J Biomed Nanotechnol. 2020 May 1;16(5):715-720. doi: 10.1166/jbn.2020.2902.
Biomedical sensor that sense different molecules with a high refractive index sensitivity is proposed in this work. Plasmonic nanospiral antenna is mounted on a top surface of an optical fiber to reflect the incident optical signal back to the fiber. The reflected signal depends on the nanospiral antenna material, dimensions and the surrounding medium. Using streptavidin molecule, the nanospiral antenna have been simulated based on finite difference time domain method to optimize its dimensions. The optimum dimensions are 10 nm, 55 nm and 40 nm for inner-outer thicknesses and height respectively. The introduced biosensor can detect different molecules based on surface plasmonic resonance, which depends on the shifting of the peak wavelength according to the molecules type. The detected molecules are Streptavidin, Urease, Uricase molecules and Glucose oxidase and Cholesterol oxidase enzymes with a high sensitivity. The maximum refractive index sensitivity is obtained when sensing cholesterol oxidase molecules with 3028 nm/RIU at 3.58 m peak wavelength. Figure of merit and quality factor are also calculated for all detected molecules. Finally, electric field and optical power, before and after binding, of the reflected signal are illustrated and discussed.
本工作提出了一种具有高折射率灵敏度的生物医学传感器，可感应不同的分子。等离子体纳米螺旋天线安装在光纤的上表面，以将入射光信号反射回光纤。反射信号取决于纳米螺旋天线的材料、尺寸和周围介质。使用链霉亲和素分子，基于时域有限差分法对纳米螺旋天线进行了模拟，以优化其尺寸。最佳尺寸分别为内-外厚度为 10nm、55nm 和 40nm，高度为 40nm。所提出的生物传感器可以基于表面等离子体共振检测不同的分子，这取决于根据分子类型峰波长的移动。检测到的分子是链霉亲和素、脲酶、尿酸酶分子以及葡萄糖氧化酶和胆固醇氧化酶，具有很高的灵敏度。当感应胆固醇氧化酶分子时，最大折射率灵敏度为 3028nm/RIU，峰值波长为 3.58μm。还计算了所有检测到的分子的品质因数和品质因数。最后，说明了和讨论了反射信号的结合前后的电场和光功率。
