A tapered microfiber sensor based on multiwalled carbon nanotubes (MWCNTs) for detecting the concentration of alizarin red S dye is proposed and verified by experiments. MWCNTs fixed on the surface of optical fiber can adsorb the alizarin red S dye molecule due to its porous structure. The surface refractive index (RI) change caused by MWCNTs coated with the fiber surface adsorbing of red dye can be captured by optical microfiber, which converted into macroscopic wavelength drift in the interference spectrum. The sensor has a high RI sensitivity of 1942.25 nm/RIU and a temperature sensitivity of $-{0.03}\;{\rm nm}/{^\circ}{\rm C}$, which has a low temperature cross-sensitivity. The sensor provides rapid detection of alizarin red S dye in the concentration range of 0–1000 mg/L, and the sensitivity is 0.412 nm/(mg/L) in the low concentration range of 0–25 mg/L. The sensor is expected to be a high-quality platform for safety considerations in environmental protection.

中文翻译：

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通过多壁碳纳米管实现的光学微纤维监测有机染料浓度

提出了一种基于多壁碳纳米管 (MWCNT) 的锥形微纤维传感器，用于检测茜素红 S 染料的浓度，并通过实验进行了验证。固定在光纤表面的多壁碳纳米管由于其多孔结构可以吸附茜素红S染料分子。涂覆有吸附红色染料的纤维表面的 MWCNTs 引起的表面折射率 (RI) 变化可以被光学微纤维捕获，并转化为干涉光谱中的宏观波长漂移。该传感器具有1942.25 nm/RIU的高RI灵敏度和$-{0.03}\;{\rm nm}/{^\circ}{\rm C}$的温度灵敏度，具有低温交叉敏感性。该传感器可在0-1000 mg/L的浓度范围内快速检测茜素红S染料，在0-25 mg/L的低浓度范围内灵敏度为0.412 nm/(mg/L)。该传感器有望成为环保安全考虑的高质量平台。