The Research On Preparation And Characteristics Of Flexible TiO₂ Microcavity For Optical Biosensing

Optical microcavity resonators have attracted the attention of researchers because of their high quality factor?Q?and high sensitivity?S?.The whispering gallery mode optical microcavity has been used in the field of biosensing and enables single molecule detection.However,microcavity structures are all fabricated on rigid substrates in the current reports on microcavities and no microcavity resonators have been flexibly integrated.This paper focuses on the preparation and characteristics of flexible TiO₂ optical microcavities,and lays a foundation for obtaining high performance flexible optical microcavity biosensors.The main work of this paper includes the following aspects:Firstly,the basic theory of flexible whispering gallery mode optical microcavity is introduced,including whispering gallery mode microring resonator model analysis and flexible microcavity realization principle.The performance indexes of whispering gallery mode optical microcavity biosensor are introduced,such as quality factor and sensitivity,limition of detect and FOM.Secondly,the structure and performance of the classical microring resonator are introduced.An asymmetric microring resonator structure is proposed.Through the asymmetric design of the microcavity structure and microcavity material,the quality factor Q of the microcavity is improved.A microring resonator structure with a local intermediate refractive index cladding layer is provided,and the sensitivity S is improved by adding a specific local intermediate refractive index cladding.Thirdly,a neutral and stable peroxo titanic acid?PTA?sol is prepared by using inorganic salt TiOSO₄ as raw material and hydrogen peroxide?H₂O₂?as complexing agent.The amorphous titanium dioxide film is prepared by spin coating method.The effects of sol concentration,spin coating speed,hot plate temperature and hot plate time on the thickness of TiO₂ film are studied.The microstructure and optical properties of TiO₂ film are studied influenced by annealing temperature and annealing time.The final optimal preparation conditions are obtained and provide material support for high sensitivity and biocompatible sensors.Fourthly,the flexible microcavity preparation process flow is established.The microcavity structure is designed by L-edit,and the electron transfer lithography and inductively coupled reactive ion etching are used to realize the shape transfer.The process conditions and precision of the flexible TiO₂ microcavity are strictly controlled.Finally,the flexible integration of the optical microcavity is realized.Finally,the optical properties and flexibility of the prepared flexible TiO₂microcavity are studied.The high-performance optical test platform is built and the corresponding components are introduced.The optical performance and flexural resistance of the flexible TiO₂ microcavity are studied by using the optical test platform.The results show that the flexible integrated optical microcavity still has a high quality factor Q and can withstand a certain degree of bending,which lays the foundation for the realization of flexible whispering gallery mode optical biosensing.