Study Of The Polymer-based Optical Waveguide Microring Biosensor

Based on planar waveguides, microring resonator with high quality factor offers a unique advantage of reducing the device size without sacrificing the sensitivity by virtue of the resonance. Polymers are emerging as an important material in the field of integrated optics. As the polymer materials are compatible with several simple fabrication processes, the cost of the optical devices is expected to be lowered down to meet economic criteria. Moreover, the molecular structure of the materials can be designed to fit some application requirements. Therefore, polymer-based optical micoring resonator biosensor is highly sensitive, that has a small size and can detect minute amount of analytes and be fabricated at low cost.We have studied the polymer-based optical waveguide microring resonator biosensor and the results are listed as follows:The transmission characteristics of microring resonator are analyzed by optical waveguide and couple-mode theory. Theoretical method is established, from which expressions of key parameters such as λm, FSR, ΔλFWHM, Q and ER factor are derived. The operating principle of the microring resonator biosensor is also studied.The polymer microring resonator based on PSQ-Ls material is designed. The design includes different kinds of several racetrack microring resonators for biosensing which operates at1550nm and850nm. Double-ring resonator (DRR) is investigated to expand FSR as compared with single-ring resonators. Through optimizing the waveguide width, the radius of the ring and the coupling length, the microring resonator with the smallest trip loss and high sensitivity can be obtained.The soft-lithography fabrication technology of polymer is introduced. The approach that couples receptor molecules to the polymer surface is investigated. The actual microfluidic fabrication is introduced and the microfluidics modeling techniques are also discussed. A stamp-and-stick method to transfer the channels on the waveguide chip is described.High-precision optical testing platform is set up to satisfy the requirement of device testing. Comprehensive testing procedure is established. Performance of device is measured, which shows quality factor up to38,000. Detection sensitivity of42nm/RIU and detection limit of2.382×10-5RIU are demonstrated by sensing various concentrations of sodium chloride solution. Finally, surface sensing are performed with IgG (human Immunoglobulin G) and PA (Staphylococcal protein A) as an affinity model. The measured results verify the feasibility and validity of the proposed polymer waveguide microring as a label-free biosensor.