Highly Sensitive and Stable CeLaCuO/Ni-BTC MOF-Based Humidity Sensor for Plant Monitoring
Jolina Rodrigues, Karthik Chimatahalli Santhakumar, Hamid Nawaz, Swati Singh, Smruti Medha Mishra, Dalaver H. Anjum, Kyriaki Polychronopoulou, Nouha Alcheikh
Abstract
High Resolution Image Download MS PowerPoint Slide Herein, we report a high-performance humidity sensor based on oxygen-vacancy-rich CeLaCuO integrated with a porous Ni-BTC metal–organic framework (MOF). Compared with the single CeLaCuO and Ni-BTC sensors, the CeLaCuO/Ni-BTC composite sensor exhibits a higher response value (24% @ 32% relative humidity (RH)), lower hysteresis (0.465%RH), faster response/recovery time (24.5/47.8 s), and enhanced long-term stability (<2.6% over 60 days). Moreover, it achieves a high sensitivity of S ≈ 1.35/%RH with excellent linearity ( R 2 = 0.9868) across 11–63% RH and demonstrates a very low temperature cross-sensitivity between 25 and 100 °C (<0.35%). These improved performance properties are attributed to abundant oxygen vacancies (Ov) in the CeLaCuO structure that provide active sites for water adsorption and H + /H 3 O + species generation for fast ionic conduction. The high-surface-area Ni-BTC framework enhances water uptake and facilitates efficient charge transfer at the oxide–MOF interface. The lab-fabricated composite sensor also demonstrates real-world applicability in a microclimate chamber for monitoring the microclimate surrounding the Fragaria ananassa (strawberry) plant, where lower humidity (<60%) can cause plant stress and reduce yield. The proposed sensor placed on the plant shows a good response for various humidity levels at 43%, 51%, and 63% RHs, respectively. Moreover, the results show that, at 63% RH, plants exhibited optimal transpiration, allowing efficient water and nutrient uptake, resulting in healthy leaf morphology with minimal stress. Thus, the proposed sensors hold strong potential as next-generation real-time humidity sensors with practical applications in agriculture, smart greenhouses, environmental monitoring, and indoor climate control.