| Popis: |
Based on a non-sequential raytrace simulation, a previously developed tubular optical waveguide probe for magnetic- focusing immunosensors has been redesigned and tested. The design features a tubular waveguide tapered at both ends with a tapered magnet embedded inside of the waveguide. For reducing background, the excitation light is directly projected into the sample solution via a fiber against the cuvette wall adjacent to the waveguide. The fluorescent signal is collected by the probe and is coupled into a transmission fiber at the distal end of probe. Simulated antigen samples (paramagnetic microspheres of 5-micron diameter with immobilized antibodies that are labeled with Cy5 dye) have been prepared for testing magnetic signal enhancement and fluorescent signal collection. Typical results show that the sensitivity of the tubular probe is one order of magnitude higher than that of a similar dual- fiber probe. With the improved excitation and transmission scheme, the new tubular probe reduces background noise to one-third that of a previously reported tubular probe and is less sensitive to the interference of ambient light. |
