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We report the design of a silicon chip dedicated to the in-situ monitoring of soil nitrogen cycle in wheat crop. Our study shows that ion-sensitive field effect transistor (ISFET) microsensors are suitable for quick on-site or long-term analysis of nutrients measured directly in soil as opposed to soil extracts analysis. Our pH-ISFET recorded soil pH for six months with results in good accordance with standard sampling method and without any loss of sensitivity. The adaptation of pH-ISFET in pNO3 and pNH4-ISFET allowed, for the first time, the in-situ measurements of natural variations of soil nitrogen contents caused by microorganisms’ activity

We present a sensor platform associated to silicon-nanowire chemical field effect transistors (Si-nw-ChemFET). Innovations concern the use of networks of suspended silicon N+/P/N+ nanowires as conducting channel, the realization by thermal oxidation and Atomic-Layer Deposition (ALD) of a SiO2/Al2O3 gate insulator all-around the silicon nanowires, and their final integration into covered SU8-based microfluidic channels. The Si-nw-MOSFET/ChemFET fabrication process and electrical/electrochemical characterizations are presented. The fabrication process did not need an expensive and time-consuming e-beam lithography, but only fast and “low cost” standard photolithography protocols. Such microdevice will provide new opportunities for bio-chemical analysis at the micro/nanoscale.