Study On VOCs Sensing Characterization Of Graphene Oxide Film Coated SP-SMS Fiber

Graphene oxide is a kind of two-dimensional material with high refractive index and strong adsorption capacity of VOCs.Graphene oxide not only has large surface area,but also has oxygen-containing functional groups which promotes the formation of hydrogen bonds.These characteristics make graphene oxide exhibit potential value for VOC gas sensing.VOC gas can do serious harm to indoor environment,because of it's inflammable and toxic hazards,indoor VOC concentration is an important indicator of indoor environmental pollution detection,many countries have laws and regulations of indoor pollution control of VOCs.Because of the architectural coatings,paints,cosmetics,plastic products,and so on,indoor VOC concentration will increase.Nowadays,the VOC gas concentration detections are usually complicated and cumbersome.Therefore,a kind of online rapid detection of VOC gas sensor research is of great importance.In this paper,considering the adsorption ability of graphene oxide,SMSF refractive index sensing characteristics and film coated D-shaped fiber enhanced evanescent field,we made a graphene oxide coated SP-SMS for VOC gas sensing,which can respond to a variety of VOCs and show high sensitivity.The main results are as follows:(1)We proposed a Side-Polished Single mode-Multimode-Single mode(SP-SMS)structure,the optical sensing properties of the structure were studied by Rsoft simulation.We found that the device is sensitive to surround refractive index.Moreover,the core diameter and polishing depth of SP-SMSF have an influence on the sensitivity of surrounding refractive index.(2)We prepared the SP-SMS fiber.The SP-SMSF was fabricated by the side polishing technology.The sensitivity of SP-SMSF was measured by using the refractive index standard.When the polishing depth was 20.6?m,the refractive index sensitivity of was 65nm/RIU in the refractive index range of 1.33-1.39,148nm/RIU in 1.39-1.43 and 1190nm/RIU in 1.43-1.45.(3)SP-SMS fiber can response to ethanol,methanol,acetone,formaldehyde and ether vapor.When the gas concentration rise,the transmittance spectrum of SP-SMSF exhibits blue shift,and the peak intensity decreases.The maximum sensitivities are 27pm/ppm,1pm/ppm,2pm/ppm,5.3pm/ppm,5.6pm/ppm for ethanol,methanol,acetone,formaldehyde,respectively.(4)We prepared graphene oxide coated SP-SMS fiber firstly.The optical sensing properties of the fiber were studied by Rsoft simulation.We found that GSP-SMS fiber is sensitive to the change of the refractive index of graphene oxide film.(5)GSP-SMS fiber can respond to ethanol,methanol,acetone,toluene,formaldehyde,ammonia,ether,chloroform and carbon tetrachloride.When the ambient temperature is 20?,the maximum sensitivity are 17.9pm/ppm,2.3pm/ppm,5.3pm/ppm,7pm/ppm,2.2pm/ppm,3.5pm/ppm,15.7pm/ppm,2.9pm/ppm,4.8pm/ppm for ethanol,methanol,acetone,toluene,formaldehyde,ammonia,ether,chloroform and carbon tetrachloride,respectively.Comparing the response of SP-SMSF with GSP-SMSF,it is found that graphene oxide film can improve the response speed and the response sensitivity expect ethanol.For ethanol,when temperature was increased from 20? to 28?,the response speed and recovery capacity of GSP-SMSF were improved.