Surface plasmon resonance based fiber optic sensor for the detection of low water content in ethanol

A fiber optic sensor utilizing surface plasmon resonance (SPR) has been fabricated for the detection of low content of water in ethanol. The sensor utilizes spectral interrogation technique for operation. The resonance wavelength has been found to vary linearly with water content in the range 0–10% with sensitivity of 1.149 nm per percentage of water. The results are in agreement with the refractive index variation of ethanol–water mixture. The sensor has a water resolution of 0.145% which is better than the evanescent wave absorption sensor reported for the similar study. The sensor will find application in determining the low water content in ethanol which is used as a bio-fuel and in the field of medicine and organic chemistry.