Dual-Printed Soil Sensors for Nitrate and Moisture Monitoring

Printing electronics has been identified as a key manufacturing scheme for enabling low-cost, high-volume sensors. These printed sensors can allow for data acquisition within industries transitioning to data-informed decision-making. One such industry is agriculture, where soil data can inform decisions to increase crop yield while protecting the environment. In this work, we demonstrate a novel, dual-printed multi-functional soil sensor that can detect nitrate levels in saturated soil while also quantifying the moisture level. The nitrate sensor utilizes an electrochemical approach and can detect nitrate values from 5 to 400 mg/L within a saturated silt loam soil. The moisture sensor uses capacitance proximity sensing to measure the moisture of the soil based on changes in the dielectric permittivity and was able to measure moisture in sandy soil ranging from 0.1 to 0.25 m3/m3. The dual-printed sensor is expected to allow for quantifiable nitrate leaching when placed in a distributed manner through multiple direct nitrate and moisture measurements.