Cano-Velázquez Mildred S, Hendriks Arthur L, Picelli Luca, van Veldhoven Rene P J, Fiore Andrea
Department of Applied Physics and Science Education, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
Eindhoven Hendrik Casimir Institute, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
Sensors (Basel). 2023 Sep 6;23(18):7703. doi: 10.3390/s23187703.
We demonstrate fiber optic sensors with temperature compensation for the accurate measurement of ethanol concentration in aqueous solutions. The device consists of two photonic crystal (PhC) fiber-tip sensors: one measures the ethanol concentration via refractive index (RI) changes and the other one is isolated from the liquid for the independent measurement of temperature. The probes utilize an optimized PhC design providing a Lorentzian-like, polarization-independent response, enabling a very low imprecision (pm-level) in the wavelength determination. By combining the information from the two probes, it is possible to compensate for the effect that the temperature has on the concentration measurement, obtaining more accurate estimations of the ethanol concentration in a broad range of temperatures. We demonstrate the simultaneous and single-point measurements of temperature and ethanol concentration in water, with sensitivities of 19 pm/°C and ∼53 pm/%, in the ranges of 25 °C to 55 °C and 0 to 50% (at 25 °C), respectively. Moreover, a maximum error of 1.1% in the concentration measurement, with a standard deviation of ≤0.8%, was obtained in the entire temperature range after compensating for the effect of temperature. A limit of detection as low as 0.08% was demonstrated for the concentration measurement in temperature-stable conditions.
我们展示了具有温度补偿功能的光纤传感器,用于精确测量水溶液中的乙醇浓度。该装置由两个光子晶体(PhC)光纤尖端传感器组成:一个通过折射率(RI)变化测量乙醇浓度,另一个与液体隔离以独立测量温度。这些探头采用了优化的PhC设计,提供类似洛伦兹分布的、与偏振无关的响应,在波长测定中实现了非常低的不精确性(皮米级)。通过结合两个探头的信息,可以补偿温度对浓度测量的影响,从而在很宽的温度范围内更准确地估计乙醇浓度。我们展示了在水中同时进行温度和乙醇浓度的单点测量,在25°C至55°C和0至50%(在25°C时)的范围内,灵敏度分别为19 pm/°C和约53 pm/%。此外,在补偿温度影响后,在整个温度范围内浓度测量的最大误差为1.1%,标准偏差≤0.8%。在温度稳定的条件下,浓度测量的检测限低至0.08%。