Printed Sensors for Continuous Monitoring of Soil and Plant Conditions

High spatial density monitoring of the environment is essential for improving the understanding and management of natural systems. This is of particular importance in soils, where sensing can help to enable optimization of agricultural inputs, increase carbon storage, reduce greenhouse gas emissions, and enhance soil health. Print-based manufacturing of electronic systems allows for the fabrication of large numbers of unconventional sensors that utilize a wide range of materials that are compatible with natural environments and can facilitate the capture of useful, high-density information. In this talk, two examples of environmental sensing using printed electronic devices will be described 1) direct sensing in soil and 2) integration of sensors with plant tissues. For soil sensing, various sensors have been studied including those to monitor moisture content, conductivity, temperature, pH, ion concentrations, and microbial activity. In the case of integrating sensors both in and on plant tissues, printed biosensors that incorporate organic electronic materials into highly biocompatible hydrogels formed through a freeze-thaw cycling approach will be discussed.