Advanced diascopic illumination technique for multi-wavelength fluorescence detection in capillary electrophoresis system

This paper presents an advanced diascopic illumination technique for simultaneously multi-wavelength fluorescence excitation and detection without any filter sets. High-throughput capillary electrophoresis detection can be realized with this simple and novel approach. The developed system is composed of a home-built dark-field condenser for fluorescence excitation and an ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer for emitted signal detection. Experimental results show that the proposed system can effectively increase the fluorescent signal. In CE experiment, a fluorescent sample, Rhodamine B, can be successfully detected using this proposed system. Furthermore, a mixed bio-sample composed of three single-strand DNAs labeled with Cy3, FITC, and Alexa647 are successfully separated and detected in a single test run. Results indicate the developed system is capable of achieving full wavelength-resolved fluorescence detection in a single microfluidic channel. The measured detection limit for the developed system is up to 5×10^-8 M (S/N = 3) while detecting a standard fluorescein, which is suitable for general bio-analytical applications.