基于金银合金薄膜的波长检测型表面等离子体共振传感器

Wavelength-Interrogated Surface Plasmon Resonance Sensor Based on Au-Ag Alloy Film

从实验和理论两方面详细研究了金银合金膜表面等离子体共振(SPR)传感器在可见光波段的敏感特性.实验方面,通过在玻璃基底上溅射50 nm厚的金银合金薄膜制备了一种新型的SPR传感芯片,并且自行搭建了基于Kretschmann结构的波长检测型SPR传感器测试平台.利用不同浓度的氯化钠(NaCl)水溶液和浓度为10μmol·L-1的牛血清蛋白(BSA)水溶液分别作为折射率样品和分子吸附样品,研究了传感器的折射率灵敏度和吸附灵敏度,并与金膜和银膜SPR传感器进行了对比研究.结果表明,对于折射率灵敏度的测试,金银合金膜SPR传感器大幅高于金膜SPR传感器,略低于银膜SPR传感器;而对于吸附敏感的研究,金银合金膜SPR传感器的灵敏度与银膜SPR传感器相近,是金膜SPR传感器的3倍.理论方面,利用菲涅尔公式和等效折射率计算公式仿真计算了这三种薄膜结构的SPR传感器的灵敏度和精确度,结果指出金银合金膜SPR传感器的灵敏度与银膜SPR传感器接近,是常规金膜SPR传感器的2.31倍,而半高峰宽仅为金膜和银膜SPR传感器的1.36倍.在稳定性方面,金银合金膜SPR传感器与金膜SPR传感器均具有良好的化学稳定性,而银膜SPR传感器较易氧化,使用寿命低,不常被采用.综上,金银合金膜在改善传感器灵敏度的同时,不会降低精度,是一种高灵敏、低成本、良好稳定性的SPR传感器敏感材料.

An Au-Ag alloy film surface plasmon resonance （SPR） sensor was studied experimentally and theoretically. SPR chips were prepared by sputtering a glass surface with a 50-nm-thick Au-Ag alloy film, and experiments were carried out with the wavelength-interrogated SPR sensor using the Kretschmann configuration. Aqueous sodium chloride and bovine serum albumin solutions were used to study the refractive index and adsorption sensitivities of the sensor. The results were compared with those obtained using Au film and Ag film SPR sensors. The refractive index sensitivity of the Au-Ag alloy film SPR sensor is higher than that of the Au film SPR sensor, but lower than that of the Ag film SPR sensor. The adsorption sensitivity of the Au- Ag alloy film SPR sensor is similar to that of the Ag film SPR, and three times of the Au film SPR sensor. Theoretical studies showed that that the sensitivity of the Au-Ag alloy film SPR is close to that of the Ag film SPR sensor, and 2.31 times of the Au film SPR sensor. The full width at half maximum of the Au-Ag film sensor is only 0.36 times of the Au or Ag film SPR sensors. The Au-Ag alloy film and Au film SPR sensors are chemically stable, but the Ag film SPR sensor is easily oxidized, so it is not often used. These results show that an Au-Ag alloy film can improve the sensitivity of the sensor, while retaining the accuracy. Au-Ag films could therefore be used as high-sensitivity, low cost, and stable SPR-sensitive materials.