Novel All-Solid-State Soil Nutrient Sensor Using Nanocomposite of Poly(3-Octyl-Thiophene) and Molybdenum Sulfate

Nitrate is a major macronutrient for plant growth. There is a high demand to develop robust, reliable, and maintenance-free soil sensors for long-term monitoring of nitrate variations in field. An ion-selective membrane-based solid-state nitrate sensor is developed using poly(3-octyl-thiophene)-molybdenum disulfide nanocomposite as an ion-to-electron transducing layer. The sensor offers a high sensitivity of 64 mV/decade, a dynamic range of 1–1500 ppm NO3--N, and an improved selectivity for nitrate detection in soils. The sensor has demonstrated the ability to continuously monitor soil nitrate concentrations over a period of four weeks.