Compact silicon-based attenuated total reflection (ATR) sensor module for liquid analysis

Abstract. Infrared attenuated total reflection (ATR) spectroscopy is a common laboratory technique for the analysis of highly absorbing liquids and solids, variety ATR accessories FTIR spectrometers are available. However, rarely found in industrial processes, where compact, robust, cost-effective sensors continuous operation required. Here, narrowband photometers more appropriate than instruments. We show concept implementation compact Si-based module with four-channel microelectromechanical systems (MEMS) detector. Measurements liquid mixtures demonstrate suitability applications chemical industry. Apart from sapphire (for wavelengths below 5 µm) diamond (extending to far-infrared region), most materials elements do not have either high enough infrared transmission or sufficient mechanical stability be exposed process fluids, abrasive components, aggressive cleaning agents. using coatings on Si improves sensor surface. In addition, by proper choice incidence angle coating thickness, an enhancement absorbance theoretically expected demonstrated first experiments diamond-coated element.