Organic vapor optical fiber sensors based on silk fibroin transduction

We report results on the development of an optical fiber long period grating sensor for organic vapor monitoring. A silk fibroin ovelayer with a thickness of the order of 400 nm is drop casted on the fiber cladding surface to enable sensing of volatile organic compound vapors. For increasing methanol vapor pressure up to 100 mbar the wavelength of the long period grating attenuation band exhibits a negative shift up to a maximum value of 4 nm. The strength of the grating attenuation band is also altered reaching a 0.27 dB strength decrease under the same maximum methanol vapor pressure. Furthermore, the recovery behavior of the sensor is presented and preliminary results of the response of the sensor to isopropanol and ethanol vapors are briefly discussed.