Development of a screen-printed thick-film nitrate sensor based on a graphite-epoxy composite for agricultural applications

The present report describes the development of a thick-film sensor with intended applications for soil analysis. A probe incorporates three sensors, each at a different depth and featuring a copper plate as the reference electrode. In addition, the probe also contains all necessary instrumentation required for processing the sensor signal and to transmit it via radio. The developed sensors were calibrated in situ using two different soil compositions by adding standard solutions. Results show a quasi-Nernstian response in soil, in response to the addition of fertilisers. Extracts of soil samples analysed by the Kjeldahl method were compared with results from the probe. This comparison confirms that the sensors are capable or measuring chemical parameters in situ in an automated fashion. (C) 2002 Elsevier Science B.V. All rights reserved.