In precision farming applications, developing polymer-based electrochemical sensors for non-invasive ion concentration monitoring in agricultural fluids has drawn more and more interest. For instance, sodium ion concentrations in soil can have a significant impact, and ion-selective field-effect transistors are commonly used to monitor sodium levels in agricultural settings. Among these, a developing trend in farming technology is the polymers manufacturing of sensors. To identify variations in sodium ion concentration in soil, we fabricated a polymer-based electrochemical sensor with two terminals. There is a channel area between two metallic contacts in the sensor fabrication. A functionalized polymer essential to the selective detection of sodium ions makes up this channel.