A compactly integrated laser‐induced fluorescence detector for microchip electrophoresis

Abstract

A simple and easy-to-use integrated laser-induced fluorescence detector for microchip electrophoresis was constructed and evaluated. The fluid channels and optical fiber channels in the glass microchip were fabricated using standard photolithographic techniques and wet chemical etching. A 473 nm diode-pumped laser was used as the excitation source, and the collimation and collection optics and mirrors were discarded by using a multimode optical fiber to couple the excitation light straight into the microchannel and placing the microchip directly on the top of the photomultiplier tube. A combination of filter systems was incorporated into a poly(dimethylsiloxane) layer, which was reversibly sealed to the bottom of the microchip to eliminate the scattering excitation light reaching to the photomultiplier tube. Fluorescein/calcein samples were taken as model analytes to evaluate the performance with respect to design factors. The detection limits were 0.05 microM for fluorescein and 0.18 microM for calcein, respectively. The suitability of this simple detector for fluorescence detection was demonstrated by baseline separation of fluorescein isothiocyanate (FITC)-labeled arginine, phenylalanine, and glycine and FITC within 30 s at separation length of 3.8 cm and electrical field strength of 600 V/cm.

Separation of catecholamines by microchip electrophoresis with a simple integrated laser-induced fluorescence detector

“…In our previous experiments as reported [20], if the separation channel was etched prior to further deep etching the OP insertion channel, as shown in Fig. 1b, the detection region, viz.…”

“…2, a simple MCE-LIF detection system with the virtue of optical fiber was constructed and some characteristics of the system have been demonstrated in detail previously [20]. A 473 nm blue diode laser (Beijing Viasho Technology, China) was used as the excitation source.…”

“…In contrast, if we etched the separation channel after completing fabrication of the OP insertion channel, the detection region could be protected perfectly (shown in Fig. 1c), The minimum distance between the separation channel and the end of the OP insertion channel was controlled to be as short as 190 m. According to the calculational methods described previously [20], the excitation beam launched from the optical fiber with 100 m core diameter will give an expanded laser spot of 156 m diameter on the separation channel. This excitation spot was small enough for the MCE separation.…”

Development of a gel monolithic column polydimethylsiloxane microfluidic device for rapid electrophoresis separation

“…The analytes detection was performed by a home-built compactly laser-induced fluorescence (LIF) detector [24]. The entire detection system included a blue diode-pumped laser (473 nm) (Beijing Viasho Technology, China) which operated in constant mode at room temperature serving as excitation source, a photomultiplier tube (PMT) (Institute of Biophysics Chinese Academy of Sciences, China) for collecting fluorescence signal, a 530 nm interference filter and a holographic notch plus filter (476 nm) (Kaiser Optical System, Ann Arbor, MI, USA) above the PMT for filtering the excitation light.…”

Modeling Fluorescence Detection for Microfluidic Card

“…Although they used microfuluidic cards, some of them still incorporated bulky and expensive detection devices, such as a microscope, laser source, photomultiplier tube (PMT), and complex optical components in the system (Li et al 2004;Maminski et al 2005;Fu et al 2006). This article provides a model that will make the detection system compact, simple, and inexpensive, but without compromising the sensitivity.…”