Biological And Chemical Sensor Based On Optical Microfiber With Functional Coatings

Fiber biochemical sensor has the advantages of anti-electromagnetic interference,miniature size and on-line detection,and so on.It has potential application in many fields such as clinical medicine,pharmacy,bioengineering,food industry,process control,environmental monitoring and military becoming become a hot research in recent years.With the development of nanotechnology research,new functional materials and devices are being discovered and produced,and new vitality has been explored for the development of fiber biochemical sensors based on novel biochemical sensitive principles and sensitive materials.In this paper,the microfiber interferometer as the sensing unit,the refractive index changes into optical interference signal spectral drift,to achieve the detection of biomass and chemical quantity.In order to improve the sensitivity and adaptability of biochemical fiber sensors,we propose to combine different functional coatings with fiber optic sensors.The article mainly includes the following two aspects:The graphene oxide film was modified on the surface of the microfiber interferometer,and interaction mechanism between graphene and DNA molecules in different pH conditions has been studied.The oxidized graphene can interact with the single-stranded DNA through the ?-? stacking effect,and such interaction can exist in a certain p H range.Based on this,the oxidized graphene functionalized microfiber interferometer was employed to realize the ability of detecting single-stranded DNA in the range of pH 4.3-8.5(human body pH enviroments).The sensor shows high sensitivity versus single-stranded DNA concentration and the detection limit reaches to 10-12 M.With compact and sensitive properties,the sensor can be applied in the detection of single-stranded DNA in complex environments,complementing the existing means of detecting single-stranded DNA.Single-stranded DNA aptamer has been modified on the surface of microfiber interferometer to selectively capture silver ions.The single-stranded DNA probe containing abundant cytosine has a special binding ability to silver ions and undergo conformational transformation,causing the change in the refractive index of the interferometer surface and converting it into the drift of the interference signal.Based on this,the detection limit of the sensor reaches to 1.36 × 10-9 M and response time is less than 10 min,providing a potential for real-time and in-situ analysis of silver ions in real matrix.