A review of electrochemiluminescence (ECL) in and for microfluidic analytical devices

The concept and realization of microfluidic total analysis systems (microTAS) have revolutionized the analytical process by integrating the whole breadth of analytical techniques into miniaturized systems. Paramount for efficient and competitive microTAS are integrated detection strategies, which lead to low limits of detection while reducing the sample volume. The concept of electrochemiluminescence (ECL) has been intriguing ever since its introduction based on Ru(bpy)3 (2+) by Tokel and Bard [1] (J Am Chem Soc 1853:2862-2863, 1972), especially because of its immense sensitivity, nonexistent auto-luminescent background signal, and simplicity in experimental design. Therefore, integrating ECL detection into microTAS is a logical consequence to achieve simple, yet highly sensitive, sensors. However, published microanalytical devices employing ECL detection focus in general on traditional ECL chemistry and have yet to take advantage of advances made in standard bench-top ECL strategies. This review will therefore focus on the most recent advancements in microfluidic ECL approaches, but also evaluate the potential impact of bench-top ECL research progress that would further improve performance and lower limits of detection of micro analytical ECL systems, ensuring their desirability as detection principle for microTAS applications.