Advances in design and construction of leaf wetness sensors

The majority of fungal infections are caused by leaf wetness, due to excessive humidity, mist, rain or irrigation. Leaf wetness duration (LWD), the total number of hours per day in which water is present on the foliage, can be monitored through a leaf wetness sensor (LWS). In this paper, an innovative procedure to manufacture a precise, low power and low cost electronic sensor is proposed to provide a tool for agronomic exploitation. The measurement subsystem consists of a two-side capacitive leaf wetness sensor, where a water presence varies the dielectric constant of the surrounding medium. The data acquisition subsystem exploits a capacitance-to-digital converter. Experimental results in controlled and real environments confirm reliability.