Abstract
Extreme weather conditions due to climate change are drastically calling for crop health supervision in agriculture via suitable technologies able to wirelessly, distributively, and sustainably monitor relevant parameters. In this work, we present a wireless, eco-friendly capacitive humidity sensor tag, fabricated via dispense printing on biodegradable paper. The device consists of an near-field communication (NFC) antenna made of biocompatible silver ink and an interdigitated electrode (IDE) sensor using biodegradable carbon ink. The sensor and antenna response to humidity was evaluated in a climatic chamber, showing a strong correlation and sensitivity to increasing and decreasing relative humidity (RH) values. The antenna was designed and characterized to resonate at the NFC frequency of 13.56 MHz. In addition, the encapsulation of the entire device was evaluated, showing minimal variation in the antenna response while enhancing the average sensitivity (0.63% /% RH) and stability of the RH sensing. Placed near a plant, this eco-friendly wireless device can estimate crop drought stress and support optimal water resource utilization while minimizing environmental impact, thereby paving the way for sustainable agricultural practices.