A microfabricated capillary electrophoresis chip with multiple buried optical fibers and microfocusing lens for multiwavelength detection

Abstract

We present a new microfluidic device utilizing multiwavelength detection for high-throughput capillary electrophoresis (CE). In general, different fluorescent dyes are only excited by light sources with appropriate wavelengths. When excited by an appropriate light source, a fluorescent dye emits specific fluorescence signals of a longer wavelength. This study designs and fabricates plastic micro-CE chips capable of performing multiple-wavelength fluorescence detection by means of multimode optic fiber pairs embedded downstream of the separation channel. For detection purposes, the fluorescence signals are enhanced by positioning microfocusing lens structures at the outlets of the excitation fibers and the inlets of the detection fibers, respectively. The proposed device is capable of detecting multiple samples labeled with different kinds of fluorescent dyes in the same channel in a single run. The experimental results demonstrate that various proteins, including bovine serum albumin and beta-casein, can be successfully injected and detected by coupling two light sources of different wavelengths to the two excitation optic fibers. Furthermore, the proposed device also provides the ability to measure the speed of the samples traveling in the microchannel. The developed multiwavelength micro-CE chip could have significant potential for the analysis of DNA and protein samples.

Microcapillary electrophoresis chips utilizing controllable micro‐lens structures and buried optical fibers for on‐line optical detection

“…6a). When compared to the previously reported works which utilized the fixed focal length micro-lens capable of in-channel optical detection, our device can provide higher optical enhancing performance by utilizing the buried optical fibers [11,27], and without a complex micro-lens design [24]. The experimental results indicated that the proposed controllable micro-lens structure is capable of the enhancement of detection signals and sensitivity of the low concentration sample.…”

“…These micro-lenses can be also integrated with microfluidic device for on-line optical detection. For example, the current group [27] reported a micro-lens structure integrated onto a micro-CE chip device with a fixed focal length. By the integration of the micro-lens structure, the signal amplitude of the fluorescent emission can be enhanced by 1.7-fold.…”

Capillary electrophoresis of proteins 2003–2005

“…A number of CE steps and components that are used in fused-silica capillaries have been transferred and successfully tested on a microchip including preconcentration on porous silica membrane [22,23], automated derivatization [29], microreactor with immobilized proteases and other proteins [181,182], UV detector [183,184], chemiluminescence detector [34,185], multiwavelength LIF detector [186], UV LIF detector [98], wall coatings [82,85], affinity CE [129], CIEF [80], and sheathless electrospray for MS [113,114].…”

Fabrication and Performance of a Photonic-Microfluidic Integrated Device

“…Integration of optical waveguides [23][24][25][26][27], filters [28][29][30], focusing elements [24][25][26][27][31][32][33], sources and detectors [28,34,35] have all been demonstrated in an integrated fashion on a microfluidic chip. Integration of optical components on chip allows devices to become self-reliant, portable, and less expensive allowing on-line monitoring possibilities and point-of-care (POC) medical care applications.…”