Ultrasensitive label-free microcavity biosensors with high selectivity

High quality factor whispering gallery mode microresonators have been recently shown to exhibit detection sensitivity of single molecule; however, the selectivity of these sensors among different types of analytes remains as an important issue, obscuring the broad applicability of optical microcavities. We demonstrate a surface modification strategy for fabrication of high selectivity and sensitivity microcavity biosensors in this study.