Label-free detection of chemical messenger proteins

Recently, quality factors greater than 100 million were demonstrated using planar arrays of silica microtoroid resonators. These high Q factors allow the toroidal resonators to perform very sensitive detection experiments. By functionalizing the silica surface of the toroid using antibodies, the toroidal resonators become both specific and sensitive detectors. Targeted detection of Interleukin-2, a cytokine which stimulates production of T cells, is demonstrated. Additional cross-reactivity experiments are also performed to verify the sensor's behavior in a more complex environment.