Researchers have introduced a novel, thermal biosensor for real-time detection of Escherichia coli, demonstrating its ability to detect the pathogen in milk without sample preparation. The sensor would be easy to mass produce, and shows potential as a low-cost, rapid tool for onsite microbial indication.

The technology is based on screen-printed electrodes (SPEs), functionalized by a simple surface-imprinting process that represents an easily scalable strategy for the production of synthetic receptors. SPEs have become increasingly popular for biosensor applications in recent years due to their low-cost and scalable production process. The SPEs were used in combination with the heat transfer method to detect E. coli.

To test the selectivity of the sensor, researchers deployed Cronobacter sakazakii, Klebsiella pneumonia, and Staphylococcus aureus. The results suggest that sensor is able to identify food samples with a high bacterial load. Its response towards E. coli was three times higher when compared to C. sakazakii and S. aureus, and around two times higher than K. pneumoniae.

The device is proposed as a rapid pre-screening tool that can be used in combination with current best practices. To illustrate the usefulness of the sensor, it was tested in milk samples inoculated with E. coli without the need for sample preparation. The results aligned with results obtained in a buffer experiment.

Overall, the sensor enables the detection of E. coli in real time, as well as the label-free quantification of the pathogen with experimental procedures that require little to no instrumentation. The researchers call for further work aimed at testing the sensor in increasingly complex food products, ranging from increasingly viscous dairy products to extracted solid food products that might influence the selectivity or sensitivity of the device.