Monitoring DNA hybridization using optical microcavities

The development of DNA analysis methods is rapidly expanding as interest in characterizing subtle variations increases in biomedicine. A promising approach is based on evanescent field sensors that monitor the hybridization process in real time. However, one challenge is discriminating between nonspecific and specific attachment. Here, we demonstrate a hybridization sensor based on an integrated toroidal optical microcavity. The surface is functionalized with ssDNA using an epoxide method, and the evanescent wave of the microresonator excites a fluorescent label on the complementary ssDNA during hybridization. Based on a temporal analysis, the different binding regimes can be identified.