Jang Daeho, Chae Geunhyoung, Shin Sehyun
School of Mechanical Engineering, Korea University, Seoul 136-701, Korea.
College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-476, Korea.
Sensors (Basel). 2015 Sep 30;15(10):25385-98. doi: 10.3390/s151025385.
The present study introduces a novel curve-fitting algorithm for surface plasmon resonance (SPR) curves using a self-constructed, wedge-shaped beam type angular interrogation SPR spectroscopy technique. Previous fitting approaches such as asymmetric and polynomial equations are still unsatisfactory for analyzing full SPR curves and their use is limited to determining the resonance angle. In the present study, we developed a sigmoid-asymmetric equation that provides excellent curve-fitting for the whole SPR curve over a range of incident angles, including regions of the critical angle and resonance angle. Regardless of the bulk fluid type (i.e., water and air), the present sigmoid-asymmetric fitting exhibited nearly perfect matching with a full SPR curve, whereas the asymmetric and polynomial curve fitting methods did not. Because the present curve-fitting sigmoid-asymmetric equation can determine the critical angle as well as the resonance angle, the undesired effect caused by the bulk fluid refractive index was excluded by subtracting the critical angle from the resonance angle in real time. In conclusion, the proposed sigmoid-asymmetric curve-fitting algorithm for SPR curves is widely applicable to various SPR measurements, while excluding the effect of bulk fluids on the sensing layer.
本研究采用自行构建的楔形光束型角度询问表面等离子体共振（SPR）光谱技术，介绍了一种用于SPR曲线的新型曲线拟合算法。以往的拟合方法，如非对称方程和多项式方程，在分析完整的SPR曲线时仍不尽人意，其应用仅限于确定共振角。在本研究中，我们开发了一种S形非对称方程，该方程能在一系列入射角范围内，包括临界角和共振角区域，对整个SPR曲线提供出色的曲线拟合。无论主体流体类型（即水和空气）如何，当前的S形非对称拟合与完整的SPR曲线几乎完美匹配，而非对称和多项式曲线拟合方法则不然。由于当前的曲线拟合S形非对称方程可以确定临界角和共振角，通过实时从共振角中减去临界角，排除了主体流体折射率引起的不良影响。总之，所提出的用于SPR曲线的S形非对称曲线拟合算法广泛适用于各种SPR测量，同时排除了主体流体对传感层的影响。
