Determining the Composition of 100 Nano-Liter Fuel Mixture in a Silicon Micro-Cuvette Using Ultraviolet Absorption Spectroscopy

Silicon microfabrication technology was employed in the generation of a cavity in the form of a truncated inverted pyramid with very smooth sidewalls and a silicon dioxide UV transparent optical window at the bottom. This can be used as a micro-cuvette for testing of fluids. 100nl fluid volumes can be tested using this platform by ultraviolet absorbance spectroscopy employing a deuterium lamp and an UV spectrometer. Mixtures of commercially sourced diesel with ethanol, and diesel with kerosene were tested in this work. Two zones of interest were identified in the absorption spectrum of diesel. For a 0 to 10% diesel in ethanol mixture, a clear shift of the UV absorption edge from 297nm to 336nm was observed. For the diesel in kerosene mixture a linear shift of the absorption edge from 335nm to 365nm was observed for the entire composition range. Our results indicate that a single wavelength source and detector at 345nm is sufficient to determine the diesel in kerosene composition using this micro-cuvette, which would be very useful in detection of adulteration in fuels. [2020-0344]