Planar waveguide enzyme sensor array for water pollution monitoring

The proposed sensor is based on SiO₂/Si₃N₄ planar waveguide having a sensing window coated with electro-statically self-assembled film containing pH sensitive organic chromophore molecules and different enzymes: urease, acetyl- and butyryl-cholinesterase. The sensor is capable of registration of enzyme reactions as well as their inhibition by traces of some typical water pollutants, such as heavy metal ions Cd²⁺, Pb²⁺, and Ni²⁺, and pesticides Imidacloprid, PVDP, and Paraoxon. A portable prototype sensor array set-up comprises 630 nm fan-beam laser diode, semi-cylindrical lens, planar waveguide with three-channel cell attached, and CCD array photodetector. Dedicated software was developed for CCD image processing and further data analysis with artificial neural network. The prototype sensor array provides both the recognition of water pollutants and evaluation of their concentration in a wide range from 10 ppm down to 1 ppb.