Highly sensitive screen-printed soil moisture sensor array as green solutions for sustainable precision agriculture

Monitoring soil moisture in real-time is an important parameter that helps farmers decide to enhance agriculture productivity and reduce resource wastage for better production and plant growth. In this work, we presented an easy-to-use and highly sensitive screen-printed flexible soil moisture sensor array to monitor soil moisture remotely for precision agriculture. The proposed sensor is based on a unique interdigitated electrode (IDE)-based capacitive structure with conductive carbon ink printed on a flexible polyethylene terephthalate (PET) substrate using the screen printing technique. Before soil moisture monitoring, the sensor is tested for humidity monitoring in an environmental chamber. A response of ∼144–1760 pF for 20–100%RH with 10%RH variation is observed for a single sensor, while an array configuration ranges from ∼127–1802 pF. The sensor response is observed for a temperature range from 20 to 50 ‘C. The sensor's sensitivity for relative humidity sensing is 19.123%pF/RH, and the response and recovery time are ∼3.3 s and ∼4.2 s. Further, the sensor is tested for soil moisture sensing, as moisture content is gradually added to the completely dry soil. A highly sensitive response for soil moisture content (MC) with a ∼40.7%pF/MC sensitivity is obtained. The sensor data is transmitted wirelessly using a Bluetooth module. The sensor is supported by a wooden stick, which illustrates the capabilities of biodegradability, the sensor is cost-effective and provides a real-time measurement for soil moisture. The sensors have the potential to provide maintenance-free monitoring, facilitating precise control of irrigation practices in precision agriculture. With their affordability and ability to operate on a large scale, the sensor offers promising opportunities for enhancing irrigation systems.