Study of chemical field effect transistors for the detection of ammonium and nitrate ions in liquid and soil phases

The development of ChemFET-based sensors for the soil analysis nitrogen-based ions is described in this work. Focusing on fluoropolysiloxane (FPSX) polymer-based matrix, nonactin and tetradodecylammonium nitrate (TDDAN) were shown to have best properties detection ammonium NH4+ NO3- respectively. Thus, FPSX-based pNH4-ISFET pNO3-ISFET microsensors exhibited good (sensitivity around 56 mV/pX concentration ranges adapted analysis) acceptable selectivity main interferent (K+, Na+, Ca2+, Cl-, H2PO42-, SO42-,…). Following, two different ISFET applied in-situ analysis. using standard relative moistures, pH clay-silt matrixes was demonstrated a six-month period (compatible with agriculture applications during fertilization period). Then, experimental studies successfully extended monitoring nitrogen mineralization through pNH4 measurement, as well nitration processes. Finally, long-term analyses performed, showing contradictory result according chosen ionophore: "zero" temporal drift PFSX-based pNH4-ISFET, huge TDDAN pNO3-ones. This work paves way future ionic matrix.