Conformable surface acoustic wave biosensor for E-coli fabricated on PEN plastic film

Over the last decades, great effort has gone into developing new biosensor technologies for applications in different fields such as disease diagnosis and detection of pollutants in water and food. Global developments in robotic, IoT technologies and in healthcare sensors require new flexible sensor technologies that are low cost and built from sustainable and reusable or recyclable materials. One of the most promising technologies is based on the development of surface acoustic wave (SAW) flexible biosensors, which are highly reproducible, reliable and wirelessly controllable. This work presents for the first time a novel aluminum nitride (AlN)-based conformable SAW immunosensor fabricated on recyclable polyethylene naphthalate. We apply it to the detection of E.Coli using a faster and innovative functionalization method that exploit Protein-A/antibody affinity. A higher sensitivity (Limit of detection-LoD, 6.54*10⁵ CFU/ml) of the Lamb wave traveling on the polymeric device has been obtained in comparison with SAWs traveling on AlN on silicon substrate (LoD, 1.04*10⁶ CFU/ml). Implementation of a finite element method allowed for the estimation of the single E.Coli mass of approximately 9*10^-13 g. This work demonstrates the high biosensing potential of flexible polymeric SAW devices for bacteria contamination control in food chain, water and smart packaging.