Design and Simulation of a Flexible Graphene Sensor with Capacitive Coupling

This work presents the design of a flexible sensor functioning within a 1–3 GHz frequency range for agricultural applications. The sensor design utilizes capacitive coupling techniques to achieve a narrow bandwidth under 100 MHz, employing a coplanar waveguide (CPW) feeding mechanism. The narrow bandwidth is intended to capture frequency changes on a minimal scale, which indicates that the sensor has a very high sensitivity in detecting substances. The substrate is Polyethylene Terephthalate (PET) with a thickness of 0.135 mm, while the radiating material is graphene, exhibiting a conductivity of 8.81×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">^</sup>4 S/m for a dielectric thickness of 80 nm. The sensor design undergoes several stages of advancement. The simulation results indicate that the sensor functions at a frequency of 1.52 GHz, with a bandwidth of 46 MHz, aligning with the specified targets. The S11 value is acceptable, measuring below -20.406 dB.