Design And Mechanism Research Of Multichannel Fluorescent Fiber-optic Probe With Zero-cross-talk

This paper mainly introduces the working mechanism of a multichannelfluorescent fiber-optic probe with zero-cross-talk and made performance research.First, analyze the principle of this kind of probe from evanescent wave and coupling,and verify its theoretical feasibility. Then set up the experimental platform ofmultichannel fluorescent fiber-optic probe, discuss the incentive mechanism offluorescence signal, and determine the detect ability of this new fluorescentfiber-optic probe through experiment. Finally, use Hitachi F-2700fluorescencespectrophotometer and multichannel fluorescent fiber-optic probe to makequantitative and qualitative analysis of Fe³⁺concentration based on the fluorescencequenching from Fe³⁺to rhodamine6G. The main research content and achievementare listed as follows:1. A new kind of multichannel fluorescent fiber-optic probe with zero cross talk,which is based on the working principle of fluorescence fiber-optic probe viaexternal vertical excitation, is presented in this article. The transmission fibers ofboth kinds are consisted of incident fiber and reception fiber which are separatedfrom each other. Under working condition, the exciting light from incident fiberdirect drive the free droplet under test on the surface of reception fiber core. Theincident fiber can be various and connect to a excitation light source of specificwavelength as needed. The reception fiber has several channels for measurement,which can be used to place various kinds of free fluorescent drops at the same time.This research also classifies the transmission light in reception fiber, introduces theworking mechanism of fiber end face total reflection, analyses the contributionability of total output energy from different transmission light, and verifies thephenomenon that the detector won’t response to this model and cause end face totalreflection when the model spreads among different cladding sectors, especially forthe interval from air between drop and polymer to polymer. 2. A detection platform based on the multichannel fluorescent fiber-optic probewith zero-cross-talk via external vertical excitation is set up. Adjusting the relativespatial position between output end face of incident fiber and fiber core side wall ofreception fiber will cause the change of shape of fluorescent drop. After analysis andcompare of different fluorescence peak strength, the relative spatial position betweenincident fiber and reception fiber is confirmed when SNR of fluorescence signal ismaximum, that is the incident fiber lies upon the reception fiber. The existence offace total reflection mechanism is also proved via comparing the peak strength offluorescence signal when the reception fiber face is coated with or without matchingfluid. Finally, we analyze the independence of each channel’s detection performancebased on the alteration of fluorescence signal peak strength, concluding that thedetection performance won’t change according to the fluorescence drop under test,which means the noise interference of stray exiting light will be minimized.3.In the analysis experiment of Fe³⁺based on F-2700instrument platform, thefluorescence exciting spectrum of rhodamine6G can be obtained. The fact thatadding Fe³⁺into the rhodamine6G solution will engender fluorescence quenching isconfirmed through comparing the change of fluorescence signal strength before andafter adding the Fe³⁺into the solution, in which the wavelength of exciting light is532nm. When the ion concentration is0.01⁰.04mg/L, the D-value of strengthquenching and ion concentration shows good linear relation. The correlationcoefficient of linear regression equation is R2=0.9921. In the analysis experimentbased on multichannel fluorescent fiber-optic probe, the application feasibility of thenew fiber-optic probe is corroborated via comparing variation trend curve offluorescence peak strength under different Fe³⁺concentration.