Optical detection of molecular beacons in microfluidic devices

Hybridization and detection of E. coli ribosomal RNA with molecular beacons labeled with a fluorescent dye is achieved in a microfluidic device. The device consists of a four ports mixing chamber, where the probes and the target molecules mix by diffusion. The weak fluorescent signal is detected by two large core optical fibers that are placed on both sides of the channel and collect the light emitted in both directions. The fibers are coupled to a spectrophotometer. The detection limit for the system is 0.2 fmol.