Design and modelling of smart sensor dedicated for water pollution monitoring

The aim of the paper is to present the smart sensor dedicated for water pollution monitoring. It consists of the ISFET (H+ ion sensitive field effect transistor) sensor and analogue-digital converter. H+ sensor can be easily replaced by any other FET-based ion sensor. The need of suitable model creation is stressed. The model of ISFET sensor as well as A/D convereter and their implementation in VHDL-AMS is presented. Finally the results of mixed signal simulation in VHDL-AMS are shown. The analysis of the whole microsystem is performed taking into account the presence of other than hydrogen ions - so called disturbing ions in the measured solution. The analysis of the possibilities of implementation of the best possible kind of the analogue-digital converter was undertaken too. In the Department of Microelectronics and Computer Science the first approach to the ion identification from the matrix of ISFET/CHEMFET sensors was performed and considered. It uses the neural network for disturbing ion identification and estimation of their concentration.