Novel sandwich technology improves sensitivity of rapid tests

© 2021 EPFL - Scientists have developed a method for boosting the sensitivity of rapid-detection tests like those used for the new coronavirus. The results of their feasibility study have just been published in Nano Letters. Pregnancy tests and rapid-detection tests for the new coronavirus work in the same way. They contain a surface - usually made of metal - on which chemical nanosensors detect specific compounds in a sample of urine, saliva or blood that indicate the presence of a given protein or part of a virus. "The tests show up as positive if their sensors come into contact with the target compound," says Olivier Martin, head of EPFL's Nanophotonics and Metrology Laboratory, within the School of Engineering. This biological mechanism is invisible to the naked eye, but the way the metal is structured makes it able to interact with light, creating disturbances in the light's movement. "These disturbances are what tell us that a sensor on the metal surface has come into contact with the target compound," says Martin.