Benéitez Nuria Teigell, Baumgartner Bettina, Missinne Jeroen, Radosavljevic Sanja, Wacht Dominik, Hugger Stefan, Leszcz Paweł, Lendl Bernard, Roelkens Gunther
Opt Express. 2020 Aug 31;28(18):27013-27027. doi: 10.1364/OE.399646.
A novel platform based on evanescent wave sensing in the 6.5 to 7.5 µm wavelength range is presented with the example of toluene detection in an aqueous solution. The overall sensing platform consists of a germanium-on-silicon waveguide with a functionalized mesoporous silica cladding and integrated microlenses for alignment-tolerant back-side optical interfacing with a tunable laser spectrometer. Hydrophobic functionalization of the mesoporous cladding allows enrichment of apolar analyte molecules and prevents strong interaction of water with the evanescent wave. The sensing performance was evaluated for aqueous toluene standards resulting in a limit of detection of 7 ppm. Recorded adsorption/desorption profiles followed Freundlich adsorption isotherms with rapid equilibration and resulting sensor response times of a few seconds. This indicates that continuous monitoring of contaminants in water is possible. A significant increase in LOD can be expected by likely improvements to the spectrometer noise floor which, expressed as a relative standard deviation of 100% lines, is currently in the range of 10A.U.
本文以水溶液中甲苯检测为例，介绍了一种基于6.5至7.5微米波长范围内倏逝波传感的新型平台。整个传感平台由一个带有功能化介孔二氧化硅包层的硅基锗波导和用于与可调谐激光光谱仪进行耐对准背面光学接口的集成微透镜组成。介孔包层的疏水功能化能够富集非极性分析物分子，并防止水与倏逝波发生强烈相互作用。对甲苯水溶液标准品的传感性能进行了评估，检测限为7 ppm。记录的吸附/解吸曲线符合弗伦德利希吸附等温线，具有快速平衡，传感器响应时间为几秒。这表明对水中污染物进行连续监测是可行的。预计通过可能改善光谱仪本底噪声可显著提高检测限，目前光谱仪本底噪声以100%谱线的相对标准偏差表示，在10 A.U.范围内。
