Flexible Wearable Antenna for IoT-Based Plant Health Monitoring

In recent years, the rapid development of wireless technologies has led to the widespread adoption of the Internet of Things (IoT) in various fields. One of the fastest-growing segments of IoT is the "smart" wearables sector. In the next few years, the development of flexible plant-wearable devices that can provide vital information about the physiological characteristics of plants will be essential to support the faster growth of precision agriculture. We propose a small (overall size & Oslash;35 mm x 0.8 mm), ultra-lightweight (0.4 g), and elegant-shaped antenna for unobtrusive integration on a plant surface for application in IoT-based precision agriculture at ISM 2.45 GHz band. The radiating element has a design that resembles a dragonfly, making the antenna visually unnoticeable. We used ZZ Plant leaves as the substrate for the antenna and transparent polymer foil for encapsulating the conductive parts, achieving a highly flexible, waterproof, and chemically resistant antenna for application in harsh environments. The obtained results indicate that the antenna is resilient to changes in substrate relative permittivity up to +/- 20%. It exhibits high radiation efficiency (between 26% and 40%) and omnidirectional patterns across the ISM 2.45 GHz band. Moreover, the measured results align reasonably well with the simulated ones.