Design and Fabrication of a Plastic-Free Antenna on a Sustainable Chitosan Substrate

The majority of wearable and flexible 5G and 6G devices are based on plastic substrates, that are harmful to the environment. Therefore, the development of sustainable and plastic-free radio frequency (RF) devices becomes a crucial issue. In this regard, we present a fully biocompatible Planar Inverted-F Antenna (PIFA), fabricated on a <inline-formula> <tex-math notation="LaTeX">$55 ~\mu \text{m}$ </tex-math></inline-formula>-thick chitosan substrate. Chitosan has a relative dielectric constant of 5. This antenna is working at 4.5 GHz in the sub-6 GHz band of the 5G spectrum. It has a very compact footprint of <inline-formula> <tex-math notation="LaTeX">$14\times23$ </tex-math></inline-formula> mm2 and a Specific Absorption Rate (SAR) of 0.41 W/kg. The prototype has been fabricated using an innovative fabrication protocol. A very good agreement between numerical and experimental results has been obtained. The measured realized gain is equal to 1 dBi at the resonant frequency. Our results demonstrate the suitability of chitosan as a dielectric substrate for the fabrication of plastic-free antennas and paves the way for the development of sustainable wearable devices for the Internet of Healthcare Things (IoHT) applications.