The Research On Micro- And Nano- Structure Enhanced SPR Imaging Sensing Technology

Surface Plasmon Resonance (SPR) sensing technology has been widely applied in the areas of biomedical science, drug screenging, environment monitoring and food safety for its merit of label-free, highly sensitive and real-time ability, and possibility to realize high-throughput. In recent years, high-througput detection using SPR imaging (SPRi) sensing technology has been developed quickly since the demand of high-througput biomolecule detection is rising, but the contrast of the image is poor, and sensitivity of SPRi is lower than conventional SPR. This thesis will focus on improving the performance of SPRi sensing technology. A high-performance SPRi sensor is designed, and a SPRi sensing platform is constructed. Based on the above work, the property of electromagnetic field in micro- and nano-structures is studied, and the field enhancement is proposed to improve the sensitivity of the SPRi sensor. Main contents and achievements of this thesis include:1. Parameters are optimized through simulations based on the polarization contrast method. A SPRi sensor is designed, and a SPRi sensing platform is established. Through some test, the refractive index resolution is 5.4 X×10-6 RIU, and the dynamic range is 1.3316-1.3553 RIU. Its performance has been improved when compared to conventional intensity SPRi sensors.2. The factors of using Au NPs to improve the sensitivity have been studied by FDTD simulations. Also, the property of electromagnetic field of Au and Ge periodic nanostructures has been studied and compared, and their underlying physics is explained, which make it a solid work for exploiting micro- and nano-structures to improve the performance of the SPRi sensor.3. The enhanced electromagnetic field caused by SPW in gold microwell structure is studied, and the parameters are optimized. Chips with gold microwell structure are fabricated. Through performance test, sensitivity is improved by over 157% by the gold microwell structure, and the refractive index resolution is improved to 1.7× 10-6 RIU,4 times better than planar gold film. BSA experiment proves the improvements.4. The enhanced electromagnetic field caused by LSPR-SPR coupling in gold gratings is studied, and the parameters are optimized. Gold gratings are fabricated inside the gold microwell structure to form a gold micro-nano structure. Through performance test, sensitivity is improved to 183% upon the improvement in gold microwell structure when the operating range is 1.3315-1.3394 RIU. MUA experiment proves the improvements.5. To improve the polarization contrast method, A novel extinction method is proposed, that is, to use thick gold film to realize background extinction. This method has merits of high-contrast, good sensitivity in small range of refractive index, background inert and easy to operate. Its potential to improve the performance of the SPRi sensor is poved by a preliminary test.Currently, the micro- and nano-structure enhanced SPRi sensor based on polarization contrast method can realize simutaneous determination of 25 spots. Compared to planar gold film, its sensitivity can be improved by 287% in small refractive index range of 1.3315-1.3394 RIU, and the best resolution of refractive index can be 1.7× 10"6 RIU. It shows potentials of high-throughput and high-sensitivity.