Experimental Investigation of Leaf Wetness Sensing Properties of MoS2 Nanoflowers Based Flexible Leaf Wetness Sensor

Abstract

To abate crop loss, it is important to explore the plant disease management systems, where leaf wetness sensors (LWS) are widely used. The leaf wetness duration (LWD) extracted from the LWS is related to plant diseases. In this work, we have fabricated the LWS on the polyamide flexible sensor to explore the leaf wetness sensing mechanism, where Molybdenum disulfide (MoS2) is used as the sensing film. Further, we have passivated the MoS2 with the help of acrylic protective lacquer (APL) conformal coating (MoS2+APL), which reduce the interaction of the water molecules with the sensor. Lab measurements indicated that fabricated LWS on the flexible substrate with MoS2 and MoS2+ APL as the sensing film offers a response of about ≈ 40,000% and ≈ 250%, respectively, at 500 Hz excitation frequency when the entire sensing area is filled with the water molecules. The response time of the MoS2 and MoS2+APL-coated flexible sensor is about 180 seconds. Fabricated LWS sensors offer hysteresis of about ± 4 % in wetness. Further, we have identified that oxidation of the Sulphur in the MoS2 plays an important role in the leaf wetness sensing mechanism. Further, we understood that MoS2 when passivated with APL coating, the oxidation effect is reduced and the sensor response is negligible.