Thin Film Technology Center, National Central University, Taoyuan 320317, Taiwan.
Optical Sciences Center, National Central University, Taoyuan 320317, Taiwan.
Sensors (Basel). 2021 Nov 16;21(22):7615. doi: 10.3390/s21227615.
The SPR phenomenon results in an abrupt change in the optical phase such that one can measure the phase shift of the reflected light as a sensing parameter. Moreover, many studies have demonstrated that the phase changes more acutely than the intensity, leading to a higher sensitivity to the refractive index change. However, currently, the optical phase cannot be measured directly because of its high frequency; therefore, investigators usually have to use complicated techniques for the extraction of phase information. In this study, we propose a simple and effective strategy for measuring the SPR phase shift based on phase-shift interferometry. In this system, the polarization-dependent interference signals are recorded simultaneously by a pixelated polarization camera in a single snapshot. Subsequently, the phase information can be effortlessly acquired by a phase extraction algorithm. Experimentally, the proposed phase-sensitive SPR sensor was successfully applied for the detection of small molecules of glyphosate, which is the most frequently used herbicide worldwide. Additionally, the sensor exhibited a detection limit of 15 ng/mL (0.015 ppm). Regarding its simplicity and effectiveness, we believe that our phase-sensitive SPR system presents a prospective method for acquiring phase signals.
SPR 现象会导致光学相位发生突然变化，因此可以将反射光的相移作为传感参数进行测量。此外，许多研究表明，相位变化比强度更剧烈，从而对折射率变化的灵敏度更高。然而，由于光学相位的频率很高，目前还无法直接测量，因此研究人员通常不得不使用复杂的技术来提取相位信息。在本研究中，我们提出了一种基于相移干涉测量的简单有效的 SPR 相位测量策略。在该系统中，偏振相关干涉信号可以通过像素化偏振相机在单个快照中同时记录。然后，可以通过相位提取算法轻松获取相位信息。实验中，成功地将所提出的基于相位的 SPR 传感器应用于检测全球使用最广泛的除草剂草甘膦小分子。此外，该传感器的检测限为 15ng/mL（0.015ppm）。鉴于其简单性和有效性，我们相信我们的基于相位的 SPR 系统为获取相位信号提供了一种有前途的方法。
