National Creative Research Initiative Center for Integrated Optofluidic Systems and Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea.
Anal Chem. 2011 Jan 15;83(2):585-90. doi: 10.1021/ac102615z. Epub 2010 Dec 17.
We demonstrate a prototypic optofluidic evanescent wave sensor made of poly(dimethylsiloxane) (PDMS) elastomer in which two light sources with different wavelengths are coupled into an optofluidic liquid-core/liquid-cladding (L(2)) waveguide. The exponentially decaying evanescent wave interacts with analyte molecules dissolved in the cladding fluids or products formed by in situ reactions at the core-cladding interface. The analyte molecules exhibit distinctly different light absorbance at the two wavelengths during the light-analyte interaction. Therefore, by using the normalized absorbance calculated from the intensity ratio of the two wavelengths instead of the absolute magnitude of either signal, unwanted effects from omnipresent external noise sources can be reduced. In addition, the differential absorption of the two beams by the analyte solutions can be used to enhance the resolution of sample analysis. The evanescent wave sensor based on a liquid waveguide can also be used for real-time monitoring of chemical reactions, because the core and cladding fluids in the L(2) waveguide are slightly miscible at the core-cladding interface due to the diffusional mixing.
我们展示了一种由聚二甲基硅氧烷（PDMS）弹性体制成的原型光流体消逝波传感器，其中两个不同波长的光源被耦合到光流体的液芯/液包层（L(2)）波导中。指数衰减的消逝波与溶解在包层流体中的分析物分子或在芯-包层界面处原位反应形成的产物相互作用。在光-分析物相互作用过程中，分析物分子在两个波长处表现出明显不同的光吸收。因此，通过使用从两个波长的强度比计算得到的归一化吸收，而不是信号的绝对值，可以减少来自普遍存在的外部噪声源的干扰。此外，分析物溶液对两束光的差分吸收可用于增强样品分析的分辨率。基于液体波导的消逝波传感器也可用于实时监测化学反应，因为由于扩散混合，L(2)波导中的芯和包层流体在芯-包层界面处略微混溶。
