Fluorescence detection integrated optics

Qi, S., X. Liu, S. Ford, J. Barrows, G. Thomas, K. Kelly, A. McCandless, K. Lian, J. Goettert, and S. A. Soper. Microfluidic devices fabricated in poly(methyl methacrylate) using hot-embossing with integrated sampling capillary and fiber optics for fluorescence detection. Lab on a Chip, 2, 88-95 (2002). 

Optical fibers (excitation and emission) have also been integrated on a PMM A chip for fluorescent detection. An intercalating near-IR dye (TOPRO-5) with an excitation wavelength of 755 nm was used to label DNA fragments. Sub-attomol detection limit of the labeled DNA fragments was achieved [674]. 

Integration of a lens was also achieved by molding a cylindrical lens together with a PDMS channel. Both the lens and the channel serve as an optical waveguide for fluorescent detection of FITC-labeled albumin (LOD = 0.3 g/L) [689]. 

A planar optical waveguide was integrated within a PDMS chip for fluorescent detection. The waveguide consists of a 150-nm-thick silicon nitride layer deposited on a 2.1-pm-thick Si02 buffer layer on a Si substrate. The rabbit IgG was... 

In order to integrate the optics in the microchip for fluorescent detection (see Figure 7.7), describe how a bandpass emission filter is fabricated. (2 marks)... 

LIF detection is the most sensitive optical method so far, but is hard to miniaturize in order to satisfy the ultimate goal of a microfluidic chip that assembles all analytical processes within one micrometerscale microstructure. Therefore, how to achieve the miniaturization of fluorescence detection on microdevices is becoming an active field for lab-on-a-chip research. Several examples demonstrate recent advances in miniaturized LIF detection on the microchip. In 2005, Renzi et al. designed a hand-held microchip-based analytical instrument that combines fluidic, optics, electrical power, and interface modules and integrates the functions of fluidics, microseparation, lasers, power supplies etc., into an... 

Cell responses to physical or chemical cues are measured in microfluidic devices primarily via optical or electrochemical means. Huorescence is the most widely used optical detection technique, because absorbance detection (commonly used for macroscale assays) is of limited value in microchannels because of the short path lengths. Fluorescence detection, characterized by its unparalleled sensitivity, is easy to implement in microfluidic systems. Chemiluminescence and bioluminescence also offer low detection limits and have less background noise than fluorescence [8]. Electrochemical detectors are even more easily integrated with microfluidic devices and often are much less expensive than optical systems. However, fabrication of electrodes in microchannel devices is a technical challenge, and the electrical fields used in detection can interfere with on-chip processes such as electrophoresis. Electrochemical techniques include potentiometry, amperometry, and... 

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