Design, prototyping, and characterization of laser-induced graphene antennas on flexible substrates: consolidating current knowledge

Laser-induced graphene (LIG) is a widespread technology for the manufacturing of low-cost and eco-friendly sensors that can be also exploited for the fabrication of conductorless antennas and RF devices for the personal and industrial Internet of Things (IoT). In this case, additional issues must be accounted for, such as the much larger lasing area, the moderate conductivity of LIG, and the durability versus environmental and mechanical conditions in real applications, but also new opportunities to provide antennas with nonconventional features. This article provides a unitary representation of the state-of-the-art knowledge for the modeling, design, fabrication, and testing of LIG-based antennas at some frequencies of IoT systems. The reader will find information about the selection of materials, how to configure the laser parameters to minimize the sheet resistance, and how to account for the moderate conductivity in numerical solvers. The upper bound performances are identified and related to the optimal antenna size. As IoT devices include sensors, the integration with the antenna can benefit from nonuniform lasing to dump unwanted RF currents on the sensor while preserving the communication capability. Finally, the immunity of LIG antennas to external stimuli is reviewed to quantify the expected degradation of performance. This tutorial hence provides a multidisciplinary background to activate a new research line, as well as to conduct experiments with the new concept of antennas engraved on substrates.