Highly sensitive graphene oxide leaf wetness sensor for disease supervision on medicinal plants

Plant disease prediction plays a pivotal role to abate the crop loss. For this purpose, early disease prediction models have been explored, where information about leaf wetness duration (LWD) is one of the important factors. The leaf wetness duration is measured with the help of leaf wetness sensors (LWS). Here, the LWS is fabricated on the polyamide flexible substrate where graphene oxide (GO) is used as the sensing film to detect the water molecules on the leaf canopy. Fabricated GO LWS has been tested under laboratory conditions, we exposed the entire sensing film with water molecule and we observed that it offers response of about 45000 % with respect to the air. Subsequently, observed response time of the fabricated sensor is around 400 s with recovery time of about 100 s. Further, the fabricated sensor shows only 2 % change in the response when exposed to the temperature ranging from 20 0C to 65 0C. Under field conditions, to explore the efficacy of the fabricated LWS, we benchmarked the LWD measured using the GO LWS with commercial LWS (Phytos 31). We have deployed the fabricated GO LWS along with Phytos 31 on the Tulsi (Ocimum tenuiflorum) medical plant. The on-field testing of the GO LWS indicates that maximum difference in LWD value using fabricated GO LWS and Phytos 31 is around ± 30 min.