An integrated optical/microfluidic platform for real-time affinity biosensing

A major challenge in many biosensing applications is the real-time detection of a multitude of analytes from a small sample volume. Achieving these goals would perhaps eliminate the need for an intermediate molecular amplification step. Our approach to this challenge involves the investigation of high sensitivity and scalable integrated optical transduction and scalable microfluidic sample delivery. The microfluidic architecture has small cross-section and allows the sample to visit each sensing zone, where a biospecific monolayer performs molecular recognition. Signal transduction occurs via a resonant optical microcavity, which has the dramatically increased signal to noise ratio in fluorescence detection necessary to detect small molecular numbers. Important performance issues in this architecture are sample flow rates, sensing zone size, and the use of passive mixing structures. In addition, microfabrication issues such as optical and microfluidic design, materials, and monolayer patterning are discussed.