Ro Kyung Won, Lim Kwanseop, Shim Bong Chu, Hahn Jong Hoon
Department of Chemistry, Division of Molecular and Life Science, Pohang University of Science and Technology, San 31 Hyoja-Dong, Pohang, 790-784, South Korea.
Anal Chem. 2005 Aug 15;77(16):5160-6. doi: 10.1021/ac050420c.
We have developed an integrated light collimating system with a microlens and a pair of slits for extended optical path length absorbance detection in a capillary electrophoresis (CE) microchip. The collimating system is made of the same material as the chip, poly(dimethylsiloxane) (PDMS), and it is integrated into the chip during the molding of the CE microchannels. In this microchip, the centers of an extended 500-microm detection cell and two optical fibers are self-aligned, and a planoconvex microlens (r = 50 microm) for light collimation is placed in front of a light-delivering fiber. To block stray light, two rectangular apertures, realized by a specially designed three-dimensional microchannel, are made on each end of the detection cell. In comparison to conventional extended detection cell having no collimator, the percentage of stray radiation readout fraction in the collimator integrated detection cell is significantly reduced from 31.6 to 3.8%. The effective optical path length is increased from 324 to 460 microm in the collimator integrated detection cell. The detection sensitivity is increased by 10 times in the newly developed absorbance detection cell as compared to an unextended, 50-microm-long detection cell. The concentration detection limit (S/N = 3) for fluorescein in the collimator integrated detection cell is 1.2 microM at the absorbance detection limit of 0.001 AU.
我们开发了一种集成光准直系统，该系统带有一个微透镜和一对狭缝，用于在毛细管电泳（CE）微芯片中进行长光程吸光度检测。该准直系统由与芯片相同的材料聚二甲基硅氧烷（PDMS）制成，并在CE微通道成型过程中集成到芯片中。在这个微芯片中，一个500微米长的扩展检测池的中心与两根光纤的中心自动对准，并且在一根传光光纤前面放置了一个用于光准直的平凸透镜（r = 50微米）。为了阻挡杂散光，在检测池的每一端制作了两个由特殊设计的三维微通道实现的矩形孔径。与没有准直器的传统扩展检测池相比，集成准直器的检测池中杂散辐射读出分数的百分比从31.6%显著降低到3.8%。集成准直器的检测池中有效光程从324微米增加到460微米。与未扩展的50微米长检测池相比，新开发的吸光度检测池中的检测灵敏度提高了10倍。在0.001 AU的吸光度检测限下，集成准直器的检测池中荧光素的浓度检测限（S/N = 3）为1.2 microM。
