Miniaturized Soil Sensor for Continuous, In-Situ Monitoring of Soil Water Potential

This paper presents a miniature embedded sensor for direct, in-situ, continuous monitoring of soil water potential variations during the growth of plants. The sensor has a small form factor due to the seamless integration of an ultra-shallow water reservoir, a nanoporous ceramic disk, and a miniature optical displacement detection unit. By increasing the hydrophilicity and smoothness of the inner surface of the water reservoir, a high cavitation pressure was obtained. The sensor makes it possible to conduct continuous, in-situ measurement of soil water potential near the roots of plant for almost two weeks.