Optimization of confocal epifluorescence microscopy for microchip-based miniaturized total analysis systems

New advances in microchip fabrication for electrochromatography

“…Figure 4A and B depicts the use of a miniaturized LC using an injection unit (upper panel) and compares the resulting peaks (lower panel) [87]. Cleaning and sample injection may need special connections for high-pressure analytical procedures such as microchip electrochromatography and nanoLC [88][89][90][91]. To address this issue, a system was proposed where a microchip including a chromatographic column compartment was employed for EOF and also pressure-driven chromatography in a way where electrode vessels and fluid transfer fittings were placed in a large rack [88].…”

Integration of a flow-type chemiluminescence detector on a glass electrophoresis chip

“…However, to realize miniaturization and integration of lab-on-a-chip devices, it is indispensible to employ equally miniaturized detectors. Up to now, laser-induced fluorescence (LIF) [9,10] and mass spectroscopy (MS) [11,12] have been most often utilized for -TAS detection because of their high sensitivity. Although submicromolar detectability can be readily obtained with these two types of detectors, the high cost and large size of the instruments are quite incompatible with the concept of -TAS.…”

Determining under‐ and oversampling of individual particle distributions in microfluidic electrophoresis with orthogonal laser‐induced fluorescence detection

“…The method described by Ocvirk et al [20] was used to determine the mass LOD of this orthognal LIF system. Briefly, a solution containing 1 nM fluorescein is continuously introduced into the separation channel.…”

“…LIF was used in the first microfluidic devices [11][12][13] because its power as a detection scheme made it an ideal match for the small sample quantities and, typically, pL-sized detection volumes. Ocvirk et al [20] later pioneered the use of epifluorescence in microfluidics, which focuses the laser and collects the fluorescence through the same objective, and achieved a zmol LOD. Epifluorescence quickly became very popular because of the simplicity of the epifluorescence design and the availability of commercial microscopes designed with epifluorescence capability.…”

“…Estimation of LOD values has been based on either fixed injections or continuous delivery of known amounts of a fluorophore to the LIF detector [20]. The latter is a more accurate description of a detector's ability to analyze particles because it represents how many fluorophores need to be present within the detector volume to obtain a detectable signal.…”