Thin-film polymer light emitting diodes as integrated excitation sources for microscale capillary electrophoresis

Abstract

We report the use of a thin-film polymer light emitting diode as an integrated excitation source for microfabricated capillary electrophoresis. The polyfluorene-based diode has a peak emission wavelength of 488 nm, an active area of 40 microm x 1000 microm and a thickness of similar 2 mm. The simple layer-by-layer deposition procedures used to fabricate the polymer component allow facile integration with planar chip-based systems. To demonstrate the efficacy of the approach, the polyfluorene diode is used as an excitation source for the detection of fluorescent dyes separated on-chip by electrophoresis. Using a conventional confocal detection system the integrated pLED is successfully used to detect fluorescein and 5-carboxyfluorescein at concentrations as low as 10(-6) M with a mass detection limit of 50 femtomoles. The drive voltages required to generate sufficient emission from the polymer diode device are as low as 3.7 V.

Recent developments in detection for microfluidic systems

“…Only visual inspection of the excitation of the fluorescent dye Rhodamine B was performed. Edel and coworkers [29] also reported on the use of OLEDs for detection in microfluidic devices. A polyfluorene-based OLED was fabricated on a separate glass substrate, which subsequently was placed in close proximity to a capillary electrophoresis glass chip.…”

CE detector based on light‐emitting diodes

“…To demonstrate that coherent sources are not required, they employed a blue LED (l max = 485 nm) as the light source. The use of a thin-film polymer light emitting diode as an integrated excitation source for microfabricated CE has been reported [23]. The polyfluorene-based diode has a peak emission wavelength of 488 nm, an active area of 40 mm61000 mm, and a thickness of ,2 mm.…”

Embedding Organic Light‐Emitting Diodes into Channel Waveguide Structures

“…Among the various devices that have been proposed are chemical gas sensors, [1] thermometers based on temperature-dependent intersystem crossing rates, [2] OFET-based biosensors for electrochemical ion detection [3] and a range of optofluidic and photonic devices. [4][5][6] Although these examples provide an impressive demonstration of the potential sensitivity of organic biosensors, the technology still awaits commercialization, in part because of issues regarding the selectivity of the sensors. For optical sensors, which are of particular interest owing to their potentially high selectivity, the integration of suitable light sources is one of the biggest challenges.…”