Silk Fibroin Enabled Optical Fiber Methanol Vapor Sensor

An optical fiber long period grating coated with silk fibroin is proposed and demonstrated for monitoring methanol vapors. Results show an exponential increase in the wavelength shift of the grating's attenuation band versus methanol vapor pressure, while reaching a value of 4 nm for 100 mbar of methanol. Results are reported on the repeatability of the response of the sensor and show that after multiple exposures to methanol vapors the overlayer retains its functionality 12 days after drop casting.