Integrating functional components into capillary electrophoresis systems using liquid-core waveguides

Abstract

Miniaturization and integration have become strong trends in the development of analytical devices, particularly over the past decade. Miniaturized total analysis systems (lTAS), lab-on-a-chip, and analytical microfluidics are all newly established concepts and methods of realizing such goals, which not only imply the production of portable and wearable analytical devices, but also dramatic enhancements in analysis speed and sample or reagent economy. Various platforms have been developed or adapted for achieving such aims, the most important of which are those based on MEMS (Micro-electromechanical Systems) techniques. However, MEMS techniques have still not quite fulfilled expectations in terms of fully integrating functional sample processing and detection components onto single microdevices. In particular, optical detection components, most commonly employed in analytical systems, have often proved to be too complicated, bulky, and/or costly to be microfabricated and integrated on a chip without sacrificing considerable analytical performance. This is especially true when minimum detection windows and volumes are vital for ensuring optimum performance, as in chip-based capillary electrophoresis (CE) separations, or when highly multiplexed detections are required. In fact, the first few generations of commercialized lab-chip CE products, albeit successful, have not yet attempted on-chip integration of detection components (except for the detection window itself). Among various possible routes towards complete integration, techniques based on liquid-core waveguides (LCW) have recently shown great promise. The state-ofart of CE with LCW is briefly reviewed in this article, and the potential for and perspectives on the miniaturization and integration of CE systems with light-emitting diode (LED)-excited fluorimetric detectors are discussed.