Bürck J, Zimmermann B, Mayer J, Ache H J
Forschungszentrum Karlsruhe, Technik und Umwelt, Institut für Radiochemie, P.O. Box 3640, D-76021, Karlsruhe, Germany.
Anal Bioanal Chem. 1996 Jan;354(3):284-90. doi: 10.1007/s0021663540284.
A new, long-path integrated optical (IO) sensor for the detection of non-polar organic substances is described. The sensing layer deposited on a planar multimode IO structure is built by a suitable silicone polymer with lower refractive index (RI). It acts as a hydrophobic matrix for the reversible enrichment of non-polar organic contaminants from water or air. Light from the near-infrared (NIR) range is coupled into the planar structure and the evanescent wave part of the light field penetrating into the silicone layer interacts with the enriched organic species. As a result, light is absorbed at the characteristic frequencies of the corresponding C-H, N-H or O-H overtone and combination band vibrations of the analytes. To perform evanescent field absorbance (EFA) measurements, the arc-shaped strip waveguide structure of 172 mm interaction length was adapted to a tungsten-halogen lamp and an InGaAs diode array spectrograph over gradient index fibers. Dimethyl-co-methly(phenyl)polysiloxanes with varying degrees of phenylation were prepared and used as sensitive coating materials for the IO structure. Light attenuation in the arc-shaped waveguides is high and typical insertion losses in the range of 14-18 dB were obtained. When the coated sensors were brought in contact with aqueous samples, the light transmission decreases, which is due to the formation of H(2)O micro-emulsions in the silicone superstrates. Nevertheless, after reaching constant light transmissions, absorbance spectra of aqueous trichloroethene samples were successfully collected. For gas measurements, where water cross sensitivity problems are absent, the sensitivity of the IO device for trichloroethene was tested as a function of the RI of the silicone superstrate. The slope of the TCE calibration function increases by a factor of 10 by using a poly(methylphenylsiloxane) layer with a RI of 1.449 instead of poly(dimethylsiloxane) (RI: 1.41). A comparison of the IO-EFA and an earlier developed fiber-optic EFA sensor for trichloroethene measurements in the gas phase showed an increase in sensitivity per unit length of the waveguide by a factor of up to 120.
本文描述了一种用于检测非极性有机物质的新型长程集成光学（IO）传感器。沉积在平面多模IO结构上的传感层由具有较低折射率（RI）的合适有机硅聚合物构成。它作为一种疏水基质，用于从水或空气中可逆地富集非极性有机污染物。近红外（NIR）范围内的光耦合到平面结构中，穿透有机硅层的光场的倏逝波部分与富集的有机物质相互作用。结果，光在分析物相应的C-H、N-H或O-H泛音以及组合带振动的特征频率处被吸收。为了进行倏逝场吸光度（EFA）测量，将172毫米相互作用长度的弧形条形波导结构通过渐变折射率光纤适配到钨卤灯和铟镓砷二极管阵列光谱仪上。制备了不同苯基化程度的二甲基-共-甲基（苯基）聚硅氧烷，并用作IO结构的敏感涂层材料。弧形波导中的光衰减很高，典型的插入损耗在14-18分贝范围内。当涂覆的传感器与水性样品接触时，光传输会降低，这是由于在有机硅上层中形成了H₂O微乳液。然而，在达到恒定的光传输后，成功收集了三氯乙烯水性样品的吸光度光谱。对于不存在水交叉敏感性问题的气体测量，测试了IO装置对三氯乙烯的灵敏度与有机硅上层折射率的函数关系。通过使用折射率为1.449的聚（甲基苯基硅氧烷）层而不是聚（二甲基硅氧烷）（折射率：1.41），三氯乙烯校准函数的斜率增加了10倍。对用于气相中三氯乙烯测量的IO-EFA和早期开发的光纤EFA传感器进行比较，结果表明波导单位长度的灵敏度提高了高达120倍。
