Miniature Multisensor Probe for Soil Nutrient Monitoring

Abstract

We present a multisensor probe containing four ISFET (Ion Sensitive Field Effect Transistor) sensing elements aiming at the real time monitoring of nutrients in the soil. A miniature solid-state reference electrode is integrated with the probe, which renders the probe resistant against prolonged periods of drying. The sensing elements inside the probe are selective towards K+, NO3-, H2PO4- as well as pH. Our measurements show, that the probe can identify the specific ions at concentrations as low as 10-5M (for K+), with a sensitivity of 33mV/decade for NO3-, 48mV/decade for K+ and 55mV/decade for pH.