3.3 - Photometric Micro Measuring Sensor for Real-Time Water Analysis

Abstract

The measuring sensor is a micro-fluidic cell for real-time water analysis. It can be optimized for different application fields depending on their expected contamination grade in the ppm (parts per million) to ppb (parts per billion) area. The cell finds its implementation especially in agricultural and environmental monitoring. It was integrated in a device called Quicklyzer for continuous measuring of soil water. The detection combines the principle of absorption and fluorescence spectroscopy. So different substances like nitrate, nitrite and humic acid can be measured in one device. The specialty is the nanotechnological liquid core waveguide which is formed with semiconductor structuring techniques. It has a surface with best homogeneity, with an optical wall roughness of 10nm +/-2nm. Samples can be measured over long distances on a small size, e.g. a cell with a length of 2.8m integrated on 6'' silicon substrate. The channel must be coated with a total internal reflection layer that leads to light guiding along the measuring path. In the fluorescence measurement cell a total internal reflection coating is needed to ensure light guiding of the fluorescence signal. The coating must also be transparent for the excitation light that is coupled into the cell. A new coating material is investigated. The Quicklyzer system is a compact, portable, online measuring tool, that can be used with a 12V power supply to take it to the field. It replaces cost and time consuming offline laboratory measuring systems, like inductively coupled plasma mass spectrometry, High-performance liquid chromatography and gas chromatography.