Fabrication And Applications Of Optofluidics System Based On Plasmonic Refractive Index Sensors

Surface plasmon resonance(SPR)is a phenomenon that creates by collective oscillations between incident light waves and surface electron waves of metal nanostructures.The SPR effect can manipulate light at nanometer scale that breaks the optical diffraction limit,enhance the local(near-field)electromagnetic field by orders of magnitude,and be extremely sensitive to the dielectric environment.Thus it is widely used in many research fields such as physics,chemistry,biological environment and materials.Among them,refractive index sensors are one of the most important applications of SPR.The optofluidics system based on SPR refractive index sensors refers to a composite device that combines the detection method of SPR sensing with the microfluidic channels.So the optofluidics system not only has the advantages of high sensitivity and good universality of SPR refractive index sensing,but also integrates the functions of sample injection,mixing,exchanging,reacting and analyzing of the microfluidic channels.As a result,high efficiency,high throughput and in-situ detection can be realized.But at the same time,this composite device puts forward new requirements for “SPR sensing” and “microfluidic channels”.Firstly,how to obtain the SPR refractive index sensing chip with excellent performance.Secondly,how to select and optimize the material of the sensing chips,so as to achieve a stable combination of the sensing chips and the microfluidic channels.Thirdly,how to fictionalize the sensing chips according to the needs of the actual detection system.Finally,how to realize the miniaturization,integration,high throughput and low sample consumption detection using the optofluidics sensing system.To address the above scientific and technical problems,this thesis aims at the development and application of the high performance SPR optofluidics refractive index sensing system.The main researches are listed as follows:(1)Using the self-made holographic lithography technology and angle-resolved spectroscopy system,the SPR chips for refractive index sensing were prepared and optimized.Then the bonding of the sensor chips and the microfluidic channels were explored to form the optofluidics detection system.The obtained SPR optofluidics refractive index sensing system has a good stability.(2)The effects of structural parameters on the half-peak width of the SPR mode are systematically explored,and the influence of half-peak width on sensitivity and figure of merit(FOM)is further studied.The present work shows that the FWHM of the resonance peak was continually broaden when increasing the feature size of the scatter of the SPR sensing chips.In the meantime,the sensitivity would increase first and then decrease.Such a result is owing to the resonance mode and EM field enhancement.When the FWHM was under 20 nm,the resonance mode was unchanged while the EM field enhancement was increased with the increasing FWHM.However,the resonance mode would be changed when the FWHM exceeded the certain range(above 20 nm),and resulting in a subsequent decrease in the sensitivity.As a final result,the FOM value continued to decrease with the increase of FWHM.Therefore,the present work provides theoretical guidance for further researches of SPR sensing in practical applications.(3)Important progress in the development of miniaturized instrument has been made.The miniaturization detection device with length,width and height of 50 mm,30.21 mm and 40 mm respectively was obtained.The miniaturized optofluidics sensing devices will play an important role in portable and rapid detections.(4)Using the developed high performance SPR optofluidics refractive index sensing system,the deposition process of polydopamine(PDA)on the surface of metal nanostructures is in situ monitored in real time.On the one hand,the excellent performance of the sensing system is verified.On the other hand,the effect of PDA deposition on sensing performance is explored,so as to optimize the deposition conditions.Finally,the modified sensing chip is applied to the detection of biomolecules.