Abstract

High efficiency separations coupled with rapid response times have been demonstrated on capillary electrophoresis devices micromachined on glass substrates. [1-3] Although detection of single organic dyes has been achieved with fluorescence detection in capillaries, [4] such detection limits have not yet been demonstrated in micromachined channels. Efficient, single molecule detection is desirable for many potential applications such as rapid DNA sequencing. The structure of microfabricated separation channels, however, does not readily facilitate a 90° fluorescence excitation/collection geometry which has been used to achieve high sensitivities in capillaries. [4] This optical geometry allows efficient spatial rejection of scattering at the capillary solution interfaces. Confocal detection in which the excitation source is introduced through the collection optics provides a means of achieving both high axial resolution and high collection efficiency.

© 1996 Optical Society of America