Soil Potassium\nSensor Using a Valinomycin-Decorated\nReduced Graphene Oxide (rGO-v)-Based Field-Effect Transistor for Precision\nFarming

A precise measurement of soil potassium (K) concentration\nis crucial\nfor enhancing agricultural productivity and promoting sustainable\nland management. The efficiency of real-time soil quality monitoring\nis hampered by the time-consuming laboratory analysis that is commonly\nassociated with conventional methods. The present research introduces\nan innovative approach utilizing a field-effect transistor (FET) structure\ncoated with reduced graphene oxide-decorated valinomycin (rGO-v) for\nthe detection of potassium ions in soil samples. The sensor exploits\nthe distinctive electrical properties of reduced graphene oxide (rGO)\nand the specific affinity of valinomycin for potassium ions. To construct\nthe device, we applied rGO-v onto an FET substrate. The conductance\nof the FET can be modified by the interaction between valinomycin\nand potassium ions, enabling the detection of potassium ions. Some\nof the advantages of this technology are its high sensitivity, fast\nresponse time, and potential for miniaturization. In addition, the\ndevice is tuned to demonstrate an enhanced sensitivity of 0.98 μA/(kg/ha)\nbelow the threshold voltage. The sensor exhibits a response time of\n40 s and demonstrates exceptional stability in the face of unfavorable\nconditions, specifically humidity. Therefore, valinomycin-decorated\nreduced graphene oxide, when subjected to appropriate gate bias, demonstrates\npromising results as a versatile, cost-effective, and easy-to-use\npotassium ion sensor.