detection of Escherichia coli O157:H7 is essential for ensuring public health, food safety, and environmental monitoring. Traditional detection methods are often time-consuming and require specialized laboratory infrastructure, limiting their practicality for on-site applications. In this study, we present a palm-sized, wireless piezoelectric immunosensor system designed for the swift and sensitive detection of E. coli O157:H7. The system integrates a gold-coated quartz crystal microbalance (QCM) sensor functionalized with protein A-immobilized antibodies, a polydimethylsiloxane (PDMS) microfluidic channel for efficient sample handling, and a flexible loop antenna for wireless signal transmission. Real-time data is transmitted via Bluetooth to a smartphone application, enhancing user interaction and portability. Sensitivity tests demonstrated a proportional increase in frequency shift corresponding to E. coli O157:H7 concentrations, achieving a detection limit as low as 10² CFU ml⁻¹ in field samples. Selectivity tests confirmed minimal cross-reactivity with other bacteria, highlighting the sensor's specificity. The incorporation of immuno-nanobeads amplified the signal, enhancing the system's ability to detect low bacterial concentrations. The portable, self-powered system offers a practical solution for rapid, on-site pathogen detection, addressing critical needs in food safety and environmental monitoring. By enabling timely and accurate detection of contaminants, this technology has the potential to significantly impact public health by reducing the incidence of foodborne illnesses, safeguarding environmental resources, and enhancing overall safety and health outcomes.