Graphene/Au/MIP-Coated D-Shaped Optical Fiber–Based SPR Sensor for Ethanol Detection

In this article, an optical bio-chemical sensor based on D-shaped optical fiber is presented for ethanol detection application. The gold and graphene nanolayers are coated for inducing the SPR over an optical fiber flat surface. The molecularly imprinted polymer (MIP) thin film is also coated over the gold film to enhance the molecular interaction between the sensing fluid and the sensing surface. The ethanol concentration is detected with reference to the 0% concentration and increased to 90% in a sample solution. The shift in resonance wavelength detects the concentration of the ethanol in the fluid sample due to the change in RI. The result shows a very good agreement between the concentration of ethanol in fluid and the resonance wavelength (RW) shift. The maximum obtained average sensitivity is 2.5 nm/concentration (every 10%) or 714 nm/RIU with Au/MIP thin film and 1137 nm/RIU for graphene/Au/MIP thin film. Based on the result and optical properties of the proposed sensor, it might be used as a real-time alcohol detector. This sensor can protect foods and drinks from the imbalance of chemicals and preservatives.