A plasmonic tilted fiber Bragg grating (TFBG)-based sensor for the detection of calcium ion (Ca) was proposed and demonstrated experimentally. Hydrogel material was synthesized by utilizing hydrogen bond recombination between cellulose nanocrystals (CNC) and polyvinyl alcohol (PVA). Sodium alginate (SA) was incorporated into this hydrogel material, resulting in a composite membrane with specific binding properties for Ca. The membrane was applied as a coating on the surface of a gold-coated TFBG. The CNC/PVA-SA modified gold on the TFBG surface enhanced the localized refractive index changes caused by variations of Ca concentrations. The experimental results demonstrated an impressive limit of detection (LOD) of approximately 0.025 fM, which is five orders of magnitude better than the current LODs of similar Ca sensors. And the proposed Ca sensor exhibited a wide dynamic range of 10 M to 10 M.

中文翻译：

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基于水凝胶结合海藻酸钠的光纤表面等离子体共振用于钙离子痕量检测


提出了一种基于等离子体倾斜光纤布拉格光栅（TFBG）的传感器，用于检测钙离子（Ca），并进行了实验演示。利用纤维素纳米晶体（CNC）和聚乙烯醇（PVA）之间的氢键重组合成水凝胶材料。将海藻酸钠 (SA) 掺入该水凝胶材料中，形成具有特定 Ca2+ 结合特性的复合膜。该膜作为镀金 TFBG 表面的涂层。 TFBG 表面的 CNC/PVA-SA 改性金增强了 Ca 浓度变化引起的局部折射率变化。实验结果表明，检测限 (LOD) 令人印象深刻，约为 0.025 fM，比当前类似 Ca 传感器的 LOD 好五个数量级。所提出的 Ca 传感器表现出 10 M 至 10 M 的宽动态范围。