Modelling of surface plasmon resonance sensor for detection of mass concentration of ethanol and methanol in a binary mixture

• Modelling of SPR sensor for detection of ethanol in water is presented.
• Overlayer refractive index and thickness limits the spectral operation range.
• Larger sensitivity is obtained by moderate value of refractive index and thickness of overlayer.
• A method for detection of ethanol content in water is discussed.

Modelling of a surface plasmon resonance sensor for detection of ethanol or methanol content in water is presented. The reflectivities of these sensors are derived using transfer matrix method and hence the corresponding sensitivity and detection accuracy are obtained in the presence of high index overlayer, like silicon and chalcogenide. It is observed that the resonant wavelength of surface plasmon resonance sensor is shifted toward higher wavelength with increase of refractive index and thickness of overlayer. Hence, by adjusting their values, the desired spectral operation range of this sensor is obtained. The sensitivity of this sensor with silicon overlayer is larger than the chalcogenide overlayer but at the same time detection accuracy is smaller. This sensor can be used to detect the mass concentration of ethanol, methanol and other similar materials. A method to obtain the percentage mass concentration of ethanol is discussed.