Application Of Waveguide-Microcavity Coupling Structure In Fluorescence Detection

Fluorescence sensing has excellent optical properties,as well as high sensitivity,convenient detection methods,and fast response.It has been widely used in biological monitoring,disease diagnosis,drug analysis,bioimaging,and chemical analysis.Optical micronanofluidics is a rapidly developing branch of fluidics,and major developments in the field of fluorescence sensing based on micro-nanofluidics have significantly expanded the application range of microsensors.Fluorescence detection of micro-nanofluids can be based on fluorescence imaging of fluorescence emission or by reading the emitted fluorescence intensity of fluorescent labels.For both methods,their low cost,high resolution and high sensitivity of fluorescence signal detection as well as fluorophore-labeled The broad spectrum makes the method of combining fluorescence with micro-nanofluidics the most important means in biology,chemistry,medicine,biotechnology,drug detection and environmental monitoring.Among them,the efficient detection of fluorescent nanoparticles in micro-nanofluids has become more and more important in the fields of medicine,biology,chemistry and other fields.How to efficiently detect and track nanoparticles in micro-nanofluids is still a problem to be solved.Therefore,based on the reading of the fluorescence emission intensity of the nanofluorescent marker in the fluid,high-precision detection of the nanoparticles in the micro-nano fluid can be realized.In this paper,two waveguide-microcavity coupling structures are proposed for the reading of the fluorescence emission intensity,and the research on the detection of nanoparticles in micro-nanofluids by these structures is systematically studied.The main contents are as follows:The first research work is to propose a waveguide-concentric ring resonator structure,through which the displacement monitoring of fluorescent nanoparticles in micro-nanofluids is realized.First,we studied the effect of fluorescent nanoparticles on the fluorescence output power under different polarization states;then,we studied the influence of factors such as the width of the upper waveguide of the structure,the material refractive index of the structure,the spacing of concentric and resonant cavities on the fluorescence output power of the structure.;Finally,the effect of fluorescent nanoparticles moving in the range of 0-1000 nm on the fluorescence output power was investigated.The final results show that when the fluorescent nanoparticles move in the range of 0-1000 nm in the structure proposed in this chapter,the detection and tracking of the nanoparticles can be realized according to the change of the peak value of the fluorescence output power.This research work has certain guiding significance for the development of particle detection in micro-nanofluids.The second research work is to propose a waveguide-resonator coupling structure through which micro-displacement monitoring of fluorescent nanoparticles in micro-nanofluids can be realized based on ratiometric fluorescence.This work is a further study on the basis of the first work.Since the detection efficiency of traditional fluorescence emission intensity is relatively low and easily affected by background noise,we propose to use ratio fluorescence that is insensitive to background noise to realize the detection of fluorescence nanometers.Microdisplacement monitoring of particles.First,we also studied the effect of different polarization states of fluorescence on the ratio of fluorescence output power;then we studied the effects of structural parameters,refractive index in the nanofluidic channel,the distance between two ring resonators and other factors on the ratio of fluorescence output power of the structure;Finally the effect of fluorescent nanoparticles moving in the 0-100 nm range on the ratio of fluorescence output power was investigated.The final results show that when the fluorescent nanoparticles move in the range of 0-100 nm in the waveguide-microcavity coupling structure proposed in this chapter,the micro-displacement of the nanoparticles can be detected with high precision according to the change of the ratio of the fluorescence output power.This research work has extensive application value in the fields of microfluidics detection,fluid particle analysis,and biological monitoring.