Polymer Waveguide Biosensor Based On Localized Surface Plasmon Resonance Of Gold Nanoparticles

In recent years,optical biosensor have achieved rapid development due to their high sensitivity,fast analysis speed and accurate result.Optical waveguide biosensor is one of the most popular research objects in this field,because it has wide application prospect in food safety,environmental testing and medical diagnosis.The common structures of optical waveguide biosensor include straight waveguide,bent waveguide,micro-ring waveguide,and MZI waveguide.The straight waveguide needs to be combined with precious metal nanoparticles to have a higher sensitivity.Fabricating micro-ring waveguide needs the high-resolution photolithography machine or even the electron beam lithography.Fabricating MZI waveguide requires the secondary photolithography.The bent waveguide has high detecting sensitivity,its preparation process is simple and the cost is relatively low,so it has a relatively broad market prospect.In this paper,the polymer straight waveguide sensor and the polymer S-shaped bent waveguide sensor based on Localized Surface Plasmon Resonance(LSPR)effect of gold nanoparticles were studied.The sensors were analyzed and studied from three aspects:material synthesis,device fabrication and performance testing.The main work completed in this paper is as follows:1.A gold nanoparticle solution was prepared by sodium citrate reduction method and its particle size was about 40 nm.The absorption peak of the solution was measured at 532 nm and the sensitivity to NaCl solution of different concentrations was 0.11 ?A/RIU.2.The sensing theories of polymer straight waveguide and polymer S-shaped bent waveguide were studied.Polymer straight waveguide and polymer S-shaped bent waveguide were designed.The bent radius and the length of I/O straight waveguide of S-shaped bent waveguide were determined as 800 ?m and 0.9 cm.The binding conditions of gold nanoparticles and polymer waveguide were explored.The microfluidic channel was fabricated by using PDMS film and I-shaped acrylic plate structure,and it was integrated with the waveguide.The leakage of water in the microfluidic channel and the coupling problem in optical path testing were solved.3.A polymer straight waveguide sensor with gold nanoparticles was prepared.For different concentrations of NaCl solution,the detecting sensitivity and the linearity of the sensor were 2.8 ?A/RIU and 0.9925.The detecting limit of the sensor for human IgG solution was 0.1 ?g/mL.When the detecting range was 10 ?g/mL-50?g/mL,the detecting result of the sensor was nonlinear.In order to study its selection specificity,rabbit IgG,sucrose,NaCl,BSA and AFP solutions were injected into the sensor,respectively.The results showed that the sensor had a good selectivity.4.A polymer S-shaped bent waveguide sensor with gold nanoparticles was prepared.The S-shaped bent waveguide with gold nanoparticles was compared with the S-shaped bent waveguide without gold nanoparticles.The results showed that the sensitivities of the sensor with and without gold nanoparticles were 11.27 ?A/RIU and 14.74 ?A/RIU,respectively.Their linearities were 0.98891 and 0.99194,respectively.Compared to the polymer straight waveguide with gold nanoparticles,their sensitivities increased by 4 times and 5.3 times,respectively.The detecting limit of the sensor for human IgG solution was 1 ?g/mL.When the detecting range was 10?g/mL-50 ?g/mL,the detecting result of the sensor was linear,its linearity was 0.99083.In order to study its selection specificity,rabbit IgG,sucrose,NaCl,BSA and AFP solutions were injected into the sensor,respectively.The results showed that the sensor had a good selectivity.