基于纳米锥森林结构的表面增强拉曼散射透明器件研究

具有无损、超灵敏和实时检测优点的表面增强拉曼散射(SERS)器件具有重要研究意义。目前,针对SERS器件的大部分研究都围绕着非透明的器件展开。使用此类器件检测高浓度试剂时,激光只能从正面入射。这意味着入射激光需要穿透被测试剂分子层才能到达位于其下方的金属纳米结构表面,因此用于激发金属纳米结构表面等离子体共振(SPR)的激光能量被减弱,相应地,SERS光谱信号也被减弱;此外,SERS光谱信号因被测试剂分子层的遮挡,无法高效返回到电荷耦合元件(CCD)中,再次被大幅度减弱,甚至有可能完全无法被检测到。相比之下,如果使用透明SERS器件,检测过程中将被测试剂分子置于器件正面,激光从器件背面入射,此时高浓度被测试剂分子层对入射激光和SERS光谱信号的干扰最小。这种情况下,可以得到较好的光谱信号。通过在石英基底上旋涂聚酰亚胺(PI)层,然后通过氧等离子体对PI层进行无掩模轰击,在石英基底上自行生成纳米纤维掩模,配合反应离子刻蚀工艺(RIE)制备了石英纳米锥森林结构。之后,通过金属纳米颗粒溅射工艺,得到SERS透明器件。对于该SERS透明器件,在测试过程中,拉曼激光可从器件的正面以及背面分别入射。初步的测试结果表明,对于罗丹明6G(R6G)在10^-3~10^-6 mol·L^-1这一浓度范围内,背面入射方式收集的SERS光谱信号强度高于正面入射方式。另外,进一步研究了该SERS透明器件背面检测的一致性,得到了良好的结果,证明了其在实际生化检测中的可行性。这一工作有望扩展SERS在分析物检测领域中的应用。

Surface-Enhanced Raman Scattering Transparent Devices Based on Nanocone Forests

Surface-enhanced Raman scattering(SERS)devices with advantages of being non-destructive,ultra-sensitive,and real-time are of significance.For now,most SERS devices are constructed on non-transparent substrates.When such non-transparent SERS devices are used to detect analytes with high concentrations,laser can only be incident from their front-sides.It means that incident laser needs to penetrate analyte molecules to reach metallic nanostructures at the bottom,so laser energy used to excite surface plasmon resonance(SPR)of metallic nanostructures is attenuated,and accordingly,SERS spectral signals are also attenuated;besides,SERS spectral signals cannot be efficiently returned to the charge-coupled device(CCD)due to the blocking of analyte molecules,so that the signals are greatly reduced and in some cases,they cannot be detected at all.In contrast,when a transparent SERS device is adopted,the analyte molecules are placed on front-side of the device and Raman laser is incident from the back-side.In this way,analyte molecules with high concentration have minimal influence on incident laser and SERS spectral signals,so better spectral signals can be obtained.In this work,a polyimide(PI)layer was spin-coated on a quartz substrate,and then the substrate was bombarded by oxygen plasma without masks.After that,nanofiber masks were formed on the quartz substrate.Later on,quartz nanocone forests were formed by a reactive-ion-etching(RIE)step.Subsequently,metallic nanoparticles were sputtered on the nanocones,thus,a transparent SERS device was obtained.For this SERS transparent device,Raman laser can be incident from front-side and back-side of the device during the test.The preliminary experimental results showed that for Rhodamine 6G(R6G),in a concentration range of 10^-3~10^-6 mol·L^-1,the SERS spectra from the back-side were with higher intensities than those from the front-side.In addition,repeatability of the device detected from the back-side was further studied.These results demonstrated the feasibility of the device in practical biochemical detection applications.This work is expected to extend the applications of SERS technique in the field of analyte detections.