A setup consisting of a bifurcated optical fiber made from high-transmission fused-silica cores with relatively high numerical
apertures (NA=0.22), high-power cyan light-emitting diodes (LEDs) and Peltier cooling elements controlled by a proportional–integrative–derivative
(PID) module is introduced to replace bulky, power- consuming lasers conventionally used in laser induced fluorescence (LIF)
microchip capillary electrophoresis (μCE). The output fiber beam size, divergence, power distribution and power stability
over time are documented. A modified epifluorescence microscope arrangement is used in conjunction with a compact fixed spectrometer
aligned with a cooled charge-coupled device (CCD) camera for added sensitivity. Fluorescent dyes such as fluorescein, 6-carboxyfluorescein
(6-FAM) and rhodamine B can be detected in cyclic olefin copolymer (COC) and glass microchannels at submicromolar levels.
A single-stranded DNA oligonucleotide (10-mer) labeled with 6-FAM is also detected with reasonable signal-to-noise ratio when
electrophoretically migrated at 100 V/cm. The compact LED excitation system presented herein will allow using capillary electrophoresis
for DNA detection in compact mobile devices.
PACS 42.72.Bj - 42.15.Eq - 42.81.Wg - 42.62.Be - 87.15.Tt