利用淀积在玻璃衬底上的金银合金薄膜作为表面等离子体共振(SPR)芯片, 构建了Kretschmann结构的近红外波长检测型SPR传感器. 采用不同浓度的葡萄糖水溶液测试了金银合金薄膜SPR传感器的折射率灵敏度. 实验结果表明随着入射角从7.5°增大到 9.5°, SPR吸收峰的半高峰宽从292.8 nm 减小到 131.4 nm, 共振波长从 1215 nm蓝移到 767.7 nm, 折射率灵敏度从35648.3 nm/RIU 减小到 9363.6 nm/RIU.在相同的初始共振波长(λR)下获得的金银合金薄膜SPR折射率灵敏度高于纯金膜(纯金膜在λR=1215 nm下的折射率灵敏度为29793.9 nm/RIU). 利用1 μmol/L的牛血清蛋白(BSA)水溶液测试了传感器对蛋白质吸附的响应.结果表明, BSA分子吸附使得金银合金薄膜SPR吸收峰红移了12.1 nm而纯金膜SPR吸收峰仅红移了9.5 nm. 实验结果还表明, 在相同λR下, 金银合金薄膜SPR吸收峰的半高峰宽大于纯金膜的半高峰宽, 因此其光谱分辨率比纯金膜SPR传感器低.
Au-Ag alloy films deposited on the glass substrates are used, for the first time, as a wavelength-interrogated near infrared surface plasmon resonance (SPR) sensor. The values of resonance wavelength (λR) of the sensor at different angles of incidence are determined by absorptiometry and its refractive-index (RI) sensitivity is investigated using aqueous glucose solutions as the standard RI samples. As the incident angle increases from 7.5° to 9.5°, the SPR absorption peak shifts from λR = 1215 nm to 767.7 nm, the full width at half magnitude (FWHM) of the peak reduces from 292.8 nm to 131.4 nm, and the RI sensitivity decreases from 35648.3 nm/RIU down to 9363.6 nm/RIU. At the same initial λR, the SPR sensor with the Au-Ag alloy film shows a higher sensitivity than that with the pure Au film (S = 29793.9 nm/RIU at λR=1215 nm with a pure Au film). Adsorption of bovine serum album molecules from the aqueous solution of 1 μmol/L protein results in a redshift of ΔλR = 12.1 nm with the Au-Ag alloy film and ΔλR=9.5 nm with the pure Au film. The experimental data also indicate that the FWHM of the SPR absorption peak with the Au-Ag alloy film is larger than that at the same λR with the pure Au film, leading to a lower spectral resolution than that of the latter.