Nanoporous silicon microcavity based optical sensor to detect adulteration of petrol by organic solvents

Adulteration of petrol by organic solvents is rampant across the globe. Here we present a novel sensor to detect adulteration of petrol by three organic solvents, namely toluene, xylene and benzene. The sensor is a nanoporous silicon microcavity structure that is sensitive to the variations in the refractive index of the fuel samples. The several useful properties of porous silicon such as its simple fabrication process, high sensitivity, compatibility with silicon microelectronics, room temperature operation, very high surface-to-volume ratio and biocompatibility make it a popular candidate for sensing applications. The primary objective of this work is to develop a novel porous silicon microcavity sensor that is capable of detecting the adulteration of petrol by the aforementioned organic solvents. This is achieved by the change in the reflectance spectrum of the microstructure when different concentrations of adulterated fuel samples are introduced in its pores, as a distinct red shift is produced for each concentration. The same sensor is utilized for sensing the adulteration by the three organic solvents. The sensing process was found to be reversible and hence the sensor is reusable.