Centre de Recherche en Photonique, Université du Québec en Outaouais, 101 rue Saint-Jean-Bosco, Gatineau, QC J8X 3X7, Canada.
Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland.
Sensors (Basel). 2020 Jul 5;20(13):3772. doi: 10.3390/s20133772.
Selected optical fiber sensors offer extraordinary sensitivity to changes in external refractive (RI), which make them promising for label-free biosensing. In this work the most sensitive ones, namely long-period gratings working at (DTP-LPG) and micro-cavity in-line Mach-Zehnder interferometers (µIMZI) are discussed for application in bacteria sensing. We describe their working principles and RI sensitivity when operating in water environments, which is as high as 20,000 nm/RIU (Refractive index unit) for DTP-LPGs and 27,000 nm/RIU for µIMZIs. Special attention is paid to the methods to enhance the sensitivity by etching and nano-coatings. While the DTP-LPGs offer a greater interaction length and sensitivity to changes taking place at their surface, the µIMZIs are best suited for investigations of sub-nanoliter and picoliter volumes. The capabilities of both the platforms for bacteria sensing are presented and compared for strains of , lipopolysaccharide , outer membrane proteins of and . While DTP-LPGs have been more explored for bacteria detection in 10-10 Colony Forming Unit (CFU)/mL for and 10-10 CFU/mL for , the µIMZIs reached 10-10 CFU/mL for and have a potential for becoming picoliter bacteria sensors.
选定的光纤传感器对外部折射率（RI）的变化具有非凡的敏感性，这使它们在无标记生物传感中具有广阔的应用前景。在这项工作中，我们讨论了最敏感的光纤传感器，即长周期光纤光栅（DTP-LPG）和微腔光纤马赫-曾德尔干涉仪（µIMZI），它们可用于细菌传感。我们描述了它们在水环境中的工作原理和 RI 灵敏度，DTP-LPG 的 RI 灵敏度高达 20000nm/RIU（折射率单位），µIMZI 的 RI 灵敏度高达 27000nm/RIU。特别关注通过刻蚀和纳米涂层来提高灵敏度的方法。虽然 DTP-LPG 提供了更大的相互作用长度和对表面变化的敏感性，但 µIMZI 最适合研究亚纳升和皮升体积。介绍了两种平台对细菌传感的能力，并对 、脂多糖、 和 外膜蛋白的菌株进行了比较。虽然 DTP-LPG 已经在 10-10 菌落形成单位（CFU）/mL 的浓度下对 和 10-10 CFU/mL 的浓度下对 进行了更深入的研究，但 µIMZI 对 达到了 10-10 CFU/mL 的检测限，并且具有成为皮升级细菌传感器的潜力。
