Evanescent-Wave Fiber-Optic Fluorometer Capable of Dense Channel Multiplexing, Signal Enhancement and Stray Excitation Light Suppression

A modified evanescent-wave fiber-optic fluorometer capable of dense channel multiplexing, simultaneous signal enhancement and suppression of excitation stray light is examined. To achieve these features in combination, a multimode fiber is decladded at numerous positions to form channels, with each individual decladded section approximately 2 mm wide. The illuminating fiber is then aligned perpendicular to one of the channels covered by a sample droplet. When the fluorescent samples or water droplets are added to or removed randomly from other channels, interchannel crosstalk is found to be completely suppressed, confirming the ability of the proposed fluorometer to multiplex a large number of channels. The maximum acceptable channel length is also explored. Zero interchannel crosstalk is demonstrated with a channel separation of 1 mm or less, indicating the possibility of dense multiplexing of channels within a short fiber segment. This study established the foundation for an alternative approach to analysis of multiple samples located in separate channels that eliminates the need to consider either the sequence in which samples are added or removed, or the number of samples. In particular, signals from samples can be examined individually or assayed in group to form a single spectrum or more overlapped spectra, enabling online comparisons. In addition, all channels share a single extremely cost-effective detection system whose reliability is guaranteed by the aforementioned superior signal quality.